JP2011153760A - Two-stage compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a two-stage compressor enabling effective heat recovery from cooling water after compressed gas is cooled. <P>SOLUTION: The two-stage compressor 1 includes: a first compressor 2 and a second compressor 3 compressing gas; and a first cooler 4 and a second cooler 5 cooling gas by heat exchange with cooling fluid. In the two-stage compressor 1, a first fluid passage configuration for introducing gas discharged from the first compressor 2 to the second compressor 3 via the first cooler 4 and supplying gas discharged from the second compressor 3 to a demand destination via the second cooler 5 and a second fluid configuration for introducing gas discharged from the first compressor 2 to the second compressor 3 via the first cooler 4 and second cooler 5 and supplying gas discharged from the second compressor 3 to the demand destination can be selected. The two-stage compressor 1 includes flow rate control means 20, 21 setting a flow rate of cooling fluid supplied to the first cooler 4 and second cooler 5 in the second flow passage configuration smaller than that in the first flow passage configuration. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a two-stage compression apparatus.

  There is a two-stage compressor that compresses gas in two stages by connecting two compressors in series. In the two-stage compression device, for example, as described in Patent Document 1, the discharge gas of the first-stage compressor is cooled by an intercooler (cooler), and then introduced into the second-stage compressor. Generally, the discharge gas of the second stage compressor is cooled by an aftercooler (cooler) and then supplied to the customer.

  Usually, an intercooler and an aftercooler are comprised by the heat exchanger which performs heat exchange between compressed gas and cooling water, and the temperature of cooling water rises by cooling compressed gas. Many two-stage compressor intercoolers and aftercoolers have a reduced heat transfer area for miniaturization and cost reduction, and the difference between the cooling water supply temperature and the discharge temperature is about 5 to 10 ° C. In many cases, the amount of water is set large, that is, the logarithmic average temperature difference in heat exchange is set to a large value.

  In recent years, from the viewpoint of energy saving, it has been proposed to recover heat from cooling water (hot water) whose temperature has increased in a cooler composed of a heat exchanger. In order to increase the efficiency of heat recovery from hot water, it is desirable to make the hot water temperature as high as possible. Therefore, it is preferable from the viewpoint of heat recovery to increase the heat transfer area of the intercooler or the aftercooler so that the compressed gas can be cooled with a small amount of cooling water.

  However, as described above, it is not preferable to increase the heat transfer area of the intercooler or the aftercooler of the two-stage compression device because it increases the size and cost of the device. In particular, in a package-type two-stage compression device in which two compressors, an intercooler and an aftercooler, and other components are housed in one housing, there is a great need for downsizing of the heat exchanger. . For this reason, in the conventional two-stage compression apparatus, it has been difficult to sufficiently recover heat from the hot water discharged from the intercooler or the aftercooler.

Japanese Patent Laid-Open No. 6-2676

  In view of the above problems, the present invention is to provide a two-stage compression device capable of performing effective heat recovery from cooling water after cooling compressed gas while using a small and inexpensive cooler. And

  In order to solve the above problems, a first aspect of a two-stage compressor according to the present invention includes a first compressor and a second compressor that compress a gas, and a first compressor that cools the gas by heat exchange with a cooling fluid. The first cooler and the second cooler, the gas discharged from the first compressor is introduced into the second compressor through the first cooler, and the second compression discharges the gas A first flow path configuration for supplying gas to a customer through the second cooler, and the gas discharged by the first compressor through the first cooler and the second cooler A second flow path configuration that is introduced into the second compressor and that supplies the gas discharged by the second compression to the demand destination can be selected, and the first cooler and the second cooler can be selected. The flow rate of the supplied cooling fluid is less in the second channel configuration than in the first channel configuration. It shall have Kusuru flow rate adjusting means.

