Heating and cooling things down require a lot of energy. How can you do both efficiently?
Cooling wort efficiently with plate exchangers.
Getting wort down to the pitching temperature as soon as possible is desirable to capture your beer’s best flavor. Every minute wasted gets you one minute closer to a truly awful-tasting beer!
An efficient process is to use a plate type heat exchanger called a “knockout,” common on most brewing systems. This is a highly efficient device that uses a counterflow plate and frame design that enables efficient heat transfer from the hot wort to the cooling medium, which is usually water. The heated water returning as hot liquor will never be hotter than the wort entering. It will require additional heating before being used as “hot liquor”. Similarly, cold water entering must be cooler than the wort leaving.
Pre-chilling “cold liquor” and additional heating when it moves to the “hot liquor” tank both consume energy. Proper control of a knockout is paramount in recovering heat and preventing waste.
A Stack Condenser can help save even more energy costs.
After bringing your hot liquor up to strike temperature, you need to heat wort up to boiling temperature and continue heating until a certain amount of water has boiled off and any off-flavor has been removed. All this heat goes out the stack in the roof as hot vapor. Instead of 
installing costly stacks through your roof, a stack condenser device recovers that heat by circulating cooler water inside pipes that hot vapor condenses on. The stack condenses the steam generated during the boil and recover thermal energy from this steam. As the heat from the steam is transferred to the cooling water that is flowing outside the tubes, thermal energy is recovered. This new hot water is pumped into the hot liquor tank for later use.
Another plus in using a stack condenser, it helps to remove dimethyl sulfide (DMS) from the wort, a compound that many brewers want to eliminate.
It’s all about balance.
By recapturing thermal energy, reducing energy consumption, and ensuring consistent beer quality, devices like a knockout or stack condenser help to improve the overall efficiency of the operation.
Smart Ways to Cool Down your Brewing Costs
So much energy is required to bring temperatures up and down, it would seem that saving energy is impossible. However, there are crafty ways to do it! Let’s next focus on how to bring down your cooling costs.
Chill out with Glycol!
One of the most critical steps in brewing is cooling the wort from the kettle to a temperature suitable for yeast pitching. In most systems this is done with a cold liquor tank. A two-stage heat exchanger is a newer, more energy efficient and cost-effective automated solution.
Cooling wort is done through the knockout process. For knockout to recover heat in a stack condenser, all brewers need a certain amount of cold water.
To cool the water, cold glycol is needed through the use of a chiller and/or heat pump. A chiller uses refrigerant to remove heat from the glycol (let’s call the energy “E” in the diagram) and expels it by blowing out hot air into the environment. The chiller uses electricity to pump the refrigerant, pump the glycol, and blow the air across the hot coils. But for all the energy it takes for the chiller to do its job, it can move two to four times as much energy (E) out from the glycol. While refrigeration often gets a bad rap, it is important to understand that refrigeration can move a lot more heat than the energy the chiller uses.
Knocking out cooling costs with a heat exchanger
Once you have cold glycol, you can put it through another heat exchanger – one just like the “knockout” described above. If you pump the water from your tank through the heat exchanger and return it back to the tank, you can remove that same amount of heat (2E), and you will see that the temperature drops. One way to be energy efficient is to use a jacketed tank which circulates the glycol directly through an insulated jacket surrounding the inner tank. Fewer pumps and less piping mean less energy is used and less energy escapes.
Now that you’ve removed a certain amount of heat (2E) from the city water that you put in your cold liquor tank, you can use it to knockout the wort. When you knockout with it, not only does it go back to the temperature it came in at (city water temp), but it actually goes even higher (4E). This additional heat is returned to the hot liquor tank for future use. So, with a heat exchanger and chiller, you can reduce heat from the wort and return it to the cold liquor tank and instead of losing that heat, return it to your hot liquor tank for additional savings!
A Two-Stage Knockout – An Even Better Idea!
In a two-stage heat exchanger, the wort passes through two separate cooling stages in succession. Proportional valves are used to control the flow rate of the coolant through each stage. Automating the proportional valves allows for precise control and minimization of energy usage. Using only a cold liquor tank, a large volume of water is required to cool the wort, and this water is often too much volume for the hot liquor tank. If your brewhouse also uses a stack condenser that is generating hot water during the boil, you may not have room for the hot water generated from knockout and have to dump it down the drain.
For breweries, a two-stage heat exchanger is a great choice for wort cooling. Automating coolant control boosts energy efficiency and heat recovery, reducing costs and environmental impact.
Want to learn more about a new brewing system that uses all the ideas presented here and recovers even more energy? Ask us about the new MARKS EnergyCraftTM Brewing System today!
MARKS Design and Metalworks is a manufacturer of American-made brewery equipment. We are proud to build equipment using stainless steel sheet goods manufactured in U.S. steel mills. Our highly skilled American welders and fabricators craft the finest brewery equipment on the market. We take pride in our craftsmanship.