RU2535232C2 - Apparatus for determining dryness factor of wet steam - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: apparatus for determining the dryness factor of wet steam comprises a pressure meter for measuring pressure in the analysed stream of steam, a unit for collecting a steam sample from the analysed stream, a line with a throttling device from the steam sample collection unit to a flow chamber, a flow chamber with a pressure meter and a temperature meter. The apparatus also includes a second flow chamber with a pressure meter and a temperature meter, the flow chamber being connected to the output of the first chamber, an output line from the second chamber with a device for measuring the flow parameter, pressure and temperature, and a computer whose inputs are connected to the outputs of all measuring devices. The apparatus also includes a vessel which is linked to the analysed stream of steam by a steam supply line and a line for outlet of a mixture of steam and steam condensate. Both flow chambers are placed in the vessel. The apparatus further includes a steam generator, as well as a vessel which is linked to steam generator by a steam supply line and a line for outlet of a mixture of steam and steam condensate. Both flow chambers are placed in the vessel.

EFFECT: design of an apparatus which does not exert hydraulic resistance on the analysed stream, enabling assembly, adjustment, connection or disconnection, as well as dismantling without stopping steam supply and without changing the operating mode thereof, enabling design of a mobile version of the apparatus for determining the dryness factor of wet steam.

2 cl, 2 dwg

Description

FIELD OF THE INVENTION

The invention relates to technical physics, and in particular to the field of determining the degree of dryness and other thermodynamic parameters of wet steam, and can be used to determine the degree of dryness both at production facilities and at saturated and wet steam consumption facilities.

State of the art

An analogue of the invention is a device comprising: a pressure meter in a controlled steam stream, a steam sampling unit from a controlled stream, a sample heater until its liquid phase completely evaporates, a second heater for overheating a heated (until its liquid phase completely evaporates) steam sample, an overheated condensation unit samples a temperature and energy meter for heating to complete evaporation of the liquid phase, temperature and energy meters for overheating, a computer to the inputs of which the outputs of all meters are connected [RF patent No. 172705, Method for determining the degree of dryness of wet water vapor].

With the essential features of the invention, the following set of features of the analogue coincides: "a pressure meter in a controlled steam stream, a site for sampling steam from a controlled stream."

The disadvantages of the analogue are:

a) the use of an energy meter for heating a sample of wet steam until the complete evaporation of its liquid phase;

b) the use of an energy meter for overheating a sample of wet steam, heated to complete evaporation of its liquid phase;

c) the use of a superheated steam sample condenser.

SUMMARY OF THE INVENTION

The problem to which the invention is directed, is: a device for determining the degree of dryness of wet steam.

When carrying out the invention, the following technical result can be obtained:

a) the device does not provide hydraulic resistance to the controlled flow;

b) the ability to install, configure, enable or disable, as well as dismantle without stopping the steam line and without changing the mode of its operation;

c) it is possible to create a mobile version of the installation to determine the degree of dryness of wet steam.

The specified technical result is achieved by the fact that a device for determining the degree of dryness of wet steam, comprising: a pressure meter in a controlled steam stream; a unit for sampling steam from a controlled stream; a line with a throttling device from the steam sampling unit to the flow chamber; flow chamber with pressure meter and temperature meter; a second flow chamber with a pressure meter and a temperature meter connected to the output of the first chamber; the line of exit from the second chamber with a meter flow rate, pressure and temperature; a calculator, to the inputs of which the outputs of all meters are connected; characterized in that it contains: a vessel connected to a controlled steam stream by a steam supply line and a steam mixture discharge line with its condensate; both flow chambers are placed in a vessel;

steam generator; as well as a vessel connected to the steam generator with a steam supply line and a steam mixture discharge line with its condensate; both flow chambers are placed in a vessel.

Signs that distinguish from the closest analogue are expressed by the following set of signs:

according to paragraph 1 "contains: a vessel connected to a controlled steam stream by a steam supply line and a steam mixture discharge line with its condensate; both flow chambers are placed in a vessel ";

according to paragraph 2 "contains: a steam generator; as well as a vessel connected to the steam generator with a steam supply line and a steam mixture discharge line with its condensate; both flow chambers are placed in a vessel. "

Thus, the objective of the invention is solved.

List of drawings

Fig. 1. The scheme of the device for determining the degree of dryness of wet steam (according to paragraph 1).

Fig. 2. The scheme of the device for determining the degree of dryness of wet steam (according to paragraph 2).

