A device for measuring dryness of saturated steam

Abstract

The present invention discloses a saturated steam dryness measuring device, which samples wet steam in real time through a sampler and enters the primary side of a shell-and-tube heat exchanger to be cooled into single-phase high-temperature water, and then is cooled into normal-temperature water by tap water on the primary side of a coil heat exchanger, and then is used as a cooling medium on the secondary side of the shell-and-tube heat exchanger to cool the wet steam on the primary side, and the wet steam dryness value is obtained by measuring the change in enthalpy and combining it with the law of conservation of energy. The product is a portable dryness measuring instrument with no moving parts, no parts that need to be replaced, and no radiation, and has the characteristics of simple structure, low cost, strong adaptability, high accuracy, etc., and can measure wet steam dryness online. The purpose of the present invention is to provide a saturated steam dryness measuring device to solve the problem of inaccurate wet steam dryness value measurement accuracy caused by the measurement accuracy of water flow.

Description

Technical Field

[0001] The invention relates to the technical field of thermal measuring instruments, and in particular to a saturated steam dryness measuring device. Background Art

[0002] In the invention patent with application number 201310086699.3, an online wet steam dryness measuring instrument is provided. The wet steam of the measuring device is cooled into single-phase water by a heat exchanger, and then cooled into single-phase low-temperature water by a cooler for a second time before being directly discharged. In this way, since the cooling medium that cools the wet steam into single-phase high-temperature water and the wet steam are in a state of dynamic flow, when obtaining the dryness value of the wet steam, in addition to measuring the enthalpy value at the outlet of the heat exchanger medium, the enthalpy value at the inlet of the heat exchanger cooler, and the enthalpy value at the outlet of the heat exchanger cooling water, it is also necessary to measure the corresponding water flow rate (the cooling medium flow rate and the wet steam flow rate that cool the wet steam into single-phase high-temperature water), and the measurement accuracy of the water flow rate has a great influence on the result of the dryness measurement, thus resulting in inaccurate measurement accuracy of the wet steam dryness value. Summary of the invention

[0003] The object of the present invention is to provide a saturated steam dryness measurement device to solve the problem of inaccurate measurement accuracy of wet steam dryness value caused by the measurement accuracy of water flow.

[0004] The present invention is achieved through the following technical solutions:

[0005] A saturated steam dryness measurement device comprises n heat exchangers, n coolers and 3n enthalpy value measurement devices, where n is a positive integer;

[0006] The primary side outlets and primary side inlets of adjacent heat exchangers are connected in sequence, and the primary side inlet of the first heat exchanger is used to connect the steam pipeline, the primary side outlet of the last heat exchanger is connected to the medium inlet of the first cooler, the medium outlet of the first cooler is connected to the secondary side inlet of the first heat exchanger, and the medium inlet and medium outlet of any remaining cooler are respectively connected to the secondary side outlets and secondary side inlets of two adjacent heat exchangers;

[0007] The enthalpy value measuring device is arranged at the primary side outlet of the heat exchanger, the secondary side inlet of the heat exchanger and the secondary side outlet of the heat exchanger, and is used to measure the primary side outlet enthalpy value h 1 , secondary side inlet enthalpy h 2 And the secondary side outlet enthalpy h 3 ;

[0008] It also includes a cooling water inlet branch and a cooling water outlet branch; the cooling water inlet branch is connected to the cooling water inlet of the cooler; the cooling water outlet branch is connected to the cooling water outlet of the cooler.

