Thanks for the remarks/questions.
Q1: for some fuels your solution will work fine, might even better then my first design.
However, the solution must be industrial proof and suited for multiple types of fuel. Fluffy fuel is more of the problem as pellets.
Q2: the green lines indicate the position of the swirl baffles to guide the fluegas in a swirl motion around the coil, forcing the fluegas to release its energy more effective towards the coil surface.
Q3: the ash pit as per my design, allows for automated cleaning even during runtime, even possible to use water lock waterflow system or just augers. ( reducing overall downtime )
Q4: the ash should not fall thru the coil, only to be conveyed with the fluegas speed, hence the flow control shield to reduce speed in the ash pit zone, and the baffles to increase the speed again.
The ash pit zones are designed for lower airspeeds, the ash will settle, just below the stack there is also a water spray system to take out the residu from the fluegas stream.
Working on a new type economizer to use the waste heat from the stack to preheat the feedstock/fuel before it go’s to the gasifier/burner. ( extracting vinegar and water , some portion can be injected in the reduction zone to temper the heat and reduce the klinker )