DE2520464A1 - METHOD AND DEVICE FOR OPERATING AN OIL-FLOODED REFRIGERANT COMPRESSOR - Google Patents

Description

LINDE AKTIENGESELLSCHAFT

(S 378 / S 379) S 75/34

De / fl May 6, 1975

Method and device for operating an oil-flooded refrigerant compressor

The invention relates to a method and a method direction for operating an oil-flooded refrigerant compressor.

! ' Such methods and devices are known.

A method for operating refrigerant compressors, in particular refrigerant compressors of the type ^! the screw compressor, in which a control slide is arranged on the pressure side of the Kälte-ι Mittelverdlchters, introduced in particular-I rem measure. However, a strong reduction in the "Kiumenstrom" ■ through the control slide causes at the same time a

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[ disadvantageous reduction of the compression ratio, so ·

that the efficiency drops sharply with small volume flows. In addition, the control slide is manufactured very precisely required, as they are guided with close play to the high-speed rotors of the refrigerant compressor got to. That makes the compressor correspondingly expensive.

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I.
The invention is based on the object of providing a

h drive and a device for operating a refrigerant compressor to find that allows a simple and inexpensive manufacture of the refrigerant compressor.

According to the invention, this object is achieved in that oil is transferred from a collecting container via a cooling oil line Refrigerant compressor is supplied and that at the same time with the closing of the suction line in the refrigerant circuit Flow of the oil in the KUhlölleitung is throttled.

The switching devices can be arranged separately and only connected to the refrigerant compressor via lines are and do not need to have rotating parts. This measure according to the invention also prevents that the refrigerant compressor is overheated, even if it works against the full final pressure when the suction line is closed. The invention also applies when switching to partial load operation

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Ί a sudden drop in pressure in the collecting tank is avoided, 1 Do not foam half of the refrigerant and oil. The inventive

| i process simplifies and therefore facilitates operation

I; of refrigerant compressors for gases strongly soluble in oil, ins-Ij special for refrigerants, essential.

i To increase the efficiency when operating the

Refrigerant compressor in partial load operation and for expansion

_: i its control range towards lower partial load ranges,

j it is advantageous if, at the same time as the closing

j! ßen the suction line in the refrigerant circuit, a relief line from the pressure line in the refrigerant circuit to the >; container is opened.

Because at least for the duration, during! ' ^: the suction line is closed in the refrigerant circuit, ι oil and optionally refrigerant from the collecting tank into the

! Pressure line is promoted in the refrigerant circuit , a

'' Flooding of the collecting tank can also be ruled out under unfavorable operating conditions.

A method according to the invention for operating an oil compressor can be provided with a device in which the device for closing the suction line in the refrigerant circuit and the device for throttling the flow of the oil

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can be operated jointly in the cooling oil line and to a switching element are summarized, carried out in a particularly simple manner will.

A refrigerant compressor can then easily be used without a great deal of additional work in terms of lines and switching devices be relieved of pressure in that the switching element has a device for opening the relief device.

When arranging at least two refrigerant compressors connected in parallel or with at least two Compressor stages of a refrigerant compressor connected in parallel can operate these particularly advantageously and the use of an additional pump for pumping oil and, if necessary, refrigerants from the collecting tank can be saved in the pressure line in the refrigerant circuit,! if every refrigerant compressor or every compressor stage j each has its own cooling oil line if the refrigerant ; Compressors or the compressor stages a common or at least interconnected collecting tank are assigned if at least one of the refrigerant compressor or the compressor stages has a relief line to Pressure relief of the pressure line and a switching element with a device for closing the suction line in the refrigerant circuit.

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i with a device ^z ^ ^m throttling the flow of the; V.ls in

ι the Kuhlölleitung and with a device to open the 1 has a discharge line and if the other refrigerants: compressors or compressor stages each have a switching element

Have a device for closing the suction line in the refrigerant circuit and with a device for throttling the flow of the oil in the cooling oil line.

; The fact that between the suction line in the refrigeration

center circle on and the. Collector a line with a check valve that is permeable in the direction of the oil collector is arranged, impurities can penetrate through

Ij the necessary sealing elements of the bread roll container as a result a too high negative pressure in the collecting tank should be avoided.

The invention is explained in more detail below using the exemplary embodiments shown schematically in the drawings explained.

