Frequently Asked Questions (FAQ)

Beer brewing

• What are the basic components of a brewery?

• A brewery can be divided into two parts: the brewhouse, where all the brewing is done, and the fermentation area, which consists of fermentation and maturation tanks. In order for the brewing process to run smoothly, you also need hot water and cold water tanks. Hot water is used to rinse the malt (lautering), while the cold water is needed for the process of wort cooling using a plate heat exchanger.

  The brewhouse consists of a mash mixer, a lauter tun, a kettle, and a centrifugal separation tank (whirlpool). The processes can be carried out in separate process tanks, or you can purchase a brewhouse with a smaller number of combined tanks, which are adapted so that different phases of the brewing process can be carried out in them.

  Read more about how to start your own brewery.

• How is the brewhouse installed and who can do it? What about the first use?

• The brewhouse installation site must be prepared beforehand: you must arrange all necessary supply connections (water, steam, glycol, electricity). All work must be performed by properly qualified personnel and in accordance with the provided instructions.

  You can start brewhouse operation on your own or you can ask SK Škrlj to help you with it.

• Is the system manual or automatic?

• All systems are semi-automatic with individual automated functions. This means that the presence of an operator / brewer is essential. Process control is carried out using the main touch screen control panel. The control panel enables you to regulate the temperature inside the tanks, the mixer and pump speed, as well as to set the timers, the step mashing program, etc.

  All brewhouses except the MB series have manual valves. Only the step mashing program and heating to the desired temperature are automated, while the timers turn off individual functions, e.g. boiling or whirlpool.

• Do I have to buy any additional equipment to be able to start brewing?

• Each brewhouse system includes a process pump, a heat exchanger, and pipe connectors, and it is equipped with a touch screen control panel for process control and a complete electrical wiring system. Some models also include a hot water tank, while with others it has to be purchased separately. Beer fermentation and maturation tanks are also extremely important for the brewing process - you can order them according to your own needs or depending on the desired capacity of your brewery (more here).

  All brewhouses, with the exception of the standard BHM250 and BHM500, which are heated with oil, require a suitable steam generator for heating and a sufficient amount of water, which is used for the purposes of the brewing process (wort cooling). There is also some additional equipment that can be important for system operation: a malt mill, wort and beer transfer pipes, a mobile pump for liquid flow and equipment cleaning, a CIP station, a grist case, a malt conveyor, and a cooling unit for fermentation and maturation tank cooling.

• What about hot water? Do I need an extra hot water tank?

• A hot water tank may be part of the main brewhouse system or it has to be purchased separately, it depends on the model. You can see a detailed description of our different brewhouse systems here.
  

  We advise you to purchase a hot water tank with a volume that is at least twice the nominal volume of the brewhouse (the size of one batch). This way, the hot water will always be ready, even if you are preparing several batches in a row.

• How are the water tanks controlled?

• The water tanks that are part of the brewhouse system (established pipe and electrical connections, built-in pump) are controlled via the main control panel of the brewhouse. The control panel is equipped with a touch screen and its user interface is available in multiple languages.

  The user enters the desired temperature into the program and then presses the suitable button to activate water heating or cooling. The process is deactivated automatically when the desired water temperature is reached.

  The pump is also controlled using the main control panel - it enables you to activate/deactivate a tank's pump and to also set a pump cycle. In this case, the pump of the selected tank is activated automatically: it alternates between pumping and pause in accordance with set time parameters.

  The control panel also displays current water temperature and flow, as well as the total amount of water pumped.

• Which heating medium is used?

• Heating is carried out along the tank wall and on the bottom, where the heating medium flows through the double jacket and, consequently, increases the temperature inside the tank.

  The heating medium used in most of our brewhouse systems is steam. The standard models of our smaller systems (BHM250 and BHM500) use thermal oil, but steam heating is available as an alternative. If the brewhouse is heated with thermal oil, the basic system includes a heater, a pump, a manifold, and a control unit.

• In what way and how fast is wort cooled? What is the cooling medium?

• Wort cooling is carried out using a heat exchanger. The wort enters the plate heat exchanger at a temperature of approximately 100 °C. Due to the interaction between the hot wort and the cold cooling medium inside the heat exchanger, the wort temperature gradually decreases, while the temperature of the cooling medium increases.

  The brewhouse can be equipped with a single-stage or two-stage heat exchanger. If the brewhouse is equipped with a single-stage exchanger, the only cooling medium used is cold water, which is stored inside a water tank and used later on in the process. However, if there is a two-stage heat exchanger, both cold water and a water/glycol solution (cooling manifold) are used for cooling. Find out how to choose the right heat exchanger here. The heat exchangers are dimensioned so that all the wort is cooled in 45 minutes (on average).

• How many batches can be completed in one day?

• The number of batches you can make in one day depends on brewhouse configuration and the recipe you use. With our brewhouses, you can complete 4 to 11 batches per day, as they are designed in such a way as to enable a simultaneous execution of multiple processes. This means that you can, for example, start mashing malt for a new batch before you've transferred the wort from the kettle to the fermenters (knockout). Consequently, if multiple processes are executed simultaneously, cycle time becomes significantly shorter.

