Economical water replenishing method for circulating cooling water system of power plant

Abstract

The invention relates to an economic water replenishing method for a power plant circulating cooling water system, and belongs to the technical field of power plant water-saving management methods. According to the technical scheme, typical water supplementing data of the circulating water system of the generator set is established, basic data of air temperature, humidity and wind speed of the local area in all seasons are established, and the evaporation loss, the pollution discharge loss and the wind blowing loss under various power generation load rate conditions and the typical water supplementing amount under different concentration multiple conditions are determined; optimal state data of low power generation water consumption, stable water quality, concentration multiple of 3.0 or above and low water replenishing cost are comprehensively considered, and a corresponding water replenishing operation method is determined; and evaluating the water replenishing economy, balance and scientificity of the circulating cooling water system of the power plant. The method has the beneficial effects that by establishing a scientific circulating water supplementing mode, balance of cost, water consumption and water quality can be comprehensively considered, and an operation method and an evaluation rule suitable for field practice are established.

Description

Technical Field

[0001] The invention relates to an economical water replenishment method for a circulating cooling water system of a power plant, and belongs to the technical field of water-saving management methods of power plants. Background Art

[0002] The power generation circulating water system is the largest water user in the power and auxiliary production processes of steel companies. Excluding the power generation system, the steel industry typically consumes 1.38 tons of fresh water per ton of steel. Including the power generation system, the figure rises to 2.21 tons per ton, a difference of 0.83 tons per ton. Water conservation in power generation systems generally focuses on three key factors: total power generation, total water replenishment, and replenishment costs. However, these three factors are directly linked to three other important factors: power generation water consumption, water quality, and concentration ratio. These six factors are interrelated and mutually influential, forming the six checks and balances within the power generation water conservation framework. Key issues with power generation systems include: high power generation water consumption; low concentration ratio; high replenishment costs; unscientific system replenishment methods; and a lack of water conservation strategies, water balance models, and scientific evaluation rules for power generation systems. In actual work, people often focus solely on the water consumption for power generation or the cost of water replenishment, ignoring the impact of water quality changes, seasonal factors, and changes in the source of water replenishment and the unit price of water from different sources. There is a lack of overall consideration of water-saving work from a high point and scientific evaluation rules for systematic water-saving effects. This reflects a lack of focus on one factor while neglecting another, and the optimal balance between low water consumption, low cost and stable water quality has not been truly achieved.

[0003] During the operation of a circulating cooling water system, the system's incoming water serves as makeup for the cooling tower. The outgoing water primarily consists of three components: evaporation loss, windage loss (excluding leakage losses), and sewage loss. Under normal operating conditions, the circulating water system's incoming water should equal the sum of evaporation loss, windage loss, and sewage loss.

[0004] The key to maintaining normal and stable operation of power generation water systems lies in two key balances: water quantity and water quality (salinity). These two balances are interconnected; changes in one will inevitably impact the other. Water conservation in power generation systems aims to find an optimal balance between water quantity and water quality (salinity), addressing both needs and preventing them from interfering with each other. Summary of the Invention

[0005] The purpose of the present invention is to provide an economical water replenishment method for the circulating cooling water system of a power plant. By establishing a scientific water replenishment method for circulating water, it is possible to comprehensively balance the three factors of cost, water consumption and water quality, and establish an operating method and evaluation rules suitable for the actual site, thereby effectively solving the above-mentioned problems existing in the background technology.

[0006] The technical solution of the present invention is: a method for economically replenishing water in a circulating cooling water system of a power plant, comprising the following steps:

[0007] Step 1: Obtain historical data on the daily average power generation, daily average water replenishment volume, daily average water replenishment cost, daily average water quality index, daily average concentration ratio, daily average power generation water replenishment water consumption, and daily average unit power generation water replenishment cost of the circulating water system of the steam turbine generator set, and establish typical water replenishment data for the circulating water system of the generator set;

[0008] Step 2: Obtain real-time meteorological information on temperature, wind speed, and humidity from local meteorological stations, as well as historical average meteorological information, to establish basic data on temperature, humidity, and wind speed for each season in the local area.

