CN105311925B - Control the extensive Adsorbent modification coupling spraying system of flue gas heavy metal pollutant emission - Google Patents

Abstract

The invention discloses a large-scale modified coupling injection system for adsorbents, which belongs to the technical field of flue gas heavy metal pollutant control. The system mainly includes: storage tank, feeder, feeding device, modified agent tank, modified host, cyclone separator, collecting hopper, feeder, gas-solid mixing accelerator, injection pipeline and air compressor, etc. During work, the adsorbent and medicament are added to the modified host according to a certain proportion, react and undergo chemical modification; the modified adsorbent is controlled by the feeder and enters the gas-solid mixing accelerator; in the gas-solid mixing accelerator, the adsorbent and gas Mix according to a certain ratio, and then spray it into the flue along the conveying pipeline to absorb and remove pollutants in the flue gas. The system is suitable for the removal of heavy metals (mercury, arsenic, lead, cadmium, chromium, etc.) and acid gases such as sulfur trioxide and hydrogen chloride in flue gas. The invention can realize large-scale on-site modification of the adsorbent, and has the characteristics of continuity and sealing.

Description

Large-Scale Adsorbent Modification Coupled Injection for Controlling Emissions of Heavy Metal Pollutants in Flue Gas system

technical field

The patent of the invention belongs to the technical field of emission control of heavy metal pollutants in flue gas, and in particular relates to a large-scale adsorbent modified coupling injection system for controlling the emission of heavy metal pollutants in flue gas. Specifically, it refers to the coupled pneumatic conveying and injection system that realizes large-scale modification of adsorbents in coal-fired power plants and other sites, and removes various pollutants in flue gas through adsorption, such as heavy metals (mercury, arsenic, lead, cadmium, chromium) And strong acid gases (sulfur trioxide and hydrogen chloride), etc.

Background technique

Heavy metals are enriched and difficult to degrade in the environment. The heavy metals and their compounds discharged to the outside world are very harmful to human health and the ecological environment. Taking the heavy metal mercury as an example, mercury pollutants have the characteristics of stable chemical properties and strong volatility. At the same time, mercury pollutants are cumulative in the natural environment and biological organisms, so the problem of mercury pollution in the atmosphere has gradually attracted people's attention. Mercury released from flue gas from coal-fired power plants is the main source of atmospheric mercury pollution. A large amount of gaseous mercury will be formed during coal combustion, and gaseous mercury will be emitted into the atmosphere along with the flue gas. Adsorption of gaseous mercury in flue gas by adsorbent is one of the mainstream mercury pollution control technologies in coal-fired flue gas. In this technology, the adsorbent is generally injected into the flue to absorb the gaseous mercury in the flue gas. Commonly used adsorbents include carbon-based adsorbents such as activated carbon and non-carbon-based adsorbents such as fly ash adsorbents. Adsorption includes physical adsorption and chemical adsorption. The physical adsorption capacity is relatively weak. In order to improve the adsorption capacity of the adsorbent, it is usually necessary to chemically modify the adsorbent.

Activated carbon has a large specific surface area and strong adsorption capacity, but it is expensive. Non-carbon-based adsorbents such as fly ash are industrial solid wastes discharged from coal-fired power plants after combustion. They are cheap and have a large stock. The utilization rate of fly ash in our country is only between 30% and 40%, and it is mainly used in construction, cement and other industries. However, fly ash has poor adsorption to gaseous mercury, so it is more necessary to modify fly ash and develop new fly ash-based adsorbents.

Chinese patent CN102120174A discloses a method of impregnating and modifying fly ash using halogen salts. In this method, the adsorbent needs to be immersed in the halogen salt solution for 3 to 12 hours, then dried for 12 hours, and finally put into Dry in a vacuum oven for 24 hours. This modification method is suitable for laboratory-scale research, but it is difficult to meet the injection volume of adsorbent required by coal-fired power plants with large flue gas volume. Therefore, how to carry out large-scale modification of adsorbents in coal-fired power plants is an urgent problem to be solved.

