WO2010006663A1

WO2010006663A1 - Cooling for a screw pump

Info

Publication number: WO2010006663A1
Application number: PCT/EP2008/068364
Authority: WO
Inventors: Ralf Steffens
Original assignee: Ralf Steffens
Priority date: 2008-07-18
Filing date: 2008-12-30
Publication date: 2010-01-21
Also published as: CN102099583A; EP2313657A1

Abstract

The invention relates to the cooling for a screw pump for the delivery and compression of gases, wherein the rotors (1) have previously known internal cooling (7). In order to increase the operational reliability and improve the application-specific adaptation, and also in order to reduce the noise, according to the invention the coolant, preferably oil, is not only continuously introduced to the two coolant supplies (21) for internal rotor cooling (7) by way of the coolant pump (10), but the coolant is also continually delivered through the flow chambers (11) in the pump housing (2) and dissipates the heat thereof by way of the coolant pump (10), the cooling air flow over the screw pump is eliminated, the entire machine is preferably enclosed with a noise absorbing material (15), and the heat dissipation for the coolant is carried out by way of a dedicated heat exchanger (16), preferably a separate standard industry oil cooler, either water-cooled or designed as a sufficiently known oil/air cooler, wherein in order to further reduce the noise the necessary cooling fan (14) for said oil/air heat exchanger (16) runs at a reduced rotational speed in that the belt drive (18) between the driving motor (17) and the pump drive shaft (6) with the contrate or bevel gear mechanism (5) is designed such that the driving motor (17) rotates at a lower rotational speed than the pump drive shaft (6), wherein the temperature level of the screw pump can be set in a targeted manner by simple dimensioning of the dedicated heat exchanger accordingly, and the user is additionally provided with the possibility of specifically defining the direction of the heat dissipation by the ability to freely position the heat exchanger (16) and corresponding connecting lines (13 and 19) for the coolant between said dedicated coolant heat exchanger and the screw pump.

Description

Designation: Cooling of a screw pump

State of the art :

Dry compressing pumps gain in particular in vacuum technology increasingly important, because by increasing commitments to environmental regulations and rising operating and disposal costs as well as increased Anfor ^¬ demands on the purity of the pumped liquid, the known wet-running vacuum systems, such as liquid ring machines and rotary vane pumps, and more often replaced by dry compressing pumps , These dry compacting machines include screw pumps, claw pumps, diaphragm pumps, piston pumps, scroll mills and Roots pumps. However, these machines have in common that they still do not meet today's demands in terms of reliability and robustness and size and weight with low price level.

Drying screw pumps are increasingly being used in vacuum technology because, as typical 2-wave displacement machines, they achieve the vacuum-specific high compressive capacity simply by achieving the necessary multiple steps as a series connection of several closed working chambers via the number of wraps per screw spindle rotor in an extremely uncomplicated manner. Furthermore, an increased rotor speed is made possible by the non-contact circulation of the screw spindle rotors, so that at the same time nominal suction capacity and delivery rate increase relative to the size.

In the PCT publication WO 00/12899 a simple rotor cooling is described for a dry-compressing screw pump by a coolant, preferably oil, is introduced into a conical rotor bore. The protective document 102006030966.9 also describes a practical solution for cooling the heated oil. At the same time a cooling air flow is passed through the actual screw pump for heat dissipation. This is not only unfavorable because of the noise development, but also lacks a satisfactory protection against accidents in case of partial failure or reduction of efficiency, for example, by pollution, in the complete cooling system for the spindle rotor pair and the pump housing, because for example the elimination of the fault , about cleaning, is quite complex. Between this Pumpeπgehäuse and the screw spindle rotor pair must be consistent and always synchronous for all operating conditions to ensure that the play distances for non-contact rotation between both rotors and the surrounding pump housing does not fall below a critical minimum value, otherwise for touching as so-called. "Start-up" leads, which leads to the immediate failure of the entire screw pump, briefly referred to as "crash". While this Minimai requirement is still reasonably easy to meet by correspondingly high clearance distances as a so-called "safety reserve", there is still the significant requirement that the clearance distances for all operating conditions remain virtually unchanged in order to achieve the most consistent possible compression behavior of the screw pump , Otherwise, the pumping behavior would be very different, which is understandably very disadvantageous to the user. This requirement applies to all operating states from cold to hot machine as well as to all state changes. This safe and reliable thermal coupling between spindle rotor pair and pump housing has not been satisfactorily solved by the prior art. At the same time, the user often desires compliance with a certain temperature level in the screw pump, which so far can only be moderately fulfilled. For the aforementioned screw pump, the drive is preferably carried out in accordance with the protective documents WO 01/57401 A1 and PCT / EP 2007/056 585.

