Dry compression compressor and method of oil separation for dry compression compressor

Abstract

The present invention relates to a dry compression or oil-free compressor for producing compressed gas and a method for oil separation for a dry compression compressor (1). The compressor has a compressor housing (4), a compression chamber (5), at least one oil chamber (19a, 19b) in which oil-lubricated bearings (18a, 18b) of a rotor bearing (16) are housed, and a shaft seal device (10a, 10b) arranged between the oil-lubricated bearings (18a, 18b) and the compression chamber (5). The shaft seal arrangement (10a, 10b) has an outer seal (17a, 17b) facing the oil-lubricated bearing (18a, 18b) and an inner seal (12a, 12b) facing the compression chamber (5), and at least one sealed gas chamber (13a, 13b, 13c, 13d) for receiving a sealing gas is formed between the outer seal (17a, 17b) and the inner seal (12a, 12b). The oil chamber (19a, 19b) has at least one gas inlet for a sealing gas flow from the sealed gas chamber (13a, 13b, 13c, 13d) and a gas outlet (26) for connection to an oil separator (30, 31, 32, 33). The oil chamber (19a, 19b) is connected to the compressor housing (4) at an ambient pressure p by an oil separation pressure difference Δp. 0 Oil chamber pressure p OR to provide.

Description

[Technical field]

[0001] The present invention relates to a dry-compression compressor for producing compressed gas, in particular compressed air, and to a method of oil separation for such a dry-compression compressor. [Background technology]

[0002] Dry compression or oil-free compressors are primarily used in applications where providing oil-free compressed process gas, especially oil-free compressed air, is important, such as in the food or pharmaceutical industry. Unlike oil-lubricated or oil-injected compressors, dry compression compressors do not allow oil to enter the compression chamber or the compressed gas produced. However, oil lubrication is often provided for the shaft bearing of the compressor rotor.

[0003] Due to the high rotational speed of the compressor rotor, high peripheral speeds of the shaft occur at the shaft seal. For this reason, non-contact seals are typically used. Non-contact seals, of course, have a certain amount of leakage. In addition to the undesirable loss of the gas to be compressed from the compression chamber, it is also desirable to seal against the ingress of oil (or grease particles in the case of grease lubrication of the bearings) from the bearing area into the compression chamber, in order to prevent contamination of the gas to be compressed.

[0004] Dry-compression compressors in which sealing air is used for sealing are known from FR 2 569 780 A1, EP 0 674 751 A1 and EP 1 975 410 A1.

[0005] Dry-compression compressors known from the prior art have several drawbacks.

[0006] If the compressor is allowed to operate in idle mode, the intake throttling by the inlet valve in the compression chamber may create a vacuum on the intake side, so that gas contaminated with oil and / or grease may be drawn into the compression chamber through the (leaking) shaft seal. In addition, impurities from the environment may be sucked through the drain openings present in the shaft seal, which may reach the process gas or compressed air and damage the shaft seal. During load operation, the pressure gradient may cause leakage flows to enter the environment through the drain openings or lanterns in the shaft seal, which may contain contaminants from lubricants such as oil or grease.

[0007] Due to the inherent leakage of the shaft seal, the leakage gas flow can reach the area of ​​the oil-lubricated bearing, and the gas or air leaking from the shaft seal is contaminated with oil. In many dry compression compressors, this oil-air mixture (oil smoke) enters the environment through openings in the compressor housing and contaminates it with oil. In addition, the leaking oil aerosol can flow into the intake area of ​​the compressor, thus impairing the quality of the compressed air produced. The pressure level in the bearing area of ​​these compressors is the ambient pressure level.

[0008] The oil smoke extraction systems sometimes used are complex and prone to failure. If oil separators are used in the prior art to clean the outgoing polluted air, they have to use additional energy to reduce the pressure level on the outlet side of the oil separator, for example via an ejector nozzle (vacuum suction nozzle) operated with compressed air or via an electrically driven suction system. The ejector nozzle can also result in a reduction in the amount of compressed air supplied and, if clogged with impurities, can lead to malfunctions in the operation of the compressor.

[0009] A rotary piston machine having a centrifugal separator for creating a vacuum in the oil chamber is known from EP 1 447 566 A1.

[0010] An oil-free compressor having a suction pump in the form of an ejector is known from EP 0 719 910 A1. Summary of the Invention

[0011] Based on this prior art, the present invention has the objective, on the one hand, of providing a high quality compressed gas, in particular compressed air, in particular for different operating conditions of the compressor, and, on the other hand, of avoiding the contamination of the environment with lubricants, in particular oils. In particular, it is the aim to achieve the most complete, simple and energy-efficient possible cleaning of the air flow emerging from the shaft seal and contaminated by the bearing lubrication.

[0012] This object is in each case solved by a dry-compression compressor according to claim 1 or 3 and by a method according to claim 23.

[0013] In particular, the object is solved by a dry-compression compressor for generating compressed gas, in particular for generating compressed air, having one or more compressor stages, which dry-compression compressor comprises: a compressor housing; at least one compressor rotor rotatably mounted relative to the compressor housing via a rotor bearing; Wherein the compressor housing comprises: a compression chamber for compressing the gas drawn in by the compressor rotor; at least one oil chamber in which at least one oil-lubricated bearing of a rotor bearing for mounting a shaft section of the compressor rotor is accommodated; Equipped with a shaft sealing device, assigned to the shaft section, arranged between the oil-lubricated bearing and the compression chamber for sealing the compression chamber against the ingress of oil from the oil chamber; The shaft seal arrangement has an outer seal facing the oil-lubricated bearing, in particular without contact, and an inner seal facing the compression chamber, in particular without contact, a sealed gas chamber for accommodating a sealing gas is formed between the outer seal and the inner seal, the oil chamber has at least one gas inlet for a sealing gas flow from the sealed gas chamber and a gas outlet for connection to an oil separator, in particular an oil smoke separator, and the oil chamber has an oil chamber pressure p0 which exceeds the ambient pressure p0 of the compressor housing by an oil separation pressure difference Δp. OR and the oil separation pressure difference Δp is preferably at least 20 mbar (2×10 3 Pa).

[0014] The invention is based on the idea of ​​creating an overpressure in the oil chamber compared to the environment by means of a sealed gas flow entering the oil chamber, which can be used for oil separation.

[0015] According to one idea of ​​the invention, it is preferably possible to omit reducing the pressure at the outlet side of the oil separator, but it is not excluded to additionally reduce the pressure level at the outlet side of the oil separator. The oil chamber pressure generated is preferably high enough to overcome a pressure difference, which can be called the oil separation pressure difference, to be overcome for the flow through the oil separator, in particular the oil smoke separator. The oil separation pressure difference Δp can be understood as the overpressure in the oil chamber compared to the pressure p0 around the compressor housing (ambient pressure of the compressor housing). In particular, if the compressed gas is a process gas (i.e. not air), the ambient pressure of the compressor housing can correspond to the intake pressure of the compressor, and the purified process gas flow is preferably injected back into the intake area of ​​the compressor. The oil separation pressure difference Δp is particularly large enough to overcome (at least) the pressure loss between the oil chamber and the outlet side of the oil separator, which comprises in particular the line pressure loss and the separation pressure difference to be overcome in the oil separator, for example the pressure difference through at least one filter medium and / or the flow pressure loss of the flow divider for oil separation. Oil chamber pressure p ORcan be understood as the sum of the compressor housing ambient pressure p0 and the oil separation pressure difference Δp (p OR =p0+Δp). A pressure level p0 of the ambient pressure of the compressor housing can be present on the pressure side of the oil separator. On the one hand, oil separation is simplified due to the elimination of the suction device on the outlet side of the oil separator. This can also save energy. On the other hand, oil separators with a higher degree of separation can be used, which usually require a higher pressure difference for flow (increased pressure loss). This allows a more complete cleaning of the escaping gas.

[0016] The oil separation pressure difference Δp is preferably greater than 20 mbar, more preferably greater than 50 mbar, more preferably greater than 100 mbar, more preferably greater than 150 mbar, more preferably about 200 mbar. The oil separation pressure difference Δp may be 20 mbar to 1000 mbar (1 bar), preferably 50 mbar to 500 mbar, more preferably 100 mbar to 300 mbar, more preferably 150 mbar to 250 mbar. Preferably, the oil separation pressure difference Δp is in the range of 150 mbar to 200 mbar, particularly preferably about 170 mbar.

[0017] The values ​​for the oil separation pressure difference Δp refer in particular to the steady (run-in) state of the oil separator. For example, the value of the oil separation pressure difference in the new condition of the oil separator (filter) (e.g. 20 mbar), for example over the first few hours of operation, may be significantly lower than the value in steady operation (e.g. 170 mbar) after, for example, more than 1000 hours of operation.

[0018] From the prior art it is known that manufacturers of compressor housings specify the maximum allowable overpressure that the shaft seal of the compressor housing can be subjected to at about 2 mbar. A typical seal with a delivery thread for the shaft passage in the compressor housing is designed for example for a pressure difference of up to about 0.5 mbar (5 mm water column). The oil chamber pressure p0 above the ambient pressure p0 of the compressor housing by the oil separation pressure difference Δp ORThe oil chamber according to the invention, which provides: clearly moves away from such known solutions.

[0019] Due to the oil separation pressure difference Δp of at least 20 mbar, compared to the prior art, oil separators with higher separation efficiency, preferably finer (better) filters, can be used, in particular without pressure reduction on the outlet side of the oil separator.

[0020] The oil chamber has an overpressure compared to the ambient pressure of the compressor housing and has a gas outlet for connection to an oil separator, thus preventing the gas-oil mixture from leaking (uncontrolled) into the environment. On the one hand, this prevents contamination of the environment with oil, and on the other hand, prevents oil aerosols from being sucked in by the compressor. This in turn improves the quality of the compressed gas in terms of its purity.

