Device and method for measuring exhaust steam enthalpy value of low-pressure cylinder of steam turbine

Abstract

The invention discloses a measuring device and a measuring method for the exhaust steam enthalpy value of a low-pressure cylinder of a steam turbine, the measuring device comprises a steam inlet pipe, steam pipes, a first collecting device and a second collecting device, a steam inlet is formed in the steam inlet pipe, the steam inlet is communicated with the low-pressure cylinder, a plurality of steam pipes are arranged in parallel, each steam pipe is communicated with the steam inlet pipe, and the first collecting device is communicated with the second collecting device. The first collecting device is connected to at least one of the multiple steam pipes in series, a first cavity is formed in the first collecting device and communicated with the steam pipes, the second collecting device is connected to at least two of the multiple steam pipes in series, a second cavity and a third cavity are formed in the second collecting device, the second cavity is communicated with the steam pipes, and the third cavity is communicated with the steam pipes. And the third cavity is communicated with the steam pipe. According to the measuring device, the steam in the first collecting device and the second collecting device is subjected to thermodynamic calculation, so that the accurate enthalpy value of the exhaust steam of the low-pressure cylinder is obtained, and the efficiency of the low-pressure cylinder is monitored in real time and the operation of the low-pressure cylinder is optimized and adjusted.

Description

Technical Field

[0001] The present invention relates to the technical field of steam turbines, and in particular, to a measuring device and a measuring method for the exhaust enthalpy value of a low-pressure cylinder of a steam turbine. Background Art

[0002] Related technologies indicate that water vapor is a working medium commonly used in industrial production to convert thermal energy into mechanical energy. To quantify how much heat can be converted into work by water vapor in the heat-work conversion, an important physical quantity of water vapor, enthalpy, is required. For the following physical states of water: unsaturated water, saturated water, saturated wet steam, dry saturated steam, and superheated steam, only the enthalpy value of saturated wet steam cannot be determined under the conditions of known pressure and temperature, and a third physical quantity, such as dryness, needs to be determined. Dryness is the proportion of dry saturated steam in the total mass of saturated wet steam in saturated wet steam.

[0003] Most of the steam turbines used in thermal power plants that use water and water vapor as heat-work conversion working media are designed such that the water vapor state at the outlet of the last stage of the low-pressure cylinder is wet saturated steam. Therefore, the enthalpy value of the water vapor at the outlet of the last stage of the low-pressure cylinder cannot be directly obtained from the pressure and temperature measured by thermal elements, and the dryness of the wet saturated steam needs to be measured and calculated. Currently, in actual production sites or performance tests of steam turbines, to obtain the enthalpy value of the water vapor at the outlet of the last stage of the low-pressure cylinder, it is necessary to calculate the thermal system of the entire steam turbine to obtain the steam flow rate and heat at the outlet of the last stage of the low-pressure cylinder, and then divide the heat by the flow rate to obtain the enthalpy value of the outlet of the last stage of the low-pressure cylinder (UEEP).

[0004] Since the steam flow rates leaked from the main steam valve, governing valve, intermediate-pressure main steam valve, shaft seal, etc. of the steam turbine cannot be measured, and even if they can be measured, there will be deviations in the data. There will also be calculation or measurement errors in the calculation of the feedwater regeneration system, resulting in the fact that the final exhaust steam flow rate and heat obtained through thermal calculation are data accumulated after all calculation and measurement errors. This makes the enthalpy value of the exhaust steam of the low-pressure cylinder obtained by dividing the exhaust steam heat and flow rate through thermal calculation very inaccurate, resulting in a large error and low accuracy in the calculated value of the UEEP efficiency of the low-pressure cylinder, which cannot meet the production and test requirements. Therefore, in actual production or performance tests of steam turbines, there is an urgent need to find a method or device that can accurately obtain the enthalpy value of the exhaust steam of the low-pressure cylinder, realize real-time monitoring of the efficiency of the low-pressure cylinder and optimization adjustment of operation, and verify the accuracy of the UEEP enthalpy value obtained through thermal calculation in steam turbine performance tests. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a measuring device for the exhaust enthalpy value of a low-pressure cylinder of a steam turbine, which can realize real-time monitoring of the low-pressure cylinder efficiency and operation optimization adjustment to verify the accuracy of the steam turbine performance.

