A pure condensing unit boiler considering industrial steam supply

Abstract

The present application relates to the technical field of boiler, and proposes a pure condensing unit boiler giving consideration to industrial steam supply, which comprises a boiler drum, evaporation heating surface and superheater heating surface, the boiler drum is provided with a steam-water separation device, and the boiler drum is provided with a water inlet, a water outlet, a steam-water inlet and a steam outlet, and the boiler drum is connected with a water supply pipe, and the water supply pipe is connected with a water supply pump in series; the evaporation heating surface is connected with an evaporation heating surface inlet header and an evaporation heating surface outlet header respectively, the evaporation heating surface inlet header is connected with the water outlet of the boiler drum through a centralized downcomer, and the evaporation heating surface outlet header is connected with the steam-water inlet of the boiler drum through a steam-water connecting pipe; the superheater heating surface is connected with a superheater inlet header and a superheater outlet header respectively, and the superheater inlet header is connected with the steam outlet of the boiler drum through a steam connecting pipe. According to the present application, an independent steam production circuit is innovatively designed from the source of the boiler, and the pressure, temperature and flow of the steam supply can be independently designed without affecting the power generation of the original pure condensing unit.

Description

Technical Field

[0001] This invention relates to the field of boiler technology, and more specifically, to a pure condensing boiler unit that can also supply steam for industrial use. Background Technology

[0002] In the traditional coal-fired power sector, high-parameter, large-capacity condensing turbine generator sets have long been the mainstay of large coal-fired power plants due to their high power generation efficiency under condensing conditions. Meanwhile, with the booming development of industrial parks and the increasing demand for comprehensive energy utilization, the demand for centralized, stable, and high-quality industrial steam is growing. Currently, common technical solutions for providing industrial steam from the boiler side of condensing units mainly involve extracting steam from the main steam, reheat hot section, and reheat cold section. However, these existing solutions generally suffer from the following technical problems when providing industrial steam: 1. Poor matching between steam supply parameters and demand, resulting in insufficient flexibility: Industrial users have diverse steam parameter requirements. If steam is extracted from the main steam source, the main steam parameters are high, significantly exceeding the industrial extraction requirements at all load levels, necessitating substantial temperature and pressure reduction, leading to low steam quality utilization. If steam is extracted from the reheat hot section, it can usually meet industrial extraction requirements at medium to high loads, requiring moderate pressure reduction and substantial temperature reduction when parameters are high. However, at low loads, the reheat steam pressure is too low to meet the steam pressure requirements, and if pressure is suppressed through the intermediate control valve, the unit's economic efficiency is poor. If steam is extracted from the reheat cold section, although the steam parameters are relatively moderate at medium to high loads, low pressure is still a problem at low loads. Moreover, extracting steam from the reheat cold section carries the risk of boiler reheater overheating. Generally, the allowable extraction volume does not exceed 5% to 7% of the reheat steam flow, which cannot meet the large steam supply demands of industrial users. In addition, the adjustment range of steam supply parameters is narrow, making it difficult to flexibly adapt to the different steam parameter requirements of users.

[0003] 2. The contradiction between steam supply stability and unit operation safety: Extraction steam parameters are easily affected by unit load fluctuations, especially at low loads, where extraction steam parameters fluctuate greatly with the main unit's operating conditions, affecting the stability of steam supply quality. To stabilize steam supply parameters, complex control systems are often required, or the unit's peak-shaving capacity may be sacrificed.

[0004] 3. Limited steam supply capacity: The steam extraction capacity is limited by the turbine flow limit, boiler heating surface protection and other safety constraints, as well as the economic impact of unit efficiency loss. Traditional pure condensing units are unable to meet the large-scale, high-flow industrial steam supply demand.

[0005] Therefore, there is an urgent need to develop a pure condensing boiler unit that can also supply steam for industrial use. This unit should be designed with an independent steam production circuit from the boiler source, allowing for independent design of the steam pressure, temperature, and flow rate. It should be specifically designed to produce steam that meets the needs of industrial users, achieving a high-efficiency, flexible, and stable balance between industrial steam supply and power generation. Summary of the Invention

[0006] The purpose of this invention is to provide a condensing boiler that can also supply steam for industrial use. It innovatively designs an independent steam generation circuit from the boiler source. While not affecting the original condensing unit's power generation, the pressure, temperature, and flow rate of the supplied steam can be designed independently, specifically for producing steam that meets the needs of industrial users, thus achieving a high-efficiency, flexible, and stable balance between industrial steam supply and power generation.

