Research On Partitioned Ammonia In SCR Denitration Flue Of Coal-fired Power Plant

The uniformity of flow field and the uniformity of mole ratio of NH₃/NO_x at the cross section of the first catalyst layer in the selective catalytic reduction?SCR?denitration flue have an important influence on the denitration efficiency of the denitration system.The following study was carried out on a cold test bench with a 15:1 ratio reduction of the actual denitration flue of a power plant.First,based on the optimization of the velocity distribution of the cold test bench,the inlet was divided into four zones,each zone equipped with a set of spray ammonia grille to carry out the corresponding zoned ammonia injection simulation study,and geted the influence of the spray ammonia grille of each zone on the distribution of carbon dioxide concentration in the first catalyst layer section of the cold test bench.The two nitrogen oxide concentration distribution conditions were numerically simulated to study the amount of flux required for each spray ammonia zone,finally make the distribution coefficient of mole ratio of CO₂/NO_x of the cold test bench first catalyst layer section simulation results under the two concentration distribution conditions is less than 15%.The original cold test bench of the laboratory was modified,and the regional spray ammonia grille and grid multi-point concentration measuring device were added.The carbon dioxide was used instead of ammonia gas to carry out the experiment,the original carbon dioxide volume concentration background interference was excluded.According to the simulated flux in each area,the final experimental results show that the distribution deviation coefficient of mole ratio of CO₂/NO_x in the cross section of the first catalyst layer is about 15%,which basically meets the technical requirements of less than 15%in engineering.Comparing the experimental results with the simulation results,the simulation results are in good agreement with the overall distribution trend of the experimental results.It is proved that the numerical model used in this paper is reliable for predicting the carbon dioxide concentration distribution at the cross section of the first catalyst layer.After verifying the reliability of the numerical model established in this paper,it is applied to the actual SCR denitration system of a power plant in Shanghai,and the corresponding numerical model is established.The corresponding baffle is designed to make the velocity distribution deviation coefficient of the first catalyst layer reduced to 13.5%,meeting the technical requirements of less than 15%in engineering.At the same time,the ammonia injection system of a power plant in Shanghai has also been treated accordingly.By adjusting the ammonia injection amount of each ammonia injection zone,the distribution deviation coefficient of the mole ratio of NH₃/NO_x at the cross section of the first catalyst layer is reduced from 29.4%to 14.8%,meeting the technical requirements of less than 15% in engineering.