A control system and method for a desalination water pump

Abstract

The present invention provides a control system and method for a desalinated water pump. The system includes: a unit set and a common system; the unit set is used to calculate the make-up water demand of desalinated water; the common system includes a running number determination module and a feedforward control module for the desalinated water pump, which are used to calculate the optimal running number of the desalinated water pump, control the start and stop of the desalinated water pump, and adjust the pressure of the outlet header of the desalinated water pump through feedforward control. The present invention can automatically match the operating conditions of the desalinated water pump according to the make-up water demand of desalinated water, realize the variable frequency control of the desalinated water pump, and quickly adjust the pressure of the desalinated water header through feedforward control to ensure the normal operation of the desalinated water system.

Description

Technical Field

[0001] The present invention relates to the technical field of desalination water pump control, and particularly relates to a control system and method for a desalination water pump. Background Art

[0002] Qualified desalinated water is produced by the chemical specialty and sent to the desalinated water tank. When the unit needs to be replenished with water, the desalinated water is sent to the user side of the unit through the desalination water pump. In order to save electricity, generally two small pumps are designed for the desalination water pump, with variable frequency control; two large pumps are designed, with variable frequency control; and one industrial frequency pump is designed for standby. When the water replenishment volume is low, the small pump is started to adjust the pressure of the desalinated water main pipe. When the water drainage volume is large, the large pump is started to adjust the pressure of the desalinated water main pipe. The whole process of starting the desalination water pump is judged by the operating personnel based on experience.

[0003] The control of the desalination water pump is generally in the public system and is controlled by the operating personnel of the chemical specialty. The control of the desalinated water user is generally in the unit unit and is controlled by the operating personnel of the unit. When there is a coordination error between the two, the following problems will occur: When the unit starts, the required water replenishment volume is large. If the public system controls the small pump to supply a large flow at this time, it will cause insufficient water supply, and the pressure of the desalinated water main pipe will drop sharply, directly affecting the safe start of the unit; when the unit is operating normally, the required water replenishment volume is small. If the public system controls the large pump to supply a small flow at this time, it is easy to damage the large pump. Therefore, when the water supply volume is different, phenomena such as insufficient adjustment of the desalination water pump will occur. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect of insufficient adjustment of the desalination water pump in the prior art, so as to provide a control system and working method for a desalination water pump, which can automatically match the operating conditions of the desalination water pump according to the required water replenishment volume of the desalinated water demand, and quickly adjust the pressure of the desalinated water main pipe through feedforward control.

[0005] The technical solution of the present invention to solve the above technical problem is as follows:

[0006] In the first aspect, the present invention provides a control system for a desalination water pump, and the system includes: a unit unit and a public system;

[0007] The unit unit is used to calculate the required water replenishment volume of the desalinated water;

[0008] The public system includes a desalination water pump operation number determination module and a desalination water pump feedforward control module, which are used to calculate the optimal operation number of the desalination water pump, control the start and stop of the desalination water pump, and adjust the pressure of the outlet main pipe of the desalination water pump through feedforward control.

[0009] The control system of the demineralized water pump provided by the embodiment of the present invention includes a unit set and a common system. The unit set is used to calculate the required makeup water volume of demineralized water. The common system includes a demineralized water pump operation number determination module and a demineralized water pump feedforward control module, which are used to calculate the optimal operation number of the demineralized water pump and control the start and stop of the demineralized water pump, and adjust the pressure of the outlet header of the demineralized water pump through feedforward control. The present invention can automatically match the operating conditions of the demineralized water pump according to the required makeup water volume of demineralized water, realize the frequency conversion control of the demineralized water pump, and quickly adjust the pressure of the demineralized water header through feedforward control to ensure the normal operation of the demineralized water system.

[0010] Optionally, the unit set includes: a condensate main pipe flow detection unit, a condensate recirculation flow detection unit, a cut-off amount detection unit, a boiler blowdown water volume detection unit, a cold section heat supply detection unit, a hot section heat supply detection unit, a boiler water filling completion detection unit, and a logic calculation unit;

[0011] The logic calculation unit is used to calculate the required makeup water volume of demineralized water, and includes: a subtraction block, a first filter block, a first switching block, a first addition block, a second addition block, and a first output block; the output end of the condensate main pipe flow detection unit is connected to the first input end of the subtraction block, the output end of the condensate recirculation flow detection unit is connected to the second input end of the subtraction block, the output end of the subtraction block is connected to the input end of the first filter block, the output end of the first filter block is connected to the second input end of the first switching block, the output end of the boiler water filling completion detection unit is connected to the first input end of the first switching block, the output end of the cut-off amount detection unit is connected to the third input end of the first switching block, the output end of the first switching block is connected to the first input end of the first addition block, the output end of the boiler blowdown water volume detection unit is connected to the second input end of the first addition block, the output end of the cold section heat supply detection unit is connected to the first input end of the second addition block, the output end of the hot section heat supply detection unit is connected to the second input end of the second addition block, the output end of the second addition block is connected to the third input end of the first addition block, and the output end of the first addition block is connected to the input end of the first output block.

