Operating characteristic simulation calculation method for open circulating water system

Abstract

The invention discloses a simulation calculation method for operating characteristics of an open circulating water system, which comprises the following steps of: obtaining relative flow coefficients and relative power coefficients under different operating conditions and different operating numbers of circulating water pumps by combining field actual measurement and simulation calculation; furthermore, on the basis of the similarity of operating parameters of the circulating water system, after the unit commissioning number and the forebay water level are changed, according to the relative flow coefficient and the relative power coefficient under different working conditions and different commissioning number of circulating water pumps and the circulating water total flow and the circulating water pump total power under the known commissioning number of the circulating water pumps, the unit commissioning number and the forebay water level are calculated. And calculating the total flow of the circulating water and the total power of the circulating water pumps under the condition that other available circulating water pumps are put into operation, so as to effectively carry out the online operation economy calculation and optimization work of the expansion unit system circulating water system.

Description

Technical Field

[0001] The invention relates to a simulation calculation method for operation characteristics of an open circulating water system, belonging to the technical field of thermal power generation. Background Art

[0002] With the deepening of energy conservation, some power stations have built online optimization systems for circulating water systems to provide real-time guidance for operation. When planning and recommending the most economical operation mode of circulating water pumps, the online optimization system of circulating water systems needs to know in advance the total flow rate and total power of circulating water under the number of available circulating water pumps in operation. According to the principle of pumps and fans, after the number of units in operation and the water level in the forebay change, the pipeline resistance of the circulating water system will change accordingly, which will lead to changes in the total flow rate and total power of circulating water under the same number of circulating water pumps in operation. Since the total flow rate of circulating water is numerically equal to the sum of the cooling water flow rates of each condenser, and the cooling water flow rate of each condenser can be determined by the condenser heat load of the currently operating unit and the temperature difference between the cooling water inlet and outlet. The total power of circulating water is numerically equal to the sum of the power of each circulating water pump motor, and the power of each motor can be measured by the on-site 6kV power meter. Therefore, the total flow rate and total power of circulating water under the current number of circulating water pumps in operation are known parameters, and the total flow rate and total power of circulating water pumps under other available numbers of circulating water pumps in operation are unknown parameters.

[0003] The simulation calculation shows that the operating parameters of different circulating water systems have certain similarities under different operating conditions. In order to effectively carry out the online economic calculation and optimization of the expanded unit circulating water system, the present invention proposes a simulation calculation method for the operating characteristics of an open circulating water system. Summary of the invention

[0004] The purpose of the present invention is to effectively carry out the online operation economic calculation and optimization work of the expanded unit circulating water system, and the present invention proposes a simulation calculation method for the operation characteristics of an open circulating water system.

[0005] The technical solution implemented by the present invention is as follows: a simulation calculation method for the operating characteristics of an open circulating water system, characterized in that the method combines on-site actual measurement with simulation calculation to obtain relative flow coefficients and relative power coefficients under different operating conditions and different numbers of circulating water pumps in operation; further, based on the similarity of the operating parameters of the circulating water system, after the number of units in operation and the water level in the forebay change, the total flow rate of circulating water and the total power of circulating water pumps under other available numbers of circulating water pumps in operation are calculated according to the relative flow coefficients and relative power coefficients under different operating conditions and different numbers of circulating water pumps in operation and the total power of circulating water pumps under the known number of circulating water pumps in operation, so as to effectively carry out the economic calculation and optimization work of expanding the online operation of the unit circulating water system.

[0006] The method defines the operating conditions of the circulating water system as two-unit operating conditions, three-unit operating conditions, and four-unit operating conditions based on the number of power plant units that can be put into operation and the design data of the circulating water system of the expanded unit system. The actual number of circulating water pumps that can be put into operation in the two-unit operating condition is 2, 3, and 4; the actual number of circulating water pumps that can be put into operation in the three-unit operating condition is 3, 4, 5, and 6; the actual number of circulating water pumps that can be put into operation in the four-unit operating condition is 4, 5, 6, 7, and 8.

