Automatic control method and system for counter-flow triple-effect evaporator

Abstract

The invention discloses an automatic control method and system for a reverse-flow triple-effect evaporator. The automatic control method comprises the steps that a starting switch is turned on; raw materials are controlled to be input into the first-effect evaporator, the second-effect evaporator and the third-effect evaporator; the controller activates the reflux valve and starts the liquid ring vacuum unit; raw materials in the triple-effect evaporator flow into the single-effect evaporator through a reflux valve in a minimum reflux state, and after the vacuum degree reaches a preset value, steam is controlled to be input into the triple-effect evaporator; the first-effect separator, the second-effect separator and the third-effect separator respectively receive and separate heat exchange raw materials obtained after heat exchange between the raw materials in the corresponding evaporators and steam; after the concentration of the raw materials in the triple-effect separator meets the requirement, liquid separated by the triple-effect separator is conveyed out; turning off the switch; and the controller sequentially turns off the steam inlet valve and the feeding valve, sequentially forbids the corresponding separators from outputting liquid and turns off the liquid ring vacuum unit. Compared with the prior art, one-key starting and stopping can be achieved, and full-process automatic control is achieved.

Description

Technical Field

[0001] The invention relates to an automatic control method and system for a countercurrent triple-effect evaporator, belonging to the technical field of evaporator application. Background Art

[0002] The countercurrent triple-effect evaporator is suitable for the evaporation and concentration of non-heat-sensitive materials with large processing volume and high discharge concentration requirements, and is used in the evaporation and concentration process of caustic soda. The countercurrent triple-effect evaporator is composed of three evaporators connected in series, a condenser, a vacuum system, and a separation system. In the countercurrent triple-effect evaporator, heating steam is introduced into the third-effect evaporator to heat the material to be concentrated. After the material is heated, secondary steam is generated in the third-effect negative pressure separation chamber and introduced into the second-effect evaporator as heating steam. The higher negative pressure of the second effect causes the material to evaporate in the second-effect negative pressure separation chamber at a lower temperature than the first effect. The secondary steam generated is then introduced into the first-effect evaporator, and the material is evaporated in the first-effect separator at a higher negative pressure than the second effect, thereby achieving the concentration of the alkali solution.

[0003] At present, the countercurrent triple-effect evaporator is used in the caustic soda concentration process, but the degree of automation is low, and the start-up and shutdown process of the countercurrent triple-effect evaporation system is relatively complicated, and each evaporation unit affects each other and is closely linked. At present, manual adjustment is required from the start of production to normal production, which has a large workload, large energy waste during the adjustment process, and certain safety risks.

[0004] In view of this, it is necessary to improve the existing countercurrent triple-effect evaporator system to solve the above problems. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides an automatic control method for a countercurrent triple-effect evaporator, which can realize full process automation without manual adjustment.

[0006] The technical solution of the present invention is:

[0007] An automatic control method for a countercurrent triple-effect evaporator, comprising:

[0008] Turn on the start switch;

[0009] The controller activates the feed valve to control the raw materials to be sequentially fed into the first-effect evaporator, the second-effect evaporator and the third-effect evaporator;

[0010] The controller activates the reflux valve and starts the liquid ring vacuum unit to adjust the vacuum degree of the first effect evaporator, the second effect evaporator and the third effect evaporator;

[0011] After the raw materials in the three-effect evaporator flow into the one-effect evaporator through the reflux valve in a minimum reflux state and the vacuum degree reaches a preset value, the controller activates the steam inlet valve to control the steam input into the three-effect evaporator;

[0012] The first-effect separator, the second-effect separator and the third-effect separator respectively receive and separate the heat exchange raw materials obtained after the raw materials in the corresponding evaporator and the steam are heat exchanged, the steam in the second-effect evaporator comes from the third-effect separator, and the steam in the first-effect evaporator comes from the second-effect separator;

[0013] After the raw material concentration in the three-effect separator meets the requirement, the controller closes the reflux valve and activates the water outlet valve, and sends out the liquid obtained after the three-effect separator separates the heat exchange raw material;

[0014] Turn off the switch;

[0015] The controller shuts off the steam inlet valve and the feed valve in sequence, and when the liquid level in the separator approaches zero, it prohibits the corresponding separators from outputting liquid in sequence, and then shuts off the liquid ring vacuum unit. In this way, the countercurrent triple-effect evaporation system can be automatically controlled to start and stop with one button, reducing manual intervention, achieving safety, reliability, and reducing manpower and increasing efficiency.

