Steam generating apparatus

Abstract

The application discloses a steam generating device, which comprises a main heat exchange unit defining a first flue gas flow channel and a steam generating flow channel; water in the steam generating flow channel exchanges heat with flue gas in the first flue gas flow channel to generate steam; a preheating unit defining a preheating flow channel for heating water in the preheating flow channel; a buffer container communicated between a water outlet end of the preheating unit and a water inlet end of the steam generating flow channel; a temperature detector for measuring water temperature, which is arranged on the buffer container or the preheating unit or a communication pipeline between the buffer container and the preheating unit; and a controllable opening and closing pressure relief assembly communicated with the buffer container.

Description

Technical Field

[0001] This disclosure relates to the field of steam generation technology, and more particularly to a steam generation device. Background Technology

[0002] Under the national call for energy conservation and emission reduction, steam generating equipment is accelerating its development towards highly efficient, low-emission, fully premixed condensing steam generators. In particular, inspection-free gas-fired steam generators, compared to traditional steam boilers, produce steam faster, are more energy-efficient and environmentally friendly, and do not require installation inspections or annual boiler audits. They are widely favored by the market and are extensively used in national production and daily life, such as in hotels, restaurants, food processing, textiles, chemicals, and feed processing industries.

[0003] However, most gas-fired steam generators on the market that are exempt from inspection have excessive actual water volume. Especially after the 2020 version of the boiler code was promulgated and implemented, the calculation method for water volume was clarified, namely the total geometric volume inside the steam-water system inlet and outlet, which includes the entire pressurized space from the feedwater pump outlet to the equipment's steam outlet. Based on this calculation method, the water volume of most gas-fired steam generators on the market far exceeds 30 liters, which not only does not meet the boiler code's exemption standard, but also poses a significant safety hazard because the condenser installed inside the equipment is a pressure-bearing component with high pressure requirements.

[0004] To address the aforementioned issues, the applicant applied for a steam boiler disclosed in publication number CN115614722B. This steam boiler operates continuously at low loads for extended periods at some user sites. Under these conditions, the steam consumption of the terminal steam-using equipment is less than the equipment's minimum output load. The boiler body liquid level and the buffer water tank level do not drop to the makeup water level. The water pump operates intermittently due to frequency conversion control based on the water level. The combustion system ignites and runs, and the blower maintains a low speed, shutting down (blower stops, flameout) when the steam pressure in the furnace reaches the set stop pressure to perform post-combustion purging. Afterward, the steam pressure slowly decreases until it reaches the set start-up pressure, at which point the blower starts to perform pre-combustion purging, and the boiler restarts, thus cyclically supplying steam at the set pressure to the terminal. When operating under these conditions for extended periods, the boiler frequently experiences faults such as high temperature and water shortage, rendering it inoperable. Summary of the Invention

[0005] The inventors discovered through research that when the equipment operates under such ultra-low load conditions for extended periods, the extremely small amount of steam consumed at the terminal causes the liquid level inside the boiler to drop very slowly. This results in a very short standby time between shutdown and restart, typically less than 3 minutes. This short cycle leads to frequent boiler start-ups and shutdowns. This frequent start-up and shutdown process exposes a deep-seated design flaw: because the water pump is not working for extended periods during standby, the feedwater inside the condenser (i.e., the preheating unit) at the tail end of the flue gas flow is completely stagnant. The necessary pre- and post-cleaning procedures for each start-up and shutdown cycle blow a large amount of high-temperature flue gas (usually still above 100°C) through the condenser's heat exchange tubes. This high-temperature flue gas continuously heats the stagnant or extremely slow-flowing water inside the condenser's heat exchange tubes, causing its temperature to rise rapidly and eventually vaporize, producing a large amount of water vapor.

