Dry gas seal for supercritical co2 pump-high pressure buffer

Abstract

Systems and methods for assuring a safe working condition of a dry gas seal when a pump/compressor is in a standstill condition. A small booster compressor is added to boost the pressure of an intermediate buffer gas injected into the chamber between a primary seal and a secondary seal of the dry gas seal. Control components detect when the barrier gas pressure drops below a preconfigured value and when detected, closes a valve in a line to a flare safe area and turns on the compressor. The boosted intermediate buffer gas, Nitrogen or dry air, slows the flow of untreated process gas through the primary seal of the dry gas seal and prevents icing of the primary seal.

What is claimed is: 
     
         1 . A system for assuring a safe working condition of a dry gas seal, associated with a pump or a compressor, during standstill operating conditions, the system comprising:
 a barrier fluid pressure detector configured to determine when barrier fluid pressure of a barrier fluid drops below a preconfigured lower limit and when said pump or said compressor, at said standstill operating condition is pressurized at a settle-out pressure;   a controllable valve connected to a chamber between a primary seal and a secondary seal of said dry gas seal, said controllable valve associated with a vent to a flare-safe area;   a booster compressor configured to boost the pressure of an intermediate buffer gas injected into said chamber; and   a control system configured to operate said controllable valve and said booster compressor based on said barrier fluid pressure.   
     
     
         2 . The system of  claim 1 , wherein said controllable valve is associated with a flare line connected to said dry gas seal. 
     
     
         3 . The system of  claim 1 , wherein said barrier fluid is carbon dioxide. 
     
     
         4 . The system of  claim 1 , wherein said intermediate buffer gas is Nitrogen. 
     
     
         5 . The system of  claim 1 , wherein said intermediate buffer gas is dry air. 
     
     
         6 . The system of  claim 1 , wherein said booster compressor boosts said pressure of the intermediate buffer gas to a preconfigured pressure when said barrier fluid pressure drops below said preconfigured pressure. 
     
     
         7 . The system of  claim 6 , wherein said preconfigured pressure is less than a pressure of an area to be sealed associated with said dry gas seal. 
     
     
         8 . The system of  claim 6 , wherein said preconfigured pressure is greater than a pressure of an area to be sealed associated with said dry gas seal. 
     
     
         9 . A method for assuring a safe working condition of a dry gas seal associated with a liquefied gas pump or a liquefied gas compressor when said liquefied gas pump or said liquefied gas compressor is in a transient operating condition, said method comprising:
 detecting a barrier fluid pressure below a preconfigured value;   closing a valve connected to said dry gas seal; and   starting a booster compressor associated with an intermediate buffer gas and maintaining said buffer gas pressure at said preconfigured value.   
     
     
         10 . A system for protecting a dry gas seal associated with a liquefied gas pump or a liquefied gas compressor, said system comprising:
 a barrier fluid pressure detector configured to detect when a pressure, associated with a barrier fluid injected into said dry gas seal, drops below a predefined lower limit;   a controllable valve configured to regulate flow from said dry gas seal to a flare-safe area;   a booster compressor configured to change pressure of an intermediate buffer gas injected into said dry gas seal;   a chamber pressure detector configured to measure pressure in a chamber between a primary seal and a secondary seal; and   a control system configured to control said controllable valve to regulate flow and said booster compressor to change pressure based on said the measured pressure in the chamber and a preconfigured pressure value.   
     
     
         11 . The system of  claim 10 , wherein said controllable valve is associated with a flare line connected to said dry gas seal. 
     
     
         12 . The system of  claim 10 , wherein said barrier fluid is carbon dioxide. 
     
     
         13 . The system of  claim 10 , wherein said intermediate buffer gas is Nitrogen or dry air. 
     
     
         14 . The system of  claim 10 , wherein said booster compressor boosts said pressure of the intermediate buffer gas to a preconfigured pressure when said pressure of the barrier fluid drops below said preconfigured pressure. 
     
     
         15 . The system of  claim 2 , wherein said barrier fluid is carbon dioxide. 
     
     
         16 . The system of  claim 15 , wherein said intermediate buffer gas is Nitrogen or dry air. 
     
     
         17 . The system of  claim 16 , wherein said booster compressor boosts said pressure of the intermediate buffer gas to a preconfigured pressure when said barrier fluid pressure drops below said preconfigured pressure. 
     
     
         18 . The system of  claim 2 , wherein said intermediate buffer gas is Nitrogen or dry air. 
     
     
         19 . The system of  claim 18 , wherein said booster compressor boosts said pressure of the intermediate buffer gas to a preconfigured pressure when said barrier fluid pressure drops below said preconfigured pressure. 
     
     
         20 . The system of  claim 2 , wherein said booster compressor boosts said pressure of the intermediate buffer gas to a preconfigured pressure when said barrier fluid pressure drops below said preconfigured pressure.