A thermal power generating unit feedwater flow measuring method
A technology of water supply flow and measurement method, which is applied in the direction of volume/mass flow generated by mechanical effects, and detection of fluid flow by measuring pressure difference, which can solve the problems of decreased measurement accuracy, low calculation accuracy of feed water flow, and loss
Active Publication Date: 2015-11-25
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 is 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] Step 2: Calcula...
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The invention provides a thermal power generating unit feedwater flow measuring method. The method comprises the steps of: determining the design working condition feedwater flow of a unit, the design working condition unit power, the feedwater pipe inner diameter, the to-be-measured working condition feedwater pressure, the feedwater temperature, the feedwater dynamic viscosity, the measuring point positions and the feedwater dynamic pressure of measuring points measured by a Pitot tube; calculating the feedwater flow rate at each measuring point; calculating the feedwater flow estimated value, the feedwater average flow rate, and the feedwater pipe interior flow Reynolds number; determining the feedwater flow rate distribution along the cross section of a pipe; by means of the feedwater flow rate distribution along the cross section of the pipe, calculating the relationship between the feedwater flow rates at the measuring points and the average feedwater flow rate and determining the flow rate weight of each measuring point; calculating the average feedwater flow rate and the feedwater flow by means of the measured feedwater flow rate at each measuring point and the flow rate weight of each measuring point; comparing the feedwater flow with the water flow initial value; if the deviation does not meet the requirement of precision, performing iterative computations until the deviation meets the requirement of precision; determining the feedwater 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