FR2518662A1 - OIL SUPPLY DEVICE FOR SCREW COMPRESSOR - Google Patents

Abstract

THE INVENTION RELATES TO AN OIL SUPPLY DEVICE FOR A SCREW COMPRESSOR, IN A REFRIGERATION INSTALLATION OPERATING IN PARTICULAR AS A HEAT PUMP. THE OIL CIRCULATES IN A CLOSED CIRCUIT, IT IS SEPARATED IN A SEPARATOR 4 FROM A COMPRESSED MIXTURE OF OIL AND REFRIGERATION AGENT AND FROM THE SEPARATED OIL A PARTIAL QUANTITY OF REFRIGERATION AGENT IS DISSOLVED IN THE 'OIL AS A FUNCTION OF PRESSURE AND TEMPERATURE. THE HEAT OF COMPRESSION ABSORBED BY THE OIL IS BROUGHT INTO A COOLER 8, WHILE THE OIL AND REFRIGERANT SOLUTION IS INJECTED UNDER PRESSURE INTO THE COMPRESSOR 3. THE FLOW PATH 13 OF THE SOLUTION CONTAINED IN SEPARATOR 4 IS SUBDIVIDED BEFORE COOLER 8 INTO TWO PARTIAL CURRENTS. APPLICATION TO THE LUBRICATION OF COMPRESSORS.

Description

18662

  The invention relates to a supply device

  oil supply for a screw compressor in a

  refrigeration system operating in particular

  as heat pump, the oil circulating in a closed circuit and being separated in an oil separator from the compressed oil-refrigerant mixture and from the separated oil a partial amount of the refrigerant being dissolved in the oil depending on the pressure and the temperature, while then the heat of compression absorbed by the oil is derived in a cooler and the oil-refrigerant solution is injected under pressure

in the screw compressor -

  It is known in screw compressors that may have one or two shafts to inject pressurized oil into the compressor for the purpose of lubricating bearings, rotor, or rotors, shaft seals and possibly the mechanism. gear, seal the intervals between the rotors when two shafts and between rotor or rotor and the housing, and

  dissipate some of the heat of compression.

  The compressed refrigerant mixture is separated from

  ration-oil, in an oil separator that

  cools down in a cooler and reintroduces

jets into the compressor.

  For the usual uses of compressors

  in refrigeration plants or possibly

  heat pumps, where relatively low condensing temperatures are achieved, for example

  low temperature, there is no particular difficulty

  with this type of oil supply.

  As in these cases the separated oil in the oil separator retains its viscosity within a permissible range, it is still possible to ensure trouble-free formation of the lubricating oil films in the compressor.

  Such an embodiment of an installation

  refrigeration system, which can operate under the conditions

  also given as a heat pump, is

  schematically in Figure 1 of the accompanying drawings.

  The installation comprises a refrigerant circuit o a screw compressor 3 driven by an electric motor 1 via a coupling

  2, an oil separator 4, a condenser 5 and an evaporator

  6 can be arranged as refrigerant, use

for example ammonia.

  The refrigerating agent vapor compressed in the compressor 3 and containing oil as a component of the mixture is introduced into the separator

  of oil 4 From this one, the oil solution

  resulting refrigerant is removed and betrayed.

  carried by means of a pressure increase pad 7

  by a cooler 8 and thence injected by means of

  9, 10a, 10b and 11 in the compression space, or feeds bearings not shown and

the shaft seal 12.

  In the case presention can for example use

  water as a cooling agent for cooling

  8 and the condenser 5, the latter being conducted in the direction of the arrow firstly through the cooler 8 and then through the condenser 5 As a means of

  heating for the evaporator 6 can be used for example

  full of water, brine or air.

  However, when screw compressors are used in heat pump installations, for example for high temperature heating systems, high condensation temperatures, for example

  the order of magnitude of 65-120 ° C are required.

  It is necessary to produce in the compressor a pressure

  final concentration relatively high because of the temperature

  condensation of the refrigerant circuit.

  This has the consequence that the lubricating oil which is under the final pressure in the oil separator is greatly enriched.

  refrigerant, especially when

  it consists of hydrocarbons containing fluorine and chlorine (for example R 12 or R 22), by

  hydrocarbons or by hydrocarbon mixtures.

  The enrichment of refrigerant in the oil can so strongly reduce the viscosity of the oil-refrigerant solution / that the formation of films

  lubricating oil in the compressor can not.

more to be guaranteed.

