Principle, Construction, Working, Uses, Merits and Demerits of Horizontal Tube Evaporator

Horizontal Tube Evaporator

Principle

Steam is circulated horizontally through tubes in this type of evaporator. When the feed is heated, the feed evaporates outside the tubes and discharges concentrated vapours from the outlet at the bottom. By circulating the product over the heating coil, the vapour is removed from the top of the chamber and the product is circulated naturally. If the surrounding environment is saturated with vapour, the process might be slowed.

Construction

There are two general types of horizontal tube evaporators: rectangular or circular, constructed of stainless steel, aluminium, nickel, carbon, spellerized iron tubing, lead covered copper, and special bronze. Between two steam chests, tubes are attached to an arc by means of arc fasteners. Tube sheets are countersunk into four-hole packing plates, which press conical gaskets around tube ends into countersunk holes. Providing a secure seal, the tube sheets can be replaced easily. A cylindrical chamber with an exterior diameter of 1 to 3 meters and a height of 2.5 to 4.5 meters has horizontal tubes of 2 to 3 cm diameter running across the bottom. The tubes of a vertical tube evaporator are arranged vertically in calendria, as shown in Figure. An evaporator calendria includes many smaller diameter tubes in which the liquid is concentrated as it rises or falls.

Working

A horizontal tube evaporator warms the liquid surrounding the tube in the bottom of the evaporator body with steam fed through horizontal tubes from a steam chest. During the condensed gas process, the steam follows a definite path to the opposite steam chest, where it is withdrawn from the opposite steam chest. It is determined by the distribution, size, and shape of the heating surface in the liquid compartment that determines the velocity and path of circulation of the liquid.

Uses

• In order to make cascara extract, it is used.
• Caustic soda is made with it.
• Sodium chloride is used to make salts.

Merits

• The effect can be enhanced by joining a number of units.
• The heating surfaces are inexpensive per unit.
• The design is extremely simple.
• Surfaces of heating can be easily renewed.
• Low maintenance construction with sectional construction.
• Easy to use.
• Liquor carrying capacity of the body.
• The headspace requirement is low.
• Shipment requires a small amount of cargo space.

Demerits

• In comparison to steam jacketed kettles, cleaning and maintenance are more difficult.
• During operation, the inside pressure of the evaporator increases, which lowers the effective temperature gradients and adversely affects heat-sensitive materials.
• The use of this method is limited to when natural circulation is able to achieve rigorous boiling.
• Liquids with high viscosity should not be used.
• Due to its location outside of the tubular heating surface, boiling liquid is difficult to clean mechanically.
• Using it to scale or salt liquids is not a good idea.

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