CA1330349C - Igcc process with combined methanol synthesis/water gas shift for methanol and electrical power product - Google Patents
Igcc process with combined methanol synthesis/water gas shift for methanol and electrical power productInfo
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- CA1330349C CA1330349C CA000595444A CA595444A CA1330349C CA 1330349 C CA1330349 C CA 1330349C CA 000595444 A CA000595444 A CA 000595444A CA 595444 A CA595444 A CA 595444A CA 1330349 C CA1330349 C CA 1330349C
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- Prior art keywords
- methanol
- gas
- carbon monoxide
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- reactor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K23/00—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids
- F01K23/02—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled
- F01K23/06—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle
- F01K23/067—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle the combustion heat coming from a gasification or pyrolysis process, e.g. coal gasification
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/15—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively
- C07C29/151—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively with hydrogen or hydrogen-containing gases
- C07C29/1516—Multisteps
- C07C29/1518—Multisteps one step being the formation of initial mixture of carbon oxides and hydrogen for synthesis
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J2300/00—Details of gasification processes
- C10J2300/16—Integration of gasification processes with another plant or parts within the plant
- C10J2300/164—Integration of gasification processes with another plant or parts within the plant with conversion of synthesis gas
- C10J2300/1643—Conversion of synthesis gas to energy
- C10J2300/165—Conversion of synthesis gas to energy integrated with a gas turbine or gas motor
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J2300/00—Details of gasification processes
- C10J2300/16—Integration of gasification processes with another plant or parts within the plant
- C10J2300/164—Integration of gasification processes with another plant or parts within the plant with conversion of synthesis gas
- C10J2300/1656—Conversion of synthesis gas to chemicals
- C10J2300/1665—Conversion of synthesis gas to chemicals to alcohols, e.g. methanol or ethanol
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J2300/00—Details of gasification processes
- C10J2300/16—Integration of gasification processes with another plant or parts within the plant
- C10J2300/1671—Integration of gasification processes with another plant or parts within the plant with the production of electricity
- C10J2300/1675—Integration of gasification processes with another plant or parts within the plant with the production of electricity making use of a steam turbine
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/16—Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/16—Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
- Y02E20/18—Integrated gasification combined cycle [IGCC], e.g. combined with carbon capture and storage [CCS]
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Engine Equipment That Uses Special Cycles (AREA)
Abstract
ABSTRACT
The present invention relates to an improvement to a process for the production of methanol from synthesis gas containing carbon monoxide and hydrogen utilizing a three phase or liquid-phase reaction technology.
The improvement to the process is the addition of relatively small amounts of water to the liquid-phase reactor thereby allowing for the use of a CO-rich synthesis gas for the production of methanol by effectuating in the same reactor the methanol synthesis and water-gas shift reactions.
The present invention relates to an improvement to a process for the production of methanol from synthesis gas containing carbon monoxide and hydrogen utilizing a three phase or liquid-phase reaction technology.
The improvement to the process is the addition of relatively small amounts of water to the liquid-phase reactor thereby allowing for the use of a CO-rich synthesis gas for the production of methanol by effectuating in the same reactor the methanol synthesis and water-gas shift reactions.
Description
~ 330349 IGCC PROOE SS WITH COMBINED METHANOL SYNTHESIS/WATER GAS SHIFT
FOR METHANOL AND ELECTRICAL POWER PRODUCTION
TECHNICAL FIELD
The present inv2ntion relates to an integrated gasification combined cycle ~IGCC) process. More specifically, the present invention relates to an improvement which converts a portion of the produced, CO-rich synthesis gas to produce a crude methanol product for peak-shavinq.
AC~GROUND OF T~E INVENTION
Methanol is produced from synthesis qas (syngas), a mixture of hydrogen (H2), carbon monoxide (CO), and carbon dioxide (CO2). The stoichiometry of the methanol synthesis reactions indicates that the desired molar reactor feed composition is given by the equation:
R = (H2-CO2~/(CO+CO2) = 2-0 However, reaction kinetics and system control dictate that the optimum ratio is actually R = 2.1 or higher. Gas with R = 2.0 to 2.1 is called "balanced" gas, i.e. balanced stoichiometrically, and has a typical com~osition of 19% CO, 5% CO2, 55% H2, and 21% CH4-N2.
Syngas is commonly made by the reforming of methane or other hydrocarbons, which gives a hydrogen-rich gas well-suited for methanol synthesis (e.g., a typical methanol syngas produced by steam reforming of methane has a composition of 15~ CO, 8% CO2, 73% H2, 4% CH4-N2, R=2.8). Currently 70 to 75% of the world's methanol comes from reformed natural gas, however, because of the instability of the oil market, liquid hydrocarbons and natural gas are not always readily available or available at an inexpensive cost. An alternative and abundant resource is coal, which can be converted to syngas in a coal gasifier such as the advanced, high-temperature coal gasifiers developed by Texaco, Dow, Shell, and British Gas/Lurgi.
Coal-derived syngas can be used as gas turbine fuel in an integrated gasification combined cycle (IGCC) electric power plant. Because of the daily cyclical demand for power, a primary concern in such a facility is load-following flexibility. To accomplish this flexibility, either the 1 3303~q front end of the IGCC plant must be built for peak capacity, or extra fuel must be imported during peak periods tcalled peak shaving~. The former is an exeensive and inefficient option. The latter, although somewhat less expensive, can be improved by producing and storing the fuel on-site. One solution to this problem is the on-site production of methanol as the peak-shaving fuel.
In an IGCC facility without methanol coproduction, the syngas is combusted in a gas turbine to produce electricity. The turbine exhaust~stack gas is used to generate and superheat steam in an integrated heat recovery system, and this steam is also used to generate electricity. In a coproduction facility, the syngas is first passed through a methanol synthesis reactor to convert a portion to methanol;
the remaining syngas is fed to the gas turbine for power production. The methanol is stored as peak-shaving fuel, which is used to augment the feed to the gas turbine during periods of high power demand. This scheme is attractive because the load on a power plant varies over a wide range, and it is more economical to feed the stored methanol than to build peak-shaving capacity into the front end of the facility.
Unfortunately, coal-derived syngas from advanced gasifiers used in IGCC plants is CO-rich (e.g., a Texaco gasifier syngas has a typical comeosition of 35~ H2, 51% CO, 13% C02, 1% CH4-N2, R=0-34)~
unlike the hydrogen-rich syngas from reformed hydrocarbons. The problem is that converting this gas to methanol by conventional methods is exeensive and com~licated because several pretreatment stees are required ~ ;
to balance the gas prior to methanol synthesis.
Conceptual IGCC co~roduct plants have been designed with gas-phase and with liguid-phase methanol synthesis reactors. With a gas-phase reactor, the main syngas stream from the gasifier is divided into two parts: approximately 75% goes directly to the gas turbine, and the remaining 25~ goes to the methanol synthesis section. This }atter stream is further divided, a~proximately 67% being mixed with steam and sent to a high temperature shift reactor (HTS). After shift, the C02 is removed and this stream $S remixed with the unshifted stream and recycle gas in the methanol loop to give a balanced gas for methanol synthesis.
Purge gas from the recycle loop and the rejected C02 from the C02 1 3303~9 removal section are sent to the gas turbine. The use of a conventional, gas-phase methanol synthesis reactor in an IGCC coproduct scheme is subject to the same shortcomings as in a gas-phase all-methanol product plant: a shift section and CO2 removal section are required in order to achieve a feed gas composition with an "R" value greater than 2.0, shift and methanol synthesis are performed in separate vessels, and the conversion per pass is limited by temperature constraints.
The liquid-~hase methanol process has an advantage over gas-phase methanol synthesis in a coproduct configuration because of its ability to }0 directly process CO-rich gas ~e.g., "~" values between about 0.30 and 0.40). The entire C0-rich gas stream from the gasifier is sent through the liquid-phase reactor in a single pass, achieving 10-20~ conversion of CO to methanol. While additional methanol can be produced by balancing the gas prior to feeding it to the liquid-phase methanol reactor, the value of this incremental methanol is outweighed by the cost of separate shift and CO2 removal units. ~ecause a liquid-phase methanol reactor operates isothermally, there is no increasing catalyst temperature and the accompanying constraint on methanol conversion which is characteristic of gas-phase methanol synthesis processes. In a typical liquid-phase design, approximately 14~ of the CO (feedgas "R" = 0.34) i5 converted to methanol, giving a reactor effluent containing approximately 9% methanol: the per pass conversion in a gas-phase reactor generally results in a reactor effluent containing only 5% methanol even though the ;~
feedgas has an "R" greater than 2Ø It should be noted, however, that even with the superior performance of the liquid-phase reactor, the coproduction scheme can still be expensive, and there is incentive to improve this processing route.
A somewhat similar coproduction scheme is also worthy of mention ~;
~U.S. Pat. 3,986,349 and 4,092,825). This scheme involves converting coal-derived syngas into liquid hydrocarbons via Fischer-Tropsch synthesis, separating the hydrocarbons from the unreacted gas, feeding the gas to a gas turbine to generate electric power, and using at least part of the hydrocarbons as peak-shaving fuel. Although methanol is mentioned as a possible by-product of the hydrocarbon synthesis, it is not one of the desired products.
SUMMARY OF THE INVENTION
The present invention is an improvement to an integrated gasification combined cycle (IGCC) electric power plant process. The IGCC process converts hydrocarbon fuels in a gasifier producing a CO-rich synthesis gas, which in turn is combusted in a gas turbine to produce ~ower. The IGCC process also includes a provision for production of methanol from the CO-rich synthesis gas prior to combustion as a supplemental fuel, which can be used to peak-shave. Methanol is produced by reacting at least a eortion of the CO-rich synthesis gas in the presence of a methanol synthesis catalyst.
