WO2011029282A1

WO2011029282A1 - Method for preparing methane-containing gas through multi-region coal gasification and gasification furnace thereof

Info

Publication number: WO2011029282A1
Application number: PCT/CN2010/001406
Authority: WO
Inventors: 毕继诚; 李克忠; 毛燕东; 曲旋; 张�荣; 孙东凯; 程相龙; 李金来; 甘中学
Original assignee: 新奥科技发展有限公司
Priority date: 2009-09-14
Filing date: 2010-09-14
Publication date: 2011-03-17
Also published as: CN102021039A

Abstract

A method for preparing methane-containing gas through multi-sectional coal gasification and the gasification furnace thereof are provided. Said gasification furnace has a partial pyrolysis region (40), a catalytic gasification region (41) and a residue gasification region (42). Said method comprises following steps: a) coal powders are added to the partial pyrolysis region (40) of the gasification furnace having the partial pyrolysis region (40), the catalytic gasification region (41) and the residue gasification region (42), where the coal powders contact with the gas stream from the catalytic gasification region (41) so as to partially pyrolyze the coal powders and produce a gas stream containing methane and partially pyrolyzed coal powders; b) the partially pyrolyzed coal powders are sent to the catalytic gasification region (41) to contact with the gas stream from the residue gasification region (42) in the presence of a catalyst, the generated gas stream is supplied to the partial pyrolysis region(40), and the insufficiently reacted coal residue is supplied to the residue gasification region (42); and c) the coal residue is contacted with a gasification agent in the residue gasification region (42), the obtained gas stream is supplied to the catalytic gasification region (41), and the generated ash residue is discharged out of the gasification furnace.

Description

Method and apparatus for preparing gas containing formazan by multi-zone coal gasification

The present invention relates to the field of coal gasification for the preparation of alternative natural gas, and more particularly to a method and apparatus for the preparation of methane-containing gas by multi-zone coal gasification.

Background technique

China is a country rich in coal and oil-poor. With the rapid development of society and economy, the demand for natural gas in China has risen sharply, and the proportion in the energy structure has increased rapidly. Domestic natural gas is still in the early stage of exploration and development, and imports are still in their infancy. The supply capacity is seriously stagnant, leading to a growing contradiction between natural gas supply and demand. The use of coal with relatively large resource advantages in China can not only promote the efficient and clean utilization of coal; but also utilize existing natural gas pipelines to effectively alleviate the contradiction between supply and demand of natural gas at a lower economic cost. This is a synthesis of inferior coal resources. Powerful measures to take advantage of.

The usual coal gasification technology, that is, the gasification of coal at a high temperature with oxygen (or air) and/or steam (also called steam), produces a synthesis gas containing a small amount of methane (CH ₄ ) ( Mainly hydrogen, carbon monoxide and carbon dioxide), followed by a water gas shift and a decaneization process, and a two-step process for the preparation of decane. The coal gasification technology has the disadvantages of high temperature required for gasification reaction, high energy consumption, high requirements on equipment, three reaction devices and complicated processes.

Coal catalytic gasification technology is an important way to clean and use coal. The coal catalytic gasification technology uses coal at a relatively low temperature with steam (H ₂ 0 ) and hydrogen (H ₂ ) to produce high concentrations. Decane (CH ₄ ). Compared with other coal gasification technologies, coal catalytic gasification technology has the advantages of high methane content and low temperature required for gasification reaction.

At present, the coal-catalyzed gasification technology mentioned in the relevant patents, the optimum temperature and pressure range required for gasification reaction are 593 ~ 700" and 20 ~ 40atm, using alkali metal carbonate As a catalyst. The cryogenic separation is used to separate the decane in the gas from the carbon monoxide and hydrogen, and the hydrogen and carbon monoxide in the reaction gas are circulated to the gasification furnace to be converted into methane in the gasification furnace, thereby improving System methane production. The coal catalytic gasification technology has the disadvantages of low gasification reaction rate, long reaction time, low carbon conversion rate and high investment in gas separation system; in order to meet the heat balance of the reactor, it is necessary to heat the furnace superheated steam to a higher temperature. Steam superheating systems and heat exchange systems have high loads and poor economics.

