Flue gas denitrification ammonia injection mixing system and its static mixer and ammonia injection control method

Abstract

The invention discloses a static mixer, which is arranged in a flue. The static mixer includes: a plurality of flow guide assemblies, which are distributed in the flue; extension; outer pipe, which is a tubular structure with thin bottom and thick top, the lower end of the outer pipe is connected with the outer wall of the intake pipe, and the upper end is higher than the intake pipe; the top plate is arranged above the outer pipe; the air outlet channel is formed by the outer periphery of the top end of the outer pipe and a dust discharge hole, which is arranged at the lower end of the outer pipe; and an ash collecting layer, which is sealedly connected with the inner wall of the flue, and forms an ash collecting groove between the guide components. The invention also discloses a flue gas denitration ammonia injection mixing system and a control method for ammonia injection. The present invention realizes two times of flue gas dedusting by setting the diversion component, which can effectively remove dust particles with larger particle size in the flue gas; the static mixer of the present invention can also effectively block the large pieces of dust falling from the flue above, avoiding The ammonia gas nozzle below is clogged.

Description

technical field [0001] The invention relates to the technical field of flue gas denitrification, in particular to a flue gas denitration ammonia injection mixing system, a static mixer and an ammonia injection control method. Background technique [0002] At present, the most widely used flue gas denitration method is the selective catalytic reduction (SCR) denitration technology. The main principle of SCR denitration technology is to inject the reducing agent ammonia into the flue gas at 280℃~420℃, and mix it evenly. 3 NO in flue gas x It is reduced to non-toxic and non-polluting nitrogen and water, so as to realize the removal of NO from the mixed gas x the goal of. [0003] Flue gas denitrification efficiency and NH 3 The escape rate is the two core performance indicators of SCR denitration technology. Studies have shown that the uniformity of the flow field of the mixed gas on the cross section of the SCR reactor is the key factor to ensure the complete SCR denitrat...

AI Technical Summary

Problems solved by technology

Since it takes a long time to adjust the uniformity of ammonia spraying every time it is started and has high technical content, the SCR denitrification device is generally entrusted to a professional company to adjust it when it is started. After the adjustment is completed, the opening of the ammonia injection manual control valve is no longer adjusted

[0008] Existing SCR inlet and outlet NO x Concentration detection generally adopts single-point measurement, and the monitoring point is generally set in the center of the flue, but the same cross-section of the flue NO x The concentration gap is quite large, and the representativeness of single-point detection is poor, so it is difficult to reflect NO truthfully. x The average concentration; when the load of the device, the combustion method, and the type of coal to be burned change, the distribution of the flue gas flow field in the flue changes under different working conditions, and the NO in the flue gas x The concentration distribution also changed. The opening of the ammonia injection manual control valve set when the device was started could no longer meet the requirements under other working conditions. The uniformity of ammonia injection became worse, and the deviation between the ammonia nitrogen molar ratio and the average value in local areas became larger. Areas where the molar ratio is too small have low denitrification efficiency and export NO x Unable to reach the standard, the area where the ammonia nitrogen molar ratio is too large ammonia escape exceeds the standard

As the country pays more attention to environmental protection, local environmental protection bureaus x Penalties for exceeding the standard are gradually increasing, as the Environmental Protection Agency has imposed strict regulations on NO x The concentration is monitored dynamically in real time, and the value of ammonia escape has not yet been included in the monitoring range. In order to ensure environmental protection standards, companies generally increase the amount of ammonia sprayed to discharge the flue gas out of NO x Control in a lower range, resulting in a substantial increase in ammonia escape from the SCR denitrification device, resulting in corrosion leakage or serious blockage of rear-end air preheaters or economizers and other equipment. If there is a wet desulfurization device in the future, it will also cause ammonia nitrogen content in the desulfurization wastewater. Significantly exceeded