[0012] The unit set of the present invention can more accurately obtain the required makeup water volume of demineralized water under the current operating conditions by detecting the condensate main pipe flow, condensate recirculation flow, boiler blowdown water volume, cold section heat supply, hot section heat supply, and boiler water filling completion of the control system, and ensure the safe operation of the system.

[0013] Optionally, the desalination water pump operation number determination module includes: a single small pump maximum output detection unit, a preset multiple small pump maximum output detection unit, a single large pump maximum output detection unit, a preset multiple large pump maximum output detection unit, and an operation number logic determination unit;

[0014] The operation number logic determination unit is used to determine the optimal operation number of the desalination water pump, and includes: a first setting block, a second setting block, a third setting block, a fourth setting block, a fifth setting block, a sixth setting block, a second output block, a third output block, a second filtering block, a first comparison block, a second comparison block, a third comparison block, a fourth comparison block, a second switching block, a third switching block, a fourth switching block, and a fifth switching block; the output end of the first output block of the unit unit is connected to the input end of the second filtering block, and the output end of the second filtering block is connected to the first input end of the first comparison block, the first input end of the second comparison block, the first input end of the third comparison block, and the first input end of the fourth comparison block. The output end of the single small pump maximum output detection unit is connected to the second input end of the first comparison block and the third input end of the second comparison block. The output end of the preset multiple small pump maximum output detection unit is connected to the second input end of the second comparison block and the third input end of the third comparison block. The output end of the single large pump maximum output detection unit is connected to the second input end of the third comparison block and the third input end of the fourth comparison block. The output end of the preset multiple large pump maximum output detection unit is connected to the second input end of the fourth comparison block; the output end of the first comparison block is connected to the first input end of the second switching block, the output end of the first setting block is connected to the second input end of the second switching block, the output end of the second setting block is connected to the third input end of the second switching block, the output end of the second comparison block is connected to the first input end of the third switching block, the output end of the second switching block is connected to the second input end of the third switching block, the output end of the third setting block is connected to the third input end of the third switching block, and the output end of the third switching block is connected to the input end of the second output block; the output end of the third comparison block is connected to the first input end of the fourth switching block, the output end of the fourth setting block is connected to the second input end of the fourth switching block, the output end of the fifth setting block is connected to the third input end of the fourth switching block, the output end of the fourth comparison block is connected to the first input end of the fifth switching block, the output end of the fourth switching block is connected to the second input end of the fifth switching block, the output end of the sixth setting block is connected to the third input end of the fifth switching block, and the output end of the fifth switching block is connected to the input end of the third output block.

[0015] The present invention determines the optimal operating number of the demineralized water pumps under the current operating conditions through the demineralized water pump operation number determination module of the common system. First, the make-up water demand of the demineralized water calculated according to the unit unit is compared with the maximum output of a single or a preset number of large pumps or small pumps. Secondly, the operating numbers of the large pumps and small pumps are switched according to the comparison results. The common system can automatically match the optimal operating number of the demineralized water pumps through the make-up water demand of the demineralized water, which can avoid the phenomenon of insufficient adjustment of the demineralized water pumps caused by manual operation and ensure the safe operation of the system.

[0016] Optionally, the demineralized water pump feed-forward control module includes: a demineralized water main pipe pressure detection unit and a feed-forward adjustment unit;

[0017] The feed-forward adjustment unit is used to adjust the pressure of the outlet main pipe of each demineralized water pump, and includes: a third filter block, a first function block, a second function block, a first control block, and a second control block; the output end of the demineralized water main pipe pressure detection unit is connected to the first input end of the first control block and the first input end of the second control block, the output end of the first output block of the unit unit is connected to the input end of the third filter block, the output end of the third filter block is connected to the input ends of the first function block and the second function block, the output end of the first function block is connected to the second input end of the first control block, and the output end of the second function block is connected to the second input end of the second control block.

