Food & Beverage manufacturers are always looking for ways to become leaner and reduce costs. When project teams are designing plant utility systems, they are focused on minimizing up-front installation costs to meet budget requirements, sometimes at the expense of much larger long-term operational costs.
Pumps are one of the biggest capital and operating costs in any hydronic system. In most cases, rules of thumb and spreadsheet-based calculated estimates are used to evaluate pipe system pressure-loss based on target fluid flow rates. Pumps are then selected based on manufacturer-provided pump curves or test data. This process often results in less than optimal system pump performance, including increased pump casing size, pump motor size and energy consumption. While the larger pump selection will usually satisfy minimum plant heating or cooling production needs, there can be significant savings and results delivered using a smaller size pump by modeling the entire hydronic system using modeling software. Let’s take a look at a real project example and the benefits of pipe modeling.
Case study
A client built a milk processing plant with a 400-ton chilled water system. After a few years of operation and several small chilled water system expansion projects, the client was experiencing a shortage of chilled water to some critical process cooling loads in the facility. Mead & Hunt was hired to provide system improvement recommendations and model the system, including every pipe segment, pipe fitting, control valve and heat exchanger. The system was modeled, and a couple piping bottlenecks were discovered in the distribution piping system. These bottlenecks were replaced, and the client avoided substantially larger pump replacements. This not only prevented the extra costs of larger pumps, but reduced the long-term energy consumption of the system. As an added bonus, the system was easier to flow balance in the field.
Lessons learned
Using software to analyze these complex systems allows us to look at the entire system and pinpoint where operational cost savings can be made. With larger systems, cost savings can be tremendous; however, smaller hydronic systems should not be neglected. Increasing the pipe size in a short pipe run can reduce the required power of the pump. In one instance Mead & Hunt encountered, by increasing a pipe run from one inch to two inches on a hydronic system, we were able to reduce the pump head almost 40%, resulting in significant long-term cost savings to the owner.
Hydronic systems are commonly designed to have the highest pressure-loss through the equipment furthest away from the pump. Although not intuitive to some designers, this actually allows the designer to reduce pipe sizes to loads closer to the pump, reducing project installation cost. This does not happen when designing a system based on rules of thumb.
As energy costs continue to rise, working to lower mechanical utility system operating costs as much as possible is critical to a food plant’s bottom line. Whether you are planning on putting in a new system, adding additional users to your existing system or would just like to know how your system is operating to minimize capital and ongoing operational costs, computer modeling of your system can be very beneficial.
