A control device for automatic oil return applied to a low-temperature waste heat generator

Abstract

The utility model discloses a control device for automatic oil return applied to low temperature waste heat generator, including turbine generator, evaporimeter, condenser, working medium pump and lubricating system, and lubricating system is connected with evaporimeter, and lubricating system includes lubricating oil storage tank, turbine high pressure volute and ejector, and evaporimeter includes steam import pipeline, and the upper portion of evaporimeter is provided with a plurality of oil return ports, and oil return port is connected with the inlet of turbine high pressure volute, and the outlet of turbine high pressure volute is connected with the inlet of ejector, and the outlet of ejector is connected with lubricating oil storage tank, forms lubricating oil circuit, compared with prior art, the utility model discloses the high and low of liquid level in evaporimeter through control module control, has replaced the manual oil return mode of traditional dependence on artificial judgment and operation, has greatly reduced the burden of operating personnel, has reduced the risk of artificial misoperation, has realized the automation of oil return process, has improved operation convenience significantly, has improved the automation level of entire generator set.

Description

Technical Field

[0001] This utility model relates to the field of organic Rankine cycle power generation equipment, specifically to an automatic oil return control device applied to a low-temperature waste heat generator. Background Technology

[0002] Organic Rankine Cycle (ORC) low-temperature waste heat power generation technology, as a highly efficient means of recovering low-grade heat energy, has been widely used in the field of industrial waste heat recovery. ORC generator sets typically include a turbine generator, evaporator, condenser, working fluid pump, and lubrication system. Among these, lubricating oil plays a crucial role in lubricating and cooling key components of the turbine generator, such as bearings.

[0003] In actual operation, especially during frequent start-ups and shutdowns of the unit, lubricating oil can easily enter the evaporator from the oil tank. Since the density of lubricating oil is usually less than that of the organic working fluid used in the system, it will float on the surface of the working fluid, causing the oil level in the lubricating oil tank to drop. When the oil level is too low, the pressure difference between the inlet and outlet of the oil pump is insufficient, failing to provide adequate lubrication to the turbine generator. This can lead to the system failing to start or operate normally, posing a risk of equipment damage.

[0004] Currently, the commonly used solution in the industry is manual oil return. This involves operators manually adjusting the evaporator's operating parameters to try and control the liquid level in the evaporator at the height of the oil return port, so that the floating lubricating oil, under the pressure difference between the inside and outside of the system, is transported back to the oil tank through the oil return pipeline and ejector. However, this manual control method has significant drawbacks: First, it has low control precision, relying entirely on the operator's experience, making it difficult to accurately and stably maintain the liquid level at the optimal oil return position, potentially leading to incomplete oil return or working fluid loss; second, it has slow response and low efficiency, requiring continuous manual monitoring and operation, increasing the workload of operators, and failing to achieve real-time precise control; third, it has poor system stability, as fluctuations in the liquid level may affect the heat exchange efficiency of the evaporator and even the stable operation of the entire ORC system. Utility Model Content

[0005] The purpose of this invention is to address the issue that when existing low-temperature waste heat power generation equipment starts up, some lubricating oil enters the evaporator and needs to be manually recovered. However, the liquid level in the evaporator cannot be accurately controlled, thus failing to ensure that the lubricating oil level in the system is exactly at the inlet position of the oil pipeline. To address this shortcoming, an automatic oil return control device for low-temperature waste heat power generation is proposed.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An automatic oil return control device for a low-temperature waste heat generator includes a turbine generator, an evaporator, a condenser, a working fluid pump, and a lubrication system. The lubrication system is connected to the evaporator and includes a lubricating oil storage tank, a turbine high-pressure volute, and an ejector. The evaporator includes a steam inlet pipe and a level sensor inside the evaporator for monitoring the levels of lubricating oil and organic working fluid. Several oil return ports are located at the top of the evaporator, connected to the inlet of the turbine high-pressure volute. The outlet of the turbine high-pressure volute is connected to the inlet of the ejector, and the outlet of the ejector is connected to the lubricating oil storage tank, forming a lubricating oil circuit. The working fluid inlet of the evaporator is connected to the working fluid pump, the working fluid outlet of the evaporator is connected to the condenser, and the working fluid outlet of the condenser is connected to the working fluid pump, forming a working fluid pump circuit. A heat source control valve is installed on the steam inlet pipe.

[0008] As a further preferred embodiment of this utility model, an oil return pipeline is provided between the oil return port and the inlet of the turbine high-pressure volute, and an oil return pipeline valve is provided on the oil return pipeline.

