The invention relates to a method for compressing a vapor of a medium by means of a rotary vane steam compressor having a rotor rotatably mounted about a drive shaft with at least one slide and at least one compressor chamber which is bounded by a housing and at least by the at least one slide. The invention also relates to a rotary vane steam compressor for carrying out such a method.
The main field of application for such a method for compressing a vapor of a medium and the vapor compressor used therefor is the compression of water vapor. But other media, such as alcohols or other hydrocarbons can be used. In this case, the saturated steam temperature is to be raised, so that a more effective use of heat and heat recovery is achieved, for example, for working on the heat pump principle devices. However, compressors can also be used for general gas compression as a compressor or for heat generation. In particular, vapors can also be compressed by the method and the vapor compressor. By vapors are meant all gases which are produced during one-stage or multistage distillation of liquid mixtures, during evaporation, degassing or during drying. For the compression of vapors, inter alia reciprocating compressors, rotary lobes or Roots blowers, side channel or steam jet compressors are used. The use of axial or radial fan technology is known. For vacuum generation liquid ring pumps, dry or oil lubricated rotary vane pumps, positive displacement blowers, diaphragm pumps, reciprocating pistons or fans are frequently used.
In compressing air to produce compressed air, compressors are known which have a water injection, the water being used for sealing, cooling and lubricating. Such a system is for example from the DE 10 2004 053 895 A1
known. The water is injected at different positions in the compression chamber and later separated again from the compressed gas. When compacting, it does not lead to a significant increase in temperature, so that the compressed compressed air has hardly absorbed water.
During the compression of gas, the mechanical work performed on the gas during compression leads to an increase in temperature. This is particularly problematic when compressing water vapor, since the steam overheats during compression and the temperature of the steam is then often far above the saturated steam temperature. Any moisture that is then in a vapor compressor evaporates and is no longer in liquid form, so that there is no longer any lubrication of the moving parts of the compressor. The steam is completely dry. In this state, however, the steam compressor is exposed to immense wear, since the compressor chamber must be sealed at very high temperatures.
Lubrication with, for example, conventional pump technology known oils, such as hydraulic oil, can not be used in an economically meaningful way, since this oil would not be separable with economically acceptable expense of the compressed steam after he has left the compressor or the compressor chamber.
From the DE 102 17 228 C1
is a vane machine for a vapor or gaseous working medium is known, which manages without liquid lubricant. The respective pressure of the working medium is used to press a sealing ring so that a sufficient sealing effect is achieved. It is assumed that this will reduce the unavoidable friction losses to a minimum.
The DE 29 38 276 A1
describes a vane compressor for Frigen in which compressed natural gas is passed through grooves, whereby bearings are lubricated. A separate lubricant is not provided.
Also in the CH 337605
For example, a machine is described in which the fluid to be conveyed is used as a protective film for lubricating mutually contacting moving parts. Another rotary machine is from the WO 2013/131004 A1
The invention is therefore based on the object to develop a method for compressing a vapor of a medium as well as a rotary vane steam compressor so that the wear is reduced and at the same time the process is economically feasible with economically justifiable expense.
The invention achieves the stated object by a method for compressing a vapor of a medium by means of a rotary vane steam compressor having a rotor rotatably mounted about a drive shaft with at least one slide and at least one compressor chamber through a housing and at least through the at least one Slider is limited, wherein the method is characterized in that the medium is used in liquid form as a lubricant, the is passed through at least one feed in the storage in a gap space between the housing and the rotor.
This embodiment of the method has a number of advantages over the method known from the prior art. Thus, the liquid introduced into the gap in liquid form serves as a lubricant and at the same time as a seal of the gap, so that the compressor chamber for sealing the vapor of the medium sealed and at the same time the wear is reduced by friction between the movable slide and the housing. If steam is to be compressed by the process, for example, water in liquid form is used as the lubricant. This has the further advantage that the lubricant does not have to be separated from the vapor of the medium in complex processes after it has left the vapor compressor. Since it is preferably the same medium, which is introduced only in different physical states in the compressor, a separation is not necessary. For example, should some of the water introduced in liquid form evaporate, that part will simply be taken up by the vapor of the medium, which is already in the compressor chamber of the vapor compressor. The same applies to other media used. The part of the liquid-introduced medium, which evaporates during the compression of the vapor of the medium, is absorbed by the later-compressed vapor of the medium and therefore does not have to be separated from it.
