CN101251405B - Apparatus for calibrating gas instrument - Google Patents
Apparatus for calibrating gas instrument Download PDFInfo
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- CN101251405B CN101251405B CN2008100604025A CN200810060402A CN101251405B CN 101251405 B CN101251405 B CN 101251405B CN 2008100604025 A CN2008100604025 A CN 2008100604025A CN 200810060402 A CN200810060402 A CN 200810060402A CN 101251405 B CN101251405 B CN 101251405B
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Abstract
The invention discloses a gas instrument calibration device, which comprises a calibration platform for assembling a flowmeter to be tested. The calibration platform is at least connected with a stagnation container, a sonic nozzle, a negative pressure pipe and a Roots vacuum pump adopting the variable frequency control in turn. The calibration platform and the gas inlet of the calibration platform are arranged in a lockable calibration chamber, and the gas outlet of the vacuum pump is communicated with the calibration chamber through an underground duct. The gas instrument calibration device which has the advantages of low noise pollution, low energy consumption and small error is particularly suitable for the calibration of a gas flow measuring instrument.
Description
Technical field
The present invention relates to the calibrating or the correction of flow instrument equipment, be specifically related to the equipment that the gas flow measuring instrument is examined and determine.
Background technology
The method of Flow Standard Device With Standard Meter Method is a lot, and the gas flow standard device of making standard scale with velocity of sound Venturi nozzle (or claiming sonic nozzle) is wherein a kind of.With compare as standard scale with other flowmeter, have lot of advantages with sonic nozzle as standard scale, as simple in structure, stable performance, accuracy height, no movable member, easy to maintenance, calibration interval long (5 years) or the like.Sonic nozzle method gas flow standard device is applicable to detection and the calibration to all gases flowmeter, can detect the flowmeter of mass flowmeter, velocity flowmeter, volumeter, spinner-type flowmeter, differential pressure flowmeter or other kind.
The structure of tradition sonic nozzle method gas flow standard device as schematically shown in Figure 1, it comprise vacuum pump 1 ', gas-holder 2 ', collecting pipe (container) 3 ', switch valve 4 ', sonic nozzle 5 ', stagnation vessel temp meter 6 ', stagnation container pressure meter 7 ', stagnation container 8 ', flow control valve 9 ', tested table back thermometer 10 ', tested table (flowmeter) 11 ', the preceding pressure gauge 12 of tested table ' etc.Its verification process is: as shown in Figure 1, with the vacuum pump 1 ' upstream straight length inlet of air by tested table sucked, through straight length before the tested table, tested table 11 ' and tested table downstream straight length enter stagnation container 8 ', stagnation container 8 ' the downstream, have one group of sonic nozzle 5 ', the controlled valve 4 in control sonic nozzle ' downstream ', can select arbitrarily the sonic nozzle 5 of the switch of wanting ', to reach the purpose that changes tested surface low amount, stagnation container 8 ' by stagnation vessel temp meter 6 ', stagnation container pressure meter 7 ' thermometric, pressure measurement, the substitution formula calculate can obtain by sonic nozzle 5 ' mass rate, that is the mass rate by tested table place.By tested table back thermometer 10 ', the temperature and pressure at the pressure gauge 12 ' tested table of measurement place before the tested table, can calculate atmospheric density, and then obtain the standard volume flow.Flow control valve 9 ' generally only be used for switch also can be used as the supplementary means of regulating flow.Carrying out low discharge when calibrating, can open vacuum pump 1 ', as long as gas-holder 2 ' vacuum tightness can meet the demands.Vacuum pump 1 ' ability should satisfy following two conditions: the first, the flow that vacuum pump provided should be greater than the maximum flow of tested flowmeter; The second, in measuring process, the vacuum tightness that vacuum pump provided should satisfy the critical pressure ratio of sonic nozzle.Usually, when ratio＜0.85 of the pressure at sonic nozzle two ends, its flow velocity has just reached velocity of sound, and its flow velocity is constant when pressure ratio continues to descend, and promptly keeps velocity of sound constant.
For the bigger standard set-up of throughput ratio, need select water-ring vacuum pump for use, therefore also need cooling tower, centrifugal pump, underground tank, exhaust box.In order to adjust the inlet gas flow field and to reduce noise, also should the bellmouth entrance be installed in the porch, the front and back straight length of tested table is answered long enough.In addition, also should be equipped with power distribution cabinet, computing machine, meter-clamping apparatus, control system and data acquisition system (DAS).
The employed measurement gas of traditional apparatus for calibrating gas instrument is the atmosphere from outdoor suction, and the air that vacuum pump is discharged is also directly to outdoor discharging.No matter domestic vacuum pump that negative pressure selects for use at present still all uses two types vacuum pump abroad in order to produce: water-ring vacuum pump and gas ring type vacuum pump.These two kinds of vacuum pumps respectively have characteristics.
Its principle of water-ring vacuum pump is to utilize the to-and-fro movement of piston to come extracting air, the heat that is produced when the extracting air is cooled off with recirculated water, so be called liquid-ring type.This vacuum pump advantage is the vacuum tightness height that can reach, and the pressure reduction ratio can reach 0.2.Shortcoming is that energy resource consumption is big, when the rated flow gap of required flow and the vacuum pump of calibrating is big, and pipeline need bypass, otherwise vacuum pump can burn out.Owing to be to take exhaust with piston, the homogeneity of average discharge was relatively poor when it extracted on the other hand.
The gas ring type vacuum pump is exactly a centrifugal high pressure fan.It receives negative pressure chamber to the inlet scoop, and exhausr port is received outside atmosphere.The advantage of this vacuum pump is that specific energy consumption is lower mutually with water-ring vacuum pump, and the homogeneity of average discharge is better simultaneously.Shortcoming is the rated flow gap when required flow and the vacuum pump of calibrating when big, pipeline need bypass, otherwise vacuum pump can burn out equally.Its pressure reduction is than not enough on the other hand, and external product is the highest at present also can only reach to 0.7.When more bigger, just can't guarantee the requirement of pressure reduction ratio＜0.85 at the two ends of sonic nozzle, thereby limit the usable range of device by the pressure loss of calibrating instrument.
No matter use the vacuum pump of that type, what traditional apparatus for calibrating gas instrument had a maximum also is the defective of general character: owing to the gas to calibrating usefulness is to extract from outside atmosphere, and again to airborne release, this has just produced three problems: one is that the temperature of the air that extracted of calibrating is uncontrollable, be subjected to the influence of outdoor temperature bigger, although can revise, brought the additive error of corrected Calculation with software.Another is because air is to the outside atmosphere discharging, when discharging noise has also been led out, and has caused the noise pollution of environment.Another all can't adopt converter technique.As adopt converter technique, for the gas ring type vacuum pump, then the following general who has surrendered of rotating speed descends the suction ability of pump rapidly, can't satisfy the calibrating requirement, for water-ring vacuum pump, the homogeneity of its average discharge also worsens rapidly when rotating speed descends, and can bring uncertain factor to calibrating, thereby make the data of calibrating produce error, influenced the authority of calibrating data.
Summary of the invention
Technical matters to be solved by this invention is to provide a kind of noise pollution low apparatus for calibrating gas instrument at the deficiencies in the prior art.Further provide a kind of apparatus for calibrating gas instrument that reduces additive error due to the corrected Calculation that produces owing to temperature variation.Further provide the apparatus for calibrating gas instrument that a kind of energy consumption greatly reduces.
For solving the problems of the technologies described above, the present invention adopts following technical proposals:
Apparatus for calibrating gas instrument of the present invention, comprise the calibrating platform position that is used to lay flowmeter to be checked, calibrating platform position is connected with stagnation container, sonic nozzle, negative-pressure pipeline and vacuum pump at least in turn, it is characterized in that described calibrating platform position is arranged in the closed calibrating chamber, and the exhausr port of described vacuum pump communicates with this calibrating chamber by outlet conduit.
Described outlet conduit is a underground pipeline.
Indoor described calibrating platform position, stagnation container, sonic nozzle and the negative-pressure pipeline of being provided with of described calibrating.
Also be connected with gas-holder between described negative-pressure pipeline and the vacuum pump.
Described vacuum pump is a Roots vaccum pump, is preferably two to five Roots vaccum pumps that are arranged in parallel, three Roots vaccum pumps that are arranged in parallel more preferably, and to reach the effect of stack, equipment investment simultaneously can be controlled at reasonable range again.Further preferred version is that described Roots vaccum pump is connected with frequency converter, so that vacuum pump is carried out frequency conversion, cuts down the consumption of energy, and further preferred version is that described frequency converter is by computer control, to realize robotization control and management.
Described vacuum pump is located in the soundproof room, and the inlet end of described outlet conduit promptly is opened on this soundproof room, to reduce the total system noise pollution of environment to external world.
The present invention has following beneficial effect:
As seen by above-mentioned, apparatus for calibrating gas instrument of the present invention is to the vacuum pump selected for use and to the control method of pump, and the pump drainage mode of gas changes.
1, because calibrating gas is adopted closed-loop system.Make the noise in the work can not be transmitted to the external world, avoided the noise pollution in the environment.
2, the closed-loop system that forms air-flow by the underdrain is adopted in calibrating with air.The air of calibrating usefulness adopts inner loop mode, does not exchange with outside air.Guarantee that like this calibrating is not subjected to the interference of ambient temperature with air.Because this closed-loop system is to connect porting with underground channel, is subjected to the influence of underground ground temperature, carry out heat interchange with the wall of trench, the temperature change value of the air of examining and determine usefulness is descended greatly, the difference variation in a year has also reached Laboratory Request.Reduced the additive error of the corrected Calculation that produces owing to temperature variation.
3, vacuum pump is selected Roots vaccum pump for use.Roots vaccum pump is compared with above-mentioned two types vacuum pump, and its characteristics are: the pressure reduction ratio is higher than the gas ring type vacuum pump, but is lower than water-ring vacuum pump, and pressure reduction can reach 0.51 than generally, can satisfy the requirement of calibrating fully.Prevented to satisfy the defective that calibrating requires with the pressure difference that the compression ring vacuum pump is produced.
4, the design feature of Roots vaccum pump determined it the homogeneity of average discharge a little less than the gas ring type vacuum pump but far above water-ring vacuum pump, the relative coefficient of its suction and rotating speed goes to zero simultaneously, and the relative coefficient of flow and rotating speed is tending towards 1.The present invention adopts converter technique that the rotating speed of Roots vaccum pump is controlled, and makes the pressure reduction ratio become adjustable.Its flow also becomes adjustable like this, also need not bypass when big in calibrating and the difference in flow of vacuum pump rated flow.Thereby reduced energy consumption widely.Energy consumption is about 1/20th of same device.
5, computing machine is by the mode of Frequency Converter Control same model vacuum pump in parallel group, make the rate of air sucked in required of vacuum pump reach Overlay, and need not will have under the prerequisite of a vacuum pump that can reach the maximum calibrating of device flow as original mode, be equipped with one group of vacuum pump for energy efficient.
6, the needs of calibrating flow value are controlled the rotating speed and the platform number of vacuum pump by computing machine, thereby reach economy and improved handling.
Description of drawings
Fig. 1 is the structural representation of traditional apparatus for calibrating gas instrument;
Fig. 2 is the structural representation of apparatus for calibrating gas instrument of the present invention.
Embodiment
Embodiment describes in further detail the present invention below in conjunction with accompanying drawing.
As shown in Figure 2, apparatus for calibrating gas instrument of the present invention, comprise a closed calibrating chamber 1 and a closed soundproof room 2, in the soundproof room 2 and be provided with three Roots vaccum pumps 3, in the calibrating chamber 1 and be provided with two calibrating platform positions 4 that are used to lay flowmeter to be checked, calibrating platform position 4 is connected with flow control valve 5 in turn, stagnation container 6, one row's sonic nozzle 7, negative-pressure pipeline 8, be equipped with switch valve 9 on the two ends pipeline of sonic nozzle 7, and described flow control valve 5, stagnation container 6, sonic nozzle 7 and negative-pressure pipeline 8 all are arranged in the described calibrating chamber 1 with sonic nozzle 7 corresponding parts, the remainder of negative-pressure pipeline 8 then stretches out in outside the calibrating chamber 1, and be communicated with described Roots vaccum pump 3 by pipeline, the exhausr port of Roots vaccum pump 3 is positioned at described soundproof room 2, and soundproof room 2 then is connected by being located at underground outlet conduit 10 between the chamber 1 with calibrating.In addition, described Roots vaccum pump 3 also is connected with the frequency converter 12 by computing machine 11 controls, and simultaneously, this computing machine 11 also is the main frame of whole apparatus for calibrating gas instrument.
Claims (6)
1. apparatus for calibrating gas instrument, comprise the calibrating platform position that is used to lay flowmeter to be checked, calibrating platform position is connected with stagnation container, sonic nozzle, negative-pressure pipeline and vacuum pump at least in turn, described calibrating platform position is arranged in the closed calibrating chamber, and the exhausr port of described vacuum pump communicates with this calibrating chamber by outlet conduit, it is characterized in that described outlet conduit is a underground pipeline, described vacuum pump is two to five Roots vaccum pumps that are arranged in parallel, and described Roots vaccum pump is connected with frequency converter.
