The majority of wastewater treatment plants utilize anaerobic digestion techniques for biological stabilization of municipal sewage sludge. These plants which today are an integral part of any community are tremendous consumers of energy. With energy costs constantly on the rise and consumption closely monitored, existing plants, some of them retrofitted, and new plants alike are installing corrugated tube heat exchangers in an effort to reduce energy consumption, and so improve operating efficiencies.
We draw from special know-how and experience in heat exchangers for water, sewage, process heat and all sorts of liquids containing solids. Our performance spectrum comprises the layout, design and manufacture of the heat exchangers including the necessary piping to the heat pump our plant requiring the energy.
Sewage treatment plants have a big energy potential, be it to cover the own need for energy or to heat and cool buildings in the vicinity. The energy is ideally recovered at the exit from the sewage works. If heat is extracted from the purified water, this lowers the temperature level and benefits both man and eco system.
DIGESTER SLUDGE HEATING
The primary application for corrugated tube heat exchangers is digester sludge heating.
Digester temperature must be maintained within tight tolerances for proper sludge stabilization, approximately 35º C for mesophilic digestion. Hot water heats the digester sludge as it is circulated through a corrugated tube heat exchanger before returning to the digester. Digester sludge contains approximately 4wt percent solids and fibers, which tend to plug conventional plate heat exchangers.
RAW SLUDGE PREHEATING
Raw sludge preheating with corrugate tube heat exchangers is accomplished by recovering waste heat from digested sludge and using it to preheat the raw sludge before it enters the digester. During colder periods of the year, the raw sludge feed to the digester may be 5 to10 ºCF. Using the heat available in the digested sludge, which leaves the digester at approximately 35 degrees, to preheat the raw sludge greatly reduces the size and operating cost of the digester sludge heater. The counter current tubular arrangement allows efficient and economic heat recovery, 60 percent recovery is nominal. Additionally, the corrugated tube is capable of handling these solid and fiber laden fluids.
Geometry
The monotube IT20 is a welded corrugated heat exchanger. We understand that hygienic equipment has to be easily cleaned. It is preferable to have the possibility of inspecting the sanitary side, in our case, the inner tube.