DK173569B1 - Diesel-type pressurized internal combustion engine with discharge air separator - Google Patents

Description

in DK 173569 B1

The present invention relates to a diesel-type pressurized internal combustion engine having at least one compressor supplying charging air to the air inlets of the cylinders, and at least one air cooler located in the flow path of the charging air between the compressor and the cylinders air inlet and cooling the charging air prior to delivery to the cylinders. with at least one row of baffles dividing the main air stream of charge air into partial streams, wherein the individual baffle 10, on its one side, has an active baffle extending obliquely to the flow direction of the main air stream, a first channel-shaped dropper with a droplet inlet located at the end of the the active guide surface, and another channel-shaped dropper with a droplet inlet on the other side of the guide plate.

Combustion engines of this type are known from commercial engine building, where for many years the pressure air of the charging air has been used by means of a compressor. In the case of enterprise engines, the term charge air is all-encompassing, but it is to be understood in connection with the invention that in two-stroke engines, the subsequent use of the word charge air covers both flushing and charging air. The pressure setting of the charge air causes a rise in temperature which necessitates cooling of the air before it is supplied to the cylinders of the engine.

Upon cooling, water condenses from the air.

Upon departure from the cooler, the air contains water droplets that should be removed before introducing air into the cylinders, otherwise the droplets could be deposited in the lubricating oil 30 on the inside of the cylinders, with consequent reduction or damage to the lubrication between piston rings and cylinder.

To counteract this, the known water separators are designed with at least two rows of baffles whose 35 active baffles force the air to change flow direction because the air flow hits the baffle and bends to the side. As the air deflects, the water droplets in the air will tend to continue straight out so that the grip of the air in the droplets is broken and the droplets are deposited on the 5 guide surfaces. The air flow will then draw the water to the end of the active baffles where the water enters the duct droplets.

US-A-3,912,471 discloses a moisture separator having a plurality of parallel baffles which change the flow direction of the flowing air several times. The baffles are composed of several plate sections so that troughs are formed at the joints between two sections which alternately project into the air flow on one and the other side of the baffle and serve to collect water droplets from the air.

DE-27 26 524 discloses a liquid separator having a plurality of baffles extending parallel to the zigzag and with projecting liquid collecting troughs spaced apart and alternately projecting into the flow on one 20 and the other side of the baffle. At the downstream end of the baffles, troughs are located at the same location which protrude on both sides of each baffle.

It has been found that the known water separators are not sufficiently efficient, especially not in newer 25 engines where the charge pressure is high and the air volumes are large. Attempts have been made to place a large number of rows of baffles one after the other, but this results in a disadvantageously large pressure drop in the air at the passage of the water separator, which adversely affects the efficiency of the engine.

The present invention aims to provide a pressurized internal combustion engine in which cylinder and piston ring wear due to water deposits from the charge air is reduced, without the pressure drop after the air cooler being excessive.

3 DK 173569 B1

To this end, the engine according to the invention is characterized in that the second dropper is located immediately adjacent to the first, and that the downstream end of the first dropper constitutes the upstream boundary of the droplet inlet in the second dropper.

Each baffle has an active baffle which, as mentioned, extends obliquely to the flow direction of the main air stream and is taken by the airflow on one side (front side) of the baffle and forces the airflow to change direction, and an opposing baffle which in the adjacent airflow of the baffle plate the other side (back side) delineates the channel from the neighboring channel. If one of the partial air streams is viewed, it flows in between two 15 baffles running parallel to one another. When the airflow strikes an active guide surface on one guide plate, it is located opposite the opposite guide surface on the other guide plate. Although the air flow does not strike directly into this portion of the opposing 20 guide surface, which is shadowed by the inflowing air, water can still settle on the surface.

The location of the first and second dropper immediately adjacent one another such that the downstream end of the first dropper constitutes the upstream boundary of the droplet inlet of the second dropper provides the advantage that the second dropper provides a minimal flow resistance. hidden behind the first dropper. It is further preferred that the first drip catcher is located, i.

30, upstream of the second droplet, droplets released at the droplet inlet of the first droplet cannot otherwise be trapped by the second droplet in the same row. Alternatively, it is possible to place the two droplet catchers with a smaller separation, but this gives local changes in the cross-sectional area of the duct, which can cause undesirable turbulence in the air flow.