[0007] The technical solution adopted in this invention is as follows: This application provides a condensing boiler unit that also provides industrial steam supply. Above the furnace, along the flue gas flow direction, are sequentially arranged a screen-type superheater and a high-temperature superheater. The boiler is connected to a horizontal flue, within which a high-temperature reheater is located. The horizontal flue is sequentially connected to a high-temperature reheater outlet turning chamber flue and a rear vertical shaft flue. A low-temperature reheater is located in the high-temperature reheater outlet turning chamber flue, and a low-temperature superheater is located in the rear vertical shaft flue. The boiler also includes a boiler drum, evaporation heating surfaces, and superheater heating surfaces. A steam-water separation device is installed inside the boiler drum. The boiler drum has a feedwater inlet, a water outlet, a steam-water inlet, and a vapor phase outlet. The feedwater inlet of the boiler drum is connected to a feedwater pipe, and a feedwater pump is connected in series with the feedwater pipe. The evaporation heating surfaces are arranged within the boiler. Above the furnace, the inlet end of the evaporating heating surface is connected to the evaporating heating surface inlet header, which is connected to the boiler drum outlet via a centralized downcomer; the outlet end of the evaporating heating surface is connected to the evaporating heating surface outlet header, which is connected to the boiler drum steam-water inlet via a steam-water connecting pipe; the superheater heating surface is located in the flue of the high-temperature reheater outlet turning chamber or in the rear flue of the rear shaft, the inlet end of the superheater heating surface is connected to the superheater inlet header, which is connected to the boiler drum vapor phase outlet via a steam connecting pipe; the outlet end of the superheater heating surface is connected to the superheater outlet header, which is connected to a steam outlet pipe.

[0008] Furthermore, in this invention, a water supply preheater is connected in series with the water supply pipe, and the water supply preheater is located between the water supply pump and the boiler drum.

[0009] Furthermore, in this invention, a desuperheater is connected in series with the steam outlet pipe, and the desuperheater's desuperheating water inlet is connected to a desuperheating water input pipe.

[0010] Furthermore, in this invention, the desuperheating water inlet pipe is equipped with a gate valve and a regulating valve.

[0011] Furthermore, in this invention, the desuperheating water inlet pipe is equipped with a flow meter.

[0012] Furthermore, in this invention, the evaporation heating surface is arranged vertically above the furnace and in front of the screen-type superheater.

[0013] Furthermore, in this invention, the boiler drum is arranged above the furnace top tundish of the boiler and suspended below the boiler's main beam by a support structure.

[0014] Compared with the prior art, the present invention has at least the following advantages or beneficial effects: This application provides a condensing boiler that also supports industrial steam supply. Completely independent of the traditional steam-water flow of a condensing boiler, the pressure, temperature, and other parameters of the supplied steam can be adjusted according to the user's specific needs. This reduces the significant energy loss caused by steam desuperheating and pressure reduction in conventional boiler-side extraction schemes, improving the overall energy utilization efficiency of power generation and industrial steam supply. When steam supply is not required, the system can be flexibly shut down, and the generated steam can be introduced into the low-temperature reheater inlet or the turbine regenerative system to increase power generation. Power generation load and steam supply load can be adjusted simultaneously and independently, offering high operational flexibility. Especially when the industrial steam supply flow is large, this system avoids the impact of conventional steam extraction schemes on the safety of the boiler's heating surfaces, improving system operational safety and decoupling the industrial steam supply from the power generation load of the condensing boiler. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A schematic diagram of the overall layout of the boiler provided in an embodiment of the present invention. Figure 1 ; Figure 2 A schematic diagram of the overall layout of the boiler provided in an embodiment of the present invention. Figure 2 ; Figure 3 This is a schematic diagram of the steam-water medium flow of a boiler provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the steam-water medium flow of the boiler when no external steam supply is required in an embodiment of the present invention; Figure 5 This is a schematic diagram of the steam generation circuit structure of a boiler provided in an embodiment of the present invention.

