Multiple installation (MI) system for once-through boilers

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On actual boiler facility, the required steam amount varies depending on the situation of the operation of the machinery using the steam. Boiler load adjustments, i.e. the combustion adjustments, are performed to respond to these variations. When boiler load falls, so does operation efficiency. A high proportion of boiler facility operation is in this low load region, which is important from the viewpoint of efficiency improvement and reduced carbon emissions. A solution to this is provided by a multiple installation system for once-through boilers.
The multiple installation system (MI system) is composed of multiple units of once-through boilers as necessary for the facility and an MI controller to control the boiler operation using the steam header pressure. During its operation, the requirement for steam on the production facility is read as the steam header pressure. The number of units that must be operated is calculated and they are operated automatically.

Organisation providing the technology
Ministry of Economy, Trade and Industry
Endorsing entity

Ministry of Economy, Trade and Industry.


In examples in Japan and countries where this technology is frequently applied, roughly a 10 to 20% improvement in the operation efficiency is observed if a flue and smoke tube boiler is replaced with a once-through boiler MI system.


· Installation is possible with around 50% of the space required for conventional equipment.


· The control ensures that the boilers necessary to meet the steam load are in a state of operating at a high efficiency (with no boilers stopped if at all possible). This makes it possible to maintain the operation efficiency in the low load region at a higher level than that of conventional boilers.
· The boilers are controlled in a way that avoids stopping whenever possible, enabling the boilers to accurately follow the variations in steam load.
· It is possible to install the boilers for each separate site using steam, so there is little heat loss or pressure reduction loss due to long steam piping.

Succes factors and requirements

It is necessary to check the laws and regulations related to installation in the country of installation.

Investments required




Countries where implemented
South Korea

Ministry of Economy,Trade and Industry, JAPAN
[email protected]

Technology owners

Ministry of Economy, Trade and Industry.