In one embodiment according to the invention, the vapor compressor is a rotary vane vapor compressor which has a rotor with at least one slide. The rotor is rotatably mounted about a drive shaft. The at least one slide is positioned on the rotor so that it is displaceably mounted, so that it protrudes more or less far beyond the outer circumference of the rotor depending on the displacement within its storage and with the projecting beyond this circumference end of the inner wall of the housing is applied. The housing may advantageously be rotationally symmetrical about a housing axis, for example in the form of a hollow cylinder. The drive shaft, about which the rotor is rotatably mounted, is advantageously arranged displaced relative to the housing axis, but both extend in parallel. The at least one slide thereby moves with its protruding from the rotor end along the inner wall of the housing and with its radially extending side surfaces along end plates or housing flanges that define the housing in the axial direction. In both areas, especially at high rotational speeds and rotational speeds of the rotor, strong friction occurs, so that advantageously there is also a gap space at all of these positions. In this gap, the medium can be introduced in liquid form, so that it reduces the friction as a lubricant.
The drive shaft of the rotor is advantageously mounted on mechanical seals, which are lubricated by the liquid medium, which is passed over the at least one feed into the storage. The mechanical seals seal the compressor chamber against the external atmosphere at the drive axle. In addition, other sealing elements, such as a shaft seal, may be provided, but only as a safety seal, for example, in case of leakage, protect the bearing of the drive shaft.
Advantageously, the housing and / or the rotor are designed such that the liquid medium in the gap space is under a back pressure which is greater than a chamber pressure, under which the vapor of the medium is in the compression chamber. This can be achieved by appropriate sealing measures of the gap, which are known in principle from the prior art, such as an opposing profiling, for example, the centrifugal pump principle, or a circumferential seal of the rotor against the walls of the housing, for example made of Teflon (PTFE) can exist. The back pressure is advantageous in order to achieve that the introduced liquid medium does not evaporate immediately, but at least for a certain time exists in liquid form between the housing and the rotor and in particular its movably designed slide and so can seal and lubricate the gap. The back pressure must be greater than the chamber pressure below which the vapor of the medium is in the compression chamber. Preferably, the backpressure is greater than the maximum chamber pressure that can be achieved during a circulation of the vapor compressor. Since the compressor is to compress and compress the vapor of the medium, the pressure inside the chamber must be increased. The backpressure is advantageously greater than the maximum chamber pressure achievable in this way.
Particularly in the case of rotary vane steam compressors, it is advantageous to introduce the liquid medium into the gap space as close as possible to the rotor axis in the case of a gap space extending at least in the radial direction as well. Due to the rotational movement of the rotor and the centrifugal forces occurring thereby, the medium introduced in liquid form is moved radially outwards and thus fills the entire gap space. At the same time, the liquid medium is rotated by the at least one slider which rotates with the rotor and one at least performs radial movement, distributed. According to the invention, the introduced liquid medium is also used, for example, to lubricate the mechanical seal of the drive shaft, which ensures the seal to the outside. The sealing of the drive shaft can be done in this way, for example in the form of a Gleitringwellenabdichtung in this way. In this way, only a lubricant and sealant is necessary, which also can easily connect to the vapor to be compressed of the medium and not have to be separated after leaving the compressor in complex processes of this steam.
In a preferred embodiment of the method, at least a portion of the liquid medium evaporates as it enters the compression chamber from the gap space. This advantageously also applies to that part of the liquid medium which enters the compression chamber from a region between the drive shaft of the rotor and the housing wall, provided that water in liquid form is introduced in this region. The vapor of the medium should absorb as much of the liquid medium. For the uniform distribution of the medium on the housing inner wall of advantage. This is particularly advantageous when water vapor is compressed and liquid water is used as a lubricant. Since the liquid medium is advantageously under the increased backpressure, which is greater than the chamber pressure within the evaporation chamber, there will be a so-called "flash evaporation", which designates an almost sudden evaporation of a relatively large proportion of the liquid medium. In this case, on the one hand, the evaporation performance is increased and at the same time the steam superheating of the vapor of the medium counteracted. Due to the evaporation of the medium introduced in liquid form, the vaporous medium is deprived of energy and thus the temperature is lowered. Certain process parameters of the process may cause the entire liquid portion of the medium to vaporize as it enters the compression chamber. In this case it is possible, for example by spraying or injecting, to introduce further liquid medium into the compression chamber so as to reduce the temperature of the steam and counteract steam overheating.
Preferably, a non-vaporized portion of the liquid medium entering the compression chamber exits the compression chamber through at least one outlet opening through which the compressed vapor also exits the chamber. In an outer surface of the housing, an additional bore can be arranged and closed with a valve. Through this hole additional liquid medium can be introduced into the compression chamber.
The non-evaporated liquid medium collects in particular by the rotational movement of the rotor on the inner wall of the housing and can lubricate in this way, in particular in a rotary vane steam compressor, the slide in its contact with the housing wall.
In order to reduce the friction occurring at this point, advantageously at least a part of the housing can be formed by a rotating hollow cylinder. The hollow cylinder rotates about a housing axis, which is a rotational symmetry axis of the housing and thus also of the hollow cylinder. It advantageously has the same rotational speed or speed as the rotor. As a result, the relative movement between the radially outer end of the at least one slide and the housing wall or the housing is reduced and thus also the friction is reduced. Preferably, this rotating hollow cylinder is mounted in a further outer ring of the housing. Preferably, a gap between the hollow cylinder and the shell ring is in fluid communication with the compression chamber. In this way, the liquid medium, which is pressed by the supply into the gap space and thus enters the compression chamber, reach into a gap between the rotating hollow cylinder and the surrounding outer ring. There it is advantageously kept under pressure, so that the rotating hollow cylinder and the surrounding shroud together fulfill the function similar to that of a sliding bearing. As a result, the occurring friction loss can be reduced in this area. In addition, in this way, liquid medium emerging from the compressor chamber is usefully used. In particular, in this embodiment, it may no longer be necessary to provide a separate outlet opening in the housing of the compressor chamber in order to dispose of the cargo of liquid medium. Rather, it enters the space between the hollow cylinder and the shroud and is used here meaningful.
Also in this area between the rotating hollow cylinder and the shroud, an additional supply can be provided for further liquid medium. This can be done via injection openings or nozzles, can pass through the other liquid medium in this space.
Advantageously, the rotating hollow cylinder can be provided with recesses in areas in which, for example, the radially outer ends of the rotary valves abut the rotating hollow cylinder. Here, for example, a proportion of the liquid medium would collect, so that here increases the sealing and lubricating effect for the same total amount of liquid medium within the compression chamber.
The invention also solves the stated problem by a rotary vane steam compressor for carrying out a method described here. According to the invention, the vapor compressor is a rotary vane vapor compressor which has a housing and a rotor rotatably mounted about a drive shaft, wherein on the rotor at least one slide is arranged, which is displaceable so that it projects beyond the rotor radially outward with respect to a rotor axis. Advantageously, a gap is formed between the housing and the rotor, to which the at least one slide belongs, into which the medium can be introduced in liquid form via the feed.
In a preferred embodiment, two, three, more preferably four slides are arranged on the rotor. It is also possible to arrange a larger number of slides on the rotor. It has proven to be advantageous if the slide is not displaceable with respect to the rotor axis exactly radially outward or inward, but if an angle is included between the radial direction with respect to the rotor axes and the direction of displacement of the respective slide, which is different from 0 °. An alignment of the displacement direction in the radial direction is possible.
Advantageously, a plurality of slides are arranged on the rotor. The introduction of the liquid medium into the gap space is effected by the at least one feed, through which the liquid medium is preferably also introduced into the bearing of the drive shaft for lubricating the mechanical seal. The medium enters after the lubrication of the mechanical seals in particular at least one end face of the compressor chamber into the chamber and is by the movement of the rotor with the slide along this end face, which is formed for example by a housing flange, in the gap between the rotor and the housing directed. A separate supply, for example, within the slider or within an end face of the housing is not necessary.
It has proven to be advantageous if at least part of the housing is formed by a hollow cylinder rotatably mounted about a housing axis, wherein the housing axis is parallel and displaced to the rotor axis, which extends in particular in the longitudinal and symmetry axis of the drive shaft extends.
