CN205392141U - A device that is used for low temperature flue gas denitration's ozone to generate hydroxyl free radical - Google Patents

Abstract

The utility model discloses a device that is used for low temperature flue gas denitration's ozone to generate hydroxyl free radical, including water storage tank, charge pump, gas pitcher, ozone generator, flue and absorption tower, characterized in that: still include the catalyst of heater, gas mixing room and area companion's heat facility, the heater turns into the vaporous water with the aqueous water of charge pump suction, and ozone that ozone generator produced gets into the gas mixing room the carrier gas is carried under, the vaporous water with contain the carrier gas intensive mixing of ozone after, under the effect of catalyst, the partial ozone in the gas mixture is the hydroxyl free radical that the oxidability is stronger with vaporous water catalysis activation, entering flue gas pipeline carries out denitration reaction. The utility model discloses a device utilizes the mist that carries ozone, hydroxyl free radical to carry out denitration reaction to the flue gas, big, when the quantity the is low NO of quantity when having solved the ozone oxidation denitration (i) x (i) the desorption rate low with the not thorough problem of oxidation absorption, improved the low temperature flue gas in NO (i) ( oxidation absorption efficiency has i) reduced ozone denitration cost to x by a wide margin.

Description

A device for generating hydroxyl radicals from ozone for low-temperature flue gas denitrification

technical field

The utility model belongs to the technical field of ozone utilization in a low-temperature flue gas denitrification system, in particular to a device for generating hydroxyl radicals by reacting ozone with gaseous water.

Background technique

In recent years, large areas of severe smog have frequently occurred in my country, which has seriously affected social and economic development and the lives and health of the people. Nitrogen oxides in the atmosphere are one of the main components of haze. In addition to coal-fired power plants and motor vehicles, industrial emissions also account for a large proportion of nitrogen oxide emissions. Typical industrial emission sources include coking plants, sintering machines, kilns and various small and medium-sized boilers. Controlling and eliminating nitrogen oxides in low-temperature flue gas from such emission sources is an urgent and realistic demand.

Selective Catalytic Reduction (SCR) technology is commonly used for flue gas denitrification of coal-fired power plant boilers. SCR technology requires flue gas temperature at 300-400°C, which is not suitable for low-temperature (<300°C) flue gas from coking plants, sintering machines, kilns and small and medium-sized boilers. The emission control technologies of nitrogen oxides in low-temperature flue gas include low-temperature SCR method and advanced oxidation absorption method using ozone (O ₃ ), both of which are currently in the pilot demonstration stage. Due to the complex composition of low-temperature flue gas, which contains more particulate matter and oily components, it is easy to block the catalyst pores and cause catalyst poisoning. The advanced oxidation absorption method using ozone (O ₃ ) has become the development direction of low-temperature flue gas denitrification.

The oxidation-reduction potential of ozone is 2.07V, which is very oxidizing, but lower than that of hydroxyl radicals. During the oxidation process, the oxygen atoms carried by the ozone are used up, and the remaining oxygen atoms can be combined into oxygen, so there is no secondary pollution during use. However, in the denitrification process, there are problems of large dosage and high operating costs, and reducing the dosage will generate more NO ₂ instead of easily absorbed high-valence N ₂ O ₅ , resulting in incomplete denitrification.

The utility model patent document with the patent number CN201410038721.1 uses ozone to be directly sprayed and combined with nitric acid to perform a spray absorption process to remove nitrogen oxides in boiler flue gas. The amount of ozone injected and the nitrogen oxides in flue gas The molar ratio is as high as 2.5, and the denitrification efficiency can reach 90%. The amount of ozone used in this method is far greater than the theoretically calculated amount, resulting in high operating costs for ozone denitrification.

In the patent document with the publication number CN102247750A, ozone is directly sprayed into the flue gas, and potassium permanganate is added during the flue gas absorption process, which acts synergistically with ozone to oxidize and absorb SO ₂ and NO _x in the absorption tower. The method dissolves potassium permanganate into the absorption liquid, and the potassium permanganate liquid catalyst is not suitable for recovery and recycling, and may cause other environmental problems.

The patent document with the patent number CN201410458290.4 also directly sprays ozone into the flue gas, then introduces the flue gas into the aqueous solution containing FeSO ₄ , and sprays H ₂ O ₂ in the direction opposite to the flow of the flue gas. NO and SO ₂ in the gas are oxidized by ozone and H ₂ O ₂ to generate nitric acid and sulfuric acid respectively. This method introduces iron ion catalysts into the absorption liquid, which is not suitable for recovery and recycling.

