DE102009016790A1 - Oil-flooded high pressure screw compressor unit, has bypass channel connected with inlet port at housing, and inlet port arranged in relation to outlet so that port is connected with working chamber that is formed by tooth spaces of rotors - Google Patents

Abstract

The unit has screw rotors arranged on a body, and a bypass channel provided with a fluid flow control valve device that is connected with a pressure tank. The tank is arranged on downstream behind of a pressure chamber (9). The controlled bypass channel is connected with an inlet port (7) at a compressor housing. The inlet port is arranged in relation to an outlet (5) so that the inlet port is connected as the outlet and is connected with a V-shaped working chamber (3) that is formed by tooth spaces of rotors. The bypass channel is arranged with a control valve out side of the housing.

Description

The Invention relates to a screw compressor unit with a screw compressor, especially an oil-flooded Screw compressor, for size pressure conditions with internal compression, with at least two pairs interlocking in parallel arranged screw rotors having combs and grooves, wherein the combs and grooves of the two rotors along a common line of action in sealing comb engagement stand and the grooves separated by the engagement line become. This forms V-shaped Working chambers, which are enclosed by a housing, the from a shell wall and from end walls with the comb and End profile edges of the rotors controllable inlets and outlets for the working medium exists. The controllable inlets and outlets shut down suction chamber and pressure chamber. In front of the suction chamber is upstream one Power control device arranged, with the help of the compressor to be promoted Mass flow can be controlled.

shell wall and end walls of the compressor housing form a cavity through at least two parallel, one another cutting holes, in which the screw rotors with their V-shaped working chambers are arranged. Rotational movement of the rotors increases the suction side V-shaped Working chambers on the communicating with the suction chamber Side, whereby working medium in these tooth spaces from the suction space over one or several inlets flows.

On the other side of the common line of action shrink during rotary motion the v-shaped Working chambers, allowing a compression of a compressible working fluid can take place.

ever according to the location of the outlet control edges defined in the pressure-side housing end wall one or more outlets that begin the opening a V-shaped Set working chamber towards the pressure chamber, will be the same otherwise Conditions on the condition of the working medium at the beginning of compression dependent Pressure in the V-shaped working chamber at the opening time this result, the independent from the pressure in the pressure chamber is, bigger, equal or smaller than this one can be. The opening time corresponds the angular position of at least one rotor in the one communicating Connection of the V-shaped working chambers, which reduce in size as a result of rotor rotation to the outlet arises.

The geometric relationship between the gullet volumes the V-shaped Working chambers at the time of separation from the suction side due Rotor rotation and tooth space volumes at the time of opening the pressure side V-shaped Working chambers to the outlet is the geometric volume reduction ratio Vi. The value Vi is for the full load operation of the screw compressor designed so that the sum of the losses is minimized and the compressor highest efficiency having. The internal compression, which is determined by the Vi value is conditional, reaches one with respect to the pressure in the pressure line optimum value of the compressor.

In order to change the volume of funding the screw compressor unit of the type described with a Saugdruckdrosseleinrichtung is the control device on the suction side the compressor is more or less closed, so that the mass flow due to the throttle relaxation of the working fluid in the control device more or less changes. With zero funding, Part load operation without promotion of working medium in the downstream pressure lines, is the Suction pressure throttle completely closed.

When Consequence of throttling at partial load and zero load change the state variables pressure and temperature of the working medium behind the control device and so that in the suction side V-shaped working chambers at partial load operation opposite full load operation with complete open Control device.

adversely is on compressor units with this kind of regulation that the achievable by internal compression pressure ratio with increasing throttling reduced.

