ES2737628T3 - Procedure to compress a steam and steam compressor - Google Patents

Abstract

Procedure for compressing a steam of a medium by means of a rotary vane steam compressor (1), which has a rotor (6) supported such that it can rotate around a drive shaft (10), with at least one vane (14) and at least one compressor chamber (26), which is limited by a housing (2) and at least also by the vane (14), of which there is at least one, waterproofing slip ring seals (43) on the shaft drive (10) the compressor chamber (26), of which there is at least one, in front of the outside atmosphere, characterized in that the medium is used in liquid form as a lubricant, which by means of at least one feed inlet (44) the support is conducted through a gap between the housing (2) and the rotor (6), the sliding ring seals (43) being lubricated by the liquid medium, which is led to the support through the feed inlet (44) , of which there is at least one.

Description

DESCRIPTION

Procedure to compress a steam and steam compressor

The invention relates to a method for compressing a steam of a medium by means of a rotary vane steam compressor, which has a rotor supported such that it can rotate around a drive shaft, with at least one vane and at least one chamber of the compressor, which is limited by means of a housing and at least also by means of the vane, of which there is at least one, waterproofing the sliding chamber seals on the drive shaft of the compressor chamber, of which there is at least one, facing the outside atmosphere The invention further relates to a rotary vane steam compressor for performing such a process.

The main field of application for such a procedure for compressing a steam of a medium and for the steam compressor used for it, is the compression of water vapor. But other means can also be used, for example alcohols or other hydrocarbons. Then the temperature of the saturated steam must be raised, in order to achieve more effective heat recovery and heat recovery, for example for equipment operating according to the principle of the heat pump. However, compressors can also be used to compress gas in general as a compressor or to generate heat. Vapors can be compressed in particular by means of the process and the steam compressor. Under vapors, then all gases that are formed by distilling liquid mixtures in one or more stages, vaporizing, degassing or drying are understood. To compress vapors, among other piston compressors, rotary pistons or Roots blowers, side channel compressors or steam jet compressors are used. The use of axial or radial fans technique is also known. Liquid ring pumps, rotary vane or oil-lubricated vane pumps, rotary piston blowers, diaphragm pumps, lifting plungers or fans are often used to generate the vacuum.

Compressors are known that when compressing air to generate compressed air, they have a water injection, using water to compress, refrigerate and lubricate. Such an installation is known for example from DE 10 2004 053 895 A1. Water is injected into different positions in the compressor chamber and subsequently separated again from compressed gas. When compressing there is no appreciable increase in temperature, so that compressed air under pressure has barely absorbed water.

When compressing gas, the mechanical work contributed to the gas when performing compression causes an increase in temperature. This is problematic, in particular when water vapor is compressed, since the steam overheats during compression and the steam temperature is often well above the saturated steam temperature. Any moisture that is then in a steam compressor is vaporized and is no longer in liquid form, so there is no longer any lubrication of the moving parts of the compressor. The steam is completely dry. But in this state the steam compressor is subjected to immense wear, since the compressor chamber has to be tightly closed at very high temperatures.

A lubrication with for example oils known by the traditional pump technique, for example a hydraulic oil, cannot be used economically reasonably, since that oil could not be separated with an economically reasonable expense of the compressed steam, once it has abandoned the compressor or the compressor chamber.

From EP 1428978 A1 a heat recovery system is known in which, for example, the heat resulting in the incineration of garbage in mechanical work is transformed. In this regard an expander is used, in which the hot steam under pressure is expanded and cooled. The equipment mentioned in the document can also be used in reverse as a compressor, to compress air. Then the compressor vanes are lubricated with water.

The invention therefore has as a basic objective to improve a process for compressing a steam of a medium, as well as a rotary vane steam compressor, such that wear is reduced and such that at the same time the procedure can be carried out at an acceptable cost economically that is the smallest possible.

The invention achieves the objective formulated by a method for compressing a steam of a medium by means of a rotary vane steam compressor, which has a supported rotor such that it can rotate around a drive shaft with at least one vane and at least one chamber. of the compressor, which is limited by a housing and at least also by the vane, of which there is at least one, waterproofing the sliding chamber seals on the drive shaft of the compressor chamber, of which there is at least one, in front of the outside atmosphere, the procedure being characterized in that the medium is used in liquid form as a lubricant, which through at least one feed inlet is conducted in the support by an interstitium between the housing and the rotor, the sliding ring joints being lubricated by means liquid, which is led to support through the feed inlet, of which there is at least one.

