JP2016160309A - Methane production solid fuel gasification system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a methane production solid fuel gasification system where the using amount of water in the whole of the system producing methane is reduced from a production gas obtained by gasifying a solid fuel.SOLUTION: Provided is a methane production solid fuel gasification system where a production gas 17 obtained by gasifying a solid fuel 1 by a gasification furnace 16 as a gasification means is cooled, dust-removed and refined, and is thereafter subjected to methanation reaction with a methanation reactor 35. Moisture generated as by-products by the methanation reaction is separated and recovered by a distillation tower 56. This moisture is charged to a production gas cooling part 18 on the downstream of the gasification furnace, and is mixed with the production gas 17 whose temperature is made high by the gasification furnace, thus is utilized for the direct cooling of the production gas.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to a methane production solid fuel gasification system, specifically, a methane production solid fuel gasification in which a product gas obtained by gasification of a solid fuel such as coal is subjected to a shift reaction and further a methanation reaction to produce methane. About the system.

Not only as the power generation fuel solid fuel such as coal, hydrogen, methane, methanol and dimethyl ether; converts the like (DME D i m ethyl E ther ), chemical raw materials and synthetic natural gas (SNG; S ynthetic N atural G demand for gasification systems that can be used for various purposes such as as) is increasing. This is because the added value of the gasification system is increased by producing hydrogen, methanol, and DME, and SNG produced from methane can be used as a city gas in an existing pipeline.

  In particular, countries and regions that produce coal tend to sell expensive bituminous coal and use cheap subbituminous coal and lignite in the vicinity, and there is a demand for a gasification system that can use subbituminous coal and lignite for multiple purposes. On the other hand, in countries and regions where water resources are scarce, there is a demand for a gasification system that can reduce the amount of water used in the entire system.

In order to produce methane from coal, a process for producing methane by a methanation reaction of a product gas obtained by gasifying coal is required. In the methanation reaction, as shown in the following formula (1) or formula (2), water is generated as a by-product, and the product gas after the methanation reaction is heated to high temperature by reaction heat (in some cases, reaches several hundred degrees) .) Whether the reaction of Formula (1) or Formula (2) proceeds is determined by the composition of the product gas and the catalyst used in the methanation reactor.
CO + 3H ₂ = CH ₄ + H ₂ O + 206 KJ / mol (1)
CO ₂ + 4H ₂ = CH ₄ + 2H ₂ O + 165 KJ / mol (2)
As can be seen from Equation (1) and Equation (2), a step of separating methane from water and distilling it is required downstream of the methanation reactor. Therefore, effective use of reaction heat is required.

Further, upstream of the methanation reactor, the product gas is supplied to the shift reactor to advance the shift reaction represented by the formula (3). Further, in some cases, CO ₂ is recovered and then supplied to the methanation reactor. There is a system.
CO + H ₂ O = CO ₂ + H ₂ +42 KJ / mol (3)
In order to advance the shift reaction, it is necessary to add water vapor, but the water vapor concentration must be higher than the stoichiometric ratio. For example, although depending on the shift catalyst, the stoichiometric ratio is about 1.5 to 2 times. Therefore, excess water vapor is contained in the product gas after the shift reaction. Most of the excess water vapor contained in the product gas is condensed and recovered as water when cooled on the upstream side of the CO ₂ recovery device. Effective use of the collected water is also required.

  For example, Patent Document 1 describes a system that transfers reaction heat of a methanation reaction to a heat source for drying coal. In this system, steam is produced by heating water using methanation reaction heat or reaction heat in a coal gasification furnace, and it is used for preheating carrier nitrogen used for pre-drying of solid fuel and for steam added to a shift reactor. It is described to use. This system is effective in gasification systems such as lignite that have a large amount of water in coal and need to be dried upstream of the gasification furnace.

Further, Patent Document 2 discloses that a gasified product gas is subjected to a shift reaction, CO _{2 is} recovered, then a methanation reaction is performed, and moisture is recovered as hydrogen by removing moisture in the generated gas. A system for generating electricity at is described. In this system, a system is described in which a product gas that has become approximately 40 ° C. by CO ₂ recovery is heated to about 200 to 350 degrees by methanation reaction heat.

JP 2012-188539 A WO 01-004045 A1

  As described above, in the gasification system in which the product gas produced by gasifying solid fuel is subjected to methanation reaction to produce methane, the effective use of methanation reaction heat is referred to in Patent Document 1 and Patent Document 2, respectively. Has been.

  However, in patent document 1, it is a system which cools the produced gas containing the dust heated up with the coal gasification furnace by an indirect heat exchange system. In the case of this system, it is considered that the heat exchanging part becomes large in order to suppress the dust from adhering to the heat exchanging part that cools the generated gas, and the apparatus cost is increased. Further, there is no mention of effective use of water vapor containing dust generated by fuel drying, excess water after shift reaction, and water generated as a byproduct of methanation reaction. Therefore, no consideration is given to reducing water consumption in the entire system.

  Further, in Patent Document 2, as in Patent Document 1, there is no mention of an effective utilization measure of excess water after the shift reaction and water removed from the product gas after the methanation reaction. Therefore, no consideration is given to reducing the water consumption of the entire system.

  The problem to be solved by the present invention is to construct a methane production solid fuel gasification system capable of reducing the amount of water used in the entire system for producing methane from a product gas obtained by gasifying solid fuel.

  In order to solve the above problems, a first aspect of the methane production solid fuel gasification system of the present invention is a methanation reaction of a product gas obtained by gasifying solid fuel in a gasification furnace as a gasification means. Moisture generated as a by-product in the reaction is separated and collected, put into the product gas downstream of the gasification furnace, and mixed with the product gas heated in the gasification furnace, thereby directly cooling the product gas.

  According to the first aspect, the water generated in the methanation reaction is separated and recovered, put into the downstream of the gasification furnace, and the product gas heated at the gasification furnace is directly cooled to cool the product gas. Therefore, the product gas cooling unit for reducing the size can be reduced in size. In particular, when industrial water or the like is used for direct cooling of the produced gas, the amount of industrial water used in the system can be reduced by partially covering with water generated by the methanation reaction.