Due to the control principle of the suction throttle control, the internal compression selected for full load operation is insufficient to sufficiently raise the internal pressure before opening the outlet or the outlets. As a result, working fluid flows back from the pressure space into the V-shaped working chamber through the outlets opening as a result of the rotor rotation when the screw compressor is operated at partial load. The working medium that has flowed back from the pressure chamber is immediately pushed out again by the volume reduction of the V-shaped working chamber, which is proceeding with further rotor rotation. This reciprocal toothed mass transport is a strong excitement for forced gas oscillations in the pressure chamber and in the pressure chamber adjacent pipes. Especially at large external pressure ratios, calculated from final pressure divided by suction, occur due to the large pressure differences between the pressure of Working medium immediately before opening the outlet opening in the V-shaped working chamber and with the outlet in Connecting pressure chamber dynamic pressure pulsations whose amplitudes may be greater than the actual operating pressure difference and thus jeopardize the reliability of the compressor and the entire pressure booster.

task The invention is to eliminate this disadvantage. According to the invention, it is proposed that a controlled bypass passage between a pressure space downstream the pressure line connects, for example, the oil separator, and a location on the compressor housing, which has a lower pressure potential than the pressure chamber arranged is and connection to the V-shaped Working chambers receives, before the outlet or outlets open. Of the controlled bypass channel has a valve assembly that opens when the pressure in the working chamber by a predefined pressure difference is below the pressure in the pressure chamber.

The dependent on load operation Pressure difference between the working chamber internal pressure and the system pressure level in the pressure line can be advantageous for opening and closing the controlled by-pass valve. The controlled valve arrangement can also use auxiliary power together with the suction regulator or in a functional context, for example in relation to throttling of the suction pressure regulator, opened or closed.

The controlled valve arrangement is opened, for example, when the suction pressure regulator is throttled. It is closed when the suction pressure regulator open becomes.

in the controlled bypass channel known control valves are arranged. Control valve and parts of the controlled bypass channel are in one advantageous embodiment in the compressor housing arranged.

In another embodiment of the invention the controlled bypass channel with control valve arranged outside the compressor housing.

Of the Bypass channel opens at the entrance in or on the compressor housing. The location of the inlet is in relation to the outlets arranged so that they earlier with those through the tooth gaps the rotors formed V-shaped Working chambers communicatively connected as the outlets.

The Location of the entrance opening the controlled bypass channel on the compressor housing is in an embodiment of the invention about arranged a tooth pitch in front of the control edges of the outlets.

Advantageous loses the entrance opening due to the rotational movement of the rotors in the angular position the connection to a considered V-shaped Working chamber when communicating with the outlets. There is no rotation angle range during which a simultaneous communicating Connection between the inlet opening of the controlled bypass channel on the compressor housing, the downsizing V-shaped Working chamber and the outlets consists.

In another advantageous embodiment is the entrance opening with respect to the control edges of the outlets arranged so that the downsizing V-shaped Working chambers during a rotation angle range simultaneously with the outlet opening and communicating with the controlled bypass channel. This Rotation angle range for the Arrangement of the inlet opening of the controlled bypass channel is smaller than the tooth pitch angle, which divided the quotient 360 ° by the number of teeth corresponds to the main rotor.

As a result This arrangement of the controlled bypass channel arises to a V-shaped tooth gap due Rotor rotation first a communicating connection of the controlled Bypass channels, then a communicating connection to the outlets.

As a result this arrangement of the controlled bypass channel disappears to a V-shaped tooth gap due Rotor rotation first the communicating connection of the controlled one Bypass channels before the outlets are completely open due to further rotor rotation.

During this Rotation angle range is the decreasing due to rotor rotation V-shaped Working chamber over filled the controlled bypass channel, whereby less when opening Working medium from the pressure chamber via the outlets flows into the working chamber and consequently the excitation of a forced gas oscillation is prevented.

By the embodiment of the invention then flows Working fluid into the tooth gaps, if the pressure at the beginning of the discharge process due to Saugdruckdrosselung would be too low. The tooth gap is before the start of the exhaust process via the controlled bypass channel filled with working medium, so that the pressure difference between the pressure chamber and V-shaped working chamber before opening is reduced to the pressure chamber and thus the Pulsationserregung is so greatly reduced that gas pulsations in the pressure line be avoided.

