Method and system for efficient denitrification of boiler modified fly ash

Abstract

The present invention discloses a method and system for efficient denitration of boiler modified fly ash, which belongs to the field of environmental protection technology. The denitration synergist includes boiler fly ash and a modifier, and the modifier includes a solvent, triethanolamine, and acetamide in a mass ratio of 100: (0.02-0.05): (0.03-0.1). The method of using this denitration agent is to transport the fly ash in the waste flue gas captured in the dust collector to an atomizer through a conveying pipeline; transport the modifier to the atomizer for atomization, and modify the fly ash in the atomizer to obtain modified fly ash; and transport the modified fly ash to the rear end of the economizer through a conveying pipeline for flue gas denitration. The above-mentioned denitration synergist and its use method significantly improve the denitration efficiency of the denitration agent, save the amount of the denitration agent, and basically prevent the denitration agent that does not participate in the reaction from polluting the environment and corroding the boiler equipment.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection, and in particular to a method and a system for efficient denitration of boiler modified fly ash. Background Art

[0002] At present, all boilers in operation, regardless of their size, use SNCR (non-catalytic reduction), PNCR (polymer denitration) and other types of denitration methods. These denitration methods are all ammonia reagents, which decompose at high temperatures and react with nitrogen oxides NO in the boiler. X However, excessive injection of denitrification agent into the boiler will cause serious corrosion of the superheated surface in the furnace, seriously shorten the normal operation time of the boiler, and greatly increase the operation and maintenance costs. In the past, the nitrogen oxide emission standard for industrial boilers and small and medium-sized boilers was 100mg / Nm 3 Or 200mg / Nm 3 , the denitrification efficiency of about 40-50% in the furnace can meet the basic requirements. As boiler emission standards become increasingly stringent, nitrogen oxide emissions are required to be less than 100mg / Nm 3 , even less than 50mg / Nm 3 Some key areas even require less than 30mg / Nm 3 , the existing design efficiency and design dosage of denitrification reducing agent in the furnace can no longer meet the requirements. Even if the denitrification in the furnace is combined with other denitrification processes, there are certain requirements for the efficiency of denitrification in the furnace, which can easily lead to excessive operation personnel and excessive input of denitrification agent; when the denitrification window temperature of the boiler furnace in some special industries is lower than 800℃, the reaction temperature cannot be reached, and the reaction efficiency is lower after the denitrification agent is sprayed in, resulting in a lot of waste, reduced boiler thermal efficiency and serious corrosion of furnace equipment. At present, some companies are also trying other technologies to improve the efficiency of denitrification in the furnace and reduce the dosage of denitrification reducing agent in the furnace. However, many methods and equipment are not easy to operate, not easy to clean and maintain, and are not suitable for industrial-scale use. Summary of the invention

[0003] In view of the above shortcomings of the prior art, the amount of denitration reducing agent in the furnace is reduced, especially for the situation where the furnace temperature in some industries is low and cannot reach the denitration reaction window temperature, the present invention provides a denitration synergist for efficient denitration of boilers, and a method of use and a denitration system, which can stably and efficiently carry out flue gas denitration treatment, reuse existing equipment and waste materials in industrial areas as much as possible, have low cost and good effect, and improve the current problems of low denitration efficiency in the furnace and excessive denitration agent usage. It is specifically achieved through the following technologies.

[0004] The invention discloses a denitrification enhancer for efficient denitrification of boilers, wherein the raw materials thereof include boiler fly ash and a modifier, wherein the modifier includes a solvent, triethanolamine and acetamide in a mass ratio of 100:(0.02-0.05):(0.03-0.1).

[0005] The above-mentioned denitrification synergist is a combination of boiler fly ash and modifier, which can recycle the boiler fly ash for multiple times and make it fully burned; triethanolamine and acetamide in the modifier can chelate with nitrogen oxides NOx in boiler flue gas to form chelates; the porous structure of fly ash has a very large specific surface area, which can provide a carrier for the reaction of triethanolamine, acetamide and chelates, effectively increasing the reaction area between nitrogen oxides NOx and denitrifier; the porous structure of fly ash can also effectively adsorb nitrogen oxides and their chelates in flue gas, prolong the retention time of nitrogen oxides in the boiler, and prolong the reaction time; it can also make the denitrifier adsorbed in the fly ash of the initial denitrification play a denitrification role again, avoid the adsorption of too much unreacted denitrifier in the porous structure of fly ash, reduce the amount of newly added denitrifier, and reduce the odor of fly ash. The large amount of carbon element remaining in the fly ash can also provide a heat source for combustion in the secondary combustion, thereby improving the thermal efficiency of the boiler.