An exemplary embodiment of such a rotary vane steam compressor has a hollow cylindrical housing with a housing inner diameter of for example 180 mm. The axial length of the housing is for example 200 mm. Within the housing, the rotor is arranged eccentrically, which has an outer diameter of for example 150 mm. This results in a total chamber volume of 1.56 dm 3 , wherein at each revolution of the rotor about twice this chamber volume is sucked. If such a compressor absorbs steam at an absolute pressure of, for example, 0.5 bar, this means a compression mass of 0.96 g per revolution and, at 1,000 revolutions per minute, a compression mass of 58 kg per hour.
This would theoretically achieve a compressor capacity of 50 kg per hour if a vapor pressure of 0.5 bar absolute should be achieved in the intake area.
If the compression capacity is to reach a pressure difference of one bar, the compressor capacity to be applied can be calculated. The free surface of the slide, which applies the compaction performance, ie in the position in which the slider is moved out of the rotor as far as possible, is in this case, for example, 6,000 mm 2 . The required force for this compression is 600 N, so that at a peripheral speed of the spool at 1,000 rpm of 8.64 m per second, a compressor capacity of 5,184 W results. In an adiabatic system, this compressor line would be fully incorporated into the increase in temperature of the steam. When using the water vapor, this leads to a temperature increase of 196 ° K.
The required amount of water to be evaporated in the compressor room to achieve a saturated steam temperature of, for example, 111 ° C at 1.5 bar absolute at the pressure outlet is at a compression capacity of, for example, 50 kg per hour at about 8.3 liters per hour. Here, however, it is merely an exemplary embodiment of the vapor compressor. Other dimensions, pressure differences, inlet and outlet pressures are also possible. In addition, the use of another medium leads to different temperature increase and compressor performance.
In the embodiments described here, consequently, the liquid medium, in particular water, is conducted into the gap space between the housing and the rotor. The sliders, which are parts of the rotor, are lubricated by the liquid under pressure in this area. The slides are preferably as close as possible to the housing wall, in particular on the end walls, to what can be supported, for example, by force application elements, such as spring elements. The slides slide in this case only on the housing wall and are lubricated by the film located thereon of liquid medium.
Advantageously, sealing elements are arranged on the end faces of the rotor, which effect a sealing of the end face of the rotor to the housing. Preferably, sealing elements are attached to the end faces of the hollow cylinder, which can be designed to rotate. These are for example in the form of sealing rings, which advantageously have the same diameter as the hollow cylinder. All of these sealing elements are in contact with the respective side wall and may advantageously be made of PTFE so that they have good sliding properties. This supports the sliding property of the lubricant.
Preferably, the seals are for example provided with obliquely extending small grooves, so profiled that a fluid pressure in the direction of the outer housing ring between the rotating hollow cylinder and the outer housing ring surrounding the hollow cylinder is achieved. The effect of this profiling is very similar to that of a centrifugal pump. Among other things, the pressure built up thereby ensures that the liquid medium, which acts as a lubricant, is kept under pressure in the intermediate space between the housing ring and the rotating hollow cylinder. Excess lubricant re-emerges on the side where the pressure in the compression chamber is lower. This is the side where the suction port is located. This results in a desired circulation of the lubricant, which is supported by the internal friction between the rotating hollow cylinder and the housing ring.
With the aid of the accompanying figures, an embodiment of the present invention will be explained in more detail below. It shows
1 The schematic cross-sectional representation through a vapor compressor according to a first embodiment of the present invention,
2 - The schematic longitudinal section through a vapor compressor and
3 - The schematic representation of an apparatus for performing the method according to another embodiment of the present invention.
1 shows a cross-sectional view through a vapor compressor 1 that has a housing 2 has, in the embodiment shown partially by a rotating hollow cylinder 4 is formed. Inside the hollow cylinder 4 is a rotor 6 arranged around a rotor axis 8th is rotatably mounted. He has a drive shaft 10 , which is driven by a motor, not shown.
Outside the hollow cylinder 4 there is a sheath ring 12 , On the rotor 6 In the embodiment shown are four slides 14 with a slider core 16 positioned with a radially outer end 18 on the hollow cylinder 4 issue. For that are in the hollow cylinder 4 wells 20 arranged in which the radially outer end 18 the slider 16 on the hollow cylinder 4 is applied. In these depressions 20 can collect lubricants and sealants and thus increase the sealing and lubricating effect.
