Hot water power generation system of screw expander

Abstract

The utility model discloses a hot water power generation system of a screw expander, which comprises a hot water exchanger which utilizes smoke to heat water for heat exchange, a water feeding pump of a water feeding device is communicated with a water path of the hot water exchanger through a pipeline, and the hot water exchanger is communicated with a power generation device of the screw expander through a pipeline. A steam exhaust port of the screw expander is connected with a condenser through an exhaust pipeline, the condenser is connected with a vacuum system, a condensed water outlet of the condenser is connected with a condensed water treatment device, and the condensed water treatment device is connected with a water supply system; and the condenser is provided with a spraying device comprising a spraying pump. The utility model can effectively solve the technical problem of low quality of medium and low temperature heat sources due to miniaturization of high temperature heat sources in the prior art, and has excellent working performance.

Description

Technical Field

[0001] The utility model relates to a screw expander hot water power generation system. Background Art

[0002] With the advent of the dual-carbon era, how to maximize the utilization of waste heat, especially low-temperature, unstable, and miniaturized waste heat, waste pressure, and waste gas, and convert it into stable electric energy has become an important task and challenge, and has also been included in China's strategic emerging industries. Because only by converting waste heat into electric energy can it be the ultimate solution to waste heat, reduce energy consumption and electricity prices, and further improve market competitiveness and energy conservation and emission reduction.

[0003] There are many heavy industries in China, especially the heavy industries represented by the steel industry. China is a major steel country. The exhaust gas temperature in the heating furnaces and the tail flue of blast furnaces in the steel industry is too high. For conventional waste heat boilers, the steam parameters are relatively low, and it is impossible to select suitable power generation equipment. Even entering the steam heat network will cause difficulties. It is difficult to collect heat energy and generate steam for utilization, and the operation and maintenance of steam production equipment are complex and require high standards. Similar situations also exist in many industries such as petrochemical industries, resulting in a large amount of heat waste.

[0004] At present, in industry, waste heat boilers plus steam turbines are mostly used for power generation, or ORC power generation. Low-boiling-point working fluids (such as organic working fluids like Freon) are used to generate steam to drive screw expanders or low-temperature turbines for power generation. The above various methods have some inevitable disadvantages, that is, the steam source is required to be a steam medium. Since the steam production equipment for steam (including low-boiling-point working fluid steam) is too complex, the operation and maintenance cost is high, and the requirements are high. Especially with requirements such as earthquake prevention, the steam production equipment is usually placed at a high place, resulting in difficulties in popularization. At the same time, in low-temperature situations, the steam parameters are relatively low, and it is difficult to transport and utilize. Although screw expanders and other prime mover fluid machines are slightly better and more adaptable than steam turbines, their efficiency is not high at low temperature and low pressure, and they cannot adapt to the high and low changes in the heat source temperature and flow rate and unstable operating conditions.

[0005] Regarding miniaturization and low-grade heat sources, it is not ideal, resulting in a very slow promotion speed in industrial waste heat power generation, especially in medium and low-temperature waste heat power generation.

[0006] Therefore, it is necessary to further improve the existing technology to solve the above technical problems. Summary of the Invention

[0007] The purpose of the utility model is to provide a technology that can effectively solve existing problems. A screw expander hot water power generation system for solving the technical problems of miniaturization of high-temperature heat sources and low quality of medium and low-temperature heat sources.

[0008] The technical solution of the utility model is:

[0009] A screw expander hot water power generation system, characterized in that: it includes a hot water exchanger that uses flue gas to heat water for heat exchange. The feed water pump of the water supply device is connected to the water circuit of the hot water exchanger through a pipeline. The hot water exchanger is connected to the screw expander power generation device through a pipeline. The exhaust port of the screw expander is connected to the condenser through an exhaust pipeline. A vacuum system is connected to the condenser. The condensate outlet of the condenser is connected to the condensate treatment device, and the condensate treatment device is connected to the water supply system;

[0010] The condenser is provided with a spraying device.

[0011] The hot water pipeline after the hot water exchanger is connected to a regulating valve and then enters the screw expander, where it undergoes pressure reduction and expansion flashing to do work, and the exhaust is a steam-water mixture.

[0012] The hot water pipeline after the hot water exchanger is connected to a distribution header. The hot water is introduced from the middle of the distribution header. The steam-water mixture outlet at the upper part of the distribution header is connected to the inlet of the screw expander. The steam-water mixture enters the screw expander to do work and generate electricity. The separated water at the lower part of the distribution header is connected to the water supply tank and discharged.

[0013] The condensate treatment device includes a condensate tank connected to the condenser. The condensate tank is connected to the makeup water tank of the water supply system through a condensate pump.

[0014] The water supply system includes a makeup water tank connected to the condensate pump. The makeup water tank is also connected to a makeup water pump that provides soft water makeup; the makeup water tank is connected to the water supply tank through a pre-feed water pump, and the water supply tank is connected to the water channel of the hot water exchanger through an inlet header.