Contents of the invention

In order to overcome the shortcomings of the above-mentioned technical problems, the utility model provides a device for generating hydroxyl radicals from ozone used in low-temperature flue gas denitrification.

The device for generating hydroxyl radicals by ozone for low-temperature flue gas denitrification of the present utility model includes a water storage tank, a feed pump, an air tank, an ozone generator, a flue and an absorption tower, and the feed pump is used to convert the water storage tank The water in the tank is drawn out, and air or oxygen is stored in the gas tank as the gas source of the ozone generator, and the flue is used to introduce the flue gas containing NO _x to be purified; it is characterized in that: it also includes a heater, a gas mixing chamber and catalyst with heat tracing device, the heater converts the liquid water pumped in by the feed pump into gaseous water, and passes it into the gas mixing chamber; the ozone generated by the ozone generator enters the gas mixing chamber under the carrier gas, and the gaseous water After the water and the ozone-containing carrier gas are fully mixed, they enter the catalyst with a heat tracing device; under the action of the catalyst, part of the ozone and gaseous water in the mixed gas are catalytically activated into more oxidizing hydroxyl radicals, carrying ozone, hydroxyl The mixed gas of free radicals enters the flue gas pipeline for denitrification reaction, and the denitrification products enter the absorption tower for absorption by lye.

The beneficial effects of the utility model are: the utility model is used for the device for generating hydroxyl radicals from ozone for denitrification of low-temperature flue gas. Firstly, the carrier gas carrying ozone is fully mixed with gaseous water, and then the mixed gas is passed into the heating device. Under the action of the catalyst, part of the ozone and gaseous water are activated into more oxidizing hydroxyl radicals, and finally the flue gas is denitrated by the mixed gas carrying ozone and hydroxyl radicals, and the hydroxyl radicals oxidize the low-temperature flue gas When the nitrogen oxides in the nitrogen oxides are generated, nitrous acid or nitric acid can be completely absorbed by the alkali solution, which solves the problems of large amount of ozone oxidation and denitrification, low _NOx removal rate and incomplete oxidation absorption when the amount is low, and improves the low-temperature flue gas Oxidation and absorption efficiency of NO _x in the middle, greatly reducing the cost of ozone denitrification.

Description of drawings

Fig. 1 is a structural schematic diagram of the device for generating hydroxyl radicals from ozone for denitrification of low-temperature flue gas according to the present invention.

In the figure: 1 water storage tank, 2 feed pump, 3 heater, 4 gas mixing chamber, 5 catalyst with heat tracing device, 6 gas tank, 7 intake valve, 8 ozone generator, 9 flue, 10 absorption tower.

detailed description

Below in conjunction with accompanying drawing and embodiment the utility model is further described.

As shown in Figure 1, the structural representation of the device for generating hydroxyl radicals by ozone for low-temperature flue gas denitrification of the present invention is provided, which consists of a water storage tank 1, a feed pump 2, a heater 3, and a gas mixing chamber 4. Catalyst 5 with heat tracing device, gas tank 6, air intake valve 7, ozone generator 8, flue 9 and absorption tower 10, liquid water is stored in water storage tank 1, and feed pump 2 is used to The liquid water in the water storage tank 1 is pumped into the heater 3 . The heater 3 is used to vaporize part of the water therein, and its heating temperature is 40-80° C., and the vaporized gaseous water is passed into the gas mixing chamber 4 through a pipeline.

Air or oxygen is stored in the gas tank 6 to prepare the gas source for ozone as the ozone generator 8, and an inlet valve 7 is arranged on the pipeline between the gas tank 6 and the ozone generator 8, and the gas inlet valve 7 can control the gas flow . The ozone generator 8 converts part of the oxygen in the gas source into ozone, and the rest is the carrier gas. The carrier gas containing ozone is passed into the gas mixing chamber 4, mixed with gaseous water, and reaches the state of gaseous water saturation.

The mixed gas containing ozone and saturated gaseous water enters the catalyst 5 with heat tracing device through the pipeline. The heating temperature of the heating device is 40-80 degrees Celsius. The mixed gas carrying ozone and hydroxyl radicals enters the flue 9 to participate in the denitrification reaction, and converts the nitrogen oxides in the flue gas into nitric acid or nitrous acid to achieve flue gas denitrification; The mixed gas is injected in the direction opposite to the direction of flue gas flow. The mixed gas after flue gas denitrification enters the absorption tower 10, and the denitrification product is absorbed in the absorption tower 10 by spraying alkali solution.

