Low temperature hot water vacuum flash evaporation power system

Abstract

The utility model relates to a kind of low-temperature hot water vacuum flash evaporation power generation systems, including flash evaporator, vacuum system, steam turbine, generator and condenser, the input end of the flash evaporator is connected with low-temperature hot water source, the flash evaporator is also connected with vacuum system;Steam-liquid separation assembly is arranged in the flash evaporator, the steam output end of the flash evaporator is connected with steam turbine, the steam turbine is connected with generator;The inlet end of the condenser is connected with the water output end of flash evaporator, while being equipped with hot well, drain expansion tank.The utility model reduces pressure flash evaporation by flash evaporator, the steam of output directly drives steam turbine, and the vacuum of flash evaporator is controlled, and combined with condenser spray reuse, low-temperature hot water power generation applicable temperature is probed to 80 ℃, without heat pump heating, expand 100 degrees below low-temperature hot water working medium direct power generation scene, directly utilize water vapor to drive steam turbine, avoid ORC working substance cost and safety risk and heat pump energy consumption.

Description

Technical Field

[0001] This utility model relates to the field of low-temperature power generation technology, and more specifically, to a low-temperature hot water vacuum flash evaporation power generation system. Background Technology

[0002] There is a large amount of low-temperature hot water in industrial enterprises such as petrochemical plants, and the amount of such hot water is increasing as the scale of the equipment becomes larger. First, it meets the preheating requirements of the process, and second, it provides winter heating or heat tracing for pipelines and equipment in plants, workshops and office buildings. After cascade utilization, there is still hot water with a temperature not higher than 100°C that is difficult to utilize. Traditional technologies generally adopt organic Rankine cycle (ORC) and full-flow screw turbine power generation systems, but the technical approach has inherent limitations.

[0003] The ORC technology faces stringent requirements in terms of working fluid selection, and its toxicity and flammability pose safety risks. It requires continuous replenishment of expensive organic working fluids, and some working fluids (such as R245fa, with a GWP of approximately 1030) contribute to the greenhouse effect and are subject to international environmental agreements. Furthermore, the system is complex, with high initial investment and maintenance costs and a long payback period. Annual maintenance costs account for approximately 2%-5% of the initial investment, and the need for working fluid replenishment and component replacement further increases costs.

[0004] Full-flow screw turbine power generation systems use water directly as the working fluid (without phase change or flash evaporation). An absorption heat pump heats the low-temperature hot water to 100-130°C to drive a screw expander for power generation. However, this system is limited by a temperature threshold, requiring a high-temperature heat source and cannot directly utilize hot water below 100°C. It also relies on organic working fluids (such as lithium bromide) or absorbents, resulting in a long recovery cycle.

[0005] Vacuum flash evaporation technology is a phase change process that utilizes the superheating and rapid vaporization of liquids in a vacuum environment to achieve efficient energy exchange. In existing technologies, coal gasification units use vacuum flash evaporation condensers to treat high-temperature slag water, achieving heat recovery and water resource recycling. In the cold chain industry, vacuum flash evaporation ice-making technology uses a low-pressure environment to instantly freeze water into ice slurry, making it a highly efficient phase change cold storage material.

[0006] However, the inventors discovered that document CN218717007U discloses a low-temperature hot water flash turbine power generation system, mainly focusing on power generation devices and corresponding structural forms using low-temperature hot water as a heat source. Furthermore, this technology's flash system has a fixed vacuum level, making it unsuitable for low-temperature hot water across the entire 80~100℃ range; it can only flash-evaporate hot water at specific temperatures, and its flash-evaporate efficiency drops sharply when the hot water temperature is below 85℃. The condenser only processes turbine condensate; the unflash-evaporate hot water needs to be transported to the pipeline network through additional pipelines, resulting in significant heat loss. Moreover, it lacks multi-parameter linkage control, making it unable to cope with fluctuations in hot water temperature and flow rate, leading to poor system stability.

[0007] Document CN103089341A discloses a power generation device that requires a heat medium at around 150°C or below and adopts a stepped heat exchange method, which cannot independently handle low-grade heat sources and has a low heat recovery rate. Utility Model Content

[0008] In response to the aforementioned technical problems, a low-temperature hot water vacuum flash evaporation electric system is provided.

[0009] The technical means adopted in this utility model are as follows: A low-temperature hot water vacuum flash evaporation electrostatic system includes: a flash evaporator, a vacuum system, a steam turbine, a generator, and a condenser. The input end of the flash evaporator is connected to a low-temperature hot water source, and the flash evaporator is also connected to the vacuum system. The flash evaporator is equipped with a high-efficiency vapor-liquid separation component. The steam output end of the flash evaporator is connected to the steam turbine, and the steam turbine is connected to the generator. The inlet end of the condenser is connected to the water output end of the flash evaporator and the water output end of the steam turbine.