[0015] An outlet header is arranged at the water outlet end of the hot water exchanger. One outlet of the outlet header is connected to the screw expander power generation device through a pipeline. The other outlet of the outlet header is connected to the inlet of the start-stop header. The bottom water outlet of the start-stop header is connected to the water supply tank, and the upper exhaust port of the start-stop header is connected to the condenser.

[0016] The utility model has the following beneficial effects compared with the prior art:

[0017] 1. The utility model provides a screw expander hot water power generation system, which can realize power generation by utilizing waste heat. Water is used as the direct medium to drive the screw expander to generate electricity. Compared with steam or organic working fluids, the requirements are lower, which is conducive to operation and maintenance. The equipment is simpler and runs more reliably. It is especially suitable for miniaturized power generation, such as industrial furnaces. At the same time, since the working fluid is water, the safety of the system is improved and the maintainability is reduced. It promotes a higher reduction in labor costs and unattended operation. The economic and safety benefits are significantly improved.

[0018] 2. Since the present utility model uses water as the direct working medium to utilize industrial waste heat, the transmission of the working medium is more feasible and reliable. Due to the complexity of steam transmission, the length of the pipeline, the treatment of hydrophobicity, and the requirements for the pipeline are relatively high. However, when using water transmission, the requirements are relatively reduced a lot and the distance can be long. This means that the waste heat recovery source and the power generation source can be configured in different places, and multiple heat sources can also be combined for power generation, which is conducive to the transmission and aggregation of multiple heat sources.

[0019] 3. The present utility model solves the problem of the utilization of a large number of industrial heat sources, especially the inability of scattered heat sources to be equipped with power generation facilities. At the same time, since water is used as the medium, its minimum heat absorption temperature range is much larger than that of steam. This is because the lower limit of the heat absorption temperature of steam is restricted by the saturation point temperature, while the limitation of water in this regard is relatively small. Therefore, water as the working medium can absorb more waste heat. Due to the good fluidity of water, it can be transmitted over a long distance. This means that multiple heat sources can be connected in series and in parallel, and the waste heat and residual temperature can be utilized in a gradient manner to maximize heat absorption for power generation, thereby maximizing the power generation efficiency.

[0020] In addition, the present utility model realizes a higher efficiency of recovering medium and low temperature heat sources, and the adjustment operation is more reliable, precise and fast; it allows the hot water temperature, flow rate and process reuse to change efficiently according to the operation requirements; the investment in the medium and low temperature heat source heat collection system is reduced, and the power generation efficiency is higher; compared with systems such as ORC (organic Rankine cycle power generation), the system is simple, has high economy, and does not produce secondary pollution (organic working medium excretion). Brief Description of the Drawings

[0021] The present utility model will be further described below in conjunction with the drawings and embodiments.

[0022] Figure 1 It is a schematic structural diagram of Embodiment 1 of the present utility model.

[0023] Figure 2 It is a schematic structural diagram of Embodiment 2 of the present utility model.

[0024] Figure 3 It is a schematic structural diagram of Embodiment 3 of the present utility model. Detailed Embodiment Embodiment

[0025] A screw expander hot water power generation system includes a hot water exchanger 1 that uses flue gas to heat water for heat exchange. The water pump 2 of the water supply device is connected to the water path of the hot water exchanger through a pipeline. The hot water exchanger is connected to the screw expander power generation device 3 through a pipeline. The exhaust (water) port of the screw expander is connected to the condenser 5 through an exhaust pipeline 4. A vacuum system (including a vacuum pump 6, a pipeline 7, a vent valve 8, etc.) is connected to the condenser. The condensate outlet of the condenser is connected to the condensate treatment device, and the condensate treatment device is connected to the water supply system;

[0026] Water is pressurized by the feed water pump 2 of the water supply device and enters the hot water exchanger. In the hot water exchanger, by absorbing the heat collected by the hot water exchanger, the high-pressure water is heated and becomes high-temperature and high-pressure water; the high-temperature and high-pressure water enters the screw expander to reduce pressure and expand to do work, and the working medium is discharged from the exhaust (water) port of the screw expander. At this time, the working medium becomes a low-temperature and low-pressure steam-water mixture, and through the exhaust pipeline, it enters the condenser; the condenser cools the working medium by exchanging heat with the outside air or water, etc., and becomes condensate; the gas that cannot be condensed is evacuated (gas) through the vacuum system and discharged from the condenser. In the condenser, the working medium releases heat and becomes low-temperature and low-pressure condensate; the condensate is treated by the condensate treatment device and then enters the feed water system, and then the feed water pump sends the water into the heat extraction device to work in sequence.

[0027] The condenser is provided with a spraying device including a spraying pump 10.

