US3915844A

US3915844A - Method for treatment of heavy oils

Info

Publication number: US3915844A
Application number: US419657A
Authority: US
Inventors: Mikio Ueda; Shigenori Suzuki
Original assignee: Mitsui Engineering and Shipbuilding Co Ltd
Current assignee: Mitsui Engineering and Shipbuilding Co Ltd
Priority date: 1972-11-30
Filing date: 1973-11-28
Publication date: 1975-10-28
Anticipated expiration: 1992-10-28
Also published as: DE2359571A1; JPS4980102A; DE2359571B2; JPS5139644B2; GB1449894A

Abstract

Method for treatment of heavy oils characterized in that a powdery or granular alkali metal compound in the heated state is fed to the coker independently from the starting oil to effect desulfurization of the starting oil and to form granular coke, and the resulting granular coke is gasified with steam and oxygen or air in the fluidized bed gasification furnace.

Description

Uited States Patent 1191 11 1 3,915,844

Ueda et a1. Oct. 28, 1975 METHOD FOR TREATMENT OF HEAVY 2,527,575 10/1950 Roetheli 208/127 OILS 2,921,017 1/1960 Johnson et a1 208/106 3,009,781 11/1961 Johnson et a1...... 201/17 Inventors: Mlklo Ueda, y g shlgenorl 3,179,584 4/1965 Hammer et a1. 208 127 Suzuki, Osaka, both Of Japan 3,707,462 12/1972 Moss 208/127 Y 3,723,291 3/1973 Thakker... 201/17 [73] Asslgneei and Engneermg 3,803,023 4/1974 Hamner, 208/127 Co., Ltd., Tokyo, Japan [22] Filed: 1973 Primary Examinerl-lerbert Levine [21] App]. No.; 419,657 Attorney, Agent, or Firm-Howson and Howson [30] Foreign Application Priority Data [57] ABSTRACT Nov. 30, 1972 Japan 47-119367 Method for treatment of heavy oils characterized in [52] US. Cl 208/127; 48/197 R; 48/211 that a powdery or granular alkali metal compound in [51] Int. Cl. C10G 9/32 the heated state is fed to the coker independently [58] Field of Search 208/127, 226, 227; 201/17, from the starting oil to effect desulfurization of the 201 /20, 31 starting oil and to form granular coke, and the resulting granular coke is gasified with steam and oxygen or [56] References Cited air in the fluidized bed gasification furnace.

UNITED STATES PATENTS 2,320,118 5/1943 Blaker 208/226 6 Clams l Drawmg Us. Patent Oct.28,1975 3,915,844

METHOD FOR'TREATMENT OF HEAVY OILS The present invention relates to method for treatment of heavy oils.

In order to obtain fuels of low sulfur content from heavy oil, it may be considered that if a heavy oil such as asphalt can be decomposed with ease to be converted to either oil or gas, reduction of the sulfur content of the products will be performed very easily. As one of conventional methods for the treatment of heavy hydrocarbons of the petroleum type such as reduced pressure distillation residual oils, thermal cracking residual oils, tars, pitches or the like, of which methods were established based on the foregoing concept, there has been provided a method comprising thermally cracking such heavy hydrocarbon at a relatively low temperature of 400 to 650C, recovering cracked gases and light cracked oils, and then gasifying the resulting coke at a temperature of 800 to I200C.

.When a heavy oil is treated according to this method,

for example according to delayed coking of fluid coking processes, sulfur contained in the heavy oil at such a high content as 3 to 7% by weight is incorporated as hydrogen sulfide in the cracked gas and as an organic sulfur compound in the cracked oil and sulfur is further concentrated in the coke and the sulfur content is twice as high as in the starting oil. The majority of sulfur left in the coke is sandwiched between carbon lattice layers to form compounds together with carbon. Therefore, in case such coke is gasified, the porosity of the coke is damaged by such sulfur compounds and it is therefore not expected to increase the surface area, though the increase of the surface area is very advantageous for the coke gasification reaction.

