Sealing system for centrifugal compressors which process lethal gases
A sealing system ( 10 ) which ensures the safe operation of very high pressure centrifugal compressors which process lethal gases. The system comprises sealing means ( 18, 19 ) separated by an annular chamber ( 12 ), and a discharge line ( 32 ) for collecting and eliminating any gases that may be released.
1. A sealing system for a centrifugal compressor for processing lethal gases comprising:
a compressor casing, a first annular chamber connected to a discharge line terminating in a low pressure outlet collector, sealing means being interposed between the compressor casing and an end flange of the casing including an inner lip seal and an outer lip seal, a second annular chamber between said inner lip seal and said outer lip seal, a third annular chamber upstream of said annular chamber, said third annular chamber being located between an inner ring gasket and an outer ring gasket, a first inert gas line for supplying pressurized inert gas to said third annular chamber, a second inert gas line having a shut-off valve therein for supplying pressurized inert gas to said first and second chambers in response to opening said shut off valve, a first line interconnecting said second annular chamber and a first pressure gauge, a second line connected to said discharge line and interconnecting said first annular chamber and a second pressure gauge, said discharge line being connected upstream of said second line to said first line by a third line having a shut off valve, a control unit for controlling the compressor and connected to said first and second pressure gauges, said control unit being responsive to a rapid rise of pressure detected by said first pressure gauge to cause the compressor to shut down and responsive to a rapid rise of pressure detected by said second pressure gauge to cause the compressor to be shut down.
2. A sealing system according to claim 1 wherein said second pressurized line has first and second sections connected respectively to said second annular chamber and to said first annular chamber, first and second valves in said first and second sections.
3. A sealing system according to claim 1 wherein said discharge line includes an orifice enabling outflow of gas in response to failure of the inner and outer lip seals.
4. A sealing system according to claim 1 wherein the gas processed in said centrifugal compressor is an acid gas with a content of hydrogen sulfide in excess of 1%.