HEAT EXCHANGERS FEATURE Heat exchangers are crucial to many processes


in the water industry but, due to the number of different types available, choosing the right one can appear daunting. For both economic and


environmental reasons, maximising productivity is essential, and correct heat exchanger selection is key to this, as Matt Hale, international sales & marketing director, HRS Heat Exchangers, explains


an operator can provide, the more likely they are to get the right heat exchanger for the job. After thoroughly researching the options


Enhancing


productivity with energy


efficient heat exchangers


F


or many water companies, there is a balance between increasing output


without increasing costs. This, however, is closely linked to efficiency, ensuring that every piece of equipment and every part of the process is optimised in order to deliver greater value for money to the operator. So, the first criteria when specifying


a heat exchanger is: will it be fit for purpose? To do this, it is important to understand both the material being treated, the heating – or cooling – medium, and the process involved. Is the material in liquid (dirty or clean water) or semi-solid (sludge)? Is it viscous? What is the extent of the temperature difference required? Other things to consider are


whether the product contains solid particles, whether it is shear sensitive, if the process needs a scraped surface heat exchanger (SSHE), or whether well-designed corrugated tubes will be enough to prevent fouling. Added to this are the space available for the heat exchanger, and the connection pipework and fittings. The more information


/ ENERGYMANAGEMENT


HRS Unicus Series scraped-surface heat exchangers


The running costs of a heat exchanger have a large effect on its overall financial viability, so selecting a heat exchanger which is


energy efficient is key to enhancing productivity


available, it may be that more than one type or model of heat exchanger is suitable. So, in order to ensure optimum productivity, it is important to consider the total cost of ownership (TCO), rather than the initial purchase price. The lifecycle cost of a heat exchanger, particularly one used to process difficult materials such as sewage sludges, heavily depends on the costs of cleaning and maintenance – buying a cheaper design which is more prone to fouling can quickly become more expensive to operate.


ENERGY EFFICIENT TECHNOLOGY The running costs of a heat exchanger have a large effect on its overall financial viability, so selecting a heat exchanger which is energy efficient is key to enhancing productivity. HRS Heat Exchangers has developed a number of features which are specifically designed to improve the operational energy efficiency of both their tubular and scraped-surface heat exchangers. These include the use of corrugated tubes specifically designed for high fouling sludges, such as the DTI Series of Double Tube Heat Exchangers, and SSHE designs including the Unicus Series. The Unicus Series is based on traditional shell and tube heat exchangers, with the


addition of a patented stainless-steel scraping mechanism which is hydraulically moved back and forth within each interior tube. This movement minimises potential fouling of the product by keeping the tube wall clean, and also creates turbulence within the material. Both of these actions help to increase heat transfer rates and, together, they create a highly efficient heat transfer process ideal for high fouling viscous materials like sludges.


MAKING THE RIGHT CHOICE Using the wrong heat exchanger can soon prove costly in terms of maintenance and spare part costs. To help, all HRS heat exchangers are designed to make cleaning and maintenance as easy and flexible as possible, while their clever design reduces cleaning and maintenance intervals. Of additional benefit, its equipment can be remotely monitored, making it easier to anticipate problems. Being able to quickly identify issues helps to keep efficiency high and provides more time to plan for maintenance. It is also important to consider the


overall installation costs, and whether fitting the heat exchanger will require the purchasing of ancillary equipment. The corrugated design of HRS’ tube-in-tube heat exchangers results in improved efficiencies, providing comparable thermal performance to other designs, but in a smaller footprint. These can often be skid- or frame-mounted, reducing the need for significant support infrastructure. Both standard clamp and flange fittings are available, although any bespoke fitting can also be supplied. So, whatever solution you


choose, make sure to consider its energy efficiency, maintenance requirements and the costs of any ancillary equipment before signing on the dotted line. Put simply, specifying the wrong heat exchanger could decrease your productivity – choosing the right heat exchanger will almost certainly increase it.


HRS Heat Exchangers www.hrs-heatexchangers.com


ENERGY MANAGEMENT | AUTUMN 2020 29


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