CN1597871A - Technical process for gasification of fluidized-bed CO gasifying furnace and apparatus thereof - Google Patents

Abstract

The invention relates to a new coal gasification process in the field of coal chemical industry, and relates to a gasification process and a device for a fluidized bed CO gasifier using _O2 + _CO2 or air+ _CO2 as a gasification agent. It uses O ₂ and CO ₂ as gasification agents, 0-10mm coke powder and anthracite as raw materials, and adopts fluidized bed gasification furnace for continuous gasification as gasification equipment, that is, continuous gasification method or air and CO ₂ As a gasification agent, 0-10mm coke powder, anthracite, lean coal, long-flame coal, and lignite are used as raw materials, and a fluidized bed gasifier with intermittent gasification work is used as gasification equipment, that is, intermittent gasification method, to make CO ₂ The gas is reduced to CO gas to produce high-purity CO gas, which is used as a raw material for organic synthesis. Its advantage is that the source of raw materials is abundant, and recycling _CO2 as a gasification agent can not only generate economic benefits, but also improve the environmental conditions. The fluidized bed gasifier is used as the gasification equipment, and the reaction speed is fast, and it is easy to reach the equilibrium composition. Obtain high-component CO gas.

Description

A gasification process method and device for a fluidized bed CO gasifier

Technical field

The invention relates to a new coal gasification process in the field of coal chemical industry, in particular to a gasification process method and a device for a fluidized bed CO gasifier.

Background technique

CO is the main raw material for organic synthesis of one-carbon chemistry. It reacts with water, methanol, ammonia, etc. to produce organic chemicals such as formic acid, formamide, and acetic acid. At present, domestic production of CO gas mostly uses fixed-bed gasifiers to produce water gas or air gas, and then separates high-purity CO gas from water gas or air gas. There are enterprises in our country that use CO and methanol process to produce acetic acid, use _CO2 and _O2 as gasification agents, and use fixed bed gasification furnace to produce CO gas. Because this process uses casting coke as raw material, the raw material price is high. Due to the fixed bed The temperature of the gasifier decreases gradually along the height of the furnace, and the temperature at the furnace outlet is about 600°C. If the reaction is a reversible reaction, the equilibrium composition of CO will decrease at the outlet temperature of the furnace, so it is difficult for the fixed-bed gasifier to obtain high-content CO raw material gas.

Contents of the invention

The object of the present invention is to address the defects of the prior art and propose a gasification process and device for a fluidized bed CO gasifier using O ₂ +CO ₂ or air + CO ₂ as the gasification agent.

The technical solution to achieve the above purpose is to use a fluidized bed gasifier as the main equipment, use oxygen-containing gas and _CO2 as the gasification agent, and use powdered coke or pulverized coal as raw materials to gasify carbon through the fluidized bed gasifier. Chemical reaction, using continuous gasification method or batch gasification method, reducing _CO2 gas to CO gas, producing high-purity CO gas, which can be used as a raw material for organic synthesis.

The continuous gasification method uses _O2 and _CO2 as gasification agents, 0-10mm coke powder and anthracite as raw materials, and adopts a fluidized bed gasifier for continuous gasification work as gasification equipment, and according to the raw material coal The ash melting point of the fluidized bed gasifier determines the working temperature of the fluidized bed gasifier, which is 150°C to 250°C lower than the ash melting point, and the fluidization velocity of the fluidized bed gasifier is 0.8m to 1.2m/s. The cyclone separator removes dust, and the separated carbon-containing dust is returned to the furnace through the feeding pipe and the _feeder to participate in the reaction again. After entering the gas purification system, further washing and dust removal, it is sent to the gas cabinet for processing.

The intermittent gasification method uses air and _CO as gasification agents, 0-10mm coke powder, anthracite, lean coal, long-flame coal, and lignite as raw materials, and adopts a fluidized bed gasifier for intermittent gasification. Gasification equipment, producing CO gas; the whole gas production process is divided into two stages: air combustion and _CO2 gasification, the time distribution between the combustion stage and the gasification stage is about 4:6, the two stages cycle alternately, and the fluidized bed gas The maximum working temperature of the gasifier is 150°C to 250°C lower than the ash melting point of raw coal, the general conversion temperature range is 50°C→100°C, and the fluidization velocity of the fluidized bed gasifier is 0.8 to 1.2m/s.

