Heat Exchanger Cleaning & Maintenance - GASKETs

Continuation from previous post...

You can either dismantle all the plate and frame heat exchanger OR you do the chemical cleaning. Well, i can say the decision must be correct. You must decide which method to chose.

If you decide to dismantle the heat exchanger and heat exchanger tubes, this will give you the highest cost impact. Why? This is because, when you dismantle the plate & frame heat exchanger, the gaskets in between the plates cannot be used anymore. Once the heat exchanger is opened, it can't be used again. The polymer structure of the gasket has already be distorted and is not in a prefect condition to be used again. By the time you open the heat exchanger, some of the gasket, might also be damaged too. Some of them have became very thin. Some of them have been torn. There are many types of condition. And most of the time, oil leaks in the heat exchanger is due to the gasket problem or the operator/technician did not fix the gasket properly on plate heat exchanger.

Example of a gasket to be placed in between the heat exchanger plates

A cleared picture of how the gasket is inserted and attached to the plates

One set of gasket to be placed in between two plates is very expansive. Depending on what type of heat exchanger, type of plates, type of oils/fluids flowing, and also range of operating temperature. This information can be obtain from a gasket or heat exchanger supplier/manufacturer. So, imagine if the plate and frame heat exchanger have 220 plates, you must have 221 gaskets placed in between the plates and the two stainless steel frames on both ends.

Heat Exchanger Cleaning

You have a plate and frame heat exchanger in your plant. The heat exchanger have been in operation for perhaps one year already. By this time, the efficiency have dropped. The heat exchanger cannot provide you the desired output temperature when they heat exchange.

How do you know this? You can know by seing the output temperature of both fluid ie the cold fuild and the hot fluid. If the output cold fluid temperature has increased and the output hot fluid temperature has decreased, then this are the sign of some sort of inefficient heat exchange situation. Why is this happening?

You can also check the pressure of the input hot or cold fluid, ie if the pressure increased, it is a sign of something called "fauling" which resulted in the heat exchange becoming inefficient. Yes, fauling is one thing that most of the time caused the heat exchanger to be not working optimumly.

All of these are just part of what you can notice and experience on your plate and frame heat exchanger. When this happen, you might want to consider removed the fauling from the plates.
But how? You have to options. You can either dismantle all the plate and frame heat exchanger OR you do the chemical cleaning. Well, i can say the decision must be correct. You must decide which method to chose. Because both will have direct impact on your production and/or operation and/or maintenance cost. So, you don't want to be caught making a bad decision by your superior!!! Ok. Let's continue in the next post....got more to tell....

My first Heat Exchanger Encounter....

It was in my third working place that i learn and have better comprehension about the heat exchanger. There are various types of heat exchanger in plant. We have plate and frame heat exchangers, shell and tube, spiral cooler and others.

The first time i get to know a plate and frame heat exchanger was when i was instructed by my boss to supervise a group of technicians and contract worker fixing and installing about 233 plates onto a heat exchanger frame. It was not an easy job. The task was very physically demanding.

Plate & Frame Heat Exchanger - Hot fluids flow down between alternate plates, cold fluids flow up between alternate plates (Adopted from Perrys Chemical Engineering Handbook: Thermal division Alfa LAval, Inc)

While performing this task, we have to be careful of the plates arrangement. We have to be carefull of the numbers and quantity of the plates. I have witness one time, these people accidently missed out one plate, which can result in the 2 types of oil cannot pass through. Thus, upsetting the initial intention of heat transfer. As soon as they realized that they miss out one plate, they decide to put another extra plate in between to continue the path of the two oils not to be blocked. Well, that's ok. But, they need to be careful next time. Not to be careless and repeat the same mistake.

The technique to tightened the plate and frame heat exchanger must be correct. We must tighten it in a criss cross manner and in the same time take the measurements of all the bolt length. The tightening length must be the same for all 8 bolts (if there is 8 bolts).

There are still a lot more to tell about the hidden information of heat exchanger.....i mean the type of information and knowledge that is not written in the text book. The one that we can only know and get it from experience and other peoples experience. I'll share some of my experience of dealing with heat exchanger from time to time. I sincerely hope the information will be beneficial for those who want to learn and know more about heat exchangers, heat transfer.