The solution

We offered a four stage IGC with inlet guide vanes on the 1st and 3rd stage, the complete scope entitled also inter-stage and after coolers, auxiliary systems and operating panels, a main electric motor and a turbo expander.

The main electric motor was a HCKD motor with a two end shaft, one end connected to the integrally geared compressor and the other end to the turbo expander. The maximum power of the driver is 2.6 MW.

The total increase of pressure ratio between compressor suction and discharge is split on the 4 compression stages. Change on the 3 first stages has very limited impact and is all compatible with piston stages initial design. Therefore the 3 first stages of compression can remain unchanged.

The integrally geared turbo expander is connected to the shaft of the main motor, which means that when the turbo-expander is in operation, the power generated is used to support the rotating power of the shaft on the main driver, and as such it reduces the amount of power required to drive the compressor.

During start-up the turbo expander is not in operation, after some time when the process on the plant is in full operation the waste gas after the process is transferred to the turbo expander. When the plant and the turbo expander is in full operation it enables the driver to reduce the required power with approximately 50%.

The conclusion

This supplied IGC operates from atmospheric pressure and has a final discharge of 14bar, with a capacity of 19.500m3.h it requires a 2.6 MW driver and the turbo expander can save up to 50% of the required power.

The compressor and turbo expander have been in operation since 2007, that is more than 10 years without any unplanned stops. The power savings of the complete supplied train over 10 years are in the region of 110.000MW/h.