Major Equipment Design - Centrifuges In The Pre-treatment Section Of

Major Equipment Design - Centrifuges In The Pre-treatment Section Of Major Equipment Design - Centrifuges In The Pre-treatment Section Of PHB Production â€" Assignment Example > Type of Major Equipment Designed: Centrifuges in the Pre-treatment Section of PHB ProductionExecutive SummaryIn this project, a decanter centrifuge for PHB, a biodegradable polymer is designed for the pretreatment process of PHB production. It is intended to be used in the separation of PHB from cell residues that are used in the bio-production of the material. The centrifuge is designed with an inflow rate of 0.77m3/hr. of PHB at a speed of 6000 RPM and a maximum g-force of 10000g. Given these design parameters, the diameter of the bowl is determined as 0.5m and the length as 4.0 m. This particular centrifuge works by conveying the solid-filled sediment towards one end of the drum by a shaft rotating at a relative speed to that of the bowl, and the clarified liquid is conveyed towards the opposite end. As a measure to minimize the cost of the equipment, a single centrifuge is used to separate the solids from the liquid in three passes to ensure clarity of the liquid and maximum r ecovery of the solid part. Careful selection of materials has been done to design the components of the machine, taking care of strength, toughness, resistance to corrosion, thermal and pressure resistance among other considerations. In addition, there is an instrumentation and control part of the design that will enable optimum control of process parameters to ensure a smooth production process through the production period if the design is implemented. 1.0 Literature Review and Assessment of Alternatives1.1 General InformationThere are various methods used in the recovery of PHB from bacterial cell matter. These include vacuum filtration, ultrafiltration, microfiltration, candle filtration, press filtration, flotation, and centrifugation. Several of these recovery processes have been investigated in order to come up with the most economic method to isolate and purify PHB. It is used in the separation of cells and particulate materials after the fermentation stage. Centrifugation is the most ideal method that is normally used to separate PHB from the medium (Harker, et al. , 2013). Following this, PHB extraction and purification can be achieved using a number of ways. The most existing methods for the recovery of PHB involve using organic solvents, such as chloroform and acetone, and use of a hypochlorite, such as sodium hypochlorite. Centrifuges use a centrifugal force generated by high speed rotations to separate solid suspensions from liquids. In the processing of PHB, centrifuges are used to recover and clarify the biomaterial from a mixture of PHB and cell matter (Pohorecki, et al. , 2010). Centrifuges can either be sedimentation units or filtration units. In a sedimentation centrifugal unit, separation of substances relies on the difference in their densities. As the slurry is fed into the spinning centrifuge, an annulus is formed next to the bowl wall and the liquid is picked up by a skimmer (Van Wegen, et al. , 1998). The solid material is the rem oved from the centrifuge quite often to enable a continuous separation process. Filtration centrifuges, on the other hand, filter the material by use of a rotating basket with a filter medium and a centrifugal rotational force expels the liquid via the filter (Tarleton Wakeman, 2011). A large scale centrifugation equipment is made of disk-stack and decanter centrifuges. The disk-stack centrifuges run at higher speeds and remove lighter biomass material. When coagulant agents are available, the decanter centrifuge improves in performance. Centrifugation does not need filter aid, which counts as one of its most significant advantages against the rotary vacuum filtration. To recover the PHB biomaterial, the paste obtained is normally washed and returned to the centrifuge for another pass.