The improvement for increasing methanol productivity from the same amount of synthesis gas is the combination of the water/gas shift and methanol synthesis reactions in a single step by reacting the carbon monoxide-rich synthesis gas with water in the presence of a catalyst in a liquid-phase reactor thereby producing both a crude methanol product and a reduced carbon monoxide content and increased hydrogen and carbon dioxide content synthesis gas. The produced reduced carbon monoxide content and increased hydrogen and carbon dioxide content synthesis gas is suitable for combustion in a gas turbine.
The ~ater added to the liquid-phase reactor can be beneficially introduced as a liquid. The catalyst in the liquid-phase reactor can be any appropriate methanol synthesis catalyst or a mixture of a methanol synthesis catalyst and a low temperature shift catalyst. The catalyst concentration in the liquid-phase methanol reactor can be in the range from about 5 to about 50 weight percent. The improvement to the process of the present invention is particularly suited to C0-rich synthesis gases having an R value less than 2Ø
The present invention also comprises several further processing steps. Among these are (1) processing at least a portion of the reduced carbon monoxide and increased hydrogen and carbon dioxide synthesis gas in, for example, a membrane unit or a pressure swing adsorber (PSA) u~it to separate the reduced carbon monoxide and increased hydrogen and carbon dioxide synthesis gas into a hydrogen-rich component and a carbon monoxide-rich component, both components comprising hydrogen, carbon dioxide and carbon monoxide, and recycling the hydrogen rich component to 1 ~30349 the inlet of the liquid-phase reactor; and (2) processing at least a portion of the reduced carbon monoxide and increased hydrogen and carbon dioxide synthesis gas in, for example, a membrane unit or a pressure swing adsorber tPSA) unit to separate the reduced carbon monoxide and increased hydrogen and carbon dioxide synthesis gas into a hydrogen-rich component and a carbon monoxide-rich component, both components comprising hydrogen, carbon dioxide and carbon monoxide, combining the hydrogen-rich component and a portion of the unprocessed synthesis gas (i.e., the gas not processed in the membrane or PSA units) into a single methanol reactor feed stream, optionally removing at least a portion of the carbon dioxide from the gas-phase methanol reactor feed stream, -reacting the methanol reactor feed stream in a gas-phase reactor to i~
produce methanol, and combining the unconverted effluent from the gas-phase methanol reactor with the carbon monoxide-rich component from the membrane unit to form a gas turbine combustion fesd.
BRIEF DESCRIPTION OF THE DRAWING
Figure 1 is a plot showing the effect of water, expressed as molar H2O/CO ratio entering the liquid-phase methanol reactor, on methanol productivity and on the hydrogen content leaving the liquid-phase methanol reactor.
Figure 2 is a schematic diagram of an embodiment of the methanol synthesis and combustion turbine sections of an IGCC power plant according to the present invention.
Figure 3 is a plot of methanol productivity for a typical liquid-phase run without water addition.
Figure 4 is a plot of methanol productivity for a run with intermittent water addition.
Figures 5 and 6 are block flow diagrams for a simple once-through ~ -liquid-phase methanol IGCC process. Figure 5 shows the process without water addition and Figure 6 with water addition.
Figures 7 and 8 are block flow diagrams for a once-through liquid-phase methanol IGCC process with a membrane recycle. Figure 7 shows the process without water addition and Figure 8 with water addition.
1 ~30349 Figures 9 and 10 sho~ block flow diagrams for a once-through liquid-phase methanol IGCC process with a memorane unit and a gas-phase mPthanol synthesis loop. Figure 9 shows the process without water addition and Figure 10 with water addition. -DETAILED DESCRIPTION OF THE INVENTION
The present invention is an improvement to the methanol production step within an integrated gasification combined cycle process wherein methanol is produced for peak-shaving from CO-rich synthesis gas. The improvement to the process is the combination of the methanol synthesis ~;
and water-gas shift reactions in a single step in order to increase ~
methanol productivity. The improvement of the present invention replaces -the need to balance the synthesis gas in shift and CO2 removal steps prior to its conversion to methanol as would be required if a gas-phase ~ethanol synthesis process were used. The present invention is based on the fact that if water is added to the CO-rich syngas feed to a liquid-phase methanol reactor, the water-gas shift and methanol synthesis reactions will take place simultaneously. In fact, if no water is added the reverse water-gas shift reaction is known to take place in either liquid or gas-phase reactors. The addition of water simply forces the equilibrium in the forward direction (i.e., CO ~ H2O ~ H2 +
C2) Several advantages of the liquid-phase methanol reactor have already been mentioned. An additional advantage is seen when considering water addition. In contrast to conventional technologies, liquid water can be added directly to the liquid-phase reactor. This saves the cost of generating high-pressure process steam, and also reduces the net heat which must be removed from the reactor. A conventional gas-phase reactor cannot accept a liquid water feed because thenmal shock and rapid vaeorization can break up and destroy the catalyst tablets. In addition, water vapor which is added must be kept well above its dew point to prevent condensation and subsequent quenching of the bed due to its plug flow operation.
-1 ~303~9 Althouqh the addition of steam to a liquid-phase methanol reactor was considered in EPRI Report AF-1291 (December 1979, p. 5-3), wherein the conce~t is discussed, and laboratory data is presented for two syngas compositions, the data indicated that methanol productivity decreases as water is added. It was reported that water addition always reduces methanol productivity, especially for gases that already have the required H2~CO stoichiometry, and that for non-stoichiometric synthesis gases, the fall off in productivity with increasing steam/CO ratio is slower. -The experimentation behind the present invention, on the other hand, shows results which are surprising relative to those in the EPRI report.
Figure 1 shows the effect of water, expressed as the molar H2O/CO ratio entering the liquid-phase methanol reactor, on methanol productivity tmmol MeOH/hr-gm catalyst) and on the molar H2~CO ratio ta measurement lS of the extent of the water-gas shift reaction) leaving the liquid-phase methanol reactor. This graph illustrates two important points. First, the methanol productivity curve goes through a maximum, showing that water indeed can be used to boost methanol productivity. This maximum was not seen or even suspected in the data reported in EPRI Report AF-1291. Second, adding water increases the hydrogen content in the effluent. Although the CO2 produced from the shift reaction prevents a stoichiometrically balanced effluent, the proper amount of CO2 can be removed later to give a balanced gas, if desired. Thus, adding a precise amount of water results in increased methanol production relative to dry CO-rich gas feed as well as a notable production of H2 via the shift reaction. Adding more water results in increased H2 production at some sacrifice to methanol productivity.
The proposed IGCC coproduct plant flowsheet according to the present invention is shown in Figure 2. With reference to Figure 2, desulfurized CO-rich synthesis gas and water (liquid or vapor) are fed to the process via lines 1 and 3, respectively, combined, and fed to liquid-phase reactor 7 via line 5, wherein the synthesis gas and water react in the presence of a catalyst. Alternatively, the liquid water or steam, in line 3, can be added directly to reactor 7 without irst being combined with the synthesis gas. Liquid-phase methanol reactor 7 can be operated 1 3303~q in either a slurry or ebullatsd mode. In the case of the slurry mode, a -~
powdered methanol synthesis catalyst (e.g., CuO~ZnO/A1203) is slurried in a liquid medium (e.g light paraffinic or cycloparaffinic oils). Alternatively, a mixture of powdered methanol synthesis catalyst and low temperature shift catalyst can be used in reactor 7. The concentration of catalyst can range from about 5 to 50 wt%. In the case -of an ebullated mode, a granulated catalyst is fluidi~ed in a liguid - ~
medium. Liquid-phase reactor 7 operates within the conventional~ -understanding of a liquid-phase reactor.
The effluent removed via line 9 from liquid-phase reactor 7 is cooled in a series of heat exchangers, including heat exchanger 43, and subsequently separated in separator 11 into a liquid and vapor stream.
The primary purpose of separator 11 is to recover and recycle the liquid medium which was vaporized and entrained in the reactor effluent. The liquid stream is recycled via line 13 to liquid-phase reactor 7.
Additionally, to provide heat removal from reactor 7, a liquid stream is removed from the reactor via line 15, cooled and returned to reactor 7.
The vapor stream from oil separator 11 is removed via line 17, cooled in a series of heat exchangers so as to condense methanol and water in the stream and then fed to high pressure methanol separator 19.
The overhead from separator 19 is removed via line 21: this overhead is mainly unreacted synthesis gas, which is then reduced in pressure in expander 23 to recover power and subsequently fed to burner 49 via line 25.
The liquid phase from separator 19 is removed via line 27, reduced in pressure in J-T valve 29 and fed to low pressure methanol separator 31. In separator 31, dissolved synthesis gas in the methanol and water solution is removed as overhead via line 35 and fed as feed to burner 49. The bottoms of separator 31 is removed via line 33 as crude methanol ~ -product.
The above is a description of a once through methanol synthesis ~ `
portion of an IGCC process. The combustion portion of the IGCC cycle is as follows: As mentioned earlier, the unreacted synthesis gas from the methanol synthesis portion is fed to burner 49 via lines 25 and 35.
These streams are combusted in burner 49 along with fuel gas produced ~ ~
. ~ .
1 3303~q from the sulfur removal step of the gasifier portion of an IGCC facility (fed via line 81), compressed air and steam. The compressed air is introduced to the process via line 75, compressed in compressor 77 and introduced into the burner via line 79. Steam is produced and introduced into the burner through two heat sources. First, boiler feed water, in line ~1, is heated in heat e~changer 43 against the efflusnt, line 9, from liquid-phase reactor 7 producing steam in line 45. Second, boiler feed water, in line 61, is heated in heat recove.y unit 57 producing steam in line 63. These two steam streams, lines 45 and 63 are combined into stream 47 which is then fed to burner 49.