Water deposited on both sides of the baffle is immediately drained at consecutive locations, which has been found to provide a surprisingly large improvement in the efficiency of the baffle row. By efficiency here is meant the proportion of removed water, ie. a 20% efficiency means removal and drainage of 20% of the amount of condensed water in the inflowing air. The efficiency depends on the air flow rate, ie. of motor load as efficiency decreases with increasing motor load.

For the same operating conditions, it has been found that a series of baffles of traditional design have an efficiency of less than 25%, while a number of baffles 15 of the design according to the invention have an efficiency of 40-50%. This marked improvement has been achieved without a significant increase in the pressure drop across the water separator.

It is not possible to explain exactly why the improvement is achieved, but it may be because the air does not follow a neat laminar course, but swirls so that the water drops are deposited on both channel sides. It is also possible for water droplets to detach from the baffle at the end of the active baffle and fly over and settle on the opposite baffle on the opposite side of the channel where the water is then trapped by the second dropper. It is possibly significant for the effect obtained that the partial air flow, before reaching the droplet inlet of the second droplet, is not subjected to substantially greater directional change than in the action of the active guide surface, since the directional changes are assumed to result in vertebrates which can tear water droplets off. the baffles so that they are carried on with the air.

The ability of the second drip catcher to drain water 35 can be enhanced by rounding the downstream end of the first drip catcher. The rounded downstream end causes water on the guide surface to flow through the drop inlet before the water releases contact with the guide surface.

As an alternative to this design, the 5 downstream boundary of the droplet inlet could protrude a bit into the airflow, so droplets that release that upstream boundary enter the inside of that downstream boundary and run into the droplet trap. It is preferred that the second channel-shaped dropper, and preferably also the first dropper, have an elongated shape with an inner cavity which extends from the droplet inlet in the direction of flow of the charge air over a length at least twice the width of the cavity. Compared to the alternative configuration, where the length and width of the cavity are approximately equal, the elongated drip catcher achieves a greater ability to retain the water until discharged through a drain at the bottom of the drip catcher. Near the drop inlet, there will often be an air whirl inside the cavity. In the cavity, the water tends to be near the bottom of the cavity farthest from the inlet, and the elongated shape of the cavity moves the water away from the air vortex, making the water more difficult to be ejected through the drop inlet. Furthermore, with the elongated shape 25, the drip catcher achieves a suitably large volume, which prevents overflow out through the drip inlet, the drip catcher having more difficulty in running full.

In one embodiment, the droplet inlet of the second dropper is at least one channel width, preferably 30 from 1.5 to four channel widths, downstream of the droplet inlet of the first dropper in the same row of baffles. This distance between the two droplet inlets firstly provides space for giving the droplets a sufficiently large internal volume without restricting the duct cross section too much, and secondly, after passing the droplet inlet to the first droplet, the air will have a certain flow distance to deposit droplets on the opposing channel side.

A manufacturing simplification can be achieved in the design of the water separator in that the first and second dropper catches are located at a duct section extending substantially parallel to the flow direction of the main air flow, the angular bending of the baffles being then the same at both ends of the water separator. active control interface. At the same time, the partial air streams achieve a good flow rate with minimal flow resistance relative to the droplet effect, which is seen, inter alia, that after passing the downstream droplets in the water separator, the flow direction has the same flow direction as the main air flow on the inflow side, so that a directional change is required. If other conditions indicate this, such as if the main air flow is to change direction after the water separator, it may be best to leave the dropper catches 20 located at a duct section extending obliquely in the desired direction.

It is preferred that the baffles in the first row closest to the air cooler upstream of their active baffles have inlet portions extending parallel to one another in the direction of air flow over a length at least twice the distance between neighboring baffles in the row. The inlet portions provide for the division of the main stream and, by virtue of their length, produce a certain alignment of the sub flows for a more laminar flow. This limitation of turbulent flows promotes the separation of suspended water droplets from the air stream as it hits the active guide surface.