The sliders 14 are in each case a slide groove 22 stored in it along the slide groove 22 are displaceable. It can be seen in the embodiment shown that the slide grooves 22 and the sliders 14 not exactly arranged in the radial direction and are displaced, but that is between the direction of displacement of the slide 14 in the slide grooves 22 and the radially outward radial direction is at an angle.
In operation, the rotor 6 around the rotor axis 8th and the hollow cylinder 4 around a housing axis 24 turned. The outer ends slide 18 the slider 14 in the wells 20 along.
Through the several slides 14 become compressor chambers 26 limited in the circumferential direction. The steam compressor 1 has at least one outlet opening 28 and at least one suction opening 30 ,
2 shows a longitudinal sectional view through the vapor compressor 1 , You can see the shroud ring 12 , the hollow cylinder 4 and the rotor 6 by the drive shaft 10 is rotatable. In the axial direction, the housing 2 through two housing flanges 32 limited, with the shroud ring 12 are rigidly connected. Between the housing flange 32 and the rotor 6 there is a rotor seal 34 through which the compression chamber 26 is sealed radially inward. After radially outward this assumes a hollow cylinder seal 36 between the rotatably mounted hollow cylinder 4 and the housing flange 32 is positioned. In the sheath ring 12 there is at least one inlet opening 38 , through the additional liquid medium, in particular water, for the lubrication of the hollow cylinder 4 can be supplied.
The drive shaft 10 is about a camp 40 stored, and is about shaft seals 42 sealed to the outside. About feeders 44 For example, the medium which is to be compressed by the plant in the vapor state can be supplied in liquid form. This will seal the drive shaft 10 and the contact areas between, for example, the sliders 14 and the housing parts or the hollow cylinder 4 and achieved lubrication of the respective friction surfaces.
One recognizes in 2 that around the drive shaft 10 Mechanical seals 43 are arranged, which are the compression chamber 26 seal against the outside atmosphere. About that by the feeder 44 supplied liquid medium are these mechanical seals 43 sealed and lubricated. About leakage openings 45 can be drained incoming water.
That about the feeders 44 introduced liquid medium is due to the rotation of the rotor 6 moved radially outward on the inner sides of the housing flange and thus lubricates the gap between the housing flange 32 as part of the housing 2 and the rotor 6 , Radially outward on the rotor 6 is the rotor seal 34 , which ensures sufficient pressure of the liquid medium in the gap. The liquid medium is carried further radially outward and thus enters the compression chamber 26 one. The proportion of the liquid medium in the compression chamber 26 not evaporated, enters between the hollow cylinder seal 36 and the housing flange 32 in a space between the hollow cylinder 4 and the jacket ring 12 one. Through the hollow cylinder seal 36 Here, too, a sufficient pressure is built up, which prevents further evaporation of the liquid medium, which now again acts as a lubricant.
3 shows the schematic view of a plant for carrying out the method. You can see the steam compressor 1 with the housing 2 being via a steam supply 46 Steam of a medium of relatively low pressure in the compression chamber of the vapor compressor 1 is introduced. About a motor 48 becomes the drive shaft 10 of the rotor 6 driven. After compression, the compressed steam leaves via a steam discharge 50 the actual steam compressor 1 and becomes a water separator 52 fed. In the exemplary embodiment shown, water vapor is to be compressed, so that liquid water is used as the sealing and lubricating medium. This is done via a water supply 54 the feeder 44 fed and enters the vapor compressor 1 one. Via 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, wherein the steam is supplied to the use and the separated water again in the vapor compressor 1 is initiated.
The water from the water separator 42 gets into a storage container 60 whose level via a level sensor 62 is determined. In the water supply 54 there is a pressure sensor 64 , a conductivity sensor 66 as well as a treatment filter 68 , with which an optimum water quality for the further plant can be achieved.
LIST OF REFERENCE NUMBERS
- steam compressor
- hollow cylinder
- rotor axis
- drive shaft
- casing ring
- slide core
- outer end
- spool groove
- housing axis
- compression chamber
- outlet opening
- housing flange
- rotor seal
- Hollow cylinder seal
- inlet port
- Shaft seal
- Mechanical seal
- Leakage opening
- steam supply
- steam discharge
- water supply
- feed valve
- level sensor
- pressure sensor
- treatment filters