[0009] Step 3: Based on the relevant data obtained in Steps 1 and 2, combined with theoretical calculations, determine the evaporation loss, blowdown loss, and wind loss under various power generation load conditions, as well as the typical water replenishment amount under different concentration ratios;

[0010] Step 4: Based on the typical water replenishment volume determined in Step 3, test and analyze the water volume ratio when the replenishment water source is primary demineralized water and new production water. Considering the optimal state data of low power generation water consumption, stable water quality, a concentration ratio of 3.0 or above, and low water replenishment cost, determine the corresponding water replenishment operation method;

[0011] Step five: Select six indicators, namely, daily power generation, daily water replenishment, daily water replenishment cost, daily water quality index, daily concentration ratio and daily power generation water replenishment water consumption, as evaluation contents. Consider the mutual influencing factors comprehensively, establish a 10-point scoring rule for each indicator, and establish an evaluation rule based on the total score, the lowest value of each item and the degree to which the radar chart of the six indicators is close to a regular hexagon to evaluate the economy, balance and scientificity of water replenishment of the power plant's circulating cooling water system.

[0012] The step one further comprises:

[0013] The daily average data of the unit's circulating water volume, circulating water temperature rise and unit vacuum degree are collected as important parameters for theoretical calculation of evaporation loss, blowdown loss and wind loss.

[0014] The second step also includes:

[0015] Based on the real-time meteorological information on temperature, wind speed and humidity released by the local meteorological station and the average meteorological information data over the years, the most appropriate calculation parameters for various water losses of the countercurrent natural ventilation cooling tower are selected according to the theoretical formula.

[0016] The step three further includes:

[0017] The evaporation loss, sewage loss and wind loss corresponding to different power generation load rates of the circulating water system obtained by theoretical calculation are analyzed and compared with the historical data actually obtained. By eliminating abnormal data, representative typical water loss and water replenishment values under normal operating transition are obtained.

[0018] The step 4 further includes:

[0019] Understand the monthly changes in water prices when the replenishment water source is primary desalted water and new water production, as well as the changes in the total alkalinity of the new water produced each month. Take into account the three optimal states of ensuring low water consumption for power generation, stable water quality and lowest replenishment cost, and determine the corresponding replenishment operation method.

[0020] The step five further includes:

[0021] The six evaluation indicators formulated focus on the changes in the corresponding score values of the changes in water replenishment volume under different power generation load rates; at the same time, the water replenishment assembly score is comprehensively evaluated in combination with the high and low unit water replenishment cost value.

[0022] The application site is characterized by an open industrial circulating water system, a countercurrent natural ventilation cooling tower, and a water supply source of primary desalted water and new production water; the evaluation data should be based on the monthly average value, and abnormal data should be removed from the monthly data.

[0023] The abnormal data includes data on the status of the startup and shutdown process and the accident handling process.

[0024] The beneficial effects of the present invention are: by establishing a scientific way of replenishing circulating water, it is possible to comprehensively balance the three aspects of cost, water consumption and water quality, and establish an operating method and evaluation rules suitable for the actual site. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the system structure of the present invention;

[0026] Figure 2 This is a schematic diagram showing the water replenishment status of the power generation circulating water system in an embodiment of the present invention;

[0027] Figure 3 This is a statistical diagram of local temperature data in an embodiment of the present invention;

[0028] Figure 4 This is a diagram of the evaluation standard for power generation circulating water replenishment in an embodiment of the present invention;

[0029] Figure 5 This is a technical background diagram before the improvement of the power generation system according to an embodiment of the present invention;

[0030] Figure 6 This is a diagram showing the improved power generation system according to an embodiment of the present invention;

