WO2022088243A1 - Sulfonation removal initiator for sulfur trioxide in coal-fired flue gas and application of sulfonation removal initiator - Google Patents

Abstract

The present invention relates to the field of energy and environment, and in particular to a sulfonation removal initiator for sulfur trioxide in coal-fired flue gas and an application of the sulfonation removal initiator. The sulfonation removal initiator in the present invention comprises the following components in percentage by mass: 0.05-0.1% of a surfactant, 0.05-0.1% of a water-soluble high-molecular compound, 0.005-0.02% of an additive, and the balance of water. The water-soluble high-molecular compound can be subjected to a sulfonation reaction with sulfur trioxide to generate an organic sulfonate high-molecular compound. The sulfonation removal initiator in the present invention is efficient, safe, cheap, simple in synthesis process, easy to operate, free of pollution to the environment, and obvious in sulfur trioxide removal effect.

Description

A sulfonated removal initiator for sulfur trioxide in coal-fired flue gas and its application 【Technical field】

The invention belongs to the field of energy and environment, and particularly relates to a sulfonated removal initiator of sulfur trioxide in coal-fired flue gas and an application thereof.

【Background technique】

At present, China has adopted strict emission restriction measures for the main pollutants of coal-fired power plants, which have achieved great results. The emissions of soot, NOx, SO ₂ and other emissions have been effectively controlled, reaching ultra-low emission standards. In the past, the concentration of SO ₃ in coal-fired power plants was low and did not attract public attention. This year, due to the comprehensive promotion and application of ultra-low emission transformation, the installation of a large number of SCR denitration systems and the use of SCR catalysts have resulted in the oxidation of part of SO ₂ into SO ₃ , which increased the concentration of SO ₃ in the flue gas. SO ₃ in flue gas is far more harmful than SO ₂ , corrodes power plant equipment, threatens the safe operation of power plants, and is discharged into the atmosphere to form acid rain and aggravate haze. The difficulty in removing SO ₃ from the flue gas of coal-fired power plants is that with the decrease of flue gas temperature, SO ₃ exists in the form of sulfuric acid mist droplets with a particle size of microns, which is difficult to remove by existing equipment in the power plant. The frequent occurrence of colored plumes and the aggravation of air preheater blockage need to be solved urgently, and a cost-effective sulfur trioxide control method needs to be developed.

CN101513583B discloses a coal-fired ultrafine particle chemical agglomeration accelerator, which includes a surfactant, a water-soluble polymer compound, a pH adjuster, an additive and water. Surfactant reduces the surface tension of the solution, promotes the wetting of ultrafine particles, and accelerates the entry of ultrafine particles into the droplets of the agglomeration accelerator, thereby increasing the capture speed and amount of ultrafine particles by the agglomeration accelerator. After the sodium-based surfactant is adsorbed by the particles, it can also enhance the electrical conductivity of the particles and reduce the specific resistance of the particles. After the water-soluble polymer compound is dissolved in water, the charged group formed can be electrically neutralized with the ultrafine particles; the long polymer chain adsorbed on the surface of the particle may be adsorbed on the surface of another particle at the same time, Two or more particles are agglomerated together by means of "bridging", and both electrical neutralization and adsorption bridging can lead to particle agglomeration. The pH adjuster can change the existing form of the molecular chain of the water-soluble polymer compound in the solution, soften the curled or rigidly stretched molecular chain into a flexible stretched molecular chain, and enhance its ability to agglomerate particles, thereby improving the ability of the agglomeration accelerator to superfine The agglomeration efficiency of the particles. The additive can enhance the ability of the surfactant to reduce the surface tension of the solution and promote the wetting of ultrafine particles; at the same time, the additive can also enhance the conductivity of the particles, reduce the specific resistance of the particles, and improve the removal efficiency of the electrostatic precipitator for fly ash with high specific resistance. Although this technical solution provides the use of agglomeration technology to treat fly ash in coal-fired power plants, it does not solve the SO ₃ gas existing in coal-fired power plants.

To sum up, the prior art still lacks a method that can solve the defects of the SCR catalyst and effectively remove the sulfuric acid trioxide mist from burning coal.