[0021] In particular, the oil chamber is designed to be airtight to the environment (except for gas outflow to the oil separator and leakage in the seals), and the sealing gas flow (or leakage gas flow) entering the oil chamber can prevent gas from exiting the oil chamber through the shaft seal arrangement (against the pressure difference that creates the sealing gas flow). In particular, the oil chamber is designed to build and maintain the oil chamber pressure and is therefore airtight to the environment. The gas to be compressed can be a process gas such as argon or nitrogen, or air, in particular ambient air.

[0022] The ambient pressure p0 of the compressor housing can be understood as the pressure present at the gas outlet downstream of the oil separator, where the oil-separated gas stream (i.e. the cleaned gas stream) leaves in the environment of the compressor housing. The ambient pressure of the compressor housing is usually the atmospheric ambient air pressure. However, the ambient pressure of the compressor housing can deviate from the atmospheric ambient pressure, for example, if the compressor is operated in a closed room with different ambient pressure levels (negative or positive pressure compared to the atmosphere). In particular when compressing a process gas and returning the cleaned process gas stream to the intake area of ​​the compressor, the ambient pressure of the compressor housing can also correspond to the intake pressure of the compressor. When compressing a process gas, the ambient pressure p0 of the compressor housing is independent of the atmospheric ambient pressure and can in particular be lower or higher than the atmospheric ambient pressure, and the oil chamber pressure p OR is set depending inter alia on the compressor intake pressure and the oil separation pressure difference Δp. The ambient pressure may depend on the altitude at which the compressor is operated. For example, as an approximation for standard conditions, 1 bar (1×10 5 At an ambient pressure p0 of 100 Pa, an oil separation pressure difference Δp of at least 20 mbar corresponds to at least 2% of the ambient pressure p0. OR would therefore be at least 1.02 bar (1020 mbar) in such a case. A preferred oil separation pressure difference Δp in the range of 200 mbar would correspond to an oil separation pressure difference Δp of about 20% at an ambient pressure p0 of 1 bar.

[0023] The sealed gas chamber can be understood as an intermediate space of the shaft seal arrangement, in particular the space between the external and internal shaft seals. The sealed gas flow can result from leakage in the shaft seal arrangement. The sealed gas flow can comprise or consist of the sealing gas supplied to the shaft seal arrangement, but can also comprise the compressed gas or the gas to be compressed leaking out of the compression chamber as a leakage gas flow, in particular due to possible mixing in the sealed gas chamber. The sealed gas flow of the sealed gas chamber can therefore result from different sources, in particular leakage from the (internal) shaft seal of the associated shaft seal arrangement, leakage from other shaft seal arrangements, for example on the other side (pressure side or suction side) of the compressor, leakage from shaft seal arrangements of further compressor stages or leakage from the sealing gas injected into the sealed gas chamber. In particular, the internal shaft seal has the task of sealing the compression chamber against ingress of gas (for example during vacuum operation in idling mode) and against egress of gas (during overpressure operation at load operation).

[0024] An oil-lubricated bearing can also be understood as a grease-lubricated bearing, or an oil-and-grease-lubricated bearing. This applies at least as far as the grease used for the bearing lubrication can be considered as oil mixed with a binder. In particular, oil smoke, which is a mixture of oil (or grease) leaking from the oil-lubricated bearing and gas flowing into the oil chamber, is formed in the oil chamber. The oil chamber can also be called an oil smoke chamber. The oil smoke is preferably created at high rotational and peripheral speeds, which can exceed 100 m / s, and the oil droplets are finely atomized upon impact. The floating oil droplets can be carried by the gas flow and form oil smoke in the oil chamber.

[0025] A contactless seal can be understood as a seal whose sealing elements (sealing surfaces) do not require contact for sealing purposes, but are preferably based on a flow-induced sealing effect. A contactless seal in particular has a (narrow) sealing gap, which of course allows a certain amount of leakage. However, even in a contactless seal there may be a (slight) contact between the sealing elements, for example between the (metallic) internal sealing surface and the (coated) circumferential surface of the rotor shaft to be sealed. However, contactless seals typically exhibit sealing gaps during operation, preferably after running-in, at least in partial areas, depending for example on the deflection of the shaft to be sealed, on the thermal expansion and on the wear of the coating (of the seal and / or of the shaft), which allows leakage flows.

[0026] The several compressor stages may have a common compressor housing or separate compressor housings.

[0027] In particular, the gas outlet of the oil chamber is connected to at least one oil separator, in particular a smoke separator. The oil separator can comprise several similar or different separation stages, in particular a pre-separator and / or a fine separator and / or a residual oil separator. Several oil separators, preferably fine separators, can be connected in series. The oil separator (smoke separator) preferably comprises (at least) one coalescing filter. The gas outlet can be fluidly connected to the oil separator (directly or indirectly), for example, via a cavity in the compressor housing or via one or more connecting lines.

[0028] In addition, the object is in particular solved by a dry-compression compressor for generating compressed gas, in particular for generating compressed air, having one or more compressor stages, which dry-compression compressor comprises: a compressor housing; at least one compressor rotor rotatably mounted relative to the compressor housing via a rotor bearing; Wherein the compressor housing comprises: a compression chamber for compressing the gas drawn in by the compressor rotor; at least one oil chamber in which at least one oil-lubricated bearing of a rotor bearing for mounting a shaft section of the compressor rotor is accommodated; Equipped with a shaft sealing device, which is arranged between the oil-lubricated bearing and the compression chamber for sealing the compression chamber against the ingress of oil from the oil chamber, and which has a seal, in particular a contactless seal, assigned to the shaft section; The oil chamber has at least one gas inlet for the leakage gas flow from the shaft seal device and a gas outlet connected to at least one oil separator, in particular an oil smoke separator, and the oil chamber has an oil chamber pressure p0 which exceeds the ambient pressure p0 of the compressor housing by an oil separation pressure difference Δp. OR and the oil separation pressure difference Δp is preferably at least 20 mbar.

[0029] This alternative form of the invention is based on the idea of ​​creating an overpressure in the oil chamber compared to the environment by a leakage gas flow entering the oil chamber, which can be used for oil separation. Reference is made to the previous description of the invention and its effects and advantages, which apply equally to this alternative form of the invention. The leakage gas flow comprises compressed gas or gas to be compressed that leaves the compression chamber and enters the oil chamber, in particular due to leakage of the shaft seal device.

[0030] In one embodiment of this alternative, the seal is an outer seal facing the oil-lubricated bearing, in particular without contact, the shaft seal arrangement also has an inner seal facing the compression chamber, in particular without contact, a sealed gas chamber for receiving a sealing gas is formed between the outer seal and the inner seal, and the leakage gas flow from the shaft seal arrangement is in particular a sealing gas flow from the sealed gas chamber. In this respect, reference is made to the previous explanations of the invention in relation to the sealed gas chamber or the sealing gas flow, which apply analogously to this embodiment.

[0031] In a preferred embodiment, the gas inflow of the oil chamber is formed by at least one sealing gap of a seal, in particular an external seal. The seal may have several sealing gaps, preferably arranged one behind the other in the axial direction. The sealing gap is generated in particular by a contactless seal and preferably extends in the circumferential direction of the shaft section of the compressor rotor. In particular, the sealing gap allows an (unhindered) flow of the sealing gas flow through the external seal of the shaft seal arrangement and / or a flow of leakage gas flow through the shaft seal arrangement (as a whole), which may originate from the sealed gas chamber or the compression chamber.

[0032] In a further embodiment, the compressor has an oil chamber pressure p OR The oil chamber pressure p is provided with at least one pressure sensor for detecting the oil chamber pressure. Different oil chamber pressures may be present in the different oil chambers, which are detected by pressure sensors assigned to the oil chambers. The pressure sensor can detect the oil chamber pressure in the oil chamber (directly) or detect the oil chamber pressure in a gas volume connected to the oil chamber (indirectly). Preferably, the pressure sensor can detect the pressure in a line section in which (essentially) the same pressure is present as the oil chamber pressure, for example in a connection line to an oil separator downstream of the gas outlet of the oil chamber. The oil chamber pressure p OR Detecting enables the oil separation pressure difference Δp to be determined.

[0033] In a further embodiment, the oil separator, in particular the oil smoke separator, comprises several separation stages, in particular at least one pre-separator and / or at least one fine separator and / or at least one residue separator. The oil separator can also comprise several similar separation stages (only), in particular several fine separators (only). In particular several fine separators can be connected in series. The fine separator preferably comprises a coalescing filter, and several (similar) coalescing filters can be connected in series. For example, the oil separation pressure difference Δp for two coalescing filters connected in series, each with a separation pressure difference of 200 mbar, can total 400 mbar. The pre-separator preferably comprises a demister and / or a wire mesh and / or a cyclone separator and / or a flow deflector, in particular with a baffle. The residue separator preferably comprises an adsorption filter. Several separation stages can increase the purity of the (purified) gas stream leaking into the environment or reduce the pollution of the environment. A knitted wire mesh or a demister can form the first separation stage, which separates in particular the coarser oil droplets and preferably generates only low pressure losses. A coalescing filter can form the second separation stage, which separates in particular the (fine) oil smoke and generates a pressure loss of, for example, 100 mbar to 300 mbar. An adsorption filter, preferably an activated carbon absorber, can form the third separation stage, which in particular absorbs any remaining residual oil and / or oil vapors. In comparison with the coalescing filter, the adsorption filter can also filter or combine oil vapors. The adsorption filter can be used in particular as the last separation stage of a multi-stage separation to achieve a particularly good cleaning of the compressed gas (e.g. air) for the best possible reduction of environmental pollution.

