CN2297733Y - Large flow measuring device - Google Patents

Abstract

The utility model belongs to a large flow measuring device for pipelines to transport fluid, which is used for measuring the fluid flow in a large-scale flue or wind channel in a power station boiler. A main body installed on the measured pipeline is constituted by connecting two to four wind channel type venturis or wind tunnel type measurement channels in parallel, and the common inlet of the channel is provided with a rectifying grid. The utility model has the advantages of higher measuring precision, higher interference immunity and operating stability, relative convenience on site arrangement, can conduct fault self-examination, and can test the pressure difference and the reference source between the temperature and the main body hydrostatic pressure measuring point at any time.

Description

A kind of big flow measurement device

The utility model belongs to the pipeline transportation fluid flow rate measurement apparatus, and it is used for the large-scale cigarette of station boiler, air channel inner fluid flow measurement.

Flow measurement device is the important component part of power boiler burning, pulverized coal preparation system, and its performance and accuracy directly influence the economy and the security of boiler unit; In addition, well behaved flow measurement device is one of essential condition that realizes burning, pulverized coal preparation system robotization.The thermal power generation unit of homemade thermal power generation unit of China and early stage import mainly uses apparatus for measuring air quantity such as air channel type venturi, wing, bourdon's tube and double-venturi, all exists the problem that some are difficult to overcome to some extent.As: air channel type venturi wind measuring device body is bigger, needs to arrange relatively difficulty with bigger space in large-scale air channel; Airfoil type wind measuring device complex structure, gaging hole are easily stifled, and bad cleaning; The flow signal that flute type pitot tube provides a little less than; The flow signal fluctuation that double-venturi type wind measuring device provides is bigger, the stability requirement height of stream field.The problems referred to above cause the Flow Measuring System precision low, and shortcomings such as poor reliability are difficult to realization best combustion air distribution and combustion system and control automatically.

The purpose of this utility model is for overcoming above-mentioned shortcoming, providing a kind of flow measurement precision high flow measurement device.

Technical essential of the present utility model is: the body that is installed on the tested pipeline is composed in parallel by 2～4 air channel type venturi or wind tunnel type measurement passage (1), is provided with rectification grid (4) in the public inlet of passage.

The utility model has the advantages that: adopted split wind-tunnel shunt volume measuring method, made big flow measurement have higher measuring accuracy; Signal processing apparatus has adopted multiple Anti-Jamming Technique, makes total system that higher anti-interference and operation stability be arranged; Body length is shorter, and has rectification, and racemization function, the cigarette air channel straight section length that connects with its inlet be as long as can satisfy measurement requirement greater than 0.8 times of equivalent diameter, on-the-spot arrange more convenient; Can carry out fault self-checking, and can test pressure reduction, reference source between temperature, body hydrostatic measuring point at any time.

Description of drawings:

Fig. 1 is a structural representation of the present utility model;

Fig. 2 is that the utility model is connected schematic block diagram with flowmeter;

Set rectification grid (4) spacing is not more than 0.2 times of former cigarette air channel equivalent diameter in the utility model.Said body both ends are to link to each other with tested pipeline by flange (8) or welding.

On the wall that the throat (2) and the intake section (3) thereof of passage (1) are located, the hydrostatic pressure measuring point is housed, in order to measure the static pressure Δ P1 at two places; Hydrostatic pressure measuring point (being two passages shown in the figure) also is housed on the wall that the throat (6) and the intake section (5) of another passage (1) are located, in order to measuring the hydrostatic pressure value at two places, and obtains differential static pressure Δ P2 therebetween.Flange (7) is used to connect cigarette, air channel.

According to Hydrodynamics Theory, fluid is under the certain condition of temperature, have certain relation between the differential static pressure of longshore current journey and the fluid flow in the measurement passage, after with fluid temperature (F.T.) and density this relational expression being revised, can obtain the fluid flow under each flow operating mode.

According to above-mentioned principle, can be according to fluid density ρ, fluid temperature (F.T.) T, Δ P1, Δ P2 and relevant calibration coefficient, calculate to such an extent that measure passage (1) respectively and measure flow Q1, Q2 in the passage (1 ') (1 ' be that another passage, Q2 be the interior flow of another passage).

Total flow Q=Q1+Q2 then

In actual applications, Q1, Q2 exist certain relation with total flow Q respectively, promptly $K1Q\≤Q1\≤K_1^{\′}Q$ $K2Q\≤Q2\≤K_2^{\′}Q$

Wherein K1, K ' ₁, K2, K ' ₂All need to obtain by rating test, its value is different and different according to on-the-spot deployment scenarios (entry and exit boundary condition).Decidable has the utility model whether fault is arranged in view of the above.

Because the utility model has adopted racemization, rectification grid, thereby can improve the inlet boundary condition; Owing to adopt the measurement passage to divide body structure, the part that flow characteristics is different is separately measured, then with results added, add and improve measuring accuracy greatly.Do not have fluid total head measuring point in the utility model body, thereby the gaging hole possibility of jamming is reduced.

Each the test point institute number of winning the confidence employing flowmeter is handled in the body, used quantifier be with 8098 single-chip microcomputers be the intelligent measurement instrument formed of core, it adopts temperature transmitter, differential pressure transmitter converts temperature and pressure reduction to corresponding with it normalized current output 4～20mA.This electric current amplifies by the isolation of STC isolating transmitter, converts the voltage output of 1～5V to.Finish one tunnel temperature with 8098 single-chip microcomputers, the data acquisition of two-way pressure reduction, and set out differential pressure and flow thereof in order to the calculated with mathematical model of determining, and will move the electric current 4～20mA output of differential pressure value at last with standard, flow is shown by the LED charactron.Flowmeter also is provided with the toggle switch input element, the online correction of feasible system parameter, and have system's operation and fault indication function.

Claims (3)

1. big flow measurement device is characterized in that being installed on body on the tested pipeline and measures passage (1) by 2～4 air channel type venturi or wind tunnel type and compose in parallel, and is provided with rectification grid (4) in the public inlet of passage.

2. according to the described big flow measurement device of claim 1, it is characterized in that set rectification grid (4) spacing is not more than 0.2 times of former cigarette air channel equivalent diameter.

3. according to the described big flow measurement device of claim 1, it is characterized in that said body both ends are to link to each other with tested pipeline by flange (8) or welding.

Images