阅读说明：本技术 降低生物质流化床气化炉合成气中焦油含量的方法 (Method for reducing tar content in biomass fluidized bed gasification furnace synthesis gas ) 是由 罗康 孙萍 赵渊 杨国祥 于 2019-10-15 设计创作，主要内容包括：本发明涉及一种降低生物质流化床气化炉合成气中焦油含量的方法,其将生物质流化床气化炉产生的飞灰负载氧化钙,然后送入降低生物质流化床气化炉。本发明将负载氧化钙后的飞灰作为床料输送至气化炉,使焦油在炉内进行催化裂解能有效降低焦油含量,并且克服了固定床催化裂解法的缺点。同时,合理利用了气化灰渣,对生物质流化床气化技术的开发与发展具有推动作用,且具有较好的应用前景和经济效益。(The invention relates to a method for reducing tar content in synthesis gas of a biomass fluidized bed gasification furnace. The fly ash loaded with calcium oxide is conveyed to the gasification furnace as bed material, so that the tar content can be effectively reduced by performing catalytic cracking on the tar in the furnace, and the defect of a fixed bed catalytic cracking method is overcome. Meanwhile, the gasification ash is reasonably utilized, so that the method has a promoting effect on development and development of the biomass fluidized bed gasification technology, and has a good application prospect and economic benefit.)

1. A method for reducing tar content in synthesis gas of a biomass fluidized bed gasification furnace is characterized in that fly ash generated by the biomass fluidized bed gasification furnace is loaded with calcium oxide and then is sent into the biomass fluidized bed gasification furnace for reducing tar content.

2. The method for reducing the tar content in the synthesis gas of the biomass fluidized bed gasifier according to claim 1, wherein the fly ash is loaded with calcium oxide by an impregnation method to form a biomass ash containing calcium oxide, and the mass fraction of the calcium oxide in the biomass ash is 1% -3%.

3. The method for reducing the tar content in the synthesis gas of the biomass fluidized bed gasification furnace according to claim 2, wherein the solution adopted by the dipping method is CaO to H in a mass ratio₂And (3) preparing a saturated solution with the ratio of O to O being 1: 100.

4. The method for reducing the tar content in the synthesis gas of the biomass fluidized bed gasifier according to claim 1, wherein the fly ash is loaded with calcium oxide by means of atomization spraying to form a biomass ash containing calcium oxide, and the mass fraction of the calcium oxide in the biomass ash is 1% -3%.

5. The method for reducing the tar content in the synthesis gas of the biomass fluidized bed gasification furnace according to claim 4, wherein the solution adopted by the atomized spray is CaO to H in a mass ratio₂And (3) preparing a saturated solution with the ratio of O to O being 1: 100.

6. The method for reducing the tar content in the syngas of the biomass fluidized-bed gasifier according to claim 1, wherein the fly ash loaded with calcium oxide is mixed with biomass fuel, dried, and then fed into the biomass fluidized-bed gasifier.

7. The method for reducing the tar content in the synthesis gas of the biomass fluidized bed gasifier according to claim 6, wherein the biomass fuel is straw, rice hulls, wood chips, dried wine lees or cane sugar residues.

8. The method for reducing the tar content in the synthesis gas of the biomass fluidized bed gasifier according to claim 1, wherein the furnace type of the biomass fluidized bed gasifier is a circulating fluidized bed gasifier, the furnace temperature is controlled to be 700-750 ℃, the biomass fluidized bed gasifier is connected with a two-stage cyclone separator for capturing fly ash, and an ash discharge port at the bottom of the biomass fluidized bed gasifier is connected with a spiral slag conveyor.

9. The method for reducing the tar content in the synthesis gas of the biomass fluidized bed gasifier according to claim 1, wherein the gasifying agent introduced into the biomass fluidized bed gasifier is air.

Technical Field

The invention relates to the technical field of biomass gasification, in particular to a method for reducing tar content in synthesis gas of a biomass fluidized bed gasification furnace.