[0007] The method is based on the design data of the circulating water system of the expanded unit system, and 8 circulating water pumps and motor modules, 4 condenser modules and 1 circulating water inlet main pipe module are connected in series and in parallel to form a circulating water pipeline. Among them, the 8 circulating water pumps and motor modules are connected in parallel, and the outlets of each circulating water pump module are collected and connected in series to the inlet of the circulating water inlet main pipe module; the outlet of the circulating water inlet main pipe module is divided and connected in series to the inlet of each condenser module.

[0008] The method measures parameters such as the circulating water pump outlet pressure, condenser inlet / return water pressure, total circulating water flow, and total power of the circulating water pump under the annual average forebay water level under two-unit operating conditions, three-unit operating conditions, and four-unit operating conditions with different numbers of circulating water pumps in operation; based on the parameters measured on site, the circulating water pump head, circulating water pump efficiency, motor efficiency, condenser pressure drop, circulating water inlet main pipe pressure drop, and circulating water pump flow-head / efficiency characteristic curve under different operating conditions and different numbers of circulating water pumps in operation are obtained. The total circulating water flow is equal to the sum of the cooling water flow of all condensers in operation. The cooling water flow of each condenser is determined by the condenser heat load of each operating unit and the temperature difference between the cooling water inlet and outlet.

[0009] The method compiles calculation programs for the circulating water pump module, condenser module and circulating water inlet main pipe module according to relevant technical specifications, and carries out simulation calculations of two-machine operating conditions, three-machine operating conditions and four-machine operating conditions under the annual average forebay water level. Among them, the circulating water pump module calculates the flow, head, efficiency and motor power under different working conditions based on the field measured circulating water pump flow-head / efficiency characteristic curve. The condenser module calculates the water side resistance based on the water velocity in the condenser tube and the characteristic curve equation provided by the American Heat Exchange Institute HEI Standard Steam Surface Condensers, and obtains the corresponding condenser water side resistance correction coefficient according to the measured condenser inlet / return water pressure under different working conditions. The resistance along the circulating water inlet main pipe is calculated according to Darcy's formula, and the corresponding correction coefficient of the resistance along the circulating water inlet main pipe is obtained according to the measured data of the pressure drop of the circulating water inlet main pipe under different working conditions; at the same time, the altitude difference between the suction inlet of the circulating water pump and the outlet of the condenser is regarded as the elevation difference between the upstream and downstream interfaces of the circulating water pipeline, and is placed in the circulating water inlet main pipe module.

[0010] The method maintains the condenser water side resistance correction coefficient and the circulating water inlet main pipe along-line resistance correction coefficient under different working conditions according to the actual fluctuation amplitude of the forebay water level, and carries out simulation calculations of circulating water pump outlet pressure, condenser inlet / return water pressure, circulating water total flow rate and circulating water pump total power under different forebay water levels under two-unit operating conditions, three-unit operating conditions and four-unit operating conditions with different numbers of circulating water pumps in operation. The numbers of circulating water pumps under the two-unit operating conditions are 2, 3 and 4 respectively; the numbers of circulating water pumps under the three-unit operating conditions are 3, 4, 5 and 6 respectively; the numbers of circulating water pumps under the four-unit operating conditions are 4, 5, 6, 7 and 8 respectively.

[0011] The method sorts out the relative flow coefficients under different forebay water levels in the following way. Under a certain forebay water level, taking the total flow of circulating water under two circulating water pumps in the two-machine operation condition as the per unit value, the relative flow coefficients under two, three and four circulating water pumps in the two-machine operation condition are obtained respectively; taking the total flow of circulating water under three circulating water pumps in the three-machine operation condition as the per unit value, the relative flow coefficients under three, four, five and six circulating water pumps in the three-machine operation condition are obtained respectively; taking the total flow of circulating water under four circulating water pumps in the four-machine operation condition as the per unit value, the relative flow coefficients under four, five, six, seven and eight circulating water pumps in the four-machine operation condition are obtained respectively.

[0012] The method takes an average value of the relative flow coefficient under different forebay water levels, the same operating conditions and the same number of circulating water pumps in operation, and uses the average value as the final value of the relative flow coefficient under different operating conditions and different numbers of circulating water pumps in operation.