[0006] These abnormally generated water vapors travel along the inlet pipe into the connected buffer container (such as a buffer tank). Although the buffer container is usually equipped with an automatic vent valve at the top, the instantaneous steam generation rate under these abnormal operating conditions is much greater than the rate that a conventional vent valve can discharge. As a result, a large amount of water vapor accumulates in the buffer tank, causing the pressure inside the tank to increase rapidly, leading to pressure problems in the condenser and the atmospheric pressure buffer container. The increased pressure inside the tank will, on the one hand, lower the actual water level in the buffer tank, which may cause distortion of the water level detection signal; more seriously, it will create significant back pressure throughout the entire inlet pipe system, especially inside the condenser pipe. With the accumulation of frequent start-stop cycles, this back pressure will continue to rise, and the flow resistance in the inlet pipe will gradually increase until it exceeds the design head of the circulating water pump (usually a small pump). When the system needs to restart and replenish water, although the small pump is running, it cannot overcome the enormous back pressure to smoothly inject water into the buffer tank. At the same time, when the boiler body liquid level drops to the set water replenishment point, the boiler main water pump (usually the large pump) starts running, but the inlet pipeline of the large pump cannot provide the required water supply. If the system detects that it cannot replenish water normally or that the water level is continuously too low, it will trigger the safety protection mechanism, causing the equipment to report an error and shut down.

[0007] In view of the above research, one object of this utility model is to provide a steam generating device to improve the situation of frequent error reports when the device is operating under ultra-low load.

[0008] To achieve the above objectives, this application adopts the following technical solution: A steam generating device, comprising: A main heat exchange unit is defined by a first flue gas flow channel and a steam generation flow channel; the water in the steam generation flow channel exchanges heat with the flue gas in the first flue gas flow channel to form steam; A preheating unit with a preheating channel is used to heat the water in the preheating channel; A buffer container connected between the water outlet of the preheating unit and the water inlet of the steam generating channel; A temperature detector for measuring water temperature is installed on the buffer container, the preheating unit, or the connecting pipe between the buffer container and the preheating unit; A pressure relief assembly that can be controlled to open and close, connected to the buffer container.

[0009] Preferably, the pressure relief assembly includes a pressure relief pipe connected to the buffer container, and the pressure relief pipe is provided with a valve for switching the pipe on and off.

[0010] Preferably, the preheating unit is a condensing heat exchanger, which has a condensing shell and condensing heat exchange tubes disposed on the condensing shell; The connecting pipe includes a preheated water outlet pipe section connecting to the uppermost condenser heat exchanger tube and a vertical water inlet pipe connecting to the top of the buffer container; the temperature detector is installed on the preheated water outlet pipe section.

[0011] Preferably, the preheating outlet pipe section is an L-shaped pipe section, which has a horizontal pipe section and a vertical pipe section that are perpendicular to each other. The outlet end of the preheating unit includes an upper flange disposed at the lower end of the vertical pipe section; the upper end of the vertical inlet pipe is provided with a lower flange connected to the upper flange.

[0012] Preferably, the temperature detector is located on the horizontal pipe section, less than 15 cm away from the condenser shell.

[0013] Preferably, the pressure relief pipe is connected to the top of the buffer container.

[0014] Preferably, the valve is a solenoid valve, and the steam generating equipment has a temperature controller electrically connected to the solenoid valve, the temperature controller being electrically connected to the temperature detector.

[0015] Preferably, the buffer container is a buffer tank, and the top of the buffer tank is also provided with an exhaust valve that can be opened when the internal pressure is greater than a predetermined pressure. Preferably, the exhaust valve is located at the center of the top of the buffer tank. The bottom of the buffer container is also connected to a drainage pipe. The top of the buffer tank is also provided with a water level gauge.

[0016] Preferably, the temperature detector includes a thermocouple; preferably, the horizontal pipe section is provided with a thermocouple tube joint, and the thermocouple is installed on the thermocouple tube joint; the thermocouple is a type K thermocouple.

