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Various industries use decanter centrifuges to separate bulk sludge or solids from fluids. From the separation of aromatic herbs from tincture or alcohol to the separation of zinc salts from the chemical broth, all types of industries use Alfa Laval decanter centrifuges.
The applications for decanter centrifuges are prevalent in all industries, such as the food industry, chemical processing, industrial waste processing, and municipal waste processing. In addition, the petroleum processing industry uses a variety of decanters to separate drilling mud and tank bottom waste oil from produced water.
Dolphin Centrifuge has designed and supplied remanufactured Alfa Laval decanter centrifuges for a wide range of applications which lends us the experience to recommend the correct type of decanter centrifuge for your specific application.
The decanter centrifuge has three main components that separate sludge from liquids. These components are the rotating bowl (1), the concentric auger (2), and the interconnecting gearbox (3), as shown in the animation above.
The rotation of the bowl exerts a high centrifugal force on the incoming sludge and liquid. This force causes the instant settling of the heavier sludge along the inner bowl wall. The auger within the bowl rotates at a differential speed in relation to the bowl. This speed differential causes the auger to scrape the separated sludge towards the solids ejecting end of the bowl.
The liquid is displaced to the liquid end, from where it exits the bowl continuously.
A decanter centrifuge is an industrial machine designed to separate bulk and heavy solids or sludge from a liquid on a continuous or pass-through basis. This type of centrifuge offers several advantages over conventional separation methods involving filtration or filter media.
This article discusses various decanter centrifuge applications with some images of decanters we have supplied for specific applications. This list is in alphabetical order.
A food-grade decanter centrifuge is perfect for separating apple sauce from apple juice. A decanter centrifuge separates the crushed, peeled apples from the juice in the typical production process.
The flow-through design of the decanter allows for this separation to be a continuous process without any interruptions for cleaning, etc. The juice separated by the decanter can then be polished off the suspended solids by a high-speed disc stack centrifuge such as the Alfa Laval BRPX-213.
The rendering industry has several uses for the decanter centrifuge. The primary application is for separating the animal carcass waste from animal fat (tallow or lard), waster, and remaining solids waste, including proteins.
The decanter centrifuge processes the leftover animal waste ground up with water and heated to separate fats and water. A three-phase decanter centrifuge separates the fat, water, and solids in a single pass.
The tallow or lard are valuable in other industries, and the separated proteins for aquaculture and animal feed applications.
Separating hemp biomass from alcohol is the primary step in producing CBD oil or extract. An Alfa Laval decanter centrifuge suitable for processing alcohol is an ideal way to separate large volumes of hemp biomass from the alcohol continuously.
A Class 1 Div 2 decanter exerts over 3,100 Gs of centrifugal force to separate the biomass to produce relatively clear alcohol. Though the alcohol retains some suspended solids, the decanter eliminates the laborious filtration process.
For large-volume hemp processing, a complete decanter centrifuge module, as shown above, includes a clean alcohol tank, feed and transfer pumps, a dry biomass auger, etc.
Carbon black is an industrial additive primarily used as a pigment in manufacturing. The production of carbon black from used tires is quite common. This process involves melting used tires using solvents and separating the carbon particles from the solvent using a centrifuge.
Due to the high percentage of carbon particles, a decanter centrifuge is well-suited for separating the solids from the solvent.
Standard filtration is unsuitable for this application because the carbon particles are sticky and tend to block the filter pores. Since a decanter centrifuge uses centrifugal force to separate the liquid from solids without using any media, it works well for this application.
Chemical industries often need to separate precipitates from chemical solutions. Decanter centrifuges are more suitable for large volumes than filters or filter presses.
The image above shows a 20 GPM decanter remanufactured and supplied by Dolphin Centrifuge for a thick chemical precipitate based on metal salts.
The ability to adjust the sludge dryness is an additional advantage of decanter centrifuges over other separation methods.
All distilleries generate grain mash that contains valuable saleable liquor. A decanter centrifuge is used in the brewing and distilling industries to separate spent grain from the liquid.
