A staged low-temperature evaporation and concentrated lye device based on heat pump cycle

Abstract

The invention discloses a staged low-temperature alkali liquor evaporating and concentrating device based on heat pump cycle. The device comprises a low-concentration alkali liquor evaporator, a high-concentration alkali liquor evaporator, a refrigerant storage tank, a vacuum pump, a first thermal expansion valve, a second thermal expansion valve, a high-pressure dry-type refrigerant evaporator, a lower-pressure dry-type refrigerant evaporator, a first coil pipe, a first fan, a second coil pipe, a second fan, a refrigeration compressor, a Roots blower, a condensate water tank, a condensate water pump, a concentrated alkali liquor pump, a liquid level control valve, a liquid level control switch, a valve and the like. The low-concentration and high-concentration alkali liquor evaporators adopt vertical shell-and-tube falling film structures, the condensation temperature of water vapor outside tubes is adjusted through adjustment of evaporation temperatures of the low-pressure and high-pressure dry-type evaporators respectively, and pressure in the low-concentration and high-concentration alkali liquor evaporators is controlled, so that the alkali liquor evaporation temperature is adjusted; a method of dual control by the aid of an alkali-liquor-side flow valve and an inverter compressor is adopted to ensure matching of heat absorption of the alkali liquor evaporators with heat release of refrigerants.

Description

technical field [0001] The invention relates to a process for concentrating lye by using a heat pump, and belongs to the technical field of chemical separation and energy saving and emission reduction. A heat pump energy-saving technology involving the dual-action cycle of refrigerant heating and cooling, refrigerant two-stage compression, solution fractional concentration and solvent condensation coupling. Background technique [0002] Energy issues and environmental issues have become increasingly prominent in industrial production, which puts forward higher requirements for energy-saving technologies. Heat pump technology is an efficient, environmentally friendly energy-saving technology that can be widely used in industrial production fields such as chemical industry, low-grade heat energy utilization, seawater desalination, and sewage treatment. The waste liquid of printing and dyeing and paper mills contains NaOH solution with low concentration. The usual practice is ...

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Problems solved by technology

Therefore, as the evaporation process proceeds, the concentration of the lye increases, and the temperature difference between the lye and the refrigerant vapor gradually decreases, which will slow down the progress of evaporating and concentrating the lye, and in severe cases will cause the evaporation to stop

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