[0009] As a further preferred embodiment of this invention, it also includes a control module, which is connected to the liquid level sensor, the working fluid pump, and the heat source control valve.

[0010] As a further preferred embodiment of this invention, the control module employs a PID controller.

[0011] The automatic oil return control device for low-temperature waste heat generators proposed in this utility model has the following advantages compared with the prior art:

[0012] 1. This utility model controls the liquid level in the evaporator through a control module, replacing the traditional manual oil return mode that relies on manual judgment and operation. This greatly reduces the burden on operators, lowers the risk of human error, automates the oil return process, significantly improves the ease of operation, and enhances the automation level of the entire generator set.

[0013] 2. This utility model adopts real-time feedback based on liquid level sensor and performs precise closed-loop regulation of heat source control valve and working fluid pump through PID controller. It can quickly and accurately stabilize the liquid level in the evaporator at the optimal position of oil return port, ensuring that the lubricating oil can be continuously, thoroughly and efficiently pressed back to the oil tank, while effectively avoiding unnecessary loss of working fluid.

[0014] 3. This utility model, through a coordinated control strategy of "thermal regulation (valve) and mechanical delivery (working fluid pump)," can smoothly respond to system disturbances and maintain dynamic stability of the evaporator liquid level. This not only optimizes the oil return process but also reduces the negative impact of drastic liquid level fluctuations on the evaporator heat exchange efficiency, thereby ensuring the overall stable and reliable operation of the ORC system.

[0015] 4. The hardware involved in this utility model (such as liquid level sensor, regulating valve, variable frequency pump, and general controller) are all common industrial components. They can be easily integrated into newly built or renovated low-temperature waste heat power generation projects without large-scale modification of the existing ORC system structure. They have good versatility and economy and high promotion value. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the lubricating oil return pipeline in an existing organic Rankine cycle power generation system;

[0017] Figure 2 This is a schematic diagram of the connection relationship of an automatic oil return control device for a low-temperature waste heat generator, which relates to this utility model.

[0018] Figure 3 This is a schematic diagram of the control module connection of this utility model;

[0019] Figure 4 This is a flowchart illustrating the control method using a control device.

[0020] The meanings of the labels in the attached diagram are as follows: 1. Evaporator, 2. Liquid level sensor, 3. Oil return port, 4. High-pressure turbine casing, 5. Ejector, 6. Lubricating oil storage tank, 7. Control module, 8. Condenser, 9. Working fluid pump, 10. Heat source control valve, 11. Oil return pipeline valve. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0022] Under normal circumstances, the low-temperature waste heat generator set will only start when the oil level in the lubricating oil storage tank is higher than that in the oil pump. When the oil level is lower than that in the oil pump, the oil pump will have difficulty drawing lubricating oil, and the pressure difference between the oil pump inlet and outlet (the lubricating oil pressure difference) will be small, which will not provide effective lubrication to the turbine of the unit, so it is not allowed to start.

[0023] This utility model relates to an automatic oil return control device for a low-temperature waste heat generator. It uses a PID controller to automatically control the opening of the heat source valve and the operating frequency of the working fluid pump to control the liquid level in the evaporator, and finally realizes the function of automatic recovery of lubricating oil in the evaporator, solving the inconvenience of manually recovering lubricating oil to the oil tank.

[0024] Example 1: Combining Figure 2An automatic oil return control device for a low-temperature waste heat generator includes a turbine generator, an evaporator 1, a condenser 8, a working fluid pump 9, and a lubrication system. Since this utility model does not involve the overall layout of organic Rankine cycle power generation, its specific connection route is not mentioned. The connection relationship of its organic Rankine cycle power generation system can refer to the connection route of conventional organic Rankine cycle power generation systems. The lubrication system is connected to the evaporator 1. The lubrication system includes a lubricating oil storage tank 6, a turbine high-pressure volute 4, and an ejector 5. The evaporator 1 includes a steam inlet pipe. A level sensor 2 is installed inside the evaporator 1 to monitor the levels of lubricating oil and organic working fluid. Several oil return ports 3 are located at the top of the evaporator 1. These oil return ports 3 are connected to the inlet of the turbine high-pressure volute 4. An oil return pipe is installed between the oil return ports 3 and the inlet of the turbine high-pressure volute 4. An oil return pipe valve 11 is installed on the oil return pipe. The outlet of the turbine high-pressure volute 4 is connected to the inlet of the ejector 5. The outlet of the ejector 5 is connected to the lubricating oil storage tank 6, forming a lubricating oil circuit. The working fluid inlet of the evaporator 1 is connected to the working fluid... Pump 9 is connected, the working fluid outlet of evaporator 1 is connected to condenser 8, and the working fluid outlet of condenser 8 is connected to working fluid pump 9, forming a working fluid pump 9 circuit; a heat source control valve 10 is installed on the steam inlet pipe; liquid level sensor 2, working fluid pump 9 and heat source control valve 10 are all connected to control module 7. Control module 7 adopts PID controller. Liquid level sensor 2 collects liquid level information in evaporator 1 in real time and sends the liquid level information of evaporator 1 to control module 7. Control module 7 compares the liquid level information of evaporator 1 with the distance from oil return port 3 to the bottom of evaporator 1, thereby controlling the opening degree of heat source control valve 10 and the frequency of working fluid pump 9, so as to control the liquid level in evaporator 1 and enable lubricating oil to automatically flow back to lubricating oil storage tank 6.

[0025] Example 2, combined with Figure 4 The control method of the automatic oil return control device for a low-temperature waste heat generator, which relates to this utility model, is as follows:

[0026] When the unit frequently fails to start, the operation of the oil pump causes the lubricating oil in the lubricating oil storage tank to enter the evaporator, resulting in the accumulation of lubricating oil. Since the density of the lubricating oil entering the evaporator is lower than that of the organic working medium, it floats on the top layer of the organic working medium.

[0027] The distance Y from the oil return port to the bottom of the evaporator is read, and the liquid level X inside the evaporator is collected by a liquid level sensor. During system operation, the control module reads the liquid level X in the evaporator in real time and compares it with the distance Y. When the liquid level X is greater than the distance Y, indicating that the lubricating oil level is higher than the oil return port, the liquid level in the evaporator needs to be lowered. Therefore, steam is controlled to enter the evaporator through a heat source control valve. The steam exchanges heat with the organic working fluid, causing the organic working fluid to vaporize. The vaporized organic working fluid then enters the condenser for cooling, thereby lowering the liquid level in the evaporator. When the liquid level X in the evaporator equals the distance Y from the oil return port to the bottom of the evaporator, it indicates that the lubricating oil is at the oil return port. The oil return line valve can be opened. Due to the pressure (the pressure inside the evaporator is higher than the pressure inside the turbine casing), the lubricating oil is pushed into the high-pressure turbine casing and then ejected back to the lubricating oil storage tank through the ejector. When the liquid level X in the evaporator is less than the distance Y from the oil return port to the bottom of the evaporator, it indicates that the lubricating oil level is lower than the oil return port. It is necessary to increase the amount of organic working fluid to raise the liquid level in the evaporator. Therefore, the frequency of the working fluid pump should be increased to increase the amount of organic working fluid, thereby raising the liquid level in the evaporator.

[0028] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that the above embodiments do not limit this utility model in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of this utility model.

Claims

1. An automatic oil return control device for a low-temperature waste heat generator, comprising a turbine generator, an evaporator (1), a condenser (8), a working fluid pump (9), and a lubrication system, wherein the lubrication system is connected to the evaporator (1), characterized in that, The lubrication system includes a lubricating oil storage tank (6), a turbine high-pressure volute (4), and an ejector (5). The evaporator (1) includes a steam inlet pipe. A liquid level sensor (2) is installed inside the evaporator (1) to monitor the liquid level of the lubricating oil and organic working fluid inside the evaporator (1). Several oil return ports (3) are provided on the upper part of the evaporator (1). The oil return ports (3) are connected to the inlet of the turbine high-pressure volute (4). The outlet of the turbine high-pressure volute (4) is connected to the inlet of the ejector (5). The outlet of the ejector (5) is connected to the lubricating oil storage tank (6) to form a lubricating oil circuit. The working fluid inlet of the evaporator (1) is connected to the working fluid pump (9). The working fluid outlet of the evaporator (1) is connected to the condenser (8). The working fluid outlet of the condenser (8) is connected to the working fluid pump (9) to form a working fluid pump (9) circuit. A heat source control valve (10) is installed on the steam inlet pipe.

2. The automatic oil return control device for a low-temperature waste heat generator according to claim 1, characterized in that, An oil return pipeline is provided between the oil return port (3) and the inlet of the turbine high-pressure volute (4), and an oil return pipeline valve (11) is provided on the oil return pipeline.

3. The automatic oil return control device for a low-temperature waste heat generator according to claim 1, characterized in that, It also includes a control module (7), which is connected to a liquid level sensor (2), a working fluid pump (9) and a heat source control valve (10).

4. The automatic oil return control device for a low-temperature waste heat generator according to claim 3, characterized in that, The control module (7) uses a PID controller.

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