A boiler exhaust steam recovery system

Abstract

This utility model relates to a boiler exhaust steam recovery system, belonging to the field of exhaust steam recovery technology. The technical solution is as follows: the top of the exhaust expansion tank (1) is connected to the cooler (3) through the exhaust pipeline (2), the cold medium inlet (301) of the cooler is connected to the demineralized water pump (4), and the cold medium outlet (302) of the cooler is connected to the deaerator (11) through the circulating water pipeline (5); the condensate recovery pipe (6) is connected to the bottom of the exhaust expansion tank, and a water quality sensor (8) and a three-way valve (9) are installed on the condensate recovery pipe in sequence. The other two ends of the three-way valve are connected to the desalination device (12) and the makeup water tank (13) respectively. The beneficial effects of this utility model are: by adding a cooler to the exhaust pipeline, heat energy recovery and condensate reuse are realized by using low-temperature demineralized water and exhaust steam to exchange heat in countercurrent. The system integrates intelligent quality control and pressure adaptive mechanism, which has the advantages of high efficiency, low cost and simple maintenance.

Description

Technical Field

[0001] This utility model relates to a boiler exhaust steam recovery system, and more particularly to a system based on a cooler to recover the heat energy and working fluid of exhaust steam. It is applicable to power plant boilers, industrial boilers and other scenarios, and belongs to the field of exhaust steam recovery technology. Background Technology

[0002] Exhaust steam refers to the steam discharged from the boiler's blowdown expansion vessel, typically at a temperature of 100-150℃. Direct discharge of this steam not only wastes a significant amount of thermal energy but also easily causes environmental problems, such as thermal damage to surrounding equipment and icing in winter. Furthermore, the high-purity water (working fluid) contained in the steam is not recovered, leading to a waste of water resources.

[0003] Existing waste heat recovery systems often require complex pipeline modifications, resulting in high investment costs and difficult maintenance. Chinese patent application CN202411878189.4, entitled "A Boiler Fixed Blowout Wastewater Heat Energy Recovery System and Method," comprises multiple subsystems, including a cold-end system, a hot-end system, a demineralized water cooling supply system, a demineralized water cooling recovery system, and a DCS automatic system. This system requires modification of the boiler's existing blowout and cooling pipelines, leading to high complexity. Furthermore, the cooling water is treated uniformly by a wastewater treatment device before storage, without separate quality control; qualified and unqualified water are treated together, increasing processing costs. Chinese patent CN201810717573.4, entitled "A Waste Heat Recovery System and Method for a Boiler Fixed Blowout Expansion Container," uses a jet-type vapor-liquid mixer (Venturi tube). Cold water is sprayed from nozzles to create negative pressure to draw in waste steam. The waste steam and cold water are directly mixed for heat exchange. The mixture enters a collection and separation tank and is directly discharged as wastewater through a blowout valve. This lack of separate quality reuse design may result in the waste of qualified working fluid. Utility Model Content

[0004] The purpose of this invention is to provide a boiler exhaust steam recovery system that does not require modification of the existing complex piping network. By adding a cooler to the exhaust pipeline, heat energy recovery and condensate reuse are achieved. The system integrates intelligent quality control and pressure adaptive mechanism, and has the advantages of high efficiency, low cost and easy maintenance, thus solving the problems existing in the background technology.

[0005] The technical solution of this utility model is: A boiler exhaust steam recovery system includes an exhaust expansion tank, an vent pipeline, a cooler, a demineralized water circulation unit, and a condensate recovery unit. The top of the exhaust expansion tank is connected to the cooler via the vent pipeline, which passes through and extends out of the cooler. The cooler is a plate heat exchanger with multiple plates forming flow channels between adjacent plates. The demineralized water circulation unit includes a demineralized water pump. The cooler's cold medium inlet is connected to the demineralized water pump, and the cooler's cold medium outlet is connected to the demineralized water circulation unit via a circulating water pipeline. The oxygenator is connected; the cold medium enters the cooler through the cold medium inlet and flows in the plate channel, and flows out through the cold medium outlet. The cold medium in the plate channel exchanges heat with the hot medium in the drain pipeline in a countercurrent manner. The hot medium and cold medium are separated by plates and do not mix directly. The condensate recovery unit includes a condensate recovery pipe, a water quality sensor and a three-way valve. The condensate recovery pipe is connected to the bottom of the fixed discharge expansion tank. The water quality sensor and the three-way valve are installed on the condensate recovery pipe in sequence. The other two ends of the three-way valve are connected to the desalination device and the water supply tank, respectively.

