DE2657858A1 - Cooling drying plant for compressed air - has coaxial or stacked heat exchangers with tube within tube elements - Google Patents

Abstract

The cooling drying plant for pressurised gases, esp. for compressed air, has vertical gas and gas heat exchanger and gas and coolant heat exchanger. The gas to be dried is continuously circulated successively through gas and gas heat exchanger and gas and coolant heat exchanger. The dryer operates without pressure vessel or may have only a small pressure vessel. The gas and gas heat exchanger (12) and gas and coolant heat exchanger can be coaxial. These heat exchangers are built up of exchanger elements (59) of tube within tube arrangements. These elements are connected to circular collector chambers (45) of small cross section. The heat exchangers can be stacked so that inner tubes (62) pass without interruption through both exchangers. Several inner tubes (62) can be arranged into an external tube (61).

Description

Device for cold drying under pressure.

standing gas, especially compressed air The invention relates to a Device for cold drying of pressurized gas, in particular compressed air, with a gas / gas heat exchanger and a gas / refrigerant heat exchanger in a substantially vertical arrangement, with the gas to be dried successively the gas / gas heat exchanger, the gas / refrigerant heat exchanger and then again flows through the gas / gas heat exchanger in a continuous cycle.

Such an arrangement is from the applicant's DT-Gbm 73 25 813.6 known. The refrigeration dryer described in this publication has already has many advantages and also works advantageously in the countercurrent process, whereby a significant energy saving is achieved. The gas to be dried, compressed air, in particular, is first transferred from the compressor to a gas / gas heat exchanger introduced, where some of the heat is withdrawn from the introduced gas or compressed air will. The gas then flows from this gas / gas heat exchanger to a gas / refrigerant heat exchanger, where the dew point of the gas to be dried so far is reduced, that the moisture contained therein and also, in part, other impurities to be deposited.

After the moisture has been separated out, the gas is fed into the gas / gas heat exchanger fed back in countercurrent to reheat the now dry gas and thereby at the same time to cool the supplied still moist gas.

Compared to previously known arrangements, kiese stands out known device for cold drying in particular also characterized in that the natural The gradient of the air in its various temperature states is used, whereby a considerable reduction in the otherwise usual pressure loss is achieved. This natural gradient results from the fact that the first introduced into the refrigeration dryer warm air can flow downwards as it cools, which is its natural gradient therefore corresponds because gas compression occurs on cooling. The same The direction of flow is from top to bottom with the gas / refrigerant heat exchanger provided so that here too the gas passes through the heat exchanger l5'n £ s its natural Gradient flows. Conversely, the gas flows through the gas / gas heat exchanger when it is reheated from the bottom up, which is also the natural need of warming up and thus corresponds to gas that is becoming lighter. The downward movement of the still with Contaminants of the loaded gas to be cooled down through the heat exchangers is also advantageous because it not only reduces the moisture but also possibly

Contained dirt as well as oil residues collect below and in a simple Way can be deducted.

However, the known arrangement also has a considerable disadvantage on: The entire arrangement must be housed in a pressure vessel. Depending on the required throughput and the pressure (the gas passed through can do that lead to very considerable values for the so-called printed liter product (printing of the of the gas in the tank in bar multiplied by the tank volume in liters). With increasing pressure liter product But the security requests also increase. So with a pressure liter product of more than 200 Li liter-.ar a decrease is through the Technical Surveillance Association is required. With an over 1000 liter, ar lying The liter product is also a review by the TüV every four Prescribed for years. The production delayed and the cost of manufacturing increased. The regular review is included Charges are prohibited and also requires the entire system to be switched off, what in many cases it can be very lcistio. In addition, despite this, it is mandatory Surveys never completely rule out the risk of a very rough pressure Standing container bursts and closes due to material fatigue or accidents considerable destruction of ilaterial as well as injuries to operating personnel lead] ran.

The object of the invention is to provide a refrigeration dryer of the type mentioned at the beginning Art to create that either works without a pressure vessel or a considerable one has reduced pressure liter product.

According to the invention the object is achieved in that gas / gas heat exchangers and gas / refrigerant heat exchangers are coaxial with one another and consist of exchanger elements are constructed, which have a tube-in-tube structure and in annular collecting spaces end with a small cross-section.

This arrangement makes it possible to do this within the refrigeration dryer drastically reduce the volume taken up by the pressurized gas, so that either with the same throughput the printed liter product is considerably reduced can be, or that with a substantially constant pressure liter product a Increase in throughput becomes possible. In particular the coaxial arrangement makes it possible to save connecting lines and thus that in these connecting lines to eliminate contained volume. In addition, the tube-in-tube construction at already relatively thin walls have considerable compressive strengths are attainable. The arrangement of the annular collecting spaces small cross-section also reduces the volume required and probes a structure that Already with very little material expenditure enables high compressive strengths.

