A feedwater combined cooling and regeneration energy utilization system and method for improving boiler steam supply capacity

Abstract

The present invention discloses a feedwater combined cold reheat energy utilization system and method for improving the steam supply capacity of a boiler, comprising a steam pipeline isolation valve, a heat recovery heat exchanger, a flow regulating orifice plate, a water inlet isolation valve, a water outlet isolation valve, and a bypass isolation valve. The cold reheat steam enters the heat recovery heat exchanger through a steam pipeline, and after heat exchange and temperature reduction, the cold reheat steam is mixed with the original steam through a steam return pipe. A flow regulating orifice plate is newly arranged on the cold reheat steam pipeline to balance the steam flow, and the feedwater at the outlet of the high-pressure heater enters the heat recovery heat exchanger after passing through the water inlet isolation valve. The system can effectively improve the boiler cold reheat industrial steam supply capacity, reduce the risk of overheating of the boiler reheater, and can be put into operation and shut down online. The system can effectively increase the flow of the unit cold reheat supply steam and thus improve the unit economy.

Description

[Technical field]

[0001] The present invention belongs to the technical field of comprehensive energy utilization, and relates to a feedwater combined cooling and regeneration energy utilization system and method for improving the steam supply capacity of a boiler. [Background technology]

[0002] Supplying steam to external industries can effectively reduce the energy consumption of thermal power generating units and is also one of the important profit directions of generating units. At the same time, on the basis of meeting the steam parameter requirements of industrial steam supply users, using steam of lower quality as much as possible is conducive to the economic operation of the unit. Therefore, increasing the industrial steam supply volume and reducing the steam supply parameters as much as possible are the directions to improve the economic efficiency of industrial steam supply of the unit.

[0003] At present, most industrial steam supply units use cold reheat steam as the steam source. However, if too much cold reheat steam is extracted, the boiler reheater is prone to overheating. Therefore, the extraction volume of cold reheat steam in many units is greatly restricted and cannot fully meet the needs of users. They can only use the steam outlet steam of the low-temperature reheater with higher steam quality or even reheat steam. At the same time, the temperature of cold reheat steam is generally several tens of degrees higher than the user's demand, and it is necessary to spray cooling water for cooling. If the temperature of cold reheat steam is reasonably reduced through technical means, and the excess heat is transferred to other locations of the generator set for full utilization, the risk of overheating of the boiler reheater will be effectively reduced, and the steam supply of the unit cold reheat can be greatly increased. [Summary of the invention]

[0004] The purpose of the present invention is to solve the problems in the prior art and to provide a feedwater combined cold reheating energy utilization system and method for improving the boiler steam supply capacity. The present invention uses boiler feedwater as a cooling source to cool part of the cold reheating steam, thereby lowering the unit's cold reheating steam temperature, reducing the risk of boiler reheater overheating, and improving the feedwater temperature and the cold reheating industrial steam supply capacity.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A feedwater combined cooling and re-energy utilization system for improving the steam supply capacity of a boiler, comprising a high-pressure cylinder, a steam pipeline and a steam return pipeline;

[0007] The cold re-steam of the high-pressure cylinder enters the steam pipe; a high-pressure heater and a heat recovery heat exchanger are provided on the steam return pipe, and part of the heat of the cold re-steam is exchanged with the feed water of the steam return pipe through the heat recovery heat exchanger, and the heat-exchanged feed water is output as boiler feed water.

[0008] The present invention is further improved in that:

[0009] The steam pipeline is provided with a flow regulating orifice plate, and a heat recovery heat exchanger is connected in parallel to the flow regulating orifice plate. The cold re-steam enters the heat recovery heat exchanger through the first steam pipeline isolation valve for heat exchange. The cold re-steam after heat exchange passes through the second steam pipeline isolation valve and merges with the cold re-steam passing through the flow regulating orifice plate. A part of the merged cold re-steam is output as industrial steam supply, and the other part is output to the boiler reheater.

[0010] The outlet of the high-pressure heater is connected to the cold side inlet of the heat recovery heat exchanger, and the cold side outlet of the heat recovery heat exchanger outputs the heated feed water.

[0011] The heat recovery heat exchanger is also connected in parallel with a bypass pipeline, and a bypass isolation valve is arranged on the bypass pipeline.

[0012] The inlet of the heat recovery heat exchanger is provided with a water inlet isolation valve, the outlet of the heat recovery heat exchanger is provided with a water outlet isolation valve, and the bypass pipeline is connected in parallel to both ends of the water inlet isolation valve, the heat recovery heat exchanger and the water outlet isolation valve.