[0009] In the invention patent with application number 201310086699.3, an online wet steam dryness measuring instrument is provided. The wet steam of the measuring device is cooled into single-phase water by a heat exchanger, and then cooled into single-phase low-temperature water by a cooler for a second time before being directly discharged. In this way, since the cooling medium that cools the wet steam into single-phase high-temperature water and the wet steam are in a state of dynamic flow, when obtaining the dryness value of the wet steam, in addition to measuring the enthalpy value at the outlet of the heat exchanger medium, the enthalpy value at the inlet of the heat exchanger cooler, and the enthalpy value at the outlet of the heat exchanger cooling water, it is also necessary to measure the corresponding water flow rate (the cooling medium flow rate and the wet steam flow rate that cool the wet steam into single-phase high-temperature water), and the measurement accuracy of the water flow rate has a great influence on the result of the dryness measurement, so the measurement accuracy of the wet steam dryness value can only reach ±5%. Based on this, the present application provides a new dryness measuring device, in which the single-phase low-temperature water is not directly discharged from the device, but is used as a cooling medium to cool the wet steam on the primary side. In this way, the cooling medium flow rate of the wet steam cooled into single-phase high-temperature water and the wet steam flow rate are equal in real time, thereby eliminating the factor (flow rate) that has the greatest impact on the dryness error, greatly improving the dryness measurement accuracy.

[0010] Preferably, since there are differences in steam temperature at different heights in the steam pipe, in order to make the temperature of wet steam extracted from the steam pipe more uniform per unit time, the present application also provides a single porous sampler with different sampling heights, the output end of the porous sampler is connected to the primary side inlet of the first heat exchanger, and the input end of the porous sampler is used to connect to the steam pipe, so that steam at different heights can be extracted, ensuring that the steam in each temperature layer can be extracted, thereby reducing errors.

[0011] Preferably, it further comprises a data processing module, which is connected to the enthalpy measuring device and is used to calculate the dryness value of the wet steam according to the primary side outlet enthalpy value, the secondary side inlet enthalpy value and the secondary side outlet enthalpy value.

[0012] In order to realize the integration of automatic data measurement and automatic calculation, a data processing module is also provided in this scheme, which is used to automatically calculate the dryness value of wet steam after the enthalpy value measuring device obtains the primary side outlet enthalpy value, the secondary side inlet enthalpy value and the secondary side outlet enthalpy value. Compared with only realizing the automatic data measurement function, adding the data processing module can greatly reduce the workload of the staff and improve the calculation efficiency and accuracy.

[0013] Preferably, it also includes a flow regulating device, which is arranged at the secondary side outlet side of the last heat exchanger and is used to adjust the secondary side outlet flow of the last heat exchanger.

[0014] Preferably, the enthalpy measuring device includes a temperature measuring device and a pressure measuring device; the temperature measuring device is arranged at the primary side outlet of the heat exchanger, the secondary side inlet of the heat exchanger and the secondary side outlet of the heat exchanger; the pressure measuring device is arranged at the primary side outlet of the last heat exchanger.

[0015] Preferably, the temperature measuring device is configured as a platinum resistor.

[0016] In this solution, the temperature measurement device uses a 3mm outer diameter armored A-class platinum resistor, and the installation method is preferably a flow-front arrangement, that is, the measuring end of the platinum resistor points in the opposite direction of the water flow, so that the temperature measurement is more accurate. The pressure measurement device uses a 0.1-class pressure transmitter for measurement, and the installation method is based on the measurement point parameters and combined with the HG / T 21581-2012 national standard installation.

[0017] Preferably, the outer surface of the heat exchanger is also covered with a thermal insulation layer.

[0018] By installing an insulation layer on the outer surface of the heat exchanger, the heat exchange between the heat exchanger and the ambient temperature can be reduced, heat loss can be reduced, and measurement accuracy can be improved. Among them, the material of the insulation layer is not fixed, and it can be reasonably selected according to the measured wet steam parameters, and the insulation layer can be installed on the outer surface of the heat exchanger in accordance with the national standards GB / T 8175-2008 and GB / T 4272-2008.

[0019] Preferably, a mixer is also included, the input end of the mixer is connected to the secondary side outlet of the last heat exchanger and the cooling water inlet branch, and the output end of the mixer is connected to the cooling water outlet branch. In order to improve the cooling efficiency, the mixer in the present application is set as a coil heat exchanger with the bottom of the primary side connected to the secondary side, which is first cooled by cooling water on the primary side and then mixed with cooling water to accelerate the cooling of single-phase high-temperature water.

[0020] Preferably, a pressure reducing device is further included, one end of which is connected to the input end of the mixer, and the other end of which is connected to the secondary side outlet of the last heat exchanger.

[0021] Preferably, the pressure reducing device is configured as a multi-stage pressure reducing orifice plate.

