| In recent years,WFGD(Wet Flue Gas Desulfurization)works as the main wet desulphurization process.Because of the characteristic of rapid reaction rate,high reaction efficiency and well operational stability,WFGD has been widely applied in flue gas treatment system of coal-fired units.After WFGD,the range of wet gas temperature is 45-60?,and the relative humidity could attain over 90%.It could achieve well effect of energy-saving emission reduction that if use some methods to recycle the water and latent heat.However existing devices such as indirect contact heat exchanger,limited by small temperature difference,easy scaling and high flow resistance,which could not fit engineering design requirements.An open heat pump application in waste heat recovering technology is used in this article,and latent heat recovery experimental facility is designed and built up based on open absorption heat pump(OAHP)system.Compared with several kinds of absorbent physical property,the CaCl2 solution is considered as the absorbent and the water vapor in the flue gas as working medium.The absorber adopts the structure that combines spray with padding.The regenerator adopts the form of vacuum distillation which could achieve better gas-liquid reaction and energy recovery results.In this system,there's solution-water chiller,solution heat recovery device and condense of regenerating steam,which use for solution cooling,pre-heat and condensing respectively.In order to analyze the relation between the parameters and the effect of the absorbent and regenerative process,the experimental study has been proceeded for the parameters.The results show that:decreasing the inlet temperature of absorbent,increasing liquid-gas ratio and the concentration of solution could reinforce the absorption effect.Increasing regenerative temperature,decreasing regenerative pressure and the concentration of solution could reinforce the regenerative effect.Recommended range of relevant parameters based on experimental data is given in the meantime.The thermodynamic evaluation is given according to operating parameters of the whole experiment.Under the experimental conditions,the Coefficient of Performance(COP)could reach up to 1.72.The cooling water temperature increases from 23.1? to 44?,and the system has good performance of heat recovery.According to the analysis result,solution-water chiller is the main energy using device,and the capacity accounts for about 50%of the system.With the combination of regenerative pressure and thermal load,the regeneration effect is better than single condition.The whole technological process is established by using the software Aspen Plus.The results of checking agree well with the experimental results in most devices,and the parameters which deviated from experimental results could be corrected by the tools of software which called data fit.The modules of Sensitivity and Design Spec used in technological process,which are to test the change of internal parameters impact on system performance.The parameters of cooling water,absorbent solution and regeneration are selected to be analyzed by sensitivity modules.Above parameters are simulated based on outlet design requirements,and the trends of system performance and are drawn.The results show that decreasing flow rate of cooling water,increasing the temperature of cooling water,decreasing flow rate of absorbent and the temperature of absorbent could lead to the increasing of COP.The flow rate of cooling water should not be over 500kg/h in order to achieve hot water outlet temperature over 50?.Hot water outlet temperature is 46.2 ?,and COP is 1.58,when the thermal load of regenerator is 6.5kw,the pressure of regenerator is 22kPa,the inlet temperature of cooling water is 24.8?,and the flow rate of cooling water is 500kg/h. |
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