COOLING ARRANGEMENT AND METHOD FOR COOLING AN AT LEAST TWO-STAGE COMPRESSED AIR GENERATOR

Abstract

The invention relates to a cooling arrangement for an at least two-stage compressed air generator (01). The cooling arrangement comprises an intercooler (04), which is arranged between a first and a second compressor stage (02, 03), an aftercooler (05), which is arranged after the second compressor stage (03), and a subassembly cooler (08), which absorbs heat from further subassemblies of the compressed air generator (01). A coolant circuit comprises a main cooler (07), the cold side of which supplies a cooled coolant having a low temperature parallel to the respective coolant inlet of the intercooler (04), of the aftercooler (05) and of the subassembly cooler (08), and the hot side of which receives the heated coolant having a high temperature exiting in parallel at the respective coolant outlet of the intercooler (04) and of the aftercooler (05). The coolant outlet of the subassembly cooler (08) is connected to a feed inlet (12) of the intercooler (04) and/or of the aftercooler (05). The feed inlet (12) is arranged between the coolant inlet and the coolant outlet, at a point at which the intermediate temperature of the coolant in the intercooler (04) or in the aftercooler (05) corresponds to the exit temperature of the coolant at the subassembly cooler (08) ±20%.

The invention furthermore relates to a method for cooling an at least two-stage compressed air generator.

Claims

1. A cooling arrangement for an at least two-stage compressed air generator (01), comprising a liquid-cooled intercooler (04), which is arranged between a first and a second compressor stage (02, 03), in order to cool the precompressed air discharged from the first compressor stage (02) before it enters the second compressor stage (03); a liquid-cooled aftercooler (05), which is arranged after the second compressor stage (03), in order to cool the air compressed by said second compressor stage (03); a liquid-cooled subassembly cooler (08), which absorbs heat from further subassemblies of the compressed air generator (01); a coolant circuit, which has a main cooler (07), the cold side of which feeds a cooled coolant having a low temperature to the respective coolant inlet of the intercooler (04), of the aftercooler (05) and of the subassembly cooler (08) in parallel, and the hot side of which receives the heated coolant having a high temperature which exits in parallel at the respective coolant outlet of the intercooler (04) and of the aftercooler (05); characterised in that the coolant outlet of the subassembly cooler (08) is connected to a feed inlet (12) of the intercooler (04) and/or the aftercooler (05), wherein the feed inlet (12) is arranged between the coolant inlet and the coolant outlet, at a point at which the intermediate temperature of the coolant in the intercooler (04) or in the aftercooler (05) corresponds to the exit temperature of the coolant at the subassembly cooler (08) ±20%.

2. The cooling arrangement according to claim 1, characterised in that a heat exchanger (09) is interposed in the coolant circuit between the respective coolant outlet of the intercooler (04) and of the aftercooler (05) and the hot side of the main cooler (07).

3. The cooling arrangement according to claim 1 or 2, characterised in that the main cooler (07) is a water-air cooler or 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, characterised in that the main cooler (07) comprises a fan (11).

5. The cooling arrangement according to any one of claims 1 to 4, characterised in that the intercooler (04) and/or the aftercooler (05) have a plurality of feed inlets (12), to which the coolant can be optionally fed from the coolant outlet of the subassembly cooler (08).

6. The cooling arrangement according to claim 5, characterised in that a distributor unit is arranged between the coolant outlet of the subassembly cooler (08) and the feed inlets (12), which distributor unit supplies, in a temperature-controlled manner, that feed inlet (12) at which the intermediate temperature of the coolant in the intercooler (04) or aftercooler (05) is closest to the exit temperature of the coolant at the subassembly cooler (08).

7. The cooling arrangement according to any one of claims 1 to 6, characterised in that at least the intercooler (04), the aftercooler (05), the subassembly cooler (08), the heat exchanger (09), the first and second compressor stages (02, 03) and an electronic control unit are arranged within a common device housing.

8. A method for cooling an at least two-stage compressed air generator (01), comprising the following steps: guiding a cooling medium in a coolant circuit through a main cooler (07) and through a first liquid-cooled intercooler (04) connected in series with the main cooler (07), which intercooler (04) thus cools air precompressed by a first compressor stage (02); guiding the cooling medium in the coolant circuit through an aftercooler (05) likewise connected in series with the main cooler (07) and connected parallel to the intercooler (04), which aftercooler (05) thus cools air post-compressed by a second compressor stage (03); feeding the cooling medium cooled in the main cooler (07) to a liquid-cooled subassembly cooler (08), which absorbs heat from further subassemblies of the compressed air generator (01); characterised in that the heated cooling medium exiting the subassembly cooler (08) is fed via a feed inlet (12) into the intercooler (04) and/or into the aftercooler (05), wherein the feed takes place at a position (12) in the intercooler (04) or in the aftercooler (05) at which the intermediate temperature of the coolant in the intercooler (04) or aftercooler (05) corresponds to the exit temperature of the coolant at the subassembly cooler (08) ±20%.

9. The method according to claim 8, characterised in that the cooling medium heated in the intercooler (04) and in the aftercooler (05) is fed to a heat exchanger (09) for heat recovery before it is returned to the main cooler (07).

10. The method according to claim 8 or 9, characterised in that the heated cooling medium exiting the subassembly cooler (08) is fed via one of a plurality of feed inlets (12) into the intercooler (04) and/or into the aftercooler (05), wherein the feed inlet (12) is selected in such a way that the intermediate temperature of the coolant in the intercooler (04) or aftercooler (05) at said feed inlet (12) corresponds to the exit temperature of the coolant at the subassembly cooler (08).

Description

[0029] Further advantages and details of the invention emerge from the following description of a preferred embodiment with reference to the drawings. In the drawings:

[0030] FIG. 1 shows a block diagram of a cooling arrangement according to the invention with deactivated heat recovery;

[0031] FIG. 2 shows a block diagram of the cooling arrangement with activated heat recovery.

[0032] 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.

[0033] 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.

[0034] 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

[0035] 01 compressed air generator/compressor plant [0036] 02 first compressor stage [0037] 03 second compressor stage [0038] 04 intercooler [0039] 05 aftercooler [0040] 06 - [0041] 07 main cooler [0042] 08 subassembly cooler [0043] 09 heat exchanger [0044] 10 - [0045] 11 fan [0046] 12 feed inlet