CN105444833A - Pressure equalizing chamber, mounting method thereof and three-dimension space multi-point pressure measuring and cross section type gas flow measuring device containing pressure equalizing chamber - Google Patents
Pressure equalizing chamber, mounting method thereof and three-dimension space multi-point pressure measuring and cross section type gas flow measuring device containing pressure equalizing chamber Download PDFInfo
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- CN105444833A CN105444833A CN201510977227.6A CN201510977227A CN105444833A CN 105444833 A CN105444833 A CN 105444833A CN 201510977227 A CN201510977227 A CN 201510977227A CN 105444833 A CN105444833 A CN 105444833A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
- G01F15/02—Compensating or correcting for variations in pressure, density or temperature
- G01F15/04—Compensating or correcting for variations in pressure, density or temperature of gases to be measured
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
- G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
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Abstract
The invention discloses a pressure equalizing chamber, a mounting method thereof and a three-dimension space multi-point pressure measuring and cross section type gas flow measuring device containing the pressure equalizing chamber. The pressure equalizing chamber is of an isosceles triangle thin wall cavity structure, two waist edges of an isosceles triangle are each continuously provided with one or more pressure measuring openings, and all the pressure measuring openings are communicated with a thin wall cavity. By the adoption of the three-dimension space multi-point pressure measuring and cross section type gas flow measuring device, multiple pressure measuring points are arranged at different streamline positions in a three-dimension space, and due to the fact that the pressure measuring cross section exceeds the pressure measuring cross section designed by any existing measuring technology, the pressure equalizing chamber, the mounting method thereof and the three-dimension space multi-point pressure measuring and cross section type gas flow measuring device are particularly applicable to the occasion that the flow speed of a large pipe is unevenly distributed; besides, due to the special thin wall cavity structure of the pressure equalizing chamber, ash accumulation does not occur easily, ash removing needle design is further adopted, and the ash accumulation tendency is reduced to the maximum degree; the gas flow measuring device has the remarkable advantages of being resistant to blocking, resistant to wearing, resistant to high temperature, high in measuring accuracy, stable in measurement value and the like.
Description
Technical field
The present invention relates to a kind of equal pressure chamber, its installation method and comprise its cross section formula gas flow surveying instrument of three dimensions multiple spot pressure, belong to gas flow measurement technical field.
Background technology
In modern enterprise is produced, per hour all need of boiler sends into a large amount of wind, the flue gas that output is a large amount of simultaneously.Along with China's economic system reform deeply, the segmentation of business accounting unit, carry out cost accounting and management, fully reduce energy consumption and become development trend, and the measurement of large pipeline dusty gas flow, its meaning seems more and more great, also more and more pay close attention to by people and pay attention to.
Industrial processes, in the measurement of temperature, pressure, flow, the large thermal parameter of liquid level four, flow measurement will reach the accuracy and reliability of expection, ICS Engineer generally believes that difficulty is maximum, especially large pipeline air quantity, flue gas flow are measured, more aobvious thorny, trace it to its cause: measured fluid generally has the features such as temperature is high, dustiness is large, corrosivity is strong first; Second carry that the pipeline section of fluid is long-pending large, straight length is short, elbow is many, and fluctuations in discharge scope is large, static pressure is little, flow velocity is low.Therefore, Measurement accuracy large pipeline air quantity, flue gas flow, should appropriate design, select flow instrument, again correctly install, use traffic instrument, only have omnibearing management and control guarantee measured value accurately and reliably.
For fuel-burning power plant, further illustrate the present situation of current large pipeline air quantity, flue gas flow measurement.
Station boiler primary and secondary air Boiler pressure control direct relation the serial important indicators such as Boiler Stable Combustion, economical operation, slagging prevention, reduction pollutant emission, is the working contents of thermal power plant's safety, economy, environmental protection operation.First air, Secondary Air are through rotary regenerative air preheater preheating, not only absorb amount of heat in flue gas, and carry a large amount of soot particle by heat exchange element, there is the feature of high temperature, dust-laden, bring sizable challenge to the work of apparatus for measuring air quantity long time stability.In addition, the exhaust smoke level of station boiler is measured also particularly important, in SCR technique, must calculate ammonia spraying amount according to real-time flue gas flow; At chimney entrance, need for environment monitoring, also necessary Measurement accuracy amount of flue gas emission; The accuracy that flue gas flow is measured and is also directly connected to heat Balance Calculation, burning efficiency is evaluated.Flue gas, compared with First air, Secondary Air, not only has higher temperature and the dust-laden of Geng Gao, and also has high humidity, feature that corrosivity is strong at boiler back end ductwork, and therefore the measurement difficulty of exhaust gas volumn can be larger.