The required amount of water is controlled by the feed pump 2 and is calculated according to the saturation humidity of the ozone-containing gas at different temperatures. The gas in the gas tank 6 is air or oxygen, and the amount of ozone produced by the ozone generator is calculated according to the concentration of nitrogen oxides in the flue gas, and the molar ratio of ozone to nitrogen oxides is required to be 0.5-1.0. During the experiment, the flue gas flow rate was about 5000m ³ /h, and the temperature was 80-250°C. According to the detection, the _NOx inlet concentration is 800-1000mg/m ³ . After spraying the carrier gas carrying hydroxyl radicals and ozone, the flue gas enters the absorption tower, and the denitrification product is absorbed by ammonia water, sodium hydroxide or other lye.

The detection of _NOx concentration in the flue gas is carried out by the Kane 9206 flue gas analyzer made in the UK, and the calculation method of the _NOx removal rate is:

SO ₂ or NO _x removal rate = (SO ₂ and NO _x inlet concentration - SO ₂ and NO _x outlet concentration)/SO ₂ and NO _x inlet concentration.

Example 1:

In this embodiment, water is fed into the heater from the water storage tank through the feed pump, and after being heated to 50°C in the heater, the water enters the gas mixing chamber, where it meets the air carrying ozone, and the ozone and nitrogen The molar ratio of the oxide is 0.5, and the ozone and gaseous water are carried by the air into the catalyst installed outside the flue gas pipe with a heating device. The heating temperature is 50°C. Under the action of the catalyst, the ozone and water are decomposed into hydroxyl radicals. Finally, the air carries ozone and hydroxyl radicals into the flue gas pipe to participate in the desulfurization and denitrification reaction. After analysis and calculation, the denitrification efficiency is 85%.

Example 2:

In this embodiment, water is fed into the heater from the water storage tank through the feed pump, and after being heated to 70°C in the heater, the water enters the gas mixing chamber, where it meets the air carrying ozone, and the ozone and nitrogen The molar ratio of the oxide is 0.8, and the ozone and gaseous water are carried by the air into the catalyst installed outside the flue gas pipe with a heating device. The heating temperature is 70°C. Under the action of the catalyst, the ozone and water are decomposed into hydroxyl radicals. Finally, the air carries ozone and hydroxyl radicals into the flue gas pipe to participate in the desulfurization and denitrification reaction. After analysis and calculation, the denitrification efficiency is 90%.

Example 3:

In this embodiment, the water is fed into the heater from the water storage tank through the feed pump, and the water is heated to 90°C in the heater and then enters the mixing chamber, where it meets the oxygen carrying ozone, and the ozone and nitrogen oxides The molar ratio is 1, and the oxygen carries ozone and gaseous water into the catalyst installed outside the flue gas pipe with a heating device. The heating temperature is 80°C. Under the action of the catalyst, ozone and gaseous water are decomposed into hydroxyl radicals, and finally Oxygen carries ozone and hydroxyl radicals into the flue gas pipe to participate in desulfurization and denitrification reactions. After analysis and calculation, the denitrification efficiency is 95%.

When the molar ratio of ozone to nitrogen oxides is 0.5, 0.8, 1.0, the heating temperature of the water in the heater is 50°C, 70°C, 90°C respectively, and the heating temperature is 50°C, 70°C, 80°C, All have higher denitration efficiency, and the higher the molar ratio of ozone to nitrogen oxides, the higher the heating temperature and the heating temperature, the higher the denitrification efficiency.

Claims (1)

1. the device for the ozone generation hydroxyl radical free radical of low-temperature denitration of flue gas, including water storage tank (1), feed pump (2), gas tank (6), ozonator (8), flue (9) and absorption tower (10), feed pump is for extracting out the water in water storage tank, in gas tank, storage has air or oxygen, using the source of the gas as ozonator, flue is to be clean containing NO for passing into _x Flue gas；It is characterized in that: also including heater (3), gas mixer chamber (4) and the catalyst (5) with heating device, the aqueous water of feed pump suction is converted into vaporous water by heater, and passes in gas mixer chamber；The ozone that ozonator produces carries lower entrance gas mixer chamber in carrier gas, after vaporous water and carrier gas ozoniferous are sufficiently mixed, enters the catalyst with heating device；Under the effect of catalyst, part ozone in gaseous mixture and vaporous water catalytic activation are the hydroxyl radical free radical that oxidisability is higher, carry ozone, the mixing gas of hydroxyl radical free radical enters flue and carries out denitration reaction, and denitration product enters absorption tower and absorbs through alkali liquor.