A steam exhaust recovery system for a fixed grate expander of a waste incineration power plant

Abstract

The application discloses a steam exhaust recovery system for a fixed-discharge expansion vessel of a waste incineration power plant, which comprises a condenser connected with the fixed-discharge expansion vessel, a condensate tank connected with the condenser, and a pre-filter connected with the condensate tank, wherein a liquid level sensor is arranged in the tank; an output pipe of the pre-filter is connected with a first branch pipe and a second branch pipe based on a three-way reversing valve; a pretreatment device and a delivery pump are sequentially arranged on the first branch pipe; the pretreatment device comprises a sodium ion exchanger, a mixed ion exchanger and a safety filter; the first branch pipe is connected with a boiler makeup water main pipe; a throttling valve is arranged on the second branch pipe and the second branch pipe is connected with a cooling tower makeup water main pipe. The system can efficiently recover the secondary steam generated by the fixed-discharge expansion vessel of the boiler, avoid white pollution caused by direct steam exhaust into the atmosphere, and realize step-by-step utilization of the condensate, thereby greatly reducing the consumption of fresh industrial water, solving the problem of water resource waste caused by traditional exhaust, and realizing the energy saving and emission reduction and resource recycling goals of the power plant.

Description

Technical Field

[0001] This application belongs to the technical field of power plant production equipment, specifically a steam recovery system for a waste incineration power plant's fixed-emission expansion container. Background Technology

[0002] The pressurized hot water discharged from the boiler steam-water system during regular blowdown, emergency water release, continuous discharge, and condensate drainage generates some secondary steam after being expanded in a fixed-discharge expansion tank. This secondary steam is typically released directly into the atmosphere, causing air pollution and wasting water resources. To reduce air pollution and water waste, a fixed-discharge expansion tank steam recovery system is needed to recover and reuse the steam, reducing pollution while maximizing the value of water resource recycling. Utility Model Content

[0003] To address the aforementioned problems in the existing technology, this application provides a steam recovery system for a waste-to-energy incineration plant's fixed-emission expansion vessel. The system uses a condenser to condense secondary steam, processes the steam, and recycles the condensed steam to the boiler feedwater system and circulating water system. To achieve the above objectives, this application adopts the following technical solution: a steam recovery system for a fixed-emission expansion container in a waste incineration power plant, comprising: a condenser connected to the fixed-emission expansion container, a condensate tank connected to the condenser, the condensate tank being connected to a pre-filter, a liquid level sensor being installed inside the tank, the output pipe of the pre-filter being connected to a first branch pipe and a second branch pipe via a three-way reversing valve, a pretreatment device and a transfer pump being installed sequentially on the first branch pipe, the first branch pipe being connected to the boiler feedwater main pipe, a throttle valve being installed on the second branch pipe and being connected to the cooling tower feedwater main pipe, and the condensate tank being provided with an overflow pipe and a drain pipe, both of which are connected to a pit.

[0004] The exhaust gas recovery system also includes a DCS system, which is connected to the constant exhaust expansion tank, condenser, level sensor, transfer pump, and valves in the system.

[0005] The pretreatment equipment includes a sodium ion exchanger, a mixed ion exchanger, and a security filter.

[0006] The condenser's inlet is connected to the industrial water supply main pipe via a pipeline, and a water flow control valve is installed on the pipeline. The outlet is connected to the industrial return water main pipe.

[0007] The boiler feedwater header is connected to the deaerator tank, which is equipped with a liquid level measuring device.

[0008] The pump is equipped with an inlet valve at its input end and an outlet valve and a check valve at its output end.

