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 D-Series Super
FLSmidth Krebs has been providing elastomer lined hydrocyclones since 1952 to mining and other process industries. The Krebs Cyclone has been the standard design since then. Fully replaceable rubber liners inside metal housings were pioneered by Krebs. Since 1952 numerous design and material improvements have been made including the introduction of our complete line of Super Cyclones.
Please contact FLSmidth Krebs or your local representative if you have any questions or would like a specific hydrocyclone recommendation.  Features and Benefits
Super Cyclones Specifications:
As mill circuits have grown in size and tonnage hydrocyclone designs were required to meet the difficult service required. This led to the development of the Krebs Super Cyclone line introduced in 1989. The design features of the Super Cyclone are as follows:
Fully one inch thick replaceable natural rubber liners for all housing sections (synthetic rubber liners are also available). The use of one inch thick rubber liners increases the life of the part by 3 to 4 times compared to standard 5/8 inch thick rubber liners.
Talon flanges to hold the liners in place without the use of adhesive.
Cone liners with profiled shape at the bottom of each liner, which increases wear life at the highest wear point on the liner.
Full line of hydrocyclones available, 10 inch (DSF10LB), 15 inch (DS15LB), 20 inch (DS20B and DS20LB), 26 inch (DS26), and 33 inch (DS33). The DS33 Cyclone is the largest hydrocyclone on the market with fully replaceable liners for all housing sections.
As with all Krebs elastomer lined hydrocyclones, each Super Cyclone is available with a large selection of vortex finder, inlet head and apex sizes to provide flexibility in adjusting hydrocyclone performance or capacity.
Super Cyclone Improvements:
Krebs has worked with customers over the past 5 years to continually improve the Super Cyclones.
The natural gum rubber compound has been improved.
A wide range of silicon carbide materials are available for the cone sections, apexes and vortex finders.
The DSF10LB, DS15LB, and DS20B Super Cyclones are now available with 10.5 degree cone sections to compliment the standard 20 degree cones. The use of a 10.5 degree cone produces a finer separation and a higher volumetric capacity.
The inlets of all the Super Cyclones have been redesigned with a smooth inlet transition with rounded corners to increase the wear life of the inlet head liner.
For equipment recommendations or additional information on a specific hydrocyclone for your application, please complete the Product Recommendation Form.
Krebs Standard Elastomer Lined Hydrocyclones
Krebs D-Series Cyclones have long been the standard for handling abrasive slurries seen in the hard rock mining, coal mining, aggregate and other process industries. With the addition of the Super Cyclone line the use of the standard hydrocyclones is in application with minimal expected cyclone wear. The standard D-Series Cyclones are also used for applications requiring urethane liners since the overall thickness of the liners does not impact liner performance, as is the case with rubber liners.
Design features of all Krebs elastomer lined hydrocyclones (including Super Cyclones):
- Fully involute feed entry design reduced turbulence in the inlet leading to sharper separations and less wear than standard tangential or squeezed type tangential inlets.
- Replaceable gum rubber or synthetic liners for all housing sections.
- Cylinder section is included in standard hydrocyclone models. Double cylinder sections are also available.
- A range of silicon carbide and alumina liners are available for the cone sections, apex, and vortex finders.
- A variety of apex designs are available including manually adjustable, air adjustable, hydraulically adjustable, and different fixed apex designs.
- Krebs Engineers has the best manifold designs available. We custom design each manifold for the requirements of the application.
- Best of all, Krebs Engineers provides full service to assist you in selecting or optimizing the performance of your hydrocyclones. Please contact us for assistance or for additional information.
Sizing and Selection of Hydrocyclones
Krebs Engineers' approach to sizing hydrocyclones is to first size the hydrocyclone based on the separation required and then to select the number of hydrocyclones of that size required to meet the flow rate. Krebs uses the Lynch & Rao hydrocyclone model but we have developed all of our own D50 and correction factors internally from our over 60,000 hydrocyclone installations. For more details on the various factors, which affect hydrocyclone separation and capacity, please see The Sizing and Selection of Hydrocyclones.
The length of the hydrocyclone affects the separation.
The longer the hydrocyclone, the finer the separation. The length of the hydrocyclone can be increased by using longer cylinder sections or by decreasing the cone angle. The cylinder can be increased but if the cylinder is too long the angular velocity of the slurry will decrease and the separation will coarsen. We normally recommend no more than two cylinder sections, which is twice the diameter of the hydrocyclone for 20 inch and smaller hydrocyclones. A finer separation can also be achieved by decreasing the cone angle. This increases the cost of the hydrocyclone and will also reduce the maximum underflow density achievable with the hydrocyclone. We normally recommend 20-degree cones for 10 inch and larger hydrocyclones. In a typical grinding circuit application in the mining industry (and other applications), the separation can be adjusted by simply adding additional dilution water. This change combined with the 20-degree cone will maximize the efficiency of the hydrocyclone and result in the lowest possible amount of fines returning to the mill. The use of longer, smaller angle cones is best when the installation does not allow the use of additional dilution water and a finer separation is required or if a fine separation is required and the feed density is already very dilute, as is the case in coal classification applications. A very high-density overflow requirement is common in the gold industry in applications which do not have thickeners. For further details, see The Use of Hydrocyclones in the Gold Industry.
The correction factor for hydrocyclone density is not constant.