[0017] Preferably, the pressure relief pipe is a Z-shaped pipe, wherein the solenoid valve is disposed in the vertical section of the pressure relief pipe, and the temperature controller is disposed on the solenoid valve; the end of the pressure relief pipe is a horizontally oriented pressure relief outlet; the pressure relief outlet is lower than the bottom of the buffer tank. Beneficial effects

[0018] The steam generator provided by this utility model is equipped with a temperature detector to monitor the water temperature and a pressure relief component on the buffer container. Before the temperature detector detects that the temperature is close to the vaporization temperature, the pressure relief component is opened to quickly release the pressure, so that the water pump can replenish water into the buffer container normally, thus improving the situation of frequent equipment error reports under ultra-low load.

[0019] Furthermore, after rapid depressurization, the pressure of the buffer container (buffer tank) can be quickly reduced by expelling a large amount of high-temperature water vapor. The preheating unit will replenish water into the buffer container in a timely manner, and the water in the preheating unit will quickly exchange heat with the flue gas, thereby rapidly reducing the temperature of the flue gas in the preheating unit to a safe range.

[0020] In particular, it has the following advantages: Improved equipment reliability under low load conditions: By actively monitoring and releasing the pressure generated by water vaporization in the preheating unit, the water replenishment system was effectively prevented from failing due to excessive back pressure, and the problem of frequent error reporting and shutdown of the equipment under ultra-low load conditions was effectively improved.

[0021] The system's safety performance is enhanced: the controllable pressure relief component can release abnormal pressure in a timely manner, avoiding prolonged overpressure bearing of the buffer container and connected pipelines, reducing potential safety hazards caused by pressure fluctuations, and protecting equipment components; in addition, it can effectively prevent the problem of the preheating unit (condensing heat exchanger) causing the exhaust gas temperature to rise above the alarm point due to the reduced heat absorption capacity after vaporization, thus causing the equipment to alarm and shut down.

[0022] Simple structure and low modification cost: This utility model only requires the addition of a temperature detector and a controllable valve, with minimal changes to the overall structure of the existing steam generating equipment. It is easy to implement and integrate, and has high economic efficiency and feasibility whether it is for new equipment manufacturing or old equipment modification. Attached Figure Description

[0023] Figure 1 This is a perspective view of a steam generating device according to an embodiment of the present invention; Figure 2 yes Figure 1 Internal structure diagram; Figure 3 yes Figure 2 The front view; Figure 4 yes Figure 2 Enlarged view of part I.

[0024] Explanation of reference numerals in the attached figures: 54. Small pump; 55. Booster pump; 100. Main heat exchange unit; 200. Preheating unit; 201. Condensation shell; 202. Condensation heat exchange tube; 25. Water outlet of the preheating unit; 251. Horizontal pipe section; 252. Vertical pipe section; 253. Thermocouple tube connector; 26. Water inlet of the buffer container; 27. Vertical water inlet pipe; 300. Buffer container; 320. Exhaust valve; 310. Pressure relief pipe; 314. Solenoid valve; 315. Thermostat; 316. Pressure relief outlet. Detailed Implementation

[0025] Please see Figures 1 to 4 This utility model provides a steam generating device, which aims to improve or further solve the problem of water replenishment failure caused by water vaporization in the preheating unit under low load and frequent start-stop conditions in the prior art.

[0026] like Figure 1 and Figure 2 As shown, the steam generating equipment in this embodiment generally includes a main heat exchange unit 100 for core heat exchange, a preheating unit 200 for recovering waste heat from flue gas, and a buffer container 300 for stabilizing water supply and preventing cavitation of the booster pump 55.

[0027] The main heat exchange unit 100 is the primary component for steam generation. Its internal structure is complex, with the first flue gas flow path and the steam generation flow path physically separated. The high-temperature flue gas generated by the burner flows in the first flue gas flow path, while the water to be heated flows in the steam generation flow path. Both undergo efficient heat exchange through the pipe walls; the water absorbs heat, rapidly heats up, and ultimately transforms into high-temperature steam, which is output from the equipment's steam outlet to supply the end user.

