Project Proposal. Beer Brewing Controller Feb 21, 2012 Olsen J. Salgado

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Todd Briggs
5 years ago
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1 Project Proposal Beer Brewing Controller Feb 21, 2012 Olsen J. Salgado Project Abstract Most brewers begin by simply boiling liquid malt extract (LME) for a set time, then adding hops to attain bitterness which offsets the sweetness of the malt extract. Others enjoy a more complicated brewing method which allows precision control of the flavor of home-made beer. The method is called all-grain brewing, and it is what industrial breweries utilize to make beer. The process can be burdensome to execute manually, particularly if the brewer would like the ability to repeat a recipe and attain the exact same results. To ensure quality control, major breweries apply controlled logic to the mechanical brewing process. As a result, Budweiser for example, has the same recognizable taste in every batch. The brewing controller built in this proposal will simulate the control process used in the industry, but in a much smaller scale for the home user. Most importantly, the controller will automate the mashing/sparging process which is the most error prone phase of all-grain brewing, and the most difficult to control by hand. The wort boiling process will be monitored and the temperature controlled by the control system, alerting the brewer to add hops when necessary. Since this system will manage a live flame, it is important to have built-in safety parameters where necessary. The scope of this project will mainly focus on the development of the control system electronics and code. The main electronics devices will be integrated into this prototype version to the extent necessary to test and demonstrate the capability. A second iteration of this prototype with brewing structure, brewing pots, and plumbing will be necessary in order to brew an actual batch of beer. The second prototype is out of scope of this document. Scalability will be factored into the design of this project so that improvements and upgrades can be added in the future. As an example, I would like to add WiFi capability to allow communication between a recipe design application and the GUI on the brew controller, or a status monitoring application via a mobile device (i.e. iphone, ipad, Xoom, or Android device). Background 1 A little bit of background information about the beer brewing process. Brewing is the production of beer through the fermentation of extracts from malted grains - traditionally 1 Brewwiki Portal, The Brewing Process, 1 P a g e

2 barley or wheat. Malted grains are made by allowing grains to germinate and then drying them in kilns. The malting process creates enzymes necessary for converting complex starches into sugars. Malted grains are then crushed and heated with water in a process called mashing to convert complex starches into simple sugars that can be readily extracted and fermented. The sweet sugars are extracted by running hot water through the grain in a process called sparging. A sweet liquid extract called wort is produced in the sparging process. The wort is then transferred to a large kettle where it is boiled with hops typically for an hour or more. The boiling process extracts bittering oils from the hops to balance the sweetness of the malt, and also sterilizes the wort. The wort is then cooled rapidly and transferred to a fermenting vat where yeast is added. Yeast then ferments the sugars in the beer, producing alcohol and carbon dioxide. After a week of active fermentation, the beer is typically transferred to a secondary vessel for conditioning. After aging, the beer is filtered, carbonated, and bottled, or kegged for consumption. Strategy The brewing controller will automate the process of brewing beer at home with accuracy in temperature and cooking times for various phases of the brewing process. There are four main phases which this controller will automate and/or monitor, plus an additional phase that will be automated dependent on total time available, and baseline complexity of this project. Phase 1 Hot Liquid Tank (HLT): Maintain temperature of water at user defined level, normally around 170 o F. Water level of the HLT will also be monitored in this phase with a mechanical-electrical level float, or some sort of capacitance sensing device. Phase 2 Mashing: Mashing is the second most complicated phase. The brewing controller will be designed around the Heat Exchanged Re-circulating Mash System (HERMS) technique, which keeps the mash at user defined temperature by circulating wort through a heat exchanger inserted in the HLT. Regulating the HLT temperature regulates the MLT temperature. This is an efficient method since the HLT needs to stay heated for phase 3. A problem I might encounter on this step is the difficulty of maintaining a mashing temperature after heating the HLT water to the strike temperature. Since the strike temperature is initially higher than the mash to account for a drop in temp due to the addition of grain, the HLT might need to re-regulate it s temperature down upon the start of the mashing phase. To overcome this I may follow the Temperature Mash technique which simply raises the target mashing temperature while the grain and the water are 2 P a g e