This variant of the design of the procedure has a series of advantages over the procedure known from the prior art. Thus, the medium introduced by the interstitium in liquid form serves as a lubricant and at the same time as a waterproofing of the interstitium, whereby the compressor chamber is hermetically sealed for the vapor of the medium and at the same time the friction wear between the moving vane is reduced and the housing. If, for example, water vapor is to be compressed by the process, then water in liquid form is used as a lubricant. This has the additional advantage that the lubricant does not have to be separated from the steam of the medium in expensive procedures, once it has left the steam compressor. Since it is treated with advantage of the same medium, which is only introduced into the compressor in different states of aggregation, a separation is not necessary. If, for example, a part of the water introduced in liquid form is to be vaporized, this part is simply absorbed by the vapor of the medium that is still in the chamber of the steam compressor. The same is valid for other means used. The part of the medium introduced in liquid form that evaporates during compression of the medium vapor is absorbed by the vapor of the subsequently compressed medium and therefore does not have to be separated from it.

In a configuration variant according to the invention, the steam compressor is a rotary vane steam compressor, which has a rotor with at least one vane. The rotor is then supported such that it can rotate around a drive shaft. The vane, of which there is at least one, is then positioned on the rotor such that it is supported on it, so that it, depending on the displacement within its support, protrudes in greater or lesser magnitude from the perimeter outer rotor and is supported by the protruding end of this perimeter on the inner wall of the housing. The housing may be advantageously symmetrical to the rotation about an axis of the housing, for example in the form of a hollow cylinder. The drive shaft on which the rotor is supported such that it can rotate is then advantageously arranged relative to the axis of the housing, but both running in parallel. The vane, of which there is at least one, then moves with its end protruding from the rotor along the inner wall of the housing and with its lateral surfaces running radially along closing plates or flanges of the housing, which limit the housing in axial direction. Strong friction occurs in both areas, in particular when it comes to high rotational speeds of the rotor, so advantageously, in all these positions, respective interstices are also provided. In this gap the medium can be introduced in liquid form, thereby reducing friction as a lubricant.

The rotor drive shaft is advantageously supported on sliding ring seals, which are lubricated by the liquid medium, which is conducted through at least one feed inlet to the support. The slip ring seals waterproof the compressor chamber against the outside atmosphere on the drive shaft. Additionally, other sealing elements may be provided, such as a shaft seal ring, which nevertheless only protect the support of the drive shaft as a safety joint, for example in a leak.

Advantageously, the housing and / or the rotor are constituted such that the liquid medium is in the interstitium under a back pressure that is higher than the pressure of the chamber, under which the vapor of the medium is in the compressor chamber. This can be achieved by means of the corresponding measures to waterproof the gap, which are basically known by the state of the art, such as a profiled in the opposite direction, for example according to the principle of the centrifugal pump, or a waterproofing around the front rotor to the walls of the housing, which for example may be composed of Teflon (PTFE). The back pressure is then advantageous to ensure that the liquid medium introduced does not vaporize immediately, but that it remains at least for a certain time in a liquid form between the housing and the rotor and in particular its configured mobile vane and thus can waterproof and lubricate the interstitium. . The back pressure must then be greater than the pressure in the chamber under which the medium vapor is in the compressor chamber. Preferably, then, the back pressure is greater than the maximum chamber pressure that can be achieved in one turn of the steam compressor. Since the compressor has to compact and compress the steam in the medium, the pressure inside the chamber must be increased. The back pressure is advantageously greater than the maximum pressure that can be achieved in the chamber in this way.

Particularly in rotary vane steam compressors it is advantageous to introduce the liquid medium, when the gap extends at least also in the radial direction, as close as possible to the rotor shaft in the gap. Due to the rotational movement of the rotor and the centrifugal forces that occur due to this, the liquid introduced medium moves radially outward and thus fills all the gap. At the same time the liquid medium is distributed by means of the vane, of which there is at least one, which rotates with the rotor and executes a movement that is at least also radial. In accordance with the invention, the liquid medium introduced is also used to for example lubricate the slip ring seal of the drive shaft, which deals with outward waterproofing. The waterproofing of the drive shaft can also be carried out in this way, for example, in the form of a slip ring shaft seal. Thus, only a lubricating and sealing agent is needed, which can also be joined without problems with the vapor of the medium to be compressed and does not have to be separated from that vapor after leaving the compressor with expensive procedures.

