High-pressure cylinder split-based combined heat and power generation steam supply system and steam supply node regulation method

Abstract

The application discloses a kind of based on high-pressure cylinder split cylinder's combined heat and power steam supply system and steam supply node regulation and control method, the based on high-pressure cylinder split cylinder's combined heat and power steam supply system, including combined heat and power unit and steam supply pipeline, combined heat and power unit has high-pressure cylinder, high-pressure cylinder includes one-stage high-pressure cylinder and two-stage high-pressure cylinder, the main steam outlet of boiler is connected with the steam inlet of one-stage high-pressure cylinder, the steam outlet of one-stage high-pressure cylinder is connected with the steam inlet of two-stage high-pressure cylinder, the steam outlet of two-stage high-pressure cylinder is connected with the cold re-steam steam inlet of boiler;Steam supply pipeline has first extraction pipeline and second extraction pipeline, the steam extraction end of first extraction pipeline is connected with the steam outlet of one-stage high-pressure cylinder, the steam extraction end of second extraction pipeline is connected with the steam outlet of two-stage high-pressure cylinder.The based on high-pressure cylinder split cylinder's combined heat and power steam supply system of the application embodiment can meet high-pressure industrial steam supply demand, realize the step-by-step utilization of steam, flexible switching steam heat source, realize energy saving and emission reduction.

Description

Technical Field

[0001] This invention belongs to the field of cogeneration technology, specifically relating to a cogeneration steam supply system based on a high-pressure cylinder with separate cylinders and a method for controlling the steam supply nodes. Background Technology

[0002] The commonly used high-pressure industrial steam supply technologies for cogeneration units include four types: cold reheat steam extraction, hot reheat steam extraction, main steam desuperheating and pressure reduction steam supply, and main steam back pressure turbine steam supply.

[0003] For 300MW-class thermal power units, among the relevant technologies, cold resteam extraction and hot resteam extraction steam supply are difficult to provide the industrial parameters of 3MPa and a steam supply of 100t / h under 50% THA conditions; main steam desuperheating and pressure reduction steam supply can meet the high-pressure steam supply demand under low-load conditions, but its economic efficiency is poor and it is difficult to meet the "three-reform" linkage requirements; steam supply through main steam back pressure turbine requires the construction of a new back pressure turbine plant, the purchase of back pressure turbines and related valves, resulting in high upfront investment costs, especially when steam supply demand fluctuates, leading to unstable economic returns. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, embodiments of the present invention propose a cogeneration steam supply system based on a high-pressure cylinder with separate cylinders. This system can meet the steam supply needs of high-pressure industries, realize the cascade utilization of steam energy, flexibly switch steam supply heat sources, and achieve energy conservation and emission reduction.

[0006] An embodiment of the present invention also proposes a method for regulating steam supply nodes.

[0007] The cogeneration steam supply system based on a high-pressure cylinder with separate cylinders according to an embodiment of the present invention includes:

[0008] A combined heat and power (CHP) unit, wherein the CHP unit has a boiler and a high-pressure cylinder, the high-pressure cylinder includes a first-stage high-pressure cylinder and a second-stage high-pressure cylinder, the main steam outlet of the boiler is connected to the steam inlet of the first-stage high-pressure cylinder, the steam outlet of the first-stage high-pressure cylinder is connected to the steam inlet of the second-stage high-pressure cylinder, and the steam outlet of the second-stage high-pressure cylinder is connected to the cold reheat steam inlet of the boiler.

[0009] The steam supply pipeline includes a main pipeline, a first extraction steam pipeline, and a second extraction steam pipeline, wherein the first extraction steam pipeline and the second extraction steam pipeline are connected in parallel to the steam inlet end of the main pipeline.

[0010] The extraction end of the first extraction steam pipeline is connected to the steam outlet end of the first high-pressure cylinder to supply steam to the main pipeline under low load conditions, and the extraction end of the second extraction steam pipeline is connected to the steam outlet end of the second high-pressure cylinder to supply steam to the main pipeline under high load conditions.

[0011] The cogeneration steam supply system based on high-pressure cylinder sub-cylinder of this invention can meet the steam supply needs of high-pressure industries, realize the cascade utilization of steam energy, flexibly switch steam supply heat sources, and achieve energy conservation and emission reduction.

[0012] In some embodiments, a connecting pipe is provided between the first high-pressure cylinder and the second high-pressure cylinder. The main steam of the boiler enters the second high-pressure cylinder through the connecting pipe after being powered by the first high-pressure cylinder. The first extraction steam pipeline is connected to the connecting pipe.