[0018] The common system of the present invention adjusts the pressure of the outlet main pipe of the demineralized water pump by adding a feed-forward control module, measures the current pressure of the outlet main pipe of each demineralized water pump, and adjusts the pressure of the outlet main pipe of each demineralized water pump respectively according to the current operating conditions of the demineralized water pump and the calculated make-up water demand of the demineralized water. This can ensure that the outlet main pipe always operates within the normal pressure range, extend the service life of the demineralized water pump, and prevent the rapid deterioration of the demineralized water system.

[0019] Optionally, the switching logic of the first switching block, the second switching block, the third switching block, and the fourth switching block includes: when the input signal of the first input end of the switching block is false, the output end of the switching block outputs the parameter value of the second input end; when the input signal of the first input end of the switching block is true, the output end of the switching block outputs the parameter value of the third input end; the output parameters of the first setting block, the second setting block, and the third setting block represent selecting a preset number of small pumps, and the output parameters of the fourth setting block, the fifth setting block, and the sixth setting block represent selecting a preset number of large pumps.

[0020] In the unit set of the present invention, the water inflow of bubbles in the early stage of unit startup is switched to solve the phenomenon that steam flows back to the condenser after the drum water level becomes normal. The common system adjusts the frequency conversion of the demineralized water pump through a switching block. First, the maximum output of a single or multiple large pumps and small pumps is compared with the calculated makeup water demand of demineralized water in a comparison block, and the switching block selects the number of operating large pumps or small pumps according to the comparison result. By adjusting according to the current operating conditions of the system through the switching block, different operating conditions can be satisfied to the greatest extent, and damage to large pumps or small pumps can be reduced.

[0021] In a second aspect, an embodiment of the present invention provides a control method for a demineralized water pump, which controls the demineralized water pump based on the system provided in the first aspect, including:

[0022] The unit set calculates the makeup water demand of demineralized water according to the stage of the operating conditions;

[0023] The common system determines the optimal number of operating demineralized water pumps according to the makeup water demand and the output of the demineralized water pump, and controls the start and stop of the demineralized water pump according to the optimal number of operating pumps;

[0024] The common system detects the pressure of the outlet header of each demineralized water pump according to the start and stop state of the demineralized water pump, and performs feedforward control according to the makeup water demand to adjust the pressure of the outlet header.

[0025] In the control method for the demineralized water pump provided by the embodiment of the present invention, the unit set calculates the makeup water demand of demineralized water according to the stage of the operating conditions; the common system determines the optimal number of operating demineralized water pumps according to the makeup water demand and the output of the demineralized water pump, and controls the start and stop of the demineralized water pump according to the optimal number of operating pumps. At the same time, the common system detects the pressure of the outlet header of each demineralized water pump according to the start and stop state of the demineralized water pump, and performs feedforward control according to the makeup water demand to adjust the pressure of the outlet header. The present invention can automatically match the operating conditions of the demineralized water pump through the makeup water demand of demineralized water, realize the frequency conversion control of the demineralized water pump, and quickly adjust the pressure of the demineralized water header through feedforward control to ensure the normal operation of the demineralized water system.

[0026] Optionally, the stages of the operating conditions of the unit set include: the stage of calculating the makeup water demand before the unit set starts, the stage of calculating the makeup water demand during the normal operation of the unit set, and the stage of calculating the makeup water demand after the unit set is put into heating.

[0027] Optionally, the process of calculating the makeup water requirement during the startup of the unit includes: during the boiler water filling stage, obtaining the measured values of the condensate main pipe flow detection unit and the condensate recycle flow detection unit respectively, and obtaining the makeup water volume of the boiler steam drum by subtracting the measured value of the condensate recycle flow detection unit from the measured value of the condensate main pipe flow detection unit. The makeup water volume of the boiler steam drum is the required makeup water volume of demineralized water.

[0028] Optionally, the process of calculating the makeup water requirement during the normal operation of the unit includes: when the unit is not heating, determining the blowdown water volume of the boiler according to the continuous blowdown and fixed blowdown of each stage of the boiler. The blowdown water volume of the boiler is the required makeup water volume of demineralized water.

[0029] Optionally, the process of calculating the makeup water requirement during the stage after the unit starts heating includes: after the unit starts heating, obtaining the measured values of the cold section heat supply detection unit and the hot section heat supply detection stage respectively, obtaining the heat supply volume of the unit by adding the measured value of the cold section heat supply detection unit to the measured value of the hot section heat supply detection stage, and calculating the required makeup water volume of demineralized water based on the blowdown water volume of the boiler and the heat supply volume of the unit.

