SCR denitration technology

SCR denitration technology

Process principle

SCR denitration technology has been successfully applied in a large number of industrial plants.  its use reducing agents (liquid ammonia, ammonia water, urea) under the action of catalysts to reduce nitrogen oxides in flue gas to harmless nitrogen and water within a suitable temperature range .
Reaction principle: NO_x+reducing agent → nitrogen+water
Reaction temperature: 300 ℃~400 ℃
Reducing agents: ammonia, urea
Catalyst: use a catalyst and catalytic reactor is required
Reactor layout: in the tail flue of the boiler

Chemical principle

Primary reaction
4NO+4NH₃+O₂→4N₂+6H₂O
2NO₂+4NH₃+O₂→3N₂+6H₂O (favorable)
Primary side reaction
4NH₃+3O₂→2N₂+6H₂O
NH₃+O₂+SO₃→NH₄HSO₄ (harmful)
NH₃+O2→NO_X+H₂O
300℃ ~ 420℃ is the selection temperature range of SCR denitration "efficiency, safety and economy" .

Process flow diagram

The main function of equipment and process systems

1. SCR reactor / catalyst system: denitration reactor body is the most important part of the denitration device, The shape is a rectangular cube with side panels on all four walls,  forming a cases . The catalyst is arranged inside it .
2. Catalyst Module: catalyst is the key component of SCR technology,  its performance will directly affect the denitration efficiency and operating life.
3. The hybrid system of flue gas / ammonia:  mixing of flue gas / ammonia by diluting fan and then injected into the reactor through the ammonia injection grid.
4. Ammonia reserve and supply system:  reducing agent is stored in the storage tank through an unloading device, and then transported to the metering and mixing module through a circulating pump.
5. Dilution water system: dilution mixer should adopt the static mixer.
6. Soot blowing system: depositing dust is preventing on the surface of the catalyst and affecting its activity by sound waves or steam blowers .
7. Electrical control system: electrical control and thermal instrumentation etc.

Technical characteristics

1. High denitration efficiency and reaching over 90%.
2. It is the most mature and reliable denitration technology on domestic and abroad .
3. High denitration efficiency  , security and stability operation.
4. The engineering investment is relatively large.
5. Ash blockage will occur when burning high ash and calcium coal