  According to this configuration, when the temperature of the discharge gas of the two-stage compressor cannot be increased, for example, when compressed air is supplied to a refrigeration type air dryer that requires the supply air temperature to be a certain temperature or less, What is necessary is just to set it as the 1st flow path structure which uses a 1st cooler as an intercooler and a 2nd cooler as an aftercooler. In addition, when the demand facility allows high-temperature compressed gas, the first cooler and the second cooler are connected in series to form a second flow path configuration that is used as one intercooler. The heat transfer area of the cooler can be increased. Accordingly, the temperature difference between the compressed gas and the cooling fluid in the intercooler is reduced, that is, the temperature of the cooling fluid at the intercooler outlet is increased, so that heat can be easily and efficiently recovered from the cooling fluid.

  In the first aspect of the two-stage compression device of the present invention, the cooling fluid passes in parallel through the first cooler and the second cooler in the first flow path configuration, and the second In the flow path configuration, the first cooler and the second cooler may pass in series.

  According to this configuration, in the second flow path configuration, the compressed gas and the cooling fluid can perform one-pass countercurrent heat exchange through both the first cooler and the second cooler. The return temperature of the cooling fluid can be increased.

  A second aspect of the two-stage compression apparatus according to the present invention includes a first compressor and a second compressor that compress a gas, a first cooler that cools the gas by heat exchange with a cooling fluid, and a second compressor. The gas discharged from the first compressor is introduced into the second compressor via the first cooler, and the gas discharged from the second compression is supplied to the second compressor. A first flow path configuration supplied to a customer through a cooler, and the gas discharged by the first compressor are divided into two, one through the first cooler and the other through the second A second flow path configuration that is introduced into the second compressor via a cooler and supplies the gas discharged by the second compression to the demand destination can be selected, and the first cooler and the The flow rate of the cooling fluid supplied to the second cooler in the second channel configuration is greater than that in the first channel configuration. It shall have a flow rate adjusting means to lessen.

  According to this configuration, when the discharge gas temperature of the two-stage compression device cannot be increased, the first flow path configuration may be used in which the first cooler is used as an intercooler and the second cooler is used as an aftercooler. . Further, when the demand facility allows high-temperature compressed gas, the first cooling device and the second cooling device are connected in parallel to form a second flow path configuration that is used as an intercooler. The flow rate of the compressed gas passing through the condenser and the second cooler can be reduced. Accordingly, the temperature difference between the compressed gas and the cooling fluid in the first cooler and the second cooler is reduced, and the outlet temperature of the first cooler and the second cooler of the cooling fluid is increased, so that the heat from the cooling fluid is increased. Enable recovery.

  As described above, according to the present invention, the second cooler can be used as the aftercooler of the two-stage compression device to reduce the supply temperature of the compressed gas, and the second cooler can be used together with the first cooler. It can also be used as a cooler to increase the heat transfer area of the intercooler. If the heat transfer area of the intercooler is increased, the temperature difference between the compressed gas and the cooling fluid can be reduced, so that the return temperature of the cooling fluid can be increased and heat recovery from the cooling fluid can be facilitated.

It is a block diagram of the two-stage compression apparatus of 1st Embodiment of this invention. It is a figure which shows the 1st flow-path structure of the two-stage compression apparatus of FIG. It is a figure which shows the 2nd flow-path structure of the two-stage compression apparatus of FIG. It is a block diagram of the two-stage compression apparatus of 2nd Embodiment of this invention.

  Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows a configuration of a two-stage compression apparatus 1 according to the first embodiment of the present invention. The two-stage compression apparatus 1 of the present embodiment is an apparatus for sucking air (gas), compressing it into two stages, and supplying the compressed air to a customer (not shown) including an intermediate processing device such as an air dryer. is there.

  The two-stage compressor 1 is a first cooling unit that exchanges heat between the first-stage compressor 2 and the second-stage compressor 3, each of which is a screw compressor, and between compressed air and cooling water (cooling fluid), respectively. And a second cooler 5. The first stage compressor 2 sucks and compresses outside air through the suction filter 6, the suction silencer 7 and the suction adjustment valve 8, and discharges the compressed air through the discharge silencer 9. The compressed air discharged from the first stage compressor 2 is introduced into the first cooler 4.

