A steam exhaust recovery system

Abstract

The application discloses a steam exhaust recovery system, which comprises a steam exhaust expander, a deaerator, a shaft seal heater and a control module. A steam exhaust pipe at the top of the steam exhaust expander and an oxygen exhaust pipe of the deaerator form a combined conveying pipeline through a first steam inlet pipe, and a steam exhaust pipeline at the bottom of the steam exhaust expander is connected with a steam exhaust tank through a water seal device with enhanced type (main water seal+U type bypass water seal). The combined pipeline is connected with the shaft seal heater through a second steam inlet pipe. The shaft seal heater uses internal negative pressure to suck the steam exhaust to condense, the heat is used for heating the steam turbine condensate water, the condensate water is returned to a condenser, and the non-condensed gas is discharged by a fan. The control module realizes intelligent regulation and control through linkage of a pressure sensor, a valve group and the fan. The system uses the natural negative pressure in the shaft seal heater to realize double-source collaborative recovery of the steam exhaust of the deaerator and the steam exhaust expander of the steam exhaust tank. The steam exhaust is conveyed to the shaft seal heater through a closed pipeline, the steam exhaust noise is eliminated from the source, the sound environment quality around the power plant is effectively improved, and the environmental protection benefit is remarkable.

Description

Technical Field

[0001] This application belongs to the field of waste incineration power generation technology, specifically a waste steam recovery and utilization system. Background Technology

[0002] During waste incineration, the large fluctuations in the calorific value of waste cause frequent changes in the parameters of the steam system. In order to ensure the deoxygenation effect of the deaerator, the deaerator needs to continuously discharge oxygen-containing exhaust steam. Currently, this exhaust steam pressure is directly vented, which not only causes a large amount of heat energy loss, but also generates exhaust noise, affecting the acoustic environment at the plant boundary.

[0003] Meanwhile, the condensate drain expansion tank, as a key piece of equipment for receiving high-pressure condensate from the entire plant, generates a large amount of secondary exhaust steam during the condensate expansion process. This exhaust steam contains a small amount of non-condensable gas and is also directly discharged through the silencer, further exacerbating energy waste and water vapor loss.

[0004] While some waste steam recovery solutions exist in the current technology, they have significant limitations: Firstly, they only target waste steam from the deaerator alone, failing to cover waste steam from the condensate drain tank and expansion tank, thus limiting the recovery scope. Secondly, the systems rely on independent condensation devices and manual valve group control, making them unsuitable for the highly fluctuating waste steam pressure conditions in waste incineration power plants, easily leading to waste steam delivery interruptions or air backflow problems. Furthermore, because traditional solutions do not consider the pressure balance between the condensate drain tank and the expansion tank, a sudden increase in pressure in the expansion tank can easily cause steam to enter the condensate drain tank, leading to water quality deterioration and consequently affecting boiler feedwater quality. Utility Model Content

[0005] To address the aforementioned problems in existing technologies, this application provides a waste steam recovery and utilization system that can achieve dual-source waste steam recovery, adapt to operating condition fluctuations, and balance energy conservation and environmental protection, thereby overcoming the shortcomings of existing technologies and improving energy utilization efficiency and environmental governance.

[0006] To achieve the above objectives, this application adopts the following technical solution: a waste steam recovery and utilization system, comprising: A condensate expansion container is provided with a steam exhaust pipe at the top and a check valve on the exhaust pipe. The bottom is connected to a condensate tank through a condensate pipe. An enhanced water seal device is provided on the condensate pipe, including a main water seal device and a U-shaped bypass water seal pipe connected in parallel to both ends of the main water seal device. The deaerator has an air vent valve on its exhaust pipe. The exhaust pipe is connected to the primary steam vent pipe and the exhaust pipe before the check valve to form a combined delivery pipeline. The shaft seal heater has a steam-side inlet connected to the combined delivery pipeline via a secondary steam inlet pipe, a water-side inlet connected to the steam turbine, a condensate outlet connected to the condenser, and is also connected to a fan for discharging non-condensable gases. The control module includes a pressure sensor for detecting pressure data of the exhaust pipe and shaft seal heater, and a PLC controller electrically connected to the pressure sensor, fan, vent valve, check valve, and control solenoid valve. The control solenoid valve is installed on the primary steam pipe and the secondary steam pipe.

[0007] The oxygen venting pipe is equipped with a self-regulating pressure regulating valve, which, together with the venting valve, forms a two-stage pressure control system.

