Circulating fluidized bed boiler device that effectively reduces emissions of nitrogen oxides and particulate matter

Abstract

The invention discloses a circulating fluidized bed boiler device capable of effectively reducing emission of nitrogen oxide and particulate matter. The circulating fluidized bed boiler device comprises a boiler, a cyclone separator, a deduster, an induced draft fan, a primary air supply system and a secondary air supply system which are connected in sequence. A burn-out chamber is arranged at an outlet of the cyclone separator. Over fire air is introduced into the burn-out chamber. A smoke recirculation pipe is drawn out behind the induced draft fan. The primary air supply system and the secondary air supply system are connected to the smoke recirculation pipe in parallel. According to the circulating fluidized bed boiler device capable of effectively reducing emission of the nitrogen oxide and the particulate matter, a smoke recirculation mode is adopted, part of the smoke is mixed into primary air and secondary air, generation of NOx is effectively reduced, grading of the secondary air in the height direction and in the horizontal direction is achieved through the secondary air arrangement mode, the burn-out chamber is arranged at the outlet of the separator, the carbon content of flying ash is reduced, and the contradiction between NOx emission reduction and high carbon content of the flying ash due to the fact that oxygen content in a combustion furnace is reduced can be effectively solved.

Description

technical field [0001] The invention belongs to the technical field of boiler combustion, and in particular relates to a circulating fluidized bed boiler device for effectively reducing nitrogen oxide and particle emissions. Background technique [0002] In the nitrogen oxides produced during boiler combustion, NO accounts for more than 90%, and nitrogen dioxide accounts for 5%-10%. The production mechanism is generally divided into the following three types: (1) Thermal type: During combustion, nitrogen in the air is Oxidation, with the increase of the reaction temperature T, the reaction rate follows an exponential law. When T<1500°C, the amount of NO produced is very small, and when T>1500°C, the reaction rate increases for every 100°C increase in T. 6-7 times larger; (2) Instantaneous reaction type: CH free radicals generated by pyrolysis of hydrocarbons in fuel volatiles can react with nitrogen in the air to form HCN and N, and then react with oxygen to form at an...

AI Technical Summary

Problems solved by technology

The circulating fluidized bed boiler has the remarkable characteristics of low nitrogen oxide emissions. The main reason is that the combustion temperature is low, only 850-1000 ℃, so the thermal NO x The second is that the solid bed material in the furnace has a great influence on NO along the height of the furnace. x The third is that circulating fluidized bed boilers are generally designed in a graded air supply mode, so that the dense phase area is in a reducing atmosphere, but although the traditional layout of secondary air inlet ducts can meet the requirements of the boiler for secondary air volume, However, the disturbance effect of the secondary air on the flue gas in the furnace is poor, which is not conducive to the full combustion of fuel in the furnace, and there is still room for improvement of circulating fluidized bed boilers

[0004] The invention patent with application number 201310351741X discloses a horizontal circulating fluidized bed heat transfer oil furnace, which includes a feeding device, a main combustion chamber, a secondary combustion chamber, a burnout chamber, a cyclone separator, a separator outlet flue and The induced draft fan, the secondary air device is arranged at the junction of the dense-phase area and the dilute-phase area of ​​the main combustion chamber, below the auxiliary combustion chamber and the burnout chamber, and the nitrogen oxides are effectively controlled through the ratio of the primary air to the secondary air. However, after two combustions in the boiler-burnout chamber, the air volume is particularly large when entering the separator, which will affect the effect of the cyclone separator, so that some large particles are not separated, and are directly discharged with the flue gas, and the fly ash The carbon content is relatively high, and at the same time increases the load of the subsequent dust collector

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