Session: 17-08-01: Posters Related to Energy

Paper Number: 99252

99252 - Hybrid 3 in 1 System Including Air-Staging, Flue Gas Recirculation, and Selective Non-Catalytic Reduction for Nox Reduction in Biomass Circulating Fluidized Bed Combustion 

NO_x reduction technology has an important meaning in global air pollutant emissions for fine dust reduction in industries and power plants, which are as critical as climate issues. The technologies for reducing NO during combustion can be divided into two categories: combustion control and flue gas treatment. Combustion control technologies with low reduction rate can suppress the NO release by forming reduction atmosphere, while flue gas treatment with high reduction rate incur several costs including operation and maintenance cost.

Therefore, a hybrid 3 in 1 system was designed using air-staging, flue gas recirculation (FGR), and selective non-catalytic reduction (SNCR) integrated into three different types of technologies to develop NOx reduction in circulating fluidized bed combustion (CFBC). The pollutant emission, especially NO, CO, and N₂O concentration based on O₂ 6 vol.%, was observed to investigate the optimal condition of hybrid 3 in 1 system.

After applying only air-staging, the NO decreased from 150 ppm without air-staging to 120 ppm, while CO concentration increased approximately 27% compared with base condition. However, the bed temperature in the combustor significantly increased due to the increase in solid retention amount at the dense zone of the combustor bottom by reducing amount of primary air entered into the distributor. Therefore, FGR was additionally, applied to control the bed temperature. Furthermore, the FGR technique is considered as a cost-effective combustion control method for reducing NO emission. The combined air-staging and FGR showed the simultaneously reduction of NO and CO to 25.9 and 18.2 % without any combustion problems such as ash-related and combustion efficiency, respectively.

For more NO reduction in the combustor, a hybrid 3 in 1 system including SNCR was performed for the injection position (9.4 and 9.9 m), the phase state (liquid and gaseous), the types (ammonia and urea), and normalized stoichiometric ratio (NSR) of reductant agent based on previously optimized air-staging and FGR conditions. Under optimal condition of hybrid 3 in 1 system, the NO emission was considerably reduced to 71 %, whereas CO emission was suppressed by preferential reaction of OH required for CO oxidation in the SNCR reaction, resulting in an increase of CO concentration from 11.5 ppm to 65 ppm by injecting liquid ammonia of 12 wt.% with NSR 4.4 at 9.4 m of the combustor. Moreover, N₂O emissions also increased to 25.9 % compared with that for the base case without hybrid 3 in 1 system. Hybrid air-staging-FGR-SNCR system is a fusion technology that can induce low-load selective catalytic reduction (SCR) by minimizing NO emission inside the combustor. However, a technology to reduce N₂O, which can be generated by the conversion of ammonia to nitrate together with O₂, is required since N₂O is considered as a powerful greenhouse gas.

 

This work was supported by the Technology Innovation Program (20005788, Development of pollutant reduction combustion technology for multi-fuel customs) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea).

Presenting Author: Tae-Young` Mun Korea Institute of Energy Research

Presenting Author Biography: I’m a principal researcher in Korea Institute of Energy Research (KIER) funded by South Korea government. My research fields are the gasification of solid fuels (biomass, wastes, and coals), the oxy-combustion with circulating fluidized bed combustion for CO2 capture, and ammonia co-firing for CO2 reduction. Also, I’m an academic advisor for a student researcher at Chungnam National University and KIER.

Authors:

Tae-Young` Mun Korea Institute of Energy Research
Seong-Ju Kim Korea Institute of Energy Research
Sung Jin Park Korea Institute of Energy Research
Sung Ho Jo Korea Institute of Energy Research
Sang Jun Yoon Korea Institute of Energy Research
Ji Hong Moon Korea Institute of Energy Research
Jae-Goo Lee Korea Institute of Energy Research