阅读说明：本技术 一种机力塔风机风量在线测量方法 (Online measuring method for air quantity of mechanical tower fan ) 是由 自平洋 赵玉柱 郝建刚 谢大幸 陈友良 樊蓉 徐婷婷 朱亚迪 于 2021-05-31 设计创作，主要内容包括：本发明公开了一种机力塔风机风量在线测量方法,步骤如下：(1)以温度测量替代风压测量；(2)通过凝汽器热负荷和水力计算得到单台机力塔的湿空气与冷却水换热量；(3)通过单台机力塔换热量及进出口空气参数计算风机风量。本发明利用机力塔空气侧进出口温湿度值和热负荷获得风机风量,风机处仅安装温度测点,更易布置且占用空间小,测点长期布置时阻力较低,抗干扰能力好,测量值波动性小。(The invention discloses an online measuring method for the air quantity of a mechanical tower fan, which comprises the following steps: (1) replacing wind pressure measurement with temperature measurement; (2) the heat exchange quantity of the wet air and the cooling water of the single mechanical tower is obtained through the heat load of the condenser and the hydraulic calculation; (3) and calculating the air quantity of the fan through the heat exchange quantity of the single mechanical tower and the air parameters of an inlet and an outlet. According to the invention, the temperature and humidity value of the air inlet and outlet of the mechanical tower and the thermal load are utilized to obtain the air quantity of the fan, only temperature measuring points are installed at the fan, the arrangement is easier, the occupied space is small, the resistance is lower when the measuring points are arranged for a long time, the anti-interference capability is good, and the fluctuation of the measured value is small.)

1. An online measuring method for the air quantity of a mechanical tower fan is characterized by comprising the following steps:

(1) replacing wind pressure measurement with temperature measurement

Considering the measurement of the air volume of the fan from the energy perspective, obtaining an indirect air volume measurement value by measuring the temperature of an air inlet and an air outlet of the mechanical tower, the humidity of the inlet air and the atmospheric pressure and combining the heat load of a condenser, and getting rid of the traditional calculation method based on the air pressure and the fan characteristic curve;

(2) the heat exchange quantity of the wet air and the cooling water of a single mechanical tower is obtained through the calculation of the heat load of a condenser and the hydraulic power

Establishing a hydraulic calculation model of a circulating water pipeline to obtain the cooling water distribution coefficient of each mechanical tower under different condenser cooling water outlet pressures, and considering that the coefficient is also the coefficient distributed by the condenser heat load among the towers, namely the heat exchange quantity of the humid air and the cooling water of a certain mechanical tower is equal to the cooling water distribution coefficient of the mechanical tower multiplied by the condenser heat load;

(3) calculating the air quantity of the fan through the heat exchange quantity of the single mechanical tower and the air parameters of the inlet and the outlet

The heat exchange quantity of the wet air and the cooling water of the single mechanical tower is obtained through calculation by the method, and the fan air quantity of the mechanical tower is obtained through calculation by combining the enthalpy value difference of an outlet at the air side of the mechanical tower and the outlet air density.

2. According toThe method for on-line measuring the wind volume of the mechanical tower fan as claimed in claim 1, wherein the wind volume is obtained by hydraulic calculation from the outlet pressure of the cooling water of the condenser and the characteristics of the cooling water pipeiProportionality coefficient of cooling water quantity of mechanical tower to total cooling water quantity of condenserα _i(ii) a The heat load of the condenser is obtained through the calculation of the side heat of the steam turbineQ(ii) a Approximately consider thatiThe heat exchange quantity of the wet air and the cooling water of the power tower is equal toα _iAndQthe product of (a).

3. The method for on-line measuring the fan air volume of the mechanical tower as claimed in claim 1 or 2, wherein the heat exchange quantity of the wet air and the cooling water of a single mechanical tower, the air parameters of an inlet and an outlet and the fan air volume of the mechanical tower are obtained by calculation.

Technical Field

The invention relates to an air quantity online measuring method, in particular to an air quantity online measuring method for a mechanical tower fan.

Background

In the cold end test process of the current generator set with the mechanical tower, the air quantity of a fan of each cooling tower is difficult to determine, the air quantity is an important measurement index in the performance test of the cooling tower, and the accuracy of the cooling capacity calculation of the cooling tower is influenced by influencing the steam-water ratio. According to the regulation of air flow measurement of the mechanical draft cooling tower: the measuring points are preferably arranged on the section of the air duct on the suction side of the fan, the vertical distance between the test section and the axis of the fan blade is preferably not less than 0.4m, the measuring point arrangement adopts an equal-area ring method, and each equal-area ring is preferably not more than 3m²。

According to the regulations, the wind speed measurement has high requirements on the installation of the measuring point, and a specially reinforced device is needed to meet the measurement safety requirements during the running of the fan. Under the condition that the field condition does not allow, the air quantity is indirectly calculated by a method of carrying out proportion conversion according to the designed air quantity, and a large error exists in the calculation. The air volume measuring environment is a damp and hot condition, and the requirement on the instrument is higher for long-term measurement. At present, a method for measuring the air quantity of a fan on line is lacked, and the measurement is only carried out when the performance of a mechanical tower is tested.

