Sound wave temperature measurement cooperative control cement kiln SNCR denitration system and working principle thereof

Abstract

The invention relates to a sound wave temperature measurement cooperative control cement kiln SNCR denitration system and a working principle thereof. The sound wave temperature measurement cooperative control cement kiln SNCR denitration system comprises a first air pipe, a second air pipe and a computer, wherein the first air pipe and the second air pipe are both provided with a plurality of denitration devices, and each denitration device comprises an ammonia water pipeline, a compressed air pipeline and a temperature measurement combination; and the temperature measurement combination comprises a plurality of sound wave temperature measurement devices which are distributed at equal angles in the circumferential direction, air inlets of the sound wave temperature measurement devices areconnected to one end of the compressed air pipeline in parallel, and a denitration combination is further arranged above the temperature measurement combination. According to the invention, the plurality of denitration devices are arranged in the flue gas flowing direction, and the temperature measurement combinations in the plurality of denitration devices can accurately measure the temperaturedata of any position in the flue gas flowing process, so that the temperature data of flue gas can be measured in real time. In addition, the distance between the temperature measurement combination and the denitration combination in each denitration device is small, and the ammonia spraying amount can be accurately and quickly determined by a plurality of ammonia water spray guns in the denitration combination according to the temperature of the flue gas at the nearby position, so that the denitration control difficulty is reduced, and the control flexibility is greatly improved.

Description

technical field [0001] The invention relates to an SNCR denitrification system for a cement kiln controlled by sound wave temperature measurement and its working principle. Background technique [0002] In recent years, the country is vigorously implementing the transformation of ultra-low emission of flue gas in non-electric industries, and the ultra-low emission of cement production line is also on the agenda. The cement production process will produce a large amount of NOx. At present, cement kilns mainly use staged combustion and SNCR system to remove In addition to NOx, from the general application situation, the removal efficiency of SNCR system is much higher than that of staged combustion to remove NOx technology, and SNCR denitrification system is also widely used in cement kilns. [0003] The NOx concentration at the outlet of the preheater at the top of the cement kiln is generally higher than 500mg / m3, and the removal efficiency can reach 60% by using SNCR denitr...

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Problems solved by technology

[0003] The NOx concentration at the outlet of the preheater at the top of the cement kiln is generally higher than 500mg / m3, and the removal efficiency can reach 60% by using SNCR denitrification technology. However, many provinces have issued local standards for air pollution emissions. The requirement is not less than 150mg / m3 or 100mg / m3. If the current removal capacity is to meet higher removal requirements, it is necessary to increase the amount of reducing agent ammonia water injection in the SNCR system. Due to the temperature field in the decomposition furnace of the cement kiln The distribution is more complicated. Due to the change of working conditions, the temperature at different sections of the furnace changes in real time in different time periods, and the temperature difference at different sections of the calciner spray gun is also large. The SNCR system often cannot capture the denitrification temperature range well. Utilization will not be sufficient. Ammonia, a toxic substance, is easily volatilized from ammonia water. Ammonia escape emission standards have also begun to be included in the emission requirements of individual provinces. The SNCR system increases the amount of ammonia sprayed to improve removal efficiency. At the same time, ammonia escape volume will inevitably increase

[0004] The temperature measuring device in the existing SNCR denitrification system is generally a thermocouple with limited length and limited insertion depth, which cannot accurately measure the temperature distribution at different positions in the furnace, and because the distance between the thermocouple and the ammonia spray gun is very long, measuring The temperature of the heated flue gas has changed when it flows to the spray gun, and the time for the thermocouple to feed back to the computer and the time for the computer to issue instructions to the spray gun are both long, and the flow rate of the spray gun is determined according to the initial temperature. This leads to the fact that the amount of ammonia injection cannot be determined according to the actual temperature of the flue gas, which makes the control of denitrification difficult and the control flexibility is poor, which needs further improvement

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