US20130061592A1

US20130061592A1 - Process for Maximization and Optimization of Coal Energy

Info

Publication number: US20130061592A1
Application number: US13/639,415
Authority: US
Inventors: Jayant Chandulal Mehta
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-03-01
Filing date: 2011-03-01
Publication date: 2013-03-14
Also published as: AU2011222370A1; WO2011108005A3; WO2011108005A2

Abstract

A process for maximization and optimization of coal energy comprising the steps of Selection of old coal mine or coal bearing areas; surveying of the mine or coal bearing areas for preparing of the panels; hydro-geological survey and Geo-Mechanical survey of the panels of Step-II above; sub paneling and slicing of the survey panels of the step-II and III above; preparing of the surface of the panel of step-IV above for development for at least boring of the panels; underground/Channeling of the boreholes at the floor level of the coal; burning of the coal in said channel of step-vi; extraction of the heat from the prepared boreholes seam & simultaneously filling of the voids created by extraction; use of the extraction heat for conversion into steam energy; use of the steam energy for generation of electricity or any other alternate use.

Description

FIELD OF INVENTION

The present invention relates to a process for maximization and optimization of Coal Energy, more particularly the present invention relates to a process which optimizes the coal energy utilization.

BACKGROUND OF THE PRESENT INVENTION

Coal is one of the most rich and abundantly available energy resources in the world. The need for the conservation and optimization of all the carbon generating energy resources are attracting the center stages at all international forums. The need for the optimum utilization of the available energy with minimal green house gas production is of utmost necessity.
The latest technology used worldwide cause huge losses of the coal energy. The presently known and utilized coal winning process results into generation of only 1/45 of available coal energy. The said figure is very and low and there was necessity to have a mechanism wherein the loss of energy can be saved and maximum utilization of energy is made possible.
The present mechanism for coal winning needs a complete revamp.

DRAWBACKS OF THE PRIOR ART

Winning in underground mines is hazardous process as working is against nature. Different hazards associated with underground mines are inundation, explosions (coal dust and methane); mine coal fires, roof and side falls, hazards due to machineries and electricity etc.
Maximum possible percentage of extraction with advance coal winning technology is ⅙ of commercial reserves. The disadvantages of opencast mines are degradation of coal, environmental pollution, degradation of fertile land, socio-economical problems, etc.
Disadvantages of U/G Coal gasification are uncontrolled coal fire poor coal gas quality.

OBJECTS OF THE PRESENT INVENTION

Object of the present invention aims at developing a process for maximization and optimization of coal energy.
Object of the present invention is to develop a process, wherein the loss of coal energy during the course of the coal winning can be saved.
Another objective of the main invention is to maximize the production of coal generation and use the same for generation of power.
Yet another objective of the present invention is to maximize the power generation from coal which can result into reduction of cost for power generation.

STATEMENT OF THE INVENTION

According to this invention, therefore, a process for maximization and optimization of coal energy comprising the steps of

- i) Selection of old coal mine or coal bearing areas;
- ii) Surveying of the mine or coal bearing areas for preparing of the panels;
- iii) Hydro-geological survey and Geo-Mechanical survey of the panels of Step-II above;
- iv) Sub paneling and slicing of the survey panels of the step-II and III above;
- v) Preparing of the surface of the panel of step-IV above for development for at least boring of the panels;
- vi) Underground channeling of the boreholes at the floor level of the coal seam. vii) Burning of the coal in said channel of step-vi;
- viii) extraction of the heat from the prepared boreholes & simultaneously filling of the voids created by extraction;
- ix) use of the extraction heat for conversion into steam energy;
- x) use of the steam energy for generation of electricity or any other alternate use.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described with reference to the accompanying drawings wherein:

FIG. 1 shows the Panel preparation

FIG. 2 shows Plan of Mine

FIG. 3 shows Panels divided into slices

FIG. 4 shows Developed Mine Plan

FIG. 5 shows Borehole pattern

FIG. 6 shows Slice extraction

FIG. 7 shows Extraction of Virgin seam

FIG. 8 shows 3 D view showing ascending extraction of slices

DETAILED DESCRIPTION OF THE INVENTION

The technology derived is the outcome of the experience gained in coal winning methods during my experience of 30 years and from following process that need to be studied in detail such as:

- Coal winning methods
- Working of Thermal Power Plant
- Experience gained from different technologies such as underground coal gasification
- Technologies used to tackle Zaria coal fire
- Advanced drilling technologies used in oil industry
- Dewatering technique used in lignite mining of Naivelly to produce coal at mean sea level
- Methane drainage technique, heat collecting pumps used in geothermal power plants
- Underground coal winning technologies
- Long-wall & B&P (board and pillars) depillaring with caving and stowing
- Isolation of fire area from surface technology
- Roof and floor rock mass of coal
- Transportation of steam
- Shaft sinking in difficult conditions
- Water infusions &pulse infLisions
- Ventilation of long headings.

