CN104236640A - Simple gas flow measuring device and measuring method - Google Patents

Abstract

The invention relates to a simple gas flow measuring device and a measuring method, and belongs to the technical field of pipeline gas flow measuring equipment and methods. According to the technical scheme, a regulating valve is arranged on a gas pipeline; an upstream pressure measuring device is arranged on the gas pipeline on the front part of the regulating valve; a downstream pressure measuring device is arranged on the gas pipeline on the back part of the regulating valve; a temperature measuring device is arranged on the back part of the downstream pressure measuring device; the output signals of the regulating valve, the upstream pressure measuring device, the downstream pressure measuring device and the temperature measuring device are connected with a field control station respectively. By adopting the simple gas flow measuring device and the measuring method, the gas flow can be calculated indirectly by using the flow characteristic and flow coefficient Ci value calculating formulas of the regulating valve and the upstream and downstream pressure values and temperature value of the regulating valve without flow instrument equipment; compared with a practically-arranged pore plate flow meter, the simple gas flow measuring device has the advantages that the flow error can be controlled within +/-3 percent, guidance is provided for process production, and the flow measuring problem of incapability of mounting a flow meter or lack of the flow meter on site is solved.

Description

A kind of simple gas flow measurement device and measuring method

Technical field

The present invention relates to a kind of simple gas flow measurement device and measuring method, belong to pipeline gas flow measurement and method and technology field.

Background technology

In smelter commercial production, pipeline gas flow generally adopts the standard throttle apparatus such as orifice plate and plug-in type gas meter to carry out flow measurement, and recycling variable valve regulates gas flow.As can be seen from the flow rate calculation formula of standard throttle apparatus and variable valve, both have common feature, are all to utilize pipeline section to amass to calculate volumetric flow rate with the product of gas flow rate, and just gas flow counts permanent area, and variable valve is variable area.At present some pipeline do not carry out flow measurement by standard throttle apparatus such as gas meters, its reason one is that the caliber of pipeline is large, straight length is little, cannot install flow measurement device, and two is do not needing not install flowmeter in accurate flow metering conduit.Therefore how carrying out flow measurement to the pipeline not installing flowmeter is the problem perplexing enterprise and technician at present.

Summary of the invention

Technical matters to be solved by this invention is to provide a kind of simple gas flow measurement device and measuring method, this apparatus and method can not use traffic instrumentation, utilization is arranged on ducted flow control valve indirect calculation and goes out gas flow, be used to guide explained hereafter, cannot install in solution scene or lack flowmeter but have the difficult problem of the flow measurement of variable valve.

The technical scheme solved the problems of the technologies described above is:

A kind of simple gas flow measurement device, its formation comprises gas pipeline, variable valve, upstream pressure measurement mechanism, downstream pressure measurement mechanism, temperature measuring equipment, field control station, operator station, variable valve is arranged on gas pipeline, along the direction of gas flow, upstream pressure measurement mechanism is arranged on the gas pipeline of variable valve front portion, downstream pressure measurement mechanism is arranged on the gas pipeline at variable valve rear portion, temperature measuring equipment is arranged on the rear portion of downstream pressure measurement mechanism, variable valve, upstream pressure measurement mechanism, downstream pressure measurement mechanism, the output signal of temperature measuring equipment is connected with field control station respectively, field control station is connected with operator station.

Above-mentioned simple gas flow measurement device, described variable valve is electronic or pneumatic control valve, and upstream pressure measurement mechanism and downstream pressure measurement mechanism are pressure unit, and temperature measuring equipment is Pt100 thermal resistance.