[0016] As a further improvement of the present invention, the three-effect separator receives and separates the heat exchange raw material obtained by heat exchange between the raw material in the three-effect evaporator and the steam, inputs the separated first steam into the second-effect evaporator to exchange heat with the raw material in the second-effect evaporator, and inputs the separated first liquid into the first-effect evaporator as raw material; the two-effect separator receives and separates the heat exchange raw material obtained by heat exchange between the second-effect evaporator and the first steam, inputs the separated second steam into the first-effect evaporator to exchange heat with the raw material in the first-effect evaporator, and inputs the separated second liquid into the third evaporator as raw material.

[0017] As a further improvement of the present invention, the first-effect separator receives and separates the heat exchange raw material obtained by the heat exchange between the first-effect evaporator and the second steam, and inputs the separated third steam into the condensing device to form condensed water, and continues to input the separated third liquid into the second evaporator as raw material.

[0018] As a further improvement of the present invention, the steam-water separator receives and delivers the condensed water through the condensing device, and the controller adjusts the operating frequency of the liquid ring vacuum unit according to the negative pressure of the steam-water separator. In this way, the vacuum degree of each effect can be automatically adjusted, the vacuum degree can be balanced, and the system can be ensured to operate in the optimal state, improve production efficiency, and reduce energy consumption.

[0019] As a further improvement of the present invention, after the liquid ring vacuum unit is shut down, when the liquid level in the steam-water separator approaches zero, the external delivery of the condensed water is stopped.

[0020] As a further improvement of the present invention, the monitoring module monitors the liquid level of the first-effect separator, the second-effect separator and the third-effect separator, and sends a monitoring signal. The controller receives the monitoring signal and reduces the flow rate of the liquid separated by the corresponding separator output when the liquid level of one or more of the first-effect separator, the second-effect separator and the third-effect separator decreases. In this way, the liquid level of each effect can be automatically adjusted, the balance control of the liquid level can be achieved, and the system can be guaranteed to operate in the optimal state, improve production efficiency and reduce energy consumption.

[0021] As a further improvement of the present invention, the monitoring module monitors the temperature of the steam outlet of the first effect separator, the second effect separator and the third effect separator, and the controller receives the monitoring signal and reduces the amount of steam entering the corresponding evaporator when the temperature of one or more steam outlets of the first effect separator, the second effect separator and the third effect separator increases. In this way, the temperature of each effect can be automatically adjusted, the temperature can be balanced, and the system can be ensured to operate in the optimal state, improve production efficiency and reduce energy consumption.

[0022] As a further improvement of the present invention, the controller activates the feed valve, and controls the raw materials to be sequentially fed into the first-effect evaporator, the second-effect evaporator and the third-effect evaporator, including: the controller activates the feed valve, controls the raw materials to be fed into the first-effect evaporator and then flow into the first-effect separator after passing through the first-effect evaporator, and after reaching the preset liquid level of the first-effect separator, flows into and enters the second-effect separator after passing through the second-effect evaporator, and after reaching the preset liquid level of the second-effect separator, flows into and enters the third-effect separator after passing through the third-effect evaporator, until the preset liquid level of the third-effect separator is reached.

[0023] As a further improvement of the present invention, when the liquid level in the separator approaches zero, the corresponding separators are sequentially prohibited from outputting liquid, including the following order: after the liquid level in the three-effect separator is emptied, the controller prohibits the three-effect separator from outputting liquid; after the liquid level in the two-effect separator is emptied, the controller prohibits the two-effect separator from outputting liquid; after the liquid level in the one-effect separator is emptied, the controller prohibits the one-effect separator from outputting liquid.

[0024] The present invention also provides an automatic control system for a countercurrent triple-effect evaporator, which applies the aforementioned automatic control method.

