CN105107629A - Specific resistance conditioning agent used for lowering fly ash resistivity and application of specific resistance conditioning agent - Google Patents

Abstract

The invention discloses a specific resistance regulator for reducing the specific resistance of fly ash. The specific resistance regulator is an aqueous solution containing alkali metal salts, and the alkali metal salts include sodium acetate and dipotassium hydrogen phosphate. The invention discloses the application and use method of the specific resistance regulator. The specific resistance regulator can effectively reduce the specific resistance of the fly ash and improve the removal efficiency of the fly ash by an electrostatic precipitator.

Description

A specific resistance regulator for reducing fly ash specific resistance and its application

technical field

The invention belongs to the field of energy and environment, and relates to a specific resistance regulator, in particular to a specific resistance regulator for reducing the specific resistance of fly ash. The present invention also relates to the application of the specific resistance regulator.

Background technique

Electrostatic precipitators are more and more widely used in the power industry. This is because the electrostatic precipitator is a dust removal device that uses a strong electric field to ionize the gas, that is, generates a corona discharge, and then charges the dust, and under the action of the electric field force, separates the dust from the gas. The dust removal method has many advantages: it can handle large flow gas and high temperature or corrosive gas; the Coulomb force directly acts on the particles floating in the gas, and the equipment structure is simple and the air velocity is low, so the pressure loss of the dust collector is small and the efficiency of the dust collector is high. , up to more than 99%, and high temperature resistance; low operation and maintenance costs and a series of advantages. Generally, when the specific resistance of dust is in the range of 10 ⁴ -10 ¹⁰ Ω∙cm, it is most suitable for electrical dust collection, but in the production of electric power industry, dust with a specific resistance higher than 5×10 ¹⁰ Ω∙cm is often encountered, that is, high specific resistance Dust, so solving the problem of dust collection with high specific resistance is of great significance for improving the dust removal efficiency of electrostatic precipitators.

According to the research status at home and abroad and the operation practice of some power plants, adding a flue gas conditioning system to the electrostatic precipitator system to improve the adaptability of the electrostatic precipitator to coal combustion and further improve the dust removal efficiency is an effective and effective way to solve the problem of dust emission. Prospect way. Among them, the performance of the specific resistance regulator plays a decisive role. At present, the most widely used conditioning technology is S0 ₃ conditioning. The principle of S0 ₃ conditioning is to inject a small amount of controllable S0 ₃ into the flue gas, and the S0 ₃ acid mist is adsorbed on the fly ash and forms on the surface of the fly ash. An adsorption layer, which reduces specific resistance through surface conduction, makes dust easier to collect, thereby improving dust removal efficiency. Although this technology is relatively well developed and widely used, there are still some problems, which are reflected in the following aspects: (1) S0 ₃ can combine with water vapor in the flue gas to generate sulfuric acid vapor, thereby reducing static electricity. Corrosion occurs in the dust collector and flue; (2) Some S0 ₃ will be discharged to the atmosphere through the chimney, affecting the atmospheric environment; (3) The clogging and corrosion of the injector nozzle is also a problem during the operation and maintenance of the S0 ₃ flue gas conditioning device. A problem that is generally concerned; (4) It is expensive, and the daily maintenance and operation costs are relatively high. Therefore, the development of a safe, economical, environmentally friendly, and efficient new specific resistance regulator will be of great significance for reducing the concentration of dust emissions and meeting the increasingly stringent requirements of laws and regulations.

Contents of the invention

One of the objectives of the present invention is to provide a specific resistance regulator for reducing the specific resistance of fly ash. The specific resistance adjuster can reduce the specific resistance of dust, so as to solve the problem of the influence of high specific resistance dust on the dust removal efficiency of the electrostatic precipitator, and will not cause corrosion to the electrostatic precipitator, flue and injector nozzle.

The object of the present invention is achieved through the following technical solutions: a specific resistance regulator for reducing the specific resistance of fly ash is an aqueous solution containing alkali metal salts, and the alkali metal salts include sodium acetate and dipotassium hydrogen phosphate.

The specific resistance regulator provided by the present invention contains alkali metal salts, and there are sodium and potassium alkali metal ions. According to the conductive mechanism of fly ash, whether it is surface conduction or volume conduction, alkali metal ions are the main carriers of charge migration in the conduction process. The high specific resistance of fly ash is often also the reason for the low or difficult release of alkali metal ions. The specific resistance adjusting agent of the present invention provides additional appropriate amount of sodium and potassium ions for the fly ash, enhances the conductivity of the fly ash, reduces the specific resistance of the fly ash, and makes it reach the specific resistance range most suitable for the electrostatic precipitator.

In the present invention, the addition amount of sodium acetate and dipotassium hydrogen phosphate can be adjusted according to the properties of the fly ash of the power plant. As an embodiment of the present invention, in the solution, the mass percentage of the sodium acetate is 0.001%-0.01%, and the mass percentage of the dipotassium hydrogen phosphate is 0.001%-0.1%. Preferably, the mass percentage of the sodium acetate is 0.005%-0.01%, and the mass percentage of the dipotassium hydrogen phosphate is 0.01%-0.1%.

Further, the alkali metal salt also includes lignin sodium carbonate, which can not only provide sodium ions, but also has a certain degree of dispersibility, can be adsorbed on the surface of fly ash, enhance metal ion exchange, and promote sodium potassium ion exchange. The release of ions can more effectively reduce the specific resistance of fly ash. The mass percent of lignin sodium carbonate in the solution in the present invention is 0.001%-0.005%.