[0008] The main water seal device is a vertical sleeve-type water seal device that matches the diameter of the drainage pipe. It includes an outer cylinder, an inner cylinder, and a liquid level observation pipe. The bottom of the outer cylinder is connected to the inlet pipe of the drainage tank through a flange, and the top of the inner cylinder is connected to the outlet pipe of the drainage expansion container through a flange. The inner cylinder is inserted into the outer cylinder to a depth of 2 meters.

[0009] One end of the U-shaped bypass water seal pipe is connected to the pipeline from the outlet of the condensate expansion container to the main water seal via a tee fitting with a one-way valve, and the other end is connected to the pipeline from the outlet of the main water seal to the condensate tank via a tee fitting with a check valve.

[0010] The connection between the secondary steam pipe and the steam-side inlet of the shaft seal heater is equipped with a high-efficiency nozzle ejection and anti-impact structure. The high-efficiency nozzle ejection and anti-impact structure includes a tapered venturi nozzle and a guide vane. The tapered venturi nozzle is located at the end of the pipe, and the guide vane is arranged around the inner wall of the pipe and located downstream of the venturi nozzle. It is used to guide the exhaust steam into the heat exchange tube of the shaft seal heater along the tangential direction.

[0011] The beneficial effects of this application are: This application provides a waste steam recovery and utilization system. By utilizing the natural negative pressure within the shaft seal heater, it achieves dual-source synergistic recovery of waste steam from the deaerator and the condensate expansion tank. The waste steam is transported to the shaft seal heater through a closed pipeline, replacing the traditional direct venting method. This eliminates exhaust noise at its source, effectively improving the acoustic environment quality around the power plant and resulting in significant environmental benefits. While increasing the waste steam recovery rate, the heat released by the condensation of waste steam in the shaft seal heater raises the temperature of the turbine condensate, reducing the heat load on the subsequent low-pressure heaters and effectively saving fuel costs for the waste incineration unit, resulting in significant overall economic benefits. The system relies on the existing equipment of the power plant for retrofitting, requiring no additional complex equipment. Equipment investment is lower than traditional solutions, and the retrofitting period is shorter. It can be carried out simultaneously with power plant shutdowns and maintenance, without affecting normal production, and has broad prospects for widespread application. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the connection structure of the waste steam recovery and utilization system of this application; In the diagram, 1—deaerator, 2—drain tank, 3—steam turbine, 4—shaft seal heater, 5—condenser, 6—vent valve, 7—control solenoid valve, 8—pressure regulating valve, 9—first-stage steam pipe, 10—check valve, 11—exhaust pipe, 12—second-stage steam pipe, 13—pressure sensor, 14—drain expansion tank. Detailed Implementation

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] A waste steam recovery and utilization system includes: a condensate expansion tank 14, a deaerator 1, a steam turbine 3, a shaft seal heater 4, and a control module, wherein the deaerator 1 includes a first deaerator 1 and a second deaerator 1, and the steam turbine 3 includes a first steam turbine 3 and a second steam turbine 3.

[0018] The top of the condensate expansion container 14 is connected to a vent pipe 11 to discharge the exhaust steam generated during expansion. A check valve 10 is installed on the vent pipe 11 to prevent air from being drawn in when the pipeline is under negative pressure and to open for pressure relief when it is under positive pressure. The bottom of the condensate expansion container 14 is connected to the condensate tank 2 via a condensate pipe. An enhanced water seal device is installed on the condensate pipe, including a main water seal device and U-shaped bypass water seal pipes connected in parallel at both ends, to achieve pressure isolation between the condensate tank 2 and the condensate expansion container 14. The main water seal device is a vertical sleeve structure, matched to the diameter of the condensate drain pipe. It includes an outer cylinder, an inner cylinder, and a liquid level observation pipe. The bottom of the outer cylinder is connected to the inlet pipe of condensate tank 2 via a flange, and the top of the inner cylinder is connected to the outlet pipe of condensate expansion container 14 via a flange. The inner cylinder is inserted into the outer cylinder to a depth of 2 meters, forming a 2-meter high water seal, which can withstand a pressure difference of 0.02-0.025 MPa. The increased water seal height significantly improves the pressure variation range of condensate tank 2 and condensate expansion container 14, preventing steam and air crossflow. This is crucial for maintaining the stable operation of the entire system and improving energy recovery efficiency. When the pressure inside condensate tank 2 and condensate expansion container 14 fluctuates, the higher water seal height provides greater resistance, preventing steam from entering condensate tank 2 or air from condensate tank 2 from entering condensate expansion container 14. When the pressure inside the condensate expansion container 14 of the condensate tank 2 increases, the water seal prevents steam from entering the condensate tank 2 through the water seal pipe, avoiding fluctuations in the water inside the condensate tank 2 caused by steam impact, which would affect the normal operation of the condensate tank 2. When the pressure inside the condensate expansion container 14 of the condensate tank 2 decreases, the water seal prevents air from entering the condensate expansion container 14 through the water seal pipe, ensuring a negative pressure environment inside the condensate expansion container 14, which is beneficial for the discharge and recovery of exhaust steam. The U-shaped bypass water seal pipe is connected in parallel to both ends of the main water seal: one end is connected to the pipeline from the outlet of the condensate expansion container 14 to the main water seal through a tee fitting with a one-way valve, and the other end is connected to the pipeline from the outlet of the main water seal to the condensate tank 2 through a tee fitting with a check valve 10. Under normal operating conditions, the main water seal works. When the main water seal fails due to a sudden pressure change, the U-shaped pipe automatically forms a second seal to ensure pressure stability.