[0013] In some embodiments, the system further includes a first control valve and a second control valve, wherein the first control valve is disposed on the first extraction steam pipeline and the second control valve is disposed on the second extraction steam pipeline.

[0014] In some embodiments, the combined heat and power unit further includes:

[0015] The intermediate pressure cylinder is connected to the steam inlet of the boiler at the hot resteam outlet.

[0016] The low-pressure cylinder has its steam outlet end connected to the steam inlet end of the intermediate-pressure cylinder.

[0017] In some embodiments, the combined heat and power unit further includes:

[0018] A condenser, wherein the steam inlet of the condenser is connected to the steam outlet of the low-pressure cylinder;

[0019] A deaerator is provided, wherein the liquid inlet of the deaerator is connected to the liquid outlet of the condenser, a condensate pump is provided between the liquid inlet of the deaerator and the liquid outlet of the condenser, the liquid outlet of the deaerator is connected to the main steam inlet of the boiler, and a feedwater pump is provided between the liquid outlet of the deaerator and the main steam inlet of the boiler.

[0020] In some embodiments, a low-pressure heater is further provided between the condenser and the deaerator. The low-pressure cylinder is provided with a first steam extraction port, which is connected to the heating medium inlet of the low-pressure heater, and the heating medium outlet of the low-pressure heater is connected to the condenser.

[0021] In some embodiments, there are multiple low-pressure heaters connected in series on a first connecting pipeline between the condenser and the deaerator. The low-pressure cylinder is provided with multiple first steam extraction ports, which are connected one-to-one with the heating medium inlets of the multiple low-pressure heaters. The temperature of the heating medium introduced into the multiple low-pressure heaters gradually increases along the flow direction of the condensate in the first connecting pipeline. In the multiple low-pressure heaters, the heating medium after heat exchange flows in the opposite direction of the condensate flow in the multiple low-pressure heaters in stages, and finally connects to the condenser.

[0022] In some embodiments, a first high-pressure heater, a second high-pressure heater, and a third high-pressure heater are connected in series along the feedwater direction on the second connecting pipe between the liquid outlet of the deaerator and the main steam inlet of the boiler. A second steam extraction port is provided on the first high-pressure cylinder, a third steam extraction port is provided on the second high-pressure cylinder, and a fourth and a fifth steam extraction port are provided on the intermediate-pressure cylinder. The fifth steam extraction port is connected to the steam inlet of the deaerator, the fourth steam extraction port is connected to the heating medium inlet of the first high-pressure heater, the third steam extraction port is connected to the heating medium inlet of the second high-pressure heater, and the second steam extraction port is connected to the heating medium inlet of the third high-pressure heater.

[0023] In some embodiments, the heating medium outlet of the third high-pressure heater is connected to the heating medium inlet of the second high-pressure heater, the heating medium outlet of the second high-pressure heater is connected to the heating medium inlet of the first high-pressure heater, and the heating medium outlet of the first high-pressure heater is connected to the steam inlet of the deaerator.

[0024] In some embodiments, the second steam extraction port is connected to the steam outlet of the first high-pressure cylinder, and the third steam extraction port is connected to the steam outlet of the second high-pressure cylinder.

[0025] The steam supply node control method of this invention is used for parameter control of the extraction node of the cogeneration steam supply system based on the high-pressure cylinder as described above, and includes the following steps:

[0026] Obtain the main steam flow rate;

[0027] Based on the difference in hydrophobicity of the heaters, the heaters in the cogeneration steam supply system based on the high-pressure cylinder are divided into hydrophobic discharge heaters and collection heaters.

[0028] The parameters of each hydrophobic discharge heater are obtained based on equation (1);

[0029]

[0030] The parameters of each collection heater are obtained based on equation (2);

[0031]

[0032] In equations (1) and (2):

[0033] τ j --Enthalpy rise of 1 kg of water in a heater / kJ·kg -1 ;

[0034] q j --Heat release of 1 kg of heating steam in the heater / kJ·kg -1 ;

[0035] γ j --Heat release of 1 kg of hydrophobic material in the heater / kJ·kg -1 ;

[0036] -- Enthalpy of water at heater outlet / kJ·kg -1 ;

[0037] h j -- Extraction enthalpy of heater / kJ·kg -1 ;

[0038] --Enthalpy of condensate discharged from heater / kJ·kg -1 ;

[0039] --Inlet enthalpy of heater water / kJ·kg -1 ;

[0040] --Enthalpy of heater entering the condensate / kJ·kg -1 ;

[0041] Based on the principle of heat balance, the thermodynamic system of the cogeneration steam supply system based on the high-pressure cylinder is iteratively calculated to obtain the main steam work and the parameters and flow rates of the steam and water in each part of the cogeneration steam supply system based on the high-pressure cylinder.

