Denitration using ozone denitration technology

Release date:2018-05-09 Author: Click:

The denitrification treatment was performed using the oxidative denitrification technology of active molecules (ozone) to achieve the target of NOx emission standards. At the same time, the influencing factors of oxygen concentration, cooling water temperature and boiler load change were analyzed. The results showed that when the adsorption pressure and desorption pressure of the VPSA oxygen generator were 40-48 kPa and -45--55 kPa, the oxygen concentration reached the optimal value of over 92%. Cooling water temperature should not exceed 32 °C. At the same time, it is proposed that the NOx emission is always in compliance with the quantitative control of the bench to meet the boiler load changes.

With the promulgation of the “Action Plan for Prevention and Control of Atmospheric Pollution” and the further reduction of the emission of flue gas pollutants from coal-fired boilers, the control of nitrogen oxide NOx has been further improved. SCR is currently a kind of denitrification technology with the most effective removal efficiency. However, when pursuing the goal of lower NOx emission, this technology will cause excessive ammonia slip due to its inherent mixing and uneven flow field. At the same time, as the catalyst loading increases, the conversion rate of SO2 to SO3 increases, and the final smoke The increase of the concentration of NH3 and SO3 in the gas will further aggravate the jamming of the air preheater. The oxidative denitrification technology based on low temperature active molecules is very good to avoid the above problems. Different from SCRs, active molecules (such as O3) are processes for synergistic treatment of flue gas through the oxidation of pollutants such as NO and heavy metals. This process has nothing to do with the type of boiler, the object of treatment is the tail gas of the boiler, the oxidation of NO and heavy metals in the flue gas to high-cost NOx and metal oxides, and then the coordination of pollutants such as NOx, SO2, and heavy metals. Remove.

In this paper, active oxidative denitration technology was used to study the NOx emission control in coal-fired flue gas, and the factors affecting denitration efficiency such as oxygen concentration, cooling water temperature and boiler load change were analyzed.

1, improve the program

 The original boiler of a power plant is 2 sets of 35t/h and 1 set of 50t/h chain furnace. The original wet desulfurization system uses a set of limestone gypsum method for SO2 removal. The active molecular oxidative denitration technology is applied to the tail flue after the flue gas confluence. Therefore, only the flue gas flow rate and nitrogen oxide content of the tail flue need to be considered, which is independent of the combustion mode of the boiler. Using the original desulfurization equipment, only the original flue gas desulfurization tower inlet flue was modified and an active molecular reactor was installed. The rest of the transformations are new devices as shown in Figure 1. Oxygen system, active molecular system, cooling water system and electrical and instrument control auxiliary systems. The oxygen system uses an adsorbent to separate oxygen and nitrogen in the air by adsorption and desorption to produce a higher concentration of oxygen. After pressurization, deoiling, and dust removal, the oxygen enters the active molecular generator, and finally the active molecule (O3) is generated through partial discharge in the discharge chamber. The discharge of high-voltage electricity to the oxygen in the discharge chamber generates a large amount of heat, so external cooling water is required to heat-treat the discharge chamber to increase the concentration of the active molecule (O3).

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