Chinese patent CN201614359U discloses a continuous powder surface modifier. This modifier is suitable for surface modification of inorganic non-metallic mineral powder fillers. During the modification process, the material passes through strong friction between the stator and the rotor. The generated temperature is 100-125°C, and the melting point of the agent is generally lower than 100°C. The mixing of materials and agents in the modified host is a mixture of solid and liquid to achieve the effect of powder surface modification.

At present, the adsorbents used in the adsorbent injection mercury removal technology are all produced in an off-line production mode, with a low degree of automation, and the moisture content of the modified adsorbent is higher than that of the original adsorbent. If the accumulation time is too long, it will easily cause agglomeration, which is difficult. It meets the needs of coal-fired power plants and other on-site continuous operations to remove heavy metal pollutants such as mercury. In order to realize the control of heavy metal pollutants such as mercury and strong acid gas pollutants in flue gas, it is of great significance to develop a large-scale adsorbent on-site modification coupling injection system.

Contents of the invention

The purpose of the invention is to propose a large-scale adsorbent modification coupled injection system for controlling the emission of heavy metal pollutants in flue gas. It is characterized in that the modification of the adsorbent is carried out at the same time as the spraying, and large-scale modification can be realized on site, and all the systems are electronically controlled for real-time control. After the test of the demonstration power plant, the system has a strong ability to control heavy metal (mercury, arsenic, lead, cadmium, chromium) pollution and strong acid gas such as sulfur trioxide and hydrogen chloride, and is suitable for the control of multiple pollutants in industrial process flue gas .

The present invention realizes large-scale modified coupling injection in the following ways:

The original unmodified adsorbent is stored in the adsorbent storage tank 1, and enters the frequency conversion feeding device 3 through the feeder 2 during operation, and the modifying agent is placed in the modifying agent tank 4.

The adsorbent and the modified agent are added to the modified host 5 according to a certain proportion, and the unmodified adsorbent collides and reacts at a high speed in the modified host, and the adsorption capacity of the modified adsorbent is greatly improved, and at the same time, no adsorbent Agglomeration phenomenon.

The material of the modified agent tank 4 and the modified host 5 is stainless steel or Teflon coating is sprayed inside, which has strong corrosion resistance and wear resistance.

The induced draft fan 7 provides negative pressure for the large-scale modification system. After modification, the adsorbent enters the cyclone separator 6 under the action of the induced draft fan 7, and the outlet of the induced draft fan 7 is connected with the delivery pipeline, so that the modified adsorbent can be guaranteed. Coupled with the sealing of the injection system, there is no loss of material quality.

After the modified adsorbent in the described cyclone separator 6 enters the collection hopper 8, it is controlled by the feeder 11 to enter the gas-solid mixing accelerator 12, and the feed rate of the feeder 11 is basically the same as that of the feeder 2. Consistent, to ensure the continuity of large-scale modified coupling injection system.

The radius of curvature of the delivery elbow 13 is 6-12 times of the pipe diameter, and the inner wall of the pipeline is lined with a 3-5mm ceramic tube, which effectively improves the service life of the delivery elbow.

The Roots blower 9 is the driving element of the adsorbent injection system, and the emptying valve 10 plays the role of adjusting the required air volume of the conveying pipeline. When the system pressure loss is too large, the Roots blower 9 can be replaced with an air compressor.

The feeding method of the injection pipeline 14 is that both ends are fed at the same time. At this time, the distribution of particles and pressure inside the pipeline is more uniform, and the sorbent sprayed into the flue 15 has a good dispersion effect, preventing pipeline blockage. All control components in the large-scale adsorbent modification coupling injection system are controlled by the electronic control system 16, which is easy to operate and improves work efficiency.

The check valve 17 is used to prevent backflow of gas and adsorbent in the delivery pipeline.

The air compressor 18 plays the role of blowing and plugging. When the injection pipeline 14 is blocked, the system automatically stops running, and the air compressor 18 starts to work to blow and block the injection pipeline.