[0013] The method sorts out the relative power coefficients under different forebay water levels in the following way. Under a certain forebay water level, taking the total circulating water power under two circulating water pumps in the two-machine operation condition as the per-unit value, the relative power coefficients under two, three and four circulating water pumps in the two-machine operation condition are obtained respectively; taking the total circulating water power under three circulating water pumps in the three-machine operation condition as the per-unit value, the relative power coefficients under three, four, five and six circulating water pumps in the three-machine operation condition are obtained respectively; taking the total circulating water power under four circulating water pumps in the four-machine operation condition as the per-unit value, the relative power coefficients under four, five, six, seven and eight circulating water pumps in the four-machine operation condition are obtained respectively.

[0014] The method takes an average value of the relative power coefficient under different forebay water levels, the same operating conditions and the same number of circulating water pumps in operation, and uses the average value as the final value of the relative power coefficient under different operating conditions and different numbers of circulating water pumps in operation.

[0015] The method uses the total circulating water flow and the total circulating water power under the current number of circulating water pumps in operation as known parameters when the number of units in operation of the power station or the water level of the forebay changes; and calculates the total circulating water flow and the total circulating water power under other available numbers of circulating water pumps in operation according to the relative flow coefficient and the relative power coefficient under different numbers of circulating water pumps in operation under different working conditions.

[0016] The beneficial effect of the present invention is that, unlike previous circulating water system operation optimization projects in which the total circulating water flow rate and the total circulating water pump power under different numbers of circulating water pumps in operation are taken as fixed values, the present invention dynamically calculates the total circulating water flow rate and the total circulating water pump power under different working conditions and different numbers of circulating water pumps in operation according to the changes in the number of units in operation and the water level in the forebay and based on the similarity of the operating parameters of the circulating water system, which helps to improve the implementation effect of the economic operation of the circulating water system of the power station. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 This is a schematic diagram of a circulating water system for an expansion unit of a power station according to an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the operating characteristics of the circulating water system of the two-machine operating condition according to an embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the operating characteristics of the circulating water system of the third machine operating condition in the embodiment of the present invention;

[0021] Figure 4 It is a schematic diagram of the operating characteristics of the circulating water system of the fourth machine operating condition in embodiment of the present invention. DETAILED DESCRIPTION

[0022] The specific implementation of the present invention is shown in the figure. Figure 1 To Attachment Figure 4 , clearly and completely describe the technical solutions in the embodiments of the present invention.

[0023] This embodiment is a circulating water system for an expanded unit of a 4*300MW unit; the condenser adopts open circulation cooling, and each unit is equipped with 2 circulating water pumps, with a total of 8 pumps in the whole plant.

[0024] An embodiment of the present invention provides a simulation calculation method for the operation characteristics of an open circulating water system, characterized in that the method combines field measurement with simulation calculation to obtain relative flow coefficients and relative power coefficients under different operating conditions and with different numbers of circulating water pumps in operation; further, based on the similarity of the operating parameters of the circulating water system, after the number of units in operation and the water level in the forebay change, the total flow rate of circulating water and the total power of circulating water pumps under other available numbers of circulating water pumps in operation are calculated according to the relative flow coefficients and the relative power coefficients under different operating conditions and with different numbers of circulating water pumps in operation as well as the total flow rate of circulating water and the total power of circulating water pumps under the known number of circulating water pumps in operation, so as to effectively carry out the economic calculation and optimization work of expanding the online operation of the unit-based circulating water system.

[0025] The following steps are involved:

[0026] The method defines the operating conditions of the circulating water system as two-unit operating conditions, three-unit operating conditions, and four-unit operating conditions based on the number of power plant units that can be put into operation and the design data of the circulating water system of the expanded unit system. The actual number of circulating water pumps that can be put into operation in the two-unit operating condition is 2, 3, and 4; the actual number of circulating water pumps that can be put into operation in the three-unit operating condition is 3, 4, 5, and 6; the actual number of circulating water pumps that can be put into operation in the four-unit operating condition is 4, 5, 6, 7, and 8.

[0027] The method is based on the design data of the circulating water system of the expanded unit system, such as Figure 1 As shown, 8 circulating water pumps and motor modules, 4 condenser modules and 1 circulating water inlet main pipe module are connected in series and in parallel to form a circulating water pipeline. Among them, the 8 circulating water pumps and motor modules are connected in parallel, and the outlets of each circulating water pump module are collected and connected in series to the inlet of the circulating water inlet main pipe module; the outlet of the circulating water inlet main pipe module is divided and connected in series to the inlet of each condenser module.

