WO2013155560A1 - Improved underground coal gasification method and apparatus - Google Patents
Improved underground coal gasification method and apparatus Download PDFInfo
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- WO2013155560A1 WO2013155560A1 PCT/AU2013/000397 AU2013000397W WO2013155560A1 WO 2013155560 A1 WO2013155560 A1 WO 2013155560A1 AU 2013000397 W AU2013000397 W AU 2013000397W WO 2013155560 A1 WO2013155560 A1 WO 2013155560A1
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- WIPO (PCT)
- Prior art keywords
- metal salt
- salt solution
- pressurised
- oxidant
- underground coal
- Prior art date
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- 239000003245 coal Substances 0.000 title claims abstract description 94
- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000002309 gasification Methods 0.000 title description 24
- 238000002485 combustion reaction Methods 0.000 claims abstract description 62
- 229910052751 metal Inorganic materials 0.000 claims description 118
- 239000002184 metal Substances 0.000 claims description 118
- 239000012266 salt solution Substances 0.000 claims description 95
- 239000007800 oxidant agent Substances 0.000 claims description 49
- 230000001590 oxidative effect Effects 0.000 claims description 49
- 239000006185 dispersion Substances 0.000 claims description 33
- 239000007789 gas Substances 0.000 claims description 28
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 14
- 239000003595 mist Substances 0.000 claims description 13
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 12
- 239000001301 oxygen Substances 0.000 claims description 12
- 229910052760 oxygen Inorganic materials 0.000 claims description 12
- 238000002347 injection Methods 0.000 claims description 11
- 239000007924 injection Substances 0.000 claims description 11
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 11
- 239000002245 particle Substances 0.000 claims description 9
- 239000007864 aqueous solution Substances 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- 229910000008 nickel(II) carbonate Inorganic materials 0.000 claims description 5
- ZULUUIKRFGGGTL-UHFFFAOYSA-L nickel(ii) carbonate Chemical compound [Ni+2].[O-]C([O-])=O ZULUUIKRFGGGTL-UHFFFAOYSA-L 0.000 claims description 5
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 5
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 5
- AYJRCSIUFZENHW-DEQYMQKBSA-L barium(2+);oxomethanediolate Chemical compound [Ba+2].[O-][14C]([O-])=O AYJRCSIUFZENHW-DEQYMQKBSA-L 0.000 claims 2
- 239000000047 product Substances 0.000 description 18
- 239000003054 catalyst Substances 0.000 description 14
- 150000003839 salts Chemical class 0.000 description 11
- 238000004519 manufacturing process Methods 0.000 description 10
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 8
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 150000002739 metals Chemical class 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000010276 construction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 230000000737 periodic effect Effects 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 2
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 125000005575 polycyclic aromatic hydrocarbon group Chemical group 0.000 description 2
- 238000000197 pyrolysis Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- QGJOPFRUJISHPQ-UHFFFAOYSA-N Carbon disulfide Chemical compound S=C=S QGJOPFRUJISHPQ-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- 239000002956 ash Substances 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 238000012824 chemical production Methods 0.000 description 1
- 150000003841 chloride salts Chemical class 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000004071 soot Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 229910021653 sulphate ion Inorganic materials 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 229930192474 thiophene Natural products 0.000 description 1
- 150000003577 thiophenes Chemical class 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
- 150000003738 xylenes Chemical class 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
- E21B43/243—Combustion in situ
Definitions
- This invention relates to a method and apparatus for increasing the rate of coal combustion within a combustion zone of an underground coal gasifier.
- a method and apparatus for introducing a metal salt solution into a combustion zone of an underground coal gasifier are disclosed.
- Underground coal gasification is a process by which product gas is produced from a coal seam by combusting and gasifying the coal in situ in the presence of an oxidant.
- the product gas is typically referred to as synthesis gas or syngas and can be used as a feedstock for various applications, including clean fuels production, chemical production, and electricity generation .
- Wells are drilled into the coal to allow for oxidant injection and product gas extraction.
- the wells are linked or extended to form an in-seam well channel (also referred to as a "linkage channel") to facilitate oxidant injection, cavity development and product gas flow.
- the well allowing the injection of oxidant is called an injection well.
- the well from which product gas emerges is called a production well.
- Both horizontal and vertical well regions can be used for injection and production.
- Underground coal gasification can also utilise one or more vertical wells (service wells) located between the injection and production wells.
- a coal seam having an injection well and a production well, with a well channel linking the two wells is typically referred to as an underground coal gasifier.
- the gasifier will have a combustion zone within which coal is combusted in the presence of an oxidant, a gasification zone located downstream of the combustion zone in which coal is gasified and partially oxidized to produce product gas, and a downstream pyro lysis zone in which pyro lysis of coal occurs.
- Hot product gas flows downstream from the gasification zone and exits the ground from a well head of the production well.
- a gasifier (gasification) cavity within the coal seam develops and grows in size.
- the product gas generated by UCG typically includes syngas as well as other components, and the constituency will depend on various factors, including the type of oxidant used for UCG (e.g., air or oxygen), water conditions (both ground water and exogenous water), coal quality, and UCG operating temperature and pressure.
- oxidant e.g., air or oxygen
- water conditions both ground water and exogenous water
- coal quality e.g., coal quality, and UCG operating temperature and pressure.