[0042] Calculate the heating parameters of the steam extraction node. If the heating parameters are not met, repeat the above steps iteratively. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of a cogeneration steam supply system based on a high-pressure cylinder with separate cylinders, according to an embodiment of the present invention.

[0044] Figure 2 This is a schematic diagram of a hydrophobic discharge heater in an embodiment of the present invention.

[0045] Figure 3This is a schematic diagram of a collection heater in an embodiment of the present invention.

[0046] 1. Boiler; 11. Main steam outlet; 12. Main steam liquid inlet; 13. Cold reheat steam inlet; 14. Hot reheat steam outlet;

[0047] 21. First-stage high-pressure cylinder; 22. Second-stage high-pressure cylinder; 23. Medium-pressure cylinder; 24. Low-pressure cylinder; 25. Connecting pipe;

[0048] 31. Main pipe; 32. First extraction steam pipe; 33. Second extraction steam pipe; 34. First control valve; 35. Second control valve;

[0049] 4. Condenser; 41. Condensate pump;

[0050] 5. Deaerator; 51. Feedwater pump;

[0051] 61. First low-pressure heater; 62. Second low-pressure heater; 63. Third low-pressure heater; 64. Fourth low-pressure heater;

[0052] 71. First high-pressure heater; 72. Second high-pressure heater; 73. Third high-pressure heater;

[0053] 81. First extraction port; 82. Second extraction port; 83. Third extraction port; 84. Fourth extraction port; 85. Fifth extraction port. Detailed Implementation

[0054] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0055] In the current power grid, renewable energy sources such as wind and solar power account for an increasingly significant proportion. However, these renewable energy sources are intermittent and volatile, posing new challenges to the power grid. Combined heat and power (CHP) units not only need to provide industrial steam but also frequently participate in peak shaving. Under low-load conditions, the steam supply systems in related technologies are insufficient to meet industrial steam demand.

[0056] Therefore, this invention proposes a cogeneration steam supply system based on a high-pressure cylinder with separate cylinders, which can meet the steam supply needs of high-pressure industries, realize the cascade utilization of steam energy, flexibly switch steam supply heat sources, and achieve energy conservation and emission reduction.

[0057] Specifically, the cogeneration steam supply system based on high-pressure cylinder in this embodiment of the invention includes a cogeneration unit and a steam supply pipeline. The cogeneration unit has a boiler 1 and a high-pressure cylinder. The high-pressure cylinder includes a first-stage high-pressure cylinder 21 and a second-stage high-pressure cylinder 22. The main steam outlet 11 of the boiler 1 is connected to the steam inlet of the first-stage high-pressure cylinder 21. The steam outlet of the first-stage high-pressure cylinder 21 is connected to the steam inlet of the second-stage high-pressure cylinder 22. The steam outlet of the second-stage high-pressure cylinder 22 is connected to the cold reheat steam inlet 13 of the boiler 1.

[0058] like Figure 1 As shown, in this embodiment of the invention, industrial steam is provided through a steam supply pipeline. The steam supply pipeline has a main pipeline 31, a first extraction steam pipeline 32, and a second extraction steam pipeline 33. The first extraction steam pipeline 32 and the second extraction steam pipeline 33 are connected in parallel to the steam inlet end of the main pipeline 31. The extraction end of the first extraction steam pipeline 32 is connected to the steam outlet end of a high-pressure cylinder 21 to supply steam to the main pipeline 31 under low load conditions. The extraction end of the second extraction steam pipeline 33 is connected to the steam outlet end of a high-pressure cylinder 22 to supply steam to the main pipeline 31 under high load conditions.