The amplitudes of the enforced are reduced so far that the compressor at low load operation down to zero production safe operation tet.

Advantageous is in another arrangement according to the invention in the controlled Bypass duct arranged a valve that uses auxiliary power in dependence opened by the pressure behind the power control device or is closed.

In Another advantageous embodiment of the invention is in the controlled bypass channel directional Valve arranged automatically depending on the pressure difference between Inlet and outlet side of this valve opens or closes. This Valve is only in one flow direction flowed through to the connection of the bypass channel to the compressor. His Construction corresponds to a spring-loaded in an embodiment according to the invention Check valve.

The Pressure difference to open the valve is predefined by known means, e.g. B. spring force and opening cross-sectional area.

This Control valve remains closed until the predefined pressure difference is reached at partial load operation. It opens when the pressure in the V-shaped working chamber As a result of lowering the suction pressure, the level drops so far that the pre-set Pressure difference exceeded becomes.

In the case, that the enclosed geometric volume in the controlled bypass channel between the control valve and the inlet opening with respect to the geometric Volume gap volume the V-shaped Working chambers leads to efficiency losses of the compression process is according to the invention a second oil-carrying line from the oil sump of the oil separator or communicatively connected components of the compressor unit arranged over the one oil stream is fed into this channel section.

The Invention is based on an embodiment explained in more detail, however she should not be limited to that be. In the associated Drawings show:

1 FIG. 3: a longitudinal section of a compressor design according to the invention, FIG.

2 FIG. 3 is a cross-sectional view of another compressor embodiment according to the invention. FIG

3 a basic version of an automatically operating pressure control valve

4 an inventive arrangement compressor bypass duct pressure vessel (oil separator)

5 shows the arrangement of the inlet opening on the compressor housing with respect to the outlets.

6 shows the other arrangement of the inlet opening on the compressor housing with respect to the outlets.

7 an inventive arrangement compressor bypass duct pressure vessel (oil separator)

8th a basic version of a pressure control valve, which uses the pressure at the inlet opening on the compressor housing as the control pressure.

9 an inventive arrangement compressor bypass duct pressure vessel (oil separator)

10 a basic version of a pressure control valve, which uses the pressure of the suction-side control valve as the control pressure.

The The invention is not limited to the examples shown.

Out establish The representability was chosen only in examples where the controlled bypass channel outside the compressor housing is.

If the bypass control valve is integrated into the compressor housing, the Outside wall parts of be shown variants of the bypass control valve parts of the compressor housing or in the compressor housing be mounted.

According to 1 and 2 the compressor has a housing which, among other things, the suction chamber 1 , the housing shell wall 8th and the pressure-side end wall 4 has. The suction room 1 is over an inlet 2 with V-shaped working chambers 3 connected. The V-shaped working chambers decrease as a result of the rotation of the main rotor 6 and the meshing side rotor 14 , They are after appropriate rotation of the two rotors via the outlets 5 with the pressure room 9 connected so that the working fluid in the pressure line 20 flows. The outlets 5 have a radial and an axial portion (see also 5 and 6 ).

In the housing shell wall 2 are a main rotor 6 . 13 and a side engine 14 arranged in coaxial position of their axes of rotation to the bore axes. When the rotors rotate, they increase with the suction chamber 1 communicating V-shaped working chambers, thereby adding working fluid into these tooth spaces from the suction space 1 over the inlet 2 flows. On the other side of the plane containing the rotor axes of rotation, the V-shaped working chambers shrink during rotation, so that compression takes place, the compression end pressure, the internal pressure, the geometric volume reduction ratio Vi and the state of the working medium in the suction space 1 of the compressor depends.

The condition of the working fluid in the suction chamber 1 the compressor changes when the compressor is operated at partial load because the pressure behind the suction pressure regulator 11 decreases.