In a preferred embodiment of the process, at least a part of the liquid medium is vaporized when it enters from the gap in the compressor chamber. This is also advantageously also for the part of the liquid medium that enters from an area between the rotor drive shaft and the wall of the housing in the compressor chamber, provided that water is carried in this area in liquid form. The medium vapor must absorb as much liquid as possible. For this, the uniform distribution of the medium on the inner wall of the housing is advantageous. This is especially advantageous when using compressed water vapor and liquid water as a lubricant. Since the liquid medium is advantageously under the increased back pressure, which is greater than the pressure inside the vaporization chamber, a so-called "flash vaporization" occurs, which means an almost immediate vaporization of a relatively large proportion of the liquid medium. Then on the one hand the vaporization power increases and at the same time the superheating of the medium vapor is counteracted. By means of the vaporization of the medium introduced in liquid form, energy is extracted from the medium in the form of steam and with this the temperature drops. When certain process parameters are given in the process, it may happen that the liquid proportion of the complete medium is vaporized as soon as it enters the compressor chamber. In this case it is possible to introduce more quantity of liquid medium into the compressor chamber, for example by spraying or injection, to thereby reduce the steam temperature and counteract steam overheating.

Preferably, a non-vaporized part of the liquid medium that has entered the compressor chamber leaves the compressor chamber through at least one outlet opening, through which the compressed steam also leaves the chamber. An additional hole, which is closed by a valve, can be arranged on the cover surface of the housing. Additional liquid medium can be introduced into the compressor chamber through this hole.

The non-vaporized liquid medium accumulates in particular due to the rotational movement of the rotor in the inner wall of the housing and can thus lubricate the vanes in their contact with the wall of the housing, in particular when it is a compressor of rotary vane steam.

In order to reduce the friction that occurs in this place, a hollow rotating cylinder can advantageously constitute at least a part of the housing. The hollow cylinder then rotates around an axis of the housing, which is an axis of symmetry to the rotation of the housing and thereby also of the hollow cylinder. It advantageously has the same speed of rotation or revolutions as the rotor. This reduces the relative movement between the radially outer end of the vane, of which there is at least one, and the wall of the housing or the housing and thereby also reduces friction. Preferably, this hollow cylinder that rotates on another housing cover ring is supported. Preferably there is an intermediate space between the hollow cylinder and the cover ring in fluid connection with the compressor chamber. In this way, the liquid medium can be reached, which is compressed by providing it to the gap and thus reaches the compressor chamber, at an intermediate space between the hollow cylinder that rotates and the cover ring that surrounds it. There it is advantageously kept under pressure, whereby the hollow rotating cylinder and the surrounding cover ring jointly fulfill a function similar to that of a sliding bearing. In this way, the friction loss that occurs can also be reduced in this area. In addition, in this way the liquid medium leaving the compressor chamber is properly used. In particular, it is no longer necessary in this configuration variant to provide a separate outlet opening in the compressor chamber housing, to get rid of the liquid medium charge. Rather, it enters the intermediate space between the hollow cylinder and the cover ring and is used there properly.

Also in that area between the rotating hollow cylinder and the cover ring an additional inlet for additional liquid medium can be provided. This can be done by means of openings or injection nozzles, through which additional liquid medium can reach this intermediate space. Advantageously, the hollow cylinder that rotates of cavities can be provided in areas where, for example, the radially outer ends of the rotating vane rest on the hollow cylinder. Here, for example, a part of the liquid medium would accumulate, thereby increasing the sealing and lubrication effect to equal total amount of liquid medium inside the compressor chamber.

The invention achieves the objective further formulated by a rotary vane steam compressor to execute a process described herein. According to the invention, the steam compressor is a rotary vane steam compressor, which has a housing and a rotor supported such that it can rotate around a drive shaft, at least one vane being arranged in the rotor, which can move such that it protrudes radially outward from the rotor with respect to an axis of rotation. Advantageously it is formed between the housing and the rotor to which the vane also belongs, of which there is at least one, an interstitium, in which the medium can be introduced in liquid form through the feed inlet.

