Spiral or corrugated tube heat exchangers – which is best for wastewater treatment?

03 July, 2019

Unlike SHEs, the tubes can easily be removed for inspection, cleaning and maintenance and a variety of flange connections are available. The unit is also made in easy-to-replace sections. Should the heat exchanger suffer internal damage, the failed section can be easily bypassed by moving the interconnecting bends; a replacement can be manufactured and fitted when it is ready. In contrast, if a spiral is damaged, the complete heat exchanger must be removed to a workshop where many layers have to be cut out to access the point of failure. This is then re-welded and all the cut away sections must be re-welded into place. The cost is significant and downtime is many weeks.

Choosing the best solution

In many situations, we believe that a corrugated tube heat exchanger, like the HRS DTI Series, is the best solution for challenging materials such as sludge. However, in the most extreme cases with a very high fouling risk, it will be necessary to use a scraped-surface heat exchanger such as either the HRS rotating R Series or the patented reciprocating Unicus Series.

In order to select the best solution, it is necessary to accurately assess the physical properties of the product or sludge to be treated, as well as the service fluid, inlet and outlet temperatures and the amount of heat regeneration required (if any). When comparing specifications or quotations for different solutions – for example SHEs compared to corrugated tubes – it is important to make sure that you are comparing like-for-like and that the performance specifications are identical. You should also assess whether any gains in efficiency or lower capital cost will be offset by increased fouling or operational costs over the full life of the unit.

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