The combustion of fossil fuels generates NOx, which is a criteria air pollutant. JNEP offers SCR, SNCR and low-NOx combustion technologies for NOx control. Depending on the specific requirements of the project, we can also provide integrated SCR+SNCR technology which has an excellent cost-performance ratio.
In the SCR denitrification process, NOx in the flue gas reacts selectively with the reductant and produces N2 and H2O with the presence of V2O5/TiO2 based catalysts at a temperature of 300 to 420 ℃. The reductant is typically anhydrous ammonia, aqueous ammonia or urea. The reaction using ammonia (anhydrous/aqueous) as the reductant for a SCR process is described as follows:
For a typical SCR process, the SCR reactor is installed between the economizer and the air reheater. The following figure shows the process flow:
In the SNCR process, a reducing agent is injected into the boiler where the temperature of the flue gas is between 800 and 1100 ℃. The reducing agent reacts with NOx and produce N2 and H2O without the presence of catalyst. The reductant can be anhydrous ammonia, aqueous ammonia or urea. The following figure shows the process flow:
JNEP not only provides SCR and SNCR technology individually, but also provides an integrated SCR+SNCR solution which combines the high NOx removal efficiency of SCR and the low investment cost of SNCR. This technology is especially suitable for small boilers which do not have sufficient room for a full-size SCR unit or for the treating of flue gas with large NOx content variation.
Backed by years of engineering experience with ammonia sorbent and flow field design/simulation analysis, JNEP’s ammonia-flue gas mixing technology maximizes the performance of the denitrification system. Through the optimization of the ammonia injection grid, the mixing non-uniformity of ammonia and flue gas can be controlled to within 5%.
JNEP’s SCR technology guarantees less than 1% SO2/SO3 conversion, less than 800 Pa system pressure drop, and over 98% equipment utilization.
JNEP’s SNCR technology guarantees less than 0.5% boiler efficiency reduction and over 98% equipment utilization. The overall NOx removal efficiency is improved through optimization of the flow field design. The quantity and position of the ammonia injectors are optimally configured, and the ammonia injection quantities and concentrations are precisely controlled by the in-situ ammonia dilution system. This guarantees a high ammonia utilization and low ammonia slip without affecting the NOx removal efficiency.
Depending on the unique design criteria for each project, SCR-only, SNCR-only or the integrated SCR+SCR process can be selected to meet specific denitrification requirements, which provides our clients with the best denitrification solutions.
SCR: Denitrification efficiency: 70-95%; Ammonia slip ≤ 3 ppm
SNCR: Denitrification efficiency: 40-65%,; Ammonia slip ≤ 10 ppm