Method for optimizing operation of cooling tower all year round

Abstract

The invention provides a full-year cooling tower optimization operation method, which comprises the following steps of: acquiring basic parameters of a cooling tower for calculation to obtain parameters representing the operation condition of the cooling tower, and establishing a target function representing the full-year operation condition of the cooling tower by taking the actually measured air volume and the actually measured water volume as independent variables and the efficiency eta st and the energy consumption N1 + N2 of the cooling tower as dependent variables; on the premise of ensuring the cooling load of the cooling tower, the guidance air volume and guidance water volume are obtained by calculating the efficiency and energy consumption of the cooling tower, and then the efficiency of the cooling tower is controlled. According to the annual cooling tower optimization operation method, an operator is guided to adjust the cooling tower to always operate at the optimal working condition point, and the problem that the efficiency of the cooling tower is difficult to effectively adjust in an existing method is solved.

Description

Technical Field

[0001] The invention relates to the technical field of industrial energy saving and cooling methods, and in particular to a method for optimizing the operation of a cooling tower throughout the year. Background Art

[0002] The circulating cooling water system is mainly composed of components such as water pumps, heat exchangers and cooling towers. Among them, the circulating water cooling tower is widely used in various fields such as chemical industry, steel, thermal power, etc. It is a kind of equipment that uses the convection of water and air to remove heat from water through evaporation.

[0003] After the traditional cooling tower is accepted and debugged to the best operating state and put into use, there is no professional adjustment. Due to filler scaling and damage, heat load changes, circulating water volume optimization and other reasons, the long-term operating state of the cooling tower deviates from the current optimal operating state, resulting in fan energy consumption, high water temperature, and even increasing the water volume to increase the power consumption of the circulating water pump.

[0004] Even if professionals make adjustments, it is difficult to determine whether to increase the air volume or reduce the water volume to adjust the operating state to the highest efficiency. Therefore, it is necessary to design an operation control plan that can ensure that the cooling tower operates in the best operating state throughout the year. Summary of the invention

[0005] The purpose of the present invention is to provide a method for optimizing the operation of a cooling tower throughout the year, thereby solving the problem that the existing method is difficult to effectively adjust the efficiency of the cooling tower.

[0006] The technical solution adopted by the present invention is: a method for optimizing the operation of a cooling tower throughout the year, obtaining the basic parameters of the cooling tower for calculation, obtaining the parameters characterizing the operating status of the cooling tower, establishing a cooling tower efficiency η with the measured air volume and the measured water volume as independent variables st The objective function that characterizes the annual operation status of the cooling tower is established with energy consumption (N1+N2) as the dependent variables. Under the premise of ensuring the heat dissipation load of the cooling tower, the efficiency and energy consumption of the cooling tower are calculated to obtain the guiding air volume and guiding water volume, thereby controlling the efficiency of the cooling tower.

[0007] The technical solution adopted by the present invention is also characterized in that:

[0008] Furthermore, the method for optimizing the operation of cooling towers throughout the year is implemented in the following steps:

[0009] Step 1: Obtain basic parameters of the cooling tower, including design parameters and real-time parameters;

[0010] Step 2: Take the cooling tower heat dissipation load Q as the standard to meet the process side requirements and define the circulating water volume Q v The annual adjustable range is ±15% of the designed water volume, and the inlet and outlet water temperature difference range is calculated accordingly;

[0011] Step 3: Calculate the air-water ratio interval λ of the cooling tower for the whole year according to the inlet and outlet water temperature difference range;

[0012] Step 4: Establish a model with measured air volume and measured water volume as independent variables and cooling tower efficiency η st The objective function that characterizes the annual operation status of the cooling tower with energy consumption (N1+N2) as the dependent variable;

[0013] Step 5, by using the objective function obtained in step 4, obtain the guiding air volume and guiding water volume with the highest cooling tower efficiency, the lowest energy consumption and the air-water ratio satisfying the air-water ratio interval λ;

[0014] Step 6: Obtain two-dimensional data consisting of air volume and water volume of multiple groups of cooling tower efficiency and energy consumption through calculation. Determine the point with the highest efficiency and the lowest energy consumption as the optimal operating point by comparing the data. At this point, the operation adjustment of the cooling tower is completed.

[0015] Furthermore, in step 1, the design parameters include fan shaft power, air volume, water volume, single tower length and width, packing installation height, and packing thermal performance, which are the design basis of the cooling tower. The design parameters mentioned in this article refer to one of these parameters; the real-time parameters are obtained using sensors, including atmospheric pressure, dry-bulb temperature, wet-bulb temperature, inlet water temperature, outlet water temperature, fan shaft real-time power, and real-time water volume, among which the real-time operating air volume is indirectly calculated.

[0016] Furthermore, step 2 is as follows:

[0017] Ensure that the cooling tower heat dissipation load Q is constant to meet the process side requirements, that is, the water volume is inversely proportional to the inlet and outlet water temperature difference, see formula (1):

[0018] Q=Q v ×c w ×(t2-t1) (1)

[0019] Where Q represents the cooling tower heat dissipation load in kW, Q v Indicates the circulating water volume, in m 3 / h,c w represents the specific heat capacity of water, kJ / (kg·℃), t2 and t1 represent the inlet and outlet temperatures of circulating water, in ℃, and (t2-t1) is the inlet and outlet water temperature difference;

[0020] The annual adjustable range of circulating water volume is generally ±15% of the design water volume. The inlet and outlet water temperature difference range can be obtained based on the inverse relationship.