Further, it is seen that in the case of the fluid coking process, cokes grow on fine coke nucleus in the layer form (onion-like form), and the resulting coke particles have high density and are hard, with further reduction of the porosity. Therefore, the rate of gasification as the result of reaction with oxygen or steam at high temperatures is much lowered and it is lower than in the case of amorphous carbon.

Further, in case a heavy hydrocarbon is coked according to the conventional method, since the oxygen content of the resulting coke is low, there is brought about a disadvantage that at the gasification step an excessive amount of oxygen is consumed in order to supply necessary reaction heat.

This invention is to provide a method for the treatment of heavy oils comprising coking a heavy oil such as asphalt, gasifying the resulting coke and thus recovering a readily desulfurizable light oil and a gas,

wherein an alkali metal compound is fed into a coker independently from asphalt to utilize it as a seed for formation of coke particles and form a readily gasifiable coke simulteneously with desulfurization of the resulting cracked gas and light cracked oil. By the term alkali metal compound used in the instant specification are meant carbonates, hydroxides and oxides of alkali metals such as Na, Li and K, compounds convertible to such compounds and mixtures thereof.

In general, when heavy hydrocarbons such as reduced pressure distillation residual oils, asphalt, heavy residual oils, pitches and tars are coked at a temperature of 400 to 650C by a fluidized bed coker, lighter hydrocarbon components of up to carbon atoms are converted to a cracked gas, and higher hydrocarbons are recovered in the form of a cracked oil, while the remainder is left in the form of cokes. Sulfur contained in the starting oil is incorporated into the cracked gas and light cracked oil mainly in the form of compounds formed together with hydrogen and hydrocarbons. Further, sulfur is also contained in the coke in the much concentrated state and it is present in the state combined directly with carbon or heavy metal, and these sulfur compounds are intruded in the lattice layers. On the other hand, when the resulting coke is gasified at a temperature of 800C, the content between the coke and the gasifying gas is performed only on the surface areas of coke particles and permeation of the gas into interiors of the particles is very difficult. Accordingly,

there is brought about a disadvantage that the rate of reaction of the coke with steam or oxygen is low.

In order to overcome these defects involved in the conventional techniques, according to the present invention, when a starting heavy oil is fed to a coker, a powdery or granular alkali metal compound in the heated state is fed to the coker independently from the starting oil and it is utilized as seed particles capable of promoting formation of granular coke, whereby an effect of desulfurization of the starting oil and an effect of forming readily gasifiable coke can be attained, and then the resulting granular coke is gasified with use of steam and oxygen or air.

More specifically, when the alkali metal compound heated at a temperature higher than the interior temperature of the coker is added to the coker, mist or vapor of the starting oil adheres on fine particles of the alkali metal compound and the volatile components of the starting oil are evaporated by the heat of the alkali metal compound, resulting in formation of fine particles of the coke. Further, fine particles of the alkali metal compound and mist or vapor of the starting oil are further stuck to the so formed fine particles of the coke and thus formed particles are stuck to each other to grow into larger particles and dry distillation is also performed at the same time. According to the conventional fluid coking process, oil components adhere on the coke nucleus and'dry-distilled by the heat received from the particle surface and oil components further adhere to the surface of the resulting coke particle and dry-distilled again, and as a result of the repetition of such adhesion and dry distillation, there are developed and grown large particles having an onion-like layer structure. On the contrary, in the process of this invention coke particles are formed in the form of aggregates of fine cokes which each coke is formed by utilizing one or more particles of the alkali metal compound as the seed.

Accordingly, in the process of this invention, the heat for gasification of volatile components is supplied from the alkali metal compound which is fed in the heated state to the coker and instantaneously incorporated and introduced into the starting oil, and therefore, the volatile components are transferred from the interior of oil drops toward the outer surface while undergoing dehydrogenation. Since the volatile components are thus gasified and they undergo the dehydrogenation reaction more extensively than in the conventional fluid coking process, the resulting coke has a better porosity and a low bulk density, which are charateristic properties of the coke obtained according to this invention.

