During the design and construction of new industrial plants, all pumps are selected based on theoretical system hydraulics.
The system's mathematical models were developed using manual calculations. Today, software is used to design plant operating conditions for a nominal rated output with consideration for expected minimum and maximum production rates. This predicted system information is used to specify pump performance and is reflected in data sheets.
When older plants were designed, many factors that contributed to problematic operations were unknown. Minimum continuous stable flow or suction and discharge recirculation was first observed in the late 1970s. Many pumps still running at plants nationwide were built before that time and don't include measures developed to counteract these latent issues.
Even when a plant unit is accurately designed with pumps matching the original specification, changes during the life of the plant result in the pump being sized incorrectly. Most industrial complexes have experienced changes that affect the performance required from the pump, such as higher or lower production rates, different product specifications, new feedstocks, changes in operating philosophies, stricter safety or environmental regulations and aging systems. Any of these changes, plus myriad more, would result in an incorrectly sized pump.
When looking at total pump life, the consequence of changing performance requirements without considering resizing the equipment to match the new duty point is significant. The once reliable machine now frequently fails and is not easily diagnosed or remedied. End users may implement a "Band-Aid" solution - ensuring there is a complete spare pump at the warehouse, if needed, to keep the unit running. This "solution" may not impact the maintenance budget, but doesn't alleviate the sharply increasing total cost of equipment ownership.
When a persistent problem is reaching the tipping point, naturally one would buy a new pump. This may seem like the easy answer, but it is rarely the solution. The final cost of the project - both time and money - can be much higher than originally anticipated. The fact is, newer pumps rarely fit as a one-to-one replacement. A replica is extremely expensive and delivery could take over 48 weeks. When retrofitting a pump with a new footprint into an existing system, costs increase again for the system modification and a plant shutdown needs to be scheduled for implementation of the system changes.
Another approach would be to re-engineer the existing machine to change the design point to meet the new rated conditions. Taking it a step further, hydraulic performance modifications can be made to best suit the operating window, resulting in significant increases in pump reliability and energy savings.
Hydro has developed a rigorous process to solve pump sizing issues by re-engineering existing equipment. First step: Reverse engineering of the existing pump geometries (these critical dimensions are captured and transformed into 3D computer models). Captured information is then analyzed by experienced professionals using computational fluid dynamics software and other traditional methods. Analysis produces new predicted pump performance based on changes to the impeller design and pump internal geometries.
Once the proposal is reviewed and approved by the end user, all manufacturing drawings are created, the Hydro parts are assigned, bill of materials are drawn up and casing modifications are verified. Modifications and manufacturing of new parts, including cast parts, are done in-house by Hydro's dedicated aftermarket service centers.
Final step - prove the new hydraulics in a controlled environment. Hydro provides certified performance testing at its Hydraulic Institute, a certified state-of-the-art test lab in Chicago. After ensuring the modified equipment meets the expected hydraulic and mechanical performance, the test lab issues new certified performance curves for the equipment.
Incorrect sizing can greatly affect reliability, production and ultimately, profitability. Plants need not live with incorrectly sized equipment. Problems can be easily identified and corrected. Hydro can help.
For more information, visit hydroinc.com or call (832) 720-8691.
