We developed a simple, reproducible controller for our

1. Automated Kiln Control System
Goal: Reduce the workload and
produce more consistent, high
quality filters

2. The overall piping system
Components: 50kg tank of liquefied natural gas, ball valves to isolate tanks, hot water bath for
converting LNG to gas, high pressure gauge, alarm system to indicate when tank needs to be
changed, manual high pressure valve, electronic valve system, low pressure gauges.

3. Tank and hot water bath

4. Inside of hot water bath
Components: coil of stainless steel pipe and 3000 watt water heater
(below the coil), thermocouple for electronic control of bath water (not
shown).

5. Water bath is kept at about 65 C. Gas temperature at outlet of water bath
Temperature is electronically controlled. is about 45 C – plenty hot enough.

6. Homemade alarm system to indicate when gas tank
needs to be changed.

7. Manual high pressure regulator and electronic valve.
The manual regulator is set so the maximum outlet pressure is 0.05 Mpa –
which is the maximum pressure the system needs for firing the kiln to cone
010. The electronic valve then just needs to control the pressure from
approximately 0.005 at the start of the burn to 0.05 Mpa at the end.
A ball valve is kept slightly open so that even if the electron valve is completely
closed the burners will continue to have gas.

8. Low pressure gauge indicates pressure going to the
venturi burners.

9. The brains of the system is a PYX Series Fuzzy Logic
Controller while the heart of the system is a digital
electronic valve system
Using information from a thermocouple inside the kiln, the controller and electronic valve work in tandem to control the temperature inside of the kiln.
As can be seen the ideal temperature (in green) at this point in the burn was 809 C and the actual temperature read by the the thermocouple in the kiln
was 808 C. The system can keep the temperature within 2 C of the program temperature profile. The valve was open 27.1% of full open (at bottom).
Other information: 47.4 % is the room humidity and the room temperature was 34.7 C. Temperature on the door of the kiln was 825 C. We use this for
comparison to the primary temperature measure near the top, center of the kiln.

10. One of our 6 venturi burners
The valves and baffles are always kept fully open.

11. View of the venturi in use.
At 810 C the flame is very blue as it goes into the kiln.

12. When cones begin to fall
The operator watches for the 010 cone to fall. She then tells the controller the maximum
temperature has been reached and controller holds the temperature for a 1 hour soak and
then the operator turns off the system by turning off the gas and controller.
In Picture: from front to back: Cones 013, 012, 011, 010, 09