As mentioned above, the alkali metal compound acts not only as the seed for formation of coke particles but also as the heating medium for promoting the dehydro- 'genation reaction in asphalt and gasifying volatile components in asphalt. Therefore, the granulation effect attained in the coker is much enhanced as compared with the case where only the starting oil is fed to the coker.

In case a heavy hydrocarbon containing a large amount of sulfur components such as thiophene, sulfides and disulfides is coked according to the customary delayed coking or fluid coking process, desulfurization is not accomplished but there is observed a tendency that the sulfur content is concentrated in the resulting coke.

In contrast, in accordance with the present invention, the sulfur components contained in the starting heavy oil are combined with the alkali metal compound just before formation of coke during the advance of the decomposition reaction and alkali metal sulfide compounds are formed, with the result that sulfur is not contained in the cracked gas or light cracked oil formed by coking of the heavy hydrocarbon, or in the resulting coke. If sulfur be contained in the resulting coke, its constant can be maintained at a very low level. It has been confirmed that during the coking reaction the alkali metal compound promotes the dehydrogenation reaction in the starting heavy hydrocarbon. Thus, in case an alkali metal compound is added according to this invention, the hydrogen content can be increased in the cracked gas, and also the oxygen content in the coke is 4 to by weight, which value is much higher than the oxygen content of about 1% by weight or less in ordinary cokes. These effects are especially conspicuous when the alkali metal compound is fed in the state heated at a temperature higher than the interior temperature of the coker.

In the gasification furnace the reaction is conducted at a temperature of about 800 to about 1200C, preferably 900 to 1000C. The coke prepared in the coker, which contains the alkali metal compound and a small amount of sulfide thereof is partially burnt with an aid of an oxidant such as oxygen or air and the unburnt coke is heated by the heat of this partial combustion, with the result that the coke is gasified by the reaction between the so heated high temperature coke and steam.

The alkali metal compound fed to the coker and its sulfide is forwarded to the gasification furnace in the form of the seed of the coke particle or in the state stuck to the formed coke particle. Such alkali metal compound and its sulfide exhibit a catalytic activity for forming such gases as carbon monoxide, hydrogen, car bon dioxide and methane by the reaction between the heated coke and steam, and therefore, the gasification of the coke can be performed advantageously. It has been known that carbonates and hydroxides of alkali metal such as Na, K and Li and mixtures thereof exhibit a catalytic effect in such reactions as the gasification of heavy hydrocarbons, the reaction between coke and steam, i.e., the aqueous gasification reaction, and the gasification of coal.

When the heavy hydrocarbon is coked in a coker according to this invention, sulfur components contained in the heavy hydrocarbon are reacted selectively with the alkali metal compound to form an alkali metal sulfide compound, and this sulfide compound is fed to the gasification furnace together with the unreacted alkali metal compound, where it is contacted with such gases as steam, carbon monoxide, hydrogen and carbon dioxide to release the sulfur as the rsult of the decomposition and it is regenerated to the original alkali metal compound, e.g., a carbonate or hydroxide, which is recycled to the coker.

As the alkali metal compound, there are employed carbonates and hydroxides of Na, Li, K and the like. They can be used singly or in the form of admixtures of two or more of them. The alkali metal compound can be directly fed to the coker as it is. It is also possible to feed the alkali metal compound in the state supported on an inorganic refractory or an alkaline earth metal compound. As the inorganic refractory, there can be mentioned, for example, alumina, murite, zirconia, chamotte, etc., and as the alkaline earth metal compound, there can be mentioned, for example, CaO, CaCO MgO, MgCO dolomite, etc. We have found that when the alkali metal compound is employed in the state supported on one or more of these compounds, the effect by addition of the alkali metal compound can be greatly enhanced.

The feature of this invention resides in utilization of theforegoing effects in combination. More specifically, the alkali metal compound to be fed to the coker as the seed for formation of particles and for reducing the sulfur content in the cracked products is utilized as the gasification catalyst in the gasification furnace and the sulfurized alkali metal compound is regenerated to the original alkali metal compound by an action of the reducing gas formed by the gasification reaction, which is recycled to the coker and used again as the heating medium for supplying the heat to the coker.

