Air movement and cleaning by water sprays

A high-pressure water spray within a tube induces airflow through the tube and captures fine dust contained in that air. The parameters controlling airflow and dust capture were investigated using tubes ranging in diameter from 8 to 60 cm, waterflow rates up to 0.761. s −1 and water pressures up to 6890 kPa. The ratio of induced airflow to waterflow (called the entrainment ratio) remains almost constant as water pressure changes. The entrainment ratio is a function principally of the sprayhead size and tube diameter. The dust capture efficiency is a function principally of the water pressure ( P ), waterflow ( Qw ) and airflow ( Qa , namely, PQw / Qa . The effects of spray angle, spray type, tube size and shape were also examined. The laboratory measurements showed good agreement with theoretical dust capture efficiencies. As an example of practical performance, a 15 cm dia. tube with a spray flow rate of 0.2251. s −1 at a pressure of 3450 kPa (500 psi) gave an induced air flow of 0.35 m 3 s −1 and 90% capture efficiency for respirable coal dust