[Stoves] continuous flow steam injector

[Kevin Chisholm]

Dear CC

Safety valves are necessary when there is a safety hazard. Is there 
actually a safety hazard present?

This is a very complicated question to answer by calculations, but very 
simple to answer in practise... do one destructive test and note the 
nature of the failure.

The danger with steam comes from the "rate of release of stored energy." 
If the total energy stored in the superheated steam is adequately small, 
or if the rate of release is adequately low, then the re is no safety 
hazard.

Small bore tubing, such as would be used for the "boiler," is able to 
withstand very high pressures at low temperatures. Then, if there was a 
"perfect blockage", overheating of the tube would tend to cause 
stretching of the tube, increasing its volume, and tending to reduce the 
internal pressure. Increased heating would not be able to attain 
pressures as high as could be attained in the original boiler because of 
the increased volume that the same steam would have to pressurize. 
Failure would be possible, but with the "stretched walls" and the high 
local temperature of the tube wall, the failure pressure would be very 
much lower than the original system.

Consider a small Childrens balloon... it is very difficult to inflate 
initially, but when the "initial bulge" is made, it is much easier to 
continue with the inflation.

In view of the importance of cost and simplicity for the intended 
application, a reliable dedicated safety valve may increase costs to an 
excessive level. Perhaps the simplest approach would be to design the 
"boiler" to fail in a safe manner.

"Design Specific" testing could cheaply, simply, and quickly determine 
if there was a safety hazard, or if the "boiler" failed in a safe manner.

Best wishes,

Kevin

Crispin Pemberton-Pigott wrote:
> Dear Craig
>
> Please be careful about sealing the inlet.  You must have a safety valve in
> there somewhere.   The line in is the present safety system because it can
> blow back through it.  
> Regards
> Cautious Crispin
>
>
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