High Temperature Reactor Heating System 2

[NRGENG]

I am involved in the design of a tubular reactor heating system. The reactor shell is filled with pellets through which reaction gases flow. The inner tubes contain hot gases which provide thermal energy to the endothermic reaction which takes place in the shell. I need to provide additional thermal energy to the shell contents.

I thought that a thermal fluid system ( Dowtherm or Therminol heated with an electric heater) would be a good fit, but found the upper temperature range of operation to be between 600 and 800 deg F. I need an operating temperature of 1000 deg C (1832 deg F).

My preferred energy source is electricity but I could possibly use something else if required. The area has a hazardous electrical classification. I would appreciate any suggestions. Thank you.

 

[moltenmetal]

So: you're obviously buiding a steam reformer, or something very like it.

What are you going to make the tubes out of to withstand pressurized service at 1000 C?

Forget about electrical area classification: the unit will have surfaces well above the autoignition temperature of anything that will burn. It will be equivalent to a piece of fired equipment. Review NFPA 497: you can't use area classification as a means of protection against fire in those circumstances. You need to mitigate the risk of fire in other ways, or not do the project.

Assuming you can solve the materials problem, you have really two choices: flue gas, or radiant electric heating. Commercial reformers are heated with burners.

 

[MJCronin]

Molten:


These people offer high temperature alloy tubes and other components for the DRI industry:

http://www.schmidt-clemens.com/company

http://www.schmidt-clemens.com/fileadmin/web_images/Broschueren/Petrochemie/DR_Catalogue_Rev4.pdf

According to thier sales info, these tube have a max operating temperature in the range of 1000 degrees C

 

[moltenmetal]

Thanks MJCronin: I'm aware of the cast materials that are used in commercial reformers, though the OP may not have been. I doubt that the smallest spuncast "tube" in HK40 etc. that can be made is small enough for what the OP was originally considering in their design, but I may be wrong. All the conventional tube materials turn into pumpkins at 1650 F or less for code service unless I'm missing something.

 

[moltenmetal]

http://www.nipera.org/~/Media/Files...sNickelAlloysRefiningPetrochemical_10071_.pdf

The authors of this paper make mention of the use of wrought materials such as 800HT and 253MA (i.e. materials you can make real "tubes" out of) at temperatures above 1650 F- indeed to temperatures in the 1850-1900 F (1010-1038 C) range. Unfortunately they make no mention how it is (safely) accomplished, these temperatures being well above the maximum temperatures at which there are safe allowable stress values listed in codes such as B31.3 and ASME VIII. Repeated questions to Eng-Tips over the years have not yielded an answer to this question either.