A cooling tower circulating water flow measurement device

Abstract

The present invention provides a cooling tower circulating water flow measurement device, comprising: a cooling tower; a vertical shaft, a water collection tank and a water collection tank are arranged in the cooling tower, the water collection tank connects the vertical shaft and the water collection tank; a plurality of tower outlet air temperature and air velocity measurement points are arranged at the throat of the cooling tower; a tower inlet air temperature measurement point is arranged at the periphery of the cooling tower; an atmospheric pressure measurement point is arranged at least 50m away from the cooling tower; a tower inlet water temperature measurement point is arranged inside the vertical shaft; and a tower outlet water temperature measurement point is arranged at the end of the water collection tank. The present invention can accurately obtain the cooling tower circulating water flow, and realize the effective measurement and monitoring of the circulating water flow of the power plant.

Description

Technical Field

[0001] The invention relates to the technical field of cooling tower circulating water flow measurement, in particular to a cooling tower circulating water flow measurement device. Background Art

[0002] The circulating water flow rate of the cooling tower is a key parameter for the operation of a thermal power plant. The circulating water flow rate is directly related to the water temperature in and out of the cooling tower, the condenser end difference, the unit back pressure, and the power consumption rate of the power plant. The measurement and monitoring of the circulating water flow rate of the power plant is of great significance to the operation of the power plant.

[0003] At present, most domestic power plants lack the measurement and real-time monitoring of circulating water flow in power plants. They mainly test the outlet pressure of the circulating water pump, and then infer the circulating water flow based on the characteristic curve of the relationship between the outlet pressure and flow of the pump. The inferred flow rate deviates greatly from the actual water volume. A few power plants measure by adding ultrasonic flowmeters to the circulating water jelly pipes. Due to the large diameter of the circulating water pipeline, a long straight pipe section is required. Few power plants have a straight pipe section length in the circulating water pipeline system that meets the installation requirements of ultrasonic flowmeters. Therefore, accurate measurement and monitoring of circulating water flow has always been a difficult problem for power plants. Summary of the invention

[0004] In view of the above-mentioned prior art, the present invention proposes a cooling tower circulating water flow measurement device, which can solve the problem of inaccurate measurement and monitoring of the current circulating water flow.

[0005] The present invention provides a cooling tower circulating water flow measurement device, comprising:

[0006] A cooling tower; a vertical shaft, a water collecting tank and a water collecting tank are provided in the cooling tower, and the water collecting tank connects the vertical shaft and the water collecting tank;

[0007] A plurality of outlet air temperature and air velocity measuring points are arranged at the throat of the cooling tower;

[0008] The tower inlet air temperature measuring point is arranged at the periphery of the cooling tower;

[0009] The atmospheric pressure measuring point is set at least 50m away from the cooling tower;

[0010] The water temperature measuring point for entering the tower is arranged inside the vertical shaft;

[0011] The outlet water temperature measuring point is located at the end of the water receiving tank.

[0012] Preferably, the outlet air temperature and air flow rate measuring points are arranged on two mutually perpendicular diameters in the form of equal-area rings, and the number of the outlet air temperature and air flow rate measuring points is no less than 10.

[0013] Preferably, four tower inlet air temperature measuring points are evenly arranged along the cooling tower, 1 m away from the edge of the water collecting pool and 1.5-2.0 m away from the ground.

[0014] Preferably, the water collecting trough is triangular in shape, one end of which is connected to the vertical shaft, and the other end of which is connected to the edge of the water collecting pool.

[0015] Preferably, four water collecting tanks are provided.

[0016] Preferably, the shaft is placed in the center of the cooling tower.

[0017] Preferably, the outlet air temperature and air velocity measuring point is provided with a first platinum resistance thermometer and an impeller anemometer; the inlet air temperature measuring point is provided with a first platinum resistance thermometer; the resolution of the first platinum resistance thermometer is not less than 0.2°C, and the accuracy is not less than 0.5 level; the accuracy of the impeller anemometer is ±0.1°C.

[0018] Preferably, the atmospheric pressure measuring point is provided with a barometer, and the accuracy of the barometer is not less than level 0.25.

