A thermal system for intelligent water level control

Abstract

This invention provides a thermal system for intelligent water level control, comprising a heat source, which is a gas-fired boiler. The gas-fired boiler includes a furnace and a water tank. Gas is burned in the furnace to heat water in the water tank. The outlet of the water tank is connected to the inlet of the main heat source circuit, and the return outlet of the water tank is connected to the outlet of the main heat source circuit. A pumping device is installed on the inlet pipe of the water tank for transporting water. A gas valve is installed on the gas pipeline for transporting gas, and an air valve is installed on the air pipeline for transporting air for combustion. A water level sensor is installed inside the water tank. The water level sensor and the pumping device are connected to a controller, which automatically controls the power of the pumping device based on the measured water level in the tank. This invention avoids damage to the water tank and safety accidents caused by excessively low water levels, and also avoids excessive water flow caused by excessively high water levels, thus achieving intelligent water level control.

Description

Technical Field

[0001] This invention relates to the field of heat exchange, and more particularly to a thermal system for intelligent water level control. Background Technology

[0002] Energy is the material foundation for the survival and development of modern society, and a powerful guarantee for the rapid and sustainable development of the national economy. In recent years, with the development of industry and the improvement of people's living standards, my country's energy consumption has been increasing day by day. However, my country is an energy-scarce country, and in order to meet the energy demand of rapid national economic development, the safe and efficient utilization of energy at multiple levels has become an urgent task.

[0003] Energy conservation and emission reduction technologies are receiving increasing attention in energy-intensive sectors such as thermal engineering, refrigeration, and power generation, and are widely used in equipment such as heat exchangers, chillers, and power plant boilers. Significant progress has been made in the utilization of waste heat resources in my country's industrial sector, particularly high-temperature and medium-temperature waste heat resources. However, compared with developed countries, there is still a gap in the utilization of low-temperature waste heat resources in the industrial sector. With the continuous deepening of energy conservation efforts, the utilization of low-temperature waste heat resources has increasingly become a hot topic and a challenge in energy conservation work. Therefore, the recovery and utilization of various low-grade waste heat from industrial production processes is of great significance, as it not only helps solve my country's energy problems but also effectively reduces environmental pollution. Compared to ORC cycle power generation, direct contact heat exchangers have unparalleled advantages over other heat exchange methods, such as simple structure, resistance to scaling, and high heat transfer efficiency. Moreover, due to the disturbance of gas-liquid two-phase flow, its heat transfer coefficient can be 20-100 times greater than that of single-phase flow, making direct contact heat exchangers one of the most effective waste heat recovery and utilization methods. With the continuous development of direct contact heat exchange theory, direct contact heat exchangers have been widely used in practical production applications such as air conditioning cold storage, medium and low temperature recovery systems, seawater desalination, energy process conversion, salt solution evaporation and crystallization, and wastewater treatment.

[0004] In thermal systems, heat exchangers are widely used in industries such as chemical, petroleum, refrigeration, nuclear energy, and power. Due to the global energy crisis, the demand for heat exchangers in industrial production is increasing, and the quality requirements for heat exchangers are also becoming more stringent. In recent decades, although compact heat exchangers (plate, plate-fin, and welded plate heat exchangers, etc.), heat pipe heat exchangers, and direct contact heat exchangers have developed rapidly, shell-and-tube heat exchangers still dominate in terms of production and usage due to their high reliability and wide adaptability. According to relevant statistics, shell-and-tube heat exchangers still account for about 70% of all heat exchangers used in industrial plants.

[0005] Currently, water level control in the steam drum or water tank of a heating system is crucial, but existing technologies primarily employ single-mode control. For example, water is replenished by detecting the water level height, but this doesn't differentiate between the urgency of the need for replenishment, leading to a series of problems. This invention presents a new system that, through optimized water level and pumping device power settings, particularly through differentiated water level and pumping device power settings, can quickly achieve a constant water level, increase hot water production, and save time. Summary of the Invention

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A thermal system for intelligent water level control includes a heat source, which is a gas-fired boiler. The gas-fired boiler includes a furnace and a water tank. Gas is burned in the furnace to heat water in the water tank. The outlet of the water tank is connected to the inlet of the main heat source circuit, and the return outlet of the water tank is connected to the outlet of the main heat source circuit. A pumping device is installed on the inlet pipe of the water tank for transporting water. A gas valve is installed on the gas pipeline for transporting gas, and an air valve is installed on the air pipeline for transporting air for combustion.