U.S. Patent 4,077,778 proposes a coal catalytic gasification process using a multi-stage fluidized bed reactor to eliminate the deficiencies of the original catalytic gasification process, to make gasification more efficient, to fully utilize feed carbon resources, and to improve carbon conversion. rate. The mainstream bed reactor operates at a higher gas velocity, entraining a portion of the carbon particles to the secondary fluidized bed reactor, performing a gasification reaction at a lower gas velocity, increasing the solid phase residence time, and maximizing the carbon conversion rate.多 Multi-stage gasification can increase carbon utilization from 70 - 85% to over 95% compared to single-stage gasification. However, the coal catalytic gasification process uses a plurality of fluidized bed reactors, which have high equipment investment and complicated operation.

In addition, U.S. Patent No. 4,094,65 (which is incorporated herein by reference to the catalyzed action of an alkali metal, can vaporize a carbonaceous solid to produce a decane, and the catalyst needs to be recycled. The water-soluble catalyst is recovered by multistage washing, and the lime is digested. Recycling of non-soluble catalysts. U.S. Patent No. 0,277,437, based on U.S. Patent No. 4,094,650, which utilizes a primary treatment to separate alkali metal from the solid residue of the reactor, simplifies the recovery of the alkali metal catalyst and improves the catalytic gasification process. Economic and total efficiency, but the recycling system is still more complicated and the recycling method is more expensive.

In addition, in order to make full use of heat and to produce gas, U.S. Patent No. 5,064,444 proposes a method of gasification of pressurized steam, and the fluidized bed gasification furnace is divided into a pyrolysis section, a gasification section, and a cooling section. Separate with a partition. A serpentine coil (snake heat exchanger) is placed in the pyrolysis section and the gasification section of the gasification furnace, and a high temperature gas of 900 Ό - 9501 C is passed through the tube to heat the pulverized coal with a gas after combustion of the fuel to provide a gasification and pyrolysis solution. Heat is needed to make gas. The fluidized bed The gasifier can be vertical or horizontal, with 700-800 superheated steam as the gasifying agent, and the cooling section is fed with saturated steam. The coal powder is entrained in the superheated steam and enters the gasifier. However, the utilization rate of the reaction volume in the gasification furnace is low, which affects the solid phase processing; only the superheated steam is used as the gasifying agent, so that the carbon conversion rate is not high, so the carbon content in the residue is high, and the coal is difficult to be effectively utilized; The heat in the high-temperature gas needs to be transmitted to the coal powder and steam through the wall of the serpentine coil. Compared with the gas-solid contact heat transfer, the indirect heating method has a slow heat transfer rate and low thermal efficiency, and the solid phase in the bed is not heated. At the same time; the equipment is complicated, especially the horizontal furnace.

Summary of the invention

The present application provides a method for preparing a gas containing decane by multi-zone coal gasification, comprising the following steps:

a. adding pulverized coal to a partial pyrolysis zone of a gasification furnace comprising a partial pyrolysis zone, a catalytic gasification zone and a residue gasification zone, where the pulverized coal is in contact with a gas stream from the catalytic gasification zone for partial heat Solving the pulverized coal to form a methane-containing gas stream and a partially pyrolyzed coal powder,

b. feeding the partially pyrolyzed coal powder into the catalytic gasification zone and contacting the gas stream from the residue gasification zone in the presence of a catalyst, the generated gas stream entering a partial pyrolysis zone, and the insufficiently reacted coal residue enters Residue gasification zone, and

c. The coal residue is contacted with the gasifying agent in the residue gasification zone, and the generated gas stream enters the catalytic gasification zone and the generated ash is discharged to the gasification furnace.

The present application also provides a method for preparing a gas containing decane by multi-zone coal gasification, which comprises the following steps:

1) adding pulverized coal to a catalytic gasification zone of a gasification furnace containing a catalytic gasification zone and a residue gasification zone, where the pulverized coal is contacted with a gas stream from the residue gasification zone in the presence of a catalyst to form a a gas stream of decane and an insufficiently reacted coal residue, and

2). The coal residue from step 1) is sent to the residue gasification zone to contact the gasifying agent. The resulting gas stream enters the catalytic gasification zone and the resulting ash is discharged from the gasifier.

