CN86202980U - Apparatus for measuring the flow of the coal dust through in blast furnace - Google Patents

Abstract

The utility model relates to a measuring device for measuring the flow rate of the single branch pipe of the coal blow of a blast furnace. The measuring device uses flow noise as detection signals to directly measure out the mass flow rate of gas-solid double-phase fluid powder lot. A microcomputer is used to do the on-line measurement of the flow rate of a blowing branch tube in view of a specific system of the coal blow of the blast furnace. The utility model centrally displays a print report, and uses an electronic scale on site to do automatic on-line calibration and correction when the electrical property of the coal variety changes.

Description

Apparatus for measuring the flow of the coal dust through in blast furnace

Pulverized coal injection in blast furnace list arm flow measurement device is applicable to single arm flow measurement of pulverized coal injection in blast furnace, also is applicable to the on-line measurement of mass flow rate of solid of the gas-solid two-fluid of similar system.

The flow measurement of present known gas-solid double-phase fluid in the world is two-parameter measurement normally, must detect duty concentration and the speed of solid material in conveyance conduit simultaneously, calculates flow then.In the flow process of gas-solid double-phase fluid, online detectable concentration and speed all are more complicated, thereby flow on-line measurement difficulty and make the installation cost costliness relatively.External commonly used have a following several types: 1, directly detect the physical quantity that is proportional to pipeline inner fluid quality, be proportional to the Coliabs power (coriolis force) of quality in the pipeline as utilization, the problem that exists is that (1) can't accurately distinguish mass flow rate of solid and gas mass flow at present.(2) sensing device is too accurate, safeguards and uses more complicated.2, make the mass flowmeter of electricity consumption difference method, a convergent divergent channel promptly is installed on pipeline,, calculate solid masses ratio and gas rate of discharge, thereby calculate the mass flow rate of solid rate by measuring the pressure differential on the direct sum convergent divergent channel.Adopt this method to measure, be used to detect difficult solution of differential pressure transmitter of gas-solid double-phase fluid, under the situation especially for high concentration.3, by measuring concentration respectively and speed is obtained flow, typical method is a static content survey concentration, and with cross-correlation method degree of testing the speed, this method material moisture variable effect is very big, and material adheres on tube wall and causes the instrument zero drift.

The objective of the invention is to propose a kind ofly to be applicable to that industrial online application can directly measure the device of the solid powder mass rate of flow of gas-solid double-phase fluid.

The present invention is that the employing flow noise is a detection signal, measures gas-solid double-phase fluid solid powder mass rate of flow.Its ultimate principle is as follows: gas-solid double-phase fluid is random turbulence state in conveyance conduit, is superimposed with small random fluctuation in the solid concentration in the local space, and the fluctuation of this concentration is called flow noise.Flow noise is the build-in attribute that gas-solid double-phase fluid must take place in flow process, it results from the fluctuation of carrying gaseous tension, the heterogeneity of solid blanking, the collision of solid particle and tube wall and reflection such as collide at multiple reason between the solid particle, directly the flow noise that extracts contains the fluctuation of concentration that above-mentioned multiple reason causes, it is a kind of random signal, for guaranteeing the stationarity of noise signal, must take the statistical measurement method, extract the higher noise signal of flow noise Mid Frequency.This part flow noise is the collision and reflection generation by solid particle, has single rectilinearity relation with the mass flow rate of solid rate.

At conveyance conduit a capacitance sensor is installed; The electric field space that gas-solid double-phase fluid consists of by sensor; Because the existence of solid particle has changed the spatial dielectric constant; The capacitance of sensor is changed corresponding to solid concentration; The small random fluctuation of high frequency contained in the electric capacity degree is proportional to flow noise; Transmitter converts the capacitor noise signal to the voltage signal X(t that processes for secondary meter); By a large amount of on-line dynamic measurement evidences when sensor transducer is reasonable in design

$\sqrt{\mathrm{E\; ［X}{}^2\mathrm{(t)］}}$ ＝lim 1/(T) ∫ ₀ ^TX ²（t）dtαM（t）

M(t in the formula) is solid masses amount rate of discharge, therefore, can measures the mass flow rate of solid rate as long as the transmitter output signal is carried out line rectification and integral mean.

It mainly is to be pieced together by two semicircle type electrode pairs as shown in Figure 2 for a capacitive transducer, sensor must be able to be taken into account energy operate as normal when coal dust conducts electricity, enough sensitivity is arranged when coal dust insulate, therefore adopt the frame mode that on half of pole piece, adds insulation course, another pole piece ground connection.

To the stable solid powder of electrical characteristics (as bituminous coal, cement, lime, flour ...) pick-up unit-through demarcating, can use that is developed into according to this principle.And for this solid material of stone coal, its electrical characteristics need only and carry out online correction on the bases of above-mentioned detection method often with different change of kind of every batch of coal, to adapt to the anthracitic special object of present China blast furnace blowing.Online dynamic correction principle is that employing time weight calculates the real traffic rate, compare with the measured value at one time, pass through linear regression method, determine the slope A and the intercept B that measure calibration curve, revised then, when thereby the electrical characteristics that guarantee solid dielectric change, reach due measuring accuracy.

