All-working-condition oxynitride ultra-low emission system of thermal power plant

Abstract

The invention provides an all-working-condition oxynitride ultra-low emission system of a thermal power plant, belongs to the field of thermal power plant boiler flue gas oxynitride control, and aimsto solve the problems of low load and excessive NOx emission of a pulverized coal furnace of a thermal power plant in a furnace starting and stopping stage. The system comprises two sets of pulverizedcoal furnace systems, wherein each set of pulverized coal furnace system comprises an air feeder, a pulverized coal furnace, a tail flue, an SCR reactor, an induced draft fan and a chimney which aresequentially connected through pipelines; the tail flues in the two sets of pulverized coal furnace systems are communicated through a connecting flue; a first electric adjusting baffle door and a fifth electric adjusting baffle door are arranged at the two ends of the connecting flue; a second electric adjusting baffle door is arranged on a pipeline for connecting the top of the first tail flue with the connecting flue; a third electric adjusting baffle door is arranged in the middle of the connecting flue; a fourth electric adjusting baffle door is arranged on a pipeline, connected with theconnecting flue, of the top of the second tail flue; and a first temperature sensor and a second temperature sensor are arranged at an inlet of the first SCR reactor and an inlet of the second SCR reactor respectively.

Description

technical field [0001] The invention relates to the technical field of boiler flue gas nitrogen oxide control in a thermal power plant, in particular to an ultra-low emission system of nitrogen oxides in all working conditions of a thermal power plant. Background technique [0002] In recent years, with the development of economy and society, air pollution has become more and more serious. Thermal power plants are an important source of air pollutants. The national environmental protection department has proposed ultra-low emission standards for flue gas pollutants, which require NO x (nitrogen oxides)≤50mg / Nm 3 . For this reason, most thermal power plants have undergone ultra-low emission transformation, and they can basically meet the emission standards under high load. [0003] At the same time, with a large number of new energy generation connected to the grid and the peak-to-valley difference in power loads increasing, new requirements have been put forward for the s...

AI Technical Summary

Problems solved by technology

Flexible peak-shaving operation will inevitably lead to frequent low-load operation of thermal power plants and a significant increase in the number of starts and stops

Although the ultra-low emission transformation has been carried out, the thermal power plant is operating at low load, especially when the boiler is started and shut down. Due to the low flue gas temperature, it cannot meet the temperature requirements of the denitrification reaction (SNCR temperature window is 850°C-1000°C, SCR The temperature window is 300°C-400°C), resulting in excessive use of denitrification reducing agent ammonia (urea), NO x Problems such as excessive emissions and serious ammonia escape

This not only increases the operating cost of the thermal power plant, but also according to the current environmental protection assessment standards, the hourly average concentration of pollutants exceeds the standard for assessment of hundreds of thousands of yuan, which brings serious economic losses to the thermal power plant.

[0004] At present, for the control of flue gas nitrogen oxides, the pulverized coal boiler mainly adopts the SCR denitrification process. x For the problem of exceeding the standard, at present, the main measures are to install the flue gas bypass of the economizer, the water side bypass of the economizer, the separation of the flue by the economizer, the hierarchical layout of the economizer, and the heating of the economizer water supply. , but no matter which method is adopted, the flue gas temperature of the SCR reactor is limited, so it cannot completely solve the problem of low load, especially the NO x The problem of exceeding the standard

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