Merry Christmas, everyone! I just put My Lan to bed and am waiting for the family to get back from the airport, so I thought I’d provide an update. My study schedule has curtailed my tinkering but hasn’t extinguished it entirely. I’ve been slowly making little changes and cobbling together a RIMS (Recirculation Infusion Mash System). The past four weeks of IR and nights has left me with many hours that were too odd to study but too scattered to sleep, so I managed to wrap much of it up. Conical Bliss Before moving on to the news, I’d like to report that the conical fermenter is working great. I’ve read mixed reviews about the plastic conicals, and getting the conical into the cabinet with a clean-in-place configuration was no small feat. The convenience of 10 gallon batches, precise temperature control, and rapid kegging have proven worth it after only two batches. Watch how quickly I can fill a 5 gallon keg! RIMS Mounting I took my seasoned 5400 W Camco heating element and mounted it in a 1.5″ stainless pipe. There’s a 1.5″ cam lock fitting for easy inspection. There’s also a 1/2″ thermowell mounted at the outlet for a 1/4″ temperature probe. The whole unit is mounted on a plastic cart from Harbor Freight, secured with cushioned stainless pipe hangers from eBay and 3/8″ stainless bolts cut to fit and secured to the cart with my Chugger pump and the control box. It’s Probably Big Enough The enclosure has been a difficulty of its own. I underestimated the size of the L6-30 plugs I use for the 240 VAC connections since the circuit has to handle 25 A, so I had to make housings for the plugs only. You can see those monstrosities hanging off the bottom of the enclosure. Actually contained within the enclosure are a switch (on the left), an AGPtek PID controller, and an SSR with heat sink. The PID controller will eventually be substituted for a custom board, but that’s a project for the future. Magic Smoke The SSR was also a frustration. I initially bought a Fotek SSR-40A, but it failed on its first cycle, giving up its magic smoke immediately. My expectations of evidence are high, so I grabbed the fire extinguisher and tried it twice more. When it looked like Independence Day in the enclosure, I concluded confidently that it was broken. I ordered a higher quality Berme brand 40A SSR, and it passed the initial test with flying colors. Wires and Circuits and Breakers, Oh My! Lastly, I swapped out the 30 A dual pole circuit breaker for a similar breaker with a ground fault circuit interrupter. GFCI is a safety feature that breaks the circuit if there is a current outside the electrical circuit, for example, through your heart. These are the same devices on the plugs for blow dryers that have Test and Reset buttons, and they’re good to use in circuits that are near conductive fluids like wort. I’ll be brewing a Belgian-Style Stout this weekend
Even though I mainly brew beer to try to salvage what’s left of my engineering mind, I also just like beer. I worked hard for the last batch I brewed, but I wasn’t too hopeful it would turn out well. It’s nice when things turn out better than planned. My first (technically) partial mash came out quite tasty. The fresh wort definitely contributes complexity. More importantly, the nutty flavor that pervades the liquid extract sold at my local brew store is absent. And at 8.1%, it does the trick. The Tigers are playing Florida. Geaux!
