Steam heat supply system based on steam pressure conversion

Abstract

The utility model relates to a steam heat supply system based on steam pressure conversion, and belongs to the technical field of cogeneration of thermal power generating units. The steam heat supply system based on steam pressure conversion comprises a water storage tank and a once-through steam furnace, the once-through steam furnace comprises a shell and a heat exchange tube bundle arranged in the shell, the input end of the heat exchange tube bundle is connected with a water storage tank pipeline through a water inlet pipe, and a water feeding pump is arranged on the water inlet pipe. Through countercurrent flow heat exchange of low-pressure high-temperature steam and demineralized water in the once-through steam furnace, the low-pressure steam exhausted by the intermediate-pressure cylinder of the steam turbine is effectively utilized and converted into available high-pressure steam, the exhaust steam consumption of the intermediate-pressure cylinder is increased, the exhaust steam consumption of the high-pressure cylinder is reduced, and then the axial thrust of rotors of the two cylinders is balanced.

Description

Technical Field

[0001] The utility model belongs to the technical field of cogeneration of thermal power units, and in particular relates to a steam heating system based on steam pressure conversion. Background Art

[0002] The cogeneration cycle utilizes the low-grade heat energy from thermal power plants and transmits the heat energy to various heat users through the steam network. It can save fuel for power production, reduce consumption, and obtain comprehensive economic benefits of heat products. It is an important measure for the development of the power industry.

[0003] However, industrial heat users generally have high requirements for heating pressure and often use high-pressure cylinder exhaust steam output by steam turbines for heating. However, in order to avoid overload of high-pressure cylinder blades and the large difference in axial thrust of the rotors of high-pressure cylinders and intermediate-pressure cylinders in the existing technology, the heating suction capacity is limited and cannot meet the growing demand of the heating market. Therefore, there is an urgent need for a heating system that can effectively utilize the exhaust steam of the intermediate-pressure cylinder and participate in heating. Summary of the Invention

[0004] The purpose of the utility model is to provide a steam heating system based on steam pressure conversion which can effectively improve the current situation that the exhaust steam pressure of the intermediate pressure cylinder is insufficient and difficult to utilize, and only requires the modification of the existing heating system.

[0005] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions:

[0006] A steam heating system based on steam pressure conversion includes a water tank and a direct current steam boiler. The direct current steam boiler includes an outer shell and a heat exchange tube bundle arranged inside the outer shell. The input end of the heat exchange tube bundle is connected to the water tank pipeline through a water inlet pipe. The water inlet pipe is provided with a water pump.

[0007] The top of the direct current steam boiler is input with low-pressure and high-temperature steam discharged from the intermediate-pressure cylinder of the turbine. The bottom of the shell is connected to a return pipe, the other end of which is connected to the top of the water tank. A condensate pump and a cooler are provided on the return pipe.

[0008] Furthermore, the direct current steam boiler is a heater, a steam-water heat exchanger, a steam generator or any form of equipment for steam-water heat conversion.

[0009] Furthermore, the direct current steam furnace includes, from bottom to top, a heating section, an evaporation section and a superheating section.

[0010] Furthermore, a water supply pipe is connected to the top of the water tank.

[0011] The utility model uses the countercurrent heat exchange between the low-pressure and high-temperature steam in the direct current steam boiler and the desalted water, which not only effectively utilizes the low-pressure steam discharged from the intermediate-pressure cylinder of the steam turbine and converts it into usable high-pressure steam, but also increases the exhaust steam consumption of the intermediate-pressure cylinder and reduces the exhaust steam consumption of the high-pressure cylinder at the same time, thereby balancing the axial thrust of the rotors of the two cylinders.

[0012] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and to implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a structural schematic diagram of a steam heating system based on steam pressure conversion shown in one embodiment of the present invention.

[0014] Explanation of the accompanying symbols: 1. Water storage tank; 2. Cooler; 3. Water feed pump; 4. Condensate pump; 5. DC steam boiler; 51. Heating section; 52. Evaporation section; 53. Superheating section; 6. Low-pressure and high-temperature steam; 7. Outlet high-pressure steam. DETAILED DESCRIPTION

[0015] The following is a clear and complete description of the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0016] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating positions or relationships, are based on the positions or relationships shown in the accompanying drawings and are intended solely to facilitate the description of this utility model and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0017] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0018] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0019] See Figure 1 A steam heating system based on steam pressure conversion shown in a preferred embodiment of the present application includes a water tank 1 and a direct current steam boiler 5. The direct current steam boiler 5 includes an outer shell and a heat exchange tube bundle arranged inside the outer shell. The heat exchange tube bundle includes a heating section 51, an evaporation section 52 and a superheating section 53 from bottom to top. The input end of the heat exchange tube bundle is connected to the water tank 1 through a water inlet pipe, and a water supply pump 3 is provided on the water inlet pipe.