In the prior art, a shell below the cross section of a fan needs to be punched, and then pitot tubes are used for sequentially measuring on division grid points, so that the operation is complex, the precision is not easy to guarantee, and the operation safety is influenced; the prior art is not suitable for on-line measurement, and the on-line arranged wind pressure measuring device is easily corroded by water vapor, is easily corroded and scaled, and is not beneficial to stable measurement.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, provides an online measuring method for the air volume of a mechanical tower fan, and fills the blank of the online measuring technology for the air volume of the mechanical tower fan.

The technical scheme adopted by the invention for solving the problems is as follows: an online measuring method for the air quantity of a mechanical tower fan is characterized by comprising the following steps:

(1) replacing wind pressure measurement with temperature measurement

The method is characterized in that the measurement of the air volume of the fan is considered from the energy perspective, an indirect air volume measurement value is obtained by measuring the temperature of an air inlet and an air outlet of the mechanical tower, the humidity of the inlet air and the atmospheric pressure and combining the heat load of a condenser, and the traditional calculation method based on the air pressure and the fan characteristic curve is eliminated.

(2) The heat exchange quantity of the wet air and the cooling water of a single mechanical tower is obtained through the calculation of the heat load of a condenser and the hydraulic power

And establishing a hydraulic calculation model of a circulating water pipeline to obtain the cooling water distribution coefficient of each mechanical tower under different condenser cooling water outlet pressures, and considering that the coefficient is also the coefficient distributed by the condenser heat load among the towers, namely the heat exchange quantity of the humid air and the cooling water of a certain mechanical tower is equal to the cooling water distribution coefficient of the mechanical tower multiplied by the condenser heat load.

(3) Calculating the air quantity of the fan through the heat exchange quantity of the single mechanical tower and the air parameters of the inlet and the outlet

The heat exchange quantity of the wet air and the cooling water of the single mechanical tower is calculated by the method, and the fan air quantity of the mechanical tower is calculated by combining the enthalpy value difference of an outlet at the air side of the mechanical tower and the outlet air density.

Further, a proportionality coefficient alpha of the cooling water quantity of the I-type power tower to the total cooling water quantity of the condenser is obtained through hydraulic calculation according to the outlet pressure of the cooling water of the condenser and the characteristics of the cooling water pipe_i(ii) a Obtaining the heat load Q of the condenser through the calculation of the side heat of the steam turbine; approximately considers that the heat exchange quantity of the wet air and the cooling water of the I-type mechanical tower is equal to alpha_iThe product of Q.

Further, the heat exchange quantity of the wet air and the cooling water of the single mechanical tower and the air parameters of the inlet and the outlet are calculated, and the air quantity of the fan of the mechanical tower is calculated.

Compared with the prior art, the invention has the following advantages and effects: according to the invention, the temperature and humidity value of the air inlet and outlet of the mechanical tower and the thermal load are utilized to obtain the air quantity of the fan, only temperature measuring points are installed at the fan, the arrangement is easier, the occupied space is small, the resistance is lower when the measuring points are arranged for a long time, the anti-interference capability is good, and the fluctuation of the measured value is small.

Drawings

FIG. 1 is a diagram of the arrangement of the measuring points in the method of the present invention.

FIG. 2 is a computational flow diagram of the method of the present invention.

In the figure: the measuring point I1, the instrument box I2, the measuring point III 3, the measuring point IV 4, the measuring point V5, the instrument box II 6 and the measuring point VI 7.

Detailed Description

The present invention will be described in further detail below by way of examples with reference to the accompanying drawings, which are illustrative of the present invention and are not to be construed as limiting the present invention.

Examples

In the embodiment, any mechanical tower configured by a single gas-steam combined cycle unit is taken as an object, and the arrangement and the material size of a circulating water pipeline are known. As shown in fig. 1, a plurality of temperature measuring points I1 are arranged at different radial distances at 40-50cm below a fan, and the terminal ends of all the temperature measuring points I1 are arranged in an instrument box I2; a second temperature and humidity and atmospheric pressure measuring point and terminal equipment thereof are arranged in a second instrument box 6 which is 5-10m away from the outer wall of the mechanical tower at the upstream of the normal wind direction; the side of the steam turbine is provided with a third measuring point 3 and a terminal thereof for pressure, temperature and flow of inlet and outlet steam and hot steam, a fourth measuring point 4 and a terminal thereof for motor power, a fifth measuring point 5 and a terminal thereof for pressure of a condenser cooling water outlet, and a sixth measuring point 7 and a terminal thereof for condensation water pressure and temperature; the measuring points three 3, four 4, five 5 and six 7 can obtain data in most of power plant DCS systems.