[0006] The present invention also provides a method for measuring the exhaust enthalpy value of a low-pressure cylinder of a steam turbine.

[0007] The measuring device for the exhaust enthalpy value of a low-pressure cylinder of a steam turbine according to the first aspect of the present invention includes: an inlet steam pipe, an inlet steam port is formed on the inlet steam pipe, and the inlet steam port is communicated with the low-pressure cylinder; a steam passage pipe, there are a plurality of the steam passage pipes, the plurality of steam passage pipes are arranged in parallel, and each steam passage pipe is communicated with the inlet steam pipe; a first collection device, the first collection device is connected in series to at least one of the plurality of steam passage pipes, a first chamber is formed in the first collection device, and the first chamber is communicated with the steam passage pipe; a second collection device, the second collection device is connected in series to at least two of the other of the plurality of steam passage pipes, a second chamber and a third chamber are formed in the second collection device, the second chamber is communicated with one of the at least two other steam passage pipes, and the third chamber is communicated with the other of the at least two other steam passage pipes.

[0008] According to the measuring device for the exhaust enthalpy value of a low-pressure cylinder of a steam turbine of the present invention, by performing thermodynamic calculations on the steam in the first collection device and the second collection device, the accurate enthalpy value of the low-pressure cylinder exhaust can be obtained, realizing real-time monitoring of the low-pressure cylinder efficiency and operation optimization adjustment to verify the accuracy of the steam turbine performance, improving the accuracy of the results, and achieving the optimal operation of the low-pressure cylinder under all working conditions.

[0009] In some embodiments, the second collection device includes: a linkage piston, one end of the linkage piston is arranged in the second chamber, the other end of the linkage piston is arranged in the third chamber, and the linkage piston can move relative to the second chamber and the third chamber simultaneously.

[0010] In some embodiments, the steam passage pipe includes:

[0011] a first pipe, the first pipe is connected to the second collection device and communicated with the second chamber;

[0012] a second pipe, the second pipe is connected to the first collection device and communicated with the first chamber;

[0013] a third pipe, the third pipe is connected to the first collection device and communicated with the first chamber;

[0014] a fourth pipe, the fourth pipe is connected to the second collection device and communicated with the third chamber;

[0015] The fifth pipe, which is connected to the second collection device and communicates with the third chamber.

[0016] In some embodiments, a first valve is connected in series on the first pipe, a second valve is connected in series on the second pipe, a third valve is connected in series on the third pipe, a fourth valve is connected in series on the fourth pipe, and a fifth valve is connected in series on the fifth pipe.

[0017] In some embodiments, the first collection device includes a first heating element for heating the steam in the first chamber; the second collection device includes a second heating element for heating the steam in the third chamber.

[0018] In some embodiments, the first collection device further includes a sixth valve and a seventh valve. The sixth valve is connected in series to the air pipe and is used to control the connection and disconnection between the first chamber and the atmosphere. The seventh valve is connected in series to the water discharge pipe and is used to control the water discharge connection and disconnection of the first chamber.

[0019] In some embodiments, the measuring device further includes: a condenser and an exhaust pipe. The exhaust pipe is connected between the second collection device and the condenser, and an eighth valve is connected in series on the exhaust pipe. The eighth valve is used to control the connection and disconnection of the exhaust pipe.

[0020] In some embodiments, the steam pipe further includes: a sixth pipe, which is connected between the condenser and the steam inlet pipe, and the exhaust pipe is connected to the sixth pipe.