The combustion gas from burner 49 is fed to gas turbine e~pander 53 via line 51 for recovery of power and subsequently fed to heat recovery unit 57 via line 55. In heat recovery unit 57, energy is recovered from the expanded combustion gas by producing steam and sueerheating steam by 1~ heat exchange of the combustion gas with boiler feed water and saturatPd steam. A portion of the steam produced in heat recovery unit 57 is introduced as feed to burner 49. Ths remaining portion of steam, in line 67, which is produced from boiler feed water introduced via line 65, is e~eanded in turbine 69 producing both power and low pressure steam.
In the above description, stream 1 represents desulfurized C0-rich gas from a Texaco coal gasifier: stream 3 can be used to sueply water such that the combined streams (line 5) have a molar ratio of H20/C0 =
0.17. As shown in ~igure 1, this is approximately the ratio necessary to achieve the maximum methanol production. Stream 5 is fed to liquid-phase reactor 7, which typically operates at about 482F and 910 esia.
Reaction heat is removed in an external heat e~change loop which produces saturated steam. The reactor effluent is cooled by first producing steam, then by heat exchange with unreacted fuel gas, and finally with cooling water. The two-phase mixture is separated and the vapor is heated and expanded, producing electric power. This expanded fuel gas is then sent to the gas turbine burner. The condensed methanol is flashed to yield the crude methanol product and a residual gas stream which is also fed to the gas turbine burner. In addition to the main fuel gas and flash gas streams, the gas turbine burner also receives a fuel gas stream from the upstream sulfur removal elant (e.g., Sele~ol, Rectisol, Rectisol *Trsde mark ~ .uYr...,..: . ~
- - 1 3333~q II), sufficient steam from the process to control ~x production, and ~ -compressed air. These streams are fed to the combustion zone, which txpically operates at 2000F. The burner effluent expands across the ~as turbine expander, which produces electric power for export and for running the air compressor. The gas turbine exhaust is used to produce and superheat steam in an integrated heat recovery system. The steam subseguently powers steam turbines which produce additional electric power.
An IGCC coproduct plant without water addition has two principal modes of operation. During peak power demand times, all of the fuel gas and some stored methanol go to the gas turbine. During off-peak hours, gas flows through the liquid-phase reactor to convert a eortion of the gas to methanol for storage. With water addition, the methanol productivity per mass of catalyst is increased, which means that either the reactor can be downsized or additional methanol can be produced from a base-size unit. The plant has greater flexibility because it can operate in three modes: all fuel gas to the gas turbine, gas through the liguid-phase reactor without water addition, and gas through liquid-phase reactor with water added.
An additional, surprising benefit of water addition has been demonstrated in the laboratory. Figure 3 shows methanol productivity for a typical liquid-ehase run with balanced syngas without water addition.
Productivity falls off with time onstream from around 17 to 12.5 gmole/hr-kg. Figure 3 illustrates the exeected and well-known fact that methanol synthesis catalyst deactivates with time. Figure 3 also illustrates a characteristic of methanol synthesis catalyst life curves, in that there is an early period of hyperactivity during which the catalyst deactivates sharply; after this hyperactivity period the catalyst deactivates slowly.
Figure 4 shows methanol productivity for a run with C0-rich syngas and intermittent water addition. Curve #l shows the baseline methanol productivity trend when water is added as indicated by curve #2. Ths data points represent the methanol productivity during the periods without water addition, the productivity during periods with water addition always exceed the baseline curve #1. The important point here `
1 3303~q is that curve ~1 is flat, rather than downward sloping, indicating that -methanol productivity is not decreasing as was seen in Figure 3. This is especially notable because thP comparison is made during the hyperactivity period, when the rate of deactivation is most pronounced.
Therefore, Figure 4 indicates that the methanol productivity of the catalyst is preserved by the intermittent addition of water. Thus, the IGCC coproduction plant with water addition not only gets an additional degree of flexibility and a smaller reactor or incremental methanol production, but also a longer-lived catalyst.
In order to further demonstrate the efficacy of the present invention and to provide a description of several other process steps which can make the IGCC process more flexible, the following examples were simulated. In these examples a base case without water addition has been run for each of the process configurations.
EXAMPLES
Example I
Figures 5 and 6 show block flow diagrams for a simple once-through liquid-phase methanol IGCC process. Figure 5 shows the process without water addition and Figure 6 with water addition. The corresponding material balances for 3,000 TPD of low sulfur coal for each figure are shown in Tables I and II, respectively.
' ~ 330349 TABLE I
IGCC LIQUID-PHASE METHANOL BASE CASE :
FLOW RATES SHOWN ARE IN LBMOL/HR
STREAM NAME & NUMBER
RAW"CO-RICH" ACID FLASH
OXYGEN GASGAS GAS GAS
COMPONENT 2 3 4 5 _ 8 - -H2 0 8,648 8,645 3 4,638 CO 0 12,600 12,597 3 10,609 CO2 0 4,482 3,211 1,271 3,108 N2tCH4-Ar) 173 409 247 162 247 O2 8,459 0 0 0 0 TOTAL (~MPH) 8,632 26,44524,7001,745 18,771 ~ ~ -TOTAL tLB/HR) 275,878590,472 518,700 71,772 455,906 ~ :
STREAM NAME & NUMBER ::~
TURBINE CRUDE :.
EXHAUST METHANOL
COMPONENT 9 11 : :
CO214,023 89 N2tCH4-AR) 122,921 0 O2 24,593 0 H2S 0 0 :
COS O O " ~
H2012,952 14 : :
CHtlOH o 1,828 TOTAL t#MPH) 174,489 1,935 TOTAL tLB/HR) 5,324,75452,776 ~' ~:: ~.',',.
... . . ~
1 3303~
TABLE II
IGCC LIQUID-P~SE METHU~IOL WITH WATER ADDITION CASE
FLOW RATES SHOWN ARE IN LBMOL/HR
STREAM NAME & NUMBER
RAW"CO-RICH" ACID -OXYGEN GAS GAS GAS WATER
H~ 08,6488,645 3 0 CO 012,60012,597 3 0 CO2 0 ~,~82 3,211 1,271 0 N2(CH4-Ar)173 409 247 162 0 O2 8,459 0 0 0 0 H20 0 0 0 0 2,139 TOTAL (#MPH) 8,63226,445 24,700 1,745 2,139 -~
TOTAL (LB/HR)275,878590,472518,70071,772 38,502 STREAM NAME ~ NUMBER
LPR FLASH TURBINE CRUDE
INLET GAS EXH~UST METHANOL
H2 8,645 6,442 0 0 CO 12,597 8,349 0 3 CO2 3,211 5,16013,818 147 ~ N2(CH4-Ar) 247 247 112,718 0 O2 0 022,103 0 COS
H2O 2,139 114,659 42 CH30H 0 177 0 1,972 TOTAL (#MPH)26,83920,376163,298 2,164 TOTAL (LB/HR) 557,202486,787 4,960,690 70,406 :~
' 1 33034q Example II
Figures 7 and 8 show block flow diagrams for a once-through liquid-phase methanol IGCC process with a membrane recycle. Figure 7 shows the process without water addition and Figure 8 with water addition. The corresponding material balances for 3,000 TPD of low sulfur coal for each fiqure are shown in Tables III and IV, respectively.
It should be noted that the membrane material in this example is a commercially available cellulose acetate. Other membranes with higher H2/CO2 selectivities will permit even greater increases in methanol production.
1 3303~q TABL~ III
IGCC LIQUID-PHASE METHANOL ~ASE CASE WITH MEMBRANE RECYCLE
FLOW RATES SHOWN ARE IN LBMOL/HR
STREAM NAME & NUMBER
RAW"CO-RICH" ACID LPR
OXYGEN GAS GAS GAS INLET
H2 08,6488,645 312,858 CO 012,60012,597 313,159 -~;
CO2 0 4,482 3,211 1,271 S,267 N2(CH4-Ar~ 173 409 247 162 256 O2 8,459 0 0 0 0 TOTAL (#MPH) 8,63226,445 24,700 1,745 31,647 TOTAL (LB/HR)275,878590,472518,70071,772 637,029 STREAM NAME & NUMBER _ FLASH MEMBRANE T ~3INE ME~3RANE CRUDE
GAS REJECT EXHAUST PERMEATE METHANOL
H2 7,021 2,809 04,213 0 CO 10,280 9,718 0 562 5 CO2 5,023 2,96312,864 2,056 183 N2(CH4-Ar) 256 247 97,782 9 0 O2 0 019,504 0 0 COS O O O O O
H20 1 010,542 0 38 CH3OH 199 18 0 106 2,804 TOTAL ~#MPH)22,78015,755 140,692 6,947 3,030 TOTAL (LB/HR) 536,960416,095 4,313,373 118,329 98,598 . .
