Patent GB-984379-A (GB)
Title: Purge arrangements for refrigeration systems
IPC: F25B15/06
Filed: 1962-11-20
Abstract: 984,379. Refrigerating. CARRIER CORPORATION. Nov. 20, 1962 [March 28, 1962 (2)], No. 43905/62. Heading F4H. Non condensible gases withdrawn from a refrigeration system and stored in a chamber are expelled by supplying fluid under pressure to the chamber. As shown in Fig. 1, a purge arrangement 100 is utilized with a continuous cycle absorption system operating at low pressure with water as the refrigerant and lithium bromide solution as the absorbent. The system comprises a shell 34, containing the generator 30 and condenser 32, and a shell 11 containing the evaporator 15 and absorber 10, the latter being connected to an upper chamber 102 of the purge arrangement by a line 13. The chamber 102 contains a cooling coil 112 which is wound about a cylinder 111 and serves to cool absorbent solution which is tapped off from the weak solution line 26 from the absorber and is supplied through line 135 to the chamber 102 which thus functions as an auxiliary absorber. Due to the cooling effect of coil 112 the chamber 102 is at a lower pressure than the absorber 10 and non-condensible gases and refrigerant vapour are drawn into the chamber through line 13. A sump 116 is provided in the base of chamber 102 and the end 121 of a syphon tube 105 projects into the sump to withdraw alternate slugs of liquid and gas therefrom and supply them to a collecting chamber 104 at the base of the unit 100. Gases from this chamber then pass through a valve 124 into a displacement chamber 103 which is intermediate the chambers 102 and 104 and contains absorbent liquid which when displaced by the gas passes through a line 125 into the chamber 104 whence it is returned to the absorber 10 through a line 126 containing a valve 127. The gases from valve 124 are collected by a hood 130 and passed through a sight glass 131, valve 132 and line 133 to the top of the chamber 103, the arrangement being such that when valve 132 is open sight glass 131 displays the level of liquid in chamber 103 and when the valve is closed the rate of withdrawal of gases from the refrigeration system is shown by the rate of depression of the liquid level in sight glass 131. The chamber 103 contains a float arrangement comprising a shaft 139 which controls a valve 137 for the admission of liquid from the line 135 and has a lower float 138 and an upper float 140 which is disposed in the interior of the cylinder 111. As the liquid level in the chamber falls the buoyancy of the float 138 becomes insufficient to maintain valve 137 closed and absorbent is supplied to the chamber, compressing the gas therein and forcing it through the interior of cylinder 111, line 141, check valve 142 and a discharge line 143. The process continues until liquid begins to enter the interior of cylinder 111 and the combined buoyancy of floats 138 and 140 closes valve 137 whereupon gas again begins to accumulate in the chamber 103. When the refrigeration system is started and large quantities of gas must be purged therefrom, a valve 155 in a line 154 leading from the line 13 to the chamber 103 is opened. The chamber 103 is initially filled with liquid at. a level greater than that in the absorber 10 so that when the valve 127 in the line 126 is opened liquid flows to the absorber from the chamber 103 creating a partial vacuum therein and drawing gases from the absorber through lines 13 and 154. A cup 150 on the shaft 139 remains full of liquid as the liquid level drops and assists in opening the valve 137 to admit liquid to and expel gas from the chamber as before. When the refrigeration system has reached the desired pressure the valve 155 is closed and a valve 152 in a drain line 151 leading from the cup 150 is opened so that the cup plays no subsequent part in opening the valve 137. In the modified arrangement shown in Fig. 2, gases are drawn from the absorber 10 through pipe 13 into the single chamber 101<SP>1</SP> of the purge arrangement 100<SP>1</SP>. A cylinder 107<SP>1</SP> is positioned in the chamber and receives absorbent through a line 1151 having a valve 116<SP>1</SP>, the absorbent filling the cylinder and flowing down the sides thereof to be cooled by a coil 108<SP>1</SP>. A return line 117<SP>1</SP> having a valve 1181 is provided between the bottom of the chamber and the absorber, the top of the chamber having a discharge line 104<SP>1</SP>, 106<SP>1</SP> including a check valve 1051. Upper and lower floats 119<SP>1</SP> and 120<SP>1</SP> are provided in the chamber so that when the liquid level falls float 120<SP>1</SP> operates to close a valve 102<SP>1</SP> in the line 13 and to open valve 116<SP>1</SP> to a greater extent than valve 118<SP>1</SP>, causing the liquid level to rise and the gases to be expelled from the chamber. When the liquid level rises sufficiently, float 119<SP>1</SP> opens valve 102<SP>1</SP> and opens valve 118<SP>1</SP> to a greater extent than valve 116 to cause the liquid level to fall and more gas to be drawn in to the chamber. Either of the valves 116<SP>1</SP> and 118<SP>1</SP> may be omitted. Specification 929,148 is referred to.