Date of Graduation

5-2022

Document Type

Thesis

Degree Name

Master of Science in Biological Engineering (MSBE)

Degree Level

Graduate

Department

Biological and Agricultural Engineering

Advisor/Mentor

Osborn, G. Scott

Committee Member

Liang, Yi

Second Committee Member

Morawicki, Ruben O.

Keywords

Craft beer; Carbonation; Craft brewing; Engineering; Seltzer

Abstract

The patented Carbo Rock-It system was developed to carbonate beverages for the craft brewing industry with the goal of reducing time, cost, and environmental impacts of the carbonation process. This research field tests, models, analyzes and optimizes the engineering and economic performance of a commercial-scale Carbo Rock-It placed in production at an operating brewery (Core Brewing and Distilling Co., Springdale, AR). Field tests indicated that the Carbo Rock-It was able to successfully carbonate twelve 120 BBL batches of Scarlet Letter Seltzer to 3.0 vol/vol while meeting all beverage quality and safety requirements. The Carbo Rock-It was able to reduce carbonation time from 72 hours to 6.5 hours on average while reducing the amount of CO2 gas required compared to the existing carbonation system. A hydraulic model accounting for all pressure losses through the system at varying beverage flowrates was created and validated against pressure measurements. The greatest error and sensitivity of the model was predicting the pressure loss through the two nozzles. Performance of the system was optimized by measuring the carbonation rate and percent saturation achieved by the unit when operated at varying equipment setups then determining setup that provided the fastest carbonation and greatest profit. The equipment setups tested were: gas injection location on the saturation tank (into the liquid pipe before the nozzle and directly into the gas headspace); and the diameter of the nozzle injecting beverage into the saturation tank (5/16” (7.9 mm), 21/64” (8.33 mm), 3/8” (9.5 mm), and 5/8” (15.9 mm)). Gas injection location had no effect on system performance. The optimal nozzle diameter was established by determining the carbonation rate and profit using Zahm and Nagel dissolved CO2 measurements. After statistical analysis, it was determined that the 21/64” orifice had the highest carbonation rate and percent saturation followed by the 5/16”, 3/8”, and 5/8”. The carbonation rate and percent saturation for the 21/64”, 5/16”, and 3/8” orifices were not significantly different at α = 0.05 and 0.10. The 21/64” orifice had the highest carbonation rate (215.41 g L-1) and percent saturation (46.6%) with the shortest operating time (6.24 hours) and cost. This was followed by the statistically similar 5/16” (178.74 g L-1; 37.3%; 6.53 hours) and 3/8” (176.74 g L-1; 35.2%; 6.78 hours) orifices. The 5/8” orifice was statistically different from all the others (96.79 g L-1; 16.9%; 13.37 hours) at α = 0.10 and only statistically different from the 21/64” orifice at α = 0.05. The economic analysis compared the operating costs to carbonate 12,000 BBL per year for each orifice size and the standard forced carbonation method typically used in craft breweries. This analysis showed that the Carbo Rock-It creates annual operating cost savings of approximately $4,500 regardless of orifice size. Additionally, the 10-year Net Present Value (NPV) for the 21/64” ($4,285,995) and 5/8” ($3,194,275) orifices were compared to that of standard forced carbonation ($3,212,775). The increased carbonation rate of the 21/64” orifice allowed for 35 additional batches per year thus increasing the NPV significantly.

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