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Material Balance for Process Involving Recycle

Recycle process is process in which a flow stream is returned to an earlier stage in the processing stage. The process is frequently used in the production facility. If the conversion of valuable reactant is considerably less than 100%, the unreacted material is usually separated and recycled. An example of a recycle process in which there is no reaction is the return of the reflux to the top of distillation column.

What do you think about the existence of recycle in material balance calculation?

In my opinion, recycle makes material balance calculation is more difficult. In this post, we will learn material balance for process involving recycle. I hope it will give you a little insight.

Without recycle process, the material balances are simple. The material balance can be carried out in serial, in which the calculated flows out of one unit become the feeds to the next. But if a recycle stream is present, then at the point when the recycle is returned, the flow will not be known as it will depend on downstream flows not yet calculated. Without knowing the recycle flow, the sequence of calculations cannot be continued to the point where recycle flow can be determined. Read More

calculation holding time of LNG in storage tank

Predicting Holding Time of LNG in Storage Tank Without Venting

In this post, we use vacuum insulated type LNG storage tank when we don’t want to deal with boil-off gas handling. The storage tank have design pressure as high as 6-10 barg. When we store LNG in the LNG, boil-off gas will be generated due to heat leak to tank. Increasing temperature of LNG will increase total volume of LNG and vapor in the tank, thus increasing its pressure.

This phenomena leads to a simple question, “How long can LNG storage tank keep the vapor before PSV works?” Read More