`
1 ~3:034q TABLE IV
IGCC LIQUID-PHASE METHANOL BASE CASE WITH MEMBRANE RECYCLE
AND WATER ADDITION
FLOW RATES SHOWN A~E IN LBMOL/HR
STREAM NAME & NUMBER
RAW"CO-RICH" ACID
OXYGEN GAS GAS GAS WATER
H2 08,6488,64i5 3 0 CO 012,60012,597 3 0 CO2 0 4,482 3,211 1,271 0 N2(CH4-Ar) 173 409 247 162 0 O2 8,459 0 H2S 0 287 0 287 0 ~-H2O 0 0 0 0 2,139 TOTAL (#MPH) 8,63226,445 24,700 1,745 2,139 TOTAL (LB/HR)275,878590,472518,70071,772 38,502 .:
STREAM NAME & NUMBER
LPR FLASH MEMBRANE TURBINE MEMBRANE CRUDE
INLET GAS REJECT EXHAUST PERMEATE METHANOL
COMPONENT 7 8 9 10 12 14 ~ :
H2 15,175 10,882 4,353 06,530 0 :~
CO 13,~12 7,858 7,444 0415 3 CO2 6,536 8,220 4,89312,533 3,325 268 N2~CH4-Ar) 256 256 247 85,659 9 0 : :
O2 0 0 016,656 0 0 :~ .
H2S 0 0 0 0 0 0 .
COS O O O O O O ` ~
H2O 2,141 4 011,951 2 140 i `' CH3OH 156 225 17 0 156 3,072 TOTAL ~#MPH)37,27527,44516,95~126,799 10,436 3,483 TOTAL ~LB/HR)733,445 618,412440,380 3,869,329 176,243 ll2,688 '''`''~','"'`' '~' ~
. ~ .
Example III
Figures 9 and 10 show block flow diagrams for a once-through liquid-phase methanol IGCC process with a membrane unit and a gas-phase methanol synthesis loop. Figure 9 shows the process without water addition and Figure 10 with water addition. The corresponding material balances for 3,0~0 TPD of low sulfur coal for each figure are shown in Tables V and VI, respectively.
In this example, the H2O/CO ratio is slightly higher than in Examples I and II to facilitate sufficient water-gas shift reaction to give a balanced syngas after membrane processing. As in Example II, the membrane material is cellulose acetate. Other membranes with higher H2~CO2 selectivity would provide additional benefits by reducing the load on the CO2 removal unit and making more high pressure C02 available for power recovery in the gas turbine expander.
1 3303~q TABLE V
IGCC LIQUID-PHASE METHANOL BASE CASE WITH MEMBRANE RECYCLE
AND GAS-PHASE METHANOL LOOP
FLOW RATES SHOWN ARE IN LBMOL/HR
STREAM NAME & NUMBER
RAW"CO-RICH" ACID FLASH
OXYGEN GAS GAS GAS GAS
H2 08,6488,645 34,638 CO 012,60012,597 310,609 CO2 0 4,482 3,211 1,271 3,108 N2(CH4-Ar) 173 409 247 162 247 O2 8,459 0 0 0 0 TOTAL (#MPH) 8,63226,445 24,700 1,745 18,771 TOTAL (LB/HR)275,878590,472518,70071,772 455,906 STREAN NAME & N~3ER
MEMBRANE MEMBRANE MEMBRANE MEMBRANE GAS-LOOP FLASH
FEED BYPASS REJECT PERMBATE FEED GAS .~
COMPONENT 9 10 11 12 13 14 -`~ : .
H2 4,334 301 1,300 3,034 3,335 323 CO 9,910 689 9,161 749 1,438 67 CO2 2,898 202 1,421 1,476 101 4 : :: ~:
N2(CH4-Ar) 231 16 219 11 28 27 :~
H2S 0 0 0 0 0 0 ~::: :
COS O O O O O O ` ~''-'':
CH3OH 157 11 9 148 159 2 ~ :
.
TOTAL (#MPH)17,530 1,219 12,110 5,419 5,06Z 422 TOTAL (LB/HR)425,59129,592328,475 ;97,09457,319 3,544 . ~ .: .:, :. :
:; .
STREAM N~M2 & NUMBER
G.T. STACK LPR GAS-LOOP TOTAL
FEED GAS CRUDE CRUDE CRUDE
H2 1,623 0 0 7 7 CO 9,227 0 4 5 10 CO2 1,42510,805 ~9 7 95 N2~CH4-Ar) 246 85,230 0 0 C
O2 017,028 0 0 0 COS
H20 0 9,198 14 91 105 CH3OH 11 0 1,828 1,615 3,443 TOTAL ~#MPH)12,532122,261 1,935 1,725 3,660 TOTAL ~LB/HR)332,018 3,742,78062,77653,771 116,538 TABLE VI
IGCC LIQUID-PHASE METHANOL BASE CASE WITH MEMBR~NE RECYCLE, GAS-PHASE METHANOL LOOP, AND WITH WATER ADDITION
FLOW RATES SHOWN ARE IN LBMOL/HR
STREAM NAME & NUMBER ~:
RAW ''CO-RICH" ACID
OXYGEN GAS GAS GAS WATER
COMPONENT 2 3 4 5 6 : .;~.:
H2 08,6488,645 3 0 CO 012,60012,597 3 0 CO2 0 4,482 3,211 1,271 0 N2(CH4-Ar) 173 409 247 162 0 O2 8,459 0 0 H20 0 0 0 0 2,674 TOTAL ~#MPH) 8,632 26,445 24,700 1,745 2,674 TOTAL ~LB/HR)275,878590,472518,70071,772 48,13Z
' STREAM NAME & NUMBER
LPR FLASH MEMBRANE MEMBRANE MEMBRANE MEMBRANE
INLET GAS FEEDBYPASS REJECT PERMEATE
H2 8,645 6,836 5,344 1,493 2,137 3,206 CO 12,597 7,755 6,061 1,693 5,734 327 CO2 3,211 5,641 4,409 1,232 2,609 1,800 N2(CH4-Ar)247 247 193 54 186 7 COS O O O O O O
H20 2,674 2 1 0 0 1 1 0 . ~:
TOTAL (#MPH)27,37420,65816,147 4,51110,679 5,468 :
TOTAL (LB/HR)566,832492,115384,657107,458285,594 99,062 ;~
, .
STREAM NAME ~ NUMBER
GAS-LOOP FLAS~ G.T. STACK LPR
FEED GAS FEED GAS CRUDE
Hz 4,699 468 2,605 0 0 CO 2,021 94 5,828 0 3 CO2 142 5 2,614 8,605 163 N2(CH4-Ar) 61 60 246 58,993 0 : ~:
O2 0 0 0 11,2~4 0 COS O O O O O
H2O 2 0 0 9,893 54 CH3OH 166 3 15 0 2,034 TOTAL ~#MPH)7,089 630 11,308 88,764 2,254 .
TOTAL (LB/HR)79,359 5,674291,268 2,687,237 73,289 :, ,:
': "
1 3303~9 STREAM NAME & NUMBER
GAS-LOOP TOTAL
CRUDE CRUDE
N2(CH4-Ar) COS O O
CH30H 2,210 4,244 TOTAL (~MPH) 2,364 4,~17 TOTAL (LB/HR)73,652 146,941 As can be seen from the Examples, the present invention includes several other erocess variations which add even more flexibility to the IGCC coproduction flowsheet. Figure 8 shows a proposed block flow diagram for a plant which incorporates a membrane loop into the effluent fuel gas stream to recover hydrogen for recycle to the liquid-phase reactor. The recycled hydrogen increases the feed H2/CO ratio to the reactor, which increases methanol production. The membrane can be used in conjunction with water addition to the liquid-phase methanol reactor, or without water addition. Mass and energy balances indicate that daily methanol production can be increased by 53% by using the membrane alone, and by an additional 15% by using both the membrane and water addition.
Figure 10 shows a proposed block flow diagram for an IGCC
coproduction scheme which incorporates water addition, membrane H2 recovery, and a gas-phase methanol loop. Here, a portion of the fuel gas bypasses the membrane so that, after C02 removal from this stream and the membrane effluent, the combined stream is balanced. This balanced gas is fed to a conventional gas-phase methanol reactor, after which the methanol is recovered and the unreacted purge gas is sent to the gas turbine.
Table VII itemizes the relative methanol production which can be achieved in these various IGCC coproduct configurations. As s~en, there are a total of 6 options available. Clearly th~re is significant flexibility available through practicing this invention.
.
1 ~30349 T~BLE VII : :
PLANT VARIATIONS USING COMBINED SHIFT/SYNTHESIS ~ :
Methanol Production Option Compared to Option #l S c~
1. Once Through Liquid-Phase Methanol 100% :
FOR METHANOL AND ELECTRICAL POWER PRODUCTION
TECHNICAL FIELD
The present inv2ntion relates to an integrated gasification combined cycle ~IGCC) process. More specifically, the present invention relates to an improvement which converts a portion of the produced, CO-rich synthesis gas to produce a crude methanol product for peak-shavinq.
AC~GROUND OF T~E INVENTION
Methanol is produced from synthesis qas (syngas), a mixture of hydrogen (H2), carbon monoxide (CO), and carbon dioxide (CO2). The stoichiometry of the methanol synthesis reactions indicates that the desired molar reactor feed composition is given by the equation:
R = (H2-CO2~/(CO+CO2) = 2-0 However, reaction kinetics and system control dictate that the optimum ratio is actually R = 2.1 or higher. Gas with R = 2.0 to 2.1 is called "balanced" gas, i.e. balanced stoichiometrically, and has a typical com~osition of 19% CO, 5% CO2, 55% H2, and 21% CH4-N2.
Syngas is commonly made by the reforming of methane or other hydrocarbons, which gives a hydrogen-rich gas well-suited for methanol synthesis (e.g., a typical methanol syngas produced by steam reforming of methane has a composition of 15~ CO, 8% CO2, 73% H2, 4% CH4-N2, R=2.8). Currently 70 to 75% of the world's methanol comes from reformed natural gas, however, because of the instability of the oil market, liquid hydrocarbons and natural gas are not always readily available or available at an inexpensive cost. An alternative and abundant resource is coal, which can be converted to syngas in a coal gasifier such as the advanced, high-temperature coal gasifiers developed by Texaco, Dow, Shell, and British Gas/Lurgi.