[0022] By setting a pressure reducing device, the single-phase cooling water can be directly discharged after the pressure is reduced, and will not cause harm to the human body.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] The single-phase low-temperature water in the measuring device is not directly discharged from the device, but is used as a cooling medium to cool the wet steam on the primary side. In this way, the cooling medium flow rate of the wet steam cooled into single-phase high-temperature water and the wet steam flow rate are equal in real time, thereby eliminating the factor (flow rate) that has the greatest impact on the dryness error, greatly improving the dryness measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0026] Figure 1 It is a structural schematic diagram of the high-pressure dryness measurement device of the present invention;

[0027] Figure 2 It is a structural schematic diagram of the high pressure dryness measurement device in the present invention;

[0028] Figure 3 It is a structural schematic diagram of a wide pressing dryness measurement device of the present invention;

[0029] Marks and corresponding parts names in the attached drawings:

[0030] 1. Heat exchanger; 2. Cooler; 3. Multi-hole sampler; 4. Flow regulating device; 5. Mixer; 6. Cooling water inlet branch; 7. Cooling water outlet branch; 8. Primary side outlet; 9. Primary side inlet; 10. Secondary side inlet; 11. Secondary side outlet; 12. Medium outlet; 13. Medium inlet; 14. Cooling water outlet; 15. Cooling water inlet; 16. Gate valve; 17. Pressure reducing device. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0032] Example 1

[0033] This embodiment provides a high pressure dryness measurement device, which is suitable for pressures ranging from 14 to 22.1 MPa. Figure 1 , including a porous sampler 3, a gate valve 16, a shell and tube heat exchanger with a surface covered with an insulation layer, a coil heat exchanger, a cooling water inlet branch 6, a cooling water outlet branch 7, and three temperature measuring devices (used to obtain the primary side outlet temperature T of the shell and tube heat exchanger, respectively). 111 , secondary side inlet temperature T121 And the secondary side outlet temperature T 122 ), a pressure measuring device (used to obtain the primary outlet pressure P of the shell and tube heat exchanger 1 ) and a mixer 5;

[0034] Among them, the input end of the porous sampler 3 is connected to the steam pipe, the output end of the porous sampler 3 is connected to the primary side inlet 9 of the shell and tube heat exchanger, and the gate valve 16 is set at the output end of the porous sampler 3 to control the flow rate of steam entering the shell and tube heat exchanger; the primary side outlet 8 of the shell and tube heat exchanger is connected to the primary side inlet 9 of the coil heat exchanger (the medium inlet 13 of the cooler 2), the primary side outlet 8 of the coil heat exchanger (the medium outlet 12 of the cooler 2) is connected to the secondary side inlet 10 of the shell and tube heat exchanger, the secondary side outlet 11 of the shell and tube heat exchanger is connected to the primary side of the mixer 5, the cooling water inlet 15 branch 6 is connected to the secondary side inlet 10 of the coil heat exchanger (the cooling water inlet 15 of the cooler 2) and the secondary side inlet 10 of the mixer 5, and the cooling water outlet 14 branch 7 is connected to the secondary side outlet 11 of the coil heat exchanger (the cooling water outlet 14 of the cooler 2) and the secondary side outlet 11 of the mixer 5.

[0035] When working, enthalpy value h 0 The wet steam passes through the porous sampler 3 and enters the primary side of the shell-and-tube heat exchanger and is cooled to an enthalpy value of h 111 Single-phase high-temperature water; the enthalpy is h 111 The single-phase high-temperature water then enters the coil heat exchanger and is cooled to an enthalpy of h 121 The enthalpy of water at room temperature is h 121 The room temperature water then enters the secondary side of the shell and tube heat exchanger and is heated to an enthalpy value of h 122 Single-phase high-temperature water.

