A method, device and control method for evaluating cooling effect of circulating water system

Abstract

The present invention discloses an evaluation method, device and control method for the cooling effect of a circulating water system, comprising: collecting outdoor dry-bulb temperature, relative humidity and atmospheric pressure, upper tower temperature of a cooling tower, upper tower cooling water flow, lower tower temperature and operation data of a fan; calculating cooling tower air volume percentage and wet-bulb temperature; calculating a polynomial of the lower tower temperature of the cooling tower related to the wet-bulb temperature, upper tower temperature, upper tower cooling water flow and cooling tower air volume percentage; calculating the corresponding lower tower temperature according to the polynomial combined with the currently collected parameters; calculating the cooling number of the cooling tower under the actual working condition; calculating the cooling number under the standard working condition, calculating the lower tower temperature when the cooling number under the actual working condition is corrected to the cooling number under the standard working condition, and calculating the cooling capacity of the cooling tower through the upper tower temperature and the lower tower temperature under the standard working condition and the corrected lower tower temperature. The present invention realizes online evaluation of the cooling effect of each cooling tower of a cooling tower group, keeps track of the current performance of each cooling tower at any time, and realizes efficient operation of the circulating water system.

Description

Technical Field

[0001] The present invention relates to the field of industrial control technology, and in particular to an evaluation method, a device and a control method for the cooling effect of a circulating water system. Background Art

[0002] Cooling tower is an important equipment for circulating water system to discharge heat to the atmosphere. Circulating water and air are in direct contact and exchange heat and mass in the tower. The heat dissipation effect directly affects the operating efficiency of the circulating water system.

[0003] In industrial plants, construction is often carried out in phases. Therefore, there may be cooling towers with different factory times and different tower forms (crossflow, counterflow, round, square, etc.) running in parallel in the circulating water system. How to maximize cooling efficiency by controlling the number of cooling towers, the number of cooling tower fans and the frequency under the given environmental parameters (outdoor dry bulb temperature, relative humidity, atmospheric pressure) and the total flow of cooling water is a goal of optimizing the operation of the circulating water system and a problem that needs to be solved. In actual operation, the cooling tower group has only a small number of sensors for monitoring, such as the upper tower mother pipe pressure sensor and water temperature sensor; the lower tower mother pipe water temperature sensor, which cannot effectively monitor each cooling tower. Therefore, the specific cooling effect, energy consumption and whether there is room for optimization of each cooling tower are unknown, resulting in the inability to provide valuable basis for the optimized operation of the cooling tower group. Summary of the invention

[0004] The present invention aims at at least one defect in the prior art and provides a method for evaluating the cooling effect of a circulating water system. The method realizes online evaluation of the cooling effect of each cooling tower in a cooling tower group, and the current performance of each cooling tower can be understood at any time, thereby realizing efficient operation of the circulating water system.

[0005] In order to solve the above technical problems, the present invention is solved by the following technical solutions:

[0006] (I) A method for evaluating the cooling effect of a circulating water system, comprising the following steps:

[0007] In response to a time trigger or a passive trigger, the outdoor dry-bulb temperature, relative humidity and atmospheric pressure, as well as the upper tower temperature of each cooling tower, the upper tower cooling water flow, the lower tower temperature of each cooling tower, and the operating data of the fans in each cooling tower are collected;

[0008] Calculate the cooling tower air volume percentage based on the fan operating data, and calculate the ambient wet bulb temperature based on the outdoor dry bulb temperature, relative humidity and atmospheric pressure;

[0009] By fitting the curve, a polynomial is obtained that the lower tower temperature of each cooling tower is related to the ambient wet bulb temperature, the upper tower temperature, the upper tower cooling water flow rate and the cooling tower air volume percentage;

[0010] According to the polynomial of the lower tower temperature of each cooling tower, combined with the currently collected upper tower temperature, upper tower flow, ambient wet bulb temperature and air volume percentage, the corresponding lower tower temperature is calculated;

[0011] According to the cooling capacity calculation process of the open cooling tower, the cooling number of the cooling tower under the actual working condition is calculated; the cooling number under the standard working condition is calculated according to the standard working condition type of the current cooling tower, and the lower tower temperature when the cooling number under the actual working condition is corrected to the cooling number under the standard working condition is calculated as the corrected lower tower temperature. The cooling capacity of the cooling tower is calculated by the upper tower temperature and the lower tower temperature under the standard working condition, and the corrected lower tower temperature, and the cooling effect is evaluated according to the cooling capacity of the cooling tower.

[0012] Beneficial effects 1. The standard of cooling towers has a performance index for each cooling tower shipped out of the factory, that is, the cooling capacity under standard conditions should be greater than 95%. During the factory test phase, the water volume and air volume are constant, that is, the fan of this cooling tower is running at power frequency, and the water volume is basically supplied according to the standard water volume. However, the cooling capacity of the cooling tower will change with the environment, user usage and service life.

[0013] This application measures atmospheric pressure, outdoor dry bulb temperature, relative humidity, upper tower temperature and lower tower temperature, and then converts them into standard working conditions, calculates the lower tower temperature value under standard working conditions, and then calculates the cooling capacity of the cooling tower. Regularly / periodically evaluate the cooling capacity of each cooling tower to help users select cooling towers with good operating performance.

