JP2018025346A - Heat recovery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat recovery system capable of recovering heat from a water addition type compressor to heat coolant.SOLUTION: A separator tank 3 is configured to perform gas-liquid phase separation to discharge fluid from a water addition-type compressor 2, and to a gas phase part, a compressed air delivery path 4 is connected, while to a liquid phase part, an added water return path 6 to the compressor 2 is connected. An aftercooler 5 is provided in the compressed air delivery path 4, and is configured to exchange heat between compressed air and coolant to cool the compressed air with the coolant and on the other hands, heat the coolant with the compressed air. A water cooler 7 is provided in the added water return path 6, and is configured to exchange heat between added water and coolant to cool added water with coolant and on the other hand, heat the coolant with the added water. In each of the coolers 5, 7, compression heat is used for heating coolant, thereby enabling heat recovery. Coolant is preferably passed through the aftercooler 5 and the water cooler 7 in this order.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat recovery system capable of recovering compression heat generated by a water addition type compressor.

  Conventionally, as disclosed in FIG. 1 of Patent Document 1 below, a screw-type water-lubricated air compressor (1) in which a pair of rotors (37) are supported by water-lubricated sliding bearings (2) at both ends; The separator (6) for separating the fluid discharged from the compressor (1) (compressed air discharged together with the lubricating water) into air and water, and the water returned from the separator (6) to the rotor of the compressor (1) are cooled. An air compression system is known that includes an air-cooled heat exchanger (10) that performs cooling and an aftercooler (11) that cools compressed air from a separator (6). In this system, a bearing water supply water pipe (23) is branched to a water pipe (22) from the air-cooled heat exchanger (10) to the rotor of the compressor (1), and the branched water is refrigerated. It is supplied to the bearing (2) of the compressor (1) via the heat absorption heat exchanger (33) of the cycle (27) or via the bypass pipe (24).

JP 2010-43589 A (paragraphs [0012]-[0017], FIG. 1)

  In the invention described in Patent Document 1, the compression heat generated in the compressor is discarded to the outside air in the air-cooled heat exchanger (10, 11) and is not recovered. Temporarily, in the heat exchanger, heat exchange between the compressed air (or separated water) from the separator tank (6) and the water flow is performed, and the heat is used to heat the compressed heat. The following issues remain.

  That is, when producing hot water by exchanging heat between compressed air and water, there is a demand for increasing the temperature of the hot water while reducing the temperature of the compressed air. Therefore, it is necessary to efficiently realize the cooling of the compressed air and the heating of the water flow. This is not limited to the case where the heat of compression is recovered and the water is heated (manufacture of warm water), and the same applies to the case where various liquids are heated using the heat of compression.

  Accordingly, the problem to be solved by the present invention is to provide a heat recovery system capable of recovering heat from a water addition type compressor and heating a coolant. Another object of the present invention is to efficiently and reliably cool the compressed air and warm the coolant when recovering heat from the compressor and heating the coolant.

  The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is characterized in that the discharge fluid from the water addition type compressor is separated into water and the compressed air is sent to the gas phase section. Is connected to the separator tank in which the return path of the added water to the compressor is connected to the liquid phase part, and provided in the compressed air delivery path, heat exchange between the compressed air and the coolant, The first heat recovery heat exchanger that heats the coolant while cooling the compressed air and the return path of the added water are provided to cool the added water by exchanging heat between the added water and the coolant. On the other hand, a heat recovery system including a second heat recovery heat exchanger for heating the coolant.

  According to the first aspect of the present invention, in the first heat recovery heat exchanger, the compressed air and the cooling liquid can be heat-exchanged to cool the compressed air with the cooling liquid, while the cooling liquid is added with the compressed air. Can warm. In addition, in the second heat recovery heat exchanger, the added water (feed water from the separator tank to the compressor) and the coolant can be heat-exchanged to cool the added water with the coolant, while the coolant can be cooled with the added water. Can be warmed. In this way, heat can be recovered by using the compression heat of the water addition type compressor for heating the coolant.

  Furthermore, the invention described in claim 2 is characterized in that the coolant is passed through the first heat recovery heat exchanger and the second heat recovery heat exchanger in order and heated. Item 2. The heat recovery system according to Item 1.