- UCG product gas will contain: (1) main syngas components (e.g., CO, H 2 , C0 2 , N 2 , and CH ); (2) solid particles/particulates (e.g., soot, ash, and coal particles); (3) water; (4) minor components such as C 2 -C6 hydrocarbons, oxygen, argon, sulphur containing components (e.g., H 2 S, COS, CS 2 , mercaptans, and thiophenes), nitrogen based components (e.g., NH 3 and HCN), hydrocarbon components (e.g., coal condensate, BTEX (benzene, toluene, ethylbenzene and xylenes), and PAHs (polycyclic aromatic hydrocarbons)); and (5) trace components such as heavy metals (arsenic and mercury) and chlorides.
- main syngas components e.g., CO, H 2 , C0 2 , N 2 , and CH
- An object of the present invention is to provide a method and apparatus for UCG that minimises one or more of the disadvantages of the prior art.
- the present inventors have now developed a method and apparatus for increasing coal combustion and appropriate gasification zone development within an underground coal gasifier, with concomitant improvement of coal resource recovery.
- a method of increasing the rate of coal combustion within a combustion zone of an underground coal gasifier including the step of introducing a metal salt solution into the combustion zone of the underground coal gasifier so as to increase the rate of combustion of the coal in the combustion zone over that achievable using an injected oxidant alone.
- the metal salt solution can be introduced into the combustion zone of the underground coal gasifier in any suitable way and in any suitable form.
- the metal salt solution can be injected into the combustion zone together with an oxidant such that the oxidant acts as a carrier for the metal salt solution.
- the injected oxidant can mix with the metal salt solution to form a dispersion (i.e., metal salt solution particles dispersed in gaseous oxidant) that promotes combustion of coal.
- the dispersion can include metal salt solution drops/particles of any suitable size.
- the metal salt solution drops/particles have an average size of anywhere between about 10 and 40 microns, including about 15, 20, 25, 30, or 35 microns (i.e., a metal salt solution mist).
- the metal salt solution is dispersed within a pressurised oxidant and the pressurised metal salt solution dispersion is used for injection into the combustion zone of the underground coal gasifier.
- the oxidant is supplied to the combustion zone of the underground coal gasifier at a pressure of between about 10 and 30 atmospheres, although pressures of about 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, or 40 atmospheres can be used.
- metal salt solution can be used.
- the metal salt can be consumed in a chemical reaction occurring in the combustion zone of the gasifier, or can function as a catalyst (i.e., the metal salt is not necessarily consumed).
- Preferred types of metals include sodium and potassium, as well as other alkali metals of Group 1 of the periodic table (IUPAC numbering).
- Preferred types of metals also include barium and calcium, as well as other alkali earth metals of Group 2 of the periodic table.
- Yet other preferred types of metals include nickel and other transition metals of Group 10 of the periodic table (nickel family metals).
- the metal salt can be a metal carbonate, sulphate or nitrate for example.
- the metal salt solution is an aqueous solution of potassium carbonate (K 2 CO 3 ), sodium carbonate (NaiCOs), barium carbonate (BaC0 3 ), or nickel carbonate (NiC0 3 ), as well as mixtures thereof.
- the preferred catalytic metal salt is sodium carbonate.
- any suitable concentration of metal salt can be introduced into the combustion zone of the underground coal gasifier, preferably about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ,13, 14, 15, 16, 17, 18, 19, 20, 21, 22 , 23, 24, 25, or even up to about 50%
- weight/weight metal salt can be injected with oxidant; preferably as a pressurised metal salt solution dispersion.
- the metal salt solution can be mixed with oxidant at any suitable ratio, including a ratio of approximately 95-80% volume/volume oxidant to 5-20% volume/volume metal salt solution.
- the injected oxidant which can act as a carrier stream for the metal salt solution, can be any suitable type of fluid or fluids.
- the oxidant is preferably a gas such as air
- the oxidant source can include an air compressor, a tank/cylinder of compressed air or oxygen, an air separation unit, or a tank/cylinder of liquid oxygen.
- the metal salt solution can be introduced into the combustion zone of the underground coal gasifier by way of an injection well or a service well.
- a pressurised metal salt solution dispersion supply system for increasing the rate of coal combustion within a combustion zone of an underground coal gasifier, the system including: a) a source of pressurised metal salt solution dispersion and b) a supply pipe having an inlet connected to the source of pressurised metal salt solution dispersion and an outlet connectable to a well head of a well of the underground coal gasifier for injecting the pressurised metal salt solution dispersion into the combustion zone of the underground coal gasifier.
- a pressurised metal salt solution dispersion supply system for increasing the rate of coal combustion within a combustion zone of an underground coal gasifier, the system including: a) a source of metal salt solution, b) a source of pressurised oxidant, and c) a supply pipe having (i) an oxidant inlet connected to the source of the pressurised oxidant, (ii) a metal salt solution inlet connected to the source of the metal salt solution and including a fogger for forming a metal salt solution mist that mixes with the pressurised oxidant within the supply pipe to form a pressurised metal salt solution dispersion, and (iii) an outlet connectable to a well head of a well of the underground coal gasifier for injecting the pressurised metal salt solution dispersion into the combustion zone of the underground coal gasifier.
- the fogger also known as a mister or sprinkler
- the fogger produces metal salt solution drops/particles having an average size of anywhere between about 10 and 40 microns, including about 15, 20, 25, 30, or 35 microns.
