SU890088A1 - Humid vapour enthalpy determination method - Google Patents

Description

one

The invention relates to the field. measurements of physical quantities, and more specifically to methods for determining the enthalpy of wet steam, and can be used in various fields of technology, in particular in power engineering.

There is a known method for determining the enthalpy of wet steam, based on the transfer of wet steam to superheated by adiabatic throttling 11J.

This method is practically not applicable. To determine the enthalpy of low-pressure wet steam, for example, on the exhaust of condensation turbines, since adiabatic throttling of this steam to convert it to superheated, the final vapor pressure is of the order of 0.0001 kgf / cm, i.e. very deep vacu l.

The closest technical solution to the invention is to determine the determination of wet steam injection, which means that a superheated steam flow is introduced into the wet steam stream and mixed with it until the temperature of the mixture is higher than the saturation temperature and the mixture Calculate the enthalpy of wet steam 2.

The disadvantages of the described method are the low accuracy of determination of the enthalpy of wet steam due to errors associated with the need to measure the flow rate of the superheated steam and mixture introduced, as well as the difficulty of automation

10 process definitions entgshpi.

The aim of the invention is to improve the accuracy of determining the enthalpy of wet steam.

This goal is achieved by

15 that, according to the method for determining the enthalpy of wet steam, the principle is that a stream of superheated steam is introduced into the wet steam stream and mixed with it until the temperature of the mixture is above the Saturation temperature and the enthalpy of the wet steam is calculated taking into account the temperatures and pressures of the superheated steam and the mixture in the resulting mixture

25 are additionally introduced and superheated is mixed with it; steam in quantity and with temperature equal to the quantity and temperature of superheated steam during the first mixing is measured

30 temperature after the second mixing, which is the basis for calculating the enthalpy of wet steam.

The method is carried out as follows.

CMeimiBajo and with it a stream of superheated steam in an amount necessary to obtain a mixture with a temperature above the saturation temperature are injected into the pipeline through which wet steam flows. A second stream of superheated steam is introduced into the mixture and mixed with it with a flow rate and a temperature equal to the flow rate and temperature of the superheated steam during the first mixing. The temperature of the superheated steam introduced is measured; the temperature of the mixture after the first and second mixing, the pressure of the superheated steam and the mixture. According to the values of the enthalpy of superheated steam, determined by pressure and temperature using water vapor, we calculate the enthalpy of wet vapor and vapor iy using the heat balance formula

i i /. 2m

G “Od5 lit + Iw I -ii,

m

where g "

Where the enthalpy of superheated steam supplied for mixing; respectively, entergshpi

21. superheated steam (mixture) after the first and second mixing;

G, Gy, are the costs of wet and superheated steam supplied for mixing.

The method for determining the enthalpy of wet steam was tested under laboratory conditions. The experiment was carried out to determine the enthalpy of wet steam at the exhaust of the turbine. Parameters of steam in front of the turbine P 12 kgf / cm, to .Entalpi superheated steam io 2820 kda / kg. The pressure of the exhaust wet steam, pa at the exhaust of the turbine P 0.2 kgf / cm

Superheated steam with initial parameters PQ, tg is passed through a heat-insulated choke, throttled to a pressure. PK - 0.2 kgf / s and the load equals two equal flows to the mixer 1 In the mixer, the wet steam is mixed first coming out of the throttles /, and then the resulting mixture is introduced into the second stream of superheated steam, the flow rate of which is equal to the flow rate of the first stream. The flow of superheated steam after the throttles is adjusted so that the temperature of the mixture after the first mixing becomes higher than the saturation temperature at. pressure. P 0.2 kgf / cm (t The vapor pressure in the mixer is measured.

pressure of superheated steam after chokes, temperature of superheated steam after chokes, t. t after the first mix t and after the second mix tj ,. .

From the tables of water vapor, the enthalpies of it are determined by the temperatures and pressures of the superheated steam: behind the choke i, after the first

mix io and after the second mix.

ty, ± 2820 kJ / kg,

t2 72С,

1. 2630 kJ / kg,

t2 108 ° С, ig. 2700 kJ / kg.

The ratio of costs

---- Moist and superheated steam is determined by the formula

2z.5Iii. ± ib-Iri2o, 357

m 1

(2.8 kg of superheated steam after dropping on 1 kg of wet steam).

The required enthalpy of the steam is determined by the formula

i i + (. 2630 + 12§30г2§281 V Ч 2m - 20.357

 2364 kj

kg

The proposed method for determining the enthalpy of wet steam has advantages over the well-known w. For this embodiment, it is necessary to measure only the pressure and temperature of the superheated steam. The cost measurement is eliminated, as a result, the accuracy of enthalpy determination is improved and the automation of the process is facilitated. On the basis of the method, devices can be created, for example, for the continuous automatic determination of the enthalpy of steam at the exhaust of a condensation tube. Their use to optimize the modes of turbine units and rapid testing of turbines provides significant economic efficiency. effect

Claims (2)

Invention Formula The method for determining the enthalpy of wet steam, which consists in introducing and mixing with it a stream of superheated steam to obtain a mixture temperature above the saturation temperature and taking into account the temperatures and pressures of the superheated steam introduced and the mixture calculate by the fact that, in order to improve the accuracy of enthalpy determination, superheated steam is additionally introduced into the resulting mixture and mixed with it in an amount and temperature equal to; the amount and temperature of the superheated inapa during the first ohm mixing, measured 96900886 temperature after second mixing, i. Pavlovsky A.Z. et al., taking into account the device, the en-h is calculated to measure the degree of moisture of the vapor. talpia wet steam. Energy machine building. 1974 Sources and formations 2. Patent CPP, 1 59678:, c. 01 K taken into account during the experiment 17/18, 1978 (prototype).  11, 0.43-44.