Use the gas flow measurement method of above-mentioned simple gas flow measurement device, it adopts following steps:

1, the discharge characteristic of installed variable valve and the flow rate calculation formula of this variable valve is determined

The discharge characteristic of smelter gas flow regulating valve is the one in linear characteristic and log characteristic, and after variable valve type selecting, discharge characteristic is just determined;

The flow formula of the variable valve of linear characteristic is:

$\frac{Q_i}{Q_{\mathrm{MAX}}}=\frac{1}{R}[1+(R-1)\frac{l}{L}]----------------------------------\left(1\right)$

The flow formula of the variable valve of log characteristic is:

$\frac{Q_i}{Q_{\mathrm{MAX}}}{R}^{(\frac{l}{L}-1)}----------------------------------------------\left(2\right)$

In formula (1), formula (2): Q _iflow under-variable valve l aperture, Nm ³/ h;

Q _mAXthe adjustable maximum flow of-variable valve, Nm ³/ h;

Q _mINthe adjustable minimum flow of-variable valve, Nm ³/ h;

The aperture of l-variable valve, 0-100%;

The maximum opening of L-variable valve, equals 100%.

2, flow coefficient C is determined _ivalue computing formula

According to the gauge pressure p that the upstream pressure measurement mechanism be arranged on gas pipeline records ₁(absolute pressure P before valve ₁=100+p ₁, unit: 100kPa), the gauge pressure p that records of downstream pressure measurement mechanism ₂(absolute pressure P after valve ₂=100+p ₂, unit: 100kPa) and the temperature t (DEG C) that records of temperature measuring equipment, judge following condition:

1) P is worked as ₂> 0.5P ₁time, be general flowing gas, the C of selected variable valve _icomputing formula:

$C_i=\frac{Q_i}{380}\sqrt{\frac{{\mathrm{\γ}}_N(273+t)}{{P_1}^2-{P_2}^2}}--------------------------------\left(3\right)$

Work as Q _i=Q _mAXtime, C _i=C _mAX, then (3) become (4):

$Q_{\mathrm{MAX}}=380C_{\mathrm{MAX}}\sqrt{\frac{{P_1}^2-{P_2}^2}{{\mathrm{\γ}}_N(273+t)}}----------------------\left(4\right)$

2) P is worked as ₂≤ 0.5P ₁time, be obstructed flow gas, the C of selected variable valve _icomputing formula:

$C_i=\frac{Q_i}{330}\frac{\sqrt{{\mathrm{\γ}}_N(273+t)}}{P_1}--------------------------------\left(5\right)$

Work as Q _i=Q _mAXtime, C _i=C _mAX, then (5) become (6):

$Q_{\mathrm{MAX}}=330P_1{C}_{\mathrm{MAX}}\sqrt{\frac{1}{{\mathrm{\γ}}_N(273+t)}}------------------\left(6\right)$

Formula is (in 3) – formulas (6): Q _iflow under-variable valve l aperture, Nm ³/ h;

γ _n-gas severe, kg/Nm ³;

C _i-regulating valve flow coefficient, Nm ³/ h;

Q _mAXthe adjustable maximum flow of-variable valve, Nm ³/ h;

C _mAX-variable valve maximum flow coefficient;

3, determine to calculate formula by the gas flow of variable valve

1) P is worked as ₂> 0.5P ₁time, be general flowing gas

When variable valve is linear characteristic, (4) is substituted into (1) and obtain (7):

$Q_i=\frac{1}{R}[1+(R-1)\frac{l}{L}]380C_{\mathrm{MAX}}\sqrt{\frac{{P_1}^2-{P_2}^2}{{\mathrm{\γ}}_N(273+t)}}---------------------\left(7\right)$

When variable valve is log characteristic, (4) is substituted into (2) and obtain (8):

$Q_i=R^{(\frac{l}{L}-1)}380C_{\mathrm{MAX}}\sqrt{\frac{{P_1}^2-{P_2}^2}{{\mathrm{\γ}}_N(273+t)}}---------------------\left(8\right)$

2) P is worked as ₂≤ 0.5P ₁time, be obstructed flow gas

When variable valve is linear characteristic, (6) is substituted into (1) and obtain (9):

$Q_i=\frac{1}{R}[1+(R-1)\frac{l}{L}]330P_1{C}_{\mathrm{MAX}}\sqrt{\frac{1}{{\mathrm{\γ}}_N(273+t)}}--------\left(9\right)$

When variable valve is log characteristic, (6) is substituted into (2) and obtain (10):

$Q_i=R^{(\frac{l}{L}-1)}330P_1{C}_{\mathrm{MAX}}\sqrt{\frac{1}{{\mathrm{\γ}}_N(273+t)}}---------------------\left(10\right)$

4, the gas flow of variable valve is calculated

Through type (7)-Shi (10) calculates the gas flow with the variable valve of linear characteristic and log characteristic corresponding to general flowing gas, obstructed flow gas respectively.