[0059] It should be noted that the steam generated in boiler 1 performs work through the high-pressure cylinder, intermediate-pressure cylinder 23, and low-pressure cylinder 24, thereby driving the generator to generate electricity. By dividing the high-pressure cylinder into a first-stage high-pressure cylinder 21 and a second-stage high-pressure cylinder 22, when the cogeneration unit is under high load conditions, steam is extracted through the first extraction pipeline 32, that is, the cold reheat steam discharged from the exhaust end of the second-stage high-pressure cylinder 22 is used for industrial steam supply. When the cogeneration unit is under low load conditions, steam discharged from the first-stage high-pressure cylinder 21 is extracted through the second extraction pipeline 33, thereby ensuring the stability of industrial steam supply parameters under different operating conditions. When steam is supplied through the exhaust of the first-stage high-pressure cylinder 21, compared with the de-cooling and depressurization of the main steam in related technologies, the unit's work capacity can be increased, and the cascade utilization of steam energy can be realized. This allows for flexible switching of the steam heat source under different operating conditions, achieving the effect of energy saving and emission reduction.

[0060] In some embodiments, a connecting pipe 25 is provided between the first high-pressure cylinder 21 and the second high-pressure cylinder 22. The main steam of the boiler 1 enters the second high-pressure cylinder 22 through the connecting pipe 25 after the first high-pressure cylinder 21 has done work. The first extraction steam pipeline 32 is connected to the connecting pipe 25.

[0061] In other words, a high-pressure cylinder in the relevant technology is divided into two parts, forming a first-stage high-pressure cylinder 21 and a second-stage high-pressure cylinder 22. When steam is not extracted through the second extraction pipe 33, the main steam of boiler 1 enters the first-stage high-pressure cylinder 21 to do work. The exhaust end of the first-stage high-pressure cylinder 21 and the inlet end of the second-stage high-pressure cylinder 22 are connected by a connecting pipe 25. The steam discharged from the exhaust end of the first-stage high-pressure cylinder 21 enters the second-stage high-pressure cylinder 22 through the connecting pipe 25 to continue doing work. The cold reheat steam discharged from the outlet end of the second-stage high-pressure cylinder 22 enters the cold reheat steam inlet end 13 of boiler 1. Under high-load conditions, the extracted cold reheat steam is used as industrial steam. An extraction port is opened on the connecting pipe 25, and the first extraction pipe 32 is connected to the connecting pipe 25 through the extraction port. Under low-load conditions, the first extraction pipe extracts steam from the connecting pipe 25 for industrial steam supply.

[0062] Taking a conventional 350MW supercritical unit (main steam pressure 24.2MPa, main steam temperature 566℃, hot reheat steam temperature 566℃, back pressure set at 4.9kPa) as an example, the high-pressure industrial steam supply parameters during cogeneration are pressure 3MPa, temperature 250℃, and extraction steam rate 100t / h.

[0063] Table 1 compares the steam supply scheme of the first-stage high-pressure cylinder 21 with the main steam supply scheme in related technologies. It summarizes the main performance indicators of the unit under the conditions of industrial steam supply from the exhaust end of the first-stage high-pressure cylinder 21 in this invention and the main steam desuperheating and depressurization steam supply scheme in related technologies. As can be seen from the table, under the main steam parameters corresponding to the pure condensing 75% THA condition, the coal consumption for power generation of the first-stage high-pressure cylinder 21 exhaust steam supply scheme in this invention is 279.4 g / kWh, while the coal consumption for power generation of the main steam supply scheme in related technologies is 287.3 g / kWh. The coal consumption for power generation of the first-stage high-pressure cylinder 21 exhaust steam supply scheme proposed in this invention is reduced by 7.9 g / kWh. Under the main steam parameters corresponding to the pure condensing 50% THA condition, the coal consumption for power generation of the first-stage high-pressure cylinder 21 exhaust steam supply scheme in this invention is 288.1 g / kWh, while the coal consumption for power generation of the main steam supply scheme in related technologies is 302.4 g / kWh. The coal consumption for power generation of the first-stage high-pressure cylinder 21 exhaust steam supply scheme proposed in this invention is reduced by 14.3 g / kWh. Calculations and comparisons show that the cogeneration steam supply system based on high-pressure cylinder splitting proposed in this invention has significant coal-saving benefits.

[0064] Table 1 Comparison of steam supply scheme for the exhaust steam of the high-pressure cylinder 21 in this invention with the main steam supply scheme in related technologies.

[0065]

[0066] In some embodiments, the cogeneration steam supply system based on high-pressure cylinder branching also includes a first control valve 34 and a second control valve 35. The first control valve 34 is located on the first extraction steam pipeline 32, and the second control valve 35 is located on the second extraction steam pipeline 33. By setting the first control valve 34 on the first extraction steam pipeline 32 and the second control valve 35 on the second extraction steam pipeline 33, the conduction or disconnection of the first extraction steam pipeline 32 and the second extraction steam pipeline 33 can be adjusted and controlled, thereby selecting the extraction steam node according to the operating conditions of the cogeneration unit.