[0028] The preheating unit 200 is located downstream of the flue gas in the main heat exchange unit 100. Its main function is to utilize the residual heat of the flue gas, which is about to exit the equipment but still retains a considerable temperature, to preheat the cold water entering the equipment. This significantly improves the overall thermal efficiency of the equipment. In a preferred embodiment, the preheating unit 200 is specifically a condensing heat exchanger. Figure 2 As shown, it mainly consists of a condenser shell 201 and multiple condenser heat exchange tubes 202 disposed inside the shell. Flue gas flows through the interior of the condenser shell 201 and the exterior of the heat exchange tubes 202, while the inlet water flows in the preheating channel inside the heat exchange tubes 202. In this way, the water absorbs heat from the flue gas, the flue gas temperature decreases, and even the water vapor in it condenses and releases a large amount of latent heat, thereby achieving efficient waste heat recovery.

[0029] A buffer container 300 is connected between the water outlet 25 of the preheating unit 200 and the water inlet of the steam generation channel of the main heat exchange unit 100. A temperature detector is used to measure the water temperature in real time. Its installation location can be selected on the buffer container 300, the preheating unit 200, or the connecting pipe between the two. In this preferred embodiment, its location is further precisely defined as the water outlet of the preheating unit 200, i.e., the outlet of the uppermost condenser heat exchange tube 202, connected to the buffer container 300 via a connecting pipe. This connecting pipe includes a preheated water outlet section and a vertical water inlet pipe 27. The temperature detector is installed on this preheated water outlet section. This arrangement allows for the most direct and rapid capture of the actual temperature of the water flowing out of the preheating unit 200.

[0030] Specifically, such as Figure 4 As shown, the preheating outlet pipe section is designed as an L-shaped section, mainly composed of a horizontal pipe section 251 and a vertical pipe section 252 connected vertically. The outlet end 25 of the preheating unit 200 is specifically represented by an upper flange located at the lower end of the vertical pipe section 252. The inlet end 26 of the buffer container 300 is connected via a vertical inlet pipe 27, the upper end of which has a lower flange that mates with the aforementioned upper flange. This flange connection method facilitates installation and maintenance.

[0031] To ensure timely and accurate temperature measurement, the temperature detector is mounted on the horizontal pipe section 251, with a distance of less than 15 cm from the condenser shell 201. This distance is crucial because, under low-load shutdown conditions, it is the stagnant water within the condenser heat exchanger tube 202 that is heated. The closer the temperature detection point is to the heat source, the more sensitive the response and the less delay is needed. If the distance is too great, heat transfer will be delayed, potentially leading to a large amount of steam and high pressure buildup in the buffer container before the detector senses the temperature rise, thus missing the optimal time for pressure relief.

[0032] In terms of specific hardware selection, the temperature detector can be a single industrial-grade thermocouple. For ease of installation and sealing, a thermocouple connector 253 is specifically provided on the horizontal pipe section 251. The thermocouple is installed on this connector, with its sensing end extending into the pipe and directly contacting the water flow. To accommodate a wide temperature range and stability requirements in industrial environments, a type K thermocouple is preferred.

[0033] In conjunction with the temperature detector is a controllable pressure relief assembly. This assembly is directly connected to the buffer container 300. In a simplified embodiment, the pressure relief assembly includes a pressure relief pipe 310 that connects to the buffer container 300, and a valve on the pipe for controlling the opening and closing of the pipe.

[0034] To achieve optimal venting performance, the pressure relief pipe 310 is preferably connected to the top of the buffer container 300. This is because both small amounts of air introduced during normal operation and water vapor generated under abnormal conditions, being gases, tend to accumulate at the highest point of the container due to their lower density. Placing the pressure relief port at the top allows for the most efficient removal of these gases.

