Pulse-Chlorination: an environment-friendly technology to control biological fouling at cooling systems

By Floris Schulze

Floris Schulze offers his advice for both mitigating the fouling and meeting the discharge limit in cooling water systems at industrial plants.

Liquefied Natural Gas (LNG) producer Qatargas, writes: "Can you help us to combat macro fouling and micro fouling in our cooling water system and at the same time reducing chlorine usage in cooling seawater systems by three quarters without any adverse operational consequences?"

Floris Schulze. Many utilities and industrial companies around the globe encounter the same problem: how can one control biological fouling and, at the same time, operate in a cost-effective and environment-friendly way? This is a well-known dilemma that can be solved thanks to a new, highly sophisticated technology.

At KEMA, a global energy consulting and testing & certification firm with offices in more than 20 countries, we have developed Pulse-Chlorination (P-C), a tailor made chlorination method. It enables optimal antifouling treatment with a minimum use of chlorine. This technology enhances a cyclic mode of hypochlorite dosing (on/off dosing regime), based on the behavioural responses of the specific bivalve to chlorine, thereby taking advantage of this recovery period to delay the restart of P-C. By applying P-C, bivalves will have to switch their metabolic mode continuously between aerobic and anaerobic

In 2007, Pulse-Chlorination was implemented at the Qatargas LNG plant. The main target species to be controlled was the pearl oyster Pinctada radiata. After two years of operation and inspections of the cooling water system, it was concluded that Pulse-Chlorination has been very successful in both mitigating the biofouling and meeting the strict discharge limit. The processes have been running without problems and the cooling water system itself was very clean in comparison with the years before, when a continuous dosing was applied. Also, clear economical benefits for operating the electro chlorination plant at lower capacity have been recognised.

The project carried out at Qatargas won an environmental award at the RECSO Offshore Arabia 2009 Conference. RECSO stands for Regional Clean Seas Organisation, a non-profit oil industry co-operative organisation functioning on the concept of "mutual aid" with the primary aim of protecting the marine environment in the Arabian Gulf. The Qatargas' cooling seawater Pulse-Chlorination project won the "Excellence in Environmental Technology" category.

The project has enabled Qatargas to significantly reduce the amount of chlorine discharged to sea thus minimizing any potential impacts on marine life. Cooling seawater is used by a number of different industries and is vital for the cooling requirement of many modern industrial and power generation facilities within Qatar.

In a statement, Qatargas said; "These awards have come as a result of our dedication and commitment towards environmental protection. Qatargas strongly believes that industrial development should go hand in hand with environmental sustainability and the various environmental initiatives undertaken by Qatargas prove that this is indeed possible."

In addition, Pulse-Chlorination was declared Best Available Technique at the well-known "Desalination and the Gulf" conference on December 6 and 7 in Bahrain. This declaration was based on independent research carried out by WorleyParsons, commissioned by the regulatory authority.

But not only in the Middle East, also with many companies in the Far East, Australia and Europe, Pulse-Chlorination has become the predominant technology.

About

Floris Schulze, Managing Director of KEMA Middle East, has 16 years of professional experience in projects concerning applied and (advanced) stochastic modelling, data analysis, econometrics, (industrial) process control, environmental-informatics, hydro-informatics and risk and maintenance management. As Managing Director KEMA Middle East he is responsible for all KEMA activities in the Middle East.