A dry cooling tower variable frequency fan joint energy-saving control method

Abstract

The present invention relates to a dry cooling tower variable frequency fan joint energy-saving control method, comprising the following steps: obtaining the flow rate of cooling water in the dry cooling tower, the water temperature of the water inlet and the set water temperature of the water outlet, calculating the required heat dissipation per unit time of cooling water; discretizing the frequency of the variable frequency fan by segmentation; establishing a fan operation combination; calculating the heat dissipation per unit time of multiple fan operation combinations in the dry cooling tower under different frequency segments; obtaining the average power of each fan under different frequency segments; querying and matching the required heat dissipation per unit time of cooling water and the heat dissipation per unit time of multiple fan operation combinations of the dry cooling tower under different frequency segments, and selecting the fan operation combination with the minimum power as the operation mode of the fan. The present invention can accurately control the water temperature of the water outlet, and realize energy saving while meeting the heat exchange demand of cooling water.

Description

Technical Field

[0001] The invention belongs to the technical field of variable frequency fans, and in particular relates to a combined energy-saving control method for variable frequency fans of dry cooling towers. Background Art

[0002] Water resources are scarce in my country, so most power plants use dry cooling to save water resources. The dry cooling tower is a typical representative of dry cooling. It is an important auxiliary equipment for circulating cooling water heat exchange of power station auxiliary equipment. It includes variable frequency fans and shutters with adjustable blade openings. Under different load and ambient temperature conditions, the heat exchange of circulating cooling water is achieved through the shutter opening and the frequency and start-up combination of multiple variable frequency fans. However, its frequency setting and operation combination are mostly determined by the operator's experience, which often causes energy waste caused by excessive fan heat dissipation output or the use of inefficient fan operation combinations. Summary of the invention

[0003] The object of the present invention is to provide a dry cooling tower variable frequency fan joint energy-saving control method, which can save energy while meeting the cooling water heat exchange requirements;

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A dry cooling tower variable frequency fan joint energy-saving control method comprises the following steps:

[0006] Step 1: Obtain the cooling water flow rate in the dry cooling tower, the water temperature at the water inlet, and the set water temperature at the water outlet, and calculate the required heat dissipation per unit time of the cooling water;

[0007] Step 2: Discretize the frequency of the variable frequency fan into segments;

[0008] Step 3: Establish a fan operation combination, and arrange and combine the opening and closing characteristics of multiple fans;

[0009] Step 4: Under different ambient temperature ranges, run the fan operation combination under each frequency range, detect the actual water temperature at the water outlet, calculate the heat dissipation per unit time of multiple fan operation combinations in the dry cooling tower under different frequency ranges; obtain the average power of each fan under different frequency ranges;

[0010] Step 5: query and match the required heat dissipation per unit time of cooling water with the heat dissipation per unit time of multiple fan operation combinations of dry cooling towers in different frequency bands to obtain at least one fan operation combination within the required heat dissipation range of cooling water.

[0011] Step 6: Query the average power of the fan in step 4. If there is only one fan operation combination, select the fan operation combination as the fan operation mode. If there are multiple fan operation combinations, add the powers of the fans turned on in the fan operation combination and select the fan operation combination with the smallest power as the fan operation mode.

[0012] Preferably, the present invention further comprises the following steps:

[0013] Step 7: Monitor the water temperature at the water outlet and the water inlet. If the actual water temperature at the water outlet is greater than or less than the set water temperature, and the required heat dissipation of the cooling water is still within the heat dissipation range of the fan operation combination, the frequency of the turned-on fan is increased or decreased in sequence within the frequency range.

[0014] Preferably, the present invention further comprises the following steps:

[0015] Step 8: Monitor the ambient temperature. If the ambient temperature is greater than or less than the applicable ambient temperature range of the fan operation combination, re-match the fan operation combination under the current ambient temperature and select the fan operation combination with the minimum power as the fan operation mode.

[0016] Preferably, in step 4, a database of heat dissipation per unit time of dry cooling tower fans in discrete frequency segments at different ambient temperatures is established according to the heat dissipation per unit time of multiple fan operation combinations in different frequency segments.

[0017] Preferably, it is characterized in that, in step 4, a dry cooling tower fan discrete frequency segment power database is established according to the average power of each fan in different frequency segments.