As is seen from the foregoing, the method of this invention is characterized in that the alkali metal compound heated at a temperature higher by at least C than the inside temperature of the coker is fed to the coker as the seed particle for formation and growth of granular coke independently from the starting heavy oil. Thus, according to the method of this invention, numerous fine particles of the alkali metal compounds are mingled in the heavy oil as seed particles for formation of coke particles at the step of coking of the heavy oil, whereby coke having a good porosity and being readily gasifiable can be obtained. Simultaneously, the alkali metal compound acts as the desulfurizing agent for reducing the sulfur content mainly in the cracked gas and light cracked oil. Further, the alkali metal compound acts as a catalyst for promoting the gasification of coke in the gasification furnace, and it is regenerated and heated in the gasification furnace and recycled to the coker as the heating medium. Thus, the alkali metal compound exhibits collective effects. The main feature of this invention resides in the use of an alkali metal compound in the process in which coke obtained by treating a heavy hydrocarbon in a fluidized bed coker is gasified according to the fluidized bed method.

This invention will now be described with reference to the accompanying drawing; in which:

The drawing is a simple flow sheet illustrating the method of this invention.

Referring to the drawing, the alkali metal compound is fed from an appropriate position 9 of a coker l independently from the starting oil fed from a position 4 of the coker. In order to supply heat to the coker, the alkali metal compound is fed in the state heated at a temperature higher by 100 to 500C than the interior temperature of the coker. The light cracked oil and cracked gas are withdrawn through a discharge system 7 and are treated at the subsequent steps.

In a gasification furnace 2, cokeformed in the coker l and transferred through a transfer conduit 12 is gasified at 800 to 1200C, preferably 850 to ll00C, by a gas, such as oxygen and steam, fed from a gas introduction system 5, and the resulting gas is withdrawn from a discharge system 8 and treated at the subsequent steps. Simultaneously, the alkali metal compound or sulfide fed to the gasification furnace in the state stuck to, or incorporated in the coke is partially regenerated by the so formed gas. The alkali metal compound acting as the catalyst and regenerated in the gasification furnace 2 is then withdrawn from the gasification furnace. In case the flow 6 recycled to the coker contains a large amount of unburnt coke and has a large particle size, it fails to act as the seed in the coker. In such case, in order to utilize the alkali metal compound flow 6 effectively as the seed for the coking reaction, it is possible to introduce a part of the alkali metal compound flow into a by-pass 10 and. feed it to a regeneration furnace 3, where it is heated. Thus, the so heated alkali metal compound is fed to the coker.

When a fresh alkali metal compound is heated and fed to to the coker, it is possible to add such fresh alkali metal compound to the flow of the heated alkali metal compound to be recycled to the coker, from an appropriate position 11.

EXAMPLE 1 Reduced pressure distillation residual oil of Gattisalan crude oil, which has properties shown in Table l, was fed at a rate of 3.0 kg/hr, together with fluidizing steam fed at a rate of 3.0 kg/hr, to a reaction vessel heated by an Elema type electric furnace, which comprises a stainless steel round tube having a length of 850 mm, a reaction zone inner diameter of 3 inches and an upper free board inner diameter of 6 inches and being equipped with a glass-blowing bottom opening having a reverse frustoconical form, an oil-blowing tube, a pipe for withdrawal of coke particles, a gas discharge pipe and a thermocouple-protecting pipe. An equimolar powdery mixture of Na CO and CaCO heated at 620C was continuously fed at a rate of 0.5 kg/hr to the reaction vessel from a powder feed pipe mounted on the upper portion of the reaction vessel indpendently from the starting oil and steam. In this manner, coking of the starting oil (reduced pressure distillation residual oil of Gattisalan crude oil) was conducted at a reaction temperature of 500C for an average coking time of minutes according to the method using a fluidized bed composed mainly of coke particles.

