Metso Minerals has played a major role in the design, engineering and installation of China"s largest waste incinerator system in Shanghai.

The twin rotary kiln system is located in the Shanghai Chemical Industrial Park (SCIP) and was built to coincide with the construction of a chemical plant. It is designed to decontaminate and neutralize solids, liquids, gases, and sludges.

Particular attention is paid to safety systems which carefully monitor a process that is handled by two identical process lines, each with a Metso-built direct-fired kiln.

Fired by propane gas and capable of processing 120 metric tonnes of material per day (MTPD), the system generates steam, which is sold on to other users. Thirty-five different control racks mix and inject the composite wastes into the primary and secondary firing chambers, and each kiln is rotated by a variable speed drive, allowing adjustment and control of the waste feed.

Metso Minerals' project manager John Whelan says special provisions and materials had to be used for the handling and piping of these systems. "The variety and quantity of these waste materials made this system quite a challenge. Most are introduced at the feed end of the kiln but many are also used to fuel the secondary combustion chamber."

Metso China's local project manager in Shanghai, Yanli Wang, points out the efficiency of the process. "The capacity of the system is driven less by weight or volume and more by temperature. When you mix the wastes efficiently, you actually do not have to use the propane in the burners - the wastes themselves combust and heat the system.

"The design and operation of the system permits the process to vary the 'recipe' of wastes in order to achieve steady temperatures and efficient disposal. There is no doubt that the system can reach the contract-rated capacity of 120 MTPD on each line."

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