[0034] In a preferred embodiment, the sealing gas flow and / or the leakage gas flow are air flows, and an air outlet downstream of the oil separator leads to the free environment of the compressor. In particular, the compressed gas (leakage gas or leakage gas flow) and the sealing gas (sealing gas flow) are air. As a result, an oil-cleaned mixture of leakage air and sealing air flows out into the environment (atmosphere).

[0035] In a further embodiment, the compressor comprises an oil return line for returning the oil separated in the oil separator back into the oil chamber, an oil pump being preferably arranged in the oil return line. The oil pump is preferably designed as a peristaltic pump or a vibrating diaphragm pump. To generate a return pressure, the oil return line can have a height difference between a higher position of the oil separator and a lower position of the oil inlet into the oil chamber. Alternatively or additionally, an oil recovery container, in particular an oil sump, can be provided, which can be connected to the oil chamber in particular via a gas discharge line or is arranged therein, preferably integrated into the compressor housing. The oil return line creates a closed oil circuit, which in particular allows a low-maintenance (continuous) operation of the compressor.

[0036] In a further embodiment, the compressor generates an oil chamber pressure p OR The blow-off valve may be arranged in a blow-off opening in the housing wall of the oil chamber and is preferably designed as a pressure relief valve or a (currentless opening) solenoid valve. The blow-off valve may have a relief function for venting the oil chamber, for example in case of overpressure or in case of a fault, such as a power failure. This can ensure that the desired direction of the pressure gradient (from inside to outside) from the compression chamber to the oil chamber can always be maintained to ensure that oil cannot enter the sealed gas chamber. This prevents contamination of the compressed air even in case of a fault.

[0037] In a further embodiment, the rotor bearing comprises an oil-lubricated suction-side bearing and an oil-lubricated pressure-side bearing, each of which rotatably supports a shaft section of the compressor rotor relative to a compressor housing, the compressor housing having a suction-side oil chamber in which the oil-lubricated suction-side bearing is accommodated and a pressure-side oil chamber in which the oil-lubricated pressure-side bearing is accommodated, the suction-side oil chamber and the pressure-side oil chamber being connected to each other, in particular via a connecting line. In particular, a respective shaft seal device is provided in each case for the suction-side bearing and the pressure-side bearing, which is preferably arranged between the respective oil-lubricated bearing and the compression chamber to seal the compression chamber against the ingress of oil from the respective oil chamber, and has a respective, in particular non-contacting, seal, in particular an outer seal, in particular a non-contacting outer seal, facing the respective oil-lubricated bearing, and a respective inner seal, in particular a non-contacting inner seal, facing the compression chamber. The connecting line can extend (partially) inside and / or (partially) outside the housing, in particular as a through-flow passage in the compressor housing. The connection of both oil chambers is in particular provided for a uniform oil chamber pressure p in both oil chambers. OR and both oil chambers are preferably connected to a common oil separator. Alternatively, the suction side oil chamber and the pressure side oil chamber can be separated from each other, preferably with one oil separator connected to each chamber.

[0038] In a further embodiment, the rotor bearing comprises an oil-lubricated suction side bearing and an oil-lubricated pressure side bearing, each of which rotatably supports a shaft section of the compressor rotor relative to the compressor housing, a suction side shaft seal arrangement is provided for the suction side bearing and a pressure side shaft seal arrangement is provided for the pressure side bearing, the suction side sealing gas chamber of the suction side shaft seal arrangement and the pressure side sealing gas chamber of the pressure side shaft seal arrangement being connected to each other via a sealing gas connection line. In particular, the suction side shaft seal arrangement has an external suction side seal facing the oil-lubricated bearing, in particular without contact, and an internal suction side seal facing the compression chamber, in particular without contact, and a suction side sealing gas chamber for receiving a sealing gas is formed between the external suction side seal and the internal suction side seal. In particular, the pressure side shaft seal arrangement has an external pressure side seal facing the oil-lubricated bearing, in particular a non-contact external pressure side seal, and an internal pressure side seal facing the compression chamber, in particular a non-contact internal pressure side seal, and a pressure side sealing gas chamber for receiving a sealing gas is formed between the external pressure side seal and the internal pressure side seal. The sealing gas connection lines can extend (partially) inside and / or (partially) outside the housing, in particular as through passages or bores in the compressor housing. The sealing gas chambers of the different compressor stages can be connected to each other via one or more sealing gas connection line(s). The sealing gas connection lines between the different sealing gas chambers allow the sealing gas to be injected from the sealing gas chamber of higher pressure to the sealing gas chamber of lower pressure. For example, the higher the pressure in the compression chamber, the higher the leakage flow at the shaft seal on the pressure side and therefore the sealing gas flow is usually higher than at the shaft seal on the suction side. Similarly, a higher leakage flow typically occurs at the shaft seal of the (second) high pressure compressor stage than at the shaft seal of the (first) low pressure compressor stage. The sealing gas connection lines allow to supply the other sealing chambers according to the resulting pressure drop. This means that a sufficiently high sealing gas chamber pressure can be provided under certain conditions to reliably seal the assigned shaft section in the sealing gas chamber, preferably without the supply (replenishment) of sealing gas.

[0039] In a further embodiment, the shaft seal arrangement additionally has an intermediate seal, in particular a non-contact intermediate seal, between the external seal and the internal seal, an external sealed gas chamber for receiving a sealing gas is formed between the external seal and the intermediate seal, and an internal sealed gas chamber for receiving a sealing gas is formed between the intermediate seal and the internal seal. The suction side and the pressure side internal sealed gas chambers can be connected to each other via a (first) sealed gas connection line. The suction side and the pressure side external sealed gas chambers can be connected to each other via a (second) sealed gas connection line. Different sealed gas chamber pressures can be present and in particular can be set in the internal and external sealed gas chambers. The sealed gas chamber pressure of the internal sealed gas chamber is preferably lower than the sealed gas chamber pressure of the external sealed gas chamber (p SGR A shaft seal device having two (or more) sealing gas chambers arranged one behind the other in the axial direction can increase the sealing effect of the shaft seal device.

[0040] In a further embodiment, the compressor has a seal gas supply, whereby a seal gas chamber pressure p in at least one seal gas chamber is SGRis variably adjustable, preferably adjustable, the sealing gas supply in particular comprising a preferably adjustable sealing gas supply valve. In particular, the sealing gas supply comprises a sealing gas input and / or a sealing gas supply line connected to at least one sealed gas chamber. The sealing gas supply valve may be a purely mechanical valve, a two-point solenoid valve (open / close) or a continuously adjustable valve, such as a proportional valve or a pressure reducing valve, or a combination of several valves. The sealing gas connection line may be part of the sealing gas supply line. The sealing gas supply line may be connected to the sealing gas connection line. The sealing gas input may comprise an external sealing gas supply, such as a compressed air network or a separate compressor (e.g. a piston compressor), or an internal sealing gas supply, such as a branched compressed gas, a return from the pressure side to the suction side within a compressor stage, or a return from the (second) high pressure compressor stage to the (first) low pressure compressor stage. By injecting sealing gas into the sealed gas chamber as required, a sufficiently high sealing gas chamber pressure p SGR It is possible to ensure that the sealed gas chamber pressure p SGR is preferably (always) equal to the oil chamber pressure p OR This allows it to react to varying pressure conditions resulting from different operating conditions within the compressor.

[0041] In a further embodiment, the compressor has at least one sealed gas buffer volume between the sealing gas input and the sealed gas chamber, the sealed gas buffer volume being preferably designed as a cavity in the compressor housing. The sealed gas buffer volume can also be formed as a cavity in a multi-part housing, for example (partly) in the compressor housing and / or (partly) in the gear housing of the compressor. The compressor housing and the gear housing are preferably manufactured as cast parts. However, the sealed gas buffer volume can also be designed as a gas pressure vessel. The volume of the sealed gas chamber can be made smaller by using (additional) sealed gas buffer volumes. The sealed gas buffer volume can ensure sufficient maintenance of the sealed gas chamber pressure during transient operating conditions of the compressor, for example during shutdown or sputtering of the compressor and / or venting of the oil chamber or in case of insufficient sealing gas input, for example at low system pressure. The sealed gas buffer volume preferably maintains the sealed gas chamber pressure p SGR The oil chamber pressure P OR This helps to improve the sealing effect of the shaft seal device and also helps to ensure that the oil chamber pressure p OR To establish or maintain a (continuous) gas flow (sealing gas flow) into the oil chamber.

[0042] In a further embodiment, the compressor is adapted to regulate the sealed gas chamber pressure p in particular in at least one sealed gas chamber and / or sealed gas buffer volume. SGR At least one pressure sensor is provided for detecting a sealed gas chamber pressure p SGR is typically (essentially) the same as the sealed gas chamber pressure in the sealed gas buffer volume. In particular, the pressure in the sealed gas buffer volume can be recorded and / or monitored instead of the pressure in the sealed gas chamber.

[0043] In a further embodiment, a control unit, preferably an electronic control unit, is provided, which controls the sealed gas chamber pressure pSGR and / or oil chamber pressure p OR and / or the sealed gas chamber pressure p SGR and oil chamber pressure p OR It is designed to monitor the pressure difference between the sealed gas chamber pressure p SGR and oil chamber pressure p OR can be detected via the pressure sensor described above, which is connected (wirelessly or wired) to a control unit. The control unit detects the sealed gas chamber pressure p SGR and oil chamber pressure p OR and may be designed to calculate the pressure difference between the sealed gas chamber pressure p and the sealed air supply and adjust at least one sealed gas supply valve of the sealed air supply based on the pressure difference. Alternatively (or additionally), the differential pressure may be recorded (measured) via a differential pressure transducer and transmitted to a control unit for adjusting the at least one sealed gas supply valve. The control unit may be located on the compressor or may be connected to the compressor via a transmitter / receiver unit, via a data link, in particular via a network. The sealed gas chamber pressure p SGR , oil chamber pressure p OR , and / or the differential pressure can be monitored at fixed or variable time intervals or continuously. The time curves can be stored in a memory unit. Monitoring the differential pressure can be used to monitor the sealed gas chamber pressure p, in particular by increasing the supply of sealed air. SGR be readjusted accordingly.

