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CN-121990646-A - Integrated device and integrated method for single-stage membrane distillation and vacuum compression

CN121990646ACN 121990646 ACN121990646 ACN 121990646ACN-121990646-A

Abstract

The invention discloses an integrated device and an integrated method for single-stage membrane distillation and vacuum compression, which relate to the field of gas field water treatment, wherein the integrated device comprises a membrane distillation unit, and the integrated device has the function of allowing part of gas field water to pass through a membrane and be converted into water vapor to be transmitted to the downstream of the membrane; the vacuum compression unit is connected with the membrane distillation unit and has the functions of compressing the water vapor at the downstream of the membrane to normal pressure and improving the temperature and enthalpy value of the water vapor, and the heat exchange unit is simultaneously connected with the membrane distillation unit and the vacuum compression unit and is used for exchanging heat between the water vapor after being heated by the vacuum compression unit and the gas field water before entering the membrane distillation unit. According to the invention, the vacuum compression unit is arranged, so that the downstream of the membrane can be conveyed to the heat exchange unit to exchange heat with the gas field water entering the membrane distillation unit, thereby achieving the purposes of saving energy consumption, improving efficiency and reducing cost.

Inventors

  • GAO YUNYUN
  • TAN YAO
  • CHEN LI
  • CHEN CHANGJIE
  • DING LIN
  • HUANG RUIXUAN

Assignees

  • 中国石油天然气股份有限公司

Dates

Publication Date
20260508
Application Date
20241107

Claims (13)

  1. 1. An integrated single stage membrane distillation and vacuum compression apparatus comprising: a membrane distillation unit (4) which functions to allow a portion of the gas field water to pass through the membrane and be converted to steam for transport downstream of the membrane; The vacuum compression unit is connected with the membrane distillation unit (4) and has the functions of compressing the water vapor at the downstream of the membrane to normal pressure and improving the temperature and enthalpy of the water vapor; The heat exchange unit is connected with the membrane distillation unit (4) and the vacuum compression unit simultaneously, and is used for carrying out heat exchange on water vapor heated by the vacuum compression unit and gas field water before entering the membrane distillation unit (4); the gas field water before entering the membrane distillation unit (4) absorbs heat and enters the membrane distillation unit (4), and the water vapor after being heated by the vacuum compression unit releases heat and is converted into liquid clean water to be recovered.
  2. 2. An integrated single stage membrane distillation and vacuum compression apparatus as claimed in claim 1 wherein the vacuum compression unit comprises a vacuum compressor (5), the vacuum compressor (5) being capable of providing a vacuum compression environment for water vapour downstream of the membrane; The heat exchange unit comprises a heat exchanger (3).
  3. 3. An integrated single stage membrane distillation and vacuum compression apparatus as claimed in claim 2 wherein the vacuum compressor (5) is a single stage vacuum compressor or a vacuum compressor train.
  4. 4. -An integrated single-stage membrane distillation and vacuum compression device according to claim 2, characterized in that the inlet of the vacuum compressor (5) is connected to the outlet line of the membrane distillation unit (4) and its outlet is connected to the heat exchanger (3) line; an inlet of the membrane distillation unit (4) is connected with the heat exchanger (3) through a pipeline; The heat exchanger (3) is further connected with a circulating pump (2) through a pipeline, the circulating pump (2) is connected with a feed liquid tank (1) through a pipeline, and the circulating pump (2) is used for conveying gas field water in the feed liquid tank (1) into the heat exchanger (3) for heat absorption and then entering the membrane distillation unit (4); the membrane distillation unit (4) is also connected with a concentrate tank (7), and the concentrate tank (7) is used for collecting gas field water concentrate which is not converted into water vapor in the membrane distillation unit (4); The heat exchanger (3) is also connected with a clear liquid tank (6), and the clear liquid tank (6) is used for collecting liquid clear water converted from water vapor after heat release in the heat exchanger (3).
  5. 5. An integrated unit for single stage membrane distillation and vacuum compression according to claim 1, wherein the membrane distillation unit (4) comprises a membrane module comprising one of a flat plate, a roll, a butterfly, a hollow fiber and a plate frame structure.
  6. 6. The integrated single stage membrane distillation and vacuum compression apparatus as claimed in claim 5, wherein the membrane module comprises a filtration membrane comprising one of PVDF, PTFE and PP microporous membrane structures.
  7. 7. The integrated single stage membrane distillation and vacuum compression apparatus according to claim 6, wherein the pore size of individual micropores of said microporous structure is 0.1-1 μm.
  8. 8. An integrated unit for single-stage membrane distillation and vacuum compression according to claim 2, wherein said heat exchanger (3) is of the dividing wall type.
  9. 9. An integrated process for single stage membrane distillation and vacuum compression, carried out by an integrated device according to any one of claims 1-8, comprising the steps of: S1, collecting gas field water into a feed liquid tank, starting a circulating pump, conveying the gas field water into a heat exchanger, starting a membrane distillation unit and a vacuum compressor, and conveying water vapor subjected to vacuum compression by the vacuum compressor into the heat exchanger to exchange heat with the gas field water in the heat exchanger. S2, continuously circulating the operation of a circulating pump, a heat exchanger, a membrane distillation unit and a vacuum compressor, collecting gas field water concentrate which is not converted into water vapor in the membrane distillation unit by adopting a concentrate tank, and collecting liquid clean water converted from the water vapor after heat release in the heat exchanger by adopting a clean water tank; and S3, closing the circulating pump, the membrane distillation unit and the vacuum compressor.
  10. 10. The integrated single-stage membrane distillation and vacuum compression method according to claim 9, wherein the operation temperature of the membrane distillation unit is 40-60 ℃; The vacuum compressor is of a screw type or Roots type structure, can provide an environment below 10kPa for water vapor at the downstream of the membrane, and the temperature of the water vapor after vacuum compression is 80-120 ℃.
  11. 11. An integrated single stage membrane distillation and vacuum compression process according to claim 10 wherein after heat exchange by said heat exchanger, the temperature of the inlet of the field water into said membrane distillation unit is equal to the temperature required by said membrane distillation unit in the membrane distillation operation.
  12. 12. The integrated single-stage membrane distillation and vacuum compression method according to claim 9, wherein the gas field water passes through the membrane distillation unit once, the concentration multiple of the membrane distillation unit is 2-10, and the recovery rate of the clear liquid tank to the liquid clear water is 45% -90%.
  13. 13. The integrated single stage membrane distillation and vacuum compression process of claim 9, wherein the field water comprises one of field produced water raw brine, raw brine impurity removal sample, field produced water adsorption tail liquid and desorption liquid.

