CN104501894A - Accurate steam flow metering compensating method - Google Patents

Abstract

The invention provides an accurate steam flow metering compensating method. By the accurate steam flow metering compensating method, the problems that random switching of states of steam is not considered in a steam flow metering compensating method in the prior art, and errors still exist possibly after compensation are solved. The accurate steam flow metering compensating method comprises the following steps of arranging a temperature sensor and a pressure sensor at a metering point; measuring the temperature and the pressure of steam at the metering point in real time; judging whether the temperature of the steam and the pressure of the steam have a corresponding relation or not in real time according to a measurement result; determining real-time steam density (rho2) by using a saturation steam compensating method if the temperature of the steam and the pressure of the steam have the corresponding relation; determining the real-time steam density (rho2) by using an over-hot steam compensating method if the temperature of the steam and the pressure of the steam do not have the corresponding relation; and calculating a steam flow metering value. The accurate steam flow metering compensating method has the advantages that the state of the steam can be judged in real time, compensation on the metering value is performed according to the state of the steam, compensation accuracy is improved, and compensation errors are eliminated.

Description

Steam flow measurement accurate compensation method

Technical field

The present invention relates to steam flow measurement compensation technique, a kind of steam flow measurement accurate compensation method is related specifically to.

Background technology

Prior art will be compensated in saturated vapor or superheated steam metering process to variable, specifically be calculated using following formula (1)：

$M=M_{\max }\×\frac{I-4}{16}\×\sqrt{\frac{{\mathrm{\ρ}}_2}{{\mathrm{\ρ}}_1}}---\left(1\right)$

In formula：M is the flow after compensation, units/kg/h；M_maxFor the engineering value of full scale flow, unit:kg/h；For the percentage of the flow before compensation, wherein, I is the flow signal current value (differential pressure transmitter setting evolution) that differential pressure transmitter is exported, and unit is mA；ρ₁·ρ₂The respectively design load and operation state values of density, unit is kg/m³.In specific calculate, difference mainly is used to ρ according to the different of metering object₂Variable is compensated.Specially：

For saturated vapor, different density ps is used according to different pressures scope₂Computing formula, can table look-up value, can also be calculated as follows using formula.

1 saturated vapor density ρ₂Computing formula：

2 and for superheated steam, density p₂Then using following formula (2) calculate：

${\mathrm{\ρ}}_2=\frac{1.04}{0.0004795\·\frac{T}{P}-\frac{1.45}{{\left(\frac{T}{100}\right)}^{3.1}}-557800\·\frac{P^2}{{\left(\frac{T}{100}\right)}^{13.5}}}---\left(2\right)$

In formula, T is temperature, and unit is K；P is absolute pressure value, and unit is Mpa.

Generally, when specifically being measured, it should first determine that detected steam species is superheated steam, or saturated vapor, variable is compensated according still further to foregoing mode.And in actual motion, due to the change of temperature and pressure, superheated steam and saturated vapor are not to be constantly in a constant state, but in the process of a continuous dynamic translation.Therefore, variable compensation is carried out to saturated vapor or superheated steam according to preceding method, it is equally possible to there is error.Obviously, prior art steam-flow meter amount compensation process has the random transition for not accounting for steam condition, the problems such as still there may be error after compensation.

The content of the invention

To solve the random transition for not accounting for steam condition that prior art steam-flow meter amount compensation process is present, the problems such as still there may be error after compensation, the present invention proposes a kind of steam flow measurement accurate compensation method.Steam flow measurement accurate compensation method of the present invention, sets temperature sensor and pressure sensor in stoichiometric point, the temperature and pressure of stoichiometric point steam is measured in real time；Saturated vapor temperature and pressure corresponding relation whether there is according to measurement result real-time judgment vapor (steam) temperature and pressure, be, real-time steam density p is determined using saturated vapor compensatory approach₂, otherwise, real-time steam density p is determined using superheated steam compensatory approach₂；

The saturated vapor compensatory approach, real-time steam density p is determined using following equation₂, i.e.,：