[0008] A water level sensor is installed inside the water tank. The water level sensor and the pumping device are connected to the controller via data transfer. The controller automatically controls the power of the pumping device based on the measured water level inside the tank.

[0009] As an improvement, if the water level drops, the controller increases the flow rate of water entering the tank by increasing the power of the pumping device; if the water level is too high, it reduces the flow rate of water entering the tank or stops supplying water to the tank by reducing the power of the pumping device or shutting down the pumping device.

[0010] Preferably, when the measured water level is lower than the first water level, the controller controls the pumping device to supply water at a first power; when the measured water level is lower than the second water level (which is lower than the first water level), the controller controls the pumping device to supply water at a second power (which is higher than the first power); when the measured water level is lower than the third water level (which is lower than the second water level), the controller controls the pumping device to supply water at a third power (which is higher than the second power); when the measured water level is lower than the fourth water level (which is lower than the third water level), the controller controls the pumping device to supply water at a fourth power (which is higher than the third power); and when the measured water level is lower than the fifth water level (which is lower than the fourth water level), the controller controls the pumping device to supply water at a fifth power (which is higher than the fourth power).

[0011] Preferably, the first water level is 1.15-1.25 times the second water level, the second water level is 1.15-1.25 times the third water level, the third water level is 1.15-1.25 times the fourth water level, and the fourth water level is 1.15-1.25 times the fifth water level.

[0012] Preferably, the order is: fifth power / fourth power > fourth power / third power > third power / second power > second power / first power.

[0013] Preferably, the fifth power is 1.7-1.9 times the fourth power, the fourth power is 1.6-1.8 times the third power, the third power is 1.5-1.7 times the second power, and the second power is 1.3-1.5 times the first power.

[0014] Preferably, a main valve is installed on the main heat source line, and the inlet and outlet of the heat source branch are respectively connected to the upstream and downstream of the main valve of the main heat source line; the heat source branch includes an inlet heat source branch, a heat exchanger, an intermediate heat source branch, and an outlet heat source branch connected in sequence; the inlet heat source branch is equipped with an inlet valve to control the connection with the upstream of the main heat source line, and the outlet heat source branch is equipped with an outlet valve to control the connection with the downstream of the main heat source line.

[0015] Preferably, the cold source is air, which is heated and then directly enters the boiler furnace.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] This invention avoids damage to the water tank and safety accidents caused by excessively low water levels, while also preventing excessive water flow due to excessively high water levels, thus achieving intelligent water level control. Furthermore, by setting the power ratio of the aforementioned water pumps, the replenishment of water reflects the urgency of the need for replenishment. For example, when the water level is below the fifth level, an emergency is particularly needed, and then the power ratio gradually decreases, reflecting the priority of urgency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the thermal system structure of the present invention.

[0019] Figure 2 This is a schematic diagram of the thermal system control structure of the present invention. Detailed Implementation

[0020] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] Figure 1 The thermal system of the present invention has been disclosed. For example... Figure 1As shown, a heat exchange system for heat sources includes a main heat source line 1, a main cold source line 2, a heat source branch line, and a cold source branch line 4. A main valve 5 is installed on the main heat source line. The inlet 6 and outlet 7 of the heat source branch line are respectively connected upstream and downstream of the main valve of the main heat source line. The heat source branch line includes an inlet heat source branch line 31, a heat exchanger 8, an intermediate heat source branch line 32, and an outlet heat source branch line 33 connected in sequence. An inlet valve 9 is installed on the inlet heat source branch line to control its connection with the upstream of the main heat source line, and an outlet valve 10 is installed on the outlet heat source branch line to control its connection with the downstream of the main heat source line.

[0022] This invention enables the heat source in the heat exchanger to remain in a continuous flow state, inhibiting bacterial growth and ensuring sterilization and disinfection, while also ensuring that users can use the heat source at a certain temperature after heat exchange at any time.