[0021] Further, step 3 is specifically as follows: an air-water ratio interval λ satisfying the inlet and outlet water temperature difference range is calculated from environmental parameters including atmospheric pressure, dry bulb temperature, and wet bulb temperature;

[0022] The air-water ratio range is the operating range of the cooling tower throughout the year. The air-water ratio is the ratio of air volume to water volume. The air volume range can be known from the circulating water volume. For details, see formula (2):

[0023]

[0024] Among them, Q m represents the water mass flow rate in kg / h; ρ1 represents the inlet dry air density in kg / m 3 , G represents the volume flow rate of dry air entering the tower, in m 3 / h.

[0025] Furthermore, step 4 is as follows:

[0026] Step 4.1, determine the measured air volume during the operation of a single tower. The cooling tower fan adopts frequency conversion regulation. The measured air volume is solved according to the similarity law between the fan shaft power and the air volume. The fan shaft power is calculated from the frequency converter.

[0027] Step 4.2: Input known design parameters and measured parameters to calculate the characteristic number N' of the filler. For details, see formula (3):

[0028] N'=Aλ m (3)

[0029] Among them, A and m characterize the packing performance, different packing types have empirical constants, and λ is the gas-water ratio interval;

[0030] Step 4.3, the measured water volume is measured by the flow sensor based on the real-time parameters of atmospheric pressure, dry bulb temperature, wet bulb temperature, inlet water temperature, and outlet water temperature. The measured air volume in step 4.1 is assumed to be the outlet temperature, and the cooling number N is calculated. For details, see formula (4):

[0031]

[0032] Among them, C W represents the specific heat capacity of water, in kj / (kg·k); Δt represents the difference between the measured inlet temperature and the assumed outlet temperature; h″ c1 It indicates the saturated air enthalpy under the condition of tower water temperature and 0.1Δt, kJ / kg(DA), h G1 Indicates the corrected specific enthalpy of air at the first point, kJ / kg(DA), h″ c2 It indicates the saturated air enthalpy under the condition of tower water temperature and 0.4Δt, kJ / kg(DA), h G2 Indicates the corrected specific enthalpy of air at the second point, kJ / kg(DA), h″ c3 Indicates the saturated air enthalpy under the condition of the difference between the inlet water temperature and 0.4Δt, kJ / kg (DA), h G3Indicates the corrected specific enthalpy of air at the third point, kJ / kg(DA), h″ c4 Indicates the saturated air enthalpy under the condition of the difference between the inlet water temperature and 0.1Δt, kJ / kg (DA), h G4 It represents the corrected specific enthalpy of air at the third point, kJ / kg (DA);

[0033] Step 4.4, calculate the cooling number N by assuming the outlet water temperature, and iterate until |N'-N|≤0.01, obtain the calculated outlet water temperature, and calculate the cooling tower efficiency, see formula (5) for details;

[0034]

[0035] Among them, η st Indicates cooling tower efficiency; Δt t Indicates the actual measured difference between the tower inlet temperature and the tower outlet temperature, Δt d Indicates the difference between the measured water inlet temperature and the theoretically calculated water outlet temperature;

[0036] Step 4.5: Calculate the energy consumption of the cooling tower. The power consumption of the fan motor can be directly obtained through the frequency converter, which is N1. The energy consumption of the water volume is determined by the water flow at the pressure measuring point above the tower. For details, see formula (6):

[0037] N2=Q s ×P (6)

[0038] Among them, N2 represents the work capacity of the upper tower flow, the unit is W, Q s Indicates the flow rate at this point, in m 3 / s, P represents the pressure at that point, the unit is Pa, the flow rate and pressure are both the actual measured values ​​of the sensor;

[0039] Step 4.6: Combine equations (3), (4), (5), and (6) to obtain the objective function that characterizes the operating conditions of the cooling tower throughout the year.

[0040] Furthermore, the energy consumption calculation in step 4.5, based on the traditional calculation of fan energy consumption, adds the calculation of the working capacity of the upper tower flow rate to comprehensively evaluate the cooling tower energy consumption.

[0041] Furthermore, the measuring point in step 4.5 can be installed at any position of the upper tower pipeline, and the specific measuring method can be adapted to local conditions.

[0042] The beneficial effects of the present invention are:

[0043] The present invention takes into account the influence of water volume, air flow, temperature, environmental climate parameters, etc. on the operation of the cooling tower, provides more key values ​​for monitoring the operation of the cooling tower, and establishes a cooling tower efficiency η with the measured air volume and the measured water volume as independent variables. stThe objective function that characterizes the operating status of the cooling tower throughout the year takes the air volume and water volume as the dependent variables. The cooling tower staff can freely adjust the air volume and water volume within the air-water ratio range according to this objective, so that the cooling tower operates under the guidance air volume and water volume, and always ensures that the heat dissipation load meets the process. No matter how the other parameters mentioned above change, this function can guide the operator to adjust the cooling tower to always operate at the optimal operating point. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic flow diagram of the method for optimizing the operation of a cooling tower throughout the year of the present invention;

[0045] Figure 2 It is a comprehensive diagram of cooling tower efficiency and energy consumption of the present invention;

[0046] Figure 3 This is a data diagram of Example 6 of the present invention. DETAILED DESCRIPTION

[0047] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] The present invention provides a method for optimizing the operation of a cooling tower throughout the year. The specific implementation process is as follows: Figure 1 shown.