The present application also provides a gasification furnace for preparing a gas containing formamidine by coal gasification, which comprises, from top to bottom, in order:

a partial pyrolysis zone for contacting the pulverized coal with a gas stream from the catalytic gasification zone, and the generated methane-containing gas stream exits the gasification furnace and the generated partially pyrolyzed coal powder is sent to the catalytic gasification zone;

b. a catalytic gasification zone for contacting a portion of the pyrolyzed coal powder from the partial pyrolysis zone with a gas stream from the residue gasification zone, the resulting gas stream entering the pyrolysis zone and the less fully reacted coal residue Delivered into the residue gasification zone; and

The c residue gasification zone is for contacting the coal residue from the catalytic gasification zone with a gasifying agent, and the generated gas stream enters the catalytic gasification zone and the generated ash is discharged to the gasification furnace.

The present application also provides a gasification furnace for preparing a gas containing decane by gasification, which comprises, from top to bottom, in order:

a catalytic gasification zone for contacting the pulverized coal with a gas stream from the residue gasification zone in the presence of a catalyst to form a methane-containing gas stream and an insufficiently reacted coal residue;

2) A residue gasification zone for contacting the coal residue from the catalytic gasification zone with a gasifying agent, and the generated gas stream enters the catalytic gasification zone, and the generated ash is discharged to the gasification furnace.

DRAWINGS

1 is a schematic structural view of a gasification furnace according to an embodiment of the present invention;

It is to be understood that the appended drawings are not intended to The scope of the invention should be determined by the content of the claims. Detailed description of the invention In a first embodiment, the present application provides a method of multi-zone coal gasification to produce a gas containing decane, comprising the steps of:

a. adding pulverized coal to a partial pyrolysis zone of a gasification furnace containing a partial pyrolysis zone, a catalytic gasification zone and a residue gasification zone, where the coal powder and the gas powder from the catalytic gasification zone, '凡凡^{, U} "

b. feeding the partially pyrolyzed coal powder to a catalytic gasification zone and contacting the gas stream from the residue gasification zone in the presence of a catalyst, the resulting gas stream entering a partial pyrolysis zone and an insufficiently reacted coal residue entering Residue gasification zone, and

c. contacting the coal residue with the gasifying agent in the residue gasification zone, and the generated gas stream enters the catalytic gasification zone and the generated ash is discharged to the gasification furnace.

The core equipment employed in the method of the present invention is a multi-zone gasifier. The gasifier is generally placed vertically or tilted, and is inclined at an angle sufficient to cause the solid material in the furnace, such as pulverized coal, to move downward under its own weight. The gasifier can be divided into three zones from bottom to top using a distribution plate. According to the functions of each zone, the residue gasification zone, the catalytic gasification zone and the partial pyrolysis zone are sequentially shown in Fig. 1. The distribution plate is typically a multi-hole distribution plate. The solid material, such as coal, moves from top to bottom, and finally leaves the gasifier from the slag discharge port at the bottom of the gasifier, while the gaseous material moves from bottom to top, and finally exits the gas from the exhaust port at the top of the gasifier. Furnace. The solid material and the gaseous material are in substantially countercurrent contact in the gasifier. In the gasifier of the present invention, the closer the temperature is to the bottom, the lower the temperature is, the closer it is to the top.

In the process of the present invention, the feed locations of the coal, gasification agent and catalyst can be selected or adjusted as desired. For example, at least a portion of the coal may enter the gasifier from any one or more of the partial pyrolysis zone and/or the catalytic gasification zone of the gasifier of the present invention; even when the heat generated by the gasification of the residue alone is insufficient When maintaining the temperature requirements for catalytic gasification, a portion of the coal can also be passed from the residue gasification zone to the gasifier. Catalyst The feed mode can be divided into two types, and a catalyst which can be gasified at a high temperature in the residue gasification zone of the present invention, such as an alkali metal carbonate, can be partially pyrolyzed from the gasifier and/or a catalytic gas. The chemical zone and/or the residue gasification zone are passed to the gasification furnace; and for the catalyst which cannot be gasified at the high temperature of the residue gasification zone of the present invention, such as an alkaline earth metal carbonate, from the partial pyrolysis zone and/or Or the catalytic gasification zone is passed to the gasifier; and the gasification agent is passed into the gasifier from the bottom and/or side of the residue gasification zone. Regardless of the region from which the coal and catalyst are fed, they eventually contact each other in the catalytic gasification zone of the gasifier and simultaneously with the gas stream containing the syngas. Obviously, the coal and the catalyst may also be mixed, for example, the coal powder is directly mixed with the catalyst itself, or the coal powder is mixed with the aqueous catalyst solution, and the like. When the feed is mixed, the mixture of the two may be fed from one or more of the catalytic gasification zone and/or the coal pyrolysis zone. The granules of the pulverized coal may be generally 0.1 to 1 mm, and may be pulverized to a pulverized coal.