Background

The promotion of the development of renewable clean energy is one of effective measures for energy conservation and emission reduction, wherein the biomass energy is rich in storage amount and is the fourth largest energy next to coal, petroleum and natural gas. The biomass gasification technology is one of important thermal conversion technologies for biomass utilization, and biomass gasification refers to the process of using biomass fuel including strawThe stalks, barks, prunes and the like are gasified with a gasifying agent to generate synthesis gas (CO and H)₂) The process of (a), large-scale commercial operation is realized at present.

Because biomass belongs to low-order fuel, more tar can be produced in the thermal conversion process, the quality and the utilization efficiency of synthesis gas are reduced, and subsequent pipelines and equipment are blocked and contaminated, which is a main problem to be solved in biomass gasification. Therefore, it is necessary to perform deep tar removal before power generation or synthesis of liquid fuels using syngas. The tar removal is generally carried out by a water washing method or a catalytic cracking method.

The water washing method is a common tar removing means in large chemical plants, and belongs to wet tar removal, namely, a method for quickly cooling tar by using water washing fuel gas so as to realize tar condensation and fall along with liquid drops is generally realized by a spray device of a cooling washing tower. The water scrubbing process is a very effective tar removal process, but this process generates a large amount of waste water, which results in energy waste, and the separation of tar from the syngas, with a consequent reduction in the calorific value of the fuel gas, which reduces the overall efficiency of the gasification. The waste water containing tar comprises a large amount of organic matters, inorganic acid and NH₃And the random discharge can cause serious pollution, subsequent treatment is needed, and a proper wastewater treatment method needs to be found when a washing method is selected for removing tar, so that the investment cost of environmental protection is increased.

The electric tar precipitator ionizes synthesis gas by using a high-voltage electric field, wherein most tar particles are negatively charged and adsorbed on the surface of a precipitation electrode along the direction of a power line to discharge charges to form medium-sized oil particles, the oil mist particles are continuously condensed on the surface of a polar plate, the particles are enlarged to form oil drops, and the oil drops flow to the bottom of equipment along the surface of the precipitation electrode and are discharged through a sewage outlet. The tar removal efficiency of the equipment is high, but the equipment is expensive and is not easy to popularize.

The catalytic cracking of tar is also one of effective means for removing tar, and the combustible component H in the synthesis gas is also added while removing tar₂And CH₄And the gas content is equal, so that the gas content is widely concerned. The research finds that CaO does not catalyze and crack tarThe catalyst is effective, and CaO is cheap and easy to obtain, so that the catalyst is one of ideal catalysts for catalytic cracking of tar. However, natural limestone and other calcium-rich minerals have low specific surface area and porosity, which are not favorable for the gas-solid heterogeneous catalytic reaction.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a method for reducing the tar content in the synthesis gas of a biomass fluidized bed gasification furnace, reasonably utilize gasification ash, and simultaneously, obviously reduce the tar content in the synthesis gas.

The technical scheme adopted by the invention for solving the technical problems is as follows: the method for reducing the tar content in the synthesis gas of the biomass fluidized bed gasification furnace is constructed, and fly ash generated by the biomass fluidized bed gasification furnace is loaded with calcium oxide and then is sent into the biomass fluidized bed gasification furnace for reducing the tar content.

In the scheme, the fly ash is loaded with calcium oxide by using an impregnation method to form biomass ash containing calcium oxide, wherein the mass fraction of the calcium oxide in the biomass ash is 1-3%.

In the scheme, the solution adopted by the dipping method is CaO to H in a mass ratio₂And (3) preparing a saturated solution with the ratio of O to O being 1: 100.

In the scheme, fly ash is loaded with calcium oxide in an atomization spraying mode to form biomass ash containing calcium oxide, and the mass fraction of the calcium oxide in the biomass ash is 1-3%.

In the scheme, the solution adopted by atomization spraying is CaO to H in mass ratio₂And (3) preparing a saturated solution with the ratio of O to O being 1: 100.

In the scheme, the fly ash loaded with calcium oxide is mixed with biomass fuel, dried and then sent into a biomass fluidized bed gasification furnace.

In the scheme, the biomass fuel is straw, rice hulls, wood chips, dried distiller grains or sucrose residues.

