CN103113919A - Biomass pyrolysis system of three-stage reactor and working method thereof - Google Patents

Abstract

The invention belongs to the technical field of novel biomass pyrolysis systems, in particular to a three-reactor biomass pyrolysis system and its working method. The system of the present invention consists of a fast fluidized bed oxidation furnace, a first cyclone separator, a flue gas pipeline, a first return valve, a bubbling fluidized bed calciner, a second return valve, a second cyclone separator, and a _CO2 pipe road, the third return valve, rotary pyrolysis furnace, feeding port, gas outlet and heat auger; the present invention adopts rapid fluidized bed oxidation furnace, bubbling fluidized bed calciner and rotary pyrolysis furnace The design structure of three reactors, the working condition parameters such as the reaction temperature of each reactor are both independent and interrelated, and its main influencing factors are the material selection and proportioning relationship of the double chemical chain; the CO of the present invention changes from _zero discharge to negative Emissions; the _H2 component content in the gas is greater than 80%, which reduces the heat loss of biomass energy and prevents the environmental pollution caused by semi-coke.

Description

A three-reactor biomass pyrolysis system and its working method

technical field

The invention belongs to the technical field of novel biomass pyrolysis systems, in particular to a three-reactor biomass pyrolysis system and its working method.

Background technique

In the context of the depletion of fossil energy in various countries in the world today, biomass energy, as a safe, reliable, abundant, environmentally friendly and renewable form of energy, has attracted more and more attention from researchers in various countries. In recent years, my country's biomass energy utilization technology has developed rapidly. By the end of 2010, the total installed capacity of biomass power generation in my country had exceeded 2000 MW.

Biomass gasification and pyrolysis have been widely promoted and applied as technical means for large-scale utilization of biomass energy in industrial production. However, the current conversion of solid biomass into gaseous fuels has the following problems:

(1) The gas produced by biomass gasification is mixed with a large amount of impurity gases such as N ₂ , CO ₂ and water vapor, resulting in a low calorific value of the gas.

(2) A large amount of semi-coke is produced in the process of biomass pyrolysis, which is directly discharged into the environment along with the slag. This practice not only causes energy loss, but also pollutes the environment.

(3) Usually, there is no decarbonization link in the biomass conversion process, and a large amount of CO ₂ is directly emitted into the atmosphere without any treatment, causing more and more serious greenhouse effects, which is not in line with today's low-carbon production operations.

Contents of the invention

Aiming at the deficiencies of the prior art, the invention provides a three-reactor biomass pyrolysis system and its working method.

A three-reactor biomass pyrolysis system, the upper outlet of the fast fluidized bed oxidation furnace is connected to the first cyclone separator; the top of the first cyclone separator is provided with a flue gas pipeline, and the bottom outlet passes through the first return material The valve is connected to the upper inlet of the bubbling fluidized bed calcination furnace; the lower outlet of the bubbling fluidized bed calcination furnace is connected to the lower part of the rapid fluidized bed oxidation furnace through the second return valve; the bubbling fluidized bed calcination furnace The top outlet of the second cyclone separator is connected with the second cyclone separator; the top of the second cyclone separator is connected with the _CO capture device through the CO pipeline, and the bottom outlet is connected with the _rotary pyrolysis furnace through the third return valve; The top of the rotary pyrolysis furnace is provided with a feed port and a gas outlet, and the lower outlet is connected to the inlet of the heat auger; the outlet of the heat auger is connected to the lower part of the bubbling fluidized bed calciner.

A working method of a three-reactor biomass pyrolysis system, the specific scheme of which is as follows:

Water vapor enters the system from the second return valve, the first return valve, the bubbling fluidized bed calciner and the third return valve; air enters the system through the bottom of the fast fluidized bed oxidation furnace;

Biomass materials enter the rotary pyrolysis furnace through the feed port, and after gasification and pyrolysis reaction with air, the primary gas production containing semi-coke carbon particles and CO ₂ and CaO from the third return valve Carry out the reaction to generate gas for industrial production. The CaCO ₃ and semi-coke particles produced by the reaction enter the bubbling fluidized bed calciner through the heat auger for high-temperature calcination, decomposition and reduction of CuO. The semi-coke particles are mixed with water The steam reacts, and the generated H2 _and CO together with unreacted semi-coke particles undergo redox reaction with CuO from the first return valve and from the fast fluidized bed oxidation furnace, and release heat to decompose _CaCO3 ; The CaO and _CO2 produced by the calcination _and decomposition of _CaCO3 in the bubbling fluidized bed calciner enter the second cyclone separator in a fluidized state. The valve enters the rotary pyrolysis furnace, and CO ₂ enters the CO ₂ capture device through the CO ₂ pipeline, thus completing the cycle of one of the chains in the double chemical chain reaction;

Another chemical chain circulation process is: the air from the fan enters from the bottom of the fast fluidized bed oxidation furnace together with Cu, and undergoes a rapid oxidation reaction, and the generated CuO enters the first cyclone with the hot exhaust gas in a fluidized state. In the separator, CuO enters the bubbling fluidized bed calciner through the first return valve by gravity to participate in the redox reaction.

