EP0172430B1 - Cooling method for a screw compressor, and a screw compressor for carrying out this method - Google Patents

Cooling method for a screw compressor, and a screw compressor for carrying out this method Download PDF

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Publication number
EP0172430B1
EP0172430B1 EP85109194A EP85109194A EP0172430B1 EP 0172430 B1 EP0172430 B1 EP 0172430B1 EP 85109194 A EP85109194 A EP 85109194A EP 85109194 A EP85109194 A EP 85109194A EP 0172430 B1 EP0172430 B1 EP 0172430B1
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EP
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Prior art keywords
condensate
temperature
screw compressor
fresh water
temperature value
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EP85109194A
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German (de)
French (fr)
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EP0172430A1 (en
Inventor
Günter Seidel
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Aerzener Maschinenfabrik GmbH
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Aerzener Maschinenfabrik GmbH
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
    • F04C29/04—Heating; Cooling; Heat insulation
    • F04C29/042—Heating; Cooling; Heat insulation by injecting a fluid

Definitions

  • the present invention relates to a method for cooling a screw-type rotor and a screw compressor having meshing engagement with the screw-groove rotor, condensate being fed into a compression space formed by the rotors and the wall of the working space surrounding them, which is obtained in a separator connected on the outlet side.
  • the invention further relates to a screw compressor for performing the method.
  • the condensate is usually fed into the compression space from a common collecting chamber via a plurality of bores arranged in the wall of the compression space. These bores open into the compression chamber both in an area in which it is not yet sealed off from the inlet and in an area in which the so-called internal compression is already taking place.
  • the fed-in condensate only evaporates when the required temperature is reached in the course of the compression process, part of the condensate remains in the liquid area at the inlet and at the start of the compression process, especially since such compressors are usually run with excess water to achieve an effective washing effect .
  • the sealing arrangements for the shaft bearings must also be designed to be relatively complex in the case of compressor designs of the type mentioned. Vacuum or overpressure air barriers must be provided, which requires a not inconsiderable additional effort and the use of external energy.
  • the object of the present invention is to provide a procedure for cooling a screw compressor and a screw compressor for carrying out the method, in which or in which the use of stainless steel and special materials in the manufacture can be dispensed with in favor of cheap materials, and complex sealing arrangements for the rotor shafts and the shaft bearings are not required.
  • the features according to the invention create a procedure in which the cooling water injection process is graded for the first time in all operating phases and is carried out precisely and in a controlled manner depending on the temperature of the conveyed medium, so that only superheated steam is produced in the compressor.
  • condensate can neither accumulate on the suction side nor on the pressure side, so that the use of stainless steel or special materials in these areas is not necessary and cheaper materials can be provided.
  • the control of the condensate and fresh water feed can be controlled as a function of the temperature of the conveyed medium in the outlet line in the most favorable manner for the respective operating conditions.
  • a particularly simple and reliable control is achieved, however, when the condensate feed occurs when a first low temperature value is reached and the fresh water feed occurs when a second higher temperature value is reached and the feed is interrupted again when the temperature values are fallen below.
  • the condensate is only injected into the compression chamber when the compressed medium has reached a certain temperature at the end of the compression process. If the temperature falls below the predetermined temperature value due to the condensate injection, the condensate injection is interrupted again so that the temperature can rise again.
  • the temperature of the pumped medium increases white despite the condensate injection ter on, fresh water is injected into the compression chamber when the second higher temperature value is reached, thus causing additional cooling of the pumped medium. If the temperature drops again below the second higher temperature value due to the fresh water injection, the fresh water feed is interrupted again. When the temperature rises again above the second higher temperature value, fresh water is then fed into the compression chamber again.
  • the condensate is fed into the compression space via a first feed line and the fresh water via a second feed line.
  • this feed line is in each case equipped with a valve, the valves being controlled by a temperature switch arranged in the outlet line of the compressor.
  • the valves are controlled by a temperature switch which responds to two adjustable temperature values.
  • This temperature switch opens the valve for the condensate supply line when the first lower temperature value is reached and the valve for the fresh water supply line when the second higher temperature value is reached. Furthermore, this temperature switch closes the respective valves as soon as the temperature drops below the respective temperature value.
  • valves can be designed in any manner. However, it is advantageous if the valves are designed as solenoid valves or as water flow regulators.
  • a cooler is provided in the outlet line, as seen in the flow direction, upstream of the condensate separator.
  • the temperature switch in the outlet line is expediently arranged upstream of the cooler, as seen in the flow direction.
  • the coating of rotors of screw compressors is basically already known. Rotors of screw compressors are coated with plastic, for example, and such a coating also achieves an optimal sealing effect and efficiency.
  • Plastic coatings however, have the disadvantage that the compressors have to be dismantled and dismantled in the event of signs of separation.
  • Lime-coated rotors on the other hand, can be reworked in the installed state without dismantling. To do this, it is only necessary to selectively supply untreated fresh water in order to touch up the detached areas.
  • the drawing shows a screw compressor 1 equipped with a screw rib rotor and a screw groove rotor, which has an inlet 2 and an outlet 3.
  • the outlet 3 opens into an outlet line 4 in which a conventional cooler 5 is arranged.
  • the condensate separator 6 is equipped with a first feed line 7, via which the condensate obtained in the condensate separator is returned to the compressor.
  • the first feed line 7 is equipped with a valve 8 with which the feed of the condensate into the compression space of the compressor can be controlled.
  • the condensate is fed into the compression chamber at a point at which the compression chamber is already closed off from the inlet of the compressor.
  • Fresh water can be fed into the compression chamber of the compressor via a second feed line 9, which is equipped with a valve 10.
  • the feed point for the fresh water into the compression chamber is arranged in such a way that it is downstream of the feed point for the condensate in the direction of conveyance of the compressor.
  • a temperature switch 11 is arranged in the outlet line 4 between the outlet 3 and the cooler 5.
  • this temperature switch 11 has two adjustable temperature values T i and T 2 .
  • the valves 8 and 10 which are designed as solenoid valves in the present exemplary embodiment, are controlled.
  • the control is designed as follows:
  • Both the valve 8 and the valve 10 are closed at a temperature of the delivery medium in the outlet 3 which is below the temperature values T 1 and T 2 . If the temperature now rises to the temperature value T i , the valve 8 for the condensate is opened via the temperature switch 11. When the temperature reaches the temperature value T 2 , the valve 10 for the fresh water is additionally opened. When the temperature drops below the temperature value T 2, the temperature switch 11 closes the valve 10 again. If the temperature then drops below the temperature value T 1, the valve 8 is also closed via the temperature switch 11.
  • the temperature value T i is set, for example, to 200 ° C and the temperature value T 2, for example to 220 ° C, the following procedure results when compressing air:
  • the compressed air in the outlet 3 initially has a temperature which is below 200 ° C.
  • the valve 8 for the condensate and the valve 10 for the fresh water are therefore closed in this phase.
  • the temperature switch 11 opens the valve 8. Since there is no condensate at this point in time, the temperature of the air in the outlet 3 will continue to rise.
  • the valve 10 opens so that fresh water can be fed into the compression chamber. As a result, the temperature of the air in outlet 3 drops again.
  • valve 10 closes again, so that the fresh water supply is interrupted. This process is repeated until sufficient condensate has accumulated in the condensate separator 6, which can be fed into the compression space via the first feed line 7 and the valve 8. If the temperature in outlet 3 drops below 220 ° C due to the condensate feed, valve 2 is first closed and thus the fresh water feed in the compression chamber is interrupted. If the temperature drops further below 200 ° C, the valve 8 is also closed, so that neither condensate nor fresh water is fed into the compression chamber.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)