[0014] (II) The present application also proposes a device for evaluating the cooling effect of a circulating water system, comprising the following structure:

[0015] Outdoor temperature and humidity sensor, installed outside the air inlet of the cooling tower, used to collect outdoor dry-bulb temperature and relative humidity;

[0016] Atmospheric barometer, installed outside the air inlet of the cooling tower, used to collect local atmospheric pressure;

[0017] A dynamic balancing electric regulating valve is installed in the upper tower pipeline of each cooling tower, including a temperature sensor and a flow meter, which collects the upper tower temperature and the upper tower cooling water flow of each cooling tower in response to time triggering or passive triggering;

[0018] The lower tower temperature sensor is installed in the lower tower pipeline of each cooling tower to collect the lower tower temperature of each cooling tower;

[0019] Fan data acquisition unit, used to collect the operating data of the fans in each cooling tower;

[0020] The parameter calculation unit is used to calculate the ambient wet bulb temperature according to the outdoor dry bulb temperature, relative humidity and atmospheric pressure, and to calculate the cooling tower air volume percentage according to the operation data of the fan; the polynomial fitting unit is used to fit the lower tower temperature of each cooling tower to the polynomial of the ambient wet bulb temperature, the upper tower temperature, the upper tower cooling water flow and the cooling tower air volume percentage by means of a fitting curve;

[0021] The lower tower temperature calculation unit calculates the corresponding lower tower temperature according to the polynomial of the lower tower temperature of each cooling tower, combined with the currently collected upper tower temperature, upper tower flow, ambient wet bulb temperature and air volume percentage;

[0022] The lower tower temperature correction unit is used to calculate the cooling number of the cooling tower under the actual working condition according to the cooling capacity calculation process of the open cooling tower; calculate the cooling number under the standard working condition according to the standard working condition type of the current cooling tower, and calculate the lower tower temperature when the cooling number under the actual working condition is corrected to the cooling number under the standard working condition as the corrected lower tower temperature;

[0023] The cooling capacity calculation unit calculates the cooling capacity of the cooling tower through the upper tower temperature and the lower tower temperature under standard working conditions and the corrected lower tower temperature;

[0024] Evaluation unit, which evaluates the cooling effect according to the cooling capacity of the cooling tower.

[0025] (III) The present application also proposes a circulating water system control method, which combines the parameters calculated by the evaluation method of the cooling effect of the circulating water system to implement the following control method:

[0026] Regularly calculate the cooling capacity and energy efficiency level of each cooling tower, give priority to operating cooling towers with high energy efficiency levels, obtain the current standard cooling water volume, use the current standard cooling water volume to match the cooling water volume required by the cooling tower group, obtain the actual cooling water volume required by each cooling tower, adjust the water flow deviation on the cooling tower according to the actual cooling water volume required by each cooling tower, and adjust the opening of the dynamic balance electric control valve according to the deviation.

[0027] Adjust the frequency or start / stop status of the fan on each cooling tower by matching the air volume.

[0028] Beneficial Effect 2: This application realizes real-time control of water volume and air volume according to environmental and process requirements when the cooling tower is actually in operation. During optimized operation, the most appropriate amount of water is allocated to each cooling tower through the adjustment of the dynamic balancing valve, while ensuring hydraulic balance, which is the prerequisite for the optimal operation of the cooling tower group. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0030] Figure 1 Flow chart of comprehensive evaluation system for cooling effect of circulating water system

[0031] Reference numerals in the figure: cooling effect comprehensive evaluation system 1; cooling tower L 1 ~L n , Dynamically balanced electric regulating valve V 1 ~V n ; Lower tower temperature sensor T 21 ~T 2,n ; Cooling tower group upper tower main pipe water temperature sensor T 1 , cooling tower group lower tower main pipe water temperature sensor T 2 , atmospheric pressure gauge P a ;Outdoor temperature and humidity sensor HT1. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with embodiments. The following embodiments are for explanation of the present invention but the present invention is not limited to the following embodiments.

[0033] A method for evaluating the cooling effect of a circulating water system comprises the following steps:

[0034] In response to time trigger or passive trigger, collect outdoor dry bulb temperature T a , relative humidity and atmospheric pressure P, and each cooling tower L i Upper tower temperature T 1i , cooling water flow rate Q ci , and the lower tower temperature T of each cooling tower 2i , and the operating data of the fans in each cooling tower;

[0035] Calculate the cooling tower air volume percentage A based on the fan operating data ai , according to the outdoor atmospheric pressure P, dry bulb temperature T a and relative humidity Calculate the ambient wet bulb temperature T s ;

[0036] The lower tower temperature T of each cooling tower is fitted by fitting the curve 2i There is a polynomial for the ambient wet bulb temperature, upper tower temperature, upper tower cooling water flow, and cooling tower air volume percentage.

[0037] According to the polynomial of the lower tower temperature of each cooling tower, combined with the currently collected upper tower temperature, upper tower flow, ambient wet bulb temperature and air volume percentage, the corresponding lower tower temperature is calculated, hereinafter referred to as the first lower tower temperature.