The Outcome of all the Above Experiences and Studies Shows That:—

- We are using only 1/45 part of coal energy
- All the studies are carried out only to control fire. i.e fire is taken as liability besides only way to use coal energy is by combustion.
- Uncontrolled fire in coal seam is only problem to use coal energy insitu.
- The technology developed make it absolutely possible to keep coal fire under total control and exploit coal energy left in abandoned mines, deep seated coal seams, thin coal seams (less than 1.2 meters) in maximum percentage.

Stages of Technology:—

- Preparation of panels, sub panels and slices
- Development for extraction of panels
- Extraction of coal energy and using the extracted coal energy for power generation and other industrial usages.
- Partial filling while extraction progress and complete airtight fillings of voids created by extraction
- Abundance of boreholes shifting equipment's to next slices
- Restoring the surface visual impact and using the same surface for prior use

Preparation of Panels and Sub Panels:—

The working will be kept in isolated panel from other workings by airtight isolation. The panel preparation will facilitate sub-surface dewatering and uninterrupted working of panel due to water problem especially in case where aquifers are present.
The extraction of panels in line of extraction will reduce the isolation work in companion panels. Extraction of number of panels at time is possible. Panel size is such that preparation cost is least and extraction is economical. The presence of geological disturbances faults, folds, also need to considered.
Technological experiences used in preparation of panels. Technologies used in shaft sinking in difficult condition, preparation of blocks, freezing or cementation will be applied which is given in detail below.
Isolation of panel from other workings by remote isolation method used in remote sealing of fire by constructing leak proof (air tight) isolation. Dewatering of blocks, sub ground water drainage used in Naivelly lignite

- Advantages of paneling
  - 1) Number of panels worked at a time
  - 2) Dewatering water available in panel block used for power generation superheated steam produced etc. will make needful water for process and need not necessary to arrange external water supply

1.1.1. Need for Preparation of Sub-Panel & Slices

- Subpanel is divided into number of slices for extraction of coal energy at a time
- Slice area is kept in such a way that the area of slice exposed to roof is kept in such a way that the roof will not fall and facilitate complete extraction of slice. Number of slices in a panel of different subpanel will be worked at a time as shown in fig no 3 extraction of slice and sequence of extraction of the same
- The number of panels (slices) worked at a time will decide the capacity of generation unit. To ensure uninterrupted supply of superheated steam is . achieved fixing the relation for above maximum capacity of generation is possible
- If complete extraction of heat up to cooling of roof rock to certain decided temperature is achieved it will facilitate uncontrolled spreading of fire
- Filling of extracted slices with stowing material that is having strength of solid coal will facilitate keep fire in control and controlling roof movement to achieve complete extraction of coal energy

Barrier left in slice extraction will be extracted while working adjoining slices after complete extraction of heat in the slice (complete process and exhausted).
2.

3. Different Stages of Technology

Stage 1:

3.1.1. Preparation of Sub Panels and Slices
1) Size of panel-geo mechanical property of roof rock will decide the size of the slices.
2) Factors controlling preparation work

- Abandoned mines
- Developed and standing on pillars
- Virgin coal seam
- Type of mining method used for extraction
- Seam density
- Geo hydrological survey report
- Accuracy of plans

3) Capacity of drilling equipment's and accuracy of drilling holes are the major factors controlling the panel preparation.
Once the size of panel is decided preparation of the slice extraction can be started. Further in developed working the slice is isolated by remote isolation technique. In virgin seam the isolation procedure need not be followed.
The development work is as shown in the FIG. 5 & FIG. 8

Stage 2:

3.1.2. Development Work for Extraction of the Slices
After completing the panels, sub panels and slices isolation work development work for extraction of slices starts. The seam is approached by set of boreholes for coal energy extraction and boreholes for filling of voids.
Number of exhaust and inlet service borehOles for providing air to working area and extraction of heat.
The number of boreholes, diameter of boreholes and positioning of boreholes depends upon certain determining factors such as

- Finding of geo mechanical studies. i.e. roof rock strength
- Permitted maximum exposure
- Thickness of seam
- The pattern depends on extraction of developed working or virgin seam
- Seam density, if seam density is more it needs close spacing to achieve complete filling of voids so as to make complete extraction of coal energy possible
- Design capacity of heat extraction
- Capacity of heat extraction pumps
- Area needed for installation of pumps
- Position of heat extraction pumps i.e vertical or horizontal
- Number of units of heat extraction pumps
- Quantity of coal on fire to generate desired quantity of heat
- Quantity of air to achieve desired quantity of coal on fire

