Insulator
- 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