[0049] The premise of the efficiency and energy consumption calculation of the present invention is that no matter how the external environmental parameters change and how the water volume and air volume are adjusted, the cooling tower heat dissipation load Q is guaranteed to be constant to meet the process side requirements, that is, the water volume and the temperature difference are inversely proportional, as shown in the following formula:

[0050] Q=Q v ×c w ×(t2-t1) (1);

[0051] Where Q represents the cooling tower heat dissipation load in kW, Q v Indicates the circulating water volume, in m 3 / h,c w It represents the specific heat capacity of water, kJ / (kg·℃), t2 and t1 represent the inlet and outlet temperatures of circulating water, in ℃, and (t2-t1) is the inlet and outlet water temperature difference.

[0052] The annual adjustable range of circulating water volume is generally ±15% of the design water volume. According to the inverse relationship, the inlet and outlet water temperature difference also has a range. The air-water ratio interval that satisfies the water temperature difference range can be calculated from the environmental parameters (atmospheric pressure, dry bulb temperature, wet bulb temperature). This air-water ratio interval is the annual operating range of the cooling tower. The air-water ratio is the ratio of air volume to water volume, see formula (2). The air volume range can be known from the circulating water volume.

[0053]

[0054] Among them, Q m represents the water mass flow rate in kg / h; ρ1 represents the inlet dry air density in kg / m 3 , G represents the volume flow rate of dry air entering the tower, in m 3 / h.

[0055] At this point, such an air-to-water ratio range can make the cooling tower meet the process requirements. Next, we need to find the guidance air volume and guidance water volume with the highest cooling tower efficiency, the lowest energy consumption and an air-to-water ratio that meets this range (in this article, the air volume at the optimal operating point is called the guidance air volume, and the water volume is called the guidance water volume).

[0056] The first is to solve the cooling tower efficiency, which involves the collection of parameters that characterize the operating conditions of the cooling tower, which are divided into design parameters and real-time parameters. The design parameters include fan shaft power, air volume, water volume, single tower length and width, packing installation height, and packing thermal performance. The measured parameters include atmospheric pressure, dry bulb temperature, wet bulb temperature, inlet water temperature, outlet water temperature, fan shaft power, and water volume. The calculation process is as follows: Figure 1 As shown (gas-water ratio and water density are intermediate values), the following steps are included:

[0057] Step 1, determine the air volume of a single tower. The cooling tower fan adopts frequency conversion regulation. The air volume is solved according to the similarity law of fan shaft power and air volume. The fan operating shaft power is calculated from the frequency converter.

[0058] Step 2: Input known design parameters and measured parameters to calculate the characteristic number N' of the filler. The formula is as follows:

[0059] N'=Aλ m (3);

[0060] Among them, A and m characterize the performance of the packing. Different packing types have empirical constants. λ can be obtained from the measured air volume and water volume. The measured air volume is obtained by step 1, and the measured water volume is measured by a flow sensor.

[0061] Step 3: The cooling number N can be calculated from the real-time parameters of atmospheric pressure, dry bulb temperature, wet bulb temperature, inlet water temperature, outlet water temperature, and the measured air volume and water volume in steps 1 and 2. The formula is as follows:

[0062]

[0063] Among them, C W represents the specific heat capacity of water, in kj / (kg·k); Δt represents the difference between the measured inlet temperature and the assumed outlet temperature; h″ c1 It indicates the saturated air enthalpy under the condition of tower water temperature and 0.1Δt, kJ / kg(DA), h G1Indicates the corrected specific enthalpy of air at the first point, kJ / kg(DA), h″ c2 It indicates the saturated air enthalpy under the condition of tower water temperature and 0.4Δt, kJ / kg(DA), h G2 Indicates the corrected specific enthalpy of air at the second point, kJ / kg(DA), h″ c3 Indicates the saturated air enthalpy under the condition of the difference between the inlet water temperature and 0.4Δt, kJ / kg (DA), h G3 Indicates the corrected specific enthalpy of air at the third point, kJ / kg(DA), h″ c4 Indicates the saturated air enthalpy under the condition of the difference between the inlet water temperature and 0.1Δt, kJ / kg (DA), h G4 It represents the corrected specific enthalpy of air at the third point, kJ / kg (DA);

[0064] Step 4, assuming the outlet water temperature, calculate the cooling number N, and iterate until the difference between the cooling number and the characteristic number meets the approximate condition, and obtain the calculated outlet water temperature, such as Figure 2 As shown, the cooling tower efficiency is determined by the following formula:

[0065]

[0066] Where η represents the cooling tower efficiency; Δt t Indicates the actual measured difference between the inlet and outlet water temperatures

[0067] st

[0068] Value, Δt d Indicates the difference between the measured water inlet temperature and the theoretically calculated water outlet temperature.

[0069] The second is to solve the energy consumption of the cooling tower. The power consumption of the fan motor can be directly obtained through the frequency converter, which is N1. The energy consumption of the water volume is determined by the water flow at the pressure measuring point of the tower. The formula is as follows:

[0070] N2=Q s ×P (6);

[0071] Among them, N2 represents the work capacity of the upper tower flow, the unit is W, Q s Indicates flow rate, in m 3 / s, P represents the pressure at that point, the unit is Pa, and both flow rate and pressure are actually measured values ​​by the sensor.

[0072] In this way, a coefficient was established with the measured air volume and the measured water volume as independent variables and the cooling tower efficiency η as the independent variable. stThe objective function that characterizes the operating status of the cooling tower throughout the year takes energy consumption (N1+N2) as dependent variables. The cooling tower staff can freely adjust the air volume and water volume within the air-water ratio range according to this objective, so that the cooling tower operates under the guidance of air volume and water volume, and always ensures that the heat dissipation load meets the process.

[0073] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0074] Example 1

[0075] The whole year cooling tower optimization operation method is to obtain the basic parameters of the cooling tower for calculation, obtain the parameters that characterize the operation status of the cooling tower, and establish a cooling tower efficiency η with the measured air volume and the measured water volume as independent variables. st The objective function that characterizes the operating status of the cooling tower throughout the year takes energy consumption N1+N2 as dependent variables. Under the premise of ensuring the heat dissipation load of the cooling tower, the efficiency and energy consumption of the cooling tower are calculated to obtain the guiding air volume and guiding water volume, thereby controlling the efficiency of the cooling tower.

[0076] Please follow the steps below to implement:

[0077] Step 1: Obtain basic parameters of the cooling tower, including design parameters and real-time parameters;

[0078] Step 2: Take the cooling tower heat dissipation load Q as the standard to meet the process side requirements and define the circulating water volume Q v The annual adjustable range is ±15% of the designed water volume, and the inlet and outlet water temperature difference range is calculated accordingly;

[0079] Step 3: Calculate the air-water ratio interval λ of the cooling tower for the whole year according to the inlet and outlet water temperature difference range;

[0080] Step 4: Establish a model with measured air volume and measured water volume as independent variables and cooling tower efficiency η st The objective function that characterizes the annual operation status of the cooling tower with energy consumption (N1+N2) as the dependent variable;

[0081] Step 5, by using the objective function obtained in step 4, obtain the guiding air volume and guiding water volume with the highest cooling tower efficiency, the lowest energy consumption and the air-water ratio satisfying the air-water ratio interval λ;

[0082] Step 6: Obtain two-dimensional data consisting of air volume and water volume of multiple groups of cooling tower efficiency and energy consumption through calculation. Determine the point with the highest efficiency and the lowest energy consumption as the optimal operating point by comparing the data. At this point, the operation adjustment of the cooling tower is completed.

[0083] Example 2

[0084] The whole year cooling tower optimization operation method is to obtain the basic parameters of the cooling tower for calculation, obtain the parameters that characterize the operation status of the cooling tower, and establish a cooling tower efficiency η with the measured air volume and the measured water volume as independent variables.st The objective function that characterizes the operating status of the cooling tower throughout the year takes energy consumption N1+N2 as dependent variables. Under the premise of ensuring the heat dissipation load of the cooling tower, the efficiency and energy consumption of the cooling tower are calculated to obtain the guiding air volume and guiding water volume, thereby controlling the efficiency of the cooling tower.

[0085] Please follow the steps below to implement:

[0086] Step 1: Obtain basic parameters of the cooling tower, including design parameters and real-time parameters;

[0087] The design parameters include fan shaft power, air volume, water volume, single tower length and width, packing installation height, and packing thermal performance, which are the design basis of the cooling tower. The design parameters mentioned in this article refer to one of these parameters. The real-time parameters are obtained by sensors, including atmospheric pressure, dry bulb temperature, wet bulb temperature, inlet water temperature, outlet water temperature, fan shaft real-time power, and real-time water volume. The real-time operating air volume is indirectly calculated.

[0088] Step 2: Take the cooling tower heat dissipation load Q as the standard to meet the process side requirements and define the circulating water volume Q v The annual adjustable range is ±15% of the designed water volume, and the inlet and outlet water temperature difference range is calculated accordingly;

[0089] Step 3: Calculate the air-water ratio interval λ of the cooling tower for the whole year according to the inlet and outlet water temperature difference range;

[0090] Step 4: Establish a model with measured air volume and measured water volume as independent variables and cooling tower efficiency η st The objective function that characterizes the annual operation status of the cooling tower with energy consumption (N1+N2) as the dependent variable;

[0091] Step 5, by using the objective function obtained in step 4, obtain the guiding air volume and guiding water volume with the highest cooling tower efficiency, the lowest energy consumption and the air-water ratio satisfying the air-water ratio interval λ;

[0092] Step 6: Obtain two-dimensional data consisting of air volume and water volume of multiple groups of cooling tower efficiency and energy consumption through calculation. Determine the point with the highest efficiency and the lowest energy consumption as the optimal operating point by comparing the data. At this point, the operation adjustment of the cooling tower is completed.

[0093] Example 3

[0094] The whole year cooling tower optimization operation method is to obtain the basic parameters of the cooling tower for calculation, obtain the parameters that characterize the operation status of the cooling tower, and establish a cooling tower efficiency η with the measured air volume and the measured water volume as independent variables. st The objective function that characterizes the operating status of the cooling tower throughout the year takes energy consumption N1+N2 as dependent variables. Under the premise of ensuring the heat dissipation load of the cooling tower, the efficiency and energy consumption of the cooling tower are calculated to obtain the guiding air volume and guiding water volume, thereby controlling the efficiency of the cooling tower.

[0095] Please follow the steps below to implement:

[0096] Step 1: Obtain basic parameters of the cooling tower, including design parameters and real-time parameters;

[0097] The design parameters include fan shaft power, air volume, water volume, single tower length and width, packing installation height, and packing thermal performance, which are the design basis of the cooling tower. The design parameters mentioned in this article refer to one of these parameters. The real-time parameters are obtained by sensors, including atmospheric pressure, dry bulb temperature, wet bulb temperature, inlet water temperature, outlet water temperature, fan shaft real-time power, and real-time water volume. The real-time operating air volume is indirectly calculated.