The correction factor for density is to correct for the viscosity of the slurry. In most cases an actual viscosity reading is not possible to obtain so the correction factor is related to hydrocyclone density. As the density increases, the viscosity increases. This relationship is not uniform for all slurries. A slurry consisting of all kaolin clay will be far more viscous at 20% solids than silica sand slurry at 50% solids. Krebs Engineers has the experience necessary to adjust this correction factor for the different slurries encountered in industrial applications.
Flat bottom cyclones have gained some acceptance in recent years. The installation of a fully flat bottom in place of the conical section will coarsen the D50 separation by over 2 times. In addition, the sharpness of the recovery curve will decrease significantly. Thus, flat bottom hydrocyclones should only be used for applications in which a coarse separation is required. The flat bottom hydrocyclone produces a very clean underflow but at the expense of a large amount of misplace coarse solids in the overflow. Krebs Engineers has fully flat bottom hydrocyclones along with 90-degree cone angles.
Maintenance
The replacement of the rubber liners is made easy using the Krebstik® adhesive. This adhesive dissolves the old glue, acts as a lubricant while installing the new liners, and does not form a permanent bond thus easing the removal of the old liners. The instructions for replacing liners is straight forward. The only warning is the larger cone liners and cylinders must sit with weight on one end for a few hours in order to allow the adhesive to set. Otherwise the liner will actually push out of the housing. The natural gum rubber liners wear better under compression, thus the liners are designed to be slightly larger than the housings.
 
Materials
FLSmidth Krebs has the most complete line of wear materials available for our hydrocyclones. The following is a list of the wear materials available.
- Natural Gum Rubber
- Synthetic Rubber (various types)
- Urethane (various types)
- Nitride bonded silicon carbide
- Reaction bonded silicon carbide
- Composite metal ceramic
- Alumina bonded silicon carbide
- Alumina ceramic
The following is a list of housing materials available for some or all parts.
- Steel
- Aluminum
- Fiberglass
- Cast urethane
- Stainless steel
- Other alloys upon request
Questions and Answers Q: How do you define separation?
A: The separation or cut point produced by a hydrocyclone is normally defined in three possible ways:
- The D50 point is the size of particle which has a 50% chance of reporting to the hydrocyclone underflow. This is the most common way to define separation when modeling a hydrocyclone.
- The mesh of separation or D95 or D98 is the particle size which has a 95% (or 98%) chance of reporting to the hydrocyclone underflow. This is often called the cut point.
- 3. Finally the separation is often defined as being a certain percent passing in the overflow. A P80 separation is the micron size in which 80% of the hydrocyclone overflow is finer than that size. A P95 separation is the micron size in which 95% of the hydrocyclone overflow is finer than that size. The P80 (or P95) produced by a given hydrocyclone will be determined by the D50 produced by the hydrocyclone, the sharpness of the separation and the size distribution of the hydrocyclone feed.
Q: What is the lowest and highest pressure drop that can be used when operating a hydrocyclone?
A: The lowest pressure drop is the minimum pressure drop required to produce a strong vortex in the middle of the hydrocyclone. For small diameter hydrocyclones (4 inch to 10 inch) this is 3 to 4 psi. For larger diameter hydrocyclones it is 5 to 7 psi.
There is no theoretical maximum pressure drop. The higher the pressure drop, the finer the hydrocyclone separation and the greater the hydrocyclone volumetric capacity. However as pressure drop is increased, the energy used by the pump increases and the wear in the hydrocyclone and pump increases. In most applications the pressure drop does not exceed 30 to 40 psi for small diameter hydrocyclones (4 inch to 10 inch) and 20 to 25 psi for larger diameter hydrocyclones.
Q: What is the range of vortex finders that can be installed in the hydrocyclone?
A: The vortex finders normally range from a minimum of 20% of the hydrocyclone diameter to a maximum of 45% of the hydrocyclone diameter.
Q: What affect does the apex have on the separation achieved by the hydrocyclone?
A: The apex is sized to discharge the underflow solids at the maximum possible density and to handle the full range of operation without roping or plugging. The affect of the apex size on the separation is minimal if the apex is not constricting the underflow discharge and if the apex angle has been properly designed. If the apex is too large the underflow density will be reduced. This does not affect the separation but it will lead to more displaced fines in the underflow.
Q: Does Krebs have specific manifold designs for multiple hydrocyclone installations?
A: Krebs has over 1,500 different manifold general arrangement drawings.
Q: Is the involute feed better than the standard tangential feed?
A: The involute feed is now recognized as the standard for high efficiency hydrocyclones compared to standard tangential or pinched tangential type feed designs. This type of hydrocyclone entry preclassifies the solids prior to entering the hydrocyclone. This reduces the coarse bypass of solids to the overflow as most of these solids are already along the outside wall of the hydrocyclone and thus are less likely to be pulled to the hydrocyclone overflow. It also reduces wear on the inlet head liner as impingement against the far wall is reduced.
Q: Can Krebs perform testwork on my sample?
A: Krebs has a hydrocyclone pilot plant for doing customer testwork in Tucson, Arizona.
INSTALLATIONS:
Krebs Cyclones are installed in mining and other industrial plants around the world. Over 60,000 hydrocyclones have been installed worldwide. Please contact Krebs for more information on the installation of Krebs Cyclones for your industry.
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