The object of the present invention is, in a dry-compressing screw pump with a cooling for the screw spindle rotor pair via a coolant which has absorbed the heat of compression from the screw screw rotors, this refrigerant such heat to withdraw that the clearance between the rotor pair and the surrounding Pump housing for all operating conditions and their changes remain almost unverän ^¬ unchanged, both the noise of the entire screw pump is simple and thorough to minimize and mitigate the critical effects of contamination in the cooling system or the elimination of such disturbances in the cooling efficiency is facilitated and The entire temperature level of the screw pump as simple as possible and useful for the particular application not only specifically targeted, but also in the direction each user desires can be removed easily and conveniently. According to the invention, this object is achieved in that the coolant, preferably oil, is continuously introduced not only in the cooling holes of the two spindle rotors, but with the help of the coolant pump constantly flows around the pump housing and dissipates the heat, the cooling air flow through the screw pump omitted, the entire Preferably, the machine is surrounded with noise-insulating material, and the heat dissipation for the coolant, which has absorbed both heat from the spindle rotor pair and the pump housing, via a separate heat exchanger, preferably as a separate standard industrial oil cooler, either water-cooled or designed as a well-known oil / air cooler, to further reduce the noise of the necessary cooling fan for this oil / air heat exchanger runs at a reduced speed by the belt drive between the drive motor and pump drive shaft with the crown or bevel gear Gear is designed so that the drive motor runs at a lower speed than the pump drive shaft, by means of simple size dimensioning of the own coolant heat exchanger, the temperature level of the screw pump is selectively adjustable and on the free positioning of the oil / air heat exchanger with a then own Cooling fan and corresponding supply and discharge lines for the coolant between this own coolant heat exchanger and the screw pump, the user is also given the possibility of targeted directional default for heat dissipation.

As a coolant, the already existing pump oil is preferably taken directly, which is anyway required for the lubrication of the rotor bearing and the synchronization teeth in the side spaces of the screw pump. However, an oil should be chosen that has both adequate lubrication properties for bearings and gear wheels as well as satisfactory heat transfer characteristics. Such oils are well known and available.

The design of the oil cooling for the pump housing takes place according to well-known embodiments, such as cast in the casting of the pump housing (steel) pipe coil or a surrounding casting cavity for coolant / oil flow, these embodiments are preferably provided in the emergence of the greatest compression heat , So in the area of narrowing spindle rotor slopes to the gas outlet of the screw pump out. The heat output for the gearbox takes place just as efficiently on the oil in this gearbox. And according to the invention no longer surrounded by the cooling air pump housing and thus the entire screw pump with the exception of the commercially available air-cooled drive motor is preferably surrounded for effective reduction of the noise level with different sound insulating sheathing, for example, by layered structure with manifold materials the various noises ( with respect to transmission, bearings, gas production, etc.) at higher working speeds of the screw pump satisfactorily dampen and suppress. This simple way of soundproofing is well known and sufficiently effective.

The required for heat dissipation own heat exchanger for the coolant, which has now absorbed the heat from spindle rotor pair and pump housing, is designed so that the dimensions of the heat exchange surfaces and the amount of cooling air flow (or the cooling fluid in water cooling) the desired Temperature level of the entire screw pump is met selectively. With the execution of a separate and mobile heat exchanger, the direction of heat dissipation can still be determined specifically according to customer requirements.

The coolant oil is preferably guided in such a way that the coolant delivery pump (for example as an internal gear pump, also called a "gerotor" pump) first conveys the oil drawn in from the gear housing through the cooling region of the pump housing. From there it passes through a connecting line to its own heat exchanger, where it is cooled and then passes from this heat exchanger directly to the two injection holes for introducing the coolant in both spindle rotors, where it again via the inner tube and the conical bore after receiving the spindle rotor heat Transmission chamber exits, to be sucked in again by the coolant pump, so that this cycle is repeated permanently. Of course, other management options for the coolant are conceivable and permissible.

The heat exchange surfaces for the coolant in the area of the fluid cooling for the pump housing are now dimensioned such that the games between the two spindle rotors and the surrounding pump housing remain virtually unchanged for all operating states. This important goal is now because ^{¬ low} accessible because the coolant according to the invention both heat the spindle rotors and the pump housing dissipates and thus there is always a congruent level in the reference level. The practical dimensioning is now simply carried out in such a way that the temperatures of spindle rotor pair and pump housing are set to almost the same level via measurements and simple model calculations. There can not be a general formula because the heat dissipation depends essentially on the individual conditions of the respective heat transfer: Material and surface properties as well as oil type etc.

The hitherto often kinking air guide is eliminated, the cooling air flow is preferably performed congruent to the cooling fan of the drive motor, even the usually smaller cooling fan for the drive motor can be completely replaced by the larger cooling fan for the heat exchanger, so that the cooling for the drive motor thanks to the more intense Cooling air flow significantly improved.

1 shows an exemplary embodiment of the present invention with a section through the entire screw pump: The counter-rotating screw spindle rotor pair (1) rotates in a pump housing (2) with a gas inlet (3) and a gas outlet (4) , The rotor pair is driven by a crown / bevel gear (5) on the pump drive shaft (6). The commercial air-cooled drive motor (17) drives with a belt drive (18) via the larger motor-side pulley (18. a), the smaller pulley (18. b) and thus the pump drive shaft (6) with the non-rotatable crown / bevel gear (5 ) at. In the case of a screw spindle rotor, the internal rotor cooling (7) is shown broken open by way of example, wherein the coolant oil is led from the coolant supply (21) to the bottom of the bore via a feed inner tube (8), where it is bored out of this inner tube (FIG. 8), then centrifugally assisted by the tapered spindle rotor bore to continuously flow back to the gear rotor side and exit again in the crown / bevel gear room where it mixes with the oil in the gear housing (9) as a conventional oil reservoir. In the transmission housing (9), the oil is now sucked by a feed pump (10). As a coolant delivery pump (10) an internal gear oil pump is exemplified, of course, however, all other common oil pumps are suitable and possible. In operation, this oil pump (10) sucks the oil now from the gear housing and conveys it via the coolant outlet (20) and the leading connecting line (12) in the coolant flow space (11) of the pump housing (2). This coolant Durchströmungsraum (11) can be designed, for example, as cast in the casting of the pump housing (steel) pipe coil (11 a), as shown in the upper section, or as the working space encircling casting cavity (11 b) in the pump housing (2 ) to the coolant / oil flow, these embodiments are to be provided especially in the emergence of the largest compression heat, ie in the area of the spindle rotor slopes becoming closer to the gas outlet (4) of the screw pump. The coolant is conveyed from the pump housing throughflow spaces (11) to the own coolant heat exchanger (16) via the outgoing connecting line (13), which is shown here as an air-cooled example.

The coolant flows through this heat exchanger (16) from the inlet E to the outlet A and is thereby cooled by the cooling-Lütter (14) generated cooling stream and then leaves the outlet A, the heat exchanger (16), and then still by oil pump (10) conveyed via the returning connecting line (19) to reach the two coolant supply lines (21). From there it passes per spindle rotor via feed inner tube (8) into the spindles for local heat dissipation, as described above.

To reduce noise, the belt drive (18) over the size of the pulleys (18 a and 18 b) designed such that the drive motor (17) runs at a lower speed than the pump drive shaft (6). In addition, the entire screw pump with the exception of the mostly air-cooled drive motor (17) to further reduce the noise level with a sound-absorbing sheath (15) surrounded, this sheath is conveniently constructed in layers with different Schalldampfenden materials, which in the present Fig. 1 as an example Noise-insulating casing (15.a) and as inner casing (15.b) is shown.

Other embodiments are of course possible in detail at any time.

This concerns in particular the design and positioning of the heat exchanger (16), which can of course be equipped with its own cooling fan, which is offered by the industry as a catalog product even as a complete unit ready so then to the screw pump virtually any according to customer requirements be positioned - of course, with the correspondingly extended connecting cables as a leading away Line (13) and return line (19), so as to be able to easily realize the direction of heat dissipation according to customer requirements.

Alternatively, for example, the usual engine's own standard cooling fan can be replaced by the air flow more intensive cooling fan (18), in which case the heat exchanger (16) would also be positioned correspondingly cheaper on the other side of the engine.

With dimensioning of the heat exchanger (16) for the heat dissipation of the coolant, the temperature level of the screw pump is determined decisively and carried out according to customer requirements, which was practically not possible because the invention secure coupling of the heat balances for the working space elements of spindle rotor pair (1) and pump housing (2) so far was not reliable.

In addition, with the present invention, the reliability of the entire screw pump is significantly improved by monitoring the condition of the entire screw pump accurately by simply monitoring the oil temperature, which is well known and proven in the prior art.

