INNOVATIVE SOLID BOWL CENTRIFUGE TECHNOLOGY

Transcription

1 INNOVATIVE SOLID BOWL CENTRIFUGE TECHNOLOGY

2 Solid bowl centrifuge technology Modern centrifuges are used in technical processes for the mechanical separation of mixtures of solids and liquids. Sedimentation, centrifugation, and filtration are mechanical separation processes, in contrast to distillation, incineration and thermal drying, which are thermal separation processes. In many processes, mechanical separation is primarily responsible for product quality, production efficiency and environmental control. Mechanical separation processes are found in practically all industrial sectors, including food, chemical, pharmaceutical, biotech, mineral, and environmental. Advantages of modern centrifuges Modern centrifuges have many advantages in comparison to other separation processes such as filtration and sedimentation. Compact designs, sealed construction to control odor emissions and avoid contamination of the product, ease of operation with continuous or automatic control systems, and limited replaceable operating parts such as filter media or filter aids make centrifuges advantageous to use. 2

3 Applications The following basic process operations are possible with solid bowl decanter centrifuges: Clarification of liquids Dewatering of sludges and suspensions Thickening of slurries Separation of three-phase mixtures, i.e. two immiscible liquid phases and a solid phase Classification of solids in a suspension according to particle size (wet classification) Sorting of solids by density. To obtain optimum results, solid bowl decanter centrifuges must be custom designed to suit specific separation processes. FLOTTWEG CENTRIFUGES can more effectively help one reach their processing goals by offering a variety of basic designs, such as the DECANTER, TRICANTER, SEDICANTER and SORTICANTER. Solid bowl centrifuges are used in most areas of mechanical liquid-solid separation. = registered trademark in various countries 3

4 Typical processes Foodstuffs Chemical products Animal fat Blood Brewer s yeast and trub Casein Clarified butter Coffee essence Corn stillage Drinking water treatment Fish meal Fish water Fruit juices Gelatin Lactose Meat extracts Molasses Mycelia Potato protein Potato scrapings Proteins Sorbose Soybean flour Starches Vegetable extracts Vegetable juices Vegetable oils Wine and beer Aluminum hydroxide Barium sulfate Bauxite Bentonite Calcium carbonate Calcium fluoride Calcium sulfate Carbide sludges Caustic soda Cellulose derivatives Clay sludge Color pigments Cryolite DMT Epoxy resin Fluorescents Graphite Gypsum HDPE Iron hydroxide Iron oxide Kaolin Latex Lead oxide Lead sulfate Lignine sulfate Magnesium hydroxide Mica Mineral oil Nickel hydroxide Pharmaceutical intermediates Phosphate compounds Phosphoric acid Plastics derivatives/additives PMMA Polypropylene Polystyrene PVC Silica Silicate Sodium chloride Titanium dioxide Tricalcium phosphate Various salts Vitamins Zinc carbonate Zinc oxide Zinc sulfate Miscellaneous Coal tar cleaning Drilling mud Hide scrapings Industrial wastewater treatment Manure Municipal wastewater treatment Oil sludges Paint sludges Plastics sorting/recycling Steelworks sludges Examples from more than 300 different applications 4

5 Solid bowl centrifuges The basic principle of the solid bowl centrifuge has been known since the end of the 19th century. Over the course of time, technology improvements along with the availability of high strength and corrosion resistant raw materials have allowed solid bowl decanters to be applicable to many processes. The utilization of electronic and electromechanical measuring and control components has improved the performance and availability of the machines. The basic design of a solid bowl centrifuge is relatively simple and can be customized by Flottweg for different requirements. Of all modern industrial centrifuges, solid bowl centrifuges have the broadest range of application. 5

