Nw Quattro Separator decanters
Continuous separation Nowadays, in practically all sectors of industry there is a need to separate solids from liquids to a certain point of the production processes. Quattro Separator meets this need by applying the centrifugal force in its decanters.
Solid particles suspended in a liquid tend to precipitate due to the gravity force.
The principle on which is based the operation of the decanter is the difference in density of the products to be separated, and as in a conventional sedimentation tank, the solid particles much more dense than the liquid particles, tend to settle due to the gravity force.
With the use of a centrifugal decanter this process is played within a cylindrical-conical drum, which given the high speed of rotation and multiplies the gravity force making this separation nearly instantaneous.
This force is then used to separate solids from liquids with an efficient method and high precision, in a way that is easy to control. Depending on the particular configuration, a centrifugal decanter can be used to separate a wide range of solids other than one or two liquids, in a process of continuous separation.
How it works
In the quattro Separator centrifugal extractor, the separation takes place thanks to the very high centrifugal acceleration developed by the rotation, which acts increasing the differences in specific weight of the various phases, and ensures high efficiency of operation.
During operation, in the drum of the decanter is sent a product, which under the action of the high radial acceleration, stratifies, placing the heavy phase (usually a solid) on the external part, while the light phase is placed towards the axis, within the heavy phase.
The liquid phase is expelled from the drum by means of the easy adjustable levels, placed at the end of the cylindrical part, while the solid phase is expelled from the holes at the end of the conical part of the drum. The product to be treated is fed inside the drum through a coaxial tube inside the centre of the screw. The separation happens according to the principle of the counter-current separation.
In the wastewater treatment either municipal and industrial, the maximum sludge dewatering is the most critical factor. This procedure allows a huge reduction in the amount of material to dispose and therefore a huge reduction in cost of sludge management in any type of activity, quattro Separator has developed a series of decanters called DDE (Dewatering Decanter) that due to the high rotation speed and the developed geometries of passage, you greatly reduce the residual content of moisture in the dewatered sludge. The result of continuous technological development is now the complete range of decanter four series DDE Environment for dewatering sludge.
The excess sludge produced in the stages of the biological processes have solid content of below 1 %. In order to reduce the amount of sludge to be treated is used to a phase of thickening to perform a first separation and bring the average content of solids in the order of 5-8%. At this stage is applied the decanter HTDE (High Thickening Decanter) specially developed for this purpose. The decanter HTDE, unlike other decanter, the principle of separation in the co-current. Recent studies, which take into account fixed costs (capital and labor) and variable (consumption of energy, water, polyelectrolyte and also spare parts), show that there are advantages for the benefit of the use of decanters for sludge thickening compared to other thickening systems. These advantages become incredibly important when it has to do with high flow rates and long process times.
Having to separate solid-liquid mixtures at low density or solids with a particle size in the order of several microns is recommended the use of a decanter specially designed for the clarification of liquids. These decanters prefer the clarity of the liquid phase and the recovery of the solid particles, even the most sensitive. Precisely for this type of applications quattro Separator has developed the line of decanter CDE (Clarifying Decanter) exploiting the principle of separation co-current. This configuration allows even the smallest solid particles to settle in a short time and then to have a liquid phase more clear.
THE SOLUTION FOR EVERY SEPARATION PROBLEM
Coffee Residues Coke
Corn starch Degumming
Dehydration Fats And Oils
Dry Cement Mixers
Lacquers And Varnishes
Mud From Aggregate Washing
Municipal Wastewater Treatment
Process Of Citrus
Recovery Of Edible Oils Recovery Of Starch Recycling Of Metals Rendering Resins
Salts (Organic And Inorganic)
Sludge From Refinery
Wastewater From Washing Beet
Structure and Housing The rotating parts are housed inside a cylindrical structure made of stainless steel AISI 304 (EN 1.4403), especially designed to minimize leakage outside of the decanter and reduce noise. The support frame is constituted by tubular steel coated with multilayer system resistant to corrosion. The entire structure rests on the ground using special robber shock absorbers, able to combine high capacity to absorb vibration at high stability anchor.
The drum consists of a cylindrical part and a truncated - conical, both made of stainless steel DUPLEX (EN 1.4470) with high surface hardness and high resistance to corrosion. This material makes superfluous the use of additional treatments to reduce the wear. The drum has been designed to operate in extremely harsh conditions: up to more than 3,500 [g] of radial acceleration, which is why the raw materials from which we make in our product are subjected to stringent quality tests in acceptance. Finally, the finished product is performed balancing computed, in order to make perfectly coincide the centre of gravity of the rotating body with its axis of rotation. The level of the liquid phase is adjustable by the user in different diameters, by acting on the adjustment plates, accessible from the outside; this enables the 'user' to modify the yields of the centrifuge, in terms of clarifying or dehydration. The outlet holes of the solid phase are protected by bushings material highly resistant to abrasion (tungsten carbides TS 457 Super); these also easily replaceable from the outside, making it possible in turn to use the most suitable material for use.
The internal screw is formed by a stem and a spiral wrapped to it, both made of stainless steel AISI 304 (AISI 316/EN 1.4470 optional). On the stem of the auger there are radial openings, alternating with the spirals, thus allowing the product to flow towards the drum. The main task of this component is to transport the solid deposited on the drum towards the conical part of the drum, taking care to keep as much as possible the state of rest.