[0031] In the figure: steam turbine 1, generator 2, condenser 3, circulating water pump group 4, cooling tower 5, main steam inlet 6, turbine exhaust 7. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the invention implementation cases clearer, the technical solutions in the invention implementation cases will be clearly and completely described below in conjunction with the drawings in the implementation cases. Obviously, the implementation cases described are only a small part of the implementation cases of the present invention, rather than all the implementation cases. Based on the implementation cases in the present invention, all other implementation cases obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] A method for economically replenishing water in a circulating cooling water system of a power plant comprises the following steps:

[0034] Step 1: Obtain historical data on the daily average power generation, daily average water replenishment volume, daily average water replenishment cost, daily average water quality index, daily average concentration ratio, daily average power generation water replenishment water consumption, and daily average unit power generation water replenishment cost of the circulating water system of the steam turbine generator set, and establish typical water replenishment data for the circulating water system of the generator set;

[0035] Step 2: Obtain real-time meteorological information on temperature, wind speed, and humidity from local meteorological stations, as well as historical average meteorological information, to establish basic data on temperature, humidity, and wind speed for each season in the local area.

[0036] Step 3: Based on the relevant data obtained in Steps 1 and 2, combined with theoretical calculations, determine the evaporation loss, blowdown loss, and wind loss under various power generation load conditions, as well as the typical water replenishment amount under different concentration ratios;

[0037] Step 4: Based on the typical water replenishment volume determined in Step 3, test and analyze the water volume ratio when the replenishment water source is primary demineralized water and new production water. Considering the optimal state data of low power generation water consumption, stable water quality, a concentration ratio of 3.0 or above, and low water replenishment cost, determine the corresponding water replenishment operation method;

[0038] Step five: Select six indicators, namely, daily power generation, daily water replenishment, daily water replenishment cost, daily water quality index, daily concentration ratio and daily power generation water replenishment water consumption, as evaluation contents. Consider the mutual influencing factors comprehensively, establish a 10-point scoring rule for each indicator, and establish an evaluation rule based on the total score, the lowest value of each item and the degree to which the radar chart of the six indicators is close to a regular hexagon to evaluate the economy, balance and scientificity of water replenishment of the power plant's circulating cooling water system.

[0039] The step one further comprises:

[0040] The daily average data of the unit's circulating water volume, circulating water temperature rise and unit vacuum degree are collected as important parameters for theoretical calculation of evaporation loss, blowdown loss and wind loss.

[0041] The second step also includes:

[0042] Based on the real-time meteorological information on temperature, wind speed and humidity released by the local meteorological station and the average meteorological information data over the years, the most appropriate calculation parameters for various water losses of the countercurrent natural ventilation cooling tower are selected according to the theoretical formula.

[0043] The step three further includes:

[0044] The evaporation loss, sewage loss and wind loss corresponding to different power generation load rates of the circulating water system obtained by theoretical calculation are analyzed and compared with the historical data actually obtained. By eliminating abnormal data, representative typical water loss and water replenishment values under normal operating transition are obtained.

[0045] The step 4 further includes:

[0046] Understand the monthly changes in water prices when the replenishment water source is primary desalted water and new water production, as well as the changes in the total alkalinity of the new water produced each month. Take into account the three optimal states of ensuring low water consumption for power generation, stable water quality and lowest replenishment cost, and determine the corresponding replenishment operation method.

[0047] The step five further includes:

[0048] The six evaluation indicators formulated focus on the changes in the corresponding score values of the changes in water replenishment volume under different power generation load rates; at the same time, the water replenishment assembly score is comprehensively evaluated in combination with the high and low unit water replenishment cost value.

[0049] The application site is characterized by an open industrial circulating water system, a countercurrent natural ventilation cooling tower, and a water supply source of primary desalted water and new production water; the evaluation data should be based on the monthly average value, and abnormal data should be removed from the monthly data.