[Content of the invention]

The purpose of the present invention is to provide a high-temperature sulfonation removal initiator for sulfur trioxide in coal-fired flue gas, which can not only effectively remove coal-fired sulfuric acid trioxide mist, but also prevent NH ₄ HSO ₄ from clogging the air preheater, affect the normal operation of the unit.

As the first aspect of the present invention, a sulfonated removal initiator for sulfur trioxide in coal-fired flue gas is protected, which includes the following components by mass percentage: 0.05-0.1% surfactant, 0.05-0.1% water-soluble The water-soluble polymer compound is 0.005-0.02% of the additive, and the rest is water. The water-soluble polymer compound can undergo sulfonation reaction with sulfur trioxide to generate an organic sulfonate polymer compound.

Aiming at the increase of SO ₃ concentration in flue gas caused by coal combustion and SCR catalytic oxidation, causing colored plumes, SO ₃ high-temperature sulfonation technology is used to remove more than 70% of SO ₃ content, and cut off (NH ₄ ) ₂ SO ₄ , NH ₄ HSO ₄ and other ammonium sulfate formation conditions, reduce the probability of air preheater blockage. Based on chemical agglomeration technology, a high _- temperature sulfonated SO3 removal initiator was developed to promote the sulfonation reaction _of SO3 and organic polymers into organic sulfonate compounds, and a sulfonation reaction to remove _SO3 in flue gas was established.

The sulfonation reaction of SO ₃ with strong oxidizing property and organic substances that can donate electron groups is a typical electrophilic substitution reaction. The flue gas temperature before the air preheater is in the range of 300-400°C, the sulfonation reaction speed is fast, the reaction activity is high, and it is an exothermic reaction. The specific reaction is as follows:

Ar-H+SO ₃ →Ar-SO ₃ H

Therefore, the water-soluble polymer compound in the sulfonation removal initiator undergoes sulfonation reaction with SO ₃ to form an organic sulfonate polymer compound, and the initiator has various surface activities such as water-solubility, emulsification and wetting, which further promotes the Initiator removal efficacy.

Preferably, the water-soluble polymer compound is any one of glucomannan and xanthan gum.

Preferably, the surfactant is any one of cetyl trimethyl ammonium chloride and polyethylene glycol octyl phenyl ether.

Preferably, the additive is any one of potassium chloride and phytic acid.

As the second aspect of the present invention, to protect the preparation method of the sulfonated removal initiator, add the water-soluble polymer compound to the water and stir it evenly, after it is completely dissolved, add the surfactant and additives, and finally stir until it is completely dissolved. .

As the third aspect of the present invention, the application of the sulfonated removal initiator is protected, characterized in that the application includes a method for sulfur trioxide removal.

Preferably, the sulfonated removal initiator is atomized to form droplets, and the droplets are sprayed into the flue before the air preheater to capture sulfur trioxide, thereby removing sulfur trioxide.

Preferably, the particle size of the droplets is not greater than 100 μm, and preferably, the droplets are 25 μm-50 μm. The spray gun is equipped with a new self-developed two-fluid physicochemical nozzle. The average droplet size is mainly measured by the Winner318A spray laser particle size analyzer, which can ensure that the droplet size meets the requirements.

Preferably, the ratio of the input amount of the sulfonation removal initiator to the mass of sulfur trioxide is not less than 10:1, preferably (10-50):1.

Preferably, the reaction temperature of the sulfonation removal initiator and sulfur trioxide is 300-400°C.

The beneficial effects of the present invention are:

(1) The sulfonated removal initiator used in the present invention includes surfactant, water-soluble polymer compound, additives and water, and has a synergistic effect. The surfactant can reduce the surface tension of the initiator solution and promote the wetting of fine particles , accelerate the adsorption of sulfuric acid trioxide mist on the particulate matter, thereby improving the capture speed and amount of sulfur trioxide by the sulfonated removal initiator. After the polymer compound is dissolved in water, its gel strength and solution viscosity will increase. Under a variety of bridging forces, the linear molecules of the polymer are entangled to form a network structure to form a stable gel, and the molecular chains of the polymer occupy the adsorption sites on the surface of the fine particles and agglomerate with the fine particles to form agglomerates. A variety of polymer compounds are compounded to form elastic active chains, and an elastic dense network structure is formed between the chains, which increases the probability of capturing sulfuric acid trioxide mist. The addition of additives increases the collision probability between sulfuric acid trioxide mist and fine particles, enhances the conductivity and intermolecular force of the polymer, and reduces the specific resistance of fine particles.

