The Technology Of Liquefying And Recovering Methane And Corban Dioxide From Biomass Gas

Biomass Gas is the gas turned sour from the residue of Biodiesel's producing which produced from the seeds of jatropha curcas, palm, flax, etc. As the development of Biodiesel industry, the ways of how to use this residue become a question worth investigating. Biomass Gas is generally composes by methane, carbon dioxide, and little hydrogen sulfide. Methane is a kind of high-calorie and clean fuel, and carbon dioxide is a kind of very important industrial raw materials. The purpose of this paper is to build a process simulation model (flow sheet), which simulates the process of separating methane and carbon dioxide from the Biomass Gas, and liquefying them; and analyzes the main parameters of the process simulation; and optimizes the parameters of the process simulation on the basis of analysis, which makes the flow sheet's energy consumption less and the flow sheet simpler.Firstly, this thesis introduces a part of ways of desulfurization, ways of carbon dioxide-absorption, ways of dehydration, and ways of liquefaction, which provides the base for building process simulation model.Secondly, this thesis chooses appropriate ways, and uses HYSYS to build the son flow sheets, which named Desulfurization Flow Sheet, Separation Flow Sheet, Dehydration Flow Sheet, and Liquefaction Flow Sheet. Desulfurization uses the way of Activated Carbon; carbon dioxide-absorption uses the way of Amine; dehydration uses the way of Molecular Sieve, liquefaction uses the way of Close Mix Refrigerant Cycle. Combine all of the son flow sheet and the parts of compression to form integrated flow sheet, which named Biomass Gas Liquefied Flow sheet.Thirdly, this thesis analyzes the main parameters of the Separation Flow sheet and the Liquefaction Flow Sheet in detail. The main parameters of Separation Flow Sheet contain the composition of amine solution, the carbon concentration of poor liquid, the flow rate of poor liquid flowing in absorber, the pressure of absorber, the temperature of poor liquid, the pressure of flash tank, the temperature of rich liquid flowing in regenerator, etc. The main parameters of Liquefaction Flow Sheet contain the composition of mix refrigerant, the temperature of gas-liquid separator, the pressure of methane gas, the pressure of carbon dioxide gas, the pressure and the pressure ratio of refrigerant, the temperature of low-pressure refrigerant, the temperature of hot flow between heat exchanger, the pressure of LNG, etc. In the process of parameter analysis, it needs to remain some basic parameters as adjustable parameters to satisfy the constraints. In this paper the basic parameters of Separation Flow Sheet are the flow rate of poor liquid flowing in absorber, the temperature of poor liquid, and the pressure of flash tank; and he basic parameters of Liquefaction Flow Sheet are the composition of mix refrigerant and the total flow rate of mix refrigerant. Though the parameter analysis, it can get the relationship between these parameters and the flow sheet's main performance parameters such as energy consumption.Lastly, this thesis optimizes the parameters of the flow sheet on the basic of parameter analysis, and gives out the data of the flow sheet which optimized.This thesis gives out a method of parameter analysis and parameter optimization, which is using in separating methane and carbon dioxide by the way of amine. And there is reference value of this method in using amine to remove acid gas. And the optimization of Separation Flow Sheet and Liquefaction Flow Sheet is very important for cutting down operating costs.