In the air supply combustion stage, air is supplied to the gasifier to make the coal in the furnace burn in a fluidized state, and the bed temperature rises rapidly. When the bed temperature rises to the predetermined maximum working temperature, the air supply is stopped; The gasification furnace is transferred to the gasification stage of supplying CO ₂ gas, and CO ₂ gas is supplied to the gasification furnace, so that the high-temperature material layer in the furnace undergoes a Boudual reaction in a fluidized state to generate CO gas. Since the reaction is a strong endothermic reaction, the bed temperature drops rapidly. When the bed temperature drops to a predetermined temperature (depending on the activity of the raw coal, generally greater than 950°C), the supply of _CO2 gas is stopped.

When coal with high moisture and volatile content is used as raw material, coal is added during the combustion stage, so that the coal can remove moisture and volatile content during the combustion stage and become coke.

The device for implementing the continuous gasification method includes a circulating fluidized bed gasifier (1), a cyclone separator (2), a feeding pipe (4), a feeder (5), a tubular heat exchanger (3), a CO Purification system (10), wherein the upper part of the fluidized bed gasification furnace (1) is cylindrical, the lower part is inverted conical, the furnace body is a steel plate structure with refractory lining, and the lower part of the furnace body is sequentially provided with air chamber (7), exhaust The slag valve and the coal bin (8) are connected to the gasifier (1) through the spiral coal stoker (9); the upper part of the furnace body is equipped with a cyclone separator (2) at the outlet of the furnace, and the lower end of the cyclone separator (2) is sequentially connected to the lower The material pipe (4), the feeder (5), is connected to the fluidized bed gasifier (1) through the feeder (5), and the top outlet of the cyclone separator (2) is connected to the tubular heat exchanger (3) The flue gas outlet at the lower end is connected with the CO purification system (10), and the heat exchange gas outlet is connected with the Venturi mixer (6).

The device for implementing the batch gasification method includes a batch fluidized bed gasifier (1), a cyclone separator (2), a feeding pipe (4), a feeder (5), a tubular heat exchanger (3), CO purification system (10) and flue gas purification system (13), wherein the upper part of the fluidized bed gasification furnace (1) is cylindrical, the lower part is inverted conical, the furnace body is a steel plate structure with refractory lining, and the lower part of the furnace body is sequentially An air chamber (7) and a slag discharge valve are provided, and the coal bunker (8) is connected to the gasifier (1) through a spiral stoker (9); the upper part of the furnace body is equipped with a cyclone separator (2) sequentially on the outlet of the furnace, The lower end of the cyclone separator (2) is sequentially connected with the feeding pipe (4) and the feeder (5), and connected with the fluidized bed gasification furnace (1) through the feeder (5), and the top of the cyclone separator (2) The outlet is connected to the tubular heat exchanger (3), and the upper end of the tubular heat exchanger (3) is provided with a gas inlet respectively connected to the _CO2 reversing valve (11-1) and the air reversing valve (11-2) , the outlet at the lower end is connected to the CO purification system (10) and the flue gas purification system (13) respectively via the CO reversing valve (12-1) and the flue gas reversing valve (12-2), and the lower end is also provided with an air chamber ( 7) The air inlet connected to the heat exchange gas outlet.

The present invention has the following advantages compared with the existing method using a fixed-bed CO gasifier:

(1) Abundant sources of raw materials. Fluidized bed continuous gasification can use 0-10mm coke powder and anthracite coal powder; while fluidized bed intermittent gasification can not only use 0-10mm coke powder and anthracite powder, but also 0-10mm lean coal , sub-bituminous coal and long-flame coal, etc.

(2) CO ₂ is used as a gasification agent. Since CO ₂ is a greenhouse gas, its recycling can not only generate economic benefits, but also improve the environment.