3 pre-mixed together. Once the temperature is raised to the predefined level, it is held there until the starch conversion is complete. 2 To sense the amount of water in the MLT, and shut off or slow the recirculation of liquid to the top of the tank to hold the mash, a fly-sparge float device will be used such as the Blichmann AutoSparge shown here. As the water drains down through the bottom of the MLT, the float on this device mechanically opens the input valve to return wort or sparge water back to the MLT. Mash Temperatures The temperature of mash can have a significant effect on the character of the beer. Lower temperature conversion - around F will take longer but will produce a more complete conversion of complex starches to sugars resulting in more fermentation and a clean, lighter tasting beer. A high temperature conversion of F ( C) will result in less starch conversion leaving a beer with more unfermentable dextrines. This will create a beer with a full body and flavor. Middle mash temperatures ( F / C) will result in medium bodied beers. 3 Phase 3 Sparging: Sparging is the most complicated and error prone step in brewing. The continuous sparge technique, also known as fly-sparging, is the most common method used in brewing today. This method continues to extract the fermentable sugars from the grain after the mash is complete. Water from the HLT heated to sparging temperature is introduced into the MLT via the auto sparge, the water percolates down through the grain bed and picks up the residual sugars left from the mash. The speed of draining is important so either a manual or electric flow control valve must be used and adjusted at the exit of the MLT. The sparge process should cease once the volume of liquid called for in the recipe is collected at the BK. The by-the-book technique of fly-sparging calls for returning the first bit of mashed wort back to the top of the MLT before evacuating it into the BK, and starting the sparging process with new HLT water. This is done to remove the cloudiness from the wort as the grain bed acts as a filter. Since the system applied the HERMS technique during the mashing phase, this step is not necessary and we can simply evacuate all the mash wort into the BK, then introduce new HLT water to the MLT. Phase 4 Boiling: The sparge water enters the BK and the inlet valve remains open until the correct volume is achieved per the recipe. As such, the system will need a method to measure quantity of liquid and monitor this value. Once reached, the pump 2 Brewwiki Portal, Mashing, 3 Brewwiki Portal, Mashing, 3 P a g e

4 will be shut-off and the valve into the BK should be closed. The PID 3 process will take control at this point to boil the volume of wort into a subtle boil for the amount of time specified by the user, usually minutes. The system should set alarms to alert the operator of the need to add hops at predefined times during the boil. Phase 5 (optional) Cooling: The wort should be cooled as quickly as possible and transferred to a primary fermenter upon completion of the boil. For this, a heat transfer device is used such as a plate chiller to remove heat from the liquid prior to adding the yeast. Should time, funding, and feasibility allow this phase to be implemented, I will do so. rmally, this capability is a manual process in the competitors systems, although there are a few home-made systems that have incorporated wort chilling. The process would involve opening a valve to the BK, and pumping the liquid from the BK to a wort chiller through the system s secondary pump. Tap water must be plumbed to the chiller as well, and that must be run simultaneously through the chiller plate. The result is near boiling tap water exhausted from the chiller plate, and cool wort. The following diagram 4 offers a similar, but simpler design of the proposed brewing controller. 4 Jackie Boy Brewery, 4 P a g e

Platform The brew controller will be built around the ZiLog ZNEO Z16 microcontroller, although I will continue to evaluate the AVR Atmel ATmega328 Arduino development platform for possible use.

Many output pins are needed, although implementing a bus addressing method like I2C would cut down on the GPIOs necessary.

5 Platform The brew controller will be built around the ZiLog ZNEO Z16 microcontroller, although I will continue to evaluate the AVR Atmel ATmega328 Arduino development platform for possible use. The final selection will be made after the determination has been made regarding the number of output pins needed. Many output pins are needed, although implementing a bus addressing method like I2C would cut down on the GPIOs necessary. While I am heavily leaning with the ZNEO, it would be nice to use the Arduino platform as it contains several built-in C libraries to drive various brewing hardware components, such as OneWire to control the DS18S20. Additionally, since I own the platform, it would be nice to be able to keep my product for home use. In addition to many GPIOs, a timer would be handy to have available for the user to easily utilize a countdown clock during ad-hoc times through the brewing process. A microcontroller that contains pulse width modulation capabilities is required, and interrupts would facilitate the code, but I do not believe interrupts are 100% necessary. Hardware A picture of what the completed system might look like is shown here. This picture does not depict 100% the actual system that I would like to build. However, it shows generally what it would look like. The framework, or brewing sculpture, will be horizontal as shown. Please keep in mind the focus of this project is to deliver the control system, not the actual brewing apparatus at this point (that would cost much more money). 5 P a g e

