Autonomous vacuum-compression evaporator with multi-stage heat recovery and solar irradiation

Abstract

The invention relates to thermal power engineering and chemical technologies, in particular to installations for desalination, wastewater treatment and concentration of solutions using an open cycle heat pump. The evaporator contains a recuperative heat exchanger connected to the feed solution line, a compressor and a condenser, made in multiple sections in the form of a flat housing with a reflective bottom and a light-transmitting cover, inside which a coil evaporator is located, and the compression system is made in the form of a three-stage cascade of centrifugal turbocompressors. In this case, a vacuum in the range from 0.035 bar to 0.045 bar is maintained in the sections of the multi-section condenser, ensuring a boiling temperature of water within the range of 27–31°C, and preliminary heating of the water is carried out by solar irradiation through a light-transmitting cover and a reflective bottom of the flat casing of the condenser, Steam compression in a multi-stage turbocompressor is performed in stages, with a compression ratio of 1.82 distributed across each stage to a pressure of 0.6 bar, while simultaneously cooling the compressed steam by injecting distillate. This technical result is achieved by maintaining a compression regime as close as possible to the saturation line, thanks to the cooling of the steam by injected condensate. This allows for a reduction in specific compression work by 45–55% and an energy conversion efficiency (COP) of up to 27.7, ensuring the unit’s autonomy and reducing energy consumption to 4.69 MW with high performance.