[0028] The method measures parameters such as the circulating water pump outlet pressure, condenser inlet / return water pressure, total circulating water flow, and total power of the circulating water pump under the annual average forebay water level under two-unit operating conditions, three-unit operating conditions, and four-unit operating conditions with different numbers of circulating water pumps in operation; based on the parameters measured on site, the circulating water pump head, circulating water pump efficiency, motor efficiency, condenser pressure drop, circulating water inlet main pipe pressure drop, and circulating water pump flow-head / efficiency characteristic curve under different operating conditions and different numbers of circulating water pumps in operation are obtained. The total circulating water flow is equal to the sum of the cooling water flow of all condensers in operation. The cooling water flow of each condenser is determined by the condenser heat load of each operating unit and the temperature difference between the cooling water inlet and outlet.

[0029] The method compiles calculation programs for the circulating water pump module, condenser module and circulating water inlet main pipe module according to relevant technical specifications, and carries out simulation calculations of two-machine operating conditions, three-machine operating conditions and four-machine operating conditions under the annual average forebay water level. Among them, the circulating water pump module calculates the flow, head, efficiency and motor power under different working conditions based on the field measured circulating water pump flow-head / efficiency characteristic curve. The condenser module calculates the water side resistance based on the water velocity in the condenser tube and the characteristic curve equation provided by the American Heat Exchange Institute HEI Standard Steam Surface Condensers, and obtains the corresponding condenser water side resistance correction coefficient according to the measured condenser inlet / return water pressure under different working conditions. The resistance along the circulating water inlet main pipe is calculated according to Darcy's formula, and the corresponding correction coefficient of the resistance along the circulating water inlet main pipe is obtained according to the measured data of the pressure drop of the circulating water inlet main pipe under different working conditions; at the same time, the altitude difference between the suction inlet of the circulating water pump and the outlet of the condenser is regarded as the elevation difference between the upstream and downstream interfaces of the circulating water pipeline, and is placed in the circulating water inlet main pipe module.

[0030] The method maintains the condenser water side resistance correction coefficient and the circulating water inlet main pipe along-line resistance correction coefficient under different working conditions according to the actual fluctuation amplitude of the forebay water level, and carries out simulation calculations of circulating water pump outlet pressure, condenser inlet / return water pressure, circulating water total flow rate and circulating water pump total power under different forebay water levels under two-unit operating conditions, three-unit operating conditions and four-unit operating conditions with different numbers of circulating water pumps in operation. The numbers of circulating water pumps under the two-unit operating conditions are 2, 3 and 4 respectively; the numbers of circulating water pumps under the three-unit operating conditions are 3, 4, 5 and 6 respectively; the numbers of circulating water pumps under the four-unit operating conditions are 4, 5, 6, 7 and 8 respectively.

[0031] The method sorts out the relative flow coefficients under different forebay water levels in the following way. Under a certain forebay water level, taking the total flow of circulating water under two circulating water pumps in the two-machine operation condition as the per unit value, the relative flow coefficients under two, three and four circulating water pumps in the two-machine operation condition are obtained respectively; taking the total flow of circulating water under three circulating water pumps in the three-machine operation condition as the per unit value, the relative flow coefficients under three, four, five and six circulating water pumps in the three-machine operation condition are obtained respectively; taking the total flow of circulating water under four circulating water pumps in the four-machine operation condition as the per unit value, the relative flow coefficients under four, five, six, seven and eight circulating water pumps in the four-machine operation condition are obtained respectively.

[0032] The method takes an average value of the relative flow coefficient under different forebay water levels, the same operating conditions and the same number of circulating water pumps in operation, and uses the average value as the final value of the relative flow coefficient under different operating conditions and different numbers of circulating water pumps in operation.

[0033] The method sorts out the relative power coefficients under different forebay water levels in the following way. Under a certain forebay water level, taking the total circulating water power under two circulating water pumps in the two-machine operation condition as the per-unit value, the relative power coefficients under two, three and four circulating water pumps in the two-machine operation condition are obtained respectively; taking the total circulating water power under three circulating water pumps in the three-machine operation condition as the per-unit value, the relative power coefficients under three, four, five and six circulating water pumps in the three-machine operation condition are obtained respectively; taking the total circulating water power under four circulating water pumps in the four-machine operation condition as the per-unit value, the relative power coefficients under four, five, six, seven and eight circulating water pumps in the four-machine operation condition are obtained respectively.