The resulting granular coke was continuously withdrawn from the reaction vessel and as a result of tests of the properties of the product, it was found that the product had an average particle size of 650 microns, a sulfur content of 0.4% by weight and a surface area of 230 m /gr.

l00gr of the so formed coke was packed in a cylindrical murite reaction tube having an inner diameter of 3 inches and length of 750 mm, and steam was introduced thereinto at a rate of 120 gr/hr while the reaction tube was heated from the outside by means of an Elema type electric furnace. Thus, the coke was gasified at 850C, 1000C and l200C to examine the influence of the gasification temperature on the degree of advance of the gasification reaction. It was found that the time required for completion of gasification of the coke was minutes at 850C, 31 minutes at 1000C and 10 minutes at 1200C.

The gasiflcation conditions are shown in Table 3 and results are shown in Table 4. The coking conditions and properties of the resulting coke are shown in Table 2 together with data of Example 2 and Comparative Examples 1 to 3.

EXAMPLE 2 The same reduced pressure distillation residual oil of Gattisalan crude oil as used in Example 1 was employed as the starting oil, and the same fluidized bed type reaction vessel as used in Example 1 was employed. An equimolar mixture of Na CO supported on alumina powder having a particle size not exceeding 30 microns was heated at 620C and was continuously fed at a rate of 0.5 kg/hr to the reaction vessel from a powder feed pipe mounted on the upper portion of the reaction vessel independently from the starting oil and steam. In this manner, coking of the starting oil was conducted at a reaction temperature of 500C for an average coking time of 20 minutes according to the method using a fluidized bed composed mainly of coke particles.

The resulting granular coke was continuously withdrawn from the reaction vessel, and as a result of tests of properties of the product, it was found that the product has an average particle size of 270 microns, a sulfur content of 0.5% by weight and a surface area of 200 m /gr.

Under the same conditions as in Example 1, gr of the so formed coke was gasified in the same gasification furnace as used in Example I. The time required for complete gasification of the coke was 83 minutes at a gasification temperature of 850C, 36 minutes at a gasification temperature of 1000C and 15 minutes at a gasification temperature of 1200C. The gasification conditions are shown in Table 3 and the results of the gasification are shown in Table 4.

The coking conditions and properties of the coke are shown in Table 2 together with data of Example 1 and Comparative Examples 1 to 3.

COMPARATIVE EXAMPLE 1 With use of the same fluidized bed type reaction vessel as employed in Example 1, the same reduced pressure distillation residual oil of Gattisalan crude oil as employed in Example 1 was coked at a starting oil feed rate of 3.0 kg/hr and a fluidizing steam feed rate of 3.0 kg/hr, at a reaction temperature of 500C for an average coking time of 20 minutes according to the method using a fluidized bed composed of coke particles.

The resulting granular coke was continuously withdrawn from the reaction vessel and as a result of tests of properties of the product it was found that the product has an average particle size of 650 microns, a sulfur content of 7.5% by weight and a surface area of 4.2 m /gr. Effects of reducing the sulfur content and increasing the surface area, such as attained in Examples 1 and 2, could not be attained in this Comparative Example.

Under the same gasification conditions as employed in Example 1, 100gr of the resulting coke was gasified with use of the same gasification furnace as employed in Example 1. The time required for complete gasificaing conditions and properties of the resulting coke are shown in Table 2 together with data of Examples and other Comparative Examples.

COMPARATIVE EXAMPLE 2 10 With use of the same fluidized bed type reaction vessel as used in Example 1, the same reduced pressure distillation residual oil of Gattisalan crude oil as employed in Example 1 was coked at a starting oil feed rate of 3.0 kg/hr and a fluidizing steam feed rate of 3.0 kg/hr, at a reaction temperature of 500C for an average coking time of minutes, while introducing a powder of an equimolar mixture of Na Co and CaCO maintained at room temperature at a rate of 0.5 kg/hr to the reaction vessel from a powder feed pipe mounted on the upper portion of the reaction vessel, according to the method using a fluidized bed composed mainly of coke particles.