IEs show

1 according to a method according to the invention

operated refrigerant compressor in load operation Figure 2 the same according to an inventive

Process operated refrigerant compressor in partial load operation.

LINDE AKTIENGESELLSCHAFT

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3 two parallel-connected, according to a device according to the invention Method-operated refrigerant compressor in load operation and FIG. 4 shows two parallel-connected, according to an inventive Process-operated refrigerant compressors in partial load operation

FIG. 1 shows an oil-flooded refrigerant compressor 1 operated according to a method according to the invention in load operation. The refrigerant compressor 1 can be a screw compressor or a rotary piston compressor of another type. The refrigerant compressor 1 sucks in refrigerant via suction line 2, compresses it and presses it via pressure line 3 through the check valve 4, which is permeable in this direction, into pressure line 5 of the refrigerant circuit. The refrigerant, which is mixed with oil in this area, reaches the oil separator 6 from the pressure line 5. In the oil separator 6, the refrigerant is separated from the oil and fed into the refrigerant circuit. The separated oil is fed into an oil pressure vessel 7 in the direction of the arrow drawn. Oil is conveyed from the oil pressure tank 7 by means of a pump 8, via a cooler (not shown) and via lines 9 to the lubrication points in accordance with the directions shown.

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directs and injected there. The oil is used to lubricate and cool the refrigerant compressor 1, the pump 12 and I ^{1 of} the bearings. In the refrigerant compressor, the oil is mixed with the refrigerant and, as described, returns to the pressure vessel 7. The pump ο can be omitted if the pressure in the pressure vessel 7 is sufficiently high anyway.

Some of the oil is accumulated in the collecting container 10. The refrigerant compressor rushes oil through line 11 ; in the direction shown from the nurse container 10. :; The oil sucked in by refrigerant compressor 1 aige mixes

! with the refrigerant and with it reaches the pressure line J5 ■ of the refrigerant circuit. The oil is separated out again in the oil separator 6 and returned to the pressure vessel 7. A ] ' pump 12 constantly conveys oil and, if necessary, refrigerant; Via line 13 from your collecting container 10 into the pressure line ;; 5 of the refrigerant circuit. So that no unfavorably low pressures can develop in the collecting ^{container 10, a line 15 leads from L of} the suction line 2 to the collecting container 10, which can be shut off by a check valve 14 which is permeable in this direction. Relief line ΐβ, cooling oil line I'll and suction line 2 v / ground in their flow cross-sections

Controlled by the switching element 17.

LINDE AKTIENGESELLSCHAFT

The switching element 17 contains a relief valve as a facility Io open and close the discharge line, a throttle valve as a device 19 for throttling the cooling oil flow in the cooling oil line 11 and a suction valve as a device 20 for opening and closing the suction line in the refrigerant circuit. Relief valve l8, throttle valve 19 and suction valve 20 are arranged together on a push rod 21 within a cylindrical housing 22 so that they can be operated together and at the same time. Tn the one Endstellunp; the push rod 21 is the relief line l6 closed, the cooling oil line 11 and the suction line 22 completely open and in the other end position the relief line 16 is open, the cooling oil line 11 is throttled and the suction line 2 closed. In order to be able to actuate the switching element pneumatically or hydraulically, at least one section is required of the housing 22 designed as a cylinder 23 and the push rod at at least one point within the cylinder 23 with a piston 24 is provided. A compression spring 25 presses the push rod towards the end position at which the suction line is closed. By introducing a print medium into the cylinder 23 is the push rod towards the end position, at

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! ' that the relief line is closed, printed. Sin at-

: · For example oiek '-. Risch scnaltlm-ve three-way valve 2c regulates

Il the feeding of the print medium. The Drue lorn- · Ir i _: r _s -μ -: - ar.-m ZyIU >> r Pj ^- - in Jon Γamne! ?: ¹ 10

j. .-; iec; er i: .a ⁱ "ijkfl: .o3sn and üie I ^ uokVraft of the compression spring? 5 can

! then an oc-keeper. the .T-aurleitur · ^ 2 causes α. As rruei-. ^. E-

μ dium can serve as the pressure vessel 7 conveyed. V But there are also other types of actuation of the push rod

possible. If the refrigerant compressor is working under load, so j is the suction line 2 in the refrigerant circuit and the cooling

| j line τ ι open and the relief line 16 closed.

