Sustainability Starts with Understanding System Power Cost

Piping systems represent a major asset in facilities in the industrial, municipal, and commercial markets.  These systems are expensive to design, build, operate, and maintain and their efficient operation has a major impact of their financial success and associated sustainability initiatives.  Optimizing the performance of  these systems over their life cycles also requires a variety of people with technical and financial disciplines to work together. 

In this blog, we will see how PIPE-FLO’s new System Power Cost functionality offers financial and equipment usage insights into the operation of fluid piping systems. 

A Measurement We All Can Understand

As a member of the ISO/ASME Pump system assessment 14414 standard, we were tasked with developing a method for assessing a pumping system.  The assessment considered the entire pumping system from energy inputs to the work performed.  The primary goal was determining the current energy consumption and identifying ways to improve system efficiency.  Since the results were evaluated by a team of diverse technical and financial people, it was difficult to get everyone onboard.  We didn’t have a way to present the results that were meaningful to everyone concerned. 

PIPE-FLO simulates how the system operates, but the results are presented in a variety of engineering units, such as head, pressure, horsepower, kiloWatts, capacity, etc.  While teaching a Piping System Fundamentals class, I realized that we needed to present the results in an easy-to-understand set of engineering units.  Instead of using abstract units, the results could be presented in the units of power cost.  The electrical power used to power the motor is based on the motor load and hours of operation.  This allows the results to be standardized to dollars per unit of time. 


I’ll demonstrate using a small open loop system with a single pump as an example (figure 1).  This system consists of a supply tank, a pump, a heat exchanger, a flow element, a flow control valve, and a destination tank. The drawing shows the calculated values for the installed instruments, specifically the level and pressures in the tanks, the pump suction and discharge pressures, the flow rate, and the corresponding position of the control valve. 

This provides plant operators with the information needed to operate the system, but provides only limited insight on how efficiently the system is operating and nothing about the operating cost.    

PIPE-FLO’s calculated results (figure 2) show how the energy is used within the system.  The flow rate through the system is set to 400 gpm, based on the set point of control valve ST1-1-FCV1.  The flow rate through the pump produced 204.7 feet head, with an efficiency of 51% based on the pump curve, and requires 43.79 horsepower into the motor shaft. 


Via PIPE-FLO’s calculated results, we can see the energy supplied by the pump and observe the losses associated with the process and control elements.  We can also see how much power is supplied to the pump to provide the required flow rate, along with the pump efficiency.  Notice the head loss across the heat exchanger and the head loss across the control valve needed to maintain the required flow rate.  Finally, you can see that the difference in static head that must be overcome for the system to work. 

Looking at the results, you can see that only half of the power supplied to the pump is used to move the process fluid through the system.  Approximately 40% of the power supplied by the pump is consumed by the control valve. 

What To Do About It

This presents two additional questions: how much does the current system cost to operate, and what can be done to minimize the operating costs? PIPE-FLO v17.5 features a new System Power Cost capability designed to address those questions. 

By entering the local cost of electrical power, and the length of time for system operation, PIPE-FLO calculates the cost to operate the pump element and the operating cost of each item of equipment in the system.   Figure 3  (below) shows the power cost for each item in our sample system.  In this example, the power cost is $.10 / kWhr, the cost is an annual cost, and the system is operating for 100% of the evaluation period. 


With the dissipated power and cost values displayed, everyone can access the financial insight into system operation.  Notice that the pump has an annual input power cost of $28,618; of that, only 51% of the power is used to move the fluid through the system.  We can also see dissipated power, along with the dissipated power cost, for each item in the system.  Notice that the flow orifice ST-1-FE1 consumes 1.04 kW of power and costs $912 in annual operating costs.  Furthermore, control valve ST1-1-FCV1 consumes 6.58 kW of power, with an annual operating cost of $5,766 per year, to limit the flow rate to 400 gpm. 

With this financial insight, everyone can see how much it costs to operate the piping system, and how much power and associate costs is consumed by the pump based on its efficiency. 

Now, to answer the second question: What might be done to reduce or minimize operating costs?

Using the computational power of PIPE-FLO, a new and more efficient pump, possibly with a Variable Speed Drive, can be inserted into the model to simulate system operation along with savings in operating cost. 

The values and savings can be documented using PIPE-FLO’s new System Cost Report with pie charts, along with a listing of the pump input and output power and with the dissipated power cost for each item in the system (figure 4).

Summary & more

Using PIPE-FLO’s System Power Cost feature provides clear and actionable financial and sustainability insights on fluid piping systems. Insights expressed in “dollars and cents” terms that will resonate throughout an organization.

Ready to KNO more about your system power cost? You’ll need to be on v17.5 of PIPE-FLO to access the System Power Cost analysis feature.  You’ll find information on how to download it here.

Watch this video for more details on the System Power Cost functionality in PIPE-FLO.

Ray Hardee P.E. stamp

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