[0034] The method takes an average value of the relative power coefficient under different forebay water levels, the same operating conditions and the same number of circulating water pumps in operation, and uses the average value as the final value of the relative power coefficient under different operating conditions and different numbers of circulating water pumps in operation.

[0035] The method uses the total circulating water flow and the total circulating water power under the current number of circulating water pumps in operation as known parameters when the number of units in operation of the power station or the water level of the forebay changes; and calculates the total circulating water flow and the total circulating water power under other available numbers of circulating water pumps in operation according to the relative flow coefficient and the relative power coefficient under different numbers of circulating water pumps in operation under different working conditions. Figure 2 , Figure 3 , Figure 4 The operating characteristics of the circulating water system under two-machine operation / three-machine operation / four-machine operation conditions at different forebay water levels are demonstrated respectively.

[0036] The above is a detailed introduction to the simulation calculation method for the operation characteristics of an open circulating water system provided by the present invention. In this embodiment, a specific example is used to illustrate the principle and implementation method of the present invention. The description of the above embodiment is only used to help understand the method and core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for simulating and calculating the operating characteristics of an open circulating water system, characterized in that: The method combines field measurement with simulation calculation to obtain relative flow coefficients and relative power coefficients under different operating conditions and different numbers of circulating water pumps in operation; further, based on the similarity of the operating parameters of the circulating water system, after the number of units in operation and the water level in the forebay change, the total circulating water flow rate and total power of circulating water pumps under other available numbers of circulating water pumps in operation are calculated according to the relative flow coefficients and relative power coefficients under different operating conditions and different numbers of circulating water pumps in operation, as well as the total circulating water flow rate and total circulating water pump power under the known number of circulating water pumps in operation, so as to effectively carry out the economic calculation and optimization work of expanding the online operation of the unit-based circulating water system.