[0038] According to the cooling capacity calculation process of the open cooling tower, the cooling number of the cooling tower under the actual working condition is calculated; the cooling number under the standard working condition is calculated according to the standard working condition type of the current cooling tower, and the lower tower temperature when the cooling number under the actual working condition is corrected to the cooling number under the standard working condition is calculated as the corrected lower tower temperature. The cooling capacity of the cooling tower is calculated by the upper tower temperature and the lower tower temperature under the standard working condition, and the corrected lower tower temperature, and the cooling effect is evaluated according to the cooling capacity of the cooling tower.

[0039] Generally speaking, the outdoor dry-bulb temperature T is obtained by timed acquisition. a , relative humidity Atmospheric pressure P, upper tower temperature T 1i , cooling water flow rate Q ci For example, collect data once every 5 seconds, once every 1 minute, etc. If you need to obtain real-time data before the collection time point, you can use external passive trigger configurations such as the collection button to achieve it.

[0040] Collect and calculate multiple groups of lower tower temperatures T 2i , upper tower temperature T 1i , flow rate on the tower Q ci , ambient wet bulb temperature Ts and air volume percentage A of each cooling tower ai , calculate the polynomial:

[0041] Exemplarily, the polynomial used in this application is as follows:

[0042] T 2i =a+bT s +cT 1i +dQ ci +eA ai

[0043] In the formula

[0044] T 2i —The i-th cooling tower L i Lower tower temperature, ℃;

[0045] T s —Ambient wet bulb temperature, °C;

[0046] T 1i —The i-th cooling tower L i Upper tower temperature, ℃;

[0047] Q ci —The i-th cooling tower Li Cooling water flow rate of upper tower, m 3 / h;

[0048] A ai —The i-th cooling tower L i Percentage of air volume;

[0049] a, b, c, d, e—fitting coefficients.

[0050] To find the fitting coefficient, the more frequent the data collection is and the more data is collected within the preset time, the more accurate the fitting coefficient will be.

[0051] In the above formula, for the outdoor ambient wet bulb temperature T s The optional calculation schemes include: Based on the outdoor dry bulb temperature T a (℃) and relative humidity Calculated with a psychrometric chart calculator or based on an approximate empirical formula Obtained by calculation.

[0052] The psychrometric chart is a graphical tool that shows the relationship between various properties of moist air, such as temperature, humidity, enthalpy, etc. By finding the point on the psychrometric chart that corresponds to atmospheric pressure, dry-bulb temperature, and relative humidity, the wet-bulb temperature and other related parameters can be read directly.

[0053] The approximate empirical formula is applicable to specific atmospheric pressure conditions. If the atmospheric pressure is significantly different from the standard atmospheric pressure, the influence of the measured atmospheric pressure needs to be considered for correction calculation.

[0054] The cooling tower L in the above formula i Air volume percentage A ai is the actual air volume Q ai Rated air volume The ratio of Q aij,max is the rated air volume of the jth fan in the i-th cooling tower, m 3 / h. Due to the difficulty in collecting actual air volume, this application discloses a method for collecting fan operation data to calculate the air volume percentage A ai as described below.

[0055] For example, take a brand of open cross-flow cooling tower available on the market as an example. Its user design operating conditions are wet bulb temperature 28°C, upper tower temperature 35.5°C, lower tower temperature 30.5°C, and rated cooling water volume 260m 3 / h, rated air volume is 191989m 3 / h, atmospheric pressure 100.5kPa.

[0056] In actual application, since both the cooling water pump and the cooling tower fan support variable frequency regulation, the cooling tower operates with variable water volume and variable air volume. The corresponding lower tower temperature polynomial is fitted through actual operation data:

[0057] T 2 =5.2589+0.2482*T s +0.6701*T 1 -0.0048*Q c -4.3446*A a .

[0058] Preferably, the method for calculating the cooling tower air volume percentage according to the operating data of the fan comprises:

[0059] When the fan is a variable frequency fan, the operating data of the fan in each cooling tower includes the start and stop status and the operating frequency. The air volume percentage A is calculated according to the following formula ai :

[0060]

[0061] In the formula

[0062] ω ij —The start and stop status of the jth variable frequency fan in the i-th cooling tower, "1" means running; "0" means stopping;

[0063] F ij —The operating frequency of the jth variable frequency fan in the i-th cooling tower, in Hz;

[0064] m—the number of variable frequency fans configured in the i-th cooling tower.

[0065] Preferably, the method for calculating the cooling tower air volume percentage according to the operating data of the fan comprises:

[0066] When the fan is a two-speed fan, the operating data of the fan in each cooling tower includes the start-stop state and the high and low speed states. The air volume percentage A is calculated according to the following formula: ai :

[0067]

[0068] In the formula

[0069] ω ij —The start and stop status of the jth two-speed fan in the i-th cooling tower,

[0070] μ ij —The high and low speed status of the j-th two-speed fan in the i-th cooling tower, "1" means high speed; "0.5" means low speed;

[0071] m—the number of two-speed fans configured in the i-th cooling tower.

[0072] Preferably, the method for calculating the cooling tower air volume percentage according to the operating data of the fan comprises:

[0073] When the fan is a power frequency fan, the operating data of the fan in each cooling tower includes the start and stop status. The air volume percentage A is calculated according to the following formula ai :

[0074]

[0075] In the formula

[0076] ω ij —The start and stop status of the jth power frequency fan in the i-th cooling tower, "1" means running; "0" means stopping;

[0077] m—the number of two-speed fans configured in the i-th cooling tower.

