Preheating issue of the gas turbine in catalytic cracking units
Thread Content
In a catalytic cracking unit, for the preheating of the flue gas, is steam used at the beginning, or flue gas?
This is how we do it here; it’s for reference only!
Our plant uses flue gas for warming up; the shut-off butterfly valve and the control butterfly valve are equipped with warming-up wires. Adjust the warm-up temperature of the flue gas turbine using the cross-line valve opening.
Is it more scientific to preheat first with steam or with flue gas? What are the advantages and disadvantages?
Our company uses flue gas for preheating. Due to a slight leakage in the butterfly valve at the inlet of the flue gas fan, no adjustments are made to this valve during the preheating process; instead, the inlet valve of the flue gas fan is gradually opened until it is fully open, thereby carrying out the preheating
It can be said that there are advantages and disadvantages in both cases; it comes down to which option is more reasonable, or whose advantages outweigh its disadvantages! Personally, I think it’s more reasonable to use gradually increasing smoke temperature: 1. It is after all the medium under actual operating conditions. 2. It is more convenient to operate.
First, use a wheel to cool the steam and gradually increase the temperature for startup; the condensate drain valve must be opened； When the temperature rises to over 200, turn on the exhaust fan to preheat the auxiliary line; use the manual valve to control the rate of temperature increase, check the preheating condition of the exhaust fan itself, and verify whether the heating and stretching are uniform as well as whether there are any leaks
In any case, you still have to turn on the steam cooling wheel; using flue gas directly is an option, but since the temperature of flue gas is high and the valves are too large, it’s difficult to control the rate of temperature increase
In fact, many times it’s just a habit; aren’t there already a few organizations using it?
Some units use flue gas, while others use steam; each has its advantages and disadvantages. For smoke generators that lack a preheating system, steam preheating is often used, but I believe this can lead to catalyst clogging, which is detrimental to the operation of the smoke generator. It is recommended to use a preheating line for warming up, as it is better to control the rate of temperature increase