[0021] According to the method for measuring the exhaust enthalpy value of the low-pressure cylinder of a steam turbine according to the second aspect of the present invention, the measuring method is applied to the measuring device described in the first aspect of the above invention of the present invention. The measuring method includes:

[0022] Step S1: Turn on the first heating element and the second heating element to heat the first chamber and the third chamber, and stop heating when the temperature reaches the exhaust temperature of the low-pressure cylinder of the steam turbine.

[0023] Step S2: Turn on the first valve, the second valve, the third valve, the fourth valve, the fifth valve and the eighth valve, and close the second valve, the third valve, the fourth valve and the fifth valve after reaching the target duration.

[0024] Step S3: Turn on the sixth valve and close the sixth valve after the pressure in the first chamber reaches the target pressure.

[0025] Step S4: Turn on the first heating element and the second heating element to heat the steam in the first chamber and the steam in the third chamber.

[0026] The measurement method for the exhaust enthalpy value of the low-pressure cylinder of a steam turbine according to the present invention is applied to the measurement device according to the first aspect of the present invention above, so as to realize the real-time monitoring of the UEEP efficiency of the low-pressure cylinder, provide a digital basis for improving the steam turbine efficiency and reducing the heat consumption rate of the steam turbine by adjusting the parameters of the steam turbine in real time during operation, and can complete the optimization curve of adjusting each parameter through the data accumulation of the parameters affecting the low-pressure cylinder efficiency, so as to realize the optimal operation of the low-pressure cylinder under all working conditions; it can also prove the correctness of the calculated value of the exhaust enthalpy of the low-pressure cylinder in the performance test of the steam turbine, and at the same time provide and accumulate data for the unit performance detection, energy conservation and consumption reduction, and the determination of maintenance items.

[0027] In some embodiments, the target duration is 5 min - 10 min, and / or the target pressure is the atmospheric pressure at the location where the first collection device is located.

[0028] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of a measurement device for the exhaust enthalpy value of the low-pressure cylinder of a steam turbine according to an embodiment of the first aspect of the present invention;

[0030] Figure 2 is a flowchart of the measurement method according to an embodiment of the second aspect of the present invention.

[0031] Reference Signs:

[0032] 100, measurement device;

[0033] 1, first collection device; 101, first chamber;

[0034] 2, second collection device; 201, second chamber; 202, third chamber;

[0035] 3, first pipe; 4, second pipe; 5, third pipe; 6, fourth pipe; 7, fifth pipe; 8, sixth pipe;

[0036] 9, first valve; 10, second valve; 11, third valve; 12, fourth valve; 13, fifth valve; 14, sixth valve; 15, seventh valve; 16, eighth valve;

[0037] 17, linkage piston; 18, first heating element; 19, second heating element;

[0038] 20, condenser; 21, exhaust pipe; 22, drain pipe; 23, air pipe;

[0039] 200, low-pressure cylinder. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0041] Reference will be made below to Figure 1 describe a measuring device 100 for the exhaust enthalpy value of a low-pressure cylinder of a steam turbine according to an embodiment of the first aspect of the present invention.

[0042] As Figure 1 shown, the measuring device 100 for the exhaust enthalpy value of a low-pressure cylinder of a steam turbine according to an embodiment of the first aspect of the present invention includes: an inlet steam pipe, a steam passage pipe, a first collecting device 1, and a second collecting device 2.

[0043] Specifically, the inlet steam pipe is formed with an inlet steam port, and the inlet steam port is communicated with the low-pressure cylinder 200. The steam passage pipes include a plurality of them, and the plurality of steam passage pipes are arranged in parallel, and each steam passage pipe is communicated with the inlet steam pipe. The first collecting device 1 is connected in series to at least one of the plurality of steam passage pipes. A first chamber 101 is formed in the first collecting device 1, and the first chamber 101 is communicated with the steam passage pipe. The second collecting device 2 is connected in series to at least two of the plurality of steam passage pipes. A second chamber 201 and a third chamber 202 are formed in the second collecting device 2. The second chamber 201 is communicated with one of the at least two other steam passage pipes, and the third chamber 202 is communicated with the other of the at least two other steam passage pipes.