[0025] The beneficial technical effect of the present invention is: an automatic control method for a countercurrent triple-effect evaporator of the present invention activates or shuts down various valves under specific conditions through a controller, thereby realizing fully automatic transportation and evaporation processing between a first-effect evaporator, a second-effect evaporator and a third-effect evaporator, that is, fully automated processing, avoiding manual operation errors, saving labor costs and energy costs, and effectively improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a flowchart of an automatic control method for a countercurrent triple-effect evaporator in accordance with a preferred embodiment of the present invention.

[0027] Figure 2 It is an application Figure 1 A partial structural schematic diagram of a system for an automatic control method for a countercurrent triple-effect evaporator.

[0028] Figure 3 It is an application Figure 1 Another part of the structural diagram of the system of the automatic control method of the countercurrent triple-effect evaporator. DETAILED DESCRIPTION

[0029] In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0030] See also Figures 1 to 3 As shown, the present invention provides an automatic control system 100 for a countercurrent triple-effect evaporator, comprising a controller 1 and a raw material tank 2, a feed heater 5, a first-effect evaporator 18, a second-effect evaporator 25, a third-effect evaporator 32 and a steam cylinder 37 that are interconnected. The controller 1 controls the raw material in the raw material tank 2 to enter the first-effect evaporator 18, the second-effect evaporator 25 and the third-effect evaporator 32 in sequence after passing through the feed heater 5, and then the steam is input into the third-effect evaporator 32 through the steam cylinder 37 to heat the raw material in the third-effect evaporator 32 and start the reaction of the entire system. The preheating of the raw material by the feed heater 5 shortens the heat exchange process between the steam and the raw material, greatly reducing the cost. In this embodiment, the controller 1 is preferably a control cabinet, and the raw material is preferably alkali solution.

[0031] The automatic control system 100 further includes a raw material delivery pump 3 and a feed valve 4 connected to the raw material tank 2 . The raw material in the raw material tank 2 is pumped by the raw material delivery pump 3 , and the flow rate of the raw material is controlled by the feed valve 4 .

[0032] The feed heater 5 is also provided with a heating inlet regulating valve 6, through which the amount of heating medium is adjusted to adjust the amplitude of the raw material preheating. Secondly, the first-effect evaporator inlet temperature remote transmission 7 is set at the inlet of the first-effect evaporator 18 to monitor the temperature of the raw material entering the first-effect evaporator 18. The heating inlet regulating valve 6 and the first-effect evaporator inlet temperature remote transmission 7 are cascade controlled. When the temperature of the first-effect evaporator inlet temperature remote transmission 7 decreases, the opening of the heating inlet regulating valve 6 increases. Generally speaking, the raw material temperature monitored by the first-effect evaporator inlet temperature remote transmission 7 is between 70°C and 85°C. The higher the raw material temperature monitored by the first-effect evaporator inlet temperature remote transmission 7, the shorter the heat exchange process between the steam and the raw material.

[0033] A steam inlet valve 35 is provided between the triple-effect evaporator 32 and the steam sub-cylinder 37 . The steam inlet valve 35 is controlled by the controller 1 to be activated or shut down by the controller 1 .

[0034] The first-effect evaporator 18, the second-effect evaporator 25 and the third-effect evaporator 32 are respectively provided with a first-effect separator 16, a second-effect separator 23 and a third-effect separator 30. The first-effect separator 16 is connected between the first-effect evaporator 18 and the second-effect evaporator 25, and the second-effect separator 23 is connected between the second-effect evaporator 25 and the third-effect evaporator 32. When the raw material is input and flows into the first-effect separator 16 after passing through the first-effect evaporator 18, after reaching the preset liquid level of the first-effect separator 16, it flows into and passes through the second-effect evaporator 25 and enters the second-effect separator 23, and after reaching the preset liquid level of the second-effect separator 23, it flows into and passes through the third-effect evaporator 32 and enters the third-effect separator 30, until the preset liquid level of the third-effect separator 30 is reached.

[0035] Preferably, a first-effect separator external delivery pump 21 and a first-effect separator external delivery regulating valve group 22 are provided between the first-effect separator 16 and the second-effect evaporator 25, and the first-effect separator external delivery pump 21 and the first-effect separator external delivery regulating valve group 22 are used to adjust the amount of raw materials input from the first-effect separator 16 to the second-effect evaporator 25. A second-effect separator external delivery pump 28 and a second-effect separator external delivery regulating valve group 29 are provided between the second-effect separator 23 and the third-effect evaporator 32, and the second-effect separator external delivery pump 28 and the second-effect separator external delivery regulating valve group 29 are used to adjust the amount of raw materials input from the second-effect separator 23 to the third-effect evaporator 32.

