Natural gas heating system transformation method

Abstract

The invention relates to the technical field of energy utilization and thermodynamic system transformation, in particular to a natural gas heating system transformation method which comprises the steps that a heat exchange tube bundle is installed in a second steam turbine condenser hot well; a first pipeline is led out from a hot water booster pump outlet mother pipe and connected into a heat exchange tube bundle water inlet connector. A second pipeline is led out from a water outlet connector of the heat exchange tube bundle and is connected to a natural gas heating system pressure regulating station to a waste heat boiler water return pipeline; and isolating valves are respectively arranged on the first pipeline and the second pipeline. Therefore, the problems that in the prior art, heat is excessive, a lithium bromide unit and a heat exchange unit cannot be normally put into operation, and the heat efficiency of a combined unit is low are solved.

Description

Technical Field

[0001] The present application relates to the technical field of energy utilization and thermal system transformation, and in particular to a method for transforming a natural gas heating system. Background Art

[0002] During the 72+24 trial run of the unit, commissioning of the natural gas heating and HVAC systems revealed significant deficiencies in existing technology. The heat required for natural gas heating at the pressure regulating station was far below the design value, resulting in the natural gas heating system being unable to absorb the heat absorbed from the waste heat boiler flue gas. This caused system overheating and cavitation in the hot water booster pump. Furthermore, the lithium bromide unit and heat exchanger were affected and unable to operate normally, failing to achieve energy savings. Furthermore, to address the issue of high condensate subcooling in the condenser, conventional technology typically used a steam system as the heat source, increasing steam consumption and reducing the thermal efficiency of the combined unit. Summary of the Invention

[0003] The present application provides a natural gas heating system modification method to solve the problems in the prior art such as excess heat, inability to operate lithium bromide units and heat exchange units normally, and low thermal efficiency of combined units.

[0004] A first embodiment of the present application provides a method for modifying a natural gas heating system, comprising the following steps: installing a heat exchange tube bundle in the hot well of the No. 2 steam turbine condenser; leading a first pipe from the hot water booster pump outlet main pipe and connecting it to the water inlet interface of the heat exchange tube bundle; leading a second pipe from the water outlet interface of the heat exchange tube bundle and connecting it to the natural gas heating system pressure regulating station to the waste heat boiler return pipe; and respectively providing isolation valves on the first pipe and the second pipe.

[0005] Optionally, the heat exchange tube bundle is a U-shaped stainless steel heat exchanger made of 316L stainless steel, with a tube bundle diameter of 25 mm and a wall thickness of 2 mm. The number of the tubes is not less than 20 and they are staggered and arranged in the middle area of ​​the condenser hot well.

[0006] Optionally, the first pipeline and the second pipeline are both φ108*4 seamless steel pipes, the connection point between the first pipeline and the hot water booster pump outlet main pipe is located between the confluence of the No. 3 hot water booster pump outlet valve and the main pipe, and the connection point between the second pipeline and the natural gas heating system return pipeline is located at the front end of the flow regulating valve.

[0007] Optionally, the isolation valve is a flange-type electric gate valve with a nominal pressure of PN25 and a nominal diameter of DN100, and has remote control and manual operation functions, and the valve opening signal is connected to the unit control system.

[0008] Optionally, the heat exchange process of the transformation method is as follows: the hot water of the natural gas heating system is cooled by the lithium bromide unit, pressurized by the hot water booster pump, enters the heat exchange tube bundle through the first pipeline, and is cooled after heat exchange with the condensate in the condenser hot well, and then returns to the natural gas heating system through the second pipeline.

[0009] Optionally, temperature sensors are installed in the water inlet and outlet pipes of the heat exchange tube bundle and the condenser hot well to monitor the water temperature data in real time and transmit it to the unit control system.

[0010] Optionally, the heat exchange tube bundle and the condenser hot well are sealed and fixed with flanges, tube sheets are provided at both ends of the tube bundle, and expansion joints are used between the tube sheets and the condenser hot well shell to compensate for temperature difference deformation.