[0036] The dryness measurement principle of this embodiment is:

[0037] The enthalpy is h 0 The wet steam passes through the porous sampler 3 and the gate valve 16 into the primary side of the shell and tube heat exchanger and is cooled to an enthalpy value of h 111 The single-phase high-temperature water in this process can be ignored. The process pressure value of the medium measured by the pressure transmitter can represent the wet steam pressure and the pressure of the water after cooling. According to IAPWS-IF97, the pressure value P 1 Calculate the corresponding saturation temperature T sat , by adjusting the valve (flow control device) behind the porous plate, T 111 <T sat , T 122 <T sat , P 1 and T 111Substitute into the enthalpy formula (IAPWS-IF97) to obtain the enthalpy value h at the primary outlet of the shell-and-tube heat exchanger 111 ; P 1 and T 121 Substitute the enthalpy formula to obtain the secondary inlet enthalpy value h of the shell-and-tube heat exchanger 121 ; P 1 and T 122 Substitute the enthalpy formula to obtain the secondary outlet enthalpy value h of the shell and tube heat exchanger 122 , through the law of energy conservation, the dryness of the wet steam being measured can be obtained. The specific formula is as follows:

[0038] (h 0 -h 111 )η x =(h 122 -h 121 )

[0039]

[0040] Among them, η x is the system heat transfer efficiency. After the high-pressure dryness measurement device is installed, it can be obtained through calibration. f is the saturated water enthalpy, h v is the saturated steam enthalpy, and x is the dryness value.

[0041] In this embodiment, since the secondary side pressure of the shell-and-tube heat exchanger is equal to the wet steam pressure, the secondary side temperature rise can reach about 300° C. Therefore, the resolution of the high-pressure dryness measurement device in this embodiment can be better than 0.005.

[0042] Example 2

[0043] This embodiment provides a medium- and high-pressure dryness measurement device, which is suitable for pressures ranging from 7 to 22.1 MPa. Figure 2 As shown, it includes a porous sampler 3, a gate valve 16, two shell-and-tube heat exchangers with a surface covered with a thermal insulation layer (No. ① shell-and-tube heat exchanger and No. ② shell-and-tube heat exchanger), two coil heat exchangers (No. ① coil heat exchanger and No. ② coil heat exchanger), a cooling water inlet branch 6, a cooling water outlet branch 7, and 6 temperature measuring devices (used to obtain the primary side outlet temperature T of No. ① shell-and-tube heat exchanger, respectively). 111 , secondary side inlet temperature T 121 And the secondary side outlet temperature T 122 , No. ② shell and tube heat exchanger primary side outlet temperature T 211 , secondary side inlet temperature T 221 And the secondary side outlet temperature T 222 ), a pressure measuring device (used to obtain the primary side outlet pressure of the shell and tube heat exchanger No. ②) and a mixer 5;

[0044] Among them, the input end of the porous sampler 3 is connected to the steam pipeline, the output end of the porous sampler 3 is connected to the primary side inlet 9 of the No. ① shell and tube heat exchanger, and the gate valve 16 is set at the output end of the porous sampler 3 to control the flow rate of steam entering the No. ① shell and tube heat exchanger; the primary side outlet 8 of the No. ① shell and tube heat exchanger is connected to the primary side inlet 9 of the No. ② shell and tube heat exchanger, the primary side outlet 8 of the No. ② shell and tube heat exchanger is connected to the primary side inlet 9 of the No. ① coil heat exchanger, the primary side outlet 8 of the No. ① coil heat exchanger is connected to the secondary side inlet 10 of the No. ① shell and tube heat exchanger, and the secondary side outlet 11 of the No. ① shell and tube heat exchanger is connected to the secondary side outlet 12 of the No. ② shell and tube heat exchanger. The primary side inlet 9 of coil-tube heat exchanger No. 1 is connected, the primary side outlet 8 of coil-tube heat exchanger No. 2 is connected with the secondary side inlet 10 of shell-and-tube heat exchanger No. 2, the secondary side outlet 11 of shell-and-tube heat exchanger No. 2 is connected in sequence to the multi-stage pressure reducing orifice plate, the flow regulating device 4 and the mixer 5, the cooling water inlet 15 branch 6 is connected to the secondary side inlet 10 of coil-and-tube heat exchanger No. 1, the secondary side inlet 10 of coil-and-tube heat exchanger No. 2 and the secondary side inlet 10 of the mixer 5, and the cooling water outlet 14 branch 7 is connected to the secondary side outlet 11 of coil-and-tube heat exchanger No. 1, the secondary side outlet 11 of coil-and-tube heat exchanger No. 2 and the secondary side outlet 11 of the mixer 5.

