Training programe

EXCHANGERS

Heat exchangers are similar to pumps and vessels. The control of heat within any facility is an important part of plant operation. The heat exchanger is used to maintain a heat balance through the addition or removal of heat by exchange with outside sources or between streams of two different operating temperatures.

Coolers cool process streams by transferring heat to cooling water, atmosphere and other media.

Exchanger exchanges heat from a hot to a cold process stream.

Reboiler boils process liquid in tower bottoms usually steam, hot oil, or a hot process steam as the heating medium.

Heater heats a process stream by condensing steam.

Condenser condenses vapor by transferring heat to cooling water, atmospheric air or other media.

Chiller cools a process stream to very low temperatures by evaporating a refrigerant.

Common heat exchangers used in processing facilities are;-

a) Shell and tube exchangers

b) Plate Exchangers

c) Spiral Heat Exchangers

d) Double pipe exchangers

e) Air cooler exchangers

FURNACES

Furnaces, also refered to as heaters, are one of the main pieces of equipment in a process complex. A furnace may raise the temperature of a gas or hydrocarbon liquid to meet specific processing needs or, in the case of pyrolysis and reformer furnaces, cause a chemical or physical change to the medium.

Primary Parts of a Furnace

The radiant section houses rows od horizontal or vertical tubes that carry the product to be heated.

Burners are primarily fired by oil or gas and located in the radiant section.

The convection section located above or downstream from the radiant section houses rows of horizontal tubes that are heated by the hot flue gases.

The stack is usually located above the convection section and carries the flue gases to the atmosphere.

Insulation lines the walled surfaces of the radiant and convection surfaces.

Fuel is fed to the burners located along the furnace floor. It is then ignited by a pilot gas line located in the burner. The combustion air flow is regulated by adjustment of the air registers. For proper operation within a furnace a natural draft must be maintained. As the temperature rises, the hot flue gas rises out of the stack and begins to exert a negative pressure within the radiant and convection sections.

Types of furnaces

A) Box type houses rows of horizontal or vertical tubes in the radiant section

B) Circular type houses tubes mounted vertically or helically in the radiant section.

C) Pyrolysis furnace product tubes are placed in the center of the radiant section because of a relatively short residence time, high heat transfer rate and need for even temperature distribution in the tubes.

D) Reformer furnace, the preheated process fluid flows through catalyst filled tubes, which are usually located in the center of the radiant section.