[0050] The abnormal data includes data on the status of the startup and shutdown process and the accident handling process.

[0051] Example:

[0052] This embodiment provides an economic water replenishment operation method and evaluation rules for a power plant circulating cooling water system, including:

[0053] Step 1: Obtain historical data such as the average daily power generation, average daily water replenishment volume, average daily water replenishment cost, average daily water quality index (calcium hardness + total alkalinity), average daily concentration multiple (calcium hardness + total alkalinity), average daily power generation water replenishment water consumption (referred to as power generation water consumption) and average daily unit power generation water replenishment cost (referred to as unit water replenishment cost) of the circulating water system of the steam turbine generator set; establish typical water replenishment data for the circulating water system of the generator set.

[0054] Step 2: Obtain real-time meteorological information such as temperature, wind speed, humidity, etc. released by local meteorological stations and average meteorological information data over the years; thus having relatively scientific data base on the temperature, humidity, and wind speed in each season of the local area, providing a basis for subsequent theoretical verification.

[0055] Step 3: Based on the relevant data obtained in Steps 1 and 2, combined with theoretical calculations, determine the evaporation loss, sewage loss and wind loss under various power generation load conditions, as well as the typical water replenishment amount under different concentration ratios.

[0056] Various water losses can be theoretically calculated based on the following formula:

[0057] The mathematical expression of water balance is: M=E+B+D(1)

[0058] Where, M—make-up water volume, t / h; E—evaporation loss, t / h;

[0059] B—wind loss, t / h; D—sewage loss, t / h;

[0060] The water replenishment percentage is expressed as: P = P1 + P2 + P3 (2)

[0061] In the formula, P is the percentage of supplementary water volume in circulating water volume, P = M / Q m ;

[0062] Its P1 is the percentage of evaporation loss to circulating water, P1 = E / Q m ;

[0063] P2—the percentage of wind loss in circulating water volume, P2=B / Q m ;

[0064] P3—the percentage of sewage loss in the circulating water volume, P3=D / Q m .

[0065] Q m —Circulating water volume, t / h.

[0066] In the above balance, P1 usually accounts for a larger share, and its size mainly depends on the heat load of the condenser and climatic conditions; the size of P2 is generally 0.1% (when a dehumidifier is installed in the unit cooling tower); the size of P3 mainly depends on the concentration rate that can be achieved by the circulating water system.

[0067] Salt balance expression of circulating water: K = (P1 + P2 + P3) / (P2 + P3); (4)

[0068] Where, K is the concentration factor of the circulating water system. In the power generation industry, it is generally advisable to keep K = 3-4 in order to save water economically.

[0069] Step 4: Based on the typical water replenishment volume determined in step 3, test and analyze the water volume ratio when the replenishment water source is primary demineralized water and new production water. Consider the optimal state data of low water consumption for power generation, stable water quality with a concentration ratio of 3.0 or above, and low water replenishment cost, and determine the corresponding water replenishment operation method.

[0070] According to steps one and three, typical water replenishment data suitable for different power generation load conditions are established.

[0071] Step 5: Select six indicators as evaluation contents, including daily power generation, daily water replenishment, daily water replenishment cost, daily water quality index, daily concentration multiple, and daily power generation water replenishment water consumption. Consider the mutual influencing factors comprehensively, establish a 10-point scoring rule for each indicator, and establish an evaluation rule based on the total score, the lowest value of each item, and the degree to which the radar chart of the six indicators is close to a regular hexagon to evaluate the economy, balance, and scientificity of water replenishment in the power plant's circulating cooling water system.

[0072] The present invention can ensure the economy and balance of water replenishment of the circulating cooling water system of the power plant for a long time, and at the same time can establish an evaluation method with strong applicability and intuitive image.