[0019] The exhaust pipe is connected to the exhaust pipe 11 of the condensate expansion tank 14 via the primary steam vent pipe 9, before the check valve 10, forming a combined transport pipeline to collect and transport the exhaust steam from deaerator 1 and condensate expansion tank 14. Exhaust valves 6 are installed on the exhaust pipes of deaerator 1 and deaerator 2 respectively to control the exhaust of exhaust steam. The two exhaust pipes are connected to the primary steam vent pipe 9 via connecting pipes. The primary steam vent pipe 9 and the exhaust pipe 11 of the condensate expansion tank 14 are connected before the check valve 10, forming a combined transport pipeline to collect and transport the exhaust steam from deaerator 1 and condensate expansion tank 14. Control solenoid valves 7 are installed on the connecting pipes and connected to a PLC controller to facilitate precise control of the exhaust steam transport of each deaerator 1. A self-regulating pressure regulating valve 8 is also connected in series in the oxygen venting pipe. The pressure regulating valve 8 is used to directly control the amount of exhaust steam entering the primary steam venting pipe 9: the opening is automatically adjusted according to the pressure of deaerator 1: it closes less when the pressure rises to reduce the amount of exhaust steam discharged; it opens more when the pressure drops to prevent air backflow. The pressure regulating valve 8 precisely controls the amount of exhaust steam entering the merging pipeline, forming a two-stage control system with the vent valve 6. The vent valve 6 serves as a backup, opening in case of self-regulating valve failure or emergency to ensure system safety.

[0020] The steam-side inlet of the shaft seal heater 4 is connected to the combined conveying pipeline via a secondary steam inlet pipe 12, utilizing internal negative pressure to draw in and condense exhaust steam; the water-side inlet is connected to the turbine 3, where the heat released during condensation heats the condensate in the turbine 3; the drain outlet is connected to the condenser 5 to recover the condensed working fluid; a fan is also connected to discharge non-condensable gases. A high-efficiency nozzle ejection and impact-resistant structure is installed at the connection point between the high-efficiency exhaust steam conveying and condensation combined conveying pipeline and the steam-side inlet of the shaft seal heater 4. The connection between the secondary steam inlet pipe 12 and the steam-side inlet of the shaft seal heater 4 is equipped with a high-efficiency nozzle ejection and anti-impact structure: a nozzle ejection method is used when the exhaust steam enters the shaft seal heater's intake pipe. A suitable tapered Venturi nozzle is selected based on the exhaust steam flow rate, pressure, and operating parameters of the shaft seal heater 4. During nozzle installation, it is essential to ensure that the nozzle's centerline coincides with the centerline of the shaft seal heater's intake pipe to guarantee accurate injection of exhaust steam into the intake pipe. Guide vanes are installed on the inner wall of the pipe. The shape, number, and installation angle of the guide vanes are designed according to the pipe's inner diameter and the exhaust steam's flow characteristics, enabling the vanes to effectively guide the exhaust steam's flow direction, resulting in a more uniform distribution of exhaust steam within the shaft seal heater 4 and enhancing the contact area between the exhaust steam and the heat exchange tubes.

[0021] When exhaust steam enters the shaft seal heater's intake pipe through the nozzle in the form of a high-speed jet, a negative pressure zone is formed around the nozzle, thereby entraining surrounding steam, enhancing the exhaust steam's suction capacity, and reducing interference with the shaft seal exhaust steam. By rationally designing the nozzle and guide vanes, the exhaust steam and shaft seal exhaust steam can be better mixed before entering the shaft seal heater 4, avoiding impact and interference from the exhaust steam on the shaft seal exhaust steam, ensuring the normal operation of the shaft seal heater 4, improving condensation efficiency, and achieving efficient recovery and utilization of exhaust steam.

