CN210009815U - A device for removing NOx, SOx and Hg based on oxidation and condensation and absorption - Google Patents

Abstract

The utility model discloses a device for removing NOx, SOx and Hg based on an oxidation method and condensation and absorption. Under the synergistic effect of hydrogen oxide, NOx, SOx and Hg in the flue gas are oxidized to high-valence substances, and then the flue gas flows through the secondary flue gas cooler to further cool down. The ash particles and water vapor are condensed and absorbed in the flue gas fly ash or the alkaline oxides injected by the flue, and the condensed and absorbed ash particles enter the electrostatic precipitator for removal, so as to achieve the purpose of simultaneous desulfurization, denitration and mercury removal; the utility model It realizes the synergistic removal of pollutants in flue gas by ozone and hydrogen peroxide. It has high adaptability to coal, is simple, efficient, and has no liquid waste. It has little corrosion to equipment, low maintenance cost, and long service life. Wet desulfurization can significantly reduce the generation of white "smoke plumes".

Description

A device for removing NOx, SOx and Hg based on oxidation and condensation and absorption

technical field

The utility model belongs to the technical field of environmental pollution control of nitrogen, sulfur oxides and heavy metal mercury, in particular to a device for removing _NOx , SOx and Hg based on _an oxidation method and condensation and absorption.

Background technique

The large amount of sulfur oxides, nitrogen oxides, mercury and organic pollutants produced by coal combustion are the main sources of air pollution, and also cause great harm to human health. The increasing environmental protection requirements put forward higher requirements for the treatment of pollutants in coal-fired power plants. At present, wet desulfurization is the most widely used desulfurization process due to its high desulfurization efficiency, but there are disadvantages such as complicated process, huge equipment investment, high water and electricity consumption, and high operating cost. Compared with wet desulfurization, semi-dry desulfurization and dry desulfurization have the characteristics of small investment and low energy consumption, but their removal effect is not ideal. There are two main types of flue gas denitrification technologies: selective catalytic reduction and selective non-catalytic reduction. The desulfurization efficiency of the selective catalytic reduction method can reach 80%-90%, but the catalyst cost is high and needs to be replaced regularly. In addition, the operating temperature is required to be as high as 300-450°C, and the engineering application is limited. However, selective non-catalytic reduction is more difficult to apply in practice due to the low denitration efficiency and the higher temperature required for process operation. The above-mentioned technologies are all single pollutant control, which have great limitations: each system operates independently, ignoring the synergy between systems, and it is difficult to achieve ultra-clean emissions; the system is complex and huge, with high operation and maintenance costs and energy consumption. , High power consumption. Therefore, it is urgent to develop a new method for deep desulfurization, denitration and mercury removal, with simple and reliable process, low operating cost, and engineering application.

CN201610137024.0 provides a method and device for applying two or three technologies of plasma desulfurization and denitration technology, hydrogen peroxide catalytic activation technology and ozone advanced oxidation desulfurization and denitration technology in one solution. The utility model ignores the synergistic effect of ozone and hydrogen peroxide in the oxidation process, and does not consider the decomposition of ozone when the temperature is above 150 ° C. At the same time, hydrogen peroxide needs a catalyst to generate hydroxyl radicals, and the catalyst is expensive and needs to be replaced regularly. The method of simply using ozone to oxidize nitrogen oxides and sulfur oxides in flue gas can achieve higher desulfurization and denitrification efficiency, but the price of ozone preparation is expensive.

SUMMARY OF THE INVENTION

In view of the above problems, the purpose of this utility model is to provide a device for removing _NOx , SOx and Hg based on oxidation method and condensation and absorption, which can remove _NOx , _SOx and heavy metal _mercury etc. in the flue gas at the outlet of the boiler body To achieve deep oxidation and deep cooling, and by spraying alkaline oxide powder into the flue, the oxidized high-valent substances in the flue gas are condensed and absorbed into the ash particles to achieve ultra-clean emission.