[0010] The high-efficiency vapor-liquid separation component inside the flash evaporator achieves a flash evaporation efficiency of over 99%, effectively removing tiny droplets carried during flash evaporation and preventing these droplets from entering the turbine and causing long-term erosion and damage to the blades, thus increasing maintenance costs. Simultaneously, a spray system is installed at the top to evenly distribute hot water, accelerating hot water flash evaporation and improving flash evaporation efficiency. The low-temperature hot water source is connected to the flash evaporator through multiple branch pipes, the ends of which are connected to the flash evaporator's spray system.

[0011] Furthermore, a condenser spray device is provided on the top of the condenser, and the water output end of the flash evaporator is directly connected to the condenser spray device.

[0012] Furthermore, a hot well is provided at the bottom of the condenser, and several water output pipes are provided at the output end of the hot well. A hot water pump is installed on one of the water output pipes, and a condensate pump is installed on another water output pipe.

[0013] Furthermore, a hydrophobic expansion tank is installed between the condenser and the hot well.

[0014] Furthermore, the condenser is connected to the vacuum system, and the condenser is connected to a vacuum breaking pipeline, on which a vacuum breaking valve is installed.

[0015] Compared with existing technologies, this invention has the following advantages: This invention directly drives a steam turbine using steam output from a flash evaporator, controls the vacuum of the flash evaporator through a vacuum system, and combines this with condenser spray recycling, extending the applicable temperature for low-temperature hot water power generation to 80°C. This eliminates the need for heat pump heating, expanding the application scenarios for direct power generation using low-temperature hot water working fluids below 100°C. It directly utilizes steam to drive the steam turbine, avoiding the cost and safety risks of ORC working fluids and the energy consumption of heat pumps. This solves the industry pain point of petrochemical plants' inability to efficiently generate electricity from waste heat at 80-100°C, achieving key breakthroughs in three dimensions: working fluid safety, heat source adaptability, and economic return on investment.

[0016] A spray system is installed on the condenser to directly receive a large amount of hot water from the flash tank. There are no conventional steam shut-off valves or regulating valves; all flash steam is directly connected to the turbine without obstruction to drive the generator, simplifying the equipment and reducing system construction costs.

[0017] This invention improves thermal efficiency. Under vacuum conditions, the boiling point of water decreases, and hot water rapidly vaporizes upon entering the flash evaporator, increasing the steam output by 3-4 times (compared to atmospheric pressure), thus enhancing thermal efficiency. Especially in high-power scenarios, power generation efficiency is significantly improved, with single-unit power reaching several MW.

[0018] A large refinery can generate 4MWh of electricity through this system, which can create an economic benefit of about 15.2 million yuan per year, significantly improving the company's overall energy utilization efficiency and achieving dual optimization of energy recovery and economic benefits.

[0019] Low-temperature vacuum flash evaporation electricity is significantly cheaper than purchased electricity, with a typical payback period of 2-3 years. It reduces enterprise electricity consumption, and in some regions, surplus electricity can be sold to the grid, generating additional revenue. This reduces fossil fuel consumption and lowers emissions of pollutants such as CO2 and SO2, helping enterprises achieve their "dual carbon" goals. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a system diagram of the present utility model.

[0022] In the diagram: 1. Flash evaporator; 2. Steam turbine; 3. Generator; 4. Condenser; 5. Hot well; 6. Drain expansion tank; 7. Vacuum system; 8. Hot water pump; 9. Condensate pump; 10. Vacuum breaker valve; 11. Control valve; 12. Switch valve. Detailed Implementation

[0023] It should be noted that, where there is no conflict, the embodiments and features in the embodiments of this utility model can be combined with each other. The present utility model will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this utility model or its application or use. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0026] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0027] In the description of this utility model, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this utility model and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this utility model. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0028] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0029] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this utility model.

[0030] like Figure 1 As shown in the figure, this utility model discloses a low-temperature hot water vacuum flash evaporation electrostatic system, including: a flash evaporator, a vacuum system, a steam turbine, a generator, and a condenser. The input end of the flash evaporator 1 is connected to a low-temperature hot water source, and the flash evaporator is also connected to the vacuum system 7. A vapor-liquid separation component is provided inside the flash evaporator. The steam output end of the flash evaporator is connected to the steam turbine 2, and the steam turbine is connected to the generator 3. The inlet end of the condenser 4 is connected to the water output end of the flash evaporator and the water output end of the steam turbine.