For the drive of the drum and the auger pivoted on the same axis is using a two-stage planetary gearbox, oil bath, of primary importance for the proper functioning of the decanter. For the choice of this component is of vital importance, there is a choice between different systems, all provided by leading companies.
The whole assembly rotating decanter (drum and scroll) is supported by two ball bearings and roller bearings. These components are lubricated with grease high resistance to centrifugation (oil lubrication optional) and at high temperatures and are also protected by a series of labyrinths, oil seals and seals to avoid any contamination of the product being processed with the lubricant. These seals may be provided in different material, this allows to use the one more suitable for the type of work to be done, thus ensuring greater reliability of the machine and the lengthening of the period of its life. Noise and vibrations The average sound pressure level of all our decanter, does not exceed 82 dB (A) (value measured in accordance with the relevant legislation). The machines are designed in such a way as to minimize the generation and propagation of vibrations. For this reason, the rotating parts are subjected to computerized balancing and the entire structure rests on damping elements. Qualified companies certified that the average value of the vertical acceleration transmitted to the ground is approximately of 3.9 [m/sec2].
In accordance with quattro Separator specification.
Design and implementation of decanters for heavy applications
In order to increase our decanter applications limit, we have developed a lubrication ‘Oil drop’ system (optional). This system allows a much higher rotation and therefore a higher centrifugal force. An optional automatic lubrication system is available. Wear-resistant materials The parts subject to wear are protected by ceramic material and / or with carryovers of tungsten carbides (TS Super 457), while the seals are rubber Buna-NA/iton or NBR / Viton. A special series of anti-wear kits and anti-chemical attack has been developed for each type of product to be treated.
Decanter for ATEX zone The treatment of toxic, corrosive or flammable products is carried out with inherting gas in overpressure. To ensure safety process are adopted and process chamber and centrifuge housing. Slight positive or negative pressures can be maintained in the process area by regulating the purge gas supply. Special sealing elements minimize the seal gas consumption. These centrifuges comply with ATEX 95 in Zone 1, up to temperature class T3.
A single electric motor controlled by means of a frequency converter controls the rotation of the drum and of the scroll. The transmission ratio and hence the differential speed is established through the replacement of the belts and the pulleys on the output shaft of the planetary gear unit. This solution the most simple and economic is indicated, in particular, in separation processes that do not require a continuous variation of the differential speed.
Double electric drive
This solution is the developed version of the previous system. A second electric motor driven by an inverter always acts directly on the scroll making it independent from the main motor. This system, controlled by our software (Structura ®) enables to react to changes in the treated product, and then allows to change the automatic setting parameters. The system also allows a recovery of energy from the secondary motor to the main motor.
The hybrid version adds an hydraulic circuit to version single electric motor. In this case a variable capacity hydraulic pump, driven by the same main motor, drives an hydraulic motor directly driving the auger. This system allows a wide range of variation of the differential speed at constant torque. Designed primarily for applications where the differential variation is a key factor.
Two hydraulic motors separately drive the drum and the scroll. These motors driven by two independent hydraulic circuits are adjusted in turn by two hydraulic variable pumps. In this case the control software (Structura ®) acting by controlling the torque, determining both the speed of the drum and the differential speed. This system is particularly used for applications limit, and / or products with toxic, corrosive or flammable. Preferred for applications in ATEX zones.
Structura® Control system The continuous changes in the concentration of solids in the feed flow in a centrifugal may cause a reduction of the separation results, the clamping or at least an overload. To avoid these problems and exploit the decanter at most, it is essential to monitor and continuously adjust the differential speed between bowl and scroll.
The control system that equips all quattro Separator decanter is based on the monitoring of the instant load to which it is subjected the decanter. This assessment is performed by continuously and constantly measuring torque. Depending on the type of engine installed, the torque may correspond to the electric input On the case of electric motors) or to the pressure of the hydraulic circuit On the case of hybrid drive or fully hydraulic). In all cases, however, the main purpose is to keep the load and the tirque at optimal levels, acting on all those parameters available in the plant. If the torque exceeds the optimum value, the control system Structura ® progressively increases the differential speed to speed up the exit of the amount of solid in excess and restore the optimal values of work. Conversely, if the torque value detected tends to decrease the software acts on the differential speed by increasing the retention time of the solids inside the drum, thus restoring, also in this case, the optimal load of work. In the case in which the variation of the differential speed is not sufficient to restore the optimal conditions, the software Structura ® fielding the second stage of management acting on feeding. In both cases the variation of the torque goes outside the allowable range, the power is adjusted (in the case of pumps with variable frequency drive) or interrupted (in the case of manual variable speed motor) until the return to the setted parameters. Thanks to the continuous and constant control of the working parameters, Structura ® allow to harness the full potential of the decanter, also avoids its clogging, thus reducing the need for maintenance and downtime. In case the control system is not sufficient and will arrive to a drum / scroll clogging, as for example for a voltage drop of the electricity network for a substantial time, Structura ® has been equipped with a routine of dis-clogging which provides the unlocking automatically, by means of a forced in counter- current washing, without to dismantle the decanter.