[0006] The heat medium inlet of the cooler is connected to the exhaust pipeline, and a throttling orifice plate is provided between the heat medium inlet of the cooler and the fixed exhaust expansion vessel. The throttling orifice plate is used to stabilize the exhaust steam flow.

[0007] A cyclone separator is provided between the fixed discharge expansion vessel and the throttling orifice plate, which can remove solid impurities in the exhaust steam in advance.

[0008] The circulating water pipeline is equipped with a self-regulating pressure regulating valve, which automatically maintains the cooling water pressure difference without relying on a complex control system, achieving "pressure self-adaptation", reducing dependence on external control and improving system stability.

[0009] The plate channel spacing of the plate heat exchanger is ≥5mm to reduce impurity deposition.

[0010] In this invention, the cold medium is secondary demineralized water, and the hot medium is exhaust steam.

[0011] The aforementioned fixed discharge expansion tank, demineralized water pump, throttling orifice plate, water quality sensor, three-way valve, cyclone separator, deaerator, desalination device, water supply tank, and self-regulating pressure regulating valve are all well-known and commonly used equipment in this field.

[0012] The process of using this utility model: The exhaust steam discharged from the fixed-discharge expansion tank enters the cooler through the vent pipeline via the hot medium inlet. Secondary demineralized water enters the cooler through the cold medium inlet via a demineralized water pump and flows within the plate flow channels. The secondary demineralized water in the plate flow channels exchanges heat counter-currently with the exhaust steam in the vent pipeline, without direct mixing. The heated secondary demineralized water enters the deaerator through the circulating water pipeline, and then enters the boiler system for reuse, saving gas and reducing production costs. After heat exchange, most of the exhaust steam forms condensate, which returns to the fixed-discharge expansion tank, while a small portion is directly discharged. The condensate from the fixed-discharge expansion tank enters the condensate recovery pipe, which is equipped with a water quality sensor and a three-way valve. Based on the water quality sensor's detection results, if the water quality meets the standard (compliant with GB / T 12145-2016), it is sent to the makeup water tank for direct reuse via the three-way valve; if it does not meet the standard, it is sent to the desalination unit for treatment via the three-way valve.

[0013] The beneficial effects of this utility model are: no need to modify the original complex pipe network, by adding a cooler to the venting pipeline, heat energy recovery and condensate reuse are achieved by using low-temperature demineralized water and venting steam to exchange heat in countercurrent. The system integrates intelligent quality control and pressure adaptive mechanism, which has the advantages of high efficiency, low cost and easy maintenance. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model; In the diagram: 1. Fixed discharge expansion container; 2. Drainage pipeline; 3. Cooler; 4. Cold medium inlet 301; 5. Cold medium outlet 302; 6. Hot medium inlet 303; 7. Demineralized water pump; 8. Circulating water pipeline; 9. Condensate recovery pipe; 10. Throttling orifice plate; 11. Water quality sensor; 12. Three-way valve; 13. Cyclone separator; 14. Deaerator; 15. Desalination device; 16. Makeup water tank; 17. Self-regulating pressure regulating valve. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and examples.

[0016] A boiler exhaust steam recovery system includes an exhaust expansion tank 1, an exhaust pipeline 2, a cooler 3, a demineralized water circulation unit, and a condensate recovery unit. The top of the exhaust expansion tank 1 is connected to the cooler 3 via the exhaust pipeline 2, which passes through and extends out of the cooler 3. The cooler 3 is a plate heat exchanger with multiple plates inside, forming flow channels between adjacent plates. The demineralized water circulation unit includes a demineralized water pump 4. The cold medium inlet 301 of the cooler 3 is connected to the demineralized water pump 4, and the cold medium outlet 302 of the cooler 3 is connected to the deaerator via a circulating water pipeline 5. The device 11 is connected; the cold medium enters the cooler 3 through the cold medium inlet 301 and flows in the plate flow channel, and flows out through the cold medium outlet 302. The cold medium in the plate flow channel exchanges heat with the hot medium in the drain line 2 in a countercurrent manner. The hot medium and cold medium are separated by the plates and do not mix directly. The condensate recovery unit includes a condensate recovery pipe 6, a water quality sensor 8 and a three-way valve 9. The condensate recovery pipe 6 is connected to the bottom of the fixed discharge expansion container 1. The water quality sensor 8 and the three-way valve 9 are installed on the condensate recovery pipe 6 in sequence. The other two ends of the three-way valve 9 are connected to the desalination device 12 and the water supply tank 13, respectively.