Usefulness of the present invention is:

The invention provides a kind of simple gas flow measurement device and measuring method, this apparatus and method can not use traffic instrumentation, force value and temperature value indirect calculation before and after the discharge characteristic of the variable valve installed, flow coefficient C i value computing formula, variable valve is utilized to go out gas flow, compare with the orifice flowmeter of actual installation, flow error can control ± 3% scope in, be used to guide explained hereafter, solve in some industrial site a difficult problem for the flow measurement cannot installing flowmeter or lack flowmeter.Structure of the present invention is simple, easy to use, with simple method solve in actual production a difficult problem, being specially adapted to flow measurement requirement is not very accurate Workplace, prove through actual use, this device and measuring method can meet the needs that general technology is produced completely, save equipment, reduce production cost.

Accompanying drawing explanation

Fig. 1 is structural representation of the present invention;

In figure, mark is as follows: gas pipeline 1, variable valve 2, upstream pressure measurement mechanism 3, downstream pressure measurement mechanism 4, temperature measuring equipment 5, field control station 6, operator station 7.

Embodiment

Because variable valve is the indispensable equipment of flow regulation during metallurgical industry is produced, the discharge characteristic formula Simple Calculation gas flow of variable valve so just can be utilized.Utilize the discharge characteristic of variable valve, may be used for non-accurate-metering occasion and simply estimate gas flow, instruct explained hereafter.The method of this easy estimation gas flow may be used for following occasion: one is that caliber is large, and straight length is little, cannot install flow measurement device; Two is mounted Causing Flowmeter Damages; Three is the occasions not needing accurate flow to measure.Prove through actual use, this method meets the needs that general technology is produced completely, has simple and practical advantage.

Show in figure, simple gas flow measurement device comprises gas pipeline 1, variable valve 2, upstream pressure measurement mechanism 3, downstream pressure measurement mechanism 4, temperature measuring equipment 5, field control station 6.

Variable valve 2 is arranged on gas pipeline 1, along the direction of gas flow, upstream pressure measurement mechanism 3 is arranged on the gas pipeline 1 of variable valve 2 front portion, downstream pressure measurement mechanism 4 is arranged on the gas pipeline 1 at variable valve 3 rear portion, temperature measuring equipment 5 is arranged on the rear portion of downstream pressure measurement mechanism 4, the output signal of variable valve 2, upstream pressure measurement mechanism 3, downstream pressure measurement mechanism 4, temperature measuring equipment 5 is connected with field control station 6 respectively, and field control station 6 is connected with operator station 7.

Show in figure, variable valve 2 is electronic or pneumatic control valve, and upstream pressure measurement mechanism 3 and downstream pressure measurement mechanism 4 are pressure unit, and temperature measuring equipment 5 is Pt100 thermal resistance.

Field control station 6 is made up of inputting modular unit, output module, power module, cpu controller part, bus mother board module, and inputting modular unit, output module, power module, cpu controller part, NIM are connected by bus mother board module and be arranged on bus mother board module.

The NIM of field control station 6 is connected with operator station 7, and NIM is the one in industrial switch, Ethernet template, fieldbus, and operator station 7 is industrial computer or graphic control panel.

Variable valve 2 of the present invention, upstream pressure measurement mechanism 3, downstream pressure measurement mechanism 4, temperature measuring equipment 5 detect valve opening, upstream pressure, downstream pressure, gas temperature respectively, and these detection signals are input to field control station 6 carry out process calculate, obtain gas flow numerical value.