In order to achieve the above object, the technical scheme adopted by the present utility model is as follows:

A device for removing _NOx , _SOx and Hg based on oxidation method and condensation and absorption, including air preheater 1, the air preheater 1 is arranged in the flue at the tail of the boiler, and the boiler body passes through the flue and electrostatic precipitator. The flue gas inlet of the cooler 14 is connected; the front end of the horizontal flue is arranged with a first-level flue gas cooler 3 , and the flue gas opening in the middle is communicated with the oxidant mixer 9 . The shell side of the oxidant mixer 9 is communicated with the oxygen tank 4, the ozone generator 5, the flow valve and the pump are arranged on the communication pipeline, and the pipe side is connected with the hydrogen peroxide vapor generator 8, the peristaltic pump 7 and the hydrogen peroxide solution storage tank accordingly. 6 is connected; the lower part of the side wall of the vertical flue is opened with a flue gas extraction port, and after being pressurized by the fan 11, the solid alkaline oxide powder is carried from the upper opening of the vertical flue and sent to the blowing device 12 arranged in the vertical flue or Use compressed air to carry the solid oxide powder into the blowing device 12; a secondary flue gas cooler 13 is arranged in the horizontal flue communicated with the electrostatic precipitator 14; The ash in the ash falling port 15 is sent to the ash treatment device 10 together; the flue gas outlet of the electrostatic precipitator 14 is communicated with the induced draft fan 16 and the chimney 17 through the flue.

The first-stage flue gas cooler 3 is used to ensure that the temperature of the flue gas is lowered to 90-100° C., so as to improve the efficiency of condensing, absorbing and removing NO _X and SO _X in the flue gas.

The secondary flue gas cooler 13 lowers the flue gas temperature to 80-85 degrees Celsius, and uses thermophoretic force and diffusive electrophoresis force to condense the ash particles in the flue gas into large particles, thereby improving the removal efficiency of the electrostatic precipitator.

The secondary flue gas cooler 13 can be a close-packed tube heat exchanger or an H-shaped finned tube heat exchanger, a double H-shaped finned tube heat exchanger, a 4H-shaped finned tube heat exchanger or a spiral finned heat exchanger. Sheet tube; these types of heat exchangers have a rectifying effect on the flue gas, which can improve the dust removal efficiency of the electrostatic precipitator.

The oxidant mixer 9 is designed with reference to the structure of the ejector. The hydrogen peroxide vapor goes through the tube process and the ozone goes through the shell process. The hydrogen peroxide vapor flash temperature is 135-145°C, and the ozone decomposes seriously at this temperature. The structure of the device can avoid the ineffective decomposition of hydrogen peroxide vapor and ozone to a large extent, and improve the oxidation efficiency of nitrogen and sulfur oxides.

After the air preheater 1 heats the air, a part of the hot air can be transported to the induced draft fan 16 and mixed with the flue gas, thereby avoiding the generation of "smoke plume".

The surface of the secondary flue gas cooler 13, the oxygen tank 4, the ozone generator 5, the hydrogen peroxide solution storage tank 6, the peristaltic pump 7, the hydrogen peroxide vapor generator 8, the oxidant mixer 9, the conveying pipeline, the nozzle , the valve, the injection device 12 and the conveying pipeline, the inner surface of the electrostatic precipitator 14 and the mixing area of the oxidant and the flue gas in the flue are coated with an inert wear-resistant material coating.

The inert wear-resistant material is silica fluoroplastic or ceramic.

The blowing device 12 is composed of four powder conveying pipes arranged around the flue. Each powder conveying pipe is provided with a number of holes. At the same time, it plays the role of disturbing the flow of flue gas and strengthening the mixing of solid alkaline oxides and flue gas.

The described method for desulfurization, denitration and mercury removal based on an oxidation method and a device for condensing and absorbing NOx, SOx, and Hg for removing NOx, SOx, and Hg: The oxidant sprayed into the horizontal flue by the oxidant mixer 9 is fully mixed, wherein the hydrogen peroxide vapor is prepared by the hydrogen peroxide vapor generator 8, the ozone is prepared by the ozone generator 5, and the hydrogen peroxide vapor and ozone are sent into the oxidant in a certain proportion to mix The device 9 is fully mixed and injected into the horizontal flue; under the synergistic action of _hydrogen peroxide and ozone, _NOx , SO2, and Hg in the flue gas are deeply oxidized to high-valence substances, and then the flue gas flows through the secondary flue gas cooler 13 Further cooling; with the decrease of flue gas temperature, gaseous acidic oxides and water vapor in the flue gas are absorbed and condensed in the flue gas fly ash or basic oxides (such as calcium oxide) injected by the flue, condensed and absorbed The ash particles after entering the electrostatic precipitator 14 along with the flue gas are removed to achieve the purpose of desulfurization, denitrification and mercury removal at the same time; in order to ensure the full mixing of the flue gas and solid alkaline oxides, a spray device 12 is installed on the top of the vertical flue; During the cooling process of the secondary flue gas cooler 13, the condensation and absorption are further intensified under the action of the thermophoretic force and the diffusive electrophoretic force between the tubes, and the purpose of rectification is achieved; It is sent to the ash treatment device 10 together, and is reused through subsequent processing; the purified flue gas is mixed with a part of the hot air from the air preheater 1 and then sent to the chimney 17 through the induced draft fan 16 to be discharged into the atmosphere to achieve whitening. the goal of.

