What is the role of the pre-lifted dry gas at the bottom of the catalytic reactor tower?
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What is the purpose of pre-raising dry gas at the bottom of a catalytic reactor tower? What does the size of its traffic affect? Does it have some impact on coking? Why is the pre-heated dry gas changed to steam during shutdown?
Using dry gas as a lifting medium to give the catalyst an appropriate velocity and density before it comes into contact with the feed oil facilitates thorough mixing between the catalyst and the oil in the reaction zone, reduces the amount of steam required and the volume of wastewater generated, and minimizes the hydrothermal deactivation of the catalyst. The magnitude of its flow rate has a certain impact on the catalyst circulation rate in the lift pipe; it cannot be proven to accelerate coking, as there are many factors that contribute to coking
Using dry gas as a pre-lift, studies have shown that it can deactivate heavy metals and reduce heavy metal pollution. When there is a large margin in the compressor, steam consumption can be reduced. I have a question for the experts: are your catalytic devices used for gas atomization?
1. Using dry gas as the lifting medium allows for savings in steam consumption and reduced energy use when there is a sufficient surplus of pressure in the compressor, as well as a decrease in the discharge of sulfur-containing wastewater. 2. It can reduce the steam partial pressure of the feed to the riser, thereby minimizing the hydrothermal deactivation of the high-temperature catalyst. 3. It can passivate heavy metals and reduce heavy metal pollution. It can reduce the yields of gas and coke, while increasing the octane number of catalytic gasoline.
Pneumatic conveying is used to accelerate the catalyst. Dry gas is employed in place of steam; this serves two purposes: it helps to reduce steam consumption and it also helps to preserve the catalyst’s activity and temperature.
The flow rate for the pre-lift of dry gas is determined by the surplus capacity of the compressor. During shutdown, the compressor is taken out of service or shut down, and the absorption stabilization system maintains pressure; therefore, the pre-heated dry gas must be replaced with steam.
Pre-heated dry gas – there should be two concepts here! One is pre-rising, which accelerates the catalyst to prepare for the short contact time in the riser; from this perspective, it may have an inhibitory effect on coking, as it reduces the contact time. One is dry gas, which eliminates the need for steam and thus saves costs; moreover, and perhaps more importantly, it reduces thermal inactivation at high temperatures, protecting the molecular sieve
The main purpose of using dry gas as a pre-lifting medium is to give the catalyst a certain velocity and uniformity before it comes into contact with oil and gas. Steam can also be used, but dry gas helps reduce wastewater emissions. It doesn’t seem that there’s any known impact of it on coking
Wow, there are also those that use dry gas for atomization? I haven’t seen it. Using steam as the lifting gas can cause hydrothermal deactivation of the catalyst; if the compressor load permits, it is better to use dry gas.
In our plant’s catalytic cracking unit, pre-heated dry gas is indeed used; of course, in addition to dry gas, steam is also used. It is the mixture of the two that is fed to the bottom of the lift pipe.
Everyone was very engaged in the discussion. As a student at the Petrochemical University, it was actually the first time I heard about the use of dry gas stripping; I learned a great deal from the posts posted above!