Decanter Centrifuges for Sewage Disposal

• After-sales Service: Permanent Technical Support
• Warranty: 1 Year
• Type: Centrifuge
• Object: Liquid-Solid Separation
• Separation Mode: Sedimentation Type
• Operating Type: Continuous Type
• Model NO.: LW
• Installation: Vertical
• Centrifuge Type: Horizontal Spiral Centrifuge
• Pressure: Low Pressure
• Condition: New
• Application: Liquid-Liquid-Solid Separation
• Operation: Automatic Continuous
• Bearing: S-K-F, NSK as Optional
• Material: SS304L, SS316L
• Transport Package: Wooden Case
• Specification: According to The Model
• Trademark: SHENZHOU
• Origin: China
• HS Code: 8421192000
• Production Capacity: 500sets

Product Description

Decanter centrifuges process characteristics

The separation process in a decanter centrifuge relies on a few process characteristics such as centrifugal force or G-force, sedimentation rate and separating factor, differential speed between the conveyor and bowl, and clarity of the liquid discharge.

Decanter centrifuges require a centrifugal force for the separation of the solids from the liquid.  This characteristic is dependent on the radius of the centrifuge and its angular rotational speed. A decanter centrifuge applies a force equivalent to several thousand G's, which reduces the settling time of the particles. It is also favored to maintain a large G-force, which will result in an improved separation.

The rate at which sedimentation occurs is an important characteristic of the decanter centrifuge separation process.  The sedimentation rate is influenced by the particle size, the shapes of the particles, their differential densities and the viscosity between the particles and the liquid. This process characteristic can be improved by utilizing flocculating agents. The sedimentation rate is also dependent on the separating factor of the decanter centrifuge, which is related to the centrifugal force.

The exterior bowl and the scroll conveyor rotate at different high speeds. This differential speed between the two is accountable for the sedimentation throughout the decanter centrifuge cylinder.  A high differential speed results in a smaller residence time of the cake settlement, so it is necessary to keep the cake thickness to a minimum to avoid impairing the discharge quality.  Keeping the cake thickness to a minimum also aids in the improvement of the cake dewatering process.  For this reason, it is necessary to obtain an optimal differential speed to balance the cake thickness and quality.

The characteristic above all affects the clarity of the liquid output which is dependent on the volumetric throughout rate, where a higher flow rate will result in a poor liquid clarity.  Another characteristic that influences the clarity of the liquid output is the differential speed.  A low differential speed results in a better clarity, therefore, aiding in the separation process.  The G-Force also plays a role in the clarity of the liquid discharge.  Higher G-force results in an increase in the separation of the solid particles from the liquid and yields a better clarity.

Categories: Centrifuges, ProductsTags: 2 phase Centrifuge, 3 phase Centrifuge, Decanter Centrifuge, Ethanol and  Centrifuge, Hemp Centrifuge, Hexane Centrifuge, Horizontal Centrifuge, THC Centrifuge

How does it work

The feed product is pumped into the decanter centrifuge through the inlet. Feed goes into a horizontal bowl, which rotates.  The bowl has is composed of a cylindrical part and a conical part.  The separation takes place in the cylindrical part of the bowl.  The fast rotation generates centrifugal forces up to 4000 x g. Under these forces, the solid particles with higher density are collected and compacted on the wall of the bowl.  A scroll (also screw or screw conveyor) rotates inside the bowl at a slightly different speed.  This speed difference is called the differential speed.  This way the scroll is transporting the settled particles along the cylindrical part of the bowl and up to the end conical part of the bowl.  At the smallest end of the conical part of the bowl, the dewatered solids leave the bowl via discharge opening.  The clarified liquid leaves through a paring disc (internal centripetal pump).

3-phase separation with a decanter

With a 3 phase decanter centrifuge, it is possible to separate 3 phases from each other in one process step only.  For example, two liquids which cannot be mixed because of different densities (e.g. oil and water) are separated from a solids phase.  The heavy liquid (water) collects in the middle between the oil and the solids layer.  Thus the two liquids separated from each other can be drawn off from the decanter.  The solids are transported via the scroll to the discharge openings as it happens also in 2-phase separation.

Typical applications of 3-phase separation are the production of edible oils such as olive oil, oil sludge processing, the production of biodiesel etc.

Parameters and influencing factors of the separation

Feed, throughput and residence time

Through the feed, the separation medium to be processed can be input into the center of the infeed chamber of the scroll, where it is accelerated.  The throughput will have an influence on the residence time.