When pressure P is 0.10~0.32, vapour density ρ is calculated using formula 5.2353P+0.0816₂；

When pressure P is 0.32~0.70, vapour density ρ is calculated using formula 5.0221P+0.1517₂；

When pressure P is 0.70~1.00, vapour density ρ is calculated using formula 4.9283P+0.217₂；

When pressure P is 1.00~1.20, vapour density ρ is calculated using formula 4.9008P+0.2465₂；

When pressure P is 2.00~2.60, vapour density ρ is calculated using formula 4.9262P+0.199₂；

In formula, P is absolute pressure value, and unit is Mpa；Vapour density ρ₂Unit be kg/m³；

The superheated steam compensatory approach, real-time steam density p is calculated using following formula (2)₂, i.e.,：

${\mathrm{\ρ}}_2=\frac{1.04}{0.0004795\·\frac{T}{P}-\frac{1.45}{{\left(\frac{T}{100}\right)}^{3.1}}-557800\·\frac{P^2}{{\left(\frac{T}{100}\right)}^{13.5}}}---\left(2\right)$ In formula, T is temperature, and unit is K；P is absolute pressure value, and unit is Mpa；Then, steam-flow meter value is calculated using following formula (1),

$M=M_{\max }\×\frac{I-4}{16}\×\sqrt{\frac{{\mathrm{\ρ}}_2}{{\mathrm{\ρ}}_1}}---\left(1\right)$

In formula：M is the flow after compensation, units/kg/h；M_maxFor the engineering value of full scale flow, unit:kg/h；For the percentage of the flow before compensation, wherein, I is that the flow signal current value that differential pressure transmitter is exported, i.e. differential pressure transmitter set evolution, and unit is mA；ρ₁·ρ₂The respectively design load and operation state values of density, unit is kg/m³；

Also, it is above-mentioned judge and calculating process be real-time continuous judge and calculate, signal input flow rate integrating instrument, computer or arithmetic processor that temperature sensor and humidity sensor are exported in real time are judged and calculated.

The Advantageous Effects of steam flow measurement accurate compensation method of the present invention are real-time judge steam state in which, and carry out variable compensation according to steam state in which, improve the accuracy of compensation, eliminate compensation error.

Brief description of the drawings

Accompanying drawing 1 is the schematic diagram of steam flow measurement accurate compensation method of the present invention.

Steam flow measurement accurate compensation method of the present invention is further described with specific embodiment below in conjunction with the accompanying drawings.

Embodiment

Accompanying drawing 1 is the schematic diagram of steam flow measurement accurate compensation method of the present invention, as seen from the figure, and steam flow measurement accurate compensation method of the present invention sets temperature sensor and pressure sensor in stoichiometric point, the temperature and pressure of stoichiometric point steam is measured in real time；It whether there is the temperature and pressure corresponding relation of saturated vapor according to measurement result real-time judgment vapor (steam) temperature and pressure, be, real-time steam density p is determined using saturated vapor compensatory approach₂, otherwise, real-time steam density p is determined using superheated steam compensatory approach₂；

The saturated vapor compensatory approach, real-time steam density p is determined using following equation₂, i.e.,：

When pressure P is 0.10~0.32, vapour density ρ is calculated using formula 5.2353P+0.0816₂；

When pressure P is 0.32~0.70, vapour density ρ is calculated using formula 5.0221P+0.1517₂；

When pressure P is 0.70~1.00, vapour density ρ is calculated using formula 4.9283P+0.217₂；

When pressure P is 1.00~1.20, vapour density ρ is calculated using formula 4.9008P+0.2465₂；

When pressure P is 2.00~2.60, vapour density ρ is calculated using formula 4.9262P+0.199₂；

In formula, P is absolute pressure value, and unit is Mpa；Vapour density ρ₂Unit be kg/m³；

The superheated steam compensatory approach, real-time steam density p is calculated using following formula (2)₂, i.e.,：

