A technology that is growing in acceptance for use in industrial applications like water/wastewater treatment and boiler feed that require the injection of chemicals is a complete range of feeder types and styles. Namely, these feeders combine the ability to inject various water-treatment chemicals with the capability of performing high-capacity filtering of the rust, corrosion, scale and coagulated solids that are produced in one piece of equipment.

The leading benefit of using a feeder is its ability to protect against harmful particles and debris due to the use of a filter bag that can trap contaminants rather than relying on inefficient and unreliable strainers or dirt/air separators. While 60- to 90-mesh screens can intercept larger particles, today’s filter bags have been designed to capture impurities that can be as small as one micron, which is five times smaller than the width of a human hair. “Neptune recommends using medium sized bag such as a 20-micron bag to start out filtration. Then upon inspection, determine the required change in filter bag’s micron size either smaller (1 OR 5 micron) or larger (50 micron) based on the initial inspection with a 20-micron bag.” said Gurmeet Kharbanda, Director Product Management – Neptune

Another benefit of the filter bag is that when it becomes full it can be removed from the feeder and thrown away, meaning that all of the solid particles that have been captured are disposed of and not recirculating through the treatment system. This makes feeders a convenient way to introduce solid or liquid chemicals into the process with the added ability to filter out contaminants that may harm the overall performance of the system or its sensitive components.

As with all technologies, operators must perform their due diligence before they are able to determine which technology to specify for the particular application. Neptune aids in the search by offering three types of feeder technologies:

• By-Pass and Filter Feeders: Designed to be a convenient method of introducing solid or liquid treatment chemicals into closed-loop water-recirculation systems. As such, they are ideal for treating chilled and hot closed-loop systems that are commonly used in heating and air-conditioning, process heating and cooling, and large-engine water jacket applications. They are offered in two vertical styles: with dish bottom in and with dish bottom out. Both styles feature a high-capacity cap that is rated to 300 psi (20.7 bar) and is designed for quick-opening, high-pressure closure for better tool-free sealing. Since the pressure binds the cap tightly to the feeder, it is necessary to bleed pressure from the tank before the cap can be removed.
• Bromine Feeders: These units are an easy and convenient way to properly feed solid biocides or other corrosive water-treatment chemicals. They are compatible with most abrasive chemicals due to a corrosion-resistant vinylester-resin body that is superior to standard steel tanks when shot-feeding chemicals. The top opening is threaded with a gasket closure, while the inlet and drain connection are located on the bottom of the tank. They can produce and maintain flow rates ranging from 2.5 Lbs. (11 kg) to 230 lbs. (104 kg) per day at maximum pressures of 150 psi (10.3 bar) and temperatures up to 150oF (66oC).
• Glycol Feeders: These feeders have been designed to facilitate the addition of a glycol solution to closed-loop chilled or hot water systems. Pressure is maintained in the system through the metered addition of glycol that makes up for any losses that may occur due to leakage. A pressure switch that has adjustable high and low set points controls the addition of glycol. When the pressure reaches the low set point, the pump begins to feed glycol until the high-pressure set point is achieved, which halts pump operation. The frame-mounted polyethylene tank holds 50 gallons (189 liters) of glycol.

Chemical injection is a critical operation in water/wastewater and closed-loop treatment systems, with feeders moving to the fore as a first-choice technology in the optimization of these applications.