The gas flow measurement method of the above-mentioned simple gas flow measurement device of use of the present invention, it adopts following steps:

1, the discharge characteristic of installed variable valve 2 is determined

The discharge characteristic of smelter gas flow regulating valve 2 is the one in linear characteristic and log characteristic, and after variable valve 2 type selecting, discharge characteristic is just determined.

The flow formula of the variable valve 2 of linear characteristic is:

$\frac{Q_i}{Q_{\mathrm{MAX}}}=\frac{1}{R}[1+(R-1)\frac{l}{L}]----------------------------------\left(1\right)$

The flow formula of the variable valve 2 of log characteristic is:

$\frac{Q_i}{Q_{\mathrm{MAX}}}{R}^{(\frac{l}{L}-1)}----------------------------------------------\left(2\right)$

In formula (1), formula (2): Q _iflow under-variable valve l aperture, Nm ³/ h;

Q _mAXthe adjustable maximum flow of-variable valve, Nm ³/ h;

Q _mINthe adjustable minimum flow of-variable valve, Nm ³/ h;

(being checked in by the instructions of variable valve);

The aperture of l-variable valve, 0-100%;

The maximum opening of L-variable valve, equals 100%.

2, flow coefficient C is determined _ivalue computing formula

According to the gauge pressure p that the upstream pressure measurement mechanism 3 be arranged on gas pipeline 1 records ₁(absolute pressure P before valve ₁=100+p ₁, unit: 100kPa), the gauge pressure p that records of downstream pressure measurement mechanism 4 ₂(absolute pressure P after valve ₂=100+p ₂, unit: 100kPa) and the temperature t (DEG C) that records of temperature measuring equipment 5, judge following condition:

1) P is worked as ₂> 0.5P ₁time, be general flowing gas, the C of selected variable valve 2 _icomputing formula:

$C_i=\frac{Q_i}{380}\sqrt{\frac{{\mathrm{\γ}}_N(273+t)}{{P_1}^2-{P_2}^2}}--------------------------------\left(3\right)$

Work as Q _i=Q _mAXtime, C _i=C _mAX, then (3) become (4):

$Q_{\mathrm{MAX}}=380C_{\mathrm{MAX}}\sqrt{\frac{{P_1}^2-{P_2}^2}{{\mathrm{\γ}}_N(273+t)}}----------------------\left(4\right)$

2) P is worked as ₂≤ 0.5P ₁time, be obstructed flow gas, the C of selected variable valve 2 _icomputing formula:

$C_i=\frac{Q_i}{330}\frac{\sqrt{{\mathrm{\γ}}_N(273+t)}}{P_1}--------------------------------\left(5\right)$

Work as Q _i=Q _mAXtime, C _i=C _mAX, then (5) become (6):

$Q_{\mathrm{MAX}}=330P_1{C}_{\mathrm{MAX}}\sqrt{\frac{1}{{\mathrm{\γ}}_N(273+t)}}------------------\left(6\right)$

Formula is (in 3) – formulas (6): Q _iflow under-variable valve l aperture, Nm ³/ h;

γ _n-gas severe, kg/Nm ³;

C _i-regulating valve flow coefficient, Nm ³/ h;

Q _mAXthe adjustable maximum flow of-variable valve, Nm ³/ h;

C _mAX-variable valve maximum flow coefficient (being checked in by the instructions of variable valve).

In theory, in formula (4), formula (6), P ₁, P ₂in should corresponding variable valve 2 standard-sized sheet time valve before maximum pressure after maximum pressure and valve.But actual verification, P ₁, P ₂force value under a certain aperture of corresponding variable valve 2, just in time as the pressure supplement to gas flow, this is innovation of the present invention just.