  Another factor to always take into account is the total capacity of the fermenters and maturation tanks at your disposal. You can only make as much wort as you are able to store, as beer needs 3 to 4 weeks to mature (depending on the type).

  Read more about our brewhouse and microbrewey capacities here.

• How are the brewhouse and other tanks cleaned? Do I need a CIP station?

• Quality beer requires perfect hygiene during each production process. The brewhouse and tanks must be thoroughly cleaned after each use. In order to prevent product contamination and an unwanted aftertaste, it is extremely important to thoroughly clean the inside of the tanks and pipe connections, as well as any other part of the system that may have come into contact with the product during the brewing process.

• How to clean a brewery?

• The brewhouse and tanks must be thoroughly rinsed with water to wash away any larger dirt residue. The entire system is then cleaned with a cleaning solution, which is prepared in accordance with the manufacturer's instructions and pumped between the tanks using a pump and flexible pipes.

  Suitable cleaning and disinfection products, as well as other cleaning equipment for breweries are available in specialized shops. They must be suitable for use on surfaces that come into contact with food and beverages. After cleaning, the entire system must be thoroughly rinsed with clean water.

• What is the max. allowable temperature of the cleaning solution used for CIP cleaning if the tanks are insulated with polyurethane foam (PU)?

• If a tank is insulated with polyurethane foam, do not use cleaning solutions at temperatures above 85 °C during CIP cleaning. The temperature can otherwise rise up to 120 °C for a short amount of time (few minutes). Prolonged exposure to high temperatures can lead to insulation material inflation and tank deformation. Prolonged use of a cleaning solution at temperatures up to 85 °C does not damage the insulation material

• Cleaning and disinfection with CIP (Clean-In-Place) technology

• The CIP station is not part of a brewery's mandatory equipment, but it is definitely recommended to have one. The CIP process is the most effective way to remove accumulated dirt and sediment from tanks, pipes, connectors, and other equipment that is connected to the system.

  The advantage of CIP cleaning is that it enables equipment cleaning and disinfection without system component disassembly.

  Read more about CIP technology here.

• Is regular service necessary? How are service and support arranged (in other countries), if there is a malfunction or if something needs to be repaired?

• A user manual is available on our web page and it also includes product maintenance and cleaning instructions. Spare parts are available at SK Škrlj, they can be delivered in a few days.

  Regular servicing is not necessary. Our trained personnel are available for remote assistance if there is a malfunction, and, if necessary, can also pay you a visit and solve the problem.

Industry

• What is the max. allowable temperature of the cleaning solution used for CIP cleaning if the tanks are insulated with polyurethane foam (PU)?
• If a tank is insulated with polyurethane foam, do not use cleaning solutions at temperatures above 85 °C during CIP cleaning. The temperature can otherwise rise up to 120 °C for a short amount of time (few minutes). Prolonged exposure to high temperatures can lead to insulation material inflation and tank deformation. Prolonged use of a cleaning solution at temperatures up to 85 °C does not damage the insulation material.

Extraction

• Does the presence of water in the material influence the extraction process?

• If the material to be extracted contains any water, it will have a negative effect on the extraction process, as the extract will then also contain water, which has to be removed with additional processing steps. In order to avoid this problem, it is recommended that the material be dried before extraction.

• Can CBD be obtained with supercritical CO₂ extraction?

• CBD (Cannabidiol) is just one of the components of the full spectrum oil product that can be extracted from the matured flowers of the Cannabis sativa plant. In addition to CBD, which is the major nonpsychotropic constituent represented in the highest concentrations, the extracted full spectrum product also contains a mix of natural components such as other cannabinoids (CBN, CBC, CBG …), terpenes, and other molecules. All these components incite a broad range of effects on the receptors of the ECS endocannabinoid system in the organism.

• What type of solvent is CO₂, polar or nonpolar?

• CO₂ is nonpolar, therefore it is the best tunable solvent for the extraction of oils and fats. Due to its nonpolarity, it is a very effective solvent for lipophilic substances such as triglycerides (vegetable oils and butters), essential oils, and lipophilic vitamins. On the other hand, water is very polar and deemed as the most “universal” solvent in nature.

  Solubility is usually explained with the saying "Like dissolves like", which means that nonpolar reactants will dissolve in nonpolar solvents and polar reactants will dissolve in polar solvents. Intermediate solvents such as ethanol, methanol, and acetone are used for tuning the solubility power. The dielectric constant of a solvent is a measure of its polarity (symbol: ε). The higher the dielectric constant of a solvent, the more polar it is. By adjusting the pressure and temperature set point, we can simulate the density and solubility power of different organic solvents, ranging from chloroform to methylene chloride to hexane.

• How does the extraction process with supercritical CO₂ work?