The cleaning is also facilitated because no longer the most time-consuming access to the cooling surfaces of the previously air-cooled screw pump has to be accomplished, but simply and only the heat exchanger has to be cleaned.

Claims

claims

1. Screw pump for conveying and compressing gases with a counter-rotating screw spindle rotor pair (1) in a pump housing (2) and with a coolant delivery pump (10) for conveying this coolant, characterized in that the coolant from the coolant pump (10) is conveyed through one or more coolant flow-through chambers (11) in the pump housing (2), and that the coolant is brought to each spindle rotor for internal rotor cooling (7) by means of the coolant pump (10) and that the coolant from the coolant pump (10) through a coolant heat exchanger (16) is moved.

2. Screw pump according to claim 1, characterized in that this coolant is the oil which is used in the side spaces of the screw pump for lubricating bearings and teeth.

3. Screw pump according to one of the preceding Ansprü ^¬ che, characterized in that the coolant pump (10) first conveys the coolant through one or more coolant flow chambers (11) in the pump housing (2), then through the heat exchanger (16) pumps and thereafter moving the coolant to the coolant supply ports (21) in each rotor rotor internal cooling rotor (7).

4. Screw pump according to one of the preceding claims, characterized in that the coolant pump (10) via leading connection lines (12) with the flow spaces (11) in the pump housing (2) and wegführende connection lines (13) of the flow areas (11) in the pump housing (2) to the heat exchanger (16) and return connection lines from the heat exchanger (16) is connected to the coolant supply lines (21) for each spindle rotor.

5. Screw pump according to one of the preceding claims, characterized in that the coolant throughflow chamber (11) in the pump housing (2) as in the casting of the pump housing (2) inserted (steel) pipe coil (11 a) is executed.

6. Screw pump according to one of the preceding Ansprü ^¬ che, characterized in that the coolant flow-through space (11) in the pump housing (2) as in the casting of the pump housing (2) provided cavity (11) is executed.

7. Screw pump according to one of the preceding claims, characterized in that the coolant flow-through spaces (11) in the pump housing (2) in the range of small and decreasing slope values of the spindle rotor pair (1).

8. Screw pump according to one of the preceding claims, characterized in that the heat exchanger (16) with a cooling Lütter (14) is operated, which runs at a lower speed than the pump drive shaft (6).

9. screw pump according to the preceding claim, characterized in that the cooling fan (14) for the heat exchanger (16) on the shaft of the drive motor (17) is fixed, which drives the pump drive shaft (6) via the belt drive (18) in that the rotational speed of this pump drive shaft (6) is above the rotational speed of the drive motor (17).

10. Screw pump according to one of the preceding claims, characterized in that the cooling fan (14) replaces its own fan of the drive motor (17).

11. Screw pump according to one of the preceding claims, characterized in that a standard-moderate industrial oil cooler is used as a heat exchanger (16).

12. Screw pump according to one of the preceding claims, characterized in that the heat exchanger (16) for discharging the coolant heat is either water-cooled or operated with air flow cooling.

13. Screw pump according to one of the preceding claims, characterized in that a sheath (15) surrounds the screw pump with the exception of the drive motor (17).

14. Screw rotor pump according to one of the preceding claims, characterized in that several casings (15 a and 15 b) surrounding the screw pump with from ^¬ exception of the drive motor (17).

15. Screw pump according to one of the preceding Ansprü ^¬ che, characterized in that a plurality of shells (15 a and 15 b) in layers surrounding the screw pump with the exception of the drive motor (17).

16. Screw pump according to one of the preceding claims, characterized in that the pump housing (2) is no longer flowed around by cooling air.

17. Screw pump according to one of the preceding claims, characterized in that over dimensioning of the heat output in the heat exchanger (16) the

Temperature level of the screw pump is controlled.

18. Screw pump according to the preceding claim, characterized in that the dimensioning of the heat output in the heat exchanger (16) via the size of the heat exchanging surfaces takes place and / or by regulating the flow rate of the laxative cooling fluid.

19. Screw pump according to one of the preceding claims, characterized in that the heat exchanger (16) is positioned so that the Wärmeabführ- direction is adapted to the particular application.

20. Screw pump according to the preceding claim, characterized in that the heat exchanger (16) receives its own cooling fan (14).

21. Screw pump according to one of the preceding claims, characterized in that the temperature of the coolant is monitored and controlled.

22. Screw pump according to the preceding claim, characterized in that in case of deviations from the target temperature for the coolant, a warning.

23. Screw pump according to the preceding An ^¬ claim, characterized in that the warning off acoustically and / or optically and / or the screw pump.