(3) Since the fluidized bed gasifier fully contacts and reacts with CO ₂ under the condition of fluidization, at the same temperature, the reaction speed is fast and it is easy to reach the equilibrium composition. Due to the uniform temperature of the material layer in the furnace, it is easy to achieve high-component CO gas.

Description of drawings

Figure 1 is a flow chart of the continuous gasification process of the present invention.

Fig. 2 is a flow chart of the fluidized bed batch gasification process of the present invention.

1 Fluidized bed gasifier 2 Cyclone separator 3 Tube heat exchanger 4 Feed pipe 5 Return feeder 6 Venturi mixer 7 Air chamber 8 Coal bunker 9 Spiral coal stoker 10 CO purification system 11-1 CO ₂ Reversing valve 11-2 Air reversing valve 12-1 CO reversing valve 12-2 Flue gas reversing valve 13 Flue gas purification system

Detailed ways

1. Fluidized bed continuous gasification method

As shown in Figure 1, this process uses pure oxygen (≥98%) mixed with _CO2 gas as a gasification agent, and coke powder with a thickness of 0-10mm is used as a raw material to be sent to the gasifier (1) through a spiral stoker (9). Inside, the CO ₂ gas is heated to 600°C by the tubular heat exchanger (3), then mixed with oxygen in proportion by the Venturi mixer (6), and then enters the gasifier (1) from the air chamber (7), so that The carbon layer in the furnace undergoes a redox reaction with _O2 and _CO2 at high temperature in a fluidized state to generate CO gas. Since this reaction is an exothermic and endothermic reaction, the bed temperature should drop. When the two reactions are in thermal equilibrium , the bed temperature is in a steady state. The temperature depends on the ash melting point of coal char, and generally does not exceed 1150°C. The generated high-temperature CO gas is passed through the cyclone separator (2) from the outlet of the gasifier (1), and the separated carbon-containing dust is returned to the gasifier (1) through the feeding pipe (4) and the feeder (5) Re-engage the response. The CO gas after dedusting enters the tubular heat exchanger (3) to exchange heat with the _CO2 feed gas entering the system. The crude CO gas passed through the tubular heat exchanger (3) is sent to the purification system (10) and then sent to the gas cabinet for processing after further washing, dedusting and cooling.

2. Fluidized bed batch gasification method

As shown in Figure 2, the process uses air and _CO2 as gasification agents. The fluidized bed gasification furnace adopts the intermittent working method, that is, the whole gas production process is divided into two stages: the air supply combustion stage, supplying air to the gasification furnace to make the coal in the furnace burn in a fluidized state, and the bed layer The temperature rises rapidly. When the bed temperature rises to the predetermined temperature (depending on the ash melting point of the raw coal, generally 150°C-250°C lower than the ash melting point), the air supply is stopped; the gasifier is switched to _CO2 gas supply. In the gasification stage, CO ₂ gas is supplied to the gasification furnace, so that the high-temperature material layer in the furnace undergoes a Boudouard reaction in a fluidized state to generate CO gas. Since the reaction is a strong endothermic reaction, the bed temperature drops rapidly. When the bed temperature drops to a predetermined temperature (depending on the activity of the raw coal, generally greater than 950°C), the supply of _CO2 gas is stopped. The gasification furnace is transferred to the air supply combustion stage. These two stages reciprocate alternately to produce CO gas. Because the whole process is carried out in a fluidized state, the temperature of the mixed bed is also very uniform, and the reaction is very rapid. No other stages of fixed bed gasifier are required, the operation is simple and easy to automate.