[0022] The control module includes a pressure sensor 13 and a PLC controller. The PLC controller is electrically connected to the pressure sensor 13, the blower, and the system valve group, adjusting system parameters in real time to maintain stable operation. Pressure sensors 13 are installed at the exhaust pipe outlet and the shaft seal heater 4 inlet to collect pressure data from the exhaust pipe and inlet in real time. When the negative pressure of the shaft seal heater 4 is detected to be lower than a set threshold, the PLC controller automatically adjusts the speed of the blower and the opening of the self-regulating valve of the shaft seal heater 4, increasing the blower speed to enhance suction capacity and ensure smooth delivery of exhaust steam; if the negative pressure is too high, the blower speed is reduced to avoid over-suction.

[0023] During system operation, exhaust steam from deaerator 1 enters the primary steam inlet pipe 9 via the exhaust pipe (controlled by a self-regulating pressure regulating valve 8 and an air vent valve 6), where it merges with exhaust steam from the exhaust pipe 11 of the condensate expansion tank 14 before the check valve 10, forming a combined transport pipeline. The merged exhaust steam then passes through the secondary steam inlet pipe 12, is guided by a venturi nozzle and guide vanes, and is drawn into the steam side by the negative pressure within the shaft seal heater 4. There, it exchanges heat with the condensate from the turbine 3 on the water side, condensing it. The released heat heats the condensate, and the condensate is transported to the condenser 5 for recovery. Non-condensable gases are discharged by the blower. During this process, an enhanced water seal device blocks pressure crossflow between the condensate expansion tank 14 and the condensate tank 2. The control module monitors and adjusts parameters in real time to ensure stable system operation even when waste incineration conditions fluctuate.

[0024] 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.

[0025] 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.

[0026] 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 waste steam recovery and utilization system, characterized in that, include: A condensate expansion container is provided with a steam exhaust pipe at the top and a check valve on the steam exhaust pipe. The bottom of the condensate expansion container is connected to a condensate tank through a condensate pipe. An enhanced water seal device is provided on the condensate pipe, including a main water seal device and a U-shaped bypass water seal pipe connected in parallel to both ends of the main water seal device. A deaerator, wherein the deaerator’s exhaust pipe is equipped with an air vent valve, and the exhaust pipe is connected to the exhaust pipe in front of the check valve via a primary steam vent pipe to form a combined delivery pipeline; The shaft seal heater has a steam-side inlet connected to the combined delivery pipeline via a secondary steam inlet pipe, a water-side inlet connected to the steam turbine, a condensate outlet connected to the condenser, and is also connected to a fan for discharging non-condensable gases. The control module includes a pressure sensor for detecting pressure data of the exhaust pipe and the shaft seal heater, and a PLC controller electrically connected to the pressure sensor, the fan, the vent valve, the check valve, and the control solenoid valve, wherein the control solenoid valve is installed on the primary steam pipe and the secondary steam pipe.

2. The waste steam recovery and utilization system as described in claim 1, characterized in that, The oxygen venting pipe is equipped with a self-regulating pressure regulating valve, which, together with the venting valve, forms a two-stage pressure control system.

3. The waste steam recovery and utilization system as described in claim 1, characterized in that, The main water seal device is a vertical sleeve-type water seal device that matches the diameter of the drainage pipe. It includes an outer cylinder, an inner cylinder, and a liquid level observation pipe. The bottom of the outer cylinder is connected to the inlet pipe of the drainage tank through a flange, and the top of the inner cylinder is connected to the outlet pipe of the drainage expansion container through a flange. The inner cylinder is inserted into the outer cylinder to a depth of 2 meters.

4. The waste steam recovery and utilization system as described in claim 1, characterized in that, One end of the U-shaped bypass water seal pipe is connected to the pipeline from the outlet of the condensate expansion container to the main water seal via a tee fitting with a one-way valve, and the other end is connected to the pipeline from the outlet of the main water seal to the condensate tank via a tee fitting with a check valve.

5. The waste steam recovery and utilization system as described in claim 1, characterized in that, The connection between the secondary steam vent pipe and the steam-side inlet of the shaft seal heater is provided with a high-efficiency nozzle ejection and anti-impact structure. The high-efficiency nozzle ejection and anti-impact structure includes a tapered venturi nozzle and a guide vane. The tapered venturi nozzle is located at the end of the pipe, and the guide vane is arranged around the inner wall of the pipe and located downstream of the venturi nozzle, which is used to guide the exhaust steam into the heat exchange tube of the shaft seal heater along the tangential direction.

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