The resulting granular coke was continuously withdrawn from the reaction vessel, and as a result of tests of properties of the product it was found that the product has an average particle size of 300 microns, a sulfur content of 0.5% by weight and a surface area of 130 m /gr. The effect of desulfurization of coke attained in this Comparative Example was comparable to that attained in Example 1 or 2, but the surface area was smaller than that obtained in Example 1 or 2.

COMPARATIVE EXAMPLE 3 With use of the same fluidized bed type reaction vessel as employed in Example 1, the same reduced pressure distillation residual oil of Gattisalan crude oil was coked at a starting oil feed rate of 3.0 kg/hr and a fluidizing steam feed rate of 3.0 kg/hr at a reaction temperature of 500C for an average coking time of 20 minutes according to the method using a fluidized bed composed mainly of coke particles. At this coking operation, an equimolar mixture of Na CO and CaCO was incorporated into the starting oil prior to its feeding to the reaction vessel, and mixture was fed to the reaction vessel together with the starting oil so that the feed rate of the mixture was 0.5 kg/hr.

The resulting coke was continuously withdrawn from the reaction vessel, and as a result of tests of properties of the product, it was found that the product has an average particle size of 700 microns, a sulfur content of 0.7% by weight and a surface area of 73 m /gr. No effect of increasing the surface area was observed in this Comparative Example.

Under the same conditions as employed in Example 1, 10 0gr of the coke was gasitied with use of the same gasification furnace as employed in Example 1. The time required for complete gasification of the coke was 300 minutes at a gasification temperature of 850C, 100 minutes at a gasification temperature of 1000C and minutes at a gasification temperature of 1200C.

The gasification conditions are shown in Table 3, and the gasification results are shown in Table 4.

The coking conditions and properties of the resulting coke are shown in Table 2 together with data of Examples and other Comparative Examples.

Under the same gasification conditions as employed 35 in Example 1, l00gr of the so formed coke was gasified Table 1 with use of the same gasification furnace as employed in Example 1. The time required for complete gasifica- Properties of Reduced Pressure Distillation Residual Oil of Gattisalan Crude Oil tion of the coke was 1 10 minutes at a coking temperature of 850C, 50 minutes at a gasification temperature Specific gravity (ZS/25C) 1.02 of 1000C and 23 minutes at a gasification temperature Psnwaflofl (25C) 86 f zoooc Sulfur content (7: by weight) 3.3 0 Conradson carbon The gasification conditions are shown in Table 3 and residue by weight) 19.1 the gasification results are shown in Table 4. The cok- 5 3 1 22; ems 225$ ram) ing conditions and properties of the coke are shown in v 492 Table 2 together with data of Examples 1 and 2 and other Comparative Examples.

Table 2 Coking Condition and Properties of Resulting Coke Example Example Comparative Comparative Comparative l 2 Example 1 Example 2 Example 3 Coking Conditions Starting oil feed rate (kg/hr) 3.0 3.0 3.0 3.0 3.0 Steam feed rate (kg/hr) 3.0 3.0 3.0 3.0 30 Alkali feed rate* (kg/hr) 0.5 0.5 O 0.5 0.5 Coking temperature (C) 500 500 500 500 500 Starting oil temperature (C) 300 300 300 300 300 Alkali temperature (C) 620 620 27 300 Coking time (minutes) 20 20 20 2O 20 9 Table 2 Continued Coking Condition and Properties of Resulting Coke inclusive of the amount of the refractory carrying the alkali metal compound.

From the results obtained in Examples 1 and 2 and Comparative Examples 1, 2 and 3, it will be seen that in case coking of the starting oil is conducted while feeding an alkali metal compound or an alkali metal compound supported on an inorganic refractory or an alkaline earth metal compound to the coking vessel independently from the starting oil, the resulting coke has a much lessened average particle size and an increased surface area, and that special good results are obtained when the alkali metal compound is fed in the state heated at a temperature higher than the coking temperature. It will be also understood that when the so obtained coke is gasifred at a high temperature, the time required for complete gasification can be greatly shortened, and that when an alkali metal compound or an alkali metal compound supported on an inorganic refractory or an alkaline earth metal compound is fed in the state heated at 620C (higher by 120C than the coking temperature), it is made possible to reduce the gasification reaction temperature by 100 to 150 C in order to obtain the same gasification time (reaction rate) as attained when the alkali metal compound is fed in the unheated state or the alkali metal compound is fed in the state incorporated in the starting oil.

