Mica Band Heaters

I'd buy something off-the-shelf, if I were you. Then you'd know it would work.
The resistance of ni-chrome wire is between 1.0 × 10⁻⁶ to 1.5 × 10⁻⁶ Ωm.
Send pictures if you can make it work.

I give this a GA. It seems that there are a lot of people out there that don"t understand the difference between heat and temperature. This is basic thermodynamics which everyone with a minimum education in engineering or science should know.

Thank You! I have to have this discussion too often with people that I feel should fully understand this. The other one that bugs me is the difference between flow and pressure. I have guys tell me they fixed a solenoid valve that can't open against the pressure by partly closing the upstrem manual valve to "reduce the pressure".

Nurse, another round! -- JHF

I think I hear the Voice of Doom.

Coolyaar + 400V + homemade = DOOM!

(Was going to say death, but knowing our OP it would be some other poor schmuck).

Although the 9" value given was the diameter, not the length, of the proposed heater, the rest of your answer deserves a GA.

Since argon is inert, if this tube contains only argon, it would be much more efficient to have the heater as a spiral coil inside the tube. Again, since the argon is inert, it can't be the catalyst, but only a source of heat to increase a reaction rate without contaminating the reactants. In my very limited experience, an 8" diameter pipe would indicate a huge amount of argon, unless the flow rate is extremely low. In that case, it would make sense to heat the argon in a coil of much smaller diameter tubing and expand the diameter just prior to the reaction vessel.

In in-pipe immersion heater would be a better design, unless something prevents it.

Yes,and it would be much better if its twisted honeycomb in-pipe heater

The more I think about it, the more questions are coming up.

Is it a quartz tube? Then it can have linear heaters arranged around it, then reflective and glassfibre insulation. I do not believe, the reaction section can also be the heating section. Too many variables.

How precise and even have to be the catalist temperature be, at what flow?

Do you have the money and the years to develop, if it is a precision thing?

Buy the darn thing, if you can specify it at all, and go on producing your thing.

In order to calculate the approximate heating power required, and from it determine the details of the heating coil, one needs to know, among other things:

• The inlet temperature of the argon gas
• The inlet pressure of the argon gas
• The flowrate of the argon gas
• The length of the pipe
• The size of the assembly downstream
• The level of insulation of the entire assembly, including whatever is downstream
• The mass and composition of the materials downstream

Also of value to the design would be:

• The position of the temperature sensor from which the temperature measurement is to be made, relative to the heater coil
• The mode of operation of the control circuit - is it on/off? PID three-term? Something else?
• The width of the tolerance band - 200degC +/- what?

Could the argon be raised to the correct temperature somewhere else and stored at that temperature, and then introduced to the catalytic process down this particular pipe, thereby avoiding the need to design such a thing?

Why is the pipe so large? Is the argon coming from cylinders, or somewhere else?

Argon has very little chemistry. Can the argon be introduced just once, and then maintained at 200degC inside the whatever-it-is-downstream while the reaction materials are introduced and the products discharged?

Can whatever-it-is-downstream be converted to some sort of continuous process?

When you have done all the calculations, multiply your power output by 2 and then control the heater by a temperature controller with a three phase thyristor circuit triggering at zero crossover and a sensor reading the downstream gas temperature. The power feed set-up you describe will not deliver a controlled temperature.

We purchase our band heaters from www.imscompany.com. They are cost effective and reliable. This method of heating gas however, is not very efficient. I suggest you install gas heaters inside the pipe. That way you will avoid wasting power required to heat the pipe and the gas external to the pipe.

Lots of good data here, you need to do some calculations on what it is you need.

For what it is worth, this sounds to me like you are going to need two heaters. One to heat and maintain temperature in your reaction vessel and another one to preheat the argon as it flows into the reaction vessel.

The food industry uses such pre-heaters for modified atmosphere packaging systems. I have used these on horizontal flow wrappers in the cheese industry. The gas (a mixture of CO2 and Nitrogen) the gas flow was heated before being injected into the package.

Here is a link to a heater...

Why don't you buy a refurbished system, open it and study what instruments and equipment they are using?

This will make you have complete knowledge of the system. Yagi electricals is one of the websites which you can use to make the purchase of used electrical supplies at cheap rates.