The De Nora blog: Water Made Easy

Can innovation be achieved with a tried-and-true disinfection technology?

Jul 2, 2020 8:21:00 AM / by William Stimeling

Since chlorine technology was first used in the US to disinfect drinking water in Jersey City, NJ, in 1908, most waterborne diseases have been eliminated in the U.S. Chlorine is still the most common disinfectant for drinking water and wastewater. Chlorine is also used for disinfection and as a biocide in numerous industries.


De Nora is a global manufacturer and supplier of electrochemical solutions for various industries. Water Online interviewed William Stimeling, De Nora Product Technology Manager-Gas Feed and Chlorine Dioxide, to learn more about gas chlorination.

Q: For which applications are gas chlorine best suited? Why?

A: Chlorine gas has been in use for over 100 years. The vacuum-operated, solution-feed technology offers maximum safety and allows flexible designs for different control strategies at multiple feed points. 

Gas chlorine is usually the least expensive method of chlorination for disinfection or biocide control, provided that the chemistry does not produce harmful by-products. One of the most common applications for gas chlorine is for the disinfection of potable water. In addition to being a potent but economical disinfectant, gas chlorination also leaves a residual. The U.S. Environmental Protection Agency (EPA) requires a residual in the water distribution system to prevent contamination in the pipelines. Gas chlorine is also used to disinfect treated wastewater and reclaimed water.

Many industries use gas chlorine for various applications. These include cooling water and intakes, aluminum or gold fluxing, pulp and paper, food and beverage, rubber glove manufacturing, flour bleaching and more.

Q: What approach would you recommend for selecting appropriate disinfection technologies for different applications?

A: Each application is unique and must be carefully reviewed. Some questions to ask

  • What water quality are you starting with and need to finish with?
  • What are the target microorganisms?
  • What is the control strategy?
  • Are disinfection by-products an issue?
  • What are the budgets for capital expenses and operating expenses?
  • Who will be using the system, and what is the operational degree of difficulty?
  • What safety issues must be considered?

Remember that each disinfection technology has advantages and disadvantages. It is important to work with a technical expert for every application. 

Q: What key advice would you give owners and operators of chlorine gas feed equipment to optimize their installed assets?

A: It’s important to use reputable, reliable equipment suppliers. Be sure you have great aftermarket support from your local representatives or manufacturer for spare parts and technical assistance.

You should also complete a site-safety assessment. Consider implementing container shut-off systems or scrubbers. Ensure the facility has an up-to-date Hazard and Operability Study (HAZOP), risk management program and training program.

Q: Do you foresee a change in the market for chlorine gas feed systems in the direction of alternative technologies?

A: Most chlorination technology applications are better suited to chlorine gas feed systems, and cost is usually the advantage. And with the impending chlorate regulations, chlorine gas has the advantage of not producing chlorates like the hypochlorites do.

Globally, we have not seen a drop in the market for chlorine gas feed systems in favor of alternative technologies. There are thousands of gas chlorination installations still providing reliable service. Internationally, large gas systems are the standard for disinfecting potable water. In my 40 years in the disinfection business, I can say that numerous facilities are still using chlorine gas because it’s the most economical and performs well. 

Some have proposed replacing gas chlorine with alternative disinfection methods because of safety concerns. That is not to say that the systems are not safe now. Current regulations require strict risk management and process safety management programs. Operators are highly-trained, with stringent safety procedures in place to prevent any problems. Emergency gas scrubbers and container shut off systems have enhanced the safety of using chlorine gas.

Of course, if chlorinated by-products are an issue, other disinfection technologies must be considered. These include chlorine dioxide, chloramination, ultraviolet radiation, ozonation, advanced oxidation processes (AOP) and peracetic acid (PAA).

Q: How do you see innovation in the established market for gas feed chlorination and instrumentation solutions compared to other solutions? Is innovation achievable?

A: Innovation does happen with this tried-and-true technology. While it might not be as glamorous as launching a new technology, there are plenty of incremental developments happening right now. These improvements deliver operating benefits for customers who still require gas feed products based on their current application.

Most innovations are related to features, instrumentation and control. Nobody has improved on the basic method of feeding — vacuum-operated solution feed — so that has not changed.

Q: What options are available for analyzing and controlling chlorine dosage and residual levels?

A: The control strategy is typically based on the process flow and chlorine demand.

  • If both flow and demand are constant, manual control is recommended.
  • If the flow varies, but demand is constant, flow proportioning is recommended.
  • If demand varies and flow is constant, residual control is recommended. If both vary, compound loop (flow + residual) control is recommended.