[0044] In a further embodiment, a control unit, preferably an electronic control unit, regulates the sealed gas chamber pressure p SGR is the oil chamber pressure p OR In particular, the sealed gas chamber pressure p in the sealed gas chamber due to different operating conditions of the compressor is SGR In a particularly preferred embodiment, the sealed gas chamber pressure p SGRPreferably, in all operating conditions of the compressor or over the entire operating time of the compressor, the following pressure gradient p0 <p OR <p SGR is set or adjusted so that a pressure is applied. Different sealed gas chamber pressures can be set in the different sealed gas chambers. In particular, if the shaft seal arrangement has two sealed gas chambers, the sealed gas chamber pressure in the inner sealed gas chamber is preferably set higher than in the outer sealed gas chamber. This ensures that the sealed gas flow always comes from the gas inlet in the direction of the oil chamber, i.e. from the sealed gas chamber, through the outer seal and from the outer seal into the oil chamber. This prevents contaminating gas (and oil) from flowing from the oil chamber through the shaft seal arrangement into the compression chamber.

[0045] In an alternative embodiment, the compressor has a sealed gas supply valve designed as a pressure reducing valve, which is arranged in particular in the sealed gas supply line to at least one sealed gas chamber. The (mechanical) pressure reducing valve can comprise a diaphragm. However, the pressure reducing valve can also be designed as an electromagnetic valve. In particular, the pressure reducing valve reduces the sealed gas chamber pressure p SGR , so as to provide a sufficiently high outlet pressure to regulate the sealed gas chamber pressure p SGR is the oil chamber pressure p OR In particular, the outlet pressure of the pressure reducing valve is greater than the (desired) oil chamber pressure p OR When using a (mechanical) pressure reducing valve, a complex (electronic) control system for an (electronically) controllable sealed gas supply valve is not necessary. In this respect, the pressure reducing valve is a cost-effective alternative, especially for the simpler, preferably single-stage design of a dry-compression compressor. However, the pressure reducing valve must be used when, for example, the compressor is operating under load and the required sealed gas chamber pressure p SGR This has the disadvantage that, if the leakage gas flow would in fact be large enough to provide a 100% suction, more sealing air may be provided than is actually required.

[0046] In one embodiment, at least one sealed gas chamber has a negative pressure safety device, which is preferably designed as a check valve that opens towards the sealed gas chamber. In particular, the negative pressure safety device comprises a valve that opens the respective sealed gas chamber, preferably towards the periphery of the compressor housing, when the pressure falls below a minimum pressure, preferably as soon as the pressure in the at least one sealed gas chamber is lower than the ambient pressure. An individual negative pressure safety device can be assigned to each sealed gas chamber. The negative pressure safety device can provide ambient pressure (atmospheric pressure) as a minimum pressure in the sealed gas chamber when the compressor starts without pressure or in case of a fault (power failure).

[0047] In one embodiment, the oil chambers of several compressor stages, in particular the oil chamber of the first compressor stage and the oil chamber of the second compressor stage, are preferably connected to each other via a common gear housing and / or via a connecting line. In particular, the suction side oil chamber of the first compressor stage is connected to the suction side oil chamber of the second compressor stage or the pressure side oil chamber of the first compressor stage is connected to the pressure side oil chamber of the second compressor stage via a common gear housing. The drive gearbox of the compressor rotor can be arranged (wholly or partly) in the gear housing.

[0048] In a further embodiment, the compressor has a plurality of compressor stages, and at least one sealed gas chamber of a first compressor stage, preferably operating at a lower first pressure level, is connected, preferably via a sealed gas connection line, to at least one sealed gas chamber of a second compressor stage, preferably operating at a higher second pressure level. The sealed gas chambers of the first and second compressor stages are connected to each other, in particular such that a leakage gas flow from the second compressor stage, preferably exiting from a pressure-side shaft seal device of the second compressor stage, can flow to at least one sealed gas chamber of the first compressor stage. In this way, the pressure gradient of the two-stage (or multi-stage) compressor is used to generate sealed air for the compressor stage with the lower pressure level. Since the volume of the leakage gas flow increases with the pressure level of the compressor stages, in particular in some compressor stages, depending on the operating conditions, preferably at least at load operation, sufficient sealing air is available to at least temporarily, i.e. for certain operating conditions, switch off the sealing gas supply and ensure the supply of sealing air for all compressor stages only by the leakage gas flow of the higher (highest) compressor stage(s).

[0049] Said object is also in particular solved by a method for oil separation for a dry-compression compressor according to the invention having one or more compressor stages (2, 3) for producing compressed gas, in particular for producing compressed air, in particular having an oil-lubricated rotor bearing of at least one compressor rotor of the compressor, said method comprising: - introducing a leakage gas flow, in particular a sealing gas flow, exiting from a shaft seal device assigned to a shaft section of the compressor rotor into an oil chamber of a compressor housing of the compressor, in which at least one oil-lubricated bearing of the oil-lubricated rotor bearing is accommodated; an oil chamber pressure p0 above the ambient pressure p0 of the compressor housing by an oil separation pressure difference Δp, which is preferably at least 20 mbar OR into an oil chamber; - injecting a gas stream from the oil chamber into an oil separator; Equipped with.

[0050] The method is based on the idea of ​​introducing a leakage gas stream into the oil chamber to create an overpressure in the oil chamber compared to the environment, which can be used for oil separation. The alternative or additional introduction of a sealing gas stream into the oil chamber can also generate or contribute to the overpressure in the oil chamber. In particular, the oil chamber pressure generated by the incoming leakage gas stream and / or sealing gas stream provides a sufficiently large pressure difference (oil separation pressure difference Δp) to allow the oil / gas stream entering the oil separator from the oil chamber to flow through the oil separator. In particular, a pressure reduction at the outlet side of the oil separator can be omitted. The method according to the invention has similar effects and advantages as those already described in connection with the dry compression compressor according to the invention. The method can implement some or all of the process engineering features described in connection with the dry compression compressor.

[0051] The supply of the gas flow from the oil chamber to the oil separator comprises in particular the application of the oil chamber pressure to the inlet side of the oil separator (essentially, i.e. with the exception of small dissipative pressure losses, for example in the connecting lines or through flow deflection). In particular, the method comprises a step for separating the oil from the gas flow in the oil separator. In particular, as a further method step, the cleaned gas flow is led away from the outlet side of the oil separator into the (free) environment of the compressor housing. In addition to the usual purpose of sealing the compression chamber against the gas outlet and the gas inlet, the shaft seal device is designed in particular to seal the compression chamber of the compressor against the oil inlet from the oil chamber and is preferably arranged between the oil-lubricated bearing and the compression chamber of the compressor housing.

[0052] One embodiment of the method comprises: - the oil chamber pressure p by at least one pressure sensor OR and / or - by means of at least one pressure sensor, in particular the sealed gas chamber pressure p in at least one sealed gas chamber of the shaft seal device and / or in the sealed gas buffer volume of the sealed gas supply SGRand / or - sealed gas chamber pressure p SGR , in particular the sealed gas chamber pressure p in at least one sealed gas chamber of the shaft seal device and / or in the sealed gas buffer volume of the sealed gas supply SGR and the oil chamber pressure p OR determining a differential pressure between wherein the shaft seal arrangement comprises an outer seal, in particular facing the oil-lubricated bearing, in particular without contact, and an inner seal, in particular facing the compression chamber, in particular without contact, and a sealing gas chamber is formed between the outer seal and the inner seal, in particular for receiving a sealing gas; and / or -The gas chamber pressure p sealed by the control unit SGR and / or oil chamber pressure p OR and / or the sealed gas chamber pressure p SGR and oil chamber pressure p OR monitoring the differential pressure between The present invention is provided with at least one of the following:

[0053] The differential pressure can be detected (measured) by a sensor, in particular a differential pressure transducer, or the oil chamber pressure p OR and the sealed gas chamber pressure p SGR It can be determined by calculation based on the following:

[0054] One embodiment of the method further comprises the step of increasing the sealed gas chamber pressure p SGR is the oil chamber pressure p OR In particular, depending on the operating conditions of the compressor, a sealing gas chamber pressure p in at least one sealing gas chamber of the shaft seal device is increased by supplying a sealing gas into the sealing gas chamber so that the sealing gas chamber pressure p SGR The sealed gas chamber pressure p SGRis adjusted in particular by adjusting a sealing gas supply valve of the sealing gas supply into the at least one sealed gas chamber. The sealing gas supply valve can be controlled by a control unit and can preferably be continuously variable. Alternatively, the sealed gas chamber pressure p SGR can be regulated via a (mechanical) pressure reducing valve. The seal gas can be supplied from the compressor's external seal gas supply or from its internal seal gas supply.

[0055] An embodiment of the method comprises as a further step measuring the sealed gas chamber pressure p in the sealed gas chamber while the compressor is operated at idle and / or during a transient operating condition of the compressor, preferably during a start-up or shut-down condition of the compressor and / or while the compressor is operated under load, in particular if the compressor is a single stage compressor. SGR is the oil chamber pressure p OR In particular, in a single stage compressor, the leakage gas flow generated is greater than the required sealed gas chamber pressure p SGR In some cases, the required sealed air volume may not be sufficient to provide sufficient sealing air volume to provide sufficient cooling, so a sealing gas supply (internal or external) is required even during loaded operation. However, in the case of two-stage or multi-stage compressors, a sealing gas supply may not be necessary, at least during loaded operation, due to the larger leakage airflow that occurs.