[0018] Preferably, in step 7, if the required heat dissipation of cooling water exceeds the heat dissipation range of the fan operation combination, the fan operation combination is re-matched and the fan operation combination with the minimum power is selected as the fan operation mode.

[0019] Preferably, in step 7, if the required heat dissipation of cooling water is within the heat dissipation range of the fan operation combination, when the frequency of the fan is increased or decreased to the end point of the frequency band range, the actual water temperature is still not equal to or close to the set water temperature, then the heat dissipation per unit time of multiple fan operation combinations in different frequency bands is updated, and then the fan operation combinations are re-matched, and the fan operation combination with the smallest power is selected as the fan operation mode.

[0020] The present invention can accurately meet the heat exchange demand of cooling water by matching the heat dissipation required per unit time of cooling water with the heat dissipation per unit time of multiple fan operation combinations in dry cooling towers in different frequency bands, so that the actual water temperature at the water outlet reaches the set water temperature as soon as possible, thereby preventing the fan in the dry cooling tower from dissipating too much or too little heat; by selecting the fan operation combination with the minimum power as the fan operation mode, energy can be saved and costs can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the dry cooling tower structure of the present invention;

[0022] Figure 2 It is a schematic diagram of the process structure of the present invention. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0024] The present invention provides a dry cooling tower variable frequency fan joint energy-saving control method, which is used to control the fan in the dry cooling tower; Figure 1 As shown, a plurality of fans 1 are arranged in the dry cooling tower, and a cooling main pipe 2 is arranged on one side of the plurality of fans 1, wherein the cooling main pipe 2 is divided into a water inlet portion and a water outlet portion; the plurality of fans 1 are installed on one side of the water inlet portion of the cooling main pipe 2; the ends of the water inlet portion and the water outlet portion are respectively provided with a water inlet and a water outlet; the cooling main pipe 2 is respectively provided with a cooling branch pipe 21 matched with each fan; one end of each cooling branch pipe is connected to the water inlet portion, and the other end is connected to the water outlet portion, and the cooling water in the cooling main pipe 2 is cooled by the plurality of fans 1;

[0025] like Figure 2 As shown, the specific control method of the variable frequency fan of the dry cooling tower includes the following steps:

[0026] Step 1: Obtain the cooling water flow rate q and water inlet temperature T in the dry cooling tower s and the set water temperature T at the water outlet i , calculate the required heat dissipation of cooling water per unit time;

[0027] Specifically, the flow rate of cooling water in the dry cooling tower and the water temperature at the water inlet are measured by the detection device.

[0028] According to the heat calculation formula:

[0029] Q 需 =c·ρ·q·(T s -T i )

[0030] Calculate the cooling water heat dissipation per unit time Q 需 , where c is the specific heat capacity of cooling water and ρ is the density of cooling water;

[0031] Step 2: Discretize the frequency of the variable frequency fan into segments;

[0032] Specifically, the frequency of the variable frequency fan can be divided into 0~15Hz, 15~25Hz, 25~35Hz, 35~40Hz;

[0033] Step 3: Establish a fan operation combination, and arrange and combine the opening and closing characteristics of multiple fans;

[0034] Specifically, taking the arrangement and combination of four fans as an example, the fan operation combinations are

[0000] ,

[0001] ,

[0010] ,

[0100] ,

[1000] ,

[1100] ,

[1010] ,

[1001] ,

[0110] ,

[0101] ,

[0011] ,

[0111] ,

[1011] ,

[1101] ,

[1110] ,

[1111] , where 1 indicates that the fan is on and 0 indicates that the fan is off. Fans No. 1 to No. 4 are arranged in sequence.