[0078] The method for calculating the first lower tower temperature specifically includes:

[0079] According to each cooling tower L i Lower tower temperature T 2i Fitting polynomial, combined with the actual tower temperature T 1i , flow rate on the tower Q ci , wet bulb temperature T s And each cooling tower L i When the air volume percentage is 1, calculate the corresponding lower tower temperature T 2is , the lower tower temperature is the required first lower tower temperature;

[0080] According to different standard operating conditions, the measured operating conditions are corrected to calculate the corrected second lower tower temperature.

[0081] At present, cooling towers are divided into standard working condition I and standard working condition II according to the use conditions. Generally, small and medium-sized open cooling towers (single tower cooling water volume is less than 1000m 3 / h) has two types of standard working conditions. Large open cooling towers generally only have standard working condition II. In the circulating water system, there may be only small and medium open cooling towers, or only large open cooling towers. This depends on the specific configuration of the circulating water system and the use requirements of the user's process end process. If the design temperature difference can only be maintained at 5°C, standard working condition I is selected; if the design temperature difference can reach 10°C, and the water temperature at the end is allowed to be higher, a cooling tower with standard working condition II can be selected. This depends on the user's selection.

[0082] Standard operating condition I: upper tower temperature 37°C, lower tower temperature 32°C, wet bulb temperature 28°C, dry bulb temperature 31.5°C, atmospheric pressure 99.4kPa.

[0083] Standard operating condition II: upper tower temperature 43℃, lower tower temperature 33℃, wet bulb temperature 28℃, dry bulb temperature 31.5℃, atmospheric pressure 99.4kPa.

[0084] If the cooling tower selection condition is standard condition I, according to the cooling capacity calculation process of the open cooling tower, the cooling number N of the cooling tower under the actual measured condition is calculated. 1 ; Assume the lower tower temperature T′ under standard operating conditions 2i , combined with the upper tower temperature of 37℃, wet bulb temperature of 28℃, dry bulb temperature of 31.5℃, atmospheric pressure of 99.4kPa, and nominal cooling water volume in standard operating condition Ⅰ, calculate the standard operating condition cooling number N d ,

[0085] Comparison of standard working condition cooling number N d And the actual working condition cooling number N 1 , calculate the lower tower temperature when the cooling number under the measured working conditions is corrected to the cooling number under the standard working conditions, that is, iterate continuously until |N d -N 1 |≤0.001, calculate the corrected lower tower temperature T′ 2i , at this time T′ 2i It is considered to be T' under actual working conditions corrected to standard working conditions 2is . At the same time, the cooling tower L i Cooling capacity η i =(37-T′ 2is ) / 5. Here 5 is the inlet and outlet water temperature difference of standard working condition I.

[0086] If the cooling tower model corresponds to standard operating condition II, the cooling number N of the cooling tower under the actual operating condition can be calculated according to the method disclosed above. 1 , assuming the lower tower temperature T' under standard conditions 2i , combined with the upper tower temperature of 43℃, wet bulb temperature of 28℃, dry bulb temperature of 31.5℃, atmospheric pressure of 99.4kPa, and nominal cooling water volume in standard operating condition II, calculate the standard operating condition cooling number N d , compared with the standard cooling number N d And the actual working condition cooling number N 1 , and iterate until |N d -N 1 |≤0.001, calculate T′ at this time 2i , at this time T′ 2i It is considered to be T' under actual working conditions corrected to standard working conditions 2is , Cooling tower L i Cooling capacity i =(43-T′ 2is ) / 10. Here 10 is the inlet and outlet water temperature difference of temperature difference standard working condition II.i Cooling capacity i =(upper tower temperature of standard working condition II - T' 2is ) / the inlet and outlet water temperature difference of standard working condition II. That is, according to the standard working condition type of the cooling tower, the upper tower temperature corresponding to the standard working condition type, the water temperature difference between the upper tower temperature and the lower tower temperature, and the corrected lower tower temperature, the cooling capacity of the cooling tower is calculated.

[0087] Among them, the calculation process of the cooling capacity of the open cooling tower can refer to the contents disclosed in GB / T7190-2018 "Mechanical Ventilation Cooling Tower".

[0088] As a preferred solution, the following steps are also included: according to the cooling capacity η of each cooling tower currently calculated i and design cooling water flow Q cdi Calculate the current standard cooling water volume of each cooling tower. The specific formula is as follows:

[0089] Q cbi =η i Q cdi

[0090] Collect the operating power Wis of each cooling tower Li at rated air volume, combined with the standard cooling water volume Q of each cooling tower cbi Calculate the power consumption ratio S of each cooling tower i , the specific formula is as follows:

[0091] S i =W i / Q cbi

[0092] The energy efficiency grade is evaluated according to the power consumption ratio, and can be evaluated in combination with the energy efficiency grade table of GB / T7190-2018 "Mechanical Ventilation Cooling Tower".

[0093] In cooling tower applications, "design cooling water flow" generally refers to the rated or nominal cooling water flow rate determined during the cooling tower design phase, which is based on the manufacturer's design specifications and expected operating conditions.

