Fired Heater Design Software

Fired Heater Design and Simulation. Are performed using Microsoft Excel Programming software and the same fired heater data are used in HTRI simulation software.

Table of Contents • • • • • • • 1. Function The primary function of a fired heater is to supply all heat required by the process in one form or another.

A fired heater utilizes gaseous or liquid fuels often produced as a by-product. The normal process function is raising the process stream to its required temperature for distillation, catalytic reaction, etc.

Sizes of heater vary considerably, dependent upon the type of duty and throughput. 1.2 Types There are two general basic designs or types of fired heaters: • Box type • Vertical type. Either of which may be forced or natural draft. BoxType Heaters (See below figures 2 and 3.) A box type heater is considered to be any heater in which the tubes are horizontal. In this type of heater it is possible to have locations or zones of different heat densities. The zone of highest heat density is the 'radiant section'. The tubes in this section are called 'radiant tubes'.

The heat pickup in the radiant tubes is mainly by direct radiation from the heating flame. In some heater designs shield tubes are used between radiant and convection section.

The zone of lower heat density is the 'convection section'. The tubes in this section are called 'convection tubes'.

This heat pickup in the convection section is obtained from the combustion gases primarily by convection. Box type heaters may be up-fired or down-fired with gas or oil fired burners located in the end or sidewalls, floor, roof or any combination thereof. Up-fired Heaters In the horizontal up-fired heater, products of combination in the radiation chamber pass upward through banks of roof tubes and a fire brick diffuser into a plenum or collecting chamber.

From the plenum chamber flue gases are passed through an overhead convection section and then to an overhead stack. Such heaters may be fired vertically upward by panels, mounted in the heater floor or hearth, the heater floor being elevated to provide headroom beneath. Alternatively, these heaters may also be fired horizontally by burners mounted in the heater-end walls, in which case the heater floor is only elevated above grade to provide air cooling convection to the heater foundations. This type of heater may contain single or multiple radiation chambers discharging flue gases to a common convection section and stack. Down-fired Heaters In the down-fired heater, combustion gases generated in the radiant chamber pass downwards through a refractory checker hearth into a collecting chamber beneath. From there the flue gases flow upward through the convection section and then out to the stack.

Medal of honor allied assault torrent. The down-fired heaters are basically intended to fire on heavy residual fuels, where the flue gases are corrosive and may clog flue gas passages of conventional heaters. Convection sections are thus protected by removal of combustion solids and are usually provided with inspection ports, soot blowing devices and tube facilities to keep the coils clean. Burners in down-fired heaters are always mounted in the heater-end walls. Vertical Heaters (See below figures 4,5 and 6) Vertical heaters are either cylindrical or rectangular.