[0028] The condensate treatment device includes a condensate tank 11 connected to the condenser. The condensate tank is connected to the make-up water tank 13 of the feed water system through a condensate pump 12.

[0029] The feed water system includes a make-up water tank connected to the condensate pump. The make-up water tank is also connected to a make-up water pump 14 that provides soft water make-up; the make-up water tank is connected to a feed water tank 16 through a pre-feed water pump 15, and the feed water tank is communicated with the water channel of the hot water exchanger through an inlet header.

[0030] When the unit starts up and only needs to dissipate heat without generating electricity, a start-stop header 17 can be set to discharge the flash steam into the condenser. That is, an outlet header is set at the outlet end of the hot water exchanger. One outlet of the outlet header is connected to the screw expander power generation device through a pipeline, and the other outlet of the outlet header is connected to the inlet of the start-stop header. The bottom outlet of the start-stop header is connected to the feed water tank, and the upper exhaust port of the start-stop header is connected to the condenser.

[0031] Furthermore, a distribution header 9 can be further provided. The upper steam-water inlet of the distribution header is connected to one steam-water outlet of the screw expander. The upper wet steam outlet of the distribution header is connected to one wet steam inlet of the screw expander. The bottom drain outlet of the distribution header is connected to the feed water tank. The function of the distribution header is: to separate the steam-water mixture entering the distribution header to generate steam and condensate for subsequent use respectively. Or to flash the high-pressure water entering the header to generate steam and water for subsequent use respectively. Of course, the distribution header can also not be provided. Embodiment

[0032] Such as Figure 2As shown, hot water directly enters the screw expander to reduce pressure and expand for work. After the hot water pipeline is connected to the regulating valve, it enters the screw expander to reduce pressure, expand and flash for work. The exhaust steam is a steam-water mixture. The steam-water mixture is separated to meet the requirements of subsequent processes, or enters the condensation system to be cooled into condensate for recycling. The distribution header is not adopted. The rest is the same as in Embodiment 1. Embodiment

[0033] As Figure 3 shown, the hot water first enters the distribution header 9 to generate wet steam and then enters the screw expander to reduce pressure and do work, achieving the purpose of converting the energy of hot water into electricity. For the hot water power generation method with a distribution header, the hot water is introduced from the middle of the distribution header. The steam-water mixture outlet at the upper part of the distribution header is connected to the inlet of the screw expander. The steam-water mixture enters the screw expander to do work and generate electricity. The separated water at the lower part of the distribution header is connected to the feed water tank and discharged. The rest is the same as in Embodiment 1. Embodiment

[0034] For hot water with a relatively high temperature, the hot water first directly enters the first screw expander to generate electricity, reduce pressure and expand for work. The exhaust steam is introduced into the distribution header to separate the steam-water mixture, and then the steam-water mixture is introduced into the second screw expander to generate electricity and do work. This method will obtain a higher hot water power generation efficiency.

Claims

1. A screw expander hot water power generation system, characterized by: It includes a hot water exchanger that utilizes flue gas to heat water for heat exchange, a water supply pump of a water supply device is connected to the water channel of the hot water exchanger through a pipeline, the hot water exchanger is connected to a screw expander power generation device through a pipeline, the exhaust port of the screw expander is connected to the condenser through an exhaust pipe, the condenser is connected to a vacuum system, the condensate outlet of the condenser is connected to a condensate treatment device, and the condensate treatment device is connected to the water supply system; the condenser is provided with a spray device.

2. A screw expander hot water power generation system according to claim 1, characterized in that: The hot water pipe after the hot water exchanger is connected to the regulating valve and then enters the screw expander, where it reduces pressure, expands, flashes, and performs work, and the exhaust steam is steam and water.

3. A screw expander hot water power generation system according to claim 1, characterized in that: The hot water pipe after the hot water exchanger is connected to the distribution manifold, hot water is introduced from the middle of the distribution manifold, the upper steam-water outlet of the distribution manifold is connected to the inlet of the screw expander, the steam-water enters the screw expander to generate power, and the separated water at the bottom of the distribution manifold is connected to the water supply tank for discharge.

4. A screw expander hot water power generation system according to claim 2, characterized in that: The water supply system includes a water replenishment tank connected to the condensate pump, and the water replenishment tank is also connected to a water replenishment pump that provides soft water replenishment; the water replenishment tank is connected to the water supply tank through a front water supply pump, and the water supply tank is connected to the water channel of the hot water exchanger through a water inlet header.

5. A screw expander hot water power generation system according to claim 4, characterized in that: A water outlet manifold is arranged at the water outlet end of the hot water exchanger, one outlet of the water outlet manifold is connected to the screw expander power generation device through a pipeline, the other outlet of the water outlet manifold is connected to the inlet of the start-stop manifold, the bottom water outlet of the start-stop manifold is connected to the water supply tank, and the upper exhaust port of the start-stop manifold is connected to the condenser.

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