- the fogger can spray a metal salt solution mist at a controlled rate into the supply pipe, such that a ratio of approximately 95-80% volume/volume oxidant to 5-20%
- volume/volume metal salt solution mist is achieved.
- the pressurised metal salt solution dispersion supply system can include at least one tank containing the metal salt solution and this tank can be of any suitable size, shape and construction.
- the tank can have a capacity of about 150 to 200 litres.
- the inlet for the metal salt solution can extend to within the supply pipe from the bottom of the tank.
- a control valve of the system associated with the inlet for the metal salt solution can control the flow rate of the metal salt solution there through.
- the tank can have an oxidant inlet connected to the supply pipe for receiving the oxidant so as to place the source of the metal salt solution under pressure, as well as to ensure proper mixing of the tank's contents.
- a control valve associated with the oxidant inlet can regulate the flow of compressed oxidant into the tank for the metal salt solution.
- the pressurised metal salt solution dispersion supply system can include two or more tanks containing the metal salt solution, such that one tank can be used whilst the other tank is being filled (including refilled) or serviced.
- the supply pipe can be of any suitable size, shape and construction.
- the supply pipe can have an inner diameter of about 150 to 300 mm, including about 175, 200, 225, 250, or 275 mm.
- the supply pipe has an inner diameter of about 160 mm.
- the supply pipe also includes an outlet that can connect to a well head of a well of an underground coal gasifier. This coupling can be achieved in any suitable way.
- the supply pipe preferably feeds the well of the underground coal gasifier a pressurised metal salt solution dispersion
- a pressurised metal salt dispersion including a metal salt solution dispersed in a pressurised oxidant for increasing the rate of coal combustion within a combustion zone of an underground coal gasifier.
- Figure 1 is a cross sectional view of a pressurised metal salt solution dispersion supply system, according to an embodiment of the present invention.
- Figure 2 is a transverse cross-sectional view (through plane A- A) of that shown in Figure 1.
- Figure 3 is an enlarged cross sectional view of a fogger of the supply system shown in Figure 1.
- Figure 4 depicts use of the supply system of Figure 1 for increasing the rate of coal combustion within a combustion zone of an underground coal gasifier, according to an embodiment of the present invention.
- the present inventors have now developed a method and apparatus for increasing the rate of coal combustion in an underground coal gasifier by introducing a metal salt solution (also referred to herein as a "metal catalyst") into a combustion zone of the gasifier in an oxidant carrier stream (e.g., an air stream).
- a metal salt solution also referred to herein as a "metal catalyst”
- an oxidant carrier stream e.g., an air stream
- Metal catalyst(s) Amount of metal catalyst within Monochromatometre reading for time taken pressurised air (% mass) for complete gasification (seconds)
- the results of Table 1 show that various metal salt catalysts shorten the time taken to gasify coal samples.
- the catalytic activity can be ranked as follows (from highest to lowest activity): K 2 C0 3 > Na 2 C0 3 > BaC0 3 > NiC0 3 .
- the present invention includes using metal salt catalysts (such as a 2 C0 3 ) in an oxidant carrier stream (such as pressurised air) as a means of increasing the rate of coal combustion to: (i) increase the coal recovery rate, (ii) increase the CO and H 2 content of product gas and (iii) reduce the volume of oily water by-product (coal/gas condensate) that is normally isolated from a raw product gas stream.
- metal salt catalysts such as a 2 C0 3
- an oxidant carrier stream such as pressurised air
- the inventors' pressurised metal salt solution dispersion supply system 1 for increasing the rate of coal combustion within a combustion zone of an underground coal gasifier (over that achievable using an injected oxidant alone) is shown in Figures 1-4.
- the system 1 includes a source of metal salt solution catalyst 4a, 4b, a source of pressurised air 5 (i.e., oxidant), a supply pipe 6 and a fogger 7
- the source of metal salt solution 4a, 4b includes two cylindrical 170 litre tanks 8a, 8b, each capable of containing a metal salt solution (5-20% weight/weight sodium carbonate) and operable independently of one another.
- Each tank 8a, 8b has an inlet 50a, 50b for receiving the metal salt solution and an isolation valve 51a, 51b.
- Each tank 8a, 8b has an inlet 9a, 9b extending to the supply pipe 6 for receiving compressed air so as to place the metal salt solution under pressure and to ensure proper mixing of the tank contents.
- a control valve 10a, 10b of the system 1 associated with each inlet 9a, 9b regulates the flow of compressed air into each tank 8a, 8b.
- Each inlet 9a, 9b has a plurality of outlets 41a, 41b for air positioned along a lower region of the tank 8a, 8b.
- the source of pressurised air 5 is an air compressor 13.
- the supply pipe 6 has an inlet 11 connected to the air compressor 13, a branched inlet pipe 14a, 14b with a branch extending to each tank 8 a, 8b, and an outlet 15 connectable to a well head 17 of a well 30 of an underground coal gasifier for injecting the pressurised metal salt solution dispersion into a combustion zone of the gasifier of a coal seam 2 (as seen in Figure 4).
- the supply pipe 6 has an inner diameter of about 160mm (but it could equally be about 180 to 200 mm).
- the supply pipe outlet 15 can couple with the well head 17 of a well 30 of an underground coal gasifier, as depicted in Figure 4.
- the fogger 7 (also known as a sprinkler or mister) is connected to an end of the inlet 14a located within the supply pipe 6. Further details of the fogger 7 can be seen in figure 3 (which is a third party commercially available fogger).