3, determine that the gas flow of variable valve 2 calculates formula

1) P is worked as ₂> 0.5P ₁time, be general flowing gas

When variable valve 2 is linear characteristic, (4) is substituted into (1) and obtain (7):

$Q_i=\frac{1}{R}[1+(R-1)\frac{l}{L}]380C_{\mathrm{MAX}}\sqrt{\frac{{P_1}^2-{P_2}^2}{{\mathrm{\γ}}_N(273+t)}}---------------------\left(7\right)$

When variable valve 2 is log characteristic, (4) is substituted into (2) and obtain (8):

$Q_i=R^{(\frac{l}{L}-1)}380C_{\mathrm{MAX}}\sqrt{\frac{{P_1}^2-{P_2}^2}{{\mathrm{\γ}}_N(273+t)}}---------------------\left(8\right)$

2) P is worked as ₂≤ 0.5P ₁time, be obstructed flow gas

When variable valve is linear characteristic, (6) is substituted into (1) and obtain (9):

$Q_i=\frac{1}{R}[1+(R-1)\frac{l}{L}]330P_1{C}_{\mathrm{MAX}}\sqrt{\frac{1}{{\mathrm{\γ}}_N(273+t)}}--------\left(9\right)$

When variable valve is log characteristic, (6) is substituted into (2) and obtain (10):

$Q_i=R^{(\frac{l}{L}-1)}330P_1{C}_{\mathrm{MAX}}\sqrt{\frac{1}{{\mathrm{\γ}}_N(273+t)}}---------------------\left(10\right)$

4, the gas flow of variable valve is calculated

Through type (7)-Shi (10) calculates the gas flow with the variable valve of linear characteristic and log characteristic corresponding to general flowing gas, obstructed flow gas respectively.

Part of devices model in embodiments of the invention is as follows:

The pressure unit model of upstream pressure measurement mechanism 3 and downstream pressure measurement mechanism 4 is EJA530A;

The model of temperature measuring equipment 5 is WZP-240;

The formation device of field control station 6 is as follows:

The model of inputting modular unit is 6ES7331-7KF02-0AB0 and 6ES7321-1BL00-0AA0; The model of output module is 6ES7332-7KF02-0AB0 and 6ES7322-1BL00-0AA0; The model of power module is 6ES7307-1KA01-0AA0; The model of cpu controller part is 6ES7315-2AH14-0AB0; The model of NIM is Moxa EDS-G205,6ES7343-1EX30-0XE0 and 6ES7153-1AA03-0XB0; The model of bus mother board module is 6ES7390-1GF30-0AA0.

The model of operator station 7 is for grinding magnificent IPC-610H type.

Embodiment 1

The model of variable valve 2 is ZKJW-0.6S, is gas regulator, DN800, and discharge characteristic is log characteristic, R=25 (being provided by variable valve operation instructions), coal gas density γ _n=1.36kg/m ³, C _max=217000.

The gauge pressure p that upstream pressure measurement mechanism 3 records ₁=4 ~ 8kPa;

Absolute pressure P before valve ₁=100+p ₁=104 ~ 108kPa=(1.04 ~ 1.08) x100kPa, unit: 100kPa;

The gauge pressure p that downstream pressure measurement mechanism 4 records ₂=1 ~ 5kPa;

Absolute pressure P before valve ₂=100+p ₂=101 ~ 105kPa=(1.01 ~ 1.05) x100kPa, unit: 100kPa.

So always have P ₂> 0.5P ₁.

Temperature t=-3 DEG C (data in November in winter) that temperature measuring equipment 5 records.

Selected calculated flow rate formula (8).Detailed data calculates and sees the following form.

Embodiment 2

The model of variable valve 2 is ZKJW-0.6S, is combustion air variable valve, DN1000, and discharge characteristic is log characteristic, R=25 (being provided by variable valve operation instructions), combustion air density γ _n=1.29kg/m ³, the maximum flow coefficient C of variable valve 2 _mAX=32000 (being provided by variable valve operation instructions).

