Insulator which used to reduce temperature of surface in industries

1. CHEMICAL ENGINEERING
L.D. COLLEGE OF ENGINEERING
PROCESS HEAT TRANSFER
o Kansagara Meet
o Enrolment No.- 130280105021

2. INSULATION

3.  Definition
 Introduction
 Properties
 Necessary
 Examples

4. The material having low thermal conductivity(k) are
called as heat insulator.
 It is used for minimise heat flow. For example: Glass, Wool
 Process equipment such as reaction vessels, reboiler, distillation
column, evaporator, etc. or a steam pipe will lose heat to the
atmosphere by convection, conduction and radiation. In such cases,
the conservation of heat that is usually of steam and coal is an
economic necessity and therefore some form of logging should be
applied to the hot surface. In furnaces, the surface temperature is
reduced substantially by making use of a series of insulating bricks
that are poor conductors oh heat

5.  Properties
o It should have a low thermal conductivity.
o It should withstand working temperature range.
o It should have a sufficient durability and mechanical strength.
o This includes resistance to moisture and the chemical environment.
o It should be easy to apply, non-toxic, readily available, durable and
inexpensive.
o It has low basic material cost, installation cost and maintenance cost.
o It should not create a fire hazard.

6.  Necessary
o To prevent an excessive flow of costly heat to the surroundings from
process units and pipelines in which heat is generated, stored, or
conveyed at temperatures above the surrounding temperature.
o To prevent an excessive flow of heat from the outside to materials
which must be kept at temperature below that of the surroundings.
o To provide for protection of personnel from skin damage through
contact with very hot and very cold surface.
o To provide comfortable working environment. The working
environment in the vicinity of process units and pipelines carrying hot
or cold stream can become uncomfortable and unacceptable, if
insulation is not provided.

7. Examples
 Cork (k= 0.025 W/m.K) – common in
refrigeration
 Asbestos (k= 0.025 W/m.K) – lagging
steam pipes
 Glass wool (k= 0.025 W/m.K) – lagging
steam pipes
 85 percent magnesia (k= 0.025 W/m.K) –
lagging steam pipes