'; rioi LasT.bel.ri '·)) ir,': the · ^{T. r} olune: i; 3tr-on des P'ältemittel-

j. v ^ rdlohLer:.; 1 uri άζΐ \ V .- '' ur-RVüS ^ rom of P. ~ ipe 12, also called

'! I "äi;.emit; plr :, ^v rdio; itt-ir work k'üm, increased, .yei Toillast-

·, Bstrio ".-.!: Jibi; eo pr-aki. ^ Sr · '- koir. ^ N Volumcr-stroni des Kältenittelver - 3.ioir:.« Rö, v / älir ^ nd dr ¹ : - pump 12 aunn then still works.

;, With partial load operation of the refrigerant compressor, the

! · Is shown in Figure 2, the three - ". Ve ge valve 26 has reversed

i ' ¹ switches. The piston 24 is consumed by the pressure of the pressure medium

i is loaded and the pressure medium, in the present case the oil, flows

_; in lines 27 and 2-r, according to the arrow

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direction back into the collecting container 10. The compression spring 25 switches the switching element 17 so that the suction valve 20 is now closed. The throttle valve 19 simultaneously throttles the passage of oil in the cooling oil line 11. This prevents the refrigerant compressor, after the suction valve is closed, from suddenly sucking in an increased amount of oil via the cooling oil line 11 from the collecting container 10. Because of the sudden drop in pressure in the collecting container 10, the easily soluble gases contained in the oil, in particular the refrigerant, would escape again in gaseous form and cause the oil to foam heavily. The foaming of the oil leads to disruptions in the compressor operation. The throttling of the cooling oil flow, however, prevents a sudden drop in pressure in the collecting container 10, which is why the foaming of the oil can be prevented in the method according to the invention. The relief valve 18 is now also open and the pressure line j $ can via the relief line 16 in the direction of Ί

arrows drawn into the collecting container 10 are depressurized. This also continues via KUhlölleitung 11 and line Oil that gets into the refrigerant compressor, which otherwise gets into the oil separator 6 immediately, goes because of the closed Check valve 4 via relief line 16 in the collection

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:, container 10 and leads to an increase in the oil level there. ! In order to prevent the collecting container 10 from being flooded and the oil pressure container 7 from being emptied, the pump pumps

! ' 12 oil and, if necessary, refrigerant after reaching a certain

¹ correct liquid level in the collecting tank 10 via line !! 13 in the pressure line 5 in the refrigerant circuit. From there

; ^! it is pressed into the oil separator 6 and then fed back into the oil pressure tank 7.

il Since the volume flow of the pump 12 is only a very low

M is a fraction of the volume flow of the refrigerant compressor,

j, the possibly self-priming pump 12 can be small. i: Depending on the operating conditions of the refrigerant compressor

I, the delivery rate of the pump 12 must be so great that a pressure

j | rise in the collecting container 10 beyond an optimal value

cannot take place. So that it goes through if the suction is too great! the pump 12 does not lead to an undesirably low pressure in the Sam- ■ Mel container 10 comes, can via line 15 and check valve

j l4 pressure equalization between suction line 2 and the collector

j container 10 are made so that in the collecting container 10 and

j; in the suction line 2 always depending on the check valve

;! 14 there is approximately the same pressure. The pressure difference can be determined by the resistance of the check valve 14

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will. In partial load operation, the pressure in the collecting container 10 is slightly below the suction pressure in the suction line 2, while the pressure in the collecting container 10 is slightly above the suction pressure in the suction line 2 during load operation.

The refrigerant compressor 1 and the pump 12

are driven by a motor 29 *, for example an electric motor, and driven by a transmission gear arranged in the collecting container 10.

In the case of two or more refrigerant compressors or compressor stages connected in parallel, the pump 12 can be omitted. For this purpose, a common collection container or several collection containers that are connected to one another must be available. One of the refrigerant compressors or the compressor stages then takes on the task of the pump. This requires that the refrigerant compressor justified by additional devices or by its design _t also can promote oil. The screw compressor, for example, has this property due to its design, so that it is particularly suitable for it.

