Screw Compressor with Oil Feed System

Abstract

A rotary screw compressor with an oil feed system that has a plurality of oil orifice nozzles to feed oil to the compressor rotors and the compressor bearings. One of the oil orifice nozzles is generally always provided with a regulated flow of oil. At least one and preferably two on/off oil valves can be selectively opened and closed. Each of the on/off oil valves are of a different size and are selectively opened and closed to step regulate the amount of oil being fed to the compression chamber according to a predetermined compression chamber discharge temperature.

1 . An improved rotary screw compressor that has compression chamber, said compression chamber including a pair of parallel cooperating compressor screws within a housing, said compression chamber having an air inlet and an air/oil outlet, the improvement comprising;
 a plurality of oil orifice nozzles, provided in said housing   one of said plurality of oil orifice nozzles being an on oil orifice nozzle that is always open or always regulating the flow of oil,   another of said oil orifice nozzles being connected to an on/off valve, and   said on/off valve being selectively opened and closed to regulate an oil volume flow into said compression chamber to regulate a discharge temperature, said discharge temperature being a temperature of a discharge from said compression chamber.   
   
   
       2 . The improved rotary screw compressor of  claim 1  wherein the housing has a plurality of oil orifice nozzles that are connected to at least two on/off valves, and each on/off valve being selectively opened and closed to regulate the oil volume flow to regulate the discharge temperature. 
   
   
       3 . The improved rotary screw compressor of  claim 2  wherein the oil orifice nozzles are sized to provide a different volume of oil to be fed to the compression chamber when by each on/off valve. 
   
   
       4 . The improved rotary screw compressor of  claim 3  wherein said on/off orifice nozzles are selectively opened and closed to maintain the discharge temperature slightly above the pressure dew point of the discharge mixture. 
   
   
       5 . The improved rotary screw compressor of  claim 3  wherein there are two on/off valves are selectively opened and closed when the discharge temperature is at a predetermined temperature. 
   
   
       6 . The improved rotary screw compressor of  claim 5  wherein of said two on/off valves, the second on/off valve and oil nozzles connected to the second on/off valve provide a larger volume of oil to the compressor than said first on/off valve and oil orifice nozzles connected to the first on/off valve. 
   
   
       7 . The improved rotary screw compressor of  claim 5  wherein after start up, said second on/off valve is closed and the first on/off valve is opened.
 if the temperature is below the predetermined temperature with the first on/off valve opened and the second on/off valve closed, the oil flow is stepped down by closing the first on/off valve; and   if the temperature rises above a second predetermined temperature with the first and second on/off valves closed, the first and second on/off valves are selectively opened and closed to step up the oil flow to reduce the temperature to below the second predetermine temperature.   
   
   
       8 . The improved rotary screw compressor of  claim 4  wherein there are three said on/off valves, the second on/off valve and oil nozzles connected to the second on/off valve provide a larger volume of oil to the compressor than said first on/off valve and oil orifice nozzles connected to the first on/off valve; and the third on/off valve and oil nozzles connected to the third on/off valve provide a larger volume of oil to the compressor than said second on/off valve and oil orifice nozzles connected to the second on/off valve. 
   
   
       9 . The improved rotary screw compressor of  claim 7  wherein at least part of the oil from the open oil line is directed to compressor bearings. 
   
   
       10 . The improved rotary screw compressor of  claim 8  wherein at least part of the oil from the open oil line is directed to compressor bearings. 
   
   
       11 . A compressor system comprising:
 a compression chamber;   an air inlet valve;   an air inlet in fluid communication with said air inlet valve, said air inlet opening into said compression chamber;   a discharge outlet in fluid communication with an air/oil separator, said air/oil separator connected to said discharge outlet, said air/oil separator having a separator air outlet and a separator oil outlet, said discharge outlet downstream of said air inlet and in fluid communication therewith,   an air line connecting said oil separator outlet to an air discharge;   an oil supply,   three oil lines connected to the oil supply,   each of said oil lines connected to an oil nozzle with each of said oil nozzles connected to deliver oil to the compression chamber,   two of said oil lines each having an on/off valve connected between the oil supply and the compression chamber and the third oil line always being opened when said compressor is in operation, and   said first and second on/off valves being selectively opened and closed to control a compression discharge temperature.   
   
   
       12 . The compressor system of  claim 11 , wherein
 the compressor is a two stage variable speed compressor wherein said compression chamber comprises   a first pair of rotary screws within a housing to form a first stage;   a second pair of rotary screws within a housing to form a second stage;   an air/oil orifice nozzle in an inter-stage connecting pipe injecting additional oil into the discharge air oil stream of said first stage and supplying air/oil mixture with supplemental injected oil to the inlet of said second stage;   said second stage having the discharge outlet connected to said air/oil separator, and   said air/oil separator having an oil line connected to the second stage to feed oil thereto.   
   
   
       13 . The compressor system of  claim 12 , wherein the second on/off valve and the oil nozzles connected to the second on/off valve has a larger volume capacity than the first on/off valve and the nozzles connected to the first on/off valve, and the two on/off valves are selectively opened and closed to control the compression chamber discharge temperature. 
   
   
       14 . The compressor system of  claim 12 , wherein
 four oil lines are connected to the oil supply and the compression chamber of said first stage compressor,   each of said four oil lines is connected to an oil nozzle with each of said oil nozzles connected to deliver oil to the compression chamber,   three of said oil lines each having an on/off valve connected between the oil supply and the compression chamber and the fourth oil line always being opened when said compressor is in operation, and   said first and second and third on/off valves being selectively opened and closed to control a compression discharge temperature.   
   
   
       15 . The compressor system of  claim 14 , wherein the second on/off valve and the oil nozzles connected to the second on/off valve has a larger volume capacity than the first on/off valve and the nozzles connected to the first on/off valve, the third on/off valve and the oil nozzles connected to the third on/off valve has a larger volume capacity than the second on/off valve and the nozzles connected to the second on/off valve, and the three on/off valves are selectively opened and closed to control the compression chamber discharge temperature.