How to measure flash steam flow rate 1

[Jimmyvanskip]

We have a direct steam oven which uses "once through" steam to cook chicken fillets, the condensate goes direct to drain.
There is a very significant flash steam plume emitting from the oven flue, from which we would like to recover heat (using a heat pipe heat exchanger) to pre-heat wash down water.
Problem is to size the heat exchanger, we need to know the mass flow rate of the flash steam.
I have considered doing a mass balance of the oven in order to calculate the flash steam, but there are too many unknown variables, this method would be inaccurate.
Does anyone know of another methodology we could use?

 

[Latexman]

A mass balance is probably the best way. Is this the only user of the boiler's steam? If so, the boiler feed water rate = steam output. If not, it's going to be more complicated. A sketch, drawing, or PFD may help.

Also, if you add a heat exchanger, that will put backpressure on the oven. Was it designed for pressure? If it was, the chicken will cook a little faster!

Good luck,
Latexman

Technically, the glass is always full - 1/2 air and 1/2 water.

 

[MisterE2]

So really quick, buy some copper tubing from home depot, attach it to the flue of the oven, wrap it around something cold and have it drain down to a gallon jug, get a scale and weight the condensate after a set period of time, after the tubing's flow rate reaches steady state(should be a startup period). Also wouldn't it be easier to just run the incoming water through a copper plate on top of the oven?

 

[TD2K]

If you know the steam consumption and the pressure, I'd go with Latexman's method.

If you don't have any idea, I'd likely measure the condensate going to sewer and back calculate the amount of flash steam. If the amount of condensate flow and steam pressure is varying all the time, MisterE's method might be one you want to look at.

 

[BronYrAur]

What do you mean by "direct steam"? Does that mean the steam comes in direct contact with the chicken? It would seem to me that recovering the condensate would yield far more energy savings than capturing flash steam. I'm guessing that this is not possible???

To answer your question, percent flash depends on the initial and final pressures. See attached chart from the Spirax Sarco book.

 

[FredRosse]

Heat Pipe would not be a good choice, suggest you should just run washdown water thru a heat exchanger, condensing steam on outside, water inside tubes.

Typical energy balance methods, measure steam input flowrate, calculate heat losses from oven to ambient, calculate heat losses to product, then calculate available heat in the exhaust steam.

I do not understand the "flash steam" element here?