[0019] Preferably, both the inlet water temperature measuring point and the outlet water temperature measuring point are provided with a second platinum resistance thermometer; the resolution of the second platinum resistance thermometer is not less than 0.1°C and the accuracy is not less than level 0.5.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention utilizes the energy conservation principle of heat transfer between the cooling tower air and the circulating water, and calculates the circulating water process by measuring the cooling tower inlet water temperature, tower outlet water temperature, inlet air dry bulb temperature, relative humidity and tower outlet air temperature, so as to accurately obtain the cooling tower circulating water flow rate and realize effective measurement and monitoring of the circulating water flow rate of the power plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a front view of an embodiment of the present invention.

[0022] Figure 2 It is a structural schematic diagram of the tower outlet air temperature and air flow rate measurement points in an embodiment of the present invention.

[0023] Figure 3 2 is a top view of an embodiment of the present invention.

[0024] Among them, 1. Cooling tower; 2. Vertical shaft; 3. Water collection tank; 4. Water collection tank; 5. Outlet air temperature and air flow rate measuring points; 6. Inlet air temperature measuring point; 7. Atmospheric pressure measuring point; 8. Inlet water temperature measuring point; 9. Outlet water temperature measuring point. DETAILED DESCRIPTION

[0025] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below with reference to specific diagrams.

[0026] Example

[0027] like Figure 1-3 As shown, a cooling tower circulating water flow measurement device comprises: a cooling tower 1, wherein a vertical shaft 2, a water collecting trough 3 and a water collecting pool 4 are arranged in the cooling tower 1, the vertical shaft 2 is placed at the center of the cooling tower 1, the water collecting trough 3 is triangular, four of which are arranged, one end of which is connected to the vertical shaft 2, and the other end is connected to the edge of the water collecting pool 4, the water collecting trough 3 extends from the center of the tower to the edge of the water collecting pool 4 with a certain slope (the center of the tower is high, and the edge of the water collecting pool is low), so that the circulating water flows out along the water collecting trough 3, which is convenient for real-time and accurate measurement of the water temperature out of the cooling tower.

[0028] It also includes: the outlet air temperature and air flow rate measuring point 5 is set at the throat of the cooling tower 1. There are 12 outlet air temperature and air flow rate measuring points 5, which are arranged on two mutually perpendicular diameters in the form of equal area rings. The inlet air temperature measuring point 6 is set at the periphery of the cooling tower 1. There are 4 inlet air temperature measuring points 6 evenly arranged along the cooling tower 1, and they are 1m away from the edge of the water collection tank 4 and 1.5m away from the ground. The atmospheric pressure measuring point 7 is set in an open area 50m away from the cooling tower. The inlet water temperature measuring point 8 is set inside the vertical shaft 2; the outlet water temperature measuring point 9 is set at the end of the water collecting tank 3 near the edge of the water collection tank 4.

[0029] Among them, the outlet air temperature and air velocity measuring point 5 is provided with a first platinum resistance thermometer and an impeller anemometer, and the impeller anemometer is installed perpendicular to the air flow direction; the inlet air temperature measuring point 6 is provided with a first platinum resistance thermometer, the resolution of the first platinum resistance thermometer is not less than 0.2°C, the accuracy is not less than 0.5 level, and the accuracy of the impeller anemometer is ±0.1°C. The atmospheric pressure measuring point 7 is provided with a barometer, the accuracy of the barometer is not less than 0.25 level, and the resolution is 0.1hPa. The inlet water temperature measuring point 8 and the outlet water temperature measuring point 9 are both provided with a second platinum resistance thermometer to ensure that the second platinum resistance thermometer is submerged by the water level in the shaft 2, and the resolution of the second platinum resistance thermometer is not less than 0.1°C, and the accuracy is not less than 0.5 level.

[0030] In this embodiment, the processing method of the measurement results of the above-mentioned measurement points is as follows:

[0031] 1) Calculate the enthalpy of the air entering the tower: calculate the average dry-bulb temperature and wet-bulb temperature of the air entering the tower;

[0032]

[0033] Among them, θ j —Average dry bulb temperature of air entering the tower, °C; θ j,k —Dry bulb temperature of air entering the tower at the kth measuring point, °C;

[0034]

[0035] Among them, τ j —Average wet bulb temperature of air entering the tower, °C; τ j,k —Wet-bulb temperature of air entering the tower at the kth measuring point, °C;

[0036]

[0037] in, is the relative humidity of the air entering the tower; p" τ —Saturated vapor pressure corresponding to dry bulb temperature, Pa; p a — atmospheric pressure, Pa; p" θ —Saturated vapor pressure corresponding to dry bulb temperature, Pa;

