Thickener tanks, rakes and feedwells are custom designed, based on the feed conditions and raking capacity. Design procedure the thickener area is also required for this calculation. Using hmhec as a cothickener will aid pigment dispersion if added during the grind, sag resistance, and viscosity retention on tinting. Clarification is the separation ofsolids from the liquid stream to produce a clarified efflu. Equipment design there are three main types of thickenersclarifiers. Improve clarifier and thickener design and operation. Service should mechanical or process problems arise, an experienced. These theories have been applied to the solution of the same problem, wherever applicable, to reveal the relative outcome of the solutions for comparison. The design involves selecting a typical solids flux and calculating the required surface area by dividing the anticipated solids feed by the flux 3. They are usually only economical for diameters of fewer than 100 feet.
Solids throughput is an important criterion in the design of thickeners. Calculation of thickener area and depth based on the data of batchsettling test received 7 june 1983. It is designed to take dilute sludges and thicken them allowing for more cost. The settling rate of any pulp is easily determined by simple laboratory tests such as outlined below. An appropriate gravity clarifier design involves taking account of the potential overloads and septic condition development. Oct 23, 2000 a key factor in selecting thickeners for lowsheen paints is the degree of leveling required. It is employed mainly in design calculations to determine the required thickener. Typical test is done by using a mlgraduated cylinder. R h e o l o g i c a l a s s e s s m e n t a r o a d m a p f o r p l a n t d e s i g n e r s a n d o p e r a t o r s. The computeraided design cad files and all associated content posted to this website are created, uploaded, managed and owned by third party users.
In the bridgesupported design, suitable for thickeners up to 50 m in diameter, the drive is supported by the bridge, driving the rakes with a centre shaft. Calculation of thickener area and depth based on the data of. Columnsupported design drives are supported by a stationary centre column of steel or concrete, and are practical for thickeners. It is the best technique if the iaboratory data is available. Grant road, suite 106 tucson, arizona 85745 introduction feed dilution or solidsliquid weight the english word sedimentation ratio is derived from the latin verb sedere size and shape of the particulate meaning to sink down. Design and construction of sludge treatment facilities table 6. The use of these additives cut across several process industries including food, pharmaceuticals, cosmetics. The torque, in turn, depends on a k factor and the thickener diameter based on the following formula. Theory and application of thickener design a g waters abstract theory the sedimentation vessel has a constant crosssectionalarea the process is onedimensional and so there is no radial variation in concentration for any horizontallaycr iii the slurry can be treated as a continuum with a continuous liquid and solid phase interacting with each. A design method for thickeners and clarifiers known as the batch flux curve technique was developed over 20 years ago, but still is not wellknown in design and operating circles. High rate thickener feed wells are designed to disperse flocculants thoroughly into the feed end to admit the flocculated slurry into the settling zone of the thickener without destruction of the newly formed floccules. Water authority is seeking information from interested firms and individuals, hereinafter called offerors to participate in a process to identify a rotary drum thickener manufacturer on which to base the design of a new rotary drum thickener facility. Thickening is a procedure used to increase the solids content of sludge by removing a portion of the liquid. The basic design of a high rate thickener is below.
Flocculation of sludge is the step in the process where destabilized particles are agglomerated in aggregates called flocs. A guide to understanding and mixing thickeners rheology modifiers, commonly referred to as thickeners or viscosifiers, are everpresent in most products. The gravity thickening design is similar to a clarifier. Steady state thickener modelling from the compressive yield stress and hindered settling function. The use of 3d dynamic models ensures integrated design. Operating lines of runs b constant downward velocity of the mixture. Pdf the common thickener underpins the performance of most hydrometallurgical facilities. In a bridge support thickener, such as the one shown below, the rakes and drive mechanism are suspended from a bridge that spans the diameter of the tank. Decant sufficient clear water or solution to establish a pulp with intermediate density. Solids contact and clean water treatment circular clarifiers. Design and development of a novel thickener feedwell using.
Such jumbo thickeners, when centrally driven, require for most demanding applications extra heavy duty drive heads some of which reach a continuous operating torque of 3. Flocculants, with their very high molecular weights long chains of monomers and their. Work done by kynch 12 was quite important as it was the basis of many further studies of thickening. A key factor in selecting thickeners for lowsheen paints is the degree of leveling required. Mip thickener design the following is a short cut to designing your own thickener. Functions of a clarifier the final clarifier must perform two primary functions. Many thickener installations operate with water recovery below design limits largely through conservative control and low prioritization of thickener optimization. Several iterations of area may be required to achieve a practical thickener size and pumping rate. The role of thickeners in optimizing coatings formulation. As a first stab we can either use the thickener flux m2tpd or the rise rate, depending if solids loading is the dominant eg. The sludge is conveyed inside the drum due to the drum inclination, as well as the combined action of the drums rotating movement and its internal design. A retrofit service is offered to enhance performance of existing thickeners and clarifiers.