The gauge pressure p that upstream pressure measurement mechanism 3 records ₁=9.5 ~ 12kPa;

Absolute pressure P before valve ₁=100+p ₁=109.5 ~ 112kPa=(1.095 ~ 1.12) x100kPa, unit: 100kPa;

The gauge pressure p that downstream pressure measurement mechanism 4 records ₂=4.5 ~ 8kPa;

Absolute pressure P before valve ₂=100+p ₂=104.5 ~ 108kPa=(1.045 ~ 1.08) x100kPa, unit: 100kPa.

So always have P ₂> 0.5P ₁.

Temperature t=-3 DEG C (data in November in winter) that temperature measuring equipment 5 records.

Selected calculated flow rate formula (8).Detailed data calculates and sees the following form.

In table, the method for the error of calculation is: the branch gas tube flow Q that flowmeter is measured ₁(Nm ³/ h), the gas flow Q that simple and easy method calculates _coal(Nm ³/ h), flowmeter branch gas tube maximum flow is 32000 (Nm ³/ h), gas flow error (%)=(Q _coal-Q ₁)/32000x100%; The combustion air arm flow Q that flowmeter is measured ₂(Nm ³/ h), the gas flow Q that simple and easy method calculates _wind(Nm ³/ h), flowmeter combustion air arm maximum flow is 45000 (Nm ³/ h), combustion air flow error (%)=(Q _wind-Q ₂)/45000x100%.

As can be seen from result of calculation, utilize variable valve to carry out Simple Calculation gas flow, compare with the orifice flowmeter of actual installation, flow error can control ± 3% scope in, be used to guide explained hereafter, flowmeter cannot be installed in solution scene or lack the difficult problem of flow measurement of flowmeter.

Certain blast-furnace hot-air producer gas (combustion air) utilizes variable valve calculated flow rate and flowmeter to record current capacity contrast

Claims (3)

1. a simple gas flow measurement device, it is characterized in that: its formation comprises gas pipeline (1), variable valve (2), upstream pressure measurement mechanism (3), downstream pressure measurement mechanism (4), temperature measuring equipment (5), field control station (6), operator station (7), variable valve (2) is arranged on gas pipeline (1), along the direction of gas flow, upstream pressure measurement mechanism (3) is arranged on the anterior gas pipeline (1) of variable valve (2), downstream pressure measurement mechanism (4) is arranged on the gas pipeline (1) at variable valve (2) rear portion, temperature measuring equipment (5) is arranged on the rear portion of downstream pressure measurement mechanism (4), variable valve (2), upstream pressure measurement mechanism (3), downstream pressure measurement mechanism (4), the output signal of temperature measuring equipment (5) is connected with field control station (6) respectively, field control station (6) is connected with operator station (7).

2. a kind of simple gas flow measurement device according to claim 1, it is characterized in that: described variable valve (2) is electronic or pneumatic control valve, described upstream pressure measurement mechanism (3), downstream pressure measurement mechanism (4) are pressure transmission device, and temperature measuring equipment (5) is Pt100 thermal resistance.

3. use a gas flow measurement method for simple gas flow measurement device described in claim 1 or 2, it is characterized in that, it adopts following steps:

A, determine the discharge characteristic of installed variable valve and the flow rate calculation formula of this variable valve

The discharge characteristic of smelter gas flow regulating valve is the one in linear characteristic and log characteristic, and after variable valve type selecting, discharge characteristic is just determined;

The flow formula of the variable valve of linear characteristic is:

$\frac{Q_i}{Q_{\mathrm{MAX}}}=\frac{1}{R}[1+(R-1)\frac{l}{L}]----------------------------------\left(1\right)$

The flow formula of the variable valve of log characteristic is:

$\frac{Q_i}{Q_{\mathrm{MAX}}}{R}^{(\frac{l}{L}-1)}----------------------------------------------\left(2\right)$

In formula (1), formula (2): Q _iflow under-variable valve l aperture, Nm ³/ h;

Q _mAXthe adjustable maximum flow of-variable valve, Nm ³/ h;

Q _mINthe adjustable minimum flow of-variable valve, Nm ³/ h;

$R=\frac{Q_{\mathrm{MAX}}}{Q_{\mathrm{MIN}}};$

The aperture of l-variable valve, 0-100%;

The maximum opening of L-variable valve, equals 100%.