The internal pressure of the working fluid due to internal compression decreases with increasing throttling of the suction pressure regulator 11 ,

If the defined pressure difference between pressure in the pressure tube 9 and reaches internal pressure, opens the controllable bypass valve, and it flows working fluid from the oil separator through the inlet opening 7 in the V-shaped working chambers, so that the internal pressure rises by almost isochore compression before the outlets 5 are completely open.

The entrance opening 7 or 7a can be arranged at different locations of the housing when the distance condition to the outlets 5 is complied with.

By returning working fluid from the high pressure side, the outlets decrease at the time of opening 5 the pressure difference between pressure chamber 9 and internal pressure. As a result, gas pulsations are significantly reduced and brought to a permissible level.

The Control of the supply of working medium is self-regulating.

Will the suction pressure regulator 11 opened again, the pressure in the suction chamber increases 1 and thus also the internal pressure in working chambers before opening the outlets 5 back to. The controllable bypass valve closes automatically, as the pressure difference between the inlet opening 7 and final pressure in the oil separator again reduced. 3 shows the controllable bypass valve 15 in a design as a spring-loaded check valve. The recirculated working fluid flows from the oil separator in the flow direction 16 into the valve when the pressure at the outlet in the bypass passage to the housing housing opening 17 at the compressor has fallen so far that the pressure difference between this pressure and the pressure in the oil separator is sufficient to overcome the spring force.

In 4 is the arrangement of the controllable bypass channel 19 between pressure vessel / oil separator 18 and inlet 7 shown on the compressor. 5 and 6 show two examples of the arrangement of the inlet opening 7 the controlled bypass channel with respect to the outlets 5 ,

The tooth pitch 23 is the reference for the distance 25 between the outlets 5 and the entrance opening 7 ,

In 5 corresponds to the distance 25 a tooth pitch 23 ,

The entrance opening 7 due to the rotational movement of the rotors in the angular position loses the connection to a considered V-shaped working chamber when a communicating connection to the outlets 5 arises. There is no rotation angle range during which a simultaneous communicating connection between the inlet opening 7 of the controlled bypass channel 19 on the compressor housing, the decreasing V-shaped working chamber and the outlets 5 consists.

In 6 is the distance 25 smaller than the tooth pitch 23 ,

In this embodiment, the inlet opening 7 with respect to the control edges of the outlets 5 arranged so that the decreasing V-shaped working chambers during a rotation angle range simultaneously with the outlets 5 and the controlled bypass channel 19 is communicatively connected. This rotation angle range for the arrangement of the inlet opening 7 of the controlled bypass channel 19 is smaller than the tooth pitch angle 23 i, the quotient of 360 ° divided by the number of teeth of the main rotor 6 . 13 equivalent.

As a result of this arrangement of the controlled bypass channel 19 arises to a V-shaped tooth gap due to rotor rotation, first a communicating connection of the controlled bypass channel 19 , then a communicating connection to the outlets 5 ,

As a result of this arrangement of the controlled bypass channel 19 As a result of rotor rotation, the communicating connection of the controlled bypass channel first disappears into a V-shaped tooth gap 19 before the outlets 5 are completely open due to further rotor rotation.

During this rotation angle range, the V-shaped working chamber, which decreases as a result of rotor rotation, becomes via the controlled bypass channel 19 filled, whereby when opening less working fluid from the pressure chamber 9 flows into the working chamber and consequently the excitation of a forced gas oscillation is prevented.

Both variants differ slightly gig in the drive power.

Through this embodiment according to the invention flows over the bypass channel 19 Working fluid into the tooth spaces if the internal pressure at the beginning of the discharge process were too low relative to the discharge pressure of the equipment as a result of the suction pressure restriction.