2. The method for simulating and calculating the operating characteristics of an open circulating water system according to claim 1, characterized in that: The method specifically comprises the following steps: Step 1: Based on the number of power plant units that can be put into operation and the design data of the circulating water system of the expanded unit system, the operating conditions of the circulating water system are defined as two-unit operating conditions, three-unit operating conditions and four-unit operating conditions; the actual number of circulating water pumps that can be put into operation under the two-unit operating condition is 2, 3 and 4; the actual number of circulating water pumps that can be put into operation under the three-unit operating condition is 3, 4, 5 and 6; the actual number of circulating water pumps that can be put into operation under the four-unit operating condition is 4, 5, 6, 7 and 8. Step 2: Based on the design data of the circulating water system of the expanded unit system, 8 circulating water pumps and motor modules, 4 condenser modules and 1 circulating water inlet main pipe module are connected in series and in parallel to form a circulating water pipeline. Among them, the 8 circulating water pumps and motor modules are connected in parallel, and the outlets of each circulating water pump module are collected and connected in series to the inlet of the circulating water inlet main pipe module; the outlet of the circulating water inlet main pipe module is divided and connected in series to the inlet of each condenser module; Step 3: Under the annual average forebay water level, the circulating water pump outlet pressure, condenser inlet / return water pressure, total circulating water flow and total power of the circulating water pump are measured on site under the two-unit operating condition, the three-unit operating condition and the four-unit operating condition with different numbers of circulating water pumps in operation; based on the parameters measured on site, the circulating water pump head, circulating water pump efficiency, motor efficiency, condenser pressure drop, circulating water inlet main pipe pressure drop and circulating water pump flow-head / efficiency characteristic curve under different operating conditions and different numbers of circulating water pumps in operation are obtained. The total circulating water flow is equal to the sum of the cooling water flow of all condensers in operation. The cooling water flow of each condenser is determined by the condenser heat load of each operating unit and the temperature difference between the cooling water inlet and outlet; Step 4: According to relevant technical specifications, the calculation procedures of the circulating water pump module, condenser module and circulating water inlet main pipe module are compiled, and simulation calculations of two-machine operating conditions, three-machine operating conditions and four-machine operating conditions under the annual average forebay water level are carried out. Among them, the circulating water pump module calculates the flow, head, efficiency and motor power under different working conditions based on the on-site measured circulating water pump flow-head / efficiency characteristic curve. The condenser module calculates the water side resistance based on the water velocity in the condenser tube and the characteristic curve equation, and obtains the corresponding condenser water side resistance correction coefficient according to the measured condenser inlet / return water pressure under different working conditions. The resistance along the circulating water inlet main pipe is calculated according to the Darcy formula, and the corresponding circulating water inlet main pipe resistance correction coefficient is obtained according to the measured data of the circulating water inlet main pipe pressure drop under different working conditions; at the same time, the altitude difference between the circulating water pump suction port and the condenser outlet is regarded as the elevation difference between the upstream and downstream interfaces of the circulating water pipeline, and is placed in the circulating water inlet main pipe module; Step 5: According to the actual fluctuation amplitude of the forebay water level, the condenser water side resistance correction coefficient and the circulating water inlet main pipe resistance correction coefficient under different operating conditions are maintained, and simulation calculations of the circulating water pump outlet pressure, condenser inlet / return water pressure, circulating water total flow rate and circulating water pump total power under different forebay water levels under two-unit operating conditions, three-unit operating conditions and four-unit operating conditions with different numbers of circulating water pumps in operation are carried out. Under the two-unit operating condition, the number of circulating water pumps is selected as 2, 3 and 4 respectively; under the three-unit operating condition, the number of circulating water pumps is selected as 3, 4, 5 and 6 respectively; under the four-unit operating condition, the number of circulating water pumps is selected as 4, 5, 6, 7 and 8 respectively; Step 6: Based on the simulation calculation results of step 5, the relative flow coefficients under different forebay water levels are sorted out by the following method, specifically: under a certain forebay water level, the total flow of circulating water under two circulating water pumps in the two-machine operation condition is taken as the per unit value, and the relative flow coefficients under two, three and four circulating water pumps in the two-machine operation condition are obtained respectively; the total flow of circulating water under three circulating water pumps in the three-machine operation condition is taken as the per unit value, and the relative flow coefficients under three, four, five and six circulating water pumps in the three-machine operation condition are obtained respectively; the total flow of circulating water under four circulating water pumps in the four-machine operation condition is taken as the per unit value, and the relative flow coefficients under four, five, six, seven and eight circulating water pumps in the four-machine operation condition are obtained respectively; Step 7: Take the average value of the relative flow coefficients obtained in step 6 under different forebay water levels and the same operating conditions and the same number of circulating water pumps in operation, and use it as the final value of the relative flow coefficients under different operating conditions and different numbers of circulating water pumps in operation; Step 8: Based on the simulation calculation results of step 5, the relative power coefficients under different forebay water levels are sorted out by the following method, specifically: under a certain forebay water level, taking the total circulating water power under 2 circulating water pumps in the two-machine operation condition as the per-unit value, the relative power coefficients under 2, 3 and 4 circulating water pumps in the two-machine operation condition are obtained respectively; taking the total circulating water power under 3 circulating water pumps in the three-machine operation condition as the per-unit value, the relative power coefficients under 3, 4, 5 and 6 circulating water pumps in the three-machine operation condition are obtained respectively; taking the total circulating water power under 4 circulating water pumps in the four-machine operation condition as the per-unit value, the relative power coefficients under 4, 5, 6, 7 and 8 circulating water pumps in the four-machine operation condition are obtained respectively; Step 9: Take the average value of the relative power coefficients obtained in step 8 under different forebay water levels and the same operating conditions and the same number of circulating water pumps in operation, and use it as the final value of the relative power coefficients under different operating conditions and different numbers of circulating water pumps in operation; Step 10: When the number of power plant units in operation or the water level in the forebay changes, the total circulating water flow and total circulating water power under the current number of circulating water pumps in operation are taken as known parameters; according to the relative flow coefficient and relative power coefficient under different operating conditions and different numbers of circulating water pumps in operation obtained in Steps 7 and 9, the total circulating water flow and total circulating water pump power under other available numbers of circulating water pumps in operation are calculated.

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