[0045] When working, enthalpy value h 0 The wet steam passes through the porous sampler 3 and enters the primary side of the No. ① shell and tube heat exchanger, where it is cooled to an enthalpy of h 111 The single-phase high-temperature water has an enthalpy of h 111 The single-phase high-temperature water enters the primary side of the No. ② shell-and-tube heat exchanger and is cooled to an enthalpy of h 211 The single-phase high-temperature water has an enthalpy of h 211 The single-phase high-temperature water is cooled by coil heat exchanger No. ① to a temperature of h 121 The enthalpy of water at room temperature is h 121 The room temperature water is heated to a temperature of h by the secondary side of the No. ① shell and tube heat exchanger. 122 The single-phase high-temperature water has an enthalpy of h 122 The single-phase high-temperature water is cooled by coil heat exchanger No. ② to an enthalpy value of h 221 The enthalpy of water at room temperature is h 221 The room temperature water is heated to a temperature of h by the secondary side of the shell and tube heat exchanger ②. 222 Single-phase high-temperature water.

[0046] The dryness measurement principle of this embodiment is:

[0047] Enthalpy h 0The wet steam passes through the porous sampler 3 and then passes through the primary side of the No. ① and No. ② shell and tube heat exchangers and is cooled into single-phase high-temperature water. The pressure change in this process can be ignored. The process pressure value of the medium measured by the pressure transmitter can represent the wet steam pressure and the pressure of the cooled water. According to IAPWS-IF97, the pressure change of the medium can be measured by the pressure transmitter. 1 Calculate the corresponding saturation temperature T sat , by adjusting the valve (flow control device) behind the porous plate, if T 111 <T sat , T 122 <T sat , the dryness value of saturated steam can be obtained by the calculation method of the high-pressure dryness measurement device provided in Example 1. If this cannot be achieved, let T 211 <T sat , T 122 <T sat , T 222 <T sat , put P 1 and T 211 、T 121 、T 122 、T 221 、T 222 Substituting into the enthalpy formula (IAPWS-IF97), we can get the enthalpy value h at the primary outlet of the shell-and-tube heat exchanger No. ② 211 、No.① shell and tube heat exchanger secondary side inlet enthalpy value h 121 、No.① shell and tube heat exchanger secondary side outlet enthalpy value h 122 , ②The secondary side inlet enthalpy of the shell and tube heat exchanger h 221 And the secondary outlet enthalpy value h of the shell and tube heat exchanger No. ② 222 , through the law of energy conservation, the dryness of the wet steam being measured can be obtained. The specific formula is as follows:

[0048] (h 0 -h 211 )η x =(h 122 -h 121 )+(h 222 -h 221 )

[0049]

[0050] Among them, η x is the system heat transfer efficiency. After the medium and high pressure dryness measurement device is installed, it can be obtained through calibration. f is the saturated water enthalpy, h v is the saturated steam enthalpy, and x is the dryness value.

[0051] In this embodiment, since the secondary side pressures of the shell and tube heat exchangers No. ① and No. ② are equal to the wet steam pressure, the secondary side temperature rise of each shell and tube heat exchanger can reach about 200°C, and the overall temperature rise can reach about 400°C. Therefore, the resolution of the medium and high pressure dryness measurement device in this embodiment can be better than 0.004.

[0052] Example 3

[0053] This embodiment provides a wide range of dryness measurement device, suitable for pressure range of 3.5 ~ 22.1MPa, such as Figure 3 As shown, it includes a porous sampler 3, a gate valve 16, three shell and tube heat exchangers with a surface covered with a thermal insulation layer (No. ① shell and tube heat exchanger, No. ② shell and tube heat exchanger and No. ③ shell and tube heat exchanger), three coil heat exchangers (No. ① coil heat exchanger, No. ② coil heat exchanger and No. ③ coil heat exchanger), a cooling water inlet 15 branch 6, a cooling water outlet 14 branch 7, and 9 temperature measuring devices (used to obtain the primary side outlet temperature T of No. ① shell and tube heat exchanger respectively). 111 , secondary side inlet temperature T 121 And the secondary side outlet temperature T 122 , No. ② shell and tube heat exchanger primary side outlet temperature T 211 , secondary side inlet temperature T 221 , secondary side outlet temperature T 222 ③The primary outlet temperature of coil heat exchanger T 311 , secondary side inlet temperature T 321 And the secondary side outlet temperature T 322 ), a pressure measuring device (used to obtain the pressure of the primary side outlet 8 of the No. ③ shell and tube heat exchanger) and a mixer 5;

[0054] Among them, the input end of the porous sampler 3 is connected to the steam pipeline, the output end of the porous sampler 3 is connected to the primary side inlet 9 of No. ① shell and tube heat exchanger, and the gate valve 16 is arranged at the output end of the porous sampler 3, which is used to control the flow rate of steam entering No. ① shell and tube heat exchanger; the primary side outlet 8 of No. ① shell and tube heat exchanger is connected to the primary side inlet 9 of No. ② shell and tube heat exchanger, the primary side outlet 8 of No. ② shell and tube heat exchanger is connected to the primary side inlet 9 of No. ③ shell and tube heat exchanger, the primary side outlet 8 of No. ③ shell and tube heat exchanger is connected to the primary side inlet 9 of No. ① coil heat exchanger, the primary side outlet 8 of No. ① coil heat exchanger is connected to the secondary side inlet 10 of No. ① shell and tube heat exchanger, the secondary side outlet 11 of No. ① shell and tube heat exchanger is connected to the primary side inlet 9 of No. ② coil heat exchanger, and the primary side outlet 8 of No. ② coil heat exchanger is connected to the primary side inlet 9 of No. ② The secondary side inlet 10 of the shell and tube heat exchanger is connected, the secondary side outlet 11 of the shell and tube heat exchanger No. ② is connected to the primary side inlet 9 of the coil heat exchanger No. ③, the primary side outlet 8 of the coil heat exchanger No. ③ is connected to the secondary side inlet 10 of the shell and tube heat exchanger No. ③, the secondary side outlet 11 of the shell and tube heat exchanger No. ③ is connected to the multi-stage pressure reducing orifice plate, the flow regulating device 4 and the mixer 5 in sequence, the cooling water inlet 15 branch 6 is connected to the secondary side inlet 10 of the coil heat exchanger No. ①, the secondary side inlet 10 of the coil heat exchanger No. ②, the secondary side inlet 10 of the coil heat exchanger No. ③ and the secondary side inlet 10 of the mixer 5, and the cooling water outlet 14 branch 7 is connected to the secondary side outlet 11 of the coil heat exchanger No. ①, the secondary side outlet 11 of the coil heat exchanger No. ②, the secondary side outlet 11 of the coil heat exchanger No. ③ and the secondary side outlet 11 of the mixer 5.

[0055] When working, enthalpy value h 0 The wet steam passes through the porous sampler and the gate valve into the primary side of the No. ① shell and tube heat exchanger and is cooled to an enthalpy value of h 111 The single-phase high-temperature water has an enthalpy of h 111 The single-phase high-temperature water enters the primary side of the No. ② shell-and-tube heat exchanger and is cooled to an enthalpy of h 211 The single-phase high-temperature water has an enthalpy of h 211 The single-phase high-temperature water enters the primary side of the No. ③ shell-and-tube heat exchanger and is cooled to an enthalpy of h 311 The single-phase high-temperature water has an enthalpy of h 311 The single-phase high-temperature water is cooled by the coil heat exchanger to an enthalpy value of h 121 The enthalpy of water at room temperature is h 121 The room temperature water is heated to a temperature of h by the secondary side of the No. ① shell and tube heat exchanger. 122 The single-phase high-temperature water has an enthalpy of h 122 The single-phase high-temperature water is cooled by the coil heat exchanger to an enthalpy value of h 221 The enthalpy of water at room temperature is h 221The room temperature water is heated to a temperature of h by the secondary side of the shell and tube heat exchanger ②. 222 The single-phase high-temperature water has an enthalpy of h 222 The single-phase high-temperature water is cooled by the coil heat exchanger to an enthalpy value of h 321 The enthalpy of water at room temperature is h 321 The room temperature water is heated to a temperature of h by the secondary side of the No. ③ shell and tube heat exchanger. 322 Single-phase high-temperature water.

