All of NES 800 range of Oil Recovery Systems operate the same principal of operation for the pre-treatment or conditioning of oil residues followed by the a 3 phase tri-canter centrifugal separation.

The larger units come in two modules, the first containing the pre-treatment unit and the second containing the centrifuge and other equipment depending upon the model. The large NES802 twin module unit is currently the largest of the range and is completely autonomous with the exception of a steam boiler.

In the first of the two modules the pre-treatment unit consists of three tanks. The first two tanks receive the input feed stock to be treated after first passing through an alternating filter basket system to remove any large debris that would damage of block the system. This can also be replaced with a shell-shaker if the input feed stock is of a quality that requires it. Whilst one of these tanks is being filled the second is being blended by paddles and / or resuspension together with heating via steam heating coils.

Chemicals can also be dosed into these tanks from the dosing tanks and mixers via their own dosing pumps. Once the contents of a tank have been conditioned to a suitable physical state for passing through the decanter then it is pumped to tank number three, which is the feed tank for the decanter.

An intricate pipework, valve and pump system enables different combinations of flow source, direction, and destination to be selected by the operator to cover any eventuality encountered. The twin polymer dosing and mixing tanks and pumps allow the dosing of polymers into the decanter inlet if required. All pumps and paddle mixers are hydraulically powered and the supply for these comes directly from the hydraulic power pack located in the module that contains the decanter.

Temperature and visual level indicators ensure the operator is in possession of of all the information he requires to operate the unit.

The second module houses 2 diesel driven hydraulic power packs built to NES usual safety specifications for hydraulic power packs. (Refer to NES 402 range of hydraulic power packs). It also houses the 2 Tri-canter centrifuges. The centrifuges are fed from the pre-treatment unit and the output of 1- water is piped to the water settling tank also housed in the same unit 2- the recovered oil piped into a separate recovered oil tank and 3-the sediments discharged onto a conveyor belt that discharges directly into a truck or skip for transport away from the site.

Both the Tri-Canter centrifuges can be operated together or either one operated alone.

Operation: - With the bowl spinning at 3,000 rpm the feed slurry is fed through a fixed central pipe into the distributor located in the scroll. The product is accelerated smoothly to bowl speed as it passes through the feed ports in the scroll into the bowl.

Separation takes place in the conical cylindrical bowl when he slurry forms a rotating liquid tube under the centrifugal force caused by the bowl rotational speed. The solids in the slurry are deposited against the bowl wall and the remaining liquids separate into a light and heavy phase giving three concentric layers held against the bowl by centrifugal force.

The scroll is rotating at a differential speed to that of the bowl and conveys the separated solids in the direction of the conical end of the bowl. The length of time the solids remain in the bowl is an important factor in determining the dryness of the final solids discharge. The residence time can be adjusted by changing the differential speed of the scroll in relation to the bowl.

The separated solids are discharged through openings at the conical end of the bowl into a fixed discharge housing and then down the discharge chute.

While the liquid phases are being clarified they progress to the cylindrical end of the bowl where they are decanted through separate discharge systems to prevent cross-contamination.

The lighter phase is normally discharged under gravity whilst the heavier phase is removed under pressure by the variable pitch impeller. By altering the impeller during operation the clarity of the two liquid phases can be optimised.

Centrifuge for continuous separation of two liquids with different specific weight and one settleable solids phase.

The first liquid phase is ejected under pressure via an adjustable impeller disc (continuous optimization of the liquid separation line during operation of the machine).

The second liquid phase flows without pressure by gravity over an adjustable weir.

All product contact parts are made of stainless steel. The other metal parts are protected against corrosion by multilayer finish.

Sealing: Material NBR

Scroll: Surface ground

Wear protection:

Feed compartment armoured with cast iron bushings

Scroll blade protected by tungsten carbide

Bowl: Wear protection:

Discharge area outside: hard metal

Flanged wheel: hard metal

Execution inside:

Wear protection by strips and cast iron bushings

Rotor housing: stainless steel

Solids housing: integrated in rotor housing

Machine base: carbon steel

with vibration insulators

Rotor: exchangeable for easy maintenance

Belt guard: according to EEC safety rules

Central lubrication system: manually operated

Drive bowl: Hydraulic motor with fluid coupling

for indication of the bowl and differential speed.