[0098] Step 2: Take the cooling tower heat dissipation load Q as the standard to meet the process side requirements and define the circulating water volume Q v The annual adjustable range is ±15% of the designed water volume, and the inlet and outlet water temperature difference range is calculated accordingly;

[0099] Step 2 is as follows:

[0100] Ensure that the cooling tower heat dissipation load Q is constant to meet the process side requirements, that is, the water volume is inversely proportional to the inlet and outlet water temperature difference, see formula (1):

[0101] Q=Q v ×c w ×(t2-t1) (1)

[0102] Where Q represents the cooling tower heat dissipation load in kW, Q v Indicates the circulating water volume, in m 3 / h,c w represents the specific heat capacity of water, kJ / (kg·℃), t2 and t1 represent the inlet and outlet temperatures of circulating water, in ℃, and (t2-t1) is the inlet and outlet water temperature difference;

[0103] The annual adjustable range of circulating water volume is generally ±15% of the designed water volume. The inlet and outlet water temperature difference range can be obtained based on the inverse relationship.

[0104] Step 3: Calculate the air-water ratio interval λ of the cooling tower for the whole year according to the inlet and outlet water temperature difference range;

[0105] Step 4: Establish a model with measured air volume and measured water volume as independent variables and cooling tower efficiency η st The objective function that characterizes the annual operation status of the cooling tower with energy consumption (N1+N2) as the dependent variable;

[0106] Step 5, by using the objective function obtained in step 4, obtain the guiding air volume and guiding water volume with the highest cooling tower efficiency, the lowest energy consumption and the air-water ratio satisfying the air-water ratio interval λ;

[0107] Step 6: Obtain two-dimensional data consisting of air volume and water volume of multiple groups of cooling tower efficiency and energy consumption through calculation. Determine the point with the highest efficiency and the lowest energy consumption as the optimal operating point by comparing the data. At this point, the operation adjustment of the cooling tower is completed.

[0108] Example 4

[0109] The whole year cooling tower optimization operation method is to obtain the basic parameters of the cooling tower for calculation, obtain the parameters that characterize the operation status of the cooling tower, and establish a cooling tower efficiency η with the measured air volume and the measured water volume as independent variables. st The objective function that characterizes the operating status of the cooling tower throughout the year takes energy consumption N1+N2 as dependent variables. Under the premise of ensuring the heat dissipation load of the cooling tower, the efficiency and energy consumption of the cooling tower are calculated to obtain the guiding air volume and guiding water volume, thereby controlling the efficiency of the cooling tower.

[0110] Please follow the steps below to implement:

[0111] Step 1: Obtain basic parameters of the cooling tower, including design parameters and real-time parameters;

[0112] The design parameters include fan shaft power, air volume, water volume, single tower length and width, packing installation height, and packing thermal performance, which are the design basis of the cooling tower. The design parameters mentioned in this article refer to one of these parameters. The real-time parameters are obtained by sensors, including atmospheric pressure, dry bulb temperature, wet bulb temperature, inlet water temperature, outlet water temperature, fan shaft real-time power, and real-time water volume. The real-time operating air volume is indirectly calculated.

[0113] Step 2: Take the cooling tower heat dissipation load Q as the standard to meet the process side requirements and define the circulating water volume Q v The annual adjustable range is ±15% of the designed water volume, and the inlet and outlet water temperature difference range is calculated accordingly;

[0114] Step 2 is as follows:

[0115] Ensure that the cooling tower heat dissipation load Q is constant to meet the process side requirements, that is, the water volume is inversely proportional to the inlet and outlet water temperature difference, see formula (1):

[0116] Q=Q v ×c w ×(t2-t1) (1)

[0117] Where Q represents the cooling tower heat dissipation load in kW, Q v Indicates the circulating water volume, in m 3 / h,c w represents the specific heat capacity of water, kJ / (kg·℃), t2 and t1 represent the inlet and outlet temperatures of circulating water, in ℃, and (t2-t1) is the inlet and outlet water temperature difference;

[0118] The annual adjustable range of circulating water volume is generally ±15% of the designed water volume. The inlet and outlet water temperature difference range can be obtained based on the inverse relationship.

[0119] Step 3: Calculate the air-water ratio interval λ of the cooling tower for the whole year according to the inlet and outlet water temperature difference range;

[0120] Step 3 is as follows: Calculate an air-water ratio interval λ that satisfies the inlet and outlet water temperature difference range based on environmental parameters including atmospheric pressure, dry-bulb temperature, and wet-bulb temperature;

[0121] The air-water ratio range is the operating range of the cooling tower throughout the year. The air-water ratio is the ratio of air volume to water volume. The air volume range can be known from the circulating water volume. For details, see formula (2):

[0122]

[0123] Among them, Q m represents the water mass flow rate in kg / h; ρ1 represents the inlet dry air density in kg / m 3 , G represents the volume flow rate of dry air entering the tower, in m 3 / h;

[0124] Step 4: Establish a model with measured air volume and measured water volume as independent variables and cooling tower efficiency η st The objective function that characterizes the annual operation status of the cooling tower with energy consumption (N1+N2) as the dependent variable;

[0125] Step 5, by using the objective function obtained in step 4, obtain the guiding air volume and guiding water volume with the highest cooling tower efficiency, the lowest energy consumption and the air-water ratio satisfying the air-water ratio interval λ;

[0126] Step 6: Obtain two-dimensional data consisting of air volume and water volume of multiple groups of cooling tower efficiency and energy consumption through calculation. Determine the point with the highest efficiency and the lowest energy consumption as the optimal operating point by comparing the data. At this point, the operation adjustment of the cooling tower is completed.

[0127] Example 5

[0128] The whole year cooling tower optimization operation method is to obtain the basic parameters of the cooling tower for calculation, obtain the parameters that characterize the operation status of the cooling tower, and establish a cooling tower efficiency η with the measured air volume and the measured water volume as independent variables. st The objective function that characterizes the operating status of the cooling tower throughout the year takes energy consumption N1+N2 as dependent variables. Under the premise of ensuring the heat dissipation load of the cooling tower, the efficiency and energy consumption of the cooling tower are calculated to obtain the guiding air volume and guiding water volume, thereby controlling the efficiency of the cooling tower.

