Feasibility of a novel de-foulant hydrocyclone with reflux for flushing away foulant continuously

In this paper, the possibility of using a novel de-foulant hydrocyclone with reflux function to separate foulant (<4 mm) from sewage and flush away the foulant continuously was studied. This de-foulant hydrocyclone can be used in prior to the sewage heat exchanger of a sewage source heat pump for pre-treatment of sewage to avoid or relieve blockage and fouling in the sewage heat exchanger. A de-foulant hydrocyclone prototype with 165 mm internal diameter and reflux function was designed and created for foulant separation. Different separation experiments of sand-water, high-concentration sewage and low-concentration sewage were investigated. The results showed the novel de-foulant hydrocyclone had an effective performance to separate the foulant from the sand-water and the domestic sewage. Maintaining low split ratio, the separation efficiency for sand-water was close to 100%, and that for high-concentration domestic sewage was 93-97%, and 57-72% for low-concentration domestic sewage. The separation efficiency was proportional to the feed foulant density while the feed pressure had no significant effect on the separation efficiency. The total static pressure losses of the novel de-foulant hydrocyclone were all within 10-20 kPa.