[0094] As a preferred solution, a real-time display unit may also be configured to display the energy efficiency rating evaluation online.

[0095] As a preferred solution, the upper tower temperature and the upper tower cooling water flow are collected through a dynamic balance electric regulating valve installed in the upper tower pipeline of each cooling tower.

[0096] The selected dynamic balancing electric regulating valve integrates the upper tower temperature sensor and the upper tower flow meter, such as the Chinese invention patent publication document, publication number: CN111322447A, invention name: valve control method and valve integrating dynamic flow balance and energy control, and the valve disclosed therein is implemented in this application.

[0097] Correspondingly, a device for evaluating the cooling effect of a circulating water system is disclosed, comprising the following structure:

[0098] Outdoor temperature and humidity sensor HT 1 and atmospheric pressure gauge P a , installed outside the air inlet of the cooling tower, the outdoor temperature and humidity sensor is used to collect the outdoor dry bulb temperature T a , relative humidity Barometer P a Used to collect local atmospheric pressure;

[0099] Dynamic balancing electric regulating valve V i , installed on each cooling tower L i The upper tower pipeline is used to collect the L i Upper tower temperature T 1i And the cooling water flow rate Q ci ;

[0100] The lower tower temperature sensor is installed in the lower tower pipeline of each cooling tower to collect the lower tower temperature T of each cooling tower. 2i ;

[0101] Fan data acquisition unit, used to collect the operating data of the fans in each cooling tower;

[0102] The parameter calculation unit is used to calculate the ambient wet bulb temperature according to the outdoor dry bulb temperature, relative humidity and atmospheric pressure, and to calculate the cooling tower air volume percentage according to the operation data of the fan; the polynomial fitting unit is used to fit the lower tower temperature of each cooling tower to the polynomial of the ambient wet bulb temperature, the upper tower temperature, the upper tower cooling water flow and the cooling tower air volume percentage by means of a fitting curve;

[0103] The lower tower temperature calculation unit calculates the corresponding lower tower temperature according to the polynomial of the lower tower temperature of each cooling tower, combined with the currently collected upper tower temperature, upper tower flow, ambient wet bulb temperature and air volume percentage;

[0104] The lower tower temperature correction unit is used to calculate the cooling number of the cooling tower under the actual working condition according to the cooling capacity calculation process of the open cooling tower; calculate the cooling number under the standard working condition according to the standard working condition type of the current cooling tower, and calculate the lower tower temperature when the cooling number under the actual working condition is corrected to the cooling number under the standard working condition as the corrected lower tower temperature;

[0105] The cooling capacity calculation unit calculates the cooling capacity of the cooling tower through the upper tower temperature and the lower tower temperature under standard working conditions and the corrected lower tower temperature;

[0106] Evaluation unit, which evaluates the cooling effect according to the cooling capacity of the cooling tower.

[0107] As a preferred solution, it also includes: a standard cooling water volume calculation unit, which is used to calculate the current standard cooling water volume of each cooling tower based on the cooling capacity of each cooling tower and the designed cooling water flow rate currently calculated.

[0108] As a preferred solution, it also includes: a power consumption ratio calculation unit, which is used to collect the operating power of each cooling tower at the rated air volume, and calculate the power consumption ratio of each cooling tower in combination with the standard cooling water volume of each cooling tower;

[0109] Energy efficiency rating is evaluated based on the power consumption ratio.

[0110] Outdoor temperature and humidity sensor HT 1 and atmospheric pressure gauge P a The installation location is based on the requirements of GB / T7190.2-2018 "Mechanical Ventilation Cooling Tower Part 2: Large Open Cooling Tower" A.5.1a), and is arranged outside the tower air inlet within 2m of the tower and 1.5m above the top of the pool, where the space is well ventilated. If the national standards, industry standards or enterprise standards used are different for the layout location, the current national standards, industry standards or enterprise standards used by the user shall prevail.

[0111] Application Example 1:

[0112] The following is a circulating water system of an electronics factory. There are 10 cooling towers in total. Each cooling tower contains a fan with a power of 18.5kW and operates at industrial frequency. The rated cooling water volume is 550m 3 / h, cooling tower selection corresponds to standard operating condition Ⅰ.

[0113] At a certain instantaneous outdoor dry-bulb temperature of 29°C, relative humidity of 90%, wet-bulb temperature of 27.6°C, and atmospheric pressure of 102.8 kPa, the actual operating parameters and evaluation parameters of each cooling tower are shown in Table 1.

[0114] Table 1:

[0115]

[0116]

[0117] As can be seen from the table above, although the cooling capacity of the cooling tower must be greater than 95% according to standard requirements when it leaves the factory, after long-term operation, the cooling capacity will decrease to varying degrees, and its standard cooling water volume, power consumption ratio and energy efficiency level will change. Therefore, if the cooling capacity and energy efficiency level of the cooling tower can be evaluated and ranked regularly, and the number or parameters of the cooling tower can be adjusted according to the evaluation results, the optimized operation of the circulating water system can be achieved.

[0118] Furthermore, a circulating water system control method is proposed, aiming to achieve efficient use according to the performance of the current cooling tower.