[0031] The vapor-liquid separation component used in this utility model can be based on existing technology or implemented using the following technology: Optionally, the vapor-liquid separation component includes multi-layer baffles and a cyclone separator. The multi-layer baffles have a preset acute angle between adjacent baffles. The multi-layer baffles are horizontally installed in the upper middle part of the flash evaporator. A cyclone separator is set below the baffles. The tangential direction of the cyclone separator is connected to the inner wall of the flash evaporator, and the outlet faces upward and is connected to the steam output pipe. Through the dual action of first removing large droplets with baffles and then removing small droplets with cyclones, the steam moisture content is ensured to meet the preset index.

[0032] Furthermore, a flash evaporator spray device is provided on the top of the flash evaporator, and the low-temperature hot water source is connected to the flash evaporator through multiple branch pipes, with the end of each branch pipe connected to the flash evaporator spray device.

[0033] Furthermore, a condenser spray device is installed at the top of the condenser, and the water output end of the flash evaporator is directly connected to the condenser spray device. The condenser is connected to several cooling water pipes. The cooling water pipes and the condenser tube sheet are sealed primarily using the tube expansion method. The condenser is also connected to softened water pipes to prevent calcium and magnesium ions in the condenser from depositing and forming scale on the condenser heat exchange tube walls.

[0034] The flash evaporator spray device and condenser spray device mentioned in this embodiment can be of various optional forms, such as annular spray pipes and rectangular distributed spray pipes. The matching nozzles can be of various optional implementations, such as fan-shaped nozzles and rotating atomizing nozzles. Any device that can achieve uniform distribution of hot water to each nozzle and uniform spraying through the flash evaporator spray device and condenser spray device is acceptable. In some extended embodiments, a check valve is installed between the water output pipe of the flash evaporator 1 and the spray pipe of the condenser to prevent water in the condenser from flowing back into the flash evaporator.

[0035] The condenser used in this embodiment can be existing technology, which is connected to several cooling water pipes. The main water inlet pipe is connected from one side of the bottom of the condenser, and the branch water pipes are arranged along the length of the condenser and connected to the tube sheets at both ends of the heat exchange tubes. In some optional embodiments, the condenser is also connected to a softened water pipe, which is connected from one side of the top of the condenser. The pipe opening is equipped with a filter screen, and the softened water is used to replenish the water lost due to evaporation in the condenser and maintain a stable liquid level.

[0036] Furthermore, a hot well 5 is provided at the bottom of the condenser, and the top of the hot well 5 is connected to the bottom outlet of the condenser 4 through a flange. Several water output pipes are provided at the output end of the hot well, one of which is equipped with a hot water pump 8 and another of which is equipped with a condensate pump 9.

[0037] Furthermore, a condensate expansion tank 6 is installed between the condenser and the hot well 5. Specifically, the top of the condensate expansion tank 6 is connected to the condensate outlet on the bottom side of the condenser 4 via a pipeline, and the bottom is connected to the top of the hot well 5 via a pipeline. Expandably, the condensate expansion tank 6 has a secondary steam outlet on its side, which is connected to the lower middle part of the condenser 4 via a pipeline to realize the recovery and utilization of secondary flash steam and avoid energy waste.

[0038] As an optional implementation, the water output end of the flash evaporator is also connected to the first water outlet pipe of the hot well 5 for subsequent use as low-temperature hot water. A first switch valve 12 is provided on the first water outlet pipe near the hot well side, and a second switch valve is provided on the water output end of the flash evaporator. In addition to being used as low-temperature hot water for subsequent use, it can also be directly transported to the input end of the flash evaporator by the hot water pump 8, and a first control valve 11 is provided on the pipeline. A second control valve is installed on the second outlet pipe of the hot well, which is connected to the downstream low-temperature hot water user end, that is, it is discharged directly without mixing with the water from the flash evaporator. The third outlet pipe of the hot well is connected to the downstream low-temperature hot water user end via condensate pump 9. As an optional implementation, a third control valve is installed on the pipeline between the inlet end of the condenser 4 and the water outlet end of the flash evaporator.

[0039] The aforementioned control valves can be manual valves, solenoid valves, pneumatic valves, etc., and can be adjusted according to the specific factory area.

[0040] Furthermore, the condenser is connected to the vacuum system, and the condenser is connected to a vacuum breaking pipeline. A vacuum breaking valve 10 is installed on the vacuum breaking pipeline. In abnormal or emergency shutdown conditions of the flash evaporator, unit, etc., the vacuum breaking valve is quickly opened to break the vacuum.

[0041] The vacuum system 7 specifically includes a vacuum pump, a vacuum buffer tank, a vacuum sensor, a frequency converter valve, and other devices. The vacuum buffer tank is connected to the non-condensable gas extraction port at the top of the condenser 4 via a pipeline; the bottom of the vacuum buffer tank is connected to the inlet of the water ring vacuum pump via a pipeline; the frequency converter valve is installed on the output pipeline of the vacuum buffer tank to adjust the vacuum level of the flash evaporator 1; and the vacuum sensor is installed at the top of the vacuum buffer tank to monitor the vacuum status in real time.

