Application of a novel low-pressure hydrocyclone for foulant removal from sewage in a sewage source heat pump

A novel low-pressure defoulant hydrocyclone (LDH), with continuous underflow and reflux function, is proposed to prevent the blockage and to defer fouling of a sewage/wastewater heat exchanger with low head loss. The characterization of the foulant and sewage/wastewater is reviewed, while the separation performance of current hydrocyclones is evaluated. Experimental results illustrate that, compared with the conventional anti-blockage devices used in sewage source heat pumps, the LDH improves the separation efficiency while decreasing the cut size, split ratio, and head loss. Compared with traditional hydrocyclones with an apex connected to a closed “grit pot” or open to atmosphere, the LDH ameliorates the separation efficiency by decreasing the “entrainment of coarse/heavy particles in overflow” and eradicating the air core with a water seal. The LDH avoids the blockage and large increase in head loss of current enhancement-separation technologies of hydrocyclones.