Heat integration: How does it work?

Heat integration: How does it work?

Reuse heat

Many (industrial) companies do not realise that heat can be reused. Heat is often used to temporarily heat something. This heat is then lost by cooling the product down. This happens a lot within i.e. the food industry. It is interesting to see whether this residual heat can be put to good use within the process. Reusing this heat is called heat integration. The question then is, how can this be done in a convenient way? For this the pinch method was invented. A simple and effective approach to conveniently match the heat demand and heat surplus. In 4 steps to a more sustainable process.

Step 1: available heat and heat demand

In order to do heat integration efficiently, it is important to know how much heat is available and demanded within a company.  That is why we first map out the available heat and the demanded heat flows. For this we use a so-called pinch curve. In addition to the available heat, this pinch curve also includes cooling in the overview.

Using this curve, we can determine the minimum heat and cold consumption. Drawing up this curve requires mapping out all heat and cold flows. Process and production times are also important here. The pinch curve is based on continuous processes, but by using heat buffering you can also include batch processes. As it is less convenient to thermally link flows that are far apart, we also determine the locations of all flows.

Step 2: Heat exchanger analysis

Based on this analysis, the heat exchanger network is designed. We indicate which type of heat exchanger is the best choice,  and what the investment costs and returns are. In this analysis we also include the influence on the process. Savings options that are more economical and also shorten the turnaround time are, of course, most likely to be implemented.

Step 3: Upgrading residual heat

Then we look at the use of heat pumps. Here we will investigate whether residual heat can be upgraded to a higher temperature level by means of heat pumps, in order to better suit the needs of the process. The pinch curve of the previous steps shows at which locations this provides the best opportunities . It will also be investigated whether the heat from cooling machines can be used in the process. If necessary, the temperature can be increased by using a heat pump.

Step 4: Generating energy

The next step is to look at how heat, cold and electricity can be generated as efficiently as possible. The combined generation of this in a (bio)heat/power installation with possible additional absorption cooling for the cooling system offers savings of up to 50%. Finally, it is determined how much energy still needs to be purchased.

More information

Is your company interested in heat integration? The specialists at CCS are happy to assist you in this. For more information please contact us and ask for René Cornelissen.

About this article

30 July 2020 / Author: Dr. Ir. René Cornelissen

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