I’ve been neglectful. Only a few of my friends are into brewing, and fewer still are into coding and electronics, but this is all that’s been discussed in this blog. Most of the people who know me are more appreciative of the ludicrous messes I get myself into. I apologize for the oversight. This one’s for you. September 16 was going to be a great day because I was planning to go all grain. This is a big brewing step. Instead of making wort with syrup or powder malt extract, the malt is made fresh on brew day from barley. It’s more complicated than just mixing grain with hot water. The grains have enzymes that have to be given time at just the right temperature to break down polysaccharides into mono- and disaccharides that yeast can ferment into ethanol and other aromatic compounds. It adds time and complication to the brewing process, but brings the promise of more complex flavor. I heated up some strike water, the hot water that’s mixed with the grain bed. I’d bought 32 lb of fresh milled grain from the brew store. It smelled delicious. I put the grain into the mash tun, a container with a false bottom to keep the grain bed. There are a few ways to dough in, which is the process of mixing the water with the grain bed. I chose to let the water seep in from the bottom. I had no idea, but things were already going terribly wrong. I circulated wort in from the bottom using my pump to improve mass transfer and keep the temperature consistent throughout the grain bed. I still had no idea there was a problem, much less that I was making it worse. During the mash, I monitored the temperature of the bed. 150 F was the goal, so here is a picture of the thermometer right at 150 F. Of course, this picture is a gross misrepresentation of the average temperature of the bed. The temperature swung wildly between 140-160 F while I was chasing it frantically with ice and boiling water. I think I even added them simultaneously at one point. Oh well. It was still smelling nice, and it’s not problematic as long as it doesn’t hit 170 F for too long. Finally, the mash was done and it was time to drain the grain bed into the brew pot. I used a continuous sparge, a technique of flushing the grain bed with hot water from the top while removing wort from the bottom. The objective is to rinse the sugar out of the bed. It wasn’t until this was done that I learned there was a problem. The specific gravity of the final wort measured 1.04. I only extracted 37% of the sugar. 80% for this technique would have been good. 70% would have been bad. 37% is embarrassing. To troubleshoot, I checked the specific gravity of the wort still left over in the mash. It should have measured near 1.008 to reflect that the sugar had
When cooling wort with my countercurrent exchanger, it’s important to know the temperature as it comes out. The goal is to bring the wort to the optimal temperature for pitching yeast as quickly as possible. Many commercially available chillers have a thermometer at the wort outlet for this reason. I improvised during my last brew session because I didn’t have time to get the thermometers working. The Saints were doing terrible today, so I turned off the game and worked on getting the thermometers on my exchanger finished. All I really need is to know one temperature, so naturally I installed four thermometers. Yes, four. I’m nosy and I want to know them all. This is about more than validating the name of the blog. The energy balance for heat exchange looks like this: So, doing a heat balance on the exchanger requires the inlet and outlet temperatures of both streams, their heat capacities, and their mass flow rates. I may make full use of this later, but for now I can use the change in the temperature of the water to know how I’m doing with the trade off between efficiency and time. I had already installed my trusty OneWire thermometers in-line on the wort inlet, wort outlet, water inlet, and water outlet when I built the exchanger. They’re the black cables leading into the compression fittings. I just needed a way to talk to them. Enter the custom microcontroller with a NRF24L01+ breakout board. I posted about this little board a while ago. I originally intended it to control a valve with a stepper motor, but that was a bust. I’m going to redesign the valve, but this little prototype still needs a home. Fortunately, it has everything needed for the exchanger: the radio breakout board to communicate with another device and an exposed header that is compatible with a OneWire network. One step I’d skipped thus far in my misadventures is the experience of soldering my own perforated boards, but it finally came up. I’ve tried before and it was always a mess because I didn’t take the time to do it right. It’s easier to design the circuit on a breadboard, build the board in Eagle, and have it fabricated. I needed a way to connect all the thermometers to one header on the board. It wasn’t a big enough problem to design a whole board, but I did want something nicer than a bunch of spliced wires. I finally unpackaged a small perforated board and soldered a bus board. It seems pretty pathetic, but getting wire to stay in place while you solder across pads is annoying. Still, a little tape and a nice pair of needle nosed pliers go a long way. I’m not about to start soldering circuits more complicated than this simple header, but it’s nice to know I can manage not to fail miserably if the need arises. I destroyed yet another old tupperware to make a case, bolted in the custom board and the hand-made header, connected the thermometers, and fastened it to the
