A method for measuring the feedwater flow rate of a thermal power unit
A technology of feed water flow and measurement method, which is applied in the direction of volume/mass flow generated by mechanical effects and the detection of fluid flow by measuring pressure difference, which can solve the problems of low calculation accuracy of feed water flow, increased power consumption of feed pumps, and decreased measurement accuracy. , to achieve the effect of being beneficial to economy, reducing throttling loss and high calculation accuracy
Active Publication Date: 2018-04-03
SOUTHEAST UNIV
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Problems solved by technology
Under certain conditions, this method has the advantages of simplicity and intuition, but this method has the following disadvantages: First, it will cause a large throttling loss when measuring the feedwater flow, which will increase the power consumption of the feedwater pump and affect the thermal economy of the unit Second, when the unit is running with variable load, the measurement accuracy will decrease
This method indirectly calculates the feedwater flow rate by measuring the condensate flow rate. The advantage is that the condensate water parameter is lower than that of the feedwater, the measurement accuracy is high, and the throttling loss is small. , more parameters and links bring greater uncertainty, making the calculation accuracy of feed water flow lower
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[0047] A method for measuring the feedwater flow rate of a thermal power unit. The measuring element used is a Pitot tube. On the section of the water supply pipeline to be tested, the length r=0, r=0.4R, r=0.8R, r=0.8R, and r are selected along the radius direction from the center of the section circle. =0.95R four points as measuring points, such as figure 2 As shown, the output parameter of Pitot tube is the dynamic pressure Δp of each measuring point i (Pa).
[0048] The determination steps are as follows:
[0049] Step 1: Initial parameter determination
[0050] Take the unit power P under the design working condition el0 (MW), design condition feed water flow D w0 (t / h), the inner diameter of the water supply pipe d (m).
[0051] Measure the unit power P in the working condition to be tested el (MW), water supply pressure p w (MPa) and feed water temperature t w (°C), calculate feed water density ρ(kg / m 3 ) and feedwater dynamic viscosity η (Pa·s).
[0052]Ste...
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The invention discloses a method for measuring the feed water flow of a thermal power unit. The feed water flow rate of the unit design working condition, unit power, the inner diameter of the feed water pipeline, the feed water pressure under the working condition to be measured, the feed water temperature and the feed water dynamic viscosity are taken; the position of the measuring point, the Pitot tube measurement The dynamic pressure of the feed water at the measured point is obtained. The flow velocity of the feed water at each measuring point is obtained by calculation, the estimated value of the feed water flow, the average velocity of the feed water, and the Reynolds number of the flow in the feed water pipe are calculated, and the velocity distribution of the feed water along the section of the pipe is determined. Using the velocity distribution of the feed water along the pipe section, the relationship between the feed water velocity at the measuring points and the average feed water velocity is calculated, and the velocity weights at each measuring point are determined. Using the feedwater velocity measured at each measuring point, combined with the velocity weights at each measuring point, calculate the average feedwater velocity and feedwater flow, and compare them with the initial value of the feedwater flow. If the deviation does not meet the accuracy requirements, iterative calculation is performed until the deviation To meet the accuracy requirements, determine the water flow.
Description
technical field [0001] The invention relates to a method for measuring the feedwater flow of a thermal power unit. Background technique [0002] Feedwater flow is an important parameter that needs to be detected in the automatic control system of thermal power units. Its measurement accuracy is directly related to the quality of feedwater regulation. At the same time, feedwater flow is also an important factor affecting the economic indicators of thermal power units, which is related to the calculation results of performance indicators. accuracy. Therefore, the accurate measurement of unit feedwater flow is of vital significance to the unit's online performance monitoring, process control, operation optimization, economic analysis, and energy saving and consumption reduction. [0003] At present, there are two main types of methods for measuring the feedwater flow of thermal power units: direct measurement and indirect measurement. Direct measurement method, that is, using...
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IPC IPC(8): G01F1/36
Inventor 王培红王德鹏赵刚苏志刚郝勇生
Owner SOUTHEAST UNIV