According to an advantageous development of the invention, gas / refrigerant heat exchangers are and gas / gas heat exchangers arranged one above the other in such a way that the inner tubes pass through both exchangers without interruption. This creates connecting lines and connecting cavities saved and the pressure liter product further reduced.

The volume required for a given heat exchanger capacity for the pressurized gas to be treated is reduced in size if there are several inner tubes lie in an outer tube, because this means that there is practically no increase in the pressure standing outer pipe a larger heat transfer surface within this outer pipe is created.

In many cases it is useful to be inside the refrigeration dryer as well Provide separation devices. In this case it is according to still another Embodiment of the invention is advantageous if such a separator is in the form of a pipe is arranged in the center of the heat exchanger. Here, too, is due to the tubular shape Achieves high compressive strength with relatively little material expenditure, In addition, the tube has the advantage over other shaped spaces that a there is a smaller increase in the pressure product per liter.

The total volume of the dryer can be reduced if the two According to yet another embodiment, heat exchangers arranged one inside the other are. While maintaining the tube- and ring construction makes it possible, even the outer dimensions of the dryer to make it very small.

Still another improvement can be achieved if the connection between the individual elements of the dryer, such as annular spaces, separators, filters, Assess input, output, formed by pipelines.

It is particularly favorable if these ring lines also, like the heat exchanger elements, have a round cross-section, because this already a high compressive strength can be achieved with low wall thicknesses. same for for possibly

Existing separators and filters, which are particularly beneficial can be built as small pressure vessels, their volume content as possible is small.

Further details, advantages and possible uses of the invention result from the attached representation of exemplary embodiments as well as from the following description.

1 and 2 show two sectional views of a device for Prior art refrigeration drying of gas; Fig. 3 is a cross-sectional view an embodiment of the device according to the invention for cold drying of gas; Fig. 4 is a sectional view taken along line A-B of Fig. 3; Fig. 5 shows a further embodiment the device according to the invention for cold drying of gas; Fig. 6 is a sectional view along lines it-B of Figure 5; FIG. 7 shows a rotated 45 ° with respect to FIG. 6 Partial sectional view to show the pipe connection between the lower and upper Ring line; 8 shows yet another embodiment of the invention s refrigeration dryer for gas; FIG. 9 is a sectional view taken along line A-B of FIG Fig. 8.

In Fig. 1, a known type of refrigeration dryer 10 is shown.

It comprises a vertically arranged gas / gas heat exchanger 12 and a gas / refrigerant heat exchanger 14 inserted parallel to it. Inside of the gas / gas heat exchanger 1 is a heat exchanger insert 18, the is equipped with cooling coils 24.

The pressurized gas to be treated, for example from a Compressor originating compressed air, the gas / gas heat exchanger 12 via a Inlet 28 is supplied, the compressed air temperature being 350 ° C., for example. From the inlet, the compressed air flows in the cooling coils 24 from top to bottom and cools down in the process.

It exits at 30 (Fig. 1), 30a, 30b (Fig. 2) and passes over Filters 32a and 32h and a space 38 for the inlet of the gas / refrigerant heat exchanger 14th

The gas / refrigerant heat exchanger 14 also contains a heat exchanger insert 36 with cooling coils 46. The flowing into the gas / refrigerant heat exchanger 14, to a temperature of z. B. 20 ° C cooled gas flows through the heat exchanger insert 36 and leaves this at a temperature of + 1.5 ° C.

The lowering of the temperature causes moisture contained in the gas and can be removed by draining 57 and 54. The now dry Gas exits the gas / refrigerant heat exchanger and goes to a filter 52 fed, where possibly not knocked down with the condensation water or from the previous ones Filters, dirt residues and oil particles that are not retained are collected. from this Filter, the cold gas then enters the Cas / gas heat exchanger 12, where it goes up past the cooling coils 24 and out of the outlet 34 is led out. This gas warms up again for use suitable temperature.

The refrigerant supplied via a line 44 flows through the one behind the other arranged cooling coils 46 and exits again via line 50. Both heat exchangers as well as the three filters are housed in a pressure vessel 16 with a Lid 17 can be closed.

Through this pressure vessel, the all components of the refrigeration dryer encloses, results in a pressure vessel with compared to the throughput very high pressure liter product.

Even with relatively low throughputs, Additional measures are required to reduce the hazards associated with pressure vessels are always connected.

