CN2268923Y - Intellectual steam flowmeter with probing needle - Google Patents

Abstract

The utility model relates to an intelligent steam flowmeter with a probe, which is used for measuring flow for too hot steam with high temperature. The flowmeter adopts a rapidity probe and a temperature sensor which are calibrated in advance and can sense total pressure and static pressure and as sense members; a secondary instrument adopts a flow integrating instrument which can convert and process a signal and performs calculation according to a certain operational formula and directly displays consequences; a transmitting unit of the flow integrating instrument is a transmitter for piezoelectric conversion type pressure and a pressure difference. Compared with an orifice flowmeter, the utility model has the advantages of broad measuring range and high accuracy and is not affected by the variation of the size of flow. The utility model has no pressure loss, and thus a good deal of energy can be saved. The utility model also has the advantages of small size, good dependability, stable work, and convenient installation and maintenance, and thus the utility model can be widely used for measuring steam flow in a thermal power plant and a chemical plant.

Description

Intelligent probe formula steam-flow meter

The utility model belongs to the gas flow measurement device, relates to a kind of steam-flow meter that is used to measure high-temperature steam.

In the prior art, flow measurement for high-temperature steam, though its equipment and instrument are a lot, as turbo flow meter, electromagnetic flowmeter, orifice flowmeter and vortex shedding flow meter newly developed in recent years etc., all accurate measurement that is difficult to use in hyperthermia and superheating steam inadequately because of the restriction or the precision of serviceability temperature.Present most of cogeneration plant and chemical plant, the widely used orifice flowmeter that is still, its reason, orifice flowmeter is simple in structure on the one hand, low price; On the other hand, what orifice plate used is stainless steel material, and making sensitive element with orifice plate can anti-high temperature more than 500 ℃.So orifice flowmeter is still the domestic preferred unit that is used for measuring the high-temperature steam flow at present.But orifice flowmeter still has the following disadvantages and defective:

The one, be subjected to the influence of flow size bigger.When flow diminishes, will cause bigger measuring error.Experiment shows, when flow is 30% when following of ratings, because flow pattern changes, Reynolds number diminishes, and what adopt during flow accumulation is the steady flow coefficient of discharge in addition, thereby causes the flow measurement number less than normal and cause error.When flow during less than 10% ratings, pressure reduction sensing less than, flow is difficult to measure, and have to regard as zero, this often causes error because of customer flow is too small in the steam supply heat supply network of cogeneration plant, can bring massive losses to cogeneration plant up to 15% sometimes.The 2nd, the orifice flowmeter energy loss is bigger, and after using a period of time, because of wearing and tearing will cause measuring error, need stop steam supply and carry out maintain and replace, so workload is big.The 3rd, the used secondary instrument of orifice flowmeter adopts mechanical force balanced type pressure and differential pressure indicator more, its poor reliability, and easy drift at zero point, measuring accuracy is low.

For overcoming deficiency and the defective that prior art exists, the purpose of this utility model and task are to provide a kind of volume little for cogeneration plant and chemical plant, measuring accuracy height, no crushing, installation and maintenance are convenient, and can carry out the intelligent probe formula steam-flow meter that data processing and result show automatically.

The utility model is achieved through the following technical solutions: it is mainly by primary instrument, secondary instrument, and be contained in transducing unit between primary instrument and the secondary instrument, valve and pipeline are formed, primary instrument comprises impression head and temperature sensor, secondary instrument adopts can carry out the signal conversion processing, calculate by certain formula, and the flow integrator that the result is directly shown, transducing unit adopts pressure unit and pressure difference transmitter, it is characterized in that above-mentioned impression head adopts prior the demarcation well, can experience the velocity probe of stagnation pressure and static pressure, this velocity probe [1] is the tubular probe of metal, two groups of exploration holes are arranged above it, open in the probe termination for one group, another group is opened in probe outer tube side, is symmetrical distribution

Accompanying drawing 1 is a system construction drawing of the present utility model.

Accompanying drawing 2 is the A-A profile of accompanying drawing 1, is the structural drawing of velocity probe.

