Cooling arrangement and method for cooling an at least two-stage compressed air generator

Abstract

A cooling arrangement for an at least two-stage compressed air generator. The cooling arrangement comprises an intercooler arranged between a first and a second compressor stage, an aftercooler arranged after the second compressor stage, and a subassembly cooler, which absorbs heat from further subassemblies of the compressed air generator. A coolant circuit comprises a main cooler, the cold side supplying a cooled coolant parallel to the respective coolant inlet of the intercooler, of the aftercooler and of the subassembly cooler, and the hot side receiving the heated coolant exiting in parallel at the respective coolant outlet of the intercooler and of the aftercooler. The coolant outlet of the subassembly cooler is connected to a feed inlet of the intercooler and/or of the aftercooler.

Claims

1. An at least two-stage compressed air generator, comprising a liquid-cooled intercooler disposed between a first compressor stage and a second compressor stage for cooling precompressed air discharged from the first compressor stage before the precompressed air enters the second compressor stage; a liquid-cooled aftercooler disposed after the second compressor stage for cooling air compressed by the second compressor stage; a liquid-cooled subassembly cooler for absorbing heat from the compressed air generator; a coolant circuit including a main cooler having a cold side and a hot side, the cold side configured to feed a cooled coolant having a low temperature respectively to a coolant inlet of the liquid-cooled intercooler, to a coolant inlet of the liquid-cooled aftercooler, and to a coolant inlet of the subassembly cooler in parallel, and the hot side configured to receive heated coolant having a high temperature which exits in parallel respectively at a coolant outlet of the liquid-cooled intercooler and at a coolant outlet of the liquid-cooled aftercooler, wherein a coolant outlet of the subassembly cooler is connected to at least one of a feed inlet of the liquid-cooled intercooler and a feed inlet of the liquid-cooled aftercooler, wherein the feed inlet of the liquid-cooled intercooler is disposed between the coolant inlet of the liquid-cooled intercooler and the coolant outlet of the liquid-cooled intercooler at a point at which an intermediate temperature of the coolant in the liquid-cooled intercooler is within twenty percent (±20%) of an exit temperature of the coolant at the subassembly cooler, and wherein the feed inlet of the liquid-cooled aftercooler is disposed between the coolant inlet of the liquid-cooled aftercooler and the coolant outlet of the liquid-cooled aftercooler at a point at which an intermediate temperature of the coolant in the liquid-cooled aftercooler is within twenty percent (±20%) of the exit temperature of the coolant at the subassembly cooler.

2. The compressed air generator according to claim 1, wherein a heat exchanger is disposed in the coolant circuit respectively between the coolant outlet of the liquid-cooled intercooler and the hot side of the main cooler, and the coolant outlet of the liquid-cooled aftercooler and the hot side of the main cooler.

3. The compressed air generator according to claim 1, wherein the main cooler is one of a water-air cooler, a water-water cooler, or a combination cooler, which uses water and air optionally as a cooling medium.

4. The cooling arrangement according to claim 3, wherein the main cooler comprises a fan.

5. The compressed air generator according to claim 1, wherein at least one of the liquid-cooled intercooler and the liquid-cooled aftercooler have a plurality of feed inlets, to which the coolant can be optionally fed from the coolant outlet of the subassembly cooler.

6. The compressed air generator according to claim 5, wherein a distributor unit is disposed between the coolant outlet of the subassembly cooler and the feed inlets of the plurality of feed inlets, wherein the distributor unit selectively supplies the plurality of feed inlets.

7. The compressed air generator according to claim 1, wherein at least the liquid-cooled intercooler, the liquid-cooled aftercooler, the subassembly cooler, a heat exchanger, the first compressor stage, the second compressor stage, and an electronic control unit are disposed within a common device housing.