[0023] As an improvement, the cold source branch 4 is connected to the cold source main branch 2, and the cold source branch 4 is connected to the heat exchanger inlet pipe to exchange heat with the heat source entering the heat exchanger.

[0024] As an improvement, the heat source is a boiler.

[0025] As an improvement, a flow regulating valve 12 is provided on the cold source branch 4 to regulate the flow rate of the cold source entering the heat exchanger 8.

[0026] As an improvement, a temperature sensor is provided on the intermediate heat source branch to detect the temperature of the heat source output by the heat exchanger 5.

[0027] As an improvement, the temperature sensor, the flow regulating valve, and the controller are connected for data transmission. The controller controls the opening degree of the flow regulating valve based on the detected temperature.

[0028] As an improvement, when the detected temperature exceeds the set data, the controller controls the flow regulating valve to increase the opening, thereby increasing the cold source flow. As an improvement, when the detected temperature is lower than the set data, the controller controls the flow regulating valve to decrease the opening, thereby reducing the cold source flow.

[0029] As an improvement, the outlet heat source branch is connected to the user pipeline 13, and a user valve 11 is installed on the user pipeline.

[0030] As an improvement, the heat exchanger is a shell-and-tube heat exchanger, with the heat source flowing through the tubes and the cold source flowing through the shell.

[0031] As an improvement, the heat source is hot water, and the cold source is gas. The heated air is then directly introduced into the boiler furnace (in the case of coal-fired or gas-fired boilers) to aid combustion. Alternatively, the heated air can be directly introduced into the user's home.

[0032] As an improvement, the output temperature range of the heat source of heat exchanger 5 is preferably 65°C-75°C.

[0033] like Figure 1 As shown, the shell-and-tube heat exchanger is arranged vertically, and multiple baffles are installed inside the shell.

[0034] As an improvement, the shell-side and tube-side flow is counter-current. Along the flow direction of the fluid in the tube side, the spacing of the baffles continuously increases from the tube inlet to the middle of the tube side. Then, from the middle of the tube side to the tube outlet, the spacing of the baffles continuously decreases. Because the heat transfer per unit length along the fluid flow path is relatively uniform during counter-current flow, the overall heat transfer effect is optimal. However, experiments and simulations have shown that the heat transfer in the middle is significantly greater than that at the tube inlet and outlet. Therefore, by changing the baffle spacing, the heat transfer area between the tube-side fluid and the shell-side fluid in the baffles also changes. This area change compensates for the uneven heat transfer, thereby further improving the heat transfer efficiency.

[0035] As an improvement, along the flow direction of the fluid within the tube, the spacing of the baffles increases progressively from the tube inlet to the middle of the tube. Then, from the middle of the tube to the tube outlet, the spacing of the baffle assembly decreases progressively. These variations in spacing make the heat transfer per unit length of the fluid flow more uniform, further improving heat transfer efficiency.

[0036] The shell-and-tube heat exchanger 5 has multiple horizontal baffles inside its shell. The baffles include a circular baffle located at the center of the shell and an annular baffle located around the shell. The circular baffles and the annular baffles are arranged adjacent to each other. Along the upward flow direction of the gas, the area of ​​the annular baffles gradually increases and then gradually decreases, while the area of ​​the circular baffles gradually decreases and then gradually increases.

[0037] During the research, it was found that the baffles in traditional heat exchangers exhibit uneven heat transfer across their cross-section in the upward gas flow direction. The heat transfer is better around the bottom inlet and outlet, and better at the center than at the edges. This invention changes the area of ​​the circular and annular baffles in the baffle assembly along the upward gas flow direction. This causes the fluid in the shell-side to gradually move towards the center, enhancing heat transfer in the heat exchange tubes around the fluid center, then further enhancing heat transfer in the heat exchange tubes at the top and bottom of the shell, and strengthening heat transfer at the bottom inlet center and top outlet. This changes the previous top-to-bottom single heat transfer method, enhancing heat transfer efficiency at different locations, resulting in more uniform heat transfer overall, and further achieving the goal of enhanced heat transfer.

[0038] The area mentioned above is the area projected onto the cross-section of the shell, or the area projected onto a horizontal plane.

[0039] The outlet pipe of the cold fluid heat exchanger 5 is equipped with a manual shut-off valve for use during maintenance.