[0056] An embodiment of the method comprises injecting a leakage gas flow from at least one sealed gas chamber of a second compressor stage, preferably operating at a higher second pressure level, into at least one sealed gas chamber of a first compressor stage, preferably operating at a lower first pressure level, preferably via a sealed gas connection line connecting the sealed gas chambers, the leakage gas flow preferably flowing from a pressure-side shaft seal device of the second compressor stage into the pressure-side sealed gas chamber of the second compressor stage. In this way, the pressure drop of the two-stage (or multi-stage) compressor is used to generate sealed air for the compressor stage having the lower pressure level.

[0057] Exemplary embodiments of the invention are explained in more detail below with reference to the drawings. [Brief description of the drawings]

[0058] [Figure 1] FIG. 1 is a schematic diagram of a first embodiment of a dry-compression compressor according to the present invention; [Diagram 2] FIG. 2 shows a schematic diagram of a second embodiment of a dry-compression compressor according to the present invention having shaft seal devices on the suction side and on the pressure side, each having two sealed gas chambers. [Diagram 3] FIG. 4 is a schematic diagram of a third embodiment of a dry-compression compressor according to the present invention having an external sealed gas supply and a sealed gas buffer volume. [Figure 4] FIG. 13 is a schematic diagram of a fourth embodiment of a dry-compression compressor according to the present invention having two compressor stages; [Diagram 5] FIG. 1 shows a schematic diagram of a fifth embodiment of a dry-compression compressor according to the invention, having two compressor stages and several sealing gas pressures. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0059] In the following description of the invention, the same reference numbers are used for identical and identically acting elements.

[0060] Each of the embodiments of the present invention described below with reference to Figures 1-5 illustrates a different aspect of the present invention. The illustrated embodiments can be combined with each other, unless technically inconsistent. In particular, the individual described components or systems of the dry compression compressor according to the present invention, such as pressure sensors, oil separator design (multi-stage design, separator stage design), oil return, sealing gas supply and sealing gas input, negative pressure protection device, and especially the control unit and process control system, can be complemented in each embodiment, are interchangeable between the embodiments, and can be combined with each other, unless technically inconsistent. Unless otherwise indicated, the letter "a" following the reference number refers to the suction side 85 of the compressor 1, and the letter "b" refers to the pressure side 86 of the compressor 1. For example, 19a refers to the suction side oil chamber and 19b refers to the pressure side oil chamber.

[0061] 1 shows a (single stage) dry or oil-free compression compressor 1 with oil-lubricated bearings 18a, 18b in the compressor housing 4. The compressor 1 draws in air as the gas to be compressed via an air inlet 70 on the suction side 85, compresses the air and conveys the compressed air from the pressure side 86 via a compressed air outlet 76 to an application not shown, typically into a compressed air network of a consumer.

[0062] The bearings 18a, 18b of the rotor bearing 16 are lubricated with oil and are arranged in oil chambers 19a, 19b of the compressor housing 4, in which the lubricating oil mixes with the gas to form a gas-air mixture in the form of oil smoke with aerosols from the lubricating oil. However, the compression chambers 5, in which the gas is compressed by rotating one or more compressor rotors 6, should remain oil-free. For this purpose, the shaft sealing devices 10a, 10b are sealed against the oil chambers 19a, 19b with the internal seals 12a, 12b and the external seals 17a, 17b. The seals 17a, 17b and 12a, 12b are non-contacting and are not completely sealed due to the high circumferential speeds and temperatures during operation. Narrow sealing gaps 14a, 14b remain on the circumference of the shaft sections 11a, 11b of the compressor rotor 6 assigned to the shaft sealing devices 10a, 10b, through which the gas flow can flow in the direction of the compression chambers 5 or vice versa, depending on the pressure gradient. This gas flow occurs due to leakage of the seals 17a, 17b and 12a, 12b. However, the lubricant may not enter the compression chamber 5 or the periphery 9 of the compressor housing 4 so as not to jeopardize the purity of the compressed gas.

[0063] According to an embodiment of the present invention, the sealing gas system prevents the ingress of lubricant into the compression chamber 5. Between the inner seal 12a, 12b and the outer seal 17a, 17b, the sealing gas chambers 13a, 13b are arranged. The sealing gas chambers 13a, 13b of the suction-side and pressure-side shaft seal arrangements 10a and 10b are connected to each other via a sealing gas connection line 42, which can also be designed as a bore in the compressor housing 4. The sealing gas flows from the sealing gas chambers 13a, 13b into the oil chambers 19a, 19b with a corresponding pressure drop. The oil chambers 19a, 19b are each supplied with an oil chamber pressure p0, which is higher than the ambient pressure p0. OR , i.e. sealed from the environment 9 so that an overpressure can be established and maintained.

[0064] Normally, there is an air leakage flow from the compression chamber 5 through the internal seal 12b at the pressure side 86 into the sealed gas chamber 13b. The higher the pressure in the compression chamber 5, the higher the air leakage flow. Thus, the air leakage flows at the internal seals 12a and 12b are different. At the suction side 85, the leakage flow through the internal seal 12a is smaller than at the pressure side 86 and can reverse in the opposite direction. At the suction side 85, during loaded operation, some sealed gas can also be drawn into the compression chamber 5 through the internal seal 12a, because the pressure there is lower than in the sealed gas chamber 13a over most of the circumference of the compressor rotor 6. At normal loaded operation, the sealed gas chamber pressure p SGR is maintained in the connected sealed gas chambers 13a, 13b due to leakage in the inner seal 12a and especially in the inner seal 12b.

[0065] In certain operating conditions, for example with low compression pressures or transient processes, sealing gas is additionally supplied to the sealing gas chambers 13a, 13b via a sealing gas supply line 50 and a regulated sealing gas supply valve 51. The sealing gas supply valve 51 can also be designed as a mechanical pressure reducing valve, in particular for a more cost-effective design of the compressor 1, and the control unit 60 described below can also be omitted. In the embodiment shown in FIG. 1, the additional sealing gas (sealing air) is branched off from the compressed air flow input to the compressed air outlet 76 and is supplied to the sealing gas supply duct 41 as an internal sealing gas input via the sealing gas supply valve 51. The sealing gas chamber pressure p in the sealing gas chambers 13a, 13b is SGR From this, the oil chamber pressure p OR During operation, the pressure gradient (p OR <p SGR), air leakage is generated (during operation) from the dry sealed gas chambers 13a, 13b through the external seals 17a, 17b into the oil chambers 19a, 19b, which air leakage flows into the oil chambers 19a, 19b as a sealed gas flow. Due to this pressure difference across all the external seals 17a and 17b, the lubricant, i.e. oil, is retained in the oil chambers 19a, 19b despite the sealing gaps 14a, 14b, and at the same time a sealed gas flow, which may include the supplied sealed air and the leaked air from the compression chamber 5, is forced into the oil chambers 19a, 19b, where the oil chamber pressure p OR is established or exists. The sealed gas chamber pressure p SGR is detected by the pressure sensor 45. The oil chamber pressure p OR is recorded by the pressure sensor 25. SGR and p OR The measured pressure values ​​for are transmitted to the control unit 60, which uses them to determine the differential pressure (not shown in FIG. 1).

[0066] According to a further aspect of the invention, the oil-contaminated leaking or sealed gas stream does not pass unpurified from the oil chamber 19a, 19b through the air outlet 37 into the environment 9 or even into the intake area of ​​the air inlet 70 of the compressor 1, but is introduced into the oil separator 30 via the gas outlet 26 and the gas discharge line 20. The gas outlet 26 is designed as a through opening in the compressor housing 4. The oil separator 30 can comprise several, preferably three, separation stages. In the oil separator 30, the oil (oil droplets and oil aerosols) is separated from the air. In this embodiment, the oil separator 30 comprises a fine separator 32, i.e. a high-density coalescing filter. The separated oil collects on the dry side of the filter element.

[0067] In the embodiment shown, the oil is returned via gravity and a height difference H in the oil return line 34 that is sufficient for all operating conditions, including pressure conditions during load operation. The oil return line 34 guides the separated oil in the oil sump 24 to a level below the oil level 23, which prevents oil smoke from the gas discharge line 20 from flowing via the oil return line 34 and bypassing the oil separator 30. Instead of or in addition to the height difference, an oil pump 36 (see figures 4 and 5) can be used. The height difference H or the delivery volume of the oil pump 36 is selected depending on the maximum differential pressure of the oil separator 30, in particular the coalesced filter elements of the fine separator 32, which can be, for example, 100 to 300 mbar.

[0068] The oil chamber pressure p, which is established by the inflow of sealed and leaked air into the oil chambers 19a, 19b OR is above the ambient pressure p0 of the compressor housing by a sufficiently large oil separation pressure difference Δp, which is required for the air flow leaving the gas outlet 26 to overcome the pressure difference in the oil separator 30. If the gas flow overcomes a pressure drop of e.g. 200 mbar from the oil chambers 19a, 19b through the inlet side of the oil separator 30 to the outlet side as a pressure difference through the coalescing filter elements of the fine separator 32, this corresponds to an oil separation pressure difference Δp of 20% at atmospheric pressure as an ambient pressure p0 of 1 bar at the outlet side of the oil separator 30, thereby reducing the oil chamber pressure p OR is at least greater than the ambient pressure p0.

[0069] Figure 2 shows a detailed view of the compressor 1, from which the structure of the compressor stages of the screw compressor can be seen. In this view, two compressor rotors 7, 8 can be seen, which are helically intermeshed and which together compress the process gas (air). Compressor rotor 8 is driven by compressor rotor 7 via a synchronous gear 84.