6 Electrical hardware components that I will need for this project are: 1) In my research for a thermocouple to regulate liquid temperature I found that I will need a food safe stainless steel (SS) thermocouple. The industrial devices can range over $80 each. To keep costs lower, I will likely opt to utilize an IC based temperature sensing device, such as the Maxim DS18S20 with a SS threaded thermowell. Cost for this solution would be around $30 each. I will need 3 devices. 2) The type of gas valve I will use is still in question. However, there are two types of devices available. One is a simple shut-off solenoid which may be used with a thermocouple to detect flame for safety. These valves do not come with built-in thermocouples from the original equipment manufacturer (OEM), thus the capability would have to be integrated making things more complicated. The cost of the solenoid valve is approximately $150 each; I assume the cost of a thermocouple would be approximately $25 each for a total cost of approximately $175 each. The second possible type of valve is a multi-valve similar to what is found in a furnace or water heater. It has a built in thermocouple that shuts gas off for safety on a no-flame detect. I prefer the use of this type of valve, but the cost might be prohibitive as this implementation calls for 2 valves at approximately $350 each. An issue I am still studying is whether these valves are capable of increasing and reducing the flow of gas linearly, versus simply shutting off. I m not 100% certain that PWM would work properly with these valves, or that the technique wouldn t cause the valves to fail prematurely. 3) Either a manually lit, pushbutton, or electronically controlled pilot light assembly for each gas valve described. 4) Similar to the gas solenoid valves, if I opt to automatically control liquid flow with the controller, I will need liquid solenoid valves. The same issues apply with these components, except that I would not need a thermocouple. Applying PWM might work, but testing will be necessary. 5) I will need two pumps, each approximately $150, although dependent on the number of valves used, the second pump might be unnecessary for MLT to BK transfers. 6) A fly-sparge float valve to ensure the wort flows slowly over the grain at the MLT. 7) A float valve to ensure adequate water level at the HLT and prevent burning the pot. The valve will be electrically connected to the controller from the HLT. 6 P a g e

7 8) A liquid volume measuring device for the BK that can report volume electronically to the microcontroller. I m looking at utilizing a sonar device such as the XL- MaxSonar -EZ0, MB1300_Datasheet.pdf 9) Several toggle switches, a button keypad, a display (preferably LCD but 4-7x5LED matrixes would work), speaker, memory (if I implement the option to store telemetry from brewing). Other hardware: 1) Two burners sized in accordance to the amount of heat output necessary for the size of brewing pots utilized in the HLT and BK. 2) 3 brewing pots or tanks for the HLT, MLT, and BK. 3) Analogue thermometers to attach to each brewing pot (brewers like these legacy devices as back-up). 4) A charcoal activated filter to filter HLT water from the tap. 5) Tube metal for the brew sculpture. 6) Sheet metal for air guards around burners. 7) 4 casters for each leg of the sculpture. 8) Wort chiller if option to integrate in design is executed. 9) Approximately 30 of food grade plastic tubing. 10) Approximately 24 quick disconnects for the plastic tubing. 11) Flexible corrugated gas tubing. 12) Approximately 10 of black pipe or copper piping for gas propane. 13) A gas propane tank regulator valve (found at any hardware store or an old grill). 14) Various black pipe, copper, and MPT fittings (found at local hardware store). 15) GFCI adapter. 7 P a g e

8 Software Modules I estimate the following control algorithms will be necessary: 1) 3 temperature PID control algorithms to manage wort pumps and gas burners. a. PID 1 maintains a steady hot liquid tank (HLT) strike temperature based on user input. Post strike, the HLT may increase the temperature during the mash to prepare for the sparge. b. PID 2 maintains a steady temperature in the mash liquid tank (MLT) via indirectly heating the wort through the HLT. c. PID 3 maintains a steady boiler kettle (BK) temperature and alarms the user at user defined times to add hops 2) Driver for gas solenoid valves that control gas burners. It is yet unknown if I will need to use the gas solenoid valve with pulse width modulation to control gas flow, or if simple on/off commands similar to a thermostat would work. Additionally, the algorithm will be dependent on the type of valve used (solenoid or multi-function). In either case, the algorithm should contain a watchdog function to turn off the gas in a no-flame condition. 3) Driver for the pumps. Since the impellers on these pumps are magnetically driven, there is no need for an algorithm to throttle down the pump. Simple on/off signals from the microcontroller will suffice. 4) Driver for fluid valves to control the output of the sparge wort pump mainly into the BK during the sparge phase. This is also an optional capability and its implementation into this project will be driven mainly by cost. If automatic valve control is not implemented, the same function can be realized by a manual ball valve at the output of the pump and an algorithm would not be necessary. 5) An algorithm is necessary to monitor how much water is available in the HLT to protect the HLT from melting. Similarly, the system needs to know how much liquid is in the BK to stop the sparging process. The HLT algorithm may be simpler as it can be implemented with a float switch via a pin read by the algorithm. The BK water volume monitor will be a more difficult implementation possibly utilizing a sonar system to sense water volume. Transfers from the MLT to the BK are normally accomplished manually by the competitors systems, thus the user can visually estimate the quantity of wort dumped into the boiler. 6) The brewing controller should have one timer with alarm available for use by the operator. 8 P a g e

