Automated beer blending; a brewery equipment manufacturer propounds the benefits of automated beer blending.
The blending of beer is an important stage in its production, particularly in the United Kingdom, where alcohol tax requirements make accurate blending an important cost-efficiency measure. It could be argued that blending is the single most important process in making beer, after fermentation. British brewers begin with heavy gravity beer and cut it, (typically from anoriginalgravity of 10/80 down to 10/32). Many brewers believe careful blending can produce up to 30 percent more volume from a plant, without affecting the taste or body of the final product. Clearly, accurate blending to precise alcohol or gravity levels optimizes the value of the beer produced, providing the brewery with the best possible utilization of labor and plant and the best return on materials used and power consumed.
Accurate measurement of flow is the heart of any blending system, and a flow ratio-based system with manual or automatic inputs of specific gravity or alcohol values is ideal for determining a calculated blend ratio for the desired final product.
The flow management of high gravity beer, carbonated liquor, returns and final blend should be accomplished with electromagnetic flowmeters. This type of flowmeter is accurate, non-intrusive to the process and easy to clean. The outputs from the flowmeters are fed into a control and display unit to provide instantaneous flow indication, totalization of batches and real-time values for calculation on a continuous basis throughout the batch blend.
There are a number of automated blending systems available today that are accurate, simple and cost-efficient. An example of such a blending system is produced by Taylor Instrument, a division of Combustion Engineering of Rochester, NY. The Taylor blending system meets the aforementioned criteria and it is capable of linking up with other plant areas (i.e. filtration, carbonation, chiller control and filling).
Control & Calculation
Under the Taylor system, the control of both carbonated liquor addition and beer returns is carried out in microprocessor-based MOD 30 controllers configured with an integral-of-error algorithm. This configuration provides a blend ratio of high accuracy because errors are measured, integrated and compensated for by instantaneous on-line controllers.
The setpoint (desired blend) is set by the blend calculations performed in a MOD 30 Sequence and Logic Unit (SLU). The SLU also provides totalization of all flows for both display and transmission to the operator interface unit or local control panel. The SLU has digital control capability to open and close product routing valves and sequence clean-in-place operations if required. This allows the combination of all blending and cleaning operations into one unit. If a target gravity meter or a percentage alcohol analyzer is used to continuously monitor these important parameters, the SLU's math capability integrates this signal into the system to trim the setpoint on the controller to provide continuous and precise control on-line.
Methods of Blending
It is advantageous for a blending system to provide a number of different blending methods. The Taylor Blending System, for example, can blend from a preset high-gravity volume to a present target gravity volume. Alternately, the system can blend continuously; blend to a percentage dilution from the high gravity volume; blend to a percentage dilution; blend from a target dilution; blend from mixed sources and to a preset dilution ratio.
When the operator selects the blend mode, the system initiates data request messages that flag the specific variables required for the selected blend mode. These variables can then be preset by the operator prior to starting the blending operation. Routing and clean-in-place operations can also be part of the total blend package when it is customized to suit a particular application.
Taylor's system incorporates a local control panel (LCP), that provides the necessary operator interface to the blending system. It has facilities to transmit or receive data on both the current and finished status of each blended batch.
The Taylor LCP has a five-inch monochromatic CRT and key pad to allow user personnel to read and input data. Data in both graphic and alphanumeric format on a number of predefined pages provides the manager, engineer and operator easy access.
Each operator display is easily selected through a single dedicated push button. The displays run through a title page to a dynamic display that shows the operator the preset and actual volumes of beer, liquor and blended beer, instantaneous flowing rates and running volumes.
Subsequent screens provide high gravity and target gravity values, together with the running blend volume. A blend mode data entry page allows the operator to enter the blend mode, blending data and stop, start and restart the blending operation.
If first and last runnings are used as part of the total blending operation, then a specific screen page is provided for the operator to use in setting both volumes and gravities. It also displays all the data needed for these two important phases of the blending operation.
Built-in inhibits prevent the start of blending operations unless data has been entered and the target gravity (TG) alcohol value is less than the high gravity (HG) value. Blending operations are also stalled unless the difference between high gravity and target gravity does not exceed a present limit. Once the conditions are met, the computer will display a variety of appropriate data, including HG, TG or alcohol percentage, HG volume required, TG volume, liquor volume required, percent dilution and the dilution ratio. When the operator decides to start blending, the soft key instruction is used.
The brewing industry has been capable of flow blending successfully for many years. Gravity and alcohol inputs have been based on laboratory samples taken at predetermined times to set and trim the blend ratio to provide the best possible blend accuracy. However, two assumptions made when blending this way can affect the actual final gravity alcohol count.
Alcohol content set into the system can be incorrect, either through operator or lab error. Second, the sample taken from the storage vessel may not be the average. When stored, beer can stratify by both density and alcohol content. In the U.K., these assumptions can create costly errors since tax is paid at one alcohol level and any value above this is given away in taxes and to the consumer. Errors below the desired level make it necessary to reblend to return to the minimum percentage of alcohol stated on the can. Consequently, breweries often err on the high side, in effect giving away money. For this reason, a gravity or alcohol percentage input from an in-line analyzer becomes very important because it can measure and trim the gravity/alcohol content continuously throughout the blending operation.
An example of such an analyzer is one developed by Process Analytics, a division of Combustion Engineering. Developed in conjunction with a major Canadian brewery, the Optibrew alcohol analyzer is based on a liquid gas chromatograph analyzer using a specially designed micro-liquid injection valve capable of injecting continuous samples of beer into the analyzer. It has full clean-in-place facilities.
Optimbrew provides a continuous reading of alcohol content from 0-6 percent with 0.02 percent repeatability and of carbon dioxide from 0-3 vols with 0.1 percent repeatability. It can be used as a stand alone unit or as a trim analyzer to a flow blending system to reduce off-spec beer, reduce or make beer returns or holding tanks obselete and enable a brewery to use all first and last runnings.
Automated blending systems can provide significant benefits for brewers who must adhere to precise alcohol levels. Automated systems can save time and increase brewery utilization, allowing brewers to increase profits - by saving on costs.
PHOTO : A recently installed brewhouse control system at John Smith's Brewery in Tadcaster, Yorkshire (above) uses a combination of Taylor Mod 30 instruments and Allen Bradley programmable logic controllers (PLCs). A Taylor local control panel (opposite page) provides an operator interface with the Mod 30 blending system. The CRT display can be configured to report any desired combination of values.
Ken Sullivan is applications manager for Taylor Instrument Europe. He recently ssisted in a brewery automation project at John Smith's Brewery, in Yorkshire, England.
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|Publication:||Modern Brewery Age|
|Date:||Jan 22, 1990|
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