[0036] In this embodiment, the separator is used to separate the raw material that has been heat exchanged with the steam to obtain separated steam and liquid. Therefore, the steam input into the triple-effect evaporator 32 through the steam cylinder 37 is only used for heat exchange with the raw material in the triple-effect evaporator 32, and is discharged from the triple-effect evaporator 32 after the heat exchange is completed, and will not enter the second-effect evaporator 25 or the first-effect evaporator 18. The steam in the second-effect evaporator 25 comes from the steam separated by the triple-effect separator 30, and the steam in the first-effect evaporator 18 comes from the steam separated by the second-effect separator 23. In contrast, the liquid separated by the first-effect separator 16 is input into the second-effect evaporator 25 as the raw material of the second-effect evaporator 25, and the liquid separated by the second-effect separator 23 is input into the third-effect evaporator 32 as the raw material of the third-effect evaporator 32. After the concentration of the raw material in the third-effect separator 30 reaches the requirement, the raw material separated by the third-effect separator 30 is externally delivered by the third-effect separator external delivery pump 36 for use by external equipment. Preferably, the flow rate of the raw material is controlled by the water outlet valve 33.

[0037] Preferably, a reflux valve 38 is also provided on the liquid delivery path separated by the triple effect separator 30, and the reflux valve 38 corresponds to the water outlet valve 33, and both are controlled by the controller 1 to selectively activate one of them. When the reflux valve 38 is activated, the water outlet valve 33 is closed, and the liquid flowing out of the triple effect separator 30 flows back to the first effect evaporator 18 through the reflux valve 38, and serves as the raw material of the first effect evaporator 18. In this way, a cycle is formed until the concentration of the liquid separated by the triple effect separator 30 meets the requirements. Therefore, a concentration monitor is provided at the water outlet of the triple effect separator 30, which is used to monitor the concentration of the liquid output by the triple effect separator 30 in real time and send a concentration monitoring signal. The controller 1 selectively activates the reflux valve 38 or the triple effect separator delivery pump 36 according to the concentration detection signal.

[0038] In this embodiment, a first-effect separator liquid level remote transmitter 17 is provided on the liquid delivery path of the first-effect separator 16, a second-effect separator liquid level remote transmitter 24 is provided on the liquid delivery path of the second-effect separator 23, and a third-effect separator liquid level remote transmitter 31 is provided on the liquid delivery path of the third-effect separator 30. The first-effect separator liquid level remote transmitter 17, the second-effect separator liquid level remote transmitter 24 and the third-effect separator liquid level remote transmitter 31 are respectively used to monitor the flow of the liquid output by the first-effect separator 16, the second-effect separator 23 and the third-effect separator 30, and send corresponding flow monitoring signals. The controller 1 receives the flow monitoring signal and controls the flow of the first-effect separator external delivery regulating valve group 22, the second-effect separator external delivery regulating valve group 29 and the water outlet valve 33 according to the flow monitoring signal. Preferably, the flow rate monitored by the liquid level remote transmitter is proportional to the flow rate controlled by the separator external delivery regulating valve group.

[0039] That is, when the liquid level of the three-effect separator liquid level remote transmission 31 decreases, the opening of the water outlet valve 33 decreases. When the liquid level of the two-effect separator liquid level remote transmission 24 decreases, the opening of the two-effect separator external delivery regulating valve group 29 decreases. When the liquid level of the one-effect separator liquid level remote transmission 17 decreases, the opening of the one-effect separator external delivery regulating valve group 22 decreases.

[0040] In this embodiment, the preferred liquid level range of the first-effect separator 16, the second-effect separator 23 and the third-effect separator 30 is between 25% and 45%. When the liquid level floats within this range, the opening of the first-effect separator external regulating valve group 22 is adjusted accordingly.

[0041] The bottom outlet pipeline of the triple-effect separator 30 is provided with a triple-effect separator outlet temperature remote transmitter 34, and the triple-effect separator outlet temperature remote transmitter 34 is cascade-controlled with the steam inlet valve 35. When the temperature of the triple-effect separator outlet temperature remote transmitter 34 increases, the opening of the steam inlet valve 35 decreases.