Keywords thickener, feedwell design, flocculation, energy. The hase thickener which contains a very strong hydrophobe shows, with all binders, the strongest low shear thickening. The operation of the thickener must accommodate fluctuations control for disturbances in the process feed stream to deliver a clear overflow and thickened underflow. Interestingly, the drying time in the pilot plant ranged 710 days. Tank design uses 3d dynamic models and follows the sans api and other best practice international codes. The thickening equipment of gold cyanide factory adopted hydraulic motor driving center thickener, the capacity does not meet expected goals, and the timing of rake lost working hours, the working efficiency is low. The powerdrum pdr drum thickener for sludge thickening may also be used to lower the hydraulic capacity of the dewatering equipment installed in the downstream process. Cationic flocculants represent the large majority of the chemicals used in sludge dewatering. Barrientos department of metallurgical engineering university of concepcion abstract in this work we analyze, in the light of their physical foundation, the different methods of thickener design that have been proposed in the literature. The monroe environmental secondary clarifier often called final clarifier effectively separates the biological floc and colloidal solids to produce wastewater with very low levels of organic material and suspended matter.
Hydraulic motor driving center thickener is a mining thickener. The volute thickener is a very simple piece of equipment that is virtually maintenancefree and fully automated. The work of this section includes providing equipment for dissolved air flotation thickener daft units for the concentration of mixed primary and secondary sludges and scums as. Mip thickener design the following is a short cut to designing your. Thickener design pdf, mining thickener, thickener tank. The cfb 450 sludge thickener as per request grabcad. Simulation of batch and continuous thickeners sciencedirect. The solids flux curve is used to model the process of continuous sedimentation. Outotec drive range encompasses single planetary and multipinion gearboxes with hydraulic or electromechanical designs for full span and centre column thickeners. This chapter presents different theories of thickener design. Thickeners and clarifiers complete range of reliable and cost. Using hmhec as a co thickener will aid pigment dispersion if added during the grind, sag resistance, and viscosity retention on tinting.
A slowspeed hydraulic motor, acting through a high efficiency planetary gearbox, is used to drive the rakes. On this basis, the client increased two improved hydraulic motor driving center thickener. The torque capability of a thickener drive is specified as duty rating being the maximum mechanism design strength or the 100% setting on the torque control box. Powerdrum pdr drum thickeners for sludge thickening. In high rate thickener hrt designs the rise rate or solids loading will dictate the required tank diameter for any given throughput. When built, each thickener is designed specifically for the. Knowing how to size a thickener and determine the capacity required to handle a predetermined tonnage of a certain pulp, by overflowing a clear solution and obtaining the desired pulp density of thickener discharge, depends upon the settling rate of that particular pulp. If leveling is crucial, an nsat is recommended as the primary thickener. Reliability over fifty years of experience in the design and manufacturing of sedimentation systems allows us to produce mechanisms that are characteristically troublefree in both installation and operation. Recall typical hydraulic loading on a gravity thickener is.
Roytec thickeners are used extensively in ccd applications. The heur rheology modifier contains a somewhat weaker hydrophobe and therefore is more selective towards the associative interaction with different latex surfaces. A number of operational factors complicate this application, but indications are that the new feedwell has led to improvements in stability and underflow properties. Simulation of batch and continuous thickeners 2045 100 b1 cr b3 1 e. Bridgesupported mechanisms for tank diameters to 50 feet. The volute thickener design is based on the patented dewatering drum design used for the pwtech volute dewatering press sludge dewatering unit. The new feedwell design has been installed in a fullscale thickener at an anglo american platinum site in south africa. An informal survey of major clarifier and thickener manufacturers found that none of the firms surveyed use this method for sizing and maximizing operating conditions. Outotec thickening technologies leading edge technologies for thickening and clarifying outotec is a global leader in the design, fabrication and supply of thickening and clarifying solutions for the minerals industry. Kynch carried out a theoretical analysis of concentration changes which can occur during. A continuous thickener is to be designed to deal with the effluent from the last question. Unlike conventional thickeners, high rate thickeners must use flocculants.
Critical in the design of the thickener area is the minimum solids handling capacity. Design of gravity thickener is the concern of this chapter. Rise rate parametrizes the area required to recover the design flow or solids loading, the design dry tonnage. To avoid possible odors, the thickener is often covered with a sealed housing. The revolutionary outotec high rate thickener has pioneered and redefined thickening and clarifying methods around the world. A thickener with center hydraulic driving and hydraulic automatic rake lifting.
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