CN201229189Y - Inserted ASME nozzle flow meter - Google Patents

Abstract

The utility model relates to a plug-in ASME nozzle flow measuring device, which is an ASME nozzle with a front and a rear straight pipes and a divergent segment. Downstream pressure tapping adopts a throat pressure tapping mode, and the diameter of a throat pressure tapping hole is 0.2d, and pressure signals measured by each throat pressure tapping hole is taken out by the downstream pressure tapping hole after voltage sharing by a ring casing. The plug-in ASME nozzle flow measuring device is used to measure gas flow in a rectangular and a circular big pipes, and is particularly suitable for measuring flow quantity in primary air, secondary air, smoke gas and the like of heat power plants which contain more dust.

Description

Plug-in type ASME nozzle flow measurement mechanism

Affiliated technical field:

The utility model relates to a kind of differential pressure type insert type flow measuring device, is used for the measurement of gas flow in rectangle, the circular large pipeline, is specially adapted to the measurement that the wind in fuel-burning power plant, secondary air, flue gas etc. contain the high fluid flow of dust.

Background technology:

At present,, often adopt the differential pressure type insert type flow measuring device, commonly used Verabar flowmeter, Annular Round Model PFB, the many larynxs of plug-in type footpath wind measuring device arranged, insert combined type double-venturi nozzle apparatus for measuring air quantity the measurement of gas flow in the large pipeline.Wherein, Verabar flowmeter, Annular Round Model PFB all are average rate cast flowmeters, and differential pressure signal is little, and can only be used for the measurement of clean fluid flow.When being used for the measurement of dusty gas, measuring accuracy and anti-blocking problem become a pair of contradiction, still do not have at present solution.The many larynxs of plug-in type footpath wind measuring device, insertion combined type double-venturi nozzle apparatus for measuring air quantity then have differential pressure signal on the low side, to the not high enough shortcoming of low discharge accuracy of detection.

Summary of the invention:

In order to overcome the above-mentioned deficiency of large pipeline flow measurement, the utility model provides a kind of plug-in type ASME nozzle flow measurement mechanism.It is the ASME nozzle that has forward and backward straight length and diffuser, and throat's ways of measure pressure is adopted in the downstream pressure, and throat's pressure port diameter is 0.2d, and the pressure signal that each throat's pressure port measures is taken out by the downstream pressure port after ring casing is all pressed.This utility model has solved following technical matters: (1) pressure port is difficult for stopping up; (2) differential pressure signal is big, ripple disable; (3) measuring accuracy height, good linearity.

The technical scheme that its technical matters that solves the utility model adopts is: (1) increases diffuser after standard A SME nozzle, to reduce crushing, improves the rate of flow of fluid by the ASME nozzle, thereby improves the output differential pressure.(2) adopt throat's ways of measure pressure, improve measuring accuracy, make output signal have favorable linearity.(3) strengthen throat's pressure port diameter, take into account measuring accuracy and anti-blocking property, fundamentally solve the susceptible to plugging problem of pressure port.(4) upstream of ASME nozzle is the preceding straight length of elliptic arc profile inlet, makes fluid steadily flow into the ASME nozzle and convection cell carries out rectification from large pipeline; There is back straight length in the downstream of ASME nozzle, makes fluid steadily flow into large pipeline.The rectification current stabilization effect of forward and backward straight length makes the output differential pressure signal stable, ripple disable.

The beneficial effects of the utility model are: pressure port is difficult for stopping up, and realizes non-maintaining operation; Improved measuring accuracy; Stable differential pressure signal helps realizing the automatic control of flow.

Description of drawings:

Below in conjunction with drawings and Examples the utility model is further specified.

Fig. 1 is a plug-in type ASME nozzle flow measurement mechanism sectional view.

Among the figure, 1. flow detecting element, 2. upstream pressure port, 3. web member, 4. lower flange, 5. upper flange, 6. securing member, 7. upstream pressure pipe, 8 downstream pressure pipes, 9. flange gasket, 10. downstream pressure port, 11. downstream pressure ring casings, 12. throat's pressure ports.

Embodiment:

Measure the flow in the large pipeline, on the large pipeline wall, longshore current body flow direction is opened the square hole of a 90mm * 300mm, and lower flange (4) is welded on this square hole place.Flow detecting element (1) and upper flange (5) weld together by web member (3), and flow sensor (1) is inserted in the large pipeline by lower flange (4), make MEDIA FLOW to Fig. 1 indicate consistent.

For ease of explanation, flow sensor (1) is divided into seven sections of L1～L7.The elliptic arc profile inlet of fluid by the L1 section enters straight length before the cylindrical shape of L2 section, measures upstream pressure and takes out through upstream pressure pipe (7) from upstream pressure port (2); Fluid enters the ASME nozzle cylindrical shape throat of L4 section through the ASME of L3 section nozzle contraction section then, measure throat pressure from throat's pressure port (12), the throat pressure that each throat's pressure port (12) measures is all pressed in grading ring chamber, downstream (11) after taken out by downstream pressure port (10), downstream pressure pipe (8), last fluid through the diffuser of L5 section enter the L6 section after straight length, the conical outlet by the L7 section flows into large pipeline again.The pressure signal that upstream pressure pipe (7) and downstream pressure pipe (8) take out constitutes a pair of differential pressure signal, and under certain industrial and mineral (pressure, temperature), the size of differential pressure signal is represented the size of flow.By measuring differential pressure signal, can calculate the flow that flows through large pipeline in conjunction with industrial and mineral temperature, pressure signal.

The elliptic arc profile inlet of L1 section is difficult for forming eddy current when fluid is entered; The straight length convection cell plays the current stabilization rectified action before the cylindrical shape of L2 section, makes fluid satisfy measurement requirement; The ASME nozzle contraction section of L3 section increases flow velocity, and pressure reduces, and pressure can be converted to kinetic energy.Can significantly reduce the percent uncertainty of efflux coefficient C value in the pressure of the ASME of L4 section nozzle cylindrical shape throat, that is improve measuring accuracy, make output signal have favorable linearity.The effect of the diffuser of L5 section is to reduce crushing, improves the rate of flow of fluid by the ASME nozzle, thereby improves the output differential pressure.The back straight length of L6 section and the conical outlet of L7 section make fluid steadily flow into large pipeline.The fluctuation that the back straight length of straight length and L6 section helps reducing to export differential pressure signal before the cylindrical shape of L2 section.

Claims (3)

1, a kind of plug-in type ASME nozzle flow measurement mechanism, by flow detecting element, web member and flange are formed, and it is characterized in that: flow detecting element adopts the ASME nozzle of band diffuser, and the downstream ways of measure pressure is throat's pressure.

2, insert type flow measuring device according to claim 1, the pressure signal that each throat's pressure port measures is taken out by the downstream pressure port after ring casing is all pressed.

3, insert type flow measuring device according to claim 1 adopts the big pressure port diameter 0.2d of throat.

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