The second aspect of the methane produced solid fuel gasification system of the present invention, some or all of the generated gas is shift reaction, the CO ₂ in the product gas after the shift reaction is supplied to the CO ₂ recovery unit In the process of providing a system for separation and recovery and cooling the product gas after the shift reaction, much of the excess water vapor (above the saturation temperature) contained in the product gas is condensed and recovered as water. The product gas is mixed downstream of the gasifier and the product gas is directly cooled. Incidentally, CO ₂ recovery unit, as well to absorb CO ₂ absorption liquid can be configured by applying a chemical absorption method for recovering CO ₂ by reproducing the absorption liquid.

According to a second aspect, since the condensed water excess steam in the product gas after the shift reaction can be effectively utilized to recover the CO ₂ recovery unit, it is possible to reduce the amount of industrial water for the system. Furthermore, if the first aspect and the second aspect are combined, the amount of industrial water used in the system can be further reduced. In addition, the product gas cooling unit can be reduced in size.

  In the first or second aspect, the water produced by the methanation reaction or shift reaction is recovered, sprayed in multiple stages on the product gas downstream of the gasifier, and the temperature range of the produced gas is 900 ° C. or higher. It is preferable to increase the water vapor concentration. According to this, the shift reaction of Formula (3) is promoted upstream of the shift reactor, the flow rate of water vapor added to the downstream shift reactor can be reduced, and the amount of catalyst used in the shift reactor can also be reduced. . Thus, according to the first and second aspects of the present invention, the methane production solid fuel gasification system that reduces the apparatus cost by reducing the size of the product gas cooling unit and reduces the amount of water used for industrial water in the system, for example. Can be built.

Furthermore, a third aspect of the methane produced solid fuel gasification system of the present invention is a reproducing tower of the CO ₂ absorbing solution in the CO ₂ recovery unit, a heat source for regenerating heat at least a portion of the CO ₂ absorbing solution, Use heat of methanation reaction. Specifically, the water produced by the methanation reaction is heated with methanation reaction heat to form high-temperature water or water vapor, and this high-temperature water or water vapor is supplied to the CO2 absorbing liquid regeneration heater. Thereby, methanation reaction heat can be effectively used in the system. Here, as water that is heated by methanation reaction heat to generate high-temperature water or water vapor, water obtained by condensing surplus steam after the shift reaction is used in addition to water generated by methanation reaction.

In the conventional CO ₂ recovery apparatus, a part of steam for power generation or the like is extracted and supplied to the regenerative heater for the CO ₂ absorption liquid. According to the third aspect, the conventional extracted steam system is used. It can be deleted or the flow rate of steam can be reduced. Furthermore, by using water generated by the methanation reaction or water obtained by condensing surplus steam after the shift reaction, it is possible to construct a methane production solid fuel gasification system that reduces the amount of water used in the system.

  The fourth aspect of the present invention is the use of the high-temperature water or water vapor supplied to the CO2 absorption liquid regeneration heater in the third aspect in the downstream of the gasification furnace, and the temperature is increased in the gasification furnace. By mixing with the produced gas, it is used for direct cooling of the produced gas. As the water used here, makeup water such as industrial water, water generated as a by-product in the methanation reaction, and water obtained by condensing surplus steam after the shift reaction are used. Thereby, methanation reaction heat can be utilized more effectively.

Further, it is preferable to add a system for collecting char accompanying the generated gas generated in the gasification furnace and re-introducing it into the gasification furnace. In this case, the high-temperature water or water vapor generated in the third or fourth aspect is supplied to the outer periphery of the char storage hopper or the char transport pipe, and is also used to keep the char warm. According to this, high temperature water or steam produced by heating water generated by methanation reaction or water condensed from surplus steam after shift reaction is supplied to the outer periphery of the char storage hopper or char transport pipe. Thus, the amount of high-temperature water or water vapor used for heat retention of the char can be reduced.
Furthermore, the high-temperature water or water vapor used for the heat insulation of the char is introduced into the downstream of the gasification furnace and mixed with the product gas heated in the gasification furnace to be used for direct cooling of the product gas.

  In addition, a small gasification furnace is installed separately from the gasification furnace, and char from the char storage hopper and at least a part of the product gas that has reached 500 ° C. or more due to the methanation reaction are supplied to this small gasification furnace. It is preferable to install a system to perform. In this case, the gas generated in the small gasification furnace is used as fuel gas, and the remaining char is re-introduced into the gasification furnace through the char carrier pipe.

Moreover, it is preferable to mix the product gas containing the char and the water vapor after the methanation reaction in a small gasification furnace installed separately from the gasification furnace. Thereby, the steam gasification reaction of char shown in Formula (4) proceeds. This reaction easily proceeds at higher temperatures, and the minimum temperature is about 500 ° C.
_{C + H 2 O = CO +} H 2 -131KJ / mol (4)
Thereby, the usage-amount of oxygen thrown in order to gasify char in a gasification furnace can be reduced, and the power usage-amount can also be reduced for oxygen production. Furthermore, there is also an effect of removing water vapor from the product gas containing water vapor, and at the same time, there is an effect of cooling the product gas heated to high temperature by the methanation reaction by the endothermic reaction of formula (4).

  In addition, when constructing a system having a solid fuel drying device upstream of the gasification furnace, a system for supplying the product gas heated to several hundred degrees after the methanation reaction to the drying device is provided so It is preferable to perform heat exchange. In other words, a solid fuel gasification system for methane production that achieves both effective use of methanation reaction heat and reduction in drying power of solid fuel by drying solid fuel with sensible heat of product gas that has been heated to high temperature after methanation reaction Can be built.

  As described above, according to the first or second aspect of the present invention, the surplus water after the shift reaction and the water generated as a by-product in the methanation reaction are separated, recovered, and reused. Water consumption can be reduced. Moreover, according to the 3rd or 4th aspect of this invention, the heat | fever generate | occur | produced in systems, such as a methanation reaction heat | fever, can be used effectively.

  ADVANTAGE OF THE INVENTION According to this invention, the methane production solid fuel gasification system which can reduce the water consumption of the whole system which manufactures methane from the product gas which gasified solid fuel can be constructed | assembled.

It is a system | strain block diagram of the methane production solid fuel gasification system of Example 1 of this invention. It is a system | strain block diagram of the methane production solid fuel gasification system of Example 2 of this invention. It is a system | strain block diagram of the methane production solid fuel gasification system of Example 3 of this invention. It is a system | strain block diagram of the methane production solid fuel gasification system of Example 4 of this invention. It is an example of the system | strain block diagram of the methane production solid fuel gasification system which changed Example 4 of this invention.

  Hereinafter, the methane production solid fuel gasification system of the present invention will be described based on examples.

The system block diagram of the methane production coal gasification system of Example 1 is shown in FIG. As shown in FIG. 1, a pulverizing device 2 as a pulverizing means for pulverizing coal 1 as a solid fuel, and a gasification furnace 16 as a gasifying means for gasifying the coal 1 crushed and supplied by the pulverizing device 2. And a product gas cooling unit 18 disposed downstream of the gasification furnace 16. Further, a dust removing device 19 for removing dust in the product gas cooled by the product gas cooling unit 18, a water washing tower 27 for washing the dedusted product gas with water, and a sulfur content in the water-washed product gas are removed. A product gas purification device comprising a desulfurization device 28 is provided. In addition, a plurality of methanation reactors 35 connected in series for the methanation reaction of the product gas purified by the product gas purifier, and moisture as a by-product in the product gas subjected to the methanation reaction in the methanation reactor 35 And a distillation column 56 for separating and recovering the water. Further, a shift reactor 34 that shifts a part or all of the product gas purified by the product gas purification device, a CO ₂ absorption tower 40 that separates and recovers CO ₂ in the shift-reacted product gas, and CO _2. The CO ₂ recovery unit is configured to include a CO ₂ regeneration tower 45 that regenerates the absorbing solution that has absorbed the water.

  Next, the detailed structure of the methane production coal gasification system of FIG. Coal 1 is pulverized by pulverizer 2 and stored in lock hopper 3. The coal 1 whose pressure has been increased to a predetermined pressure by the lock hopper 3 is transferred to the feed hopper 4 via the transfer valve 5, and is then gasified via the fuel transfer pipe 9 and the fuel burner 10 along with the transfer gas. The furnace 16 is charged.

An inert gas such as N ₂ or CO ₂ is used as a gas for transferring and conveying the coal 1. In this embodiment, re-CO ₂ treated with CO ₂ regeneration tower 45 recovered in the system (hereinafter referred to as recovered _CO 2 101.) Withdrawing a portion of, has been boosted to a predetermined pressure in the CO ₂ compressor 52 Use CO ₂ 102 (see * 1 in the figure). The flow rate of the reused CO ₂ 102 is adjusted by the flow rate adjustment valve 51. Further, since the pressure at the outlet side of the CO ₂ compressor 52 is constant, the flow rate of the circulating CO ₂ in CO ₂ compressor 52 is adjusted by the flow rate control valve 82.

When transferring the coal 1, the CO ₂ is also introduced into the lock hopper 3, the lock hopper pressure equalization valve 6 and the feed hopper pressure equalization valve 7 are opened, and the pressure of the lock hopper 3 and the feed hopper 4 is equalized. Prevent stagnation of transport. For adjusting the pressure of these hoppers, a pressure adjusting valve 8 is used. From the pressure control valve 8, CO ₂ containing dust in the coal 1 is discharged (see * 2 in the figure). For this reason, after removing dust by a dust removing means (not shown), the dust is mixed into the stored CO ₂ 103 system of the CO ₂ recovery unit. Note that CO ₂ containing dust may be reused and put into the lock hopper 3 or the feed hopper 4, but in this case, the number of devices increases and the operation becomes complicated. This is because a device for storing the discharged CO ₂ , adjusting the flow rate, and adjusting the pressure is separately required, and the discharged CO ₂ flow rate varies.

The coal 1 charged into the gasification furnace 16 from the fuel burner 10 is mixed with oxygen 15 similarly charged from the fuel burner 10 and partially burned to be gasified to generate a high-temperature product gas 17. The main components of the product gas 17 are CO and H ₂ . Here, the oxygen 15 introduced into the gasifier 16 is produced by the air separator 13. The air 11 is pressurized by a compressor 12 and supplied to an air separator 13 to be separated into nitrogen 14 and oxygen 15. In this embodiment, this separated oxygen 15 is used. The product gas 17 having a high temperature is supplied to the product gas cooling unit 18. In the product gas cooling unit 18, the spray water 63 whose pressure has been increased to a predetermined pressure by the booster pump 64 is charged to cool the product gas 17. In order to atomize the spray water 63, although not shown, a atomization nozzle is installed at the spray water inlet of the generated gas cooling unit 18.

  As the spray water 63, water recovered after a shift reaction or a methanation reaction described later is used, and makeup water 61 (for example, industrial water) is used for the shortage. The flow rate of the makeup water 61 is adjusted by the flow rate adjustment valve 62 of the makeup water. Further, water vapor may be added to cool the product gas 17. When supplying steam, the generated gas cooling steam 66 is supplied by a system different from the spray water 63. In the present embodiment, the system in which the generated gas cooling water vapor 66 is input to the downstream side of the spray water 63 is shown. In this case, even if the product gas cooling water vapor 66 and the product gas 17 are mixed and the temperature of 900 ° C. or higher can be maintained, the shift reaction shown in the formula (3) proceeds in the product gas cooling unit 18. Thereby, the usage-amount of the catalyst in the downstream shift reactor 34 can be reduced. Although the shift reaction is an exothermic reaction, the operation is performed while adjusting the flow rate of the separately provided spray water 63 while monitoring the temperature of the product gas 17 at the outlet of the product gas cooling unit 18.

The product gas 17 exiting the product gas cooling unit 18 is separated from the char 20 accompanied by the dust removing device 19. Next, the halogen-based material (chlorine or the like) and fine particles are removed by the water washing tower 27, and the sulfur content is further removed by the desulfurizer 28. As a result, a product gas purification apparatus is formed. The char 20 separated from the product gas 17 is stored in the charlock hopper 21, appropriately transferred to the char feed hopper 22, and then reintroduced into the gasification furnace 16 through the char transport pipe 59 and the char burner 60. The An inert gas is used as the carrier gas for the char 20. The carrier gas in the present embodiment, like the coal 1 shows a system using recycled CO 2 _102.

The method of transferring and transporting the char 20 is the same as that of the coal 1 described above. That is, when the char 20 is transferred, the charlock hopper equalizing valve 24 and the charfeed hopper equalizing valve 25 are opened, the charlock hopper 21 and the charfeed hopper 22 are equalized, and the char transfer valve 23 is opened to transfer the char 20. To do. CO ₂ is supplied to promote the transfer of the char 20 and adjust the pressure of the hopper, and the pressure of these hoppers is adjusted by adjusting the opening of the char system pressure adjusting valve 26. The CO ₂ released from the char system pressure regulating valve 26 is thrown into the storage CO ₂ system after dedusting.

On the other hand, the main components of the desulfurized product gas 29 flowing out from the desulfurizer 28 are CO, H ₂ , CO ₂ , and H ₂ O (water vapor). The desulfurized product gas 29 is heated to about 200 to 300 ° C. by a product gas heat exchanger 30 and a product gas heater 31. This heating temperature is set according to the characteristics of the catalyst used in the downstream shift reaction or methanation reaction. The product gas 29 after desulfurization is supplied to the shift reactor 34 and the methanation reactor 35. The amount supplied to each reactor depends on which methanation reaction of formula (1) or formula (2) described above proceeds and the composition of the product gas 29 after desulfurization (concentration of CO, H ₂ , CO ₂ ) ). The supply amount of the product gas 29 after desulfurization to each reactor is adjusted by the product gas flow rate adjustment valve 32 of the shift reaction system and the product gas flow rate adjustment valve 33 of the methanation reaction system.

In this embodiment, the system for advancing the methanation reaction of the formula (1) is described, but the system for advancing the methanation reaction of the formula (2) may be used. Note that the catalyst charged in the methanation reactor 35 needs to be changed depending on which reaction of the formula (1) or the formula (2) proceeds. In the shift reactor 34, the desulfurized product gas 29 is mixed with the added shift reaction water vapor 36, and the shift reaction shown in the equation (4) proceeds. Thereby, the main components of the product gas 37 after the shift reaction are H ₂ and CO ₂ . Here, the product gas 37 after the shift reaction also includes unreacted residual CO and H ₂ O (water vapor). Further, since the shift reaction is an exothermic reaction, the temperature of the product gas 37 after the shift reaction becomes higher than the gas temperature at the entrance which was about 200 to 300 ° C.

The product gas 37 after the shift reaction is cooled to about 40 ° C. by the product gas heat exchanger 30 and the cooler 70. The water condensed here is separated by the drum 71 and becomes water 72 recovered after the shift reaction. In this embodiment, a system is shown in which the entire amount of water 72 recovered after the shift reaction is effectively used as spray water 63 (see * a). In addition, saturated water vapor remains in the product gas 37 after the shift reaction that has passed through the drum 71. Incidentally, there is a concern that the water 72 recovered after the shift reaction is mixed with by-products such as methanol. This is because unreacted CO and H ₂ O (water vapor) remain in the product gas 37 after the shift reaction. In this embodiment, since the water 72 recovered after the shift reaction is charged as spray water 63 into the product gas cooling unit 18, by-products such as methanol contained in the recovered water 72 are evaporated in the product gas cooling unit 18.・ Can be disassembled. Therefore, in this embodiment, there is no problem even if a by-product such as methanol is mixed in the water 72 recovered after the shift reaction, and no additional equipment and system for processing the by-product are required.

The product gas 37 after the shift reaction is supplied to the CO ₂ recovery unit. In this example, CO ₂ is unnecessary because the methanation reaction of CO and H ₂ in formula (1) proceeds. However, it is possible to cope with the adjustment of the product gas composition upstream of the methanation reactor 35, the malfunction of the CO ₂ recovery unit, and the promotion of the methanation reaction by CO ₂ and H _{2 in} the formula (2). A system for bypassing the CO ₂ recovery unit is provided. The shift reaction after product gas 37 supplied to the CO ₂ recovery unit flow rate, and the flow bypassing the CO ₂ recovery unit, the generation of the CO ₂ recovery unit, respectively the gas flow control valve 39, and the CO ₂ recovery unit of the bypass line of The generated gas flow rate adjustment valve 38 is adjusted. In addition, the system for bypassing the CO ₂ recovery unit, to be able to supply the produced gas 37 after the shift reaction to methanation reactor 35 after pressure adjustment, the bypass line of the CO ₂ recovery unit generates gas compressor 54 installed Is done.

Product gas 37 after the shift reaction is supplied to the CO ₂ recovery unit is supplied to the CO ₂ absorber 40, CO ₂ absorbing solution 46 (e.g., methyldiethanolamine, etc.) in contact with, CO ₂ is separated is absorbed . Thereby, the main component of the product gas 41 after CO ₂ absorption is H ₂ . The product gas 41 after absorbing CO ₂ is pressurized by the product gas compressor 53 after absorbing CO ₂ and supplied to the methanation reactor 35. On the other hand, the CO ₂ absorbing liquid 42 that has absorbed CO ₂ in the CO ₂ absorber 40, a heat exchanger 43 and the heater 44 of the CO ₂ absorbing solution is heated to 100 ° C. or higher is supplied to the CO ₂ regeneration tower 45 . In the CO ₂ regeneration tower 45, CO ₂ in the CO ₂ absorbing liquid 42 that has absorbed CO ₂ is released, so that it can be reused as the CO ₂ absorbing liquid 46. CO ₂ absorbing liquid 46 that has been reproduced is pressurized by the pressurizing pump 47, is cooled in heat exchanger 43 of the CO ₂ absorbing solution to about 40 ° C., it is supplied to the CO ₂ absorber.

To keep the CO ₂ recovery rate in the CO ₂ recovery unit, it is necessary to keep warm the CO ₂ absorbing solution in the CO ₂ regeneration tower 45. Therefore, a part of the CO ₂ absorbing solution in the CO ₂ regeneration tower 45 is extracted as a CO ₂ absorbing solution 48 for regeneration heating, heated to 100 ° C. or more by the CO ₂ absorbing solution regeneration heater 49, and then CO ₂ regeneration. Return to Tower 45. High-temperature water or low-temperature steam of 300 ° C. or lower is suitable for this heat source. In the present embodiment, a system using low-temperature steam is shown, and this low-temperature steam is referred to as a regeneration heating steam 50 for the CO ₂ absorbent.

Part of the recovered CO ₂ 101 recovered by the CO ₂ regeneration tower 45 is reused CO ₂ 102 and the rest is stored CO ₂ 103. Regarding the reused CO ₂ 102, the flow rate is adjusted by the flow rate adjusting valve 51 for the reused CO ₂ according to the required amount on the gasification furnace 16 side, and the pressure is increased to a predetermined pressure by the CO ₂ compressor 52. And used as a gas for transporting and transporting the char 20.

In this example, the methanation reaction of Formula (1) is advanced in the methanation reactor 35. Therefore, it is desirable to adjust the flow rate of the product gas flowing to each system and the reaction rate in the shift reactor so that the composition of the product gas flowing into the methanation reactor 35 is CO: H ₂ = 1: 3. . The product gas temperature at the entrance of the methanation reactor 35 is set to about 250 to 300 ° C. This temperature is determined by the activation temperature of the methanation catalyst. Moreover, the methanation reaction shown in Formula (1) is an exothermic reaction. For this reason, the temperature of the product gas 55 after the methanation reaction rises at the outlet of the methanation reactor 35. Therefore, it is common to divide the methanation reactor 35 into a plurality of columns and connect them in series, and repeatedly supply the methanation reactor 35 to the methanation reactor 35 while cooling the product gas 55 after the methanation reaction. This prevents deterioration of the methanation catalyst and damage to the methanation reactor 35 due to an excessive increase in the temperature of the product gas 55 after the methanation reaction. In this embodiment, an example in which three towers of methanation reactor 35 and three coolers 73 after methanation are installed.

The main components of the product gas 55 after the methanation reaction are CH ₄ and H ₂ O. If a large amount of unreacted H ₂ and CO remain, a system for recycling at least a part of the product gas 55 after the methanation reaction to the methanation reactor 35 may be added.

The product gas 55 after the methanation reaction is cooled by the cooler 73 after the methanation and then supplied to the distillation column 56, and H ₂ O is separated by cryogenic separation to become methane 57. On the other hand, the water 58 separated by the distillation column 56 and recovered after the methanation reaction is introduced into the product gas cooling unit 18 through any one of the following systems, and the product gas 17 heated at the gasification furnace 16 is heated. Cool down.
(A) The water 58 recovered after the methanation reaction is heated by the distillation tower 56 and the cooler 73 after the methanation to form water vapor (see * b → * c). First, for regeneration heating of the CO ₂ absorbent 48 The steam 50 is supplied to the regenerative heater 49 and becomes a heat source for heating the CO ₂ absorbent 48 (see * c → * d).
(B) The water vapor after heating the CO ₂ absorbent 48 is supplied to the product gas cooling section 18 as product gas cooling water vapor 66 (see * d). A part of the regeneration heating steam 50 (* c) of the CO ₂ absorbent may be used as the shift reaction steam 36.
(C) Although not shown, the water 58 recovered after the methanation reaction is heated in the distillation column 56 to form high-temperature water (* b). First, the CO ₂ absorbent regenerative heater 49 is used for regenerative heating. A heat source for heating the CO ₂ absorbing liquid 48 is used. Next, the product gas cooling unit 18 is supplied through the spray water 63 system. Although not shown, the water 58 recovered after the methanation reaction is supplied to the product gas cooling unit 18 via the spray water 63 system.

  As described above, the methane production coal that effectively uses the water 58 recovered after the methanation reaction and the water 72 recovered after the shift reaction in the gasification system and also effectively uses the heat of the methanation reaction in the system. A gasification system can be constructed.

In order to quantitatively evaluate the effect of this system, water 72 recovered after the shift reaction and after the methanation reaction with respect to the total water flow rate (spray water 63 and shift reaction water vapor 36) used in the methane production coal gasification system. An example of a trial calculation of the ratio of the total flow rate of the collected water 58 is shown below.
(I) Water consumption in the system First, the flow rate of the product gas 17 produced in the gasifier 16 is 14,500 Nm ³ / h, the temperature is 1200 ° C., the main composition is 50% CO, 25% H ₂ , CO ₂ is assumed to be 15% and H ₂ O is assumed to be 3%. When spray water 63 is sprayed on this generated gas 17 at 25 ° C. and 5,400 kg / h (I ₁ ) is directly cooled, it is assumed that all the spray water becomes water vapor and is completely mixed with the generated gas 17. The product gas temperature after mixing is estimated to be cooled to about 200 ° C.
Water vapor was added to the cooled product gas at the entrance of the shift reaction to adjust to H ₂ O / CO = 1.2, and the shift reaction rate in the shift reactor 34 (of the CO that entered the shift reactor 34). The ratio of CO converted to CO ₂ by the shift reaction shown in Formula (3) is assumed to be 60%. Under this assumption, the flow rate of the steam 36 for shift reaction is estimated to be about 1,200 kg / h (I ₂ ). Here, the progress of the shift reaction in the product gas cooling unit 18 is not considered.
(II) Amount of water recovered in the system It is assumed that the product gas 37 after the shift reaction is cooled to about 40 ° C. upstream of CO ₂ recovery, and at this time, water vapor exceeding the saturated concentration is condensed and recovered as water. To do. The saturated concentration at 40 ° C. is about 7%, and the flow rate of the water 72 recovered after the shift reaction is about 2,690 kg / h (II ₁ ).
On the other hand, in the methanation reactor 35, it is assumed that the methanation reaction by CO and H ₂ shown in the formula (1) proceeds. Assuming that 80% of the CO contained in the product gas at the inlet of the methanation reactor 35 is methane, the product gas 55 after the methanation reaction is cooled downstream of the methanation reactor 35 to remove all moisture. . At this time, the flow rate of the water 58 recovered after the methanation reaction is estimated to be about 2,660 kg / h (II ₂ ). This flow rate of water includes water remaining as saturated steam in the product gas 37 after the shift reaction.
(III) Water balance From the above, the amount of water used in the system was approximately 6,600 kg / h of (I = I ₁ + I ₂ ), and the amount of water recovered after the shift reaction and the methanation reaction was (II = II ₁ + II ₂ ), which is about 5,350 kg / h. Therefore, the amount of water recovered after the shift reaction and after the methanation reaction is about 80% of the amount of water input to the system. From this, it is estimated that the amount of water used in the system can be reduced by about 80% if all the water recovered after the shift reaction and the methanation reaction is effectively used.

  In FIG. 2, the system | strain block diagram of the methane production coal gasification system of Example 2 is shown. Since the main system constituting the system is the same as that of the first embodiment, the differences from the first embodiment will be described below. The difference between the second embodiment and the second embodiment is that the char supply section including the char hopper and the char transport pipe is kept warm, and methanation reaction heat is used as the heat retaining heat source. The water recovered in the methanation reaction system is converted into steam superheated with methanation reaction heat, this steam is supplied to the char supply section to keep the char supply section warm, and then this steam is supplied to the product gas cooling section 18. And mixed with the product gas (see * d to * e).

The water 58 recovered in the methanation reaction system is heated in the distillation column 56 to become water vapor (* b), and further, in the cooler 73 of the methanation reaction system, by heat exchange with the product gas 55 after the methanation reaction. The steam becomes 200 to 300 ° C. or higher (* b → * c), and is supplied to the CO ₂ absorbing liquid regeneration heater 49 as the regeneration heating steam 50 of the CO ₂ absorbing liquid 48 (* c → * d). After the regenerative heater 49 heats the regenerative heating CO ₂ absorbent 48, the regenerative heating steam 50 is supplied to the char supply section as water vapor 81 that keeps the char supply section warm. The char supply unit includes a charlock hopper 21, a char feed hopper 22, a pipe connecting these, a char transport pipe, and the like. The water vapor 81 that keeps the char supply section passes through a heat insulation pipe provided on the outer periphery of the char supply section, and keeps the atmospheric temperature in the char supply section above the dew point.

  Thus, by keeping the char supply section warm, troubles such as stagnation of the transfer of the char 20 due to the generation of condensed water in the char supply section and blockage due to char aggregation in the transport pipe can be prevented. The atmosphere temperature required in the char supply unit is set higher than the saturation temperature at the operating pressure in the char supply unit. The water vapor 81 that keeps the char supply part warmed after being used as a heat source for keeping the char supply part is supplied to the product gas cooling part 18 as the water vapor 66 for cooling the product gas. Thereby, the product gas 17 which became high temperature in the gasification furnace 16 is cooled.

  According to the second embodiment, it is possible to construct a methane production coal gasification system that effectively uses water (steam) generated in the methanation reaction and reaction heat of the methanation reaction in the system.

  Further, in the second embodiment, a system is provided in which the water vapor 66 for cooling is supplied to the product gas cooling unit 18 upstream of the spray water 63 (* e). Thereby, when the concentration of water vapor is increased in the region where the temperature of the product gas 17 is about 900 ° C. or higher, the shift reaction without catalyst is expected to be promoted in the product gas cooling unit 18. If the shift reaction can be promoted in the product gas cooling unit 18, there is an effect of reducing the flow rate of the water vapor 36 for the shift reaction added in the downstream shift reactor 34 and the amount of the shift catalyst used in the shift reactor 34. Be expected.

  In FIG. 3, the system | strain block diagram of the methane production coal gasification system of Example 3 is shown. Since the main system constituting the system is the same as that of the first embodiment, the differences from the first embodiment will be described below. The third embodiment is different from the first embodiment in that a small gasification furnace 76 for gasifying the char 20 stored in the charlock hopper 21 is provided instead of the char feed hopper 22.

  In the second embodiment, the char 20 stored in the charlock hopper 21 is supplied to the char gasification furnace 76 through the char transfer valve 23. At this time, the charlock hopper equalizing valve 24 is opened to equalize the pressure of the charlock hopper 21 and the char gasification furnace 76, and measures for char transfer are required. As measures against this, it is conceivable to transfer gas into the upstream charlock hopper 21, or to vibrate by a vibrator, mechanical transfer (for example, a screw conveyor).

In the second embodiment, a description will be given of a system in which gas is introduced into the charlock hopper 21 and char is transferred to the char gasification furnace 76. As this gas, for example, a part or all of the product gas 55 after the inert gas or methanation reaction is used as the gas for char gasification. In Example 2, a part of the product gas 55 after the methanation reaction is branched downstream of the methanation reactor 35 and used as the product gas 74 (* x) for char gasification after the methanation reaction. The main components of the product gas 74 for char gasification after the methanation reaction are CH ₄ and H ₂ O (water vapor) due to the methanation reaction of the formula (1). The flow rate of the product gas is adjusted by the product gas flow rate adjusting valve 75 for char gasification after the methanation reaction. For promoting the gasification of the char, it is preferable to supply a higher-temperature product gas as described in the equation (4). For this reason, in a system in which a plurality of methanation reactors 35 are installed in series, a system for collecting the product gas for char gasification from the downstream side of the upstream methanation reactor 35 is preferable (* x).

  After the methanation reaction, the product gas 74 for char gasification is supplied to the charlock hopper 21 for transferring the char 20 and the char gasification furnace 76 for steam gasification of the char 20, respectively. In the char gasification furnace 76, the furnace temperature is maintained at 500 ° C. or higher, and the char 20 and the product gas are mixed. Thereby, the carbon content in the char is gasified by the steam gasification reaction of the char shown in the formula (4). The char gasification furnace 76 may be of a system that ensures a reaction time of the char 20 and the product gas 74 for char gasification of several seconds or more, such as a fluidized bed gasification furnace.

A dedusting device 19 is installed downstream of the char gasification furnace 76 to separate and collect the char gas 78 after steam gasification accompanied by the product gas 79 after steam gasification after the methanation reaction. The recovered char 78 after steam gasification may be stored in the char storage hopper 77 and then returned to the coal 1 supply system of the gasification furnace 16. The third embodiment shows a system for returning the char 78 after steam gasification to the lock hopper 3 of the coal 1. On the other hand, the main components of the product gas 79 after the methanation reaction and after steam gasification are CH ₄ , H ₂ O (water vapor), CO, and H ₂ . That is, since the product gas 79 after the methanation reaction and after steam gasification contains various flammable components, it is not shown, but it is burned and used for power generation and is required in the system. It is good to cover the power.

As in Example 3, in order to collect and gasify the char 20 in the product gas, the gasifying agent for the char 20 is changed from oxygen to water vapor. Thereby, the usage-amount of the oxygen 15 for gasifying the char 20 can be reduced, and the motive power of the air separator 13 which manufactures this oxygen can be reduced. Further, H ₂ O (water vapor) contained in the product gas 74 for char gasification after the methanation reaction is converted to H ₂ by the char gasification reaction and can be used as fuel or the like. Furthermore, since the char gasification reaction of Formula (4) is an endothermic reaction, the sensible heat of the product gas 74 for char gasification is used for the char gasification reaction after the methanation reaction. Thereby, size reduction of the cooler 73 after methanation is also possible.

  As described above, the methane production coal gasification system of the third embodiment not only effectively uses the water generated in the methanation reaction in the system as in the first embodiment, but also uses the reaction heat of the methanation reaction. It can be used effectively for the char gasification reaction and the amount of oxygen used can be reduced.

  In FIG. 4, the system | strain block diagram of the methane production coal gasification system of Example 4 is shown. Since the main system constituting the system is the same as that of the first embodiment, the differences from the first embodiment will be described below. The fourth embodiment is different from the first embodiment in that a system for using the sensible heat of the product gas, which has been heated by the methanation reaction, to dry the solid fuel 1 is provided.

That is, the water 58 recovered after methanation is heated in the distillation column 56 to become water vapor (* b) of 200 ° C. or higher, and the CO ₂ absorbent regenerative heater 49 as the CO ₂ absorbent regenerative heating steam 50. To be supplied. After the CO ₂ absorbent 48 for regeneration heating is heated by the regeneration heater 49 for the CO ₂ absorbent, the regeneration heating steam 50 for the CO ₂ absorbent is cooled as the product gas cooling steam 66 (* c). The product gas 17 supplied to the unit 18 and heated to a high temperature in the gasification furnace 16 is cooled. Thereby, the water generated by the methanation reaction and the reaction heat of the methanation reaction can be effectively used in the system.

  Furthermore, in the system of the fourth embodiment, the methanation reaction heat is effectively used as a drying heat source for the solid fuel 1. That is, a system of water vapor 80 circulating through the cooler and the drying device after methanation is newly installed (* d → * e). Thereby, the water vapor 80 circulating through the cooler after the methanation and the drying device is heated by heat exchange with the product gas 55 after the methanation reaction in the cooler 73 after the methanation. The heated water vapor 80 is supplied to the drying device 67 and becomes a heat source for drying the solid fuel 1. The water vapor 80 discharged from the drying device 67 returns to the cooler 73 after methanation again and is reheated.

  On the other hand, the water vapor 68 containing the scattered fuel generated by drying the solid fuel 1 by the drying device 67 is pressurized to a predetermined pressure by the steam compressor 69 containing the scattered fuel, and then supplied to the product gas cooling unit 18. The scattered fuel (solid) contained in the water vapor 68 is recovered together with the char 20 by the dust removing device 19 downstream of the product gas cooling unit 18, and is supplied to the gasification furnace 16 again through the charlock hopper 21 and the char feed hopper 22. Is done.

  As described above, according to the methane production coal gasification system of Example 4, the methanation reaction heat can be effectively used for drying the solid fuel, and the moisture in the solid fuel can also be effectively used.

  As described above, the present invention has been described based on the embodiments, but the present invention is not limited thereto, and can be implemented in a form that is modified or changed within the scope of the gist of the present invention. It will be apparent to those skilled in the art that such variations or modifications are within the scope of the claims.

  For example, as shown in FIG. 5, a part (* Y) of water vapor 68 containing scattered fuel generated in the solid fuel drying device 67 is branched and supplied to the charlock hopper 21 and the char gasification furnace 76. It is also possible to use a system that gasifies water vapor.

