Combustion device and boiler

A boiler comprising:

• a furnace;
• a combustion device installed in the furnace and configured to inject and burn ammonia as a fuel;
• an ammonia supply unit configured to supply the ammonia to the combustion device;
• and
• a pulverized coal supply unit configured to supply pulverized coal to the combustion device, wherein
• the combustion device includes:
• an inner tube nozzle disposed in a center part of the combustion device when viewed in an injection direction of the fuel, connected to the ammonia supply unit, and configured to inject the ammonia;
• an outer tube nozzle disposed to surround the inner tube nozzle from outside in a radial direction when viewed in the injection direction of the fuel, connected to the ammonia supply unit, and configured to inject the ammonia around the inner tube nozzle such that nitrogen oxides, which are generated by burning a mixture of the ammonia injected from the outer tube nozzle and oxygen, are supplied to a reduction region, which is formed by the ammonia injected from the inner tube nozzle, and the nitrogen oxides are reduced in the reduction region to become nitrogen gas;
• and
• a pulverized coal injection nozzle connected to the pulverized coal supply unit and configured to inject air containing the pulverized coal around the outer tube nozzle when viewed in the injection direction of the fuel,
• a tip end of the inner tube nozzle protrudes farther in the injection direction than a tip end of the outer tube nozzle, and
• the outer tube nozzle and the pulverized coal injection nozzle each taper towards the tip end of the inner tube nozzle.