What is claimed is:

1. In a method for treatment of heavy hydrocarbon coker feedstocks wherein the heavy hydrocarbon coker feedstock is coked in a fluidized bed coking furnace producing granular coke particles, and the resultant coke particles are gasified in a fluidized bed gasification furnace, the improvement comprising adding particles consisting of an alkali metal compound or an alkali metal compound supported on an inorganic refractory or an alkaline earth metal compound support medium to said coking furnace independently of the hydrocarbon coker feedstock, said alkali metal compound being heated to a temperature of C. to 500C. higher than the temperature in the coking furnace at the time said alkali metal compound is combined with said hydrocarbon coker feedstock in said coking furnace, whereby said particulate alkali metal compound acts as seed particles for the formation and growth of readily gasified granular coke particles having high porosity, high surface area, and high oxygen content during the coking process.

2. The method of claim 1 wherein said particulate alkali metal compound is a member of the group consisting of the carbonates, hydroxides and oxides of the alkali metals or mixtures thereof.

3. The method of claim 1 wherein said particulate alkali metal compound is sodium carbonate.

4. The method of claim 1 wherein said inorganic refractory support medium is a member of the group of alumina, zirconia, murite and chamotte.

5. The method of claim 1 wherein said alkaline earth metal compound support medium is a member of the group of calcium oxide, calcium carbonate, magnesium oxide, magnesium carbonate and dolomite.

6. The method of claim 1 wherein the alkali metal compound or alkali metal compound supported on an inorganic refractory or an alkaline earth metal compound support medium acts as a catalyst for the gasification of coke in the gasification furnace and is regenerated and heated in the gasification furnace and recycled to the coker furnace.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,915,844 Dated October 28, 1975 Inventor(s) Mikio Ueda et -1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 3, l. 23 "constant should be "content" Col. 6, 1. 16 Insert and 05100:; after "Na CO Signed and Sealed this tenth Day Of February 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner oflarems and Trademarks

Claims

1. IN A METHOD FOR TREATMENT OF HEAVY HYDROCARBON COKER FEEDSTOCKS WHEREIN THE HEAVY HYDROCARBON COKER FEEDSTOCK IS COKED IN A FLUIDIZED BED COKING FURNACE PRODUCING GRANULAR COKE PARTICLES, AND THE RESULTANT COKE PARTICLES ARE GASIFIED IN A FLUIDIZED BED GASIFICATION FURNACE, THE IMPRIVEMENT COMPRISING ADDING PARTICLES CONSISTING OF AN ALKALI METAL COMPOUND OR AN ALKALI METAL COMPOUND SUPPORTED ON AN INORGANIC REFRACTORY OR AN ALKALINE EARTH METAL COMPOUND SUPPORT MEDIUM TO SAID COKING FURNACE INDEPENDENTLY OF THE HYDROCARBON COKER FEEDSTOCK, SAID ALKALI METAL COMPOUND BEING HEATED TO A TEMPERATURE OF 100*C. TO 500*C. HIGHER THAN THE TEMPERATURE IN THE COKING FURNACE AT THE TIME SAID ALKALI METAL COMPOUND IS COMBINED WITH SAID HYDROCARBON COKER FEEDSTOCK IN SAID COKING FURNACE, WHEREBY SAID PARTICULATE ALKALI METAL COMPOUND ACTS AS SEED PARTICLES FOR THE FORMATION AND GROWTH OF READILY GASIFIED GRANULAR COKE PARTICLES HAVING HIGH POROSITY, HIGH SURFACE AREA, AND HIGH OXYGEN CONTENT SURING THE COKING PROCESS.