Coal-derived syngas can be used as gas turbine fuel in an integrated gasification combined cycle (IGCC) electric power plant. Because of the daily cyclical demand for power, a primary concern in such a facility is load-following flexibility. To accomplish this flexibility, either the 1 3303~q front end of the IGCC plant must be built for peak capacity, or extra fuel must be imported during peak periods tcalled peak shaving~. The former is an exeensive and inefficient option. The latter, although somewhat less expensive, can be improved by producing and storing the fuel on-site. One solution to this problem is the on-site production of methanol as the peak-shaving fuel.
In an IGCC facility without methanol coproduction, the syngas is combusted in a gas turbine to produce electricity. The turbine exhaust~stack gas is used to generate and superheat steam in an integrated heat recovery system, and this steam is also used to generate electricity. In a coproduction facility, the syngas is first passed through a methanol synthesis reactor to convert a portion to methanol;
the remaining syngas is fed to the gas turbine for power production. The methanol is stored as peak-shaving fuel, which is used to augment the feed to the gas turbine during periods of high power demand. This scheme is attractive because the load on a power plant varies over a wide range, and it is more economical to feed the stored methanol than to build peak-shaving capacity into the front end of the facility.
Unfortunately, coal-derived syngas from advanced gasifiers used in IGCC plants is CO-rich (e.g., a Texaco gasifier syngas has a typical comeosition of 35~ H2, 51% CO, 13% C02, 1% CH4-N2, R=0-34)~
unlike the hydrogen-rich syngas from reformed hydrocarbons. The problem is that converting this gas to methanol by conventional methods is exeensive and com~licated because several pretreatment stees are required ~ ;
to balance the gas prior to methanol synthesis.
Conceptual IGCC co~roduct plants have been designed with gas-phase and with liguid-phase methanol synthesis reactors. With a gas-phase reactor, the main syngas stream from the gasifier is divided into two parts: approximately 75% goes directly to the gas turbine, and the remaining 25~ goes to the methanol synthesis section. This }atter stream is further divided, a~proximately 67% being mixed with steam and sent to a high temperature shift reactor (HTS). After shift, the C02 is removed and this stream $S remixed with the unshifted stream and recycle gas in the methanol loop to give a balanced gas for methanol synthesis.
Purge gas from the recycle loop and the rejected C02 from the C02 1 3303~9 removal section are sent to the gas turbine. The use of a conventional, gas-phase methanol synthesis reactor in an IGCC coproduct scheme is subject to the same shortcomings as in a gas-phase all-methanol product plant: a shift section and CO2 removal section are required in order to achieve a feed gas composition with an "R" value greater than 2.0, shift and methanol synthesis are performed in separate vessels, and the conversion per pass is limited by temperature constraints.
The liquid-~hase methanol process has an advantage over gas-phase methanol synthesis in a coproduct configuration because of its ability to }0 directly process CO-rich gas ~e.g., "~" values between about 0.30 and 0.40). The entire C0-rich gas stream from the gasifier is sent through the liquid-phase reactor in a single pass, achieving 10-20~ conversion of CO to methanol. While additional methanol can be produced by balancing the gas prior to feeding it to the liquid-phase methanol reactor, the value of this incremental methanol is outweighed by the cost of separate shift and CO2 removal units. ~ecause a liquid-phase methanol reactor operates isothermally, there is no increasing catalyst temperature and the accompanying constraint on methanol conversion which is characteristic of gas-phase methanol synthesis processes. In a typical liquid-phase design, approximately 14~ of the CO (feedgas "R" = 0.34) i5 converted to methanol, giving a reactor effluent containing approximately 9% methanol: the per pass conversion in a gas-phase reactor generally results in a reactor effluent containing only 5% methanol even though the ;~
feedgas has an "R" greater than 2Ø It should be noted, however, that even with the superior performance of the liquid-phase reactor, the coproduction scheme can still be expensive, and there is incentive to improve this processing route.
A somewhat similar coproduction scheme is also worthy of mention ~;
~U.S. Pat. 3,986,349 and 4,092,825). This scheme involves converting coal-derived syngas into liquid hydrocarbons via Fischer-Tropsch synthesis, separating the hydrocarbons from the unreacted gas, feeding the gas to a gas turbine to generate electric power, and using at least part of the hydrocarbons as peak-shaving fuel. Although methanol is mentioned as a possible by-product of the hydrocarbon synthesis, it is not one of the desired products.
SUMMARY OF THE INVENTION
The present invention is an improvement to an integrated gasification combined cycle (IGCC) electric power plant process. The IGCC process converts hydrocarbon fuels in a gasifier producing a CO-rich synthesis gas, which in turn is combusted in a gas turbine to produce ~ower. The IGCC process also includes a provision for production of methanol from the CO-rich synthesis gas prior to combustion as a supplemental fuel, which can be used to peak-shave. Methanol is produced by reacting at least a eortion of the CO-rich synthesis gas in the presence of a methanol synthesis catalyst.
The improvement for increasing methanol productivity from the same amount of synthesis gas is the combination of the water/gas shift and methanol synthesis reactions in a single step by reacting the carbon monoxide-rich synthesis gas with water in the presence of a catalyst in a liquid-phase reactor thereby producing both a crude methanol product and a reduced carbon monoxide content and increased hydrogen and carbon dioxide content synthesis gas. The produced reduced carbon monoxide content and increased hydrogen and carbon dioxide content synthesis gas is suitable for combustion in a gas turbine.
The ~ater added to the liquid-phase reactor can be beneficially introduced as a liquid. The catalyst in the liquid-phase reactor can be any appropriate methanol synthesis catalyst or a mixture of a methanol synthesis catalyst and a low temperature shift catalyst. The catalyst concentration in the liquid-phase methanol reactor can be in the range from about 5 to about 50 weight percent. The improvement to the process of the present invention is particularly suited to C0-rich synthesis gases having an R value less than 2Ø
The present invention also comprises several further processing steps. Among these are (1) processing at least a portion of the reduced carbon monoxide and increased hydrogen and carbon dioxide synthesis gas in, for example, a membrane unit or a pressure swing adsorber (PSA) u~it to separate the reduced carbon monoxide and increased hydrogen and carbon dioxide synthesis gas into a hydrogen-rich component and a carbon monoxide-rich component, both components comprising hydrogen, carbon dioxide and carbon monoxide, and recycling the hydrogen rich component to 1 ~30349 the inlet of the liquid-phase reactor; and (2) processing at least a portion of the reduced carbon monoxide and increased hydrogen and carbon dioxide synthesis gas in, for example, a membrane unit or a pressure swing adsorber tPSA) unit to separate the reduced carbon monoxide and increased hydrogen and carbon dioxide synthesis gas into a hydrogen-rich component and a carbon monoxide-rich component, both components comprising hydrogen, carbon dioxide and carbon monoxide, combining the hydrogen-rich component and a portion of the unprocessed synthesis gas (i.e., the gas not processed in the membrane or PSA units) into a single methanol reactor feed stream, optionally removing at least a portion of the carbon dioxide from the gas-phase methanol reactor feed stream, -reacting the methanol reactor feed stream in a gas-phase reactor to i~
produce methanol, and combining the unconverted effluent from the gas-phase methanol reactor with the carbon monoxide-rich component from the membrane unit to form a gas turbine combustion fesd.
BRIEF DESCRIPTION OF THE DRAWING
Figure 1 is a plot showing the effect of water, expressed as molar H2O/CO ratio entering the liquid-phase methanol reactor, on methanol productivity and on the hydrogen content leaving the liquid-phase methanol reactor.
Figure 2 is a schematic diagram of an embodiment of the methanol synthesis and combustion turbine sections of an IGCC power plant according to the present invention.
Figure 3 is a plot of methanol productivity for a typical liquid-phase run without water addition.
Figure 4 is a plot of methanol productivity for a run with intermittent water addition.
Figures 5 and 6 are block flow diagrams for a simple once-through ~ -liquid-phase methanol IGCC process. Figure 5 shows the process without water addition and Figure 6 with water addition.
Figures 7 and 8 are block flow diagrams for a once-through liquid-phase methanol IGCC process with a membrane recycle. Figure 7 shows the process without water addition and Figure 8 with water addition.
1 ~30349 Figures 9 and 10 sho~ block flow diagrams for a once-through liquid-phase methanol IGCC process with a memorane unit and a gas-phase mPthanol synthesis loop. Figure 9 shows the process without water addition and Figure 10 with water addition. -DETAILED DESCRIPTION OF THE INVENTION
The present invention is an improvement to the methanol production step within an integrated gasification combined cycle process wherein methanol is produced for peak-shaving from CO-rich synthesis gas. The improvement to the process is the combination of the methanol synthesis ~;
and water-gas shift reactions in a single step in order to increase ~
methanol productivity. The improvement of the present invention replaces -the need to balance the synthesis gas in shift and CO2 removal steps prior to its conversion to methanol as would be required if a gas-phase ~ethanol synthesis process were used. The present invention is based on the fact that if water is added to the CO-rich syngas feed to a liquid-phase methanol reactor, the water-gas shift and methanol synthesis reactions will take place simultaneously. In fact, if no water is added the reverse water-gas shift reaction is known to take place in either liquid or gas-phase reactors. The addition of water simply forces the equilibrium in the forward direction (i.e., CO ~ H2O ~ H2 +
C2) Several advantages of the liquid-phase methanol reactor have already been mentioned. An additional advantage is seen when considering water addition. In contrast to conventional technologies, liquid water can be added directly to the liquid-phase reactor. This saves the cost of generating high-pressure process steam, and also reduces the net heat which must be removed from the reactor. A conventional gas-phase reactor cannot accept a liquid water feed because thenmal shock and rapid vaeorization can break up and destroy the catalyst tablets. In addition, water vapor which is added must be kept well above its dew point to prevent condensation and subsequent quenching of the bed due to its plug flow operation.