- the fogger 7 has a tubular body 70, a channel 71 and a head 72. As the metal salt solution flows through the channel 71 of the body 70 and past the head 72, it is converted into a mist. The fogger 7 converts the pressurised metal salt solution into a mist of particles having an average size of anywhere between about 10 and 40 microns.
- the metal salt solution mist mixes with the compressed air within the supply pipe 6 at a ratio of approximately 95-80% volume/volume pressurised air to 5-20%
- Control valves 20a, 20b of the system 1 associated with the inlet 14a, 14b regulate the flow of the metal salt solution to the fogger 7 and can be adjusted to vary the ratio according to conditions within the underground gasifier and the composition of combustibles within the produced product gas.
- the delivery system 1 is coupled to the well head 17 of the well 30 of an underground coal gasifier.
- the well 30 includes a 128-300 mm metal pipe 22 that is encased in concrete.
- the coal seam 2 is, for example, located approximately 180-250 m below ground level.
- tanks 8a, 8b are filled with a metal salt solution via inlet 50a, 50b.
- Tank 8a is placed under pressure by feeding in compressed air from compressor 13 via inlet 9a, with valve 20a closed. Compressed air is able to flow freely through supply pipe 6 to the well 30 via the well head 17.
- Control valve 20a is opened such that the metal salt solution can pass through inlet 14a and be converted to a mist via the fogger 7.
- the metal salt solution mist then mixes with compressed air within the supply pipe 6 at a ratio of approximately 95-80% volume/volume pressurised air to 5-20% volume/volume mist to form a pressurised metal salt solution dispersion.
- the supply pipe 6 injects into the coal seam 2 the pressurised metal salt solution dispersion at a rate of about 2 to 10 mVminute and at a pressure of between about 10 to 30 atmospheres. Having reached the combustion zone 53, the pressurised metal salt solution dispersion increases the rate of combustion of the coal and provides greater heat for gasification to take place downstream of the combustion zone within the gasification zone 54.
- the invention as exemplified (or as generally described) has at least the following advantages: (i) the invention increases the efficiency of recovering coal via underground gasification by promoting gasification zone expansion laterally; (ii) the invention enables calorific value control of the product gas during gasification; (iii) the invention ensures that the quality of the product gas remains stable when aiming for a particular CO/H 2 ratio; (iv) the invention is easy to implement; (v) the invention improves the efficiency of underground gasification of coal by increasing the content of useful product gas components; and (vi) the invention reduces the cost of energy production by improving the quality of UCG product gas and reducing the cost of drilling.
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- Physics & Mathematics (AREA)
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Abstract
The invention relates to a method and apparatus for increasing the rate of coal combustion within a combustion zone of an underground coal gasifier.
Description
IMPROVED UNDERGROUND COAL GASIFICATION METHOD AND APPARATUS
TECHNICAL FIELD
[0001] This invention relates to a method and apparatus for increasing the rate of coal combustion within a combustion zone of an underground coal gasifier. In particular, a method and apparatus for introducing a metal salt solution into a combustion zone of an underground coal gasifier are disclosed.
BACKGROUND ART
[0002] Underground coal gasification (UCG) is a process by which product gas is produced from a coal seam by combusting and gasifying the coal in situ in the presence of an oxidant. The product gas is typically referred to as synthesis gas or syngas and can be used as a feedstock for various applications, including clean fuels production, chemical production, and electricity generation .
[0003] Wells are drilled into the coal to allow for oxidant injection and product gas extraction. The wells are linked or extended to form an in-seam well channel (also referred to as a "linkage channel") to facilitate oxidant injection, cavity development and product gas flow. The well allowing the injection of oxidant is called an injection well. The well from which product gas emerges is called a production well. Both horizontal and vertical well regions can be used for injection and production. Underground coal gasification can also utilise one or more vertical wells (service wells) located between the injection and production wells.
[0004] A coal seam having an injection well and a production well, with a well channel linking the two wells, is typically referred to as an underground coal gasifier. The gasifier will have a combustion zone within which coal is combusted in the presence of an oxidant, a gasification zone located downstream of the combustion zone in which coal is gasified and partially oxidized to produce product gas, and a downstream pyro lysis zone in which pyro lysis of coal occurs. Hot product gas flows downstream from the gasification zone and exits the ground from a well head of the production well. As coal is consumed or gasified, a gasifier (gasification) cavity within the coal seam develops and grows in size.
[0005] The product gas generated by UCG typically includes syngas as well as other components, and the constituency will depend on various factors, including the type of
oxidant used for UCG (e.g., air or oxygen), water conditions (both ground water and exogenous water), coal quality, and UCG operating temperature and pressure.
[0006] Typically, UCG product gas will contain: (1) main syngas components (e.g., CO, H2, C02, N2, and CH ); (2) solid particles/particulates (e.g., soot, ash, and coal particles); (3) water; (4) minor components such as C2-C6 hydrocarbons, oxygen, argon, sulphur containing components (e.g., H2S, COS, CS2, mercaptans, and thiophenes), nitrogen based components (e.g., NH3 and HCN), hydrocarbon components (e.g., coal condensate, BTEX (benzene, toluene, ethylbenzene and xylenes), and PAHs (polycyclic aromatic hydrocarbons)); and (5) trace components such as heavy metals (arsenic and mercury) and chlorides.