Claims

1. An economical water replenishment method for a circulating cooling water system in a power plant, characterized in that The following steps are involved: Step 1: Obtain historical data on the daily average power generation, daily average water replenishment volume, daily average water replenishment cost, daily average water quality index, daily average concentration ratio, daily average power generation water replenishment water consumption, and daily average unit power generation water replenishment cost of the circulating water system of the steam turbine generator set, and establish typical water replenishment data for the circulating water system of the generator set; Step 2: Obtain real-time meteorological information on temperature, wind speed, and humidity from local meteorological stations, as well as historical average meteorological information, to establish basic data on temperature, humidity, and wind speed for each season in the local area. Step 3: Based on the relevant data obtained in Steps 1 and 2, combined with theoretical calculations, determine the evaporation loss, blowdown loss, and wind loss under various power generation load conditions, as well as the typical water replenishment amount under different concentration ratios; Step 4: Based on the typical water replenishment volume determined in Step 3, test and analyze the water volume ratio when the replenishment water source is primary demineralized water and new production water. Considering the optimal state data of low power generation water consumption, stable water quality, a concentration ratio of 3.0 or above, and low water replenishment cost, determine the corresponding water replenishment operation method; Step five: Select six indicators, namely, daily power generation, daily water replenishment, daily water replenishment cost, daily water quality index, daily concentration ratio and daily power generation water replenishment water consumption, as evaluation contents. Consider the mutual influencing factors comprehensively, establish a 10-point scoring rule for each indicator, and establish an evaluation rule based on the total score, the lowest value of each item and the degree to which the radar chart of the six indicators is close to a regular hexagon to evaluate the economy, balance and scientificity of water replenishment of the power plant's circulating cooling water system.

2. The economical water replenishment method for a circulating cooling water system of a power plant according to claim 1, characterized in that: The step one further comprises: The daily average data of the unit's circulating water volume, circulating water temperature rise and unit vacuum degree are collected as important parameters for theoretical calculation of evaporation loss, blowdown loss and wind loss.

3. The economical water replenishment method for a circulating cooling water system of a power plant according to claim 1, characterized in that: The second step also includes: Based on the real-time meteorological information on temperature, wind speed and humidity released by the local meteorological station and the average meteorological information data over the years, the most appropriate calculation parameters for various water losses of the countercurrent natural ventilation cooling tower are selected according to the theoretical formula.

4. The economical water replenishment method for a circulating cooling water system of a power plant according to claim 1, characterized in that: The step three further includes: The evaporation loss, sewage loss and wind loss corresponding to different power generation load rates of the circulating water system obtained by theoretical calculation are analyzed and compared with the historical data actually obtained. By eliminating abnormal data, representative typical water loss and water replenishment values under normal operating transition are obtained.

5. The economical water replenishment method for a circulating cooling water system of a power plant according to claim 1, characterized in that: The step 4 further includes: Understand the monthly changes in water prices when the replenishment water source is primary desalted water and new water production, as well as the changes in the total alkalinity of the new water produced each month. Take into account the three optimal states of ensuring low water consumption for power generation, stable water quality and lowest replenishment cost, and determine the corresponding replenishment operation method.

6. The economical water replenishment method for a circulating cooling water system of a power plant according to claim 1, characterized in that: The step five further includes: The six evaluation indicators formulated focus on the changes in the corresponding score values of the changes in water replenishment volume under different power generation load rates; at the same time, the water replenishment assembly score is comprehensively evaluated in combination with the high and low unit water replenishment cost value.

7. The economical water replenishment method for a circulating cooling water system of a power plant according to claim 1, characterized in that: The application site is characterized by an open industrial circulating water system, a countercurrent natural ventilation cooling tower, and a water supply source of primary desalted water and new production water; the evaluation data should be based on the monthly average value, and abnormal data should be removed from the monthly data.

8. The economical water replenishment method for a circulating cooling water system of a power plant according to claim 1, characterized in that: The abnormal data includes data on the status of the startup and shutdown process and the accident handling process.

Images