The overall efficiency of the water separator can be improved by having at least two, and preferably three, rows of baffles in the water separator and the baffles in the subsequent row being related to the baffles in the previous row. As mentioned above, the first row of baffles in the water separator 5 can have an efficiency of 40-50%, and this is under operating conditions with large flow rates of air. Under the same operating conditions, a further improvement of 20-30% can be achieved with the second row of baffles and an improvement of the efficiency of at least 5-10% with a third row of baffles. Since the pressure loss in the charge air caused by the flow resistance increases approximately the same with each subsequent row, it is not immediately advantageous to use more than three rows of baffles. By linking the baffles in the rows, an improvement in efficiency is obtained, presumably of at least 10%, because turbulence in the partial flow is avoided due to swirl release at the flow past a free end in a row.

The turbulent currents break up the larger droplets into 20 smaller droplets, which are more difficult to catch on the baffles, and they can also tear water droplets away from the baffles.

As mentioned above, it is desirable that the water separator does not cause excessive pressure drop in the charge air.

In a preferred embodiment, the pressure drop is minimized and the efficiency of the water separator is improved by the baffles extending down to a bottom plate which is unbroken in the areas between the baffles and pierced by drainage holes within the duct droplets and that beneath the bottom plate. is a collection chamber with internal dividing walls. Since there is only the possibility of outflow of water and possibly air to the collection chamber from the interior of the dropper catches, the air loss in the expression of the water is relatively limited.

35 The air loss is further minimized by the fact that the collection chamber is divided by dividing walls, which reduces the risk of air from a button so water-filled droplet fan blowing into the collection chamber and disrupting the drainage function. It is preferred that the partition walls 5 lie between the rows of baffles, i.e. down in the collection chamber at the transition between the rows.

Thus, the flow conditions are limited by one row in influencing the conditions of the other rows.

In a preferred further development, the dividing walls have through-holes near the bottom of the collection chamber, and the collection chamber has at least one drain below the last row of baffles in the water separator, but no drains below the preceding row (s). By placing only a drain off the last 15 rows of baffles, the water from the drip catches in the other rows is forced to pass past the dividing walls, and since this can only happen through the through holes near the bottom of the collection chamber where there is only water, the air is large. seen prevented from blowing down through the up-collection chamber at the first row and up into the drip catches in the last row of baffles, which would short-circuit the water separator and tear water up and out the outlet side.

A further limitation of the pressure drop at the water separator can be achieved by the drain being passed pressure-tight through the outer housing in which the water separator is mounted. This prevents the air from blowing out to the engine compartment through an annular gap around the drain. It has been customary in the past to have such a gap to exhaust water which had accumulated in the main line between the air cooler and the water separator, but this causes too much pressure loss in the charging air.

The water separator and cooler may be located one after the other between a compressor 35 turbocharger and a purge air receiver in a two-stroke intersection engine. Typically, a two-stroke cross-head motor has very high power and a correspondingly large air consumption, and it is therefore particularly advantageous to apply the invention to such an engine. The use can be made in the traditional way in which the main air flow after the exit from the cooler flows through a 90 ° duct bend, after which it flows through the water separator. In the duct bending a large part of the droplets are deposited on the duct wall. However, this arrangement is space consuming and 10 may also impose undue restrictions on the design of the air cooler. It is therefore preferred that the water separator is located immediately after the air cooler.

In one embodiment, the upstream ends of the baffles in the water separator are at a distance of 10 mm 15 to 100 mm from the air cooler. This location of the water separator very close to the air cooler gives the advantage that the water droplets that are detached from the air cooler do not reach the same flow rate as the air before they are in the water separator. When the droplets have a high velocity, there is a high risk of splintering and bouncing back into the air as small water droplets that are more difficult to remove. Therefore, there is a significant advantage in placing the water separator with a separation of less than 100 mm from the air cooler. In operation, the air cooler and the water separator are subject to vibration, generated by air pulsations and motor vibrations. Since both the cooler and the water separator contain relatively thin plates, the above distance of 10 30 mm is a lower limit on how close the two elements can be to each other, the distance having to give room for the vibrations. A minimum distance of 30 mm will often be handy to allow for any inaccuracies in mounting. It is preferred that the distance 35 between the air cooler and the water separator is in the range of 40 to 60 mm, which is a suitable compromise between the desire on the one hand to avoid damage to the thin plates in operation and on the other. side to catch the drops while their speed is small.