These disadvantages are highlighted in the following additional figures illustrated embodiments bypassed. So in Fig. 3 is a first embodiment one above the prior art described above according to the invention improved refrigeration dryer shown in longitudinal section, while FIG Shows cross-section along the line A-B of FIG.

Here, too, there is the device for cold drying of compressed gas as in the prior art from a gas / gas heat exchanger 12 and a gas / refrigerant heat exchanger 14. Both heat exchangers are arranged coaxially one above the other. This arrangement is advantageous according to the invention because it would otherwise require connecting lines and Saininel spaces are omitted and the volume occupied by the compressed gas is reduced will.

The increase in the overall height by arranging the both heat exchangers can be kept within limits that at least in the gas / gas heat exchanger 12 Exchanger elements are used which have particularly good heat transfer properties and therefore only one require low overall height. It is z. B. on the patent application P 26 54 253.0 referenced. According to this application, the exchanger element 59 consists of an outer one Tube 61 and an inner tube 62, which is arranged coaxially therewith and also as a core tube referred to as. Meandering corrugated sheet metal 64 is pushed into the core tube, which is in thermally conductive contact with the inner wall of the core tube 62. By this corrugated sheet metal 64 becomes the heat exchanger surface within the core tube increased by a factor of 10-15, for example. Taking into account that by the influence of the longer heat conduction path leads to a deterioration in heat transfer, which is taken into account by a factor of 0.3-0.7, for example There is still an improvement in the aero-transmission by a factor of what is present Example 3 - 10.5. If previously a Kühischlangen length of z. B. 6 m required that was not the case in a heat exchanger vessel without a zigzag or loop guide more could be accommodated, it becomes through this improvement of the heat transfer possible to shorten the cooling coil length to 2 m or even 60 cm, which makes it is possible, these cooling coils or tubes as shown in Fig. 3, from one upper air inlet collector 45 through the gas / gas heat exchanger 12 and then through the gas / refrigerant heat exchanger 14 to the lower air outlet header 47 respectively. This special shape of the heat exchanger elements does not succeed only a reduction in the overall height to, for example, 2 - 3 m, but the lower Volume content under pressure within the heat exchanger is significantly reduced.

In fact, the depicted compressed air dryer does not contain any actual boiler more, but only pipes and ring lines that are in proportion can be easily constructed with little material expenditure for high pressures can. In addition, it is not only the liter product that is significantly reduced can, but that even in the event of a crack in any of the under pressure standing walls gas can only flow out relatively slowly, because to Breaking point Flowing gas from other cavities flow through relatively long distances must before the break point is reached. A real burst, like one Pressure vessel of the prior art is easily possible, is thereby excluded. In this respect, the cavities that exist within the various pipelines contribute are not, in the true sense of the word, to the liter product of the Ixciltetrockner at. In this respect, the arrangement shown can be completely boiler-free Compressed air dryers are spoken.

Of course, the device shown in Fig. 3 can be an external one Have housing (not shown) and associated mounting devices, however, such a housing would not be under pressure and thus on the one described Do not change the facts. Such a housing would only be used for thermal insulation serve or also to protect against other mechanical or other external influences. The arrangement of an outer housing can also be indicated for optical reasons. In the other figures, too, there may be external housings and other mounting devices are omitted for reasons of simplicity.

By the coaxial arrangement one above the other shown in FIG the two heat exchangers not only achieve that for the two exchangers the same core tubes 62 can be used, whereby, as already stated, corresponding pressurized connection lines and collecting spaces are not required, the construction of the refrigeration dryer is also simplified and cheaper because the otherwise The required pressure-resistant wall and aging facilities are no longer necessary.

An outer tube is located around four core tubes 62 (see FIG. 4) 61, through which in the gas / gas heat exchanger 12 from a central air collector 74 cold air flows from the bottom up into the upper air outlet header 42 to from there via an outlet connection 76 the refrigerant dryer as a dried one ncrmal to leave tempered air. On the other hand, it flows through the lumen into the outer tube 60 in the region of the gas-fit refrigerant heat exchanger 14, a refrigerant which is at is fed to a lower refrigerant collector 65, from there the outer tubes 61 d-flows through t and is collected again at the upper refrigerant collector 80 and withdrawn will.