  According to the second aspect of the present invention, the coolant can be passed through the first heat recovery heat exchanger and the second heat recovery heat exchanger in order and heated. By passing the coolant first through the first heat recovery heat exchanger, the compressed air can be cooled as desired with a relatively low temperature coolant. Then, the coolant can be further heated by passing the coolant heated thereby through the second heat recovery heat exchanger.

  ADVANTAGE OF THE INVENTION According to this invention, the heat recovery system which can heat-recover from a water addition type compressor and can heat a cooling fluid is realizable. Moreover, when heat is recovered from the compressor and the coolant is heated, cooling of the compressed air and heating of the coolant can be performed efficiently and reliably.

It is the schematic which shows the heat recovery system of one Example of this invention.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing a heat recovery system 1 according to an embodiment of the present invention.

  The heat recovery system 1 of the present embodiment is provided in a water addition type compressor 2, a separator tank 3 that separates the discharged fluid from the compressor 2 into air and water, and a compressed air delivery path 4 from the separator tank 3. The main part is an aftercooler 5 as a first heat recovery heat exchanger and a water cooler 7 as a second heat recovery heat exchanger provided in an added water return path 6 from the separator tank 3 to the compressor 2. Prepare as.

  The compressor 2 is a water addition type air compressor. The type of the compressor 2 is not particularly limited, but is, for example, a screw type or a scroll type. In the water addition type compressor 2, water (typically purified water (pure water) or softened water) is added to an air suction port, and this added water is used for sealing a compression chamber or cooling a compression mechanism. Meanwhile, the air is compressed and discharged. At the time of this discharge, additive water is also discharged together with the compressed air.

  The compressor 2 is driven by the electric motor 8 in the illustrated example, but may be driven by another prime mover. For example, the compressor 2 may be driven by a steam motor (steam engine). Further, the compressor 2 may be on / off controlled or capacity controlled (output adjustment). For example, in the compressor 2, the electric motor 8 is on / off controlled, or the rotation speed of the electric motor 8 is inverter-controlled. Alternatively, in the case of a steam motor, the opening / closing or opening of the steam supply valve to the steam motor is controlled.

  When the compressor 2 is operated, outside air is sucked into the compressor 2 from the suction passage 10 via the air filter 9, and in that case, the details will be described later, but via the added water return passage 6 from the separator tank 3. Water is added at a set flow rate. And the air compressed in the compressor 2 is discharged to the separator tank 3 with additional water. A check valve 12 is provided in the discharge path 11 from the compressor 2 to the separator tank 3.

  The water addition type compressor 2 can also be called a water lubrication type or a water injection type (in other words, these may be included). Here, the compressor 2 has water added to the air suction port, but may include a water supply port in addition to the air suction port, and water may be added to the water supply port.

  The separator tank 3 receives the discharge fluid (compressed air discharged together with the added water) from the compressor 2 and separates the air and water. That is, the discharge fluid from the compressor 2 is divided into compressed air and separated water in the separator tank 3. Accordingly, the separator tank 3 is divided into an upper gas phase portion and a lower liquid phase portion.

  A compressed air delivery path 4 to the compressed air utilization section is connected to the gas phase section of the separator tank 3. The compressed air delivery path 4 is provided with a primary pressure adjusting valve 13 and an after cooler 5 in order from the separator tank 3 side. The primary pressure regulating valve 13 is a valve that keeps the inside of the separator tank 3 at a set pressure or higher during the operation of the compressor 2. Here, the primary pressure regulating valve 13 is a self-acting valve that operates mechanically based on the pressure on the primary side (that is, the separator tank 3 side), but in some cases, the primary pressure is monitored by a sensor, An electric valve controlled based on the detected pressure may be used. In addition, although not shown in the drawings, the gas-phase part of the separator tank 3 may be provided with an exhaust air discharge valve in addition to a safety valve.