The specific implementation steps are that the raw coal of 0-10 mm is fed into the furnace from the coal bunker (8) by the spiral coal stoker (9). In the air supply combustion stage. The air from the Roots blower passes through the air reversing valve 11-2 and the tube heat exchanger (3) successively. After the air is heated to 600°C, it enters the gasifier (1) through the air chamber (7), so that The material bed in the furnace burns in a fluidized state, and the bed temperature rises rapidly. When the bed temperature rises to 1100°C, the air supply is stopped, and the gasifier enters the CO ₂ gasification stage. At this time, the air reversing valve 11-2 is closed, the flue gas reversing valve 12-2 is closed, the _CO2 reversing valve 11-1 and the CO reversing valve 12-1 are opened, and _CO2 is supplied to the gasifier (1) The gas passes through the CO ₂ reversing valve 11-1 in turn, the tubular heat exchanger (3), and the CO ₂ is heated to 600°C and enters the gasifier (1) through the air chamber (7), where it flows with the high-temperature material layer. The Boudouard reaction is carried out in the reduced state to generate CO gas. The bed temperature began to drop, and when the temperature dropped to 950°C, the supply of CO ₂ gas was stopped. The gasification furnace is transferred to the stage of supplying air for combustion. The high-temperature flue gas generated during the combustion stage enters the cyclone separator (2) from the furnace outlet, and the separated carbon-containing dust passes through the feeding pipe (4) and the return device (5), and returns to the gasifier (1) for re-combustion . The high-temperature flue gas from the initial dedusting passes through the tubular heat exchanger (3), heat exchange and cools down to below 500°C, and enters the flue gas purification system (13) through the flue gas heat exchange valve 12-2. Further cooling and dust reduction, after the dust reaches the emission standard, it is discharged into the atmosphere. The CO gas produced in the gasification stage enters the cyclone separator (2) from the furnace outlet, and the separated carbon-containing dust passes through the feeding pipe (4) and the return device (5), and returns to the furnace for re-gasification. The initially dedusted CO gas is cooled to below 500°C through the tubular heat exchanger (3), and enters the CO purification system (10) through the CO gas reversing valve 12-1 for cooling and dedusting. The transition between the combustion stage for air and the gasification stage for carbon dioxide is automatically carried out according to the set temperature.

One cycle of the gas production process is 4 to 5 minutes, the air supply combustion stage is 40% of the cycle time, and the _CO2 gas production stage is about 60% of the cycle time. The fluidized bed batch gasification method does not require oxygen production equipment, has small investment and low operating costs, and is suitable for small and medium gas source projects. The fluidized bed batch gasification method has a wide range of raw material sources and is applicable to almost all types of coal. Especially sub-bituminous coal, long-flame coal and other young coals with high volatility. These coal ash have low melting point, good activity, high volatile matter and moisture content. When used in continuous gasification, the content of _H2 and carbon nitrogen compounds in the product gas is high. It will cause difficulties for the purification of CO in the future. In the intermittent gasification, coal is added in the air supply combustion stage, and the moisture and volatile matter of the incoming coal are quickly dried and dry-distilled and burned in the combustion stage; in the CO ₂ gasification stage, the raw coal has become coke. Therefore, the moisture and volatile matter in the coal no longer affect the product gas, which is also a major advantage of this gasification method.

Claims (6)