[0030] The present invention divides the calculation of the required makeup water volume of demineralized water for the unit into three stages according to the operating conditions of the unit: before startup, during normal operation, and after starting heating. Firstly, during the initial startup stage, mainly the steam drum is replenished with water. Therefore, the condensate main pipe flow and the condensate recycle flow are detected, and the required makeup water volume of demineralized water under the boiler water filling condition can be calculated by subtracting the two measured values. Secondly, during normal operation and when not heating, the blowdown water volume of the boiler is determined through the continuous blowdown and fixed blowdown of each stage of the boiler. At this time, the blowdown water volume of the boiler is used as the required makeup water volume of demineralized water for the unit under the current condition. Finally, after the unit starts heating, the return water of the heating unit is less or even non-existent. At this time, taking the heat supply volume of the unit as the required makeup water volume of demineralized water can meet the normal water supply of the system. Such a division can more accurately calculate the required makeup water volume of demineralized water under the current condition. Based on the accurate required makeup water volume, the optimal operation plan of the demineralized water pump can be determined to ensure the normal water supply of the system. Description of the Drawings

[0031] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0032] Figure 1 It is a schematic structural diagram of a control system for a demineralized water pump provided by an embodiment of the present invention;

[0033] Figure 2 Schematic diagram of the unit set structure of a desalination water pump control system provided by an embodiment of the present invention;

[0034] Figure 3 Schematic diagram of the structure of the running number determination module of the desalination water pump in the common system of a desalination water pump control system provided by an embodiment of the present invention;

[0035] Figure 4 Schematic diagram of the structure of the feedforward control module of the desalination water pump in the common system of a desalination water pump control system provided by an embodiment of the present invention;

[0036] Figure 5 Schematic diagram of a method for a desalination water pump control system provided by an embodiment of the present invention. Detailed implementation manners

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] Embodiment 1

[0040] An embodiment of the present invention provides a control system for a desalination water pump. As Figure 1 shown, the system specifically includes: a unit set and a common system;

[0041] The unit set is used to calculate the makeup water demand of desalinated water;

[0042] The common system includes a running number determination module and a feedforward control module of the desalination water pump, which are used to calculate the optimal running number of the desalination water pump, control the start and stop of the desalination water pump, and adjust the pressure of the outlet header of the desalination water pump through feedforward control.

[0043] Specifically, in the embodiment of the present invention, as Figure 2As shown in the figure, the unit unit includes: a condensate main pipe flow detection unit (A-01), a condensate recirculation flow detection unit (A-02), a cut-off amount detection unit (A-03), a boiler drain water amount detection unit (A-04), a cold section heat supply amount detection unit (A-05), a hot section heat supply amount detection unit (A-06), a boiler water filling completion detection unit (D-01) and a logic calculation unit. The logic calculation unit is used to calculate the make-up water demand of demineralized water, including: a subtraction block (SUB-01), a first filter block (LAG-01), a first switching block (T-01), a first addition block (ADD-01), a second addition block (ADD-02) and a first output block (AO-01). The internal connection relationship of the unit unit is as follows:

[0044] The output end of the condensate main pipe flow detection unit (A-01) is connected to the first input end X1 of the subtraction block (SUB-01), the output end of the condensate recirculation flow detection unit (A-02) is connected to the second input end X2 of the subtraction block (SUB-01), the output end of the subtraction block (SUB-01) is connected to the input end X1 of the first filter block (LAG-01), the output end of the first filter block (LAG-01) is connected to the second input end N of the first switching block (T-01), the output end of the boiler water filling completion detection unit (D-01) is connected to the first input end X1 of the first switching block (T-01), the output end of the cut-off amount detection unit (A-03) is connected to the third input end Y of the first switching block (T-01), the output end of the first switching block (T-01) is connected to the first input end X1 of the first addition block (ADD-01), the output end of the boiler drain water amount detection unit (A-04) is connected to the second input end X2 of the first addition block (ADD-01), the output end of the cold section heat supply amount detection unit (A-05) is connected to the first input end X1 of the second addition block (ADD-02), the output end of the hot section heat supply amount detection unit (A-06) is connected to the second input end X2 of the second addition block (ADD-02), the output end of the second addition block (ADD-02) is connected to the third input end X3 of the first addition block (ADD-01), and the output end of the first addition block (ADD-01) is connected to the input end of the first output block (AO-01).