8. A method for cooling an at least two-stage compressed air generator, comprising: guiding a cooling medium in a coolant circuit through a main cooler and through an intercooler, the intercooler connected in series with the main cooler, and the intercooler cooling air precompressed by a first compressor stage; guiding the cooling medium in the coolant circuit through an aftercooler, the coolant circuit through the aftercooler connected in series with the main cooler and the coolant circuit through the aftercooler connected in parallel to the intercooler, wherein the aftercooler cools air compressed by a second compressor stage; feeding the cooling medium cooled in the main cooler to a liquid-cooled subassembly cooler, the subassembly cooler absorbing heat from the compressed air generator; wherein the heated cooling medium exiting the subassembly cooler is fed into at least one of a feed inlet of the intercooler and a feed inlet of the aftercooler, and wherein the feed inlet of the intercooler is at a position in the intercooler at which an intermediate temperature of the coolant in the intercooler is within twenty percent (±20%) of an exit temperature of the coolant at the subassembly cooler, and the feed inlet of the aftercooler is at a position in the aftercooler at which an intermediate temperature of the coolant in the aftercooler is within twenty percent (±20%) of the exit temperature of the coolant at the subassembly cooler.

9. The method according to claim 8, wherein the cooling medium heated in the intercooler and in the aftercooler is fed to a heat exchanger for heat recovery before it is returned to the main cooler.

10. The method according to claim 8, wherein the heated cooling medium exiting the subassembly cooler is selectively fed via one of a plurality of feed inlets into at least one of the intercooler and the aftercooler.

Description

(1) Further advantages and details of the invention emerge from the following description of a preferred embodiment with reference to the drawings. In the drawings:

(2) FIG. 1 shows a block diagram of a cooling arrangement according to the invention with deactivated heat recovery;

(3) FIG. 2 shows a block diagram of the cooling arrangement with activated heat recovery.

(4) FIG. 1 shows the simplified block diagram of a compressed air generator 01 or a compressor plant. The block diagram mainly comprises the essential elements of a cooling arrangement and omits other units of the compressed air generator. The compressed air generator comprises at least a first compressor stage 02 and a second compressor stage 03. The air precompressed in the first compressor stage 01 is supplied at a temperature of, for example, 200° C. to an intercooler 04 for cooling and exits said intercooler 04 at approximately 50° C., in order to then be further compressed by the second compressor stage 03. The finally compressed air exits the second compressor stage 03 at a temperature of approximately 200° C. and is then fed to an aftercooler 05 for renewed cooling, so that the compressed air is finally delivered to external units at approximately 50° C. For the dissipation of heat, a main cooler 07 delivers a cooling medium, preferably cooling water, to its cold side at a temperature of 45° C., for example. The cooling water A is delivered at this low temperature parallel to the inflow of the intercooler 04, the aftercooler 05 and a subassembly cooler 08. The cooling water flows through the intercooler 04 and the aftercooler 05 to absorb the heat of the compressed air and is delivered back to the hot side of the main cooler 07 at a high temperature of 90° C. for example. Prior to this, in the depicted design, the cooling water flows through one more heat exchanger 09, which, however, is deactivated in FIG. 1, so that the cooling water temperature at the inlet and outlet of the heat exchanger 09 is virtually unchanged. The heat is discharged at the main cooler 07, in order to bring the cooling water back to a low temperature. The cooling is assisted, for example, by a fan 11, which discharges a heated exhaust air at a temperature of 40° C., for example.

(5) A special feature of the cooling arrangement is that, after flowing through the subassembly cooler 08, the cooling water is not guided directly to the main cooler 07 or to the upstream heat exchanger 09 parallel to the cooling water of the intercooler and the aftercooler. Instead, the cooling water outlet of the subassembly cooler is connected in each case to a feed inlet 12 at the intercooler 04 and at the aftercooler 05. The feed inlet 12 can alternatively also be provided only at one of the two coolers 04, 05 and its position is selected such that an intermediate temperature of 57° C., for example, prevails there in the cooler 04, 05. The intermediate temperature is to correspond substantially to the outlet temperature of the cooling water B, which is delivered from the subassembly cooler 08. The cooling water B is thus admixed again with the cooling water A in the intercooler 04 and/or in the aftercooler 05 and further heated there to the high temperature.

(6) FIG. 2 shows the simplified block diagram of the compressed air generator 01 or the compressor plant in a modified operating state, specifically with activated heat recovery at the heat exchanger 09. This results in a drop in the temperature of the heated cooling water from 90° C. to 50° C., for example, at the heat exchanger 09. The extracted heat is available for other applications, such as for heating purposes, for example.

LIST OF REFERENCE NUMBERS

(7) 01 compressed air generator/compressor plant 02 first compressor stage 03 second compressor stage 04 intercooler 05 aftercooler 06 - 07 main cooler 08 subassembly cooler 09 heat exchanger 10 - 11 fan 12 feed inlet