Improving Output of Your Current Brewhouse (Part 2: Boiling, Whirlpooling and Wort Cooling)
Part 2: Boiling, Whirlpooling and Wort Cooling
Whether a brewery has two or five vessels in their Brewhouse, there are five key process steps that cannot be skipped, truncated, avoided, or bypassed: Milling and weighing up, Mashing, Wort extraction(including spent grains removal), Wort boiling, Wort cooling (including trub separation).
Generally speaking, these steps create one linear brew cycle. In this second installment in our series of articles about ways to get more production out of your brewhouse, we will be discussing boiling, whirlpooling and wort cooling.
Wort Collection and Boiling
Running off the lauter tun and filling the kettle is often the longest part of the linear brew cycle. Time is often wasted in heating the kettle to boil. Some considerations regarding the heating of wort during runoff and boil:
- Heating capability of boil kettle. Whether the kettle is jacketed or has an internal or external calandria the heat transfer surfaces must be correctly sized and located to ensure the contents are at boil in accordance with client requirements.
- Insulation. Reducing the potential for “radiated losses” and also afford operator protection, it is important to insulate the kettle surfaces. A minimum of 3” of insulation applied to the bottom head and side wall areas is recommended.
- Vapor evacuation. It is important to correctly size the vent stack to facilitate efficient removal of vapors and condensables. Evaporation rate, length of stack and ambient conditions are important factors in the stack sizing. In cases where “stack fans” are employed, again sizing is key. When using fans with open door boiling the entrained air sub-cools the upper layer of wort, giving rise to a less vigorous boil, loss of evaporation rate, lower skin temperature and ineffective removal of volatiles. If the fan is too small, it will restrict vapor flow enhancing the potential for an over boil. Too large and wort droplets can be pulled up the stack and yield a shorter knockout volume.
- Steam Pressure. If you have examined steam tables, you will realize the importance of steam pressure and its relationship to temperature. A high pressure boiler is ideal, since when regulated down for use in the brew kettle it will remain consistent at pressure independent of other brewery demands. A low pressure boiler will fluctuate in pressure as the load on the system changes. Most control systems for low pressure boilers will shut them off if they detect 15 psi steam pressure. There are also pressure relief valves on the steam piping that will relieve at 15 psi in low pressure systems. For these reasons, the boiler’s pressure set point should be set as high as possible to where it won’t shut off, but fluctuations will occur.
- Quantifying. Gauging a temperature (rather than a perception of rolling boil) to being boil time can add structure to your brewing process and ensure a more consistent product.
Whirlpooling and Trub Separation
Whether you have a dedicated whirlpool or are whirlpooling in the kettle, trub separation is important to product quality and yield. It is also important to minimize solids going through the wort chiller. Today’s beers are trending toward late addition hops, which means you will likely be adding them in the whirlpool. There are several whirlpool/kettle design factors that will help minimize time while not sacrificing separation capabilities:
- Tank Geometry. The main function of the whirlpool process is to spin the contents of the tank to allow trub pile to form in the center of the vessel. Implicit in correct whirlpool sizing is the H/D ratio, wort volumes and gravities, including hop and addition rates. Provided the H/D ratio is correct, in the majority of cases a single sloping flat bottom in the range of 1/8” to ¼” per foot will allow for excellent separation and wort extraction.
- Draw off port(s). Efficient trub pile formation not only relies on item 1 above, but piping and entry velocity (WCM suggests a kettle KO time in the order of 10-15 minutes.) and wort draw-off port location(s). Trub does not form all at once during the rest phase, larger particles settle out faster leaving the fine smaller ones to gradually migrate by the natural centrifugal action. The use of multi-port draw-off points should enhance pile formation and result in improved wort quality delivered to the cellar.
- Trub Removal. Water is an expensive commodity. Design of the trub removal nozzle(s) should target efficient and timely removal while minimizing water usage.
The last step in the brew cycle is mostly about equipment sizing, but there are some procedural provisions that should be considered:
- Time. Wort chilling will typically be a 30-40 minute process, although equipment can be sized to target almost any time.
Cooling fluid. Breweries typically use water, cold liquor, glycol, or a combination to chill the wort via a plate and frame heat exchanger. Limitations in the temperature capabilities of the setup can cause knockouts to go longer than the target time. It is important to correctly size the wort cooler, based on cooling time, wort temperature ranges and line pressures. Coolers are generally single or double stage. Whichever cooler option is used, it is important to look at the energy balance of removing heat (wort cooling), water use/regeneration, together with refrigeration demands.
- City Water –City water temperatures vary due to region and season, and depending upon the cold wort temperature, supplementing by either Chilled liquor or glycol could be required.
- Cold Liquor (Chilled Water) – Cold liquor ensures a constant cooling media that is always below the target knockout temperature. Chilled water is turned into hot water and re-used in the brewing process.
- Water and Glycol – Supplementing the cooling water’s capabilities is often done with a second stage in the plate and frame heat exchanger. The wort will be cooled by city or filtered water first and then glycol second. This allows better control of knockout temperatures and less water usage when water temperatures approach or exceed knockout temperatures.
- Flushing /sanitizing - Heavy hop and ingredient loads, together with poor trub separation in the whirlpool give rise to excessive cold break and potential plugging of the wort cooler. It is good practice to install the provision for reverse flush and CIP of the cooler and piping systems. The method of sanitizing the cold wort line and fermenter should also be considered during the design phase, and provide the flexibility you are looking for.
Efficient utilization of equipment is a concern in any brewery. Whether large or small: saving time means saving money. The heart of the brewery, the Brewhouse, holds the most opportunity for time savings. Not all suggested solutions require major equipment overhauls or purchases with the right equipment. Give Sprinkman a call or hit our “Request A Quote” section of the web site and we will help you improve your situation!