-1 ~303~9 Althouqh the addition of steam to a liquid-phase methanol reactor was considered in EPRI Report AF-1291 (December 1979, p. 5-3), wherein the conce~t is discussed, and laboratory data is presented for two syngas compositions, the data indicated that methanol productivity decreases as water is added. It was reported that water addition always reduces methanol productivity, especially for gases that already have the required H2~CO stoichiometry, and that for non-stoichiometric synthesis gases, the fall off in productivity with increasing steam/CO ratio is slower. -The experimentation behind the present invention, on the other hand, shows results which are surprising relative to those in the EPRI report.
Figure 1 shows the effect of water, expressed as the molar H2O/CO ratio entering the liquid-phase methanol reactor, on methanol productivity tmmol MeOH/hr-gm catalyst) and on the molar H2~CO ratio ta measurement lS of the extent of the water-gas shift reaction) leaving the liquid-phase methanol reactor. This graph illustrates two important points. First, the methanol productivity curve goes through a maximum, showing that water indeed can be used to boost methanol productivity. This maximum was not seen or even suspected in the data reported in EPRI Report AF-1291. Second, adding water increases the hydrogen content in the effluent. Although the CO2 produced from the shift reaction prevents a stoichiometrically balanced effluent, the proper amount of CO2 can be removed later to give a balanced gas, if desired. Thus, adding a precise amount of water results in increased methanol production relative to dry CO-rich gas feed as well as a notable production of H2 via the shift reaction. Adding more water results in increased H2 production at some sacrifice to methanol productivity.
The proposed IGCC coproduct plant flowsheet according to the present invention is shown in Figure 2. With reference to Figure 2, desulfurized CO-rich synthesis gas and water (liquid or vapor) are fed to the process via lines 1 and 3, respectively, combined, and fed to liquid-phase reactor 7 via line 5, wherein the synthesis gas and water react in the presence of a catalyst. Alternatively, the liquid water or steam, in line 3, can be added directly to reactor 7 without irst being combined with the synthesis gas. Liquid-phase methanol reactor 7 can be operated 1 3303~q in either a slurry or ebullatsd mode. In the case of the slurry mode, a -~
powdered methanol synthesis catalyst (e.g., CuO~ZnO/A1203) is slurried in a liquid medium (e.g light paraffinic or cycloparaffinic oils). Alternatively, a mixture of powdered methanol synthesis catalyst and low temperature shift catalyst can be used in reactor 7. The concentration of catalyst can range from about 5 to 50 wt%. In the case -of an ebullated mode, a granulated catalyst is fluidi~ed in a liguid - ~
medium. Liquid-phase reactor 7 operates within the conventional~ -understanding of a liquid-phase reactor.
The effluent removed via line 9 from liquid-phase reactor 7 is cooled in a series of heat exchangers, including heat exchanger 43, and subsequently separated in separator 11 into a liquid and vapor stream.
The primary purpose of separator 11 is to recover and recycle the liquid medium which was vaporized and entrained in the reactor effluent. The liquid stream is recycled via line 13 to liquid-phase reactor 7.
Additionally, to provide heat removal from reactor 7, a liquid stream is removed from the reactor via line 15, cooled and returned to reactor 7.
The vapor stream from oil separator 11 is removed via line 17, cooled in a series of heat exchangers so as to condense methanol and water in the stream and then fed to high pressure methanol separator 19.
The overhead from separator 19 is removed via line 21: this overhead is mainly unreacted synthesis gas, which is then reduced in pressure in expander 23 to recover power and subsequently fed to burner 49 via line 25.
The liquid phase from separator 19 is removed via line 27, reduced in pressure in J-T valve 29 and fed to low pressure methanol separator 31. In separator 31, dissolved synthesis gas in the methanol and water solution is removed as overhead via line 35 and fed as feed to burner 49. The bottoms of separator 31 is removed via line 33 as crude methanol ~ -product.
The above is a description of a once through methanol synthesis ~ `
portion of an IGCC process. The combustion portion of the IGCC cycle is as follows: As mentioned earlier, the unreacted synthesis gas from the methanol synthesis portion is fed to burner 49 via lines 25 and 35.
These streams are combusted in burner 49 along with fuel gas produced ~ ~
. ~ .
1 3303~q from the sulfur removal step of the gasifier portion of an IGCC facility (fed via line 81), compressed air and steam. The compressed air is introduced to the process via line 75, compressed in compressor 77 and introduced into the burner via line 79. Steam is produced and introduced into the burner through two heat sources. First, boiler feed water, in line ~1, is heated in heat e~changer 43 against the efflusnt, line 9, from liquid-phase reactor 7 producing steam in line 45. Second, boiler feed water, in line 61, is heated in heat recove.y unit 57 producing steam in line 63. These two steam streams, lines 45 and 63 are combined into stream 47 which is then fed to burner 49.
The combustion gas from burner 49 is fed to gas turbine e~pander 53 via line 51 for recovery of power and subsequently fed to heat recovery unit 57 via line 55. In heat recovery unit 57, energy is recovered from the expanded combustion gas by producing steam and sueerheating steam by 1~ heat exchange of the combustion gas with boiler feed water and saturatPd steam. A portion of the steam produced in heat recovery unit 57 is introduced as feed to burner 49. Ths remaining portion of steam, in line 67, which is produced from boiler feed water introduced via line 65, is e~eanded in turbine 69 producing both power and low pressure steam.
In the above description, stream 1 represents desulfurized C0-rich gas from a Texaco coal gasifier: stream 3 can be used to sueply water such that the combined streams (line 5) have a molar ratio of H20/C0 =
0.17. As shown in ~igure 1, this is approximately the ratio necessary to achieve the maximum methanol production. Stream 5 is fed to liquid-phase reactor 7, which typically operates at about 482F and 910 esia.
Reaction heat is removed in an external heat e~change loop which produces saturated steam. The reactor effluent is cooled by first producing steam, then by heat exchange with unreacted fuel gas, and finally with cooling water. The two-phase mixture is separated and the vapor is heated and expanded, producing electric power. This expanded fuel gas is then sent to the gas turbine burner. The condensed methanol is flashed to yield the crude methanol product and a residual gas stream which is also fed to the gas turbine burner. In addition to the main fuel gas and flash gas streams, the gas turbine burner also receives a fuel gas stream from the upstream sulfur removal elant (e.g., Sele~ol, Rectisol, Rectisol *Trsde mark ~ .uYr...,..: . ~
- - 1 3333~q II), sufficient steam from the process to control ~x production, and ~ -compressed air. These streams are fed to the combustion zone, which txpically operates at 2000F. The burner effluent expands across the ~as turbine expander, which produces electric power for export and for running the air compressor. The gas turbine exhaust is used to produce and superheat steam in an integrated heat recovery system. The steam subseguently powers steam turbines which produce additional electric power.
An IGCC coproduct plant without water addition has two principal modes of operation. During peak power demand times, all of the fuel gas and some stored methanol go to the gas turbine. During off-peak hours, gas flows through the liquid-phase reactor to convert a eortion of the gas to methanol for storage. With water addition, the methanol productivity per mass of catalyst is increased, which means that either the reactor can be downsized or additional methanol can be produced from a base-size unit. The plant has greater flexibility because it can operate in three modes: all fuel gas to the gas turbine, gas through the liguid-phase reactor without water addition, and gas through liquid-phase reactor with water added.
An additional, surprising benefit of water addition has been demonstrated in the laboratory. Figure 3 shows methanol productivity for a typical liquid-ehase run with balanced syngas without water addition.
Productivity falls off with time onstream from around 17 to 12.5 gmole/hr-kg. Figure 3 illustrates the exeected and well-known fact that methanol synthesis catalyst deactivates with time. Figure 3 also illustrates a characteristic of methanol synthesis catalyst life curves, in that there is an early period of hyperactivity during which the catalyst deactivates sharply; after this hyperactivity period the catalyst deactivates slowly.
Figure 4 shows methanol productivity for a run with C0-rich syngas and intermittent water addition. Curve #l shows the baseline methanol productivity trend when water is added as indicated by curve #2. Ths data points represent the methanol productivity during the periods without water addition, the productivity during periods with water addition always exceed the baseline curve #1. The important point here `
1 3303~q is that curve ~1 is flat, rather than downward sloping, indicating that -methanol productivity is not decreasing as was seen in Figure 3. This is especially notable because thP comparison is made during the hyperactivity period, when the rate of deactivation is most pronounced.
Therefore, Figure 4 indicates that the methanol productivity of the catalyst is preserved by the intermittent addition of water. Thus, the IGCC coproduction plant with water addition not only gets an additional degree of flexibility and a smaller reactor or incremental methanol production, but also a longer-lived catalyst.
In order to further demonstrate the efficacy of the present invention and to provide a description of several other process steps which can make the IGCC process more flexible, the following examples were simulated. In these examples a base case without water addition has been run for each of the process configurations.
EXAMPLES
Example I
Figures 5 and 6 show block flow diagrams for a simple once-through liquid-phase methanol IGCC process. Figure 5 shows the process without water addition and Figure 6 with water addition. The corresponding material balances for 3,000 TPD of low sulfur coal for each figure are shown in Tables I and II, respectively.