Breweries also generate similar organic waste that a decanter can separate to reduce waste volume, save disposal costs, and help with product recovery for other applications.
Like the grain distillation process, industrial ethanol production uses large quantities of corn. This process also involves the separation of corn biomass from syrup and alcohol.
Alfa Laval decanter centrifuges are widely used in all ethanol production plants to separate corn meal from the fluid with ethanol. Given that these centrifuges process flammable alcohol, these decanters must be suitable to operate in hazardous locations.
An Alfa Laval disc stack centrifuge downstream of the decanter polishes the alcohol to remove the fluid's remaining small suspended particles.
The food industry uses alcohol and other solvents to extract flavors from various aromatics, ingredients, and plants. The process involves blending the raw source of flavors with the solvent and the subsequent extraction of the solvent which has adsorbed the flavors.
Depending on the source product's volume, filtration or centrifugation can separate the solvent from the spent product.
A decanter centrifuge allows for the separation of this biomass from the solvent continuously. Therefore a decanter centrifuge is ideal for large volumes of such flavor-carrying solvents.
Again, a stainless steel disc-stack centrifuge downstream of the decanter polishes the solvent to remove all remaining small, suspended particles.
The production of fish meal involves large-scale cooking of unwanted fish parts that pass through a coarse strainer to remove large debris such as bones, etc. The cooked slurry then passes through a fish oil decanter centrifuge, separating the fish solids or fish meal from the liquid. The liquid phase consists of fish oil and stick water, which are valuable byproducts.
The output from the decanter is tunable for the desired amount of dryness. This fish meal is fish feed in aquaculture, mainly for shrimp farming.
The fats, grease, and other fluid waste collected from restaurants and other establishments are collectively known as grease trap waste. This fluid is a waste stream that needs to be disposed of while, at the same time, the fats in this waste have commercial value.
Separation of the sludge and water from grease trap waste is the first step in recovering the valuable fats used in animal feed and other industries.
Due to the large amounts of unpredictable sludge contained in grease trap waste, a decanter centrifuge is an ideal first step to separate the sludge from the fat and water.
| Decanter Model >> | Alfa Laval NX-314 | Sharples P-3400 |
| GTW Capacity | 25 GPM @ 150 F | 50 GPM @ 150 F |
| Max. Particle Size | 1/2" | 1/2" |
| Particle Separation Efficiency (Micron) | 50 Microns | 50 Microns |
| Max. Sludge Content | 30% v/v | 35% v/v |
| Motor Power | 15 HP | 25 HP |
| Bowl Speed | 4000 RPM | 4000 RPM |
| Max. G-Force | 3,100 Gs | 3,000 Gs |
| Material of Construction | 316L Stainless Steel Wetted Parts | 316L Stainless Steel Wetted Parts |
| Feed Connection Size | 1-1/2" | 2" |
| Max. Processing Temperature | 230 F | 230 F |
A three-phase disc stack centrifuge separates the liquid stream into fats and water in subsequent processes.
The photograph above shows a complete decanter centrifuge module designed and manufactured by Dolphin Centrifuge for grease trap waste processing.
The system includes an Alfa Laval decanter centrifuge, an electric preheater, a clean oil tank with pumps, and a fully automatic control system. The optional sludge auger is provided to move the sludge from underneath the decanter sludge chute away from the decanter base.
Humic fertilizer production requires soaking organic biomass in water and separating the water containing the essential nutrients from the spent biomass.
Given the range and type of particles in humic biomass, typical filters are unsuitable for this process. The smaller particles tend to plug up the filters quickly, requiring filter changes and associated labor.
A humic decanter centrifuge easily separates the biomass particles to 100-micron level while the separated water with nutrients exits the decanter from the fluid end.
The occasional presence of sand particles is a challenge for other separation methods due to the wear characteristics. A decanter centrifuge has an abrasion-resistant coating on surfaces prone to wear.
The process of making herbal extracts is similar to flavor extraction. The soaking of herbs in a solvent or similar medium is followed by solvent extraction from the spent herb biomass.