Today is my first day brewing with the latest iteration of my brewery. That includes a Chugger pump, my countercurrent heat exchanger for wort chilling, and my conical fermenter with upgraded cabinet controller software. Thank goodness the friends I invited had other plans. The day started stressful when I snapped a polypropylene female camlock fitting while tightening an adjacent threaded fitting. I quickly replaced it with a stainless fitting, finished tightening things up, and the day improved thereafter. The first task was to sanitize the conical fermenter. This meant making a 5 gallon batch of Star San. I knew it would foam when I turned on the sump pump, but what a mess! The foam nearly filled the 15 gallon conical tank. When I turned off the pump, the foam ran out faster than I thought and overfilled two buckets. It got all over the place! I saved a gallon like I always do, but I had to store the other four in a couple of cornelius kegs. I don’t have anywhere to keep these cool, so I can’t reliably store the Star San for the next brew session. It’s not like the stuff is expensive, but I’d like to optimize my use if I can since it’s a synthetic detergent. At least I have two sanitized kegs ready to take the beer from this brew session. Another difference is that my burner has wheels! I like to brew close to the garage door for ventilation and to enjoy the weather, but I need to move the pot to the cabinet to pump it into the tank. I could either get really long hoses or make my brew pot mobile. Until I go all electric, I chose the latter. This has an additional benefit: I can fill the brew pot directly from the cam lock water supply I installed in my garage. I burned a couple of new lines on my brew paddle at 10 and 11 gallons since I’m doubling the batch size and got to work! One of the more annoying tasks with extract brewing is getting liquid extract dissolved. Dry extract is luxurious. It floats on top until it dissolves. It’s also expensive. Liquid extract is much cheaper, but it’s a sticky syrup that sinks straight to the bottom where it scorches. I previously dealt with this by slowly dissolving the extract with a metal strainer. Now that I have a pump, I can aggressively circulate the wort while adding extract! Sweet. With the extract dissolved, it’s only a matter of getting through the hot break. This is the point in the brew when the surface tension of the wort transiently increases, and bubbles form like crazy. With 5 gallon batches, I never worried too much. A 15 gallon pot can hold the entire hot break of a 5 gallon batch. I braced for the hot break and watched vigilantly. I was very underwhelmed. The hot break was prolonged and mild. I
The recipe for beer is pretty simple. One important step is boiling the wort, the sweet mixture that yeast will ferment into beer. Boiling sanitizes the beer so that yeast can work its magic, but not before the wort is cooled back down or the yeast meets the same quick, steamy end as its potential competitors. There are many ways to cool wort, but I recently upgraded my cooling technique to the optimum method: countercurrent heat exchange. I previously used this immersion cooler. This is a good method in which a length of coiled tubing is placed into the wort. Cool water is pumped into one side and it comes out hot on the other, all the while cooling the wort. Despite the ease of execution of an immersion chiller, it’s limited. Initially, there is a large temperature difference between the wort and the cold water running through the chiller, and it works well. As the wort cools, the temperature difference between the wort and the water decreases, and the cooling is less effective. It takes more and more water to accomplish the same heat transfer. Countercurrent exchange doesn’t suffer this limitation, and this is why it’s a superior heat transfer method. How it avoids this limitation can be demonstrated by comparing the countercurrent configuration to the parallel configuration, which is somewhat similar to the immersion chiller method. Here’s a diagram showing both flow configurations: Both involve a tube within a tube. The inner tube is usually made of thin metal so that the fluids can easily exchange heat across the metal. In the parallel configuration, hot wort is introduced at the same side as cold water. As the wort and water flow through the tube and exchange heat, they approach the same temperature you would get if you mixed the two in a bucket (ignoring the thermodynamic effects of mixing). In the countercurrent configuration, hot wort is introduced at one end and cold water is introduced on the other. This results in a very different temperature profile for each fluid along its path. Check out this diagram from Engineering Toolbox: The result is that the wort is continuously cooled throughout its path while the cold water is continuously heated throughout its path. To phrase this more practically, you more fully utilize the cooling ability of all the water you use. Unlike the immersion chiller that only heats the first amount of water to near the starting wort temperature, all the water used in a countercurrent heat exchanger will be heated near the starting wort temperature. While countercurrent heat exchange is limited by the surface area and the flow rates, so are other methods. For any exchange method, too small a surface area or too high a flow rate and the fluids don’t have a chance to exchange enough energy. Countercurrent exchange is not equilibrium limited, and this is the difference. Countercurrent exchange isn’t just an engineering technique. It evolved biologically and is evident in many homeostasic mechanisms. My favorite is the kidney, an analogous example of countercurrent mass transfer. Remember those tubules and the sodium gradient? That’s countercurrent