The beneficial effects of the present invention are:

(1) At the same time of industrial production, attention was paid to the capture and control of high-concentration CO ₂ produced by the system, CO ₂ was changed from zero emission to negative emission, and the concentration of CO ₂ at the outlet of the incinerator was greater than 85%;

(2) Through biomass pyrolysis and gas decarbonization, the _H2 component content in the gas is greater than 80%; the unit calorific value of the gas has been greatly improved, and it has higher utilization value;

(3) The semi-coke produced by biomass pyrolysis is gasified in the calcination reactor, which reduces the heat loss of biomass energy and prevents the environmental pollution caused by semi-coke.

Description of drawings

Fig. 1 is the structural representation of system device of the present invention;

Labels in the figure: 1-fast fluidized bed oxidation furnace; 2-the first cyclone separator; 3-flue gas pipeline; 4-the first return valve; Material valve; 7-second cyclone separator; 8-CO ₂ pipeline; 9-third material return valve; 10-rotary pyrolysis furnace; 11-feeding port; 12-gas outlet; 13-heat auger .

Detailed ways

The present invention provides a three-reactor biomass pyrolysis system and its working method. The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

A three-reactor biomass pyrolysis system, the upper outlet of the fast fluidized bed oxidation furnace 1 is connected to the first cyclone separator 2; the top of the first cyclone separator 2 is provided with a flue gas pipeline 3, and the bottom outlet passes through The first return valve 4 is connected with the upper inlet of the bubbling fluidized bed calcination furnace 5; The top outlet of the bubbling fluidized bed calciner 5 is connected with the second cyclone separator 7; the top of the second cyclone separator 7 is connected with the CO _capture device through the _CO pipeline 8, and the bottom outlet is connected through the second cyclone separator 7. The three-return valve 9 is connected to the rotary pyrolysis furnace 10; the top of the rotary pyrolysis furnace 10 is provided with a feed port 11 and a gas outlet 12, and the lower outlet is connected to the inlet end of the heat auger 13; the outlet end of the heat auger 13 It is connected with the lower part of the bubbling fluidized bed calciner 5.

A working method of a three-reactor biomass pyrolysis system, the specific scheme of which is as follows:

Water vapor enters the system from the second return valve 6, the first return valve 4, the bubbling fluidized bed calciner 5 and the third return valve 9; air enters the system through the bottom of the fast fluidized bed oxidation furnace 1 ;

The biomass material enters the rotary pyrolysis furnace 10 through the feed port 11, and after gasification and pyrolysis reaction with air, the primary gas produced containing semi-coke carbon particles and CO ₂ and the gas from the third return valve 9 CaO reacts to generate gas for industrial production, and the _CaCO3 and semi-coke particles produced by the reaction enter the bubbling fluidized bed calciner 5 through the heat auger 13 for high-temperature calcination, decomposition and reduction of CuO. Coke particles react with water vapor, and the produced H ₂ , CO, together with unreacted semi-coke particles, undergo redox reactions with CuO from the first return valve 4 and from the fast fluidized bed oxidation furnace 1, and Exothermic decomposes _CaCO3 ; CaO and CO2 produced by the calcination and decomposition of _CaCO3 in the bubbling fluidized bed calciner 5 enter the second cyclone separator ₇ in a fluidized state, and CaO is separated from _CO2 gas-solid under the action of gravity Open, CaO enters the rotary pyrolysis furnace 10 through the third return valve 9, _CO2 enters the _CO2 capture device through the _CO2 pipeline 8, so far the cycle of one of the chains in the double chemical chain reaction is completed ;

Another chemical chain circulation process is: the air from the fan enters from the bottom of the fast fluidized bed oxidation furnace 1 together with Cu, and undergoes a rapid oxidation reaction, and the generated CuO enters the first furnace with hot waste gas in a fluidized state. In the cyclone separator 2, CuO enters the bubbling fluidized bed calciner 5 through the first return valve 4 by gravity to participate in the redox reaction.

A double chemical chain reaction is adopted, and the specific reaction conditions are as follows:

1. Rotary pyrolysis furnace

[C _x H _y O _z ]→tar1+char1→

tar2[CH _0.85 O _0.17 ]+char2[CH _0.20 O _0.13 ]

+H ₂ +CO+CO ₂ +CH ₄ +C ₂ H ₄ + (1)

This reaction is that the biomass material with C _x H _y O _z as the main component undergoes a pyrolysis reaction in a rotary pyrolysis furnace to generate a preliminary cracked gas composed of various gas components, which contains a large amount of CO ₂ , resulting in Due to the instability of combustion, it is not suitable for direct combustion applications. The reaction is endothermic, +1000 kJ/kg.