[0009] The beneficial effects of this application are: This application provides a steam recovery system for the exhaust expansion vessel of a waste-to-energy incineration plant. It efficiently recovers secondary steam generated by the boiler's exhaust expansion vessel, avoiding the white pollution caused by direct steam discharge into the atmosphere. Simultaneously, it utilizes condensate in a cascade manner, significantly reducing the consumption of fresh industrial water and solving the water waste problem caused by traditional discharge methods, thus combining environmental protection and water conservation value. The system uses a pretreatment process to ensure that the recovered water quality is suitable for different water use scenarios, guaranteeing the safe and stable operation of core equipment. Based on a DCS system, it achieves fully automated control of the entire process, flexibly switching the recovery destination according to the condensate tank level, deaerator tank level, and boiler operating status, reducing manual intervention. Furthermore, by optimizing the pipeline switching logic and regeneration system configuration, it improves the system's operational stability and continuity, reduces maintenance costs, and ultimately achieves the energy conservation, emission reduction, and resource recycling goals of the waste-to-energy incineration plant. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the structure of this application; In the diagram, 1—constant discharge expansion vessel, 2—condenser, 3—condensate tank, 4—pre-filter, 5—sodium ion exchanger, 6—mixed ion exchanger, 7—security filter, 8—sump, 9—industrial water supply main pipe, 10—industrial water return main pipe, 11—cooling tower makeup water main pipe, 12—boiler makeup water main pipe, 13—overflow pipe, 14—water tank drain pipe, 15—filter drain pipe, 16—transfer pump, 17—throttle valve, 18—deaerator water tank, 19—three-way reversing valve. Detailed Implementation

[0011] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.

[0012] It should be understood that although the terms "first," "second," "third," etc., may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0013] In the description of this application, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0014] Unless otherwise expressly 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 or an electrical connection; 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. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0015] like Figure 1 The exhaust steam recovery system shown is for a waste-to-energy incineration plant's fixed-emission expansion tank 1, comprising: a fixed-emission expansion tank 1, a condenser 2, a condenser 2 water tank, a primary conveying pipeline, a secondary conveying pipeline, and a DCS system. The primary conveying pipeline supplies water to the boiler feedwater system, and the secondary conveying pipeline supplies water to the circulating water system. The primary conveying pipeline has a higher priority than the secondary conveying pipeline, prioritizing the recovery of condensate for supplying water to the boiler feedwater system.

[0016] Condenser 2 is connected to the constant-discharge expansion vessel 1, condensate tank 3, industrial water supply header 9, and industrial return header 10. Secondary steam generated by the constant-discharge expansion vessel 1 enters the steam side of condenser 2 through pipes, while cooling water from the industrial water supply header 9 enters the cooling side of condenser 2 through pipes. The secondary steam and cooling water exchange heat indirectly through the pipe walls within condenser 2. After releasing heat, the steam condenses into liquid water (condensate). Under gravity, the condensate flows into condensate tank 3 through the condensate outlet pipe at the bottom of condenser 2, completing the "steam condensation - condensate collection" process. The heated cooling water returns to the industrial return header 10, achieving cooling water circulation. Isolation valves are installed on the connecting pipes of industrial water supply header 9, industrial return header 10, and condenser 2 to cut off the inlet and outlet water during maintenance. A water flow control valve is also installed on the inlet pipe to regulate the inlet water flow and control condensation efficiency. A first level sensor is installed inside condensate tank 3 to detect the condensate formation within the tank. The condensate tank 3 is equipped with an overflow pipe 13 and a tank drain pipe 14, both of which are connected to the pit 8. The condensate tank 3 is set with an output liquid level threshold, a low liquid level threshold, and a high liquid level threshold. When the liquid level is lower than the low liquid level threshold, the delivery pump 16 is prohibited from starting. When the liquid level is higher than the high liquid level threshold, the overflow valve is opened. A water flow control valve is installed on the overflow pipe 13. The water flow control valve is linked to the first liquid level sensor (the opening is reduced when the liquid level is low and increased when the liquid level is high).

[0017] The condensate tank 3 is connected to the pre-filter 4, which is a multi-media filter (using quartz sand and activated carbon as the filter media). The pre-filter 4 filters suspended impurities, colloids, and trace organic matter in the condensate, preventing wear on the subsequent transfer pump 16 or blockage of the recycling water point. Isolation valves are installed on both the inlet and outlet pipes of the pre-filter 4 for easy equipment maintenance. A drain port and drain valve are provided at the bottom of the pre-filter 4 for periodic backwashing and drainage. The drain port is connected to the pit 8 via the filter drain pipe 15.