[0035] To achieve automatic control, the valve is preferably a solenoid valve 314. The steam generator is also equipped with a temperature controller 315, which is electrically connected to the solenoid valve 314, forming an execution loop; simultaneously, the temperature controller 315 is also electrically connected to the aforementioned temperature detector (thermocouple), forming a detection loop. This creates a complete closed-loop automatic control system. When the temperature signal measured by the temperature detector is transmitted to the temperature controller 315, the internal logic circuit or microprocessor of the temperature controller 315 compares it with a preset temperature threshold (e.g., 95°C). Once the measured temperature exceeds this threshold, the temperature controller 315 outputs an electrical signal, driving the solenoid valve 314 to open and perform a pressure relief action. When the temperature drops back to a safe range, the temperature controller 315 disconnects the power supply to the solenoid valve, causing it to automatically close. As a specific, but not limiting, option, the temperature controller 315 can be a commercially available, reliable industrial-grade temperature controller, such as the Hongrun OHR-A103 series temperature controller.

[0036] Furthermore, the pressure relief component can be manually operated via a switch. When the temperature detected by the temperature detector reaches the alarm temperature (near the vaporization temperature), an alarm signal is issued, allowing manual pressure relief by operating the pressure relief component switch. Therefore, the device connection structure of this application is not limited to automatic control connections. Of course, this application does not involve improvements to the computer program. Simply adding a type K thermocouple, a temperature controller 315, and a pressure relief pipe to the steam generating equipment is sufficient. For example, with the Hongrun OHR-A103 series temperature controller, only the trigger temperature needs to be set on the temperature controller; the operator does not need to adjust the algorithm program.

[0037] To further optimize structure and safety, the physical structure of the pressure relief pipe 310 can be designed as a Z-shaped pipe. The solenoid valve 314 can be installed on the vertical section of the pressure relief pipe 310, and the thermostat 315 can be integrated into or installed nearby on the solenoid valve 314 for convenient wiring and debugging. The end of the pressure relief pipe 310, i.e., the pressure relief outlet 316, is designed to be horizontal. More importantly, the installation height of the pressure relief outlet 316 is lower than the bottom of the buffer tank 300. The horizontally oriented pressure relief outlet 316 can guide any potentially discharged high-temperature steam and hot water in a safe direction, preventing vertical upward spray that could injure equipment or personnel above. Furthermore, the pressure relief outlet 316 being lower than the bottom of the tank ensures that even if condensate or carried-out hot water is present during the pressure relief process, it can be smoothly discharged by gravity, preventing accumulation within the pipe.

[0038] In addition, to enhance the functionality of the buffer container 300 (specifically a buffer tank in this embodiment), besides connecting to the aforementioned active pressure relief assembly, a conventional mechanical vent valve 320 can also be installed on the top of the buffer container 300. This vent valve passively opens when the internal pressure exceeds a predetermined safety pressure, and is located at the center of the top of the buffer tank. Furthermore, for ease of maintenance and emptying, a drainage pipe is connected to the bottom of the buffer container. To enable direct monitoring of the water level within the container, a water level gauge is also installed on the top or side wall of the buffer tank.

[0039] It should be noted that the structure and function of the buffer container 300, the main heat exchange unit 100, and the preheating unit 200 in this embodiment can all refer to the steam generating equipment disclosed in CN115614722B, and the repeated parts will not be described again.