When coal dust passes through the space electric field of capacitive transducer, the electric capacity of (resembling shown in Figure 3) sensor changes, make the oscillation frequency fo of oscillator A also produce corresponding change △ f, convert frequency change to change in voltage △ V(t through regulator C), be divided into two-way then, one the tunnel through low-pass filter D, takes out the voltage signal △ V(t that rises corresponding to mean concentration), with a fixed reference potential V _sIt is poor relatively to ask, and amplifies through comparison amplifier E then, produces FEEDBACK CONTROL electricity V _oBe added on the varactor, (F is the conversion of electricity-electric capacity, is mainly finished by varactor) changes the equivalent electric capacity of varactor, because varactor also and be added in the tank of oscillator A, thereby compensated because average

The frequency change that concentration causes makes oscillation frequency autostable at centre frequency f _oOn.Another road signal △ V(t) through Hi-pass filter G.Take out small high frequency flow noise △ V(t) amplify through high-gain, at last with the voltage signal (X of flow noise _t) send.Transmitter is owing to adopt the frequency modulation working method, thereby sensitivity is very high, antijamming capability is strong, adopt the low frequency negative-feedback closed-loop circuit, make the sensor output that the solid particle mean concentration causes, ambient temperature, humidity, adhesion and the drift of circuit itself or the like of solid particle on tube wall influences, all can be removed effectively, and the flow noise signal of high frequency is not produced any influence.

To X(t) signal carries out all square computing, perhaps carries out line rectification and integral mean computing simply, then can carry out flow measurement.

X=√ E ［ X ²Or ［ | X(t) | ］ (t) ］

M＝AX＋B

A, B are and the solid material bulk density in the formula, the measurement coefficient relevant with the solid material electrical characteristics, and when measured medium fixedly the time, A, B are constant.

Advantage of the present invention: realize the one-parameter measurement, measuring process is greatly simplified, and cost is low, is applicable to that commercial Application is particularly useful for single arm flow measurement of pulverized coal injection in blast furnace, safeguards simple, not fragile.

Fig. 1 is the calibration curve between actual real traffic and the measurement.

Fig. 2 is capacitor sensor structure figure.

Fig. 3 is the schematic block circuit diagram of transmitter.

Fig. 4 is the diagrammatic sketch block diagram of blast furnace pulverized coal list arm measuring system.

Describe one embodiment of the present of invention in conjunction with Fig. 4, A is the coal storage batch can, and B is for measuring the electronic scale pressure head output signal B(t of batch can weight), P ₁-P _nBe several coal jetting branch, T ₁-T _nBe sensor and the transmitter installed on corresponding each arm, output signal is X ₁(t) ... X _n(t) Z ₁-Z _nBe the line rectification integrating circuit, C is a multicircuit switch, and D is a controllable gain amplifier, and E is an A/D converter, and F is a microcomputer, and G is CRT, and H is a printer, and I is that IEEE488 interface J is 192 mathematics voltage tables able to programme.During normal the measurement, the instantaneous delivery measured value of each arm of CRT centralized displaying and corresponding absolute altitude light beam, and each arm integrated flux and total integrated flux can be at any time or the timed print measurement result.

After computing machine enters the demarcation revision program, automatically cylinder is elevated to a fixed value, at first revise the gain of controllable gain amplifier D, A/D converter can be operated in the full range, take out a jar weight difference △ W by the IEEE488 interface from 192 second every Fixed Time Interval △ T then _iGive computing machine, the weight △ of this minimizing _MiSo the i.e. coal dust weight that several arms spray altogether in the △ T time is total flow M _i(t) be

M _i（t）＝ (△W _i)/(△T)

Meanwhile, computing machine is with the total cumulative flow value X of each arm in the detected △ T time _i(t) calculate

At this moment nominal data M _iAnd X _iDeposit calculator memory in, along with winding-up is carried out, tank pressure reduces gradually, the corresponding minimizing of flow is fetched when computing machine and to be given the calibration given data, or receives operating personnel's keyboard commands, promptly change the linear regression processing of nominal data over to, obtain and demarcate constant A, B, then former demarcation constant is revised, and gone back to process of measurement automatically.

Each demarcation correction time is no more than 15 minutes, and according to field condition, every batch of coal can spray several days to tens days, so every demarcation once can guarantee to use more than one day at least.

Claims (4)

1, a kind of measurement mechanism of pulverized coal injection in blast furnace list arm flow is characterized in that this device is by the capacitor noise sensor, the frequency modulation transmitter, and microcomputer system special interface circuit and high precision 192 digital voltmeters constitute.

2, device according to claim 1 is characterized in that the capacitor noise sensor adopts two half gardens to piecing together structure, and one of them electrode adds shielding insulation, and another pole piece is by tube wall ground connection.

3, it is characterized in that utilizing the frequency modulation principle to convert the small capacitance variable signal that capacitive transducer produces to voltage signal according to the described device of claim 1, and gating negative-feedback circuit in addition, eliminate slow-changing signals and (comprise average solids concentration, solid powder adheres to the capacitance variations cause and extraneous thermal effect etc. at tube wall), extract steadily flow noise signal at random.

4, match with on-site solids powder jar electronic scales according to the described device of claim 1, by the microcomputer measuring system automatically control finish, through dynamic on-line proving and regression Calculation, revise and measure constant, measure to adapt to different electrical characteristics powder flows.

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