[0018] A three-way reversing valve 19 is installed on the output pipe of the pre-filter 4, connecting it to the first branch of the primary delivery pipeline and the second branch of the secondary delivery pipeline. The first branch is equipped with pretreatment equipment and a delivery pump 16. Considering potential pollution risks during actual operation, such as minor leaks in the boiler blowdown pipeline between the expansion tank and the boiler, wastewater containing hardness (calcium and magnesium ions) and salt (chloride and sulfate ions) may mix with the secondary steam, causing the condensate hardness and conductivity to exceed standards. Long-term operation of system pipelines (such as expansion tanks and condensers) may generate rust debris and scale particles, which may enter subsequent pipelines with the condensate. Therefore, pretreatment equipment including a sodium ion exchanger 5, a mixed ion exchanger 6, and a security filter 7 is installed. The sodium ion exchanger 5 is used for efficient hardness removal, and the mixed ion exchanger 6 is used for deep desalination. The sodium ion exchanger 5 reduces the condensate hardness to meet the boiler feedwater hardness requirements, preventing scaling in pipelines and equipment. The condensate then enters the mixed ion exchanger 6 to remove trace cations such as sodium and potassium ions, as well as anions such as chloride and sulfate ions, significantly extending the regeneration cycle. The exchanger is equipped with a regeneration salt tank and a regeneration pump to achieve automatic regeneration and ensure stable softening effect. Because the inner diameter of the pipe connecting the boiler feedwater header 12 to core components such as the boiler economizer and water-cooled walls is small and the water cleanliness requirements are extremely high, a security filter 7 removes resin debris generated during the operation of the mixed ion exchanger 6, protecting the boiler feedwater system. After pretreatment (filtration + softening), the condensate meets the "condensate recovery water quality standard" in the boiler feedwater treatment design specifications and is delivered to the boiler feedwater header 12 through the output pipe, replacing part of the fresh industrial water and reducing the load on the boiler feedwater preparation system and fresh water consumption. This destination must ensure stable operation of the pretreatment unit and that water quality monitoring data meets standards in real time. A transfer pump 16 is installed to meet the input pressure of the boiler feedwater header 12. The input end of the transfer pump 16 is equipped with a pump inlet valve, and the output end is equipped with a pump outlet valve and a check valve. Pressure control is achieved through a variable frequency constant pressure pump and a check valve. The boiler feedwater header 12 is used to supply water to the deaerator water tank 18. A second liquid level sensor is installed in the deaerator water tank 18 to detect the water supply status in the deaerator water tank 18.

[0019] The second branch pipe is equipped with a throttle valve 17 and connected to the cooling tower makeup water header 11, supplying water to the circulating water system. The circulating water system has relatively low water quality requirements; the addition of condensate reduces the amount of fresh industrial water needed for replenishment. Simultaneously, the lower condensate temperature (typically 30-40℃) reduces the cooling load on the cooling tower, improving the operating efficiency of the circulating water system. Because the input pressure of the circulating water system makeup water header is low, the throttle valve 17 reduces the pressure to a preset range.

[0020] The DCS system is connected to the constant-discharge expansion tank 1, condenser 2, first / second level sensors, transfer pump 16, and valves in the system to achieve automatic control of the exhaust steam recovery system. Upon receiving the start signal from the constant-discharge expansion tank 1, the DCS system activates condenser 2 to condense the secondary steam. The first level sensor monitors the condensate generation in condensate tank 3 in real time. When the condensate level in condensate tank 3 meets the output level (ensuring sufficient water delivery and preventing pump idling), the three-way reversing valve 19 switches to the primary delivery pipeline, activating the pre-filter 4, sodium ion exchanger 5, mixed ion exchanger 6, security filter 7, and transfer pump 16, supplying water to the deaerator tank 18 through the boiler feedwater header 12. When the second level sensor detects that the deaerator tank 18 is at a high level and requires no additional water supply, or when the DCS system inputs that the boiler is shut down (e.g., for maintenance or standby), the DCS system switches to the circulating water system for water supply. Switch the three-way reversing valve 19 to the secondary delivery pipeline, close the sodium ion exchanger 5, the mixed ion exchanger 6, the security filter 7 and the delivery pump 16, and open the throttle valve 17 to match the pressure with the circulating water system's makeup water main pipe to complete the water supply.