[0044] It can be understood that the plurality of steam passage pipes are all communicated with the inlet steam pipe, the first collecting device 1, and the second collecting device 2. High-temperature steam flows into the first collecting device 1 and the second collecting device 2 through the inlet steam pipe and the steam passage pipes. The first collecting device 1 has a first chamber 101, and the second collecting device 2 has a second chamber 201 and a third chamber 202. The second chamber 201 and the third chamber 202 are not communicated, and the volumes of the second chamber 201 and the third chamber 202 can change simultaneously. When the volume of the second chamber 201 becomes smaller, the volume of the third chamber 202 increases. When the volume of the second chamber 201 becomes larger, the volume of the third chamber 202 becomes smaller. The accuracy of the enthalpy value of the exhaust steam per unit mass of the low-pressure cylinder 200 of the steam turbine is judged by performing a thermodynamic calculation on the steam in the first collecting device 1 and the second collecting device 2.

[0045] The measuring device 100 for the exhaust enthalpy value of the low-pressure cylinder of a steam turbine according to an embodiment of the present invention calculates the heat of the steam in the first collecting device 1 and the second collecting device 2, so as to obtain the accurate enthalpy value of the exhaust of the low-pressure cylinder 200, realize the real-time monitoring of the efficiency of the low-pressure cylinder 200 and the optimization adjustment of the operation, verify the accuracy of the performance of the steam turbine, improve the accuracy of the result, and realize the optimal operation of the low-pressure cylinder 200 under all working conditions.

[0046] In some embodiments of the present invention, as Figure 1 shown, the second collecting device 2 includes: a linkage piston 17, one end of the linkage piston 17 is arranged in the second chamber 201, the other end of the linkage piston 17 is arranged in the third chamber 202, and the linkage piston 17 can move relative to the second chamber 201 and the third chamber 202 simultaneously. It can be understood that by setting the linkage piston 17, the volumes of the second chamber 201 and the third chamber 202 can be adjusted simultaneously. When the volume of the second chamber 201 becomes smaller, the volume of the third chamber 202 increases; when the volume of the second chamber 201 becomes larger, the volume of the third chamber 202 decreases. The structural design of the second collecting device 2 is ingenious and can realize accurate enthalpy value calculation.

[0047] In some embodiments of the present invention, as Figure 1 shown, the steam pipe includes: a first pipe 3, the first pipe 3 is connected to the second collecting device 2 and communicates with the second chamber 201; a second pipe 4, the second pipe 4 is connected to the first collecting device 1 and communicates with the first chamber 101; a third pipe 5, the third pipe 5 is connected to the first collecting device 1 and communicates with the first chamber 101; a fourth pipe 6, the fourth pipe 6 is connected to the second collecting device 2 and communicates with the third chamber 202; a fifth pipe 7, the fifth pipe 7 is connected to the second collecting device 2 and communicates with the third chamber 202. Thus, arranging multiple steam pipes facilitates controlling the steam inlet volume in the first collecting device 1 and the second collecting device 2, ensuring the accuracy of the measurement result.

[0048] In some embodiments of the present invention, a first valve 9 is connected in series on the first pipe 3, a second valve 10 is connected in series on the second pipe 4, a third valve 11 is connected in series on the third pipe 5, a fourth valve 12 is connected in series on the fourth pipe 6, and a fifth valve 13 is connected in series on the fifth pipe 7. Thus, by setting the first valve 9, the second valve 10, the third valve 11, the fourth valve 12 and the fifth valve 13, it is convenient to control the first pipe 3, the second pipe 4, the third pipe 5, the fourth pipe 6 and the fifth pipe 7, reducing the control difficulty of the measuring device 100.

