Entrained-flow gasifier and gasification method using the same for synthesizing syngas from biomass fuel

Patent metadata

Field	Value
Publication number	US-9873841-B2
Application number	US-201615344569-A
Country	US
Kind code	B2
Filing date	Nov 6, 2016
Priority date	Dec 29, 2011
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

A method for gasifying biomass using a gasifier, the gasifier including a furnace body and a fuel pretreatment system. The method includes 1) crushing and sieving a biomass fuel to yield particle size-qualified fuel particles, 2) exciting working gas to yield plasma, and spraying the plasma into the gasifier, 3) spraying the particle size-qualified fuel particles into the gasifier via nozzles, synchronously spraying an oxidizer via an oxygen/vapor inlet into the gasifier, and 4) monitoring the temperature and components of the syngas, regulating an oxygen flow rate, a vapor flow rate, and microwave power to maintain the process parameters within a preset range and to control a temperature of the syngas to be between 900 and 1200° C., collecting the syngas from the syngas outlet at the top of the furnace body, and discharging liquid slag from the slag outlet.

First claim

The invention claimed is:

1. A method for gasifying biomass using a gasifier, the gasifier comprising
a furnace body comprising a fuel inlet, a syngas outlet and a slag outlet, the fuel inlet comprising nozzles; and
a fuel pretreatment system comprising a feeding hopper;
wherein:
the furnace body is vertically disposed;
the fuel inlet is disposed at a lower part of the furnace body;
the syngas outlet is disposed at a top of the furnace body;
the slag outlet is disposed at a bottom of the furnace body;
the fuel pretreatment system is disposed outside of the furnace body;
a bottom of the feeding hopper is connected to the furnace body via the nozzles;
the nozzles are disposed radially along the furnace body; and
one or two layers of microwave plasma generators are disposed in parallel at a gasification zone of the furnace body and each layer of the microwave plasma generators comprises working gas inlets;
the method comprising:
1) crushing and sieving a biomass fuel using the fuel pretreatment system to yield particle size-qualified fuel particles, and transporting the particle size-qualified fuel particles to the feeding hopper;
2) introducing working gas from the working gas inlets into the microwave plasma generator, exciting the working gas to yield high temperature, high degree of ionization, and high activity of plasma, and spraying the plasma to into the gasifier;
3) spraying the particle size-qualified fuel particles into the gasifier via the nozzles, synchronously spraying an oxidizer via an oxygen/vapor inlet into the gasifier, so that a thermal-chemical reaction between the fuel particles and the oxidizer in the presence of high activity of plasma proceeds to yield syngas comprising carbon monoxide and hydrogen; and
4) monitoring the temperature and components of the syngas, regulating oxygen flow rate, vapor flow rate, and microwave power to maintain the process parameters within a preset range, collecting the syngas having a temperature of between 900 and 1200° C. from the syngas outlet at the top of the furnace body, and discharging liquid slags from the slag outlet.

2. The method of claim 1 , wherein
the fuel pretreatment system further comprises a fuel crushing apparatus, a sieving apparatus, a first fuel container for receiving the particle size-qualified fuel particles, and a second fuel container for receiving particle size-unqualified fuel particles;
a number of nozzles is between 2 and 4;
a number of working gas inlets is between 2 and 4;
the sieving apparatus is disposed downstream to the fuel crushing apparatus;
the feeding hopper is disposed downstream to the first fuel container;
the first fuel container and the second fuel container are disposed side-by-side downstream to the sieving apparatus; and
a monitoring unit is disposed close to the syngas outlet at the top of the furnace body.

3. The method of claim 1 , wherein the fuel pretreatment system further comprises a fuel crushing apparatus, a sieving apparatus disposed downstream to the fuel crushing apparatus, a first fuel container for receiving the particle size-qualified fuel particles, and a second fuel container for receiving particle size-unqualified fuel particles; the first fuel container and the second fuel container are disposed side-by-side downstream to the sieving apparatus; and in step 1), the particle size-qualified fuel particles are received by the first fuel container, the particle size-unqualified fuel particles are first received by the second fuel container and then returned to the fuel pretreatment system for crushing again until meeting the particle size requirement; the particle size-qualified fuel particles are transported from the first container to the feeding hopper; and the particle size of the fuel particles is less than 5 mm.