6 FLOTTWEG DECANTER CENTRIFUGES Feed The slurry is fed through a stationary pipe into the feed zone located in the center of the scroll. The product is then accelerated circumferentially and delivered through distribution ports into the bowl. Bowl The bowl has a cylindrical/ conical shape and rotates at a pre-set speed optimal for the application. The slurry rotates with the bowl at the operating speed and forms a concentric layer at the bowl wall. The solids contained in the slurry are deposited against the bowl wall by centrifugal force. The length of the cylindrical bowl section and the cone angle are selected to meet the specific requirements of an application. Scroll The scroll rotates at a slightly different speed than the bowl and conveys the deposited solids toward the conical end of the bowl. This differential speed determines the residence time of the solids in the bowl. Residence time is an important variable for the dry solids content. It can be adjusted by changing the differential speed of the scroll thus providing optimal separation. If the physical properties of the slurry change, FLOTTWEG DECANTERS can be supplied feed inlet solids discharge liquid discharge by gravity FLOTTWEG DECANTER for the liquid-solid separation with gravity overflow of the liquid phase (centrate) Eccentric adjustable weir plates (patented) with a different scroll design or by modifying an existing scroll. Scroll pitch and single or multiple flight configurations are important design variables. 6

7 Solids discharge Rotor bearing precise adjustment of the pond neering refinement that permits Settled solids are ejected A special selection and depth in the bowl. Overflow is quick and precise adjustment through ports at the conical arrangement of bearings pro- then collected in a centrate of the pond depth during end of the bowl into the solids vides long life and exceptional chamber and discharged by operation to accommodate housing and fall through to the reliability. A central lubrication gravity. changing conditions. discharge chute. system supplies either grease or oil to bearings. Impeller (skimmer) Materials of construction The clarified liquid can also be FLOTTWEG uses high-quality Overflow weirs decanted with an impeller and stainless steel for all wetted The clarified liquids flow to the discharged from the bowl un- areas. Bowl and scroll castings cylindrical end of the bowl der pressure. This eliminates are made from centrifugal cast where they exit over weir the need for a separate cen- high strength and corrosion plates. Easily adjustable preci- trate pump. The FLOTTWEG resistant stainless steel. sion weir plates allow for the adjustable impeller is an engi- liquid discharge under pressure feed inlet solids discharge FLOTTWEG DECANTER with pressurized centrate discharge Adjustable impeller

8 FLOTTWEG TRICANTER 3-phase separation The FLOTTWEG TRICANTER enables three-phase separation, i.e. the simultaneous separation of two immiscible liquids with different densities and one solid phase, provided that the solid phase is the heaviest phase. The most important difference from a decanter is the separate discharge of the two liquid phases. The FLOTTWEG TRICANTER discharges the heavy liquid through an adjustable impeller under pressure and the light phase by gravity. The adjustable impeller allows adjusting the separation zone and degree of separation within the machine during operation. This optimizes purity of the liquids and may possibly eliminate downstream equipment. discharge of heavy phase under pressure feed inlet solids discharge liquid discharge FLOTTWEG TRICANTER (THREE PHASE DECANTER) Discharge of the centrate: heavy liquid phase under pressure, light phase by gravity Adjustable impeller 8

9 FLOTTWEG SORTICANTER The innovative FLOTTWEG SORTICANTER is designed for the separation of solids by density. The process is aided by a carrier liquid with a specific gravity that is between the densities of the two solid streams to be separated. The patented FLOTTWEG SORTICANTER consists of a cylindrical conical bowl with a second inner cone at the cylindrical end and a double acting scroll conforming to the inner contour of the bowl. The bowl and lagging scroll rotate at a high speed in the same direction. The solid-liquid mixture is conveyed through the centrifuge feed pipe and inlet ports in the scroll body into the bowl and accelerated to the bowl speed. Centrifugal force causes the solids which are heavier than the carrier liquid to settle against the bowl wall. The scroll conveys the deposited layer of heavy solids toward the conical bowl section, over the drying zone and ejects them through ports into the stationary solids housing and down the discharge chute. The solids which are lighter than the carrier liquid float and are conveyed with the liquid toward the cylindrical end of the bowl. When the floating particles have reached the second inner cone, scroll liquid discharge under pressure feed inlet solids discharge of heavy phase solids discharge of light phase FLOTTWEG SORTICANTER for plastic recycling flights wound in the opposite direction to those conveying sedimentated solids transfer the lighter solids across a drying zone to the exit ports. The liquid is skimmed off and discharged under pressure by an impeller at the cylindrical end of the bowl. After an intermediate cleaning step, liquid may be recycled as carrier liquid. Carrier liquids with different densities enable the user to shift the effective interface zone. = registered trademark in various countries 9