Description

Die vorliegende Erfindung betrifft ein Verfahren zum Kühlen eines einen Schraubenrippenrotor und einen mit diesem in Kämmeingriff stehenden Schraubennutenrotor aufweisenden Schraubenverdichters, wobei in einen von den Rotoren und der Wandung des diese umgebenden Arbeitsraumes gebildeten Verdichtungsraum Kondensat eingespeist wird, welches in einem auslassseitig angeschlossenen Abscheider gewonnen wird. Die Erfindung betrifft ferner einen Schraubenverdichter zum Durchführen des Verfahrens.The present invention relates to a method for cooling a screw-type rotor and a screw compressor having meshing engagement with the screw-groove rotor, condensate being fed into a compression space formed by the rotors and the wall of the working space surrounding them, which is obtained in a separator connected on the outlet side. The invention further relates to a screw compressor for performing the method.

Bei bekannten Schraubenverdichtern (vgl. US-A-35 35 057 und 31 29 877) wird das Kondensat aus einer gemeinsamen Sammelkammer meist über eine Vielzahl von in der Wandung des Verdichtungsraumes angeordneten Bohrungen in den Verdichtungsraum eingespeist. Diese Bohrungen münden in den Verdichtungsraum sowohl in einem Bereich, in dem dieser noch nicht gegenüber dem Einlass abgeschlossen ist als auch in einem Bereich, in dem bereits die sogenannte innere Verdichtung stattfindet. Da jedoch das eingespeiste Kondensat erst im Verlaufe des Verdichtungsprozesses bei Erreichen der erforderlichen Temperatur verdampft, verbleibt ein Teil des Kondensates im Bereich des Einlasses und zu Beginn des Verdichtungsprozesses zwangsläufig noch in flüssigem Zustand, zumal derartige Verdichter zur Erzielung eines wirksamen Wascheffektes meist mit Wasserüberschuss gefahren werden.In known screw compressors (cf. US-A-35 35 057 and 31 29 877), the condensate is usually fed into the compression space from a common collecting chamber via a plurality of bores arranged in the wall of the compression space. These bores open into the compression chamber both in an area in which it is not yet sealed off from the inlet and in an area in which the so-called internal compression is already taking place. However, since the fed-in condensate only evaporates when the required temperature is reached in the course of the compression process, part of the condensate remains in the liquid area at the inlet and at the start of the compression process, especially since such compressors are usually run with excess water to achieve an effective washing effect .