[0070] Between the inner seal 12a, 12b and the outer seal 17a, 17b, two sealed gas chambers 13a, 13c and 13b, 13d are shown, which are separated from each other by an additional intermediate seal 15a, 15b. The seals 12a, 12b, 15a, 15b, 17a, 17b are non-contact shaft seals, since the circumferential speeds and temperatures are too high for contact with the seals over a long period of time. The seals 12a, 12b, 15a, 15b, 17a, 17b can have a conveying effect. For this purpose, for example, a screw thread can be present, which additionally promotes leakage in the direction of the oil chambers 19a, 19b during operation.

[0071] Oil reaches the oil-lubricated bearings 18a, 18b as lubricant via a lubricant oil inlet 82. The oil chambers 19a, 19b are connected to each other via a connecting line 21. The oil chamber 19b has a gas outlet 26 for connecting a common gas discharge line 20 for injecting a gas stream with oil smoke into an oil separator 30 (not shown in FIG. 2).

[0072] On the suction side 85 of the compressor rotors 7 and 8, the sealed gas chambers 13a, 13c of the two shaft seal devices 10a, 10b have separate sealed gas supply ducts 41, so that there are a total of four sealed gas supply ducts 41 on this side. On the pressure side 86, the sealed gas chambers 13b, 13d of the two compressor rotors 7 and 8 are connected to each other via through-holes in the compressor housing 4 via sealed gas connection lines 42, so that there are a total of two sealed gas supply ducts 41 on the pressure side 86.

[0073] Each of the compressors 1 in Figures 1, 3, 4, and 5 can be designed with suction and pressure side shaft seal devices 10a, 10b, each with two sealed gas chambers 13a, 13c or 13b, 13d, as shown in Figure 2. In other figures, the viewpoint is chosen so that only one compressor rotor is visible for greater clarity. In addition to the oil-free screw compressor, the compressor 1 can also be an oil-free compression screw blower, a roots blower, or a speed compressor.

[0074] FIG. 3 shows a compressor 1 similar to that shown in FIG. 1, the differences being explained below.

[0075] The compressor 1 has a sealed gas buffer volume 48, which can be designed as a gas pressure vessel or as a cavity integrated into the compressor housing 4. The sealed gas chambers are connected to one another by a sealed gas connection line 42, which runs through the sealed gas buffer volume 48 with an enlarged flow cross section. The sealed gas buffer volume 48 compensates for pressure fluctuations during operation of the compressor 1 and reduces the sealed chamber pressure p SGR can be used to readjust the flow rate of the sealed gas. At the same time, this sealed gas buffer volume 48 performs a cooling function for the sealed gas by increasing the surface area. The sealed gas buffer volume 48 has a separation effect and is designed to separate and collect liquid or solid contaminants before the sealed gas is injected into the other sealed gas chamber. Separation can be achieved by a deflector for the sealed gas, a reduced flow velocity in the buffer volume and / or a (coarse) demister mesh.

[0076] Furthermore, a sealing gas input 58 is shown as an external sealing gas source, which in addition to the internal sealing gas source serves to provide sealing gas from the compressed air outlet 76 via the sealing gas supply valve 51a. A volume of sealing gas is stored in a sealing gas buffer volume 55, e.g. a buffer tank, so as to be able to provide a sufficient supply of sealing gas via the adjustable sealing gas supply valve 51 during transient operating conditions of the compressor 1, e.g. for a safe start-up without pressure at the compressed air outlet 76 or for a safe venting (shutdown) in case of a power failure. A non-return valve 59 prevents gas overflow from one sealing gas source to the other. The individual sealing gas sources are fed into the compressor 1 via the detected sealing gas chamber pressure p SGRor other operating parameters, via the sealing gas supply valves 51, 51a and 51b, either individually or together. If required, sealing gas can thus be supplied to the sealing gas buffer volume 48 via the sealing gas supply valve 51 and further to the sealing gas chambers 13a, 13b. The sealing gas inputs 58, in particular the external one, and the sealing gas buffer volumes 48, 55 can be used independently of each other.

[0077] Via the pressure sensor 45, the pressure p in the sealed gas buffer volume 48, in the sealed gas connection line(s) 42 and in the sealed gas chamber 13 SGR The oil chamber pressure p in the oil chambers 19a, 19b connected via the connecting line 21, the gas exhaust line 20, and optionally in the oil sump 24 (not shown in FIG. 3) is detected. OR is recorded via pressure sensor 25. The pressure in the sealed gas buffer volume 55 is detected by pressure sensor 54. The pressure sensors 25, 45, 54 and the sealing gas supply valves 51, 51a, 51b are connected to a control unit 60 (not shown).

[0078] During operation, oil is collected in the lower area of ​​the oil separator 30. When the compressor is stopped and the pressure between the oil separator 30 and the oil chambers 19a, 19b is balanced, the oil is returned to the oil chambers 19a, 19b via the oil return line 34 using gravity and a sufficient height difference H2. In the present exemplary embodiment, due to the pressure conditions occurring during loaded operation, the height difference H2 alone is not sufficient to reliably prevent oil from flowing back, so a check valve 39 is provided in the oil return line 34, which reliably prevents the oil from bypassing the filter element of the oil separator 30. Thus, return only occurs when the pressure level drops, for example when the compressor 1 is stopped or may be idling. In the embodiment shown in FIG. 1 with a sufficiently large height difference H, however, oil recirculation also occurs during loaded operation.

[0079] 4 shows a two-stage compressor, where a first compressor stage 2 and a second compressor stage 3 are connected in series to achieve a higher final pressure, where the sealed gas chamber of the second compressor stage 3 is connected to the sealed gas chamber of the first compressor stage 2. In this way, leakage in the internal seals 12a, 12b of the second compressor stage 3 can be used to pressurize the sealed gas chambers 13a, 13b of the first compressor stage 2.

[0080] Also shown is an inlet valve 71, which can be used to reduce the pressure at the inlet of the first compressor stage 2 and at the same time blow off air via a relief valve 72 when the compressor is idling. A check valve 73 prevents backflow from the compressed air outlet 76. Idle operation is partly necessary to allow easier starting of the compressor and to limit the number of motor starts when air requirements are low. Figure 5 also shows an air pressure sensor 77 for the final system pressure (i.e. at the interface to the compressed air network) and an air pressure sensor 78 for the final compressed pressure.

[0081] The closed inlet valve 71 and the open relief valve 72 (idle blow-off valve) result in that negative pressure is present in the compression chamber of the first compressor stage 2 and also on the suction side 85 of the second compressor stage 3 during idling. As a result, some sealing gas is drawn in from the sealed gas chambers 13a, 13b through the internal seals 12a, 12b, which is in any case more advantageous than drawing in any contaminated (usually unfiltered) air from the environment or oil leakage in the compressor without sealing gas. Downstream of the compressor stages 2 and 3, the compressed air is cooled in a heat exchanger 74 and the condensate formed is separated and discharged via a condensate separator 75. In this way, the cooled air, preferably with a lower water content, can be used to pressurize the sealed gas chambers 13a, 13b via the sealed gas supply valve 51.

[0082] The sealed gas chambers 13a, 13b are equipped with a negative pressure safety device 46, so that in case of a vacuum, ambient air can enter the sealed gas chambers 13a, 13b, preventing a negative pressure in the sealed gas chambers 13a, 13b. The negative pressure safety device 46 is designed as a check valve that opens towards the sealed gas chambers 13a, 13b.

[0083] The suction side oil chambers 19a of the two compressor stages 2 and 3 are connected to one another via a common gear housing 89. The gear housing 89 houses a drive gear 83, which is also oil lubricated and driven by a drive shaft 90, which comprises a drive gear wheel connected to the suction side shaft section 11a for driving the compressor rotor 6. The pressure side oil chamber 19b, in which the synchronizing gear 84 is arranged, is also connected to the pressure side oil chamber 19b via a connecting line 21, which supplies the oil chamber pressure p OR The oil chamber 19a is connected to a common oil chamber 19a where the oil pressure p exists. Also shown is circulating oil lubrication with the oil sump 24, the lubricating oil pump 81, and the lubricating oil lines 80 to the bearings 18a, 18b and the drive gears 83, 84. Due to the lower speed, a contacting drive shaft seal 87 can also be used to seal the drive shaft 90 so that no or less leakage occurs. These leakages can also be drained into a leakage collection device 88 or, optionally, returned to the oil sump 24, where the increased oil chamber pressure p in the oil sump 24 or oil chamber 19a is eliminated. OR must be taken into consideration.

[0084] FIG. 4 shows a three-stage soot separation process. Large oil droplets are pre-separated in a pre-separator 31, for example by a wire mesh / demister, and the separated oil can flow back into the oil chamber by gravity. The soot then flows through a fine separator 32, which can be a coalescing filter 32. In this case, the pressure difference across the separator element is so high that the separated oil can no longer return by gravity to the oil chamber with tolerable height differences during operation. For this purpose, an oil return device in the form of an oil pump 36 and a backflow preventer 38 is provided in the oil return line 34, so as to allow the oil to be returned to the oil chamber 19a even during continuous operation of the compressor 1. The oil pump 36 can be designed as a peristaltic pump or a vibrating diaphragm pump. The oil pump 36 can be switched on and monitored via a fill level sensor 35 as required. By monitoring the fill time and the pump-down time, the soot separation and the oil return can also be monitored for correct functioning. A residual oil separator 33 designed as an adsorption filter 33, for example an activated carbon filter, is used as the third cleaning stage. It also adsorbs the remaining residual oil and oil vapors, so that clean air is blown out to the environment 9 via the air outlet 37. In the case of process gas compression, the escaping purified gas can also be injected directly back into the intake of the compressor 1.

