Catalytic start-up
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How is it possible to start up a catalytic process without using a flare?
Before starting the injection of fuel in the unit, the fractionation system is filled with gas, and the air compressor is started. The reaction pressure is controlled by backflow at the outlet of the air compressor. After fuel injection for the reaction begins, the amount of gas increases, causing the backpressure of the air compressor to rise above the stable pressure level, after which it is fed into the stabilization system.
Warm up the pipes of the press before feeding, start it in rotation, and increase the speed after feeding begins
These days, in many cases, flares are not used or only a small number of flares are used during operation. This involves starting the compressor to operate at low speed before injecting oil, and using the flare at the compressor outlet to control pressure; once the desired pressure is reached, the valve at the compressor outlet is opened to stabilize the pressure. As the amount of oil flowing into the lift pipe increases, the speed of the turbine is gradually increased as well
Not starting up the unit without activating the flare system is not just a matter of utilizing the reverse flow path; the gas phase that reaches the compressor inlet after feeding in also does not arrive there immediately – it needs to do so gradually. Even if the reverse flow path is fully activated, it still takes some time, as it is necessary to ensure that the compressor does not experience surge
Most importantly, some units have now installed a start-up gas line in front of the distillation tower top air cooler; this line supplies additional gas to compensate for the amount of gas entering the compressor, thereby preventing surging and ensuring that the compressor can start up in an orderly manner.