Diese verbleibende Kondensat kann sich in Vertiefungen ansammeln und in Abhängigkeit des saugseitigen Druckes mit der Dichtanordnung für die Rotorwellen in Verbindung gelangen. Es ist daher erforderlich, diese Teile aus rostfreiem Stahl herzustellen und in diesem Bereich Sondermaterialien einzusetzen. Kondensat verbleibt auch in denjenigen Betriebsphasen in flüssigem Zustand, in denen sich das Gehäuse noch nicht auf Betriebstemperatur befindet. Somit kann auch auf der Druckseite Kondensat anfallen, so dass auch diese Bereiche aus rostfreiem Stahl und Sondermaterialen hergestellt werden müssen. Der Einsatz von rostfreiem Stahl und Sondermaterialien führt jedoch zwangsläufig zu sehr hohen Herstellungskosten.This remaining condensate can collect in depressions and, depending on the suction-side pressure, can come into contact with the sealing arrangement for the rotor shafts. It is therefore necessary to manufacture these parts from stainless steel and to use special materials in this area. Condensate remains in the liquid state even in those operating phases in which the housing is not yet at operating temperature. This means that condensate can also accumulate on the pressure side, so that these areas must also be made of stainless steel and special materials. However, the use of stainless steel and special materials inevitably leads to very high manufacturing costs.

Um ein Durchschlagen von Kondensat auf die Ölseite des Verdichters zu vermeiden, müssen bei Verdichterkonstruktionen der erwähnten Art darüber hinaus die Dichtanordnungen für die Wellenlager relativ aufwendig gestaltet werden. So müssen Unter-oder Überdruckluftsperren vorgesehen werden, was einen nicht unerheblichen zusätzlichen Aufwand sowie den Einsatz von Fremdenergie erfordert.In order to prevent condensate from bleeding through on the oil side of the compressor, the sealing arrangements for the shaft bearings must also be designed to be relatively complex in the case of compressor designs of the type mentioned. Vacuum or overpressure air barriers must be provided, which requires a not inconsiderable additional effort and the use of external energy.

Von Nachteil ist ferner, dass das im Bereich des Einlasses eingespritzte Kondensat entsprechend der verdampfenden Menge den volumetrischen Wirkungsgrad beeinflussen kann, was ebenfalls unerwünscht ist.Another disadvantage is that the condensate injected in the area of the inlet can influence the volumetric efficiency in accordance with the evaporating amount, which is also undesirable.

Aufgabe der vorliegenden Erfindung ist es, eine Verfahrensweise zum Kühlen eines Schraubenverdichters sowie einen Schraubenverdichter zur Durchführung des Verfahrens zu schaffen, bei der bzw. bei dem auf den Einsatz von rostfreiem Stahl und Sondermaterialien bei der Herstellung zugunsten billiger Materialien verzichtet werden kann und aufwendige Dichtanordnungen für die Rotorenwellen und die Wellenlager nicht erforderlich sind.The object of the present invention is to provide a procedure for cooling a screw compressor and a screw compressor for carrying out the method, in which or in which the use of stainless steel and special materials in the manufacture can be dispensed with in favor of cheap materials, and complex sealing arrangements for the rotor shafts and the shaft bearings are not required.

Diese Aufgabe wird erfindungsgemäss durch eine Verfahrensweise gelöst, bei der das Kondensat nach Abschluss des Verdichtungsraumes gegenüber dem Einlass des Verdichters in den Verdichtungsraum eingespeist und in Förderrichtung des Verdichters stromabwärts von Einspeisstelle Frischwasser in den Verdichtungsraum eingespeist wird, wobei die Kondensat- und die Frischwassereinspeisung in Abhängigkeit der Temperatur des Fördermediums in der Auslassleitung unabhängig voneinander gesteuert werden.This object is achieved according to the invention by a procedure in which the condensate is fed into the compression chamber opposite the inlet of the compressor after the compression chamber has been closed and fresh water is fed into the compression chamber downstream of the feed point, the condensate and fresh water feeds being dependent on this the temperature of the medium in the outlet line can be controlled independently.

Durch die erfindungsgemässen Merkmale ist eine Verfahrensweise geschaffen, bei der der Kühlwassereinspritzvorgang erstmalig in allen Betriebsphasen abgestuft und präzise in Abhängigkeit der Temperatur des Fördermediums gesteuert vorgenommen wird, so dass im Verdichter ausschliesslich überhitzter Dampf anfällt. Dadurch kann weder auf der Saugnoch auf der Druckseite Kondensat anfallen, so dass der Einsatz von rostfreiem Stahl oder Sondermaterialien in diesen Bereichen nicht erforderlich ist und billigere Materialien vorgesehen werden können.The features according to the invention create a procedure in which the cooling water injection process is graded for the first time in all operating phases and is carried out precisely and in a controlled manner depending on the temperature of the conveyed medium, so that only superheated steam is produced in the compressor. As a result, condensate can neither accumulate on the suction side nor on the pressure side, so that the use of stainless steel or special materials in these areas is not necessary and cheaper materials can be provided.

Auch können aufwendig gestaltete Dichtanordnungen entfallen, da mangels Kondensatanfall ein Durchschlagen nicht eintreten kann. Darüber hinaus erfolgt mangels Kondensatanfall im Einlass keine Beeinflussung des volumetrischen Wirkungsgrades.Elaborately designed sealing arrangements can also be dispensed with, since, due to the lack of condensate, strikethrough cannot occur. In addition, due to a lack of condensate in the inlet, there is no influence on the volumetric efficiency.