9 7) Future option: Driver to output system status of health and brewing status for live review by the user. The data would be viewable via a GUI system and logged for review later. 8) Future option: System wirelessly connected to a console for status reporting. Evaluations My evaluations for this system have mainly been from information gathering via the internet. I have found several home-made systems, and various production model systems that work, thus I believe this is a feasible idea. That said my idea is to automate the entire process as much as possible. This might be very aggressive in such little time, thus I might have to tone back the level of automation on this version 1 prototype. Additionally, I have read several data sheets for brewing components (electronic and mechanical) that are necessary to make my project successful (as described above). That said, much more work is necessary especially in the realm of gas control and liquid control valves. I would like hardware that can throttle in and out gas or liquid in linear form. I am not sure I will be able to find components that do this cost effectively, thus I might have to give that idea up and go with full on/full off valves. Unknowns Gas control valves. Liquid control valves. Liquid volume measuring device for Boiler Kettle. IC temperature sensing device. LCD display and keypad for user parameter input (not critical for design, could use LEDs and pushbuttons). How a PID works. Sonar water volume sensing Implementation Plan I will begin development of this project by first testing the components under unknowns to understand how they work. In priority order, I will study gas valves, IC temperature sensor, liquid volume measuring device, liquid control valves, and LCD. Once the components are tested and their operation is understood, I will start to write the code for the PIDs. The software components will be tested practically by keeping a water filled turkey fryer to a predefined temperature. The turkey fryer will be retrofitted to use the final gas valve choice. 9 P a g e

10 The functions to turn on and off the pump(s), timer to wait predefined time periods, user timers, and control of valves will be implemented around the PID temperature control functions and tested with the turkey fryer as they are completed. The water volume detection control software will be tested once the sonar sensor is tested. In order to resemble real life function, input parameters will have to be issued via these tests that resemble what would be passed during real brewing operations. Once all functions are confirmed to work independently, work will commence on the user controls to input data into the software. This is where the toggle switches, keypad, LCD or LED display code will be developed and tested for proper output to the control functions. As a fallback, if this cannot be completed in prototype 1, I am content with simply adjusting variables in raw code and recompiling the software for the time being. Resources ZNEO Z16 development board LCD display 120v 15A relay for wort pump (if available) Gas and liquid valves (if available) Burners with pilot lights (if available) 10 P a g e

11 Main () User interface loop User defined parameters Start Brewing Set start delay Optional: Start Brewing delay function Gas Valves Function (ALL CLOSED) Water Valves Function (ALL CLOSED) Water Valves Function (ALL CLOSED) Turn on water into HLT If water available in HLT Gas Control 1 Function (ON/REGULATE) Sound lights and siren until button hit User Adds Grain into MLT & HITS BUTTON PID1 Control Function (HLT) Pump 1 Function (ON) Water Valves Function (2, 4 OFF, 1,3 ON) Strike Temp? Water Valves Function (Turn on 2 and 4) To page 2 11 P a g e

12 Gas Control 1 Function (OFF) Pump 1 Function (OFF) Gas Valves Function ERROR (ALL CLOSED) If water available in HLT From page 1 Gas Control 1 Function (ON/REGULATE) BK Volume monitor triggered? Pump 2 Function (OFF) Gas Control 2 Function (ON/REGULATE) PID 2 Control Function (MASH) Pump 2 Function (ON) PID 3 Control Function (BOILER) Timer elapsed? Water Valves Function (2,4,6,7 ON, 1,3 OFF) Water Valve Functions (ALL CLOSED) Timer elapsed? Gas Valves Function (ALL CLOSED) Main Boil Timer elapsed? Sound lights and siren until button hit (ADD HOPS) Loop number of hops addition times Wort Complete 12 P a g e

Valve 6 Boiler Kettle (BK) Temp Sensor 3 Mash Liquid Tank (MLT) Valve 2 Valve 3 Heat Xchanger Hot Liquid Tank (HLT) Temp Sensor 1 Water level float Gas valve 2 Burner 2 Burner

13 Valve 6 Boiler Kettle (BK) Temp Sensor 3 Mash Liquid Tank (MLT) Valve 2 Valve 3 Heat Xchanger Hot Liquid Tank (HLT) Temp Sensor 1 Water level float Gas valve 2 Burner 2 Burner 1 Thermocoupl e Temp Sensor 2 Thermocoupl e Gas valve 1 Valve 5 Valve 7 Valve 1 Valve 4 Pump 1 Optional: Pump 2 Valve 8 Gas regulator To Fermenter Chiller 13 Propane P a g e Gas

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