  An added water return path 6 to the compressor 2 is connected to the liquid phase portion of the separator tank 3. The added water return path 6 is provided with a water cooler 7, a water filter 14, and an added water valve 15 in order from the separator tank 3 side. During operation of the compressor 2, the stored water in the separator tank 3 can be returned to the compressor 2 through the added water return path 6 by opening the added water valve 15. At that time, the added water can be returned from the separator tank 3 to the compressor 2 by the suction into the compressor 2 by the operation of the compressor 2 and the pressurization in the separator tank 3. Further, the primary pressure regulating valve 13 keeps the separator tank 3 at a set pressure or higher, and the pressure in the compressed air delivery path 4 (and thus the pressure in the separator tank 3) is maintained as desired, as will be described later. Therefore, the additive water can be supplied to the compressor 2 at a set flow rate while the additive water valve 15 functions as an orifice. In addition, when the added water is supplied from the separator tank 3 to the compressor 2, impurities can be removed by the water filter 14.

  The aftercooler 5 as the heat exchanger for first heat recovery exchanges heat without mixing the compressed air and the cooling water, cools the compressed air with the cooling water, and warms the cooling water with the compressed air. Heat recovery can be achieved by using the compression heat of the compressed air for heating the cooling water.

  The water cooler 7 as the second heat recovery heat exchanger exchanges heat without mixing the added water (separated water in the separator tank 3 and the water supplied to the compressor 2) and the cooling water, Is cooled with cooling water, while the cooling water is warmed with added water. Heat recovery can be achieved by using the compression heat of the added water for heating the cooling water.

  In addition, as cooling water of each cooler 5 and 7, soft water or purified water (pure water) etc. other than tap water can be used according to a use. For example, when preheating water supply to a steam boiler using the heat recovery system 1, degassed softened water is used as cooling water.

  In this embodiment, the cooling water is passed through the after cooler 5 and the water cooler 7 in series. At this time, the cooling water is preferably passed through the after cooler 5 and then through the water cooler 7 as in the illustrated example. Specifically, the cooling water from the water supply source is supplied to the after-cooler 5 through the inlet passage 16, passed through the after-cooler 5, and then supplied to the water cooler 7 through the communication path 17. 7, it is sent to a hot water use section (for example, a water supply tank of a steam boiler) via an outlet path 18.

  Although the cooling water may be supplied to the aftercooler 5 and the water cooler 7 by a supply water pressure from a water supply source, in the present embodiment, the cooling water is supplied by a pump (not shown). The pump is provided in the inlet passage 16, but may be provided in the communication passage 17 or the outlet passage 18 in some cases.

  The flow rate of the cooling water to the aftercooler 5 and the water cooler 7 is preferably adjustable. In order to adjust the water flow rate, the rotational speed of the pump may be controlled by an inverter, but in this embodiment, the opening degree of the heat recovery valve 19 is adjusted. The heat recovery valve 19 is provided in the outlet passage 18, but may be provided in the inlet passage 16 or the communication passage 17 depending on circumstances.

  During operation of the compressor 2, by opening the heat recovery valve 19 and operating the pump, the cooling heat can be passed through the aftercooler 5 and the water cooler 7 to recover the compression heat. Then, by adjusting the opening degree of the heat recovery valve 19 during the flow of the cooling water, the flow rate of the cooling water and thus the temperature of the hot water in the outlet passage 18 can be adjusted.

  The heat recovery system 1 further includes a water supply channel 20 and a drainage channel 21. The water supply path 20 is means for replenishing water from a water supply source such as an ion exchange device (for example, a mixed bed type pure water device or a hard water softening device) as additive water. In the present embodiment, the water supply path 20 from the water supply source is connected to the suction path 10 to the compressor 2. The water supply path 20 is provided with a water supply valve 22.

  On the other hand, the drainage channel 21 is connected to the bottom of the separator tank 3. A drainage valve 23 is provided in the drainage channel 21, and drainage from the separator tank 3 can be achieved by opening the drainage valve 23.

