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A
lot of work and study has taken place since the last meeting when Rod brought
the Lamont boiler to the meeting. The
top head design of the drum has been changed three times with helpful input from
him and others. Each design
requires re-analysis and new calculations on stresses/strengths/new seal choices
and anyone that has ever built a prototype can understand the ordeal of
finalizing the design. Rod
has made the final “inspection head” design for the drum top, bolt circle
and bolt sizes chosen and machined. He
has welded on the top connecting flange and drilled and tapped for the final
bolt circle design. Finalized
choice and sizes of seals will be BUSACK AND SHAMBAM 600F Kalraz seals(as this
600psi boiler will operate at about 590F).
Rod
has made a new longer stay rod of ¾”
schedule XXS pipe as the addition of the top head increased the length of the
stay rod. The top tension nut and
seals designed(a preliminary tension of 10K-12K psi will be used on the stay
rod). The original idea to use the
pipe stay rod ID as both a bottom blowdown path( with a pressed in seal plug)
plus a water level control system has been abandoned on this prototype. The
upper top of the stay rod will be for steam outlet to a throttle valve.
We are adding two ¼” schedule 80 side drum pipes to be attached to a
2” pipe vertical header, similar to what
others in our SACA/NE club have done.
This 2” pipe will be used for their water level indicators with small
vertical spark plugs that have electrode extensions to be usable for water level
indications as well as water level control.
I had hoped to use one such plug with a proportional readout depending
upon submersion depth/resistance has been abandoned
as circuit design of such a device would require a lot more time and
study.
As
this is a rich mans hobby being done by those of much lesser means, the
beautiful Penberthy magnetic water level indicator and controller @ $2,700 for a
12 inch length will not be considered---we will have to make our own design.
Craig was kind to send me some of the Radio Shack 12vdc LED’s that he
uses directly without any circuitry and they are truly amazing; they light at
about 4 volts and appear burnout proof at higher voltages.
I ran a bunch of tests with an old small diameter steam table pot about
12 “ in height and as it was a dirty corroded pot to burn waste oil in my
woodstove thought its lack of conductivity and filthiness would be reflective of
a old boiler. I did wash it out and
scrub with steel wool but its surface would not respond to a digital resistance
meter so off to the testing. Good
thing I don’t have a wife, as conducting these experiments on the kitchen gas
stove and bringing all of it to a raging, spilling boil, adding oil and salts
and checking changes in the LED performance. Even when
the 1/16" brazing rod was coated with oil and grit, the reliability
of the LED performance never changed. Even
a violent boiling with 4” of
electrode just above the water level of this boiling caldron
did not ,with all the steam passing by it,
give a false reading---so there is hope.
I
have had time to design a control circuit using the LED
lighting sequence and will
get around to making the circuit board. Basically
it will control a feedwater bypass solenoid valve so that water level in the
tall vertical drum will be controlled within a 6” level with external
adjustments provided.
Rod
has been very busy on modifying his beautiful engine, new steel pistons have
been designed with three rings, the high pressure now made of 4130 steel to
replace the original cast aluminum one that was not made for the higher
temperatures that this engine will be run at—hopefully around 575 degrees F.
The low pressure piston has been redesigned as it had developed a stress
crack on the inner nub due to insufficient wall thickness. Rod is also installing a new bearing oil system to
protect this engine when used above its original speed and inlet pressures.
The
boiler circulating pump has been another great user of time and developed
frustration. After searching the Thomas Register and finding 40 “boiler
circulating pump companies” two
quotes came pack at between $17,000 -$23,000
weighing as much as the boiler and requiring over one horsepower.The GKN
Sintered Metals Company was
originally going to make available some of its bronze/graphite impregnated
material to make the pump high temperature bearing/seal rings we need and it
appears to be a wonderful material. Unfortunately
when asked how many we would require after the prototype bearings were received
a reply that they were not interested---I fully understand that a company that
makes pressed sintered bearings cannot do business with such small quantities
involved---Rod and I are back to step one on the pump bearings and the search
including graphitar and graphalloy plus
a dozen other companies will continue—it all takes a lot of time!!
Finding cheap off the shelf items are sometimes very hard to find.
Tests will be run on this pump and if acceptable new cases and seals will be designed for the considerable higher boiler pressures and temperatures required. This will be a backup to the screw water pump we have spent so much time on. At present it appears we will be able to pump 4000 pounds per hour with a 5 psi pressure differential with only 6-7 amperes at 13.5 volts as we have found a way to greatly reduce shaft seal/packing horsepower to a minimum. Tests will continue .
~click pix to enlarge~
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Much thanks to those that have contributed information and knowledge to this
project in areas that Rod and I are ignorant in.
Only those that have been through the exercise of building a new boiler
and dealt with the considerable problems of all the peripheral
and external support and
control systems can comprehend the task at hand.
Thanks to many friends with generous input, it is only with thoughtful
input that such a project can survive and have completion.
George K. Nutz
