Liquid-solid particle, separators Cyclone

Lines in vacuum service, 135—141 Line symbols, 17, 23 Numbering, 23 Lined centrifugal pumps, 171 Liquid-solid particle, separators, 228 Baffle type specifications, 248 Baffle type, 247, 248 Centrifugal, 256, 259-261 Chcvron-vanc, 248, 235 Comparison chart, 230 Cyclone, 259 Specification form, 268 Vane, 259 Wire mesh, 246 York-vane, 248 Low pressure storage... 

The palm oil exiting the low-pressure screw press has approximately 66% oil, 24% moisture, and 10% solids (18). The solid particles are typically separated from the oil using the traditional method of pumping the oil into a tank with approximately 2 hours of residence time to allow the heavier solid particles to settle and be continuously dredged from the base of the tank. After gravity separation, the oil is then pumped through a liquid cyclone to remove residual solids. Solid particles separated from the clean oil stream are saturated with oil and recycled back into the process. After the palm oil is cleaned of solid particles, it is heated and pumped through a vacuum oil-dryer to remove moisture. 

Spray Dryers A spray diyer consists of a large cyhndrical and usu ly vertical chamber into which material to be dried is sprayed in the form of small droplets and into which is fed a large volume of hot gas sufficient to supply the heat necessary to complete evaporation of the liquid. Heat transfer and mass transfer are accomphshed by direct contact of the hot gas with the dispersed droplets. After completion of diying, the cooled gas and solids are separated. This may be accomplished partially at the bottom of the diying chamber by classification and separation of the coarse dried particles. Fine particles are separated from the gas in external cyclones or bag collectors. When only the coarse-particle fraction is desired for fini ed product, fines may be recovered in wet scrubbers the scrubber liquid is concentrated and returned as feed to the diyer. Horizontal spray chambers are manufactured with a longitudinal screw conveyor in the bottom of the diying chamber for continuous removal of settled coarse particles. 

Centrifugal force can also be used to separate solid particles from fluids by inducing the fluid to undergo a rotating or spiraling flow pattern in a stationary vessel (e.g., a cyclone) that has no moving parts. Cyclones are widely used to remove small particles from gas streams ( aerocyclones ) and suspended solids from liquid streams ( hydrocyclones ). 

In this section, the general design of the hydrocyclone and its application in the grading of solid particles, or their separation from a liquid, is considered and then the special features required in hydrocyclones required for the separation of immiscible liquids will be addressed. The use of cyclones for separating suspended particles from gases is discussed in Section 1.6.2. 

Liquid cyclones can be used for the classification of solid particles over a size range from 5 to 100 /rm. Commercial units are available in a wide range of materials of construction and sizes from as small as 10 mm to up to 30 m diameter. The separating efficiency of liquid cyclones depends on the particle size and density, and the density and viscosity of the liquid medium. 

Use a cyclone separator to remove, from a gas, droplets or solid particles of diameter down to 10 microns (0.01 mm). Use a hydroclone separator to remove, from a liquid, insoluble liquid droplets or solid particles of diameter down to 5 microns (0.005 mm). However, small amounts of entrained liquid droplets are commonly removed from gases by vertical knock-out drums equipped with mesh pads to help coalesce the smallest droplets. 

To separate solids having about the same density but with a range of partide size, separate based on cut diameter and use air or liquid classifiers such as cyclones, hydrocyclones or spiral classifiers Particle size 25-2000 [xm feed solids concentration 5 to 40%. Cut diameter is the particle diameter that has equal chance to report to either the overflow or the underflow streams. 

Hydrocyclone Hydraulic device for separating suspended solid particles from liquids by centrifugal action. Cyclone action splits the inlet flow, a small part of which exits via the lower cone, the remainder overflowing the top of the cylindrical section. Particles are separated according to their densities so that the denser particles exit via the cone underflow and less dense particles exit with the overflow. 

The liquid-solid hydrocyclone, shown schematically in Fig. 3.4-3, functions like a gas-solid cyclone. The hydrocyclone is also known as a hydroclone. The primary independent parameters that influence the ability of a hydrocyclone to make a separation are size and geometry of the hydrocyclone, particle size and geometry, solids loading, inlet velocity, split between overflow and underflow, density differential, and liquid viscosity. A reasonable estimate of Ae particle cut diameter (50% in underflow and overflow) d o) is given by the following dimensionless relationship, developed initially by Bradley ... 

When the solid particles enter near the cylindrical wall they can be dispersed radially inwards because of the intensive turbulent mixing in the feed sections. There is, however, very little information about the behaviour of the liquid in the cylindrical section this portion of the cyclone is usually treated as a preliminary separating zone and the main separations are thought to be performed in the conical section. 

Figure 3.4.22 Cyclone for the separation of solid particles from gases or liquids.

Filtration Centrifugation Sedimentation Cyclone separator Electrostatic precipitator Demister Magnetic separator Screening Liquid-solid Liquid-solid or liquid-liquid Liquid-solid Gas-solid or Gas-liquid Gas-solid Gas-solid or gas-liquid Solid-solid Solid-liquid Solid-solid Pressure reduction Centrifugal force Gravity Flow Electric field Pressure reduction Magnetic field Size of particles... 

---