A mechanical vapor recompression (MVR) liquid purification system, in particular an MVR water desalination system, comprising:
- a pressure-tight enclosure provided with a first end and a second end, having circular cylindrical elongated shape along a longitudinal axis A, and being-horizontally oriented during operation of the system,
- first, second and third evaporation compartments E1, E2, and E3, arranged within said enclosure along the longitudinal axis A, wherein the first evaporation compartment E1 is arranged closer to the first end of the enclosure than the second evaporation compartment E2 and the third evaporation compartment E3, wherein the third evaporation compartment E3 is arranged closer to the second end of the enclosure than the first evaporation compartment E1 and the second evaporation compartment E2, the first, second and third evaporation compartments E1, E2, and E3 are connected in series and have circular cylindrical shapes, each evaporation compartment comprises first and second planar and circular sidewalls, and each evaporation compartment is provided with a plurality of longitudinal pipes running from the first sidewall to the second sidewall, and the first and second circular sidewalls are provided with openings for said plurality of longitudinal pipes, wherein each evaporation compartment is provided with two or more spraying nozzles arranged to be supplied with inflow liquid from inflow liquid tubing, or inflow liquid is supplied to one of the first evaporation compartment E1 or the second evaporation compartment E3 through an opening, and pipes are provided to allow liquid to flow to the other compartments,
- wherein said system further comprises:
- a central tube running along the longitudinal axis A of the enclosure through centers of said first, second, and third evaporation compartments E1, E2, and E3, and configured to allow steam to flow from the second end to the first end of the enclosure,
- a compressor assembly arranged at said first end of the enclosure and at least partly within said central tube, comprising a compressor provided with compressor vane members structured to provide steam flow along the longitudinal axis, within said central tube from said second end to said first end of the enclosure, wherein the compressor assembly further comprises a motor for rotating said compressor at a variable rotational speed,
- a partial vacuum generating member arranged to generate partial vacuum in the evaporation compartments,
- wherein the first evaporation compartment E1 comprises a greater number of the plurality of longitudinal pipes than the second evaporation compartment E2, and the second evaporation compartment E2 comprises a greater number of the plurality of longitudinal pipes than third evaporation compartment E3, and wherein the longitudinal pipes for each evaporation compartment are evenly spread in a cross-section perpendicular to the longitudinal axis of the respective evaporation compartment, and the longitudinal pipes are configured to allow steam to flow from the first end to the second end of the enclosure,
- wherein each evaporation compartment is provided with an inflow liquid collecting container arranged at a bottom of each evaporation compartment and configured to collect non-vaporized inflow liquid, wherein the collecting container comprises a level sensor configured to measure a level of inflow liquid and to generate a level signal when a liquid level deviates from a predetermined liquid level interval, and
- wherein purified liquid collecting spaces are provided between the evaporation compartments for collecting purified liquid, said purified liquid collecting spaces being delimited by the first sidewall of one of the evaporation compartments and the second sidewall of another of the evaporation compartments that is adjacent to said one of the evaporation compartments, and an inner surface of the enclosure, and wherein outflow of purified liquid from the liquid collecting spaces is enabled by tubes and valves,
- wherein the system further comprises a control unit configured to control operation of the system according to designated performance, by performing a control procedure adapted to:
- generate said partial vacuum in the evaporation compartments,
- control said motor to operate said compressor at a rotational speed such that temperature of the steam is increased when the steam passes said compressor to achieve desired recycling of specific heat associated to vaporization, and
- control a plurality of valves and pumps provided to supply the system with the inflow liquid and to receive purified liquid from the system.