The molar ratio of the solid basic oxide powder to the pollutants in the flue gas is (1.1 to 1.3): 1. When the content of the basic oxide in the flue gas fly ash is sufficient, the blowing device (12) stops spraying the smoke. Spray solid alkaline oxide powder in the channel;

The mixing ratio of ozone and hydrogen peroxide in the oxidant is (0.6-1.5): 1;

The molar ratio of the hydrogen peroxide and ozone mixed gas to the pollutants in the flue gas is (0.7-1.2):1.

Compared with the prior art, the utility model has the following advantages:

1) The utility model adopts the dry process of oxidation method, deep cooling and absorption condensation, utilizes cheap hydrogen peroxide to replace part of ozone as an oxidant to deeply oxidize NOx, SOx and heavy metal mercury in the flue gas, and utilizes ozone and superoxide. The synergistic effect of hydrogen oxide enhances the oxidation efficiency of the oxidant and improves the removal efficiency of flue gas pollutants.

2) The utility model is a dry process, which realizes the deep cooling oxidation, condensation, absorption and removal of NOx, SOx and heavy metal mercury at the same time, the process is simple and efficient, and no liquid waste is generated, which minimizes the effect of oxidation products on equipment. Corrosion damage.

3) The utility model fully considers the ineffective decomposition of ozone caused by the mixing of flashed hydrogen peroxide and ozone, and cleverly utilizes the ejector structure in the oxidant mixer to avoid the decomposition of ozone due to high temperature as much as possible.

4) In this utility model, a part of the hot air heated by the air preheater is mixed with the flue gas behind the induced draft fan and discharged together through the chimney, avoiding the generation of "smoke plume".

Description of drawings

Figure 1 is a schematic diagram of a device for removing _NOx , _SOx and Hg based on oxidation and condensation and absorption.

Fig. 2 is a top view of the blowing device.

In the figure: 1. Air preheater; 2. Control valve; 3. Primary flue gas cooler; 4. Oxygen tank; 5. Ozone generator; 6. Hydrogen peroxide solution storage tank; 7. Peristaltic pump; 8 , hydrogen peroxide vapor generator; 9, oxidant mixer; 10, ash treatment device; 11, fan; 12, injection device; 13, secondary flue gas cooler; 14, electrostatic precipitator; 15, ash fall mouth; 16, induced draft fan; 17, chimney.

Detailed ways

The structure and working principle of the present utility model will be further described below in conjunction with the accompanying drawings.

As shown in Fig. 1, the present invention is a device for removing _NOx , SOx and Hg based on oxidation method and condensation and absorption, including _an air preheater 1, which is arranged in the flue at the tail of the boiler , the boiler body is communicated with the flue gas inlet of the electrostatic precipitator 14 through the flue; The shell side of the oxidant mixer 9 is communicated with the oxygen tank 4, the ozone generator 5, the flow valve and the pump are arranged on the communication pipeline, and the pipe side is connected with the hydrogen peroxide vapor generator 8, the peristaltic pump 7 and the hydrogen peroxide solution storage tank accordingly. 6 Connected; a flue gas extraction port is opened at the lower part of the side wall of the vertical flue, and after being pressurized by the fan 11, the alkaline solid oxide powder is carried from the upper opening of the vertical flue and sent to the blowing device 12 arranged in the vertical flue; A secondary flue gas cooler 13 is arranged in the horizontal flue communicated with the electrostatic precipitator 14; the ash in the electrostatic precipitator 14 and the ash in the ash falling port 15 arranged at the bottom of the vertical flue are sent to the ash treatment device 10; The flue gas outlet of the electrostatic precipitator 14 is communicated with the induced draft fan 16 and the chimney 17 through the flue.

As shown in FIG. 2 , the blowing device 12 is composed of four powder conveying pipes arranged around the flue. Each powder conveying pipe is provided with a number of holes, and the solid alkaline oxide powder is ejected from the holes in the smoke. The flow pattern of the four-wall tangent circle is formed in the channel, and at the same time, it plays the role of disturbing the flow of flue gas and strengthening the mixing of solid alkaline oxides and flue gas.