In the scheme, the furnace type of the biomass fluidized bed gasification furnace is a circulating fluidized bed gasification furnace, the furnace temperature is controlled to be 700-750 ℃, the biomass fluidized bed gasification furnace is connected with a two-stage cyclone separator for capturing fly ash, and an ash discharge port at the bottom of the biomass fluidized bed gasification furnace is connected with a spiral slag conveyor.

In the scheme, the gasification agent introduced into the biomass fluidized bed gasification furnace is air.

The method for reducing the tar content in the synthetic gas of the biomass fluidized bed gasification furnace has the following beneficial effects:

1. the carbon content of the fly ash of the biomass fluidized bed gasification furnace reaches 50 percent, carbon in the biomass raw material fed into the furnace is discharged out of the furnace without reaction, so that a great deal of energy loss is caused, and the porosity of carbon-containing ash in ash is high, so that the fly ash is an ideal carbon-based catalyst carrier. After the fly ash is loaded with calcium oxide, the fly ash is used as a bed material heat carrier in the biomass fluidized bed gasification furnace, which is beneficial to the catalytic cracking reaction of a tar precursor in the furnace, thereby effectively reducing the tar content in the synthesis gas, improving the heat value of the synthesis gas and reducing the treatment difficulty of subsequent equipment.

2. The fly ash loaded with calcium oxide is conveyed to the gasification furnace as bed material, so that the tar content can be effectively reduced by performing catalytic cracking on the tar in the furnace, and the defect of a fixed bed catalytic cracking method is overcome. Meanwhile, the gasification ash is reasonably utilized, so that the method has a promoting effect on development and development of the biomass fluidized bed gasification technology, and has a good application prospect and economic benefit.

3. The invention changes waste into valuable, utilizes fly ash in the fluidized bed gasification furnace, and saves bed material quartz sand required by a normal biomass fluidized bed gasification furnace. The fly ash is returned to the furnace again, which is beneficial to the further reaction of the unreacted carbon in the fly ash, thereby overcoming the defect of low carbon conversion rate of the biomass fluidized bed gasification furnace.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a schematic diagram of the method for reducing tar content in syngas of a biomass fluidized bed gasifier according to the present invention;

FIG. 2 is a scanning electron micrograph of fly ash loaded with calcium oxide in example 1; .

FIG. 3 is a scanning electron micrograph of the silica sand of comparative example 1.

Detailed Description

For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

As shown in figure 1, the method for reducing the tar content in the synthesis gas of the biomass fluidized bed gasification furnace comprises the following steps: the fly ash generated by the biomass fluidized bed gasification furnace is loaded with calcium oxide and then sent into the biomass fluidized bed gasification furnace.

Preferably, the fly ash loaded with calcium oxide is mixed with biomass fuel, dried and then sent into a biomass fluidized bed gasification furnace.

Preferably, the biomass fuel is straw, rice hull, wood chips, dried distillers' grains or cane sugar residues.

Preferably, the biomass fluidized bed gasification furnace is a circulating fluidized bed gasification furnace, the furnace temperature is controlled to be 700-750 ℃, the biomass fluidized bed gasification furnace is connected with a two-stage cyclone separator for capturing fly ash, and an ash discharge port at the bottom of the biomass fluidized bed gasification furnace is connected with a spiral slag conveyor.

Preferably, the gasification agent introduced into the biomass fluidized bed gasification furnace is air.

Preferably, the fly ash is loaded with calcium oxide by an impregnation method to form biomass ash containing calcium oxide, wherein the mass fraction of the calcium oxide in the biomass ash is 1-3%. The solution adopted by the dipping method is CaO to H in the mass ratio₂And (3) preparing a saturated solution with the ratio of O to O being 1: 100.

Preferably, the fly ash can be loaded with calcium oxide by using an atomization spraying mode to form biomass ash containing calcium oxide, and the mass fraction of the calcium oxide in the biomass ash is 1-3%. The solution adopted by atomization spraying is CaO to H in mass ratio₂And (3) preparing a saturated solution with the ratio of O to O being 1: 100.