4. The method of claim 1 , wherein in step 2), the start-up of the microwave plasma generators is between 2 and 3 seconds earlier than the start-up of the nozzles of the gasifier; the working gas comprises an auxiliary oxidizer, and is introduced into the microwave plasma generators via the working gas inlets to be excited to yield high temperature, high degree of ionization, and high activity of plasma.

5. The method of claim 3 , wherein in step 2), the start-up of the microwave plasma generators is between 2 and 3 seconds earlier than the start-up of the nozzles of the gasifier; the working gas comprises an auxiliary oxidizer, and is introduced into the microwave plasma generators via the working gas inlets to be excited to yield high temperature, high degree of ionization, and high activity of plasma.

6. The method of claim 4 , wherein in step 3), the particle size-qualified fuel particles are carried by carrier gas and sprayed into the gasifier via the nozzles; the oxidizers are synchronously sprayed into the gasifier via the oxygen/vapor inlet, so that a partial oxidation-reduction reaction and gasification reaction between the fuel particles and the oxidizer proceed to yield syngas comprising a large amount of carbon monoxide and hydrogen and a small amount of CO 2 , CH 4 , H 2 S, and COS; the syngas flows upward to the gasification zone of the microwave plasma generators, and mixes with the horizontally/tangentially sprayed plasma gas for thermo-chemical gasification reaction at between 1200 and 1800° C., a central zone temperature is between 1800 and 2000° C., a retention time of the syngas in the gasification zone is between 1 and 10 seconds, and the power of the microwave plasma generators is controlled to drive the reaction to proceed completely.

7. The method of claim 5 , wherein in step 3), the particle size-qualified fuel particles are carried by carrier gas and sprayed into the gasifier via the nozzles; the oxidizers are synchronously sprayed into the gasifier via the oxygen/vapor inlet, so that a partial oxidation-reduction reaction and gasification reaction between the fuel particles and the oxidizer proceed to yield syngas comprising a large amount of carbon monoxide and hydrogen and a small amount of CO 2 , CH 4 , H 2 S, and COS; the syngas flows upward to the gasification zone of the microwave plasma generators, and mixes with the horizontally/tangentially sprayed plasma gas for thermo-chemical gasification reaction at between 1200 and 1800° C., a central zone temperature is between 1800 and 2000° C., a retention time of the syngas in the gasification zone is between 1 and 10 seconds, and the power of the microwave plasma generators is controlled to drive the reaction to proceed completely.

8. The method of claim 1 , wherein in step 4), the volume content of CO and H 2 in the syngas exceeds 85%, the syngas contains no tar and no phenolic compounds, the liquid slag discharged from the slag outlet is chilled to be pollution-free, which can be used as a thermal insulation material.

9. The method of claim 3 , wherein in step 4), the volume content of CO and H 2 in the syngas exceeds 85%, the syngas contains no tar and no phenolic compounds, the liquid slag discharged from the slag outlet is chilled to be pollution-free, which can be used as a thermal insulation material.

10. The method of claim 7 , wherein in step 4), the volume content of CO and H 2 in the syngas exceeds 85%, the syngas contains no tar and no phenolic compounds, the liquid slag discharged from the slag outlet is chilled to be pollution-free, which can be used as a thermal insulation material.

11. The method of claim 8 , wherein in steps 2) and 3), the working gas and the carrier gas are air and/or oxygen and/or vapor; and the vapor is originated from the recycling of sensible heat of syngas.

12. The method of claim 9 , wherein in steps 2) and 3),

Assignees

• Wuhan Kaidi Eng Tech Res Inst

Inventors

• Chen Yilong
• Zhang Yanfeng
• Xia Minggui
• Zhang Liang

Classifications

• C10J2300/0976

  as steam · CPC title

• C10J3/466

  Entrained flow processes · CPC title

• C10J2200/152

  Nozzles or lances for introducing gas, liquids or suspensions · CPC title

• C10J3/506

  for entrained flow gasifiers · CPC title

• C10J2300/0906

  Physical processes, e.g. shredding, comminuting, chopping, sorting · CPC title