MHIEC Refurbishes Waste-to-Energy Facilities at Eco Clean Plaza Miyazaki

Mitsubishi Heavy Industries Environmental & Chemical Engineering (MHIEC) successfully finished the refurbishment of several facilities at its Eco Clean Plaza Miyazaki: a waste-to-energy plant in Kyushu, Japan. The refurbishment work, which focused on ensuring stable combustion and long-term operation, upgraded out-of-date equipment that ran for over 15 years. MHIEC’s combustion control system extended plant service life and achieved stable combustion with lower air ratios.

The company also replaced equipment involved in:

• Combustion
• Combustion-gas cooling
• Waste gas treatment
• Waste heat utilization
• Ventilation
• Ash removal
• Electrical instrumentation

Following refurbishment, the plant attained a 31.86% CO₂ reduction rate compared to the lower 17.25% targeted rate. This was achieved by replacing a feeder and boiler piping, allowing higher durability when exposed to lower air ratios. Additionally, the increased power generation made efficient use of waste steam through a low-temperature denitration catalyst. Lastly, MHIEC installed high-efficiency motors, converted to inverter-type equipment, and optimized the remaining plant equipment.

Refurbishment & Plant Background

MHIEC completed the refurbishment over a four-year span, from 2021-2024, encountering difficulties with ongoing waste treatment and the coronavirus pandemic. Despite this, it was completed on schedule and enabled a waste treatment capacity of 579 tons per day (tpd), lengthened plant service life, and significantly reduced CO₂ emissions.

The Eco Clean Plaza Miyazaki contains waste incineration, recycling, and final waste management facilities, treating waste from Miyazaki City and nine surrounding localities. It is equipped with three stoker-type incinerators, each with a waste treatment capacity of 193 tpd. Using waste heat via steam turbine, the facility generates 11,200 kW. The incineration facilities were designed and constructed by Mitsubishi Heavy Industries (MHI) and completed in October 2005.

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