[0129] Please follow the steps below to implement:

[0130] Step 1: Obtain basic parameters of the cooling tower, including design parameters and real-time parameters;

[0131] The design parameters include fan shaft power, air volume, water volume, single tower length and width, packing installation height, and packing thermal performance, which are the design basis of the cooling tower. The design parameters mentioned in this article refer to one of these parameters. The real-time parameters are obtained by sensors, including atmospheric pressure, dry bulb temperature, wet bulb temperature, inlet water temperature, outlet water temperature, fan shaft real-time power, and real-time water volume. The real-time operating air volume is indirectly calculated.

[0132] Step 2: Take the cooling tower heat dissipation load Q as the standard to meet the process side requirements and define the circulating water volume Q v The annual adjustable range is ±15% of the designed water volume, and the inlet and outlet water temperature difference range is calculated accordingly;

[0133] Step 2 is as follows:

[0134] Ensure that the cooling tower heat dissipation load Q is constant to meet the process side requirements, that is, the water volume is inversely proportional to the inlet and outlet water temperature difference, see formula (1):

[0135] Q=Q v ×c w ×(t2-t1) (1);

[0136] Where Q represents the cooling tower heat dissipation load in kW, Q v Indicates the circulating water volume, in m 3 / h,c w represents the specific heat capacity of water, kJ / (kg·℃), t2 and t1 represent the inlet and outlet temperatures of circulating water, in ℃, and (t2-t1) is the inlet and outlet water temperature difference;

[0137] The annual adjustable range of circulating water volume is generally ±15% of the designed water volume. The inlet and outlet water temperature difference range can be obtained based on the inverse relationship.

[0138] Step 3: Calculate the air-water ratio interval λ of the cooling tower for the whole year according to the inlet and outlet water temperature difference range;

[0139] Step 3 is as follows: Calculate an air-water ratio interval λ that satisfies the inlet and outlet water temperature difference range based on environmental parameters including atmospheric pressure, dry-bulb temperature, and wet-bulb temperature;

[0140] The air-water ratio range is the operating range of the cooling tower throughout the year. The air-water ratio is the ratio of air volume to water volume. The air volume range can be known from the circulating water volume. For details, see formula (2):

[0141]

[0142] Among them, Q m represents the water mass flow rate in kg / h; ρ1 represents the inlet dry air density in kg / m 3, G represents the volume flow rate of dry air entering the tower, in m 3 / h;

[0143] Step 4: Establish a model with measured air volume and measured water volume as independent variables and cooling tower efficiency η st The objective function that characterizes the annual operation status of the cooling tower with energy consumption (N1+N2) as the dependent variable;

[0144] Step 4 is as follows:

[0145] Step 4.1, determine the measured air volume during the operation of a single tower. The cooling tower fan adopts frequency conversion regulation. The measured air volume is solved according to the similarity law between the fan shaft power and the air volume. The fan shaft power is calculated from the frequency converter.

[0146] Step 4.2: Input known design parameters and measured parameters to calculate the characteristic number N' of the filler. For details, see formula (3):

[0147] N'=Aλ m (3);

[0148] Among them, A and m characterize the packing performance, different packing types have empirical constants, and λ is the gas-water ratio interval;

[0149] Step 4.3, the measured water volume is measured by the flow sensor based on the real-time parameters of atmospheric pressure, dry bulb temperature, wet bulb temperature, inlet water temperature, and outlet water temperature. The measured air volume in step 4.1 is assumed to be the outlet temperature, and the cooling number N is calculated. For details, see formula (4):

[0150]

[0151] Among them, C W represents the specific heat capacity of water, in kj / (kg·k); Δt represents the difference between the measured inlet temperature and the assumed outlet temperature; h″ c1 It indicates the saturated air enthalpy under the condition of tower water temperature and 0.1Δt, kJ / kg(DA), h G1 Indicates the corrected specific enthalpy of air at the first point, kJ / kg(DA), h″ c2 It indicates the saturated air enthalpy under the condition of tower water temperature and 0.4Δt, kJ / kg(DA), h G2 Indicates the corrected specific enthalpy of air at the second point, kJ / kg(DA), h″ c3 Indicates the saturated air enthalpy under the condition of the difference between the inlet water temperature and 0.4Δt, kJ / kg (DA), h G3 Indicates the corrected specific enthalpy of air at the third point, kJ / kg(DA), h″ c4 Indicates the saturated air enthalpy under the condition of the difference between the inlet water temperature and 0.1Δt, kJ / kg (DA), hG4 It represents the corrected specific enthalpy of air at the third point, kJ / kg (DA);

[0152] Step 4.4, calculate the cooling number N by assuming the outlet water temperature, and iterate until |N'-N|≤0.01, and obtain the calculated outlet water temperature, and calculate the cooling tower efficiency, as shown in formula (5):

[0153]

[0154] Among them, η st Indicates cooling tower efficiency; Δt t Indicates the actual measured difference between the tower inlet temperature and the tower outlet temperature, Δt d Indicates the difference between the measured water inlet temperature and the theoretically calculated water outlet temperature;

[0155] Step 4.5: Calculate the energy consumption of the cooling tower. The power consumption of the fan motor can be directly obtained through the frequency converter, which is N1. The energy consumption of the water volume is determined by the water flow at the pressure measuring point above the tower. For details, see formula (6):

[0156] N2=Q s ×P (6);