The tooth gap, however, before the start of the exhaust operation on the controlled bypass channel 19 filled with working fluid, so that the pressure difference between the pressure chamber and V-shaped working chamber is reduced before opening to the pressure chamber and thus the pulsation excitation is so greatly reduced that gas pulsations are avoided in the pressure line.

In 7 to 10 Further embodiments of the invention are shown, the other options for controlling the bypass channel 19 demonstrate.

7 is characterized by a self-regulating bypass control valve, which in 8th is shown.

As the internal pressure of the V-shaped gullets changes, the pressure on the port drops 26 and at the connection 27 , The at the connection 28 applied final pressure of the compressor system will overcome the spring force when the desired pressure difference between inlet 28 and control pressure port 26 is reached. Then the bypass channel 19 opened, and working fluid flows to the inlet opening 7 , 9 is represented by an externally controlled bypass control valve, which is controlled by a functional connection to control the suction pressure regulator. When the suction pressure regulator 11 closes, opens the bypass control valve 15 ,

In 10 this link is not shown.

1

suction

2

inlet

3

working chamber at intake pressure

4

pressure side end wall

5

outlets

6

main rotor

7

Entry opening of the controlled bypass channel on the compressor housing

8th

Housing casing wall

9

pressure chamber

10

suction end wall

11

Suction pressure

12

V-shaped working chamber

13

main rotor

14

Besides rotor

15

controllable Bypass control valve

16

flow direction

17

to Housing opening on compressor

18

Pressure vessel oil separator

19

controllable bypass channel

20

pressure line

21

direction of rotation Besides rotor

22

direction of rotation main rotor

23

Pitch angle at the main rotor

24

distance the entrance opening to the outlet = tooth pitch angle,

25

distance the entrance opening to the outlet <tooth pitch angle

26

Control pressure connection

27

procedure

28

Intake

Claims (10)

Screw compressor unit, with at least one screw compressor, with internal compression, with at least two pairs interlocking, parallel screw rotors having combs and grooves, with a housing consisting of a shell wall and end walls with controllable from the comb edges of the rotors inlets and outlets for the Working medium, which connect suction chamber and pressure chamber, and shell wall and end walls enclose a working space, which is formed by at least two parallel, intersecting housing housing in which the screw rotors are arranged and with a flow control device, as a controllable throttle and / or Shut-off device is arranged in front of the inlet, characterized in that a bypass channel is provided with a flow-controllable valve device which is communicatively connected to a pressure vessel, which is arranged downstream of the pressure chamber, and the controlled bypass passage is connected to an inlet opening on the compressor housing, and that the inlet opening is arranged with respect to the outlets so that it communicates with the V-shaped working chambers formed by the tooth gaps of the rotors formerly communicating as the outlets. Screw compressor according to claim 1, characterized that control valve and parts of the controlled bypass channel arranged in the compressor housing are. Screw compressor according to claim 1 to 3, characterized characterized in that the controlled bypass channel with control valve outside of the compressor housing is arranged. Screw compressor according to claim 1 to 3, characterized in that the controllable valve device at a predefined pressure difference between pressure in the pressure chamber and pressure in working chambers opens or closes. Screw compressor according to claim 1 to 3, characterized characterized in that the controllable valve device in functional Connection with the suction throttle controller opens or closes. Screw compressor according to claim 1 to 3, characterized characterized in that the controllable valve device in dependence from a predefined pressure difference between pressure in the pressure chamber and pressure in working chambers opens or closes. Screw compressor according to claim 1, characterized that the pressure chamber of the oil separator is. Screw compressor according to claim 1, characterized that the entrance opening the controlled bypass channel about a tooth pitch in front of the control edges the outlet on the compressor housing is arranged. Screw compressor according to claim 6, characterized that the entrance opening the controlled bypass channel exactly one tooth pitch in front of the control edges the outlet on the compressor housing is arranged. Screw compressor according to claim 6, characterized that the entrance opening of the controlled bypass channel less than one tooth pitch in front of the Control edges of the outlet is arranged on the compressor housing.