[0020] The bottom of the shell is connected to a return pipe, the other end of the return pipe is connected to the top of the water storage tank 1, and a condensate pump 4 and a cooler 2 are provided on the return pipe.

[0021] Furthermore, a water supply pipe is connected to the top of the water tank 1 for replenishing desalted water.

[0022] Working principle:

[0023] The temperature of the low-pressure, high-temperature steam 6 discharged from the intermediate-pressure cylinder of the turbine is at the level of 345°C, and the external heating temperature is at the level of 260°C. Although the pressure is relatively low, it is sufficient to serve as a heat source for a direct-flow steam boiler.

[0024] During operation, the top of the direct current steam boiler 5 receives the low-pressure and high-temperature steam 6 discharged from the intermediate pressure cylinder of the steam turbine, releases heat to the heat exchange tube bundle through the superheating section 53, the evaporation section 52, and the heating section 51 in sequence, and is finally cooled into condensate at about 40°C. The condensate is transported to the cooler 2 through the condensate pump 4 for further cooling and then flows back to the water storage tank 1.

[0025] On the other hand, the desalted water in the water tank 1 is pumped into the heat exchange tube bundle by the water feed pump 3, and passes through the heating section 51, the evaporation section 52 and the superheating section 53 in sequence, absorbs the heat of the low-pressure high-temperature steam 6, and is converted into outlet high-pressure steam 7 with an output pressure of 1.2 MPa and a temperature of 260°C, and finally merges with the heating main pipe to supply heat to the outside.

[0026] The following provides basic calculations for heat exchange in a direct current steam boiler 5:

[0027] The enthalpy of desalted water at room temperature of 25°C is 104.85KJ / Kg;

[0028] The enthalpy of steam at 1.2 MPa and 260°C is 2954.66 KJ / Kg;

[0029] The amount of heat required to convert 1 kg of normal temperature desalted water into heating steam is 2954.66-104.85=2849.81 kJ / kg;

[0030] When the power load is 150MW, the enthalpy of low-pressure high-temperature steam with 6 parameters of 0.3MPa and 345℃ is 3159.7KJ / Kg;

[0031] The enthalpy of condensed water at atmospheric pressure at 40°C is 167.53KJ / Kg;

[0032] It can be obtained that the heat released by 1Kg low-pressure high-temperature steam 6 being cooled to 40℃ normal-pressure condensed water is 3159.7-167.53=2992.17KJ / Kg;

[0033] Assuming that the heat exchange efficiency of the once-through steam boiler is 95%, the heat that can be utilized by 1 kg of low-pressure, high-temperature steam 6 is 2992.17×0.95=2842.56 kJ / kg;

[0034] The amount of low-pressure, high-temperature steam in the medium-pressure cylinder 6 required to convert 1 kg of normal-temperature desalted water into heating steam is 2849.81 ÷ 2842.56 = 1.003 kg.

[0035] It can be concluded that if the steam supply of the steam direct current boiler is designed to be 100 t / h, it is necessary to extract 100.3 t / h of low-pressure and high-temperature steam 6 discharged from the intermediate-pressure cylinder of the steam turbine, which greatly increases the amount of exhaust steam from the intermediate-pressure cylinder and reduces the amount of exhaust steam from the high-pressure cylinder, thereby balancing the axial thrust of the rotors of the two cylinders.

[0036] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0037] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present utility model patent shall be determined by the appended claims.

Claims

1. A steam heating system based on steam pressure conversion, characterized in that: The device comprises a water storage tank and a direct current steam boiler, wherein the direct current steam boiler comprises an outer shell and a heat exchange tube bundle arranged inside the outer shell, wherein the input end of the heat exchange tube bundle is connected to the water storage tank pipeline through a water inlet pipe, and a water feed pump is provided on the water inlet pipe; The top of the direct current steam boiler is input with low-pressure and high-temperature steam discharged from the intermediate-pressure cylinder of the turbine. The bottom of the shell is connected to a return pipe, the other end of which is connected to the top of the water tank. A condensate pump and a cooler are provided on the return pipe.

2. The steam heating system based on steam pressure conversion according to claim 1, characterized in that: The direct current steam boiler is a heater, a steam-water heat exchanger, a steam generator or any form of equipment used for steam-water heat conversion.

3. The steam heating system based on steam pressure conversion according to claim 1, characterized in that: The direct current steam furnace comprises, from bottom to top, a heating section, an evaporation section and a superheating section.

4. The steam heating system based on steam pressure conversion according to claim 1, characterized in that: The top of the water storage tank is also connected with a water supply pipe.

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