Simultaneous flue gas desulfurization and denitrification method

Abstract

The invention relates to a method for simultaneously performing desulfurization and denitrification on smoke gas in the technical field of environmental protection. The method comprises the following steps of: enabling the smoke gas containing SO2 and NO after state adjustment and particles of a transition metal oxide or the particles of a mixture containing the transition metal oxide to be fully mixed and be in contact reaction, wherein the SO2 is oxidized to SO3 in a catalytic manner, the NO is oxidized to NO2 in the catalytic manner, most of the SO3 and the NO2 are subjected to direct hydration reaction with water, then finally exist on the surfaces of the particles in the form of sulfates and nitrates or sulfuric acid and nitric acid and are further removed from the smoke gas, and the residual SO3 and the NO2 in the smoke gas, which do not participate in the hydration reaction, are purified along with the smoke gas by alkali liquor absorption; and recovering the particles which are discharged from a reactor, and then recycling the particles. According to the method disclosed by the invention, the high-efficient simultaneous desulfurization and denitrification can be realized, and the method can be suitable for deep desulfurization and denitrification of the smoke gas.

Description

technical field [0001] The invention relates to a method in the technical field of environmental protection, in particular to a 2 , NO flue gas simultaneous desulfurization and denitrification method. Background technique [0002] Sulfur dioxide and nitrogen oxides are currently the most important gaseous pollutants with large content and wide influence in the air pollutants. They are the main cause of acid rain, and they are also the secondary PM in the atmosphere. 2.5 The main cause of particulate matter. By 2011, although my country had taken many measures in flue gas purification, the total emissions of sulfur dioxide and nitrogen oxides in that year still reached 22.179 million tons and 24.043 million tons, both of which far exceeded the national environmental capacity. About 90% of the sulfur dioxide and 70% of the nitrogen oxides come from the direct combustion of coal. However, from the perspective of energy consumption, nearly 70% of my country's energy structure...

AI Technical Summary

Problems solved by technology

[0005] 1. Gaseous SO in flue gas 2 Must be absorbed into the droplet first, and the Ca(OH) in the droplet 2 A neutralization reaction occurs to generate CaSO 3 , which is the first gas-liquid reaction; but because SO 2 Solubility in water is relatively low, so gaseous SO 2 Dissolving into the liquid phase is slow and time-consuming. In order to maintain high desulfurization efficiency, a large amount of alkaline mist must be sprayed into the flue gas to ensure sufficient gas-liquid contact area to increase the probability of gas-liquid collision. Guaranteed entry of SO into the droplet 2 The mass transfer migration and reaction time required to react with the base in the droplet, which define the minimum residence time that the droplet must remain in the reactor

[0006] 2. In order to make the CaSO in the droplet 3 Stabilization also requires the introduction of a large amount of air to oxidize the CaSO in the droplets 3 Become CaSO 4 instead of stabilization; due to the lower solubility of oxygen in water, this is a more difficult gas-liquid reaction and thus requires a longer reaction time

But the defect of this invention is: the cost of activated carbon fiber is high, and it must be replaced regularly; the dust content of flue gas entering the reactor is required to be low, otherwise it is very easy to pollute, wear or block the pores of activated carbon fiber and reduce its performance; sulfur oxidation The removal of pollutants and nitrogen oxides must be carried out separately in two-stage reactors, resulting in complicated equipment; the regeneration of activated carbon fibers is also carried out in the reactor for removing pollutants, and the dilute acid produced by washing is highly corrosive, which is harmful to the reactor. The anti-corrosion performance requirements are high, and the activated carbon fiber must be washed in the reactor first and then dried with hot air during the regeneration process, so it is difficult to achieve continuous treatment of flue gas

But the defect of this invention is: this process belongs to the wet process, and the gas-liquid mass transfer efficiency is low. To ensure the removal efficiency, it is necessary to ensure a good gas dispersion effect, resulting in high requirements for the gas dispersion device and a huge reactor; With the pH value in the slurry, the SO 2 The solubility in it is significantly reduced, and the utilization rate of the ore pulp is low; the dilute acid and ore powder in the ore pulp have serious corrosion and wear on the equipment; the regeneration of the metal chelating agent is difficult and the loss is large; the pressure loss in the reactor is large, which is not conducive to large-scale production Engineering application

[0015] Facing the more stringent emission standards of sulfur dioxide and nitrogen oxides in exhaust gas, the above-mentioned existing flue gas desulfurization and denitrification technologies are all incompetent due to their own shortcomings.