  The compressed air that has passed through the first cooler 4 is introduced into the second compressor 3 via the first intermediate supply valve 10 or introduced into the second cooler 5 via the second intermediate supply valve 11. The second compressor 3 further compresses the supplied compressed air and discharges it through the discharge silencer 12. The compressed air discharged from the second compressor 3 is introduced into the second cooler 5 through the first high-pressure supply valve 13 or is directly supplied to the customer through the second high-pressure supply valve 14.

  The compressed air that has passed through the first cooler 5 is supplied to the customer through the first discharge valve 15 or introduced into the second stage compressor 3 through the second discharge valve 16.

  The two-stage compressor 1 is supplied with cooling water from a cold water source (not shown) via a water supply line 17, and returns the used cooling water to the cold water source via a circulation line 18. The first cooler 4 is connected to the water supply line 17 via a supply three-way valve 19 and a first adjustment valve (flow rate adjusting means) 20, and returns the passed cooling water directly to the reflux line 18. . The second cooler 5 is connected to the water supply line 17 via a second regulating valve (flow rate adjusting means) 21, and the passing cooling water can be directly returned to the reflux line 18 via the reflux three-way valve 22. Supply to the supply three-way valve 19 is also possible. The supply three-way valve 19 can also be connected to the reflux three-way valve 22 by disconnecting the first cooler 4 from the water supply line 17.

  In FIG. 2, the first intermediate supply valve 10, the second intermediate supply valve 11, the first high-pressure supply valve 13, the second high-pressure supply valve 14, the first discharge valve 15, and the second discharge valve 16 are configured to be selected. The 1st flow-path structure of the two-stage compression apparatus 1 shown is shown. In the figure, the flow path indicated by a broken line is a flow path where the compressed air does not flow because the flow path is closed by the valves 10, 11, 13, 14, 15 and 16. In addition, the flow path of the cooling water determined by the supply three-way valve 19 and the reflux three-way valve 22 in the first flow path configuration is also illustrated.

  In the first flow path configuration, the compressed air discharged from the first compressor 2 is cooled by the first cooler 4 and then introduced into the second compressor 3. The compressed air discharged from the second compressor 3 is cooled by the second cooler 5 and then supplied to the customer. Further, in the first flow path configuration, the cooling water supplied from the water supply line 17 is supplied to the first cooler 4 and the second cooler 5 and returned to the circulation line 18. That is, in the first flow path configuration, the cooling water passes through the first cooler 4 and the second cooler 5 in parallel.

  Subsequently, FIG. 3 shows a second flow path configuration of the two-stage compression apparatus 1. In the second flow path configuration, the compressed air discharged from the first compressor 2 is cooled by the first cooler 4 and then further cooled by the second cooler 5, and then the first compressor 3. be introduced. The compressed air discharged from the second compressor 3 is directly supplied to the customer. In the second flow path configuration, the cooling water supplied from the water supply line 17 passes through the first cooler 4 after passing through the second cooler 5, that is, the second cooler 5 and the first cooling. It passes through the vessel 4 in series and is returned to the reflux line 18.

  The heat balance between the compressed air and the cooling water in the two-stage compressor 1 when the first flow path configuration is adopted will be described. In addition, 32 degreeC cooling water shall be supplied to the two-stage compression apparatus 1 from the feed water line 17. FIG. Further, the ambient temperature air is heated to about 200 ° C. by the change in the polytrope when compressed in the first compressor 2. In order to prevent overheating of the second compressor 5, the first cooler 4 needs to cool the compressed air to about 60 ° C.

