Waste gas recovery systems

In a waste gas recovery system with inlet means for receiving the waste gas, a compressor connected to the inlet means, serving to compress the waste gas and outlet means connected to the compressor and cooling means at the outlet means, the outlet means serving to discharge the compressed waste gas;

• the improvement comprising:
• means for driving the compressor at a selectable speed, first sensing means for sensing the pressure of the waste gas at the inlet means and for controlling the drive means to drive the compressor at a speed commensurate with the sensed pressure, second sensing means for sensing the temperature at the outlet of the compressor and valve means in communication with the outlet means downstream of the cooling means and controlled by the second sensing means and operable to re-cycle gas from the outlet means to the inlet of the compressor in the event that the sensed temperature exceeds a pre-determined value.

A waste gas recovery system comprising inlet means for receiving the waste gas, a compressor with an inlet connected to the inlet means to receive the waste gas, valve means connected between the inlet means and the inlet of the compressor, outlet means connected to an outlet of the compressor to discharge the compressed waste gas, drive means for driving the compressor at variable controlled speed, means for sensing the pressure of the waste gas at the inlet means and for controlling both the valve means and the drive means in accordance with the sensed pressure, means for sensing the temperature of the waste gas at the outlet of the compressor and temperature control means responsive to the temperature sensing means and operable on the gas fed to the inlet of the compressor in the event that the sensed temperature exceeds a pre-determined value to reduce the temperature of the gas at outlet of the compressor.

In a waste gas recovery system with a compressor serving to compress the waste gas;

• an improved method of control which comprises sensing the pressure of the gas fed to the inlet of the compressor, sensing the temperature of the gas leaving the outlet of the compressor, controlling the drive speed of the compressor in accordance with the sensed pressure and successively controlling separate valve means to inject liquid coolant into the gas fed to the inlet of the compressor and to re-circulate gas from the outlet to the inlet of the compressor at pre-determined sensed temperature values.