Optimized Design Of Hollow Fiber Membrane Module For Low Temperature Flue Gas Dehumidification

Driven by the coal-to-gas policy,the use of natural gas boilers has increased,resulting in an increase in natural gas consumption.The main component of natural gas is methane.The flue gas produced after combustion contains a large amount of water vapor.If the flue gas is discharged without treatment,it will cause waste of water resources,haze,and chimney corrosion.In view of the large amount of water vapor in the gas boiler exhaust,this paper proposes a flue gas heat and moisture recovery system combining the flue gas waste heat recovery heat exchanger and the absorption heat pump.The gas boiler exhaust first passes the flue gas heat exchanger temperature from 150 ° C up to 55 ° C.Most of the recovered sensible heat is used to heat the heat network back water,and then the low temperature flue gas enters the dehumidification module and the hollow fiber membrane dehumidification module.The dehumidification solution is subjected to heat and mass exchange,and the moisture content is lowered and discharged through the chimney.The concentrated solution absorbs the water vapor in the flue gas and becomes a dilute solution.After being regenerated by the solution generator,it enters the component for recycling.This article will focus on the performance of hollow fiber membrane dehumidification components.The hollow fiber membrane is used in the dehumidification module,and the hollow fiber membrane is used as an intermediate medium to prevent direct contact between the gas and the liquid,thereby effectively preventing the gas-liquid entrainment and the dispersion of the solution.The choice of desiccant and membrane material is the key to affect the dehumidification performance and economy of the module.In this paper,the dehumidification principle of hollow fiber membrane is analyzed.Combined with the application background of low temperature flue gas dehumidification,the low cost Ca Cl2 solution and better performance are selected.Polyvinylidene fluoride film(PVDF)and preliminary design of the component structure.According to the designed component structure,a three-dimensional mathematical model was established.The coupled boundary conditions were used to solve the velocity field,temperature field and concentration field by COMSOL software.The flow and heat transfer and mass transfer between randomly arranged tube bundles were studied by simulation results.Secondly,the simulation is carried out under different working conditions such as inlet flue gas flow rate,inlet flue gas temperature and inlet solution flow rate.According to the simulation results,the heat and humidity transfer performance of dehumidification components and the factors affecting their performance are analyzed.Through numerical simulation,the effects of mass transfer area,component filling rate and filament length on dehumidification performance were investigated,and finally the optimal size of the dehumidification module was obtained.