CN106352942A - Liquid level measurement device and liquid level measurement method based on double differential pressure transmitters - Google Patents
Liquid level measurement device and liquid level measurement method based on double differential pressure transmitters Download PDFInfo
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- CN106352942A CN106352942A CN201610852191.3A CN201610852191A CN106352942A CN 106352942 A CN106352942 A CN 106352942A CN 201610852191 A CN201610852191 A CN 201610852191A CN 106352942 A CN106352942 A CN 106352942A
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- liquid level
- valve
- differential pressure
- connecting pipe
- pressure transmitter
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/14—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measurement of pressure
Abstract
The invention relates to a liquid measurement device and liquid level measurement method based on double differential pressure transmitters. The liquid level measurement device comprises a first liquid level differential pressure transmitter and a second liquid level differential pressure transmitter, a negative pressure interface and a positive pressure interface of the first liquid level differential pressure transmitter communicate with a negative pressure pipe orifice and a positive pressure pipe orifice of to-be-measured equipment through a first pressure guide pipe and a second pressure guide pipe correspondingly respectively; the second pressure guide pipe is provided with a positive pressure lateral root valve and a positive pressure lateral condensing vessel; a negative pressure interface and a positive pressure interface of the second liquid level differential pressure transmitter communicate with the first pressure guide pipe and a negative pressure lateral condensing vessel through a third pressure guide pipe and a fourth pressure guide pipe correspondingly respectively; the downstream part of the fourth pressure guide pipe provided with a first separation tank isolating valve communicates with a seventh pressure guide pipe which is provided with a separation tank blowdown valve and sequentially connected with a second separation tank isolating valve and a separation tank; a downstream part of the positive pressure lateral condensing vessel communicates with a fifth pressure guide pipe; a downstream part of the third pressure guide pipe communicates with a sixth pressure guide pipe. With the adoption of the measurement device, the adverse effect of liquid phase density uncertainty of the first pressure guide pipe on liquid level measurement of a steam pocket can be eliminated.
Description
Technical field
The present invention relates to a kind of liquid level emasuring device based on double difference pressure transmitter and level measuring method.
Background technology
Currently, substantial amounts of boiler and useless pot are applied in power industry, petrochemical industry or coal chemical industry, using these pots
Stove or useless pot output steam are for the heat that steam turbine or recovery process system produce that generates electricity, drives.Boiler and useless pot
Liquid level of steam drum is a very important parameter, is to weigh the mark whether boiler circuit balances, the height of liquid level of steam drum is direct
The impact quality of steam and the safe operation of boiler and useless pot.For example, liquid level of steam drum is too high can affect steam-water separation effect, make
The steam zone liquid of output, not only reduces quality and the yield of steam, and can lead to the upstream devices such as steam turbine
Damage；If liquid level of steam drum is too low, gently then impact boiler or useless pot in vapour, water balance, heavy then lead to boiler and useless pot damage, very
Extremely can set off an explosion.Therefore, the control for liquid level of steam drum especially needed draws attention.
Although have developed multiple methods for controlling liquid level of steam drum, for example, Two-impulse control method and
Three blunt quantity control method.But, because existing measuring method is still difficult to the liquid level of accurately measure drum, cause drum
Liquid level remain puzzlement boiler and useless pot steadily, a difficult problem for safe operation.
Generally one or more sets "+one single-compartment balance container of a differential pressure transmitter " or " one are adopted in prior art
+ one double-chamber balancing vessel of platform differential pressure transmitter " is measuring the liquid level of steam drum in useless pot and boiler.However, due to being transported by drum
Row working conditions change, variation of ambient temperature and heat tracing impact, the comparing water column density of single-compartment balance container and double-chamber balancing vessel
It is respectively provided with larger uncertainty.For example, larger day and night temperature, cold season come into operation heat tracing or drum brownout operation etc. all
Comparing water column density will be led to change, and then affect accurate measurement and the control accuracy of liquid level of steam drum.
Content of the invention
Primary technical problem to be solved by this invention is to provide one kind to can guarantee that liquid level of steam drum for above-mentioned prior art
Certainty of measurement, it is to avoid level gauging is changed by operating condition, variation of ambient temperature and heat tracing are affected based on double difference pressure
The liquid level emasuring device of transmitter.
Further technical problem to be solved by this invention is to provide a kind of level gauging side based on double difference pressure transmitter
Method.