The pressurized gas to be dried is sent to the refrigeration dryer Supplied via a connection piece 82, it first reaches the upper air inlet header 45, which is in the form of an annular and therefore relatively pressure-resistant hollow Box is shown with a rectangular Ou section. The rectangular cross-section is not the ideal shape for pressure resistance, but results from this construction is a simplified 1 creation and a lighter combination of several superimposed annular spaces. On the bottom surface of the box 45 The core rolls of the four outer tubes 61 provided open out, see FIGS. 3 and 4. The gas resp.

the compressed air flows from the collector 45 into the core tube 62, is through that flowing in the opposite direction through the lumen of the outer tube 61 and likewise pressurized dry and cold gas pre-cooled and then through the im Lumen of the outer tube in the gas / refrigerant heat exchanger flowing, not under Pressurized refrigerant to a temperature close to zero, e.g. B. to 1.50C brought. The air cooled in this way enters together with condensed moisture the lower air outlet airler 47, which has the same shape as the upper one Air inlet header 45. Separates during the entire cooling process Moisture, which is either carried along with the gas in the form of droplets or on the walls of the core tube or on the ones contained in this core tube Meander-shaped sheet metal strips precipitate and slowly run down and in the collector 47 exits, where it is by means of condensate drain devices not shown in detail can be deducted.

The maximally cold air now arrives from the lower air outlet collector 47 and air partly still laden with mist droplets, dirt and oil droplets either directly via a corresponding pipe (not shown) or via further dryer elements, such as cyclone separator 84, calming chamber 88, chimney 92, filter 94, in the annulus 74, from where they pass the gas / gas heat exchanger in countercurrent in the manner already described durchlvluft and over the upper air outlet connector 42 and the outlet nozzle 76 leaves the refrigeration dryer.

The optional additional elements are mainly used to a better separation of carried away oil droplets, water droplets and dirt particles of the treated air to allow. In this connection it is nany to the Patent application P 26 54 253.0 referenced by the applicant. Instead of the in FIG illustrated arrangement of only four outer tubes 61 can of course without significant To increase the volume of the refrigeration dryer, additional tubes are arranged depending on the required nominal power. In this way can be with the same rest of the structure adjust the throughput very precisely to the needs, whereby The external dimensions of the refrigeration dryer do not or, but the manufacturing costs are adapted accordingly.

In Fig. 5 is a further embodiment of the refrigeration dryer according to the invention employed at the gas / gas heat exchanger 112 and gas / refrigerant heat exchanger 114 are arranged coaxially one inside the other. The embodiment shown here corresponds in many parts of the embodiment shown in FIG. To make things easier the overview has corresponding parts with the same reference numbers and prefixed 1 referred to.

By nesting the two heat exchangers, this is possible it to reduce the height of the straight line. The reduction in height, however, requires additional measures to prevent the pre-cooled gas exiting the gas / gas heat exchanger gas to sa @@ eln what happens in an @ additional @ @ storage room 175, then one of these Collecting room @ upwardly leading pipe 177 (see Fig. 6 and 7), which is in the collecting space 173 Opens, the one with the core barrel of the gas / refrigerant heat exchanger 114 in Connection. The pre-cooled gas now flows from this (compared to FIG. 3) Collector 173 located at the upper end of the refrigeration dryer in one of the core tubes of the gas / refrigerant heat exchanger 114 and pours into the lower air intake manifold 1 47, where it is the deepest Temperautr has reached about 1.5 ° C. Separated liquid collects both in collector 175 and in collector 147 and can be withdrawn from here. From the collecting space 147 the gas could now be passed directly into the collecting space 174, to warm up again when ascending through the gas / gas heat exchanger and then exit via the collector 142 and the nozzle 176. Optionally, however also here to improve the water, oil and dirt separation, as already with the one in Fig. 3, in the center of the refrigeration dryer, a cyclone separator 184, a calming room 188, an adjoining chimney 192 and finally again a filter assembly 194 can be provided. In this case the filter would outgoing compressed air, now also cleaned of small oil droplets, as with the embodiment of FIG. 3 in a space 183 lying around the chimney back to collector 174. As a result, however, a relatively large one pressurized space would arise, it is more expedient to order instead the outer tubes of the gas / refrigerant heat exchanger to another tube 199 place, the lumen of which is connected to a collector 181, which in turn is connected to filter 194 has. In addition to the volume reduction, this also results the further advantage that the lumen of the tube 199 through which the still maximally cold Gas flows back down into the collector 174, at the same time for thermal insulation of the gas / refrigerant heat exchanger compared to the adjacent gas / gas heat exchanger 112 serves.

In this embodiment, the refrigerant is supplied from below via the plenum 163 and, after the refrigerant, the core tubes 162 of the gas / refrigerant heat exchanger flowed through and collected in the collecting space 180 has drawn off the upper end of the refrigeration dryer via a corresponding line a0a ..