[0040] Through the above technical solution, this embodiment installs a temperature detector at a key location near the preheating unit outlet to monitor the water temperature about to enter the buffer container in real time. When the equipment is under low-load, frequent start-stop conditions, the stagnant water (approximately) in the preheating unit is heated by high-temperature flue gas. Once the temperature detector detects an abnormal rise in water temperature, reaching or approaching the boiling point of water (indicating that internal vaporization has begun or is about to occur), this embodiment can manually or actively open the controllable pressure relief component. The pressure relief component promptly discharges the abnormally high-pressure steam generated by water vaporization in the buffer container, thereby effectively avoiding the accumulation of back pressure in the inlet pipe. In this way, when the equipment needs to be replenished with water again, the water pump can overcome normal pipe resistance and smoothly inject water into the buffer container and the main heat exchange unit, ensuring the stable and reliable operation of the equipment, thereby effectively improving the equipment error problem caused by water vaporization in the preheating unit under low-load conditions.

[0041] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the scope of the present utility model. Any modifications, equivalent variations, and alterations made based on the essential technical content of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A steam generating device, characterized in that, include: A main heat exchange unit is defined by a first flue gas flow channel and a steam generation flow channel; the water in the steam generation flow channel exchanges heat with the flue gas in the first flue gas flow channel to form steam; A preheating unit with a preheating channel is used to heat the water in the preheating channel; A buffer container connected between the water outlet of the preheating unit and the water inlet of the steam generating channel; A temperature detector for measuring water temperature is installed on the buffer container, the preheating unit, or the connecting pipe between the buffer container and the preheating unit; A pressure relief assembly that can be controlled to open and close, connected to the buffer container.

2. The steam generating equipment as described in claim 1, characterized in that, The pressure relief assembly includes a pressure relief pipe connected to the buffer container, and the pressure relief pipe is equipped with a valve for switching the pipe on and off.

3. The steam generating equipment as described in claim 2, characterized in that, The preheating unit is a condensing heat exchanger, which is provided with a condensing shell and condensing heat exchange tubes disposed on the condensing shell; The connecting pipe includes a preheated water outlet pipe section connecting to the uppermost condenser heat exchanger tube and a vertical water inlet pipe connecting to the top of the buffer container; the temperature detector is installed on the preheated water outlet pipe section.

4. The steam generating equipment as described in claim 3, characterized in that, The preheated water outlet pipe section is an L-shaped pipe section, which has a horizontal pipe section and a vertical pipe section that are perpendicular to each other. The water outlet end of the preheating unit includes an upper flange located at the lower end of the vertical pipe section; the upper end of the vertical water inlet pipe is provided with a lower flange connected to the upper flange.

5. The steam generating equipment as described in claim 4, characterized in that, The temperature detector is located on the horizontal pipe section, less than 15 cm away from the condenser shell.

6. The steam generating equipment as described in claim 2, characterized in that, The pressure relief pipe is connected to the top of the buffer container.

7. The steam generating equipment as described in claim 4, characterized in that, The valve is a solenoid valve, and the steam generating equipment has a temperature controller electrically connected to the solenoid valve, and the temperature controller is electrically connected to the temperature detector.

8. The steam generating equipment as described in claim 1, characterized in that, The buffer container is a buffer tank, and the top of the buffer tank is also provided with an exhaust valve that can be opened when the internal pressure is greater than a predetermined pressure.

9. The steam generating equipment as described in claim 1, characterized in that, An exhaust valve is located at the top center of the buffer tank; a drainage pipe is also connected to the bottom of the buffer container; and a water level gauge is also installed at the top of the buffer tank.

10. The steam generating equipment as described in claim 7, characterized in that, The temperature detector includes a thermocouple.

11. The steam generating apparatus as described in claim 10, characterized in that, The horizontal pipe section is equipped with a thermocouple tube joint, and a thermocouple is installed on the thermocouple tube joint; the thermocouple is a type K thermocouple.

12. The steam generating equipment as described in claim 7, characterized in that, The pressure relief pipe is a Z-shaped pipe, the solenoid valve is installed in the vertical section of the pressure relief pipe, and the temperature controller is installed on the solenoid valve; the end of the pressure relief pipe is a horizontally oriented pressure relief outlet; the pressure relief outlet is lower than the bottom of the buffer tank.

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