[0040] When the user is not using water, they close the flow regulating valve 12 and the user valve 11, and open the outlet valve 10. The heat source flows along the main pipeline; simultaneously, it flows into the main pipeline along the heat source branch 31, the heat exchanger 8, the intermediate heat source branch 32, and the outlet heat source branch 33. In other words, both the main pipeline and the branch pipelines can provide the same heat source.

[0041] When a user needs water, they open the flow regulating valve 12, close the outlet valve 10, and open the user valve 11. As the heat exchange process between the heat exchanger 5 and the cold fluid proceeds, the water temperature in the intermediate branch decreases, and the water temperature displayed by the temperature sensor 8 is recorded in real time. When the temperature drops to the desired value, water is drawn from the user's pipeline. When the user stops using water, they close the flow regulating valve 12, leaving the user valve 11 open to continuously discharge cold water. When the water temperature returns to 70°C, they close the user valve 11 and simultaneously open the outlet valve 10, thus realizing the normal water use function of the heat source system.

[0042] The thermal system provided by this invention is particularly suitable for users who use hot water intermittently. When the user is not using it, the heat source in the heat exchanger 5 remains in a flowing state, which can better meet the verification requirements. It can also provide different user water temperatures and flow rates, and can meet the needs of users with large flow rates.

[0043] The heat source is a gas-fired boiler 15. For example... Figure 2 As shown, the gas-fired boiler includes a furnace 16 and a water tank 14. Gas is burned in the furnace 16 to heat water in the water tank 14. The outlet of the water tank is connected to the inlet of the main heat source line 1, and the return outlet of the water tank is connected to the outlet of the main heat source line 1. A pumping device is installed on the water tank inlet pipe for transporting water.

[0044] As an improvement, a gas valve is installed on the gas pipeline 177 that transports gas, and an air valve is installed on the air pipeline 18 that transports air for combustion.

[0045] A water level sensor is installed inside the water tank 14. The water level sensor and the pumping device are connected to the controller via data transfer. The controller automatically controls the power of the pumping device based on the measured water level inside the tank. If the water level drops, the controller increases the power of the pumping device to increase the flow rate of water entering the tank. If the water level is too high, the controller reduces the power of the pumping device or shuts it off to reduce the flow rate of water entering the tank or stops supplying water to the tank.

[0046] The above settings prevent dry burning caused by low water levels, which could damage the water tank and lead to safety accidents. On the other hand, they also prevent excessive water flow caused by high water levels, thus achieving intelligent water level control.

[0047] When the measured water level is lower than the first water level, the controller controls the pumping device to supply water at the first power; when the measured water level is lower than the second water level (which is lower than the first water level), the controller controls the pumping device to supply water at the second power (which is higher than the first power); when the measured water level is lower than the third water level (which is lower than the second water level), the controller controls the pumping device to supply water at the third power (which is higher than the second power); when the measured water level is lower than the fourth water level (which is lower than the third water level), the controller controls the pumping device to supply water at the fourth power (which is higher than the third power); when the measured water level is lower than the fifth water level (which is lower than the fourth water level), the controller controls the pumping device to supply water at the fifth power (which is higher than the fourth power).

[0048] Preferably, the power ratio is: fifth power / fourth power > fourth power / third power > third power / second power > second power / first power. By setting the power ratio of the water pumps as described above, the water replenishment reflects the urgency of the need for replenishment. For example, when the water level is below the fifth level, an emergency is particularly needed, and then the power ratio gradually decreases, reflecting the order of urgency.

[0049] The first water level is 1.15-1.25 times the second water level, the second water level is 1.15-1.25 times the third water level, the third water level is 1.15-1.25 times the fourth water level, and the fourth water level is 1.15-1.25 times the fifth water level.

[0050] The fifth power is 1.7-1.9 times the fourth power, the fourth power is 1.6-1.8 times the third power, the third power is 1.5-1.7 times the second power, and the second power is 1.3-1.5 times the first power.

[0051] By optimizing the water level and pumping device power, especially by setting differentiated water level and pumping device power, a constant water level can be quickly achieved, increasing hot water output and saving time.