In Figure 3, two parallel-connected refrigerant compressors 30, 31f ^ ie also compressor stages working in parallel of a refrigerant compressor during load operation

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-Οι shown. A pressure prevails in the collecting container 32 which corresponds approximately to the pressure in the suction line 33 or, due to the greater resistance of the check valve 34, is lower than the pressure Pressure in the suction line can be ^. The refrigeration medium compressor 30 * 31 or the compressor stages are driven by the H

j electric motor 35 via a common gear transmission yG, whose!; Housing equilateral represents the collection container 32 which is sealed to the outside with the seal ¹ 37th The refrigerant

1 seal 30 conveys via the check valve 38 into the oil drain

; | Scheider 39 »while the refrigerant compressor y \ can work without a non-return valve. The arrows drawn in lines 33 and 53 indicate the direction of the refrigerant flow. From the oil separator 39, the separated oil is directed into Ij the oil pressure vessel 40, from where it is also fed back by its own overpressure or by an oil pump (not shown)

^I filter and oil cooler, not shown, in line 49 to the i

j Storage and compression rooms are conveyed and injected there.

π The refrigerant compressor 30 is equipped with a switching element 4l

II equipped, in addition to the relief valve 42 and suction valve 43 is provided with the throttle valve 44. The refrigerant compressor 31 has a switching element 46 which has only one suction valve 48

! and a throttle valve 47 is open. The switching elements 4l and 46

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are actuated hydraulically or pneumatically by the piston 45 or 59. In the example shown, the oil pressure from line 49 is used for this purpose. Two three-way valves 50 and 51 switch first the refrigerant compressor 30, then the refrigerant compressor 31, to partial load operation, independently of the required output.

If both refrigerant compressors are working at full load, the switching elements 4l, 46 are switched so that the suction valves 43, 48 and the throttle valves 44, 47 are fully open. For this purpose, the cylinders of the switching elements 4l must be connected to the pressure medium via the two three-way valves 50, 51 . In this case, passes through line 49 and 60 Druckme dium to the switching element 46 and via line 49 and 6l pressure medium to the switching element 4l.

During load operation, as shown in FIG. 3, both suction valves 43 and 48 are open. The refrigerant compressors 30, 31 suck in refrigerant from the suction line 33, compress it and press it into the pressure lines 52 or 53 · at the same time The refrigerant compressors 30, 31 suck in via lines 55, 56 or 57 »58 oil originating from the bearing lubrication and, if necessary, refrigerant from the collecting tank 32 and press

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ii this also into the pressure lines 52 and 53. In the olabii separator, the refrigerant and the oil are separated again.

: j Daa refrigerant enters the refrigerant circuit while

ij that 31 is returned to the oil pressure tank.

·. '· The compressor 30

Il switched to partial load operation. This happens because

I ₁ the three-way valve 51 the line leading to the switching element 4l

i device 49 for the print medium and a line 62

Ij opens, through which the pressure medium leaves the switching element 4l in

Jj flows back through the collecting container 32. The other in the switching element 4l

.i orderly compression spring finally closes the suction

|! line 33, the throttling of the cooling oil line 55, 56 and the

nen the relief line 5 ^ · Because of the simultaneous closing of-Sens Säugventils 43 compresses the refrigerant compressor to only by a very low pressure in the suction line 33

j · the small final pressure that prevails in the collecting container 32,

Refrigerant from pressure line 52 through relief line 5 ^ j. into the collecting container 32 in the direction of the arrows shown

j | can relax. Throttle valve 44 closes the flow cross

i cut the cooling oil line 55, 56 except for a small cross • j cut, since in the cooling oil line 56 there is also a very low pressure as in the suction line 33. The through throttle valve

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44 throttled oil and possibly refrigerant amount compressed to the small pressure in pressure line 52 and arrives Via the relief line 54 back to the collecting container 32 return. This would be flooded with oil if the refrigerant compressor 31 did not get the oil via the cooling oil line 57, 58 and, if necessary, would suck off refrigerant and convey it into the pressure line 53. This also applies to the refrigerant compressor 30 originating oil from the refrigerant compressor 31 over the oil separator 39 is returned to the oil pressure tank 40, from where it is again fed to both refrigerant compressors via line 49 for bearing lubrication and cooling.