[0007] Disadvantages of standard UCG methods utilising air as the oxidant include: due to a low rate of oxidation within the main combustion zone of an underground coal gasifier, additional oxidation reactions tend to take place downstream of the main combustion zone along the length of a well channel, thereby increasing the propagation rate of the combustion front. Consequently, there is less gasification zone development and gasifier cavity expansion in a lateral (i.e., cross sectional) direction relative to the length of the well channel and direction of gas flow. This leads to poor utilisation of coal seam reserves situated between well channels extending alongside one another (such as in a knife-edge gasifier
configuration), and to the necessity of having to decrease the distance between such well channels. That is, the low rate of oxidation reduces the effectiveness of coal resource recovery by standard UCG methods.
[0008] Additionally, when a well channel of an underground coal gasifier is short, an increase in the air injection rate does not increase the production of desirable product gas components (e.g., CO and H2), because the length of the gasification zone of the gasifier is reduced.
[0009] Finally, although using oxygen as an oxidant results in a greater rate of oxidation than using air as the oxidant, the cost of UCG product gas production increases multi-fold because oxygen production (or purchase) is costly.
[0010] Thus, there is a need for methods and systems of increasing the rate of coal combustion and appropriate gasification zone development in an underground coal gasifier to improve coal resource recovery.
SUMMARY OF INVENTION
[0011] An object of the present invention is to provide a method and apparatus for UCG that minimises one or more of the disadvantages of the prior art.
[0012] Throughout this specification, unless the context requires otherwise, the words "comprise", "comprises" and "comprising" will be understood to mean the inclusion of a stated integer, group of integers, step, or steps, but not the exclusion of any other integer, group of integers, step, or steps.
[0013] The present inventors have now developed a method and apparatus for increasing coal combustion and appropriate gasification zone development within an underground coal gasifier, with concomitant improvement of coal resource recovery.
[0014] According to an aspect of the present invention, there is provided a method of increasing the rate of coal combustion within a combustion zone of an underground coal gasifier, the method including the step of introducing a metal salt solution into the combustion zone of the underground coal gasifier so as to increase the rate of combustion of the coal in the combustion zone over that achievable using an injected oxidant alone.
[0015] The metal salt solution can be introduced into the combustion zone of the underground coal gasifier in any suitable way and in any suitable form. For example, the metal salt solution can be injected into the combustion zone together with an oxidant such that the oxidant acts as a carrier for the metal salt solution. The injected oxidant can mix with the metal salt solution to form a dispersion (i.e., metal salt solution particles dispersed in gaseous oxidant) that promotes combustion of coal.
[001 ] The dispersion can include metal salt solution drops/particles of any suitable size. Preferably, the metal salt solution drops/particles have an average size of anywhere between about 10 and 40 microns, including about 15, 20, 25, 30, or 35 microns (i.e., a metal salt solution mist).
[0017] Preferably, the metal salt solution is dispersed within a pressurised oxidant and the pressurised metal salt solution dispersion is used for injection into the combustion zone of the underground coal gasifier.
[0018] Preferably, the oxidant is supplied to the combustion zone of the underground
coal gasifier at a pressure of between about 10 and 30 atmospheres, although pressures of about 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, or 40 atmospheres can be used.
[0019] Any suitable type of metal salt solution can be used. The metal salt can be consumed in a chemical reaction occurring in the combustion zone of the gasifier, or can function as a catalyst (i.e., the metal salt is not necessarily consumed). Preferred types of metals include sodium and potassium, as well as other alkali metals of Group 1 of the periodic table (IUPAC numbering). Preferred types of metals also include barium and calcium, as well as other alkali earth metals of Group 2 of the periodic table. Yet other preferred types of metals include nickel and other transition metals of Group 10 of the periodic table (nickel family metals).
[0020] The metal salt can be a metal carbonate, sulphate or nitrate for example.
Preferably, the metal salt solution is an aqueous solution of potassium carbonate (K2CO3), sodium carbonate (NaiCOs), barium carbonate (BaC03), or nickel carbonate (NiC03), as well as mixtures thereof. The preferred catalytic metal salt is sodium carbonate.
[0021] Although any suitable concentration of metal salt can be introduced into the combustion zone of the underground coal gasifier, preferably about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ,13, 14, 15, 16, 17, 18, 19, 20, 21, 22 , 23, 24, 25, or even up to about 50%
weight/weight metal salt can be injected with oxidant; preferably as a pressurised metal salt solution dispersion.
[0022] The metal salt solution can be mixed with oxidant at any suitable ratio, including a ratio of approximately 95-80% volume/volume oxidant to 5-20% volume/volume metal salt solution.
[0023] The injected oxidant, which can act as a carrier stream for the metal salt solution, can be any suitable type of fluid or fluids. The oxidant is preferably a gas such as air
(approximately 20% oxygen), oxygen-enriched air (greater than 20% oxygen), or a gas/gas mixture (e.g., C02 and/or nitrogen in any desired ratio) enriched with oxygen (greater than or equal to 20% oxygen), or substantially pure oxygen. The oxidant source can include an air compressor, a tank/cylinder of compressed air or oxygen, an air separation unit, or a tank/cylinder of liquid oxygen.
[0024] The metal salt solution can be introduced into the combustion zone of the
underground coal gasifier by way of an injection well or a service well.