10 FLOTTWEG SEDICANTER The FLOTTWEG SEDICANTER is used for the separation of solids from liquids when the solids form a soft but flowable sediment. The SEDICANTER is used in cases where the solids are too fine-grained to be processed in a normal decanter and the sediment cannot be easily discharged from the decanter due to its soft consistency. During the separation process, the liquid and solids move in the same direction without having to pass through a turbulent inlet zone. The centrate is discharged through an adjustable impeller within the scroll. The sediment formed in the SEDICANTER, the heavy phase, is accumulated and pressed out of the bowl under an immersion disc. Applications for the SEDICANTER include soft products such as biomasses, yeast suspensions, protein suspensions and fermentation broths. Technical features: Up to 10,000 x g centrifugal force possible to facilitate the separation of very fine, slowsettling solids Uniquely designed feed distributor and bowl seal to prevent foaming in the product inlet zone liquid discharge under pressure feed inlet solids discharge FLOTTWEG SEDICANTER Gastight machine design Clean-in-place provisions available to meet pharmaceutical industry standards Fluoropolymer rotor seals available for critical applications FLOTTWEG SEDICANTER S4E-3 Optional drives including the FLOTTWEG SIMP-DRIVE. 10

11 Centrifuge cleaning Centrifuges must always be cal and food processing appli- product-dependent. In most biotechnological and food flushed clean before shut- cations are designed with cases, the use of a solids-free processing industries to meet down. Depending on the Clean-in-Place (CiP) systems. centrate will be adequate. the highest demands for clean- application, different clean- Additional rinsing nozzles for liness. Requirements and ing systems may be incor- Cleaning of Centrifuges for cleaning the housing, the bowl specifications for design, porated into the centrifuge Standard Applications exterior and the scroll interior manufacturing and testing are design. For the majority of applications can be installed if required. according to specific company (e.g. sludges, separation of standards. FLOTTWEG CENTRIFUGES crystalline products), it is suffi- Cleaning of Centrifuges for are designed for continuous cient to flush the centrifuge Pharmaceutical, Biotechni- operation and do not need to before shutdown through the cal and Food Processing be opened for cleaning. feed pipe to remove deposits Applications FLOTTWEG CENTRIFUGES for of solids. The flushing time and FLOTTWEG designs its cen- pharmaceutical, biotechnologi- the type of cleaning fluid are trifuges for the pharmaceutical, Characteristic features of Rinsing nozzles are provided centrifuges to meet hygienic for the centrifuge housing requirements are: and for the interior of the All welds are ground to meet scroll body. specific sanitary finish stan- The centrate impeller is ad- dards. justable to facilitate flushing Special hygienic housing All product-contact parts are of the bowl. seals provided with a surface finish Frequency-controlled drives Electrically reversible scroll in accordance with specified for CIP-cleaning at low speed. rotation for enhancing clean- roughness values. Electropolished scroll, hous- ing during CIP cleaning. ing and bowl surfaces. = registered trademark in various countries 11

12 Drives General Decanter centrifuges are subject to two conflicting basic drive requirements. On one hand, the entire rotor has to run at high speed, and on the other hand, the scroll inside the bowl has to rotate at a very low differential speed and simultaneously at a high torque relative to the bowl wall. FLOTTWEG frequency controlled electric motors or speed-adjustable hydraulic motors offer infinitely variable speed. Long start-up times help overcome a high inertia moment and avoid peak loads during the initial current phase. FLOTTWEG offers hydraulic motors or gear drives to drive the scroll depending on the application. The majority of the drive configurations offer variable differential speeds. This ensures optimum adjustment to meet individual customer requirements. Fully hydraulic drive Hybrid drive Frequency inverter drive (VFD) 12 Fully hydraulic drive The bowl and the scroll are driven by separate hydraulic motors. A compact hydraulic aggregate with two variable pumps feeds two separate oil circuits. The volume flow of the oil determines the bowl speed and the differential speed of the scroll, whereas the oil supply pressure is directly proportional to the torque output and thus to the load. This drive permits the use of variably adjustable control, monitoring and analog control. The drive s design enables independent rotation of the scroll even when the bowl is shut down. Hybrid drive In this version, a frequencycontrolled electric motor drives the bowl instead of a hydraulic motor. The hydraulic aggregate for the scroll is compact because only one oil circuit is required. Control and adjustment are the same as with the hydraulic drive. Hydraulic drives offer particular advantages for applications in mobile processing systems. Their compact design (controls, aggregate) provides for optimal utilization of floor space. Another advantage is applicability in explosion proof areas.

