05.11.2019.

Why Is The Pinch Analysis One Of The Most Important Methods For Energy Efficiency Improvement? Pinch Method As The Powerful Technique for Energy Efficiency Improvement, Process Integration and Optimization

Ivana Lukec, Ph.D.
Why Is The Pinch Analysis One Of The Most Important Methods For Energy Efficiency Improvement?
Maintaining good performance of the heat exchanger networks is a major part of an energy efficiency program and pinch analysis is a brilliant technique to do that because it is both simple and practical. However, the pinch method is way more applicable than just optimizing heat exchanger networks.
 
There are some questions that very often pop-up when talking about pinch analysis. Here, I want to target a few most important ones.
 

First of all, why is the pinch method so effective?

I was dealing with this question for some time a couple of years ago. Because I thought, optimization is optimization - why would you need to call it "pinch analysis"? You just do a normal optimization anyway. 
That was my thinking until the project that came along needed employment of exact this technique. Of course, what happened was A-HA moment after I looked into the composite curves and I finally figured out what it was all about. When you take a look into the composite curves, pinch point etc. you also see the process from a different perspective. I started seeing the energy efficiency problems from another point of view.
 
The pinch method is very practical and a simple technique! However, applying it with success needs practice and knowledge. Ones you are able to use the methodology, it gives you wider and more insightful point of view to energy efficiency in general.
 
A skeptic would say something similar as I just mentioned:
 

Why should these methods show a step change over the many years of careful design and learning by generations of highly competent engineers? 

 
The thing is that, to achieve optimality in most cases, some insights are needed which are neither intuitively obvious nor provided by common sense. They are simply the result of a pinch way of thinking. Because the way you see hot and cold stream is different.
 
Another question is also:

Isn’t the pinch analysis only applicable to oil refineries and large bulk chemical and petrochemical plants and maybe not to my process?

 
In fact, experience has shown that this is far from true – the pinch analysis can bring benefits in a huge range of plants and industries, large and small, both within and outside the “traditional” process industries.
 
Let's name just a few:
  • Crude Distillation Unit - that is an example of a large refinery unit, but deserves the fist position because that's the unit where pinch analysis was first applied decades ago.  Pinch method is hugely applicable for Crude Distillation Units and can bring significant improvements and savings.
  • Breweries - There are studies showing how more than 20% of energy can be saved with application of pinch methods on a typical brewery. There are a lot of beer producers, right?
  • Whiskey distilleries - The majority of whiskey production is grain whiskey produced in the large-scale continuous processes. These distilleries have an excellent record of waste minimization in general. However, thanks to the application of pinch analysis, several of the largest distilleries have also optimized their energy systems and achieved considerable overall savings. 
Other examples include:
  • cement production,
  • sugar production,
  • desalination,
  • organic chemicals production,
  • petrochemical units,
  • refinery units etc.

Pinch method is only about heat exchanger networks, isn’t it?

 
That’s the coolest thing – no, it’s not!
However, that's a common response from people who’ve heard about the technique in the past. But the fact is that improvements come not only from heat recovery projects, but also from changing process conditions, improved operability and more effective interfacing with utility systems, all underpinned by better process understanding. Pinch analysis has broadened
a long way beyond the original studies. It is now an integral part of the overall strategy
for process development and design, often known as process synthesis, and the
optimization of existing plants.
 

I need to use a special and expensive tool to practice pinch analysis?

No, you don't neceserily need it. There are many good tools on the market specialized for pinch analysis that are good to have. However, first pinch analysis, done on the Crude Distillation Unit, as mentioned above, used none of the tools. For the first analysis, engineers even did not have enough time to use a process simulator. They only used material and heat balances from the real data and did their own spreadsheets and pinch calculations. 
The pinch analysis can be done in this was today if there are no affordable tools. 
However, it is good to use a process simulator for the purpose of building your own material and heat balances. There are different process simulators available on the market today, from open source to highly professional tools. About the calculation tools, you can read more at the link.
 

Should I learn about energy efficiency improvement with pinch method?

It is an investment in yourself. Energy efficiency improvement is one of the most important topics of every industrial process today. If you work in the industry, having the pinch analysis knowledge can help you contribute to your own team to find improvements in energy efficiency.

If you are developing your own business in chemical engineering, the course will give you hugely important knowledge that can open up new opportunities in targeting, analyzing and solving energy efficiency problems.
With the 4-week online course "Improvement of energy efficiency with pinch method: from idea to solution", you will learn: 
  • How to identify and approach opportunities for process heat recovery,
  • How to execute heat recovery assessment and develop optimized solution,
  • Steps in development of pinch method applicable across industries,
  • How to develop a study to present the business case,
  • How to use your knowledge to develop you own consulting business.

To find out more information and apply for the course, follow this link.