The following post has been submitted by Paul Dodgshun
A Proposed New Design of E-cat Boiler
(using the Operating Principle of a Once-through Boiler and with Steam Conditions suitable for driving a Steam Turbine)
Inspired by the realisation that the finned heat exchanger in the 1MW E-cat is a once-through boiler and having worked at two power stations that used different designs of once-through boilers, I started sketching. How would you put E-cat modules into a high temperature, high pressure boiler that was safe, cheap and reliable?
http://www.thermopedia.com/content/638/ Fig 3 was the main inspiration. A temperature of 400C in the lead in an E-cat is more than enough to exceed the critical point of water/steam (221bar 374C) and we do not want to be building reactors for those sorts of pressures. Steam generating plant in the UK was standardised at 540C turbine inlet temperature, so maybe this can be reached. Lead melts at 327C and boils at 1749C (https://en.wikipedia.org/wiki/Lead).
Take four E-cat reactor modules and place them on end in a square array. Draw a circle inside the square and another two outside. The circles are the plan view of a once-through boiler tube that spirals for the full height of the reactor modules. The once-through boiler tube is immersed in the molten lead shielding of the E-cats. All boiler tails can be above the lead level, as can the electric leads to the E-cat modules.
Producing spiral boiler tube bundles is easy; you just feed a long tube onto a turning drum of the required diameter. The tube materials can vary along their length, if needed, and so can the diameter.
The containment is a thermally insulated steel drum that provides support for the internals and a flanged lid for access but crucially it is not a pressure vessel subject to the steam pressure. The design can take heat from both sides of the fuel wafer and it may well be that the inner spiral would be the superheater and the outermost spiral would be the economiser.
The next size up could be an octagonal arrangement of fuel wafers and the ring of wafers could just keep on growing. Then you could put a second ring tank inside the first. There is no obvious limit to how big this arrangement could be.
Maybe there is a fatal flaw but I have not seen it yet.