Describe principle of work of the present utility model, structure and specific embodiment in detail below in conjunction with accompanying drawing:

The utility model is mainly by velocity probe 1, temperature sensor 2, and pressure transducer and transmitter 3, pressure reduction passes sensor and transmitter 4, flow integrator 5, control valve 6,7,8 and equalizing valve 9 are formed.Velocity probe 1 is the tubular probe of the less metal of a kind of size, and two groups of exploration holes are arranged above, opens in the probe termination for one group, for single gaging hole 11, meets to air-flow, thereby can experience the stagnation pressure of air-flow on the measured position; Another group is opened in probe outer tube side, for being symmetrically distributed in pipe several side openings 12 all around, being generally 2-4 and being advisable.Air-flow can be experienced the static pressure of air-flow when flowing through along tubular axis.The pressure that these two groups of gaging holes are experienced is drawn by two pipelines of isolating mutually of probe interior respectively.Be that pipeline 13 is stagnation pressure tube, pipeline 14 is a static tube.Wherein static tube 14 is drawn two outlets again through behind the valve 7, and an outlet is led to pressure transducer and transmitter 3 through valve 8, and the low-pressure side of differential pressure pickup and transmitter 4 is led in another outlet; Stagnation pressure tube 13 is then guided the high-pressure side of this differential pressure pickup and transmitter into through valve 6.Like this, differential pressure pickup has just recorded the poor of the stagnation pressure at place, velocity probe position and static pressure.Because the error on making, the measured pressure of probe may have certain error with real pressure.Experiment shows that the manufacturing of this error and probe has relation, in case the probe completion of processing, this error has just been determined.Therefore, this error can remedy it by trial correction in advance, thereby obtains a correction coefficient.

During actual measurement, the probe of velocity probe is placed on pipeline center, measures Peak Flow Rate Vmax.But during actual pipeline flowed, the gas velocity on a certain cross section was uneven, and the center is higher and lower near the wall place.According to hydromechanical ultimate principle, if known the average velocity V on a certain cross section, (wherein G is a flow can to try to achieve the steam flow that flows through this cross section according to G=F γ V, F is that pipeline cuts, γ is a current density, and V is an average velocity).For specific mobility status, owing between average velocity and the maximal rate certain scale-up factor is arranged, this coefficient also can be measured out in advance by experiment, thereby obtains another correction coefficient.Twice prior correction coefficient of demarcating combined, can obtain a total correction coefficient K.So just obtained utilizing measured value to calculate the Practical Formula of pipeline steam flow: $G=K\left(\frac{{\mathrm{\&pi;<figure-callout\; id="2"\; label="d"\; filenames="Y9521647000061.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}{4}\right)\sqrt{\frac{2g\left(\mathrm{\&Delta;P}\right)}{\frac{(0.00471t+1.286)\&times;100}{P+100}-0.0097+1.32\&times;{10}^{-5}t}}$ In (wherein P is a stagnation pressure, and Δ P is a pressure reduction, and t is a temperature, and d is the tested pipeline diameter) following formula, pressure P and pressure differential deltap P can obtain pressure and pressure difference by velocity probe, and convert electric signal to by pressure transducer 3 and differential pressure pickup 4 respectively; Temperature sensor 2 adopts thermal resistance thermometer or thermopair, also exports electric signal, and these signals calculate flow G by flow integrator by following formula after conversion processing, and the result is directly shown.Pipe diameter d and correction coefficient K place calculation procedure as known quantity.

The utility model is compared with existing orifice flowmeter, has the following advantages and beneficial effect: This steam-flow meter measurement category is wide, and measure error is little, all can obtain when big flow and low discharge High certainty of measurement. No crushing can be saved big energy. Volume is little, good reliability, and work is steady Fixed, installation and maintenance are convenient, can be widely used in the measurement of the steam flow in steam power plant and chemical plant.

Claims (1)

1, a kind of intelligent probe formula steam-flow meter, it is mainly by primary instrument, secondary instrument, and be contained in transducing unit between primary instrument and the secondary instrument, valve and pipeline are formed, primary instrument comprises impression head and temperature sensor, secondary instrument adopts can carry out the signal conversion processing, calculate by certain formula, and the flow integrator that the result is directly shown, transducing unit adopts pressure unit and pressure difference transmitter, it is characterized in that above-mentioned impression head adopt demarcate in advance good, can experience the velocity probe of stagnation pressure and static pressure, this velocity probe [1] is the tubular probe of metal, and two groups of exploration holes are arranged above it, opens in the probe termination for one group, another group is opened in probe outer tube side, is symmetrical distribution.

Images