13 Gear drive with frequency inverter A frequency-controlled electric motor drives the bowl via a V-belt drive. A second parallel V-belt drive with a slightly different transmission ratio powers a cycloid planetary gear and generates the differential speed of the scroll. The differential speed can be changed and adjusted by changing V-belt pulleys. The FLOTTWEG gear drive is the most basic drive solution and is particularly suited for separation processes which do not require operating adjustment of the differential speed. Backdrive with Dual-VFD This solution is derived from the FLOTTWEG gear drive with the scroll drive having its own frequency-controlled motor. The differential speed can be separately adjusted with a preset range and controlled and monitored independently of torque. Both drive motors are powered by a FLOTTWEG frequency inverter, which is power-linked via a regenerative circuit. This drive is best suited for high differential speeds. Bowl drive Scroll drive Backdrive with Dual-VFD SIMP-DRIVE = registered trademark in various countries SIMP-DRIVE The SIMP-DRIVE constitutes the new generation of the FLOTTWEG s dual frequency inverter back drive concept. This new electric drive arrangement includes the advantages of the hydraulic and electromechanical drives. The main feature of this new concept is a multi-stage planetary gear which allows for entirely independent operation and drive of the bowl and scroll (similar to a hydraulic drive) Benefits include: High efficiency and low energy demand A simple drive system not requiring linkage Independent frequency inverters (VFDs) which are standard designs, simple to operate and simple to maintain Constant torque, high solids Simple integration into process control systems Smallest possible inverter size High flexibility in the selection of the operating speed Discharge of the bowl even at full stop Applicable for small to medium differential speeds Low power draw. 13

14 Centrifuge controls Fluctuations of the solid throughput and concentration in the centrifuge may cause a decrease in separation results, blockage or an overload of the centrifuge. To avoid problems and to fully utilize the capacity of the centrifuge, the differential speed needs to be continuously adjusted for operating conditions. FLOTTWEG offers control systems for the differential speed which are based on the following principle. Scroll torque is a measure of bowl solids load. Load and torque should be kept at an optimum value. If the torque exceeds the optimum value, the FLOTTWEG control system increases the differential speed to convey the solid faster out of the bowl until the torque decreases. Conversely, the differential speed is reduced when the torque decreases. This automatic control process ensures optimum separation during normal operation. An integrated two-stage overload protection offers excellent control of the machine resulting from process deviations. If the increase in differential speed is not sufficient to compensate for a solids overload, the feed supply is stopped until the torque falls back below set Process control system 14

15 point. In the majority of situations, this is sufficient to remedy the overload without having to shutdown the system. If this measure is insufficient to keep the scroll torque from rising, the bowl drive is shut down when the torque reaches the second set point. As the bowl speed decreases, the torque is reduced and the machine will usually empty itself. Typically there is no need for manually removing the solids. Machines with hydraulic drive or SIMP-DRIVE enable solids discharge at full-torque scroll operation during the bowl shut down. FLOTTWEG provides all machines with adjustable differential speeds (hydraulic drives, dual VFDs and SIMP-DRIVE drives) with this control system. The range of control systems covers a basic version with a hydraulic-mechanical analog control via an electronic industrial control system to programmable logic controllers (PLC) and integration into distributive control systems (DCS). All electronic systems allow for remote control and monitoring. Programmable controls support a variety of complex links and monitoring for plant systems (e.g. CIP and automated process steps). = registered trademark in various countries PLC decanter controller 15

16 Sealing systems Most sizes and models of FLOTTWEG CENTRIFUGES are available in a variety of rotor and housing seal designs for the following operating conditions: atmospheric vapor-tight gas-tight FLOTTWEG CENTRIFUGES can also be adapted for operating in closed-loop systems. Atmospheric centrifuges are the standard version. They are used for applications where there is no harm from products or vapors released to the environment and where it is not necessary to isolate the centrifuge bowl from the surrounding atmosphere. Vapor-tight versions of FLOTTWEG centrifuges are the right choice in cases where substances emitted from the process could pollute the environment or if contact of the product with ambient air is undesirable. Additional seals on rotor shafts and housing provide the necessary seal. Emissions can be eliminated when purge gas/air is applied to seals or the centrifuge housing is vented. Atmospheric Vapor-tight Gas-tight Gas-tight centrifuges allow the safe operation with toxic, corrosive or flammable media by applying inert purge gas to rotor seals and by inertizing the 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. 16