The feature of station boiler First air, Secondary Air and flue gas determines after apparatus for measuring air quantity uses for a long time and is easy to wearing and tearing and blocking, wherein particularly thorny with blockage problem again.Conventional differential pressure type flow meter total head mouth and static port insert in air-flow, and the dust carried in air-flow is owing to clashing into measurement mechanism, with the effect of air current flow and frictional static, be easily bonded in pressure tappings and connecting pipe thereof.When gas temperature is lower than acid dew point and water dew point, the viscosity of dust enlarges markedly, and causes dust agglomerations in measurement mechanism, more exacerbates the blockage problem of measurement mechanism.This blocking occurs in the inside of apparatus for measuring air quantity, can only solve, bring very large maintenance workload to thermal technology's specialty by the way that pressurized air timing purges.
Fuel-burning power plant air and flue system pipeline section is long-pending large, the components such as baffle plate adjustment doors, support bar are arranged in pipeline, limit by arrangement space, general straight length is shorter and elbow is more, cause pipeline flow field comparatively disorderly, flow section velocity distribution, Temperature Distribution are seriously uneven, and the average dynamic pressure value that single-point or a few point record can not represent the total blast volume of whole flow section or the change of total exhaust gas volumn.
In addition, existing air quantity or flue gas flow measurement mechanism crushing also larger, be applied to fuel-burning power plant very uneconomical, as Venturi tube, the pressure difference signal of airfoil type flowmeter employing to the mode augmented flow measurement mechanism of pipeline throttling, but add air current flow resistance simultaneously, and then cause station service power consumption rate to increase.
Summary of the invention
The invention provides a kind of equal pressure chamber, its installation method and comprise its cross section formula gas flow surveying instrument of three dimensions multiple spot pressure, to improve the stability and accuracy that in industrial processes, air quantity and flue gas flow are measured.
For solving the problems of the technologies described above, the technical solution adopted in the present invention is as follows:
A kind of all pressure chambers, be isosceles triangle thin wall cavity structure, equal pressure chamber is provided with 6 ~ 60 pressure tappings, and pressure tappings is symmetrically distributed on two waist limits of isosceles triangle, and all pressure tappings are all communicated with thin wall cavity; The drift angle of isosceles triangle is 90 ~ 150 °, and corresponding two base angles are 15 ~ 45 °.
Above-mentioned equal pressure chamber is suitable for the measurement of various pipeline flow, comprises the measurement of large pipeline air quantity, flue gas flow, and when utilizing above-mentioned equal pressure chamber pressure, air-flow is met at the position, summit of isosceles triangle.
Above-mentioned equal pressure chamber can provide stable average total head and average static pressure, measures the average discharge of the flow section corresponding to isosceles triangle base, represents the total flow of whole flow section.It should be noted that, above-mentioned pressure cross section is approximately equal to the flow section that triangle base covers, and namely all pressure chamber fluoran stream surface nearly all provides flow measurement signal, compared with traditional apparatus for measuring air quantity, pressure area is much bigger, therefore can provide more stable and flow signal accurately.
In order to ensure to form stable total head and static pressure, preferably, do not retain the drift angle sharp parts of isosceles triangle, the base of isosceles triangle is provided with extension section, dividing plate is provided with between extension section and the bottom of isosceles triangle, the end of extension section is uncovered structure, and the end of extension section refers to the one end away from isoceles triangle drift angle.
Extension section and isosceles triangle section separate by aforementioned barriers completely.
Namely the above-mentioned drift angle sharp parts not retaining isosceles triangle also can be the shapes such as isosceles trapezoid.Extension section extends gained by isosceles triangle base, there is extension section when the drift angle sharp parts not retaining isosceles triangle, then all pressure chamber is the thin wall cavity structure of isosceles trapezoid and rectangle laminated structure, and extension section and isosceles triangle section is separated completely by dividing plate.