[0017] The heat medium inlet 303 of the cooler 3 is connected to the exhaust pipeline 2. A throttling orifice plate 7 is provided between the heat medium inlet 303 of the cooler 3 and the fixed exhaust expansion container 1. The throttling orifice plate 7 is used to stabilize the exhaust steam flow.

[0018] A cyclone separator 10 is provided between the fixed discharge expansion vessel 1 and the throttling orifice plate 7. The cyclone separator 10 can remove solid impurities in the exhaust steam in advance.

[0019] The circulating water pipeline 5 is equipped with a self-regulating pressure regulating valve 14. The self-regulating pressure regulating valve automatically maintains the cooling water pressure difference, without relying on a complex control system, realizing "pressure self-adaptation", reducing dependence on external control and improving system stability.

[0020] In this invention, the cold medium is secondary demineralized water, and the hot medium is exhaust steam.

[0021] In this embodiment, refer to the appendix. Figure 1A boiler exhaust steam recovery system includes an exhaust expansion tank 1, an exhaust pipeline 2, a cooler 3, a demineralized water circulation unit, and a condensate recovery unit. The cooler 3 is located at the end of the exhaust pipeline 2, with a flange welded to the end of the exhaust pipeline. The exhaust pipeline is connected to the hot medium inlet 303 of the cooler via the flange, and the hot medium outlet is connected to the condensate recovery pipe 6. The exhaust expansion tank 1 is connected to the cooler 3 via the exhaust pipeline 2. The demineralized water circulation unit includes a demineralized water pump 4, and the cold medium inlet 301 and cold medium outlet 302 of the cooler 3 are respectively connected to the demineralized water pump 4 and the circulating water pipeline 5. The condensate recovery unit includes a condensate recovery pipe 6, a water quality sensor 8, and a three-way valve 9, which delivers condensate to a makeup water tank 13 or a desalination device 12 based on the water quality detection results.

[0022] The cooler 3 is a plate heat exchanger. The plate channel spacing of the cooler 3 is ≥5mm. The hot medium inlet is equipped with a throttling orifice plate 7 and a cyclone separator 10. The cold medium outlet 302 is equipped with a self-regulating pressure regulating valve 14.

[0023] The cooler 3 is a 316L stainless steel plate heat exchanger, and the heat exchange area is designed according to the steam volume (for example, 10t / h of steam requires 50㎡ of heat exchange area); the demineralized water pump has a flow rate adjustment range of 3-8t / h and a head ≥30m.

[0024] The circulating water pipeline 5 is equipped with a shut-off valve and a filter, which are devices known in the art.

[0025] The process of using this utility model: The exhaust steam discharged from the fixed-discharge expansion vessel 1 enters the cooler 3 through the vent pipe 2 via the hot medium inlet 303. Secondary demineralized water enters the cooler 3 through the cold medium inlet 301 via the demineralized water pump 4 and flows within the plate flow channel. The secondary demineralized water in the plate flow channel exchanges heat counter-currently with the exhaust steam in the vent pipe 2, without direct mixing. The heated secondary demineralized water enters the deaerator 11 through the circulating water pipeline 5, and is then reused in the boiler system, saving gas and reducing production costs. After heat exchange, most of the exhaust steam forms condensate, which returns to the fixed-discharge expansion vessel 1, while a small portion is directly discharged. The condensate from the fixed-discharge expansion vessel 1 enters the condensate recovery pipe 6, which is equipped with a water quality sensor 8 and a three-way valve 9. Based on the water quality detection result of the water quality sensor 8, if the water quality meets the standard (compliant with GB / T 12145-2016), the condensate recovery pipe 6 will be used to recover the condensate. If the water meets the standard, it is sent to the water supply tank 13 for direct reuse through the three-way valve 9; if it does not meet the standard, it is sent to the desalination device 12 for treatment through the three-way valve.

[0026] The core of this utility model is the cooler 3, which is a plate heat exchanger that adopts a counter-current heat exchange with indirect walls: the low-temperature secondary demineralized water enters from the cold medium inlet 301 and comes into counter-current contact with the exhaust steam transported by the vent pipeline 2 in the plate heat exchanger, without direct mixing, thus achieving heat transfer; the exhaust steam condenses into condensate and flows back to the exhaust expansion vessel 1, and is discharged through the condensate recovery pipe 6; the heated secondary demineralized water returns to the boiler's circulating water system through the cold medium outlet 302, saving gas and reducing production costs.