The technical scheme that the above-mentioned primary technical problem of present invention solution is adopted is: the liquid level based on double difference pressure transmitter is surveyed
Amount device is it is characterised in that include the first liquid level differential pressure transmitter and the second liquid level differential pressure transmitter, wherein:
The negative port of described first liquid level differential pressure transmitter passes through the negative pressure mouth of pipe that the first connecting pipe connects Devices to test,
The suction side root valve being close to the described negative pressure mouth of pipe and suction side condensing container are provided with the first connecting pipe；First liquid level differential pressure
The positive pressure interface of transmitter passes through the malleation mouth of pipe that the second connecting pipe connects Devices to test, and it is described that the second connecting pipe is provided with next-door neighbour
The positive pressure side root valve of the malleation mouth of pipe and positive pressure side condensing container；
The negative port of described second liquid level differential pressure transmitter passes through the 3rd connecting pipe and connects the first connecting pipe；Second liquid level
The positive pressure interface of differential pressure transmitter passes through the 4th connecting pipe and connects suction side condensing container, and it is described that the 4th connecting pipe is provided with next-door neighbour
First knockout drum isolating valve of suction side condensing container；
The communicating downstream of described positive pressure side condensing container has the 5th connecting pipe, and the 5th connecting pipe is provided with positive pressure side blowdown
Valve；
The communicating downstream of described 3rd connecting pipe has the 6th connecting pipe, is provided with suction side blowdown on the 6th connecting pipe
Valve；The communicating downstream of described 4th connecting pipe has the 7th connecting pipe, and the 7th connecting pipe is connected with turn the second knockout drum isolation
Valve and knockout drum, are provided with knockout drum blowoff valve on described 7th connecting pipe in knockout drum downstream.
With improvement, described suction side condensing container and positive pressure side condensing container are provided with three procedural interfaces and one
It is furnished with the floss hole of DRAIN PLUG.Wherein, a procedural interface connection suction side root valve of suction side condensing container, suction side
Another procedural interface of condensing container is respectively communicated with the first liquid level differential pressure transmitter and the second liquid level differential pressure transmitter, suction side
3rd procedural interface of condensing container connects the first knockout drum isolating valve；Accordingly, a process of positive pressure side condensing container
Orifice positive pressure side root valve, another procedural interface of positive pressure side condensing container connects the first liquid level differential pressure transmitter, just
3rd procedural interface connection positive pressure side blowoff valve of pressure side condensing container.
Improve further, described second connecting pipe passes through the one or three valve group and connects the first liquid level differential pressure transmitter, described the
Three connecting pipes pass through the two or three valve group and connect the second liquid level differential pressure transmitter；Described 6th connecting pipe through the second threeway, the one or three
Lead to logical first liquid level differential pressure transmitter；Described 4th connecting pipe is respectively communicated with the 7th connecting pipe and the second liquid level through the 3rd threeway
Differential pressure transmitter.
Improve again, described one or three valve group include the one or three valve group suction side isolating valve, the one or three valve group positive pressure side every
From valve and the one or three valve group balanced valve；Described two or three valve group includes the two or three valve group suction side isolating valve, the two or three valve group
Positive pressure side isolating valve and the two or three valve group balanced valve.
The technical scheme that the above-mentioned further technical problem of present invention solution is adopted is: the liquid level based on double difference pressure transmitter
Measuring method, using above-mentioned liquid level emasuring device it is characterised in that comprising the steps 1 to step 6:
Step 1, before described liquid level emasuring device comes into operation and under normal temperature and pressure state, to the first liquid level differential pressure
Transmitter and the second liquid level differential pressure transmitter carry out adjustment operation；Wherein, described adjustment operation comprises the steps 1-1 to step
1-6:
Step 1-1, closes suction side root valve and positive pressure side root valve, to keep described liquid level emasuring device to set with to be measured
Separate between standby；
Step 1-2, opens suction side blowoff valve, positive pressure side blowoff valve, the first knockout drum isolating valve, the second knockout drum isolation
Valve, knockout drum blowoff valve, the one or three valve group suction side isolating valve, the one or three valve group positive pressure side isolating valve, the two or three valve group negative pressure
Side isolating valve and the two or three valve group positive pressure side isolating valve, and close the one or three valve group balanced valve and the two or three valve group balanced valve；
Step 1-3, the DRAIN PLUG of suction side condensing container and positive pressure side condensing container is all opened, and keeps suction side
The DRAIN PLUG of condensing container is in open mode with the DRAIN PLUG of positive pressure side condensing container；
Step 1-4, by the first liquid level differential pressure transmitter and the zeroing of the second liquid level differential pressure transmitter, then by the first liquid level differential pressure