[0011] The beneficial effects achieved by adopting the above-mentioned present invention are as follows: The embodiment of the present application installs a U-shaped stainless steel heat exchange tube bundle in the condenser hot well to construct a waste heat recovery loop for the natural gas heating system and condensate, which can significantly reduce the water temperature of the natural gas heating system and completely solve the problems of system overheating and hot water booster pump cavitation. It also changes the traditional method of using the steam system as a heat source to reduce the condensate supercooling, thereby reducing the thermal efficiency of the combined unit. Instead, it uses the heat recovered from the boiler flue gas waste heat to heat the condensate, thereby eliminating the condensate supercooling and improving the thermal efficiency of the combined unit. After the transformation, the lithium bromide unit can be put into operation normally, which can reduce the power consumption of the HVAC system, save electricity, and simultaneously realize the cascade utilization of flue gas waste heat. Therefore, it solves the problems of excess heat, the inability of the lithium bromide unit and heat exchange unit to be put into operation normally, and the low thermal efficiency of the combined unit in the prior art.

[0012] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which: Figure 1 A flowchart of a natural gas heating system modification method provided according to an embodiment of the present application; Figure 2 The present invention provides a flow chart of the heat exchange process of the transformation method according to the embodiment of the present application. DETAILED DESCRIPTION

[0014] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0015] The following describes a natural gas heating system modification method according to an embodiment of the present application with reference to the accompanying drawings. To address the prior art issues mentioned in the background art, such as excess heat, inability to properly operate the lithium bromide unit and heat exchanger, and low thermal efficiency of the combined unit, the present application provides a natural gas heating system modification method. This method significantly reduces the water temperature of the natural gas heating system by installing a U-shaped stainless steel heat exchanger bundle within the condenser hot well, thereby establishing a waste heat recovery loop between the natural gas heating system and the condensate. This method completely resolves the system overheating and hot water booster pump cavitation issues. The method also changes the traditional method of using a steam system as a heat source to reduce condensate subcooling, thereby reducing the thermal efficiency of the combined unit. Instead, the method uses heat recovered from boiler flue gas waste heat to heat the condensate, thereby eliminating condensate subcooling and improving the thermal efficiency of the combined unit. After the modification, the lithium bromide unit can be properly operated, reducing HVAC system power consumption, saving electricity, and simultaneously achieving cascaded utilization of flue gas waste heat. This method solves the prior art issues of excess heat, inability to properly operate the lithium bromide unit and heat exchanger, and low thermal efficiency of the combined unit.

[0016] Specifically, Figure 1 A flow chart of a natural gas heating system modification method provided in an embodiment of the present application.

[0017] like Figure 1 As shown, the natural gas heating system transformation method includes the following steps: In step S101 , a heat exchange tube bundle is installed in the hot well of the condenser of the No. 2 steam turbine.

[0018] Specifically, the No. 2 steam turbine condenser is a key auxiliary machine in the gas-steam combined cycle unit. Its core function is to condense the turbine exhaust steam into liquid water, maintain a vacuum state at the turbine exhaust port, and thus improve the thermal efficiency of the unit.

[0019] It is understood that by installing a heat exchange tube bundle within the hot well of the No. 2 steam turbine condenser, this embodiment of the application establishes a direct heat exchange channel between the natural gas heating system and the condensate, achieving efficient waste heat recovery, eliminating system overheating, and lowering the water temperature, allowing the lithium bromide unit to operate normally. Furthermore, during the heat exchange process, the condensate temperature is raised, eliminating condensate subcooling and improving the unit's thermal efficiency.

[0020] In the embodiment of the present application, the heat exchange tube bundle is a U-shaped stainless steel heat exchanger made of 316L stainless steel, with a tube bundle diameter of 25 mm and a wall thickness of 2 mm. There are no less than 20 tubes, which are staggered and arranged in the middle area of ​​the condenser hot well.

[0021] As can be understood, the present embodiment utilizes U-shaped heat exchange tube bundles arranged in a staggered pattern in the central area of ​​the condenser hot well, maximizing the heat exchange area within a limited space. The staggered arrangement enhances fluid turbulence, improving heat exchange efficiency. Furthermore, the corrosion resistance of 316L stainless steel ensures stable operation under the long-term impact of condensate and high-temperature hot water. The staggered arrangement design does not affect the original water flow path of the hot well, ensuring the normal operation of the condenser's main system and easy maintenance.

