Study Of Combined Cooling Heating And Power System Based On Biomass-steam Gasification

Nowadays,the energy shortage and environmental pollution are very serious.The utilization of the biomass energy is rasing.Biomass as a renewable energy is rich in resources and low pollutional,which has become the important strategic choice in many countries.This paper proposed a rational use of biomass energy through combining cooling heating,and power(CCHP)system with biomass gas based on biomass-steam gasification.Firstly,two CCHP systems intergrated with biomass-steam gasification are proposed.One is burning the biomass gas and the other is using the electric to provide the heat needed in the gasification process.In order to realize the stepwise use of energy,the CCHP system integrates with heat pipe heat exchanger(HPHE)to recover the waste heat of the product gas from gasifier to produce the steam needed in the gasification,which can save other steam generators.The configuration,equipment selection and energy utilization of the two subsystems are also analyzed.Secondly,the three different operation strategies of the CCHP system are presented,which are summer condition,winter condition and transition season condition.The status of a hotel in Beijing being an example demonstrates the analyses.In order to compared with the CCHP system integrated with biomass-air gasification,the energy and exergy flows are analyzed based on the first and the second laws of thermodynamics.The primary energy efficiency and exergy efficiency in different operation strategies are obtained.The hourly loads of typical days in the cooling and heating conditions are choosed to analyse the CCHP system performance.Finally,based on the exergoeconomic theory and integrated with energy grade,the modified product allocation model of the biomass-steam gasification CCHP system has been analysed.The exergoeconomic performance of all equipments in the CCHP system are obtained and unit exergy cost of electricity,chilled water(water for heating)and domestic hot water are calculated both in summer and winter conditions.Moreover,sensitivity analysis has been conducted to indicate the effect law of unit exergy cost along with the key factors,such as biomass cost,investment capital,interest rate and operation time.