[0027] This invention employs a plate heat exchanger to separate the exhaust steam and the secondary demineralized water through plates, preventing impurities in the exhaust steam (such as trace amounts of salt carried by boiler wastewater) from mixing into the secondary demineralized water, ensuring the purity of the secondary demineralized water, avoiding working fluid contamination, and reducing treatment costs. The counter-current heat exchange design creates the maximum temperature gradient between the hot medium (exhaust steam) and the cold medium (secondary demineralized water) along the flow direction, resulting in higher heat exchange efficiency (requiring a secondary demineralized water temperature rise ΔT ≥ 30℃) and stable heat exchange efficiency.

[0028] The condensate recovery unit of this utility model is equipped with a water quality sensor 8 and a three-way valve 9. After the condensate is discharged through the condensate recovery pipe 6, the water quality sensor detects the water quality (such as conductivity) in real time. If it meets the standard (complies with GB / T 12145-2016 standard), the three-way valve sends it to the water replenishment tank for direct reuse; if it does not meet the standard, it is sent to the desalination device for treatment.

[0029] During commissioning, the steam flow rate is gradually increased, and the temperature rise of the demineralized water is monitored to ensure it meets expectations (ΔT≥30℃). The pressure difference of the cooler is checked monthly, and backflushing is performed if ΔP≥10kPa. The conductivity of the condensate is tested quarterly to ensure that the water quality meets the GB / T 12145-2016 standard.

[0030] This invention features anti-clogging and easy maintenance. The cyclone separator 10 can pre-remove solid impurities from the exhaust steam. The plate channel spacing of the plate heat exchanger is ≥5mm, reducing impurity deposition. Combined with monthly backflushing (ΔP≥10kPa), it significantly reduces the risk of clogging and the frequency of maintenance. This invention also features pressure adaptive and stable operation. The orifice plate stabilizes the exhaust steam flow, and the self-regulating pressure regulating valve automatically maintains the cooling water pressure difference. It does not rely on a complex control system, achieving "pressure self-adaptation," reducing dependence on external control and improving system stability.

[0031] This invention requires no modification to the existing complex piping network; a cooler is simply added to the end of the venting pipeline. Utilizing counter-current heat exchange between low-temperature demineralized water and venting steam, heat energy recovery and condensate reuse are achieved, reducing initial investment costs. It is suitable for small and medium-sized power plants or industrial boilers. The system integrates intelligent quality-differentiated control and pressure adaptive mechanisms, offering advantages such as high efficiency, low cost, and easy maintenance. It is highly adaptable to various scenarios, not dependent on specific industry piping structures, and applicable to all types of power plants and industrial boilers, thus broadening its application scope.

Claims

1. A boiler exhaust steam recovery system, characterized in that: The system includes a fixed-discharge expansion vessel (1), an emptying pipeline (2), a cooler (3), a demineralized water circulation unit, and a condensate recovery unit. The top of the fixed-discharge expansion vessel (1) is connected to the cooler (3) through the emptying pipeline (2), which passes through and extends out of the cooler (3). The cooler (3) is a plate heat exchanger with multiple plates inside, forming plate flow channels between adjacent plates. The demineralized water circulation unit includes a demineralized water pump (4). The cold medium inlet (301) of the cooler (3) is connected to the demineralized water pump (4), and the cold medium outlet (302) of the cooler (3) is connected to the deaerator (11) through a circulating water pipeline (5). The cold medium enters the cooler (3) through the cold medium inlet (301) and flows in the plate channel. It flows out through the cold medium outlet (302). The cold medium in the plate channel exchanges heat with the hot medium in the drain line (2) in a countercurrent manner. The hot medium and cold medium are separated by the plates and do not mix directly. The condensate recovery unit includes a condensate recovery pipe (6), a water quality sensor (8) and a three-way valve (9). The condensate recovery pipe (6) is connected to the bottom of the fixed discharge expansion container (1). The water quality sensor (8) and the three-way valve (9) are installed on the condensate recovery pipe (6) in sequence. The other two ends of the three-way valve (9) are connected to the desalination device (12) and the water supply tank (13) respectively.

2. The boiler exhaust steam recovery system according to claim 1, characterized in that: The heat medium inlet (303) of the cooler (3) is connected to the venting pipeline (2), and a throttling orifice plate (7) is provided between the heat medium inlet (303) of the cooler (3) and the fixed discharge expansion container (1).

3. A boiler exhaust steam recovery system according to claim 2, characterized in that: A cyclone separator (10) is provided between the fixed discharge expansion container (1) and the throttling orifice plate (7).

4. A boiler exhaust steam recovery system according to claim 1 or 2, characterized in that: The circulating water pipeline (5) is equipped with a self-regulating pressure regulating valve (14).

5. A boiler exhaust steam recovery system according to claim 1 or 2, characterized in that: The plate channel spacing of the plate heat exchanger is ≥5mm.

Images