[Gasification] Oxygen sensors for gasifier engines

[doug.williams]

Hi Tom, and Colleagues,

Sorry for the slow response on this, but just catching up on my mail.

> In the feedback loop one needs a gas valve that can be controlled from
> this signal.  We have built one, but does anyone know of a simple
> inexpensive available valve for this?

It's been our experience that these types of motorised valves are not cheap 
(UKP500) or reliable in the size we need them for lambda controlling..We 
actually used a valve from Germany for the engine in Belfast, but these 
assemblies are not made for the job, and in our case, had a motor life of 
500 hours. The engine clocked up 549 hours before it burnt out! I also know 
that other users of these valves have had burnout and corrosion problems. 
Possibly you need to consider other types of control (pneumatic, vacuum) if 
you cannot get a valve designed for continuous operation.

You may find it easier to set the main gas/air mix with a conventional 
valve, and then use the controller to do the tweeking. One thing for sure, 
lambda sensors show just how much fluctuation of the gas quality exists 
across the operational  parameters, especially in batch feeding, but for 
smaller installations are a questionable addition of costs. If however you 
are experiencing other issues that affect  gas stability, the existing need 
for the lambda sensoring, should be giving more than a signal about gas/air 
ratio.

For the others interested in this subject, it should be noted that while DIY 
projects can draw from an amazing supply of junk to solve a problem, 
commercially development needs commercially supplied componentry. Cheap is 
good, but not to a customer with a burnt out valve motor in some distant 
place.
Hope this helps.
Doug Williams,
Fluidyne Gasification.