Opportunities for Efficiency Improvement Through Recovered Thermal Energy
The rising cost of fossil fuels and power, along with the strict goals set by the Climate Change Act for reducing greenhouse gas emissions, have made energy efficiency in the potato processing industry a more pressing concern.
Overall, the food and beverage processing industry accounts for 25% of the estimated 11.4 TWh of recoverable heat that is wasted annually, making the utilization of waste heat sources essential to increasing industrial energy efficiency.
Heat exchange between a neighboring or same process source and sink is typically the most cost-effective solution for waste heat recovery, and a variety of highly developed heat exchangers are readily available for purchase.
Several innovative technologies have surfaced recently to facilitate the recovery of lower-temperature heat streams. Examples of these include compact heat exchangers with low approach temperatures and low-temperature organic Rankine cycles (fundamental operating cycles where an operating fluid is continuously evaporated and condensed), with unique working fluids.
Innovative Technologies to Facilitate the Heat Recovery
In steam systems, heat recovery from flue gas is frequently the best option. In an economizer, boiler feed water can be heated using flue gas heat. Large boilers typically use this measure, but additional heat recovery is frequently possible. The requirement to maintain the economizer wall temperature above the dew point of any acids present in the flue gas - such as sulfuric acid in fossil fuels containing sulfur - represents the limiting factor for flue gas heat recovery.
According to a research paper titled “Opportunities for low-grade heat recovery in the UK food processing industry”, an industrial air compressor can generate up to 90% of its electrical energy as heat. A heat recovery unit can often recover between 50 and 90% of this available thermal energy, which can then be used for heat pump applications, boiler make-up water preheating, water heating, process heating, make-up air heating, and space heating. For every 100 cfm of compressor capacity, it is predicted that recovered heat of about 50,000 Btu/hour is accessible. Repayment terms are usually shorter than a year.
A heat exchanger, for example, can be used to recover heat from the hot water blanchers' discharge water. Similarly, heat recovery from the hot condensate that exits the steam blancher may be feasible if the condensate is not recycled internally. In situations where fouling is under control, heat can be recovered via a heat exchanger and applied to boiler feed water or equipment cleaning water beforehand.
You can read the rest of this article in your complimentary e-copy of Issue 4 of Potato Business Dossier 2023, which you can access by clicking here.