[0049] In some embodiments of the present invention, the first collection device 1 includes a first heating element 18, and the first heating element 18 is used to heat the steam in the first chamber 101; the second collection device 2 includes a second heating element 19, and the second heating element 19 is used to heat the steam in the third chamber 202. Thus, by providing the first heating element 18 and the second heating element 19, the first collection device 1 and the second collection device 2 are heated.

[0050] In some embodiments of the present invention, the first collection device 1 further includes a sixth valve 14 and a seventh valve 15. The sixth valve 14 is connected in series to the atmosphere pipe 23, and the sixth valve 14 is used to control the connection and disconnection between the first chamber 101 and the atmosphere. The seventh valve 15 is connected in series to the drain pipe 22, and the seventh valve 15 is used to control the drainage connection and disconnection of the first chamber 101. Thus, by providing the sixth valve 14 and the seventh valve 15, it is convenient to control the first collection device 1, and the control difficulty of the measuring device 100 is reduced.

[0051] In some embodiments of the present invention, the measuring device 100 for the exhaust enthalpy value of the low-pressure cylinder 200 of the steam turbine further includes: a condenser 20 and an exhaust pipe 21. The exhaust pipe 21 is connected between the second collection device 2 and the condenser 20, and an eighth valve 16 is connected in series to the exhaust pipe 21. The eighth valve 16 is used to control the connection and disconnection of the exhaust pipe 21. Thus, the design of the measuring device 100 is ingenious. By providing the eighth valve 16, the operation difficulty of the measuring device 100 is reduced, which is convenient for the operator to control.

[0052] In some embodiments of the present invention, the steam pipe further includes: a sixth pipe 8. The sixth pipe 8 is connected between the condenser 20 and the steam inlet pipe, and the exhaust pipe 21 is connected to the sixth pipe 8. Thus, it is convenient for the condensed water to flow out of the measuring device 100 to ensure the accuracy of the next measurement result and improve the measurement accuracy.

[0053] According to the method for measuring the exhaust enthalpy value of the low-pressure cylinder of the steam turbine according to the second aspect embodiment of the present invention, the measuring method is applied to the measuring device 100 according to the first aspect embodiment of the present invention as Figure 2 shown, and the measuring method includes:

[0054] Step S1: Turn on the first heating element 18 and the second heating element 19 to heat the first chamber 101 and the third chamber 202, and stop heating when the temperature reaches the exhaust temperature of the low-pressure cylinder 200 of the steam turbine;

[0055] Step S2: Turn on the first valve 9, the second valve 10, the third valve 11, the fourth valve 12, the fifth valve 13, and the eighth valve 16, and close the second valve 10, the third valve 11, the fourth valve 12, and the fifth valve 13 after reaching the target duration;

[0056] Step S3: Turn on the sixth valve 14, and close the sixth valve 14 after the pressure in the first chamber 101 reaches the target pressure;

[0057] Step S4: Turn on the first heating element 18 and the second heating element 19 to heat the steam in the first chamber 101 and the steam in the third chamber 202.

[0058] It can be understood that in Step S1, the first heating element 18 and the second heating element 19 are turned on to heat the first chamber 101 and the third chamber 202 until the temperature of the exhaust steam from the low-pressure cylinder 200 of the steam turbine stops heating, so as to prevent the formation of drain water when the steam enters the first chamber 101 and the third chamber 202.

[0059] Step S2: Turn on the first valve 9, the second valve 10, the third valve 11, the fourth valve 12, the fifth valve 13 and the eighth valve 16 simultaneously, and close the second valve 10, the third valve 11, the fourth valve 12 and the fifth valve 13 after reaching the target duration. Since the absolute pressure of the condenser 20 is less than the absolute pressure of the exhaust cylinder, under the action of the pressure difference, the steam enters the first chamber 101, the second chamber 201 and the third chamber 202 and flows into the condenser 20 along the steam pipe. After stable operation for 5 to 10 minutes, after closing the second valve 10, the third valve 11, the fourth valve 12 and the fifth valve 13 simultaneously, the first collecting device 1 and the second collecting device 2 store the same mass of steam.