Size and number of stowing boreholes depends on certain factors such as

- Size of stowing material
- Type of material used
- Technique used to flush stowing material either by hydraulic or pneumatic or by simple dropping system
- Thickness of coal seam
- Gradient of coal seam
- Density of coal seam
- Rate of stowing for filling voids
- Tightness & strength of filling material to be achieved
- Need of cement slurry or foam injection to complete compactness and air tightness of voids

By taking into consideration above factors the designing of the borehole pattern will be done and accordingly the seam will be approached After the seam is approached by boreholes, the next step of development will be Driving channels—for connection between boreholes (i.e. inlet and outlet) channels at floor portion of seam has to be driven Fitting of burners attached to coil tubing in the channels
Technologies, experience used in preparation of subpanel and slices

- Remote isolation of fire area with complete airtight seal
- Geothermal energy based power plant units
- Experience in heat extraction pumps, its design and capacity, installation and its efficiency used in geothermal power plants
- Ventilation of fire area while tackling underground coal fires
- Different mechanical ventilators used for mine ventilation as used for ventilation of long drive up to 1000 meter or more single entry particularly used in long wall
- Design of mine ventilation
- Experience gained in different stowing practices such as hydraulic, mechanical or pneumatic
- Technology used in gasification of coal seam to create channel in coal seam using special drilling technique
- Technology used in underground gasification of use of a burner attached to the coil tubing. The burner is used to burn through boreholes casing and ignite coal. The ignition system can be moved to any desired location in injection well. Thus ‘control reaction ignition point’ (CRIP) technique enables a new reactor to be installed at any chosen upstream location, after the decline reactor has been abandoned

3.1.3. Stage 3:
3.1.4. Extraction Method for Extracting Coal Energy from Slices
After completing development work extraction of panel will be started.

Manner of Extraction of Coal Energy

- The coal seams, panels, slices are extracted in ascending manner as shown in FIG. 7
- Panel, slices are extracted in designed line of extraction (the line of extraction may change according to condition)

Procedure for Coal Energy Extraction:

By ‘Control Reaction of ignition Point’ (CRIP) coal is ignited at bottom most portion of slice. Ventilation of working area beside buoyancy (hot gases in exhaust, content of moisture, etc.) is necessary by mechanical means as to control the quantity of coal on fire & quantity of heat generated and also to carry out heat generated to heat extraction pumps.
The slice will be extracted by different compartments to facilitate complete extraction of coal energy within the permitted area of exposure. As shown in FIG. 6 the sequences of extraction of slice in compartment.
Air shall be kept blowing in inlet & heat extracted in exhaust bore holes to produce superheated steam directly used for driving turbine. Further steam produced can be used to flash power plant that needs 6000 kgs-9000 kgs of steam each hour to produce each MW of electrical power. This is for maximum possible use of heat produced.
3.1.5.
3.1.6. Stage 4:
3.1.7. Partial filling while extraction progress and complete airtight fillings of voids created by extraction
As the bottom coal is extracted the exposure of top coal is available for oxidation, as ash falls down and gets a dome shape.
As coal combustion at work place reaches to stowing boreholes, forming certain voids, partial filling of voids by stowing material should be started. The Pneumatic stowing is suitable as complete filling of void is possible within slice.
The extraction height is kept within limit as less as possible by continuous partial filling of voids (as low as 1.5 meters or less). It will facilitate more area of exposure as height of extraction has direct effect on roof fall
After completion of slice extraction the heat generation will fall

- Continue the heat extraction till the roof rock temperature reduces to certain designed temperature.
- The voids should be complete filled even inlet and exhaust holes can be used for the purpose.
- Injection of cement slurry, foaming material to make air tight to facilitate compaction along roof.
- Achieve the strength of filling to facilitate working of seams above uninterrupted

The FIG. 5 will show the extraction of slices in compartment.
Simultaneous extraction of 1^st& 2^ndcompartment and after extraction & complete filling working of 3^rdcompartment will be started.
The completion of slice in lower coal seam and for extraction of upper seam, same set of boreholes will be used for extraction of upper seam and same procedure will be adopted as in case of lower coal seam.
3.1.8. In certain cases the fire in coal seam is difficult to achieve so it is necessary to prepare coal for easy fire. The preparation is needed in bottom most coal where coal to enlighten needs to develop cracks in coal seam. These cracks in coal seam can be developed by advance water infusion under pressure to open the cracks and fast advancement of fire with aid of pressure air difference between Inlet and outlet boreholes.
The fig will give the sequence of extraction of adjoining slices and slices in upper seam.
Number of slices in one panel in different seams or within panels will be worked simultaneously in keeping certain sequence as shown in FIG. 3 & 8.
Number of slices simultaneously work depends on following factors:

- Infrastructure available for drilling
- Funds available
- Size of generator and requirement of superheated steam
- The provision of simultaneous extraction of slices will facilitate
- Uninterrupted supply of steam
- Planning of high generation capacity plants

Methane (CH4) formed as emission or distillation of coal burnt below heat extraction pump by installing activated platinum wire gauze and heat generated will be used for stem generation.
Different Technologies and Experiences Used in Extraction of Coal Energy

- Methane drainage system
- Methane explosibility
- Ventilation of mine
- Interpretation of samples of air in different stages of coal fire
- Development workings in coal seam effect of height of gallery on roof control
- Experience in Zaire coal fire to reduce rate of fire travel particularly by circulation of liquid Nitrogen through bore holes for cooling down the roof rock.
- Checking packing of galleries and making airtight seal in remote sealing of fire area.
- Extraction of coal in ascending method with stowing
- Extraction of coal in multi seam mines
- Technologies used in detection of CH4 in M.S.A methanometer.
- Boundary ventilation system used in metal underground mines
- Product of coal combustion and exhaust treatment in thermal power stations.
- Infusion of coal by pressure water, shock or pulse infusion of coal seam
- Directional drilling technique
- Continuous sampling of mine air technique
- Fire in coal stock

Stage 5:

Abundance of boreholes shifting equipment's to next slices
After completing the extraction procedure of slices subpanels and panels to the topmost seam the boreholes are left abundant.
3.1.9.
3.1.10. Stage 6:
3.1.11. Restoring the Surface Visual Impact and Using the Same Surface for Prior Use
3.1.12. Restoring the surface visual impact will be done as per the EMP-Environmental Management Plan.

SUMMARY OF THE PRESENT INVENTION

A coal mine is initially divided into number of panels preferably of 200/200 meters and the said panels are divided further in to sub panels of 45/200 meters. The said panels are thereafter converted into the dewatered compartments. The said compartments are thereafter provided with the boreholes of diameter of 24″. The stowing is done by bore of small 8″ diameter.
Thereafter fire is enlightened in the coal seam by using the advance torch technology. The controlled and predetermined air is infused in sub panel during the combustion of coal to keep the fire in control. The extraction of heat is also done in controlled manner in order to maintain the combustion in the advanced stage, thereby reducing the emission of green house gases like Carbon Monoxide or Hydrogen. The same is further achieved by filing the voids formed by the combustion of coal. The panels are selected in such a manner that the roof of the panels shall not fall at any point of time during the process.
Thereafter the heat generated from the combustion can be utilized for generation of power by using the state of art technology.

ADVANTAGES OF THE PRESENT INVENTION

- 1. The process is capable to bring down the cost of electricity 40-50 paisa/unit.
- 2. There is no need of vigorous R & D it can be conceptualized by unification and modification of available technologies used in Thermal Power Station (hereinafter called as T.P.S.) and mining.
- 3. This process is capable of using coal energy from already abandoned mines, unworkable coal seams and even for coal seams, which are 1.2 meters thick, hence, exploitation of larger reserves of coal is possible.
- 4. Maximum % utilization of coal energy is possible as compared to other technologies possible in the arena of electricity generation.
- 5. It is also safer and intuitively more efficient because of lowers emission fugitive dust, noise and visual impact of the surface, lower water consumption, no dirt handling and disposal at mine sites, no coal washing and fines disposal at mine sites, no ash handling and disposal at power station sites, no coal stocking and transport, no mine water recovery and significant surface hazard liabilities on abandonment.
- 6. The process is free from degradation of land and has comparatively less environmental impact with potential of lowering the overall capital and operation cost.
- 7. The process will revolutionize the generation or power both cost wise and technology wise and will be able to meet the need of 3,00,000 MW/Day persistently for 3500 years.
- 8. The process will not lead to emission of the green house gases.
- 9. It will prove to be best alternative to nuclear energy, which cost about (6.50 Rs/unit) and ensure health & security.

Claims

1. A process for maximization and optimization of coal energy comprising the steps of:

i) selecting old coal mine or coal bearing areas;

ii) surveying the mine or coal bearing areas for preparing of survey panels;

iii) conducting a hydro-geological survey and a geo-mechanical survey of the panels of step ii above;

iv) sub paneling and slicing of the survey panels of steps ii) and iii) above;

v) preparing the surface of the panel of step iv) above for development for at least boring of the panels;

vi) underground/channeling of the boreholes at the floor level of the coal;

vii) burning of the coal in said channel of step-vi;

viii) extraction of the heat from the prepared boreholes seam and simultaneously filling of the voids created by extraction;

ix) use of the extraction heat for conversion into steam energy; and

x) use of the steam energy for generation of electricity or any other alternate use.

2. The process as claimed in claim 1, wherein, the compaction and strength shall be of the coal removed from the slices.

3. (canceled)