[0085] In exceptional cases, such as emergency venting of the oil chambers 19a, 19b, e.g. in case of overpressure in the oil chambers 19a, 19b or in case of operational failure (power failure), the oil smoke can also be blown out of the oil chambers 19a, 19b via the blow-off valve 47. To prevent excess oil from escaping into the environment 9, the oil smoke is pre-cleaned via a pre-separator 31 with low pressure loss.

[0086] FIG. 5 shows a two-stage oil-free compressor 1, in which the sealed gas chambers are operated at different sealed gas chamber pressures p SGR , i.e. p SGR1 and p SGR2The pressure levels of the sealed gas chambers 13a, 13b can be adjusted via pressure control valves 52, 53. The pressure control valve 52 is a pressure reducing valve. Two (or more) different pressure levels can be used to optimize the sealed gas flow for the respective operating conditions. The sealed gas chamber pressure p recorded by the respective pressure sensors 45a and 45b is SGR1 and p SGR2 are measured in sealed gas buffer volumes 43 and 44, respectively.

[0087] If liquid runs low in the sealed gas chamber, this can be detected by a level sensor 57 and the condensate can be drained through a drain valve 56 .

[0088] Several procedural aspects of the invention, particularly those relating to the control system, are described below.

[0089] The pressure sensors 25, 45a, 45b, the adjustable sealed air supply valve 51, the blow-off valve 47 and the oil pump 36, in addition to other sensors such as the air pressure sensors 77, 78 and the fill level sensor 35, as well as the liquid sensor 57, are connected to a control unit 60, which may provide further inputs for recording measurement data from the other sensors and outputs for controlling other components, in particular the valves. The control unit 60 may in particular determine the oil chamber pressure p detected by the sensor 25, OR The sealed gas chamber pressure p detected by the sensor 45 or 45a and 45b is monitored. SGR Or p SGR1 and p SGR2 Based on the oil chamber pressure p OR This differential pressure (p SGR -p OR ) the control unit 60 controls the sealing gas supply valve 51 or the sealing gas supply valves 51a, 51b. The control unit 60 can be located (locally) on the compressor 1 or connected to the compressor 1 via a (wireless) network connection for its control and regulation. SGRcan be monitored within fixed or dynamic limits. The control unit 60 can take into account further operating parameters of the compressor, such as the intake and discharge pressures, the speed or temperature of the compressor stages, to set one or more sealed gas chamber pressures for each operating condition.

[0090] The sealing gas supply valve 51 is closed during longer shutdown times to prevent unnecessary loss of compressed air.

[0091] Just before or when the compressor 1 starts to operate, the sealing gas supply valve 51 is already opened to pressurize the sealing gas chambers 13a, 13b with sufficient overpressure.

[0092] During operation, the sealed gas chamber pressure p SGR is the p in the sealed gas chambers 13a, 13b SGR The oil chamber pressure p in the oil chambers 19a, 19b is always OR is adjusted to be higher than

[0093] During shutdown, the pressure p in the sealed gas chambers 13a, 13b SGR is slowly reduced by injecting only small amounts of sealing gas via the sealing gas supply line 50 as needed. This achieves a uniform reduced pressure both in the sealing gas buffer volumes 43, 44 with their sealing gas chambers 13a, 13b as well as in the transmission housing 89 with its oil chambers 19a, 19b. This ensures that the pressure gradient continues to run from the sealing gas chambers 13a, 13b to the oil chambers 19a, 19b and not vice versa. The sealing gas flow continues to flow into the oil chambers 19a, 19b.

[0094] [List of reference numbers] 1. Compressor 2 First Compressor Stage 3 Second Compressor Stage 4 Compressor housing 5 Compression Chamber 6 Compressor rotor 7 First Compressor Rotor 8 Second Compressor Rotor 9 Environment 10a, 10b Shaft seal device 11a, 11b Shaft section 12a, 12b Internal seal 13a, 13b Outer sealed gas chamber 13c, 13d Inner sealed gas chamber 14a, 14b Sealing gap 15a, 15b Intermediate seal 16 Rotor bearing 17a, 17b External seal 18a, 18b Bearings 19a, 19b Oil chamber 20 Gas exhaust line 21 Connection Line 23 Oil level 24 Oil Sump 25 Pressure sensor (oil chamber pressure p OR ) 26 Gas outlet 30 Oil separator 31 Pre-separator 32 Fine separator 33 Residual oil separator 34 Oil return line 35 Filling level sensor 36 Oil Pump 37 Air outlet 38 Backflow preventer 39 Check valve 41 Sealed gas supply duct 42 Sealed gas connection line 43,44 Sealed gas buffer volume 45 Pressure sensor (sealed gas chamber pressure p SGR ) 45a, 45b Pressure sensor (sealed gas chamber pressure p SGR ) 46 Negative Pressure Safety Device 47 Blow-off valve 48 sealed gas buffer volume 50 Sealed gas supply line 51 Sealing gas supply valve 51a Sealing gas supply valve 51b Sealing gas supply valve 52 Pressure Control Valve 53 Pressure Control Valve 54 Pressure Sensor 55 Sealed gas buffer volume 56 Drain valve 57 Liquid Sensor 58 Sealed gas inlet 59 Check valve 60 Control Unit 70 Air inlet 71 Inlet valve 72 Relief valve 73 Check valve 74 Heat exchanger (compressed air cooler) 75 Condensate separator 76 Compressed air outlet 77 Air pressure sensor for system end pressure 78 Air pressure sensor for compression end pressure 80 Lubricant Line 81 Lubricating Oil Pump 82 Lubricating oil intrusion 83 Drive Gear 84 Synchronous Gear 85 Suction side 86 Pressure Side 87 Drive shaft seal 88 Leak Collection Device 89 Gear housing 90 Drive shaft

Claims

1. A dry-compression compressor (1) for generating compressed air, having one or more compressor stages (2, 3), - a compressor housing (4), - at least one compressor rotor (6, 7, 8) rotatably mounted relative to the compressor housing (4) via rotor bearings (16), wherein the compressor housing (4) comprises ○ a compression chamber (5) for compressing the gas drawn in by the compressor rotor (6, 7, 8), ○ at least one oil chamber (19a, 19b) accommodating at least one oil-lubricated bearing (18a, 18b) of the rotor bearings (16) for mounting the shaft sections (11a, 11b) of the compressor rotor (6, 7, 8), and - a shaft seal device (10a, 10b) assigned to the shaft sections (11a, 11b), arranged between the oil-lubricated bearing (18a, 18b) and the compression chamber (5) to seal the compression chamber (5) against the ingress of oil from the oil chamber (19a, 19b), the shaft seal device (10a, 10b) having an outer seal (17a, 17b) facing the oil-lubricated bearing (18a, 18b) without contact and an inner seal (12a, 12b) facing the compression chamber (5) without contact, at least one sealing gas chamber (13a, 13b, 13c, 13d) for accommodating sealing gas being formed between the outer seal (17a, 17b) and the inner seal (12a, 12b), the oil chamber (19a, 19b) having at least one gas inlet for diverting sealing gas from the sealing gas chamber (13a, 13b, 13c, 13d), and a gas outlet (26) for connection to an oil fume separator, The oil chambers (19a, 19b) have an oil chamber pressure p that exceeds the ambient pressure p of the compressor housing (4) by an oil separation pressure difference Δp 0 and are designed to provide an oil chamber pressure p that exceeds the ambient pressure p of the compressor housing (4) by an oil separation pressure difference Δp OR of at least 20 mbar, dry-compression compressor (1).

2. The dry-compression compressor (1) according to claim 1, characterized in that the gas outlet (26) of the oil chamber (19a, 19b) is connected to an oil fume separator.

3. A dry-compression compressor (1) for generating compressed air, having one or more compressor stages (2, 3), - a compressor housing (4), - at least one compressor rotor (6, 7, 8) rotatably mounted relative to the compressor housing (4) via rotor bearings (16), wherein the compressor housing (4) comprises ​ ○ A compression chamber (5) for compressing the gas drawn in by the compressor rotors (6, 7, 8); ○ At least one oil chamber (19a, 19b) accommodating at least one oil-lubricated bearing (18a, 18b) of the rotor bearing (16) for mounting the shaft sections (11a, 11b) of the compressor rotors (6, 7, 8); Comprising: - A shaft seal device (10a, 10b) assigned to the shaft sections (11a, 11b), arranged between the oil-lubricated bearings (18a, 18b) and the compression chamber (5) to seal the compression chamber (5) against the ingress of oil from the oil chambers (19a, 19b) and having a non-contact seal; Comprising, the oil chambers (19a, 19b) having at least one gas inlet for the leakage gas flow from the shaft seal device (10a, 10b); And a gas outlet (26) connected to at least an oil fume separator; The oil chambers (19a, 19b) have an oil chamber pressure p 0 that exceeds the ambient pressure p OR of the compressor housing (4) by an oil separation pressure difference Δp, and the oil separation pressure difference Δp is at least 20 mbar, for a dry compression type compressor (1).

4. The seal (17a, 17b) is an external seal (17a, 17b) facing the oil-lubricated bearing (18a, 18b), the shaft seal device (10a, 10b) also having an internal seal (12a, 12b) facing the compression chamber (5), at least one sealing gas chamber (13a, 13b, 13c, 13d) for receiving the sealing gas being formed between the external seal (17a, 17b) and the internal seal (12a, 12b), and the leakage gas flow from the shaft seal device (10a, 10b) being a sealing gas flow. The dry compression type compressor (1) according to claim 3, characterized in that.

5. The gas inflow of the oil chamber (19a, 19b) is formed by at least one sealing gap (14a, 14b) of the seal (17a, 17b). The dry compression type compressor (1) according to any one of claims 1 to 4, characterized in that.

6. The dry-compression compressor (1) is characterized in that it comprises at least one pressure sensor (25) for detecting the oil chamber pressure p OR . The dry compression type compressor (1) according to any one of claims 1 to 4.

