3 replies to this topic

[Bunturng]

Dear all,


I have some reluctant between to buy the dimple jacket mixing tank and half pipe coil jacket tank and I found some article and also described our routine work as below if your guys have some experiences or knowledges about this problem please kindly comment or share your idea :-

My pharmaceutical factory need a mixing tank with cooling jacket which every day it has to sterile the internal by the pure steam (121 deg C) to sterile the tank surface prior to pour the hot water(80 deg C) into the tank but as attached article said that " the rapid temperature change causes an equal rate of thermal expansion between the vessel wall and the dimple jacket resulting in high operating stresses in the dimple jacket and vessel material and welds. Thermal shocking also cause damage to other dimple jacket or vessel attachments. Thermally shocking dimple jackets and/or vessels will shorten the service life significantly and may cause unscheduled down time and costs."

From the article, I am wondering that this will happen or not if we use the half pipe coil jacket?

Thank you in advance for everyone comment or reply.

Best regards

[Art Montemayor]

Bunturng:

Wherever there is a scope of work that calls for preheating a vessel and its contents as quickly and efficiently as possible, I definitely DO NOT RECOMMEND:

• An external dimpled jacket on the vessel;
• A half pipe heating/cooling jacket on the vessel;
• Any jacket on the vessel.

Unless you have another valid and important reason in your scope of work, I see no reason to depend on such inefficient, costly, and insufficient heat transfer in any process. There are much better, more efficient, more dependable, and predictable methods available to carry out batch heat transfer operations.

Unless you definitely require an internal heat transfer surface that is small, plane, and quick to clean and sterilize, then you don’t need an external jacket. And if you do, then a straight, common jacket with baffles is what I would use. However, when you resort to a jacket for heating or cooling a vessel you are at the mercy of very inefficient heat transfer.

My field experience verifies the expensive maintenance and upkeep of dimpled and half-pipe jackets. The half-pipe is the worse example for very expensive manual welding, deformation, stresses, high velocities, high pressure drops, expansion problems, corrosion, weight, etc..

You don’t tell us any basic data (such as fluids, size, agitators, time, sketch, materials, etc.) so we really can’t offer any specific recommendations. If you need or want specific comments and recommendations you should do your part and furnish all the basic data.

[Bunturng]

Dear Montemayor,

Thank you very much for your reply.

Yesterday I may not explained well,

The mixing tank has to sterile the internal of the tank by direct pure steam at 121 deg C for 20 minutes and then pour the serile water (80deg C) then cool down the hot sterile water from 80 deg C to around 30-35 deg.C. So, why we need the cooling jacket. And I found the article as attached (yesterday I might made mistake to attach the file then you did not get it).

And the other factor that we have to concern is the mixer will be installed in the clean room and very difficult to repair, so, it has to be durable

In case that we have to install the heat exchanger, which option is better choice between dimple jacket and half pipe coil but if both is not ok what type should be? (plate and frame heat exchanger is not recommended for sterile pharmaceutical process)

Thank in advance for your recommend.

Best regards

Bunturng  dimple jacket temp shock.pdf   45.79KB   1121 downloads

[Art Montemayor]

Bunturng:

Without any knowledge of your basic Scope of Work, I can’t make any serious, specific recommendations or suggestions. I thought I was very specific in pointing out that fact in my last sentence in my last post. Without knowing what you want (or need) to accomplish, we can’t make any specific comments or responses to your general and un-defined queries. I want to help you, but you make your life difficult by not sharing what you know with us.

I have had experience in batch processing – especially working with chemists and their ideas of what a process should have or how it should be designed. I can tell you from personal field experience that chemists do not belong in the engineering field without having hands-on experience in the design and operating field. Chemists are the ones who “rule” in the research and development of fine chemicals, pharmaceuticals, and other specialty chemicals. But in the production plant, they are basically useless individuals because they lack the training or expertise on how to make a process work SAFELY, EFFICIENTLY, ECONONOMICALLY, and CONSISTANTLY. Those skills are not in their training and they know it. That is why they cannot be held liable for process results out in the plant. That is OUR job.

To a chemist, a heating or cooling jacket is a heat exchanger. To an engineer, a jacket is nothing more than a “token” attempt” to keep liquid contents stable at a given temperature – and never meant to industrially, economically, and efficiently carry out a required process heat transfer. A chemist knows little and cares nothing about process heat transfer, film coefficients, and driving forces. Production economics are beyond a chemist’s experience.

If possible, I would stay away from employing any jacket on a process vessel – especially one that is reliant on fast heat-ups and cool-downs. What your submitted file says is exactly what I have personally experienced out in the field. That is why I am adamantly against dimpled jackets. I repeat what I stated previously: There are much better, more efficient, more dependable, and predictable methods available to carry out batch heat transfer operations.

But we have to know what it is that we are trying to accomplish before citing any methods, processes, answers, or recommendations.

I hope that I have been clear in my response and that we can be of help to you.