Method of gasification of biomass using gasification island

Patent metadata

Field	Value
Publication number	US-9410095-B2
Application number	US-201414316727-A
Country	US
Kind code	B2
Filing date	Jun 26, 2014
Priority date	Dec 29, 2011
Publication date	Aug 9, 2016
Grant date	Aug 9, 2016

Abstract

A method of gasification of biomass using a gasification island. The gasification island includes: a biomass pre-treatment and storage unit, a biomass feeder, an external heat source, a gasifier, a crude syngas cooling unit, a crude syngas washing unit, a fresh syngas storage unit, and an ash and wastewater treatment unit. The method includes: pre-treating and storing biomass, gasifying the biomass in the gasifier, cooling a crude syngas, washing and removing dust from the crude syngas, and storing fresh syngas.

First claim

The invention claimed is:

1. A method of gasification of biomass using a gasification island, the gasification island comprising: a biomass pre-treatment and storage unit, a biomass feeder, an external heat source, a gasifier, a crude syngas cooling unit, a crude syngas washing unit, a fresh syngas storage unit, and an ash and wastewater treatment unit, the method comprising:
pre-treating and storing biomass in the biomass pre-treatment and storage unit;
crushing the stored biomass in the biomass feeder;
gasifying the biomass in the gasifier by feeding the biomass to the gasifier while supplying the external heat source and an oxidant to the gasifier, controlling an operating temperature of the gasifier at between 1300 and 1750° C., allowing the biomass to fully contact with the oxidant so that desiccation, volatile matter precipitation, pyrolysis, and gasification reaction occur, respectively, whereby yielding a crude syngas and an ash;
removing a slag from the gasifier in a liquid state;
cooling the crude syngas by introducing the crude syngas to a quench tower and a two-stage waste heat boiler of the cooling unit to decrease the temperature of the crude syngas to between 85 and 200° C. and to recover the sensible heat; and
washing the crude syngas after sensible heat recovery in the washing unit and removing the dust therefrom in an electric dust precipitator of the ash and wastewater treatment unit to obtain the clean and fresh syngas having both a dust content and a tar content of 10 mg/Nm3 and a temperature of 45° C.;
transporting the clean and fresh syngas to the gas storage tank for storage;

wherein
the gasification island is operated at a negative pressure.

2. The method of claim 1 , wherein the external heat source is supplied by a plasma torch generator, a microwave plasma generator, or a laser thermal generator.

3. The method of claim 1 , wherein
a gasification medium is selected from the group consisting of air,
oxygen-enriched air, pure oxygen, water vapor, or a mixture thereof;
a temperature of a bottom of the gasifier is controlled between 1450 and 1750° C. whereby realizing the slag removal in the liquid state;
slag removal from the gasifier adopts continuous slag removal or intermittent slag removal, the continuous slag removal is adopted when the raw material has a high ash content, and the intermittent slag removal is adopted when the raw material has a low ash content;
a temperature of an upper part of the gasifier is controlled between 800 and 1450° C., a flow velocity of the crude syngas therein is controlled between 0.5 and 2.0 m/s; and
the crude syngas is introduced out of the gasifier via the upper part thereof, the flow velocity of the crude syngas at an outlet of the gasifier is controlled between 8 and 20 m/s, and the dust content in the crude syngas is 20 g/Nm3.

4. The method of claim 1 , wherein the crude syngas is cooled as follows:
the crude syngas is introduced from the gasifier through a water-cooling pipe to the quench tower, where the crude syngas is cooled to a temperature of below 850° C. by spray water, a water-cooling bundle, or a vapor-cooling bundle, and a molten slag carried by the crude syngas is cured and separated;
the crude syngas having the temperature of below 850° C. after treated by the quench tower is transported to a first-stage waste heat boiler for recovering waste heat, the temperature of the crude syngas is decreased to above a condensation point of a heavy tar, and a flow velocity of the crude syngas in the first-stage waste heat boiler is controlled between 7 and 20 m/s; and
the crude syngas from the first-stage waste heat boiler is transported to the second-stage waste heat boiler for recovering the waste heat, the crude syngas is continued being cooled and the temperature of the crude syngas is decreased to between 85 and 200° C., and the flow velocity of the crude syngas in the second-stage waste heat boiler is controlled between 7 and 20 m/s.

5. The method of claim 4 , wherein the crude syngas enters the first-stage waste heat boiler for recovering the waste heat, and the temperature of the crude syngas decreases to between 350 and 450° C.

6. The method of claim 1 , wherein the crude syngas is washed as follows:
the crude syngas after the heat recovery having the dust content of ≦20 g/Nm 3 is transported through a pipe to a scrubbing-cooling tower or a Venturi scrubber for further decreasing the temperature of the crude syngas and removing the dust therefrom; the temperature of the crude syngas after washing is decreased to between 15 and 55° C. and the wash water is circulated for use;
a filter is disposed on a water circulating pipe to remove pollutants carried by the circulating wash water; pollutants are discharged in time according to water quality of the circulating wash water, and fresh circulating water is supplemented;
the circulating water is cooled by a mechanical draft hollow cooling tower; and
a filter residue after curing is returned to the gasifier as a bed layer or is transported to an ash library along with the molten slag, thereby realizing a comprehensive utilization.

7. The method of claim 6 , wherein the dust removal of the crude syngas is conducted as follows:
the crude syngas from the scrubbing-cooling tower or the Venturi scrubber is introduced to a wet electric dust collector, where the dust and other impurities in the crude syngas is removed under the action of an electric field produced therein; and
the fresh syngas from the wet electric dust collector is transported by a coal gas booster fan to the gas storage tank or directly supplied to devices of the subsequent process as a feed gas.

8. The method of claim 1 , wherein
molten slags produced in the gasifier are granulated and used as a building material for comprehensive utilization; and
the ash from the cooling and washing units are cured and used as a bed layer of the gasifier for recycling.

Assignees

• Wuhan Kaidi General Res Inst Of Eng & Tech Co Ltd
• Wuhan Kaidi Eng Tech Res Inst

Inventors

• Zhang Yanfeng
• Xia Minggui
• Nie Hongtao
• Liu Wenyan
• Zhang Liang

Classifications

• C10K1/028 Primary

  by electrostatic precipitation (separating dispersed particles from gases or vapour by electrostatic effect in general B03C3/00) · CPC title

• C10K1/06

  combined with spraying with water {(C10K1/001 takes precedence)} · CPC title

• C10J2300/0976

  as steam · CPC title

• Y02E20/18

  Integrated gasification combined cycle [IGCC], e.g. combined with carbon capture and storage [CCS] · CPC title

• C10J2300/0906

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