[0035] It should be noted that the embodiment of the present invention does not limit the number of fans, and can be arranged and combined according to the actual number of fans;

[0036] Step 4: Under different ambient temperature ranges, run the fan operation combination under each frequency range to detect the actual water temperature T at the water outlet. O , calculate the heat dissipation per unit time Q of multiple fans running in the dry cooling tower in different frequency bands 实 , obtain the average power P of each wind turbine in different frequency bands;

[0037] Specifically, according to the heat calculation formula:

[0038] Q 实 =c·ρ·q·(T s -T O )

[0039] According to the actual water temperature T detected at the outlet at different fan frequencies O , calculate the heat dissipation per unit time Q of the fan operation combination 实 , get the minimum and maximum heat dissipation of the fan operation combination in this frequency range, by detecting the power of each fan in the fan operation combination when it is turned on in different frequency ranges, and then take the average of the power as the operating power of the fan in this frequency range;

[0040] Among them, because the use environment, location and use time of each fan are different, the heat dissipation of each fan at the same frequency is different, and it is necessary to actually calculate the heat dissipation per unit time Q of the fan operation combination. 实 Make measurements and calculations;

[0041] In this embodiment, in step 4, the heat dissipation per unit time Q of the plurality of fan operation combinations in different frequency bands is calculated. 实 , establish a database of heat dissipation per unit time in discrete frequency segments of dry cooling tower fans at different ambient temperatures for easy query,

[0042] The specific database relationship is shown as follows:

[0043] Table 1

[0044] Ambient temperature T∈[18,25]

[0045]

[0046] Among them, Q is the heat dissipation value and Q0 is the natural heat dissipation.

[0047] For example, Q 1,3

[0001] is the minimum heat dissipation value of the fan operation combination at 15-25Hz; Q 1,4

[0001] is the maximum heat dissipation value of the fan operation combination at 15-25Hz;

[0048] In this embodiment, in step 4, a dry cooling tower fan discrete frequency segment power database is established according to the average power P of each fan in different frequency segments.

[0049] Table 2

[0050]

[0051] Where P represents the average power in the frequency band.

[0052] Step 5: Calculate the required heat dissipation per unit time of cooling water Q 需 Heat dissipation per unit time Q in different frequency bands combined with multiple fans of dry cooling tower 实 Perform query matching to obtain at least one fan operation combination within the required cooling water heat dissipation range.

[0053] Specifically, the heat dissipation required per unit time using cooling water is Q 需 The dry cooling tower fan discrete frequency segment unit time heat dissipation database is queried and matched, and the cooling water unit time heat dissipation demand Q 需 All fan operation combinations within the heat dissipation value Q range in Table 1 are selected;

[0054] Step 6: Query the power of the fan in step 4. If there is only one fan operation combination, select the fan operation combination as the operation mode of the fan. If there are multiple fan operation combinations, add the powers of the fans turned on in the fan operation combinations and select the fan operation combination with the smallest power as the operation mode of the fan.

[0055] Specifically, multiple fan operation combinations are selected, and according to the database in Table 2, the powers of the fans turned on in the fan operation combinations in the selected frequency band are added to obtain the power of each fan operation combination, and then the fan operation combination with the smallest power is selected as the operation mode of the fan.

[0056] In this embodiment, the following steps are also included:

[0057] Step 7: Monitor the water temperature T at the outlet O and the water temperature T at the water inlet s , if the actual water temperature at the outlet is T O Greater or less than the set water temperature T i , cooling water heat dissipation required Q 需 If the fan is still within the heat dissipation range of the fan operation combination, the frequency of the turned-on fan will be increased or decreased in sequence within the frequency range;

[0058] After selecting the fan operation combination, according to the water temperature T O , adjust the fan frequency at any time so that the actual water temperature T O Equal to or close to the set water temperature T i , to achieve the outlet water temperature T O stability control.

[0059] In this embodiment, in step 7, if the required heat dissipation of cooling water is greater than or less than the heat dissipation range of the fan operation combination, the fan operation combination is re-matched, and the fan operation combination with the minimum power is selected as the operation mode of the fan;

[0060] The required heat dissipation of cooling water may be greater or less than the heat dissipation range of the fan operation combination due to changes in the ambient temperature or the water temperature at the water inlet. In this case, it is necessary to repeat steps 5 and 6 to reselect the fan operation combination.

[0061] In this embodiment, in step 7, if the required heat dissipation of cooling water is within the heat dissipation range of the fan operation combination, when the frequency of the fan is increased or decreased to the end point of the frequency range, the actual water temperature is still not equal to or close to the set water temperature, then the heat dissipation per unit time of multiple fan operation combinations in different frequency ranges is updated, and then the fan operation combinations are re-matched, and the fan operation combination with the smallest power is selected as the operation mode of the fan;

[0062] The actual heat dissipation per unit time of the fan operation combination may be different from the heat dissipation in Table 1 due to changes in ambient temperature, operating environment or prolonged use time. Therefore, it is necessary to re-update the heat dissipation per unit time Q of multiple fan operation combinations in different frequency bands. 实 , that is, update the database of heat dissipation per unit time in discrete frequency segments of dry cooling tower fans at different ambient temperatures, and then repeat steps 5 and 6 to reselect the fan operation combination.