[0067] In some embodiments, the cogeneration unit further includes an intermediate-pressure cylinder 23 and a low-pressure cylinder 24. The hot resteam outlet 14 of the boiler 1 is connected to the steam inlet of the intermediate-pressure cylinder 23, and the steam outlet of the intermediate-pressure cylinder 23 is connected to the steam inlet of the low-pressure cylinder 24. Specifically, the cold resteam discharged from the second-stage high-pressure cylinder 22 is reheated by the boiler 1 to form hot resteam, which is then introduced into the intermediate-pressure cylinder 23 to do work. The steam discharged from the steam outlet of the intermediate-pressure cylinder 23 enters the low-pressure cylinder 24 to do work, thereby realizing the full utilization of steam energy.

[0068] In some embodiments, the cogeneration unit further includes a condenser 4 and a deaerator 5. The steam inlet of the condenser 4 is connected to the steam outlet of the low-pressure cylinder 24, and the liquid inlet of the deaerator 5 is connected to the liquid outlet of the condenser 4. A condensate pump 41 is provided between the liquid inlet of the deaerator 5 and the liquid outlet of the condenser 4. The liquid outlet of the deaerator 5 is connected to the main steam inlet 12 of the boiler 1. A feedwater pump 51 is provided between the liquid outlet of the deaerator 5 and the main steam inlet 12 of the boiler 1.

[0069] Specifically, the steam discharged after the low-pressure cylinder 24 performs work is condensed into condensate after passing through the condenser 4. The condensate is pumped to the deaerator 5 by the condensate pump 41 to remove oxygen and other gases, preventing corrosion or erosion of the components of the cogeneration unit. The deaerated condensate is then pumped to the boiler 1 by the feedwater pump 51 to achieve the recycling of condensate.

[0070] In some embodiments, a low-pressure heater is also provided between the condenser 4 and the deaerator 5. A first extraction port 81 is provided on the low-pressure cylinder 24, which is connected to the heating medium inlet of the low-pressure heater. The heating medium outlet of the low-pressure heater is connected to the condenser 4. By providing the low-pressure heater, the steam extracted from the low-pressure cylinder 24 heats the condensate in the low-pressure heater, reducing the heat absorbed by the condensate after it enters the boiler 1. This improves the energy utilization rate of the entire combined heat and power unit and reduces energy loss.

[0071] Furthermore, there are multiple low-pressure heaters connected in series on the first connecting pipeline between the condenser 4 and the deaerator 5. The low-pressure cylinder 24 is provided with multiple first steam extraction ports 81, which are connected one-to-one with the heating medium inlets of the multiple low-pressure heaters. The temperature of the heating medium introduced into the multiple low-pressure heaters gradually increases along the flow direction of the condensate in the first connecting pipeline. In the multiple low-pressure heaters, the heating medium after heat exchange flows in the opposite direction of the condensate flow in the multiple low-pressure heaters step by step, and finally connects to the condenser 4.

[0072] Multiple first steam extraction ports 81 are arranged on the low-pressure cylinder 24, such as two, three or four first steam extraction ports 81. Preferably, four first steam extraction ports 81 are arranged on the low-pressure cylinder 24, and four low-pressure heaters are connected in series on the first connecting pipe. The four low-pressure heaters are arranged sequentially along the condensate flow direction in the first connecting pipe as first low-pressure heater 61, second low-pressure heater 62, third low-pressure heater 63 and fourth low-pressure heater 64. The steam temperature entering the fourth low-pressure heater 64 is the highest, the steam temperature entering the third low-pressure heater 63 is the second highest, and the temperature entering the first low-pressure heater 61 is the lowest. In this way, the condensate in the first connecting pipe can be heated multiple times to improve the energy utilization rate.

[0073] Furthermore, the steam in the fourth low-pressure heater 64 flows into the third low-pressure heater 63 after heat exchange, where it undergoes heat exchange again to recover energy. Similarly, the steam in the third low-pressure heater 63 flows into the second low-pressure heater 62 after heat exchange, and the steam in the second low-pressure heater 62 flows into the first low-pressure heater 61 after heat exchange, thus achieving energy recovery step by step. The steam discharged from the first low-pressure heater 61 enters the condenser 4 to form condensate, which is then recycled.