Aufgrund der erfindungsgemässen Verfahrensweise kann das Einsatzgebiet von 1 stufigen «trockenen» Schraubenverdichtern in Bereiche erweitert werden, für die bisher nur öleingespritzte oder zweistufige trockene Verdichter eingesetzt werden konnten. Gegenüber Verdichtern mit Öl einspritzung wird erfindungsgemäss somit der Betriebsstoff Öl eingespart. Auch ist der nicht unerhebliche Aufwand für Ölfilteranordnungen nicht erforderlich, da das verdichtete Arbeitsmedium keine Ölanteile mehr enthält. Mangels Öleinsatz sind auch die Umweltbedingungen besser und keine Brand- bzw. Explosionsgefahr gegeben.Due to the procedure according to the invention, the field of application of 1-stage “dry” screw compressors can be expanded into areas for which previously only oil-injected or two-stage dry compressors could be used. Compared to compressors with oil injection, oil is thus saved according to the invention. The not inconsiderable effort for oil filter arrangements is also not necessary, since the compressed working medium no longer contains any oil components. If oil is not used, the environmental conditions are better and there is no risk of fire or explosion.

Grundsätzlich kann die Steuerung der Kondensat-und der Frischwassereinspeisung in Abhängigkeit der Temperatur des Fördermediums in der Auslassleitung in der für die jeweiligen Betriebsbedingungen günstigsten Weise gesteuert werden. Eine besonders einfache und betriebssichere Steuerung wird jedoch erreicht, wenn die Kondensateinspeisung bei Erreichen eines ersten niedrigen Temperaturwertes und die Frischwassereinspeisung bei Erreichen eines zweiten höheren Temperaturwertes erfolgt und jeweils bei Unterschreiten der Temperaturwerte die Einspeisung wieder unterbrochen wird. Bei einer derartigen bevorzugten Verfahrensweise wird das Kondensat erst dann in den Verdichtungsraum eingespritzt, wenn das verdichtete Medium am Ende des Verdichtungsprozesses eine bestimmte Temperatur erreicht hat. Fällt die Temperatur aufgrund der Kondensateinspritzung wieder unter den vorgegebenen Temperaturwert, so wird die Kondensateinspritzung wieder unterbrochen, so dass die Temperatur wieder ansteigen kann. Steigt die Temperatur des Fördermediums dagegen trotz Kondensateinspritzung weiter an, so wird bei Erreichen des zweiten höheren Temperaturwertes Frischwasser in den Verdichtungsraum eingespritzt und damit eine zusätzliche Kühlung des Fördermediums hervorgerufen. Fällt aufgrund der Frischwassereinspritzung die Temperatur wieder unter den zweiten höheren Temperaturwert ab, so wird die Frischwassereinspeisung wieder unterbrochen. Bei einem erneuten Temperaturanstieg über den zweiten höheren Temperaturwert hinaus wird dann erneut Frischwasser in den Verdichtungsraum eingespeist.In principle, the control of the condensate and fresh water feed can be controlled as a function of the temperature of the conveyed medium in the outlet line in the most favorable manner for the respective operating conditions. A particularly simple and reliable control is achieved, however, when the condensate feed occurs when a first low temperature value is reached and the fresh water feed occurs when a second higher temperature value is reached and the feed is interrupted again when the temperature values are fallen below. In such a preferred procedure, the condensate is only injected into the compression chamber when the compressed medium has reached a certain temperature at the end of the compression process. If the temperature falls below the predetermined temperature value due to the condensate injection, the condensate injection is interrupted again so that the temperature can rise again. In contrast, the temperature of the pumped medium increases white despite the condensate injection ter on, fresh water is injected into the compression chamber when the second higher temperature value is reached, thus causing additional cooling of the pumped medium. If the temperature drops again below the second higher temperature value due to the fresh water injection, the fresh water feed is interrupted again. When the temperature rises again above the second higher temperature value, fresh water is then fed into the compression chamber again.

Bei einem erfindungsgemässen Schraubenverdichter zur Durchführung des Verfahrens wird das Kondensat über eine erste Zuführleitung und das Frischwasser über eine zweite Zuführleitung in den Verdichtungsraum eingespeist. Diese Zuführleitung ist erfindungsgemäss jeweils mit einem Ventil ausgestattet, wobei die Ventile von einem in der Auslassleitung des Verdichters angeordneten Temperaturschalter gesteuert werden. Eine derartige Anordnung ist einfach im Aufbau, wartungsarm und betriebssicher.In a screw compressor according to the invention for carrying out the method, the condensate is fed into the compression space via a first feed line and the fresh water via a second feed line. According to the invention, this feed line is in each case equipped with a valve, the valves being controlled by a temperature switch arranged in the outlet line of the compressor. Such an arrangement is simple in construction, requires little maintenance and is reliable.

