An Experimental Study on the Characteristics of NOx Distributions at the SNCR Inlets of a Large-Scale CFB Boiler

Abstract

The unknown NOx distributions inside large-scale CFB (circulating fluidized bed) boilers have always hindered the economy of the SNCR (selective non-catalytic reduction) process. In this study, field tests were carried out on a typical 300 MW CFB boiler, where multi-level 316 L-made probe and Ecom-J2KN/Testo 350 analyzers were used to perform detailed two-dimensional distributions of flue gas composition at SNCR inlets for the first time. The penetration depth inside the horizontal flue pass was up to 7 m. The NOx distributions were analyzed in detail combining with the auxiliary test in the dilute phase zone. Key results show that the average O2 concentrations in #A and #C regions were 6.52% and 0.95%, respectively. The vertical NOx distributions of #A and #C SNCR inlets were similar, showing a trend of first increasing and then decreasing with peak value all appeared at 5 m depth, while the NOx distribution of #B SNCR inlet was basically increasing. Some local areas with extremely high NOx concentration (over 2000 mg/m3) were observed near the inclined edge of SNCR inlets, which has never been reported before. Based on this, the optimization of urea injections was conducted, which could save 15.7% of the urea solution consumption while ensuring ultra-low emission of NOx.

Thermal–Hydraulic Calculation and Analysis on Water Wall System of a 700 MWe Ultra-Supercritical CFB Boiler

“…CFB boiler technology is also well suited for applications requiring high steam parameters and is capable of achieving supercritical and ultra-supercritical steam conditions, which makes it ideal for use in large-scale power plants, where high efficiency and reliable operation are crucial [5]. In addition, the amount of NO x is limited by controlling the combustion temperature, air staging, lowering excess air, flue gas treatment, controlling the cyclone performance, controlling the coal particle size, or SNCR, resulting in better environmental performance [6][7][8][9]. In addition, SO 2 emissions can be controlled by increasing the cyclone efficiency or appropriately reducing the particle size of the limestone, approaching a more ideal desulfurization efficiency [10].…”

Sulfur and Water Resistance of Carbon-Based Catalysts for Low-Temperature Selective Catalytic Reduction of NOx: A Review

“…Therefore, it is an increasingly urgent task to remove NO x . Currently, several denitration technologies, including selective non-catalytic reduction (SNCR) [5][6][7], selective catalytic reduction (SCR) [8,9], and non-selective catalytic reduction (NSCR) [10,11], can be used to reduce NO x . Among them, selective catalytic reduction (SCR) for the removal of NO x is considered to be one of the most promising technologies which has been commercialized for both stationary and mobile NO x sources.…”

Membrane-less Paired Electrolysis for Cooperative Conversion of Complex NO in a Complexing Absorption System

“…Currently, selective catalytic reduction (SCR) 3 and selective noncatalytic reduction (SNCR) 4,5 are applied widely as mature NO removal technologies. The SCR method converts NO into N 2 at 200−400 °C and is plagued by ammonia escape and catalyst deactivation.…”

“…Currently, selective catalytic reduction (SCR) and selective noncatalytic reduction (SNCR) , are applied widely as mature NO removal technologies. The SCR method converts NO into N 2 at 200–400 °C and is plagued by ammonia escape and catalyst deactivation. − SNCR is operated at 1120–1380 °C without a catalyst and suffers from secondary pollution induced by ammonia escape as well .…”