[0022] In step S102, a first pipe is led out from the hot water booster pump outlet main pipe and connected to the water inlet interface of the heat exchange tube bundle; It can be understood that the embodiment of the present application leads a first pipe from the hot water booster pump outlet main pipe to the water inlet interface of the heat exchange tube bundle, and can directly use the pressure of the pump outlet to drive high-temperature hot water to flow through the heat exchange tube bundle, avoiding the addition of additional power equipment, simplifying the system process and reducing the modification cost, and ensuring that the hot water is efficiently exchanged with the condensate at a stable flow rate. At the same time, the water intake pipeline is located close to the heat source, reducing heat loss and pipeline resistance, and ensuring the stable operation of the waste heat recovery system.

[0023] In the embodiment of the present application, the first pipeline is a φ108*4 seamless steel pipe, and the connection point between the first pipeline and the hot water booster pump outlet main pipe is located between the confluence of the No. 3 hot water booster pump outlet valve and the main pipe.

[0024] It can be understood that the embodiment of the present application selects the connection point upstream of the valve to avoid the pressure fluctuations caused by the opening and closing of the pump outlet valve affecting the stability of the hot water flow, and the source position close to the junction of the main pipe can directly obtain the stable pressure medium output by the booster pump, ensuring that the hot water pressure at the inlet of the heat exchange tube bundle is maintained at about 1.4MPa, ensuring that hot water flows through the tube bundle at a stable flow rate and exchanges heat with condensate water efficiently. In addition, the structural design of the seamless steel pipe can reduce the risk of pipeline leakage, and the selection of the pipe diameter and connection position does not require large-scale modification of the original main pipe, reducing construction difficulty and modification costs, while ensuring the compatibility of the waste heat recovery system with the original hot water circulation system, ensuring the long-term stable operation of the entire natural gas heating system after modification.

[0025] In step S103, a second pipe is led out from the water outlet interface of the heat exchange tube bundle and connected to the natural gas heating system pressure regulating station to the waste heat boiler return pipe.

[0026] It can be understood that the embodiment of the present application leads a second pipe from the water outlet interface of the heat exchange tube bundle and connects it to the natural gas heating system pressure regulating station to the waste heat boiler return pipe, so that the low-temperature hot water after heat exchange can be directly introduced into the original return pipe, and the pressure difference in the return pipe is used to realize the gravity circulation of hot water, avoiding the addition of power equipment such as circulation pumps, and simplifying the system structure; the access point is located between the pressure regulating station and the waste heat boiler, which can enable the cooled hot water to return to the waste heat boiler in time to participate in the next round of heat exchange, forming a closed cycle of "waste heat boiler flue gas heating → heat exchange tube bundle heat release → waste heat boiler reheating", thereby improving heat utilization efficiency; at the same time, with the help of the layout of the original return pipe, the laying length of the new pipe can be reduced, the construction cost and the heat dissipation loss of the pipe can be reduced, and the original process of the natural gas heating system will not be affected, thereby ensuring the stability and reliability of the system after the transformation and realizing efficient recovery and recycling of waste heat.

[0027] In the embodiment of the present application, the second pipeline is a φ108*4 seamless steel pipe, and the connection point between the second pipeline and the return water pipeline of the natural gas heating system is located at the front end of the flow regulating valve.

[0028] It can be understood that the embodiment of the present application selects the connection point at the front end of the flow regulating valve, which can utilize the stable pressure environment upstream of the valve to avoid the pressure fluctuations generated during valve adjustment affecting the stability of the return water flow, thereby ensuring that the low-temperature hot water can smoothly flow into the return water pipe; at the same time, the connection position is close to the pressure regulating station, which can shorten the laying length of the return water pipe, reduce heat loss and pipe resistance, and with the help of the layout of the original return water pipe, there is no need for large-scale transformation of the system, reducing construction difficulty and cost. In addition, the structure of the seamless steel pipe can reduce the risk of leakage, ensure the sealing of the return water system, and allow the hot water after heat exchange to return to the waste heat boiler in time, forming an efficient heat recycling closed loop, thereby improving the operating efficiency and stability of the entire natural gas heating system.

[0029] In step S104 , isolation valves are respectively provided on the first pipeline and the second pipeline.