In a preferred configuration variant, two, three, preferably four vanes in the rotor are arranged. It is also possible to have a larger number of vanes in the rotor. It has been found that it is advantageous that the vane cannot move with respect to the rotor shaft exactly radially towards outside or inward, but between the radial direction with respect to the rotor shafts and the direction of travel of the corresponding vanes an angle that is different from 0 ° is covered. An orientation of the direction of travel in the radial direction is also possible.

Advantageously several vanes are arranged in the rotor. The introduction of the liquid medium into the interstitium is carried out through at least one feed inlet, whereby the liquid medium is preferably introduced also in the support of the drive shaft to lubricate the sliding ring gasket. The medium enters the chamber, after lubricating the slip ring seals, in particular on at least one front side of the compressor chamber and is driven by the movement of the rotor with the vane along that front surface, which for example it is formed by a housing flange, until the gap between the rotor and the housing. A separate feed line is not necessary, for example inside the vane or inside a front surface of the housing.

It has been found that it is advantageous that at least a part of the housing is formed by a hollow cylinder supported such that it can rotate about an axis of the housing, the axis of the housing running parallel to the axis of the rotor and displaced thereon , this one running in particular in the longitudinal axis and of symmetry of the drive shaft.

An exemplary configuration variant of such a rotary vane steam compressor has a hollow cylinder-shaped housing with an inside diameter of the housing of for example 180 mm. The axial length of the housing is for example 200 mm. The rotor is eccentrically disposed within the housing, which has an outside diameter of for example 150 mm. This results in a total chamber volume of 1.56 dm3, with approximately twice this chamber volume being aspirated at each turn of the rotor. If a water vapor compressor with an absolute pressure of for example 0.5 bar is aspirated with such an compressor, this means a compressed mass of 0.96 g per revolution and for 1000 revolutions per minute a compressed mass of 58 kg per hour.

This could theoretically achieve a compressor power of 50 kg per hour, when an absolute vapor pressure of 0.5 bar must be reached in the suction zone.

When the compression power has to achieve a pressure difference of 1 bar, the power to be provided by the compressor can be calculated. The free surface of the vane that provides the compression power, that is, in the position in which the vane has moved in the maximum amplitude out of the rotor, is in this case for example 6000 mm2. The force required for this compression is 600 N, which for a peripheral speed of the blade at 1000 turns per minute of 8.64 m per second, results in a compressor power of 5184 W. In an adiabatic system, This power of the compressor would go completely to the increase in steam temperature. When water vapor is used this causes a temperature rise of 196 ° K.

The amount of water that needs to be vaporized in the compressor chamber to achieve a saturated steam temperature of for example 111 ° C at 1.5 bar absolute at the pressure outlet, is found, for a compression power of for example 50 kg per hour, at approximately 8.3 liters per hour. However, it is only an example variant of the steam compressor as an example. Other dimensions, differences in pressure, inlet pressure and outlet pressure are equally possible. In addition, the use of another medium results in another increase in temperature and other compressor powers.

In the embodiments written here, the liquid medium, in particular water, is therefore led to the gap between the housing and the rotor. The vanes, which are parts of the rotor, are lubricated by the liquid under pressure in this area. Then the vanes are preferably as close as possible to the wall of the housing, in particular to the front walls, which can be supported, for example, by means of elements that provide strength, for example spring elements. In this case, the vanes slide only on the wall of the housing and are lubricated by the liquid medium film on top.

Advantageously, sealing elements are arranged on the front walls of the rotor, which cause a waterproofing of the front surface of the rotor with respect to the housing.

Preferably, sealing elements are mounted on the front surfaces of the hollow cylinder, which can be configured such that it rotates. They are configured, for example, in the form of sealing rings, which advantageously have the same diameter as the hollow cylinder. All these sealing elements are in contact with the corresponding side wall and can be advantageously made of PTFE, whereby they have good sliding properties. In this way the sliding property of the lubricating medium is supported.

