EVALUATING KEGGING OPERATIONS: SEEING INTO THE BLACK BOX Eric Johann Samp, Ph.D. eric.samp@millercoors.com Chris Nimptsch chris@profamo.com
Abstract Kegging operations are critical to the success of both small and large breweries. The operation of keg lines however is a black box since it is difficult to visualize what is happening during the kegging operations. This includes deullage, initial rinsing, caustic cleaning, detergent removal, acid rinsing (if applicable), steam sterilizing, CO2 pre-purging, and filling. Many of these steps are critical to ensuring kegs are clean, sterilized, and filled properly yet there are no simple methods to evaluate this on a keg line through observations. Rotech test kegs are kegs that are retrofitted with temperature, pressure, and fill level sensors that allow one to see inside the black box in order to evaluate and monitor kegging operations. This presentation will walk through typical Rotech test keg profiles and discuss case studies in the industry where issues were identified and corrected. Real life examples will be provided illustrating how to interpret the results and how to improve kegging operations.
Outline Overview of kegging operations Rotech Test Keg (keg, data reader) Software Profiles Saturated Steam Case studies - High temperature steam - Inadequate CO2 Purging (Carbonate Formation) - Negative Pressure after steaming - Lower neck temps during steam hold (air still present) - Low pressure steam during hold, inadequate hold times - Fobbing During filling - Inadequate steam removal - Brimfilling
Best Practices for Cleaning and Filling Best practice is a safe and fully monitored process that gives the required line throughput and results in the kegs receiving more than adequate amount of washing, sterilizing, then filling to the correct volume of beer while maintaining the required carbonation levels with low oxygen pickup and low beer loss while using the least amount of utilities. Andy Brewer
Kegging Operations Overview Pulsed Washing Process Step Deullage Initial rinse Blow Out - Air Purge Caustic Wash - Pulse Caustic Fill / Soak- Objectives Drain previous product out of the keg. Push CO2 out Remove residual product - some times weak caustic can be employed. Sometimes water or mixed water. Remove remaining CO2 inside the keg and water before doing a chemical wash or caustic soak High / Low velocity spray of caustic to clean keg sidewalls and spears Rinse inside keg (entire surface) with hot caustic and soak the neck or in Europe sometimes fill the whole keg. This helps clean the spring basket area of the valve.
Kegging Operations Overview Process Step Purge caustic and water rinse Acid wash Blow Out Acid Objectives Ensure no caustic carryover to acid Optional - depends on keg line OEM or brewery selection Remove acids
Kegging Operations Overview Process Step Hot water wash Blow Out with Steam Add Steam for Sterilization Steaming hold Objectives Remove any residual acid. Hot water assists with increasing inside keg temps Remove hot water, provides heat to increase temperatures inside keg Inject in the keg saturated steam for sterilization. Temperatures should be equal from neck to bottom Provide ample time for keg to be sterilized while exposed to saturated steam (< 275F)
Kegging Operations Overview Process Step CO2 Purge Pressurization Filling Objectives Purge out steam, condensate, and air. Full removal of steam is required to assure no DO pickup. Temperatures inside kegs < 212 F Counterpressure keg prior to filling Fill gently (slow - fast - slow ideal) assuring no fobbing and fill to correct volume (no brimful filling). Final keg pressures < 30 psi (Brewers Association)
Kegs A Big Black Box Neck/valve Keg Mfg Sight Glass Keg Spear Temperature Probe Pressure Gage Dimple
The Problem with Sight Glass Kegs Orientation can be random Need to see all gages (left side gage is hidden) No electronic data logging What happens if you have multiple lanes?