  The solubility of the refrigerant in the oil depends on the type of refrigerant, the type of oil and the end pressure of the compressor

  and the outlet temperature of the cooling agent mixture

  management-oil after the compressor.

  The higher the pressure in the separator

  of oil, the greater the solubility of the refrigerating agent

  management in the oil and higher is the temperature, _

lower is the solubility.

  The object of the present invention is to develop

  per device for supplying oil to a screw compressor which keeps the viscosity under control by reducing the proportion of refrigerant in

oil.

  The problem of the present invention is solved

  in that the flow path of the oil-solution

  refrigerant in the oil separator is subdivided before the cooler into two partial streams, a first partial stream being injected at least in one uncooled

  the compression space while the heat of compres-

  from the second partial stream in the cooling,

  is dissipated and that the cooled partial current

  at least the bearings of the compressor.

  It is possible on the basis of the measurements taken according to the present invention, that the partial flow

251-8662

  cooled used for bearings has a viscosity

  which guarantees the formation of oil films in the

  required portion, while on the other handby the injection of the uncooled partial stream directly into the compression space the outlet temperature is maintained correspondingly high and thus obtained as little refrigerant as possible is

dissolved in the oil.

  The outlet temperature of the compressed mixture 1-0 refrigerant oil varies according to the pressure ratio of the compressor This ratio depends on the one hand the temperature of the means transmitting the heat

  in the evaporator of the cooling circuit - and of

  to be part of the temperature to be produced by the absorbing means

the heat in the condenser.

  By changing the pressure conditions

  also vary the amount of the oil solution-

  refrigerant injected into the compressor.

  If, for example, the ratio of the pressures is lower, thus when the pressure in the evaporator increases and the pressure in the condenser remains constant, or when the pressure in the evaporator remains constant and the pressure in the condenser

  drop, the amount of solution injected with oil-

  refrigerant also becomes weaker.

  In the most favorable case, when the report is

  pressure becomes weaker, such a reduction

  solution of the injected solution of oil-refrigerant

  tion, that the outlet temperature remains constant, or varies in a range such that the viscosity of the current

  cooled partial is not influenced decisively.

  However, operating conditions may also arise for which, when the ratio of the pressures is changed, the quantity of oil injected varies so that the outlet temperature drops in a proportion for which the viscosity of the solution of oil-refrigerant becomes too low, or also cases for which the temperature

  of output goes up beyond a value which would

  such as carbonization or other

  the properties of the lubricating oil.

  In order to guarantee here also a trouble-free operation of the installation as far as

  the oil supply of the screw compressor, it is

  sees an advantageous embodiment of the present invention which consists in regulating the amount of passage

  of at least one partial current depending on the temperature

  An alternative embodiment for influencing the temperature of the compressor

  output provides that the device according to the present invention

  It includes a refrigerant-oil coolant outlet temperature sensor which influences a three-way valve connected to two oil-coolant solution supply lines, one of the lines opening out before the cooler, and other after this one, while the outlet pipe of the valve

  three-way is directed to the compression space.

  This regulation of the outlet temperature

  can also find his job when, during a job

  partly dependent on reports that are also inadmissible.

  are made with regard to the supply of

compressor oil screw.

  The present invention will now be described with reference to exemplary embodiments and in the light of the accompanying drawings in which: FIG. 1 shows as already indicated and of

  schematically an embodiment of a plant

  refrigeration section which can also function as a heat pump; Figure 2 is a block diagram of an oil supply system for a screw compressor in a refrigerant circuit of a heat pump installation where the outlet temperature is influenced by a quantity control of the uncooled partial flow;

  Figure 3 shows in a form of representation

  analogous embodiment a second embodiment where the outlet temperature is influenced by means of a temperature control of the oil solution.

  refrigerant injected into the compressor space

if we; and

  FIG. 4 represents in a functional diagram

  a third embodiment o the temperature

  outlet temperature is influenced by quantity control of the refrigerant oil-coolant solution

  injected into the compression space.

  The coinciding elements of the installation have in Figures 2 to 4 the same reference numbers as in the

figure 1.

  As a cooling agent, for example, a hydrocarbon containing fluorine and chlorine,

namely for example R 12 or R 22.

