This document should serve as a summary for your reference when discussing biogas boilers with potential customers.
Further information can be found in the documents listed below:

• Miura Biogas Capabilities – A presentation for reference when discussing biogas.
• Biogas Fuel Requirements - Required fuel components and quality for burning biogas with Miura boilers.
• Biogas Boiler Project Checklist – A checklist for use when finalizing project details to ensure a quick acceptance if an order is submitted.

Biogas Basics

Biogas is a gaseous fuel produced through natural processes as bacteria anaerobically digest organic matter. The source matter ranges from animal and food waste to agricultural waste and wastewater sludge. Biogas is generally composed of about 45-75% methane and 25-40% carbon dioxide, with a few other components at various concentration levels. The concentration of these components depends largely on the source material.
Using biogas as a source of combustion is carbon-neutral since the carbon dioxide is already produced during the digestion process. Miura America has expanded its capability to generate steam using biogas as a primary fuel. This presents great opportunity to reduce carbon emissions while reducing customers’ fuel costs.

Biogas Challenges

• Fuel Quality
  • Variable methane content, HHV, fuel pressure
• Corrosion
  • H2S is corrosive in fuel line
  • H2SO4 is produced in the flue gas path
• Scaling
  • Biogas often contains siloxanes, which can cause scaling and plug up the furnace
• Safety
  • H2S is hazardous to human health

Miura Experience

Miura Group has substantial experience worldwide, but limited sales in North America.

• Miura Japan and China have each sold more than 100 biogas boilers.
• Miura America has established designs but has limited installations. However, all standard NOx (≤100 ppm) EX(H) boilers are currently available for use with biogas, with some specific requirements.

Required Design Details

• Fuel Composition must meet Miura’s requirements in document EN-SC-101
• A special gas train with larger pipe and specialty components rated for biogas
• An independent pilot line using natural gas or propane
• Larger blower if full rated boiler output is needed
• Gas train air purge system with control box if H2S concentration is greater than 20 ppm

Recommended Design Details

• No economizer or special economizer

Auxiliary Equipment

• Gas pre-treatment, including H2S and siloxane scrubbers, gas mixer, pressure booster
• H2S gas leak detector

Agency and Field Approval

• Field approval is required since no uniform standards for biogas exist
  • Miura cannot provide a UL-approved boiler from the factory
  • ASME CSD-1 formally does not apply to biogas
• Always engage Engineering and the boiler inspector that will be approving the installation as early as possible to ensure the boiler will meet local requirements.