[0025] According to another aspect of the present invention, there is provided a pressurised metal salt solution dispersion supply system for increasing the rate of coal combustion within a combustion zone of an underground coal gasifier, the system including: a) a source of pressurised metal salt solution dispersion and b) a supply pipe having an inlet connected to the source of pressurised metal salt solution dispersion and an outlet connectable to a well head of a well of the underground coal gasifier for injecting the pressurised metal salt solution dispersion into the combustion zone of the underground coal gasifier.
[0026] According to a further aspect of the present invention, there is provided a pressurised metal salt solution dispersion supply system for increasing the rate of coal combustion within a combustion zone of an underground coal gasifier, the system including: a) a source of metal salt solution, b) a source of pressurised oxidant, and c) a supply pipe having (i) an oxidant inlet connected to the source of the pressurised oxidant, (ii) a metal salt solution inlet connected to the source of the metal salt solution and including a fogger for forming a metal salt solution mist that mixes with the pressurised oxidant within the supply pipe to form a pressurised metal salt solution dispersion, and (iii) an outlet connectable to a well head of a well of the underground coal gasifier for injecting the pressurised metal salt solution dispersion into the combustion zone of the underground coal gasifier.
[0027] The fogger (also known as a mister or sprinkler) can be of any suitable size, shape and construction, and can produce a metal salt solution mist (i.e., drops/particles) of any suitable size. Preferably, the fogger produces metal salt solution drops/particles having an average size of anywhere between about 10 and 40 microns, including about 15, 20, 25, 30, or 35 microns.
[0028] The fogger can spray a metal salt solution mist at a controlled rate into the supply pipe, such that a ratio of approximately 95-80% volume/volume oxidant to 5-20%
volume/volume metal salt solution mist is achieved.
[0029] The pressurised metal salt solution dispersion supply system can include at least one tank containing the metal salt solution and this tank can be of any suitable size, shape and construction. For example, the tank can have a capacity of about 150 to 200 litres. The inlet for the metal salt solution can extend to within the supply pipe from the bottom of the tank. A control valve of the system associated with the inlet for the metal salt solution can control the
flow rate of the metal salt solution there through. The tank can have an oxidant inlet connected to the supply pipe for receiving the oxidant so as to place the source of the metal salt solution under pressure, as well as to ensure proper mixing of the tank's contents. A control valve associated with the oxidant inlet can regulate the flow of compressed oxidant into the tank for the metal salt solution.
[0030] The pressurised metal salt solution dispersion supply system can include two or more tanks containing the metal salt solution, such that one tank can be used whilst the other tank is being filled (including refilled) or serviced.
[0031] The supply pipe can be of any suitable size, shape and construction. The supply pipe can have an inner diameter of about 150 to 300 mm, including about 175, 200, 225, 250, or 275 mm. Preferably, the supply pipe has an inner diameter of about 160 mm. The supply pipe also includes an outlet that can connect to a well head of a well of an underground coal gasifier. This coupling can be achieved in any suitable way. The supply pipe preferably feeds the well of the underground coal gasifier a pressurised metal salt solution dispersion
(approximately 5-20% weight/weight metal salt solution concentration; approximately 95- 80% volume/volume oxidant to 5-20% volume/volume metal salt solution) at a rate of about 2 to 10 m3/minute (including, about 3, 4, 5, 6, 7, 8, or 9 mVminute) over the required time period (usually for as long as the gasifier remains in operation).
[0032] According to yet a further aspect of the present invention, there is provided a pressurised metal salt dispersion including a metal salt solution dispersed in a pressurised oxidant for increasing the rate of coal combustion within a combustion zone of an underground coal gasifier.
[0033] Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying figures.
BRIEF DESCRIPTION OF DRAWINGS
[0034] Figure 1 is a cross sectional view of a pressurised metal salt solution dispersion supply system, according to an embodiment of the present invention.
[0035] Figure 2 is a transverse cross-sectional view (through plane A- A) of that shown in Figure 1.
[0036] Figure 3 is an enlarged cross sectional view of a fogger of the supply system shown in Figure 1.
[0037] Figure 4 depicts use of the supply system of Figure 1 for increasing the rate of coal combustion within a combustion zone of an underground coal gasifier, according to an embodiment of the present invention.
DESCRIPTION OF EMBODIMENTS
[0038] In the figures, like reference numerals refer to like features.
[0039] The present inventors have now developed a method and apparatus for increasing the rate of coal combustion in an underground coal gasifier by introducing a metal salt solution (also referred to herein as a "metal catalyst") into a combustion zone of the gasifier in an oxidant carrier stream (e.g., an air stream). A result of this development is that the length of the combustion zone along a well channel of the gasifier is decreased and, as a
consequence, the lateral width of a gasification zone of the gasifier within the coal seam is increased. In addition, the amount of energy per unit of time is also increased, which ultimately provides more energy for reactions within the gasification zone, where the formation of combustible gases (particularly CO and H2) occurs byway of the following chemical reactions:
C02 + C = 2CO
H20 + C = CO + H2
2H20 + C = C02 + 2H2
[0040] The effect of various metal salt (e.g., carbonate) catalysts on the time taken to gasify coal samples (of uniform size) was investigated. Table 1 below shows the duration of complete gasification of coal samples as depending of the presence of metal carbonate catalysts.
