Biomass gasification technology is analysed

Biomass gasification technology is analysed

Biomass energy is the energy of human use of the earliest and most, contains the huge energy, the creatures of the earth's total output of up to 1400 t ~ 1800 t every year, equivalent to 10 times the world's total energy consumption, have great potential for the development and utilization of. And since the biomass energy has the superiority of renewable, low pollution and wide distribution, biomass gasification technology has become a hot spot in the field of energy development and utilization of content.



1 biomass gasification principle, process and equipment

Biomass gasification in certain thermodynamic conditions, in the case of limited oxygen incomplete combustion in the biomass, combustible part at the same time will be converted to gas thermal chemical reaction. Due to gasification device type, the type of gasification agent, reaction conditions, material properties, process conditions, such as material of the gasification process is complicated, but most include solid fuel drying, pyrolysis reaction, reduction reaction, and four basic processes such as oxidation reaction. Drying process requires a large amount of heat to the water released in full. Began to occur when the temperature is above 160 ℃ the thermal decomposition reaction of macromolecule organic matter, and the higher the temperature, decomposition were the more fierce. Due to the higher volatile matter is contained in biomass, so at a lower temperature (300 ℃ ~ 400 ℃) can release 70% volatile (carbon dioxide, carbon monoxide, methane, hydrogen, etc.) and parse out the tar, carbon constitute a further reaction bed at the same time. Then carbon layer with the water in the air, hydrogen, carbon dioxide reduction reaction to generate combustible gases. Oxidation of carbon and oxygen generated by incomplete combustion of carbon monoxide, at the same time gives off heat, the temperature is 1000 ℃ ~ 1200 ℃. Biomass gasification system is the core of the application of the equipment for the gasifier. Biomass gasification unit in accordance with the gasification method can be divided into two types, namely fixed bed gasifier and fluidized bed gasifier.



2 new technology of biomass gasification

2.1 biomass gasification tar catalytic cracking

In the process of biomass gasification, the gasification temperature is low, the tar content in the gasification process of gas big (tar energy accounted for 5% ~ 10%) of combustible gas energy. Low temperature tar liquid with water, combined into solidification state material such as charcoal particles, not only may clog, gas pipeline and valve hole, at the same time has a role in the corrosion of metal pipeline and affected the normal work of the equipment, at the same time also can cause secondary pollution.

The tar removal methods mainly including wet method, dry method and catalytic cracking process. The poor performance of wet process and dry process purification: wet method to remove tar, tar failed to make full use of, and the resulting wastewater effluent is easy to cause environmental pollution. Dry to remove tar tar deposition seriously and filter material from a large amount of tar, difficult to handle.

Cracking purification technology is to join in the process of biomass gasification catalyst (Ni catalyst, calcined dolomite, olivine and iron catalysts, etc.) will tar