2. apparatus for calibrating gas instrument according to claim 1 is characterized in that indoor described calibrating platform position, stagnation container, sonic nozzle and the negative-pressure pipeline of being provided with of described calibrating.
3. apparatus for calibrating gas instrument according to claim 1 and 2 is characterized in that also being connected with between described negative-pressure pipeline and the vacuum pump gas-holder.
4. apparatus for calibrating gas instrument according to claim 1 and 2 is characterized in that described vacuum pump is three Roots vaccum pumps that are arranged in parallel.
5. apparatus for calibrating gas instrument according to claim 1 and 2 is characterized in that described vacuum pump is located in the soundproof room, and the inlet end of described outlet conduit promptly is opened on this soundproof room.
6. apparatus for calibrating gas instrument according to claim 1 and 2 is characterized in that described frequency converter is by computer control.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2008100604025A CN101251405B (en) | 2008-04-08 | 2008-04-08 | Apparatus for calibrating gas instrument |
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| CN2008100604025A CN101251405B (en) | 2008-04-08 | 2008-04-08 | Apparatus for calibrating gas instrument |
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| CN101251405A CN101251405A (en) | 2008-08-27 |
| CN101251405B true CN101251405B (en) | 2011-06-01 |
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Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101749222A (en) * | 2008-12-03 | 2010-06-23 | 北京迪通电子技术研究所 | Multifunctional motor control device |
| CN103837215B (en) * | 2014-03-25 | 2016-08-24 | 重庆市计量质量检测研究院 | Commutation valve type p.V.T.t method gas flow meter |
| CN104535142A (en) * | 2015-01-04 | 2015-04-22 | 镇江市计量检定测试中心 | Nozzle block type gas flowmeter calibrating device |
| CN104501917B (en) * | 2015-01-04 | 2018-09-18 | 镇江市计量检定测试中心 | Super large caliber sonic nozzle group formula gas flowmeter calibrating installation |
| CN105091989A (en) * | 2015-05-06 | 2015-11-25 | 姜跃炜 | An environment-controllable flow detection standard device |
| CN105444846B (en) * | 2015-12-16 | 2018-11-06 | 桂林航天工业学院 | A kind of experimental provision measuring venturi spillway discharge |
| CN107677342A (en) * | 2016-08-01 | 2018-02-09 | 中国石油化工股份有限公司 | Natural gas flowmeter verification system |
| CN108827407B (en) * | 2018-04-08 | 2021-06-15 | 广州能源检测研究院 | Adjusting device and adjusting method for back pressure ratio of automatic balancing system |
| CN110243444B (en) * | 2019-07-09 | 2024-05-10 | 海盐美捷测试仪器有限公司 | Negative pressure source device, gas meter verification gas circuit system and verification method |
| CN114001803B (en) * | 2021-09-09 | 2024-02-27 | 国家管网集团浙江省天然气管网有限公司 | Bypass type natural gas flow automatic verification control system and control method thereof |
Citations (2)
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| CN1188671C (en) * | 2003-04-11 | 2005-02-09 | 天津大学 | Gas flow standardizing devices |
| CN1948838A (en) * | 2006-11-10 | 2007-04-18 | 周彬 | Method of making indoor maintaining constant temperature by using earth |
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- 2008-04-08 CN CN2008100604025A patent/CN101251405B/en active Active
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1188671C (en) * | 2003-04-11 | 2005-02-09 | 天津大学 | Gas flow standardizing devices |
| CN1948838A (en) * | 2006-11-10 | 2007-04-18 | 周彬 | Method of making indoor maintaining constant temperature by using earth |
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| 华陈权,郑金吾,张朝晖.音速喷嘴气体流量标准装置流量的准确定位.计量技术.2002,(8),36. * |
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Effective date of registration: 20101231 Address after: 315400 No. 1, Rainbow Road, Northeast Industrial Park, Zhejiang, Yuyao Applicant after: Yuyao Yinhuan Flowmeter Co., Ltd. Address before: Rainbow Road 315400 Zhejiang city of Yuyao Province in Northeast Industrial Park, No. 1 Yuyao Yinhuan flowmeter Co. Ltd. Applicant before: Zhu Jiashun |
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