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CN-122010213-A - MVR evaporator system

CN122010213ACN 122010213 ACN122010213 ACN 122010213ACN-122010213-A

Abstract

The application discloses an MVR evaporator system which comprises an evaporator, a compressor, a liquid separation unit and a control unit, wherein a liquid separation cylinder conveying port is formed in the bottom of a liquid separation cylinder of the liquid separation unit and is communicated with a bottom discharge port of the evaporator through a first branch, a first bottom valve is arranged on the first branch, the liquid separation cylinder conveying port is also connected with a second branch communicated with the outside of the system, a second bottom valve is arranged on the second branch, a first density sensor is used for measuring the liquid density ρ2b of the bottom of the liquid separation cylinder in real time, and the control unit is configured to control the opening and closing states of the first bottom valve and the second bottom valve at least based on ρ2b after liquid in the liquid separation cylinder is placed and layered, so that heavy component pollutants at the lower layer and light component pollutants at the upper layer after the liquid separation and the rest and layering are discharged to the outside of the system through the second branch, and liquid at the middle layer is conveyed back to the evaporator through the first branch. The evaporator system ensures that the evaporator can still continuously evaporate under the condition of high concentration of wastewater, thereby greatly improving the treatment efficiency of the system.

Inventors

  • CHEN YUE
  • OU YUPING
  • YU HUATAO

Assignees

  • 深圳市蓝石环保科技有限公司

Dates

Publication Date
20260512
Application Date
20260302

Claims (10)