Bei einem bevorzugten Ausführungsbeispiel eines erfindungsgemässen Schraubenverdichters werden die Ventile von einem auf zwei einstellbare Temperaturwerte ansprechenden Temperaturschalter gesteuert. Dieser Temperaturschalter öffnet bei Erreichen des ersten niedrigeren Temperaturwertes das Ventil für die Kondensatzuführleitung und bei Erreichen des zweiten höheren Temperaturwertes das Ventil für die Frischwasserzuführleitung. Ferner schliesst dieser Temperaturschalter die jeweiligen Ventile wieder, sobald die Temperatur unter den jeweiligen Temperaturwert absinkt.In a preferred embodiment of a screw compressor according to the invention, the valves are controlled by a temperature switch which responds to two adjustable temperature values. This temperature switch opens the valve for the condensate supply line when the first lower temperature value is reached and the valve for the fresh water supply line when the second higher temperature value is reached. Furthermore, this temperature switch closes the respective valves as soon as the temperature drops below the respective temperature value.

Grundsätzlich können die Ventile in jeder beliebigen Weise ausgebildet sein. Vorteilhaft ist es jedoch, wenn die Ventile als Magnetventile oder als Wassermengenregler ausgebildet sind.Basically, the valves can be designed in any manner. However, it is advantageous if the valves are designed as solenoid valves or as water flow regulators.

Bei einem bevorzugten Ausführungsbeispiel ist in der Auslassleitung in Strömungsrichtung gesehen stromaufwärts von dem Kondensatabscheider ein Kühler vorgesehen. Zweckmässigerweise ist bei einer derartigen Anordnung der Temperaturschalter in der Auslassleitung in Strömungsrichtung gesehen stromaufwärts von dem Kühler angeordnet.In a preferred exemplary embodiment, a cooler is provided in the outlet line, as seen in the flow direction, upstream of the condensate separator. With such an arrangement, the temperature switch in the outlet line is expediently arranged upstream of the cooler, as seen in the flow direction.

Aufgrund der Einspeisung von Frischwasser und der sofortigen Verdampfung beim Einspeisvorgang findet im Verdichtungsraum des Verdichters ein Kalkausfall statt. Die dabei entstehenden Kalkpartikelchen lagern sich auf den Rotoren und der Wandung des Arbeitsraumes ab. Da dieser Vorgang nur während des Betriebes abläuft, kann sich die Kalkschicht nur solange aufbauen, bis das sogenannte Nullspiel und damit ein maximal möglicher Dichtungseffekt und Wirkungsgrad erreicht ist. Ein weiterer Aufbau der Kalkschicht wird durch das Aneinandervorbeigleiten der Rotoren verhindert.Due to the feed of fresh water and the immediate evaporation during the feed process, a lime precipitate takes place in the compression chamber of the compressor. The resulting lime particles are deposited on the rotors and the wall of the work area. Since this process only takes place during operation, the limestone layer can only build up until the so-called zero backlash and thus the maximum possible sealing effect and efficiency is achieved. A further build-up of the lime layer is prevented by the rotors sliding past each other.

Während des oben beschriebenen Vorganges ist keine Steigerung der Antriebsleistung für den Verdichter zu beobachten, da die Kalkschicht sehr weich ist. Ein Aushärten der Kalkschicht findet erst nach dem Abstellen des Verdichters und dem Abkühlen statt. Dabei können die Rotoren derart fest miteinander verbunden werden, dass ein erneutes Anfahren des Verdichters nicht möglich ist.During the process described above, no increase in the drive power for the compressor can be observed, since the lime layer is very soft. The lime layer cures only after the compressor has been switched off and has cooled down. The rotors can be firmly connected to one another in such a way that the compressor cannot be restarted.

Die erfindungsgemässe Verfahrensweise ermöglicht es nun, diesen grundsätzlich positiven Effekt des Nullspieles auszunützen, ohne dabei den Nachteil des Aushärtens mit den daraus resultierenden Folgen in Kauf nehmen zu müssen. So kann aufgrund des erfindungsgemässen Verhahrens unaufbereitetes Frischwasser nur solange eingespeist werden, bis sich die Kalkschichten nicht grossflächig berühren und nach dem Abstellen und Abkühlen ein neuer Start möglich ist. Von diesem Zeitpunkt wird dann nur mehr aufbereitetes Frischwasser eingespeist, so dass ein weiterer Aufbau der Kalkschicht nicht erfolgt. Die Dauer der Frischwasserzufuhr mit Kalkausfall kann durch Versuche ermittelt werden.The procedure according to the invention now makes it possible to exploit this fundamentally positive effect of the zero play without having to accept the disadvantage of curing with the resulting consequences. Thus, due to the inventive method, untreated fresh water can only be fed in until the layers of lime do not touch each other over a large area and a new start is possible after switching off and cooling. From this point in time, only treated fresh water is fed in, so that the limestone layer does not build up further. The duration of the fresh water supply with lime precipitation can be determined by tests.

Die Beschichtung von Rotoren von Schraubenverdichtem ist grundsätzlich bereits bekannt. So werden Rotoren von Schraubenverdichtern beispielsweise mit Kunststoff beschichtet und durch eine derartige Beschichtung ebenfalls ein optimaler Dichteffekt und Wirkungsgrad erreicht. Kunststoffbeschichtungen haben jedoch den Nachteil, dass bei Ablösungserscheinungen die Verdichter demoniert und zerlegt werden müssen. Kalkbeschichtete Rotoren können dagegen im eingebauten Zustand ohne Demontage nachgebessert werden. Hierzu ist es lediglich erforderlich, gezielt unaufbereitetes Frischwasser einzuspeisen, um die abgelösten Bereiche nachzubessern.The coating of rotors of screw compressors is basically already known. Rotors of screw compressors are coated with plastic, for example, and such a coating also achieves an optimal sealing effect and efficiency. Plastic coatings, however, have the disadvantage that the compressors have to be dismantled and dismantled in the event of signs of separation. Lime-coated rotors, on the other hand, can be reworked in the installed state without dismantling. To do this, it is only necessary to selectively supply untreated fresh water in order to touch up the detached areas.