Information confirming the possibility of carrying out the invention

In Fig. 1. and Fig. 2 shows diagrams of two variants of a device for determining the degree of dryness of wet steam. This device contains:

- steam line 1 with pressure sensor 2;

- a site for sampling steam 16 with a throttle 9 in the sampling line;

- chamber 10 with pressure gauges 3 and temperature 4;

- camera 11 with pressure gauges 12 and temperature 14;

- a meter for the flow parameter of a sampled steam 7 with a pressure meter 6 and a temperature meter 5;

- valve 8 for regulating the flow rate of the sample taken;

- calculator 15 with connected outputs of all meters;

under item 1:

- a vessel 17 with a chamber 10 and a chamber 11 connected to a controlled steam stream, a steam supply line 18 and a steam mixture discharge line with its condensate 19;

under item 2:

- a steam generator 20, for example, with an electric heater 21, with a node for supplying electrical energy 22; equipped with a typical system of control, protection, interlocks and regulation of parameters, in particular steam pressure;

- a vessel 17 with a chamber 10 and a chamber 11 connected to a steam generator, a steam supply line 18 and a steam mixture discharge line with its condensate 19.

The need for a variant of the device according to paragraph 2 arises, for example, when it is used to control the degree of dryness in steam pipelines with relatively low pressure. When the temperature of the saturating vapors in the steam line does not differ significantly from the boiling point in the chamber 10. In this case, any mobile steam generator unit producing high-pressure saturated steam and having a power sufficient to overheat the sampled steam can be used as a steam source. The variant of the device according to paragraph 2 can also be recommended for creating a mobile unit for periodically monitoring the degree of dryness in sections of steam pipelines equipped with steam sampling units.

The operation of the device is as follows.

The initial state of the variant according to paragraph 1: the device is connected to the steam line 1; steam supply lines 18 and a steam mixture discharge line with its condensate 19 are open; the cavity of the vessel 17 and the chambers 10 and 11 located in it are sufficiently warmed up, the temperature in the chambers corresponds to the temperature of the saturating vapors in the controlled flow.

The initial state of the variant according to paragraph 2: the device is connected to the steam line 1 and the steam generator 20. The steam supply lines 18 and the steam mixture withdrawal line with its condensate 19 are open; the cavity of the vessel 17 and the chambers 10 and 11 located therein are sufficiently warmed up, the temperature in the chambers corresponds to the temperature of the saturating steam generated by the steam generator 20. The steam generator stabilizes the pressure of the generated bunk at a predetermined value, for example 12.0 MPa.

The control valve 8 sets the flow rate of the sample being taken, at which the temperature of the steam is set in the chamber 10, which is slightly higher than the temperature of the saturating vapors. Then produce a small increase in consumption. The correspondence of the temperature in the chamber 10 to the temperature of the vapors saturating it is controlled. When this condition is met, a complete evaporation of the liquid phase occurs in chamber 10. That is, in the chamber 10 saturated steam.

Saturated steam from the chamber 10 enters the chamber 11, where it overheats substantially.

From the chamber 11, an overheated sample of steam enters the line with measuring instruments for temperature 5, pressure 6 and flow rate 7.

During the experiment, the following values of the measured parameters were recorded:

- Pressure in the steam line (P _steam = 12.4 MPa);

- The pressure in the chamber 10 (P ₁₀ = 1.4 MPa);

- The temperature in the chamber 10 (t ₁₀ = 200 ° C);

- The pressure in the chamber 11 (P ₁₁ = 1.35 MPa);

- Temperature in chamber 11 (t ₁₁ = 290 ° C);

- Consumption in the flow line of the steam sample (G ₇ = 0.06 kg / s).

The flow rate in the sampling line was established with the condition that saturated chamber (or slightly superheated steam) was in chamber 10.

In the chamber 11, substantially superheated steam will be obtained.

The chambers 10 and 11 are identical, the external conditions for these chambers are identical, equal masses of the sample taken of wet steam pass through the chambers.

In the chamber 10, the evaporation processes; at the inlet - two phases (wet steam) - at the outlet one phase [saturated steam (or slightly superheated steam)].

Overheating in chamber 11 is a single-phase flow at the inlet and outlet.

From the steam pipe into the chamber 10 comes wet steam:

G _samples = G '' + G '= 0.06 kg / s,

where G _samples - the flow rate of the sample of wet steam from the steam line into the chamber 10;

G '' is the flow rate of the vapor phase in the sample taken of wet steam;

G 'is the flow rate of the liquid phase in the selected sample of wet steam.

Saturated steam enters from chamber 10 into chamber 11:

G _n = 0.06 kg / s,

where G _n is the flow rate of saturated steam from chamber 10 to chamber 11.

Superheated steam comes from the chamber 11 into the line of the flow assembly:

G _n = 0.06 kg / s,

where G _n is the flow rate of superheated steam from the chamber 11 to the flow control unit.

The difference in heat fluxes at the outlet and inlet of the chamber 11 determines the heat flux into the steam sample entering through the walls of the chamber 11 from the heating medium into which the chambers are placed.

Q ₁₁ = G _n · i _n -G _n · i _n = 0.06 · (719.5-668.4) = 3.066 kcal / s,

where Q ₁₁ is the heat flux from the heating medium into the chamber 11;

i _n is the enthalpy of saturated vapor from chamber 10;

i _n is the enthalpy of superheated steam from chamber 11.

The heat flux from the heating medium to the chamber 10 (Q ₁₀ ) is slightly larger than the heat flow from the heating medium to the chamber 11 (Q ₁₁ ) mainly due to different temperature differences inside the chambers and the heating medium in the cavity of the vessel 17.

This stems from the identity of the material and the geometry of the chambers, from the identity of external conditions (for example, the temperature of wet steam in the steam line corresponds to the pressure until it is completely condensed), and also because the temperature of saturated steam in chamber 10 is lower than the temperature of superheated steam in chamber 11.

That is: Q ₁₀ = k · Q ₁₁ = 1.2042 * 3.066 = 3.692 kcal / s,

where k is the coefficient of correspondence of heat fluxes Q ₁₀ and Q ₁₁ .

This coefficient can be determined from the following equation:

$$k=\eta \cdot \sqrt{\frac{t_{\mathrm{eleven}}}{{\mathrm{<figure-callout\; id="10"\; label="t"\; filenames="00000005.png"\; state="\{\{state\}\}">t</figure-callout>}}_{10}}}=\mathrm{1,0}\cdot \sqrt{\frac{290.0}{\mathrm{200,0}}}=\mathrm{1,2042,}$$

where η is the experimentally determined correction. In the calculation, η = 1.0.

Heat flow with a sample of wet steam from the steam line to the chamber 10

Q _samples = G _n · i _n -Q ₁₀ = 0.06 · 668.4-3.692 = 36.412 kcal / s;

where Q is the _sample heat flow with a sample of wet steam from the steam line to the chamber 10. The consumption of the vapor phase in the sample taken from the steam line:

$$G^{\text{'}\text{'}\text{'}\text{'}}=\frac{Q_{PR\mathrm{about}bs}-G_{PR\mathrm{about}bs}\cdot i^{\text{'}\text{'}}}{\left(i^{\text{'}\text{'}\text{'}\text{'}}-i^{\text{'}\text{'}}\right)}=\left(\mathrm{36,412}-0.06\cdot 348.4\right)/\left(648.7-348.4\right)=\mathrm{15,508}/\mathrm{300,3}=\mathrm{0,0516}\mathrm{to}g/\mathrm{from},$$

where i '' is the vapor phase enthalpy in a controlled stream of wet steam;

i 'is the enthalpy of the liquid phase in a controlled stream of wet steam.

Dryness (X) of wet steam in the steam line:

$$X=\frac{G^{\text{'}\text{'}\text{'}\text{'}}}{G_{PR\mathrm{about}bs}}\mathrm{0,0516}/0.06=\mathrm{0.86.}$$

Claims (2)

1. A device for determining the degree of dryness of wet steam, comprising: a pressure meter in a controlled steam stream; a unit for sampling steam from a controlled stream; a line with a throttling device from the steam sampling unit to the flow chamber; flow chamber with pressure meter and temperature meter; a second flow chamber with a pressure meter and a temperature meter connected to the output of the first chamber; the line of exit from the second chamber with a meter flow rate, pressure and temperature; a calculator, to the inputs of which the outputs of all meters are connected; characterized in that it comprises: a vessel connected to a controlled steam stream by a steam supply line and a steam mixture discharge line with its condensate; both flow chambers are placed in a vessel. 2. The device according to claim 1, characterized in that it contains: a steam generator; as well as a vessel connected to the steam generator with a steam supply line and a steam mixture discharge line with its condensate; both flow chambers are placed in a vessel.

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