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How does it work?

This page continues the story about RIMS / HERMS and is divided in the following paragraphs:

• Introduction: an introduction of the brewing setup, with a few pictures
• Glossary: explanation of a few common used terms
• The start of the brewing process: a description how the brewing setup is powered up
• Mashing phase: a description how mashing is done
• Sparging phase: a description how sparging is done
• Chilling phase: a description how cooling of the wort is achieved
• And? How does it work? a description of some results, with a few graphs

Every individual phase, along with the coordination of these phases, is being taken care of by the brew program. So any description of an event here is fully automated by that brewing program.

Introduction

The current brewing setup is fairly complex. It is something different than the two small pans that I used in the early days. The brewing setup consists of a number of major components (if you wish to read more details about every component, have a look at the brewing setup):

• The PC: a computer running windows XP, which runs the custom made software program e-brew
• The electronics: All the electronics, necessary for controlling the brewing system, are located here
• The pans / brew kettles: these pans have sizes of 150 L (Hot Liquid Tun, HLT), 115 L (Mash/Lauter Tun, MLT) and 140 L (boil kettle).
• The magnetic pump: the heart of the brewing setup, this pump takes care of transferring fluids from any kettle to another
• The counter flow chiller (CFC): this is the cooler, that cools down the hot wort from the boil kettle down to room temperature
• The gas burners: two burners of 24 kW each (!), adjustable from 0 % to 100 % power (modulating)

The picture shows most of the brewing setup. The Hot Liquid Tun (HLT) is shown on the left side, The Mash/Lauter Tun (MLT) is shown in the middle and the boil kettle is shown on the right. The pump and the CFC are also visible (behind the copper pipes and the green hose in the lower compartment).

This brewing setup is a so-called HERMS / RIMS system.

In order to get a better understanding how the brewing setup does its work, the following illustration may be helpful:

Glossary

There are some specific words, used in the illustration. These words are:

• HLT, Hot Liquid Tun: this is the kettle that contains all the warm water needed for mashing and sparging. This pan (current size is 90 L) is replaced shortly by one of 150 L
• MLT, Mash Lauter Tun: this is the kettle, where mashing takes place. It contains the malt with the water. This is a double-walled pan, with isolation in between. The total net volume is 115 L.
• Boil, the boiling kettle. The result (called the 'wort') from the mashing phase is collected here. The hops are added to the wort, and then the wort is brought to a boil for 2 hours.
• CFC, Counter Flow Chiller. The beer from the boil kettle is cooled down to room temperature by this component. The cooled down wort is then pumped to the fermentation bin
• V1 .. V10: these are manual ball valves. that can be opened and closed. In fact, this is the only equipment that is still under manual control. But there are plans to replace these manually controlled valves by solenoid valves, which can be controlled by the brewing program
• Fermentor: the fermentation bin. I have a number of bins, ranging from 30 L up to 120 L

The start of the brewing process

I start by rinsing all the pipes. Then I close all valves, except for V8. This valve has a special function, that of pump by-pass. You can use it to regulate the net flow through your system (I have measured values between 3 and 12 litres per minute).

Next I check all the pipes (connected with quick-connect couplings). I fill the HLT with fresh water, then the brewing program takes over and lights the burner until the HLT temperature is 57 °C. The heating of the water in the HLT can also be controlled with a time-switch function built in the brewing program. You set a time and a date and at that time, the brewing program switches on the heater. So if you are ready for some brewing early in the morning, the water is already at strike temperature!

Then, V2 and V4 are opened and the pump is activated. The desired amount of water is pumped from the HLT into the MLT. During this, valve V1 is opened, so that I already have a flow from the MLT through the pump, through V4, through the heat-exchanger (in the HLT) and back again to the MLT. After reaching the correct volume in the MLT, valve V2 is closed (the pump remains on all the time). The next thing to do is to add the milled grain to the water in the MLT.
Valves V9 and V10 are added for convenience during sanitation and are normally closed during brewing operations.

As far as valve V5 is concerned: this valve is not really used anymore. Initially it served the purpose of heating the HLT water to the next temperature during a mash-rest. In order to prevent that the mash water was heated as well, valve V5 was added. If this valve is opened (and valve V4 is closed), the heat-exchanger in the HLT was bypassed. But it was easier to just switch off the pump when pre-heating the HLT water (which is what is programmed into the brewing application).