  In addition, the separator tank 3 is provided with a water level detector 24. The configuration of the water level detector 24 is not particularly limited. For example, the water level detector 24 is a float type water level detector capable of detecting the water level of purified water / condensed water not containing ions. Further, a pressure sensor 25 is provided in the compressed air delivery path 4 from the separator tank 3 downstream of the primary pressure regulating valve 13. The pressure sensor 25 can monitor the discharge pressure of compressed air (supply pressure to the compressed air utilization unit). Further, a temperature sensor 26 is provided in the outlet path 18 from the water cooler 7. The temperature sensor 26 can monitor the temperature of the hot water after being heated by the after cooler 5 and the water cooler 7.

  Next, operation | movement of the heat recovery system 1 of a present Example is demonstrated. A series of controls described below is basically automatically performed by a controller (not shown). That is, the controller includes the compressor 2 (specifically, the motor 8), the addition water valve 15, the heat recovery valve 19, the water supply valve 22, the drain valve 23, the water level detector 24, the pressure sensor 25, the temperature sensor 26, and the like. The compressor 2 and the valves 15, 19, 22, 23, etc. are controlled based on the detection signals of the sensors 24, 25, 26 and the like.

  First, the flow of air will be described. When the operation of the compressor 2 is started, the compressor 2 sucks air through the air filter 9, compresses it, and discharges it. The compressed air discharged from the compressor 2 is sent from the separator tank 3 to the compressed air utilization section via the aftercooler 5 of the compressed air delivery path 4. However, since the primary pressure adjusting valve 13 is provided in the compressed air delivery path 4, the primary pressure adjusting valve 13 is closed and compressed when the pressure in the separator tank 3 is low as just after the start of operation. Compressed air is not sent to the air utilization unit. When the pressure on the primary side of the primary pressure adjustment valve 13 (that is, the separator tank 3 side) becomes equal to or higher than the set pressure, the primary pressure adjustment valve 13 is opened and compressed air is sent to the compressed air utilization unit.

  During operation of the compressor 2, the compressor 2 is controlled so as to maintain the pressure detected by the pressure sensor 25 at the target pressure. For example, the motor 8 of the compressor 2 is on / off controlled or inverter controlled. Note that the target pressure is higher than the set pressure of the primary pressure regulating valve 13. Therefore, the separator tank 3 is basically maintained at the target pressure thereafter.

  During operation of the compressor 2, by opening the addition water valve 15, water can be added to the suction port of the compressor 2 at a set flow rate. Thereby, sealing, cooling, and lubrication of the compressor 2 can be achieved. Compressed air from the compressor 2 is discharged to the separator tank 3 with added water. Then, air / water separation is achieved in the separator tank 3. The compressed air after separation of the steam and water in the separator tank 3 is sent out from the compressed air delivery path 4. On the other hand, the separated water after the air-water separation in the separator tank 3 can be supplied to the compressor 2 via the added water return path 6 as added water to the compressor 2.

  During operation of the compressor 2 (during the production of compressed air), the pump is operated to pass cooling water through the aftercooler 5 and the water cooler 7. Thereby, in the aftercooler 5, while compressed air and cooling water are heat-exchanged and compressed air can be cooled with cooling water, cooling water can be heated with compressed air. Further, in the water cooler 7, heat can be exchanged between the added water (water supplied from the separator tank 3 to the compressor 2) and the cooling water to cool the added water with the cooling water, while the cooling water can be heated with the added water. . In this way, the cooling water is heated by the aftercooler 5 and the water cooler 7 and sent to the hot water utilization section downstream of the outlet path 18. At this time, if the opening degree of the heat recovery valve 19 is adjusted so that the temperature detected by the temperature sensor 26 is maintained at the set temperature, the hot water having the set temperature can be supplied to the hot water using section.

  During operation of the compressor 2, the water level in the separator tank 3 is maintained at the set water level. For example, when the water level detected by the water level detector 24 exceeds the upper limit water level, the drain valve 23 is opened to lower the water level to a predetermined level. Conversely, when the water level detected by the water level detector 24 falls below the lower limit water level, the water supply valve 22 is opened to raise the water level to a predetermined level. While the water supply valve 22 is opened, makeup water is supplied to the separator tank 3 via the compressor 2. During this time, the addition water valve 15 may be closed.