[0045] In the embodiment of the present invention, the LAG time of the first filter block (LAG-01) is 10s, which can be specifically corrected on site. In addition, when the input signal of the input end X1 of the first switching block (T-01) is true, the output end of the first switching block (T-01) outputs the value of 0% of the input end Y of the first switching block (T-01); when the output signal of the input end X1 of the first switching block (T-01) is false, the output end of the first switching block (T-01) outputs the value of the input end N of the first switching block (T-01).

[0046] Specifically, in the embodiment of the present invention, 5 desalination pumps are provided in the desalination pump system, 2 large pumps are controlled by frequency conversion in cooperation with one large pump operating at power frequency, and 2 small pumps are controlled by frequency conversion. The above settings are only for illustration and not limited thereto. Therefore, as Figure 3 shown, the desalination pump operation number determination module of the common system in this embodiment includes: a single small pump maximum output detection unit (A-08), a 2-small-pump maximum output detection unit (A-09), a single large pump maximum output detection unit (A-13), a 2-large-pump maximum output detection unit (A-14), and an operation number logic determination unit. The operation number logic determination unit is used to determine the optimal operation number of the desalination pump, including: a first setting block (A-10), a second setting block (A-11), a third setting block (A-12), a fourth setting block (A-15), a fifth setting block (A-16), a sixth setting block (A-17), a second output block (AO-02), a third output block (AO-03), a second filtering block (LAG-02), a first comparison block (L-01), a second comparison block (HL-01), a third comparison block (HL-02), a fourth comparison block (HL-03), a second switching block (T-02), a third switching block (T-03), a fourth switching block (T-04), and a fifth switching block (T-05). The internal connection relationship of the desalination pump operation number determination module is as described below:

[0047] The output end of the first output block (AO-01) of the unit unit is connected to the input end X1 of the second filtering block (LAG-02). The output end of the second filtering block (LAG-02) is connected to the first input end X1 of the first comparison block (L-01), the first input end X1 of the second comparison block (HL-01), the first input end X1 of the third comparison block (HL-02), and the first input end X1 of the fourth comparison block (HL-03). The output end of the single small pump maximum output detection unit (A-08) is connected to the second input end L of the first comparison block (L-01) and the third input end H of the second comparison block (HL-01). The output end of the 2-small-pump maximum output detection unit (A-09) is connected to the second input end L of the second comparison block (HL-01) and the third input end H of the third comparison block (HL-02). The output end of the single large pump maximum output detection unit (A-13) is connected to the second input end L of the third comparison block (HL-02) and the third input end H of the fourth comparison block (HL-03). The output end of the 2-large-pump maximum output detection unit (A-14) is connected to the second input end L of the fourth comparison block (HL-03);

[0048] The output terminal of the first comparison block (L-01) is connected to the first input terminal X1 of the second switching block (T-02). The output terminal of the first setting block (A-10) is connected to the second input terminal N of the second switching block (T-02). The output terminal of the second setting block (A-11) is connected to the third input terminal Y of the second switching block (T-02). The output terminal of the second comparison block (HL-01) is connected to the first input terminal X1 of the third switching block (T-03). The output terminal of the second switching block (T-02) is connected to the second input terminal N of the third switching block (T-03). The output terminal of the third setting block (A-12) is connected to the third input terminal Y of the third switching block (T-03). The output terminal of the third switching block (T-03) is connected to the input terminal of the second output block (AO-02).

[0049] The output terminal of the third comparison block (HL-02) is connected to the first input terminal X1 of the fourth switching block (T-04). The output terminal of the fourth setting block (A-15) is connected to the second input terminal N of the fourth switching block (T-04). The output terminal of the fifth setting block (A-16) is connected to the third input terminal Y of the fourth switching block (T-04). The output terminal of the fourth comparison block (HL-03) is connected to the first input terminal X1 of the fifth switching block (T-05). The output terminal of the fourth switching block (T-04) is connected to the second input terminal N of the fifth switching block (T-05). The output terminal of the sixth setting block (A-17) is connected to the third input terminal Y of the fifth switching block (T-05). The output terminal of the fifth switching block (T-05) is connected to the input terminal of the third output block (AO-03).

[0050] In the embodiment of the present invention, the LAG time of the second filtering block (LAG-02) is 5 s, which can be specifically corrected on site. In addition, when the input signal of the input terminal X1 of the second switching block (T-02) is true, the output terminal of the second switching block (T-02) outputs the value of the input terminal Y of the second switching block (T-02), that is, the output parameter of the first setting block (A-11). When the output signal of the input terminal X1 of the second switching block (T-02) is false, the output terminal of the second switching block (T-02) outputs the value of the input terminal N of the second switching block (T-02), that is, the parameter value of the first setting block. The switching logics of other switching blocks are all as described above. In the embodiment of the present invention, the output parameters of the first setting block, the second setting block and the third setting block characterize the selection of small pumps with a preset number. The output parameters of the fourth setting block, the fifth setting block and the sixth setting block characterize the selection of large pumps with a preset number. For example: the first setting block (A-10) is set to 0; the second setting block (A-11) is set to 1; the third setting block (A-12) is set to 2; the fourth setting block (A-15) is set to 0; the fifth setting block (A-16) is set to 1; the sixth setting block (A-17) is set to 2.