The range of transmitter and the second liquid level differential pressure transmitter is disposed as -1000h1G～0；Wherein, h1For the first liquid level differential pressure transporting
The negative pressure mouth of pipe of device to the malleation mouth of pipe vertical dimension；G is the acceleration of gravity of described liquid level emasuring device present position；
Step 1-5, after closing suction side blowoff valve and positive pressure side blowoff valve, by suction side condensing container and positive pressure side condensation
Water is filled in container, then the closure DRAIN PLUG of suction side condensing container and the DRAIN PLUG of positive pressure side condensing container respectively；
Step 1-6, checks after confirming that knockout drum blowoff valve no liquid is discharged, first closes knockout drum blowoff valve, then open negative
Pressure side root valve and positive pressure side root valve, thus complete the adjustment work for described liquid level emasuring device；
Step 2, starts described liquid level emasuring device, and carries out discharge opeing operation according to prefixed time interval to knockout drum；Its
In, the discharge opeing operation for knockout drum comprises the steps 2-1 to step 2-5:
Step 2-1, locks and keeps the measured value of the second liquid level differential pressure transmitter；
Step 2-2, closes the first knockout drum isolating valve and the two or three valve group positive pressure side isolating valve；
Step 2-3, knockout drum isolating valve and the operation opening knockout drum blowoff valve are closed in circulation execution successively, and finally make
Knockout drum blowoff valve is in open mode；
Step 2-4, checks after confirming that knockout drum blowoff valve no liquid is discharged, closes knockout drum blowoff valve, open the respectively
One knockout drum isolating valve and the second knockout drum isolating valve, and open the two or three valve group positive pressure side isolating valve；
Step 2-5, releases the locking to the second liquid level differential pressure transmitter measured value, so that the second liquid level differential pressure transmitter weight
Newly put into operation, thus completing discharge opeing operation；
Step 3, the first liquid level differential pressure transmitter device under test carries out differential pressure measurement, acquires corresponding first liquid level difference
The first differential pressure value between the malleation lateral pressure of pressure transmitter and negative pressure lateral pressure: wherein, described first differential pressure value is labeled as δ
p1；First differential pressure value δ p1Computing formula as follows:
δp1=p0+ρ0hg+ρs(h1-h)g-(p0+ρ1h1g)
=(ρ0-ρs)hg+(ρs-ρ1)h1g；
Wherein, p0Represent the operating pressure of gas phase in Devices to test, ρ0Represent the density of liquid phase in Devices to test, h represents and treats
Liquid level to be measured is needed, g represents the acceleration of gravity on the residing ground of described Devices to test, ρ in measurement equipmentsRepresent in Devices to test
Density of gas phase, h1Represent the vertical dimension of the negative pressure mouth of pipe of the first liquid level differential pressure transmitter to the malleation mouth of pipe；ρ1Expression is in negative
The density of liquid phase in the first connecting pipe between pressure side condensing container and the 3rd connecting pipe；
Step 4, the second liquid level differential pressure transmitter device under test carries out differential pressure measurement, acquires corresponding second liquid level difference
The second differential pressure value between the malleation lateral pressure of pressure transmitter and negative pressure lateral pressure: wherein, described second differential pressure value is labeled as δ
p2；Second differential pressure value δ p2Computing formula as follows:
δp2=p0+ρsh1g-(p0+ρ1h1g)
=(ρs-ρ1)h1g；
Step 5, according to gained first differential pressure value and the second differential pressure value, obtains between the first differential pressure value and the second differential pressure value
Difference；Wherein, the difference between the first differential pressure value and the second differential pressure value is labeled as δ p:
δ p=δ p1-δp2
=(ρ0-ρs)hg；
Step 6, according to the difference between the first differential pressure value and the second differential pressure value, finally give need in Devices to test to be measured
The liquid level of amount: wherein it is desired to liquid level h computing formula to be measured is as follows:
Compared with prior art, it is an advantage of the current invention that:
First, liquid level emasuring device provided by the present invention arranges two liquid level differential pressure transmitters, i.e. the first liquid level
Differential pressure transmitter and the second liquid level differential pressure transmitter, the first liquid level differential pressure transmitter measure in real time suction side condensing container with to be measured
Differential pressure between the malleation mouth of pipe of equipment, the second liquid level differential pressure transmitter measures suction side condensing container and the 3rd connecting pipe in real time
Between the upper and lower differential pressure of the first connecting pipe, to eliminate the uncertainty of density of liquid phase in the first connecting pipe to surveying in Devices to test
Steam drum liquid level measurement precision impacts so that the liquid level of steam drum finally giving will not be subject to the density of liquid phase in the first connecting pipe
Impact, and then eliminate the impact that operating condition change, variation of ambient temperature and heat tracing cause to certainty of measurement, effectively protect
Demonstrate,prove the precision of steam drum liquid level measurement；
Secondly, measured using the liquid level of steam drum in the level measuring method device under test of present invention offer, reduce
The length of the first connecting pipe of in the vertical direction, eliminates because in connecting pipe between the positive and negative pressure side pipe mouth of Devices to test
Extra error caused by the density contrast of liquid phase medium, further increases steam drum liquid level measurement precision.
