The Challenge:

Developing a PC-Based real time control and monitoring system for temperature of different zones and air level in the furnace with controlling of a motor, and also monitoring of various types of the gas.

The Solution:

Using Field Point Network Module, Field Point Thermocouple Input Module, Field Point Analog (4-20mA) Output Module, Field Point Relay Output modules, Personal Computer & Lab View.

Introduction

The PC Based Furnace controller consists of National Instruments’ Field Point based Hardware to connect the Thermocouple, Relay outputs for control. The Thermocouple input provides the PC with the temperature input and Relay contacts are used to turn on the heater circuit. The Motor is controlled through 4-20 mA module depending on the current being applied through the software i.e. the RPM of the motor is controlled.

The software for controlling the temperature of the 5 different zones is developed using National Instrument’s graphical programming language Lab VIEW. The control is achieved based on the principal of ON/OFF control using software, which ensures optimum power delivery to the heating element. The software has got the facility to run the furnace with any number of and any combination of Ramp and Soak cycle i.e. since we are having 5 different zones we can set ramp and zone cycle for each zone separately, also It has also got the facility to auto turn off the power supply to the heating element and to the motor at the end of heating process. The operator can observe the temperature trending on a graph. We have also integrated 2 anemometers & gas analyzers to acquire the data like velocity and percentages of various gases respectively. These are integrated through the serial ports and are acquired using the software.

Software

The software is developed in such a way that it provides complete security and flexible to include new zones as and when required.

In order to use the software the user has to enter a valid password to gain access to the software. After entering the software the user has to select to select a suitable test that they want to perform.

Some of the tests that perform are as follows cold experiment, new experiment. In the cold experiment the furnace won’t be turned on, i.e. the experiment is done when the furnace is cold, the motor is run at different RPM’s for sucking the air in the furnace, this will be done through the software and the motor is controlled through the field point 4-20 mA Module, and the velocity at different points is captured through the serial ports, this is done through the software and it will be plotted on the graph with velocity vs. motor current .The duration between each points acquired is user defined

In New experiment option the user enters various parameters along with the temperature settings for each zone and also enters the motor speed.

12 different graphs on the screen where he can see the temperature of 5 different zones both inner and outer temperatures. The user is provided the options of zooming each graph and merging two different graphs to compare the graphs.

There is also an option for the user to see various gas contents in the air of the furnace by clicking on the button gas.

All the data is saved in a file so that the data can be used for post analysis and for report generation.

In the main menu the user can select option-logged data. When the users enter he has to enter the files name that he wants to see and analysis.

Result

The software was able to successfully control and monitor the 5-zone drop tube furnace. Unlike conventional system, this system made it possible to obtain feedback on the operation in real time and to perform analysis on the stored data.