(2) The sulfonation removal initiator of the present invention is efficient, safe and cheap, has a simple synthesis process, is easy to operate, has no pollution to the environment, has an obvious effect on sulfur trioxide removal, and can greatly reduce sulfur trioxide emissions from coal-fired power plants , Since most of the sulfuric acid trioxide mist is concentrated on the fine particles, the sulfonation removal initiator can also realize the removal of fine particles and heavy metals.

(3) When the sulfonation removal initiator of the present invention removes sulfur trioxide, the particle size of the droplets is 25 μm-50 μm, which can fully contact the sulfuric acid trioxide mist and fine particles in the flue gas to achieve better removal. The effect is that the input amount of the sulfonation removal initiator and the mass ratio of sulfur trioxide are appropriate, so as to ensure the removal effect and avoid the impact of the incompletely evaporated droplets escaping to the subsequent equipment.

(4) The present invention has created a new way of using high-temperature flue gas before the air preheater to treat waste with waste, advanced energy saving and environmental protection. Compared with conventional applications, the air preheater is used as a preheating device that improves the heat exchange performance of the boiler and reduces energy loss. In the event of serious blockage, it will cause the boiler to limit the load, or even shut down for maintenance, which will affect the normal operation of the unit. By spraying sulfonation and removing initiator before the air preheater, it is used to treat SO ₃ in the flue gas, cut off the formation conditions of ammonium sulfate such as (NH ₄ ) ₂ SO ₄ , NH ₄ HSO ₄ and so on, and reduce the blockage of the air preheater Probability, solve the problem that the pressure difference of the air preheater continues to rise in the continuous operation of the unit, and achieved good results.

(5) The sulfonation removal initiator of the present invention effectively removes SO ₃ fundamentally, solves the fundamental problem of colored plumes in power plants, and fills up SO ₃ in coal-fired power plants from multiple dimensions such as operation stability, energy saving and consumption reduction Governance gaps.

【Description of drawings】

Fig. 1 is a process flow diagram of the method of use of the present invention.

【Detailed ways】

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

An example of the present invention proposes an initiator for high-temperature sulfonation removal of sulfur trioxide in coal-fired flue gas, which is characterized in that it includes the following components by mass percentage: 0.05-0.1% surfactant, 0.05-0.1% surfactant A water-soluble polymer compound, 0.005-0.02% of an additive, the balance being water, the water-soluble polymer compound can undergo sulfonation reaction with sulfur trioxide to generate an organic sulfonate polymer compound.

The water-soluble polymer compound can be selected from glucomannan and xanthan gum. The surfactant is any one of cetyl trimethyl ammonium chloride and polyethylene glycol octyl phenyl ether. The additives are potassium chloride and phytic acid.

The present invention also proposes a method for preparing the above-mentioned sulfonation and removing the initiator. The method is specifically as follows: adding a water-soluble polymer compound to the water and stirring it evenly, adding a surfactant and additives after it is completely dissolved, and finally stirring until it is completely Dissolved to obtain the sulfonated removal initiator.

As shown in FIG. 1 , the present invention also proposes a method for using the above-mentioned sulfonated removal initiator for sulfur trioxide removal. The method is specifically: atomizing the sulfonated removal initiator into droplets Then, the droplets are sprayed into the flue before the air preheater to capture the sulfur trioxide of coal combustion, or the sulfur trioxide after the coal combustion is catalytically oxidized by SCR, so as to remove the sulfur trioxide.

