Efficiency Of Gasification Process Research Articles

Development оf energy saving technology of two-stage biomass gasification for cogeneration plants

A two-stage fine biomass gasification process for the low - power generation plants based on ICE, providing the tar content in the producer gas of no more than 7.1 mg/m3n that meets the requirements of the ICE producers was developed. Based on the results of experimental studies of the two-stage fine biomass gasification process, the effective process regimes were determined. The optimal range of the specific air flow, which provides a stable process of oxidative biomass pyrolysis in a dense layer at the pyrolysis temperature not exceeding 800oC is 25.0 55.0 m3/(m2 h).Efficiency of the oxidative pyrolysis process reaches 98.0% taking into account the disposal of all heat flows. Efficiency of the coke residue gasification process without the use of sensible heat of the producer gas is on average 78.0%. Using the sensible heat of the producer gas allows to improve gasification process efficiency to an average of 96.4%.Numerical and theoretical studies of gas ICE operation have shown that the gas ICE operation on the producer gas with a calorific value of 7.6 MJ/m3 is optimum. In this case, the fall of ICE effective power is 16.0%, and the cost of electric power generation is 0.39 UAH/(kW∙h). The results of studies have also shown that increasing the natural gas proportion in a mixture of more than 40.0% is not desirable, since it leads to higher cost of electric power generation up to 1.04 UAH/ (kW∙h) that corresponds to the cost of electric power from the external power system.Exergy analysis of a cogeneration plant has shown a high value of total exergy efficiency of 45 %, while exergy efficiency of individual circuit elements, such as a pyrolyzer and gasifier reaches 96 %, and the "ICE-generator" unit - 91 %. Such values of efficiency are caused by deep disposal of all heat flows in the circuit.

Thermodynamic modelling of fate and removal of alkali species and sour gases from biomass gasification for production of biofuels

The development of advanced synthesis gas cleaning technologies based on chemical conversion and physical separation can improve the efficiency of gasification processes for production of biofuels. This paper outlines thermodynamic equilibrium calculations on the release and removal of alkali species and sour gases during gasification of 24 different types of herbaceous and woody biomass under the conditions of the gasifier in Gussing, Austria. In general, the calculation results are in good agreement with former experimental results. The composition of the gasifier derived as well as the cleaned gas strongly depends on the used feedstock. The alkali concentration can be limited to values below 100 ppbv using aluminosilicates at 850 °C. The H2S concentration cannot be limited to values below 200 ppmv using conventional Ca- or Cu-based sorbents but can be limited to values below 1 ppmv by stabilised BaO at 850 °C. The HCl concentration can be limited to values below 1 ppmv by alkali carbonates at temperatures below 550 °C.

A Novel Biomass Gasifier for Producing Tar-Free and Hydrogen-Rich Syngas

Hydrogen from biomass gasification is reviewed as one of the promising clean energies approaches in the future for fuel cell. However, the syngas from biomass gasification usually contains a certain amount of tar, which could not only decrease the efficiency of gasification process and hydrogen production, but also condense as a dense mixture and impose a series of serious problems. So “Excess Enthalpy Gasification (EEG)” is put forward and applied into biomass gasification and a novel biomass gasifier is presented for the purpose of tar-free and hydrogen-rich syngas in this work. The structure characteristic of the gasifier and tar conversion characteristic are analyzed detailedly to prove the feasibility and excellence performance for producing tar-free and hydrogen-rich syngas from biomass gasification.

Thermodynamic analysis of coal gasification processes

Thermodynamic analysis for evaluating and improving coal gasification process efficiency requires estimation of enthalpy, entropy, and availability transformations in various process steps. A compilation of procedures and data relevant to coal gasification processes is presented for calculating the above thermodynamic properties. Enthalpy and availability transformations are estimated for significant process steps in the HYGAS ® process for ptoducing substitute natural gas from coal. The thermal efficiencies based on the first law of thermodynamics are compared with the availability efficiencies based on the second law. Work intensive process steps, such as gas compression and separation, are shown to have extremely low thermal efficiencies and fairly high availability efficiencies. Heat intensive process steps, such as steam generation, have high thermal efficiencies but generally poor availability efficiencies.