[0056] The dryness measurement principle of this embodiment is:

[0057] Enthalpy h 0 The wet steam passes through the porous sampler 3 and then passes through the primary side of the No. ①, No. ② and No. ③ shell and tube heat exchangers and is cooled into single-phase high-temperature water. The pressure change in this process can be ignored. The process pressure value of the medium measured by the pressure transmitter can represent the wet steam pressure and the pressure of the cooled water. According to IAPWS-IF97, the pressure change of the medium can be measured by the pressure transmitter. 1 Calculate the corresponding saturation temperature T sat , by adjusting the valve behind the porous orifice plate, if T 111 <T sat , T 122 <T sat , the dryness value of saturated steam can be obtained by using the high-pressure dryness measurement device calculation method. If this is not possible, let T 211 <T sat , T 122 <T sat , T 222 <T sat , the dryness value of saturated steam can be obtained by using the calculation method of the medium and high pressure dryness measurement device. If this cannot be achieved, let T 311 <T sat , T 122 <T sat , T 222 <T sat , T 322 <T sat , put P 1 and T 311 、T 121 、T 122 、T 221 、T 222 、T 321 、T 322 Substituting into the enthalpy formula (IAPWS-IF97), we can get the enthalpy value h at the primary outlet of the shell-and-tube heat exchanger No. ③. 311 、No.① shell and tube heat exchanger secondary side inlet enthalpy value h 121 、No.① shell and tube heat exchanger secondary side outlet enthalpy value h 122 , ②The secondary side inlet enthalpy of the shell and tube heat exchanger h221 , Enthalpy value of secondary outlet of No.② shell and tube heat exchanger h 222 、③The secondary side inlet enthalpy of the shell and tube heat exchanger h 321 、③The secondary outlet enthalpy of the shell and tube heat exchanger h 322 , through the law of energy conservation, the dryness of the wet steam being measured can be obtained. The specific formula is as follows:

[0058] (h 0 -h 311 )η x =(h 122 -h 121 )+(h 222 -h 221 )+(h 322 -h 321 )

[0059]

[0060] Among them, η x is the system heat transfer efficiency. After the wide pressure dryness measurement device is installed, it can be obtained through calibration. f is the saturated water enthalpy, h v is the saturated steam enthalpy, and x is the dryness value.

[0061] In this embodiment, since the secondary side pressures of the shell and tube heat exchangers No. ①, No. ② and No. ③ are equal to the wet steam pressure, the secondary side temperature rise of each shell and tube heat exchanger can reach about 150°C, and the overall temperature rise can reach about 500°C. Therefore, the resolution of the wide pressure dryness measurement device in this embodiment can be better than 0.003.

[0062] Among them, in order to ensure the long-term stable operation of the dryness measuring device, after the dryness measuring device is installed and fixed, first turn on the tap water and fully open all the valves on the tap water side; gradually fully open the gate valve until the pressure is stable, slowly open the stop valve behind the multi-stage pressure reducing orifice, and after the system is stable, adjust the tap water valve at the secondary outlet of each coil heat exchanger to make the secondary inlet temperatures of all shell-and-tube heat exchangers close; then slowly open the stop valve to make the shell-and-tube heat exchanger (for high-pressure dryness measuring devices, the shell-and-tube heat exchanger refers to No. ① shell-and-tube heat exchanger, for medium and high pressure dryness measuring devices, the shell-and-tube heat exchanger refers to No. ② shell-and-tube heat exchanger, for wide pressure dryness measuring devices, the shell-and-tube heat exchanger refers to No. ③ shell-and-tube heat exchanger) The difference between the primary outlet temperature and the saturation temperature is less than 10°C. The tap water flow rate connected to the dryness measuring device shall not be less than 10m 3 / h, the pressure is not less than 0.5MPa, the temperature is not higher than 35℃, ensuring that the secondary side inlet temperature of all shell and tube heat exchangers is lower than 50℃, ensuring long-term stable operation of dryness.