Feedforward control for chlorination-dechlorination is also widely used in this application. Ratio control of chlorine and ammonia feed is popular for chloramination as well. Custom control strategies can also be developed. Engineers should work closely with the technical experts and their clients during design and specification.

Q: Can you give us a short history of Capital Controls® and De Nora?

A: The original Capital Controls company invented the all-vacuum gas feed system and has 60 years of experience in the industry. Capital Controls was also the first gas feed manufacturer that was certified by the International Organization for Standardization (ISO). The company has been a member of the Chlorine Institute since 1972, providing a full range of chlorine gas feed technology.

De Nora, a leading global supplier of electrochemical technologies, acquired the well-recognized and proven Capital Controls® brand as well as a host of other water and wastewater brands ? including De NORA TETRA™, ClorTec®, EST, SANILEC®, SEACLOR®, UAT and BALPURE® in 2015.

Now the industry standard, the Capital Controls all vacuum gas feed system, is the most copied brand in the world. The design is simple, safe and robust. The De Nora Water Technologies business was created with these product lines and also includes a wide range of ozone systems and the Giselle® sanitizing system ?.

Q: What influence has De Nora had over the Capital Controls® products since the acquisition?

A: The original Electrode Technologies organization, De Nora, has a long history of innovation, investing around 3 percent of revenues in the identification, development and commercialization of exciting new technologies across a range of industries. 

Now with the De Nora Water Technologies group, we’ve completed several product launches in the water industry as well, including the OMNIPURE™ Series 64 Marine Sewage Treatment Units, ClorTec® DN on-site sodium hypochlorite generators, emergency scrubber technology (EST) dry media scrubbers and process equipment and more.

De Nora has brought new developments for Capital Controls® gas feed systems online quickly. Within the first 18 months, we consolidated multiple-gas-feed product lines into a simpler and better Capital Controls® product line.

For example, for many years, we offered both Advance™ and Chlortrol (formerly Bailey Fischer and Porter) gas feed systems. This was confusing to customers and could have resulted in mismatched components. De Nora recognized the problems and combined the two lines into the improved Capital Controls® product line, keeping the best features of both.

Q: Can you expand on the new gas feed and instrumentation products that you’re planning to launch?

A: De Nora consolidated five Capital Controls® gas feed cabinets to three in 2016.The three cabinets are now the Series 4100B (10 to 3,000 lb/day), 4200B (1,000 to 8,000 lb/day) and 5200B (1,000 to 10,000 lb/day). This simplification makes it easier for engineers and end-users to select the right cabinet for their application based on capacity.

We selected the best technology from the original gold-standard systems and packaged in a compact, sleek, modern look, including the cabinet’s small, space-saving footprint, which continues to be unique to the market. The liquid chlorine vaporizer also has a new modern appearance.

All three of the gas feed cabinets are available in either automatic or manual control and range in maximum capacity from 3,000 lb/day to 10,000 lb/day. All models, manual and automatic, feature a larger 10” standard gas flowmeter for better resolution.

The automatic cabinet models feature the familiar Chloromatic™ automatic valve actuator with onboard controller. This upgrade means that you may not need an additional controller, reducing costs.

The Series 4100B features sonic operation to 3,000 lb/day — gas feed at the speed of sound — on both manual and automatic models, eliminating the need for a differential pressure regulator.

We also launched the MicroChem® 3 Water Analysis System with new panel-mounted,factory-configured packages to measure free and total chlorine as well as chlorine dioxide, pH, and ORP.

This consolidation and upgrade to the Capital Controls gas feed line has been in development since 1998. With De Nora’s acquisition of the product line in 2015 and its focus on innovation, De Nora finalized the changes and launched in less than two years.

Q: Is it possible to retrofit existing gas feed facilities with some of the newer technologies, and how difficult would it be, if so?

A: Yes, the new wall panels and cabinet feeders can very easily be retrofitted into existing systems. Components are almost directly interchangeable.

Q: Are custom engineered solutions available?

A: Of course, we often get requests for custom solutions. Some customers need a specific control strategy. They may ask for custom instrumentation. In some cases, customers want different mounting options for their components. Each application is unique, and De Nora works closely with our customers to meet their specific requirements.

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Tags: Insider, De Nora, chlorination, gas feed, chlorine gas

William Stimeling

Written by William Stimeling

De Nora Product Manager-Gas Feed and Chlorine Dioxide

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