DESCRIPTION OF SYMBOLS 1 ... Solid fuel, 2 ... Crushing device, 3 ... Lock hopper, 4 ... Feed hopper, 5 ... Transfer valve, 6 ... Lock hopper pressure equalizing valve, 7 ... Feed hopper pressure equalizing valve, 8 ... Pressure adjusting valve, 9 ... Fuel conveyance pipe DESCRIPTION OF SYMBOLS 10 ... Fuel burner, 11 ... Air, 12 ... Compressor, 13 ... Air separator, 14 ... Nitrogen, 15 ... Oxygen, 16 ... Gasification furnace, 17 ... Product gas, 18 ... Product gas cooling part, 19 ... Dedusting 20 ... Char, 21 ... Char lock hopper, 22 ... Char feed hopper, 23 ... Char transfer valve, 24 ... Charlock hopper pressure equalizing valve, 25 ... Char feed hopper pressure equalizing valve, 26 ... Char system pressure regulating valve, 27 ... Washing tower, 28 ... desulfurization device, 29 ... product gas after desulfurization, 30 ... product gas heat exchanger, 31 ... product gas heater, 32 ... product gas flow rate adjustment valve for shift reaction system, 33 ... metaneshi Down the reaction system flow control valve in the product gas, 34 ... shift reactor, 35 ... methanation reactor, 36 ... shift reaction for steam, 37 ... product gas after the shift reaction, 38 ... of the bypass line of the CO ₂ recovery unit product gas flow adjustment valve, 39 ... CO2 recovery unit product gas flow rate regulating valve, 40 ... CO ₂ absorption tower, 41 ... CO ₂ product gas after absorption, 42 ... CO ₂ absorbed CO ₂ absorbing solution, 43 ... CO ₂ Absorption liquid heat exchanger, 44 ... CO ₂ absorption liquid heater, 45 ... CO ₂ regeneration tower, 46 ... CO ₂ absorption liquid, 47 ... Pressure pump, 48 ... CO ₂ absorption liquid for regeneration heating, 49 ... Regeneration Heater, 50 ... steam for regenerative heating of CO ₂ absorbent, 51 ... flow rate adjusting valve for reused CO ₂ , 52 ... compressor for CO ₂ , 53 ... compressor for generated gas after absorbing CO ₂ , 54 ... CO ₂ recovery Bypass system Compressor for product gas, 55 ... Product gas after methanation reaction, 56 ... Distillation tower, 57 ... Methane, 58 ... Water recovered after methanation reaction, 59 ... Char transport pipe, 60 ... Char burner, 61 ... Supply water , 62 ... makeup water flow control valve, 63 ... water spray, 64 ... rising pump spray water, 65 ... playback heating water in the CO ₂ absorbing liquid, 66 ... product gas cooling steam, 67 ... drying apparatus, 68 ... scattered Steam containing fuel, 69 ... Compressor for steam containing scattered fuel, 70 ... Cooler, 71 ... Drum, 72 ... Water recovered after shift reaction, 73 ... Cooler after methanation, 74 ... After methanation reaction Product gas for char gasification, 75... Flow adjustment valve for product gas for char gasification after methanation reaction, 76 ... Char gasification furnace, 77 ... Char storage hopper, 78 Char after steam gasification, 79 ... Product gas after steam gasification after methanation reaction, 80 ... Steam circulating through cooler and drying apparatus after methanation, 81 ... Steam to keep char supply means warm, 82 ... flow control valve of the circulating CO _2, 101 ... recovered _CO 2, 102 ... recycled _CO 2, 103 ... storage CO ₂

Claims (8)

Gasification means for solid fuel, first cooling means for the product gas generated in the gasification means, dust removal and purification means for the product gas, methanation reaction means for producing methane from the dust and purified product gas, and methanation A second cooling means for the product gas after the reaction, and a methane distillation means for separating methane and water of the cooled product gas after the methanation reaction,
The water separated by the methane distillation means is supplied to the first cooling means and mixed with the product gas generated by the gasification means. Gasification means for solid fuel, first cooling means for product gas generated in the gasification means, dust removal and purification means for the product gas, shift reaction means for the dust gas purified and purified, and product gas after the shift reaction Second cooling means, CO ₂ recovery means for recovering CO ₂ in the cooled product gas after the shift reaction, methanation reaction means for producing methane from the CO ₂ recovered product gas, and product gas after the methanation reaction A third cooling means, and a methane distillation means for separating methane and water of the product gas after the cooled methanation reaction,
The water condensed by the second cooling means of the product gas after the shift reaction and the water separated by the methane distillation means are supplied to the first cooling means of the product gas, and the generated gas generated by the gasification means A solid fuel gasification system for methane production characterized by mixing with methane. Gasification means for solid fuel, first cooling means for product gas generated in the gasification means, dust removal and purification means for the product gas, shift reaction means for the dust gas purified and purified, and product gas after the shift reaction second cooling means, the CO ₂ recovery unit the CO ₂ in the product gas after the cooled shift reaction recovered using CO ₂ absorbing solution, methanation reaction unit for methane production from the product gas after CO ₂ recovered in, A third cooling means for the product gas after the methanation reaction, and a methane distillation means for separating methane and water of the cooled product gas after the methanation reaction,
Water separated in the methane distillation unit, the heat is supplied to the third cooling means of the product gas after the methanation reaction, supplying the water that has been said heated CO ₂ regeneration tower in the CO ₂ recovery unit And at least a part of the CO ₂ absorbent is used as a heat source for regenerative heating, and the water obtained by heating the CO ₂ absorbent in the CO ₂ regeneration tower is supplied to the first cooling means for the product gas, A methane production solid fuel gasification system characterized by mixing with generated product gas. Gasification means for solid fuel, first cooling means for generated gas generated by the gasification means, dust removal and purification means for the generated gas, and char supply means for supplying the char recovered by the dust removal means to the gasification means , Methanation reaction means for producing methane from dedusted and purified product gas, second cooling means for product gas after methanation reaction, and methane for separating methane and water of product gas after cooled methanation reaction Having distillation means;
The water separated by the methane distillation means is supplied to the second cooling means for the product gas after the methanation reaction and heated, and the heated water is supplied as a heat source for keeping the char of the char supply means. The methane production solid fuel gasification system is characterized in that the water retaining the char is supplied to the first cooling means for the produced gas and mixed with the produced gas generated by the gasification means. Gasification means for solid fuel, first cooling means for product gas generated by the gasification means, dust removal and purification means for the product gas, char gasification means for gasifying the char recovered by the dust removal means, dust removal and Having a methanation reaction means for producing methane from the purified product gas,
A methane production solid fuel gasification system, wherein a product gas containing water vapor generated by the methanation reaction means is supplied as a gasifying agent for the char gasification means. In the methane production solid fuel gasification system according to claim 1,
On the upstream side of the gasification means of solid fuel, there is a means for drying solid fuel,
Providing a water vapor circulation system for circulating between the second cooling means of the product gas after the methanation reaction and the drying means of the solid fuel;
The methane production solid fuel gasification system, wherein the water vapor circulation system circulates the water vapor heated at the second cooling means as a heat source of the drying means for drying the solid fuel. The methane production solid fuel gasification system according to claim 6,
A solid fuel gasification system for producing methane characterized in that a gas containing water vapor generated by the drying means for solid fuel is supplied to the first cooling means to cool the produced gas. In the methane production solid fuel gasification system according to claim 6,
Furthermore, it has a char gasification means for gasifying the char recovered by the dust removal means,
A methane production solid fuel gasification system, characterized in that a gas containing water vapor generated by the drying means of solid fuel is supplied to the char gasification means.

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