Low NOx combustion technology could effectively control the output of NOx to reduce the NOx emission form the origin. The mature low NOx combustion technology, invented by Zhejiang University Thermal Power Engineering Institution and adopted by JNHB, could reduce more than 50% output of the NOx.

By combining low NOx combustion technology with SCR & SNCR denitrification technology and forming the integrative cooperation control technology, the total denitrification efficiency is guaranteed more than 80% with more reliable economic operation.

The low NOx combustion technology of Zhejiang University includes: low-NOx combustion technology and low-loaded stable combustion technology of adjustable lean-rich pulverized-coal, Three-dimensional swing separating over-fired air combustion technology, fuel classification reburning technology, the complex multifunctional direct-flow combustion technology.

I、The adjustable pulverized-coal lean-rich low-loaded stable combustion technology
The bias combustion technology forms the partly fuel-rich region in the outlet of the burner, which causes the reducing atmosphere and restrains the production of NOx meanwhile with a significant reduction of NOx emission; the double-stable combustion technology of bias combustion plus stable combustion makes sure the stable combustion result in the low-loaded condition.

the schematic diagram of bumping pulverized-coal bias shunt
The adjustable pulverized-coal bias low NOx combustion technology has successfully applied in over 50 boilers and all gained the great practical effect.

The design of the burner

II. the Over Fire Air （SOFA）Technology of Three-dimensional Swinging Separated Arrangement 
Through installing the three-dimension swinging over fire air (SOFA) and combing the reconstruction of the original secondary air nozzle, the technology, a deep air classification low-NOx combustion technology, successfully reduces the air volume in the pulverized-coal combustion region to form the rich-fuel zone when the pulverized coal enters the furnace and run the oxygen-deficient combustion, which reduces the production of the fuel NOx.  the three dimension could swing the over fire air and make it have the swing function from up to bottom, left to right, which could adjust the height of the flame center in furnace and the difference of the flue gas temperature in the outlet of the furnace to make the combustion regulation more flexible and reliable.

the Furnace Arrangement of the Typical Swing Over Fire Air System

III. Fuel Reburning Technology
Fuel reburning technology, a fuel classified combustion technology in the furnace, is to set the NOx reduction region for the secondary fuel oxygen-deficient combustion in the furnace in order to control the eventual production volume of the NOx.

The  80%--85% fuel is sent to the primary combustion zone to fully burning in the condition of excess air ratio >1; while the other 15%--20% fuel is sent from the upper of the primary combustion zone and form the reducing atmosphere in the condition of air excess ratio <1. Part of the generated NOx  occurs the reducing reaction with the fuel and the incomplete combustion product.

the Schematic Diagram of the Fuel Reburning Technology

IV. The Complex Multifunctional Direct-flow Combustion Technology
The complex multifunctional direct-flow combustion technology is a combustion system applied on the tangential fired boilers combined with the horizontal rich-lean combustion technology; the primary air reversed tangential technology, air classification technology of the level and the height direction of the furnace, the converging technology of the outlet of the primary air and other multi-methods, which could effectively reduce the NOx emission and control the slag-bonding in the furnace to achieve the low-loaded stable burning and prevent the water cooled wall from high-temp corrosion.

(a) With performance wind　　　　　　　(b) without performance wind

The comparison diagram of the oxygen content around the water cooled wall in the furnace