Before use, the different components in the raw materials can be stored independently, and the sulfonation removal initiator can be obtained by proportioning according to the proportion; Remove the initiator, but the storage time of the prepared high-concentration solution should not be too long, preferably one week. The ratio of the input amount of the sulfonated removal initiator to the mass of sulfur trioxide is not less than 10:1, preferably (10-50):1, to ensure the removal effect while avoiding incompletely evaporated droplets from escaping. Subsequent devices have an impact. Further, the particle size of the droplets is preferably 100 μm or less, more preferably 25 μm-50 μm, and the droplet particle size in this range can fully contact the sulfuric acid trioxide mist and fine particles in the flue gas to achieve a better removal effect. .

The present invention is described in detail below according to specific embodiments, and the percentages in the embodiments are all mass percentages.

Example 1

This embodiment provides a sulfonated removal initiator, the formula ratio of which is 0.05% glucomannan, 0.1% cetyltrimethylammonium chloride, 0.02% potassium chloride, and the balance is water ;

A power plant electrostatic precipitator four electric field fly ash is mixed with preheated air as simulated flue gas and is introduced into the reaction chamber. For droplets with a particle size of 50μm, the mixed flue gas volume is 2200ml/min, and the initiator dosage is 5ml/min. By measuring the content of sulfur trioxide in the flue gas, it can be seen that the concentration of sulfur trioxide is 114ppm. The mass ratio of sulfur oxides was 20:1, and the two interacted in the simulated flue environment in the reaction chamber, the residence time was 2s, and the reaction temperature was 350 °C. The concentration of sulfur trioxide is tested as follows, using the EPA 80% isopropanol absorption method to collect sulfur trioxide in the flue gas, and measure it by ion chromatography.

The sulfonated removal initiator promotes the agglomeration of sulfuric acid trioxide mist and fine particles, which are then captured by the subsequent bag filter. , to determine the concentration of sulfur trioxide emissions. The test results show that the emission concentration of sulfur trioxide dropped significantly after spraying the sulfonated removal initiator with this formula, and the removal rate of sulfur trioxide after the dedusting device was increased by 40.3% compared with that without spraying the sulfonated removal initiator. to 89.6%, an increase of 49.6%.

The difference between Examples 2 to 5, and Comparative Examples 1 to 9 and Example 1 lies in the difference in formulations, which are specifically described in Table 1, and are not detailed here.

Table 1 embodiment and comparative example formula ratio and test result table

Examples 6-11 and Comparative Examples 10-15 are different from Example 1 in that the reaction parameters are different, which are specifically described in Table 2, and are not detailed here.

Table 2 embodiment and comparative example formula ratio and test result continuation table

From the comparison of Examples 1-5 and Comparative Examples 1-9, it can be seen that the used sulfonation removal initiators include surfactants, water-soluble polymer compounds, additives and water, which have a synergistic effect and greatly improve the resistance to three Sulfur oxide removal efficiency.

From the comparison between Example 1 and Example 2, it can be seen that in Example 2, when the mass ratio of polymer to surfactant is 1:1, the effect is better. Example 5 When the mass ratio of polymer to surfactant is 1:1, the removal efficiency is better than other ratios.

It can be seen from Examples 1, 6, 7 and Comparative Examples 10 and 11 that the smaller the particle size, the higher the SO ₃ removal efficiency. This is because the smaller the droplet particle size, the larger the surface area of the droplet group, the easier it is to collide and intercept SO ₃ in the flue gas, and the more complete and faster the sulfonation reaction occurs. The smaller the droplet size, the higher the requirements for the nozzle and the greater the difficulty of atomization. Conversely, the larger the particle size, the longer the droplet evaporation time, the longer the droplet evaporation distance, and the more difficult it is to arrange in practical engineering applications. Studies have shown that droplets with a particle size of less than 100 μm can be completely evaporated, so that the escape of incompletely evaporated droplets can cause corrosion to subsequent equipment and flues. Considering the technical and economic conditions, the particle size of the droplets is preferably 25 μm-50 μm.

It can be seen from Examples 1, 8, ₉ , 10, 11, 12 and Comparative Examples 12 and 13 that when the ratio of the sulfonation removal initiator to the flue gas concentration is large, a small amount of SO3 cannot be effectively removed, and the removal efficiency is low . On the contrary, when the ratio of the sulfonation removal initiator to the concentration of flue gas is small, the evaporation of droplets absorbs more heat, and it is easy to occur that the droplets are not completely evaporated, resulting in incomplete sulfonation reaction. The effect of efficiency is limited, and the ratio of the input amount of the sulfonation removal initiator to the mass of sulfur trioxide is not less than 10:1, which can achieve better results, preferably (10-50):1.