[0017] Icons: 1-Screen-type superheater; 2-High-temperature superheater; 3-Horizontal flue; 4-High-temperature reheater; 5-High-temperature reheater outlet diversion chamber flue; 6-Rear vertical shaft rear flue; 7-Low-temperature reheater; 8-Low-temperature superheater; 9-Boiler drum; 10-Evaporating heating surface; 11-Superheater heating surface; 12-Feed water pipe; 13-Feed water pump; 14-Evaporating heating surface inlet header; 15-Evaporating heating surface outlet header ; 16-Centralized downcomer; 17-Steam-water connection pipe; 18-Superheater inlet header; 19-Superheater outlet header; 20-Steam connection pipe; 21-Steam outlet pipe; 22-Feedwater preheater; 23-Desuperheater; 24-Desuperheating water inlet pipe; 25-Gate valve; 26-Regulating valve; 27-Flow meter; 28-Support structure; 29-Furnace top ladle; 30-Large plate beam; 31-Deaerator. Detailed Implementation

[0018] The embodiments of this application will now be described in detail with reference to the accompanying drawings. Example

[0019] Please refer to Figure 1 , Figures 3-5 This embodiment provides a pure condensing unit boiler that can also supply steam for industrial use. The boiler is an existing pure condensing unit boiler. A screen-type superheater 1 and a high-temperature superheater 2 are arranged sequentially above the furnace along the flue gas flow direction. The boiler is connected to a horizontal flue 3. A high-temperature reheater 4 is arranged in the horizontal flue 3. The horizontal flue 3 is connected to a high-temperature reheater outlet turning chamber flue 5 and a rear vertical shaft rear flue 6 in sequence. A low-temperature reheater 7 is arranged in the high-temperature reheater outlet turning chamber flue 5, and a low-temperature superheater 8 is arranged in the rear vertical shaft rear flue 6. It also includes a boiler drum 9, an evaporator heating surface 10, and a superheater heating surface 11. The boiler drum 9 is an existing product. The boiler drum 9 itself is equipped with a steam-water separation device. The boiler drum 9 has a water inlet, a water outlet, a steam-water inlet, and a vapor phase outlet. The water inlet of the boiler drum 9 is connected to a water supply pipe 12. The end of the water supply pipe 12 away from the boiler drum 9 is connected to the original deaerator 31 of the original pure condensing unit. The water supply pipe 12 is connected in series with a water supply pump 13 and a water supply preheater 22. The water supply preheater 22 is located between the water supply pump 13 and the boiler drum 9. After the water is deaerated by the deaerator 31, it is transported to the position of the water supply pump 13. The water is pumped to the water supply preheater 22 by the water supply pump 13. The heat source of the water supply preheater 22 can come from the steam turbine regenerative steam. After the water is heated by the water supply preheater 22, it is transported to the boiler drum 9.

[0020] The evaporation heating surface 10 is arranged above the boiler furnace, such as... Figure 5As shown, to minimize the impact on the original condensing unit boiler structure layout, in this embodiment, the evaporation heating surface 10 is vertically arranged above the furnace and in front of the screen-type superheater 1. The boiler drum 9 is arranged above the boiler's furnace top liner 29 and suspended below the boiler's large plate beam 30 by the support structure 28. (The boiler's "furnace top liner" refers to a large box-type (or enclosed) structure that covers the high-temperature area of ​​the boiler furnace top and consists of an internal sealing structure, an insulation layer, and an external metal protective plate, providing insulation, sealing, and protection functions. It is sometimes also called the "furnace top cover" or "furnace top insulation shell," and it plays a crucial role in ensuring the boiler's economic efficiency, safety, reliability, and improving the working environment.) The inlet end of the evaporating heating surface 10 is connected to the evaporating heating surface inlet header 14, and the evaporating heating surface inlet header 14 is connected to the water outlet of the boiler drum 9 through a centralized downcomer 16; the outlet end of the evaporating heating surface 10 is connected to the evaporating heating surface outlet header 15, and the evaporating heating surface outlet header 15 is connected to the steam and water inlet of the boiler drum 9 through a steam and water connecting pipe 17.