[0038] Where, the saturated steam pressure p" v According to the Guillet formula published by Guillet in 1939:

[0039]

[0040] Where, T is temperature in degrees Kelvin, K;

[0041] P" v ——Saturated steam pressure corresponding to temperature T, 105Pa;

[0042]

[0043] Among them, i j —Enthalpy of air entering the tower, J / kg; other symbols are the same as before;

[0044] 2) Calculate the tower air enthalpy:

[0045]

[0046] Among them, θ o —Average dry bulb temperature of air leaving the tower, ℃; θ o,k —Dry bulb temperature of air leaving the tower at the kth measuring point, ℃; the air leaving the tower is saturated air, so τ o =θ o , τ o,k =θ o,k , where τ o —Average wet bulb temperature of air leaving the tower, ℃; τ o,k —Wet-bulb temperature of air leaving the tower at the kth measuring point, °C;

[0047]

[0048] Among them, i o—Enthalpy of air out of the tower, J / kg;

[0049] 3) Calculate the tower air mass flow rate:

[0050]

[0051] Among them, ρ d —Dry air density, i.e. 1m 3 The mass of dry air in wet air, kg / m 3 ;p d —Pressure corresponding to dry air, Pa; R d —The gas constant of dry air is 287.14 J / (kg·K); the air out of the tower is saturated air,

[0052]

[0053] Among them, V o —Average air velocity out of the tower, m / s; V o,k —Average air velocity out of the tower at the kth measuring point, m / s;

[0054]

[0055] Among them, m a —Dry air mass flow, m / s; R o —Tower throat radius, m; S h — Cross-sectional area of ​​the tower throat;

[0056] 4) Calculate the temperature difference between the circulating water inlet and outlet:

[0057]

[0058] Where, t2—water temperature out of the tower, ℃; t 2,k —Water temperature out of the tower at the kth measuring point, °C; Δt=t1-t2, where Δt is the circulating water temperature difference, °C; t1 is the water temperature in the tower, °C;

[0059] 5) Calculate circulating water flow:

[0060] Q w m a *(i o -i j ) / C w *Δt,

[0061] Among them, Q w —Circulating water flow, Kg / s; C w —Specific heat of water, J / (kg·℃).

[0062] The above are only implementation modes of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure made using the contents of the present invention's specification and drawings, directly or indirectly used in other related technical fields, are also within the patent protection scope of the present invention.

Claims

1. A cooling tower circulating water flow measurement device, characterized in that: include: Cooling towers; A vertical shaft, a water collection tank and a water collection tank are provided in the cooling tower, and the water collection tank connects the vertical shaft and the water collection tank; A plurality of outlet air temperature and air velocity measuring points are arranged at the throat of the cooling tower; The tower inlet air temperature measuring point is arranged at the periphery of the cooling tower; The atmospheric pressure measuring point is set at least 50m away from the cooling tower; The water temperature measuring point for entering the tower is arranged inside the vertical shaft; The outlet water temperature measuring point is located at the end of the water receiving tank; The outlet air temperature and air flow rate measuring points are arranged on two mutually perpendicular diameters in the form of equal-area rings, and there are no less than 10 outlet air temperature and air flow rate measuring points; 4 inlet air temperature measuring points are evenly arranged along the cooling tower, and are 1m away from the edge of the water collection tank and 1.5-2.0m away from the ground; the water collection trough is triangular, one end of which is connected to the vertical shaft and the other end is connected to the edge of the water collection tank; there are four water collection troughs; the vertical shaft is placed in the center of the cooling tower; the outlet air temperature and air flow rate measuring points are arranged There is an impeller anemometer; the outlet air temperature and air velocity measuring point and the inlet air temperature measuring point are both provided with a first platinum resistance thermometer; the resolution of the first platinum resistance thermometer is not less than 0.2°C, and the accuracy is not less than level 0.5; the accuracy of the impeller anemometer is ±0.1°C; the atmospheric pressure measuring point is provided with a barometer, and the accuracy of the barometer is not less than level 0.25; the inlet water temperature measuring point and the outlet water temperature measuring point are both provided with a second platinum resistance thermometer; the resolution of the second platinum resistance thermometer is not less than 0.1°C, and the accuracy is not less than level 0.5.

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