[0074] In some embodiments, a first high-pressure heater 71, a second high-pressure heater 72, and a third high-pressure heater 73 are connected in series along the water supply direction on the second connecting pipe between the liquid outlet end of the deaerator 5 and the main steam inlet end 12 of the boiler 1. A second steam extraction port 82 is provided on the first high-pressure cylinder 21, a third steam extraction port 83 is provided on the second high-pressure cylinder 22, and a fourth steam extraction port 84 and a fifth steam extraction port 85 are provided on the intermediate-pressure cylinder 23. The fifth steam extraction port 85 is connected to the steam inlet end of the deaerator 5, the fourth steam extraction port 84 is connected to the heating medium inlet of the first high-pressure heater 71, the third steam extraction port 83 is connected to the heating medium inlet of the second high-pressure heater 72, and the second steam extraction port 82 is connected to the heating medium inlet of the third high-pressure heater 73.

[0075] In other words, the feedwater pump 51 transports the deaerated condensate from the deaerator 5 to the boiler 1, realizing the recycling of condensate. To further realize energy recovery and reduce the heat required for the condensate to be converted into steam in the boiler 1, this embodiment of the invention provides a first high-pressure heater 71, a second high-pressure heater 72, and a third high-pressure heater 73 connected in series along the feedwater direction on the second connecting pipeline. The heating medium inlet of the first high-pressure heater 71 is connected to the fourth steam extraction port 84 of the intermediate-pressure cylinder 23, which controls the condensate in the second connecting pipeline. The first heating process involves connecting the heating medium inlet of the second high-pressure heater 72 to the third steam extraction port 83 on the high-pressure cylinder to heat the condensate in the second connecting pipeline for the second time. The heating medium inlet of the third high-pressure heater 73 is connected to the second steam extraction port 82 on the high-pressure cylinder to heat the condensate in the second connecting pipeline for the third time. In addition, the fifth steam extraction port 85 on the intermediate-pressure cylinder 23 is connected to the steam inlet of the deaerator 5 to drive the deaerator 5 to work and deoxygenate the condensate transported to the deaerator 5 from the first connecting pipeline.

[0076] Furthermore, the heating medium outlet of the third high-pressure heater 73 is connected to the heating medium inlet of the second high-pressure heater 72, the heating medium outlet of the second high-pressure heater 72 is connected to the heating medium inlet of the first high-pressure heater 71, and the heating medium outlet of the first high-pressure heater 71 is connected to the steam inlet of the deaerator 5.

[0077] Specifically, in order to improve the utilization rate of heat in the steam, the steam discharged from the third high-pressure heater 73 enters the second high-pressure heater 72 for energy recovery, the steam discharged from the second high-pressure heater 72 enters the first high-pressure heater 71 for energy recovery, and the steam discharged from the first high-pressure heater 71 enters the deaerator 5 to make the deaerator 5 work.

[0078] In some other embodiments, the second steam extraction port 82 is connected to the steam outlet of the first high-pressure cylinder 21, and the third steam extraction port 83 is connected to the steam outlet of the second high-pressure cylinder 22.

[0079] The steam supply node control method of this invention is used for parameter control of the extraction node of the cogeneration steam supply system based on the high-pressure cylinder as described above, and includes the following steps:

[0080] To obtain the main steam flow rate, specifically, the main steam flow rate is obtained through iterative calculation using the Freuger formula.

[0081] Based on the difference in hydrophobicity of the heaters, the heaters in the cogeneration steam supply system based on the high-pressure cylinder are divided into hydrophobic discharge heaters and collection heaters. Specifically, as follows: Figure 2 and Figure 3As shown, calculations based on energy balance and mass balance categorize the parameters of the thermodynamic system into three types: the first being the enthalpy rise of the feedwater in the heater, expressed as τ. j The second is the heat released by the steam in the heater, expressed as q. j The third aspect is the heat release from the hydrophobic element in the heater, expressed as γ. j It is indicated that, among them, the condensate discharge heater belongs to the surface heater type, and its condensate discharge method is staged gravity flow; the collection heater includes the mixing heater and the surface heater with condensate pump.

[0082] The parameters of each hydrophobic discharge heater are obtained based on equation (1);

[0083]

[0084] The parameters of each collection heater are obtained based on equation (2);

[0085]

[0086] In equations (1) and (2):

[0087] τ j --Enthalpy rise of 1 kg of water in a heater / kJ·kg -1 ;

[0088] q j --Heat release of 1 kg of heating steam in the heater / kJ·kg -1 ;

[0089] γ j --Heat release of 1 kg of hydrophobic material in the heater / kJ·kg -1 ;

[0090] -- Enthalpy of water at heater outlet / kJ·kg -1 ;

[0091] h j -- Extraction enthalpy of heater / kJ·kg -1 ;

[0092] --Enthalpy of condensate discharged from heater / kJ·kg -1 ;

[0093] --Inlet enthalpy of heater water / kJ·kg -1 ;

[0094] --Enthalpy of heater entering the condensate / kJ·kg -1 .