[0051] Specifically, in the embodiments of the present invention, as Figure 4 shown, the feedforward control module of the demineralized water pump in the common system includes: a demineralized water main pipe pressure detection unit (A-18) and a feedforward adjustment unit. The feedforward adjustment unit is used to adjust the pressure of the outlet main pipe of each demineralized water pump, and includes: a third filter block (LAG-03), a first function block (F-01), a second function block (F-02), a first control block (PID-01), and a second control block (PID-02). The first control block (PID-01) is the control block for the small demineralized water pump, and the second control block (PID-02) is the control block for the large demineralized water pump. The connection relationship of the feedforward control module of the demineralized water pump is as described below:

[0052] The output end of the demineralized water main pipe pressure detection unit (A-18) is connected to the first input end X1 of the first control block (PID-01) and the first input end X1 of the second control block (PID-02). The output end of the first output block (AO-01) of the unit set is connected to the input end X1 of the third filter block (LAG-03). The output end of the third filter block (LAG-03) is connected to the input end X1 of the first function block (F-01) and the input end X1 of the second function block (F-02). The output end of the first function block (F-01) is connected to the second input end X2 of the first control block (PID-01). The output end of the second function block (F-02) is connected to the second input end (PID-01) of the second control block (PID-02).

[0053] In the embodiments of the present invention, the LAG time of the third filter block (LAG-03) is 5 s, which can be specifically corrected on site. The functions of the first function block (F-01) and the second function block (F-02) are produced according to the output of the large and small demineralized water pumps, and can be specifically corrected according to the actual situation.

[0054] The control system of the demineralized water pump provided by the embodiments of the present invention includes a unit set and a common system. The unit set is used to calculate the make-up water demand of demineralized water. The common system includes a demineralized water pump operation number determination module and a feedforward control module of the demineralized water pump, which are used to calculate the optimal operation number of the demineralized water pump, control the start and stop of the demineralized water pump, and adjust the pressure of the outlet main pipe of the demineralized water pump through feedforward control. The present invention can automatically match the operating conditions of the demineralized water pump according to the make-up water demand of demineralized water, realize the variable frequency control of the demineralized water pump, and quickly adjust the pressure of the demineralized water main pipe through feedforward control to ensure the normal operation of the demineralized water system.

[0055] Embodiment 2

[0056] The embodiments of the present invention provide a control method for a demineralized water pump, as Figure 5 shown, this method is used to control the demineralized water pump based on the system provided in Embodiment 1, and includes:

[0057] S1: The unit set calculates the make-up water demand of demineralized water according to the stage of the operating condition.

[0058] S2: The common system determines the optimal operating number of the demineralized water pumps according to the make-up water demand and the output of the demineralized water pumps, and controls the start and stop of the demineralized water pumps according to the optimal operating number.

[0059] S3: The common system detects the pressure of the outlet header of each demineralized water pump according to the start and stop state of the demineralized water pumps, and adjusts the outlet header pressure through feedforward control according to the make-up water demand.

[0060] Specifically, in the embodiments of the present invention, the stages divided according to the operating conditions of the unit set include: the stage of calculating the make-up water demand before the unit set starts, the stage of calculating the make-up water demand during the normal operation of the unit set, and the stage of calculating the make-up water demand after the unit set is put into heating. The calculation processes of each stage are as follows:

[0061] 1. The process of calculating the make-up water volume in the stage of calculating the make-up water demand before the unit set starts: In the stage of filling water into the boiler, the detection quantities of the condensate main pipe flow detection unit and the condensate recycle flow detection unit are respectively obtained, and the make-up water volume of the boiler steam drum is obtained by subtracting the detection quantity of the condensate recycle flow detection unit from the detection quantity of the condensate main pipe flow detection unit. The make-up water volume of the boiler steam drum is the make-up water demand of demineralized water.