[0052] As an improvement, a temperature sensor is installed on the main heat source circuit. The gas valve and air valve are connected to the controller 19 via data connection, and the controller controls the opening degree of the gas valve and air valve according to the detected heat source temperature of the main heat source circuit.

[0053] When the detected temperature of the main heat source circuit is lower than the set value, the controller increases the opening of the gas valve and air valve to increase the amount of gas and combustion air entering the system. Conversely, when the detected temperature of the main heat source circuit is higher than the set value, the controller decreases the opening of the gas valve and air valve to reduce the amount of gas and combustion air entering the system. By increasing or decreasing the heat output of the water tank, the controller ensures that the output temperature remains constant.

[0054] While the present invention has been disclosed above with reference to preferred embodiments, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A thermal system for intelligent water level control, comprising a heat source, wherein the heat source is a gas-fired boiler, the gas-fired boiler includes a furnace and a water tank, wherein gas is burned in the furnace to heat water in the water tank, the outlet of the water tank is connected to the inlet of the main heat source circuit, and the return outlet of the water tank is connected to the outlet of the main heat source circuit; a pumping device is installed on the inlet pipe of the water tank for transporting water; a gas valve is installed on the gas pipeline for transporting gas, and an air valve is installed on the air pipeline for transporting air for combustion. A water level sensor is installed inside the water tank. The water level sensor and the pumping device are connected to the controller. The controller automatically controls the power of the pumping device based on the measured water level inside the tank. A main valve is installed on the main heat source line, and the inlet and outlet of the heat source branch are respectively connected to the upstream and downstream of the main valve of the main heat source line; the heat source branch includes an inlet heat source branch, a heat exchanger, an intermediate heat source branch and an outlet heat source branch connected in sequence; the inlet heat source branch is equipped with an inlet valve to control the connection with the upstream of the main heat source line, and the outlet heat source branch is equipped with an outlet valve to control the connection with the downstream of the main heat source line; The heat exchanger is a shell-and-tube heat exchanger, with the heat source flowing through the tubes and the cold source flowing through the shell; the heat source is hot water, and the cold source is gas; the shell-and-tube heat exchanger is arranged vertically, and multiple horizontal baffles are installed inside the shell of the shell-and-tube heat exchanger. The baffles include a circular baffle located at the center of the shell and annular baffles located around the shell; the circular baffles and annular baffles are arranged adjacent to each other, and along the upward flow direction of the gas, the area of ​​the annular baffles first gradually increases and then gradually decreases, while the area of ​​the circular baffles first gradually decreases and then gradually increases.

2. The thermal system as described in claim 1, characterized in that, If the water level drops, the controller increases the power of the pumping device to increase the flow of water into the tank. If the water level is too high, it reduces the power of the pumping device or shuts it off to reduce the flow of water into the tank or stops supplying water to the tank.

3. The thermal system as described in claim 2, characterized in that, When the measured water level is lower than the first water level, the controller controls the pumping device to supply water at the first power; when the measured water level is lower than the second water level (which is lower than the first water level), the controller controls the pumping device to supply water at the second power (which is higher than the first power); when the measured water level is lower than the third water level (which is lower than the second water level), the controller controls the pumping device to supply water at the third power (which is higher than the second power); when the measured water level is lower than the fourth water level (which is lower than the third water level), the controller controls the pumping device to supply water at the fourth power (which is higher than the third power); when the measured water level is lower than the fifth water level (which is lower than the fourth water level), the controller controls the pumping device to supply water at the fifth power (which is higher than the fourth power).

4. The thermal system as described in claim 3, characterized in that, The first water level is 1.15-1.25 times the second water level, the second water level is 1.15-1.25 times the third water level, the third water level is 1.15-1.25 times the fourth water level, and the fourth water level is 1.15-1.25 times the fifth water level.

5. The thermal system as described in claim 4, characterized in that, Fifth power / Fourth power > Fourth power / Third power > Third power / Second power > Second power / First power.

6. The thermal system as described in claim 5, characterized in that, The fifth power is 1.7-1.9 times the fourth power, the fourth power is 1.6-1.8 times the third power, the third power is 1.5-1.7 times the second power, and the second power is 1.3-1.5 times the first power.

7. The thermal system as described in claim 1, characterized in that, The cold source is air, which is heated and then directly enters the boiler furnace.

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