It should be noted that, the above-mentioned actual static pressure of static pressure ratio fluid measured in equal pressure chamber extension section is lower, mainly because the flowing of peripheral fluid forms swabbing action, cause extension section and formed " region of no pressure " relatively, peripheral fluid flow velocity is higher, " vacuum tightness " larger.Differential pressure signal after the dynamic pressure that the differential pressure that above-mentioned swabbing action is formed and flowing stagnation are formed superposes, meets Bernoulli equation principle, truly can reflect the size of actual flow.Just because of this, utilize the flow measurement device of the present invention's equal pressure chamber pressure to survey dynamic pressure signal larger than theoretical dynamic pressure signal, have pressure difference signal amplification, this will be conducive to the measurement accurately and reliably of air quantity.
In order to improve the accuracy of measurement, pressure tappings is symmetrically distributed on two waist limits of isosceles triangle.
Above-mentioned equal pressure chamber preferably adopts stainless sheet steel to make, and for the ease of preparation, ensures the accuracy of pressure simultaneously, preferably, equal pressure chamber, what comprise two blocks of isosceles triangle side plates and more than one piece meets stream dividing plate, and two blocks of isosceles triangle side plates are parallel and be oppositely arranged; The stream dividing plate of meeting of more than one piece to be located between two blocks of isosceles triangle side plates and to be connected as a single entity by two blocks of isosceles triangle side plates, and two waist limits of isosceles triangle are divided into more than two parts, every a formation one pressure tappings by the stream dividing plate of meeting of more than a piece.
In order to improve the stability of measurement, meeting stream dividing plate and being connected with isosceles triangle side plate is vertical, meet and flow septum plane and meet air-flow and parallel with the base of isosceles triangle side plate, pressure tappings cross section is rectangle.
In order to ensure the accuracy measured further, preferably, the spacing of two blocks of isosceles triangle side plates is 30 ~ 80mm.And with meet the limit approximately equal flowing dividing plate.
In order to reduce in equal pressure chamber further and pressure tappings dust stratification may, suspention has the deashing pin of more than in equal pressure chamber, and pressure tappings is stretched out at deashing pin two ends.
Above-mentioned deashing pin can utilize the kinetic energy measuring fluid to realize automatic ash removing.
Because pressure tappings is arranged continuously, preferably, arrange a deashing pin every one group of pressure tappings, one group of pressure tappings refers to two pressure tappings that isosceles triangle two waist limit is symmetrical, and two symmetrical pressure tappings are stretched out at deashing pin two ends.
Can ensure that deashing pin can beat every block and meet stream dividing plate like this, and then ensure that pressure tappings does not block, beat caused vibration and obvious deashing effect is all played to whole equal pressure chamber.
In order to reduce the wearing and tearing of all pressure chambers under high temperature, dust atmosphere, at outside surface and the fluoran stream surface spraying wear-resistant materials of equal pressure chamber.
Because above-mentioned stream dividing plate of meeting directly is subject to airflow scouring, be the parts that the present invention the most easily occurs to wear and tear, as the another kind of preferred version reduced wear, meet stream dividing plate and adopt high-abrasive material to make, as high temperature alloy or potsherd.
The installation method of above-mentioned equal pressure chamber, one or more equal pressure chamber is arranged in pipeline, when arranging two or more, the average total head pressure regional peace equal static pressure pressure region of each equal pressure chamber is communicated with communicating pipe respectively, and picks out at least one overall average total head pressure guiding pipe and an overall average static pressure pressure guiding pipe respectively.
Total head is that (average total head pressure region) measures in isosceles triangle thin wall cavity, and static pressure measures at isosceles triangle thin wall cavity outer (average static pressure pressure region), particular location thin wall cavity back (being also the part outside isosceles triangle bottom weakened wall cavity), when being provided with extension section, average static pressure pressure region is preferably in extension section middle part.
In order to prevent dust stratification, any section of communicating pipe and the angle of surface level are all less than 30 °.
In order to ensure all pressures effect of multiple equal pressure chamber, being provided with throttling in communicating pipe and all calming the anger and chew.
Above-mentioned throttling is all calmed the anger the Main Function chewed: prevent owing to there is obvious pressure reduction between each equal pressure chamber and cause gas flow rate in communicating pipe higher, and then causes the unstable or distortion of the differential pressure between above-mentioned overall average total head and overall average static pressure.Above-mentioned throttling is all calmed the anger to chew and actual is played throttle orifice effect, single throttle hole area (referring to the minimum cross-section of air nozzle in Figure 13) is less than 30% of cross-sectional area in communicating pipe, the principle of installation site and project organization avoids dust stratification in communicating pipe, and specific constructive form is not construed as limiting.
Above-mentioned equal pressure chamber is installed in circular pipe or rectangular duct; When being installed in circular pipe, preferably equal pressure chamber vertically to be inserted in pipeline and is passed through home position; When being installed on rectangular duct, the equal pressure chamber of preferred two or more is vertically inserted in pipeline, and interval is even.Also namely when be installed in circular pipe be mixing time, equal pressure chamber is preferably one, and when being installed on rectangular duct, equal pressure chamber is preferably two or more.
In order to stability and the accuracy of guaranteed flow measured value, the length of equal pressure chamber should close to circular pipe internal diameter or rectangular duct direction of insertion to edge lengths.
When being installed in the gaseous environment containing dust, for preventing bottom dust stratification, preferably, the length of equal pressure chamber is less than circular pipe internal diameter 50 ~ 200mm or is less than the 50 ~ 200mm of rectangular duct direction of insertion to edge lengths, and equal pressure chamber length refers to the length on isosceles triangle base.
During installation, easy dust stratification area in fluid bottom equal pressure chamber should be made unobstructed.Rectangular duct direction of insertion refers to the spacing between the two side of the rectangular duct that the two ends of equal pressure chamber length direction are right to edge lengths.
The difference of above-mentioned average total head and average static pressure is average dynamic pressure, from know-why, above-mentioned equal pressure chamber get differential pressure signal and can represent the size that it meets flow section flow completely, even if velocity flow profile is seriously uneven along its length, affect also not too large.Therefore, for obtaining total cross-section flow accurately, the direction that preferably all pressure chamber length direction is larger with change in flow gradient is consistent.According to above-mentioned optimum principle, when upstream is provided with baffle plate adjustment doors, preferably make equal pressure chamber length direction and flapper axes normal; When upstream is provided with 90 ° of elbows, preferably make equal pressure chamber length direction and elbow upstream line level.When above-mentioned optimum principle conflicts mutually with aforementioned optimum principle, should by aforementioned optimum principle determination installation method, and other measure be taked to ensure measuring accuracy, as increased fair water fin.
Comprise the cross section formula gas flow surveying instrument of the three dimensions multiple spot pressure of above-mentioned equal pressure chamber, comprise dynamic pressure measurement unit, static pressure measurement unit, temperature measurement unit and flow rate calculation display module;
Dynamic pressure measurement unit comprises equal pressure chamber, total head pressure pipe, static pressure pressure pipe and pressure difference transmitter, total head pressure pipe extends mid point position, equal pressure chamber isosceles triangle base and is communicated with the thin wall cavity of equal pressure chamber, measure average total head, static pressure pressure pipe extends middle part, equal pressure chamber isosceles triangle base and is communicated with thin wall cavity back, measures average static pressure; Total head pressure pipe is all connected with pressure difference transmitter with static pressure pressure pipe;
Pressure difference transmitter, static pressure measurement unit are connected with flow rate calculation display module respectively with temperature measurement unit.
The difference of above-mentioned average total head and average static pressure is average dynamic pressure, electric signal is converted to through pressure difference transmitter, transfer to flow rate calculation display module, the static motorized signal provided in conjunction with static pressure measurement unit and temperature measurement unit and temperature signal, gas flow that real-time calculating is surveyed, concrete calculating is with reference to prior art.
When the cross section formula gas flow surveying instrument of three dimensions multiple spot of the present invention pressure uses, be inserted in corresponding pipeline, insert the parts mainly equal pressure chamber producing resistance in pipeline, its fluoran stream surface almost provides flow measurement signal completely, and conventional flow measuring device (as multipoint mode apparatus for measuring air quantity, wing wind measuring device etc.) all cannot realize this point and gap is obvious, therefore the present invention obtains flow measurement signal the most reliably with minimum cost, and power savings advantages is particularly evident.
When flow measurement device of the present invention is in non-dusting gaseous environment, installation site is unrestricted; But be in the gaseous environment containing dust, in order to avoid dust stratification, installation site should be selected in horizontal pipe or be not more than on the tilted tube of 60 ° with the angle of surface level.When be in the gaseous environment containing dust but do not meet above-mentioned condition time, as measurement mechanism of the present invention is installed in vertical pipeline, extra technical measures must being taked to ensure not dust stratification, joining pressurized air timing purging system etc. as increased.
Preferably, static pressure pressure pipe extends equal pressure chamber isosceles triangle base extension section middle part and is communicated with thin wall cavity back.
The structure of above-mentioned equal pressure chamber and arrangement are core contents of the present invention, and other forms the requisite ingredient of measurement mechanism all with reference to prior art.
The NM technology of the present invention is all with reference to prior art.
Adopt the cross section formula gas flow surveying instrument of three dimensions multiple spot of the present invention pressure, multiple pressure point is arranged at three dimensions various flows line position, due to the pressure cross section that pressure cross section can be designed considerably beyond existing any one measuring technique, be therefore especially applicable to the occasion of large pipeline gas flow rate skewness; In addition, due to the thin wall cavity structure that equal pressure chamber is special, not easily dust stratification, and adopt the design of deashing pin further, reduce fouling potential to greatest extent; The significant advantage such as gas flow surveying instrument of the present invention has anti-blocking, abrasionproof, high temperature resistant, measuring accuracy is high, measured value is stable.
Accompanying drawing explanation
Fig. 1 is the ultimate principle of air flow rate measurement mechanism of the present invention.
Fig. 2 is the cut-open view of the equal pressure chamber of gas flow surveying instrument of the present invention.
Fig. 3 is the view of the equal pressure chamber of gas flow surveying instrument of the present invention along airflow direction.
Fig. 4 is the arrangement schematic diagram of equal pressure chamber in cold primary air piping in embodiment 1.
Fig. 5 is A-A schematic cross-section in Fig. 4 (being rotated counterclockwise 90 °).
Fig. 6 is the arrangement schematic diagram of equal pressure chamber in heat primary air pipe in embodiment 2.
Fig. 7 is B-B schematic cross-section in Fig. 6.
Fig. 8 is the arrangement schematic diagram of equal pressure chamber in hot secondary air channel in embodiment 3.
Fig. 9 is C-C schematic cross-section in Fig. 8.
Figure 10 is the arrangement schematic diagram of equal pressure chamber respectively in SCR reactor inlet and outlet conduit in embodiment 4.
Figure 11 is the structural representation after the equal pressure chamber be arranged in embodiment 4 in SCR reactor inlet vertical pipe is optimized.
Figure 12 is D-D schematic cross-section in Figure 10.
Figure 13 is that the throttling be installed in embodiment 4 in pressure pipe is all calmed the anger the front view chewed.
Figure 14 is the vertical view of Figure 13;
Figure 15 is the arrangement schematic diagram of equal pressure chamber in chimney inlet duct in embodiment 5.
Figure 16 is E-E schematic cross-section in Figure 15.
In figure, 1 is isosceles triangle side plate, 2 for meeting stream dividing plate, 3 is deashing pin, 10 is equal pressure chamber, 11 is extension section, 12 is average total head pressure region, 13 is average static pressure pressure region, 14 is pressure guiding pipe, 15 is total head pressure pipe, 16 is static pressure pressure pipe, 17 chew for throttling is all calmed the anger, 21 is cold First air pitch, 22 is heat primary air pitch, 23 is that hot Secondary Air 90 ° is curved logical, 24 is SCR reactor, 25 is baffle assembly, 26 is chimney, 31 is that cold First air flows to, 32 is the heat primary air flow direction, 33 is that hot Secondary Air flows to, 34 is denitration import flue gas flow direction, 35 is the denitration exiting flue gas flow direction, 36 is the neat stress flow direction.
Embodiment
In order to understand the present invention better, illustrate content of the present invention further below in conjunction with embodiment, but content of the present invention is not only confined to the following examples.
Embodiment 1
300MW coal unit adopts unit pulverized-coal system, and join 6 medium-speed pulverizers, the mode that every platform coal pulverizer inlet adopts hot and cold First air to mix regulates disintegrating outlet temperature.Above-mentioned cold First air pipeline vertically accesses heat primary air pipeline from top to bottom, and the straight length that quarter bend leads between cold First air pitch installs cross section of the present invention formula gas flow surveying instrument.Complete measurement mechanism comprises dynamic pressure measurement unit, static pressure measurement unit, temperature measurement unit and flow rate calculation display module, as shown in Figure 1.Dynamic pressure measurement unit is made up of equal pressure chamber, total head pressure pipe, static pressure pressure pipe and pressure difference transmitter, described equal pressure chamber is isosceles triangle thin wall cavity structure, air-flow is met at the position, summit of isosceles triangle, multiple pressure tappings is arranged on two waist limits continuously, and be all communicated with thin wall cavity, total head pressure pipe extends mid point position, isosceles triangle base by pressure tappings and is communicated with thin wall cavity, measure average total head, static pressure pressure pipe extends isosceles triangle base extension section middle part by pressure tappings and is communicated with thin wall cavity back, measure average static pressure, as shown in Figure 2,3.The difference of above-mentioned average total head and average static pressure is average dynamic pressure, 4-20mA electric signal is converted to through pressure difference transmitter, transfer to flow rate calculation display module in DCS system, the static motorized signal provided in conjunction with static pressure measurement unit and temperature measurement unit and temperature signal, calculate in real time survey cold primary air flow.
304 corrosion resistant plates that above-mentioned equal pressure chamber adopts 2mm thick make, and in isosceles triangle shape, drift angle is 120 °, and two base angles are 30 °, and two pieces of isosceles triangle side sheet room distances are 30mm; Do not retain the drift angle sharp parts of equal pressure chamber isosceles triangle, the base of isosceles triangle is provided with extension section, and be provided with between two blocks of isosceles triangle side plates and meet stream dividing plate and form pressure tappings on two waists, pressure tappings longitudinal section is rectangle.Above-mentioned cold First air pipeline section is circular, internal diameter 500mm.
Due in cold First air substantially without dust, therefore without the need to considering dust stratification problem.Above-mentioned equal pressure chamber length and cold First air internal diameter of the pipeline are substantially suitable, and also by home position in vertical insertion pipeline, diametrically arrange 8 pressure tappings continuously, pressure tappings is symmetrically distributed on the both sides of isosceles triangle between two.
Lead to because equal pressure chamber upstream exists a quarter bend, the maximum direction of change in flow gradient should be substantially parallel with curved logical upstream line, therefore, for obtaining representative flow signal, ensures that equal pressure chamber length direction is parallel with curved logical upstream line.
For improving the measuring accuracy of cross section of the present invention formula apparatus for measuring air quantity, not only must carry out flow calibration in laboratory standard wind-tunnel, but also should revise Wind Coverage Calculation model in conjunction with the result of on-the-spot flow calibration.
Embodiment 2
300MW coal unit adopts unit pulverized-coal system, and join 6 medium-speed pulverizers, the mode that every platform coal pulverizer inlet adopts hot and cold First air to mix regulates disintegrating outlet temperature.Above-mentioned heat primary air pipe is horizontally disposed, due to site space restriction, only can install cross section of the present invention formula apparatus for measuring air quantity in heat primary air pitch downstream, as shown in Figure 6.
In the present embodiment, the structure of equal pressure chamber is similar to Example 1, difference size and mounting means.The cross section of heat primary air pipeline is rectangle, and width is 900mm, is highly 1200mm.Above-mentioned equal pressure chamber length is about 1000mm, vertically inserts heat primary air pipeline along short transverse, and single equal pressure chamber totally 16 pressure tappings from top to bottom, are symmetrically distributed on the both sides of isosceles triangle between two; Arrange 3 equal pressure chambers along heat primary air duct width direction, spacing is 300mm.48 pressure tappings are arranged in above-mentioned measurement cross section altogether, the stability of common guarantee measuring-signal and accuracy, as shown in Figure 7.
Because heat primary air carries a small amount of dust from rotary regenerative air preheater, therefore need to consider that dust is on the impact of measurement mechanism.During installation, bottom equal pressure chamber and between bottom surface, heat primary air road the space of reserved about 100mm, ensures that air channel lower flow is unobstructed, cross section of the present invention formula apparatus for measuring air quantity can be avoided to block.
Due to the impact of heat primary air pitch, on heat primary air road flow section, velocity flow profile is comparatively even in the width direction, and seriously uneven along short transverse velocity flow profile.But cross section of the present invention formula apparatus for measuring air quantity almost gets average dynamic pressure completely in the short transverse of air channel, and therefore measuring-signal truly can reflect the size of actual air volume.At air channel Width, arrange 3 equal pressure chambers, and the average total head pressure region of each equal pressure chamber and each average static pressure pressure region are communicated to a bit respectively, measure overall average total head and overall average static pressure.Because Width velocity flow profile is comparatively even, arrange that 3 equal pressure chambers can ensure the precision measured.