Initiators mounted on power packs

NESL fully hydraulic drive VS2I-370 A aggregate

for continuous adjustment of bowl- and scroll differential speed as well as for control of scroll diff. Speed (from 3 to 22 min^-1 during operation and under load.

This variant of drive makes a slow start-up of the machine possible without the high electric starting current, which is required otherwise, and also almost constant dryness of the solids with heavy fluctuating solids contents in the inflow. At the same time the machine is protected against overload and clogging, including Parker double pump (variable displacement type), and air-cooled heat exchanger for hydraulic oil.

For leading and lagging operation of the machine, revolving.

Enables the addition of flocculent or other separation aids directly in front of the inlet area of the decanter.

Creates a dense and vibration isolating connection between the solids chute of the decanter and the continuous solids chute of the decanter and the continuous solids conveying systems.

NES 802 Pre-Treatment Unit & Centrifuge Decanter Unit (Hydraulic Version)

• 2 X 40 ft Skids - 11.67m X 2.24m X 2.15m - Weight (per skid) 11,500 KGs

• One side of each skid fitted with lift up and drop down awning and walkway

• 2 heated resuspension tanks of 10m3 each with hydraulic shell shaker

• 1 heated blending tank with paddle mixer
• 3 Rotary Lobe transfer pumps 84 m3/h (500Bbl/h) @ 6.2 Bar (91 psi) hydraulically powered with main pipework in 3" - Ball valves fitted allowing all possible variations of product flow direction including feed to decanter centrifuge

• High and Low level visual and audible alarms - 6"overflow pipe from all tanks terminating in flange for site connection

• Control Panel for hydraulic operation Forward/Reverse/Stop of pumps, agitators and mixers
• Steam Control systems with steam traps on all three tanks

• Steam Heating coils : 2" Pipe

• 2 Chemical and 2 polymer dosing/mixing tanks with paddle mixers and pumps for continuous dosing of chemicals and polymers - pumps and mixers hydraulically powered

• Twin continuous inline quick clean filters on incoming line with change over valves - back flush and steam injection facility

• Emission control chimneys on re-suspension and blending tanks

• Removable tank lids

• Removable access plates on tank sides for cleaning purposes

• Sandblasted and Painted in choice of 1 colour

• 2 X Horizontal 3 Stage Decanter Centrifuges hydraulic drive and 2 diesel hydraulic power packs

• Belt conveyor with swing and height adjustment for solids discharge hydraulically powered
• Separated oil outlet 3"
• Water outlet to inbuilt settling tank with drain and draw off points and submersible discharge pump
• Bulkhead separation to Ventilated Power Pack engine room

• All control systems outside of engine room intrinsically safe or flameproof
• Sandblasted and Painted in choice of 1 colour

Hydraulic drive system for each Z42-3/451 centrifuge comprising:

1. Rotodiff type 1070S/V with V belt pulley
2. Volvo F11-19 drive motor with block and console for 3200 rpm max bowl speed
3. Control block on stand with flow/speed meters for bowl and for scroll, scroll speed setting and bowl speed setting, boost pressure setting, machine cut off pressure, feed in cut off pressure.

Engine- Iveco 8061 6 cyl diesel water cooled

Power(intermittent)-84.5KW@2500rpm

Power(continuous) –76 KW@ 2500rpm

Displacement 5.9 l - 12v electrics

Fitted with splitter box for 2 X tandem pumps 1+2 and 3+4

Pump No.1 for the bowl - Plunger type pilot operated with variable displacement 65 l/min 250 bar

Pump No.2 for the scroll – Gear pump fixed displacement 54.5 l/min 250 bar

Pump No.3 for centrifuge feed pump – Gear pump fixed displacement 54.5 l/min *

Pump No.4 for the bypass oil cooler 12 Kw and filtration – Gear pump fixed displacement 54.5 l/m

Mounting Protection Frame with lifting point

Pressure line filtration 10 micron abs.

Fuel and Hydraulic Tanks- incorporated

Full instrumentation and controls fitted

Safety- Spark Arrestor/Chalwyn inlet valve/Engine protection

No return line filtration is allowed

Only Mineral oil with viscosity VG68 (68mm2/s, 68cst) to DIN 51524HLP to HL68 to ISO HM68 is permitted

copyright © 1996-2006 by Non Entry Systems Ltd (NESL)