A decanter centrifuge uses centrifugal force to separate the biomass from the solvent. The decanter bowl rotates at a high rotational speed exerting tremendous centrifugal force on the liquid and solids. The heavier solids settle on the bowl wall, and the internal rotating auger pushes these separated solids out of the decanter bowl.
The washing of printing presses generates a wastewater stream that carries dry or thickened ink residue. The user cannot discard this water with the removal of this residue. At high volumes, a decanter centrifuge can separate this ink from the wastewater generating a relatively clean water stream that is dischargeable with or without further processing.
All industries generate some form of wastewater. Depending on the industry, this wastewater often carries large amounts of sludge. Sludgy wastewater is costly to handle and dispose of due to the volume and disposal costs.
An industrial wastewater decanter centrifuge can continuously separate the sludge from the wastewater at high separation rates. A typical decanter centrifuge can reduce the sludge content of an industrial wastewater stream from 40% to less than 1%.
If the wastewater carries oil, a three-phase disc-stack centrifuge can separate the oil from the water after the decanter has eliminated the sludge.
Kelp or seaweed is finding use as an organic fertilizer. The produce fertilizers from kelp, the depleted kelp biomass needs to be separated from the water with the extracted nutrients. The large volume of kelp in the water is a challenge for conventional dewatering technologies.
A decanter centrifuge can continuously separate up to 40% kelp biomass from water. The kelp and water mix goes through a macerator-type pump which shreds the kelp releasing the nutrients into the water. The dryness of the separated biomass is adjustable with the decanter centrifuge.
Also, the stainless steel construction of the decanter allows the use of salt-water kelp through the same equipment.
One of the most common applications of the decanter centrifuge is treating municipal sewage or wastewater. Almost all medium to large-scale municipalities uses decanter centrifuges for the primary treatment of sewage.
Decanter centrifuges are popular for this application due to their ability to process large volumes of wastewater at a high capacity. Also, the closed design of the decanter helps keep odors in check during the process.
Chemical dosing is often an option for municipal wastewater processing. Adding polymers increases the efficiency of the centrifuge while separating the smaller sludge particles.
Decanter centrifuges with over 500 gallons per minute processing capacity are available for such applications.
Organic waste from composting or similar methods carries large amounts of sludge containing various materials. This waste stream also carries water and fats from food waste. Before use, this compost needs to be dewatered.
A decanter centrifuge works well for this application. By dewatering the compost continuously, an Alfa Laval decanter reduces the volume of waste considerably. This reduction helps reduce transportation and disposal costs while producing high-grade compost, an organic fertilizer.
The separated fluid stream primarily consists of water with small amounts of oils and fats. A three-phase disc-stack centrifuge separates the fats from the water for water disposal.
The paper industry processes large volumes of wood pulp to produce paper. This production process generates volumes of wastewater with significant amounts of wood fiber and pulp.
A decanter centrifuge processes this water to concentrate the wood fiber and pulp with minimum amounts of water, which makes it cost-effective for disposal.
The poultry processing operation generates a waste stream of skin, fats, and proteins after separating meat from the carcass. The fats and proteins have commercial value once they are in separate phases.
An Alfa Laval three-phase decanter centrifuge can continuously separate the solids (meat protein & skin) from the water and fat. Separated chicken fat is also a suitable feedstock for biodiesel production.
The application of heat to organic biomass in the absence of oxygen creates pyrolysis or bio-oil. The predominant biomass used in pyrolysis is discarded rubber tires. The debris from the tires is often the contaminant that requires separation before this oil is useable as fuel.
A decanter centrifuge is perfect for separating metal wire strands and other solid debris from pyrolysis oil. The Alfa Laval NX-418 decanter centrifuge can process up to 50 GPM of bio-oil at 210 F to produce clean pyrolysis oil. The solids or separated sludge that is high in carbon and is also a valuable byproduct for black carbon production.