[0060] Step S3: Open the sixth valve 14 to connect the first chamber 101 with the external atmosphere, and close the sixth valve 14 after the pressure in the first chamber 101 reaches the target pressure. When the pressure in the first chamber 101 is equal to the atmospheric pressure, close the sixth valve 14. When the pressure in the first chamber 101 is less than the atmospheric pressure, open the sixth valve 14. The pressure in the first chamber 101 becomes the atmospheric pressure, and the steam in the first chamber 101 cools into water. The first collecting device 1 is provided with a dryness and humidity sensor. When the dryness and humidity sensor does not change, open the seventh valve 15 to discharge the condensed water of the steam in the first chamber 101 and measure its mass.

[0061] Step S4: Turn on the first heating element 18 and the second heating element 19 to heat the steam in the first chamber 101 and the steam in the third chamber 202, and heat the steam in the third chamber 202 into superheated steam. Since the internal pressure of the second chamber 201 has been maintained at the exhaust pressure of the low-pressure cylinder 200, during the heating process of the steam in the third chamber 202 by the second heating element 19, the linkage piston 17 moves towards the second chamber 201 to keep the pressure in the third chamber 202 unchanged. A pressure sensor and a temperature sensor are provided in the third chamber 202, and the electric energy of the second heating element 19 is measured by a wattmeter in the connected circuit.

[0062] Finally, it should be understood that the sixth valve 14 is closed, the first chamber 101 is heated to the exhaust temperature again, and then the second valve 10, the third valve 11, the fourth valve 12, and the fifth valve 13 are opened. The steam introduced cools the third chamber 202 to the exhaust temperature, and the linkage piston 17 is restored to the position where the volume of the second chamber 202 is the same as the volume of the third chamber 202.

[0063] According to the method for measuring the exhaust enthalpy value of the low-pressure cylinder of a steam turbine according to an embodiment of the present invention, the measuring method is applied to the measuring device 100 according to the first aspect embodiment of the present invention above, so as to realize the real-time monitoring of the UEEP efficiency of the low-pressure cylinder, provide a digital basis for improving the steam turbine efficiency by adjusting the parameters of the steam turbine in real time during operation and reducing the heat consumption rate of the steam turbine, and can complete the optimization curve of adjusting each parameter through the data accumulation of the parameters affecting the efficiency of the low-pressure cylinder 200, so as to realize the optimal operation of the low-pressure cylinder 200 under all working conditions; it can also prove the correctness of the calculated exhaust enthalpy value of the low-pressure cylinder 200 in the performance test of the steam turbine, and at the same time provide and accumulate data for the unit performance detection, energy conservation and consumption reduction, and the determination of maintenance items.

[0064] In some embodiments of the present invention, the target duration is 5 min - 10 min, and the target pressure is the atmospheric pressure at the location where the first collection device 1 is located.

[0065] The following explains the measurement principle:

[0066] Unsaturated wet steam is composed of saturated water and saturated steam. When unsaturated wet steam is heated at constant pressure to become superheated steam, its heat absorption consists of the following two parts:

[0067] 1. After the saturated water in the saturated wet steam absorbs the latent heat of vaporization to become saturated steam, it continues to absorb heat to become superheated steam;

[0068] 2. The saturated steam in the saturated wet steam absorbs heat to become superheated steam.

[0069] During the constant-pressure heating process, the volume of the third chamber expands, and the heat equivalent of the external work done is the heat released by the third chamber to the outside.

[0070] Here, let Q 1 be the mass of saturated water in the wet saturated steam, Q 2 be the mass of saturated steam in the wet saturated steam, the total mass of steam in the third chamber is Q, and the heat of electric heating is q.

[0071] The saturated water Q 1 in the wet saturated steam needs to absorb the latent heat of vaporization to become saturated steam under constant pressure.

[0072] The heat absorption is:

[0073] q 1 = Q1 ×(h” - h’) (1)

[0074] Where: q 1 -- is the heat absorption when saturated water absorbs heat to become saturated steam

[0075] h” -- is the enthalpy of saturated steam at the corresponding pressure

[0076] h’ -- is the enthalpy of saturated water at the corresponding pressure

[0077] Since the steam in the third chamber is continuously heated at a constant pressure, and the temperature remains unchanged during the process of saturated water in the steam being heated to saturated steam at a constant pressure, the values of h” and h’ can be conveniently obtained from the thermodynamic elements that measure the pressure and temperature in the third chamber before electrical heating.

[0078] The saturated water Q in wet saturated steam 1 Absorbs heat to become saturated steam Q1 and then continues to absorb heat to become superheated steam

[0079] The heat absorption is:

[0080] q 2 = Q 1 ×(h - h”) (2)

[0081] Where: q 2 -- is the heat absorption when saturated steam absorbs heat to become superheated steam

[0082] h -- is the enthalpy of superheated steam at the corresponding pressure and temperature

[0083] The enthalpy value of superheated steam can be conveniently obtained from the pressure and temperature measurement points added in the third chamber after the heating in the third chamber is completed

[0084] The saturated steam Q in wet saturated steam 2 Absorbs heat to become superheated steam Q 2 .

[0085] The heat absorption is:

[0086] q 3 = Q 2 ×(h - h”) (3)

[0087] Where: q 3 -- is the heat absorption when saturated steam absorbs heat to become superheated steam

[0088] h -- is the enthalpy of superheated steam at the corresponding pressure and temperature

[0089] The work done by the steam in the third chamber is completed at a constant pressure. Therefore, the work done by the steam in the third chamber during constant-pressure heating is:

[0090] w = p×ΔV (4)

[0091] Where: p -- is the constant pressure heating pressure

[0092] ΔV -- is the change in the volume of the third chamber from the start of heating expansion to the end of heating of the linkage piston. This can be obtained from the design dimensions of the third chamber and the linkage piston

[0093] w -- is the work done externally

[0094] From the above equations (1)-(4) and the known electrical heating quantities q, Q 1 and Q 2 and the relationship of the total steam mass Q, according to the law of conservation and conversion of energy in the first law of thermodynamics, a system of binary linear equations can be obtained as follows:

[0095] Q 1 + Q 2 = Q (5)

[0096] q 1 + q 2 + q 3 + w = q (6)

[0097] By solving equations (5) and (6), the values of Q 1 and Q 2 can be obtained. According to the definition of the dryness of the unsaturated steam, the values of Q 1 and Q 2 are obtained, and thus the dryness of the steam is obtained, and the enthalpy value of the wet saturated steam is also obtained.

[0098] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0099] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0100] In the present invention, unless otherwise clearly specified or limited, the terms "mounted", "connected", "coupled", "fixed", etc. shall be construed broadly. For example, it may be a fixed connection, a detachable connection, or an integral body; it may be a mechanical connection, an electrical connection, or a communication connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0101] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0102] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A device for measuring the exhaust enthalpy value of a low-pressure cylinder of a steam turbine, characterized in that: include: A steam inlet pipe, wherein the steam inlet pipe is formed with a steam inlet port, and the steam inlet port is communicated with the low-pressure cylinder; A steam pipe, wherein the steam pipe comprises a plurality of steam pipes, the plurality of steam pipes are arranged in parallel, and each of the steam pipes is connected to the steam inlet pipe; a first collecting device, the first collecting device being connected in series to at least one of the plurality of steam pipes, a first cavity being formed in the first collecting device, the first cavity being communicated with the steam pipe; A second collecting device, the second collecting device is connected in series to at least two of the multiple steam pipes, a second cavity and a third cavity are formed in the second collecting device, the second cavity is connected to one of the at least two steam pipes, and the third cavity is connected to the other of the at least two steam pipes.