Here, the exchange heat quantity between the compressed air and the cooling water is Q, the heat transmissivity of the first cooler 4 is U, the heat transfer area of the first cooler 4 is S, and the logarithmic average of the compressed air and the cooling water If the temperature difference is ΔTm, the following relationship holds:
Q = U · S · ΔTm (1)

  In this embodiment, if the output of the first stage compressor 2 is 100 kW, the exchange heat quantity Q required in the first cooler 4 is also about 100 kW / h. When the first cooler 4 cools the compressed air from about 200 ° C. to about 60 ° C., the heat transfer rate U and the heat transfer area S are set such that the temperature of the cooling water at the outlet of the first cooler 4 is 37 ° C. Have. When the flow rate of the cooling water is calculated from the exchange heat quantity Q and the temperature rise of the cooling water, it is about 17200 kg / h.

  The temperature of the compressed air discharged from the second compressor 3 is also 200 ° C., which is the same as the discharge temperature of the first compressor 2. The second cooler 5 is of the same type as the first cooler 4 and has the same heat transmissibility U and heat transfer area S as the first cooler. When the second regulating valve 21 is adjusted to the same opening as the first regulating valve 19, the flow rate of the cooling water flowing through the second cooler 5 becomes the same as the flow rate of the cooling water in the first cooler 4. At this time, the first cooler 4 and the second cooler 5 are different in only the pressure (volume) of the compressed air and other conditions according to the above formula (1) are the same. The outlet temperature of the cooling water is also the same as that of the first cooler 4. Therefore, the two-stage compression apparatus 1 supplies 60 ° C. compressed air to the customer in the first flow path configuration.

  On the other hand, in the second flow path configuration, the first cooler 4 and the second cooler 5 are connected in series, and the heat transfer area of the first cooler 4 and the second cooler 5 is doubled. It can be regarded as one heat exchanger. Also here, the opening degree of the first regulating valve 20 and the second regulating valve 21 is adjusted so that the temperature of the compressed air introduced into the second compressor 3 becomes 60 ° C., which is the same as that in the first flow path configuration. That is, the exchange heat quantity Q between the compressed air and the cooling water is adjusted to the same value as that of the first flow path configuration. In this case, since the heat transfer area S is doubled compared to the case of the first flow path configuration, the logarithmic average temperature difference ΔTm is half that of the first flow path configuration.

The logarithm average temperature difference ΔTm is ΔT1 which is the temperature difference between the compressed air and the cooling water at the compressed air inlet of the first cooler 4, and ΔT2 is the temperature difference between the compressed air and the cooling water at the compressed air outlet of the second cooler 5. Then, it is expressed by the following formula.
ΔTm = (ΔT1−ΔT2) / ln (ΔT1 / ΔT2) (2)

  Therefore, in the second flow path configuration, when the inlet temperature of the second cooler 5 of the cooling water is 32 ° C., the outlet temperature of the first cooler 4 of the cooling water is about 150 ° C., and the exchange heat quantity Q and The cooling water flow rate calculated from the rising temperature of the cooling water is about 364 kg / h.

  Thus, in this 2nd flow path structure, since the cooling water collect | recovered in the reflux line 18 is a hot water of about 150 degreeC, it can collect | recover heat easily from there. However, in the second flow path configuration, 200 ° C. compressed air discharged from the second compressor 3 is supplied to the customer as it is. Therefore, when the demand destination is a refrigeration air dryer or the like that does not allow high-temperature compressed air, the two-stage compressor 1 needs to be used in the first flow path configuration, and is used in the second flow path configuration. I can't do it.

  Furthermore, in FIG. 4, the 1st flow-path structure of the two-stage compression apparatus 1a of 2nd Embodiment of this invention is shown. With respect to the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  In the two-stage compressor 1a of the present embodiment, in the first flow path configuration, the compressed air discharged by the first compressor 2 is introduced into the second compressor 3 via the first cooler 4, and the second The compressed air discharged from the compressor 3 is introduced into the second cooler 5 through the high pressure supply valve 23, and the compressed air that has passed through the second cooler 5 passes through the first discharge valve 24 to the customer. Supplied.