As with other applications, a disc stack centrifuge acts as a polishing centrifuge to remove the suspended particles from the fluid exiting the decanter centrifuge. Adding a disc stack centrifuge makes pyrolysis oil production a two-step separation process.
Multiple chemical and manufacturing processes use industrial resins as the primary ingredients. The production process for resins involves the chemical reaction of base ingredients in a fluid medium.
The separation process involves the separation of these solid resin particles from the liquid medium. A decanter centrifuge has the ability to separate large volumes of solids from the liquid and is, therefore, an ideal choice for this process.
The airtight design of decanter centrifuges is an added benefit to processing resins that emit vapors and other gases during processing.
A mechanical expeller crushes sunflower and other similar oil seeds to extract the oil contained in the seeds. The oil from the expeller carries seed debris and other contaminant particles. The process must remove this sediment contaminant before the producer can use the oil.
An Alfa Laval decanter centrifuge can separate the seed debris and other sediments, such as dirt and sand, from the oil.
The photograph above shows a complete sunflower oil separating decanter centrifuge module designed and manufactured by Dolphin Centrifuge. The module includes an Alfa Laval NX-314 decanter with feed and transfer pumps and a clean oil tank with all auxiliary sensors and instruments.
The process of cannabinoid extraction from the marijuana plant biomass involves the use of ethanol alcohol as a medium or solvent. The crushed plant biomass and alcohol combine to form a slurry. The alcohol absorbs the THC during this process.
The next step is the separation of the alcohol from the biomass. A decanter centrifuge can separate this slurry into partially dry biomass and the liquid ethanol carrying the THC.
Since the process uses alcohol which is flammable, the equipment, including the decanter centrifuge, needs to be suitable for hazardous areas such as Class 1 Div 1 or Division 2.
The photograph above shows a complete Alfa Laval NX-418 Decanter centrifuge module suitable for Class 1 Div 2 hazardous applications such as separating alcohol from marijuana or hemp biomass. The system shown is a complete module including a separate alcohol collection tank with feed and transfer pumps.
Used oil or used cooking oil is also known as waste vegetable oil (WVO). It is a waste product generated by the food industry. The food processing industry and restaurant waste combined are known as grease trap waste and contain high amounts of solid waste or sludge.
The used oil content of this used oil is a valuable product as a heating fuel and as feedstock for some biofuels such as biodiesel.
A decanter centrifuge separates the heavy sludge from the used oil collection. After separating the sludge from the oil, the three-phase disc stack centrifuge separates the suspended solids and water from this oil.
The system shown above is a modular unit that can heat and process grease trap waste through an Alfa Laval NX-314 decanter centrifuge. The blue tank, seen below the decanter, is the collection tank for de-sludged oil.
The decanter model (NX-314) is rated at up to 25 GPM on grease trap waste at 180 F. The used oil must be at an elevated temperature for optimum centrifuge performance.
Waste oil is a generic term to describe once-used mineral oil. There are multiple sources of waste oil, mainly automotive engine oil and industrial oils.
Waste oil collection companies mix different types of waste oil, generating a stream that is often high in solid content. Therefore, separating the sludge from the waste oil is essential before processing it further to recover the oil for reuse.
A decanter centrifuge (as shown above) is adept at separating large volumes of waste oil from the entrained sludge. The fluid exiting the decanter is mostly water and mineral oil with trace amounts of suspended solids.
Again, the integrated electric preheater raises the temperature of the waste oil to facilitate the easy separation of sludge from the waste oil at a maximum flow rate.
Yellow grease is another term for used cooking oil. We have covered this application in the used oil section above.
The mixing of zinc ash and sulphuric acid produces zinc sulfate. This process is a chemical reaction that produces zinc sulfate crystals and releases hydrogen gas. The crystals are the product of value and need separation.
Traditional methods use filter presses or other filtration equipment for this separation process. A decanter centrifuge automates this process while removing the manual labor required for filtration methods.
For more information about your specific application, visit our contact us page or call one of our engineers at (248) 522-2573.
by Sanjay Prabhu MSME
Engineering Manager, Dolphin Centrifuge