Horizontal spiral pusher decanter Decanter short, it has been widely used in sewage treatment plant sludge dewatering process. Although different manufacturers or models with different specifications Decanter have different device structures, equipment, materials, specifications and operation of the adjustment mechanism, etc., but the basic principle is similar device, is its simple introduction to on-site users to more good use and adjustment. 1 structure and dehydration principle Decanters mainly by the drum, spiral, differential system, level baffle, drive systems and control systems and other components. Decanters is to use the difference in density between solid and liquid, the centrifugal force to accelerate the sedimentation rate of the solid particles to solid-liquid separation. Specific separation of sludge and flocculant liquid is fed through the inlet pipe inside the drum mixing chamber, in this mixed flocculation (pipeline dosing if the former sludge pump or pump after dosing, already ahead of flocculation reaction) , since the rotor (spiral and drum) of high-speed rotation and friction, sludge is accelerated and form a cylindrical liquid ring layer (liquid ring area) inside the rotor under the action of centrifugal force, a large proportion of the solid particles to settle to turn drum wall to form a sludge layer (solid ring layer), then the coil and drum relative speed difference to the solid phase into the drum cone end, after the introduction of the liquid (or the land area known as the drying zone) sludge can be dried, push the slag discharge port, and the supernatant is discharged from the drum big end, solid-liquid separation. 2 decanters influence factors effect the effect of horizontal spiral centrifuge use, the impact of the mechanical part brought into adjustable and non-adjustable factors factors, are described separately, first understand its mechanism, it is possible in use its effective control. 2.1 A non-adjustable mechanical factors drum diameter and effective length of the drum diameter is larger, the longer the effective length, the greater the effective size of the settlement, the greater processing power, the material in the drum, the longer residence time in the at the same speed, the greater the separation factor, the better the separation. But limited material, the centrifuge drum diameter can not be increased without limit, because as the diameter of the maximum allowable speed decreases with reduced material sturdiness, and thus the centrifugal force is reduced accordingly. Drum diameter is typically between 200 ~ 1000mm, an aspect ratio between 3 to 4. Now the development of decanters large aspect ratio has tended to trend higher speed, such devices are more able to adapt to the low concentration of sludge treatment, better mud biscuits. In addition, in the case of the same amount of processing, large drum diameter centrifuge can run at a lower speed difference, because the spiral lose slag capacity of larger drum diameter, to achieve the same output capacity of slag, a small turn centrifuge drum diameter must be achieved by increasing the speed difference. B drum half cone angle of settling sediment inside the centrifuge drum along the drum cone is pushed out of the discharge port, due to the centrifugal force and the downward force by reflux slip. Centrifuge drum half cone angle is the more important design parameters. From clarifying effect in terms of the requirements of the cone angle as large as possible; and from the transport sludge and dewatering effect in terms of the requirements of the cone angle as small as possible. Since the output of slag is a necessary condition for the centrifuge work properly, so the best design must first meet the conditions of transport slag. For the difficult separation of materials such as activated sludge and a half cone angle of generally less than 6 degrees, in order to reduce sediment in the return rate. Ordinary general material half cone angle of 10 degrees or less will be able to ensure the smooth transportation of sediment. C Pitch Pitch That distance between the two adjacent spiral blade is a very important structural parameters directly affect the success or failure of transmission slag. Spiral constant diameter, pitch larger helix angle greater the chance of material between the spiral blade clogging becomes. While the large pitch will reduce the number of turns of the helical blade, resulting in uneven distribution of the drum cone material caused by machine vibration increase. So for the difficult separation of materials such as activated sludge, slag lose more difficult pitch should be smaller, generally 1/5 ~ 1/6 drum diameter in order to facilitate transport. For easy separation of materials, the pitch should be larger, usually 1/2 to 1/5 drum diameter in order to increase transmission capacity sediment. D helix spiral is the main component type Decanters, its role is to transport sediment settling on the inside of the drum and well drained sediment, it is not only the discharge device also determines the production capacity, service life and separation. Type according to the spiral of relative movement of liquid and solid manner in the drum divided into counter-flow and Downstream. Counterflow centrifuge feed chamber in the middle of the spiral, which is located near the border between the drying zone and the settling zone, in order to ensure adequate sedimentation from the liquid phase, the solid phase only but its residence time required by a conical portion, So ask for a higher centrifugal force; material from here to enter this area will cause the drum has settled solids particles floated again due to disturbances, also produce turbulence and additional vortex, the separation effect is reduced. Downstream centrifuges due inlet ends of the drum, to avoid turbulence counterflow ensure undisturbed sediment, centrifuge sedimentation have played a full-length, expanding the size of the settlement, suspension of the residence time in the machine growth, so that the separation effect is improved. Due to prolonged and settlement without interference can effectively reduce the use of flocculants, the floating of the fluid inside the machine are greatly improved, and the centrifugal force can be increased by increasing the drum diameter, it can significantly reduce the speed to save power consumption, while reducing, to extend the life of the machine. Centrifuge downstream helical structure is particularly suitable for solid-liquid density difference is small, solid-phase settlement poor performance, low content of solid material difficult to separate. But downstream centrifuge filtrate is by skimming pipe from the filtrate tube when skimming through the unseparated out again separated solid particles deposited in the skimming tube, falling downwards clogging fluid passageway, to be washed regularly. In recent years, with the increasing requirements for sludge dewatering, it appeared efficient spiral structure. As Sweden's Alfa Laval BD shutter technology, namely in the spiral centrifuge discharge end of the cone section to set up a special baffle, make centrifuges in ultra-deep sump state, in order to increase pressure on the cake slag force, and only the lower part of sediment transport, and the upper high moisture content sludge trapped on the outside of the press cone section, achieve dewatering, resorted to more dry mud. Swedish NOXON uses inclined plate sedimentation principles Lamella technology, then centrifuge auger blade design to the optimum tilt state, the blade angle, pitch, blade pitch and other parameters have been optimized design, processing capacity, reduced flocculant consumption and cake moisture content.