Im folgenden ist zur weiteren Erläuterung und zum besseren Verständnis schematisch ein Ausführungsbeispiel eines nach dem erfindungsgemässen Verfahren arbeitenden Schraubenverdichters unter Bezugnahme auf die beigefügte Zeichunung näher beschrieben.In the following, an embodiment of a screw compressor working according to the method according to the invention is schematically described in more detail with reference to the attached drawing for further explanation and for better understanding.

Die Zeichnung zeigt einen mit einem Schraubenrippenrotor und einem Schraubennutenrotor ausgestatteten Schraubenverdichter 1, der einen Einlass 2 und einen Auslass 3 aufweist. Der Auslass 3 mündet in eine Auslassleitung 4, in der ein herkömmlicher Kühler 5 angeordnet ist. An den Kühler 5 schliesst sich ein Kondensatabscheider 6 an, der ebenfalls bekannter Bauart ist.The drawing shows a screw compressor 1 equipped with a screw rib rotor and a screw groove rotor, which has an inlet 2 and an outlet 3. The outlet 3 opens into an outlet line 4 in which a conventional cooler 5 is arranged. A condensate separator 6, which is also of a known type, is connected to the cooler 5.

Der Kondensatabscheider 6 ist mit einer ersten Zuführleitung 7 ausgestattet, über die das im Kondensatabscheider gewonnene Kondensat zum Verdichter zurückgeführt wird. Die erste Zuführleitung 7 ist mit einem Ventil 8 ausgestattet, mit dem die Einspeisung des Kondensats in den Verdichtungsraum des Verdichters gesteuert werden kann. Die Einspeisung des Kondensats in den Verdichtungsraum erfolgt an einer Stelle, an der der Verdichtungsraum gegenüber dem Einlass des Verdichters bereits abgeschlossen ist.The condensate separator 6 is equipped with a first feed line 7, via which the condensate obtained in the condensate separator is returned to the compressor. The first feed line 7 is equipped with a valve 8 with which the feed of the condensate into the compression space of the compressor can be controlled. The condensate is fed into the compression chamber at a point at which the compression chamber is already closed off from the inlet of the compressor.

Über eine zweite Zuführleitung 9, die mit einem Ventil 10 ausgestattet ist, kann Frischwasser in den Verdichtungsraum des Verdichters eingespeist werden. Die Einspeisstelle für das Frischwasser in den Verdichtungsraum ist dabei derart angeordnet, dass sie in Förderrichtung des Verdichters stromabwärts von der Einspeisstelle für das Kondensat liegt.Fresh water can be fed into the compression chamber of the compressor via a second feed line 9, which is equipped with a valve 10. The feed point for the fresh water into the compression chamber is arranged in such a way that it is downstream of the feed point for the condensate in the direction of conveyance of the compressor.

In der Auslassleitung 4 ist zwischen dem Auslass 3 und dem Kühler 5 ein Temperaturschalter 11 angeordnet. Dieser Temperaturschalter 11 besitzt im vorliegenden Ausführungsbeispiel zwei einstellbare Temperaturwerte Ti und T2. Über den Temperaturschalter 11 werden die Ventile 8 und 10, die im vorliegenden Ausführungsbeispiel als Magnetventile ausgestaltet sind, gesteuert.A temperature switch 11 is arranged in the outlet line 4 between the outlet 3 and the cooler 5. In the present exemplary embodiment, this temperature switch 11 has two adjustable temperature values T i and T 2 . About the temperature switches 11, the valves 8 and 10, which are designed as solenoid valves in the present exemplary embodiment, are controlled.

Die Steuerung ist dabei wie folgt gestaltet:The control is designed as follows:

Bei einer Temperatur des Fördermediums im Auslass 3, die unter den Temperturwerten T, und T2 liegt, ist sowohl das Ventil 8 als auch das Ventil 10 geschlossen. Steigt nun die Temperatur auf den Temperaturwert Ti an, so wird über den Temperaturschalter 11 das Ventil 8 für das Kondensat geöffnet. Erreicht die Temperatur den Temperaturwert T2, so wird zusätzlich das Ventil 10 für das Frischwasser geöffnet. Bei einem Absinken der Temperatur unter den Temperaturwert T2 schliesst der Temperaturschalter 11 das Ventil 10 wieder. Sinkt die Temperatur dann unter den Temperaturwert T, ab, so wird über den Temperaturschalter 11 auch das Ventil 8 geschlossen.Both the valve 8 and the valve 10 are closed at a temperature of the delivery medium in the outlet 3 which is below the temperature values T 1 and T 2 . If the temperature now rises to the temperature value T i , the valve 8 for the condensate is opened via the temperature switch 11. When the temperature reaches the temperature value T 2 , the valve 10 for the fresh water is additionally opened. When the temperature drops below the temperature value T 2, the temperature switch 11 closes the valve 10 again. If the temperature then drops below the temperature value T 1, the valve 8 is also closed via the temperature switch 11.