Step a of the first embodiment of the present invention occurs in a partial pyrolysis zone of the gasification furnace, the coal added to the zone is in contact with the gas stream from the catalytic gasification zone, and the coal powder is partially pyrolyzed to form a A gas stream of decane and a partially pyrolyzed coal powder. All of the gas in the zone leaves the gasifier and the partially pyrolyzed coal moves down the gasifier. In this step, at least a portion of the coal is passed from the partial pyrolysis zone to a gasifier, preferably a majority of the coal, even more preferably all of the coal, is passed from the partial pyrolysis zone to the gasifier. The advantage of this is that the heat released by the methanation reaction of the synthesis gas in the catalytic gasification zone is fully utilized, and the heat enters the partial pyrolysis zone with the gas after the reaction in the catalytic gasification zone, and the partial pyrolysis zone The coal entering the gasifier is contacted, the coal is preheated and rapidly pyrolyzed, and the volatiles in the coal are pyrolyzed. Since the volatile matter of the coal contains methane, the zone not only plays a role in preheating the coal. Further, the decane content in the gaseous product is further increased by partial pyrolysis of the coal. Pyrolysis also produced The tar, the tar leaves the gasifier with the gas product under the conditions of the zone, and the partially pyrolyzed coal powder enters the lower area of the gasifier to continue the reaction. The temperature in the portion of the pyrolysis zone is primarily regulated by the gas flow rate of the zones below and the amount of coal powder fed to the zone, typically 450-650 Torr.

Step b of the first embodiment of the invention occurs in the catalytic gasification zone of the gasifier. In this step, the partially pyrolyzed coal powder is fed into the catalytic gasification zone and contacted with the gas stream from the residue gasification zone by the catalyst to react and form a gas stream and an insufficiently reacted coal residue, wherein The resulting gas stream mainly contains CH ₄ , C0, H ₂ and C0 ₂ , and a small amount of H ₂ S, NH ₃ and the like. The main reactions occurring in this catalytic gasification zone are as follows:

2C + 2H ₂ 0 → 2H ₂ + 2C0 (1)

CO + H ₂ 0 → C0 ₂ + H ₂ (2)

3H ₂ + CO → CH ₄ + H ₂ 0 (3)

C + 2H ₂ → CH ₄ (4)

The reaction temperature of the catalytic gasification zone is 650 ~ 750 "C, and the pressure is 0. l ~ 4MPa (absolute pressure, the same below). In the catalytic gasification zone, CO and H from the gasification zone of the gasifier residue _{2 The} methanation reaction occurs under the action of the catalyst. As shown in the reaction formula (3), the yield of decane is increased, and the heat of reaction released is carried upward by the reaction-generated gas into the partial pyrolysis zone. In step a, the coal residue which is not sufficiently reacted enters the residue gasification zone. In addition, carbon gasification reactions (1) and (4), carbon monoxide shift reaction (2), etc. occur, wherein the catalyst is selected from the group consisting of: (1) an alkali metal or alkaline earth metal oxide, carbonate, hydroxide, acetate, nitrate, lS compound or a mixture thereof, such as sodium oxide, calcium oxide, sodium carbonate, potassium carbonate, lithium carbonate, Calcium carbonate, potassium hydroxide, sodium hydroxide, calcium hydroxide, sodium acetate, calcium nitrate, calcium chloride, etc.; or (2) oxides of transition metals, such as oxides of iron, cobalt, nickel, molybdenum, etc.; Above (1) and (2) a mixture of catalysts In the case of an oxide, a transition metal oxide can be formed in situ by adding a decomposable salt or hydroxide of a transition metal to the gasifier because these decomposable salts or hydroxides are at a high temperature in the gasifier. It is easily decomposed into the corresponding oxides. 5〜 0. 2。 The ratio of the ratio of the catalyst and the pulverized coal is 0. 05 ~ 0. 2.

