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This post was last edited by yangshaoj2005 on 2017-12-16 07:45. What does the hot gas efficiency of gasification refer to? Is it generally calculated based on the high or low calorific value of coal gas or coal? Answer: The efficiency of hot gas is the ratio of the sum of the chemical energy of the gas produced by gasification and the increase in enthalpy of the steam generated in the gasifier and the hot gas sensible heat utilization system, to the chemical energy of the coal used for gasification. ““The increase in the enthalpy of steam” refers to the difference between the enthalpy of the steam generated in the sensible heat utilization system and the enthalpy of its feed water. It is generally calculated based on the lower heating value of gas and coal fed into the furnace
The ratio of the sum of the chemical energy of the coal gas generated by gasification and the increase in enthalpy of the steam produced in the gasifier and the hot gas sensible heat utilization system, to the chemical energy of the coal used for gasification. High calorific value
The ratio of the chemical energy of the gas produced after coal gasification to the chemical energy (higher heating value) of the coal used for gasification is known as the thermal gasification efficiency, which is generally calculated based on the higher heating value
Thanks for the advice! After checking the answer key, I realized my understanding was too superficial and too literal
Thermal gas efficiency = (chemical energy of the generated gas + thermal energy utilized in generating steam in the gasifier) / chemical energy of the coal used for gasification. The difference between the high calorific value and the low calorific value lies in whether the water in the fuel combustion products is in liquid or gaseous form; a liquid state of water corresponds to the high calorific value, while a gaseous state corresponds to the low calorific value. The lower heating value is equal to the higher heating value minus the heat of condensation of water vapor. Most fuel is used for combustion, and the flue gas temperatures in various furnaces exceed the condensation temperature of water vapor; therefore, it is not possible to release the heat of condensation of water vapor. As a result, in energy utilization, the lower heating value of the fuel is generally used as the basis for calculations. Countries make different choices: Japan and the countries in North America generally use the high calorific value, while China, the former Soviet Union, Germany, and the Organization for Economic Co-operation and Development use the low calorific value for conversions; some countries use both types of calorific values. The difference between the high and low calorific values of coal and oil is about 5%, while for natural gas and city gas it is around 10%
Hot gas efficiency: the ratio of the chemical energy (higher heating value) of the gas produced as a result of coal gasification to the chemical energy (heating value) of the coal used for gasification； It is generally calculated using the geothermal potential value
The ratio of the sum of the chemical energy of the coal gas produced by gasification and the increase in enthalpy of the steam generated in the gasifier and the hot gas sensible heat utilization system, to the chemical energy of the coal used for gasification. ““The increase in the enthalpy of steam” refers to the difference between the enthalpy of the steam generated in the sensible heat utilization system and the enthalpy of its feed water. It is generally calculated based on the lower heating value of gas and coal fed into the furnace
The hot gas efficiency ηr is defined as the ratio of the sum of the chemical energy of the gas generated by gasification and the increase in enthalpy of the steam produced in the gasifier and the hot gas sensible heat utilization system, to the chemical energy of the coal used for gasification. Calculated based on the high price of gas and coal.