[0021] Depending on the steam temperature used by industrial users, the superheater heating surface 11 can be arranged above the low-temperature superheater 8 inside the rear flue 6 of the rear shaft (e.g., Figure 1 (as shown in the horizontal arrangement) or inside the flue 5 of the high-temperature reheater outlet diversion chamber (such as...) Figure 2 (As shown in the vertical arrangement), in this embodiment, the superheater heating surface 11 is arranged above the low-temperature superheater 8 in the rear flue 6 of the rear shaft, and can be suspended using the original condensing unit boiler superheater hanging pipe. The inlet end of the superheater heating surface 11 is connected to the superheater inlet header 18, and the superheater inlet header 18 is connected to the steam phase outlet of the boiler drum 9 through a steam connecting pipe 20; the outlet end of the superheater heating surface 11 is connected to the superheater outlet header 19, and the superheater outlet header 19 is connected to a steam outlet pipe 21, which is used to supply steam to the terminal. A desuperheater 23 is connected in series with the steam outlet pipe 21. The desuperheating water inlet of the desuperheater 23 is connected to a desuperheating water inlet pipe 24. The end of the desuperheating water inlet pipe 24 away from the desuperheater 23 is connected to the outlet of the original feedwater pump of the original condensing unit, supplying desuperheating water into the desuperheater 23. The desuperheating water inlet pipe 24 is equipped with a gate valve 25, a regulating valve 26, and a flow meter 27. The gate valve 25 is used to control the opening and closing of the desuperheating water inlet pipe 24, the regulating valve 26 is used to control the flow rate of the desuperheating water inlet pipe 24, and the flow meter 27 is used to measure the flow rate of the desuperheating water inlet pipe 24. The steam temperature can be adjusted by regulating the flow rate of the desuperheating water injected into the desuperheater 23.

[0022] In practical applications, when the design of a pure condensing unit needs to also consider industrial steam supply, such as Figure 1 and Figure 3As shown, the working fluid flow of the independent steam generation circuit is as follows: After deaerator 31, feedwater is pumped by an independent feedwater pump 13, heated by feedwater preheater 22 (heat source: regenerative steam from the turbine), and then transported to boiler drum 9. After mixing with circulating water in boiler drum 9, it is introduced into the evaporation heating surface inlet header 14 through centralized downcomer 16, and then flows upward through the evaporation heating surface 10 above the furnace, generating saturated steam. This forms a steam-water mixture, which enters the upper boiler drum 9 from the evaporation heating surface outlet header 15 via steam-water connection pipe 17. The mixture then undergoes steam-water separation by the steam-water separator in boiler drum 9. The separated water is mixed with feedwater through the centralized downcomer 16 and then enters the evaporator heating surface 10 for natural circulation. The saturated steam separated from the boiler drum 9 enters the superheater inlet header 18 through the steam connection pipe 20, then enters the superheater heating surface 11 above the low-temperature superheater 8 located in the rear flue 6 of the rear shaft, and then enters the superheater outlet header 19. The saturated steam flows sequentially through the superheater inlet header 18, the superheater heating surface 11, and the superheater outlet header 19 to form superheated steam, which is finally led to different industrial users through the steam outlet pipe 21. To accurately meet the steam parameter requirements of different users, a desuperheater 23 is installed on the steam outlet pipe 21. The desuperheating water is taken from the outlet of the original feedwater pump of the original condensing unit. The independent feedwater pump 13 adjusts the pump head (pressure) and flow rate by changing the pump motor speed, thereby regulating the steam supply pressure.

[0023] like Figure 4 As shown, when there is no demand for external steam supply, this circuit still needs to produce steam to prevent the heating surface from burning dry. The generated steam can be introduced into the inlet of the low-temperature reheater or the turbine regeneration system (the turbine regeneration system refers to a system that extracts some of the steam that is doing work from different parts of the turbine and uses the heat of this steam to heat the boiler feedwater or condensate in stages) to increase the power generation of the pure condensing unit. Example

[0024] like Figure 2 As shown, when the steam temperature of industrial users is further increased, such as from 300-350℃ to 450-500℃, the superheater heating surface 11 can be arranged in the flue duct 5 of the high-temperature reheater outlet turning chamber. Here, the flue gas is not split and the flue gas temperature is also higher, which can achieve a higher steam supply temperature.

[0025] Thus, the pure condensing boiler that also provides industrial steam supply provided in this application proposes a new industrial steam supply system based on conventional ultra-supercritical pure condensing boilers. Its main advantages include: Completely independent of the original pure condensing unit boiler's steam-water process, the steam supply pressure, temperature and other parameters can be adjusted according to the user's specific needs, reducing the huge energy loss caused by steam desuperheating and pressure reduction in conventional boiler-side steam extraction schemes, and improving the comprehensive energy utilization efficiency of power generation + industrial steam supply.