[0157] Among them, N2 represents the work capacity of the upper tower flow, the unit is W, Q s Indicates the flow rate at this point, in m 3 / s, P represents the pressure at that point, the unit is Pa, the flow rate and pressure are both the actual measured values ​​of the sensor;

[0158] Step 4.6: Combine formulas (3), (4), (5), and (6) to obtain the objective function that characterizes the annual operation status of the cooling tower;

[0159] Step 5, by using the objective function obtained in step 4, obtain the guiding air volume and guiding water volume with the highest cooling tower efficiency, the lowest energy consumption and the air-water ratio satisfying the air-water ratio interval λ;

[0160] The energy consumption calculation in step 4.5 is based on the traditional calculation of fan energy consumption, and the calculation of the working capacity of the upper tower flow is added to comprehensively evaluate the cooling tower energy consumption; the measuring point can be installed at any position of the upper tower pipeline, and the specific measurement method can be adapted to local conditions.

[0161] Step 6: Obtain two-dimensional data consisting of air volume and water volume of multiple groups of cooling tower efficiency and energy consumption through calculation. Determine the point with the highest efficiency and the lowest energy consumption as the optimal operating point by comparing the data. At this point, the operation adjustment of the cooling tower is completed.

[0162] Example 6

[0163] In order to verify the year-round cooling tower optimization operation method of the present invention, a cooling tower of a domestic circulating water field is used as an experiment. The plant has a total of three water fields, the water pump model is SN1000-X20B / 1020, and the flow rate is 15953m 3 / h, head 34.4m, fan is D8750, cooling tower model is the same, single tower design circulating water volume is 5000m 3 / h, the designed air volume is 2.78 million m 3 / h, the design temperature difference is 10℃, and the same filler was replaced one year ago. One tower was taken from each water field, and the experimental time was 8.1-8.31. The average dry bulb temperature was 32.44℃, and the wet bulb temperature was 27.99℃. It was calculated that 0.702 was the best gas-water ratio. The heat dissipation load of the three towers remained consistent. One tower used the control scheme of the present invention, and the other two towers used frequency conversion + outlet water temperature control. The best gas-water ratio obtained in the control of the present invention is 0.702, and the water volume adjustment range is 4500-5500m 3 / h, the air volume adjustment range is 2.3 to 3.1 million m 3 / h, such as Figure 3 As shown in the figure, the point with the lowest energy consumption and the highest efficiency is found in this two-dimensional coordinate area. After continuous debugging, the guiding air volume is 2.74 million m 3 / h, the guidance water volume is 4600m 3 / h. The water volumes of the other two units remain the same. The average hourly results are shown in the table below.

[0164] Tower No. F1002 F2002 F3008 Control scheme Control scheme of the present invention Frequency conversion + water outlet temperature control Frequency conversion + water outlet temperature control Circulation flow (m3 / h) 4600 4800 5350 Temperature difference between inlet and outlet tower(℃) 10.87 10.42 9.35 Cooling tower efficiency (%) 109％ 104％ 93.5％ Cooling tower energy consumption (kW·h) 331.24 345.88 436.73 Conclusion of operating condition points optimal Slightly Serious Mistake

[0165] Under the experimental conditions, the average monthly outlet water temperature of the three towers is 32.2-32.4℃, which meets the process production requirements, but the energy consumption is completely different. F3008 and F2002 maintain the original frequency conversion + outlet water temperature control scheme, and the upper tower flow is determined by the water field staff according to the consistency of the upper tower valve opening, resulting in a huge difference in energy consumption between the two towers. F1002, which adopts the control scheme of the present invention, uses the standard of combining cooling tower efficiency and energy consumption to continuously search for the best point operating condition. Compared with F2002, it ensures that the heat dissipation load remains unchanged and the energy consumption is reduced by 4.23%, which is quite objective throughout the year.

Claims

1. The method for optimizing the operation of cooling towers throughout the year is characterized in that: The basic parameters of the cooling tower are obtained for calculation, and the parameters that characterize the operating status of the cooling tower are obtained. The measured air volume and the measured water volume are used as independent variables, and the cooling tower efficiency η is used as the st The objective function that characterizes the annual operation status of the cooling tower is established with energy consumption (N1+N2) as the dependent variables. Under the premise of ensuring the heat dissipation load of the cooling tower, the efficiency and energy consumption of the cooling tower are calculated to obtain the guiding air volume and guiding water volume, thereby controlling the efficiency of the cooling tower.

2. The method for optimizing cooling tower operation throughout the year according to claim 1, characterized in that: Please follow the steps below to implement: Step 1: Obtain basic parameters of the cooling tower, including design parameters and real-time parameters; Step 2: Take the cooling tower heat dissipation load Q as the standard to meet the process side requirements and define the circulating water volume Q v The annual adjustable range is ±15% of the designed water volume, and the inlet and outlet water temperature difference range is calculated accordingly; Step 3: Calculate the air-water ratio interval λ of the cooling tower for the whole year according to the inlet and outlet water temperature difference range; Step 4: Establish a model with measured air volume and measured water volume as independent variables and cooling tower efficiency η st The objective function that characterizes the annual operation status of the cooling tower is taken as the dependent variable, with energy consumption (N1+N2); Step 5, by using the objective function obtained in step 4, obtain the guiding air volume and guiding water volume with the highest cooling tower efficiency, the lowest energy consumption and the air-water ratio satisfying the air-water ratio interval λ; Step 6: Obtain two-dimensional data consisting of air volume and water volume of multiple groups of cooling tower efficiency and energy consumption through calculation. Determine the point with the highest efficiency and the lowest energy consumption as the optimal operating point by comparing the data. At this point, the operation adjustment of the cooling tower is completed.