  1. 1. The MVR evaporator system is characterized by comprising an evaporator, a compressor, a liquid separating unit and a control unit, wherein, An evaporation heat exchanger is arranged in the evaporator, a tube side of the evaporation heat exchanger is communicated with an air suction port of the compressor through a gas phase outlet at the upper part of the evaporator, and an air exhaust port of the compressor is communicated with a shell side inlet of the evaporator heat exchanger; The liquid distribution unit comprises a liquid distribution cylinder and a first density sensor, wherein the bottom of the liquid distribution cylinder is provided with a liquid distribution cylinder conveying port, the liquid distribution cylinder conveying port is communicated with a bottom discharge port of the evaporator through a first branch, a first bottom valve is arranged on the first branch, the liquid distribution cylinder conveying port is also connected with a second branch communicated with the outside of the system, and a second bottom valve is arranged on the second branch; The control unit is configured to control the opening and closing states of the first bottom valve and the second bottom valve based on at least ρ 2b after standing and layering of the liquid in the liquid separating cylinder, so as to discharge heavy component pollutants located at the lower layer and light component pollutants located at the upper layer after standing and layering to the outside of the system through the second branch, and convey the liquid located at the middle layer back to the evaporator through the first branch.
  2. 2. The MVR evaporator system of claim 1, wherein the control unit is specifically configured to: When ρ 2b is larger than or equal to a second density threshold ρ d2 , controlling the first bottom valve to be in a closed state and controlling the second bottom valve to be in an open state so as to discharge heavy component pollutants at the lower layer through the second branch; In the case where the second density threshold ρ d2 ＞ρ 2b > the first density threshold ρ d1 , controlling the second bottom valve to be in a closed state, controlling the first bottom valve to be in an open state to deliver the liquid of the middle layer back to the evaporator via the first branch; And under the condition that ρ 2b is less than or equal to a first density threshold value ρ d1 , controlling the first bottom valve to be in a closed state and controlling the second bottom valve to be in an open state so as to discharge light-component pollutants on the upper layer through the second branch.
  3. 3. The MVR evaporator system of claim 2, further comprising a second density sensor mounted in an upper portion of the knock out cylinder for measuring a liquid density ρ 2a of the upper portion of the knock out cylinder and a third density sensor for measuring an initial density ρ 1 of liquid to be treated entering the system; the control unit is further configured to: Calculating a weighted value lambda= (rho 1 -ρ 3 )/(ρ 1 -ρ 2 ), wherein rho 2 is the thickest density of the liquid in the liquid separating cylinder, rho 2 =ρ 2a when the light component pollutant is more than the heavy component pollutant in the liquid separating cylinder, rho 2 =ρ 2b ;ρ 3 is the average density of the liquid in the liquid separating cylinder when the heavy component pollutant is more than the light component pollutant in the liquid separating cylinder, Ρ (h) is the variation curve of the liquid density measured by the first density sensor along with the liquid level height, and hs is the total height of the liquid in the liquid separating cylinder; ρ d1 and ρ d2 are calculated, where ρ d1 =ρ 3 +λ(ρ 2 -ρ 3 ),ρ d2 =1 when the light fraction contaminants are more than the heavy fraction contaminants in the separating cylinder, ρ d1 =1,ρ d2 =ρ 3 +λ(ρ 2 -ρ 3 when the heavy fraction contaminants are more than the light fraction contaminants in the separating cylinder.
  4. 4. The MVR evaporator system of claim 1, wherein the liquid distribution unit further comprises a first liquid level sensor for detecting a liquid level height within the liquid distribution cylinder in real time; the control unit is further configured to: Recording the total height hs n of the liquid in the liquid separating cylinder after standing and layering during the nth liquid separation, the liquid level height h1 n after the heavy component pollutants are discharged, and the liquid level h2 n after the middle layer of liquid is discharged; Calculating the volume ratio of the middle layer liquid to the total liquid in the liquid separating cylinder in the nth liquid separating process to be kn= (h 2 n -h1 n ）/hs n ; k according to successive m-times of liquid separation (n-m+1.) k (n-2), k (n-1), kn, determining the rate of change of k; Under the condition that the change rate of k is reduced to a first preset threshold value, controlling to shorten the interval time t (n+1) of next liquid separation; And under the condition that the change rate of k rises to a second preset threshold value, controlling to prolong the interval time t (n+1) of the next liquid separation.
  5. 5. The MVR evaporator system of any of claims 1 to 4, further comprising a vacuum system connected to the upper portion of the liquid distribution cylinder by a first vacuum line provided with a first suction valve; the control unit is configured to control opening of the first suction valve before opening of the first base valve to deliver the liquid in the evaporator to the liquid distribution cylinder.
  6. 6. The MVR evaporator system of claim 5, wherein the upper portion of the liquid-dividing cylinder is further connected to a first compressed gas line, and a liquid-dividing cylinder pressurization valve is disposed on the first compressed gas line; The control unit is configured to control the first suction valve to be closed and the liquid-dividing cylinder pressurizing valve to be opened after the liquid in the liquid-dividing cylinder stops boiling.
  7. 7. The MVR evaporator system of any of claims 1 to 4, wherein the liquid separation unit further comprises a liquid separation cylinder heat exchanger disposed at an outer periphery of the liquid separation cylinder, wherein an inlet of the liquid separation cylinder heat exchanger is communicated with an exhaust port of the compressor with a liquid separation cylinder heating valve disposed therebetween, and a drain port of the liquid separation cylinder heat exchanger is connected with a liquid separation cylinder drain valve.
  8. 8. The MVR evaporator system according to any of claims 1 to 4, further comprising a preheating unit including a preheating cylinder and a preheating cylinder heat exchanger provided at an outer periphery of the preheating cylinder, a preheating cylinder delivery port of the preheating cylinder being communicated with the evaporator, an inlet of the preheating cylinder heat exchanger being communicated with a shell side steam outlet provided on the shell side, a water discharge port of the preheating cylinder heat exchanger being connected with a preheating cylinder drain valve, a gas outlet of the preheating cylinder heat exchanger being communicated with a gas phase outlet provided at an upper portion of the evaporator with a return valve provided therebetween.
  9. 9. The MVR evaporator system of claim 8, wherein the preheating cylinder upper portion is connected to the vacuum system through a second vacuum line provided with a second suction valve, the preheating cylinder upper portion is further connected to a second compressed gas line provided with a preheating cylinder pressurization valve; The control unit is configured to control the second suction valve to be closed and the preheating cylinder pressurizing valve to be opened so that the air pressure in the preheating cylinder is larger than the air pressure in the evaporator when the preheating unit heats the liquid in the preheating cylinder.
  10. 10. The MVR evaporator system of claim 8, wherein a preheating cylinder heater and a second temperature sensor are also disposed within the preheating cylinder, the second temperature sensor for detecting a wastewater temperature in the preheating cylinder; the control unit is configured to control the preheating cylinder heater to be turned on in a case where the temperature of the wastewater in the preheating cylinder falls below the temperature of the wastewater in the evaporator.