1. A gasification process of a fluidized bed CO gasifier, characterized in that the fluidized bed gasifier is used as the main equipment, with oxygen-containing gas and _CO as the gasification agent, and with pulverized coke or pulverized coal as raw materials , the carbon gasification reaction is carried out through the fluidized bed gasification furnace, and the continuous gasification method or the intermittent gasification method is used to reduce _CO2 gas to CO gas to produce high-purity CO gas, which is used as a raw material for organic synthesis. 2. The gasification process of a fluidized bed CO gasifier according to claim 1, characterized in that the continuous gasification method uses _O2 and _CO2 as gasification agents, 0 ~ 10mm coke powder, Anthracite is used as the raw material, and a fluidized bed gasifier with continuous gasification work is used as the gasification equipment. The working temperature of the fluidized bed gasifier is determined according to the ash melting point of the raw coal, which is 150 to 250 □ lower than the ash melting point. The fluidization velocity of the fluidized bed gasification furnace is 0.8m~1.2m/s. The generated CO gas is dedusted by the high-temperature cyclone separator, and the separated carbon-containing dust is returned to the furnace through the feeding pipe and the return device. Participating in the reaction, the initially dedusted CO gas is exchanged with the CO ₂ gas entering the furnace through a tubular heat exchanger, and then enters the gas purification system for further washing and dedusting before being sent to the gas cabinet for processing. 3. The gasification process of a fluidized bed CO gasifier according to claim 1, characterized in that the intermittent gasification method uses air and _CO as gasification agents, 0 ~ 10mm coke powder, anthracite , lean coal, long-flame coal, and lignite as raw materials, using intermittent gasification fluidized bed gasifier as gasification equipment to produce CO gas; the whole gas production process is divided into two stages: air combustion and _CO2 gasification , the time distribution between the combustion stage and the gasification stage is about 4□6, the maximum working temperature of the fluidized bed gasifier is 150□~250□ lower than the ash melting point of raw coal, and the general conversion temperature range is 50□→100□ , the fluidization velocity of the fluidized bed gasifier is 0.8 ~ 1.2m/s; in the air supply combustion stage, air is supplied to the gasifier to make the coal in the furnace burn in a fluidized state, and the bed temperature rises rapidly , when the bed temperature rises to the predetermined maximum working temperature, the air supply is stopped; the gasification furnace is transferred to the gasification stage of supplying CO ₂ gas, and CO ₂ gas is supplied to the gasification furnace to make the high-temperature material layer in the furnace flow Boudouard reaction is carried out in the state of oxidization to generate CO gas. When the bed temperature drops to a predetermined temperature (depending on the activity of the raw coal, generally greater than 950 ° C), the supply of CO ₂ gas is stopped, and it enters the air supply combustion stage. The transition between the two stages takes place automatically according to the set temperature. 4. The gasification process of a fluidized bed CO gasifier according to claim 3, characterized in that when coal with high moisture and volatile content is used as raw material, coal is added in the combustion stage to make the coal burn Remove moisture and volatile matter in stages and become coke. 5. realize the device of the gasification process of a kind of fluidized bed CO gasifier described in claim 2, it is characterized in that device comprises circulating fluidized bed gasifier (1), cyclone separator (2), blanking Tube (4), feeder (5), tubular heat exchanger (3), CO purification system (10), wherein the upper part of the fluidized bed gasification furnace (1) is cylindrical, and the lower part is inverted cone, The furnace body is a steel plate structure with refractory lining. The lower part of the furnace body is equipped with an air chamber (7) and a slag discharge valve in sequence. The coal bunker (8) is connected to the gasifier (1) through a spiral stoker (9); the upper part of the furnace body A cyclone separator (2) is installed in sequence on the furnace outlet, and the lower end of the cyclone separator (2) is connected to the feeding pipe (4) and the feeder (5) in sequence, and the feeder (5) is connected to the fluidized bed gasifier (1) connected, the top outlet of the cyclone separator (2) is connected with the tubular heat exchanger (3), the lower outlet is connected with the CO purification system (10), and the heat exchange gas outlet is connected with the Venturi mixer (6) . 6. Realize the device of the gasification process of a kind of fluidized bed CO gasifier described in claim 3, it is characterized in that device comprises intermittent fluidized bed gasifier (1), cyclone separator (2), lower Material pipe (4), feeder (5), tubular heat exchanger (3), CO purification system (10), flue gas purification system (13), wherein the upper part of the fluidized bed gasifier (1) is a garden Cylindrical, the lower part is inverted conical, and the furnace body is a refractory-lined steel plate structure. The lower part of the furnace body is equipped with an air chamber (7) and a slag discharge valve in sequence. The furnace (1) is connected; the upper furnace outlet of the furnace body is provided with a cyclone separator (2), and the lower end of the cyclone separator (2) is sequentially connected with the feeding pipe (4), the feeder (5), ) is connected with the fluidized bed gasifier (1), the top outlet of the cyclone separator (2) is connected with the tubular heat exchanger (3), and the upper end of the tubular heat exchanger (3) is equipped with a _CO2 reversing The gas inlet connected to the valve (11-1) and the air reversing valve (11-2) respectively, and the outlet at the lower end is respectively connected to the CO purification system through the CO reversing valve (12-1) and the flue gas reversing valve (12-2). (10) The flue gas purification system (13) is connected, and the lower end is provided with a heat exchange gas outlet connected to the air inlet of the air chamber (7).

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