Description

Integrated device and integrated method for single-stage membrane distillation and vacuum compression Technical Field The invention relates to the field of gas field water treatment, in particular to an integrated device and an integrated method for single-stage membrane distillation and vacuum compression. Background The gas field water is a byproduct in the natural gas exploitation process, has complex composition, generally has the characteristics of high impurity component content of salts, petroleum, solid suspended particles, organic chemical agents and the like, and can cause harm to stratum and surrounding ecological environment when being directly reinjected or discharged. In addition, the gas field water has associated resources such as lithium, bromine, potassium and the like which are higher than the comprehensive evaluation grade, only the emission problem of waste water is focused in the past, and less attention is paid to the recovery of the lithium resources in the gas field water, so that the waste of the resources and the pollution to the environment are caused. The gradual increase of the national requirements for environmental protection and energy utilization leads to the gradual increase of the treatment difficulty of the gas field water, so that the development and research of new technology and new process realize the recycling treatment of the produced water of the gas field and become an important task in the production process of each oil field. The direct treatment of the gas field water usually adopts a treatment process of reinjection after flocculation sedimentation filtration or standard discharge after treatment, however, the reinjection treatment process of the produced water can face the problems of insufficient reinjection capacity of a reinjection system, limited space of the residual reinjection layer, increased approval difficulty of newly built reinjection engineering, and the like, and the treatment process of the gas field water standard discharge can face the problems of high treatment difficulty, high treatment cost and the like, and the problems often limit the effective treatment of the produced water, influence the stable and efficient development of the gas field, and waste associated resources. In order to realize recovery of associated resources, the prior art mostly adopts reverse osmosis membrane separation technology, evaporation concentration technology and the like. The reverse osmosis membrane technology is generally suitable for the concentration process of salt solution with the salt ion concentration below 10g technology -1, the requirement on the operation condition is high, the incoming material liquid pressure is required to be above 1MPa, in addition, as the reverse osmosis process is carried out, the concentration polarization of the membrane surface is more and more obvious, and the upstream liquid pressure of the membrane is required to be continuously improved to maintain the membrane flux. When the salt concentration in the solution reaches beyond 70g, -1, the required operating pressure will exceed the withstand pressure of the existing membrane modules. The reverse osmosis membrane separation technology has high requirements on the feed solution, generally requires pretreatment operations such as adsorption, microfiltration and the like, and has limited salt concentration capability. The evaporation technology is used as a common salt solution concentration technology, is suitable for the evaporation concentration process of salt solution with the salt ion concentration of more than -1 g, the fresh water production strength of the salt solution is generally -2·h-1 of 20kg liquid, the desalination rate can reach 98%, and the solution can be concentrated to a saturated state. For energy saving, multi-effect evaporation and mechanical vapor compression evaporation are generally selected, wherein the mechanical vapor compression technology realizes cascade utilization of vapor, and only electric power can be used in the later stage except for the participation of vapor in the starting stage. However, the evaporation technology has the common problems of high evaporation temperature, small mass transfer area of the evaporator, huge equipment volume, poor corrosion resistance and the like. The membrane distillation is used as a novel membrane method desalination technology, integrates respective advantages of membrane separation and evaporation technologies, and is applicable to salt ion concentration ranging from 1g as -1 to more than 200g of novel -1. In the membrane distillation process, under the action of a hydrophobic porous membrane, water in the feed liquid evaporates on the surface of the membrane to form gas, passes through the membrane pores, and finally condenses and is enriched at the downstream of the membrane. Inorganic salt ions in the feed solution are trapped upstream of the membrane, thereby achieving desalination. The membra