Preferably, the joints are provided, for example, with small grooves that run obliquely, that is, they are profiled, such that a pressure of the liquid is reached in the direction of the outer ring of the housing between the hollow rotating cylinder and the outer ring of the housing surrounding the hollow cylinder. The action of this profiling is very similar to that of a centrifugal pump. The Pressure that is thus established causes, among others, that the liquid medium, which acts as a lubricant, be kept under pressure in the intermediate space between the housing ring and the rotating hollow cylinder. The excess lubricant comes out again on the side where the pressure in the compressor chamber is lower. This is the side where the suction opening is located. This results in an intended circulation of the lubricant, which is supported by internal friction between the rotating hollow cylinder and the housing ring.

An exemplary embodiment of the present invention will be described in more detail below with the aid of the attached figures. It shows in

1 shows the schematic representation in cross-section through a steam compressor according to a first exemplary embodiment of the present invention,

Figure 2 shows the schematic representation in longitudinal section through a steam compressor and Figure 3 shows the schematic representation of an equipment for carrying out the process according to another exemplary embodiment of the present invention.

Figure 1 shows a representation of a cross section through a steam compressor 1, which has a housing 2, which in the embodiment shown is partially formed by a hollow cylinder 4 that rotates. Inside the hollow cylinder 4 there is arranged a rotor 6, which is supported such that it can rotate around an axis of the rotor 8. In this regard it has a drive shaft 10, which is driven by a motor not shown.

Outside the hollow cylinder 4 there is a cover ring 12. In the rotor 6, four vanes 14 with a core of the vanes 16, which are supported by a radially outer end 18 in the hollow cylinder 4, are positioned in the exemplary embodiment shown. For this purpose, 4 cavities 20 are arranged in the hollow cylinder, on which the radially outer end 18 of the vanes 16 rests on the hollow cylinder 4. In these cavities 20, lubricant and sealing means can be accumulated and thus increase the effect of tightness and lubrication.

The vanes 14 are supported in respective grooves of the vanes 22, in which they can slide along the groove of the vane 22. It is observed in the exemplary embodiment shown that the grooves of the vanes 22 and the vanes 14 they are not arranged nor can they slide exactly in the radial direction, but between the direction of travel of the vanes 14 in the grooves of the vanes 22 and the radial direction oriented exactly radially outward, there is an angle.

During operation, the rotor 6 rotates around the axis of the rotor 8 and the hollow cylinder 4 around an axis of the housing 24. Then the outer ends 18 of the vanes 14 slide along the cavities 20.

The different vanes 14 limit the compressor chambers 26 in the perimeter direction. The steam compressor 1 has at least one outlet opening 28 and at least one suction opening 30.

Figure 2 shows a representation in longitudinal section through the steam compressor 1. The cover ring 12, the hollow cylinder 4 and the rotor 6 can be seen, which can be rotated by the drive shaft 10. In the axial direction it is limited the housing 2 by two flanges of the housing 32, which are rigidly connected with the cover ring 12. Between the housing flange 32 and the rotor 6 is a seal of the rotor 34, whereby the compressor chamber is waterproofed 26 radially inwards. Radially outwardly, this function assumes a hollow cylinder seal 36, which is positioned between the hollow cylinder 4 supported such that it can rotate and the housing flange 32. At least one inlet opening 38 is located in the cover ring 12. , through which additional liquid medium, in particular water, can be provided to lubricate the hollow cylinder 4.

The drive shaft 10 is supported by a bearing 40 and is waterproofed outwards by means of sealing rings of the shaft 42. By means of feed inlets 44 the medium can be provided in liquid form, which in the vapor state has to be compressed by the installation. In this way, a waterproofing of the drive shaft 10 and of the contact areas between for example the vanes 14 and the housing parts or the hollow cylinder 4 as well as a lubrication of the corresponding friction surfaces is achieved.

It can be seen in Figure 2 that around the drive shaft 10 are arranged slip ring seals 43, which waterproof the compressor chamber 26 against the outside atmosphere. By means of the liquid medium provided through the feed inlet 44, these sliding joint rings 43 are waterproofed and lubricated. Through the leakage openings 45, the water that has entered can be evacuated.

The liquid medium introduced through feed inlets 44, moves due to the rotation of the rotor 6 radially outwardly towards the inner sides of the housing flange and thus lubricates the gap between the housing flange 32 as part of the housing 2 and rotor 6. Radially out on rotor 6 is Find the rotor seal 34, which makes the pressure of the liquid medium in the gap sufficient. The liquid medium is carried further radially outward and thus enters the compressor chamber 26. The part of the liquid medium that does not vaporize in the compressor chamber 26 enters between the hollow cylinder seal 36 and the housing flange 32 in an intermediate space between the hollow cylinder 4 and the cover ring 12. By means of the hollow cylinder seal 36 a sufficient pressure is also established here, which prevents further vaporization of the liquid medium which now acts again as a lubricant.