[0042] The bottom outlet pipeline of the second-effect separator 23 is provided with a second-effect separator outlet temperature remote transmitter 27, and the outlet pipeline of the steam separated by the triple-effect separator 30 is provided with a triple-effect separator secondary steam regulating valve group 26, and the second-effect separator outlet temperature remote transmitter 27 and the triple-effect separator secondary steam regulating valve 26 are cascade controlled. When the temperature of the second-effect separator outlet temperature remote transmitter 27 increases, the opening of the triple-effect separator secondary steam regulating valve 26 decreases.

[0043] The bottom outlet pipeline of the first-effect separator 16 is provided with a first-effect separator outlet temperature remote transmitter 20, and the outlet pipeline of the steam separated by the second-effect separator 23 is provided with a second-effect separator secondary steam regulating valve group 19, and the first-effect separator outlet temperature remote transmitter 20 is cascade controlled with the second-effect separator secondary steam regulating valve 19. When the temperature of the first-effect separator outlet temperature remote transmitter 20 increases, the opening degree of the second-effect separator secondary steam regulating valve 19 decreases.

[0044] Therefore, the temperature of the liquid output from the separator monitored by the separator outlet temperature remote transmission is inversely proportional to the steam temperature received by the separator. In order to ensure the smooth operation of the automatic control system 100, the temperature range monitored by the triple-effect separator outlet temperature remote transmission 34 is usually 70°C-80°C, the temperature range monitored by the double-effect separator outlet temperature remote transmission 27 is usually 100°C-110°C, and the temperature range monitored by the single-effect separator outlet temperature remote transmission 20 is usually 135°C-155°C.

[0045] The automatic control system 100 also includes a liquid ring vacuum unit drain tank 8, a liquid ring vacuum unit 9, a steam-water separator 12 and a cooling device 15 that are interconnected. The cooling device 15 is used to receive the steam separated by the first effect separator 16 and cool it to form condensed water. The steam-water separator 12 is used to receive the condensed water in the cooling device 15 and send it out. The liquid ring vacuum unit 9 is used to suck the gas in the first effect separator 16, the first effect evaporator 18, the second effect separator 23, the second effect evaporator 25, the triple effect separator 30 and the triple effect evaporator 32 to adjust the vacuum degree in the first effect separator 16, the first effect evaporator 18, the second effect separator 23, the second effect evaporator 25, the triple effect separator 30 and the triple effect evaporator 32. Generally speaking, the closer to the liquid ring vacuum unit 9, the greater the vacuum in the corresponding equipment.

[0046] The steam-water separator 12 is also externally connected to a condensate delivery pump outlet regulating valve group 10 and a condensate delivery pump 11, and the condensate delivery pump outlet regulating valve group 10 and the condensate delivery pump 11 are used to deliver and regulate the flow of the condensate.

[0047] The steam-water separator 12 is also provided with a steam-water separator liquid level remote transmission 13 and a steam-water separator negative pressure remote transmission 14. The steam-water separator liquid level remote transmission 13 and the condensate delivery pump outlet regulating valve 10 are in cascade control. When the liquid level of the steam-water separator liquid level remote transmission 13 decreases, the opening of the condensate delivery pump outlet regulating valve 10 decreases. The liquid ring vacuum unit 9 is variable frequency controlled, and the steam-water separator negative pressure remote transmission 14 and the liquid ring vacuum unit 9 are in cascade control. When the negative pressure of the steam-water separator negative pressure remote transmission 14 decreases, the speed of the liquid ring vacuum unit 9 increases to increase the vacuuming force.

[0048] In this embodiment, all remote transmission signals enter the controller 1 as 4-20mA analog signals, and the controller outputs 4-20mA analog signals to control the opening of the regulating valve and the variable frequency regulation of the pump. In addition, all the external pump outlet regulating valve groups can also be replaced by the variable frequency regulation of the pump.

