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Thermal trace type secondary air quantity measuring method and system

A secondary air volume and measurement method technology, which is applied in the application of thermal effects to detect fluid flow, etc., can solve the problems of volumetric flowmeters with large resistance, unsuitable for secondary air flow measurement, and unpredictable errors, etc., to achieve initial investment and daily maintenance Low cost, convenient data sharing, and convenient installation

Inactive Publication Date: 2009-07-01
NANJING UNIV OF SCI & TECH
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Volumetric flowmeters are not suitable for secondary air flow measurement due to their large resistance; in combustion equipment, there are a large number of secondary air outlets, and mass flowmeters (such as Coriolis flowmeters) cannot be used on a large scale due to their high price.
Therefore, in the conventional measuring device, only the velocity measuring element may be used for the flow measurement of the secondary air
[0004] The limiting factor for flow measurement of secondary air is that the channel structure cannot meet the requirements of conventional velocity-type measuring elements
There are three shortcomings of this classic method: First, whether the static pressure of an air duct and the opening of the damper can determine the air volume of the air duct is insufficient, and the theoretical basis is insufficient; The static pressure signal taken out before the damper is extremely unstable, and the signal has basically no practical value; finally, this method can only be calibrated in the cold state, and the error in the hot state cannot be estimated
Therefore, this classical method is only a qualitative measurement method, basically without the value of quantitative measurement

Method used

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  • Thermal trace type secondary air quantity measuring method and system
  • Thermal trace type secondary air quantity measuring method and system
  • Thermal trace type secondary air quantity measuring method and system

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Experimental program
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Embodiment 1

[0025] as attached image 3 As shown, the dotted arrow indicates that the signal of this path is connected to the control box 4. The measurement system uses the thermal tracer method to realize the programmed measurement of the secondary air flow, and the selected tracer is cold air. The high-pressure head (about 6KPa) cold air from the outlet of the blower 7 (before the air preheater) passes through the filter 8 and the cold air main pipe (diameter DN150) 9, and is sent to the four cold air headers 12 (pipe diameter) at the four corners of the furnace. DN150), eight cold air branch pipes 13 (pipe diameter DN100) are connected to each cold air header, and then connected to the secondary air duct 21 installed in the ) on the gas injection pipe 15 (pipe diameter DN50, nozzle diameter d=5mm, nozzle number n=20, nozzle row number is 2 rows, nozzle spacing L1=60mm, nozzle angle β=150°, gas distribution pipe position parameter L2= 100mm, L3 / L4=0.7), the above equipments (8, 9, 12,...

Embodiment 2

[0030] as attached Figure 4 shown. The measurement system selects desalted water as the tracer, uses the thermal tracer method to calibrate the functional relationship between the secondary air flow and the damper opening, and further completes the online measurement of the secondary air flow through the total flow of the secondary air box and the signal of the damper opening .

[0031] as attached Figure 4 The shown embodiment is a method of obtaining the flow rate by calibrating the opening of the damper, but it completely overcomes the three shortcomings of the classical method in the background technology. Flow meter 24, this flow meter indicates the total secondary air volume of this angle (because the measuring point position has a long straight pipe section, so conventional flow measurement means can be used); An accurate valve position sensor 23 is installed; the signals of the flowmeter 24 and the valve position sensor 23 are connected to the industrial control c...

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Abstract

The invention relates to a thermal tracing type secondary air flow measurement method and a system therefore, wherein a secondary air duct is arranged with a gas distribution tube and a detection tube, the length L4 of the gas distribution tube and an air door is 0.5 to 0.75 times of the diameter L3 of the secondary air duct, the tracer accurately measured by a tracer flux meter is filled into the main flow of an object secondary air duct via the gas distribution tube to be mixed completely in the duct and is detected at descending by the detection tube about tracker thermal parameters, the tracer flux and the tracer thermal parameters are collected by a control box, and the secondary air flux is calculated via energy and quality conservation to be output. The invention can be applied in special field while the straight part of the secondary air duct is not long enough, thus not being limited by the short duct structure of secondary air ducts. The flux and temperature of tracer can be accurately measured to improve the calculation accuracy on secondary air flux. The invention can obtain secondary air flux via online way by the tracer continuously provided.

Description

a technical field [0001] The invention belongs to the secondary air flow measurement technology of industrial combustion equipment, in particular to a heat tracing type secondary air flow measurement method and system thereof. Two background technology [0002] In industrial combustion equipment, the secondary air is the air that is sent into the furnace separately. The air flow and flow distribution of each secondary air channel directly affect the aerodynamic field and temperature field in the furnace. In order to meet the requirements of ignition, flame stabilization, load regulation, superheated steam temperature regulation, coking and slagging prevention, and NO control x Operational requirements such as generation rate and combustion efficiency optimization require reasonable configuration of the flow rate of each secondary air channel, and the premise of realizing a reasonable allocation of secondary air is the ability to measure the flow rate of the secondary air onl...

Claims

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Application Information

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IPC IPC(8): G01F1/68
Inventor 刘心志王益祥张后雷朱曙光
Owner NANJING UNIV OF SCI & TECH