Brief description
Fig. 1 is the structural representation of the liquid level emasuring device in the embodiment of the present invention based on double difference pressure transmitter；
Fig. 2 is the level measuring method schematic flow sheet in the embodiment of the present invention based on double difference pressure transmitter.
Specific embodiment
Below in conjunction with accompanying drawing embodiment, the present invention is described in further detail.
As shown in figure 1, the liquid level emasuring device based on double difference pressure transmitter in the present embodiment, including the first liquid level differential pressure
Transmitter lt1 and the second liquid level differential pressure transmitter lt2, wherein:
The negative port of the first liquid level differential pressure transmitter lt1 connects the negative pressure mouth of pipe of Devices to test by the first connecting pipe 1
K1, the first connecting pipe 1 is provided with the suction side root valve v1 and suction side condensing container c1 of next-door neighbour negative pressure mouth of pipe k1；First liquid
The positive pressure interface of potential difference pressure transmitter lt1 connects the malleation mouth of pipe k2 of Devices to test, the second connecting pipe 2 by the second connecting pipe 2
It is provided with the positive pressure side root valve v2 and positive pressure side condensing container c2 of next-door neighbour malleation mouth of pipe k2；
The negative port of the second liquid level differential pressure transmitter lt2 connects the first connecting pipe 1 by the 3rd connecting pipe 3；Second liquid
The positive pressure interface of potential difference pressure transmitter lt2 connects suction side condensing container c1 by the 4th connecting pipe 4, and the 4th connecting pipe 4 sets
There is the first knockout drum isolating valve v5 of next-door neighbour suction side condensing container c1；
The communicating downstream of positive pressure side condensing container c2 has the 5th connecting pipe 5, and the 5th connecting pipe 5 is provided with positive pressure side blowdown
Valve v4；
The communicating downstream of the 3rd connecting pipe 3 has the 6th connecting pipe 6, is provided with suction side blowoff valve on the 6th connecting pipe 6
v3；The communicating downstream of the 4th connecting pipe 4 has the 7th connecting pipe 7, and the 7th connecting pipe 7 is connected with turn the second knockout drum isolating valve
V6 and knockout drum c3, is provided with knockout drum blowoff valve v7 on the 7th connecting pipe 7 in knockout drum c3 downstream.
With improvement, in the liquid level emasuring device based on double difference pressure transmitter for the present embodiment, suction side condensing container c1 and
Positive pressure side condensing container c2 is provided with three procedural interfaces and a floss hole being furnished with DRAIN PLUG.Suction side condensation is held
One procedural interface connection suction side root valve v1 of device c1, another procedural interface of suction side condensing container c1 is respectively communicated with
3rd procedural interface of the first liquid level differential pressure transmitter lt1 and the second liquid level differential pressure transmitter lt2, suction side condensing container c1
Connect the first knockout drum isolating valve v5.Accordingly, a procedural interface connection positive pressure side root valve of positive pressure side condensing container c2
Another procedural interface the connection first liquid level differential pressure transmitter lt1, positive pressure side condensing container c2 of v2, positive pressure side condensing container c2
The 3rd procedural interface connection positive pressure side blowoff valve v4.
In addition, in the present embodiment, the second connecting pipe 2 passes through the one or three valve group tv1 and connects the first liquid level differential pressure transmitter
Lt1, the 3rd connecting pipe 3 passes through the two or three valve group tv2 and connects the second liquid level differential pressure transmitter lt2；6th connecting pipe 6 is through the two or three
Logical t2, the first threeway t1 connect the first liquid level differential pressure transmitter lt1；4th connecting pipe 4 is respectively communicated with the 7th through the 3rd threeway t3
Connecting pipe 7 and the second liquid level differential pressure transmitter lt2.
Improve again, the liquid level emasuring device in the present embodiment also includes two three valve groups, be the one or three valve group tv1 respectively
With the two or three valve group tv2；Wherein, the one or three valve group tv1 includes the one or three valve group suction side isolating valve v11, the one or three valve group
Positive pressure side isolating valve v12 and the one or three valve group balanced valve v13；Two or three valve group tv2 includes the two or three valve group suction side isolation
Valve v21, the two or three valve group positive pressure side isolating valve v22 and the two or three valve group balanced valve v23.