                   （2）

(2)

This reaction is to add CaO to the biomass material to absorb the CO ₂ produced by cracking. It is believed that the reaction is easier to carry out when moisture is involved, so an appropriate amount of water vapor is introduced into the fourth return valve. The reaction is endothermic (the temperature should not be too high), +175.7 kJ/mol.

The reaction temperature in the furnace is controlled at about 650 °C, and the required reaction heat in the gasifier comes from the physical sensible heat of CaO.

2. Bubbling fluidized bed calciner

(3)

The carbon particles (semi-coke) that have not been fully reacted in the rotary pyrolysis furnace enter the high-temperature bubbling fluidized bed calciner to react with the added water vapor, and the generated CO and _H2 are mainly used to reduce CuO. Not intended for combustion applications as gas. The reaction absorbs a large amount of heat, +131.5 kJ/mol.

2CuO+C→2Cu+CO ₂ (4)

CuO+H ₂ →Cu+H ₂ O (5)

CuO+CO→Cu+CO ₂ (6)

High temperature CuO from a fast fluidized bed oxidation furnace undergoes redox reactions with three typical reducing agents C, H ₂ and CO. All three reactions are exothermic, although heating is required to proceed. The reaction temperature is about 800 °C.

(7)

In the bubbling fluidized bed calciner in a fluidized state, the CaO produced _by the thermal decomposition of CaCO ₃ enters the cyclone separator along with the CO ₂ , and the CaO solid material is separated and enters the rotary pyrolysis furnace. Gas is collected. The reaction is endothermic, and the reaction temperature is about 800 °C.

3. Rapid fluidized bed oxidation furnace

2Cu+O ₂ →2CuO (8)

The chemical chain reaction carried out in the fast fluidized bed oxidation furnace mainly provides oxide material CuO for this double chemical chain reaction process, as an intermediate medium to complete the whole system process. This reaction is a rapid oxidation reaction, which releases a lot of heat, and the temperature is about 850 °C.

Claims (2)

1. A three-reactor biomass pyrolysis system, characterized in that: the upper outlet of the fast fluidized bed oxidation furnace (1) is connected to the first cyclone separator (2); the first cyclone separator (2) A flue gas pipeline (3) is arranged at the top of the top, and the bottom outlet is connected with the upper inlet of the bubbling fluidized bed calciner (5) through the first return valve (4); the bubbling fluidized bed calciner (5) The lower outlet is connected to the lower part of the fast fluidized bed oxidation furnace (1) through the second return valve (6); the top outlet of the bubbling fluidized bed calciner (5) is connected to the second cyclone separator (7); The top of the second cyclone separator (7) is connected to the _{CO capture} device through the CO pipeline (8), and the bottom outlet is connected to the rotary pyrolysis furnace (10) through the third return valve (9); The top of the rotary pyrolysis furnace (10) is provided with a feeding port (11) and a gas outlet (12), and the lower outlet is connected to the inlet end of the heat auger (13); the outlet end of the heat auger (13) is connected to the bubbling fluidizer The lower part of the bed calciner (5) is connected. 2. A working method of a three-reactor biomass pyrolysis system as claimed in claim 1, wherein the specific scheme is as follows: Water vapor enters the system from the second return valve (6), the first return valve (4), the bubbling fluidized bed calciner (5) and the third return valve (9); the air passes through the fast fluidized bed The bottom of the oxidation furnace (1) enters the system; The biomass material enters the rotary pyrolysis furnace (10) through the feeding port (11), and after gasification and pyrolysis reaction with air, the primary gas produced containing semi-coke carbon particles and CO ₂ is combined with the gas from the second The CaO in the three-return valve (9) reacts to generate gas for industrial production, and the CaCO ₃ and semi-coke particles produced by the reaction enter the bubbling fluidized bed calciner (5) through the heat auger (13) High-temperature calcination decomposes and reduces CuO, in which the semi-coke particles react with water vapor, and the generated H ₂ and CO together with unreacted semi-coke particles are mixed with the first return valve (4) and the rapid fluidization The CuO in the bed oxidation furnace (1) undergoes a redox reaction, and releases heat to decompose CaCO ₃ ; the CaO and CO ₂ produced by the calcination and decomposition of CaCO ₃ in the bubbling fluidized bed calcination furnace (5) enter the second stage in a fluidized state. Cyclone separator (7), under the action of gravity, CaO and CO ₂ gas-solid separation, CaO enters the rotary pyrolysis furnace (10) through the third return valve (9), CO ₂ passes through the CO ₂ pipeline ( 8) Enter the CO ₂ capture device, and complete the cycle of one of the chains in the double chemical chain reaction; Another chemical chain circulation process is: the air from the fan enters from the bottom of the fast fluidized bed oxidation furnace (1) together with Cu, and undergoes a rapid oxidation reaction, and the generated CuO enters with the hot exhaust gas in a fluidized state. In the first cyclone separator (2), CuO enters the bubbling fluidized bed calciner (5) through the first return valve (4) by gravity to participate in the redox reaction.

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