Figure 3 shows the schematic view of an installation to perform the procedure. The steam compressor 1 with the housing 2 can be seen, steam being introduced into the steam compressor chamber 1 through a steam feed inlet 46, coming from a medium with a relatively small pressure. The drive shaft 10 of the rotor 6 is driven by means of a motor 48. After compression, the compressed steam leaves the steam compressor 1 itself and leaves it to a water separator 52. Exemplary embodiment shown is to compress water vapor, whereby liquid water is used as a means of sealing and lubrication. This is conducted through a water inlet line 54 to the feed inlet 44 and enters the steam compressor 1. By means of a feed valve 56 and a pump 58, the amount of water supplied can be adjusted. In the water separator 52, water vapor is separated from the liquid water, the water vapor being conducted for use and the separated water being taken back to the steam compressor 1.

Water from the water separator 42 is conducted to a storage tank 60, whose filling level is determined by a filling level sensor 62. At the water inlet 54 there is a pressure sensor 64, a conductivity sensor 66 , as well as a regeneration filter 68, with which optimum water quality can be achieved for the installation that follows.

Reference List

1 steam compressor

2 housing

4 hollow cylinder

6 rotor

8 rotor shaft

10 drive shaft

12 cover ring

14 palette

16 paddle core

18 outer end

20 cavity

22 vane groove

24 housing shaft

26 compressor chamber

28 exit opening

30 suction opening

32 housing flange

34 rotor seal

36 hollow cylinder gasket

38 entry opening

40 bearing

42 shaft seal ring

43 slip ring gasket

44 power input

45 leakage opening

46 steam inlet conduction

48 engine

50 steam outlet pipe

52 water separator

54 water inlet conduction

56 feed valve

58 bomb

60 storage tank

62 fill level sensor

64 pressure sensor

66 conductivity sensor

68 regeneration filter

Claims (9)

1. Procedure for compressing a steam of a medium by means of a rotary vane steam compressor (1), which has a rotor (6) supported such that it can rotate around a drive shaft (10), with at least one vane ( 14) and at least one compressor chamber (26), which is limited by a housing (2) and at least also by the vane (14), of which there is at least one, waterproofing slip ring seals (43) in the drive shaft (10) the compressor chamber (26), of which there is at least one, facing the outside atmosphere, characterized in that the medium is used in liquid form as a lubricant, which by means of at least one feed inlet ( 44) is conducted in the support by a gap between the housing (2) and the rotor (6), the sliding ring seals (43) being lubricated by the liquid medium, which is led to the support through the feed inlet ( 44), of which there is at least one. 2. Method according to claim 1, characterized in that the housing (2) and / or the rotor (6) are constituted such that the liquid medium is in the interstitium under a back pressure, which is higher than the pressure of the chamber under which the vapor of the medium is located in the compressor chamber (26). 3. Method according to one of the preceding claims, characterized in that at least a part of the liquid medium is vaporized when it enters from the gap in the compressor chamber (26). 4. Method according to claim 3, characterized in that a non-vaporized part of the liquid medium that has entered the compressor chamber (26) leaves the compressor chamber (26) through at least one outlet opening (28). 5. Method according to one of the preceding claims, characterized in that at least a part of the housing (2) is formed by a hollow cylinder (4) that rotates. 6. Rotary vane steam compressor (1) for performing a method according to one of the preceding claims. 7. Rotary vane steam compressor (1) according to claim 6, characterized in that the vane (14) is supported such that it can move in such a way that the rotor (6) protrudes radially outwardly with respect to an axis of the rotor (8). 8. Rotary vane steam compressor (1) according to claim 7, characterized in that several vanes (14) are arranged in the rotor (6). 9. Rotary vane steam compressor (1) according to claim 7 or 8, characterized in that at least a part of the housing (2) is formed by a hollow cylinder (4) supported such that it can rotate about an axis of the housing (24), running an axis of the housing (24) in parallel and displaced with respect to the rotor shaft (8).