Step c of the first embodiment of the present invention occurs in the residue gasification zone of the gasifier. After the coal residue of step b enters the zone, it is contacted with a gasifying agent which is introduced into the zone, wherein the gasifying agent contains oxygen and saturated steam or superheated steam, wherein the temperature of the superheated steam may be 200-500. The weight ratio of the oxygen entering the gasifier to the coal powder entering the gasifier is 0.1 to 1. 0. The superheated steam and oxygen may be passed to the zone as a mixture, or may be passed to the zone separately and mixing occurs in the zone. The main reactions that occur in this area are as follows:

C + 0 ₂ → C0 ₂ (5)

C + C0 ₂ → 2C0 (6)

C + H ₂ 0 → CO + H ₂ (7)

CO + H ₂ 0 → C0 ₂ + H ₂ (8) These reactions produce a gas stream including synthesis gas and ash, in which the total conversion of carbon can be over 90%. The gas stream including the syngas further includes carbon dioxide and unreacted water vapor and possibly oxygen, the gas stream is directed upward into the catalytic gasification zone to perform step b, and the ash is discharged Gasifier. Since the reaction in this zone is a strong oxidation reaction, a large amount of heat is released, so the temperature in this zone is the highest in the gasifier. The temperature of the zone can be controlled at a temperature suitable for the synthesis gas by adjusting the feed rate and/or composition of the gasifying agent, typically 800-1200 "C, and the heat of reaction released is the above catalytic gasification. The zone provides heat, in which the weight ratio of the incoming steam to the coal entering the gasifier is generally 0 - 1 0. The weight ratio of the oxygen to the gas entering the gasifier is generally 0.1 to 1. 0. If the catalyst used in the process of the present invention is not vaporizable at the temperature of the zone, the catalyst is withdrawn from the gasifier as the ash is passed to the catalyst recovery unit for recovery; if the catalyst employed in the process of the invention is The gas can be vaporized at the temperature of the zone, and the catalyst is vaporized into a vapor and flows upward into the catalytic gasification zone along with the gas stream including the synthesis gas, and condenses on the coal as the gas temperature decreases. Repeat the catalytic effect.

Alternatively, more broadly, in the method of producing a methane-containing gas by multi-zone coal gasification of the present invention, a part of the pyrolysis zone may be omitted, and therefore, the method of the present invention may include the following steps.

1) adding pulverized coal to a catalytic gasification zone of a gasification furnace containing a catalytic gasification zone and a residue gasification zone, where the pulverized coal is contacted with a gas stream from the residue gasification zone in the presence of a catalyst to form a a gas stream of methane and an unreacted coal residue, and

2) The coal residue of step 1) is sent to the residue gasification zone to be in contact with the gasifying agent, and the generated gas stream enters the catalytic gasification zone and the ash is discharged to the gasification furnace.

At least a portion of the coal enters the gasifier from the catalytic gasification zone. In step 1), the coal is contacted with the gas stream from the residue gasification zone in the presence of the catalyst in the catalytic gasification zone to form a decane-containing gas stream and an insufficiently reacted coal residue, wherein the catalyst, temperature, pressure process The conditions and the like are substantially the same as those described above for the step b of the first embodiment, the generated decane-containing gas stream flows upwardly out of the gasifier, and the unreacted coal residue moves downward to the residue gasification. Area.

In step 2), the coal residue from step 1) enters the residue gasification zone and is contacted with a gasifying agent, wherein the reaction occurring in step 2), the type and composition of the gasifying agent, the composition of the generated gas stream, The process conditions of temperature, pressure and the like are also substantially the same as step c of the first embodiment above.