[0062] 2. The process of calculating the make-up water volume in the stage of calculating the make-up water demand during the normal operation of the unit set: When the unit is not in heating, the blowdown volume of the boiler is determined according to the continuous blowdown and fixed blowdown of each stage of the boiler. The blowdown volume of the boiler is the make-up water demand of demineralized water.

[0063] 3. The process of calculating the make-up water volume in the stage of calculating the make-up water demand after the unit set is put into heating: After the unit set is put into heating, the detection quantities of the cold section heat supply detection unit and the hot section heat supply detection stage are respectively obtained, the heat supply of the unit set is obtained by adding the detection quantity of the cold section heat supply detection unit to the detection quantity of the hot section heat supply detection stage, and the make-up water demand of demineralized water is calculated based on the blowdown volume of the boiler and the heat supply of the unit set.

[0064] The control method for the desalted water pump provided by the embodiment of the present invention is such that the unit set calculates the required makeup water volume of desalted water according to the stage of the operating condition; the common system determines the optimal number of operating desalted water pumps according to the required makeup water volume and the output of the desalted water pump, and controls the start and stop of the desalted water pump according to the optimal number. Meanwhile, the common system detects the pressure of the outlet header of each desalted water pump according to the start and stop state of the desalted water pump, and adjusts the pressure of the outlet header through feedforward control according to the required makeup water volume. The present invention can automatically match the operating condition of the desalted water pump through the required makeup water volume of desalted water, realize the variable frequency control of the desalted water pump, and quickly adjust the pressure of the desalted water header through feedforward control to ensure the normal operation of the desalted water system.

[0065] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A control system for a desalination water pump, characterized in that, Including: Unit units and common systems; The unit unit is used to calculate the make-up water demand of demineralized water; The common system includes a demineralized water pump operation number determination module and a demineralized water pump feedforward control module, which are used to calculate the optimal operation number of the demineralized water pump, control the start and stop of the demineralized water pump, and adjust the pressure of the outlet header of the demineralized water pump through feedforward control; Among them, the unit unit includes: a condensate main pipe flow detection unit, a condensate recycle flow detection unit, a cut-off amount detection unit, a boiler drain water amount detection unit, a cold section heat supply detection unit, a hot section heat supply detection unit, a boiler water filling completion detection unit, and a logic calculation unit; The logic calculation unit is used to calculate the make-up water demand of demineralized water, including: a subtraction block, a first filter block, a first switching block, a first addition block, a second addition block, and a first output block; The output end of the condensate main pipe flow detection unit is connected to the first input end of the subtraction block, the output end of the condensate recycle flow detection unit is connected to the second input end of the subtraction block, the output end of the subtraction block is connected to the input end of the first filter block, the output end of the first filter block is connected to the second input end of the first switching block, the output end of the boiler water filling completion detection unit is connected to the first input end of the first switching block, the output end of the cut-off amount detection unit is connected to the third input end of the first switching block, the output end of the first switching block is connected to the first input end of the first addition block, the output end of the boiler drain water amount detection unit is connected to the second input end of the first addition block, the output end of the cold section heat supply detection unit is connected to the first input end of the second addition block, the output end of the hot section heat supply detection unit is connected to the second input end of the second addition block, the output end of the second addition block is connected to the third input end of the first addition block, and the output end of the first addition block is connected to the input end of the first output block; The demineralized water pump operation number determination module includes: a single small pump maximum output detection unit, a preset multiple small pump maximum output detection unit, a single large pump maximum output detection unit, a preset multiple large pump maximum output detection unit, and an operation number logic determination unit; The operation number logic determination unit is used to determine the optimal operation number of the demineralized water pump, including: a first setting block, a second setting block, a third setting block, a fourth setting block, a fifth setting block, a sixth setting block, a second output block, a third output block, a second filter block, a first comparison block, a second comparison block, a third comparison block, a fourth comparison block, a second switching block, a third switching block, a fourth switching block, and a fifth switching block; The output end of the first output block of the unit set is connected to the input end of the second filtering block. The output end of the second filtering block is connected to the first input end of the first comparison block, the first input end of the second comparison block, the first input end of the third comparison block, and the first input end of the fourth comparison block. The output end of the single small pump maximum output detection unit is connected to the second input end of the first comparison block and the third input end of the second comparison block. The output end of the preset multiple small pump maximum output detection unit is connected to the second input end of the second comparison block and the third input end of the third comparison block. The output end of the single large pump maximum output detection unit is connected to the second input end of the third comparison block and the third input end of the fourth comparison block. The output end of the preset multiple large pump maximum output detection unit is connected to the second input end of the fourth comparison block; The output end of the first comparison block is connected to the first input end of the second switching block. The output end of the first setting block is connected to the second input end of the second switching block. The output end of the second setting block is connected to the third input end of the second switching block. The output end of the second comparison block is connected to the first input end of the third switching block. The output end of the second switching block is connected to the second input end of the third switching block. The output end of the third setting block is connected to the third input end of the third switching block. The output end of the third switching block is connected to the input end of the second output block; The output end of the third comparison block is connected to the first input end of the fourth switching block. The output end of the fourth setting block is connected to the second input end of the fourth switching block. The output end of the fifth setting block is connected to the third input end of the fourth switching block. The output end of the fourth comparison block is connected to the first input end of the fifth switching block. The output end of the fourth switching block is connected to the second input end of the fifth switching block. The output end of the sixth setting block is connected to the third input end of the fifth switching block. The output end of the fifth switching block is connected to the input end of the third output block.