17 Purging with inert gas Processing of hazardous and pharmaceutical industry, oxygen is reduced below criti- small overpressure. This pre- materials processes with flammable cal level with the inert gas. vents atmospheric air from Processes with any risk of organic solvents or oil sludge Purging is complete if a multi- penetrating into the system. explosion must be controlled treatment processes. These ple of the system volume has by using inert gas. Generally, centrifuges comply with passed through the machine or nitrogen is used. Centrifuges ATEX 95 in Zone 1, up to if an oxygen probe at the cen- and system parts used for the temperature class T4. trifuge housing shows a safe processing of hazardous mate- oxygen concentration. rials have to be gastight to pre- Purging vent the exit of vapors into the Before starting, the entire sys- Continuous inert gas supply atmosphere as well as to avoid tem including the centrifuge is After successful purging and the entry of air into the system. purged. For this purpose, large during the operation with prod- Typical examples are process- volumes of inert gas are flushed uct, sufficient inert gas is fed es in the chemical, petroleum, through the system until the into the system to ensure a Rotor Seal Housing Control of centrifuges system and product emission purged with inert gas is into the atmosphere. based on differential pressure FLOTTWEG purge gas control unit monitoring. Processing of materials Differential pressure monitoring susceptible to oxidation gas pressures are maintained maintains a fixed constant Often the processing of bever- at the centrifuge. In many overpressure in the sealing ages and food requires that cases, carbon dioxide is used system using control valves. products be prevented from as the inert gas. A system This ensures a small overpres- undergoing oxidation. For this monitoring the flow of gas is sure within the sealing system purpose the leakage of air into typically used. and the inside of the centrifuge the centrifuge is prevented by guaranteeing protection corresponding constructive against air leakage into the measures and positive inert 17

18 Lubrication FLOTTWEG CENTRIFUGES can be provided with different lubrication systems. The lubrication system depends on the type of operation, for example, batch or continuous operation and the degree of automation of the entire system. Central lubrication system All main lubrication points are permanently manifolded via tubing or hoses to a central pump. The lubricant is dispensed proportionally through a special piston distributor. The scroll bearings are permanently sealed and lubricated, but can also be re-greased manually. Automatic grease lubrication In contrast to the manual central lubrication system, the greasing system can Central lubrication system (manually operated) Automatic grease lubrication Oil droplet lubrication system 18 be automatically activated. This ensures the uniform and reliable lubrication of the centrifuge. It prevents bearings from being under- or over-lubricated and rules out short-term spikes in bearing temperatures and excessive grease consumption. The grease pump is automatically controlled. For many applications, an airoperated oil droplet lubrication system is supplied. Automatic oil droplet lubrication system The fully automatic oil-air lubrication system ensures optimal lubrication with oil droplets transported via air to the bearings. Optimum lubrication is achieved at high speeds, with low oil consumption and no loss in performance. Monitoring of the oil and air pressure guarantees high operational safety. Pneumatic designs are available for utilization in explosion-proof areas. They are suited for Zone 1 up to temperature class T4 according to ATEX 95. This system does not require oil recirculation or treatment.

19 Wear protection FLOTTWEG offers a wide range of wear protection to meet the requirements of the many different applications in which centrifuges are installed: [1] Welded hard facing or spray coating [2] Ceramic [3] Tungsten carbide tiles, brazed or bolted [4] Chill castings [5] Plastic liners In order to minimize maintenance costs for applications involving highly abrasive products, all wear protection elements, except welded hard facings or spray coatings, are field-replaceable. Illustration of replaceable wear protection elements 19

