Considering a Feed System Upgrade?

Fully integrated systems bring reliable, performance-based chemical feed to critical water and wastewater applications

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For most facilities today, the only constant is change. Managers, facility engineers and maintenance supervisors, swamped with improvement initiatives brought about by ever-increasing competitive pressures, must continuously search for new ways to make improvements in the efficiency and reliability of their plants' processes and systems. Compounding this challenge is the fact that typically far less human resources than ever before are in place to address these initiatives.

Facilities also are facing increased pressure to improve performance in chemical delivery, control and monitoring.

Chemical feed and control essentially entail the introduction of chemicals into various processes at desired ratios to maintain system integrity such as the mitigation of biological fouling, deposits or corrosion. Once you get past the concept stage and proceed to the real world, however, chemical feed becomes far more challenging and complex. However, the area is ripe with opportunities for plants to gain significant performance advantages.

Automation, reliability, optimization & safety

Facilities are updating their chemical feed systems primarily to gain four key advantages: automation, reliability, optimization and safety.

The adoption of automation is proliferating as the result of the decade-long trend toward downsizing. Without the necessary human resources to monitor, analyze and adjust chemical feed rates, facilities increasingly are compelled to adopt ," and trust ," automation. This reality, coupled with advances in microprocessor technology, has driven the development of better, more user-friendly and more affordable automation for even highly customized chemical feed applications.

Paramount to the advancement in automated chemical feed has been the development of and improvements in real-time analyzer technologies. The ability to continuously measure the performance of a chemical being fed and to automatically adjust feedrate appropriately has brought process optimization in the form of performance-based chemical feed control. Only a few years ago, a facility and the water treatment company serving it relied heavily on quantity-based chemical feed control with periodic dosage adjustments. Facilities now have a greater ability to modulate the precise amount of chemical automatically to meet ever-changing system requirements continuously.

Today's automation capabilities help to avoid or minimize damaging events, extending equipment life. Automation also is allowing neat chemical feed in many applications, thereby reducing chemical handling and maximizing operator safety. Plus, control automation and real-time analyzer technologies now facilitate the logging of comprehensive historical chemical usage and pertinent application data to assist the plant with troubleshooting and cost optimization.

 

To develop new automated feed and control systems, critical understanding of key chemical processes and automated chemical process control is essential.

Re-thinking who does what

As facilities strive to adopt automation and increase reliability, optimization and safety, facility management must re-think the design and procurement process for acquiring these increasingly sophisticated systems. To meet new performance criteria, chemical feed and control systems must be designed and built to meet the specific needs of each application precisely.

But at what cost? Long gone are the days when the required chemical feed expertise rarely extended beyond the boundaries of a pump. Substantial application knowledge is now required to facilitate the needs and requirements of the plant owner, its engineering, procurement and construction (EPC) firm (for new construction), and the plant's water treatment firm. Feed and control systems not only must meet the interfacing requirements of the plant, but also must deliver the types of chemicals at the precise feedrates required by the water treatment firm to meet specific performance criteria while operating within water treatment budgets.

Plants usually issue a specification for chemical feed equipment, and this spec typically contains numerous line items such as pumps, back pressure valves, manual valves, piping, etc. In the past, many plants possessed the in-house resources necessary to manage and coordinate the efforts of a contractor to integrate all these components on-site. Or, in some cases, plants elected to build chemical feed systems in-house.

Today, these approaches might not result in the most efficient chemical feed and control system. Plants and EPCs often must maintain constant focus on the "bigger picture" items such as turbines and process pumps that represent millions of dollars; therefore, it can be difficult to provide dedicated resources and experience for the various small chemical treatment systems that will serve the plant. What is needed today is a way to efficiently shift these burdens away from the plant and the engineer and toward specialists who can facilitate the connection between water treatment application needs and feed system design.

Custom packaged feed systems

Increasingly, facilities are using custom packaged chemical feed systems. Here, the solutions provider designs the entire system specifically for the application and builds it off-site.

After the "modular" system is thoroughly tested, it then is delivered to the plant on a skid. Electricity is established and plumbing connected, and interface connections are made to the plant's distributed control system (DCS) at a junction box (or, depending on the needs and capabilities of the plant, the packaged feed system is designed to include local automated control with wireless interface capabilities).

Although packaged chemical feed skids long have been available, their use was more limited until relatively recently, partly because few companies possessed the necessary skills to provide fully integrated packaged systems. Although some pump manufacturers provide packaged systems, the resulting systems often are not designed with an understanding beyond the boundaries of the pump. However, several full-service packaged system providers have been established over the past several years to meet the need for optimized, site-specific chemical feed solutions.

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