If an even smaller volume flow is required from the refrigerant compressor, the three-way valve 50 also switches the refrigerant compressor 31 in the same way as the refrigerant compressor 30 to partial load operation. This state is represented by FIG. Both suction valves 43 and 48 are closed. The refrigerant compressor 30 is, as previously described, relieved of pressure by relief valve 42 and only consumes a fraction of its power during load operation. The refrigerant compressor 31 also no longer draws in refrigerant from the suction line 33. But it must be what is released from the oil Refrigerant from sump 32 together with the oil via the

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Suck in cooling oil lines 57 and 58 and into pressure line 53 pump so that the oil circuit is secured.

This cooling oil flow also out through the throttle valve 47 be rotseüt, otherwise in the collecting container 32 a the pressure is too low. The formation of a vacuum is particularly important in closed work processes, such as in the case of refrigerant

! deserved, not wanted, as in no case over the Ij
Seal 37 air or moisture should get into the refrigerant. As an additional security against excessive suction of the collecting tank 32 by the refrigerant compressor 3I, the check valve J> k is provided, with which pressures in the collecting tank 32 can be set that are lower than the pressure in the S -ug line 33 but still above a vacuum -

I'm reshaping lie.

j · Since the refrigerant vex 'densifier 3I is still

has to work against the full final pressure, its performance

j uptake i \\ xv by a small amount. Trotζden results

j compared to other methods of rubbing

jl refrigerant compressor :! an extremely cheap average ü Power consumption ..

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The arrows in Figures 1 to 4 each indicate the direction of the flowing fluids. The bold ones Arrows show the main direction of flow of the refrigerant and the arrows drawn in thin lines show the main directions of flow of the oil.

This method of operating refrigerant compressors is not restricted to use with a rotary lobe compressor limited with only two parallel compressor stages.

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Claims (1)

LINDE AKTIENGESELLSCHAFT t! (S 378 / S 579) De / fl ·· '. r-'ai 1075 Claims , '1. Procedure for operating an oil-flooded refrigerant Ii poet, characterized in that oil via a cooling oil j line (11) is fed from a collecting container (10) to the refrigerant and compressor (l) and that at the same time as I j the closing of the suction line (2) in the refrigerant circuit J! the flow of the oil in the cooling oil line (ll) is throttled |: will. 2. The method according to claim 1, characterized in that simultaneously with the closing of the suction line (2) in the refrigerant circuit, a relief line (16) from the pressure line (3) in the refrigerant circuit to the collecting container (10) is opened . Γ. π η ■ LINDE AKTIENGESELLSCHAFT 3. The method according to claim 1 or 2, characterized in that at least during the period during which the suction line (2) is closed in the refrigerant circuit, oil and optionally refrigerant from the collecting tank (10) in the pressure line (3) is conveyed in the refrigerant circuit. 4. Apparatus for performing the method according to one of the Claims 1 to 3 * characterized in that the device for closing the suction line (2) in the refrigerant circuit and the device for throttling the flow of the oil in the cooling oil line (ll) can be operated jointly and as one Switching element are summarized. 5. Apparatus according to claim 4, characterized in that the switching element (17) has a device for opening the relief line (l6). 6. Apparatus according to claim 4 and 5, with at least two parallel refrigerant compressors or with at least two parallel compressor stages of a refrigerant compressor, characterized in that each refrigerant compressor (30, 31) or each compressor stage one 6 η q r /, 7 / η /, 7 7 2 b 2 U 4 6 4 LINDE AKTIENGESELLSCHAFT - 21 - own KUhlölleitung (55,56 or 57,5B) that the refrigerant compressors (30 »31) or the Verdiohterstufe a common or at least interconnected collecting tank (32) are assigned ₇ that at least one of the refrigerant compressors (30) or the Compressor stages a relief line (54) for pressure relief of the pressure line (52) and a switching element (4l) with a device (43) for closing the suction line (33) in the refrigerant circuit, with a device (44) for throttling the flow of the oil in the cooling oil line (55, 5 ¹ ^) and with a device (42) for opening the relief line (54) and that the remaining refrigerant compressors (31) or compressor stages each have a switching element (46) with a device (48) for closing the suction line (33 ) in the refrigerant circuit and with a device (47) for throttling the flow of the oil in the cooling oil line (57, 58). 7. Apparatus according to claim 6, characterized in that between the suction line (33) in the refrigerant circuit and the Collection container (32) a line with one in the direction of the oil collection container permeable check valve (34) is arranged. 609847/0477