Browse Prior Art Database

Setting and Controlling the Temperature Profile in a Tubular Furnace

IP.com Disclosure Number: IPCOM000083024D
Original Publication Date: 1975-Mar-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Phipps, PB: AUTHOR [+2]

Abstract

Setting and control of a temperature profile is difficult, because heat applied at one point affects the temperature at all points in the furnace. A model of the heat transfer in the furnace is used to calculate the heat inputs at all points required to achieve and maintain a desired profile.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 2

Setting and Controlling the Temperature Profile in a Tubular Furnace

Setting and control of a temperature profile is difficult, because heat applied at one point affects the temperature at all points in the furnace. A model of the heat transfer in the furnace is used to calculate the heat inputs at all points required to achieve and maintain a desired profile.

Many chemical processes require that different parts of an apparatus be maintained at different temperatures. Examples can be found in crystal growth, doping, and stoichiometry control. These processes are often carried out in a furnace such as that represented in Fig. 1. This consists of a tube wound with a heating wire which is tapped at intervals, to permit selected quantities of power Qi to be introduced in each of the N zones. The temperature Ti can be measured in each zone. A representative desired profile T is shown in Fig. 2.

The difficulty in achieving this profile is that heat applied at one point affects the temperature at all points in the furnace. It is not clear whether a particular temperature profile is attainable, or if it is possible, what voltages to apply to each zone. Furthermore, even if controllers regulate each zone without electrical interaction, they will interact profoundly due to heat transfer.

This method provides both a means of setting the temperature profile without trial and error and a superior means of controlling the profile without the use of multiple controllers.

The essential elements of this meth...