The Mashing Phase

The mash water is circulated continuously (MLT -> V1 -> pump -> V4 -> HLT heat exchanger -> MLT). By increasing the HLT temperature, the program can also increase the MLT temperature. I can even do step raises by opening V5 and closing V4. Experience shows that the initial HLT temperature should be about 3 °C higher than the MLT temperature. So if I want 52 °C in the MLT, I set the initial HLT temperature to 55 °C.

The Sparging phase

After mashing is complete, valve V7 is opened and a part of the wort is pumped into the boil kettle. The program stops pumping when the desired volume is achieved. Then valve V7 is closed again and V2 is opened. The water level in the MLT will increase again, because fresh water from the HLT is added to the MLT. If the desired volume is added, valve V2 is closed again. The program recirculates this for 20-25 minutes through the mash.
Then valve V7 is opened again and some of the wort is pumped into the boil kettle. The program repeats this 4-5 times (adjustable within the program). So if 50 L of sparging water needs to be added, the program adds 5 times 10 L (or 4 times 12.5 litres). During the entire sparging phase, the program controls the HLT temperature and keeps it close to 80 °C. After sparging, all wort has been collected in the boil kettle and the pump can be switched off. All valves are closed again. I make sure that the burner under the boil kettle is lighted as soon as possible. I want to start boiling just after I finished sparging. I add the hops and boil for 90-120 minutes. Meanwhile I clean the MLT.

Chilling phase

When boiling is finished I let the wort rest for 5 minutes, Then I connect the counter flow chiller to the water tap and open V3 and V6. The pump is switched on and it pumps the hot wort through the counter flow chiller into the fermentation bin. The counter flow chiller is extremely efficient: it is able to cool 50 L of wort from 100 °C down to 20 °C in approx. 10 minutes. The cooling water that comes out is boiling hot (ideal to clean things with). If all wort is pumped through, the pump is switched off. Then cleaning can start. I pump the remaining hot water from the HLT through all the pipes and the counter flow chiller.

And? How does it work?

Great! I initially encountered some problems, such as a leaky pump and unreliable thermometers. But having a pump makes a big difference. Temperature is much better to control. And you don't have to walk around with heavy pans anymore. No more waiting for an hour to cool things down. I managed to save several hours compared to the setup without pump and counter flow chiller.

Another advantage is the flexibility of the computer program. I wrote the program in such a way that all process parameters are adjustable, such as the number of sparging batches, or the P, I and D values of the PID controller. Parameter values are saved automatically in the Windows Registry, so that when you restart the program, these parameters are set to the latest value.

And if I require functionality that can not be realised with changing parameters, I write an update of the brew program. In this way, a number of updates have been realised!

This is a graph that is reconstructed from a log-file. It shows the various temperatures during a brewing session. The brewing program writes, every 5 seconds, all relevant data into a log-file.

Explanation of the graph:

• Tset_MLT: this is the reference temperature for the Mash/Lauter Tun (MLT). This should be the actual mash scheme that you want to use
• Tset_HLT: calculated by the program. It typically is set a few degrees higher than Tset_MLT in order to compensate for temperature losses
• Thlt: the measured and filtered actual temperature of the HLT, which is read from a digital (12 bit + sign) temperature sensor that is mounted inside the HLT
• Tmlt: the measured and filtered actual temperature of the MLT, which is read from a digital (12 bit + sign) temperature sensor that is mounted inside the MLT
• Ttriac: the measured actual temperature of the power electronics inside the electronics box (the system is shut down when this becomes too high)

One of the striking things in this graph are the sine-waves / ripples in the HLT temperature (yellow line). It is an indication that the PID controller has not been set properly! The second graph (below) shows another response, but then from a properly set PID controller. The HLT temperature is, in this case, the fat blue line.
The ripples in the previous graph are almost completely gone. The temperature is controlled to within 0.05 °Celsius. You can barely see 5 little peaks in the graph (at the right end of the graph). These are the moments that sparging water from the HLT is transferred to the MLT. But the PID controller reacts very well to this disturbance.

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