It can be known from Examples 1, 13, 14 and Comparative Examples 14 and 15 that in the temperature range of 300°C-400°C, the higher the temperature, the better the removal effect. When the temperature is low, the long polymer chains adsorbed on the particle surface are not fully extended, and the adsorption bridging effect is relatively weak, and the removal effect of SO ₃ is weakened. Conversely, when the temperature is higher, the evaporation time _of the droplets becomes faster, the contact time with SO3 becomes shorter, the time for the sulfonation reaction to occur is limited, and the removal effect decreases. The reaction temperature is preferably 300°C to 400°C.

Application Example

The present embodiment provides a sulfonation removal initiator, the formula ratio of which is 0.1% xanthan gum, 0.1% cetyltrimethylammonium chloride, 0.05% potassium chloride, and the balance is water;

Before the air preheater of a 300MW coal-fired unit, the sulfonated removal initiator described in formula example (2) was sprayed into the vertical flue with a particle size of 50 μm through a liquid dosing pump, compressed air, and a double-flow atomizing nozzle. The amount of flue gas is 1,980,000m ³ /h, the concentration of SO ₃ in the flue gas is about 31.6mg/m ³ , and the spray amount _of the sulfonation removal initiator is 2.5m ³ /h. The mass ratio of chemical removal initiator was 1:39.96. The average concentration of sulfur trioxide in the exhaust flue gas was reduced by 17.2 mg per square meter, and the removal efficiency reached 54.3%.

By demonstrating the change of pressure difference in the continuous operation of the unit for 4 months, it shows that the removal of initiator by sulfonation can effectively solve the occurrence of blockage of the air preheater. Before the sulfonation removal initiator, the monthly average pressure difference of the air preheater was 757.7Pa, 1012.9Pa, 1204.8Pa, 1578.3Pa, the pressure difference increased by about 52%, and the blockage of the air preheater became more serious; After the initiator, the monthly average pressure difference of the air preheater was 999.0Pa, 783.1Pa, 866.4Pa, 777.9Pa, and the air preheater pressure difference remained stable.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection scope of the present invention.

Claims (10)

1. A sulfonated removal initiator for sulfur trioxide in coal-fired flue gas, characterized in that, it comprises the following components by mass percentage: 0.05-0.1% of a surfactant, 0.05-0.1% of a water-soluble polymer compound, 0.005-0.02% of additives, the rest is water, the water-soluble polymer compound can undergo sulfonation reaction with sulfur trioxide to generate organic sulfonate polymer compound.
2. The sulfonation removal initiator according to claim 1, wherein the water-soluble polymer compound is any one of glucomannan and xanthan gum.
3. The sulfonation removal initiator according to claim 2, wherein the surfactant is any one of cetyltrimethylammonium chloride and polyethylene glycol octyl phenyl ether.
4. The sulfonation removal initiator according to claim 1 or 2, wherein the additive is any one of potassium chloride and phytic acid.
5. The preparation method of sulfonation removal initiator according to any one of claims 1-4, characterized in that, adding a water-soluble polymer compound to the water and stirring evenly, after completely dissolving, adding surfactants and additives, and finally Stir until completely dissolved.
6. The application of the sulfonation removal initiator according to any one of claims 1-4, characterized in that, the application includes a method for sulfur trioxide removal.
7. The application according to claim 6, wherein the sulfonated removal initiator is atomized to form droplets, and the droplets are sprayed into the flue before the air preheater for capturing sulfur trioxide , so as to remove sulfur trioxide.
8. The application according to claim 7, wherein the particle size of the droplets is not greater than 100 μm, and preferably, the droplets are 25 μm-50 μm.
9. The application according to claim 7, wherein the ratio of the input amount of the sulfonation removal initiator to the mass of sulfur trioxide is not less than 10:1, preferably (10-50):1.
10. The application according to claim 7, wherein the reaction temperature of the sulfonated removal initiator and sulfur trioxide is 300-400°C.

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