In addition, as shown in Fig. 2 using above-mentioned liquid level emasuring device, the present embodiment also provides one kind to be based on double difference buckling
Send the level measuring method of device, this level measuring method comprises the steps 1 to step 6:
Step 1, before liquid level emasuring device comes into operation and under normal temperature and pressure state, to the first liquid level differential pressure transporting
Device lt1 and the second liquid level differential pressure transmitter lt2 carries out adjustment operation；Wherein, adjustment operation comprises the steps 1-1 to step 1-
6:
Step 1-1, closes suction side root valve v1 and positive pressure side root valve v2, to keep liquid level emasuring device to set with to be measured
Separate between standby 8；In this manner it is ensured that any operation of Devices to test 8 will not be to the preliminary adjustment work of measurement apparatus
Make to produce impact, any adjustment operation of measurement apparatus also the operation of device under test 8 will not produce impact；
Step 1-2, opens suction side blowoff valve v3, positive pressure side blowoff valve v4, the first knockout drum isolating valve v5, the second separation
Tank isolating valve v6, knockout drum blowoff valve v7, the one or three valve group suction side isolating valve v11, the one or three valve group positive pressure side isolating valve
V12, the two or three valve group suction side isolating valve v21 and the two or three valve group positive pressure side isolating valve v22, and close the one or three valve group balance
Valve v13 and the two or three valve group balanced valve v23；
Step 1-3, the DRAIN PLUG of suction side condensing container c1 and positive pressure side condensing container c2 is all opened, and keeps negative
The DRAIN PLUG of pressure side condensing container c1 and the DRAIN PLUG of positive pressure side condensing container c2 are in open mode；
Step 1-4, by the first liquid level differential pressure transmitter lt1 and the second liquid level differential pressure transmitter lt2 zeroing, then by the first liquid
The range of potential difference pressure transmitter lt1 and the second liquid level differential pressure transmitter lt2 is disposed as -1000h1G～0；Under normal temperature and pressure, water
Density be about 1000kg/m3, wherein, h1Negative pressure mouth of pipe k1 to malleation mouth of pipe k2 for the first liquid level differential pressure transmitter lt1 away from
From；G is the acceleration of gravity of liquid level emasuring device present position；
Step 1-5, after closing suction side blowoff valve v3 and positive pressure side blowoff valve v4, by suction side condensing container c1 and malleation
Water is filled in the condensing container c2 of side, then the DRAIN PLUG of closure suction side condensing container c1 and positive pressure side condensing container c2 respectively
DRAIN PLUG；After liquid level emasuring device comes into operation, the liquidus temperature in the first connecting pipe 1 and the second connecting pipe 2 can rise
Height, the suction side condensing container c1 of setting can provide extra cooling effect to the liquid phase in the first connecting pipe 1, and positive pressure side condenses
Container c2 can provide extra cooling effect to the liquid phase in the second connecting pipe 2, reduces the first liquid level differential pressure transmitter lt1 with this
Operating temperature during work, reduces the temperature difference of the positive and negative both sides of the first liquid level differential pressure transmitter lt1；
Step 1-6, checks after confirming that knockout drum blowoff valve v7 no liquid is discharged, first closes knockout drum blowoff valve v7, then beat
Open suction side root valve v1 and positive pressure side root valve v2, thus completing the adjustment work for liquid level emasuring device；
Step 2, starts liquid level emasuring device, and carries out discharge opeing operation according to prefixed time interval to knockout drum c3；Wherein,
Discharge opeing operation for knockout drum c3 comprises the steps 2-1 to step 2-5:
Step 2-1, locks and keeps the measured value of the second liquid level differential pressure transmitter lt2, it is to avoid discharge opeing operation is surveyed to liquid level
Amount causes to fluctuate；
Step 2-2, closes the first knockout drum isolating valve v5 and the two or three valve group positive pressure side isolating valve v22；
Step 2-3, knockout drum isolating valve v6 and the operation opening knockout drum blowoff valve v7 are closed in circulation execution successively, and
Knockout drum blowoff valve v7 is made to be in open mode eventually；
Step 2-4, checks after confirming that knockout drum blowoff valve v7 no liquid is discharged, closes knockout drum blowoff valve v7, beat respectively
Open the first knockout drum isolating valve v5 and the second knockout drum isolating valve v6, and open the two or three valve group positive pressure side isolating valve v22；
Step 2-5, releases the locking to the second liquid level differential pressure transmitter lt2 measured value, so that the second liquid level differential pressure transporting
Device lt2 puts into operation again, thus completing discharge opeing operation；
Step 3, the first liquid level differential pressure transmitter lt1 device under test 8 carries out differential pressure measurement, acquires corresponding first liquid
The first differential pressure value between the malleation lateral pressure of potential difference pressure transmitter lt1 and negative pressure lateral pressure: wherein, the first differential pressure value is labeled as
δp1；First differential pressure value δ p1Computing formula as follows:
δp1=p0+ρ0hg+ρs(h1-h)g-(p0+ρ1h1g)
=(ρ0-ρs)hg+(ρs-ρ1)h1g；
Wherein, p0Represent the operating pressure of gas phase in Devices to test 8, ρ0Represent the density of liquid phase in Devices to test 8, h represents