[0030] It can be understood that in the embodiment of the present application, isolation valves are respectively provided on the first pipeline and the second pipeline. When the system is under maintenance, the heat exchange tube bundle can be isolated by closing the valve to avoid affecting the normal operation of the natural gas heating system and ensure continuous production of the unit; when the heat exchange tube bundle has a fault such as leakage, the medium flow path can be cut off in time to prevent the accident from expanding; when the system is debugged or the operating parameters are adjusted, the hot water flow can be adjusted through the valve to optimize the heat exchange efficiency; in addition, the setting of the isolation valve can also automatically adjust the valve opening according to the condensate temperature when the desalted water replenishment volume is large in winter, thereby realizing the coordinated operation of the waste heat recovery system and the main system, and improving the safety, flexibility and controllability of the entire natural gas heating system.

[0031] In the embodiment of the present application, the isolation valve is a flange-type electric gate valve with a nominal pressure of PN25 and a nominal diameter of DN100. It has remote control and manual operation functions, and the valve opening signal is connected to the unit control system.

[0032] Specifically, a flanged electric gate valve with a nominal pressure of PN25 and a nominal diameter of DN100 is used as the isolation valve. Its valve body is made of WCB carbon steel, the valve stem is made of 2Cr13 stainless steel, and the sealing surface is welded with STL hard alloy. It is connected through an RF flat-weld flange, matches the φ108 pipe, and has low local resistance. It has the dual functions of remote signal control and manual operation. The valve opening is connected to the unit control system in real time, and the hot water flow can be accurately adjusted. When the hot well water temperature exceeds 58°C or the condensate temperature is lower than 40°C, it will automatically interlock for protection. Manual operation can ensure system operation in emergency situations.

[0033] PN25 indicates a valve design pressure of 2.5 MPa, matching a system operating pressure of 1.4 MPa. This provides a 1.78-fold safety margin to withstand water hammer during startup and shutdown of the hot water booster pump. The DN100 precisely matches the inner diameter of a φ108*4 pipe (100 mm), ensuring a smooth flow path and a local resistance coefficient of ≤0.15, ensuring a pressure loss of ≤0.02 MPa under hot water flow.

[0034] It can be understood that the embodiment of the present application uses a flanged electric gate valve as an isolation valve, which has the dual functions of remote control and manual operation, and the valve opening signal is connected to the unit control system. The valve opening can be remotely and accurately adjusted through the unit control system to control the hot water flow, and achieve real-time matching with the condensate temperature. When the system has abnormalities such as overheating or insufficient heat exchange, it can automatically interlock and adjust to ensure safe operation. The manual operation function can maintain the valve opening and closing in an emergency in the event of a system failure to ensure that the natural gas heating system is not interrupted.

[0035] In the embodiment of the present application, the heat exchange process of the transformation method is as follows: the hot water of the natural gas heating system is cooled by the lithium bromide unit, pressurized by the hot water booster pump, enters the heat exchange tube bundle through the first pipeline, and is cooled after heat exchange with the condensate in the condenser hot well, and then returns to the natural gas heating system through the second pipeline.

[0036] For example, in summer conditions, a 150MW gas-steam combined cycle unit uses this transformation method, such as Figure 2As shown, the natural gas heating system generates 95°C hot water, which is cooled to 80°C by the lithium bromide unit. The hot water booster pump then pressurizes it to 1.4MPa, passing through a φ108 pipe into the heat exchange tube bundle within the hot well. After reverse heat exchange with condensate at 44°C and a flow rate of 77t / h, the temperature is lowered to 60°C before returning to the waste heat boiler. At this point, the condensate temperature rises to 58°C, meeting the operating requirements of the natural gas heating system. The lithium bromide unit can operate normally, providing centralized cooling for the complex building and the central control building. The HVAC system's power consumption is reduced from 105.3kW to 6kW, saving 2383.2kWh per day.

[0037] For example, a 150MW gas-steam combined cycle unit used this retrofit method during winter operation. The demineralized water feed rate was 25 t / h at a temperature of 15°C. The hot water was cooled to 80°C by the lithium bromide unit before entering the tube bundle. It then mixed with the low-temperature demineralized water fed into the hot well for heat exchange. The condensate temperature was maintained at 46°C after heat exchange. The demineralized water feed was preheated from 15°C to 46°C, and the subcooling was reduced from 8°C to 0°C. This fully utilized the boiler tail preheating and improved the boiler's thermal efficiency. At the same time, the natural gas heating system water temperature remained stable at 60°C, resulting in more stable system operation and a 2% increase in boiler efficiency.

