Case Study: A New Design for a Water-Cooled Furnace Brings to Life the Concept of “Conservative Innovation”

When a CECON consultant specializing in chemical and process engineering presented his idea for a new design for a water-cooled furnace to the expert designers he worked with they said one word: IMPOSSIBLE.  But employing his concept of “conservative innovation design,” he persisted and built a furnace that not only operated successfully, it became far more practical to maintain and repair than the traditional design.

 Over the course of five years, I have built and operated a total of seven rotary induction water cooled furnaces—giant furnaces capable of processing hundreds of tons of ore per hour—in two different factories.  

 When No. 6 was running, my electrician, who I had been working with since No. 1, came into my office and declared: “We must get rid of this water cooling nuisance. You must make an air-cooled coil!” He had a point. Water leakages and sometimes blocked water passages, created safety risks, demanded problematic repairs and consequently caused lengthy down time of the furnaces.

 I immediately responded: “Our furnaces are not the first in the world. If this were possible, the Chinese experts who supplied the equipment would have done it long ago. Forget about it! We have enough on our hands.”

 He was disappointed, but he understood my point.

 But that evening I found myself considering the possibilities. I started writing notes and making sketches. I assumed that if this was really impossible, my engineering calculations would run into a dead end, or some expert will convince me to let go of the idea.

 My criteria were that I need the new design to be suitable for conversion of the existing furnaces without major modifications including the need to modify the power supply and control mode. Getting rid of the cooling water nuisance was tempting but not enough to justify a major design revolution, especially considering that we already 6 furnaces running.

It took some calculations and consulting with experts of heat exchange and electrical bus bar designers to come up with an alternative design of an air-cooled coil that would have the same Ohmic resistance as the original despite of the higher working temperature.The copper weight was 2.5 times the original. More expensive but still not prohibitive. I now knew that I had a suitable design.

We knew the maximum current in the coils so we could calculate the power needed to overcome the Ohmic resistance of the coils. We then measured the cooling water flow rate and temperature difference and thus verified that we know the heat load to be removed by the surrounding air. With this in hand, and using some heat exchange coefficients found in literature, we could calculate the surface temperature of any suggested copper profile to be used for the construction of the new AIR-COOLED INDUCTION COIL. 

Knowing the service temperature of the Copper we could now find the new specific resistance of the Copper and calculate the required cross section in order that the total coil resistance will be the same as the original. The copper weight was 2.5 times the original. More expensive but still not prohibitive. I now compared my results to engineering tables which I received from an electrical engineer showing service conditions and loads for bare copper cables and bus bars used in electrical panels. The comparison was encouraging. I now knew that I had a suitable design.

What is Conservative Innovative Design?

At this stage I would like to spell out the main characteristics of what I call Conservative Innovative design. The innovative part of this is easy to understand. Once you face a problem, which the existing technology cannot solve satisfactorily, keep your mind open to innovative ideas even if, at first glance they look unsuitable. Do not be afraid of innovation. Have the guts to try new things.

How do you apply innovation in a conservative way? We must remember that we are within an operating facility where a lot of money was invested and time is highly valued. We must respect the “old” technology even if we are critical of it, as this is actually what we have and what is paying the bills and providing pay checks.

We must not be too adventurous or too arrogant. We must consult with many experts, listen to many opinions, especially those which reject our ideas and predict failure. We must be critical to prove to ourselves that the rejecting opinions are wrong–or maybe they are right or partially right and maybe we can learn something and improve. This requires patience and hesitation. A thinking process that does not go through the hesitation stage had simply not been examined deeply enough. Never assume that things will go right. Prove it to yourself!