CN111007112B - System and method for online measurement of steam humidity based on conductivity method - Google Patents

Abstract

The invention relates to a system and method for on-line measurement of steam humidity based on conductivity method. The water inlet is connected, wherein the system includes a steam sampling system connected with the steam outlet of the steam-water separator, a recirculating water sampling system and a measuring system connected with the recirculating water pipe, and the measuring system includes an electrical conductivity meter and an instrument control terminal connected electrically, The conductivity meter is used to measure the conductivity of the condensed water in the condensed water collection container and the conductivity of the recirculated water in the cooling water collection container, respectively, and the conductivity meter transmits the measured data to The instrument control terminal, the instrument control terminal processes the data to obtain the steam humidity. The invention is simple in principle and convenient in operation, can measure the humidity of high temperature and high pressure steam on-line, and effectively improves the accuracy of steam humidity measurement.

Description

A system and method for online measurement of steam humidity based on conductivity method

technical field

The invention relates to the technical field of steam humidity measurement, in particular to a system and method for on-line measurement of steam humidity based on a conductivity method.

Background technique

The steam humidity at the outlet of the steam generator is a key parameter during the operation of the nuclear power plant, and its size directly affects the safe and efficient operation of the nuclear power system. The steam-water separator can effectively dehumidify the wet saturated steam in the steam generator, which can greatly improve the steam quality of the steam generator outlet. It is the key equipment in the operation of the nuclear power plant.

During the development of the steam-water separator, it is necessary to carry out a verification test for its performance. The steam humidity at the outlet of the steam-water separator is an important indicator for evaluating its performance. Common steam humidity measurement methods include throttling method, heating method, tracer method, etc. Among them, the throttling method test is more convenient and easy to use, but it cannot measure and calculate the heat loss during the throttling process, and the error is large; The heater processing technology is complex, and the heat loss in the heating process cannot be accurately calculated, and the error is large; the tracer method is the mainstream measurement method of steam humidity in nuclear power plants at present, the measurement technology is mature, and the measurement accuracy is high, but it cannot be measured online. Provide real-time and effective steam humidity data for nuclear power plant operation management.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a system and method for measuring steam humidity on-line based on the conductivity method. The present invention is simple in principle, easy to operate, can measure the humidity of high-temperature and high-pressure steam on-line, and effectively improves the accuracy of steam humidity measurement. .

In order to solve the above problems, the present invention provides a system for measuring the humidity of steam on-line based on the conductivity method. The water inlet of the steam generator is connected, and the system includes:

A steam sampling system, which is connected with the steam outlet of the steam-water separator; the steam sampling system includes a steam sampling device, a condensing device and a condensed water collection container connected in sequence through pipelines, and the steam sampling device is connected to the steam outlet of the steam-water separator On the pipeline, the steam separated from the steam-water separator is condensed by the condensation device and becomes condensed water and collected into the condensed water collection container;

A recirculating water sampling system, which is connected to the recirculating water pipe, the recirculating water sampling system includes a recirculating water sampling device, a cooling device and a cooling water collection container connected in sequence through a pipeline, and the recirculating water sampling device is in communication On the recirculating water pipe, the circulating water is collected into the cooling water collection container after being cooled by the cooling device;

A measurement system comprising an electrical conductivity meter and an instrument control terminal that are electrically connected, the conductivity meters are respectively used to measure the conductivity of the condensed water in the condensed water collection container and the recirculated water in the cooling water collection container The conductivity meter transmits the measured data to the instrument control terminal, and the instrument control terminal processes the data to obtain the steam humidity.

Preferably, a first shut-off valve and a first pressure reducing valve are arranged between the steam sampling device and the condensing device in sequence, and a first electric regulating valve and a flowmeter are arranged between the condensing device and the condensed water collection container in sequence. , the lower end of the condensed water collection container is provided with a second electric regulating valve;

A second shut-off valve and a second pressure reducing valve are arranged between the recirculating water sampling device and the cooling device in sequence, and a third electric regulating valve is arranged between the cooling device and the cooling water collection container, and the cooling water is collected A fourth electric regulating valve is also arranged at the lower end of the container;

The instrument control terminal is respectively electrically connected with the first electric regulating valve, the second electric regulating valve, the flow meter, the third electric regulating valve and the fourth electric regulating valve.

Preferably, the flowmeter is a mass flowmeter.

Preferably, the steam sampling device comprises a sampling pipe and a socket socket, the socket socket is coaxially fixed on the sampling pipe, and the socket socket is fixed on the outer wall of the steam outlet pipe of the steam-water separator;

One end of the sampling pipe passes through the pipe wall of the steam outlet pipe and extends into the pipe. In the pipe, the end of the sampling pipe is wedge-shaped; the sampling pipe faces the inflow direction of the steam, and the wedge-shaped end The part is located on the central axis of the steam outlet pipe.

Preferably, an opening is provided on the recirculating water pipe;

The recirculating water sampling device includes a water intake pipe, the water intake pipe is connected to the opening, and the cooling device communicates with the recirculation water pipe through the water intake pipe.

Preferably, the conductivity meter includes a main unit, a first measurement terminal and a second measurement terminal that are electrically connected to the main unit, and the main unit is electrically connected to the instrument control terminal; the first measurement terminal includes a first measurement terminal. A conductance electrode, a first conductance probe, a first temperature sensor and a first data collector, the first conductance electrode is fixed in the condensed water collection container, the first conductance probe is connected to the first conductance The electrodes are fixedly connected, and both the first temperature sensor and the first data collector are electrically connected to the host;

The second measurement end includes a second conductance electrode, a second conductance probe, a second temperature sensor and a second data collector, the second conductance electrode is fixed in the cooling water collection container, and the second conductance electrode is fixed in the cooling water collection container. The conductance probe is fixedly connected to the second conductance electrode, and the second temperature sensor and the second data collector are both electrically connected to the host.

Preferably, the condensing device and the cooling device are both serpentine heat exchangers.

Preferably, the condensed water collection container and the cooling water collection container are both closed metal containers.

Preferably, the condensed water collection container and the cooling water collection container are made of 304 stainless steel.

This embodiment also provides a method for measuring steam humidity on-line based on the conductivity method, using the system described in the above-mentioned embodiment, including the following steps:

Step 1, adding potassium carbonate to the recirculating water before measuring;

Step 2, measure the conductivity of the condensed water of the steam separated by the steam-water separator and the conductivity of the recirculating water respectively by the conductivity meter;

Step 3, the instrument control terminal compares the above two electrical conductivities to obtain the steam humidity.

Preferably, in step 2, after the conductivity meter shows stable, the measured steam humidity at this time is consistent with the steam humidity in the steam outlet pipe of the steam-water separator.

Preferably, in step 1, the relationship between the conductivity and the concentration of the potassium carbonate aqueous solution is obtained by calibration;

In step 3, the steam humidity is obtained by the following formula:

In the formula: M _st : mass flow rate of wet steam, the unit is t/h, measured by the flow meter set in the steam outlet pipe of the steam-water separator, and this flow meter is electrically connected to the instrument control terminal;

M _m : the mass flow rate of water carried by the steam, the unit is t/h, measured by the flow meter in the steam sampling system, and the flow meter is electrically connected to the instrument control terminal;

S _fw : the concentration of the wet steam tracer element, the unit is mg/kg, the conductivity is obtained by the conductivity meter, and this concentration is obtained according to the relationship curve of the conductivity and the concentration;

S _c : the concentration of the recirculating water tracer element, the unit is mg/kg, the conductivity is obtained by the conductivity meter, and the concentration is obtained according to the relationship curve of the conductivity and the concentration;

ω: Steam humidity, %.

Compared with the prior art, the present invention has the following technical effects:

1. The present invention is suitable for high-temperature and high-pressure steam humidity measurement places, and can realize real-time online measurement of steam humidity, and the measurement principle is simple, the device processing technology is easy to implement, and the measurement accuracy is high. The invention is simple in principle and convenient in operation, can measure the humidity of high-temperature and high-pressure steam on-line, and effectively improves the real-time performance and accuracy of steam humidity measurement.

2. The present invention designs a steam sampling device, which can ensure that the sampling pipe is always in an upstream state, and the isokinetic sampling of steam is ensured by the mass conservation method.

Of course, it is not necessary for any product embodying the present invention to achieve all of the above-described advantages simultaneously.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained from these drawings without any creative effort. In the attached picture:

1 is a schematic structural diagram of a system for on-line measurement of steam humidity based on a conductivity method provided by a preferred embodiment of the present invention;

FIG. 2 is a schematic diagram of the installation structure of the steam sampling device provided by the preferred embodiment of the present invention.

Detailed ways

A system for online measurement of steam humidity based on conductivity method provided by the present invention will be described in detail below with reference to FIGS. 1 to 2 . This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed Embodiments and specific operation process, but the protection scope of the present invention is not limited to the following examples, those skilled in the art can modify and modify it within the scope of not changing the spirit and content of the present invention.

The steam outlet of the steam generator is connected with the steam inlet of the steam-water separator through pipes. In the steam-water separator, the steam-water separator will separate clean steam and condensed water for reuse. Therefore, this condensed water is also called circulating water, which passes through the circulating water outlet of the steam-water separator (also called the circulating water outlet). In the present invention, the circulating water outlet of the steam-water separator is connected with the water inlet of the steam generator through a recirculating water pipe.

Please refer to FIG. 1 , the present invention provides a system for measuring steam humidity on-line based on conductivity method, the system includes:

A steam sampling system 1, which is connected to the steam outlet of the steam-water separator; the steam sampling system 1 includes a steam sampling device 11, a condensing device 14 and a condensed water collection container 17 connected in sequence through pipelines, and the steam sampling device 11 is used for Take the steam separated by the steam-water separator, that is, the steam sampling device 11 is connected to the steam outlet pipeline of the steam-water separator, and the steam is condensed by the condensation device 14 and becomes condensed water and is collected to the condensed water collection. in container 17;

Recirculating water sampling system 2, which is connected with the recirculating water pipe, the recirculating water sampling system 2 includes a recirculating water sampling device 21, a cooling device 24 and a cooling water collection container 26 which are connected in sequence through pipelines. The circulating water sampling device 21 is used to obtain the circulating water separated by the steam-water separator, that is, the circulating water sampling device 21 is connected to the recirculating water pipe, and the circulating water is cooled by the cooling device 24 and collected to the in the cooling water collection container 26;

A measurement system 3, which includes a conductivity meter 31 and an instrument control terminal 32 that are electrically connected, the conductivity meter 31 is respectively used to measure the conductivity of the condensed water in the condensed water collection container 17 and the cooling water collection container The conductivity of the recirculating water in 26, the conductivity meter 31 transmits the measured data to the instrument control terminal 32, which processes the data to obtain steam humidity.

Further, a first flow meter is provided in the steam outlet pipeline of the steam-water separator, a first stop valve 12 and a first pressure reducing valve 13 are arranged between the steam sampling device 11 and the condensing device 14 in sequence, and the condensing device A first electric regulating valve 15 and a second flow meter 16 are arranged between 14 and the condensate collecting container 17 in sequence, and a second electric regulating valve 18 is also arranged at the lower end of the condensing water collecting container 17;

A second shut-off valve 22 and a second pressure reducing valve 23 are arranged between the recirculating water sampling device 21 and the cooling device 24 in sequence, and a third electric regulating valve is arranged between the cooling device 24 and the cooling water collection container 26 25, the lower end of the cooling water collection container 26 is also provided with a fourth electric regulating valve;

The instrument control terminal 32 is respectively electrically connected with the first electric regulating valve 15 , the second electric regulating valve 18 , the second flow meter 16 , the third electric regulating valve 25 and the fourth electric regulating valve 27 .

The first pressure reducing valve 13 can reduce the pressure in the system to the working pressure of the condensing device 14 , and the second pressure reducing valve 23 can reduce the pressure in the system to the working pressure of the cooling device 24 .

Both the condensing device 14 and the cooling device 24 are serpentine heat exchangers.

The condensed water collection container 17 and the cooling water collection container 26 are both closed metal containers, preferably made of 304 stainless steel, which can effectively isolate the air and eliminate the influence of air on the electrical conductivity of the condensed water and cooling water.

The first flowmeter and the second flowmeter 16 described above are preferably mass flowmeters, and it is judged whether the steam sampling has reached the constant velocity sampling according to the indication of the flowmeters.

The instrument control terminal 32 includes a control processing unit and a display unit, such as a computer.

Please refer to FIG. 2 , the steam sampling device 11 includes a sampling pipe 111 and a nozzle socket 112 , the nozzle socket 112 is coaxially fixed on the sampling pipe 111 , and the nozzle socket 112 is fixed on the steam-water separator. On the outer wall of the steam outlet pipe 4;

One end of the sampling pipe 111 passes through the pipe wall of the steam outlet pipe 4 and extends into the pipe. In the pipe, the end of the sampling pipe 111 is wedge-shaped; the sampling pipe 111 faces the inflow direction of the steam , and the wedge-shaped end is located on the central axis of the steam outlet pipe 4. Through the above structure, the influence of the sampling pipe 111 on the flow field in the steam pipe can be minimized, and the steam flowing in the pipe can enter the sampling pipe 111 horizontally, without any Collision with the inner wall of the pipe. The other end of the sampling pipe 111 is connected to the condensing device 14 through a pipeline, and the first stop valve 12 and the first pressure reducing valve 13 are arranged on this pipeline.

In this embodiment, the steam sampling device 11 is preferably a detachable structure.

In this embodiment, an opening is set on the recirculating water pipe, and the opening is opened on the pipe wall of the recirculating water pipe; the recirculating water sampling device includes a water intake pipe, and the water intake pipe is coaxially fixed on the pipe wall. In a pipe sleeve, the outer pipe wall of the pipe sleeve is sealedly connected with the inner side of the opening to prevent water leakage; the cooling device 24 is communicated with the recirculating water pipe through the water intake pipe.

In this embodiment, the conductivity meter 31 is a multi-range instrument, and the conductivity meter 31 includes a host and a first and second measuring ends that are electrically connected to the host. The host and the instrument control terminal 32 Electrical connection; the first measurement end includes a first conductivity electrode, a first conductivity probe, a first temperature sensor and a first data collector, and the first conductivity electrode is fixed in the condensed water collection container 17 , the first conductivity probe is fixedly connected to the first conductivity electrode, and the first temperature sensor and the first data collector are both electrically connected to the host;

The second measurement end includes a second conductance electrode, a second conductance probe, a second temperature sensor and a second data collector, the second conductance electrode is fixed in the cooling water collection container 26, and the first Two conductance probes are fixedly connected to the second conductance electrode, and both the second temperature sensor and the second data collector are electrically connected to the host.

The purpose of the temperature sensor is to enable temperature compensation of the conductivity of the solution. The size of the conductivity is closely related to the dissociation degree of the electrolyte in water and the migration speed of the ions, and the dissociation degree and the migration speed are related to the temperature of the solution. As the temperature increases, the conductivity of the solution increases, and vice versa, the conductivity decreases. In order to overcome the influence of temperature and make the conductivity of different solutions comparable at different temperatures, it is recognized that 25 °C is used as the reference temperature when measuring the conductivity. When the solution temperature is not 25 °C, temperature compensation is performed to compensate to Conductivity at 25°C.

The measurement principle of this system is as follows:

The conductivity of the potassium carbonate aqueous solution has a certain proportional relationship with the concentration of potassium carbonate in the solution. The relationship between the conductivity and the concentration can be obtained by calibration. In addition, in an ideal state, pure water is pure water after condensation of pure steam, and the conductivity is almost is zero, but under actual working conditions, the steam will carry a certain amount of droplets containing conductive substances and flow downstream, so that the condensed water formed after the steam condenses has a certain conductivity. Therefore, a certain mass of potassium carbonate is added to the recirculating water before the measurement, the concentration S _c of potassium carbonate in the recirculating water is obtained by calculation, and then the concentration S _fw of potassium carbonate in the wet steam is obtained by measuring the conductivity of the condensed water of the sampled steam, The steam humidity is obtained by:

In the formula: M _st : wet steam mass flow, the unit is t/h, measured by the first flow meter arranged in the steam outlet pipeline of the steam-water separator, and this first flow meter is electrically connected with the instrument control terminal 32;

M _m : the mass flow rate of water carried by the steam, in units of t/h, measured by the second flow meter in the steam sampling system 1, and this second flow meter is electrically connected to the instrument control terminal 32;

S _fw : the concentration of the wet steam tracer element, the unit is mg/kg, the conductivity is obtained by the conductivity meter 31, and this concentration is obtained according to the relationship curve of the conductivity and the concentration;

S _c : the concentration of the recirculating water tracer element, the unit is mg/kg, the conductivity is obtained by the conductivity meter 31, and this concentration is obtained according to the relationship curve of the conductivity and the concentration;

ω: Steam humidity, %.

A method for measuring steam humidity on-line based on conductivity method, this method uses the above-mentioned system, and includes the following steps:

Step 1, obtain the relational formula between the conductivity of the potassium carbonate aqueous solution and the mass concentration by calibration;

Step 2, adding a certain quality of potassium carbonate in the recirculating water, the potassium carbonate concentration in the water is controlled at the allowable value;

Step 3, adjust the first shut-off valve 12 and the second pressure reducing valve 23, and adjust the inlet pressure of the condensing device 14 to the working pressure of the condensing device 14;

Adjust the condensed water flow of the condensing device 14 to ensure that all the steam entering the steam sampling system 1 is condensed to a condensed water close to normal temperature;

Adjust the first electric control valve 15 and the second electric control valve 18 by observing the indication of the second flow meter 16 to ensure that the steam flow rate in the sampling pipe 111 for taking steam is consistent with the steam flow rate in the steam outlet pipe of the steam-water separator. The liquid level in the condensate collection container 17 is stable and submerges the first conductivity electrode;

Adjust the second shut-off valve 22 and the second pressure reducing valve 23, and adjust the inlet pressure of the cooling device 24 to the working pressure of the cooling device 24;

Adjust the cooling water flow of the cooling device 24 to ensure that all the recirculating water entering the recirculating water sampling system 2 is cooled to water close to normal temperature;

Adjust the third electric control valve 25 and the fourth electric control valve 27 to ensure that the recirculated water slowly flows into the cooling water collection container 26, and the liquid level is stable and submerged the second conductivity electrode;

Step 4, after the conductivity meter 31 shows stable, the water replacement in the condensed water collection container 17 and the cooling water collection container 26 is completed, and the measured steam humidity at this time is consistent with the steam humidity in the main steam pipeline;

In step 5, the instrument control terminal 32 processes the electrical conductivity of the steam condensed water and the recirculating water measured by the electrical conductivity meter 31 to obtain the steam humidity ω.

In the formula: M _st : the mass flow rate of wet steam, the unit is t/h, measured by the first flow meter arranged in the steam outlet pipeline of the steam-water separator, and the first flow meter is electrically connected with the instrument control terminal 32;

M _m : the mass flow rate of water carried by the steam, in units of t/h, measured by the second flow meter 16 in the steam sampling system 1, and this second flow meter 16 is electrically connected with the instrument control terminal 32;

S _fw : the concentration of the wet steam tracer element, the unit is mg/kg, the conductivity is obtained by the conductivity meter 31, and this concentration is obtained according to the relationship curve of the conductivity and the concentration;

S _c : the concentration of the recirculating water tracer element, the unit is mg/kg, the conductivity is obtained by the conductivity meter 31, and this concentration is obtained according to the relationship curve of the conductivity and the concentration;

ω: Steam humidity, %.

The above disclosure is only a specific embodiment of the present application, but the present application is not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present application.

Claims (12)

1. A system for online measurement of steam humidity based on conductivity method, the steam outlet of the steam generator is connected with the steam inlet of the steam-water separator, and the circulating water outlet of the steam-water separator is connected with the water inlet of the steam generator through a recirculating water pipe , characterized in that the system includes: A steam sampling system, which is connected with the steam outlet of the steam-water separator; the steam sampling system includes a steam sampling device, a condensing device and a condensed water collection container connected in sequence through pipelines, and the steam sampling device is connected to the steam outlet of the steam-water separator On the pipeline, the steam separated from the steam-water separator is condensed by the condensation device and becomes condensed water and collected into the condensed water collection container; A recirculating water sampling system, which is connected to the recirculating water pipe, the recirculating water sampling system includes a recirculating water sampling device, a cooling device and a cooling water collection container connected in sequence through a pipeline, and the recirculating water sampling device is in communication On the recirculating water pipe, the circulating water is collected into the cooling water collection container after being cooled by the cooling device; A measurement system comprising an electrical conductivity meter and an instrument control terminal that are electrically connected, the conductivity meters are respectively used to measure the conductivity of the condensed water in the condensed water collection container and the recirculated water in the cooling water collection container The conductivity meter transmits the measured data to the instrument control terminal, and the instrument control terminal processes the data to obtain the steam humidity. 2. a kind of system of measuring steam humidity on-line based on conductivity method as claimed in claim 1, is characterized in that, between described steam sampling device and condensation device, be provided with first stop valve and first pressure reducing valve successively A first electric regulating valve and a flow meter are arranged between the condensing device and the condensed water collection container in sequence, and a second electric regulating valve is arranged at the lower end of the condensed water collection container; A second shut-off valve and a second pressure reducing valve are arranged between the recirculating water sampling device and the cooling device in sequence, and a third electric regulating valve is arranged between the cooling device and the cooling water collection container, and the cooling water is collected A fourth electric regulating valve is also arranged at the lower end of the container; The instrument control terminal is respectively electrically connected with the first electric regulating valve, the second electric regulating valve, the flow meter, the third electric regulating valve and the fourth electric regulating valve. 3 . The system for measuring steam humidity on-line based on the conductivity method according to claim 2 , wherein the flow meter is a mass flow meter. 4 . 4. A system for online measurement of steam humidity based on conductivity method according to claim 1, wherein the steam sampling device comprises a sampling pipe and a socket, and the socket is coaxially fixed on the On the sampling pipe, the nozzle socket is fixed on the outer wall of the steam outlet pipe of the steam-water separator; One end of the sampling pipe passes through the pipe wall of the steam outlet pipe and extends into the pipe. In the pipe, the end of the sampling pipe is wedge-shaped; the sampling pipe faces the inflow direction of the steam, and the wedge-shaped end The part is located on the central axis of the steam outlet pipe. 5. The system for measuring steam humidity on-line based on conductivity method as claimed in claim 1, wherein an opening is provided on the recirculating water pipe; The recirculating water sampling device includes a water intake pipe, the water intake pipe is connected to the opening, and the cooling device communicates with the recirculation water pipe through the water intake pipe. 6. a kind of system of measuring steam humidity on-line based on conductivity method as claimed in claim 1, is characterized in that, described conductivity meter comprises host computer and the first way measurement terminal and the second way measurement that are electrically connected with host computer The host is electrically connected to the instrument control terminal; the first measurement terminal includes a first conductance electrode, a first conductance probe, a first temperature sensor and a first data collector, the first conductance electrode is fixed in the condensed water collection container, the first conductivity probe is fixedly connected to the first conductivity electrode, and the first temperature sensor and the first data collector are both electrically connected to the host; The second measurement end includes a second conductance electrode, a second conductance probe, a second temperature sensor and a second data collector, the second conductance electrode is fixed in the cooling water collection container, and the second conductance electrode is fixed in the cooling water collection container. The conductance probe is fixedly connected to the second conductance electrode, and the second temperature sensor and the second data collector are both electrically connected to the host. 7 . The system for measuring steam humidity on-line based on the conductivity method according to claim 1 , wherein the condensing device and the cooling device are both serpentine heat exchangers. 8 . 8 . The system for on-line measurement of steam humidity based on the conductivity method according to claim 1 , wherein the condensed water collection container and the cooling water collection container are both sealed metal containers. 9 . 9 . The system for measuring steam humidity on-line based on the conductivity method according to claim 8 , wherein the condensed water collecting container and the cooling water collecting container are made of 304 stainless steel. 10 . 10. A method for measuring steam humidity on-line based on conductivity method, using the system as claimed in claim 1, characterized in that, comprising the following steps: Step 1, adding potassium carbonate to the recirculating water before measuring; Step 2, measure the conductivity of the condensed water of the steam separated by the steam-water separator and the conductivity of the recirculating water respectively by a conductivity meter; Step 3, the instrument control terminal compares the above two electrical conductivities to obtain the steam humidity. 11. The method for online measurement of steam humidity based on conductivity method as claimed in claim 10, characterized in that, in step 2, after the conductivity meter is stable, the steam humidity measured at this time is the same as the The steam humidity in the steam outlet pipe of the steam-water separator is consistent. 12. a kind of method for on-line measurement of steam humidity based on conductivity method as claimed in claim 11, is characterized in that, in step 1, obtains the relation curve of conductivity and the concentration of potassium carbonate aqueous solution by calibration; In step 3, the steam humidity is obtained by the following formula:

In the formula: M _st : mass flow rate of wet steam, the unit is t/h, measured by the flow meter set in the steam outlet pipeline of the steam-water separator, and this flow meter is electrically connected to the instrument control terminal; M _m : the mass flow rate of water carried by the steam, the unit is t/h, measured by the flow meter in the steam sampling system, and the flow meter is electrically connected to the instrument control terminal; S _fw : the concentration of the wet steam tracer element, the unit is mg/kg, the conductivity is obtained by the conductivity meter, and this concentration is obtained according to the relationship curve of the conductivity and the concentration; S _c : the concentration of the recirculating water tracer element, the unit is mg/kg, the conductivity is obtained by the conductivity meter, and the concentration is obtained according to the relationship curve of the conductivity and the concentration; ω: Steam humidity, %.

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