2. The control system of the desalination water pump according to claim 1, characterized in that, The demineralized water pump feedforward control module includes: a demineralized water main pipe pressure detection unit and a feedforward adjustment unit; The feedforward adjustment unit is used to adjust the pressure of the outlet main pipe of each demineralized water pump and includes: a third filtering block, a first function block, a second function block, a first control block, and a second control block; The output end of the demineralized water main pipe pressure detection unit is connected to the first input end of the first control block and the first input end of the second control block. The output end of the first output block of the unit set is connected to the input end of the third filtering block. The output end of the third filtering block is connected to the input end of the first function block and the input end of the second function block. The output end of the first function block is connected to the second input end of the first control block. The output end of the second function block is connected to the second input end of the second control block.

3. The control system of the desalination water pump according to claim 1, characterized in that, The switching logics of the first switching block, the second switching block, the third switching block, and the fourth switching block include: When the input signal at the first input terminal of the switching block is false, the output terminal of the switching block outputs the parameter value of the second input terminal; when the input signal at the first input terminal of the switching block is true, the output terminal of the switching block outputs the parameter value of the third input terminal; The output parameters of the first setting block, the second setting block and the third setting block characterize the selection of a preset number of small pumps, and the output parameters of the fourth setting block, the fifth setting block and the sixth setting block characterize the selection of a preset number of large pumps.

4. A control method for a desalination water pump, characterized in that, Based on the system according to any one of claims 1-3, controlling a desalination water pump, the control method comprising: The unit unit calculates the make-up water demand for desalinated water according to the stage of the operating condition; The common system determines the optimal number of operating desalination water pumps according to the make-up water demand for desalinated water and the output of the desalination water pumps, and controls the start and stop of the desalination water pumps according to the optimal number; The common system detects the pressure of the outlet header of each desalination water pump according to the start and stop state of the desalination water pump, and performs feedforward control according to the make-up water demand for desalinated water to adjust the pressure of the outlet header of the desalination water pump.

5. The control method of the desalination water pump according to claim 4, characterized in that The stages of the operating condition of the unit unit include: the make-up water demand calculation stage before the unit unit starts, the make-up water demand calculation stage during the normal operation of the unit unit, and the make-up water demand calculation stage after the unit unit is put into heating.

6. The control method of the desalination water pump according to claim 5, characterized in that, The process of calculating the make-up water volume in the make-up water demand calculation stage before the unit unit starts includes: in the stage of boiler water filling, respectively obtaining the detection amounts of the condensate main pipe flow detection unit and the condensate recirculation flow detection unit, and obtaining the boiler drum make-up water volume by subtracting the detection amount of the condensate recirculation flow detection unit from the detection amount of the condensate main pipe flow detection unit, and the boiler drum make-up water volume is the make-up water demand for desalinated water.

7. The control method of the desalination water pump according to claim 5, characterized in that, The process of calculating the make-up water volume in the make-up water demand calculation stage during the normal operation of the unit unit includes: when the unit is not heating, determining the boiler blowdown volume according to the continuous blowdown and fixed displacement of each stage of the boiler, and the boiler blowdown volume is the make-up water demand for desalinated water.

8. The control method of the desalination water pump according to claim 7, wherein, The process of calculating the make-up water volume in the make-up water demand calculation stage after the unit unit is put into heating includes: after the unit unit is put into heating, respectively obtaining the detection amounts of the cold section heat supply detection unit and the hot section heat supply detection unit, obtaining the unit unit heat supply by adding the detection amount of the cold section heat supply detection unit and the detection amount of the hot section heat supply detection unit, and calculating the make-up water demand for desalinated water based on the boiler blowdown volume and the unit unit heat supply.

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