[0006] It is worth emphasizing that the above-mentioned denitrification enhancer is not a denitrifier. Its main function in the denitrification process is to absorb the common denitrifiers commonly used in boilers and the residual denitrifiers in the porous structure of fly ash. Therefore, after using the above-mentioned denitrification enhancer, the boiler needs to continue to add denitrifiers for denitrification during combustion, but the amount added can be significantly reduced.

[0007] Preferably, the modifier comprises a solvent, triethanolamine and acetamide in a mass ratio of 100:0.04:0.06.

[0008] Preferably, the solvent is water or the supernatant of an industrial wastewater pool, and the pH value of the supernatant is 6-8.

[0009] The present invention also provides a method for using the above-mentioned denitration synergist for efficient denitration of boilers, comprising the following steps:

[0010] S1. The fly ash in the waste gas captured in the dust collector is transported to the atomizer through a conveying pipeline;

[0011] S2, transporting the modifier to an atomizer for atomization, and modifying the fly ash in the atomizer to obtain modified fly ash;

[0012] S3. The modified fly ash is transported to the rear end of the economizer through a transport pipeline to participate in the flue gas denitrification reaction.

[0013] By using the denitrification synergist according to the above method, the fly ash and the atomized triethanolamine and acetamide are evenly mixed and then put into the boiler for secondary or tertiary (i.e. repeated multiple times) combustion. The porous structure on the surface of the fly ash is used to adsorb the nitrogen oxides NOx chelated with the triethanolamine and acetamide in the synergist, which can provide a large amount of denitrification reaction area for the denitrification process of the denitrification agent and improve the denitrification effect; by improving the denitrification effect of the denitrification agent, the input amount of the denitrification agent is reduced, the corrosion of the inner wall of the boiler is avoided, and the denitrification cost and equipment maintenance cost are effectively reduced.

[0014] Preferably, in the above-mentioned method of use, the injection air volume in step S1 is 10-20 m3 / min, and the injection total pressure is 30-58.8 kPa.

[0015] Preferably, in the above method of use, the heating temperature of the entire process of steps S1-S3 is 105-110°C.

[0016] The present invention also combines the above-mentioned method of use and utilizes the above-mentioned denitrification enhancer to provide a high-efficiency denitrification system, including a dust collector, an atomizer, an economizer, a wastewater tank, a water pump, and a modifier tank; the wastewater tank, water pump, modifier tank, and atomizer are connected in sequence through a conveying pipe; the cone bucket at the bottom of the dust collector is connected to the atomizer through a conveying pipe, a fan is connected to the conveying pipe between the cone bucket and the atomizer, and the atomizer is connected to the rear end of the economizer through the conveying pipe.

[0017] Preferably, in the above-mentioned denitration system, a booster pump is further provided on the delivery pipeline between the modifier tank and the atomizer, and the blower is a low-pressure Roots blower.

[0018] Compared with the prior art, the advantages of the present invention are as follows: by using boiler fly ash in combination with triethanolamine and acetamide, a denitrification method that is completely different from all the existing technologies is provided, which has very high operability; the denitrification efficiency of the denitrification agent is significantly improved, the amount of the denitrification agent is saved, and the denitrification agent that does not participate in the reaction is basically prevented from polluting the environment and corroding the boiler equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of equipment connection of the denitration system provided by the present invention;

[0020] In the figure: 1. dust collector; 101. cone bucket; 2. ultrasonic atomizer; 3. economizer; 4. wastewater tank; 5. water pump; 6. modifier tank; 7. low-pressure Roots blower. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] This specific implementation provides a set of high-efficiency denitrification system, such as Figure 1 As shown, the system includes a dust collector 1, an ultrasonic atomizer 2, an economizer 3, a wastewater tank 4, a water pump 5, and a modifier tank 6; the wastewater tank 4, the water pump 5, the modifier tank 6, and the ultrasonic atomizer 2 are connected in sequence through a conveying pipeline; the cone hopper 101 at the bottom of the dust collector 1 is connected to the ultrasonic atomizer 2 through a conveying pipeline, and a low-pressure Roots blower 7 is connected to the conveying pipeline between the cone hopper 101 and the ultrasonic atomizer 2, and the ultrasonic atomizer 2 is connected to the rear end of the economizer 3 through a conveying pipeline.