2. The device for measuring the exhaust enthalpy of a low-pressure cylinder of a steam turbine according to claim 1, characterized in that: The second collecting device comprises: a linkage piston, one end of which is arranged in the second chamber, the other end of which is arranged in the third chamber, and the linkage piston can move relative to the second chamber and the third chamber at the same time.

3. The device for measuring the exhaust enthalpy of a low-pressure cylinder of a steam turbine according to claim 2, characterized in that: The steam pipe comprises: a first tube connected to the second collecting device and communicating with the second chamber; a second tube connected to the first collecting device and communicating with the first chamber; a third tube, the third tube being connected to the first collecting device and communicating with the first chamber; a fourth tube, the fourth tube being connected to the second collecting device and communicating with the third chamber; A fifth tube is connected to the second collecting device and communicated with the third chamber.

4. The device for measuring the exhaust enthalpy of a low-pressure cylinder of a steam turbine according to claim 3, characterized in that: The first tube is connected in series with a first valve, the second tube is connected in series with a second valve, the third tube is connected in series with a third valve, the fourth tube is connected in series with a fourth valve, and the fifth tube is connected in series with a fifth valve.

5. The device for measuring the exhaust enthalpy of a low-pressure cylinder of a steam turbine according to any one of claims 1 to 4, characterized in that: The first collecting device includes a first heating element, and the first heating element is used to heat the steam in the first chamber; the second collecting device includes a second heating element, and the second heating element is used to heat the steam in the third chamber.

6. The device for measuring the exhaust enthalpy of a low-pressure cylinder of a steam turbine according to any one of claims 1 to 4, characterized in that: The first collecting device also includes a sixth valve and a seventh valve. The sixth valve is connected in series to the atmospheric pipe and is used to control the connection and disconnection between the first chamber and the atmosphere. The seventh valve is connected in series to the drain pipe and is used to control the connection and disconnection of the drain of the first chamber.

7. The device for measuring the exhaust enthalpy of a low-pressure cylinder of a steam turbine according to any one of claims 1 to 4, characterized in that: Also includes: A condenser and an exhaust pipe, wherein the exhaust pipe is connected between the second collecting device and the condenser, and an eighth valve is connected in series to the exhaust pipe, and the eighth valve is used to control the on-off of the exhaust pipe.

8. The device for measuring the exhaust enthalpy of a low-pressure cylinder of a steam turbine according to claim 7, characterized in that: The steam passage pipe further includes: a sixth pipe, the sixth pipe is connected between the condenser and the steam inlet pipe, and the steam exhaust pipe is connected to the sixth pipe.

9. A method for measuring the exhaust enthalpy value of a low-pressure cylinder of a steam turbine, characterized in that: The measuring method is applied to the measuring device according to any one of claims 1 to 8, and the measuring method comprises: Step S1, turning on the first heating element and the second heating element to heat the first cavity and the third cavity until the temperature of the exhaust steam from the low-pressure cylinder of the steam turbine is reached and then stopping the heating; Step S2, opening the first valve, the second valve, the third valve, the fourth valve, the fifth valve and the eighth valve, and closing the second valve, the third valve, the fourth valve and the fifth valve after reaching the target time; Step S3, opening the sixth valve, and closing the sixth valve after the pressure in the first chamber reaches the target pressure; Step S4, turning on the first heating element and the second heating element to heat the steam in the first chamber and the steam in the third chamber.

10. The method for measuring the exhaust enthalpy value of the low-pressure cylinder of a steam turbine according to claim 9, characterized in that: The target duration is 5 min-10 min, and / or the target pressure is the atmospheric pressure at the location of the first collecting device.

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