[0119] Combined with the parameters calculated in Example 1 and / or Example 2, the following control method is implemented:

[0120] Regularly calculate the cooling capacity and energy efficiency level of each cooling tower, give priority to operating cooling towers with high energy efficiency levels, obtain the current standard cooling water volume, use the current standard cooling water volume to match the cooling water volume required by the cooling tower group, obtain the actual cooling water volume required by each cooling tower, adjust the water flow deviation on the cooling tower according to the actual cooling water volume required by each cooling tower, and adjust the opening of the dynamic balance electric control valve according to the deviation.

[0121] Adjust the frequency or start / stop status of the fan on each cooling tower by matching the air volume.

[0122] The control method is further explained. By the above disclosed method, each cooling tower L is regularly analyzed. i Cooling capacity η i , the current standard cooling water volume Q can be obtained cbi , using the current standard cooling water volume Q cbi Match the cooling water volume Q required by the cooling tower group ce The specific plan is as follows:

[0123] If p cooling towers with high cooling capacity (or cooling towers with high energy efficiency rating) are selected under the current measured working conditions, calculate the standard cooling water volume Q of each cooling tower. cbi , total standard cooling tower water volume Q cb , according to the actual demand of cooling water volume Q of cooling tower group ce , then the actual cooling water demand of each cooling tower is Q cbi / Q cb *Q ce , each cooling tower L i Dynamic balance electric regulating valve V on the upper tower pipeline i According to the target water volume and the actual cooling water volume Q ci Deviation, adjust the valve opening.

[0124] The valve adopts the above-mentioned dynamic balancing electric regulating valve. The purpose of this application is not only to ensure that the cooling capacity of each cooling tower is fully utilized, but also to ensure the balance of water volume on the cooling tower, to avoid the occurrence of excessive flow in some cooling towers and short flow in some cooling towers due to uneven water flow in the cooling tower group. Secondly, this is also the prerequisite for optimized control of the cooling tower group.

[0125] For the cooling tower group, there is an optimal cooling tower fan energy consumption to match the required cooling water temperature difference ΔT ce The details are as follows: given the water temperature of the cooling tower main tube T 1 Under the premise of, the water temperature of the main pipe of the cooling tower group is required to be T 2 =T 1 -ΔT ce ; The water temperature formula of the main pipe of the lower tower obtained after the water flow of the lower tower of p cooling towers is as follows:

[0126]

[0127] In the above formula, X i , Y are all known parameters, among which,

[0128] X i =Q cbi / Q cb *e i ;e i is the fitting coefficient e of the temperature polynomial under the i-th cooling tower;

[0129] Y=Q cb1 / Q cb *(a 1 +b 1 T s +c 1 T 11 +d 1 Q cb1 / Q cb *Q ce )+…+Q cbp / Q cb *(a p +b p T s +c p T 1p +d p Q cbp / Q cb *Q ce ).

[0130] Q cb1 -Q cbp is the currently calculated standard cooling water volume of each of the p cooling towers in operation.

[0131] a1 -a p , b 1 -b p , c 1 -c p , d 1 -d p are the polynomial coefficients of p cooling towers.

[0132] In the process of cooling tower heat dissipation, for different upper tower temperatures and ambient wet bulb temperatures, under the premise that the optimal water volume is known, the lower tower temperature of each cooling tower is only related to its air volume. This means that the water temperature of the main pipe of the lower tower of the cooling tower group is T 2 It is related to the air volume of each running cooling tower. 2 As a known constraint, there is the possibility of multiple cooling towers with different air volumes, which correspond to the operating energy consumption of all fans in a group of cooling towers. However, there must be a group with the lowest total operating energy consumption. At this time, the air supply volume of each cooling tower is the optimal air supply volume. The optimal air supply volume can be achieved by adjusting the frequency or start and stop state of the fan of each cooling tower.

[0133] Application Case 2:

[0134] The circulating water system in this case has two cooling towers, each with a fan with a power of 7.5kW and variable frequency operation, and a rated cooling water volume of 260m 3 / h, cooling tower selection corresponds to standard operating condition Ⅰ.

[0135] At a certain time point, the outdoor dry-bulb temperature is 30°C, the relative humidity is 73.74%, the ambient wet-bulb temperature is 26.1°C, and the atmospheric pressure is 100.5 kPa. Through the above-disclosed calculation method, the actual operating parameters and evaluation parameters of each cooling tower are obtained as shown in Table 2.

[0136] Table 2:

[0137]

[0138] When the total required water volume is equal to the actual total water volume, the target cooling water volume that L1 should be allocated is 202.58m 3 / h, the cooling water volume allocated to L2 is 195.32m 3 / h, according to the current working conditions, the required temperature difference is 3.52℃, and the actual temperature difference is 3.9℃. When the air volume percentages of the two cooling towers are both 0.892, the cooling tower fans have the lowest operating power.

[0139] The present application further discloses a cooling effect comprehensive evaluation system 1, which, as a main control system, includes functions such as receiving collected data, calculating cooling effects, and transmitting control instructions, and includes the following structure:

[0140] The sensor signal receiving unit receives the outdoor dry bulb temperature T a , relative humidity Barometer P a , the upper tower temperature of each cooling tower is T 1i , cooling water flow rate Q ci and lower tower temperature T 2i ;

[0141] And receive the operating data of the fans in each cooling tower.

