Absorption Heat Pump To Recycle The Waste Heat Of Chlor-alkali Evaporation

Absorption heat pump is a kind of energy saving equipment, which can recover waste heat that can't be recovered by the conventional means because its temperature is too low. So if absorption heat pump is used, a great deal of heating steam will be saved, at the same time greenhouse gas will also be largely reduced. At present, absorption heat pump technology is gived attention by every country.A new combination way of open absorption heat pump is proposed, which is used to recover waster heat in the workshop section of evaporation of chlorine-alkali. In this new combination way without evaporator and condenser, low-pressure steam is directly absorped by absorber and steam vaporised from generator is directly sent to brine heat exchanger to preheat brine, so it saves much investment.Based on the first law of thermodynamics, the thermodynamic performance of OAHP is analysed and the results show that the heat input at the generator temperature is separated into two parts, one goes to brine heat exchanger following steam vaporised from generator and the other flows to absorber following the work fluids, and that main reason of the decrease of coefficient of performance of OAHP is the strong solution brings more high temperature level heat to the absorber. In order to improve COP, a heat exchanger should be used for heat exchange of solutions that come in and go out the generator.The optimization model of OAHP with objective funtion of net present value in the serivce life shows that as FR increases, the objective funtion firstly increases and then decreases. There is a suitable FR value in the range of 7 to 10. As EF increases, the objective funtion increases, but too high EF requires higher FR, or else crystallization will occur. As the concentration of strong solution increases, the objective funtion increase, but the material of OAHP can't operate under the high concentration condition.The simulation results show that recovery of the waste heat produced in the workshop section of evaporation of chlorine-alkali with absorption heat pump technology can be implemented. The OAHP using NaOH solution as working fluids is better than conventional AHP using LiBr solution as working fluids.