The invention also relates to a gasification furnace for preparing a gas containing methane by coal gasification, from the top to the The following includes:

a part of the pyrolysis zone for contacting the pulverized coal with the gas stream from the catalytic gasification zone, and the generated decane-containing gas stream exits the gasifier and generates a portion of the pyrolyzed pulverized coal to be fed to the catalytic gasification zone ;

b. a catalytic gasification zone for contacting a portion of the pyrolyzed coal powder from the partial pyrolysis zone with a gas stream from the residue gasification zone, the resulting gas stream entering the partial pyrolysis zone and the less fully reacted coal The residue is sent to the residue gasification zone; and

c. a residue gasification zone for contacting the coal residue from the catalytic gasification zone with a gasifying agent, and the generated gas stream enters the catalytic gasification zone, and the generated ash is discharged to the gasification furnace.

The zones are separated by a distribution plate having holes for the passage of gaseous material. The gas distribution plate is further provided with an overflow device having a tubular form open at both ends, and the overflow device is for flowing the solid phase raw material from the upper layer to the lower layer space from the upper space through the overflow device.

Alternatively, a part of the pyrolysis zone may be omitted. In this case, the gasification process for producing a methane-containing gas by coal gasification of the present invention includes:

a catalytic gasification zone for contacting pulverized coal with a gaseous stream from the residue gasification zone in the presence of a catalyst to form a decane-containing gas stream and an insufficiently reacted coal residue;

Feeding equipment for introducing materials such as coal, a catalyst, a mixture of coal and a catalyst, a gasifying agent, etc. into a gasifier may be provided in each zone of the gasifier as needed, and these feeding apparatuses are those skilled in the art. openly known. In addition, at the bottom end and the top end of the gasifier, there is also a discharge device for the gas and ash to leave the gasifier, and these discharge devices are provided. It is also well known to those skilled in the art.

In a preferred embodiment, the gasifier of the present invention includes equipment for introducing at least a portion of the coal from any one or more of the partial pyrolysis zone and/or the catalytic gasification zone of the gasifier to the gasifier. These feeding devices can include silos, rotating feed devices, and the necessary connecting pipes. Depending on whether the gasifier is at atmospheric or high pressure gasification, the feed equipment can be operated at atmospheric or high pressure.

In another preferred embodiment, the gasifier of the present invention comprises an apparatus for mixing a catalyst into pulverized coal and an apparatus for directly feeding the catalyst to a gasifier.

In another preferred embodiment, the gasifier of the present invention further comprises means for transporting at least partially pyrolyzed coal fines from the pyrolysis zone to the catalytic gasification zone, such as an overflow pipe, etc., and for use in coal The equipment for transporting the residue from the catalytic gasification zone to the residue gasification zone, such equipment may be a slagging apparatus known in the art. In a preferred embodiment, two slagging devices are arranged in series at the outlet of the bottom end of the gasifier, wherein a valve, a secondary slagging device and a primary slag are arranged between the primary slag discharging device and the gasification furnace. There are also valves between the devices, and the two slag discharge devices are also provided with a venting valve and a charging valve. When discharging the slag, the valve between the primary slag discharging device and the secondary slag discharging device is first closed, and The valve between the primary slag discharge device and the gasifier is opened, and the ash is discharged into the primary slag discharge device. After the quality of the ash received by the primary slagging device reaches a set threshold, the charging valve of the secondary slagging device is opened to charge the secondary slag discharging device, and the pressure of the secondary slag discharging device and the primary slag discharging When the pressure of the equipment is the same, the communication valve between the first-stage slagging equipment and the second-stage slagging equipment is opened, and the solid in the first-stage slagging equipment is sent to the second-stage slagging equipment, and the first-stage slagging equipment is closed. The communication valve between the slagging devices opens the venting valve of the secondary slagging device to relieve the pressure of the secondary slag discharging device, and discharges the ash in the secondary slag discharging device.

The method for carrying out the invention using the gasifier of the present invention further comprises a pulverized coal preparation device, a mixing device for mixing the catalyst with the pulverized coal, a device for drying and pre-oxidizing the mixture, and a pulverized coal feeding device, both of which are It is well known in the art. The method of the present invention using the gasifier of the present invention further comprises means for separating and purifying the methane-containing gas stream leaving the gasifier and slagging equipment for discharging the ash from the bottom of the gasifier, The field is well known.