In Fig. 6 there are again only four outer ears for each Heat exchanger shown. Of course, a smaller or larger one can also be used Number of such exchanger elements can be provided without this Printer liter product changes significantly. It should be noted that because of the connecting line 177 (see FIG. 7) does not cover the entire circumference of each heat exchanger ring can be used for the arrangement of exchanger elements.

8 and 9 is a third embodiment of the invention Device for cold drying of pressurized gas, in particular compressed air, shown.

Here, too, there are gas / gas heat exchangers 212 and gas / refrigerant heat exchangers 214 coaxially interleaved.

Instead of the annular collecting spaces with a rectangular cross-section in this embodiment, however, pipelines are provided, whereby this arrangement becomes even more pressure-resistant. In this way, the compressed gas to be dried is supplied via the nozzle 282 in a manifold 245 passed to which the core tubes 262 of the gas / gas heat exchanger 212 are soldered or welded on. @ Instead of the collecting space 174 there is a collecting pipe 274 is provided to circulate the purified cold air flowing upwards in the countercurrent to introduce the outside tube 261 of the gas / gas heat exchanger, from where, after flowing through the exchanger, it is collected in the collector pipe 242 and the outlet 276 is fed.

Instead of the collecting space 175, there is also a collecting pipe 275 for receiving of the pre-cooled gas provided. arrives via a line 277 leading upwards this precooled gas then into the pipeline corresponding to the collecting space 173 273.

From there, the core tubes of the gas / refrigerant heat exchanger 214 supplied, which in a. lower manifold 247 flow out. @this The lower manifold 247 is marked with one that is also shown here, but not necessarily necessary yklonabscheieer 284 via an ear 248 in connection. The cyclone separator 284 differs from the cyclone separator 184 shown in FIG. 7 in that the lower stand is arched to increase the compressive strength is.

The housing of the cyclone separator can also contain the calming chamber 288 include. In addition, a filter 294 can also be provided here again. In these: In the event of a situation, the calming space 288 is connected to the filter 294 via a pipeline 292 in connection, should never be too large in diameter, including liier to contribute as little as possible to the printed liter product.

The pressurized gas passes over from the filter assembly 294 an additional tube 272 (see Fig. 9 # in the collecting ring 274. From this collecting ring, that with the fusing of the outer tube of the gas / gas heat exchanger 212 in connection stands, the gas is heated to the already mentioned Samnelrinq 242, to be delivered to the consumer via outlet 276. For the coolant supply and filling, no pressure-tight header pipes are provided, as the refrigerant circuit does not have as high a pressure as the compressed air circuit.

Patent claims: L e r s e i t e

Claims (8)

Claims: 1. Device for cold drying under pressure standing gas, in particular compressed air, with a gas / gas heat exchanger and a gas / refrigerant heat exchanger in an essentially vertical arrangement, wherein the gas to be dried successively the gas / gas heat exchanger, the Gas / refrigerant heat exchanger and again the gas / gas heat exchanger in one continuous cycle, characterized in that gas / gas heat exchanger (12; 112; 212) and gas / refrigerant heat exchanger (13; 113; 213) are coaxial with one another and made up of exchanger elements (59) having a tube-in-tube construction have and in annular collecting spaces (45, 42, 74, 47; 173, 145, 142, 174, 147, 175; 273, 245, 242, 274, 247, 275) with a small cross-section. 2. Apparatus according to claim 1, characterized in that the gas / refrigerant heat exchanger (13) and gas / gas heat exchanger (12) are arranged one above the other in such a way that that the inner tubes (62) run through both exchangers without interruption. 3. Apparatus according to claim 1 or 2, characterized in that several inner tubes (62) lie in an outer tube (61). 4. Device according to one of claims 1 to 3, characterized in that that also a separator (84, 88, 92; 184, 188, 192; 284, 288, 292) in tubular form in Center of the heat exchanger (12, 13; 112, 113; 212, 213) is arranged. 5. Apparatus according to claim 1, claim 3 or claim 4, characterized characterized in that the heat exchanger to reduce the dryer volume (112, 113; 212, 213) are arranged one inside the other. 6. Device according to one of claims 1 to 5, characterized in that that the connection between the individual elements of the dryer, such as ring gutters, Separator, filter, inlet, outlet, of pipelines (e.g. 199, 192, 177; 292, 248, 277, 272). 7. Device according to one of claims 1 to 6, characterized in that that the ring lines (245, 273, 242, 274, 275, 247) have a round cross-section. 8. Device according to one of claims 1 to 7, characterized in that that possibly existing separator (286) and filter (294) built as a small pressure vessel whose volume content is as small as possible.