Liquid level to be measured is needed, g represents the acceleration of gravity of Devices to test 8 present position, ρ in Devices to test 8sRepresent Devices to test
Density of gas phase in 8, h1Represent the vertical dimension of the negative pressure mouth of pipe k1 to malleation mouth of pipe k2 of the first liquid level differential pressure transmitter lt1；ρ1
Represent the density of liquid phase in the first connecting pipe 1 being between suction side condensing container c1 and the 3rd connecting pipe 3；This density of liquid phase
ρ1Often because the factor such as heat tracing or drum brownout operation that come into operation larger day and night temperature, cold season is affected and shows
Very big uncertainty, density of liquid phase ρ1Have a strong impact on the accuracy of measurement of liquid level of steam drum and control accuracy in Devices to test；
Liquid level of steam drum in Devices to test is exactly required liquid level h to be measured in the present embodiment herein；Wherein, liquid level h to be measured
Maximum occurrences be h1；
Step 4, the second liquid level differential pressure transmitter lt2 device under test 8 carries out differential pressure measurement, acquires corresponding second liquid
The second differential pressure value between the malleation lateral pressure of potential difference pressure transmitter lt2 and negative pressure lateral pressure: wherein, the second differential pressure value is labeled as
δp2；Second differential pressure value δ p2Computing formula as follows:
δp2=p0+ρsh1g-(p0+ρ1h1g)
=(ρs-ρ1)h1g；
Step 5, according to gained the first differential pressure value δ p1With the second differential pressure value δ p2, obtain the first differential pressure value δ p1With second
Differential pressure value δ p2Between difference；Wherein, the first differential pressure value δ p1With the second differential pressure value δ p2Between difference be labeled as δ p:
δ p=δ p1-δp2
=(ρ0-ρs)hg；
Step 6, according to the first differential pressure value δ p1With the second differential pressure value δ p2Between difference, finally give in Devices to test 8
Need liquid level to be measured: wherein it is desired to liquid level h computing formula to be measured is as follows:
It is solely dependent upon according to the acquisition that the computing formula of liquid level h to be measured in step 6 can be seen that liquid level h value to be measured
First differential pressure value δ p1, the second differential pressure value δ p2, the density of liquid phase ρ in Devices to test 80, the density of gas phase ρ in Devices to test 8s
And the gravity acceleration g of Devices to test 8 present position, and badly affect liquid level measurement precision to be measured under normal circumstances
ρ1, that is, the density of liquid phase in the first connecting pipe 1 between suction side condensing container c1 and the 3rd connecting pipe 3 is in the present embodiment
In be eliminated.It can be seen that, using to be measured the setting of the level measuring method acquisition based on double difference pressure transmitter in the present embodiment
Liquid level h to be measured in standby is more accurate because eliminating the uncertain impact of density of liquid phase in the first connecting pipe 1, it is to avoid liquid
Position measurement is affected the certainty of measurement it is ensured that liquid level of steam drum by operating condition change, variation of ambient temperature and heat tracing, enters one
Step ensure that boiler and the safe operation of useless pot.
Claims (5)
1. the liquid level emasuring device based on double difference pressure transmitter it is characterised in that include the first liquid level differential pressure transmitter (lt1) and
Second liquid level differential pressure transmitter (lt2), wherein:
The negative port of described first liquid level differential pressure transmitter (lt1) connects the negative pressure of Devices to test by the first connecting pipe (1)
The mouth of pipe (k1), the first connecting pipe (1) is provided with the suction side root valve (v1) being close to the described negative pressure mouth of pipe (k1) and suction side
Condensing container (c1)；The positive pressure interface of the first liquid level differential pressure transmitter (lt1) connects Devices to test by the second connecting pipe (2)
The malleation mouth of pipe (k2), the second connecting pipe (2) is provided with the positive pressure side root valve (v2) being close to the described malleation mouth of pipe (k2) and malleation
Side condensing container (c2)；
The negative port of described second liquid level differential pressure transmitter (lt2) passes through the 3rd connecting pipe (3) and connects the first connecting pipe (1)；
The positive pressure interface of the second liquid level differential pressure transmitter (lt2) pass through the 4th connecting pipe (4) connect suction side condensing container (c1), the 4th
Connecting pipe (4) is provided with the first knockout drum isolating valve (v5) being close to described suction side condensing container (c1)；
The communicating downstream of described positive pressure side condensing container (c2) has the 5th connecting pipe (5), and the 5th connecting pipe (5) is provided with malleation
Side blowoff valve (v4)；
The communicating downstream of described 3rd connecting pipe (3) has the 6th connecting pipe (6), is provided with suction side on the 6th connecting pipe (6)
Blowoff valve (v3)；The communicating downstream of described 4th connecting pipe (4) has the 7th connecting pipe (7), and the 7th connecting pipe (7) is sequentially connected
There are the second knockout drum isolating valve (v6) and knockout drum (c3), described 7th connecting pipe (7) in knockout drum (c3) downstream is upper to be arranged
There is knockout drum blowoff valve (v7).