[0049] The working process of the present invention is as follows: the automatic control program is started, the status of each regulating valve and machine pump is checked, and after the starting conditions are met, the raw material delivery pump 3 and the feed valve 4 are started in sequence, and after the first-effect separator 16 reaches the set liquid level, the first-effect separator external delivery pump 21 and the first-effect separator external delivery regulating valve group 22 are automatically started, and after the second-effect separator 23 reaches the set liquid level, the second-effect separator external delivery pump 28 and the second-effect separator external delivery regulating valve group 29 are automatically started, and after the third-effect separator 30 reaches the set liquid level, the controller 1 controls the water outlet valve 33 to close and opens the reflux valve 38 to ensure that the alkali solution is internally circulated under the minimum reflux state.

[0050] After opening the reflux valve 38, the controller 1 controls the liquid ring vacuum unit 9 to start. After the vacuum degree reaches the set value, the steam inlet valve 35 is opened. When the liquid level of the steam-water separator 12 reaches the specified value, the condensate delivery pump 11 is automatically started. At the same time, the controller 1 controls the opening of the feed valve 4, the first-effect separator delivery regulating valve group 22, the second-effect separator delivery regulating valve group 29 and the reflux valve 38, and the system enters steady-state regulation. At this time, the vacuum degree, temperature, liquid level, etc. of each effect meet the process requirements. After the alkali solution concentration in the triple-effect separator 30 is qualified, the water outlet valve 33 is opened to deliver the alkali solution, and the control is transferred to the normal production procedure.

[0051] Under the parking automatic control program, the steam inlet valve 35 is sequentially controlled to be closed, the raw material delivery pump 3 is prohibited from running, and the feed valve 4 is closed. After the liquid level of the three-effect separator 30 is evacuated, the three-effect separator delivery pump 36 is shut down; after the liquid level of the two-effect separator 23 is evacuated, the two-effect separator delivery pump 28 is shut down; after the liquid level of the first-effect separator 16 is evacuated, the first-effect separator delivery pump 21 is shut down, and the liquid ring vacuum unit 9 is shut down at the same time; after the steam-water separator 12 is evacuated, the condensate delivery pump 11 is shut down.

[0052] The present invention also provides an automatic control method for a countercurrent triple-effect evaporator, comprising:

[0053] Turn on the start switch;

[0054] The controller 1 activates the feed valve 4 to control the raw materials to be sequentially fed into the first-effect evaporator 18, the second-effect evaporator 25 and the third-effect evaporator 32;

[0055] The controller 1 activates the reflux valve 38 and starts the liquid ring vacuum unit 9 to adjust the vacuum degree of the first effect evaporator 18, the second effect evaporator 25 and the third effect evaporator 32;

[0056] After the raw materials in the three-effect evaporator 32 flow into the first-effect evaporator 18 through the reflux valve 38 in a minimum reflux state and the vacuum degree reaches a preset value, the controller 1 activates the steam inlet valve 35 to control the steam input into the three-effect evaporator 18;

[0057] The first-effect separator 16, the second-effect separator 23 and the third-effect separator 30 respectively receive and separate the heat exchange raw materials obtained after the raw materials in the corresponding evaporators are heat-exchanged with the steam. The steam in the second-effect evaporator 25 comes from the third-effect separator 30, and the steam in the first-effect evaporator 18 comes from the second-effect separator 23.

[0058] After the raw material concentration in the triple-effect separator 30 meets the requirement, the controller 1 closes the reflux valve 38 and activates the water outlet valve 33, and sends the liquid obtained after the triple-effect separator 30 separates the heat exchange raw material.

[0059] Turn off the switch;

[0060] The controller 1 sequentially shuts off the steam inlet valve 35 and the feed valve 4, and when the liquid level in the separator approaches zero, sequentially prohibits the corresponding separators from outputting liquid, and then shuts off the liquid ring vacuum unit 9. After shutting down the liquid ring vacuum unit 9, when the liquid level in the steam-water separator 12 approaches zero, the delivery of the condensed water is stopped.

[0061] The three-effect separator 30 receives and separates the heat exchange raw material obtained by heat exchange between the raw material in the three-effect evaporator 32 and the steam, inputs the separated first steam into the second-effect evaporator 25 to exchange heat with the raw material in the second-effect evaporator 25, and inputs the separated first liquid into the first-effect evaporator 18 as raw material; the second-effect separator 23 receives and separates the heat exchange raw material obtained by heat exchange between the second-effect evaporator 25 and the first steam, inputs the separated second steam into the first-effect evaporator 18 to exchange heat with the raw material in the first-effect evaporator 18, and inputs the separated second liquid into the third evaporator 32 as raw material.

