Pumps & Systems, July 2013
Intelligent pumping is a growing trend across the water, wastewater, buildings and industry markets. The first challenge in developing an intelligent pump infrastructure is to focus on and understand how the intelligence, or automation, of a system improves overall system operation. Three primary options are the variable frequency drive (VFD), the programmable logic controller (PLC) and the human machine interface (HMI). Another challenge is to interface the different products and software support to integrate the system’s components so that they work together. Additional challenges are the programming complexity and the time required to develop pump-specific functionality.
Ideal Solution
The foundation of an ideal solution is a common software platform. End users want to:
• Reduce engineering, operations and
maintenance costs
• Maximize plant and production efficiency
• Improve production quality
• Reduce their energy footprint
• Improve the safety and security of their people, processes and property
• Optimize their operational budgets
Pump control solution providers want to bring products to market quicker. Original equipment manufacturers (OEMs) want to work with a control platform that is easily upgradeable, compliant with global standards and simple to implement. All suppliers of control platforms provide end users and pump control solution builders with PLCs and software designed for the process automation of standalone or system-control applications that require industrial control communications and input/output (I/O) capabilities. However, many suppliers are slowed by concerns regarding backward compatibility and by the extra effort involved in developing proprietary platforms and communication systems. This market approach can limit innovation and increase integration and purchasing costs for end users.
Innovative platforms take a different approach by embracing open architectures and technology and allowing end users and pump control solution builders to differentiate themselves at each stage of automation—from design and development to the implementation and maintenance of the machine or system. Ideally, these platforms reduce the complexity of the functions that are not specific to an OEM’s field of activity and allow OEMs to concentrate on their area of expertise. OEMs can then reduce spending and investment on design, installation and implementation.
Innovation for Simplicity
Companies should focus on innovation for simplicity, which means to reduce the system complexity to help end users perform their jobs in the best way. Because of evolving market options—including flexible and scalable hardware control platforms, ready-to-use architectures and pump control solutions—builders are able to design more energy-efficient and cost-effective solutions while maximizing performance. Additionally, the innovation for simplicity principle provides immediate benefits for the new architecture in which field devices are controlled across one machine network and programmed by a single software program.
This concept focuses on modernization and digitization across the production floor. When designing a pump system, a complete automation solution should be provided. These modern production infrastructures should be based on flexible and scalable hardware controller platforms that include PLCs, motion controllers, HMI controllers and drive controllers—all with embedded intelligence and extendable performance and open to standard networks. This allows end users to optimize their machine costs.
Pump control solution designers can benefit from reduced project development and production costs because the ready-to-use architectures can be tested by expert engineers, validated to be compatible with other automation components and documented to ease installation and commissioning. These pre-programmed features offer speed in developing generic or dedicated applications.
For an intelligent pump system infrastructure, pump designers should prioritize these control function blocks:
• Pump stage and de-stage—This function switches a combination of fixed and variable speed pumps to maintain constant pressure in a booster system. It maintains the pressure by switching between the pumps in the system, makes the system energy efficient by ensuring that the pumps operated by drives are given priority. The function also ensures smooth operation by checking the availability of the pumps and, if a fault is detected, switches to the next pump.
• Friction loss—This function compensates for friction by adapting the pressure set point according to the number of running pumps or the flow value (optional) in the discharge side. It also ensures a longer operating life by ensuring linear pressure in the system. This function can also generate alarms if it detects an abnormality in suction pressure curve, and it ensures that the pumps operate in an optimized state with the adaptation of the pressure set points.
• Proportional-integral-derivative controller—This function adjusts the set point of the variable speed drives to maintain constant pressure in a booster system. It maintains the required pressure by adjusting the set points, generates alarms in case of a deviation of limits and ensures smooth operation by maintaining the set points’ curve by avoiding damping.
• Cavitation protection—This function avoids the operation of the pump in during cavitation by stopping the pump. This ensures a longer pump life. The function generates alarms if cavitation is detected and ensures that the pumps operate optimally with the adaptation of the set points.
• Auxiliary pump—This function controls the auxiliary pump to maintain water pressure during night/sleep mode with alarm monitoring. It detects when these pumps need to operate to optimize efficiency and increases the energy efficiency of the system by operating smaller pumps to maintain lower flow.
Intelligent design, the interoperability of control solutions and the pre-programmed pump-specific functionality simplifies system design and reduces time to market. P&S