HRS Heat Exchangers has won two significant orders involving sludge and waste food applications for an unnamed environmental company in the UK.

One order involves the use of HRS' double-tube heat exchangers for the cooling of sewage sludge after a thermal hydrolysis process.

Thermal hydrolysis is a process for heating sludge under high pressure and high temperature usually 140-170C which increases the gas load, producing more biogas which can be used to create power and heat.

During the process the sludge is stabilised and disinfected providing an easier to dewater product at the end of the process.

The double-tube design was chosen for this application as the tube in tube concentric geometry makes it easier to work with fluids that contain particles without having to worry about blocking the product flow.

For the other order, HRS is to supply a complete turnkey package to continuously pasteurise mixed food waste to Animal By-Products Regulation (ABPR) standards.

Controlled by the EU, the main aim of the Animal By-products Regulation 2009 is to prevent animal by-products from presenting a risk to animal or public health through the transmission of disease.

HRS is installing a turnkey system utilising corrugated Double Tube heat exchangers in a thermal regeneration loop to heat incoming raw waste with hot pasteurised sludge to reduce running energy costs. The product is further heated to its pasteurisation temperature before being held for an hour to comply with the ABPR regulations.

As part of a thermal regeneration loop, HRS corrugated DTR heat exchangers will heat incoming raw waste with hot pasteurised sludge. The food waste goes through three sequenced tanks as part of the continuous batch process. The product then passes through the thermal regeneration heat exchanger, where it is cooled by the incoming raw waste before going to the digesters.