Embodiment 3
The hot secondary air duct sectional dimension of 600MW coal unit reaches 4500 × 4800mm, and because sectional dimension is comparatively large, straight length is shorter, flow velocity is lower and distribution is serious uneven, and conventional air measuring technology is difficult to meet unit cooperative control overflow.Adopt cross section of the present invention formula apparatus for measuring air quantity, in hot secondary air duct, arrange 4 × 2 equal pressure chambers, as shown in Figure 8,9.Arrange multiple along the vertical direction of insertion of equal pressure chamber, can reduce the size of single equal pressure chamber, and then reduce manufacturing cost, convenient transport, is also convenient to in-site installation.The structure of above-mentioned single equal pressure chamber is similar to Example 2, repeats no more.
It should be added that, in the present embodiment, total head pressure pipe and the part of static pressure pressure pipe in air channel are all in " X " shape, and this structure can ensure all pressures effect between each equal pressure chamber.
Embodiment 4
After certain 600MW coal unit denitration transformation, spray ammonia automatic control system need calculate ammonia spraying amount according to flue gas flow, therefore must install flue gas flow measurement mechanism.Because site space is comparatively compact, alternative installation site is two places only: the vertical ascent stage of ammonia-spraying grid to SCR reactor inlet and the tilting section (with horizontal plane angle about 30 °) of SCR reactor outlet, as shown in Figure 10.
In ammonia-spraying grid to vertical ascent stage of SCR reactor inlet, cross section of the present invention formula flue gas flow measurement mechanism is installed if select, optimal design must be adopted to ensure in pressure pipe not dust stratification.Concrete measure is: different from embodiment 1-3, and the equal pressure chamber in this place does not arrange extension section, to avoid extension section place dust stratification, and makes total head pressure pipe and horizontal plane angle be updip about 45 °, static pressure pressure pipe directly in the back pressure of total head pressure pipe, as shown in figure 11.
If select the tilting section of SCR reactor outlet to install cross section of the present invention formula flue gas flow measurement mechanism, structure and the embodiment 1-3 of equal pressure chamber are similar.SCR outlet is of a size of 3000 × 12000mm, Width is far longer than short transverse, therefore nearly 12 equal pressure chambers are arranged, each average total head pressure regional peace equal static pressure pressure region is communicated with communicating pipe respectively, and pick out an overall average total head pressure guiding pipe and an overall average static pressure pressure guiding pipe respectively, as shown in figure 12.In order to ensure all pressures effect of each equal pressure chamber, all calming the anger and chew installing communicating pipe and each pressure regional connectivity place throttling additional, as shown in figure 12, the throttling longitudinal section of chewing of all calming the anger is bow-tie shape, and xsect is circular, and concrete structure is see Figure 13,14.
In addition, because SCR is arranged in high dirt section, in order to avoid measurement mechanism blocking, all installed many deashing pins additional in each equal pressure chamber inside, two symmetrical pressure tappings are stretched out at deashing pin two ends.
Embodiment 5
Certain 1000MW coal unit, by the requirement of local Environmental Protection Agency, installs flue gas flow measurement mechanism at chimney entrance, and access desulfurization CEMS, as the foundation calculating power plant's charges for disposing pollutants.The cross-sectional dimension of chimney gas approach is comparatively large, and almost without straight length, the neat stress humidity after desulfurization again comparatively greatly, corrosivity is stronger.Consider above-mentioned factor, the 316L corrosion resistant plate of 4mm is adopted when equal pressure chamber makes, to slow down relative corrosion rate, and the spacing of two pieces of triangular side panels is enlarged to 80mm, improve the size of pressure tappings and internal cavities, make it not easily block, separately assemble from deashing pin, ensure flue gas flow measurement mechanism of the present invention steady operation reliably and with long-term, as shown in figure 16.
In addition, for the measurement occasion that straight length is shorter, perfect fair water fin design is necessary, also embodies to some extent in Figure 15.