' ~ 330349 TABLE I
IGCC LIQUID-PHASE METHANOL BASE CASE :
FLOW RATES SHOWN ARE IN LBMOL/HR
STREAM NAME & NUMBER
RAW"CO-RICH" ACID FLASH
OXYGEN GASGAS GAS GAS
COMPONENT 2 3 4 5 _ 8 - -H2 0 8,648 8,645 3 4,638 CO 0 12,600 12,597 3 10,609 CO2 0 4,482 3,211 1,271 3,108 N2tCH4-Ar) 173 409 247 162 247 O2 8,459 0 0 0 0 TOTAL (~MPH) 8,632 26,44524,7001,745 18,771 ~ ~ -TOTAL tLB/HR) 275,878590,472 518,700 71,772 455,906 ~ :
STREAM NAME & NUMBER ::~
TURBINE CRUDE :.
EXHAUST METHANOL
COMPONENT 9 11 : :
CO214,023 89 N2tCH4-AR) 122,921 0 O2 24,593 0 H2S 0 0 :
COS O O " ~
H2012,952 14 : :
CHtlOH o 1,828 TOTAL t#MPH) 174,489 1,935 TOTAL tLB/HR) 5,324,75452,776 ~' ~:: ~.',',.
... . . ~
1 3303~
TABLE II
IGCC LIQUID-P~SE METHU~IOL WITH WATER ADDITION CASE
FLOW RATES SHOWN ARE IN LBMOL/HR
STREAM NAME & NUMBER
RAW"CO-RICH" ACID -OXYGEN GAS GAS GAS WATER
H~ 08,6488,645 3 0 CO 012,60012,597 3 0 CO2 0 ~,~82 3,211 1,271 0 N2(CH4-Ar)173 409 247 162 0 O2 8,459 0 0 0 0 H20 0 0 0 0 2,139 TOTAL (#MPH) 8,63226,445 24,700 1,745 2,139 -~
TOTAL (LB/HR)275,878590,472518,70071,772 38,502 STREAM NAME ~ NUMBER
LPR FLASH TURBINE CRUDE
INLET GAS EXH~UST METHANOL
H2 8,645 6,442 0 0 CO 12,597 8,349 0 3 CO2 3,211 5,16013,818 147 ~ N2(CH4-Ar) 247 247 112,718 0 O2 0 022,103 0 COS
H2O 2,139 114,659 42 CH30H 0 177 0 1,972 TOTAL (#MPH)26,83920,376163,298 2,164 TOTAL (LB/HR) 557,202486,787 4,960,690 70,406 :~
' 1 33034q Example II
Figures 7 and 8 show block flow diagrams for a once-through liquid-phase methanol IGCC process with a membrane recycle. Figure 7 shows the process without water addition and Figure 8 with water addition. The corresponding material balances for 3,000 TPD of low sulfur coal for each fiqure are shown in Tables III and IV, respectively.
It should be noted that the membrane material in this example is a commercially available cellulose acetate. Other membranes with higher H2/CO2 selectivities will permit even greater increases in methanol production.
1 3303~q TABL~ III
IGCC LIQUID-PHASE METHANOL ~ASE CASE WITH MEMBRANE RECYCLE
FLOW RATES SHOWN ARE IN LBMOL/HR
STREAM NAME & NUMBER
RAW"CO-RICH" ACID LPR
OXYGEN GAS GAS GAS INLET
H2 08,6488,645 312,858 CO 012,60012,597 313,159 -~;
CO2 0 4,482 3,211 1,271 S,267 N2(CH4-Ar~ 173 409 247 162 256 O2 8,459 0 0 0 0 TOTAL (#MPH) 8,63226,445 24,700 1,745 31,647 TOTAL (LB/HR)275,878590,472518,70071,772 637,029 STREAM NAME & NUMBER _ FLASH MEMBRANE T ~3INE ME~3RANE CRUDE
GAS REJECT EXHAUST PERMEATE METHANOL
H2 7,021 2,809 04,213 0 CO 10,280 9,718 0 562 5 CO2 5,023 2,96312,864 2,056 183 N2(CH4-Ar) 256 247 97,782 9 0 O2 0 019,504 0 0 COS O O O O O
H20 1 010,542 0 38 CH3OH 199 18 0 106 2,804 TOTAL ~#MPH)22,78015,755 140,692 6,947 3,030 TOTAL (LB/HR) 536,960416,095 4,313,373 118,329 98,598 . .
`
1 ~3:034q TABLE IV
IGCC LIQUID-PHASE METHANOL BASE CASE WITH MEMBRANE RECYCLE
AND WATER ADDITION
FLOW RATES SHOWN A~E IN LBMOL/HR
STREAM NAME & NUMBER
RAW"CO-RICH" ACID
OXYGEN GAS GAS GAS WATER
H2 08,6488,64i5 3 0 CO 012,60012,597 3 0 CO2 0 4,482 3,211 1,271 0 N2(CH4-Ar) 173 409 247 162 0 O2 8,459 0 H2S 0 287 0 287 0 ~-H2O 0 0 0 0 2,139 TOTAL (#MPH) 8,63226,445 24,700 1,745 2,139 TOTAL (LB/HR)275,878590,472518,70071,772 38,502 .:
STREAM NAME & NUMBER
LPR FLASH MEMBRANE TURBINE MEMBRANE CRUDE
INLET GAS REJECT EXHAUST PERMEATE METHANOL
COMPONENT 7 8 9 10 12 14 ~ :
H2 15,175 10,882 4,353 06,530 0 :~
CO 13,~12 7,858 7,444 0415 3 CO2 6,536 8,220 4,89312,533 3,325 268 N2~CH4-Ar) 256 256 247 85,659 9 0 : :
O2 0 0 016,656 0 0 :~ .
H2S 0 0 0 0 0 0 .
COS O O O O O O ` ~
H2O 2,141 4 011,951 2 140 i `' CH3OH 156 225 17 0 156 3,072 TOTAL ~#MPH)37,27527,44516,95~126,799 10,436 3,483 TOTAL ~LB/HR)733,445 618,412440,380 3,869,329 176,243 ll2,688 '''`''~','"'`' '~' ~
. ~ .
Example III
Figures 9 and 10 show block flow diagrams for a once-through liquid-phase methanol IGCC process with a membrane unit and a gas-phase methanol synthesis loop. Figure 9 shows the process without water addition and Figure 10 with water addition. The corresponding material balances for 3,0~0 TPD of low sulfur coal for each figure are shown in Tables V and VI, respectively.
In this example, the H2O/CO ratio is slightly higher than in Examples I and II to facilitate sufficient water-gas shift reaction to give a balanced syngas after membrane processing. As in Example II, the membrane material is cellulose acetate. Other membranes with higher H2~CO2 selectivity would provide additional benefits by reducing the load on the CO2 removal unit and making more high pressure C02 available for power recovery in the gas turbine expander.
1 3303~q TABLE V
IGCC LIQUID-PHASE METHANOL BASE CASE WITH MEMBRANE RECYCLE
AND GAS-PHASE METHANOL LOOP
FLOW RATES SHOWN ARE IN LBMOL/HR
STREAM NAME & NUMBER
RAW"CO-RICH" ACID FLASH
OXYGEN GAS GAS GAS GAS
H2 08,6488,645 34,638 CO 012,60012,597 310,609 CO2 0 4,482 3,211 1,271 3,108 N2(CH4-Ar) 173 409 247 162 247 O2 8,459 0 0 0 0 TOTAL (#MPH) 8,63226,445 24,700 1,745 18,771 TOTAL (LB/HR)275,878590,472518,70071,772 455,906 STREAN NAME & N~3ER
MEMBRANE MEMBRANE MEMBRANE MEMBRANE GAS-LOOP FLASH
FEED BYPASS REJECT PERMBATE FEED GAS .~
COMPONENT 9 10 11 12 13 14 -`~ : .
H2 4,334 301 1,300 3,034 3,335 323 CO 9,910 689 9,161 749 1,438 67 CO2 2,898 202 1,421 1,476 101 4 : :: ~:
N2(CH4-Ar) 231 16 219 11 28 27 :~
H2S 0 0 0 0 0 0 ~::: :
COS O O O O O O ` ~''-'':
CH3OH 157 11 9 148 159 2 ~ :
.
TOTAL (#MPH)17,530 1,219 12,110 5,419 5,06Z 422 TOTAL (LB/HR)425,59129,592328,475 ;97,09457,319 3,544 . ~ .: .:, :. :
:; .
STREAM N~M2 & NUMBER
G.T. STACK LPR GAS-LOOP TOTAL
FEED GAS CRUDE CRUDE CRUDE
H2 1,623 0 0 7 7 CO 9,227 0 4 5 10 CO2 1,42510,805 ~9 7 95 N2~CH4-Ar) 246 85,230 0 0 C
O2 017,028 0 0 0 COS
H20 0 9,198 14 91 105 CH3OH 11 0 1,828 1,615 3,443 TOTAL ~#MPH)12,532122,261 1,935 1,725 3,660 TOTAL ~LB/HR)332,018 3,742,78062,77653,771 116,538 TABLE VI
IGCC LIQUID-PHASE METHANOL BASE CASE WITH MEMBR~NE RECYCLE, GAS-PHASE METHANOL LOOP, AND WITH WATER ADDITION
FLOW RATES SHOWN ARE IN LBMOL/HR
STREAM NAME & NUMBER ~:
RAW ''CO-RICH" ACID
OXYGEN GAS GAS GAS WATER
COMPONENT 2 3 4 5 6 : .;~.:
H2 08,6488,645 3 0 CO 012,60012,597 3 0 CO2 0 4,482 3,211 1,271 0 N2(CH4-Ar) 173 409 247 162 0 O2 8,459 0 0 H20 0 0 0 0 2,674 TOTAL ~#MPH) 8,632 26,445 24,700 1,745 2,674 TOTAL ~LB/HR)275,878590,472518,70071,772 48,13Z
' STREAM NAME & NUMBER
LPR FLASH MEMBRANE MEMBRANE MEMBRANE MEMBRANE
INLET GAS FEEDBYPASS REJECT PERMEATE
H2 8,645 6,836 5,344 1,493 2,137 3,206 CO 12,597 7,755 6,061 1,693 5,734 327 CO2 3,211 5,641 4,409 1,232 2,609 1,800 N2(CH4-Ar)247 247 193 54 186 7 COS O O O O O O
H20 2,674 2 1 0 0 1 1 0 . ~:
TOTAL (#MPH)27,37420,65816,147 4,51110,679 5,468 :
TOTAL (LB/HR)566,832492,115384,657107,458285,594 99,062 ;~
, .