5 If the downstream boundary of the droplet inlet protrudes too far into the air partial flow between the neighboring plates, the flowing air is affected by excessive flow resistance and an excessively high air vortex can be set up within the second droplet, 10 because too much of the air is conducted. into the dropper.

It is therefore preferred that the downstream boundary of the droplet inlet extends 1-2 mm past a plane extending in the surface of the channel wall upstream of the droplet inlet. This provides suitable good trapping of 15 drops while limiting both flow resistance in the partial flow and air intake in the dropper.

As an air cooler can be used a pipe fin cooler, which may be sectionalized, but it is also possible to do the cooling by spraying water directly into the air in several steps, which is further described in the applicant's EP Patent No. 0 701 655. in such a cooler it is important to make an effective water separation between the individual steps, and it is therefore preferred that the water separator be included in the air cooler at least 25 between two of its cooling stages. There may then be several water separators in connection with the air cooler.

Examples of embodiments of the invention will now be described in more detail with reference to the very schematic drawing, in which FIG. 1 shows a principle sketch of air flows through a turbocharged diesel engine according to the invention, in which the charging air passes a water separator; FIG. 2 shows, on a larger scale, a horizontal section through three neighboring plates in a row in the water separator of FIG. 1, 35 FIG. 3 is a top plan view through the outer housing of an air cooler and water separator in another embodiment of the invention; FIG. 4 is a section along line IV-IV of FIG. 3 in the outer housing, however, the details of air cooler and water separator 5 are omitted, fig. 5 and 6 on a larger scale the water separator of FIG.

3 is a front and side view, respectively; 7 shows on a larger scale a horizontal section through the water separator of FIG. 5, 10 FIG. 8 shows on a larger scale a section of a water drain through the outer housing; and FIG. 9 is a diagram showing efficiencies for the water separator.

In FIG. 1 shows the upper part of a two-stroke, 15-length flushed crosshead engine 1 of the diesel type, which can be a main engine in a ship or a stationary electric power producing engine and can have a nominal power of 2000 kW for the small engines and up to 80,000 kW for the largest engines. The motor can also be a four-stroke 20 motor, which can have a power down to 500 kW.

The motor 1 is pressurized, which can be done by means of a mechanical or electrically driven compressor. In the embodiment shown, the compressor is part of a turbocharger 4, the turbine of which is driven by the exhaust gases, which as shown 25 with arrows run out of a cylinder 2 through the exhaust valve and into an exhaust receiver 3, from which the exhaust gases leave the engine via the turbocharger. The turbocharger's compressor not shown sucks charging air into the engine as indicated by the arrows. The pressurized, warm 30 charge air flows downward and, as shown by arrow 5, rotates to a horizontal flow direction into an air cooler 6 in which the air is cooled, and at the same time water condenses into the air. If the cooler is a pipe fin cooler, a greater proportion of this water will be deposited on the plate-shaped fins and run to the outlet end of the cooler, where the water is returned to the air in the form of larger droplets, which by the air fluctuations. and the vibrations as well as the flowing charge air are detached from the fins. A water separator 7 (Water Mist Catcher) is located 5 immediately after the air cooler. The charging air flows through the water separator and proceeds into a flushing air receiver 8 connected to air chambers around the lower ends of the cylinders. When the piston is near the bottom dead center, rinsing air ports 9 are open so that 10 charge air flows from the air chamber into the cylinder.

In this type of engine, the air inlet of the cylinders is thus made up of the rinsing air ports. If the engine is a four-stroke engine instead, the air inlet is the intake valves.

The water separator 7 contains at least one transverse row of baffles 10 extending from top to bottom of the water separator, possibly interrupted by stiffening horizontal intermediate bottoms. A section with three baffles from a water separator with a single row of baffles is shown in FIG. 2. The flow direction of the main air flow is indicated by arrow A. The water separator housing has a leading edge 11 and each baffle 10 has an inlet portion 12 extending upstream beyond the leading edge. Of course, it is possible to make the water separator without these inlets if 25 are not needed for their contribution to the overall efficiency.