The recent modifications to the cabinet warranted a small software upgrade. The power and heat transfer of the two modes are drastically different. The heating side, a SSR-throttled in-line water heater element, can increase the temperature of the fluid much faster than the thermoelectric chips I was using previously. The cooling side, a copper coil sitting inside the refrigerator, is much slower; in fact, it has to slowly cool the fluid reservoir before it even approaches a useful rate of heat transfer from the fermenter. Previously, I’d used a single set of control parameters for both the heating and the cooling side, but the parameters are now too different. I had to rewrite the code to use different PID parameters for each. This is trivial, but rewriting the TCP communication protocols to include the parameter values so that I can change them for the purpose of tuning took a little time. Here’s the current control scheme: This is essentially a dual-loop control configuration with a bit of switching logic included. In simple terms, one controller uses the temperature of the fermenter to determine what temperature the heat exchange fluid should be. The heating and cooling controllers measure the current temperature of the heat exchange fluid, compare it to the desired temperature, and adjust the power output to bring the temperature to the setpoint. A bit of control logic (which actually includes another controller) determines whether the the cabinet should be in heating or cooling mode. This is necessary to keep the cabinet from inappropriately switching between the two modes when the temperature of the fermenter is near setpoint. By “controller” I mean PID. Many brewers are familiar with discrete hardware units that are called PID controllers, but PID control is really just an approach to controlling a measured variable by changing a process output. I wrote a software PID object in C++ based on my father’s Visual Basic implementation (check out his blog to see that I am a small chip off a very large block) that I use in the software for the microcontroller that runs the cabinet. I omitted derivative control, opting only for proportional and integral. As my father would say, derivative control isn’t often that important. An important thing to know about PID controllers is that they have to be tuned. Plainly, this setting how the controller reacts to the error it detects. A well tuned controller will quickly reach setpoint. An overtuned controller will oscillate aggressively about the setpoint. A loosely tuned controller will take forever to get there. An incorrectly tuned controller will blast off in the wrong direction, an undesirable and possibly unsafe scenario. Rigorous controller tuning would require a decent process model. I don’t have even a simple one and don’t care to make one, so I opted for manual tuning. This is an iterative process that involves perturbing the system, watching its response, and adjusting the PID tuning parameters accordingly. Here is the data from the last bit of cooling mode tuning. I decided to get the fluid temperature controller tuned for the cooling
It’s ready for a test drive. The conical fermenter is assembled and in place, ready to make some delicious beer with the convenience of a commercial brewery. The last part needed was a clean-in-place system. Since my fermenter is so challenging to get in and out of its mounted position in my cabinet, I need a way to clean and sanitize it without taking it out for scrubbing or shaking. The solution is a system that vigorously sprays the inside of the fermenter. I fiddled around with a homemade apparatus, but quickly abandoned it for something more reliable. I got my hands on a rotating spray ball from Brewer’s Hardware. This fitting has a ball with biased slots. The slots spray fluid from the ball and are configured so the flowing fluid rotates the ball, cleaning the tank wall. I tried attaching the spray ball to a few small pumps including my Chugger pump, but the flow rate wasn’t sufficient. The ball barely sprayed and didn’t spin at all. I had to get a high volume, intermediate pressure sump pump from Harbor Freight. I mounted the spray ball in the lid of my fermenter along with a check valve to prevent negative gauge pressure in the tank during draining, and I gave it a test. Watching it from the outside is important and useful, but it’s a little dull. I decided to get a better view of the action with my GoPro – if only for entertainment purposes. Once it was working, I realized that I have no planned additions to the fermenter for a few years. Thus, it was time to mount it in the cabinet! It was tricky, but once I figured out how to slip the collar in place it was a piece of cake. Now it just needs some wort, yeast, and a little time.