The beneficial effects of the implementation of the present invention include:

1) The present invention realizes on-site large-scale adsorbent modification coupling injection, and the modification of the adsorbent and the injection are carried out at the same time, ensuring the continuity of the technological process of reducing pollutants through the adsorption method;

2) The present invention ensures the sealing of the system, no dust spillage, good effect of adsorbent modification and spray coupling, no loss of material quality, and prevents material from polluting the environment;

3) The present invention ensures that the moisture content of the adsorbent after large-scale modification is lower than 3%, which meets the requirements of pneumatic transportation. At the same time, the adsorbent collides at a high speed in the modification machine, and the caking phenomenon is reduced, and the entire conveying and spraying process is not easy. In the event of blockage, the reliability of the system operation is high;

4) The present invention realizes automation, and the main working components are placed on the ground without being transported to work on the platform. The control components of the whole system are controlled by the electric control system, and the operation is simple.

Description of drawings

Fig. 1 is a process flow chart of the coupled injection system for large-scale modification of adsorbents in the present invention.

Among them, the labels in the figure are:

1. Storage tank; 2. Feeder; 3. Frequency conversion feeding device; 4. Modified agent tank; 5. Modified host; 6. Cyclone separator; 7. Induced fan; 8. Collection hopper; 9. Roots blower; 10. Evacuation valve; 11. Feeder; 12. Gas-solid mixing accelerator; 13. Delivery elbow; 14. Injection pipe; 15. Flue; 16. Electric control system; 17. Check valve ; 18. Air compressor.

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

The present invention proposes a large-scale adsorbent modified coupling injection system, as shown in Figure 1, comprising: adsorbent storage tank 1, rotary feeder 2, frequency conversion feeding device 3, modified agent tank 4, modified Main engine 5, cyclone separator 6, induced draft fan 7, collection hopper 8, Roots blower 9, emptying valve 10, feeder 11, gas-solid mixing accelerator 12, conveying elbow 13, injection pipe 14, flue 15, Electric control system 16, check valve 17 and air compressor 18. The system includes two parts: a large-scale modification system and an injection system, and the two systems work together to ensure the continuity and sealing of the coupling system.

The large-scale modification system includes a feeding device and a modification and collection device. 1, 2, 3, and 4 form an adsorbent and medicament feeding device before modification, and the sorbent and medicament are added to the modified host according to a certain ratio 5 In the process, the modification is completed in the modified host 5; under the action of the induced draft fan 7, the modified adsorbent coming out of the modified host 5 enters the cyclone separator 6 along the connecting pipe for separation, wherein the adsorbent falls to At the bottom of the cyclone separator, the air enters the delivery pipeline from the outlet of the induced draft fan 7.

The injection system includes a pneumatic conveying device and an injection pipeline, 9 and 10 form an air inlet device; 8 and 11 form an adsorbent feeding device. The adsorbent and the gas in the gas-solid mixing accelerator 12 are mixed according to a certain ratio, and then flow to the injection pipe 14 along the delivery pipe, and are evenly sprayed into the flue 15 .

The frequency conversion feeding device 3 is equipped with a heating device. When working in a cold working environment, the heating device is turned on to ensure the normal operation of the modification system.

The modified agent tank 4 is made of stainless steel or coated with Teflon inside, and has an electric heating rod to ensure that the modified system can operate in a cold working environment.

The modified host 5 is made of stainless steel or coated with Teflon inside, which is wear-resistant and corrosion-resistant.

The delivery elbow 13 is lined with a 3-5 mm thick ceramic tube on the inner wall of the pipeline to enhance the wear resistance of the delivery elbow.

When the injection pipeline 14 is blocked, the system automatically stops running, and the air compressor 18 starts to work to blow the injection pipeline to blockage.

The present invention may be embodied in other specific forms without departing from the spirit and main characteristics of the invention. Therefore, the above-mentioned embodiments of the present invention can only be considered as descriptions of the present invention and can not limit the present invention, and the claims point out the scope of the present invention, but the above description does not all point out the scope of the present invention. Therefore, any changes within the meaning and scope equivalent to the claims of the present invention should be considered to be included in the scope of the claims.