[0063] It is also worth noting that for the measurement of dryness below 3.5 MPa, multiple high-pressure dryness measurement devices can be used for combined measurement. Since the system is relatively complex, it will not be introduced in this embodiment.

[0064] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A saturated steam dryness measurement device, characterized in that: It comprises n heat exchangers (1), n ​​coolers (2) and n enthalpy value measuring devices, where n is a positive integer; The primary side outlets (8) and primary side inlets (9) of adjacent heat exchangers (1) are connected in sequence, and the primary side inlet (9) of the first heat exchanger (1) is used to connect to a steam pipeline, the primary side outlet (8) of the last heat exchanger (1) is connected to the medium inlet (13) of the first cooler (2), the medium outlet (12) of the first cooler (2) is connected to the secondary side inlet (10) of the first heat exchanger (1), and the medium inlet (13) and medium outlet (12) of any remaining cooler (2) are respectively connected to the secondary side outlets (11) and secondary side inlets (10) of two adjacent heat exchangers (1); The enthalpy value measuring device is arranged at the primary side outlet (8) of the heat exchanger (1), the secondary side inlet (10) of the heat exchanger (1) and the secondary side outlet (11) of the heat exchanger (1), and is used to measure the primary side outlet enthalpy value, the secondary side inlet enthalpy value and the secondary side outlet enthalpy value; It also includes a cooling water inlet branch (6) and a cooling water outlet branch (7); the cooling water inlet branch (6) is connected to the cooling water inlet (15) of the cooler (2); the cooling water outlet branch (7) is connected to the cooling water outlet (14) of the cooler (2).

2. A saturated steam dryness measurement device according to claim 1, characterized in that: It also comprises a porous sampler (3) with different sampling heights, wherein the output end of the porous sampler (3) is connected to the primary side inlet (9) of the first heat exchanger (1), and the input end of the porous sampler (3) is used to connect to the steam pipeline.

3. A saturated steam dryness measurement device according to claim 1, characterized in that: It also includes a data processing module, which is connected to the enthalpy measuring device and is used to calculate the dryness value of the wet steam according to the primary side outlet enthalpy value, the secondary side inlet enthalpy value and the secondary side outlet enthalpy value.

4. A saturated steam dryness measurement device according to claim 1, characterized in that: It also comprises a flow regulating device (4), which is arranged on the secondary side outlet (11) side of the last heat exchanger (1) and is used to regulate the flow rate of the secondary side outlet (11) of the last heat exchanger (1).

5. The saturated steam dryness measurement device according to claim 1, characterized in that: The enthalpy value measuring device comprises a temperature measuring device and a pressure measuring device; the temperature measuring device is arranged at the primary side outlet (8) of the heat exchanger (1), the secondary side inlet (10) of the heat exchanger (1) and the secondary side outlet (11) of the heat exchanger (1); the pressure measuring device is arranged at the primary side outlet (8) of the last heat exchanger (1).

6. A saturated steam dryness measurement device according to claim 5, characterized in that: The temperature measuring device is configured as a platinum resistance.

7. A saturated steam dryness measurement device according to any one of claims 1 to 6, characterized in that: The outer surface of the heat exchanger (1) is also covered with a thermal insulation layer.

8. The saturated steam dryness measurement device according to claim 1, characterized in that: It also comprises a mixer (5), the input end of the mixer (5) being connected to the secondary side outlet (11) of the last heat exchanger (1) and the cooling water inlet branch (6), and the output end of the mixer (5) being connected to the cooling water outlet branch (7).

9. A saturated steam dryness measurement device according to claim 8, characterized in that: It also comprises a pressure reducing device (17), one end of which is connected to the input end of the mixer (5), and the other end of which is connected to the secondary side outlet (11) of the last heat exchanger (1).

10. A saturated steam dryness measurement device according to claim 9, characterized in that: The pressure reducing device (17) is configured as a multi-stage pressure reducing orifice plate.

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