[0095] Based on the principle of heat balance, the thermal system of the cogeneration steam supply system based on the high-pressure cylinder is iteratively calculated to obtain the main steam work and the parameters and flow rates of steam and water in each part of the cogeneration steam supply system based on the high-pressure cylinder. Furthermore, economic indicators such as heat consumption rate, steam consumption rate, thermal efficiency and coal consumption rate can also be obtained.

[0096] After completing the thermal system iteration, the heating parameters of the extraction steam node are calculated. If the heating parameters are not met, the above iteration steps are repeated.

[0097] This invention divides the traditional high-pressure cylinder into two high-pressure cylinders, enabling the cascade utilization of steam energy to meet the demand for high-pressure industrial steam supply, thereby achieving energy conservation and emission reduction. The beneficial effects achieved by the embodiments of this invention are: (1) Under low-load conditions, compared with the main steam de-cooling and de-pressure heating, this invention can achieve cascade utilization of energy, energy conservation and emission reduction. For a conventional 350MW ultra-supercritical unit, under the main steam parameters corresponding to the pure condensing 50% THA condition, the power generation coal consumption of the high-pressure cylinder 1-stage exhaust steam heating scheme proposed in this invention is reduced by 14.3g / kWh; (2) Compared with the limitation of the limited extraction steam volume of the regenerative system 1 in related technologies, this invention drills holes in the connecting pipe between the first-stage high-pressure cylinder and the second-stage high-pressure cylinder to extract steam, significantly increasing the extraction steam volume, which can meet the demand of 100t / h for high-pressure industrial steam supply extraction; (3) This invention consists of two-stage extraction steam sources: cold reheat steam and exhaust steam from the first-stage high-pressure cylinder, which can flexibly switch the heating steam source according to the unit's electrical load.

[0098] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0099] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0100] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0101] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0102] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0103] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A cogeneration steam supply system based on a high-pressure cylinder with separate cylinders, characterized in that, include: A combined heat and power (CHP) unit, wherein the CHP unit has a boiler and a high-pressure cylinder, the high-pressure cylinder includes a first-stage high-pressure cylinder and a second-stage high-pressure cylinder, the main steam outlet of the boiler is connected to the steam inlet of the first-stage high-pressure cylinder, the steam outlet of the first-stage high-pressure cylinder is connected to the steam inlet of the second-stage high-pressure cylinder, and the steam outlet of the second-stage high-pressure cylinder is connected to the cold reheat steam inlet of the boiler. The steam supply pipeline includes a main pipeline, a first extraction steam pipeline, and a second extraction steam pipeline, wherein the first extraction steam pipeline and the second extraction steam pipeline are connected in parallel to the steam inlet end of the main pipeline. The extraction end of the first extraction steam pipeline is connected to the steam outlet end of the first high-pressure cylinder to supply steam to the main pipeline under low load conditions, and the extraction end of the second extraction steam pipeline is connected to the steam outlet end of the second high-pressure cylinder to supply steam to the main pipeline under high load conditions.

2. The cogeneration steam supply system based on a high-pressure cylinder with separate cylinders according to claim 1, characterized in that, A connecting pipe is provided between the first high-pressure cylinder and the second high-pressure cylinder. The main steam of the boiler enters the second high-pressure cylinder through the connecting pipe after being powered by the first high-pressure cylinder. The first extraction steam pipeline is connected to the connecting pipe.

3. The cogeneration steam supply system based on a high-pressure cylinder with separate cylinders according to claim 1, characterized in that, It also includes a first control valve and a second control valve, the first control valve being located on the first extraction steam pipeline and the second control valve being located on the second extraction steam pipeline.

4. The cogeneration steam supply system based on a high-pressure cylinder with separate cylinders according to any one of claims 1-3, characterized in that, The combined heat and power unit also includes: The intermediate pressure cylinder is connected to the steam inlet of the boiler at the hot resteam outlet. The low-pressure cylinder has its steam outlet end connected to the steam inlet end of the intermediate-pressure cylinder.