[0038] It can be understood that the embodiment of the present application realizes deep recovery of waste heat, eliminates condensate supercooling, and improves the thermal efficiency of the unit through the closed-loop design of "lithium bromide unit pre-cooling → hot water booster pump pressurization → deep heat exchange of heat exchange tube bundle → return water recirculation"; the cooled hot water returns to the natural gas heating system through the second pipeline without changing the original return water path, forming a "heating-heat release-reheating" closed cycle with the waste heat boiler, thereby improving heat utilization.

[0039] In the embodiment of the present application, temperature sensors are installed in the water inlet and outlet pipes of the heat exchange tube bundle and the condenser hot well to monitor the water temperature data in real time and transmit it to the unit control system.

[0040] Specifically, PT100 temperature sensors were installed 1 meter from the inlet of the heat exchanger tube bundle, 1.5 meters from the outlet of the water pipe, and 200 mm from the tube bundle in the middle of the condenser hot well. Two sets of sensors were installed in the hot well to monitor the inlet and outlet temperatures of the condensate. The sensors, with an armored structure and an IP68 protection rating, are connected to the unit's DEH system via shielded cables. They collect water temperature data in real time with a sampling period of 1 second and transmit it synchronously to the unit's control system for display and storage.

[0041] It can be understood that the embodiment of the present application monitors the water temperature in real time through a temperature sensor and connects to the control system, which can optimize the operating efficiency. When the heat exchange efficiency is detected to be reduced, the scaling of the tube bundle can be judged in time and the cleaning program can be started to ensure that the heat transfer coefficient is maintained above 2300W / (m²・K); energy-saving intelligent regulation can be achieved, and the desalted water replenishment amount can be automatically adjusted according to the hot well temperature in winter to avoid a sudden drop in condensate temperature due to low-temperature replenishment. At the same time, historical temperature data can be used to quickly locate faults, improve maintenance efficiency, and reduce downtime losses.

[0042] In the embodiment of the present application, the heat exchange tube bundle and the condenser hot well are sealed and fixed with flanges, tube sheets are provided at both ends of the tube bundle, and expansion joints are used between the tube sheets and the condenser hot well shell to compensate for temperature difference deformation.

[0043] As can be understood, the embodiments of this application utilize flange connections for sealing and fixing, facilitating the installation, maintenance, and replacement of the heat exchange tube bundle. If a tube bundle leaks or scales, the bolts can be quickly removed for repair, shortening downtime for maintenance. The sealing structure of the concave and convex flanges combined with the rubber gasket effectively prevents crosstalk between hot water and condensate, ensuring the purity and safety of the heat exchange system. The provision of expansion joints eliminates thermal stress caused by temperature differences, preventing fatigue cracks or leaks at the connection between the tube sheet and the shell, and extending the service life of the equipment.

[0044] The following is a detailed description of a natural gas heating system modification method using a specific embodiment, as follows: Taking a 150MW gas-steam combined cycle unit as an example, the original natural gas heating system of the unit had problems such as high hot water temperature, inability to put the lithium bromide unit into operation, and high condensate subcooling. This modification method was used to carry out the transformation.

[0045] A heat exchange tube bundle consisting of 24 U-shaped 316L stainless steel tubes with a diameter of 25 mm and a wall thickness of 2 mm is installed in the hot well of the No. 2 turbine condenser. These tubes are staggered in the central area of ​​the hot well. 20 mm thick stainless steel tube sheets are installed at both ends of the bundle. Metal bellows expansion joints are used between the tube sheets and the condenser hot well shell to compensate for temperature differential deformation. The heat exchange tube bundle and the hot well are sealed with flanges to ensure sealing and structural stability. PT100 temperature sensors are also installed in the inlet and outlet water pipes of the heat exchange tube bundle and in the condenser hot well to monitor water temperature in real time and transmit this data to the unit control system.

[0046] A φ108*4 seamless steel pipe was selected as the first pipeline, leading from the hot water booster pump outlet main pipe. The connection point was located between the outlet valve of the No. 3 hot water booster pump and the confluence of the main pipe, and then connected to the water inlet of the heat exchange tube bundle. This pipeline can use the 1.4MPa pressure at the pump outlet to drive 80°C high-temperature hot water through the heat exchange tube bundle. The connection point is located to avoid the impact of pump outlet pressure fluctuations, ensuring a stable hot water supply.