3. The method for optimizing cooling tower operation throughout the year according to claim 2, characterized in that: In step 1, the design parameters include fan shaft power, air volume, water volume, single tower length and width, filler installation height, and filler thermal performance, which are the design basis of the cooling tower. The design parameters mentioned in this article refer to one of these parameters; the real-time parameters are obtained using sensors, including atmospheric pressure, dry-bulb temperature, wet-bulb temperature, inlet water temperature, outlet water temperature, fan shaft real-time power, and real-time water volume, among which the real-time operating air volume is indirectly calculated.

4. The method for optimizing cooling tower operation throughout the year according to claim 3, characterized in that: The step 2 is specifically as follows: Ensure that the cooling tower heat dissipation load Q is constant to meet the process side requirements, that is, the water volume is inversely proportional to the inlet and outlet water temperature difference, see formula (1): Q=Q v ×c w ×(t2-t1) (1) Where Q represents the cooling tower heat dissipation load in kW, Q v Indicates the circulating water volume, in m 3 / h,c w represents the specific heat capacity of water, kJ / (kg·℃), t2 and t1 represent the inlet and outlet temperatures of circulating water, in ℃, and (t2-t1) is the inlet and outlet water temperature difference; The annual adjustable range of circulating water volume is generally ±15% of the design water volume. The inlet and outlet water temperature difference range can be obtained based on the inverse relationship.

5. The method for optimizing cooling tower operation throughout the year according to claim 4, characterized in that: The step 3 is specifically as follows: calculating an air-water ratio interval λ that satisfies the inlet and outlet water temperature difference range based on environmental parameters including atmospheric pressure, dry-bulb temperature, and wet-bulb temperature; The air-water ratio range is the operating range of the cooling tower throughout the year. The air-water ratio is the ratio of air volume to water volume. The air volume range can be known from the circulating water volume. For details, see formula (2): Among them, Q m represents the water mass flow rate in kg / h; ρ1 represents the inlet dry air density in kg / m 3 , G represents the volume flow rate of dry air entering the tower, in m 3 / h.

6. The method for optimizing cooling tower operation throughout the year according to claim 5, characterized in that: The step 4 is specifically as follows: Step 4.1, determine the measured air volume during the operation of a single tower. The cooling tower fan adopts frequency conversion regulation. The measured air volume is solved according to the similarity law between the fan shaft power and the air volume. The fan shaft power is calculated from the frequency converter. Step 4.2: Input known design parameters and measured parameters to calculate the characteristic number N' of the filler. For details, see formula (3): N'=Aλ m (3) Among them, A and m characterize the packing performance, different packing types have empirical constants, and λ is the gas-water ratio interval; Step 4.3, the measured water volume is measured by the flow sensor based on the real-time parameters of atmospheric pressure, dry bulb temperature, wet bulb temperature, inlet water temperature, and outlet water temperature. The measured air volume in step 4.1 is assumed to be the outlet temperature, and the cooling number N is calculated. For details, see formula (4): Among them, C W represents the specific heat capacity of water, in kj / (kg·k); Δt represents the difference between the measured inlet temperature and the assumed outlet temperature; h″ c1 It indicates the saturated air enthalpy under the condition of tower water temperature and 0.1Δt, kJ / kg(DA), h G1 Indicates the corrected specific enthalpy of air at the first point, kJ / kg(DA), h″ c2 It indicates the saturated air enthalpy under the condition of tower water temperature and 0.4Δt, kJ / kg(DA), h G2 Indicates the corrected specific enthalpy of air at the second point, kJ / kg(DA), h″ c3 Indicates the saturated air enthalpy under the condition of the difference between the inlet water temperature and 0.4Δt, kJ / kg (DA), h G3 Indicates the corrected specific enthalpy of air at the third point, kJ / kg(DA), h″ c4 Indicates the saturated air enthalpy under the condition of the difference between the inlet water temperature and 0.1Δt, kJ / kg (DA), h G4 It represents the corrected specific enthalpy of air at the third point, kJ / kg (DA); Step 4.4, calculate the cooling number N by assuming the outlet water temperature, and iterate continuously until |N'-N|≤0.01, obtain the calculated outlet water temperature, and calculate the cooling tower efficiency, as shown in formula (5): Among them, η st Indicates cooling tower efficiency; Δt t Indicates the actual measured difference between the tower inlet temperature and the tower outlet temperature, Δt d Indicates the difference between the measured water inlet temperature and the theoretically calculated water outlet temperature; Step 4.5: Calculate the energy consumption of the cooling tower. The power consumption of the fan motor can be directly obtained through the frequency converter, which is N1. The energy consumption of the water volume is determined by the water flow at the pressure measuring point above the tower. For details, see formula (6): N2=Q s ×P (6) Among them, N2 represents the work capacity of the upper tower flow, the unit is W, Q s Indicates the flow rate at this point, in m 3 / s, P represents the pressure at that point, the unit is Pa, the flow rate and pressure are both the actual measured values ​​of the sensor; Step 4.6: Combine equations (3), (4), (5), and (6) to obtain the objective function that characterizes the operating conditions of the cooling tower throughout the year.

7. The method for optimizing cooling tower operation throughout the year according to claim 6, characterized in that: The energy consumption calculation in step 4.5 is based on the traditional calculation of fan energy consumption, and the calculation of the working capacity of the upper tower flow is added to comprehensively evaluate the cooling tower energy consumption.

8. The method for optimizing cooling tower operation throughout the year according to claim 6, characterized in that: The measuring point in step 4.5 can be installed at any position of the upper tower pipeline, and the specific measuring method can be adapted to local conditions.

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