The air part stream A ', which flows in between two neighboring plates, strikes an active guide surface 14 which extends obliquely to the direction A at an angle of about 45 °. At the other end of the baffle 14, the baffles rotate a similar angle back again so that the air sub-flow exits the baffles in a flow direction substantially parallel to the direction A on the inlet side. The active guide surface 14 may extend at 35 angles other than 45 °, such as an angle in the range of 30-60 °, but the former is preferred because it provides a suitably large droplet effect with a suitable small flow resistance.

A first drip catcher 15 is duct-shaped in the height of the water separator and has a drip inlet 16 at the end of the active guide surface in the region where the guide plate returns to its original course.

Another drip catcher 17, also channel-shaped in the height of the water separator, is in immediate extension of drip catcher 15 and has a drip inlet 18 open to the neighbor channel on the other side of the baffle, which may be called the back side, while the opposite side with the active side. guide surface 14 can be called the front.

The inner cavity of the first dropper is oblong in the direction A and in the example shown has a length corresponding to about four times the width. The downstream end 19 of the first dropper is rounded. The second drip catcher has essentially the same configuration as the first drip when the drip inlet is disregarded. If desired, the free plate edge of the droplet inlets can be bent inwardly into the inner cavity thereby preventing overflow, but it is preferable instead to give the droplets sufficiently large internal volume by increasing their lengths which does not appreciably affect the flow resistance upon the passage of air through the baffles. .

The baffles are typically stainless steel thin sheets which are bent in the desired shape and assembled as needed by welding, such as spot welding, brazing or a similar stable assembly method. Another option is to extrude the baffles in the desired shape into an aluminum alloy.

For the sake of simplicity, the following description uses the same reference numerals for details of the same kind as above.

In another embodiment of the motor shown in FIG.

3 and 4, the arrangement of the elements at the air cooler is slightly different from that of FIG. 1. The air cooler 6 and the water separator 7 are at the same height as the purge air receiver, as seen in FIG. 4, and the water separator has three rows of baffles, and not just one row as in FIG. First

The charge air from the compressor flows into the duct bend 20, turns towards and flows into the air cooler 6, and immediately after leaving the downstream end of the air cooler 21, the charging air flows between the inlet portions 12 of the water separator. At the flange portions 22, the water separator is bolted to a partition 23 having a through hole 24 of the same size as the flow area of the water separator. This ensures that the charging air can only pass through the water separator by flowing in between the baffles 10. After the water separator, the air flow turns towards the rinsing air receiver 8 and passes through a series of openings 25 thereto. The rinsing air receiver may further be provided with charging air from electrically operated auxiliary fans (not shown in Figures 3 and 4) mounted next to openings 26 at the end of the receiver.

The water separator is shown in more detail in FIG. 5- 9. There are three rows of baffles 30, 31 and 32, with rows 31 and 32 starting at the downstream end of the second drip catcher 17 in the previous row. The baffles in the rows are continuous to achieve the best efficiency. This has happened with one of the above assembly methods. The active guides are inclined alternately to one side and the other, so that the waste space inside the water separator housing is as small as possible.

The drip catches are terminated downwardly by a bottom plate 35 33 which is unbroken in the areas between the guide plates, so that charging air does not blow downwards through the ducts, but is pierced by one or more drain holes 34 within each drip catcher so that water can flow into a collecting chamber 35 below the base plate. Between each row of 5 baffles, specifically between the last drain hole in one row and the first drain hole 34 in the next row, the collection chamber has dividing walls 36 with through holes 37 near the bottom of the collection chamber. A plurality of drains 38 are mounted at the bottom of the collection chamber 10 under the last row of baffles. The drain is made up of two flange pieces 39, 40 with gaskets clamped together for pressure-tight installation around a hole in a bottom plate 41 in the outer housing. A pipe not shown is connected to the drain and connects this to a drain tank.

When there are multiple drains, the collecting chamber 35 may be divided between adjacent drains by a dividing wall 42 extending substantially perpendicular to the walls 36.

In FIG. Figure 9 shows a diagram of the efficiency of a water separator of the kind mentioned with three rows of interconnecting baffles. There are 48 baffles covering an inflow area with a height of 1200 mm and a width of 930 mm. The efficiency is shown as a function of the amount of water removed, expressed in liters per hour. The efficiency is around 99% at 240 l / h and is seen to remain very high over a large operating range. At 500 l / h, the efficiency is about 94%.