[0062] The first-effect separator 16 receives and separates the heat exchange raw material obtained by heat exchange between the first-effect evaporator 18 and the second steam, and inputs the separated third steam into the condensing device 15 to form condensed water, and further inputs the separated third liquid into the second evaporator 25 as raw material.

[0063] The steam-water separator 12 receives and delivers the condensed water through the condensing device 15 , and the controller 1 adjusts the operating frequency of the liquid ring vacuum unit 9 according to the negative pressure of the steam-water separator 12 .

[0064] The monitoring module monitors the liquid levels of the first-effect separator 16, the second-effect separator 23 and the third-effect separator 30, and sends a monitoring signal. The controller 1 receives the monitoring signal and reduces the flow rate of the liquid separated by the corresponding separator output when the liquid level of one or more of the first-effect separator 16, the second-effect separator 23 and the third-effect separator 30 decreases.

[0065] The monitoring module monitors the temperature of the steam outlet of the first-effect separator 16, the second-effect separator 23 and the third-effect separator 30. The controller 1 receives the monitoring signal and reduces the amount of steam entering the corresponding evaporator when the temperature of one or more steam outlets of the first-effect separator 16, the second-effect separator 23 and the third-effect separator 30 increases.

[0066] In this embodiment, the monitoring module synchronously monitors the liquid levels of the first-effect separator 16, the second-effect separator 23 and the third-effect separator 30 and the temperatures of the steam outlets of the first-effect separator 16, the second-effect separator 23 and the third-effect separator 30 to automatically balance the flow rate of the liquid obtained by the separation output entering the separator and the steam volume of the corresponding evaporator.

[0067] After the start switch is pressed, the controller 1 activates the feed valve 4, controls the input of the raw material, and flows into the first-effect separator 16 after passing through the first-effect evaporator 18. After reaching the preset liquid level of the first-effect separator 16, the raw material flows into and passes through the second-effect evaporator 25 and then enters the second-effect separator 23. After reaching the preset liquid level of the second-effect separator 23, the raw material flows into and passes through the third-effect evaporator 32 and then enters the third-effect separator 30, until the preset liquid level of the third-effect separator 30 is reached.

[0068] When the liquid level in the separator approaches zero, the corresponding separators are prohibited from outputting liquid in sequence, including the following order: after the liquid level in the three-effect separator 30 is emptied, the controller 1 prohibits the three-effect separator 30 from outputting liquid; after the liquid level in the two-effect separator 23 is emptied, the controller 1 prohibits the two-effect separator 23 from outputting liquid; after the liquid level in the one-effect separator 16 is emptied, the controller 1 prohibits the one-effect separator 16 from outputting liquid. Therefore, the order of shutting down the external pumps is to shut down the three-effect separator external pump 36, shut down the two-effect separator external pump 28, and shut down the one-effect separator external pump 21.

[0069] In summary, the automatic control method and system of a countercurrent triple-effect evaporator of the present invention activates or shuts down various valves under specific conditions through the controller 1, thereby realizing fully automatic transportation and evaporation processing between the first-effect evaporator 18, the second-effect evaporator 25 and the triple-effect evaporator 32, that is, fully automated processing, avoiding manual operation errors, saving labor costs and energy costs, and effectively improving production efficiency.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the technical principles of the present invention, and these improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An automatic control method for a countercurrent triple-effect evaporator, characterized in that: include: Turn on the start switch; The controller activates the feed valve to control the raw materials to be sequentially fed into the first-effect evaporator, the second-effect evaporator and the third-effect evaporator; The controller activates the reflux valve and starts the liquid ring vacuum unit to adjust the vacuum degree of the first effect evaporator, the second effect evaporator and the third effect evaporator; After the raw materials in the three-effect evaporator flow into the one-effect evaporator through the reflux valve in a minimum reflux state and the vacuum degree reaches a preset value, the controller activates the steam inlet valve to control the steam input into the three-effect evaporator; The first-effect separator, the second-effect separator and the third-effect separator respectively receive and separate the heat exchange raw materials obtained after the raw materials in the corresponding evaporator and the steam are heat exchanged, the steam in the second-effect evaporator comes from the third-effect separator, and the steam in the first-effect evaporator comes from the second-effect separator; After the raw material concentration in the three-effect separator meets the requirement, the controller closes the reflux valve and activates the water outlet valve, and sends out the liquid obtained after the three-effect separator separates the heat exchange raw material; Turn off the switch; The controller shuts off the steam inlet valve and the feed valve in sequence, and when the liquid level in the separator approaches zero, prohibits the corresponding separators from outputting liquid in sequence, and then shuts off the liquid ring vacuum unit.

