High pressure belt press for sludge

The high pressure belt press NPF_HP type is recommended when it is necessary to obtain a strong reduction of the water content in sludge. Generally it is installed downstream the sludge treatment lines and consists of a frame in normal profile, a sludge load hopper, storage and drain tanks for the filtered water, two joined belts through which the sludge to be dewatered passes, a roller assembly used to drain and press the sludge, belt puller, belt centring and transmission rollers, a washing system with nozzles for each belt and two sturdy planetary gear motors. The roller assembly comprises one first big diameter drainage roller, one second drainage roller, one low pressure roller, one medium pressure roller, nine high pressure rollers, two transmission rollers, two belt pullers, two belt centring rollers and four return rollers. The sludge goes in touch with the belt in the higher part of the belt press, goes through a long section where the water drips by gravity and successively falls on the second belt and goes on flowing into a wedge which facilitates the very delicate removal of the water from the sludge. Subsequently, the sludge goes into the first drainage roller zone, which allows a first slight sludge pressure thanks to its big diameter. The sludge is then submitted to increasingly higher pressures up to the high pressure zone. The large quantity of small diameter rollers allows high pressures on sludge together with a long time of retention. After the sludge discharge, the two belts are submitted to washing for the residual material elimination. All this occurs with a continuous and completely automatic operation. The main characteristic of this belt press is given by the possibility to successfully treat also the sludge difficult to be dewatered, the initial low pressures and the long stabilization time; in fact the sludge flocks, the high final pressures and the long high pressure time moreover allow to reach an excellent degree of dewatering of the sludge. The standard construction includes the supply of an inverter for the belt speed adjustment. Moreover, on request, a ploughshare system, installed on board of the belt press to increase the efficiency of the first stage of gravity dripping, can be supplied. This is particularly useful for the sludge difficult to be treated. The standard construction is with hot dip galvanized carbon steel frame while the other parts in contact with the water, the tanks, the drainage rollers, low and medium pressure rollers are in stainless steel. Moreover, high pressure, transmission, return, pulling and centring rollers are covered with a rubber layer. On request it is possible the construction with particular protections or completely in stainless steel.