Intelligent Zoning Spraying Ammonia Measurement and Control System
Intelligent Partition Ammonia Measurement and Control System

Through zoned control over ammonia spraying quantity, the SCR intelligent zoned ammonia spaying control system increases the uniformity of NOx concentration distribution at SCR outlet, avoids partial insufficient or excessive ammonia spraying at SCR inlet and, while meeting the requirements of ultra-low NOx emission standard, decreases ammonia escape rate, alleviates corrosion and ash deposition of boiler rear equipment, and prolongs the life of denitrification catalyst. The specific realization way is as follows: add a zoned leveling valve (pneumatic or electric regulation) and a zoned ammonia flow meter between conventional ammonia spaying pipe total control valve and branch regulating valve; perform patrol measurement on the NOx/O2 concentration (temperature optional) distribution at SCR outlet; get the deviation percentage of ammonia flow at different zones of SCR inlet through the operation of control system, the value of which will be the control target value; and perform closed-loop regulation of zoned leveling valves to enable the compliance of measured flow change percentage of zoned ammonia flow meter with the control target value.

  • The ammonia splaying zoning design is based on the phenomenon of random molecule diffusion, each zoned ammonia splaying section is in an approximate square, i.e., the dimensions at different directions are close to each other as much as possible, and generally the SCR at each side is divided into three 3-5 zones for controlling ammonia splaying quantity.

  • The single-point measurement time of NOx/O2 concentration at SCR outlet (temperature optional) is 5-10s, and each side has a set of instruments to measure 8-12 flue/gas mixture samples at SCR outlet along the width direction respectively by switching the pipeline valve groups; each patrol inspection period is 1-2min.

  • A measurement adjustment period is less than 5min, and it is recommended to measure and adjust periodically at an interval of 10-60min (30min in default and optional in practice), or the measurement and adjustment can be triggered automatically by the signals of work condition changes by switching to the mode of intelligent operation.

  • Utilizing differential pressure at the flue/gas side of air pre-heater to perform large flow automatic sampling, which needs no additional power equipment and heat tracing pipes, reduce malfunction points and increase system liability.

  • Adopting multiple technical measures to eliminate the possibility of blockage of pipelines and measurements instruments, including large dip angle design for sampling pipelines, using efficient nano insulation materials, timing back flushing, etc.

  • The switching valve group in sampling pipeline is adaptive to high-temperature and dusty application environments, and is wear-free tightly closed.

  • The instruments for measuring NOx/O2 concentration at SCR outlet use straight insertion design, work directly in high temperature, have the function of online automatic calibration, and are featured by simple structure and no need for maintenance.

  • Zoned ammonia flow meter adapts to the application environments of short straight pipe, low flow speed, high temperature and easy condensation (when urea as reducing agent).

  • The distributed measurement of NOx/O2 concentration (temperature optional) is finer, mainly used for guiding the manual adjustment of branch regulating valves and replacing conventional ammonia splaying adjustment optimization test.

  • The optimization control over ammonia splaying quantity control valve is included for implementation to increase the automatic controty of ammonia splaying.

Contact service team
  • Contact:Mr Shi
  • Contact number:13776673365