Patience is a trait that brewers cultivate from the very first batches they brew. Remember the agonizing wait for your first bottles to condition or for that first keg to force carbonate? Experience and a steady pipeline help ameliorate the painful wait for beer to finish its last step, but even at the biggest production breweries, brewers are always watching the clock and always wishing things would go just a little bit quicker.
In the October/November Gearhead column (“The Force Behind the Fizz”), we looked at how some brewers, especially lager brewers, are using natural carbonation to imbue their beer with bubbles, but the far more common technique is static-force carbonation. The typical setup uses a carb stone in a bright tank, and through controlling temperature, pressure, and time, brewers can dial in the exact level of carbonation they are shooting for. It’s foolproof, but the time it takes is a precious resource in the brewery. Carbonating beer in a bright tank can take anywhere from a few hours to a few days, and this lag time at the end of the brewing process can wreak havoc on the production schedule. While good brewers are not known for taking shortcuts, an efficient brewer is a profitable brewer, and a streamlined process can be the difference between meeting production goals and leaving orders unfilled. Instead of filling a tank with beer and waiting for it to carbonate, many brewers are using an in-line carbonation system to inject carbon dioxide into the beer as it moves from one vessel to another.
A variety of systems for in-line carbonation is available, and the technique scales from large production breweries, such as AleSmith (San Diego, California) and Modern Times (San Diego, California), down to the homebrew level. The way they work is simple and similar from the largest commercial installations down to the homebrew scale. The home brewery setups, such as Blichmann Engineering’s QuickCarb, are particularly simple: A pump pushes beer from one vessel (say a secondary fermentation vessel) past a thumb-sized carb stone mounted perpendicular to the flow in a T-junction and into a second vessel (say a corny keg). A regulated tank of CO2 is connected to the barb on the end of the carb stone, and gas bubbles through the stone and into the liquid. By the time the beer reaches the destination vessel, it’s carbonated to spec. The exact carbonation level of the finished beer can be dialed in by adjusting how much gas pressure is applied to the stone. Since the solubility of carbon dioxide into liquid depends on the temperature of the liquid, you can look up the pressure values on the “carb chart” (see “In-line Carbonation: DI-WHY?”, below). Once the process is dialed in, the system will carbonate a five-gallon batch in about an hour. The commercial systems do the same thing, but the calculations are handled by controller software.
The key to both the homebrewer’s tools and the commercial solutions from companies such as QuantiPerm and ProBrew is the point at which the gas is injected into the flow of beer: the diffusion stone. Made from stone, ceramic, or steel, these porous devices turn the flow of gas into a stream of tiny bubbles that easily dissolve into the beer.
“Carbon dioxide likes beer. It wants to dissolve into the beer,” says Dr. Murthy Tata, founder and president of QuantiPerm. The chemical engineer knows bubbles; he’s been in the beverage business for decades and has a particular interest in how gases and liquids interact. The QuantiPerm in-line carbonation products, the xFlowCO2 and the xFlowMini, both push beer past a custom-made powder-metallurgy diffusion medium while software manages the rates and pressure—the operator only needs to dial in the amount of beer being carbonated and how many volumes of CO2 they want to add. The unit can be placed between a fermentation vessel and a bright tank, before or after a mechanical separator, or as part of a recirculation loop on a single vessel.
“My favorite thing about the xFlow is that it just does what it’s supposed to do,” says Tyler Jones of Broken Tooth Brewing (Anchorage, Alaska). “There’s no babysitting it. You set it, and an alarm goes off when it’s done.” Jones has been brewing beer at Broken Tooth for more than 20 years, and the beers are in high demand. The brewery is part of a family of restaurants including Moose Tooth Pizza—one of the busiest pizza parlors in the nation. It’s a challenge for the brewery to keep up with the thirsty locals and tourists, but the xFlow unit has been a tank-multiplier for Jones. In-line carbonation can bubble-up a beer two or three days faster than the brewery’s typical static carbonation procedure with a carb stone. Commissioned in August 2019, the system is a new tool in Jones’s arsenal, and he says they haven’t had time to finalize their in-line carbonation process. Instead, the brewers are looping the unit into a bright tank and recirculating the beer for about two hours to carbonate. Jones says the flexibility of the xFlow unit was a major selling point—it can even be used to nitrogenate beer. Jones plans to develop some nitro variants of Broken Tooth favorites by using the xFlow between a bright tank and the packaging line and nitrogenating a partial batch while filling kegs.
At Raised Grain Brewing (Waukesha, Wisconsin), the in-line carbonation process is more developed. They’ve been using a ProCarb Plus device that’s integrated into a centrifuge since they upgraded from their original seven-barrel brewery to a 20-barrel production brewery in 2017. “We’ve had zero issues with it,” says Founder and Brewmaster Scott Kelley. “It’s faster, more consistent, and more efficient.”