[0142] The parameter calculation unit is used to calculate the ambient wet bulb temperature according to the outdoor dry bulb temperature, relative humidity and atmospheric pressure, and to calculate the cooling tower air volume percentage according to the operation data of the fan; the polynomial fitting unit is used to fit the lower tower temperature of each cooling tower to the polynomial of the ambient wet bulb temperature, the upper tower temperature, the upper tower cooling water flow and the cooling tower air volume percentage by means of a fitting curve;

[0143] The lower tower temperature calculation unit calculates the corresponding lower tower temperature according to the polynomial of the lower tower temperature of each cooling tower, combined with the currently collected upper tower temperature, upper tower flow, ambient wet bulb temperature and air volume percentage;

[0144] The lower tower temperature correction unit is used to calculate the cooling number of the cooling tower under the actual working condition according to the cooling capacity calculation process of the open cooling tower; calculate the cooling number under the standard working condition according to the standard working condition type of the current cooling tower, and calculate the lower tower temperature when the cooling number under the actual working condition is corrected to the cooling number under the standard working condition as the corrected lower tower temperature;

[0145] The cooling capacity calculation unit calculates the cooling capacity of the cooling tower through the upper tower temperature and the lower tower temperature under standard working conditions and the corrected lower tower temperature;

[0146] Evaluation unit, which evaluates the cooling effect according to the cooling capacity of the cooling tower.

[0147] Furthermore, it also includes a timing unit for controlling the regular calculation of the cooling capacity and energy efficiency level of each cooling tower, giving priority to operating cooling towers with high energy efficiency levels, and obtaining the current standard cooling water volume.

[0148] Furthermore, when the control function is realized, it also includes a control unit, which matches the cooling water volume required by the cooling tower group with the current standard cooling water volume, obtains the actual cooling water volume required by each cooling tower, adjusts the water flow deviation on the cooling tower according to the actual cooling water volume required by each cooling tower, and controls the dynamic balancing electric regulating valve according to the water flow deviation parameter on the cooling tower.

[0149] By matching the air volume, the frequency or start / stop status of the fan on each cooling tower is adjusted, and a frequency or start / stop status control signal is output.

[0150] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of the modules or units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed.

[0151] The units may or may not be physically separated, and the components displayed as units may be one physical unit or multiple physical units, that is, they may be located in one place or distributed in multiple different places. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0152] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0153] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solution of the embodiment of the present invention is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions to enable a device (which can be a single-chip microcomputer, chip, etc.) or a processor (processor) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), disk or optical disk and other media that can store program codes.

[0154] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for evaluating the cooling effect of a circulating water system, characterized in that: The steps include: In response to a time trigger or a passive trigger, the outdoor dry-bulb temperature, relative humidity and atmospheric pressure, as well as the upper tower temperature of each cooling tower, the upper tower cooling water flow, the lower tower temperature of each cooling tower, and the operating data of the fans in each cooling tower are collected; Calculate the cooling tower air volume percentage based on the fan operating data, and calculate the ambient wet bulb temperature based on the outdoor dry bulb temperature, relative humidity and atmospheric pressure; By fitting the curve, a polynomial is obtained that the lower tower temperature of each cooling tower is related to the ambient wet bulb temperature, the upper tower temperature, the upper tower cooling water flow rate and the cooling tower air volume percentage; According to the polynomial of the lower tower temperature of each cooling tower, combined with the currently collected upper tower temperature, upper tower flow, ambient wet bulb temperature and air volume percentage, the corresponding lower tower temperature is calculated; According to the cooling capacity calculation process of the open cooling tower, the cooling number of the cooling tower under the actual working condition is calculated; the cooling number under the standard working condition is calculated according to the standard working condition type of the current cooling tower, and the lower tower temperature when the cooling number under the actual working condition is corrected to the cooling number under the standard working condition is calculated as the corrected lower tower temperature. The cooling capacity of the cooling tower is calculated by the upper tower temperature and the lower tower temperature under the standard working condition, and the corrected lower tower temperature, and the cooling effect is evaluated according to the cooling capacity of the cooling tower.

2. The method for evaluating the cooling effect of a circulating water system according to claim 1, characterized in that: The following steps are also included: The current standard cooling water volume of each cooling tower is calculated based on the cooling capacity of each cooling tower and the designed cooling water flow rate; Collect the operating power of each cooling tower at rated air volume, calculate the power consumption ratio of each cooling tower in combination with the standard cooling water volume of each cooling tower, and evaluate the energy efficiency level based on the power consumption ratio; The cooling effect is evaluated based on one or more indicators of the current standard cooling water volume, cooling capacity, power consumption ratio or energy efficiency level of each cooling tower.

3. The method for evaluating the cooling effect of a circulating water system according to claim 1, characterized in that: The method for calculating the cooling tower air volume percentage according to the operation data of the fan comprises: When the fan is a variable frequency fan, the operating data of the fan in each cooling tower includes the start and stop status and the operating frequency. The air volume percentage A is calculated according to the following formula ai : In the formula ω ij —The start and stop status of the jth variable frequency fan in the i-th cooling tower, "1" means running; "0" means stopping; F ij —The operating frequency of the jth variable frequency fan in the i-th cooling tower, in Hz; m—the number of variable frequency fans configured in the i-th cooling tower.