TABLE 1
Metal catalyst(s) Amount of metal catalyst within Monochromatometre reading for time taken pressurised air (% mass) for complete gasification (seconds)
Catalyst- free - 0.6563
NiCOj 1.0 -
Nico3 2.5 0.5488
BaC03 2.5 0.5053
CaC03 5.0 0.4629
CaC03 + Na2C03 2.5+2.5 0.4349
Na2C03 5.0 0.4284
Na2C03 + K2C03 2.5+2.5 0.3787
K2C03 5.0 0.3711
[0041] The results of Table 1 show that various metal salt catalysts shorten the time taken to gasify coal samples. The catalytic activity can be ranked as follows (from highest to lowest activity): K2C03 > Na2C03 > BaC03 > NiC03.
[0042] A combination of metal carbonate catalysts was not found to provide an advantage over single metal carbonate catalysts.
[0043] The effect of various metal salt solution catalysts on combustion/gasification temperature was investigated. Table 2 below shows the temperature profile during the complete gasification of coal samples (of uniform size) as depending of the presence of metal salt catalysts.
TABLE 2
[0044] The results of Table 2 support that, in the presence of metal salt solution catalysts,
the amount of energy per unit of time increases, thereby ultimately providing more energy for reactions within the gasification zone where the formation of combustible gases CO and H2 occurs.
[0045] Therefore, the present invention includes using metal salt catalysts (such as a2C03) in an oxidant carrier stream (such as pressurised air) as a means of increasing the rate of coal combustion to: (i) increase the coal recovery rate, (ii) increase the CO and H2 content of product gas and (iii) reduce the volume of oily water by-product (coal/gas condensate) that is normally isolated from a raw product gas stream.
[0046] The inventors' pressurised metal salt solution dispersion supply system 1 for increasing the rate of coal combustion within a combustion zone of an underground coal gasifier (over that achievable using an injected oxidant alone) is shown in Figures 1-4. The system 1 includes a source of metal salt solution catalyst 4a, 4b, a source of pressurised air 5 (i.e., oxidant), a supply pipe 6 and a fogger 7
[0047] The source of metal salt solution 4a, 4b includes two cylindrical 170 litre tanks 8a, 8b, each capable of containing a metal salt solution (5-20% weight/weight sodium carbonate) and operable independently of one another. Each tank 8a, 8b has an inlet 50a, 50b for receiving the metal salt solution and an isolation valve 51a, 51b. Each tank 8a, 8b has an inlet 9a, 9b extending to the supply pipe 6 for receiving compressed air so as to place the metal salt solution under pressure and to ensure proper mixing of the tank contents. A control valve 10a, 10b of the system 1 associated with each inlet 9a, 9b regulates the flow of compressed air into each tank 8a, 8b. Each inlet 9a, 9b has a plurality of outlets 41a, 41b for air positioned along a lower region of the tank 8a, 8b.
[0048] The source of pressurised air 5 is an air compressor 13.
[0049] The supply pipe 6 has an inlet 11 connected to the air compressor 13, a branched inlet pipe 14a, 14b with a branch extending to each tank 8 a, 8b, and an outlet 15 connectable to a well head 17 of a well 30 of an underground coal gasifier for injecting the pressurised metal salt solution dispersion into a combustion zone of the gasifier of a coal seam 2 (as seen in Figure 4).
[0050] The supply pipe 6 has an inner diameter of about 160mm (but it could equally be about 180 to 200 mm). The supply pipe outlet 15 can couple with the well head 17 of a well
30 of an underground coal gasifier, as depicted in Figure 4.
[0051] The fogger 7 (also known as a sprinkler or mister) is connected to an end of the inlet 14a located within the supply pipe 6. Further details of the fogger 7 can be seen in figure 3 (which is a third party commercially available fogger). The fogger 7 has a tubular body 70, a channel 71 and a head 72. As the metal salt solution flows through the channel 71 of the body 70 and past the head 72, it is converted into a mist. The fogger 7 converts the pressurised metal salt solution into a mist of particles having an average size of anywhere between about 10 and 40 microns.
[0052] The metal salt solution mist mixes with the compressed air within the supply pipe 6 at a ratio of approximately 95-80% volume/volume pressurised air to 5-20%
volume/volume metal salt solution mist. However, this ratio may be varied according to the task at hand, as will be understood by one of ordinary skill in the art. Control valves 20a, 20b of the system 1 associated with the inlet 14a, 14b regulate the flow of the metal salt solution to the fogger 7 and can be adjusted to vary the ratio according to conditions within the underground gasifier and the composition of combustibles within the produced product gas.
[0053] The following explains how the delivery system 1 can be used to increase the rate of coal combustion within a combustion zone of an underground coal gasifier.
[0054] As seen in Figure 4, the delivery system 1 is coupled to the well head 17 of the well 30 of an underground coal gasifier. The well 30 includes a 128-300 mm metal pipe 22 that is encased in concrete. The coal seam 2 is, for example, located approximately 180-250 m below ground level.
[0055] One or more of tanks 8a, 8b are filled with a metal salt solution via inlet 50a, 50b. Tank 8a is placed under pressure by feeding in compressed air from compressor 13 via inlet 9a, with valve 20a closed. Compressed air is able to flow freely through supply pipe 6 to the well 30 via the well head 17. Control valve 20a is opened such that the metal salt solution can pass through inlet 14a and be converted to a mist via the fogger 7. The metal salt solution mist then mixes with compressed air within the supply pipe 6 at a ratio of approximately 95-80% volume/volume pressurised air to 5-20% volume/volume mist to form a pressurised metal salt solution dispersion. The supply pipe 6 injects into the coal seam 2 the pressurised metal salt solution dispersion at a rate of about 2 to 10 mVminute and at a pressure of between about 10 to 30 atmospheres. Having reached the combustion zone 53, the pressurised metal salt
solution dispersion increases the rate of combustion of the coal and provides greater heat for gasification to take place downstream of the combustion zone within the gasification zone 54.