Wird der Temperaturwert Ti beispielsweise auf 200°C und der Temperaturwert T2 beispielsweise auf 220°C eingestellt, so ergibt sich beim Verdichten von Luft folgende Arbeitsweise:If the temperature value T i is set, for example, to 200 ° C and the temperature value T 2, for example to 220 ° C, the following procedure results when compressing air:

Wird der Schraubenverdichter 1 angefahren, so hat die komprimierte Luft im Auslass 3 zu Beginn eine Temperatur, die unter 200°C liegt. Das Ventil 8 für das Kondensat und das Ventil 10 für das Frischwasser sind deshalb in dieser Phase geschlossen. Ist der Anfahrvorgang abgeschlossen und wird der Betrieb mit dem Verdichter aufgenommen, so erhöht sich die Temperatur der kompromierten Luft im Auslass 3 langsam. Sobald die Temperatur der Luft im Auslass 3 200°C erreicht hat, öffnet der Temperaturschalter 11 das Ventil 8. Da zu diesem Zeitpunkt noch kein Kondensat vorliegt, wird die Temperatur der Luft im Auslass 3 weiter ansteigen. Sobald sie den Temperaturwert 220° erreicht hat, öffnet das Ventil 10, so dass Frischwasser in den Verdichtungsraum eingespeist werden kann. Dadurch sinkt die Temperatur der Luft im Auslass 3 wieder ab. Hat die Temperatur 220°C unterschritten, schliesst das Ventil 10 wieder, so dass die Frischwasserzufuhr unterbrochen wird. Dieser Vorgang wiederholt sich so oft, bis im Kondensatabscheider 6 ausreichend Kondensat angefallen ist, das über die erste Zuführleitung 7 und das Ventil 8 in den Verdichtungsraum eingespeist werden kann. Sinkt nun die Temperatur im Auslass 3 aufgrund der Kondensateinspeisung unter 220°C ab, so wird zuerst das Ventil 2 geschlossen und damit die Frischwassereinspeisung in dem Verdichtungsraum unterbrochen. Sinkt die Temperatur weiter unter 200°C ab, so wird auch das Ventil 8 geschlossen, so dass weder Kondensat noch Frischwasser in den Verdichtungsraum eingespeist wird.When the screw compressor 1 is started up, the compressed air in the outlet 3 initially has a temperature which is below 200 ° C. The valve 8 for the condensate and the valve 10 for the fresh water are therefore closed in this phase. When the start-up process is complete and operation with the compressor is started, the temperature of the compressed air in outlet 3 slowly increases. As soon as the temperature of the air in the outlet 3 has reached 200 ° C., the temperature switch 11 opens the valve 8. Since there is no condensate at this point in time, the temperature of the air in the outlet 3 will continue to rise. As soon as it has reached the temperature value of 220 °, the valve 10 opens so that fresh water can be fed into the compression chamber. As a result, the temperature of the air in outlet 3 drops again. If the temperature has dropped below 220 ° C., the valve 10 closes again, so that the fresh water supply is interrupted. This process is repeated until sufficient condensate has accumulated in the condensate separator 6, which can be fed into the compression space via the first feed line 7 and the valve 8. If the temperature in outlet 3 drops below 220 ° C due to the condensate feed, valve 2 is first closed and thus the fresh water feed in the compression chamber is interrupted. If the temperature drops further below 200 ° C, the valve 8 is also closed, so that neither condensate nor fresh water is fed into the compression chamber.

Aufgrund der oben beschriebenen Verfahrensweise fällt im Verdichter ausschliesslich überhitzter Dampf an, so dass sich weder einlass- noch auslassseitig Flüssigkeit ansammeln kann. Der Einsatz von rostfreiem Stahl oder Sondermaterialien in diesen Bereichen ist daher nicht erforderlich, so dass billigere Materialien verwendet werden können, die die Herstellungskosten erheblich reduzieren. Auch können aufwendig gestaltete Dichtanordnungen entfallen, da mangels Kondensatanfall ein Durchschlagen nicht eintreten kann. Mangels Kondensatanfall im Einlass findet auch keine Beeinflussung des volumetrischen Wirkungsgrades statt.Due to the procedure described above, only superheated steam is produced in the compressor, so that liquid cannot accumulate on either the inlet or outlet side. The use of stainless steel or special materials in these areas is therefore not necessary, so that cheaper materials can be used, which significantly reduce the manufacturing costs. Elaborately designed sealing arrangements can also be dispensed with, since, due to the lack of condensate, strikethrough cannot occur. In the absence of condensate in the inlet, there is no influence on the volumetric efficiency.