5. The cogeneration steam supply system based on a high-pressure cylinder with separate cylinders according to claim 4, characterized in that, The combined heat and power unit also includes: A condenser, wherein the steam inlet of the condenser is connected to the steam outlet of the low-pressure cylinder; A deaerator is provided, wherein the liquid inlet of the deaerator is connected to the liquid outlet of the condenser, a condensate pump is provided between the liquid inlet of the deaerator and the liquid outlet of the condenser, the liquid outlet of the deaerator is connected to the main steam inlet of the boiler, and a feedwater pump is provided between the liquid outlet of the deaerator and the main steam inlet of the boiler.

6. The cogeneration steam supply system based on a high-pressure cylinder with separate cylinders according to claim 5, characterized in that, A low-pressure heater is also provided between the condenser and the deaerator. The low-pressure cylinder is provided with a first steam extraction port, which is connected to the heating medium inlet of the low-pressure heater. The heating medium outlet of the low-pressure heater is connected to the condenser.

7. The cogeneration steam supply system based on a high-pressure cylinder with separate cylinders according to claim 6, characterized in that, There are multiple low-pressure heaters, which are connected in series on the first connecting pipeline between the condenser and the deaerator. The low-pressure cylinder is provided with multiple first steam extraction ports, which are connected one-to-one with the heating medium inlets of the multiple low-pressure heaters. The temperature of the heating medium introduced into the multiple low-pressure heaters gradually increases along the flow direction of the condensate in the first connecting pipeline. In the multiple low-pressure heaters, the heating medium after heat exchange flows in the opposite direction of the condensate flow in the multiple low-pressure heaters in stages, and finally connects to the condenser.

8. The cogeneration steam supply system based on a high-pressure cylinder with separate cylinders according to claim 5, characterized in that, A first high-pressure heater, a second high-pressure heater, and a third high-pressure heater are connected in series along the feedwater direction on the second connecting pipe between the liquid outlet of the deaerator and the main steam inlet of the boiler. A second steam extraction port is provided on the first high-pressure cylinder, a third steam extraction port is provided on the second high-pressure cylinder, and a fourth and a fifth steam extraction port are provided on the intermediate-pressure cylinder. The fifth steam extraction port is connected to the steam inlet of the deaerator, the fourth steam extraction port is connected to the heating medium inlet of the first high-pressure heater, the third steam extraction port is connected to the heating medium inlet of the second high-pressure heater, and the second steam extraction port is connected to the heating medium inlet of the third high-pressure heater.

9. The cogeneration steam supply system based on a high-pressure cylinder with separate cylinders according to claim 8, characterized in that, The heating medium outlet of the third high-pressure heater is connected to the heating medium inlet of the second high-pressure heater, the heating medium outlet of the second high-pressure heater is connected to the heating medium inlet of the first high-pressure heater, and the heating medium outlet of the first high-pressure heater is connected to the steam inlet of the deaerator; and / or The second steam extraction port is connected to the steam outlet of the first high-pressure cylinder, and the third steam extraction port is connected to the steam outlet of the second high-pressure cylinder.

10. A method for regulating steam supply nodes, characterized in that, The parameter control for the extraction node of the cogeneration steam supply system based on the high-pressure cylinder sub-cylinder as described in any one of claims 1-9 includes the following steps: Obtain the main steam flow rate; Based on the difference in hydrophobicity of the heaters, the heaters in the cogeneration steam supply system based on the high-pressure cylinder are divided into hydrophobic discharge heaters and collection heaters. The parameters of each hydrophobic discharge heater are obtained based on equation (1); The parameters of each collection heater are obtained based on equation (2); In equations (1) and (2): τ j --Enthalpy rise of 1 kg of water in a heater / kJ·kg -1 ; q j --Heat release of 1 kg of heating steam in the heater / kJ·kg -1 ; γ j --Heat release of 1 kg of hydrophobic material in the heater / kJ·kg -1 ; -- Enthalpy of water at heater outlet / kJ·kg -1 ; h j -- Extraction enthalpy of heater / kJ·kg -1 ; -- Enthalpy of condensate discharged from heater / kJ·kg -1 ; --Inlet enthalpy of heater water / kJ·kg -1 ; --Enthalpy of heater entering the condensate / kJ·kg -1 ; Based on the principle of heat balance, the thermodynamic system of the cogeneration steam supply system based on the high-pressure cylinder is iteratively calculated to obtain the main steam work and the parameters and flow rates of the steam and water in each part of the cogeneration steam supply system based on the high-pressure cylinder. Calculate the heating parameters of the steam extraction node. If the heating parameters are not met, repeat the above steps iteratively.

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