20 Centrifuge monitoring Vibration monitoring (standard) Vibration sensors transmit acceleration signals to an analyzer that sounds an alarm or trips the centrifuge upon reaching the full limit value. Temperature Monitoring (optional) Bearing temperatures are constantly remote-monitored in Flottweg centrifuges by means of resistance thermometers. Upon exceeding pre-set temperature limits, the centrifuge alarms or shuts down. This preventive measure safeguards against bearing failure or machine damage. Shock Pulse Measurement (SPM) (optional) The roller bearings in the centrifuge are monitored continuously using an SPM system. Shock-impulse sensors are installed at each bearing and connected to a central alarm. Pressure waves (stock impulses) emitted by damaged or worn bearings are picked up by the sensor and converted into an electrical signal An alarm is triggered if the signals from the sensor exceed a set limit more than once every 10 seconds. 20

21 Customer service Customer service is our preventive maintenance. Design and construction of ISO certification strength complete process systems FLOTTWEG is ISO 9001 Application-based project FLOTTWEG services Installation, commissioning, certified and manufactures its planning, high-quality manu- include: maintenance, repair and products in compliance with facturing and professional Competent advice on spare parts service world- all current technical standards. after-sales service are prereq- separation processes wide. uisites for customer satisfac- Pilot tests on-site or at the tion. Experienced and reliable Flottweg laboratory and test service engineers from our center customer service department Selection and specification FLOTTWEG products are are ready to respond quickly of equipment designed and manufactured to reduce down time. The Customer-tailored automa- in GERMANY! FLOTTWEG service group is tion/control systems and also available to perform process integration Service hotline Telephone +49 / / Telefax +49 / The Flottweg mobile test units. Service on call 365 days a year. 21

22 Solid bowl centrifuges Product lines and models Centrifugal force x g* DECANTER Z23-3 Z23-4 Z32-3 Z Z4E-3 Z4E Z5E Z6E-2 Z6E-3 Z6E Z Z Z * dependent on temperature and density of the slurry 22

23 Centrifugal force x g* TRICANTER Z23-3 Z Z Z Z4E-3 Z4E Z5E Z6E-3 Z6E SORTICANTER K4D K6E K6EF SEDICANTER PRODECANTER S3E S4E 6500 = registered trademark in various countries S6E 5000 * dependent on temperature and density of the slurry 23

24 FLOTTWEG subsidiaries around the world Australia Flottweg Australian Representative Office 90 A Pacific Highway Roseville, NSW 2069 Sydney AUSTRALIA Telephone +61/ Telefax +61/ flottwegsydney@oz .com.au China Flottweg Separation Technology (Shanghai) Co. Ltd. No. 516, Chunzhong Road Xinzhuang Industrial Zone Shanghai P. R. CHINA Telephone +86/ Telefax +86/ flottweg@online.sh.cn CIS/Russia Flottweg AG Kutusowskij Prospekt 7/4 korpus 1, Office Moskau CIS/RUSSIA Telephone +7/ Telefax +7/ flottweg.moskau@flottweg.com France Flottweg France SAS Technoparc-Espace Media 3 rue Gustave Eiffel Poissy Cedex FRANCE Telephone +33/ Telefax +33/ france@flottweg.fr Germany Flottweg AG Vertriebs- und Service-Center Büro Nord-Ost Handelsplatz Leipzig GERMANY Telephone +49/ Telefax +49/ leipzig@flottweg.com Flottweg AG Vertriebs- und Service-Center Büro Nord-West Rösrather Straße Köln GERMANY Telephone +49/ Telefax +49/ koeln@flottweg.com Italy Veronesi Separatori SPA Via Don Minzoni, Villanova di Castenaso Bologna ITALY Telephone +39/ Telefax +39/ info@veronesi.separatori.com Mexico Flottweg Mexico S.A. de C.V. German Centre Office N , Av. Santa Fe 170 Col. Lomas de Santa Fe Mexico, D.F. MEXICO Telephone +52/ Telefax +52/ juan.gaviria@flottweg.com Poland Flottweg Polska ul. Pelplinska 8b Warszawa POLAND Telephone +48/ Telefax +48/ FlottwegPoland@flottweg.com USA/Kanada Flottweg Separation Technology, Inc Toebben Drive Independence, KY41051 USA Telephone +1/ Telefax +1/ sales@flottweg.net For more than 50 FLOTTWEG representatives worldwide see our homepage: contact/service/addresses Representative: PR 0004 I / 09