  As described above, the separator tank 3 is preferably provided with an air release valve (not shown). In that case, when the compressor 2 is stopped, the air release valve is opened. By opening the air release valve even when the compressor 2 is stopped, the reverse rotation of the compressor 2 can be prevented. Thereafter, when the compressor 2 is restarted, the air release valve is closed.

  According to the heat recovery system 1 of the present embodiment, in the aftercooler (first heat recovery heat exchanger) 5 and the water cooler (second heat recovery heat exchanger) 7, the compression heat of the compressor 2 is cooled with cooling water. Heat recovery can be achieved by using for heating. At that time, the cooling water is preferably passed through the after cooler 5 and the water cooler 7 in order. By passing the cooling water through the aftercooler 5 first, the compressed air can be cooled as desired with relatively low-temperature cooling water. Then, the cooling water heated thereby can be passed through the water cooler 7 to further raise the temperature of the cooling water.

  The heat recovery system 1 of the present invention is not limited to the configuration (including control) of the above embodiment, and can be changed as appropriate. In particular, (a) the discharge fluid from the water addition type compressor 2 is separated into air and the compressed air delivery path 4 is connected to the gas phase part, while the added water return path to the compressor 2 is connected to the liquid phase part. 6 is connected to the separator tank 3, (b) provided in the compressed air delivery path 4, and aftercooler 5 for cooling the compressed air with the cooling liquid, (c) provided in the added water return path 6, Other configurations are not particularly limited as long as the water cooler 7 cooled by the coolant is provided.

  For example, in the above-described embodiment, the cooling water is passed through the aftercooler 5 and the water cooler 7 in series. That is, the cooling water may be bifurcated downstream of the inlet path 16, one is passed through the after cooler 5, and the other is passed through the water cooler 7, and then merged and passed through the outlet path 18.

  Moreover, in the said Example, although the opening degree of the heat recovery valve 19 was adjusted based on the detected temperature of the temperature sensor 26 during cooling water flow, the pump was inverter-controlled based on the detected temperature of the temperature sensor 26, and a tapping temperature May be controlled to be constant. Or you may abbreviate | omit implementation of such tapping temperature constant control depending on the case.

  Furthermore, in the said Example, although water was passed through the aftercooler 5 and the water cooler 7, liquids other than water may be passed depending on the case. Even when heat is recovered by each of the coolers 5 and 7 to produce hot water, the following configuration may be used. That is, an antifreeze liquid such as ethylene glycol or water is circulated between the aftercooler 5 (and / or the water cooler 7) and another heat exchanger (hereinafter referred to as a water-heater heat exchanger). While the circulating fluid and compressed air are heat-exchanged by the aftercooler 5, the circulating fluid and water are exchanged in the water heating heat exchanger, and the water is exchanged in the water heating heat exchanger. Warm water may be produced by heating.

1 Heat recovery system 2 Compressor 3 Separator tank 4 Compressed air delivery path 5 After cooler (heat exchanger for first heat recovery)
6 Added water return path 7 Water cooler (second heat recovery heat exchanger)
DESCRIPTION OF SYMBOLS 8 Motor 9 Air filter 10 Suction path 11 Discharge path 12 Check valve 13 Primary pressure adjustment valve 14 Water filter 15 Addition water valve 16 Inlet path 17 Communication path 18 Outlet path 19 Heat recovery valve 20 Water supply path 21 Drainage path 22 Water supply valve 23 Drain valve 24 Water level detector 25 Pressure sensor 26 Temperature sensor

Claims (2)

A separator in which a fluid discharged from a water addition type compressor is separated into a gas and a discharge path for compressed air is connected to the gas phase part, while a return path for added water to the compressor is connected to the liquid phase part A tank,
A heat exchanger for first heat recovery which is provided in the delivery path of the compressed air and heat-exchanges the compressed air and the cooling liquid to cool the compressed air, while heating the cooling liquid;
A heat exchanger for second heat recovery that is provided in a return path of the added water, heat-exchanges the added water and the cooling liquid to cool the added water, and heats the cooling liquid. Heat recovery system. The heat recovery system according to claim 1, wherein the cooling liquid is passed through the first heat recovery heat exchanger and the second heat recovery heat exchanger in order and heated.

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