2. the liquid level emasuring device based on double difference pressure transmitter according to claim 1 is it is characterised in that described suction side
Condensing container (c1) and positive pressure side condensing container (c2) are provided with three procedural interfaces and a row with DRAIN PLUG
Put mouth；Wherein, procedural interface connection suction side root valve (v1) of suction side condensing container (c1), suction side condensing container
(c1) another procedural interface is respectively communicated with the first liquid level differential pressure transmitter (lt1) and the second liquid level differential pressure transmitter (lt2),
3rd procedural interface of suction side condensing container (c1) connects the first knockout drum isolating valve (v5)；Positive pressure side condensing container (c2)
Procedural interface connection positive pressure side root valve (v2), another procedural interface connection first of positive pressure side condensing container (c2)
Liquid level differential pressure transmitter (lt1), the 3rd procedural interface connection positive pressure side blowoff valve (v4) of positive pressure side condensing container (c2).
3. the liquid level emasuring device based on double difference pressure transmitter according to claim 2 is it is characterised in that described second leads
Pressure pipe (2) is passed through the one or three valve group (tv1) and is connected the first liquid level differential pressure transmitter (lt1), and described 3rd connecting pipe (3) passes through the
Two or three valve groups (tv2) connect the second liquid level differential pressure transmitter (lt2)；Described 6th connecting pipe (6) through the second threeway (t2), first
Threeway (t1) connects the first liquid level differential pressure transmitter (lt1)；Described 4th connecting pipe (4) is respectively communicated with through the 3rd threeway (t3)
Seven connecting pipes (7) and the second liquid level differential pressure transmitter (lt2).
4. the liquid level emasuring device based on double difference pressure transmitter according to claim 3 is it is characterised in that the described 1st
Valve group (tv1) includes the one or three valve group suction side isolating valve (v11), the one or three valve group positive pressure side isolating valve (v12) and first
Three valve group balanced valves (v13)；Described two or three valve group (tv2) include the two or three valve group suction side isolating valve (v21), the two or three
Valve group positive pressure side isolating valve (v22) and the two or three valve group balanced valve (v23).
5. the level measuring method based on double difference pressure transmitter, using the liquid level emasuring device described in claim 4, its feature exists
In comprising the steps 1 to step 6:
Step 1, before described liquid level emasuring device comes into operation and under normal temperature and pressure state, to the first liquid level differential pressure transporting
Device (lt1) and the second liquid level differential pressure transmitter (lt2) carry out adjustment operation；Wherein, described adjustment operation comprises the steps 1-1
To step 1-6:
Step 1-1, closes suction side root valve (v1) and positive pressure side root valve (v2), to keep described liquid level emasuring device and to treat
Separate between measurement equipment；
Step 1-2, open suction side blowoff valve (v3), positive pressure side blowoff valve (v4), the first knockout drum isolating valve (v5), second point
From tank isolating valve (v6), knockout drum blowoff valve (v7), the one or three valve group suction side isolating valve (v11), the one or three valve group positive pressure side
Isolating valve (v12), the two or three valve group suction side isolating valve (v21) and the two or three valve group positive pressure side isolating valve (v22), and close
One or three valve group balanced valves (v13) and the two or three valve group balanced valve (v23)；
Step 1-3, the DRAIN PLUG of suction side condensing container (c1) and positive pressure side condensing container (c2) is all opened, and keeps negative
The DRAIN PLUG of pressure side condensing container (c1) is in open mode with the DRAIN PLUG of positive pressure side condensing container (c2)；
Step 1-4, by the first liquid level differential pressure transmitter (lt1) and the zeroing of the second liquid level differential pressure transmitter (lt2), then by the first liquid
The range of potential difference pressure transmitter (lt1) and the second liquid level differential pressure transmitter (lt2) is disposed as -1000h1G～0；Wherein, h1For
The negative pressure mouth of pipe (k1) of the first liquid level differential pressure transmitter (lt1) to the malleation mouth of pipe (k2) distance；G is described liquid level emasuring device
The acceleration of gravity of present position；
Step 1-5, after closing suction side blowoff valve (v3) and positive pressure side blowoff valve (v4), by suction side condensing container (c1) with just