The method of the utility model for desulfurization, nitrification and mercury removal based on the oxidation method and the device for removing _NOx , _SOx and Hg by condensation and absorption is as follows:

After the flue gas at the outlet of the boiler body is cooled by the primary flue gas cooler 3 in the horizontal flue, it is fully mixed with the oxidant sprayed into the horizontal flue by the oxidant mixer 9, wherein the hydrogen peroxide vapor is prepared by the hydrogen peroxide vapor generator 8, Ozone is prepared by the ozone generator 5, and the hydrogen peroxide vapor and ozone are sent into the oxidant mixer 9 in a certain proportion to be fully mixed and sprayed into the horizontal flue; under the synergistic effect of _hydrogen peroxide and ozone, _NOx , SO2 in the flue gas , Hg is deeply oxidized into high-valence substances, and then the flue gas flows through the secondary flue gas cooler 13 to further cool down; with the decrease of the flue gas temperature, the gaseous acid oxides and water vapor in the flue gas are absorbed and condensed in the flue gas. In the ash or the alkaline oxides (such as calcium oxide) blown by the flue, the condensed and absorbed ash particles enter the electrostatic precipitator 14 for removal along with the flue gas, so as to achieve the purpose of simultaneous desulfurization, denitration and mercury removal. In order to ensure the full mixing of flue gas and solid alkaline oxides, a spray device 12 is installed on the top of the vertical flue; during the cooling process of the secondary flue gas cooler 13, it is further intensified under the action of the thermophoretic force and diffusional force between the tubes. The ash collected by the electrostatic precipitator 14 and the ash in the ash drop port 15 are sent to the ash and slag treatment device 10 together, and are reused through subsequent processing. The purified flue gas is mixed with a part of the hot air from the air preheater 1 and sent to the chimney 17 through the induced draft fan 16 to be discharged into the atmosphere to achieve the purpose of whitening.

Example 1:

The exhaust smoke from the boiler body is cooled to 98°C through the primary flue gas cooler 3, and then fully mixed with the oxidant sprayed into the horizontal flue by the oxidant mixer 9. The hydrogen peroxide vapor is prepared by the hydrogen peroxide vapor generator 8, and the ozone is The ozone generator 5 is prepared, and the hydrogen peroxide vapor and ozone are sent to the oxidant mixer 9 at a ratio of 1:1.5 to be fully mixed and sprayed into the horizontal flue; The concentration of SO ₂ is 2000mg/m ³ , the concentration of NO _X is 300mg/m ³ , the concentration of Hg is 20μg/m ³ , and the molar ratio of the mixed gas of ozone and hydrogen peroxide to the pollutants in the flue gas is 1.2:1. Under the action of oxidant, NO _X , SO ₂ and Hg in the flue gas are deeply oxidized into high-valence substances; then they flow through the secondary flue gas cooler to cool down to 85°C. During the cooling process, the gaseous state in the flue gas Acids and water vapor are absorbed and condensed into alkaline oxides in flue injection or flue gas fly ash; the molar ratio of alkaline oxide powder to pollutants in flue gas is 1.2:1; after condensation and absorption The ash particles enter the electrostatic precipitator 14 to realize the removal of pollutants in the flue gas, and the purified flue gas is mixed with a part of the hot air from the air preheater 1 and then transported to the chimney 18 through the induced draft fan 16 to be discharged into the atmosphere to achieve elimination. white purpose. By detecting the pollutant concentration before and after the flue gas treatment, it can be known that the desulfurization efficiency of the process is 100%, the denitration efficiency is 95%, and the mercury removal efficiency is 100%.

Example 2:

The exhaust smoke from the boiler body is cooled to 95°C through the primary flue gas cooler 3, and then fully mixed with the oxidant sprayed into the horizontal flue by the oxidant mixer 9. The hydrogen peroxide vapor is prepared by the hydrogen peroxide vapor generator 8, and the ozone is The ozone generator 5 is prepared, and the hydrogen peroxide vapor and ozone are sent into the oxidant mixer 9 at a ratio of 1:1.2 to be fully mixed and injected into the horizontal flue; The concentration of SO ₂ is 2000mg/m ³ , the concentration of NO _X is 300mg/m ³ , the concentration of Hg is 20μg/m ³ , and the molar ratio of the mixed gas of ozone and hydrogen peroxide to the pollutants in the flue gas is 0.9:1. Under the action of oxidant, NO _X , SO ₂ and Hg in the flue gas are deeply oxidized into high-valence substances; then they flow through the secondary flue gas cooler to cool down to 82°C. During the cooling process, the gaseous state in the flue gas Acids and water vapor are absorbed and condensed into the alkaline oxides in flue injection or flue gas fly ash; the molar ratio of solid alkaline oxide powder to pollutants in flue gas is 1.1:1; condensed and absorbed The ash particles after entering the electrostatic precipitator 14 realize the removal of pollutants in the flue gas. The purified flue gas is mixed with a part of the hot air from the air preheater 1 and then transported to the chimney 18 through the induced draft fan 16 to be discharged into the atmosphere. the purpose of whitening. By detecting the pollutant concentration before and after flue gas treatment, it can be known that the desulfurization efficiency of this process is 99%, the denitration efficiency is 94%, and the mercury removal efficiency is 100%.

Claims (6)

1. NO removal based on oxidation method and coagulation absorption_X、SO_XHg plant comprising an air preheater (1), characterized in that: the air preheater (1) is arranged in a flue at the tail part of the boiler, and the boiler body is communicated with a flue gas inlet of the electrostatic dust collector (14) through the flue; the front end of the horizontal flue is provided with a first-stage flue gas cooler (3), and the middle part of the horizontal flue is provided with a flue opening communicated with an oxidant mixer (9); the shell side of the oxidant mixer (9) is communicated with the oxygen tank (4), the ozone generator (5), the flow valve and the pump are arranged on the communicating pipeline, and the pipe side is sequentially communicated with the hydrogen peroxide steam generator (8), the peristaltic pump (7) and the hydrogen peroxide solution storage tank (6); a flue gas extraction opening is formed in the lower portion of the side wall of the vertical flue, and the flue gas is pressurized by a fan (11) and then carries solid alkaline oxide powder to be sent into a blowing device (12) arranged in the vertical flue from an opening in the upper portion of the vertical flue or uses compressed air to carry solid alkaline oxide powder to enter the blowing device (12); a secondary flue gas cooler (13) is arranged in a horizontal flue communicated with the electrostatic dust collector (14); the ash in the electrostatic dust collector (14) and the ash in an ash falling port (15) arranged at the bottom of the vertical flue are sent into the ash slag processing device (10) together; the smoke outlet of the electrostatic dust collector (14) is communicated with an induced draft fan (16) and a chimney (17) through a flue.

2. According to claim1 the method for removing NO based on oxidation method and coagulation and absorption_X、SO_XHg, comprising: the secondary flue gas cooler (13) adopts a close-packed tube type heat exchanger or an H-shaped finned tube heat exchanger, a double H-shaped finned tube heat exchanger, a 4H-shaped finned tube heat exchanger or a spiral finned tube heat exchanger.

3. The process of claim 1 for the removal of NO based on oxidation and coagulation absorption_X、SO_XHg, comprising: the oxidant blender (9) is designed according to the ejector structure, the hydrogen peroxide vapor passes through the tube side, the ozone passes through the shell side, and the ejector structure is adopted to ensure that the hydrogen peroxide and the ozone are only contacted and mixed at the outlet of the blender.

4. The process of claim 1 for the removal of NO based on oxidation and coagulation absorption_X、SO_XHg, comprising: and inert wear-resistant material coatings are coated on the surface of the secondary flue gas cooler (13), the oxygen tank (4), the ozone generator (5), the hydrogen peroxide solution storage tank (6), the peristaltic pump (7), the hydrogen peroxide steam generator (8), the oxidant mixer (9), the conveying pipeline, the spray head, the valve, the blowing device (12), the conveying pipeline, the inner surface of the electrostatic dust collector (14) and a mixing area of the oxidant and the flue gas in the flue.

5. The method of claim 4 for removing NO based on oxidation and coagulation and absorption_X、SO_XHg, comprising: the inert wear-resistant material is silicon dioxide, fluoroplastic or ceramic.

6. The process of claim 1 for the removal of NO based on oxidation and coagulation absorption_X、SO_XHg, comprising: the blowing device (12) is composed of four powder conveying pipelines arranged around the flue, each powder conveying pipeline is provided with a plurality of holes, solid alkaline oxide powder is sprayed out of the holes to form a four-wall tangent circle flowing form in the flue, and the four-wall tangent circle flowing form simultaneously plays a role in disturbing the flow of flue gas and strengtheningMixing the basic oxide with fume.

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