4. The method for evaluating the cooling effect of a circulating water system according to claim 1, characterized in that: The method for calculating the cooling tower air volume percentage according to the operation data of the fan comprises: When the fan is a two-speed fan, the operating data of the fan in each cooling tower includes the start-stop state and the high and low speed states. The air volume percentage A is calculated according to the following formula: ai : In the formula ω ij —The start and stop status of the jth two-speed fan in the i-th cooling tower, ω ij —The high and low speed status of the j-th two-speed fan in the i-th cooling tower, "1" means high speed; "0.5" means low speed; m—the number of two-speed fans configured in the i-th cooling tower.

5. The method for evaluating the cooling effect of a circulating water system according to claim 1, characterized in that: The method for calculating the cooling tower air volume percentage according to the operation data of the fan comprises: When the fan is a power frequency fan, the operating data of the fan in each cooling tower includes the start and stop status. The air volume percentage A is calculated according to the following formula ai : In the formula ω ij —The start and stop status of the jth power frequency fan in the i-th cooling tower, "1" means running; "0" means stopping; m—the number of two-speed fans configured in the i-th cooling tower.

6. The method for evaluating the cooling effect of a circulating water system according to claim 1, characterized in that: The ambient wet-bulb temperature is calculated based on the outdoor dry-bulb temperature and relative humidity in combination with a psychrometric chart calculator, or is calculated based on an approximate empirical formula.

7. A device for evaluating the cooling effect of a circulating water system, characterized in that: Includes the following structures: Outdoor temperature and humidity sensor, installed outside the air inlet of the cooling tower, used to collect outdoor dry-bulb temperature and relative humidity; Atmospheric barometer, installed outside the air inlet of the cooling tower, used to collect local atmospheric pressure; A dynamic balancing electric regulating valve is installed in the upper tower pipeline of each cooling tower, including a temperature sensor and a flow meter, which collects the upper tower temperature and the upper tower cooling water flow of each cooling tower in response to time triggering or passive triggering; The lower tower temperature sensor is installed in the lower tower pipeline of each cooling tower to collect the lower tower temperature of each cooling tower; Fan data acquisition unit, used to collect the operating data of the fans in each cooling tower; The parameter calculation unit is used to calculate the ambient wet bulb temperature according to the outdoor dry bulb temperature, relative humidity and atmospheric pressure, and to calculate the cooling tower air volume percentage according to the operation data of the fan; the polynomial fitting unit is used to fit the lower tower temperature of each cooling tower to the polynomial of the ambient wet bulb temperature, the upper tower temperature, the upper tower cooling water flow and the cooling tower air volume percentage by means of a fitting curve; The lower tower temperature calculation unit calculates the corresponding lower tower temperature according to the polynomial of the lower tower temperature of each cooling tower, combined with the currently collected upper tower temperature, upper tower flow, ambient wet bulb temperature and air volume percentage; The lower tower temperature correction unit is used to calculate the cooling number of the cooling tower under the actual working condition according to the cooling capacity calculation process of the open cooling tower; calculate the cooling number under the standard working condition according to the standard working condition type of the current cooling tower, and calculate the lower tower temperature when the cooling number under the actual working condition is corrected to the cooling number under the standard working condition as the corrected lower tower temperature; The cooling capacity calculation unit calculates the cooling capacity of the cooling tower through the upper tower temperature and the lower tower temperature under standard working conditions and the corrected lower tower temperature; Evaluation unit, which evaluates the cooling effect according to the cooling capacity of the cooling tower.

8. The cooling effect evaluation device of the circulating water system according to claim 7, characterized in that include: A standard cooling water volume calculation unit is used to calculate the current standard cooling water volume of each cooling tower according to the currently calculated cooling capacity of each cooling tower and the designed cooling water flow rate; The power consumption ratio calculation unit is used to collect the operating power of each cooling tower at the rated air volume, and calculate the power consumption ratio of each cooling tower in combination with the standard cooling water volume of each cooling tower; Energy efficiency rating is evaluated based on power consumption ratio; The evaluation unit evaluates the cooling effect according to one or more indicators of the current standard cooling water volume, cooling capacity, power consumption ratio or energy efficiency level of each cooling tower.

9. The device for evaluating the cooling effect of a circulating water system according to claim 7, characterized in that: A real-time display unit is also included for displaying the energy efficiency rating evaluation.

10. A circulating water system control method, characterized in that: Combined with the parameters calculated by the method described in any one of claims 2 to 6, the following control method is implemented: Regularly calculate the cooling capacity and energy efficiency level of each cooling tower, give priority to operating cooling towers with high energy efficiency levels, obtain the current standard cooling water volume, use the current standard cooling water volume to match the cooling water volume required by the cooling tower group, obtain the actual cooling water volume required by each cooling tower, adjust the water flow deviation of the cooling tower according to the actual cooling water volume required by each cooling tower, and adjust the opening of the dynamic balance electric regulating valve according to the deviation; Adjust the frequency or start / stop status of the fan on each cooling tower by matching the air volume.

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