[0042] Specifically, the condenser is equipped with a multi-parameter interlocking protection unit. This unit is electrically connected to sensors integrated into the system, such as the turbine speed sensor, flash evaporator vacuum sensor, and condenser level sensor. When the speed exceeds the preset standard or the vacuum level fluctuates abnormally beyond the preset standard, the vacuum breaker valve is quickly triggered, further improving system safety. Specifically, the speed sensor is installed near the coupling of the turbine 2 to monitor the speed in real time; the level sensor is installed inside the condenser 4 to monitor the water level within the condenser; all sensors are connected to a PLC controller via signal lines. The PLC controller is electrically connected to the aforementioned vacuum breaker valve 10, vacuum pump, and frequency converter valve to achieve interlocking control. The above technology is existing technology, representing conventional techniques for vacuum systems in the condenser field.

[0043] The specific vacuum flash evaporation electrolysis method of this utility model embodiment includes the following steps: Low-temperature hot water at 80~100℃ is delivered to a flash evaporator for vacuum flash evaporation. A vacuum pump inlet pressure regulating valve is set to adaptively adjust the vacuum level, generating saturated steam under the corresponding temperature and pressure conditions. Optionally, the vacuum level dynamic adaptive adjustment module automatically adjusts the pumping rate of the vacuum system according to the real-time temperature of the hot water to achieve precise vacuum flash evaporation of the low-temperature hot water. Through the internal high-efficiency gas-liquid separation component, the water content is controlled. Under the set temperature and pressure monitoring, the flash steam enters the steam turbine and outputs saturated steam at the set pressure of 81℃ and 50KPa(a). Under the corresponding steam water content, flash steam volume, and pressure, a high-efficiency gas-liquid separator is selected, and the flash evaporation efficiency can reach 99%.

[0044] Flash steam is delivered to the turbine through the outlet of the flash evaporator, and the turbine output is connected to the generator to provide power to the generator. The hot water separated by the flash evaporator is transported to the condenser, and the condensate generated by the steam turbine enters the condenser. The condensate is then transported to the downstream unit through the hot well at the bottom of the condenser.

[0045] This invention uses low-temperature hot water (not exceeding 100℃, e.g., 96℃) under vacuum to flash evaporate the hot water, generating phase-change saturated steam, which serves as the steam source for a steam turbine to drive an asynchronous motor for power generation. Specifically, the steam turbine uses fully vacuum low-temperature hot water for flash evaporation and power generation.

[0046] Under normal operating conditions, as the vacuum level increases, the flashing in the flash evaporator intensifies, the turbine output increases, and the frequency converter will automatically increase its frequency in line with the shaft system. Vacuum pressure transmitters and speed probes are used to monitor the vacuum level and turbine speed in real time. Overspeed protection interlocks are set up to ensure grid connection safety. When the shaft system frequency, phase, voltage and other parameters deviate from the grid to the allowable grid connection range, synchronous grid connection and power generation are achieved. Finally, the 96℃ hot water is cooled to 81℃ for outlet water, realizing the conversion of thermal energy into electrical energy.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A low-temperature hot water vacuum flash evaporation electrostatic system, characterized in that, include: The system comprises a flash evaporator, a vacuum system, a steam turbine, a generator, and a condenser. The input end of the flash evaporator is connected to a low-temperature hot water source, and the flash evaporator is also connected to the vacuum system. The flash evaporator is equipped with a vapor-liquid separation component. The steam output end of the flash evaporator is connected to the steam turbine, and the steam turbine is connected to the generator. The inlet end of the condenser is connected to the water output end of the flash evaporator, and it is equipped with a non-condensable gas extraction outlet connected to the vacuum system.

2. The system according to claim 1, characterized in that, The top of the flash evaporator is equipped with a flash evaporator spray device, and the low-temperature hot water source is connected to the flash evaporator through multiple branch pipes, with the end of each branch pipe connected to the flash evaporator spray device.

3. The system according to claim 1, characterized in that, The top of the condenser is equipped with a condenser spray device, and the water output end of the flash evaporator is directly connected to the condenser spray device.

4. The system according to claim 1, characterized in that, A hot well is provided at the bottom of the condenser, and several water output pipes are provided at the output end of the hot well. A hot water pump is installed on one of the water output pipes, and a condensate pump is installed on another water output pipe.

5. The system according to claim 4, characterized in that, A condensate expansion tank is installed between the condenser and the hot well.

6. The system according to claim 1, characterized in that, The condenser is connected to the vacuum system, and a vacuum breaking pipeline is connected to the condenser, with a vacuum breaking valve installed on the vacuum breaking pipeline.

Images