A method and plant of production of combustible gas using biomass

Abstract

This invention involves a method and plant of production of combustible gas using biomass. This plant comprises a furnace body, a furnace cavity, gasifying agent inlet, combustible gas outlet (arranged on furnace cavity and higher than gasifying agent inlet), and a device that ignites biomass arranged at intersection between the horizontal plane where the combustible gas outlet is located and the internal wall of the furnace cavity. Method of operation: load biomass in the plant and ignite the upper part; gasifying agent will run through the material from bottom to top, gasifying the material and generating flue gas. This invention features outstanding advantages of stable gasifying reaction, safe and reliable operation, high fuel gas calorific value, low environmental pollution, and easy purification of combustible gas etc. This method can be used to produce combustible gas from not only biomass, but also solid organic gasifying raw materials such as household garbage and industrial refuse etc.

Description

FILED OF THE INVENTION[0001]This invention relates to the technology of biomass energy equipment, in particular a method and plant of production of combustible gas using biomass.BACKGROUND OF THE INVENTION[0002]Biomass is a regenerative energy source that features the following: ① regeneration; ② low pollution; ③ wide distribution. Use of biomass as alternative energy source can improve environment, in that acid rain and CO2 in atmosphere can be reduced, thereby has active significance in alleviating the “greenhouse effect”. Volatile content of biomass is as high as above 70%. After being heated, biomass can release large amount of volatile matter at relatively low temperature. Therefore, gasifying technology is very suitable for conversion of biomass raw material. The high grade fuel gas generated by biomass gasification can be directly used as fuel for production and living purposes, and also used for internal combustion engine or gas turbine for power generation, to realize combi...

AI Technical Summary

Benefits of technology

[0005]The purpose of this invention is to overcome aforesaid problems in upper and lower suction methods / plants, and provide a method and plant capable of safe and reliable operation, low tar content in fuel gas, stable gasification process, and low pollution.

[0009]Combustible gas produced can further pass a layer of biomass material, for purification of fuel gas and increase of calorific value.

[0016]1. Stable gasification reaction. During gasification, dry biomass material forms a reduction layer, an oxidation layer, a pyrolysis layer, and a drying layer from top to bottom. In this sequence, material density of these layers increases. This is totally different from traditional gasifying methods in which reduction layer and oxidation layer are under pyrolysis layer and drying layer. In this way, discontinuity between gasifying reaction levels, caving in, and burning-through etc. due to gravity can be avoided. This invention very much favors manufacture of large gasifying plants.

[0017]2. High calorific value of fuel gas and low environmental pollution. Since the reduction layer constantly expands downward during gasification reaction, the levels are stable, and the temperature is maintained at 700° C.˜900° C., so that CO2 generated by pyrolysis layer and oxidation layer is subject to reduction reaction to generate more CO, and tar in flue gas is subject to cracking when passing reduction layer to become combustible gas, so that tar content in fuel gas is greatly lowered, difficulty of subsequent fuel gas purification is lessened, environmental pollution is reduced, and fuel gas calorific value exceeds 5MJ / m3.

[0018]3. Safe and reliable operation. The gasifying plant of this invention operates under slight positive pressure and safety hazard due to poor seal and external air entering the plant and in contact with high temperature fuel gas is avoided. The gasifying plant of this invention can be shutdown at any time, and the danger of accidental shutdown as present in lower suction type plant is avoided.

[0019]From above description, it can be seen that the method and plant of this invention have broken through traditional practice of biomass gasification. By means of simple and practical means, gasification reaction levels have been improved to provide outstanding advantages of stable gasification reaction, safe and reliable operation, high calorific value of fuel gas, low environmental protection, and easy purification of fuel gas. This invention is not only applicable to production of combustible gas from biomass, but also from solid organic gasification raw materials such as household garbage and industrial refuse etc.

Problems solved by technology

In addition, this process requires large investment.

For these reasons, it is very difficult to promote this method in China.

Upper suction type gasifying plant features safe operation, but has disadvantages of high tar content in fuel gas generated, difficult purification, unstable gasification process, and serious environmental pollution etc.

Although the lower suction type gasifying plant features lower tar content, more stable gasification, and lower pollution as compared with upper suction type gasifying plant, it is subject to discontinuity between gasifying reaction levels, caving in, and burning-through etc., which adversely affect gasifying effect.

In addition, due to slightly negative pressure operation, if sealing of the gasifying plant is not good, external air may enter the plant and be in contact with high temperature fuel gas, resulting in safety hazard.

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