Optimization And Evaluation On Flue Gas Purification And Waste Heat Recovery System

Coal-fired boiler is one of the important energy equipment in China.Boiler flue gas contains tremendous of sulfur,nitrogen and other pollutants,which cause serious damage to environments.The traditional coal-fired boiler room flue gas treatment is usually used dust collector,desulfurization tower,dehumidification tower and other equipment,which has the problem such as large site area,high initial investment and other issues.In order to solve the above problems,a flue gas purification and waste heat recovery system,which can combine the desulfurization tower with dehumidification tower,was constructed.To achieve the purpose of boiler flue gas desulfurization,dehumidification and waste heat recovery were analyzed simultaneously.Based on the analysis of quality balance and energy balance of coal-fired boiler room,the flue gas purification and waste heat recovery system structure were studied.The main equipment of the system includes:economizer,air preheater,solution-desalination water heat exchanger,low temperature energy converter and high temperature energy converter.The moisture absorber in the low temperature energy converter is Ca?Cl?₂ and the balance agent is Ca?OH?₂.On the basis of rationally simplified model,the main components and systems in the flue gas purification and waste heat recovery system are modeled mathematically.Low-temperature energy converter heat transfer,mass transfer model,high-temperature energy converter sub-calculation model and the main heat exchanger model were build.Write the MATLAB program which can call the REFPROP9.0 for the working parameters.The method of solving the model is also studied.Taking the dynamic investment payback period as the objective function,the flue gas temperature and the liquid-gas mass ratio of the low-temperature energy converter are chosen as the optimization variables.The particle swarm optimization algorithm is used to optimize the flue gas purification and waste heat recovery system.The key parameters such as PH value and liquid-gas mass ratio of the moisture-absorbing solution were studied.The optimized flue gas temperature of the optimized low-temperature energy converter is 130?.When the liquid-mass ratio is 2.2,the minimum value of the dynamic investment payback period is 2.48 years.The optimization design and evaluation of flue gas purification and waste heat recovery in a coal-fired boiler room were sutdied.Introduced the waste heat recovery system start and stop process and maintenance experience.After the case of energy-saving transformation,the recovery of flue gas waste heat is 716.5kW,which is 4.08 times than the original waste heat recovery system.The overall dust removal efficiency is 95.5%and the desulfurization efficiency is 91.4%.Energy-saving emission reduction capacity is better.the Net income of this system after the optimized design is 428,000 yuan per year.The dynamic payback period is 2.73 years which shows the economic indicator is good.The study of flue gas purification and waste heat recovery system,can meet the boiler flue gas desulfurization,dehumidification requirements on the basis of the recovery of flue gas waste heat.In addition to economic benefits for the production unit,the system can achieve energy saving and environmental protection objectives.The boiler room flue gas purification and waste heat recovery technology has a guiding significance.