Example

The following examples are given to illustrate the invention, which are not intended to be limiting.

Referring to Fig. 1, the gasification furnace of Fig. 1 includes three zones from top to bottom, which are a partial pyrolysis zone 40, a catalytic gasification zone 41, and a residue gasification zone 42. The raw coal enters part of the pyrolysis zone 40 through the pipeline 43, and the temperature of the partial pyrolysis zone 40 is 450 ~ 650t, and the gas stream from the catalytic gasification zone 41 heats the raw coal powder in the partial pyrolysis zone ^{40 to} cause it to occur. Partial pyrolysis and hydropyrolysis to obtain decane-containing gas products, tar and pyrolysis pulverized coal. The gaseous product and tar exit the gasifier from the outlet line 48 and enter the subsequent separation equipment. The pyrolyzed coal powder moves downward into the catalytic gasification zone 41. A further portion of the coal and catalyst enters the catalytic gasification zone from line 44 in the form of a mixture together with the pyrolyzed coal powder from the partial pyrolysis zone in the catalytic gasification zone 41 and from the residue gasification zone. The gas stream reacts and the reaction is as shown in the above reaction formulas (1) - (4) to form a gaseous product. There are mainly CH ₄ , C0, and C0 ₂ , and a small amount of H ₂ S and NH ₃ and the like. These gaseous products move upward into a portion of the pyrolysis zone 40 to pyrolyze the coal. The temperature of the catalytic gasification zone 41 is 650-75 O. The coal residue which is not sufficiently reacted enters the residue gasification zone 42 downward, and under the action of the superheated steam 46 and the oxygen gas 47 introduced, the reaction represented by the above reaction formulas (5) to (8) occurs, and the synthesis is carried out. The gas product and the solid ash, which are gas, move up to the catalytic gasification zone 41 for reaction, and the ash is discharged to the gasifier through the primary slag discharge device 50 and the secondary slagging device 51. 5MPa压力。 Under the pressure of 3. 5MPa.

The advantages of the invention are as follows:

(1) retaining the characteristics and advantages of catalytic gasification, and obtaining a higher content of decane, gram Difficulties in the catalytic gasification alone, such as longer reaction time, higher ash content of discharged ash, etc.;

(2) Multi-zone coupled gasification, part of the pyrolysis zone of the gasification furnace of the present invention uses the residual temperature of the catalytic gasification gas to heat the newly entered pulverized coal, partially pyrolysis, and produces methane gas and the like, without increasing The decane and tar are added under the condition of energy consumption; the main reaction of catalytic gasification occurs in the catalytic gasification zone; the residual gasification zone passes through the gasification agent to gasify the remaining residue, and provides catalysis by burning and gasification of the residue. The heat required for gasification, while providing hydrogen and CO, is beneficial to the catalytic gasification reaction;

(3) Compared with the two-step method for preparing decane, the device integrates multiple reactors to realize the coupling of the flow and the heat coupling, and the self-supply heat reduces the energy consumption of the superheated steam, and solves the problem of carbon residue in the residue; The average residence time increases gas production capacity and increases carbon conversion.

(4) From the whole process, the methane-rich gas is prepared by gasification of the multi-zone gasifier, which has high thermal efficiency, high solid phase processing depth, high decane content in the gas product, and simple and easy operation.

Claims

Rights request

1. A method for preparing a methane-containing gas by multi-zone coal gasification, comprising the steps of: a. adding pulverized coal to a partial pyrolysis zone of a gasification furnace comprising a partial pyrolysis zone, a catalytic gasification zone and a residue gasification zone, Wherein the pulverized coal is contacted with a gas stream from the catalytic gasification zone to partially pyrolyze the pulverized coal to form a decane-containing gas stream and a partially pyrolyzed coal powder,

2. The method of claim 1 wherein at least a portion of the coal enters the gasifier from any one or more of a portion of the gasification zone and/or the catalytic gasification zone of the gasifier.

3. The method according to claim 1, wherein the catalyst is selected from the group consisting of: (1) an alkali metal or alkaline earth metal oxide, carbonate, hydroxide, acetate, nitrate, halide or a mixture thereof; Or (2) an oxide of a transition metal; or a mixture of (1) and (2) above.