Description

MVR evaporator system Technical Field The application relates to the technical field of wastewater treatment, in particular to an MVR evaporator system comprising a liquid separation unit. Background The evaporator is a common chemical equipment and is widely used in the fields of chemical industry, environmental protection, pharmacy, food, textile, energy and the like. The evaporator generally utilizes the difference of boiling points of water and other solutes in the solution, and the water is boiled and gasified by heating and escapes from the solution, so that the purposes of separating the water from the solutes, concentrating the solution and the like are realized. In recent years, evaporators such as mechanical vapor recompression (MECHANICAL VAPOR RECOMPRESSION, MVR) evaporators are often used for wastewater treatment, especially for high-pollution, high-concentration industrial wastewater treatment such as electroplating wastewater, organic wastewater, oily wastewater, and the like. It has the advantages of wide adaptability, short process chain, high automation degree, etc. However, as the evaporator processes wastewater, the concentration of wastewater in the evaporator continues to increase as evaporation proceeds. When the concentration reaches a certain level, the water content of the wastewater in the evaporator is reduced, the pollution is enhanced, or factors such as salt precipitation, crystallization and the like which are unfavorable for continuous evaporation are caused, so that the evaporator has to interrupt the evaporation process and discharge the concentrated solution. That is, the evaporation time of the conventional evaporator is limited, and it is difficult to continuously perform evaporation treatment on wastewater under the condition of high concentration, which affects the treatment efficiency. Disclosure of Invention It is an object of the present application to provide an MVR evaporator system comprising a liquid separation unit which enables on-line separation and discharge of concentrate from the evaporator by the liquid separation unit, so that the evaporator can continue to evaporate without interruption at high wastewater concentrations, greatly improving the processing efficiency of the system. The application provides an MVR evaporator system, which comprises an evaporator, a compressor, a liquid separating unit and a control unit, wherein an evaporation heat exchanger is arranged in the evaporator, a tube side of the evaporation heat exchanger is communicated with an air suction port of the compressor through a gas phase outlet at the upper part of the evaporator, an air outlet of the compressor is communicated with a shell side inlet of the evaporator heat exchanger, the liquid separating unit comprises a liquid separating cylinder and a first density sensor, a liquid separating cylinder conveying port is arranged at the bottom of the liquid separating cylinder, the liquid separating cylinder conveying port is communicated with a bottom discharge port of the evaporator through a first branch, a first bottom valve is arranged on the first branch, the liquid separating cylinder conveying port is also connected with a second branch communicated with the outside of the system, a second bottom valve is arranged on the second branch, the first density sensor is arranged at the bottom of the liquid separating cylinder and is used for measuring liquid density rho 2b at the bottom of the liquid separating cylinder in real time, the control unit is configured to open and close liquid in the liquid separating cylinder to be layered, after the liquid separating cylinder is kept still 2b, the liquid is at least kept still in a layer, and the liquid is separated from the second bottom layer through the second branch and the second bottom valve is arranged on the second branch, the second bottom valve is in a layer through the second branch, and the layer is placed on the second bottom layer and the second bottom valve is in a state of the layer. In one possible implementation, the control unit is specifically configured to: When ρ 2b is larger than or equal to a second density threshold ρ d2, controlling the first bottom valve to be in a closed state and controlling the second bottom valve to be in an open state so as to discharge heavy component pollutants at the lower layer through the second branch; In the case where the second density threshold ρ d2＞ρ2b > the first density threshold ρ d1, controlling the second bottom valve to be in a closed state, controlling the first bottom valve to be in an open state to deliver the liquid of the middle layer back to the evaporator via the first branch; And under the condition that ρ 2b is less than or equal to a first density threshold value ρ d1, controlling the first bottom valve to be in a closed state and controlling the second bottom valve to be in an open state so as to discharge light-component pollutants on the upper layer throu