${\mathrm{\ρ}}_2=\frac{1.04}{0.0004795\·\frac{T}{P}-\frac{1.45}{{\left(\frac{T}{100}\right)}^{3.1}}-557800\·\frac{P^2}{{\left(\frac{T}{100}\right)}^{13.5}}}---\left(2\right)$

In formula, T is temperature, and unit is K；P is absolute pressure value, and unit is Mpa；Then, steam-flow meter value is calculated using following formula (1),

$M=M_{\max }\×\frac{I-4}{16}\×\sqrt{\frac{{\mathrm{\ρ}}_2}{{\mathrm{\ρ}}_1}}---\left(1\right)$

In formula：M is the flow after compensation, units/kg/h；M_maxFor the engineering value of full scale flow, unit:kg/h；For the percentage of the flow before compensation, wherein, I is that the flow signal current value that differential pressure transmitter is exported, i.e. differential pressure transmitter set evolution, and unit is mA；ρ₁·ρ₂The respectively design load and operation state values of density, unit is kg/m³；

Also, it is above-mentioned judge and calculating process be real-time continuous judge and calculate, signal input flow rate integrating instrument, computer or arithmetic processor that temperature sensor and humidity sensor are exported in real time are judged and calculated.

Obviously, the Advantageous Effects of steam flow measurement accurate compensation method of the present invention are real-time judge steam state in which, and carry out variable compensation according to steam state in which, improve the accuracy of compensation, eliminate compensation error.

Claims (1)

1. a kind of steam flow measurement accurate compensation method, it is characterised in that temperature sensor and pressure sensor are set in stoichiometric point, measured in real time the temperature and pressure of stoichiometric point steam；Whether saturated vapour pressure and vs. temperature are obeyed according to measurement result real-time judgment vapor (steam) temperature and pressure, is, real-time steam density p is determined using saturated vapor compensatory approach₂, otherwise, real-time steam density p is determined using superheated steam compensatory approach₂；

The saturated vapor compensatory approach, real-time steam density p is determined using following equation₂, i.e.,：

When pressure P is 0.10~0.32, vapour density ρ is calculated using formula 5.2353P+0.0816₂；

When pressure P is 0.32~0.70, vapour density ρ is calculated using formula 5.0221P+0.1517₂；

When pressure P is 0.70~1.00, vapour density ρ is calculated using formula 4.9283P+0.217₂；

When pressure P is 1.00~1.20, vapour density ρ is calculated using formula 4.9008P+0.2465₂；

When pressure P is 2.00~2.60, vapour density ρ is calculated using formula 4.9262P+0.199₂；

In formula, P is absolute pressure value, and unit is Mpa；Vapour density ρ₂Unit be kg/m³；

The superheated steam compensatory approach, real-time steam density p is calculated using following formula (2)₂, i.e.,：

${\mathrm{\ρ}}_2=\frac{1.04}{0.0004795\·\frac{T}{P}-\frac{1.45}{{\left(\frac{T}{100}\right)}^{3.1}}-557800\·\frac{P^2}{{\left(\frac{T}{100}\right)}^{13.5}}}---\left(2\right)$

In formula, T is temperature, and unit is K；P is absolute pressure value, and unit is Mpa；

Then, steam-flow meter value is calculated using following formula (1),

$M=M_{\max }\×\frac{I-4}{16}\×\sqrt{\frac{{\mathrm{\ρ}}_2}{{\mathrm{\ρ}}_1}}---\left(1\right)$

In formula：M is the flow after compensation, units/kg/h；M_maxFor the engineering value of full scale flow, unit:kg/h；For the percentage of the flow before compensation, wherein, I is that the flow signal current value that differential pressure transmitter is exported, i.e. differential pressure transmitter set evolution, and unit is mA；ρ₁·ρ₂The respectively design load and operation state values of density, unit is kg/m³；

Also, it is above-mentioned judge and calculating process be real-time continuous judge and calculate, signal input flow rate integrating instrument, computer or arithmetic processor that temperature sensor and humidity sensor are exported in real time are judged and calculated.