B, determine flow coefficient C _ivalue computing formula

According to the gauge pressure p that the upstream pressure measurement mechanism be arranged on gas pipeline records ₁(absolute pressure P before valve ₁=100+p ₁, unit: 100kPa), the gauge pressure p that records of downstream pressure measurement mechanism ₂(absolute pressure P after valve ₂=100+p ₂, unit: 100kPa) and the temperature t (DEG C) that records of temperature measuring equipment, judge following condition:

A. P is worked as ₂> 0.5P ₁time, be general flowing gas, the C of selected variable valve _icomputing formula:

$C_i=\frac{Q_i}{380}\sqrt{\frac{{\mathrm{\γ}}_N(273+t)}{{P_1}^2-{P_2}^2}}--------------------------------\left(3\right)$

Work as Q _i=Q _mAXtime, C _i=C _mAX, then (3) become (4):

$Q_{\mathrm{MAX}}=380C_{\mathrm{MAX}}\sqrt{\frac{{P_1}^2-{P_2}^2}{{\mathrm{\γ}}_N(273+t)}}----------------------\left(4\right)$

B. P is worked as ₂≤ 0.5P ₁time, be obstructed flow gas, the C of selected variable valve _icomputing formula:

$C_i=\frac{Q_i}{330}\frac{\sqrt{{\mathrm{\γ}}_N(273+t)}}{P_1}--------------------------------\left(5\right)$

Work as Q _i=Q _mAXtime, C _i=C _mAX, then (5) become (6):

$Q_{\mathrm{MAX}}=330P_1{C}_{\mathrm{MAX}}\sqrt{\frac{1}{{\mathrm{\γ}}_N(273+t)}}------------------\left(6\right)$

Formula is (in 3) – formulas (6): Q _iflow under-variable valve l aperture, Nm ³/ h;

γ _n-gas severe, kg/Nm ³;

C _i-regulating valve flow coefficient, Nm ³/ h;

Q _mAXthe adjustable maximum flow of-variable valve, Nm ³/ h;

C _mAX-variable valve maximum flow coefficient;

C, determine to calculate formula by the gas flow of variable valve

A. P is worked as ₂> 0.5P ₁time, be general flowing gas

When variable valve is linear characteristic, (4) is substituted into (1) and obtain (7):

$Q_i=\frac{1}{R}[1+(R-1)\frac{l}{L}]380C_{\mathrm{MAX}}\sqrt{\frac{{P_1}^2-{P_2}^2}{{\mathrm{\γ}}_N(273+t)}}---------------------\left(7\right)$

When variable valve is log characteristic, (4) is substituted into (2) and obtain (8):

$Q_i=R^{(\frac{l}{L}-1)}380C_{\mathrm{MAX}}\sqrt{\frac{{P_1}^2-{P_2}^2}{{\mathrm{\γ}}_N(273+t)}}---------------------\left(8\right)$

B. P is worked as ₂≤ 0.5P ₁time, be obstructed flow gas

When variable valve is linear characteristic, (6) is substituted into (1) and obtain (9):

$Q_i=\frac{1}{R}[1+(R-1)\frac{l}{L}]330P_1{C}_{\mathrm{MAX}}\sqrt{\frac{1}{{\mathrm{\γ}}_N(273+t)}}--------\left(9\right)$

When variable valve is log characteristic, (6) is substituted into (2) and obtain (10):

$Q_i=R^{(\frac{l}{L}-1)}330P_1{C}_{\mathrm{MAX}}\sqrt{\frac{1}{{\mathrm{\γ}}_N(273+t)}}---------------------\left(10\right)$

The gas flow of D, calculating variable valve

Through type (7)-Shi (10) calculates the gas flow with the variable valve of linear characteristic and log characteristic corresponding to general flowing gas, obstructed flow gas respectively.