Claims (8)

1. A large-scale adsorbent modification coupling injection method for controlling the discharge of heavy metal pollutants in flue gas, characterized in that the method includes carrying out adsorbent modification on site, and directly transporting the modified adsorbent to Injection system, forming an on-site adsorbent modification and injection integration process, injecting the modified adsorbent into the flue to absorb pollutants in the flue gas, the pollutants include heavy metals and strong acid gases, the The method includes a modifying step and a spraying step, wherein the modifying step includes: transporting the original unmodified adsorbent from the adsorbent storage tank (1) to the frequency conversion feeding device (3) through the feeder (2) , the adsorbent from the frequency conversion feeding device (3) and the modifying agent in the modifying agent tank (4) are added in the modified host (5) according to a certain ratio, and the original unmodified adsorbent is added to the modified host ( 5) in high-speed collision and reaction modification, under the effect of the induced draft fan (7), the modified adsorbent coming out from the modified host (5) is collected by the cyclone separator (6); the spraying step Including: after the modified adsorbent separated from the cyclone separator (6) enters the collection hopper (8), it is controlled by the feeder (11) to enter the gas-solid mixing accelerator (12), and the modified adsorbent and the air inhaled from the Roots blower (9) are mixed according to a certain ratio in the gas-solid mixing accelerator (12), and then flow to the injection pipeline (14) along the delivery pipeline, and the modified The adsorbent is evenly sprayed into the flue (15), the pipeline between the Roots blower (9) and the feeder (11) is connected with an emptying valve (10), the gas-solid mixing accelerator (12) and the injection pipeline (14) is provided with delivery elbow (13) and check valve (17) in the delivery pipeline between (14), and injection pipeline (14) is connected with air compressor (18); All control elements are controlled by electric control system in the described method (16) control; the frequency conversion feeding device (3) has a heating device, and the modified agent tank (4) is made of stainless steel or sprayed with Teflon coating inside, and has an electric heating rod to ensure the modification step It can operate in a cold working environment; the feeding method of the injection pipe (14) is simultaneous feeding at both ends, which promotes a more uniform distribution of particles and pressure inside the pipe, and the adsorbent sprayed into the flue (15) has a good dispersion effect, And prevent pipe clogging. 2 . The adsorbent modified coupled injection method according to claim 1 , wherein the heavy metals include mercury, arsenic, lead, cadmium or chromium, and the strong acid gases include sulfur trioxide and hydrogen chloride. 3. The coupling injection method for adsorbent modification according to claim 1, characterized in that, the method realizes large-scale continuous modification of the adsorbent on-site, and the physical and chemical properties of the adsorbent are improved by mixing and reacting in the modification process. And the structure changes, which improves the activity of the adsorbent. 4. The adsorbent modified coupling injection method according to claim 1, characterized in that, the material of the modified host (5) is stainless steel or internally sprayed with a Teflon coating, which is wear-resistant and corrosion-resistant, and is unmodified The adsorbent will not agglomerate after high-speed stirring and collision inside the modified host. 5. The adsorbent modification coupling injection method according to claim 1, characterized in that, when the system pressure loss is too large, the Roots blower (9) can be replaced with an air compressor. 6. The adsorbent modified coupling injection method according to claim 1, characterized in that, the delivery elbow (13) is lined with a 3-5 mm thick ceramic tube on the inner wall of the pipeline to enhance the wear resistance of the delivery elbow and improve System life. 7. The adsorbent modification coupling injection method according to claim 1, characterized in that the check valve (17) is used to prevent the gas and adsorbent in the delivery pipeline from flowing backward. 8. The adsorbent modified coupling injection method according to claim 1, characterized in that, the air compressor (18) plays the role of blowing and plugging, and when the injection pipeline (14) is blocked, the system automatically stops running, Air compressor (18) starts working, blows and blocks injection pipeline.