Decanter Centrifuge: Ethyl Acetate Design, Safety & Operation

This report provides a comprehensive overview of decanter centrifuges, focusing on their process description, design heuristics, and safety aspects. It begins by explaining the operating principle of decanter centrifuges, which relies on separating materials of varying densities through centrifugal force. The report details the process characteristics, including centrifugal force, sedimentation rate, and differential speed, and their impact on liquid clarity. Furthermore, it explores design heuristics such as process scale and length-to-diameter ratio, which are crucial for optimizing performance and economic value. A significant portion of the report is dedicated to control safety aspects, emphasizing adherence to international standards, the implementation of control systems, and the importance of basket/bowl design and inspection. The report references several key publications, adhering to Harvard referencing style, to support its analysis of decanter centrifuge technology and its safe and effective application in industrial settings. Desklib provides this document and many similar solved assignments to aid students.

Decanter Centrifuge 1
Decanter Centrifuge
By Name
Course
Instructor
Institution
Location
Date

Decanter Centrifuge 2
Decanter centrifuge
A centrifuge is a high-speed rotating device that separates materials of varying densities.
A decanter centrifuge aids in separating solids components from liquids hence therefore of
importance in chemical industry (Records & Sutherland, 2011). There exist several factors
affecting decanter centrifuge performance including design factors and aspects.
Decanter centrifuge utilizes the operating principle grounded on separation via buoyancy.
Generally, denser materials fall at the bottom of the mixture while less dense ones are suspended
above. Settling rate is increased through rotational capabilities of the decanter centrifuge. The
rotation produces a force similar to between 1000 and 4000gs which reduces the material settling
time whereby materials that could settle for 2 hours now takes seconds through the use of
decanter centrifuge. Eventually, this mode forms effective, reliable and faster separation results.

Decanter Centrifuge 3
Horizontal decanter centrifuge
Process characteristics
the process of separation in a decanter centrifuge depends on process features such as
centrifugal force also known as G-force, the rate of sedimentation, factors of separation, the
speed difference between the conveyor and bowl and discharge clarity of the liquid.
Decanter centrifuge utilizes the centrifugal force in separating solids from liquids in the
mixture. This feature relies on the radius of the centrifuge and the angular speed of rotation
(Altieri et al, 2013). The rate of sedimentation process is also an important feature in the decanter
separation process. The following features influence the sedimentation rate: size of particles,
shapes possessed by the particles, density variation of the particles and the existing viscosity
properties between the particles and the liquid. Utilization of flocculating agents can improve

Decanter Centrifuge 4
this characteristic process. The rate of sedimentation to depends on separating factor possessed
by the decanter centrifuge which directly relates to centrifugal force.
The scroll conveyor and the exterior owl depict varying rotation speeds. The existing
difference in speed between the two is responsible for the entire sedimentation in the cylinder
within the decanter centrifuge. High variation of speed generates reduced or limited time of
residence of the settlement of the cake hence the need of making the thickness of the cake to a
maximum minimum aimed at preventing the discharge quality impairment (Altieri, 2010).
Maintaining minimum thickness of the cake also helps in improving the dewatering process of
the cake. It is, therefore, necessary to balance the thickness of the cake and quality through
achieving a maximum differential speed.
The above-discussed characteristics all have effects on the clarity of the liquid output
which solely relies on the volumetric throughout rate whereby a higher rate of flow results in a
poor clarity of the liquid. Differential speed forms another characteristic which influences the
clarity of the liquid output. A better clarity is achieved by a low differential speed which
eventually leads to an improved process of separation. A big role is also played by the G-force
towards influencing the clarity of the liquid discharge (Lee & Pennwalt, 2014). Increased
separation of the solid particles from the liquid is achieved by a higher G-force thereby
eventually resulting in a better liquid clarity.
Design heuristics
This forms methods on experience grounds aimed at serving the goal of reducing the
calculations needs in consideration of sizing of the equipment, performance or parameters of
operation.

Decanter Centrifuge 5
The scale of the process makes one of the most important design heuristics that needs to be
considered in employing decanter centrifuges. Decanter centrifuges should be used in large-scale
separation processes with a goal of maximizing economic value.
Length to diameter ratio is another design heuristic consideration. Ratios of 2, 3 and 4 are
commonly used. Higher solids conveyance capacity and larger volume of suspension are
achieved through decanter centrifuges with similar diameter but longer length thus enhancing
settling out of fine solids (Michelsen & Incentra, 2013). Other design heuristics to be considered
includes beach angle at the conical section, applied intensity of the centrifugal force and
differential speed controlling cake transport.
Control safety aspects of a decanter centrifuge usage
Safety aspects of the decanter centrifuge relate to the following:
Standards and Certification. Conformity to international standards and certification forms the
first safety step ensuring safe installation and equipment operation. BS.EN12547:1999 forms the
standard covering industrial centrifuges.
Control systems. It plays a key role in reducing associated risks essential to the process
equipment. The available risks depend on the centrifuge type being used, i.e., the following
safety aspects apply to the decanter centrifuge:
 Allowing human access under strict safety conditions only
 Operation of product discharge mechanisms
 Bowl or basket integrity

Decanter Centrifuge 6
Reduction of risks follows certain outlined steps (Madsen & Alfa, 2015). First, risks should be
designed out if practical, second, protective measures such as guarding or interlock control must
be adopted. Lastly, in situations where no alternative exists, warning labels should be adopted.
Basket or bowl design and inspection. The bowl should be designed with an aim of preventing
rupture while enhancing continuous operation with fewer fatigue cycles. The rotational speed of
baskets should be controlled since the failure of the basket while rotating at high speed might
destroy the centrifuge and any party close to it. The inspection should focus on
 Loss of material from the bowl
 Cracks presence on the bowl or basket
 Inner coatings damages

Decanter Centrifuge 7
Reference
Altieri, G., 2010. Comparative trials and an empirical model to assess throughput indices in olive
oil extraction by decanter centrifuge. Journal of food engineering, 97(1), pp.46-56.
Altieri, G., Di Renzo, G.C. and Genovese, F., 2013. Horizontal centrifuge with screw conveyor
(decanter): optimization of oil/water levels and differential speed during olive oil extraction.
Journal of food engineering, 119(3), pp.561-572.
Lee, C.Y., Pennwalt Corp, 2014. Centrifuge apparatus. U.S. Patent 3,885,734.
Madsen, B., Alfa Laval Separation AS, 2015. Decanter centrifuge with energy dissipating inlet.
U.S. Patent 5,374,234.
Michelsen, J., Incentra, 2013. Decanter centrifuge. U.S. Patent 6,123,656.
Records, A. and Sutherland, K., 2011. Decanter centrifuge handbook. Elsevier.