Claims (12)
1. an equal pressure chamber, is characterized in that: be isosceles triangle thin wall cavity structure, equal pressure chamber is provided with 6 ~ 60 pressure tappings, and pressure tappings is symmetrically distributed on two waist limits of isosceles triangle, and all pressure tappings are all communicated with thin wall cavity; The drift angle of isosceles triangle is 90 ~ 150 °, and corresponding two base angles are 15 ~ 45 °.
2. all pressure chambers as claimed in claim 1, is characterized in that: what comprise two blocks of isosceles triangle side plates and more than one piece meets stream dividing plate, and two blocks of isosceles triangle side plates are parallel and be oppositely arranged; The stream dividing plate of meeting of more than one piece to be located between two blocks of isosceles triangle side plates and to be connected as a single entity by two blocks of isosceles triangle side plates, and two waist limits of isosceles triangle are divided into more than two parts, every a formation one pressure tappings by the stream dividing plate of meeting of more than a piece.
3. all pressure chambers as claimed in claim 2, is characterized in that: meet stream dividing plate and be connected with isosceles triangle side plate is vertical, meet to flow septum plane and meet air-flow and parallel with the base of isosceles triangle side plate, and pressure tappings longitudinal section is rectangle; The spacing of two blocks of isosceles triangle side plates is 30 ~ 80mm.
4. the equal pressure chamber as described in claim 1-3 any one, is characterized in that: all in pressure chamber, suspention has the deashing pin of more than, and pressure tappings is stretched out at deashing pin two ends.
5. all pressure chambers as claimed in claim 4, it is characterized in that: arrange a deashing pin every one group of pressure tappings, one group of pressure tappings refers to two pressure tappings that isosceles triangle two waist limit is symmetrical, and two symmetrical pressure tappings are stretched out at deashing pin two ends.
6. the equal pressure chamber as described in claim 1-3 any one, it is characterized in that: the drift angle sharp parts not retaining isosceles triangle, the base of isosceles triangle is provided with extension section, dividing plate is provided with between extension section and the bottom of isosceles triangle, the end of extension section is uncovered structure, and the end of extension section refers to the one end away from isoceles triangle drift angle.
7. the installation method of the equal pressure chamber described in claim 1-6 any one, it is characterized in that: the equal pressure chamber of arranging one or more in pipeline, when arranging two or more, the average total head pressure regional peace equal static pressure pressure region of each equal pressure chamber is communicated with communicating pipe respectively, and picks out at least one overall average total head pressure guiding pipe and an overall average static pressure pressure guiding pipe respectively.
8. installation method as claimed in claim 7, is characterized in that: any section of communicating pipe and the angle of surface level are all less than 30 °.
9. as claimed in claim 7 or 8 installation method, is characterized in that: be provided with throttling in communicating pipe and all calm the anger and chew.
10. installation method as claimed in claim 7 or 8, is characterized in that: all pressure chamber is installed in circular pipe or rectangular duct; When being installed in circular pipe, equal pressure chamber vertically to be inserted in pipeline and is passed through home position; When being installed on rectangular duct, the equal pressure chamber of two or more is vertically inserted in pipeline, and interval is even.
11. installation methods as claimed in claim 7 or 8, is characterized in that: all the length of pressure chamber is less than circular pipe internal diameter 50 ~ 200mm or is less than the 50 ~ 200mm of rectangular duct direction of insertion to edge lengths, and equal pressure chamber length refers to the length on isosceles triangle base.
The 12. cross section formula gas flow surveying instruments comprising the three dimensions multiple spot pressure of the equal pressure chamber described in claim 1-6 any one, is characterized in that: comprise dynamic pressure measurement unit, static pressure measurement unit, temperature measurement unit and flow rate calculation display module;
Dynamic pressure measurement unit comprises equal pressure chamber, total head pressure pipe, static pressure pressure pipe and pressure difference transmitter, total head pressure pipe extends mid point position, equal pressure chamber isosceles triangle base by pressure tappings and is communicated with the thin wall cavity of equal pressure chamber, measure average total head, static pressure pressure pipe extends middle part, equal pressure chamber isosceles triangle base and is communicated with thin wall cavity back, measures average static pressure; Total head pressure pipe is all connected with pressure difference transmitter with static pressure pressure pipe;
Pressure difference transmitter, static pressure measurement unit are connected with flow rate calculation display module respectively with temperature measurement unit.
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| CN105444833B (en) | 2018-10-19 |
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