Advancing Boiler Ash Cleaning Technology to Halve Annual Overhaul Frequency and Improve Operational Performance

ECOVE’s subsidiary, ECOVE Environment Services Corp., operates 11 large-scale Energy-from-Waste (EfW) Centers in Taiwan, accounting for more than half of the processing capacity among privately operated EfW Centers nationwide. This article highlights the company’s efforts to address ash and salt accumulation caused by long-term boiler operation at incineration plants. Through the comprehensive enhancement of shockwave soot-blowing technology and gas booster systems, the company successfully reduced the annual overhaul frequency from twice a year to once, achieving a major operational breakthrough. The improvement not only significantly enhanced operational performance but also effectively reduced energy consumption and carbon emissions associated with gas cylinder replacement and transportation.

Facility-Specific Cleaning Solutions through Diverse Boiler Cleaning Technologies

ECOVE has long been dedicated to the resource circulation industry and continuously accumulates operational experience by introducing new equipment and technologies to enhance incineration efficiency. Since each EfW Center differs in equipment configuration, operating load, and site conditions, continuous improvement requires more than simply adopting a single technology. Instead, improvements must be tailored to each facility’s characteristics by integrating considerations such as operational safety and maintenance convenience, and gradually implementing optimization measures.

To address boiler ash accumulation and maintain heat exchange efficiency, ECOVE has introduced various boiler cleaning technologies since 2010. Starting with traditional steam soot blowing and mechanical rapping, the company has continuously tested and implemented CO₂ shockwave cleaning, mobile shockwave cleaning, fixed shockwave cleaning, and water spray cleaning technologies. Through extensive operational validation, ECOVE has progressively identified the most suitable ash cleaning solutions for each facility.

Fixed shockwave soot-blowing systems are essential for removing boiler ash deposits and maintaining stable incinerator operation.

Introducing a Patented Gas Booster System to Resolve Residual Gas Issues and Improve Utilization Efficiency

Boiler tube ash accumulation in incineration plants occurs because fly ash and salts contained in flue gas tend to adhere to boiler tube bundles and internal duct surfaces after prolonged continuous operation. This reduces heat exchange efficiency, accelerates material corrosion, and subsequently affects steam generation and power output, while also increasing boiler tube replacement costs. Shockwave cleaning technology operates by mixing gases such as fuel gas and oxygen, igniting the mixture, and utilizing the instantaneous pulse generated by the explosion to remove accumulated ash and reduce salt-induced corrosion. This allows boilers to maintain optimal heat transfer performance.

Previously, all gas sources used in shockwave cleaning systems were supplied through gas cylinders. However, shockwave cleaning systems require specific inlet pressures for each gas supply source. When gas pressure falls below equipment requirements, residual gas remaining inside cylinders cannot be effectively supplied to the system. Based on field operating experience, approximately one-third of the gas volume often remained unused, resulting in resource waste.

To maximize residual gas utilization, ECOVE installed a “gas booster system” in its shockwave cleaning systems starting in 2022 and subsequently obtained a patent for the technology, demonstrating its engineering innovation capabilities. The system uses compressed air to drive a piston, boosting residual gas pressure from below 2 atm to more than 100 atm, thereby improving gas cylinder utilization efficiency. The system automatically starts and stops according to the pressure of the system, eliminating the need for manual monitoring. In addition, its fully pneumatic design eliminates risks associated with electrical sparks and removes the need for explosion-proof electrical components, effectively achieving both safety and efficiency.

Upgrading Gas Supply Systems by Replacing Conventional Consumable-Based Management with Continuous and Stable Supply

After resolving residual gas utilization issues through the gas booster system, ECOVE further upgraded the gas supply method for shockwave cleaning systems by replacing methane cylinders with natural gas supply, improving energy utilization efficiency at the source. The upgraded system connects natural gas pipelines directly to the plant’s shockwave cleaning system. The gas is then pressurized by the booster system and precisely controlled through pressure regulators to ensure stable supply.

Methane is a greenhouse gas, switching to natural gas supply reduces the frequency of gas cylinder installation and removal. Combined with flow, pressure, and leakage monitoring, the system helps mitigate fugitive methane leakage risks. Compared with conventional gas cylinders, natural gas provides continuous supply and stable pressure. This transformation changes the gas supply management model from an “intermittent, consumable-based” approach into a “continuous, system-based” energy supply model, improving system stability and aligning gas resource allocation more closely with actual process requirements. This transition from consumable-based supply to system-based supply eliminates the need for gas cylinder storage space, inventory management, and supply coordination. More importantly, it significantly reduces Scope 3 greenhouse gas emissions associated with cylinder transportation and logistics, creating tangible value-chain decarbonization benefits.

Gas cylinders previously used in the shockwave cleaning system

Pressure regulator of the upgraded shockwave cleaning system

Expanding Applications: Evaluating Nitrogen Generators to Replace Gas Cylinders

Building on the successful experience and benefits of replacing methane cylinders with natural gas, ECOVE is actively evaluating the feasibility of using nitrogen generators to replace nitrogen cylinders. The objective is to separate nitrogen directly from ambient air through on-site equipment and provide a continuous nitrogen source for shockwave generators.

In the shockwave cleaning system, nitrogen functions as a pneumatic spring that generates thrust to hold the valve seat in position. When the gas mixture ignition pressure exceeds the preset level, the valve instantly opens, releasing a high-pressure pulse into the boiler for ash removal. The accumulated nitrogen pressure then pushes the valve back to its original position and closes it. Traditional nitrogen cylinder systems face similar challenges, including declining cylinder pressure, incomplete utilization of residual gas, and inventory management issues. If nitrogen generators are successfully implemented in the future, ECOVE expects to achieve comparable operational and environmental benefits to those realized through the replacement of methane cylinders. Furthermore, this approach will transform traditional cylinder-based resource consumption model into an on-site circular resource management system, fully aligning with the core principles of the circular economy. 

Innovative R&D Delivering Operational and Sustainability Benefits

Through systematic evaluation, validation, and implementation of improvements to the shockwave cleaning system, the ECOVE team has established a solid foundation for long-term continuous boiler operation at incineration plants. The initiative achieved a significant breakthrough by reducing annual overhaul frequency from twice a year to once, substantially lowering auxiliary fuel consumption and maintenance costs associated with boiler startup and shutdown cycles.

Looking ahead, ECOVE will continue identifying optimization opportunities based on the characteristics of each facility. Through the introduction of innovative technologies and the integration of cross-site operational experience, the company will further enhance the resilience of resource recovery facilities, improve operational performance, implement energy conservation and carbon reduction measures, and contribute engineering expertise to advancing environmental sustainability.