Developed in partnership with Alfa Laval, the ProCarb Plus is at the top of the ProBrew’s line of carbonation systems. It injects CO2 on the inlet side of the centrifuge’s drum, and the high G forces imposed while the centrifuge pulls out particles in the beer (see “Serious About Separation,” beerandbrewing.com) help the gas dissolve into the beer as efficiently as possible.
QuantiPerm’s Tata sums up the tricky physics of gas dissolution and bubble disproportionation (one of his areas of expertise) by saying: “Small bubbles are more easily absorbed than large bubbles, and large bubbles cannibalize small ones, which reduces dissolution rates.” The high pressures within the drum of the centrifuge ensure that the CO2 bubbles remain small and are quickly dissolved, meaning even faster and more efficient carbonation. “We can go from a crashed beer to canned in the same day,” Raised Grain’s Kelley says, and it helps keep the beer flowing out of his brewery.
Speed and Efficiency, but …
The relative speed at which these systems carbonate beer and the predictability of the process help brewers stick to production plans and scheduling, whether the brewery is one-man-operation in the garage or, as in the case of San Diego’s AleSmith, a high-volume production brewery running two shifts a day. The Corosys CCS in-line carbonation system at AleSmith is hooked up to the outlet side of the GEA centrifuge and handles batches up to 255 barrels. “It saves us a lot of time,” Lead Brewer Anthony Chen says. The ability to carbonate a batch the same day it’s schedule to be kegged means fewer scheduling changes for his staff and fewer delays in getting product to his distributors. The Corosys system can adjust the flow of beer past its proprietary direct gas injectors to ensure perfect carbonation levels no matter how long residency time in the centrifuge is. “We’re not at the mercy of carbonation anymore,” he says.
Beyond the speed and efficiency of in-line carbonation, brewers love the flexibility of the systems, their small footprint on the brewery floor, and the ease of maintenance. All the commercial systems use CIP loops to clean and sanitize, and the homebrew versions can be cleaned with beer-line cleaner and StarSan. But there are some downsides to the in-line carbonation process; several brewers mentioned the difficulty hitting the exact carbonation levels with some setups. “You need accurate measurements before you start,” Kelley says. He uses an Anton Paar CboxQC to measure the exact carbonation level of the fermented beer before it enters the centrifuge, and Jones says his challenge is knowing exactly how much beer needs to be carbonated. The fix many brewers use is to carbonate to 90–95 percent of the final levels and top-off with a carb stone if needed. Jones says that even with the top-off, they still save time and effort.
Whether you’re scheduling a team of shift brewers and constantly on the lookout for process improvements to keep margins up and distributors happy or you’re a homebrewer with a keg of crashed beer that you want to drink ASAP, in-line carbonation systems are accessible and flexible tools for shortening that gap between a finished beer and a beer that’s in your glass.
In-Line Carbonation: DI-WHY?
Take out the automated controls and proprietary gas-injection mediums, and the professional in-line carbonation systems are simple enough to build at home, especially scaled down for home brewery batch sizes. Several brewing channels on YouTube have outlined their build process for DIY in-line carbonation systems that can bring a corny keg up to serving levels of CO2 in just about an hour.
The parts list is manageable: just a carb stone with a barbed gas fitting on one end; a stainless-steel T-joint; a gas line to hook up to your CO2 regulator; two lengths of beer line with the appropriate fittings to connect to your keg; and some assorted barbs, clamps, and fittings. A small self-priming pump and power supply plus the various electrical components to wire it up round out the build.
The pump is connected to the beer-out port on the keg and pushes the beer past the carb stone mounted perpendicular to the flow of beer in the T-joint. Another beer line runs from the output side of the joint and into the gas-in port on the keg. The correct pressure is dialed in on your CO2 bottle’s regulator, and the pump recirculates the beer through the looped system until it hits the target carbonation level. You can determine how to set the gas pressure by looking up your target level of carbonation on the carb chart and cross referencing it with the temperature of the beer you’re carbonating.
The process, of course, works better and faster when you’re carbonating cold beer, but the real trick to nailing the perfect level of carbonation is to adjust the regulator pressure to slightly higher than the carb chart reads. The reason for this is the carb stone itself imposes some inherent resistance to the gas flow, and you have to add a few more PSI to overcome this. Some users of these at-home in-line systems say that setting the regulator to 5 or 6 PSI above what the chart reads gives them the best results. You can tell that the beer is carbonated to your target when no more bubbles are visible in the flow on the output side of the T-junction.
The whole project should cost you between $80 and $100 and can be built in an afternoon. Or if you prefer an off-the-shelf solution, the Blichmann QuickCarb system (blichmannengineering.com/quickcarb.html) retails for about $180. Either setup will beat the old “30 PSI and shake it” method of carbonating (and often over-carbing) your home brewed kegs!
Tim Trabold, Building an Inexpensive, Rapid Carbonator for Brewing:
Blichmann Engineering, QuickCarb™ Instructional Video: