Air System

Here is something interesting to discuss on how to design air system in term it's capacity. It's basically on how to determine user's consumption. Users can be continuous users and intermittent users. Continuous users easily can be estimated since these users are consume continuously and no need to consider on oversizing the air system. However, there is some confusion in intermittent users. There are two different approaches in estimating the consumption for these users when designing air compressors. This intermittent users also classified as dynamic users sometimes. The first approach is by putting some weightage to the different users in percentage which will give lower consumption per unit user; it shows that the consumption is not fully utilized all the time. The second approach is by taking three single largest users without multiplying with any weightage. This is something very hard to clarify because of the subjectiveness. Lastly, any comments or criticisms are most welcome for our all understanding improvement.

Pressure Drop - Part 2

In the previouse article, I wrote about good and bad pressure drop and briefly explained about why we care about it from the beginning stage and while operating the plants or facilities. Here I'll further share about how can we utilize the pressure drop.

The pressure drop again as highlighted in previous article is actually due to the friction along the piping. In the meantime, it is not a significant losses relative to equipments. As we all aware there is allowable pressure drop for all the equipments such a way that pumps or compresssors can be sized properly to reach destination pressure. All the equipments need to be sized so that the pressure drop calculated is not beyond the allowable pressure drop. How does usually this pressure drop is affected or can affect the size/design of equipment? It is exactly same as happen to piping but than much larger pressure drop relative to friction losses. So, it is actually same principal where the friction losses inside the equipment as higher velocity will give higher losses. For new design, the equipment can be designed so that the calculated pressure drop lower than allowable. Unfortunately, what would happen if the equipment designed is giving higher pressure drop than allowable? How it can be rectified? Does it mean that the whole equipment need to be revamped?

Pressure Drop

What do we know about pressure drop? What is all about? Where do we see this pressure drop? Is it a harm or benefit? How to differentiate between good and bad pressure drop? Why do we need pressure drop? Where do we need it? When do we need it? Why is that so important to consider the pressure drop? What is the difference between allowable and calculated pressure drop? How pressure drop can be manipulated in order to get the optimum performance of equipments?

As we all know pressure drop occur due to friction factor and it can't be zero but can be minimised as happen to fouling. Similarly the pressure drop can be minimised as much as possible by using very smooth material of pipe. However, this is not practicale to use very smooth material of pipe or equipment since it would not be feasible economically for large configuration of plants or processing facilities. So far while this para, people might think about the harm and benefit of pressure drop and obviously only the bad thing can be seen so far as it all talk about how to minimise it.

Here is the time to talk about good and bad pressure drop. The pressure drop again needs to be defined properly so that can differentiate between good and bad. These good and bad actually reflecting to the allowable and calculated pressure drop. We should know how to manipulate the pressure drop so that good pressure drop can be gained. Before the good and bad pressure drop can be explained further, the allowable and calculated pressure drop need to be understood correctly. In direct way, substraction of the allowable and calculated pressure drop dictating the pressure drop is a good or bad pressure drop. Do you have any idea on this? Usually if calculated pressure drop is higher than allowable pressure drop, then, the excess pressure drop is considered as bad pressure drop. This scenario is further explained later by referring to an example.

The allowable pressure drop usually is defined from overall allowable pressure drop of the system/unit/line. This system, unit, or line can be defined starting from discharge point of pump or compressor to the destination point. So, the allowable pressure drop can be defined as substraction of discharge pressure and destination pressure. Greater the deviation between these values, better the allowable pressure drop. However, it is not economical to design very huge margin of allowable pressure drop. So, have you got an idea how this allowable pressure drop can be considered as good pressure drop? Let us explore!

Glycol Package

What is the real function of glycol package? Why do we need this? Is that necessary to have this? Where it is located? Onshore? Offshore? What are the parameters that actually affect the performance of the glycol package which consists of glycol contactors and it's glycol regeneration skid? What do we expect if the feed conditions change in term of the performance of overall of glycol package? What should we do in order to get the optimum performance? When talk about performance, what are the parameters actually can be measured in order to get optimum performance? Which area that can be studied further if there is change in feed condition? What is the benchmark when do the optimisation?

There are lot of questions that can be raised for only simple package (I would say) compared to any other process technologies. Some people might say that first couple of questions is very fundamental relative to oil and gas industry. However, we should bear in mind that there might be some people never came accross in this glycol package before. Sometime different discipline might not really aware of this since they concern might be same regardless of the operation.

Overall picture of this glycol package can be read from GPSA section 20. However, those interested with the topic in surface and want to via this article and comment. You can do so. Experienced guys are welcomed to share their experience during designing or operation of this glycol package and very much appreciated.