2 replies to this topic

[eddie2314]

Folks, I've been scratching my head about this one and am hoping someone can enlighten me. I am involved in the design of an item of equipment for use on the international market and am struggling to define what code the basic design should adhere to.

The item is an indirect fired rotary kiln. It can be used in many industries. It consists of a combustion chamber fired by burners. The chamber is vented to atmosphere. Inside the chamber sits a rotating tube filled with solids. The solids are dried and the resultant vapor goes out a vent. However the vapor is under backpressure (approx 7psig, or near 0.5 barg).

I've been looking at ASME code and can see that because the MAWP is < 15psig i don't need to adhere to section VIII. I then looked at section IV for low pressure and it doesn't seem to fall under that either. In my interpretation the unit is not strictly a steam boiler (although the majority of vapour will be steam and minor quantities of hazardous compounds). So my question is, what code, if any, do i need to apply?

Also, i was considering two potential pressure control philosophies.

1. a simple cracked and locked manual butterfly valve to create a backpressure. Set and forget during commissioning, with a high pressure alarm to interlock the system into shutdown should high pressure arise.

2. a PCV adjusting to a set pressure (looks expensive given the temperatures and vent diameter - 700degC and 6inch). Again, a high pressure alarm would shut the system down.

I'm not fully sure if a pressure relief device is required (given the low pressures, the uncertainty over code requirements, the inclusion of a high pressure interlock already etc). Thoughts welcome!

Thanks

[fallah]

eddie.

Please upload a simple sketch of the system.

[kkala]

Yes, a sketch would clarify a lot, as previous post suggests. Some further clarifications along with it would be useful, in my opinion.
1. Requested code concerns only the "rotating tube filled with solid" ? What about enclosing "combustion chamber"?
Opinion on applicability of API Std 560 concerning fired heaters is welcomed, http://www.techstree...duct_id=1516745 '> http://www.techstree...duct_id=1516745 . I am not familiar with codes (Mecanical, not Process Dept are responsible for them here).
2. Is "steam" back pressure of 7 psig necessary for the satisfactory operation of drying? What if it is lower?