STREAM NAME ~ NUMBER
GAS-LOOP FLAS~ G.T. STACK LPR
FEED GAS FEED GAS CRUDE
Hz 4,699 468 2,605 0 0 CO 2,021 94 5,828 0 3 CO2 142 5 2,614 8,605 163 N2(CH4-Ar) 61 60 246 58,993 0 : ~:
O2 0 0 0 11,2~4 0 COS O O O O O
H2O 2 0 0 9,893 54 CH3OH 166 3 15 0 2,034 TOTAL ~#MPH)7,089 630 11,308 88,764 2,254 .
TOTAL (LB/HR)79,359 5,674291,268 2,687,237 73,289 :, ,:
': "
1 3303~9 STREAM NAME & NUMBER
GAS-LOOP TOTAL
CRUDE CRUDE
N2(CH4-Ar) COS O O
CH30H 2,210 4,244 TOTAL (~MPH) 2,364 4,~17 TOTAL (LB/HR)73,652 146,941 As can be seen from the Examples, the present invention includes several other erocess variations which add even more flexibility to the IGCC coproduction flowsheet. Figure 8 shows a proposed block flow diagram for a plant which incorporates a membrane loop into the effluent fuel gas stream to recover hydrogen for recycle to the liquid-phase reactor. The recycled hydrogen increases the feed H2/CO ratio to the reactor, which increases methanol production. The membrane can be used in conjunction with water addition to the liquid-phase methanol reactor, or without water addition. Mass and energy balances indicate that daily methanol production can be increased by 53% by using the membrane alone, and by an additional 15% by using both the membrane and water addition.
Figure 10 shows a proposed block flow diagram for an IGCC
coproduction scheme which incorporates water addition, membrane H2 recovery, and a gas-phase methanol loop. Here, a portion of the fuel gas bypasses the membrane so that, after C02 removal from this stream and the membrane effluent, the combined stream is balanced. This balanced gas is fed to a conventional gas-phase methanol reactor, after which the methanol is recovered and the unreacted purge gas is sent to the gas turbine.
Table VII itemizes the relative methanol production which can be achieved in these various IGCC coproduct configurations. As s~en, there are a total of 6 options available. Clearly th~re is significant flexibility available through practicing this invention.
.
1 ~30349 T~BLE VII : :
PLANT VARIATIONS USING COMBINED SHIFT/SYNTHESIS ~ :
Methanol Production Option Compared to Option #l S c~
1. Once Through Liquid-Phase Methanol 100% :
2. With Water Addition 108X
3. With Membrane Recycle 153%
4. With Membrane Recycle ;~
and Water Addition 168% .
and Water Addition 168% .
5. With Membrane Recycle Gas-Phase MeOH Loop 188% :~
..
..
6. With Membrane Recycle Gas-Phase MeOH Loop and Water Addition 232%
The present invention has been described with reference to a specific embodiment thereof. This embodiment should not be considered a limitation ::~on the sco~e of the present invention: the scope of which should be ascertained by the following claims.
~ ~
: ~ . : .
:
. .. : .
:: , . ~ : ::
The present invention has been described with reference to a specific embodiment thereof. This embodiment should not be considered a limitation ::~on the sco~e of the present invention: the scope of which should be ascertained by the following claims.
~ ~
: ~ . : .
:
. .. : .
:: , . ~ : ::
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In an integrated gasification combined cycle (IGCC) electric power plant process wherein the IGCC process converts hydrocarbon fuels in a gasifier producing a carbon monoxide-rich synthesis gas, which in turn is combusted in a gas turbine to produce power; wherein the IGCC process also includes a provision for production of methanol from the carbon monoxide-rich synthesis gas prior to combustion; and wherein methanol is produced by reacting at least a portion of the carbon monoxide-rich synthesis gas in the presence of a methanol synthesis catalyst; the improvement for increasing methanol productivity from the same amount of synthesis gas comprises combining water/gas shift and methanol synthesis reactions in a single step by reacting the carbon monoxide-rich synthesis gas with water in the presence of a catalyst in a liquid-phase reactor thereby producing both a crude methanol product and a reduced carbon monoxide content and increased hydrogen and carbon dioxide content synthesis gas for combustion.
2. The process of Claim 1 wherein the carbon monoxide-rich synthesis gas has an "R" value of less than 2Ø
3. The process of Claim 1 wherein the water reacted with the carbon monoxide-rich synthesis gas in the liquid-phase reactor is introduced to the reactor as liquid water.
4. The process of Claim 1 wherein the catalyst in the liquid-phase reactor comprises a methanol synthesis catalyst.
5. The process of Claim 1 wherein the catalyst in the liquid-phase reactor comprises a mixture of a methanol synthesis catalyst and a low temperature shift catalyst.
6. The process of Claim 1 wherein concentration of the catalyst in the liquid-phase reactor is in the range from 5 to 50 weight percent.
7. The process of Claim 1 which further comprises processing at least a portion of the reduced carbon monoxide and increased hydrogen and carbon dioxide synthesis gas to separate the reduced carbon monoxide and increased hydrogen and carbon dioxide synthesis gas into a hydrogen-rich component and a carbon monoxide-rich component, both components comprising hydrogen, carbon dioxide and carbon monoxide, and recycling the hydrogen rich component to the inlet of the liquid-phase reactor.
8. The process of Claim 7 wherein separation of the reduced carbon monoxide and increased hydrogen and carbon dioxide synthesis gas is accomplished in a membrane unit.
9. The process of Claim 1 which further comprises processing at least a portion of the reduced carbon monoxide and increased hydrogen and carbon dioxide synthesis gas to separate the reduced carbon monoxide and increased hydrogen and carbon dioxide synthesis gas into a hydrogen-rich component and a carbon monoxide-rich component, both components comprising hydrogen, carbon dioxide and carbon monoxide, combining the hydrogen-rich component and a portion of the unprocessed synthesis gas to form a gas-phase methanol reactor feed stream, reacting the gas-phase methanol reactor feed stream in a gas-phase reactor to produce methanol, and combining the unconverted effluent from the gas-phase methanol reactor with the carbon monoxide-rich component to form a gas turbine combustion feed.
10. The process of Claim 9 which further comprises removing at least a portion of the carbon dioxide from the gas-phase methanol reactor feed stream prior to reacting the gas-phase methanol reactor feed stream in the gas-phase reactor to produce methanol.
11. The process of Claim 10 wherein separation of the reduced carbon monoxide and increased hydrogen and carbon dioxide synthesis gas is accomplished in a membrane unit.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/178,955 US4946477A (en) | 1988-04-07 | 1988-04-07 | IGCC process with combined methanol synthesis/water gas shift for methanol and electrical power production |
| US178,955 | 1994-01-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1330349C true CA1330349C (en) | 1994-06-21 |
Family
ID=22654604
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000595444A Expired - Fee Related CA1330349C (en) | 1988-04-07 | 1989-03-31 | Igcc process with combined methanol synthesis/water gas shift for methanol and electrical power product |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4946477A (en) |
| EP (1) | EP0336378B1 (en) |
| JP (1) | JPH01301925A (en) |
| AU (1) | AU612810B2 (en) |
| CA (1) | CA1330349C (en) |
| DE (1) | DE68911972T2 (en) |
| ES (1) | ES2061757T3 (en) |
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1989
- 1989-03-31 CA CA000595444A patent/CA1330349C/en not_active Expired - Fee Related
- 1989-04-04 EP EP89105906A patent/EP0336378B1/en not_active Expired - Lifetime
- 1989-04-04 DE DE89105906T patent/DE68911972T2/en not_active Expired - Fee Related
- 1989-04-04 AU AU32404/89A patent/AU612810B2/en not_active Ceased
- 1989-04-04 ES ES89105906T patent/ES2061757T3/en not_active Expired - Lifetime
- 1989-04-07 JP JP1089526A patent/JPH01301925A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7714176B2 (en) | 2001-10-01 | 2010-05-11 | Technology Convergence Inc. | Methanol production process |
Also Published As
| Publication number | Publication date |
|---|---|
| AU3240489A (en) | 1989-10-12 |
| JPH01301925A (en) | 1989-12-06 |
| AU612810B2 (en) | 1991-07-18 |
| ES2061757T3 (en) | 1994-12-16 |
| EP0336378A2 (en) | 1989-10-11 |
| EP0336378B1 (en) | 1994-01-05 |
| EP0336378A3 (en) | 1992-02-05 |
| US4946477A (en) | 1990-08-07 |
| DE68911972D1 (en) | 1994-02-17 |
| DE68911972T2 (en) | 1994-05-05 |
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| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed | ||
| MKLA | Lapsed |
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