• Extraction with supercritical fluids is a multistage separation process where one or multiple components are separated from the matrix using a supercritical fluid as the extracting solvent. In the initial phase, liquid CO₂ is pumped through a heat exchanger and into an extraction vessel using a high-pressure pump. In the heat exchanger, the CO₂ enters the supercritical state under a controlled set pressure and temperature. The supercritical CO₂ then passes through the extraction vessel which has been pre-filled with dried and crushed plant material. During the extraction, the supercritical solvent passes through the plant material and dissolves the soluble compounds. The pressure in the extraction vessel is maintained using a PLC-controlled pressure regulator. A mixture of solute and supercritical fluid is transferred to the collection vessels where the pressure is gradually relieved. By lowering the pressure, the dissolution power of CO₂ gradually decreases and the dissolved compounds (fractions) are consequently separated from the solvent. Finally, the pressure in the system is reduced, the CO₂ returns to its gaseous state and has no power to dissolve. It is then cooled again and liquefied in a gas recycling system from where it returns back to the process.

• How do I know if my Supercritical CO₂ Extraction system investment idea is feasible?

• An economic evaluation based on a detailed profitability analysis showed that SFE is an economically feasible process, as it disclosed the encouraging values of return on investment (ROI) and net present values (NPV) for all scale-up capacities. Hence, the kinetic study for the SFE process by using mathematical modelling on overall extraction curve (OEC) of laboratory-scale data is crucial. However, many cases on increasing the scale from laboratory to the industrial level showed a significant decrease in extraction yield. Hence, an intermediate-scale experiment (pilot scale) was a better strategy because it considered the restriction that might occur on the industrial-scale. This way, the laboratory-scale data could be safely utilized to develop the economic evaluation for the SFE process, in which the process tendency is to sustain the extraction yield with increasing scale. According to Pereira et al., the most reported drawback of SFE for the past 20 years was a high initial investment cost on industrial plants. SFE was considered too expensive by many investors because of the high investment costs compared to conventional low-pressure equipment. Therefore, the use of this technology for high-added-value products was restricted. However, if considering the use and quality of its product, the operating costs of SFE were relatively low.

• How is the extraction process carried out?

• In order to ensure the best yield of extraction, it is imperative to carry out several sample/material preparation steps of pre- and post-extraction techniques that can help improve the extraction yield and refine the final product. After CO₂ is pressurized to a supercritical state, supercritical CO₂ is passed into the extraction vessel containing the loaded and shredded plant material. The supercritical CO₂ acts as a solvent diffusing into the plant matrix and dissolving the target compounds. The solubility of different compounds in supercritical CO₂ varies based on factors such as pressure, temperature, and the chemical properties of the compound. Selective extraction can be achieved by adjusting the pressure and temperature. Lowering the pressure leads to the extraction of volatile compounds while raising the pressure can improve the extraction of less volatile compounds.

  A higher temperature boosts the extraction of less volatile compounds and improves the solubility of certain compounds but it has to be controlled in order to avoid thermal degradation.

  The hemp post-extraction process usually consists of four steps: winterization, filtration, evaporation, and further refinement, such as chromatography.

  https://sk-skrlj.com/en/extraction.

• How efficient is the extraction process?

• We usually measure and express the efficiency of the extraction method with yield. The yield of any extraction process depends upon the quality of the original source material (matrix). For example, different cannabis strains show different cannabinoid profiles and produce specific levels of CBD.

• What are the advantages of SFE compared to traditional extraction methods with organic solvents?

• The extraction process with supercritical CO₂ is very fast compared to traditional methods and very economical to operate/run. There is only a small amount of organic solvent used for the cosolvent extraction or in most cases none at all, which results in practically no solvent residue. This method is known for perfectly preserving thermally labile compounds. CO₂ as a solvent is easily tunable and can be used very efficiently for a broad range of selective extraction tasks. Due to its great selectivity, the targeted compounds can be extracted out of complex matrices. It is possible to conduct a selective extraction by tuning the pressure and temperature in a way that preserves the volatiles and the thermolabile molecules. Additionally, the closed-loop system used in supercritical CO₂ extraction minimizes the release of CO₂ into the atmosphere.

• What process parameters are controlled during the extraction process?

• The extraction process is controlled using an integrated PLC system where the parameter settings are presented graphically on the touch screen. The process parameters such as temperature, pressure, flow, extraction time, and S/S ratio are set and stored as a method (recipe) that enables reproducible operation.

• Under what conditions will CO₂ reach the supercritical stage?

• Carbon dioxide (CO₂) enters the supercritical fluid state at its critical temperature of 31.1 °C and relatively low critical pressure of 72.8 bar.

• How much CO₂ is used and how much of it is lost during the extraction process?

• In modern extraction systems, equipped with a recycling vessel, CO₂ recirculation is continuous. In theory, this process can run indefinitely.

• What is the main advantage of supercritical CO₂ as a “green” solvent?

• CO₂ is an inexpensive and readily available so-called GRAS (generally regarded as safe) solvent that is very easy to recycle and reuse. By using CO₂, we can avoid the use of other solvents and as a consequence the need for solvent waste that require special environmentally hazardous and costly waste treatments like special incineration facilities.

  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6152233/