  Further, in the two-stage compressor 1a, in the second flow path configuration, half of the compressed air discharged by the first compressor 2 is diverted and introduced into the second cooler 5 via the intermediate discharge valve 25, The compressed air that has passed through the second cooler 5 is introduced into the second compressor 3 through the intermediate supply valve 26 together with the compressed air that has passed through the first cooler 4, and the compressed air discharged by the second compressor is high pressure. Supply to the customer through the discharge valve 27.

  In the present embodiment, in both the first flow path configuration and the second flow path configuration, the first cooler 4 and the second cooler are provided with a regulating valve (flow rate adjusting means) 28 from the water supply line 17. A half amount of the cooling water supplied through the first cooling device 4 is introduced, and the cooling water that has passed through the first cooling device 4 and the second cooling device is returned to the reflux line 18.

  In the present embodiment, in the second flow path configuration, the flow rate of the compressed air and the cooling water passing through the first cooler 4 and the second cooler is half that of the first cooler 4 of the first flow path configuration. Become. That is, in the second flow path configuration of the present embodiment, heat exchange with half the exchange heat quantity Q is performed in parallel, so the logarithmic average temperature difference ΔTm in the second flow path configuration can be halved. it can. For this reason, also in this embodiment, the flow rate of the cooling water of the first cooler 4 and the second cooler 5 is set to about 182 kg / h (total 364 kg / h) by adjusting the opening of the regulating valve 28, and the outlet temperature thereof Can be about 150 ° C.

DESCRIPTION OF SYMBOLS 1, 1a ... Two-stage compressor 2 ... 1st compressor 3 ... 2nd compressor 4 ... 1st cooler 5 ... 2nd cooler 10 ... 1st intermediate supply valve 11 ... 2nd intermediate supply valve 13 ... 1st High pressure supply valve 14 ... Second high pressure supply valve 15 ... First discharge valve 16 ... Second discharge valve 19 ... Three-way supply valve 20 ... First adjustment valve (flow rate adjusting means)
21 ... Second adjusting valve (flow rate adjusting means)
DESCRIPTION OF SYMBOLS 22 ... Three-way valve 23 ... High pressure supply valve 24 ... 1st discharge valve 25 ... Intermediate discharge valve 26 ... Intermediate supply valve 27 ... High pressure discharge valve 28 ... Adjustment valve (flow rate adjustment means)

Claims (3)

A first compressor and a second compressor for compressing a gas; and a first cooler and a second cooler for cooling the gas by heat exchange with a cooling fluid;
The gas discharged from the first compressor is introduced into the second compressor through the first cooler, and the gas discharged from the second compression is supplied to the customer through the second cooler. A first flow path configuration for supplying to
The gas discharged from the first compressor is introduced into the second compressor via the first cooler and the second cooler, and the gas discharged from the second compression is supplied to the customer. A second flow path configuration can be selected,
In the second flow path configuration, the flow rate of the cooling fluid supplied to the first cooler and the second cooler is less than that of the first flow path configuration. A compression device.   The cooling fluid passes through the first cooler and the second cooler in parallel in the first flow path configuration, and the first cooler and the second cooling in the second flow path configuration. 2. The compression apparatus according to claim 1, wherein the compressors are passed in series. A first compressor and a second compressor for compressing a gas; and a first cooler and a second cooler for cooling the gas by heat exchange with a cooling fluid;
The gas discharged from the first compressor is introduced into the second compressor through the first cooler, and the gas discharged from the second compression is supplied to the customer through the second cooler. A first flow path configuration for supplying to
The gas discharged from the first compressor is divided into two parts, one is introduced into the second compressor through the first cooler and the other is introduced into the second compressor through the second cooler. Can select the second flow path configuration for supplying the gas discharged by the customer to the demand destination,
In the second flow path configuration, the flow rate of the cooling fluid supplied to the first cooler and the second cooler is less than that of the first flow path configuration. A compression device.

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