[0026] When steam supply is not required, the system can be flexibly shut down, and the generated steam can be introduced into the inlet of the low-temperature reheater or the turbine regenerative system to increase power generation. The power generation load and steam supply load can be adjusted simultaneously and independently, providing high operational flexibility. Especially when the industrial steam supply flow is large, this system can avoid the impact of conventional steam extraction schemes on the safety of the boiler's heating surfaces, improve system operational safety, and decouple the industrial steam supply from the power generation load of the condensing unit boiler.

[0027] Furthermore, this application does not use a circulation pump for forced circulation, but instead adopts natural circulation between the boiler drum 9 and the evaporation heating surface 10. This results in a simpler structure, higher reliability, lower operating and maintenance costs, and greater energy efficiency without a circulation pump. It is also more suitable for low-pressure applications such as steam supply systems. By adding a feedwater preheater 22 before the feedwater pump 13 and the boiler drum 9, the feedwater temperature entering the steam supply system can be freely adjusted by regulating the heat supply of the heat source—the regenerative steam from the steam turbine. As the feedwater temperature increases, the heat absorption of the evaporation heating surface 10 increases, and the steam flow rate increases accordingly, thereby regulating the system's steam supply flow rate.

Claims

1. A condensing boiler unit that also supplies steam for industrial use, wherein a screen-type superheater (1) and a high-temperature superheater (2) are sequentially arranged above the furnace along the flue gas flow direction; the boiler is connected to a horizontal flue (3); a high-temperature reheater (4) is arranged in the horizontal flue (3); the horizontal flue (3) is sequentially connected to a high-temperature reheater outlet turning chamber flue (5) and a rear vertical shaft rear flue (6); a low-temperature reheater (7) is arranged in the high-temperature reheater outlet turning chamber flue (5); and a low-temperature superheater (8) is arranged in the rear vertical shaft rear flue (6); characterized in that: It also includes a boiler drum (9), an evaporation heating surface (10), and a superheater heating surface (11). The boiler drum (9) is equipped with a steam-water separation device. The boiler drum (9) has a water inlet, a water outlet, a steam-water inlet, and a vapor phase outlet. The water inlet of the boiler drum (9) is connected to a water supply pipe (12), and the water supply pipe (12) is connected in series with a water supply pump (13). The evaporation heating surface (10) is arranged above the boiler furnace. The inlet end of the evaporation heating surface (10) is connected to an evaporation heating surface inlet header (14). The evaporation heating surface inlet header (14) is connected to the water outlet of the boiler drum (9) through a centralized downcomer (16). The outlet end of the evaporation heating surface (10) is connected to an evaporation heating surface outlet header (15). The evaporation heating surface outlet header (15) is connected to the steam-water inlet of the boiler drum (9) through a steam-water connecting pipe (17). The superheater heating surface (11) is arranged in the flue (5) of the outlet turning chamber of the high temperature reheater or in the rear flue (6) of the rear shaft. The inlet end of the superheater heating surface (11) is connected to the superheater inlet header (18). The superheater inlet header (18) is connected to the vapor phase outlet of the boiler drum (9) through a steam connection pipe (20). The outlet end of the superheater heating surface (11) is connected to the superheater outlet header (19). The superheater outlet header (19) is connected to a steam outlet pipe (21).

2. A pure condensing boiler unit that also provides industrial steam supply according to claim 1, characterized in that, The water supply pipe (12) is connected in series with a water supply preheater (22), which is located between the water supply pump (13) and the boiler drum (9).

3. A pure condensing boiler unit that also provides industrial steam supply according to claim 1, characterized in that, The steam outlet pipe (21) is connected in series with a desuperheater (23), and the desuperheating water inlet of the desuperheater (23) is connected to a desuperheating water input pipe (24).

4. A pure condensing boiler unit that also provides industrial steam supply according to claim 3, characterized in that, The desuperheating water inlet pipe (24) is equipped with a gate valve (25) and a regulating valve (26).

5. A pure condensing boiler unit that also provides industrial steam supply according to claim 3, characterized in that, The desuperheating water inlet pipe (24) is equipped with a flow meter (27).

6. A pure condensing boiler unit that also provides industrial steam supply according to any one of claims 1-5, characterized in that, The evaporation heating surface (10) is arranged vertically above the furnace and in front of the screen-type superheater (1).

7. A pure condensing boiler unit that also provides industrial steam supply according to any one of claims 1-5, characterized in that, The boiler drum (9) is arranged above the furnace top tundish (29) of the boiler and suspended below the boiler's main beam (30) by a support structure (28).

Images