Various modifications can be made to the above embodiments. In particular, when the baffles are made by bending thin sheet, they may have a more angular course than shown in FIG. 2. It is also possible to let the downstream edge of the drop inlet 18, i.e. the end of the free sidewall in the second drop catches a small portion into the inflowing air so that the drop inlet 18 also removes drops not drawn into the inlet at its upstream end. The duct section next to the first and second drip catches need not extend parallel to the direction A, but may be directed at an angle to it. This may be especially true for the last row of baffles 5 if the air is to make a turn immediately after the water separator. This rotation can then be initiated by an appropriate angular position of the channel section.

Claims (13)

1. Diesel-type pressurized internal combustion engine (1) with at least one compressor providing charge air to the air inlets of the cylinders, and at least one air cooler (6) located in the flow path of the charge air between the compressor and the air inlets of the cylinders and cool the charge air prior to delivery to the cylinders; at least one water separator (7) having at least one row of baffles (30, 31, 32) dividing the main air stream of charge air 10 into partial streams, and wherein each baffle has on its one side an active baffle (14) which extends obliquely relative to the flow direction (A) of the main air flow, a first channel-shaped dropper (15) having a droplet inlet (16) located at the end of the active guide surface, and a second channel-shaped dropper (17) with a droplet inlet (18) on the other side of the pilot plate, characterized in that the second dropper (17) is located in the immediate extension of the first and that the downstream end of the first dropper (15) constitutes the 20 upstream of the droplet inlet (18) in the second dropper (17). Pressurized internal combustion engine according to claim 1, characterized in that the downstream end (19) of the first drip catcher (15) is rounded. Pressurized internal combustion engine according to claim 1 or 2, characterized in that the second channel-shaped dropper (17), and preferably also the first dropper (15), has an elongated shape with an internal cavity extending from the droplet inlet into the charging air. flow direction over a length at least twice the width of the cavity. Pressurized internal combustion engine according to one of claims 1-3, characterized in that the drop inlet (18) for the second drop catcher (17) is at least 35 one channel width, preferably from 1.5 to four channel widths, downstream of the drop inlet (16) for the first dropper in the same row of baffles. Pressurized internal combustion engine according to one of claims 1 to 4, characterized in that the first 5 and the second drip catcher (15, 17) are located at a duct section which runs substantially parallel to the flow direction (A) of the main air flow. Pressurized internal combustion engine according to one of claims 1 to 5, characterized in that the baffles (10) in the first row (30) closest to the air cooler upstream of their active baffles (14) have inlet portions (12) mutually parallel to one another. For example, the straight line extends in the direction of flow of air over a length at least twice as long as the distance 15 between neighboring depots in the row. Pressurized internal combustion engine according to one of claims 1-6, characterized in that the baffles extend down to a bottom plate (33) which is unbroken in the areas between the baffles (10) and is pierced 20 by drain holes (34) before in the channel-shaped droplet catches, and that beneath the base plate is a collecting chamber with internal dividing walls (36), preferably between the rows of baffles. Pressurized internal combustion engine according to claim 7, 25, characterized in that the dividing walls (36) have through-holes (37) near the bottom of the collection chamber and that the collection chamber has at least one drain (38) below the last row of baffles in the water separator, but no drains below the preceding 30 rows. Pressurized internal combustion engine according to claim 8, characterized in that the drain (38) is passed pressure-tight through the outer housing in which the water separator is mounted. Pressurized internal combustion engine according to one of the claims 1-9, characterized in that the water separator (7) and the cooler (6) are located one after the other between a compressor turbocharger and a flushing air receiver (8) in a two-stroke cross-head motor. Pressurized internal combustion engine according to one of the preceding claims, characterized in that the upstream ends of the baffles (10) in the water separator are at a distance from 10 mm to 100 mm, preferably from 40 to 60 mm, from the air cooler (6). Pressurized internal combustion engine according to one of the preceding claims, characterized in that the downstream boundary of the droplet inlet (16, 18) extends 1-2 mm past a plane extending in the surface of the duct wall upstream of the droplet inlet. Pressurized internal combustion engine according to one of the preceding claims, characterized in that the water separator is included in the air cooler at least between two of its cooling stages.