[0013] A feedwater combined cooling and regeneration energy utilization method for improving boiler steam supply capacity comprises the following steps:

[0014] During normal operation, the first steam pipeline isolation valve, the second steam pipeline isolation valve, the water inlet isolation valve and the water outlet isolation valve are opened, and the bypass isolation valve is closed; a part of the cold re-steam of the high-pressure cylinder of the steam turbine passes through the first steam pipeline isolation valve, the heat recovery heat exchanger and the second steam pipeline isolation valve, and then merges with the other part of the cold re-steam passing through the flow regulating orifice plate; the outlet feed water of the high-pressure heater passes through the water inlet isolation valve, the heat recovery heat exchanger and the water outlet isolation valve and is heated by part of the cold re-steam, and the heated feed water enters the boiler;

[0015] When the unit does not use cold steam to supply steam to the outside, close the first steam pipeline isolation valve and the second steam pipeline isolation valve, open the bypass isolation valve, and the heat recovery heat exchanger is in a shutdown state.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention transfers part of the heat of the cold re-steam to the boiler feed water through a heat recovery heat exchanger. On the one hand, it can reduce the temperature of the cold re-steam by more than 20°C and increase the cold re-industrial steam supply by more than 100%. On the other hand, it can increase the boiler feed water temperature, so that the energy of the cold re-extracted steam can be fully utilized, and this cold re-energy utilization process will not significantly affect the unit cycle efficiency. The unit will be more economical due to the improvement of the external steam supply capacity and the reduction of the use of high-quality steam, and the use of industrial steam supply cooling water can also be reduced.

[0018] The present invention sets a heat recovery heat exchanger, and utilizes part of the cold re-steam to heat the boiler feed water to achieve energy joint transfer and utilization, thereby reducing the risk of boiler reheater overheating, increasing the maximum heating capacity of cold re-steam, increasing the feed water temperature, reducing the amount of cold re-steam cooling water used, and improving the unit operation economy. The present invention can be applied to secondary reheating power generation units that supply steam to external industries. Through heat exchange, the heat of cold re-steam is partially utilized in the feed water, reducing the temperature of cold re-steam and external industrial steam supply, reducing the risk of reheater overheating when the boiler cold re-steam supplies steam to external industries, improving the maximum capacity of cold re-steam to external industrial steam supply, reducing the use of high-quality steam such as reheat steam, reducing the use of industrial steam cooling water, improving the unit operation economy, and reducing coal consumption for power generation.

Brief Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 It is a schematic diagram of the system structure of the present invention.

[0021] Among them, 1-turbine high-pressure cylinder; 2-first steam pipe isolation valve; 3-high-pressure heater; 4-heat recovery heat exchanger; 5-second steam pipe isolation valve; 6-flow regulating orifice plate; 7-water inlet isolation valve; 8-water outlet isolation valve; 9-bypass isolation valve. [Specific implementation method]

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0025] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0026] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0027] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0029] See also Figure 1 The feed water combined with cold regeneration energy utilization system for improving the steam supply capacity of the boiler of the present invention comprises a first steam pipeline isolation valve 2, a heat recovery heat exchanger 4, a second steam pipeline isolation valve 5, a flow regulating orifice plate 6, a water inlet isolation valve 7, a water outlet isolation valve 8, and a bypass isolation valve 9; the cold regeneration steam enters the heat recovery heat exchanger 4 through the steam pipeline, and a first steam pipeline isolation valve 2 is arranged between the pipelines. The cold regeneration steam is mixed with the original steam through the steam return pipeline after heat exchange and cooling. A second steam pipeline isolation valve 5 is arranged between the steam return pipelines. A flow regulating orifice plate 6 is newly arranged on the cold regeneration steam pipeline to balance the steam flow. The feed water at the outlet of the high-pressure heater enters the heat recovery heat exchanger 4 after passing through the water inlet isolation valve 7. After being heated by steam, the feed water enters the boiler after passing through the water outlet isolation valve 8. At the same time, the heat recovery heat exchanger 4 is provided with a bypass isolation valve 9.

[0030] Principle of the present invention:

[0031] By transferring part of the heat of the cold re-steam to the boiler feed water through the heat recovery heat exchanger 4, the temperature of the cold re-steam can be reduced by more than 20°C, reducing the risk of overheating of the boiler reheater, and thus increasing the cold re-steam industrial steam supply by more than 100%. Since the heat is used to increase the feed water temperature, the negative impact on the unit's economic performance is small, and the commissioning of the unit's cold re-steam desuperheating water can also be reduced. The increase in industrial steam supply will greatly improve the unit's economic indicators.

