Optimal heat recovery
In principle, there are a number of challenges with the electrification of the above process. Although green electricity appears to be a sustainable solution, it proves to be an obstacle to achieving heat recovery because the peak power for electrical preheating in a batch process is substantial, and the capacity of the electrical connection is not continuously available. In addition, heat recovery will be difficult to achieve because electricity is used for heating instead of a warm medium. A characteristic of a batch process is that heating the new raw materials entering the reactor cannot occur simultaneously with the cooling of the finished product leaving the reactor. In practice, this would mean waiting until the product is complete before heating the raw materials for the new batch, or vice versa: waiting for the finished product to cool before the raw materials for a new batch are needed. This is often undesirable due to equipment utilisation or the characteristics of the product.

Direct heat exchange is, therefore, not possible. In our example, we will buffer the heat so that the available heat is not lost. The temperature difference is the driving force for heating or cooling. It is, therefore, essential to keep the hot buffer as warm as possible and the cold buffer as cool as possible. A batch is often heated or cooled by pumping the contents around through a heat exchanger. However, this has a negative effect on heat recovery because the pumping also produces an average temperature; the return temperature is low at the beginning of the heating process and high at the end. So, a better approach would be to heat the raw materials feeding into the reactor and cool the product stream coming out. This method would ensure the hot buffer is kept at the highest possible temperature and the cold buffer at the lowest possible temperature. 

Low temperature loss due to heating and cooling product streams
To compensate for the temperature drop in the hot buffer (caused by heating the product), the hot buffer needs heating; electrically with a heater. But because we heat the raw materials feeding into the reactor rather than pumping the product around, the temperature loss is relatively low; a favourable effect. By applying a heat buffer, the heating time range is also lengthened, resulting in much lower peak power than direct heating. By cooling the product, the cold buffer becomes warmer and needs cooling. The required cooling capacity is minimised by cooling the product stream leaving the reactor rather than pumping the product through a heat exchanger. The concept described above minimises peak electrical power and maximises heat recovery. 

Industrial Internet of Things
But is it enough? Electricity is more expensive per kilowatt hour than natural gas. It is, therefore, necessary to explore further savings, for example, in the efficiency of the process.

Switching to green energy is not our only focus. Savings can also be made by reducing cycle times, preventing malfunctions and downtime and, for example, increasing reliability through comprehensive and accurate asset management. Collecting and processing accurate data is essential for all these aspects.

In the factory of the future, workers will be responsible for monitoring and collaborating with advanced automation systems to produce efficiently and safely. These systems will be connected and monitored via the Industrial Internet of Things and will be capable of collecting and analysing data in real-time. Thus optimising business operations and identifying any potential problems, and thereby offering excellent opportunities for far-reaching process optimisation.  

Many existing factories were designed in the 1960s and 1970s. So whether we would still want to manufacture products in the same way is highly questionable. Moreover, redesigning the process based on today’s technology can achieve many gains. After all, today’s requirements and possibilities are a world apart from those of the past.

Factory of the future
This article focuses on the electrification of a single batch process. But maybe there are opportunities within the factory where processes can be combined. And what will the new reality of the energy transition bring when it comes to the self-storage of electrical energy generated from solar panels, wind turbines or other sustainable sources? We love to think ahead when brainstorming the factory of the future with our clients.

These are exciting times. However, designing with today’s possibilities and conditions means that conceptually different designs are needed than in the past - reinventing industry. Long live the energy transition!