[0023] The operation method of the above-mentioned high-efficiency denitrification system is carried out at a heating temperature of 105-110°C throughout the process, specifically:

[0024] (1) Using a cyclone dust collector to continuously capture the waste flue gas in the industrial area to obtain fly ash; using a dilute phase pneumatic conveying method, the fly ash is transported from the cone hopper at the bottom of the dust collector through a conveying pipeline to the rear end of the economizer;

[0025] (2) While the fly ash is being transported, the pH value of the supernatant in the wastewater pool of the industrial area is adjusted to 6-8, and then the supernatant is pumped into a modifier tank by a water pump, mixed with triethanolamine and acetamide to form a modifier, and the modifier is transported to an ultrasonic atomizer for atomization;

[0026] The dosage ratio of supernatant, triethanolamine and acetamide is 100:(0.02-0.05):(0.03-0.1); Generally speaking, the higher the concentration of triethanolamine and acetamide, the better the denitrification effect, but in order to consider the economic cost, the ratio of 100:0.04:0.06 can be selected;

[0027] (3) The atomized modifier is also sprayed to the rear end of the economizer through the conveying pipeline, and an appropriate amount of denitrification agent is added at the same time. The modifier, fly ash and denitrification agent react with nitrogen oxides in the flue gas to complete the denitrification process. During the transportation from the cone hopper to the rear end of the economizer, the fly ash passes through an ultrasonic atomization device with a modification reagent solution inside. The fly ash reacts with the modification reagent solution under the ultrasonic atomization environment to modify the fly ash and obtain modified fly ash;

[0028] The jet air volume is 10-20m 3 / min, and the total injection pressure is 30-58.8kPa; the specific injection air volume and total injection pressure depend on the actual conditions of different boilers; fly ash can be continuously recycled after multiple combustions, continuously providing a reaction carrier for the flue gas denitrification reaction.

[0029] The denitration system, denitration method and corresponding denitration synergist provided in this specific embodiment utilize the chelation between triethanolamine, acetamide and nitrogen oxides NOx in boiler flue gas to form a chelate. The porous structure of fly ash has a very large specific surface area, which can adsorb and provide a carrier for the reaction of triethanolamine, acetamide and chelate. The added denitrifier reacts with nitrogen oxides in the chelate on the surface of fly ash. This method greatly improves the efficiency of denitration reaction, effectively recycles wastes such as fly ash and wastewater supernatant, reduces the amount of denitrifier, and avoids boiler corrosion problems; it provides a process with high implementation degree, low commissioning cost and operating cost saving for the denitration of waste gas, tail gas and flue gas from fixed pollution sources such as thermal power plants, industrial kilns, and garbage incinerators. In addition, the present invention can consume factory wastewater and fly ash without affecting the quality of fly ash.

Claims

1. A method for efficient denitration of boiler modified fly ash using a denitration synergist, characterized in that: The following steps are involved: S1. The fly ash in the waste gas captured in the dust collector is transported to the atomizer through the conveying pipeline; the injection air volume is 10-20m 3 / min, the total injection pressure is 30-58.8kPa; S2, transporting the modifier to an atomizer for atomization, and modifying the fly ash in the atomizer to obtain modified fly ash; S3, transporting the modified fly ash to the rear end of the economizer through a transport pipeline to participate in the flue gas denitrification reaction; At the same time, a proper amount of denitrification agent is added, and the modifier, fly ash and denitrification agent react with nitrogen oxides in the flue gas to complete the denitrification process; the chelation reaction between triethanolamine, acetamide and nitrogen oxides NOx in the boiler flue gas forms a chelate; the added denitrification agent reacts with nitrogen oxides in the chelate on the surface of the fly ash to denitrify; the fly ash can be continuously recycled after multiple combustions, and continuously provides a reaction carrier for the flue gas denitrification reaction; The heating temperature of the whole process of steps S1-S3 is 105-110°C; The raw materials of the denitrification enhancer include boiler fly ash and a modifier, wherein the modifier includes a solvent, triethanolamine and acetamide in a mass ratio of 100:0.04:0.06; the solvent is the supernatant of an industrial wastewater pool, and the pH value of the supernatant is 6-8.

2. The method for efficient denitration of boiler modified fly ash using a denitration synergist according to claim 1, characterized in that: The process is completed by using a system for efficient denitrification of boiler modified fly ash, which comprises a dust collector, an atomizer, an economizer, a wastewater tank, a water pump, and a modifier tank; the wastewater tank, the water pump, the modifier tank, and the atomizer are connected in sequence through a conveying pipeline; the cone bucket at the bottom of the dust collector is connected to the atomizer through a conveying pipeline, a fan is connected to the conveying pipeline between the cone bucket and the atomizer, and the atomizer is connected to the rear end of the economizer through a conveying pipeline.

3. The method for efficient denitration of boiler modified fly ash using a denitration synergist according to claim 2, characterized in that: A booster pump is also provided on the delivery pipeline between the modifier tank and the atomizer, and the blower is a low-pressure Roots blower.

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