[0032] Working process of the present invention:

[0033] A part of the cold re-steam of the high-pressure cylinder of the steam turbine of the present invention passes through the first steam pipeline isolation valve 2, the heat recovery heat exchanger 4, and the second steam pipeline isolation valve 5, and the steam that has been heat exchanged in the heat recovery heat exchanger 4 is merged with the original cold re-steam, and the other part of the cold re-steam that has not been heat exchanged passes through the flow regulating orifice plate 6 and is merged with the cooled cold re-steam; the outlet feed water of the high-pressure heater 3 has been heated by part of the cold re-steam after passing through the water inlet isolation valve 7, the heat recovery heat exchanger 4, and the water outlet isolation valve 8, and the heated feed water enters the boiler.

[0034] During normal operation, the first steam pipe isolation valve 2, the second steam pipe isolation valve 5, the water inlet isolation valve 7, and the water outlet isolation valve 8 are all in the open state, and the bypass isolation valve 9 is in the closed state; when the unit does not use cold steam to supply steam to the outside, the first steam pipe isolation valve 2 and the second steam pipe isolation valve 5 are closed in sequence, and then the bypass isolation valve 9 is gradually opened, and the heat recovery heat exchanger 4 is in a shutdown state.

[0035] The present invention has a clear principle, a simple system, low maintenance, can be put into operation and shut down online, and is suitable for all secondary reheat power generating units. It is an innovative technology for increasing the cold reheat industrial steam supply of the reheat unit, reducing the risk of boiler reheater overtemperature, and improving the heating economy of the unit.

[0036] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A feedwater combined cooling and regeneration energy utilization system for improving boiler steam supply capacity, characterized in that: It comprises a high-pressure cylinder (1), a steam pipeline and a steam return pipeline; The cold re-steam of the high-pressure cylinder (1) enters the steam pipe; a high-pressure heater (3) and a heat recovery heat exchanger (4) are provided on the steam return pipe, and part of the heat of the cold re-steam is exchanged with the feed water of the steam return pipe through the heat recovery heat exchanger (4), and the heat-exchanged feed water is output as boiler feed water; The steam pipeline is provided with a flow regulating orifice plate (6), and the heat recovery heat exchanger (4) is connected in parallel to the flow regulating orifice plate (6). The cold re-steam enters the heat recovery heat exchanger (4) through the first steam pipeline isolation valve (2) for heat exchange. The cold re-steam after heat exchange passes through the second steam pipeline isolation valve (5) and merges with the cold re-steam passing through the flow regulating orifice plate (6). A portion of the merged cold re-steam is output as industrial steam supply, and the other portion is output to the boiler reheater; The outlet of the high-pressure heater (3) is connected to the cold side inlet of the heat recovery heat exchanger (4), and the cold side outlet of the heat recovery heat exchanger (4) outputs the heated feed water.

2. The feedwater combined cooling and regeneration energy utilization system for improving boiler steam supply capacity according to claim 1 is characterized in that: The heat recovery heat exchanger (4) is also connected in parallel with a bypass pipeline, and a bypass isolation valve (9) is provided on the bypass pipeline.

3. The feedwater combined cooling and regeneration energy utilization system for improving boiler steam supply capacity according to claim 2 is characterized in that: A water inlet isolation valve (7) is provided at the inlet of the heat recovery heat exchanger (4), and a water outlet isolation valve (8) is provided at the outlet; a bypass pipeline is connected in parallel to both ends of the water inlet isolation valve (7), the heat recovery heat exchanger (4) and the water outlet isolation valve (8).

4. A feedwater combined cooling and regeneration energy utilization method for improving boiler steam supply capacity using the system according to any one of claims 1 to 3, characterized in that: The following steps are involved: During normal operation, the first steam pipeline isolation valve (2), the second steam pipeline isolation valve (5), the water inlet isolation valve (7) and the water outlet isolation valve (8) are opened, and the bypass isolation valve (9) is closed; a portion of the cold re-steam of the high-pressure cylinder of the steam turbine passes through the first steam pipeline isolation valve (2), the heat recovery heat exchanger (4) and the second steam pipeline isolation valve (5), and then merges with another portion of the cold re-steam passing through the flow regulating orifice plate (6); the outlet feed water of the high-pressure heater (3) passes through the water inlet isolation valve (7), the heat recovery heat exchanger (4) and the water outlet isolation valve (8) and is heated by a portion of the cold re-steam, and the heated feed water enters the boiler; When the unit does not use cold steam to supply steam to the outside, the first steam pipeline isolation valve (2) and the second steam pipeline isolation valve (5) are closed, the bypass isolation valve (9) is opened, and the heat recovery heat exchanger (4) is in a shutdown state.

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