7. The oil fume separator comprises a plurality of separation stages, at least one pre-separator (31) and / or at least one fine separator (32) and / or at least one residual oil separator (33), the fine separator (32) comprising a combined filter. The dry compression type compressor (1) according to any one of claims 1 to 4, characterized in that.

8. The sealed gas flow and / or the leakage gas flow is an air flow, and an air outlet (37) downstream of the oil fume separator leads to the free environment of the dry compression compressor (1), characterized in that the dry compression compressor (1) according to any one of claims 1 to 4.

9. The dry compression compressor (1) is provided with an oil return line (34) for returning the oil separated in the oil fume separator to the oil chambers (19a, 19b), and an oil pump (36) is arranged in the oil return line (34), characterized in that the dry compression compressor (1) according to any one of claims 1 to 4.

10. The dry-compression compressor (1) releases the oil chamber pressure p from the oil chambers (19a, 19b). OR The dry-compression compressor (1) according to any one of claims 1 to 4, characterized in that it comprises a blow-off valve (47) for releasing the pressure p from the oil chambers (19a, 19b).

11. The rotor bearing (16) comprises an oil-lubricated suction-side bearing (18a) and an oil-lubricated pressure-side bearing (18b), each of which rotatably supports a shaft section (11a, 11b) of the compressor rotor (6, 7, 8) with respect to the compressor housing (4), and the compressor housing (4) has a suction-side oil chamber (19a) in which the oil-lubricated suction-side bearing (18a) is accommodated and a pressure-side oil chamber (19b) in which the oil-lubricated pressure-side bearing (18b) is accommodated, and the suction-side oil chamber (19a) and the pressure-side oil chamber (19b) are connected to each other, characterized in that the dry compression compressor (1) according to any one of claims 1 to 4.

12. The rotor bearing (16) comprises an oil-lubricated suction-side bearing (18a) and an oil-lubricated pressure-side bearing (18b), each of which rotatably supports a shaft section (11a, 11b) of the compressor rotor (6, 7, 8) with respect to the compressor housing (4), a suction-side shaft seal device (10a) is provided for the oil-lubricated suction-side bearing (18a), and a pressure-side shaft seal device (10b) is provided for the oil-lubricated pressure-side bearing (18b). The suction-side sealed gas chambers (13a, 13c) of the suction-side shaft seal device (10a) and the pressure-side sealed gas chambers (13b, 13d) of the pressure-side shaft seal device (10b) are connected to each other via a sealed gas connection line (42), characterized in that the dry compression compressor (1) according to any one of claims 1 to 4.

13. The shaft seal device (10a, 10b) additionally has an intermediate seal (15a, 15b) between the external seal (17a, 17b) and the internal seal (12a, 12b), and an external seal gas chamber (13a, 13b) for receiving a sealing gas is formed between the external seal (17a, 17b) and the intermediate seal (15a, 15b), and an internal seal gas chamber (13c, 13d) for receiving a sealing gas is formed between the intermediate seal (15a, 15b) and the internal seal (12a, 12b). The dry compression type compressor (1) according to any one of claims 1 to 4.

14. The dry-compression compressor (1) has a sealed gas supply unit (50, 51, 51a, 51b), whereby the sealed gas chamber pressure p in at least one sealed gas chamber (13a, 13b, 13c, 13d) SGR is variably adjustable, and the sealed gas supply unit (50, 51, 51a, 51b) is characterized by comprising an adjustable sealed gas supply valve. The dry compression type compressor (1) according to any one of claims 1 to 4.

15. The dry compression type compressor (1) has at least one sealed gas buffer volume part (48, 55) between the sealed gas input part (58) and the sealed gas chambers (13a, 13b, 13c, 13d), and the sealed gas buffer volume part (48, 55) is designed as a cavity. The dry compression type compressor (1) according to any one of claims 1 to 4.

16. The dry-compression compressor (1) is characterized by comprising at least one pressure sensor (45, 45a, 45b) for detecting the pressure p of a sealed gas chamber in at least one sealed gas chamber (13a, 13b, 13c, 13d) and / or a sealed gas buffer volume part (48, 55). SGR ​ The dry compression type compressor (1) according to any one of claims 1 to 4.

17. An electronic control unit (60) is provided, and the control unit (60) is for the sealed gas chamber pressure p SGR and / or the oil chamber pressure p OR and / or the sealed gas chamber pressure p SGR and the oil chamber pressure p OR characterized in that it is designed to monitor the differential pressure therebetween. The dry compression type compressor (1) according to claim 16.

18. The control unit (60) adjusts the seal gas supply valve (51) so that the seal gas chamber pressure p SGR is higher than the oil chamber pressure p in the oil chambers (19a, 19b), and the seal gas chamber pressure p in the seal gas chambers (13a, 13b, 13c, 13d) is set for different operating states of the dry compression compressor (1). OR The seal gas supply valve (51) is arranged in a seal gas supply line (50) to at least one of the seal gas chambers (13a, 13b, 13c, 13d). SGR characterized by being arranged in a seal gas supply line (50) to at least one of the seal gas chambers (13a, 13b, 13c, 13d). The dry compression type compressor (1) according to claim 16.

19. The dry compression type compressor (1) has a sealed gas supply valve (51) designed as a pressure reducing valve, and the sealed gas supply valve (51) is arranged in a sealed gas supply line (50). The dry compression type compressor (1) according to any one of claims 1 to 4.

20. At least one sealed gas chamber (13a, 13b, 13c, 13d) has a negative pressure safety device (46), and the negative pressure safety device (46) is designed as a check valve that opens towards the sealed gas chamber (13a, 13b, 13c, 13d). The dry compression type compressor (1) according to any one of claims 1 to 4.

21. The oil chamber of the first compressor stage (2) and the oil chamber of the second compressor stage (3) of the dry compression type compressor (1) according to any one of claims 1 to 4 are connected to each other.

22. The dry-compression compressor (1) has a plurality of compressor stages (2, 3), and at least one sealed gas chamber (13a, 13b, 13c, 13d) of the first compressor stage (2) operating at a first pressure level is connected to at least one sealed gas chamber (13a, 13b, 13c, 13d) of the second compressor stage (3) operating at a second pressure level, and the first pressure level is lower than the second pressure level. The dry-compression compressor (1) according to any one of claims 1 to 4.

23. A method for oil separation for a dry-compression compressor (1) having at least one compressor rotor (6, 7, 8) with an oil-lubricated rotor bearing (16) of one or more compressor stages (2, 3) for generating compressed air, the method comprising: - introducing a leakage gas flow flowing out from a shaft seal device (10a, 10b) assigned to a shaft section (11a, 11b) of the compressor rotor (6, 7, 8) into an oil chamber (19a, 19b) of a compressor housing (4) of the dry-compression compressor (1), in which at least one oil-lubricated bearing (18a, 18b) of the oil-lubricated rotor bearing (16) is accommodated; - an oil chamber pressure p that exceeds the ambient pressure p of the compressor housing (4) by an oil separation pressure difference Δp of at least 20 mbar 0 is provided in the oil chambers (19a, 19b), and OR providing said oil chamber pressure p into said oil chambers (19a, 19b); - feeding a gas flow from the oil chamber (19a, 19b) into an oil separator (30, 31, 32, 33). The method comprising.

24. - detecting the oil chamber pressure p by at least one pressure sensor (25) OR and / or - detecting the sealed gas chamber pressure p by at least one pressure sensor (45, 45a, 45b) SGR and / or - determining a differential pressure between the sealed gas chamber pressure pSGR and the oil chamber pressure p OR ; and Here, the shaft seal device (10a, 10b) has an external seal (17a, 17b) facing the oil-lubricated bearing (18a, 18b) without contact, and an internal seal (12a, 12b) facing the compression chamber (5) without contact, and the sealed gas chamber (13a, 13b, 13c, 13d) is formed between the external seal (17a, 17b) and the internal seal (12a, 12b) for receiving a sealed gas, and / or - A step of monitoring a differential pressure between the sealed gas chamber pressure p SGR and / or the oil chamber pressure p OR and / or the sealed gas chamber pressure p SGR and the oil chamber pressure p OR by a control unit (60). characterized by at least one of The method according to claim 23.

25. Sealing gas chamber pressure p SGR is higher than the oil chamber pressure p in the oil chambers (19a, 19b), OR depending on the operating state of the dry compression type compressor (1), by supplying sealing gas into the sealing gas chambers (13a, 13b, 13c, 13d), the sealing gas chamber pressure p in at least one of the sealing gas chambers (13a, 13b, 13c, 13d) of the shaft seal device (10a, 10b) SGR is set, characterized in that The method according to claim 23.

26. - while the dry-compression compressor (1) is being operated at idle, and / or - during a transient operating state of the dry-compression compressor (1), and / or while the dry-compression compressor (1) is being operated under load, The sealing gas pressure p in the sealing gas chambers (13a, 13b, 13c, 13d) SGR is higher than the oil chamber pressure p in the oil chambers (19a, 19b), and by opening the sealing gas supply valves (51, 51a, 51b), OR sealing gas is supplied into the sealing gas chambers (13a, 13b, 13c, 13d). The method according to claim 23. **Claim 27**: At least one leakage gas flow from at least one sealed gas chamber (13a, 13b, 13c, 13d) of a second compressor stage (3) operating at a second pressure level is introduced into at least one sealed gas chamber (13a, 13b, 13c, 13d) of a first compressor stage (2) operating at a first pressure level via a sealed gas connection line (42) connecting the sealed gas chambers (13a, 13b, 13c, 13d), the leakage gas flow flowing from a pressure-side shaft seal device (10b) of the second compressor stage (3) into the pressure-side sealed gas chambers (13b, 13d) of the second compressor stage (3), and the first pressure level being lower than the second pressure level. The method according to claim 23.

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