Claims (8)

1. Method for cooling a screw compressor having a helical rib rotor and a helical groove rotor in mating engagement therewith, condensate being introduced into a compession chamber formed by the rotors and the wall of the working chamber surrounding the rotors, which condensate is recovered in a separator connected to the outlet side, characterised in that the condensate is introduced into the compression chamber after closure of the compression chamber against the inlet of the compressor and fresh water is introduced into the compression chamber downstream of the inlet position considered in the feed direction of the compressor, and in that the introduction of condensate and fresh water are controlled mutually independently in dependence upon the temperature of the feed medium in the outlet conduit.
2. Method according to claim 1 characterised in that the introduction takes place upon reaching a first lower temperature value and the introduction of fresh water takes place upon reaching a second higher temperature value and in each case is interrupted when the temperature falls again below this temperature value.
3. Screw compressor for carrying out the method of claim 1 characterised in that the condensate is introduced via a first conduit (7) and the fresh water is introduced via a second feed conduit (9) into the compression chamber and each feed conduit (7 or 9) is provided with a respective valve (8 or 10), the valves (8 or 10) being controlled by a temperature switch (11) arranged in the outlet conduit (4).
4. Screw compressor according to claim 3 for carrying out the method to claim 2 characterised in that the valve (8 or 10) are controlled by a temperature switch (11) responsive to two settable temperature values (Ti and T2), which switch opens the valve (8) for the first feed conduit (7) for the condensate when the first lower temperature value (Ti) is reached and opens the valve (10) for the second feed conduit (9) for the fresh water when the second higher temperature value (T2) is reached, and closes the respective valves (8 or 10) again when the temperature falls below the respective temperature value (T, or T2).
5. Screw compressor according to claim 3 or 4 characterised in that the valves (8 or 10) are solenoid valves.
6. Screw compressor according to claim 3 or 4 characterised in that the valves (8 or 10) are water flow regulators.
7. Screw compressor according to claim 3 or 4 characterised in thatthe a cooler (5) is provided in the outlet conduit (4) upstream of the condensate separator (6) considered in the flow direction.
8. Screw compressor according to claim 3 or 4 and 7 characterised in that the temperature switch (11) is arranged in the outlet conduit (4) upstream of the cooler (5) considered in the flow direction.
EP85109194A 1984-07-23 1985-07-23 Cooling method for a screw compressor, and a screw compressor for carrying out this method Expired EP0172430B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19843427117 DE3427117A1 (en) 1984-07-23 1984-07-23 METHOD FOR COOLING A SCREW COMPRESSOR AND SCREW COMPRESSOR FOR CARRYING OUT THE METHOD
DE3427117 1984-07-23

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EP0172430A1 EP0172430A1 (en) 1986-02-26
EP0172430B1 true EP0172430B1 (en) 1988-04-20

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EP85109194A Expired EP0172430B1 (en) 1984-07-23 1985-07-23 Cooling method for a screw compressor, and a screw compressor for carrying out this method

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EP (1) EP0172430B1 (en)
DE (2) DE3427117A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4207189A1 (en) * 1991-04-12 1992-10-15 Kobe Steel Ltd OIL-FREE SCREW COMPRESSOR WITH LIQUID INJECTION
DE3903067C3 (en) * 1989-02-02 2000-02-10 Guenter Kirsten Process for producing a rotor for rotary piston machines, and rotor manufactured using the process
SG85187A1 (en) * 1999-06-09 2001-12-19 Sterling Fluid Sys Gmbh Rotary piston compressor with an axial direction of delivery

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Publication number Priority date Publication date Assignee Title
BE1011062A3 (en) * 1997-03-25 1999-04-06 Atlas Copco Airpower Nv A blow-off COMPRESSOR UNIT AND THUS USED moisture separator.
DE20015744U1 (en) 2000-09-12 2001-01-25 Rietschle Werner Gmbh & Co Kg Pump with water feed
DE10151176B4 (en) * 2001-10-12 2008-02-28 Renner, Bernt Compressor system with at least one water-injected screw compressor for compressing gas
BE1018075A3 (en) * 2008-03-31 2010-04-06 Atlas Copco Airpower Nv METHOD FOR COOLING A LIQUID-INJECTION COMPRESSOR ELEMENT AND LIQUID-INJECTION COMPRESSOR ELEMENT FOR USING SUCH METHOD.
JP5248373B2 (en) 2009-03-11 2013-07-31 株式会社日立産機システム Water jet air compressor
WO2013049221A1 (en) 2011-09-26 2013-04-04 Ingersoll Rand Company Water cooled screw compressor

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Publication number Priority date Publication date Assignee Title
US3535057A (en) * 1968-09-06 1970-10-20 Esper Kodra Screw compressor
US3795117A (en) * 1972-09-01 1974-03-05 Dunham Bush Inc Injection cooling of screw compressors
GB1548663A (en) * 1975-06-24 1979-07-18 Maekawa Seisakusho Kk Refrigerating apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3903067C3 (en) * 1989-02-02 2000-02-10 Guenter Kirsten Process for producing a rotor for rotary piston machines, and rotor manufactured using the process
DE4207189A1 (en) * 1991-04-12 1992-10-15 Kobe Steel Ltd OIL-FREE SCREW COMPRESSOR WITH LIQUID INJECTION
SG85187A1 (en) * 1999-06-09 2001-12-19 Sterling Fluid Sys Gmbh Rotary piston compressor with an axial direction of delivery

Also Published As

Publication number Publication date
DE3562291D1 (en) 1988-05-26
EP0172430A1 (en) 1986-02-26
DE3427117A1 (en) 1986-02-20

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