[0047] A φ108*4 seamless steel pipe is used as the second pipeline, leading from the outlet of the heat exchange tube bundle and connecting to the waste heat boiler return pipe at the natural gas heating system pressure regulating station. The connection point is located in front of the flow control valve. The 60°C low-temperature hot water after heat exchange is directly introduced into the existing return pipe. The pressure difference in the return pipe is used to achieve gravity circulation of the hot water, forming a closed cycle of "heating with flue gas from the waste heat boiler, releasing heat from the heat exchange tube bundle, and then reheating in the waste heat boiler."

[0048] Flanged electric gate valves are installed on the first pipeline and the second pipeline as isolation valves respectively. The valves have remote control and manual operation functions, and the valve opening signals are connected to the unit control system.

[0049] After the retrofit, during summer operation, hot water from the natural gas heating system is cooled by the lithium bromide unit, then boosted by the hot water booster pump. It then enters the heat exchange tube bundle through the first pipeline, exchanges heat with the 44°C condensate in the condenser hot well, reducing its temperature to 60°C before returning to the natural gas heating system through the second pipeline. The retrofit has been remarkably effective, with the hot water system temperature remaining stable at 60°C, eliminating the risk of overheating. The condensate temperature has increased from 44°C to 58°C, improving boiler efficiency. During winter operation, the demineralized water makeup and condensate temperature increased from 32°C to 46°C, and the degree of subcooling decreased from 8°C to 0°C, resulting in a 2% increase in boiler efficiency. Simultaneously, the activation of the lithium bromide unit reduced HVAC system power consumption by 35%, saving over 429,000 kWh annually and significantly improving economic benefits and energy efficiency.

[0050] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "N" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0052] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application belong.

[0053] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiment, the N steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having logic gate circuits for implementing logical functions on data signals, an application-specific integrated circuit having suitable combinational logic gate circuits, a programmable gate array (PGA), a field-programmable gate array (FPGA), etc.

[0054] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

Claims

1. A method for modifying a natural gas heating system, characterized in that: The following steps are involved: Install heat exchange tube bundles in the hot well of the No. 2 steam turbine condenser; Leading out a first pipe from the outlet main pipe of the hot water booster pump and connecting it to the water inlet interface of the heat exchange tube bundle; A second pipe is led out from the water outlet interface of the heat exchange tube bundle and connected to the natural gas heating system pressure regulating station to the waste heat boiler return pipe; Isolation valves are respectively provided on the first pipeline and the second pipeline.

2. A natural gas heating system modification method according to claim 1, characterized in that: The heat exchange tube bundle is a U-shaped stainless steel heat exchanger made of 316L stainless steel, with a tube bundle diameter of 25mm and a wall thickness of 2mm. There are no less than 20 tubes, which are staggered and arranged in the middle area of ​​the condenser hot well.

3. A natural gas heating system modification method according to claim 1, characterized in that: The first pipeline and the second pipeline are both φ108*4 seamless steel pipes. The connection point between the first pipeline and the hot water booster pump outlet main pipe is located between the confluence of the No. 3 hot water booster pump outlet valve and the main pipe. The connection point between the second pipeline and the natural gas heating system return pipeline is located at the front end of the flow regulating valve.

4. A natural gas heating system modification method according to claim 1, characterized in that: The isolation valve is a flange-type electric gate valve with a nominal pressure of PN25 and a nominal diameter of DN100. It has remote control and manual operation functions, and the valve opening signal is connected to the unit control system.

5. A natural gas heating system modification method according to claim 1, characterized in that: The heat exchange process of the transformation method is as follows: hot water from the natural gas heating system is cooled by the lithium bromide unit, pressurized by the hot water booster pump, enters the heat exchange tube bundle through the first pipeline, exchanges heat with the condensate in the condenser hot well, and the temperature is reduced before returning to the natural gas heating system through the second pipeline.

6. A natural gas heating system modification method according to claim 1, characterized in that: include: Temperature sensors are installed in the inlet and outlet pipes of the heat exchange tube bundle and the condenser hot well to monitor the water temperature data in real time and transmit it to the unit control system.

7. A natural gas heating system modification method according to claim 1, characterized in that: The heat exchange tube bundle and the condenser hot well are sealed and fixed with flanges, tube sheets are arranged at both ends of the tube bundle, and expansion joints are used between the tube sheets and the condenser hot well shell to compensate for temperature difference deformation.

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