Sight Glass Kegs Large Rackers
Rotech Test Keg Temperature Sensors - neck - middle - bottom Pressure Sensor Level Sensor Data Recorder
Rotech Test Keg
Rotech Test Keg Profiles This profile would keep me as a QA Manager up all night worrying Legend Purple = psi Blue = Beer Black = Neck Red = Middle Green = Top
Definitions Microbial Stabilization Sterilization Any item is considered to be sterile when it is completely free of all living microorganisms and viruses. The definition is categorical and absolute (i.e., an item is either sterile or it is not). A sterilization procedure is one that kills all microorganisms, including high numbers of bacterial endospores. Disinfection Disinfection is generally a less lethal process than sterilization. It eliminates nearly all recognized pathogenic microorganisms but not necessarily all microbial forms (e.g., bacterial spores) on inanimate objects. Disinfection does not ensure an overkill and therefore lacks the margin of safety achieved by sterilization procedures.
A Little About Steam
Relative Differences Between Saturated & Super Saturated Steam
Reading the Profiles Saturated Steam Legend Purple = psi Blue = Beer Black = Neck Red = Middle Green = Top
Reading Profiles Steam Hold Time Legend Purple = psi Blue = Beer Black = Neck Red = Middle Green = Top Start t=343 End t=373
Reading Profiles What is Wrong?
Impact of High Temperature Steam Picture courtesy of Jon B. Graber, Micro Matic, LLC The impact of repeated exposures to high temperature steam (> 275 F) resulting in delamination of the rubber with the metal spline
Reading Profiles What is wrong?
Reading Profiles What is Wrong? No more sleeping at night
Monitoring Steam Pressures Critical parameter Pressure gages feeding keg line should be installed (in the right location) and checked frequently Make sure gages are accessible
Gas Purge & Keg Counter Pressurization After sterilization step, the sterilant must be removed CO2 is typically used to push any condensed steam out of the keg by pushing it through the spear and evacuating any liquid through the gas ports One objective is to slightly cool down the keg side walls from sterilization temperatures to minimize any CO2 loss in the beer as it encounters a hot side wall Target is to get temperatures <100 C If steam remains, it will condense and can be a source of DO pick up
Gas Purge & Keg Counter Pressurization Note: Upright keg fill Start of fill Very weak CO2 Purge
Gas Purge & Keg Counter Pressurization Pressure release and CO2 purge followed by counterpressurization Note: temps @ start of fill < 212 F)
Recommended CO2 Purge Times Steam De-Ullage Keg Size 1/6 bbl 1.5 sec ¼ bbl ½ bbl Recommended Min Purge Time 2.7 sec 4.5 sec Utilizing the Rotech test keg and trialing purge times will help dial the optimal amount of CO2 to adequately push out steam / condensate
Keg Filling Evidence of Fobbing
Brimful Filling & Hydro Static Shock
Final Fill Pressures
Keg Cleaning Some of the Basics CO 2 present in returned kegs will react with sodium hydroxide to form sodium carbonate and water CO 2 + 2NaOH => Na 2 CO 3 + H 2 O http://www.titrations.info/acid-base-titration-sodium-hydroxide-and-carbonate Therefore purging and removal of CO2 is critical Critical parameters are: 1) active caustic % 2) temperature 3) volume & soak time (spring gasket assembly)
Concentration (%) Conductivity (ms) Keg Cleaning Some of the Basics Caustic / Carbonate Titration in Main Wash Tank 1.6 1.4 Study from Gunderman & Hutchinson WBC 2012 160 140 1.2 1 % Caustic % Carbonate Conductivity 120 100 0.8 80 0.6 0.4 Conductivity does not indicate a problem Titration shows rapid loss of active alkalinity, and a rapid buildup of carbonate alkalinity 60 40 0.2 20 0 0 0 100 200 300 400 500 600 700 Kegs Cleaned
Keg Cleaning Temperatures, Amount, Time
Example Low Temp Soak
Recommended Caustic Levels for Soak Keg Size 1/6 bbl 0.3 gal ¼ bbl ½ bbl Recommended Min Caustic Volume 0.5 gal 0.8 gal Although these are not official minimum levels, the objective will be to cover the valve gasket assembly to ensure it is covered during the soak
Utilities Optimization - Example
Process Trouble Shooting
Summary Keg Line Operations can be a black box if one chooses to not use tools available today Rotech test keg is one device that can assist since it does see inside the black box Other critical parameters on keg lines need to be routinely monitored (and recorded) Critical Control Points are:
Q&A