[0021] In a specific DCS system switching embodiment: Level 1 → Level 2: First, reduce the frequency of the transfer pump 16 from 50Hz to 20Hz (pressure from 1.0MPa to 0.6MPa), maintain for 10 seconds, then shut down the sodium bed, mixed bed, and security filter 7. Next, slowly open the throttle valve 17 (opening from 0% to 80%, taking 20 seconds), and finally shut down the transfer pump 16. Level 2 → Level 1: First turn on the sodium bed, mixed bed, and security filter 7, and flush with a small flow rate (transfer pump 16, frequency 20Hz, 10 seconds). After the water quality meets the standard, slowly increase the frequency to 50Hz and close the throttle valve 17.

[0022] Furthermore, a conductivity meter, hardness meter, and suspended solids meter are installed on the outlet pipe of the security filter 7. An electric isolation valve is added between the pretreatment equipment and the boiler feedwater header 12 and connected to the DCS system. If the conductivity, hardness, or suspended solids detection value exceeds the threshold during the primary pipeline transportation process, the DCS will immediately trigger an alarm and control the three-way reversing valve 19 to switch to the secondary pipeline, shut down the primary pipeline delivery pump 16 to prevent unqualified water from entering the boiler feedwater header 12, and simultaneously shut down the electric isolation valve to form a double protection.

[0023] Finally, it should be noted that in this document, relationships such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "include," "contain," or any other variations are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0024] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0025] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A steam recovery system for a waste-to-energy incineration plant's fixed-emission expansion vessel, characterized in that, include: The system includes a condenser connected to a fixed-discharge expansion tank, a condensate tank connected to the condenser, a pre-filter connected to the condensate tank, a liquid level sensor installed inside the tank, an output pipe of the pre-filter connected to a first branch pipe and a second branch pipe via a three-way reversing valve, a pretreatment device and a delivery pump installed sequentially on the first branch pipe, a connection to the boiler feedwater main pipe, a throttle valve installed on the second branch pipe and connected to the cooling tower feedwater main pipe, and an overflow pipe and a drain pipe, both connected to a pit.

2. The exhaust steam recovery system for a waste-to-energy incineration plant's fixed-emission expansion vessel as described in claim 1, characterized in that, The exhaust gas recovery system also includes a DCS system, which is connected to the fixed exhaust expansion tank, the condenser, the liquid level sensor, the transfer pump, and the valves in the system.

3. The exhaust gas recovery system for a waste-to-energy incineration plant's fixed-emission expansion vessel as described in claim 1, characterized in that, The pretreatment equipment includes a sodium ion exchanger, a mixed ion exchanger, and a security filter.

4. The exhaust gas recovery system for a waste-to-energy incineration plant's fixed-emission expansion vessel as described in claim 1, characterized in that, The condenser's inlet is connected to the industrial water supply main pipe via a pipeline, and a water flow control valve is installed on the pipeline. The outlet is connected to the industrial return water main pipe.

5. The exhaust gas recovery system for a waste-to-energy incineration plant's fixed-emission expansion vessel as described in claim 1, characterized in that, The boiler feedwater header is connected to the deaerator tank, and the deaerator tank is equipped with a liquid level measuring device.

6. The exhaust gas recovery system for a waste-to-energy incineration plant's fixed-emission expansion vessel as described in claim 1, characterized in that, The pump is equipped with an inlet valve at its input end and an outlet valve and a check valve at its output end.

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