[0056] The invention as exemplified (or as generally described) has at least the following advantages: (i) the invention increases the efficiency of recovering coal via underground gasification by promoting gasification zone expansion laterally; (ii) the invention enables calorific value control of the product gas during gasification; (iii) the invention ensures that the quality of the product gas remains stable when aiming for a particular CO/H2 ratio; (iv) the invention is easy to implement; (v) the invention improves the efficiency of underground gasification of coal by increasing the content of useful product gas components; and (vi) the invention reduces the cost of energy production by improving the quality of UCG product gas and reducing the cost of drilling.
[0057] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.
Furthermore, the particular features, structures, or characteristics can be combined in any suitable manner in one or more combinations.
[0058] Throughout the specification the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features. It will therefore be appreciated by those of skill in the art that, in light of the instant disclosure, various modifications and changes can be made in the particular embodiments exemplified without departing from the scope of the present invention.
Claims
1. A method of increasing the rate of coal combustion within a combustion zone of an underground coal gasifier, the method comprising the step of introducing a metal salt solution into the combustion zone of the underground coal gasifier so as to increase the rate of combustion of the coal in the combustion zone over that achievable using an injected oxidant alone.
2. The method of claim 1 , wherein the metal salt solution is injected into the combustion zone of the underground coal gasifier together with an oxidant such that the oxidant acts as a carrier for the metal salt solution.
3. The method of claim 1 , wherein the metal salt solution is dispersed within a pressurised oxidant and the pressurised metal salt solution dispersion is injected into the combustion zone of the underground coal gasifier.
4. The method of claim 3, wherein the pressurised oxidant is at a pressure of between about 10 and 30 atmospheres.
5. The method of any one of claims 2 to 4, wherein the oxidant is selected from the group consisting of air, oxygen-enriched air and a gas/gas mixture enriched with oxygen.
6. The method of claim 5, wherein the oxidant is air.
7. The method of any one of claims 1 to 6, wherein the metal salt solution is an aqueous solution selected from the group consisting of potassium carbonate, sodium carbonate, barium carbonate, nickel carbonate, and combinations thereof.
8. The method of claim 7, wherein the metal salt solution is an aqueous solution of sodium carbonate.
9. The method of any one of claims 1 to 8, wherein the metal salt solution is introduced into the combustion zone of the underground coal gasifier by way of an injection well or a service well.
10. A pressurised metal salt solution dispersion supply system for increasing the rate of coal combustion within a combustion zone of an underground coal gasifier, the system comprising: a) a source of pressurised metal salt solution dispersion; and
b) a supply pipe having an inlet connected to the source of pressurised metal salt solution dispersion and an outlet connectable to a well head of a well of the underground coal gasifier for injecting the pressurised metal salt solution dispersion into the combustion zone of the underground coal gasifier.
11. A pressurised metal salt solution dispersion supply system for increasing the rate of coal combustion within a combustion zone of an underground coal gasifier, the system comprising:
a) a source of metal salt solution;
b) a source of pressurised oxidant; and
c) a supply pipe having
(i) an oxidant inlet connected to the source of the pressurised oxidant;
(ii) a metal salt solution inlet connected to the source of the metal salt solution and including a fogger for forming a metal salt solution mist that mixes with the pressurised oxidant within the supply pipe to form a pressurised metal salt solution dispersion; and
(iii) an outlet connectable to a well head of a well of the underground coal gasifier for injecting the pressurised metal salt solution dispersion into the combustion zone of the underground coal gasifier.
12. The pressurised metal salt solution dispersion supply system of claim 11, wherein the metal salt solution is an aqueous solution selected from the group consisting of potassium carbonate, sodium carbonate, barium carbonate, nickel carbonate, and combinations thereof.
13. The pressurised metal salt solution dispersion supply system of claim 12, wherein the metal salt solution is an aqueous solution of sodium carbonate.
14. The pressurised metal salt solution dispersion supply system of claim 11, wherein the pressurised oxidant is pressurised air.
15. The pressurised metal salt solution dispersion supply system of claim 11, wherein the fogger produces metal salt solution drops/particles having an average size of between about 10 and about 40 microns.
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RU2595126C1 (en) * | 2015-06-29 | 2016-08-20 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Казанский государственный энергетический университет" (ФГБОУ ВПО "КГЭУ") | Installation for underground gasification of fuel |
CN106089177A (en) * | 2016-08-18 | 2016-11-09 | 中国矿业大学(北京) | A kind of high-efficiency coal underground gasification furnace and construction method thereof |
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RU2595126C1 (en) * | 2015-06-29 | 2016-08-20 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Казанский государственный энергетический университет" (ФГБОУ ВПО "КГЭУ") | Installation for underground gasification of fuel |
CN106089177A (en) * | 2016-08-18 | 2016-11-09 | 中国矿业大学(北京) | A kind of high-efficiency coal underground gasification furnace and construction method thereof |
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