Water is filled in pressure side condensing container (c2), then the DRAIN PLUG of closure suction side condensing container (c1) and positive pressure side condensation respectively
The DRAIN PLUG of container (c2)；
Step 1-6, checks after confirming that knockout drum blowoff valve (v7) no liquid is discharged, first closes knockout drum blowoff valve (v7), then beat
Open suction side root valve (v1) and positive pressure side root valve (v2), thus completing the adjustment work for described liquid level emasuring device；
Step 2, starts described liquid level emasuring device, and carries out discharge opeing operation according to prefixed time interval to knockout drum (c3)；Its
In, the discharge opeing operation for knockout drum (c3) comprises the steps 2-1 to step 2-5:
Step 2-1, locks and keeps the measured value of the second liquid level differential pressure transmitter (lt2)；
Step 2-2, closes the first knockout drum isolating valve (v5) and the two or three valve group positive pressure side isolating valve (v22)；
Step 2-3, knockout drum isolating valve (v6) and the operation opening knockout drum blowoff valve (v7) are closed in circulation execution successively, and
Knockout drum blowoff valve (v7) is made to be in open mode eventually；
Step 2-4, checks after confirming that knockout drum blowoff valve (v7) no liquid is discharged, closes knockout drum blowoff valve (v7), beat respectively
Drive the first knockout drum isolating valve (v5) and the second knockout drum isolating valve (v6), and open the two or three valve group positive pressure side isolating valve
(v22)；
Step 2-5, releases the locking to the second liquid level differential pressure transmitter (lt2) measured value, so that the second liquid level differential pressure transmitter
(lt2) again put into operation, thus completing discharge opeing operation；
Step 3, the first liquid level differential pressure transmitter (lt1) device under test carries out differential pressure measurement, acquires corresponding first liquid level
The first differential pressure value between the malleation lateral pressure of differential pressure transmitter (lt1) and negative pressure lateral pressure: wherein, described first differential pressure value mark
It is designated as δ p1；First differential pressure value δ p1Computing formula as follows:
δp1=p0+ρ0hg+ρs(h1-h)g-(p0+ρ1h1g)
=(ρ0-ρs)hg+(ρs-ρ1)h1g；
Wherein, p0Represent the operating pressure of gas phase in Devices to test, ρ0Represent the density of liquid phase in Devices to test, h represents to be measured and sets
Standby middle needs liquid level to be measured, g represents the acceleration of gravity of described Devices to test present position, ρsRepresent in Devices to test
Density of gas phase, h1Represent the vertical dimension of the negative pressure mouth of pipe (k1) of the first liquid level differential pressure transmitter (lt1) to the malleation mouth of pipe (k2)；
ρ1Represent the density of liquid phase in the first connecting pipe (1) being between suction side condensing container (c1) and the 3rd connecting pipe (3)；
Step 4, the second liquid level differential pressure transmitter (lt2) device under test carries out differential pressure measurement, acquires corresponding second liquid level
The second differential pressure value between the malleation lateral pressure of differential pressure transmitter (lt2) and negative pressure lateral pressure: wherein, described second differential pressure value mark
It is designated as δ p2；Second differential pressure value δ p2Computing formula as follows:
δp2=p0+ρsh1g-(p0+ρ1h1G)=(ρs-ρ1)h1g；
Step 5, according to gained first differential pressure value and the second differential pressure value, obtains the difference between the first differential pressure value and the second differential pressure value
Value；Wherein, the difference between the first differential pressure value and the second differential pressure value is labeled as δ p:
δ p=δ p1-δp2=(ρ0-ρs)hg；
Step 6, according to the difference between the first differential pressure value and the second differential pressure value, finally give need in Devices to test to be measured
Liquid level: wherein it is desired to liquid level h computing formula to be measured is as follows:
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| CN109387258A (en) * | 2018-11-23 | 2019-02-26 | 中国二十二冶集团有限公司 | Heat exchanger condensed water liquid level control system and method are measured or controlled using differential pressure transmitter |
| CN111380589A (en) * | 2020-03-28 | 2020-07-07 | 华中科技大学 | Liquid level measuring device and liquid level measuring method for pressure difference type gas storage |
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| CN111380589A (en) * | 2020-03-28 | 2020-07-07 | 华中科技大学 | Liquid level measuring device and liquid level measuring method for pressure difference type gas storage |
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| CN106352942B (en) | 2019-05-17 |
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