4. The method of claim 1 or 2, wherein the temperature of the partial pyrolysis zone is in the range of 450-650, the temperature of the catalytic gasification zone is in the range of 650-750X, and the temperature of the residue gasification zone is in the range of 800-1200, gasification The pressure in the furnace is in the range of 0.1 to 4 MPa.

5. A method according to claim 1 or 2, said gasifying agent being passed from the bottom of the gasifier, which contains oxygen as well as saturated or superheated steam.

6. The method of claim 5, wherein the weight ratio of the superheated steam to the coal entering the gasifier is 0. 5-5, the weight of the oxygen fed into the gasifier and the coal entering the gasifier The ratio is 0. 1-1. 0.

7. Multi-zone coal gasification process for preparing decane-containing gas, comprising the following steps

2) The coal residue of step 1) is sent to the residue gasification zone to be in contact with the gasifying agent, and the generated gas stream enters the catalytic gasification zone and the generated ash is discharged to the gasification furnace.

8. The method according to claim 7, wherein the catalyst is selected from the group consisting of: (1) an alkali metal or alkaline earth metal oxide, carbonate, hydroxide, acetate, nitrate, halide or a mixture thereof; Or (2) an oxide of a transition metal; or a mixture of (1) and (2) above.

The method of claim 7, wherein the catalytic gasification zone temperature is in the range of 650-750 Torr, the residue gasification zone temperature is in the range of δ Ο Ο - ,, and the gasifier pressure is in the range of 0.1 - 4 MPa.

10. The method of claim 7 wherein said gasifying agent is passed from the bottom of the gasifier and contains oxygen and saturated or superheated steam.

11. The method of claim 3 or 8, wherein the transition metal is selected from the group consisting of iron, cobalt, nickel, molybdenum or mixtures thereof.

12. The method of claim 3 or 8, wherein the transition metal oxide is generated in situ by adding a decomposable salt or hydroxide of the transition metal to a gasifier.

13. Coal gasification gasifier for the preparation of decane-containing gas, which in order from top to bottom includes:

a partial pyrolysis zone for contacting the pulverized coal with a gas stream from the catalytic gasification zone, and the generated methane-containing gas stream exits the gasification furnace and the generated partially pyrolyzed coal powder is sent to the catalytic gasification zone; b. a catalytic gasification zone for contacting a portion of the pyrolyzed coal powder from the partial pyrolysis zone with a gas stream from the residue gasification zone, the resulting gas stream entering the partial pyrolysis zone and the less fully reacted coal The residue is sent to the residue gasification zone; and

C. Residue gasification zone for contacting the coal residue from the catalytic gasification zone with the gasification agent, and the generated gas stream enters the catalytic gasification zone, and the generated ash is discharged to the gasification furnace.

14. The gasifier of claim 13 further comprising means for adding at least a portion of the coal to the gasifier from any one or more of the partial pyrolysis zone and/or the catalytic gasification zone of the gasifier.

The gasifier according to claim 13 or 14, further comprising means for mixing the catalyst into the pulverized coal and means for directly adding the catalyst to the gasifier.

16. The gasifier of claim 13 or 14 further comprising means for transporting partially pyrolyzed coal fines from the pyrolysis zone to the catalytic gasification zone and for transporting the coal residue from the catalytic gasification zone to the residual gas Equipment in the district.

17. Coal gasification furnace for the preparation of decane-containing gas, which in turn comprises from top to bottom:

1) a catalytic gasification zone for contacting the pulverized coal with a gas stream from the residue gasification zone in the presence of a catalyst to form a methane-containing gas stream and an insufficiently reacted coal residue;

18. The gasifier of claim 17 further comprising: means for mixing the catalyst into the pulverized coal and means for directly introducing the catalyst to the gasifier.

19. The gasifier of claim 17 further comprising means for transporting the coal residue from the catalytic gasification zone to the residue gasification zone.

20. The gasifier of claim 13 or 17, further comprising two series of slagging devices disposed at the outlet of the bottom end of the gasifier.

21. The gasifier of claim 13 or 17, wherein said zones are separated by a porous distribution plate.

22. The gasifier of claim 13 or 17, further comprising an overflow tube for moving the coal downward