Acceleration

The separation medium reaches its maximum speed in the decanter bowl, causing the solids to settle on the bowl inner diameter.  A characteristic feature of the bowl is its cylindrical/conical shape.

Differential speed

There is a differential speed between the decanter bowl and the scroll, which is created by a gear unit on the industrial decanter centrifuges.  The differential speed determines the solid content in the outfeed.

Filling volume / Weir discs or overflow weir

The clarified liquid flows to the cylindrical end of the bowl in the decanter centrifuge, from where it runs out through openings in the bowl cover.  These openings contain precisely adjustable weir discs/weir plates by means of which the pond depth in the bowl can be set.  The weir discs determine the filling volume of the bowl.

Model	Diameter (mm)	Max. Speed (rpm)	Separation Factor	Capacity (M3/H)	Power (kw)	Weight (kg)	Overall Size (mm)
LW250×1000	250	5400	4080	2-10	11-15	1000	2600×760×1115
LW300×700	250	4600	3553	2-10	11-15	1120	2335×814×1170
LW300×1000	300	4600	3553	2-10	11-18.5	1380	2635×814×1170
LW350×1000	350	4200	3450	2-18	15-30	1950	2712×872×1244
LW350×1320	350	4200	3450	3-22	22-30	2200	3012×872×1244
LW350×1550	350	4200	3450	2-18	15-30	1950	2800×1380×850
LW430×1320	430	4000	3845	4-28	22-37	2500	3120×940×1320
LW430×1600	430	4000	3845	4-28	22-37	2500	3000×1500×1000
LW430×1800	430	4000	3845	4-28	22-37	2950	3600×940×1320
LW480×1800	480	3650	3580	6-35	37-45	4550	3650×1010×1396
LW480×2000	480	3650	3580	8-40	45-55	5050	3850×1010×1396
LW500×2000	500	3500	3423	8-40	45-55	5800	4150×1380×1558
LW530×2120	530	3500	3630	10-50	45-75	7200	4270×1380×1558
LW530×2200	530	3500	3630	10-50	45-75	7200	3800×2350×1200
LW580×2120	580	3000	29180	12-55	55-75	7800	4290×1450×1638
LW650×2400	650	2800	29180	15-60	75-90	8300	4330×1560×1768

Advantages and limitations over competitive processes

Generally the decanter centrifuge has more advantages than disadvantages; however, there are some limitations when compared to other processes.

Advantages:

• Decanter centrifuges have a clean appearance and have little to no odour problems.
• Not only is the device easy to install and fast at starting up and shutting down but also only requires a small area for operation compared to other competitive processes.
• The decanter centrifuge is versatile as different lengths of the cylindrical bowl section and the cone angle can be selected for different applications.  Also, the system can be pre-programmed with various design curves to predict the sludge type, while some competitive processes, such as a belt filter press, cannot change the belt type to operate for different sludge types.  Its versatility allows the machine to have various functions such as operating for thickening or dewatering.
• The machine can operate with a higher throughput capacity than smaller machines.  This also reduces the number of units required.
• The device is simple to optimise and operate as it has few major variables and reliable feedback information.
• The decanter centrifuge has reduced labour costs compared to other processes, as it requires low continuous maintenance and operator attention.
• Compared to some competitive process such as the belt filter process, the decanter centrifuge has more process flexibility and higher levels of performance.

Limitations:

• The decanter centrifuge cannot separate biological solids with very small density differences, such as cells and viruses.  A competitive process that is capable of separating these difficult-to-separate solids is the tubular-bowl centrifuge.
• The machine can be very noisy and can cause vibration.
• The device has a high-energy consumption due to high G-forces.
• The decanter centrifuge has high equipment capital costs. Hard surfacing and abrasion protection materials are required for the scroll to reduce wear and therefore reduce the maintenance of the scroll wear.
  

FAQ
Q1: Where can I get product & price information?
A1: Send us inquiry or email directly, then we will contact you.
Q2: How can I make sure your machinery is suitable for me? 
A2: Please tell all the separation information you know, such as your raw liquid,
two-phase or three-phase separation, solid content in liquid, solid size, the purpose, etc. After analyzing your information, we will to choose a suitable model for you, and send the details and videos to you.
Q3: What should I do if I want to see the separation effect?
A3: If you can come to our factory with the raw liquid, we will provide test service. Or you deliver the raw liquid to us, and we will do a test, and supply you the testing videos.
Q4: How to enjoy the OEM services?
A4: As the manufacturer of the machine, we will try our best to satisfy you if you have any specific requirement, such as the cover device, drum size, motor voltage, etc.