  According to FIG. 2, the flow path 13 of the oil-coolant solution in the oil separator is subdivided after the pump 7

  before the cooler 8 in two partial streams of which

  one is cooled in the cooler 8 and is supplied by the bypass lines 10a, 10b and 11 to the bearings

  not shown and at the shaft seals 12 The second section

  uncooled partial fraction is injected through a pipe 14

  o is disposed a regulating valve 15, in the

compression rate.

  In the pressure line 16 of the compressor 3 there is a temperature sensor 17 which acts on the control valve 15 via a

positioning element 18.

  As already described in a previous passage

  At the same time, the outlet temperature of the compressed refrigerant oil mixture influences the solubility of the refrigerant in the oil in the oil separator 4 and therefore the viscosity of the lubricant. On the other hand, the outlet temperature must not exceed a certain

limit value.

  If the outlet temperature deviates from the

  required because of conditions of employment which change

  the regulating valve 15 opens more or less

  in correspondence, via a signal from

  from the temperature detector 17 and transmitted to the

Positioning 18.

  While in the exemplary embodiment

  precedes, the outlet temperature is controlled by the

  In the exemplary embodiment shown in FIG. 3, the regulation of the outlet temperature takes place by means of a temperature adjustment of the partial flow injected into the compression space. here influences a three-way valve 20 as a function of the signal transmitted by the temperature sensor 17 to the positioning element 21, when the outlet temperature deviates from the value

  nominal; the valve is connected to two

  a refrigerant oil-coolant solution one of which diverges before the cooler 8 and the other 19 deviates after the cooler 8 from a manifold 22, while the outlet pipe 14 has led

in the compression space.

  In the exemplary embodiment shown in FIG. 4, the outlet temperature is influenced by regulating a partial amount of the cooled partial stream, while the flow rate of the oil-refrigerant solution uncooled injected by line 14 into the compression space

  remains constant for a specific condition of functioning.

  tioning. When the outlet temperature deviates from the

  nominal value, one influences, via a

  positioning element 23 as a function of a temperature sensor 17, a two-way valve 24 whose supply line 25 reaches the collecting pipe 22 and whose outlet line 26 goes into the space of

  compression The two-way valve is at the same temperature

  the required exit pattern in an intermediate position, so that a partial amount of cooled refrigerant oil-coolant solution is constantly mixed with

  the uncooled solution of oil-refrigerant.

  As soon as the outlet temperature exceeds the nominal value

  nal, the quantity, injected into the compression space, of chilled solution of oil-refrigerating agent

  increases or when the nominal value of the temperature

  output gradient decreases, the-amount of oil solution-

  cooled refrigeration agent is braked accordingly The mixture of uncooled solution

  and cooled solution of oil-refrigerating agent-

  takes place here inside the compression space.

  It should be noted again that in all embodiments, the uncooled partial stream can also

  be injected into several places in the compression space.

  if we. In addition, it may be appropriate to feed the shaft seal in uncooled oil-agent solution.

  refrigeration instead of the same cooled solution.

18662

Claims (3)

  1 Device for the supply of oil   of a screw compressor (3) in a refrigeration plant   in particular operating as a heat pump, the oil circulating in a closed circuit and being separated in an oil separator (4) from the compressed agent mixture   of refrigeration-oil than from the separated oil   A partial amount of refrigerant is dissolved in the oil as a function of pressure and temperature, and then the heat of compression absorbed by the oil is diverted into a cooler (8).   and the oil-refrigerant solution is injected   pressure device in the screw compressor, characterized in that the flow path (13) of the refrigerant oil-coolant solution is   the oil separator (4) is subdivided before cooling   deur (8) in two partial streams (14, 19), the first partial stream (14) of which is injected into the compression space (3) in the non-refrigerated state at at least one place, whereas at from the second partial stream into the cooler (8), compression heat is dissipated and the cooled partial stream is   brought at least to the bearings of the compressor (3).   2 Device according to claim 1, characterized   by a detector (17) of the outlet temperature of the coolant-oil mixture, the signal of which influences the amount of passage of at least one partial stream.   Device according to claim 1, characterized   by a sensor (17) of the outlet temperature of the coolant-oil mixture which influences a three-way valve (20) connected to two pipes   supplying (19, 14) of the oil-refrigerant solution   one of the supply lines (14) diverging before the cooler (8) and the other supply line (19) deviating past the cooler (8) and the outlet line (14a). the three-way valve (20) to the compression space (3) -