Moving bed filter

The trend in the use of deep bed filters in water treatment is to eliminate conventional flocculators and sedimentation tanks, and to employ the filter as a flocculation reactor for direct filtration of low turbidity waters. The constraints of batch operation can be removed by using one of the available continuous filters which provide continuous backwashing of a portion of the medium. Such systems include moving bed filters, radial flow filters, or traveling backwash filters. Further development of continuous deep bed filters is likely. Besides clarification of Hquids, which is the most frequent use, deep bed filters can also be used to concentrate soflds into a much smaller volume of backwash, or even to wash the soflds by using a different Hquid for the backwash. Deep bed filtration has a much more limited use in the chemical industry than cake filtration (see Water, Industrial water treatment Water, Municipal WATERTREATiffiNT Water Water, pollution and Water, reuse). 

In an in-bed filter (also known as deep filtration) the particles are separated throughout the whole depth of the filter. The filter is either made of fibers (filter mats) or of collector bodies, see Figure 3.2.1. Collector bodies are applied when the operating conditions are extreme as per the temperature (up to 1400 °C) and the nature of the entrained particles (sticky and abrasive). For separating sticky particles or droplets of high viscosity a moving bed filter can be applied. Movement... 

Delft University of Technology carried out a series of experiments in a counterflow moving bed filter similar to that for Combustion Power Company but employed a simpler feed system for the granular media [9]. These tests indicated acceptable collection efficiencies only at relatively low filter velocities. 

Experiments were performed to establish appropriate hydrodynamic behavior of the moving bed filter. Tests were performed with a plexiglass prototype using soda-lime glass beads as the granular material and air as the gas stream. All tests were conducted at room temperature (25 C) and atmospheric pressure. 

J., "Use of a moving bed filter for cleanup of hot producer gas," Fifth International Biomass of the... 

From an industrial viewpoint, hot gas cleanup of particulates using ceramic or metallic barrier, or granular moving bed, filters [48, 49] has proved a commercial success [50]. The only disadvantage is the higher investment cost, due to construction material requirements and the higher gas volume to be dealt with as a result of high-temperature operation. However, in most cases, this is more than compensated for by the reduction in the overall process costs. 

It is recommended that a filter screen be used ahead of and in conjunction with filters of this type. Continuous self-cleaning filters of this kind are considered to be one of the most reliable types of bulk water filter available, with low plant costs and high clarification efficiencies. A full scale array of moving bed filters is shown in Figure 4.6. 

Filtration is employed when the suspended soUds concentration is less than 100 mg/L and high effluent clarity is required. Finely dispersed suspended soUds require the addition of a coagulant prior to filtration. Filters most commonly used in wastewater treatment are a dual media (anthrafUt and sand) or a moving bed or continuous-backwash sand filter. Performance data for the tertiary filtration of municipal and industrial wastewater are shown in Table 10. 

It is convenient to classify centrifugal filters into two broad classes, depending on how the solids are removed fixed bed or moving bed. 

Screen/Classifier Hydroclone Rotary Drum Filter Filtering Centrifuge Moving Bed Dryer Fluid Bed Dryer... 

In the recent years Simulated Moving Bed (SMB) technology has become more and more attractive for complex separation tasks. To ensure the compliance with product specifications, a robust control is required. In this work a new optimization bas adaptive control strategy for the SMB is proposed A linearized reduced order model, which accounts for the periodic nature of the SMB process is used for online optimization and control purposes. Concentration measurements at the raffinate and extract outlets are used as the feedback information together with a periodic Kalman filter to remove model errors and to handle disturbances. The state estimate from the periodic Kalman filter is then used for the prediction of the outlet concentrations over a pre-defined time horizon. Predicted outlet concentrations constitute the basis for the calculation of the optimal input adjustments, which maximize the productivity and minimize the desorbent consumption subject to constraints on product purities. 

Horizontal basket or moving bed solvent extractors are preferred over vertical tower extractors in processing safflower cake. The fibrous nature of safflower provides a natural channel through which the solvent can move, and the bed acts as a natural filter medium. Tower extractors generally have problems extracting... 

GAC may be used in fixed or moving beds and in downflow or upflow mode. Fixed beds are operated in downflow mode and as such, provide some amount of solids filtration however, influent solids concentration must be kept low (less than 5 mg/L suspended soHds) to prevent rapid plugging of the bed. Filtered solids are periodically removed by backwashing. Upflow beds are more tolerant of soHds because they are fluidized and expanded by the wastewater entering at the bottom. In moving beds, the flow is countercurrent and makeup, fresh carbon is added continuously at the top of the unit while an equal amount of spent carbon is removed from the bottom. 

Design Of A Moving Bed Granular Filter For Biomass Gasification... 

Based on observations by other researchers that formation of a dust cake is important to efficient dust collection for fixed bed granular filters, we have developed a new concept for a moving bed granular filter that makes use of this property. The goal is to establish a quasi-steady dust cake that is continuously or periodically renewed on the upstream side of the dust cake and swept away on the downstream side. 

The effects of three design features on performance of the moving bed granular filter were evaluated. These features include the screened disengagement section the tangential inlet and flow straightening fins above the gas engagement section. 

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