2. The automatic control method of a countercurrent triple-effect evaporator according to claim 1, characterized in that: The three-effect separator receives and separates the heat exchange raw material obtained by heat exchange between the raw material in the three-effect evaporator and the steam, inputs the separated first steam into the two-effect evaporator to exchange heat with the raw material in the two-effect evaporator, and inputs the separated first liquid into the one-effect evaporator as raw material; the two-effect separator receives and separates the heat exchange raw material obtained by heat exchange between the two-effect evaporator and the first steam, inputs the separated second steam into the one-effect evaporator to exchange heat with the raw material in the one-effect evaporator, and inputs the separated second liquid into the third evaporator as raw material.

3. The automatic control method of a countercurrent triple-effect evaporator according to claim 2, characterized in that: The first-effect separator receives and separates the heat exchange raw material obtained by the heat exchange between the first-effect evaporator and the second steam, and inputs the separated third steam into the condensing device to form condensed water, and further inputs the separated third liquid into the second evaporator as raw material.

4. The automatic control method of a countercurrent triple-effect evaporator according to claim 3, characterized in that: The steam-water separator receives and delivers the condensed water through the condensing device, and the controller adjusts the operating frequency of the liquid ring vacuum unit according to the negative pressure of the steam-water separator.

5. The automatic control method of a countercurrent triple-effect evaporator according to claim 4, characterized in that: After the liquid ring vacuum unit is shut down, when the liquid level in the steam-water separator approaches zero, the delivery of the condensed water is stopped.

6. The automatic control method of a countercurrent triple-effect evaporator according to claim 3, characterized in that: The monitoring module monitors the liquid levels of the first-effect separator, the second-effect separator and the third-effect separator, and sends a monitoring signal. The controller receives the monitoring signal and reduces the flow rate of the liquid separated by the corresponding separator output when the liquid level of one or more of the first-effect separator, the second-effect separator and the third-effect separator decreases.

7. The automatic control method of a countercurrent triple-effect evaporator according to claim 3, characterized in that: The monitoring module monitors the temperature of the steam outlet of the first effect separator, the second effect separator and the third effect separator. The controller receives the monitoring signal and reduces the amount of steam entering the corresponding evaporator when the temperature of one or more steam outlets of the first effect separator, the second effect separator and the third effect separator increases.

8. The automatic control method of a countercurrent triple-effect evaporator according to claim 1, characterized in that: The controller activates the feed valve to control the raw materials to be sequentially fed into the first-effect evaporator, the second-effect evaporator and the third-effect evaporator, including: the controller activates the feed valve to control the raw materials to be fed into the first-effect evaporator and then flow into the first-effect separator, after reaching the preset liquid level of the first-effect separator, flow into and enter the second-effect separator after passing through the second-effect evaporator, after reaching the preset liquid level of the second-effect separator, flow into and enter the third-effect separator after passing through the third-effect evaporator, until the preset liquid level of the third-effect separator is reached.

9. The automatic control method of a countercurrent triple-effect evaporator according to claim 1, characterized in that: When the liquid level in the separator approaches zero, sequentially prohibiting the corresponding separators from outputting liquid includes the following sequence: After the liquid level in the three-effect separator is evacuated, the controller prohibits the three-effect separator from outputting liquid; after the liquid level in the two-effect separator is evacuated, the controller prohibits the two-effect separator from outputting liquid; after the liquid level in the one-effect separator is evacuated, the controller prohibits the one-effect separator from outputting liquid.

10. An automatic control system for a countercurrent triple-effect evaporator, characterized in that: The automatic control method as claimed in any one of claims 1 to 9 is applied.

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