[0063] In this embodiment, the following steps are also included:

[0064] Step 8: Monitor the ambient temperature. If the ambient temperature exceeds the applicable ambient temperature range of the fan operation combination, re-match the fan operation combination under the current ambient temperature and select the fan operation combination with the minimum power as the fan operation mode;

[0065] When the current ambient temperature is not within the ambient temperature range of Table 1, the dry cooling tower fan discrete frequency segment unit time heat dissipation database within the current ambient temperature range should be matched, and step 6 should be repeated to reselect the fan operation combination.

Claims

1. A dry cooling tower variable frequency fan joint energy-saving control method, characterized in that: The following steps are involved: Step 1: Obtain the cooling water flow rate in the dry cooling tower, the water temperature at the water inlet, and the set water temperature at the water outlet, and calculate the required heat dissipation per unit time of the cooling water; Step 2: Discretize the frequency of the variable frequency fan into segments; Step 3: Establish a fan operation combination, and arrange and combine the opening and closing characteristics of multiple fans; Step 4: Under different ambient temperature ranges, run the fan operation combination under each frequency range, detect the actual water temperature at the water outlet, calculate the heat dissipation per unit time of multiple fan operation combinations in the dry cooling tower under different frequency ranges; obtain the average power of each fan under different frequency ranges; Step 5: query and match the required heat dissipation per unit time of cooling water with the heat dissipation per unit time of multiple fan operation combinations of dry cooling towers in different frequency bands to obtain at least one fan operation combination within the required heat dissipation range of cooling water. Step 6: Query the average power of the fan in step 4. If there is only one fan operation combination, select the fan operation combination as the fan operation mode. If there are multiple fan operation combinations, add the powers of the fans turned on in the fan operation combination and select the fan operation combination with the smallest power as the fan operation mode.

2. A dry cooling tower variable frequency fan joint energy-saving control method according to claim 1, characterized in that: The following steps are also included: Step 7: Monitor the water temperature at the water outlet and the water inlet. If the actual water temperature at the water outlet is greater than or less than the set water temperature, and the required heat dissipation of the cooling water is still within the heat dissipation range of the fan operation combination, the frequency of the turned-on fan is increased or decreased in sequence within the frequency range.

3. A dry cooling tower variable frequency fan joint energy-saving control method according to claim 2, characterized in that: The following steps are also included: Step 8: Monitor the ambient temperature. If the ambient temperature exceeds the applicable ambient temperature range of the fan operation combination, re-match the fan operation combination under the current ambient temperature and select the fan operation combination with the minimum power as the fan operation mode.

4. A dry cooling tower variable frequency fan joint energy-saving control method according to claim 1, characterized in that: In step 4, a database of heat dissipation per unit time of dry cooling tower fans in discrete frequency segments at different ambient temperatures is established according to the heat dissipation per unit time of multiple fan operation combinations in different frequency segments.

5. A dry cooling tower variable frequency fan joint energy-saving control method according to claim 1 or 4, characterized in that: In step 4, a dry cooling tower fan discrete frequency segment power database is established based on the average power of each fan in different frequency segments.

6. A dry cooling tower variable frequency fan joint energy-saving control method according to claim 2, characterized in that: In step 7, if the required heat dissipation of cooling water is greater than or less than the heat dissipation range of the fan operation combination, the fan operation combination is re-matched, and the fan operation combination with the minimum power is selected as the fan operation mode.

7. A dry cooling tower variable frequency fan joint energy-saving control method according to claim 2, characterized in that: In step 7, if the required heat dissipation of cooling water is within the heat dissipation range of the fan operation combination, when the frequency of the fan is increased or decreased to the end point of the frequency band range, the actual water temperature is still not equal to or close to the set water temperature, then the heat dissipation per unit time of multiple fan operation combinations in different frequency bands is updated, and then the fan operation combinations are re-matched, and the fan operation combination with the smallest power is selected as the fan operation mode.

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