by Ravvin » Tue Jun 18, 2019 7:43 pm
Hi all.
I have a 5 plate Neuraliser with a 500mm packed section containing 2x 500gm rolls of copper mesh separated by loosely packed stainless scrubbers on a 5 Star 50L milk churn boiler..
I have a 1000 litre IBC with a pressure pump to circulate the cooling water. The water comes from the pump to the house through a 3/4" reinforced hose. It then splits at a Y fitting that has a built-in ball valve on each output fork. From the Y, one side goes straight to the PC through reinforced clear 1/2" hose. The other side runs to a 1/2" gate valve and then to the RC in the same sort of hose. The outflow from the PC and RC join at another Y fitting and back to the IBC through more 3/4" pipe.
I did the cleaning run last weekend, using the heads and tails saved from all my previous TPW runs through my T500, watered down to below 40%. I didn't have enough wash to cover the top element, so ran it on a single 2400w element through a voltage controller.
I started the water when I turned the power to the element on and ran it with no restriction to the water flow. After about 45 minutes, I noticed there were droplets falling back down onto the bottom bubbler plate. From there, the plate quickly loaded up and I watched it progress up through the other 4 until they were all bubbling away madly. I had the ball valve on the bottom of the parrot open so I could tell if I was over-powering the RC at any point.
I let it reflux for 30 minutes and started slowly closing the gate valve, watching for the first drips from the bottom of the parrot. I closed it a 1/4 turn, waited a minute to see any change, then closed it another quarter. Eventually, I realised the gate valve was closed, yet water was still flowing. (I worked out later that it was just poorly made, with so much play in the screw threads that the gate could move around and jamb in the housing.)
I reopened the gate valve fully and used the ball valve on the inlet Y fitting. Its really not ideal as it is really hard to get fine control. I was able to get the PC output to either drip or run at a stream that ended up being about 4L/hr. Way too fast for a good run, but ok for a cleaning run. I did 300ml cuts, just for the practice, but this was feints and I ended up just dumping them all in my Bulk Crap Storage flagon for future cleaning runs. The bulk of the spirit coming off had the alchometer sitting around 92%, but it started to drop below 90% near the end.
Now onto Sunday's run and the issues.
I popped the RC off and dumped 10L of hot water down the packed section to rinse out the copper mesh, scrubbers and the plates. Once it drained through, I lifted the still off the boiler and emptied it out, rinsing with hot water to get the last of the pong from the feints out. I can't run a drain hose as the boiler has to sit on the kitchen floor, on a ceramic tile to stop the heat melting the lino. I have about 2" clearance between the top of the still and the ceiling.
I had 2x 30L fermenters filled with CFW. Both had cleared a month or more ago. I had a bit of an oops with one, as I bought the sugar in both 2 and 3kg bags, to save me having to measure it as I use 5kg in a 30L wash. What I forgot was I bought an extra 3kg bag for use in cooking and grabbed the wrong one. So one wash had 5kg and the other had 6kg. The wash with 6kg bubbled for about a week longer than the 5kg wash. When I measured the specific gravity and corrected it for temp, the 5kg wash came out at 9.29% and the 6kg was was 12.13%.
I filled the boiler and started the water and both elements. I ran the bottom element through the voltage controller. After an hour all 5 plates were bubbling away happily, so I shut off the top element. I had the water to both RC and PC wide open and ran it in reflux for 45 minutes and then I dialled the bottom one back to 80% and started shutting down the water to the RC, while watching for the first drips from the bottom of the parrot. I had shut the gate valve right down and used the ball valve to tweak it until it started to flow. I dropped the first 200ml as fores and closed the parrot dump valve. When it filled up, it showed 92% and I started taking off 200ml, then dumped the parrot into the same cuts jar, taking it up to 300ml. I figure if I don't, I am mixing fores with the heads and later, heads with the hearts.
Now the problem.
I was able to dial the RC in so I was taking off between 2 & 2.5L/hr. I noticed that when I had the flow rate just right, the stream from the parrot was curving back, almost like it was trying to crawl back up the outside of the parrot spout. The issue was that after taking the first 300ml cut of heads, the output alcohol percentage had dropped below 90%. Every jar I took off, it dropped more. By jar 10, it was down to 70%. I kept going and by jar 15 it was at 60%. Finally at jar 19 it dropped below 40% and I shut the element off and let it cool with the water opened back up fully for another hour, in case there was any leftover alcohol vapour coming off.
Up until about jar 17, all 5 plates appeared to be bubbling happily. From 17 to the end I saw the top one was almost empty and I could hear splashing in the packed section.
I left the cuts out to air for 2 days and tested them tonight. Interestingly, this is the first time I have had jars airing and yet can't smell anything in the house. Whether it is because its a CFW instead of my usual TPW wash, or whether its the difference in quality between the 5 Star Neuraliser and the T500, I don't know, but am very happy.
With the cuts, I found a very distinct change between jar 7 and 8, so the first 7 jars went in the feints flagon. At jar 15, I could just start to taste a change, jars 16 to 19 also went into the feints flagon. I combined jars 8 to 15 as hearts and it measured out at 60%. I don't think 2.4L @ 60% is right for 50L of CFW at approximately 10%.
What I don't understand is that the cleaning run using feints at around 30% was coming out at mid to high 90's. This run went smoothly, with no surprises other than having the % drop right from the start. I must be doing something wrong, but not sure what.
Has anyone else run into this issue?
Something to consider is that its fairly cool here now. The water in the IBC was 6°. I hope to pick up a decent needle valve to replace the gate valve on the RC line and some really good insulation that was ordered by a local mill for wrapping steam pipes and was left over from the job. It seems a pity to hide all that nice shiny stainless though. :)
Greg.