Trang and My Lan were out of town over the weekend. While I’ve mostly forgotten what it’s like to have the place to myself, I did manage to keep busy working on an academic manuscript and, of course, the brewery. Between the broken cabinet fan, the conversion from thermoelectric chips to a tube mounted water heater, and the conical installation, the cabinet has been in pieces for weeks. Fortunately, it’s slowly coming back together. I replaced the thermoelectric chips with a water heater mounted in a stainless steel tube. It’s only a 1200 W element but is much more powerful than the chips. I tested the system at only 1% power and the fluid temperature increased 10 degrees Celsius in about 30 seconds. Nuclear winter won’t keep me from my ales. I’ve also gone back to a smaller aquarium pump in a bucket. The Denner magnetic drive pump I had in place before was a little noisy and overpowered, so I’ll reuse that for my clean-in-place system. The bucket mounted pump is quiet, adequate for the system (I measure a flow rate of 30 mL/s), and can fit inside the refrigerator. Putting the fluid reservoir in the refrigerator might also allow me to make cooling more efficient. Secondly, I redid the wiring for the whole system. I run the power for the pump and heating element directly through the wall of the refrigerator. The thermosensor wiring is all new, with pre-terminated RJ-45 cables that don’t have to be secured with rubber-bands to maintain a connection. They’re all connected through my OneWire hub circuit board and providing reliable signal. I just need to tidy up the cables. The cabinet fan still doesn’t work although I’m sure the controller is providing power. The immersion coil may make the cabinet radiator obsolete in the summer, so I’m not in a hurry to fix it. Removing the thermistors frees up a second fan terminal for the controller, so I may put a large fan into the refrigerator to increase heat transfer at the copper coil inside. I’ll wait until I can run a cooling test with the conical in place to see just how cold I can get 5 gallons of water. Once my CIP fitting arrives, the conical will be ready to go into the cabinet. I’ve put my Chugger pump on a temporary mount. All I need is to put my burner on wheels and finish the counter-flow heat exchanger, and the back end of my brewery will be finished!
I finally pressure tested my fermentor!Several brewers have made conical fermenters using plastic tanks. These tanks have the benefit of a valve at the very bottom. This allows the removal of trub (dead yeast) without transferring to a whole new vessel. The disadvantage is setting up a conical fermenter takes a little more work. Using a simple ball valve on the bottom is problematic. Ball valves have a recess between the body and the ball that collects fluid. For sanitary operations, these would have to be sanitized with heat and occasionally disassembled. A superior approach is a butterfly valve. These valves have no recess to collect fluid, but are mechanically more complicated since the disc has to mate with a gasket. They’re typically much more expensive, but I found a couple of beautiful 1.5″ stainless butterfly valves with silicone gaskets for nearly nothing on eBay. A couple of tri-clamp adapters from Glacier Tanks and a 1.5″ camlock adapter from ProFlow Dynamics makes my valve assembly. Unfortunately, this is where things got tricky and delayed the project. I failed to account for the length of this valve assembly when designing my Fermentation Cabinet. I also designed the doors of the cabinet to account for the tank but not the metal frame. To make an embarrassing story short, I attached hooks to the tank walls for hoisting it into place using small pulleys in my cabinet. The hooks are attached with stainless bolts and washers, which are internally sealed with 1/4″ silicone o-rings and gaskets I made using silicone sheet and punch tools. I built a simple frame into which the tank is lowered in the cabinet, giving enough clearance for the valve assembly. I also wanted to add an immersion coil, something I haven’t seen anyone do with a plastic conical yet. This will make my temperature control system more efficient since I’ll pump the heat exchange medium (I use water) directly through the tank instead of heating or cooling the air around the tank. I got some 3/8″ stainless tubing on eBay that sat in someone’s closet for a couple of decades and a couple of stainless compression fittings. I discovered two things when making this coil. First, bending stainless tubing is not easy! I invariably end up bleeding every time I do it. I wasn’t able to make perfectly smooth bends in the long segments, but the small kinks are only cosmetic and may even improve overall heat transfer by adding turbulence. Second, the walls of the plastic conicals are thicker than stainless vessels. Getting the male NPT fittings through the vessel wall required NPS locknuts from Bargain Fittings. I also wasn’t able to place a washer between the camlock adapter on the external side and the tank. I’ll just have to hope it doesn’t break. I also added a camlock adapter below the liquid level for a temperature sensor and another near the top for a blow-off tube. Finally, I pressure tested the vessel by filling it to the brim. There weren’t any leaks