The specific calculation flow is shown in fig. 2, and the online measuring method for the air quantity of the mechanical tower fan comprises the following steps:

(1) and establishing a hydraulic calculation model of the cooling water pipeline, calculating the cooling water flow of each cooling tower under the condition of different condenser cooling water outlet pressures, and calculating the deviation adjustment calculation parameters of the total cooling water flow and the measured value through comparison. The pipeline resistance is calculated according to the existing standard method, and the gravity pressure drop calculation formula is as follows: Δ p_wρ gh; the on-way resistance pressure drop calculation formula is as follows:the local resistance pressure drop calculation formula is as follows:

wherein, λ represents an on-way resistance coefficient, and the unit is 1; l represents the length of the flow channel and has the unit of m; w represents the flow velocity of the fluid in the tube in m/s; d_nRepresents the internal diameter of the pipe section in m; rho represents the density of water, and 1000kg/m is taken³(ii) a ζ represents the local drag coefficient of the pipe section, in units of 1.

In the calculation working condition of the embodiment, the unit is provided with 6 mechanical towers. Various data calculated by a hydraulic calculation model of the cooling water pipeline are as follows, wherein the calculation result of the single-tower heat load distribution coefficient obtained by calculation is as follows:

(2) in the calculation of the heat load of the condenser, the circulating water flow is difficult to confirm, so in the calculation condition of this embodiment, parameters closely related to the calculation of the heat load of the condenser are selected, and the main parameter values are as follows:

the heat load of the condenser is the difference value of the steam exhaust heat of a low-pressure cylinder of a steam turbine and the heat of condensed water, namely the latent heat of vaporization of cooling water entering the condenser taken away by heat exchange, and the specific calculation formula is as follows: q ═ Q₁-q₂+q₃+q₄-q₅-q₆P, where Q represents the condenser heat load in MJ.h^-1；q₁The unit of the high-pressure steam inlet heat of the steam turbine is MJ.h^-1；q₂The unit of the high-pressure exhaust heat of the steam turbine is MJ.h^-1；q₃Represents the heat of medium-pressure steam admission of the steam turbine and has the unit of MJ.h^-1；q₄Represents the heat quantity of low-pressure steam of the boiler and has the unit of MJ.h^-1；q₅Expressing the heat supply and the exhaust steam heat with the unit of MJ.h^-1；q₆Represents the heat of the condensed water and has the unit of MJ.h^-1(ii) a p denotes turbine electronicsThe unit of the electric energy generated by the machine per hour is MJ.h^-1。

(3) In this embodiment, a mechanical tower No. 1 is taken as an example for calculation, and a calculation formula of a corresponding single-tower heat exchange amount is as follows: q₁＝Q*α₁Wherein Q is₁Represents the heat exchange quantity of No. 1 mechanical tower with the unit of MJ.h^-1；α₁And the unit of the distribution coefficient of the cooling water flow of the No. 1 mechanical tower is 1.

In this embodiment, the heat exchange amount of the power tower No. 1 is calculated, and the calculation result is as follows:

condenser heat load/MJ.h-1	Heat load distribution coefficient of mechanical tower	Heat exchange quantity/MJ.h of mechanical tower-1
			620880.7	0.189	117346.4

(4) In this embodiment, the single tower inlet and outlet air parameters calculated by the mechanical tower air side parameter calculation method are provided, and the calculation results are as follows:

item	Temperature/. degree.C	Humidity/%)	Air pressure/kPa	Density/kg m-3	Enthalpy value/kJ.kg-1
						Inlet air of mechanical tower	29	66	102.3	/	71.4
Air at the outlet of the mechanical tower	33	100	102.3	1.095	115.7

(5) In this embodiment, the calculation of the fan air volume of the single tower is based on the fact that the heat dissipation capacity of the water side is consistent with the heat absorption capacity of the air side, and the specific formula of the computer power tower air volume is as follows:wherein M represents the air volume of the single-tower fan and the unit is M³·h^-1；Q₁Represents the heat dissipated by a single cooling tower through air and has the unit of MJ.h^-1(ii) a ρ represents the density of air at the outlet of the fan in kg · m^-3；h₂Expressing the enthalpy value of the air at the outlet of the cooling tower fan, and the unit is kJ kg^-1；h₁Expressing the enthalpy value of the air at the inlet of a fan of the cooling tower, and the unit is kJ kg^-1。

Those not described in detail in this specification are well within the skill of the art.

Although the present invention has been described with reference to the above embodiments, it should be understood that the scope of the present invention is not limited thereto, and that various changes and modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention.