CN109459533B - Steam humidity measuring device and method thereof - Google Patents
Steam humidity measuring device and method thereof Download PDFInfo
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- CN109459533B CN109459533B CN201811395249.1A CN201811395249A CN109459533B CN 109459533 B CN109459533 B CN 109459533B CN 201811395249 A CN201811395249 A CN 201811395249A CN 109459533 B CN109459533 B CN 109459533B
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- 238000000034 method Methods 0.000 title claims abstract description 36
- 238000005070 sampling Methods 0.000 claims abstract description 54
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims abstract description 47
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 43
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 24
- 238000001816 cooling Methods 0.000 claims abstract description 22
- 230000001105 regulatory effect Effects 0.000 claims abstract description 16
- 238000005259 measurement Methods 0.000 claims description 22
- 229920006395 saturated elastomer Polymers 0.000 claims description 15
- 238000012360 testing method Methods 0.000 claims description 15
- 238000007789 sealing Methods 0.000 claims description 12
- 229910001220 stainless steel Inorganic materials 0.000 claims description 4
- 239000010935 stainless steel Substances 0.000 claims description 4
- 238000004364 calculation method Methods 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 230000001681 protective effect Effects 0.000 claims description 3
- 230000008676 import Effects 0.000 claims description 2
- 239000011148 porous material Substances 0.000 abstract description 3
- 238000004321 preservation Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000009413 insulation Methods 0.000 description 3
- 238000005485 electric heating Methods 0.000 description 2
- 230000017525 heat dissipation Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 239000000700 radioactive tracer Substances 0.000 description 2
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 241000406668 Loxodonta cyclotis Species 0.000 description 1
- 206010053615 Thermal burn Diseases 0.000 description 1
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- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
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- 230000007547 defect Effects 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
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- G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
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Abstract
The invention discloses a steam humidity measuring device and a method thereof, wherein the steam humidity measuring device comprises a sampling tube, a measuring tube, a regulating valve, a cooling device and a measuring tank, wherein a platinum resistor is arranged at the inlet of the sampling tube, the outlet of the sampling tube is connected with the inlet of the measuring tube, the outlet of the measuring tube is connected with the cooling device through the regulating valve, a pore plate, a pressure temperature sensor, a heater and a temperature sensor are sequentially arranged in the measuring tube from the inlet to the outlet, the outlet of the cooling device is provided with a three-way valve, two outlets of the three-way valve are respectively connected with a drain pipe and a drip pipe, the measuring tank is positioned below the drip pipe, the bottom of the measuring tank is provided with a water drain valve, and the measuring tank is provided with a force sensor. The invention can measure the steam humidity of the boiler barrel on line, the measuring device is relatively simple, and the whole accuracy is high.
Description
Technical Field
The invention belongs to the technical field of steam humidity measurement, and particularly relates to a steam humidity measurement device and a steam humidity measurement method.
Background
In a steam boiler and a steam heating system, the measurement and control of the steam humidity are significant in guaranteeing the safety and economic operation of equipment and guaranteeing the quality of products.
The existing steam humidity measurement principle and method are more, and the method comprises a chloration method, a throttling method, an optical method, a tracer method, an ultrasonic method, a microwave method, a capacitance method and the like. The chlorine root method is used more at present, but the measurement is complex and the error is larger; the throttling method has simple principle and good reproducibility, but is not accurate; the optical method can be used for online measurement, but has high price, high randomness of measurement results and harsh use conditions; the tracer method is accurate in measurement, but cannot be online, and is high in price and complex in operation; ultrasonic, microwave and capacitance methods are still in research and development stages and are not well suited for steam humidity measurement at higher temperatures.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a steam humidity measuring device and a steam humidity measuring method based on a thermodynamic principle and a mass conservation principle, and the steam humidity measuring device and the steam humidity measuring method can be used for measuring the steam humidity on line.
In order to solve the technical problems, the invention adopts the following technical scheme:
the utility model provides a steam humidity measuring device, includes sampling pipe, survey pipe, governing valve, cooling device, measurement jar, the entrance of sampling pipe is equipped with platinum resistance, the sampling pipe export with survey pipe's access connection, survey pipe's export with cooling device passes through the governing valve and links to each other, be equipped with orifice plate, pressure temperature sensor, heater and temperature sensor in proper order from the import to the export in the survey pipe, cooling device's export is equipped with the three-way valve, drain pipe and drip pipe are connected respectively to two exports of three-way valve, the measurement jar is located the below of drip pipe, the bottom of measurement jar is equipped with the drain valve, be equipped with force transducer under the measurement jar.
Preferably, the device further comprises a humidity display instrument, a controller is arranged in the humidity display instrument, the platinum resistor, the pressure temperature sensor, the regulating valve, the three-way valve, the heater, the water drain valve and the force sensor are all connected with the controller, a display is further arranged on the humidity display instrument, and the display is connected with the controller.
Preferably, the outer wall of the sampling tube is provided with threads, a sealing baffle is arranged at the rear of the threads, and a high-temperature-resistant sealing gasket is arranged in front of the sealing baffle.
Preferably, a groove is formed in the pipe wall at the inlet of the sampling pipe, the platinum resistor is located in the groove, a through-flow cap is further arranged at the inlet of the sampling pipe, and the through-flow cap covers the groove after being screwed.
Preferably, an insulating layer is arranged on the outer side of the measuring tube, and a stainless steel protective tube is arranged outside the insulating layer.
Preferably, two perforated plates are arranged in the measuring tube upstream of the pressure-temperature sensor.
Preferably, the regulating valve and the cooling device are both provided with heat insulation layers.
Preferably, four force sensors are arranged below the metering tank, and the four force sensors are uniformly and symmetrically arranged along the circumference of the bottom surface of the metering tank.
A method for measuring steam humidity, comprising the steps of: (1) Starting a steam humidity measuring device, and measuring the steam temperature t inside the boiler barrel through a platinum resistor 1 Pressure p of steam after flowing through the orifice plate 2 Temperature t 2 After the steam further flows through the heater, the pressure is basically unchanged, p, as measured by the pressure and temperature sensor 3 ≈p 2 Temperature t 3 The steam mass flow m and the steam humidity W can be calculated according to a steady flow energy equation and an energy balance relation by measuring by a temperature sensor; (2) After the steam humidity measuring device works stably for a period of time, the humidity display instrument controls the three-way valve to drain outwards, and the water drain valve also drains outwards; after the metering tank is emptied, the display displays the empty tank quality of the metering tank, then the three-way valve drains downwards, the water drain valve is closed, and the metering tank starts to store water; after water is stored, the steam mass flow m measured by a metering tank zq Instead of the heater measured sampled steam mass flow m.
Preferably, the specific calculation method of the steam mass flow m and the steam humidity W is as follows:
according to the steady flow energy equation, there is the following relationship:
wherein q is heat loss, h 1 Enthalpy of steam at inlet of sampling tube, h 2 To measure the enthalpy of the steam in the tube before the heater c 1 C, for the flow rate of steam at the inlet of the sampling tube 2 To measure the flow rate of steam in front of heater in tube, g is the gravitational constant, z 1 Is the height at the inlet of the sampling tube; z 2 The height in front of the heater in the measurement tube;
c 1 ≈0，q≈0，z 2 ＝z 1 the simplified equation can be obtained:
according to the energy balance relation, the following can be obtained:
N＝f(h 3 -h 2 )m
wherein N is the electrothermal power of the heater, and f is the measurement coefficient; h is a 2 To measure the enthalpy of the steam in the tube before the heater, h 3 The enthalpy of the steam after the heater in the measuring tube is measured, and m is the steam test mass flow of the heater section;
pressure of steam before heater p 2 Temperature t 2 The pressure is basically unchanged after the steam flows through the heater as measured by the pressure and temperature sensor, p 3 ≈p 2 Temperature t 3 As measured by a temperature sensor, according to the pressure p 2 Temperature t 2 Enthalpy h can be found by means of a superheated steam table 2 Density ρ 2 The method comprises the steps of carrying out a first treatment on the surface of the According to pressure p 3 Temperature t 3 Enthalpy h can be found by means of a superheated steam table 3 ；
The initial assignment f=1, the heater segment steam test mass flow m can be found using the following equation:
m can in turn be calculated by the following formula:
the method is obtained by the conversion of the formula:
wherein m is the steam test mass flow of the heater section, d is the inner diameter of the measuring tube, c 2 To measure the flow rate ρ of steam in front of heater in tube 2 To measure the density of the steam in front of the heater in the tube;
platinum resistance measuring temperature t at inlet of sampling tube 1 According to the temperature ordered saturated steam table, the corresponding saturated water enthalpy h' and saturated steam enthalpy h″ can be found. Enthalpy h 1 The expression of (2) is as follows:
h 1 ＝h′W+h″(1-W)
in the formula, h 1 For the enthalpy of the steam at the inlet of the sampling tube, h' is the temperature t at the inlet of the sampling tube 1 Corresponding saturated water enthalpy, h' is the temperature t at the inlet of the sampling tube 1 Corresponding saturated steam enthalpy, wherein W is steam humidity;
when the standard is carried out, the steam mass flow m is accurately measured by the metering tank zq Then the measurement coefficient f=m/m zq =a. The f assignment is changed from 1 to A and m is recalculated.
The beneficial effects of the invention are as follows:
1. the steam humidity of the boiler barrel can be measured on line, the measuring device is relatively simple, and the overall accuracy is high.
2. The range of measurable steam humidity is large, and the steam humidity measurement requirement of higher temperature level can be met.
3. And a high-precision sensor is selected, so that the test links are fewer, and error forming factors are effectively controlled.
4. And the corresponding measuring and calculating data are calibrated by using the high-precision force sensor, and the final result is more accurate.
Drawings
Fig. 1 is a schematic structural view of the present invention.
List of reference numerals:
1-platinum resistance; 2-sampling tube; 3-threading; 4-sealing baffle plates; 5-a pressure temperature sensor; 6-a temperature sensor; 7-an insulating layer; 8-measuring a tube; 9-a regulating valve; 10-a cooling device; 11-a metering tank; 12-a water drain valve; 13-through-flow screw cap; 14-well plates; 15-a heater; 16-a water release button; 17-a water storage button; 18-a three-way valve; 19-a power button; 20-calibrating a button; 21-a humidity display; 22-a display; 23-signal input/output terminals; 24-force sensor.
Detailed Description
The invention is further described with reference to the drawings and detailed description which follow:
as shown in fig. 1, the steam humidity measuring device comprises a sampling tube 2, a measuring tube 8, a regulating valve 9, a cooling device 10 and a metering tank 11, wherein a platinum resistor 1 is arranged at the inlet of the sampling tube 2, the outlet of the sampling tube 2 is connected with the inlet of the measuring tube 8, the outlet of the measuring tube 8 is connected with the cooling device 10 through the regulating valve 9, a pore plate 14, a pressure temperature sensor 5, a heater 15 and a temperature sensor 6 are sequentially arranged from the inlet to the outlet of the measuring tube 8, a three-way valve 18 is arranged at the outlet of the cooling device 10, two outlets of the three-way valve 18 are respectively connected with a drain pipe and a drip pipe, the metering tank 11 is positioned below the drip pipe, a water drain valve 12 is arranged at the bottom of the metering tank 11, and a force sensor 24 is arranged below the metering tank 11.
The steam humidity measuring device further comprises a humidity display instrument 21, a controller is arranged in the humidity display instrument 21, the platinum resistor 1, the pressure temperature sensor 5, the temperature sensor 6, the regulating valve 9, the three-way valve 18, the heater 15, the water drain valve 12 and the force sensor 24 are all connected with the controller, the humidity display instrument 21 is further provided with a display 22, and the display 22 is connected with the controller.
The humidity display 21 in this example is also provided with a water discharge button 16, a water storage button 17, a power button 19, a calibration button 20, and a signal input/output terminal 23. The wetness indicator 21 is used to detect signals, process data, control processes, display measured parameters. Letter (letter)The number input/output terminal 23 receives signals from the platinum resistor 1, the pressure temperature sensor 5, the heater 15, the temperature sensor 6, and the force sensor 24, and outputs signals for controlling the opening and closing of the three-way valve 18 and the drain valve 12. The display 22 is a liquid crystal display screen, and the display 22 displays the humidity W and the temperature t of the steam in the boiler barrel 1 Steam pressure p of heater 15 2 Temperature rise Δt, sampling steam mass flow m, total mass G of metering tank 11.
The outer wall of the sampling tube 2 is provided with threads 3, and the rear of the threads 3 is provided with a sealing baffle 4. The screw thread 3 is used for installing the sampling pipe 2, and in this example the sampling pipe 2 stretches into the drum steam space, and is fixed with the drum through screw thread 3, and sealing baffle 4 is hugged closely the drum outer wall after the sampling pipe 2 is installed, plays sealed effect, in order to strengthen sealed effect, still is equipped with high temperature resistant sealing gasket between drum and the sealing baffle 4.
The pipe wall at the inlet of the sampling pipe 2 is provided with a groove, the platinum resistor 1 is positioned in the groove, the inlet of the sampling pipe 2 is also provided with a through-flow rotary cap 13, and the through-flow rotary cap 13 covers the groove after being screwed. The outer diameter of the sampling tube 2 is unchanged. The platinum resistor 1 is used for measuring the steam temperature in the boiler barrel, in the example, the platinum resistor 1 adopts Shanghai Shuangxu film type platinum resistor, the model MWFT1, the measuring range is-79-400 ℃, and the allowable error is +/-0.3+0.005|DEG C.
The sampling tube 2 is combined with the measuring tube 8 to form an L-shaped test element, the main materials of the sampling tube 2 and the measuring tube 8 are stainless steel, and the rear end of the measuring tube 8 is screwed into the regulating valve 9. The measuring tube 8 is provided with two pore plates 14, a pressure temperature sensor 5, a heater 15 and a temperature sensor 6 from left to right, the measuring tube 8 is L-shaped, and the rear part is turned by 90 degrees; the orifice plate 14 serves to enhance the throttling effect; the heat preservation layer 7 is coated outside the measuring tube 8, the material is superfine glass fiber, and the highest use temperature is 450 ℃; the heat preservation layer 7 is provided with a stainless steel protective tube.
In the example, the pressure temperature sensor 5 selects mountain elephant PT131, the pressure range is 0-1 MPa-200 MPa, the temperature range is 0 ～ 200 ～ 400 ℃, and the precision is 0.35 level; the temperature sensor 6 adopts armored platinum resistor produced by Shanghai automation instrument three factories, model WZPK2-265SA, measuring range-200-500 ℃, allowable error + -0.15+0.002|t|DEG C. The electrothermal power of the heater 15 is measured by using a DP3-W200 digital display power meter manufactured by Sanyou Automation instruments, inc., the measuring range is 0-200W, and the measuring error is +/-0.5% FS +/-0.2.
The cooling device 10 adopts a water cooling mode and is responsible for cooling sampled steam into water (the water temperature is controlled to be below 50 ℃, the bottom of the cooling device 10 is provided with a common direct-reading thermometer with the precision of 1.5 level), and the cooling device is connected with the regulating valve 9 and the three-way valve 18; proper heat insulation and scald prevention are required on the surface of the cooling device 10; the regulating valve 9 also needs to be properly insulated. Therefore, the regulating valve 9 and the cooling device 10 are both provided with heat insulation layers.
Four force sensors 24 are arranged below the metering tank 11, and the four force sensors 24 are uniformly and symmetrically arranged along the circumference of the bottom surface of the metering tank 11. According to the time parameter, the measuring tank 11 can accurately measure the mass flow of water, the force sensor 24 used in the example is of a marine product circular plate type, model N10A-50, the weighing range is 0-50 kg, the precision is 0.2 level, and the total mass of the measuring tank 11 is four force algebraic sums; the water fed into the metering tank 11 is cooled by the sampling steam, and the mass flow of the water is the mass flow of the sampling steam. The bottom of the metering tank 11 is provided with a water drain valve 12 and the empty tank is provided with a mass G g Steam mass flow m zq ，G＝G g +m zq The total mass G must not exceed 180kg.
The steam humidity measuring method using the device comprises the following steps:
(1) After the steam humidity measuring device is started, the temperature t of steam inside the boiler barrel is measured through the platinum resistor 1 1 Pressure p of steam after flowing through orifice plate 14 2 Temperature t 2 After the steam has further flowed through the heater 15, as measured by the pressure-temperature sensor 5, the pressure is substantially unchanged, p 3 ≈p 2 Temperature t 3 The steam mass flow m and the steam humidity W can be calculated according to the steady flow energy equation and the energy balance relation by the temperature sensor 6.
(2) After the steam humidity measuring device works stably for a period of time, the power button 19 is pressed, and the humidity display instrument 21 is electrified to work; pressing the water discharge button 16, the three-way valve 18 discharges water outwards, and the water discharge valve 12 discharges water outwards at the same time; after the metering tank 11 is emptied, the display 22 displays the empty quality of the metering tank 11, and the water storage button is pressed17, the three-way valve 18 drains downwards, the water drain valve 12 is closed, and the metering tank 11 starts to store water; after a longer period of water is stored, the calibration button 20 is pressed, and the steam mass flow m measured by the metering tank 11 is used zq Instead of the sampled steam mass flow m measured by the heater 15, the display 22 displays the updated steam humidity and the sampled steam mass flow, and the measured steam humidity is more accurate; if the amount of water in the metering tank 11 is too large, the water discharge button 16 may be pressed again, and the related operation is repeated.
Steam temperature t inside the boiler barrel 1 Enthalpy h 1 Humidity W, flow rate c 1 Approximately 0, platinum resistance 1 can measure t 1 The method comprises the steps of carrying out a first treatment on the surface of the After the steam flows through the orifice plate 14 (two blocks), the pressure p 2 Temperature t 2 Enthalpy h measured by pressure-temperature sensor 5 2 Flow rate c 2 The method comprises the steps of carrying out a first treatment on the surface of the After the steam has further flowed through the heater 15, the pressure is substantially constant, p 3 ≈p 2 Temperature t 3 Enthalpy h measured by temperature sensor 6 3 Wen Sheng t=t 3 -t 2 The method comprises the steps of carrying out a first treatment on the surface of the By means of the metering tank 11, the mass flow m of the sampled steam can be accurately measured zq 。
The specific calculation method of the steam mass flow m and the steam humidity W comprises the following steps:
according to the steady flow energy equation, there is the following relationship:
wherein q is heat loss, h 1 For the enthalpy of the steam at the inlet of the sampling tube 2, h 2 To measure the enthalpy of the steam in the tube 8 before the heater 15 c 1 For the flow rate of steam at the inlet of the sampling tube 2 c 2 To measure the flow rate of steam in the tube 8 before the heater 15, g is the gravitational constant, z 1 Is the height at the inlet of the sampling tube 2; z 2 The height in front of the heater 15 in the measuring tube 8;
between the steam of the boiler barrel and the steam at the pressure temperature sensor 5, the internal test element of the boiler barrel has no heat dissipation, and the external test element has good heat preservation, so q is approximately equal to 0; the test element being placed horizontally, z 2 ＝z 1 The simplified equation can be obtained:
according to the energy balance relation, the following can be obtained:
N＝f(h 3 -h 2 )m
wherein N is the electric heating power of the heater 15, and f is the measurement coefficient; h is a 2 To measure the enthalpy, h, of the steam in the tube 8 before the heater 15 3 For measuring the enthalpy of the steam in the pipe 8 after the heater 15, m is the test mass flow of the steam in the section 15 of the heater;
pressure p of steam before heater 15 2 Temperature t 2 The pressure is substantially constant, p, after the steam has passed through the heater 15, as measured by the pressure-temperature sensor 5 3 ≈p 2 Temperature t 3 As measured by a temperature sensor 6, according to the pressure p 2 Temperature t 2 Enthalpy h can be found by means of a superheated steam table 2 Density ρ 2 The method comprises the steps of carrying out a first treatment on the surface of the According to pressure p 3 Temperature t 3 Enthalpy h can be found by means of a superheated steam table 3 ；
Since the pressure and temperature sensors 5 and 6 only measure parameters related to the tube axis center, the energy balance equation of the heater 15 segment is properly corrected by the measurement coefficient f, the initial assignment f=1, and the steam test mass flow m of the heater 15 segment can be obtained by the following formula:
m can in turn be calculated by the following formula:
the method is obtained by the conversion of the formula:
wherein m is the steam test mass flow of the heater 15 sections, d is the inner diameter of the measuring tube 8, c 2 To measure the flow rate ρ of steam in the tube 8 before the heater 15 2 For measuring the density of the steam in the tube 8 before the heater 15;
platinum resistor 1 measures temperature t at inlet of sampling tube 2 1 According to the temperature ordered saturated steam table, the corresponding saturated water enthalpy h' and saturated steam enthalpy h″ can be found. Enthalpy h 1 The expression of (2) is as follows:
h 1 ＝h′W+h″(1-W)
in the formula, h 1 For the enthalpy of the steam at the inlet of the sampling tube 2, h' is the temperature t at the inlet of the sampling tube 2 1 Corresponding saturated water enthalpy, h' is the temperature t at the inlet of the sampling tube 2 1 Corresponding saturated steam enthalpy, wherein W is steam humidity;
when the steam mass flow m is calibrated, the metering tank 11 is utilized to accurately measure the steam mass flow m zq Then the measurement coefficient f=m/m zq =a. The assignment of f is changed from 1 to A, m is calculated again, at the moment, m is more accurate, the electric heating power N is regulated basically without influence, and the heat dissipation influence of the 15 sections of the heater is smaller. The related formula is calculated again, and the finally obtained steam humidity W is more accurate.
The steam humidity measuring device and the method thereof adopt the high-precision sensor, consider the influence of the flow velocity inside the test element, consider the heat preservation of the relevant surface, and can calibrate important parameters frequently, thereby having larger humidity measuring range and obviously improving the measuring precision.
The technical means disclosed by the scheme of the invention is not limited to the technical means disclosed by the embodiment, and also comprises the technical scheme formed by any combination of the technical features. It should be noted that modifications and adaptations to the invention may occur to one skilled in the art without departing from the principles of the present invention and are intended to be within the scope of the present invention.
Claims (6)
1. The utility model provides a steam humidity measuring device, its characterized in that includes sampling tube, survey pipe, governing valve, cooling device, metering tank, the entrance of sampling tube is equipped with platinum resistance, the sampling tube export with survey pipe's access connection, survey pipe's export with cooling device passes through the governing valve and links to each other, survey pipe is interior to be equipped with orifice plate, pressure temperature sensor, heater and temperature sensor from the import to export in proper order, cooling device's export is equipped with the three-way valve, two exports of three-way valve connect drain pipe and drip pipe respectively, the metering tank is located the below of drip pipe, the bottom of metering tank is equipped with the water drain valve, the metering tank is equipped with force transducer down;
the device comprises a platinum resistor, a pressure temperature sensor, a regulating valve, a three-way valve, a heater, a water drain valve and a force sensor, and is characterized by further comprising a humidity display instrument, wherein a controller is arranged in the humidity display instrument, the platinum resistor, the pressure temperature sensor, the regulating valve, the three-way valve, the heater, the water drain valve and the force sensor are all connected with the controller, a display is further arranged on the humidity display instrument, and the display is connected with the controller;
the outer wall of the sampling tube is provided with threads, a sealing baffle is arranged at the rear of the threads, and a high-temperature-resistant sealing gasket is arranged in front of the sealing baffle;
the sampling tube extends into the steam space of the boiler barrel and is fixed with the boiler barrel through threads, and the sealing baffle is tightly attached to the outer wall of the boiler barrel after the sampling tube is installed;
a groove is formed in the pipe wall at the inlet of the sampling pipe, the platinum resistor is positioned in the groove, the inlet of the sampling pipe is also provided with a through-flow rotary cap, and the through-flow rotary cap covers the groove after being screwed;
the outside of the measuring tube is provided with an insulating layer, and a stainless steel protective tube is arranged outside the insulating layer.
2. The steam humidity measuring device as claimed in claim 1, wherein two orifice plates are provided in the measuring tube in front of the pressure temperature sensor.
3. The vapor humidity measuring device of claim 1, wherein the regulating valve and the cooling device are provided with heat insulating layers.
4. The vapor humidity measuring device of claim 1, wherein four force sensors are arranged below the metering tank, and the four force sensors are uniformly and symmetrically arranged along the circumference of the bottom surface of the metering tank.
5. A method of measuring the humidity of steam, characterized in that it is based on the device of claim 1, comprising the steps of: (1) Starting a steam humidity measuring device, and measuring the steam temperature t inside the boiler barrel through a platinum resistor 1 Pressure p of steam after flowing through the orifice plate 2 Temperature t 2 After the steam further flows through the heater, the pressure is basically unchanged, p, as measured by the pressure and temperature sensor 3 ≈p 2 Temperature t 3 The steam mass flow m and the steam humidity W can be calculated according to a steady flow energy equation and an energy balance relation by measuring by a temperature sensor; (2) After the steam humidity measuring device works stably for a period of time, the humidity display instrument controls the three-way valve to drain outwards, and the water drain valve also drains outwards; after the metering tank is emptied, the display displays the empty tank quality of the metering tank, then the three-way valve drains downwards, the water drain valve is closed, and the metering tank starts to store water; after water is stored, the steam mass flow m measured by a metering tank zq Instead of the heater measured sampled steam mass flow m.
6. The method for measuring steam humidity according to claim 5, wherein the specific calculation method of the steam mass flow m and the steam humidity W is as follows:
according to the steady flow energy equation, there is the following relationship:
wherein q is heat loss, h 1 For steam at the inlet of the sampling tubeEnthalpy, h 2 To measure the enthalpy of the steam in the tube before the heater c 1 C, for the flow rate of steam at the inlet of the sampling tube 2 To measure the flow rate of steam in front of heater in tube, g is the gravitational constant, z 1 Is the height at the inlet of the sampling tube; z 2 The height in front of the heater in the measurement tube;
c 1 ≈0，q≈0，z 2 ＝z 1 the simplified equation can be obtained:
according to the energy balance relation, the following can be obtained:
N＝f(h 3 -h 2 )m
wherein N is the electrothermal power of the heater, and f is the measurement coefficient; h is a 2 To measure the enthalpy of the steam in the tube before the heater, h 3 The enthalpy of the steam after the heater in the measuring tube is measured, and m is the steam test mass flow of the heater section;
pressure of steam before heater p 2 Temperature t 2 The pressure is basically unchanged after the steam flows through the heater as measured by the pressure and temperature sensor, p 3 ≈p 2 Temperature t 3 As measured by a temperature sensor, according to the pressure p 2 Temperature t 2 Enthalpy h can be found by means of a superheated steam table 2 Density ρ 2 The method comprises the steps of carrying out a first treatment on the surface of the According to pressure p 3 Temperature t 3 Enthalpy h can be found by means of a superheated steam table 3 The method comprises the steps of carrying out a first treatment on the surface of the The initial assignment f=1, the heater segment steam test mass flow m can be found using the following equation:
m can in turn be calculated by the following formula:
the method is obtained by the conversion of the formula:
wherein m is the steam test mass flow of the heater section, d is the inner diameter of the measuring tube, c 2 To measure the flow rate ρ of steam in front of heater in tube 2 To measure the density of the steam in front of the heater in the tube;
platinum resistance measuring temperature t at inlet of sampling tube 1 According to the temperature ordered saturated steam table, corresponding saturated water enthalpy h' and saturated steam enthalpy h″ can be obtained; enthalpy h 1 The expression of (2) is as follows:
h 1 ＝h′W+h″(1-W)
in the formula, h 1 For the enthalpy of the steam at the inlet of the sampling tube, h' is the temperature t at the inlet of the sampling tube 1 Corresponding saturated water enthalpy, h' is the temperature t at the inlet of the sampling tube 1 Corresponding saturated steam enthalpy, wherein W is steam humidity;
when the standard is met, the measuring tank is used for accurately measuring the steam mass flow mzq, and then the measuring coefficient f=m/mzq =A; the f assignment is changed from 1 to A and m is recalculated.
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