Device and Method for Evacuating a Chamber and Purifying the Gas Extracted From Said Chamber

Abstract

A device evacuates a chamber and purifies the gas extracted from said chamber of any foreign substances. The device comprises a dry-condensing vacuum pump having an input connected to the chamber to be evacuated and is suitable for maintaining the input pressure at a constant level at the output despite variable conditions. An intermediate line which connects to the output of the dry-condensing vacuum pump and a liquid ring vacuum pump, the input of which is connected to the intermediate line, are additionally provided. A corresponding method makes it possible to purify the gas of any foreign substances reliably and effectively.

1 . A device for evacuating a chamber and for purifying a gas that is extracted from the chamber of entrained foreign substances comprising:
 a. a dry-compression vacuum pump having a chamber to be evacuated, an inlet connected to the chamber to be evacuated and an outlet and which is suitable for keeping the inlet pressure constant despite variable conditions at the outlet;   b. an intermediate line which connects to the outlet of the dry-compression vacuum pump; and   c. a liquid ring vacuum pump, having an inlet connected to the intermediate line.   
     
     
         2 . The device as claimed in  claim 1 , characterized in that the dry-compression vacuum pump is designed to generate a pressure of between 1 mbar and 40 mbar at the inlet side. 
     
     
         3 . The device as claimed in  claim 1 , characterized in that the dry-compression vacuum pump is designed to generate a pressure of between 80 mbar and 300 mbar in the intermediate line. 
     
     
         4 . The device as claimed in  claim 1 , characterized in that an opening for the supply of scavenging gas is provided at the outlet of the dry-compression vacuum pump and/or in the intermediate line. 
     
     
         5 . The device as claimed in  claim 4 , wherein the dry-compression pump has a housing characterized in that the opening is a gap that exists between a shaft and the housing of the dry-compression vacuum pump. 
     
     
         6 . The device as claimed in  claim 1 , characterized in that the liquid ring vacuum pump has an operating liquid and is provided with an inlet and an outlet for the operating liquid, which inlet and outlet permit an inflow and outflow of the operating liquid during the operation of the liquid ring vacuum pump. 
     
     
         7 . The device as claimed in  claim 1  wherein the operating liquid has a conductivity, characterized in that a sensor is provided for determining the conductivity of the operating liquid. 
     
     
         8 . The device as claimed in  claim 6  wherein the operating liquid has an inflow and an outflow and a concentration of foreign substances, characterized in that a control device is provided which adjusts the inflow and the outflow of the operating liquid as a function of the concentration of foreign substances in the operating liquid. 
     
     
         9 . The device as claimed in  claim 1 , characterized in that the operating liquid of the liquid ring vacuum pump contains a solvent which is coordinated with the foreign substances contained in the gas. 
     
     
         10 . The device as claimed in  claim 1  wherein the operating liquid has a pH value, characterized in that a pH sensor is provided for determining the pH value of the operating liquid. 
     
     
         11 . The device as claimed in  claim 10  wherein the sensor determines measurement values, characterized in that a control device is provided which is designed to adjust the pH value of the operating liquid as a function of the measurement values from the pH sensor. 
     
     
         12 . The device as claimed in  claim 1 , characterized in that a combustion device is arranged in the intermediate line. 
     
     
         13 . A method for evacuating a chamber having a gas with entrained foreign substances and for purifying the gas that is extracted from the chamber of entrained foreign substances, having the following steps:
 a. drawing the gas having a pressure out of the chamber;   b. increasing the pressure to a value below atmospheric pressure, wherein a pump is used which pump has an inlet pressure and an outlet pressure and is suitable for keeping the inlet pressure constant even if the outlet pressure is variable;   c. conducting the gas onward to a liquid ring vacuum pump which outputs the gas at atmospheric pressure.   
     
     
         14 . The device as claimed in  claim 1 , characterized in that the dry-compression vacuum pump is designed to generate a pressure of between 2 mbar and 30 mbar at the inlet side. 
     
     
         15 . The device as claimed in  claim 1 , characterized in that the dry-compression vacuum pump is designed to generate a pressure of between 5 mbar and 20 mbar at the inlet side. 
     
     
         16 . The device as claimed in  claim 1 , characterized in that the dry-compression vacuum pump is designed to generate a pressure of between 100 mbar and 150 mbar in the intermediate line. 
     
     
         17 . The device as claimed in  claim 2 , characterized in that the dry-compression vacuum pump is designed to generate a pressure of between 100 mbar and 150 mbar in the intermediate line. 
     
     
         18 . The device as claimed in  claim 2 , characterized in that an opening for the supply of scavenging gas is provided at the outlet of the dry-compression vacuum pump and/or in the intermediate line. 
     
     
         19 . The device as claimed in  claim 3 , characterized in that an opening for the supply of scavenging gas is provided at the outlet of the dry-compression vacuum pump and/or in the intermediate line. 
     
     
         20 . The device as claimed in  claim 2 , characterized in that the liquid ring vacuum pump has an operating liquid and is provided with an inlet and an outlet for the operating liquid, which inlet and outlet permit an inflow and outflow of the operating liquid during operation of the liquid ring vacuum pump.