The second object of the present invention is to provide the application of the above-mentioned specific resistance regulator, specifically, the application of the specific resistance regulator in removing high specific resistance fly ash in power plant dust removal.

The third object of the present invention is to provide a method for using the above-mentioned specific resistance regulator in dust removal in power plants. Specifically, the method of use is as follows: test the properties of flue gas and fly ash, the concentration of particulate matter emission and the amount of flue gas, determine the specific resistance according to the test results to adjust the dosage of each component, and put the specific resistance regulator in the flue before the electrostatic precipitator. The particle size of 10-40 μm is sprayed, and the specific resistance adjusting agent is adsorbed on the fly ash particles, thereby reducing the specific resistance of the fly ash and improving the removal efficiency of the electrostatic precipitator for the high specific resistance fly ash. The dosage of the specific resistance regulator is different for different units. The injection quantity of the specific resistance regulator is related to the boiler flue gas volume. The amount of the regulator required for 10000m ³ flue gas per hour is about 1t, and the effect is the best at this time.

The present invention has the following advantages:

(1) The specific resistance regulator of the present invention can effectively reduce the specific resistance of fly ash and improve the removal efficiency of the fly ash.

Sodium acetate and dipotassium hydrogen phosphate provide the fly ash with an additional amount of sodium and potassium ions, enhance the conductivity of the fly ash, reduce the specific resistance of the fly ash, and make it reach the most suitable specific resistance range for the electrostatic precipitator. When the specific resistance regulator further contains lignin sodium carbonate, lignin sodium carbonate can not only provide sodium ions, but also has a certain degree of dispersibility, can be adsorbed on the surface of fly ash, enhance metal ion exchange, and promote sodium and potassium ions The release of fly ash can significantly reduce the specific resistance of fly ash, and can reduce the dust concentration at the outlet of electrostatic precipitator in coal-fired power plants by about 30%, which has broad commercial prospects.

(2) The main component of the specific resistance regulator of the present invention is a salt substance, which effectively reduces the corrosion of the regulator to the flue.

(3) The specific resistance regulator of the present invention has wide sources of raw materials, low price, simple chemical composition, simple and quick synthesis process, and is suitable for industrial promotion.

(4) The specific resistance adjusting agent of the present invention has no pollution to the environment and conforms to the current environmental protection concept.

(5) Since most of the toxic heavy metals are concentrated on fine particles, the integrated removal of heavy metals can also be realized by using the specific resistance regulator of the present invention.

Description of drawings

Fig. 1 is a flow chart of the method for using the specific resistance regulator of the present invention.

Detailed ways

The preparation method of the specific resistance regulator of the present invention: add tap water in a mixing container, then add sodium acetate and dipotassium hydrogen phosphate under constant stirring, after the two are completely dissolved, add lignin sodium carbonate, and then stir until completely dissolved That's it.

The specific resistance adjuster is stored independently according to different components before mixing, and can also be stored as a high-concentration solution in proportion, and diluted with tap water in proportion when used. But the time should not be too long, preferably a week.

According to different power plants, different flue gas conditions and coal-fired fly ash characteristics, adjust the proportion of different components of the specific resistance regulator, determine the dosage of the specific resistance regulator, arrange a double-flow atomizing nozzle in the flue before the dust collector, and mix the specific resistance regulator Spraying with a particle size of 10-40μm reduces the specific resistance of fly ash, improves the removal efficiency of dust collectors for high specific resistance fly ash, reduces the concentration of smoke and dust emissions, reduces the cost of sewage discharge of enterprises, and protects the atmospheric environment.

The following examples will be listed in detail, and the percentages in the examples are all percentages by mass.

Example 1

Sodium acetate 0.001%

Dipotassium hydrogen phosphate 0.001%

Sodium Lignin Carbonate 0.001%

The rest is water.

Test the properties of flue gas and fly ash, the emission concentration of particulate matter and the amount of flue gas, and determine the specific resistance according to the test results to adjust the dosage of each component, such as the above-mentioned ratio. The specific resistance regulator is sprayed into the flue between the air preheater and the electrostatic precipitator. Under the action of external air, the specific resistance regulator is atomized into droplets with an average particle size of about 30 μm and sprayed into the flue. Interaction occurs in the flue, and the residence time is about 10s. The specific resistance regulator contacts and fuses with the fly ash to adjust the specific resistance, and then is captured by the subsequent electrostatic precipitator. At the outlet of the rear of the electrostatic precipitator, an isokinetic sampler is used for constant-current sampling to measure the particle emission concentration. The results show that after spraying the specific resistance regulator, the dust concentration after the dust removal device dropped from 130.6mg/m ³ to 90.8mg/m ³ when the specific resistance regulator was not sprayed, and the reduction ratio reached 30.5%.

Example 2

Sodium acetate 0.005%

Dipotassium hydrogen phosphate 0.005%

Sodium lignin carbonate 0.002%

The rest is water.

Test the properties of flue gas and fly ash, the emission concentration of particulate matter and the amount of flue gas, and determine the specific resistance according to the test results to adjust the dosage of each component, such as the above-mentioned ratio. Before the electrostatic precipitator, the specific resistance regulator is sprayed into the vertical flue with a particle size of about 25 μm at a flow rate of 0.05Kg/ ^Nm3 flue gas through a liquid distribution pump, compressed air, and double-flow atomizing nozzles. The original 38.8mg/Nm ³ is reduced to 25.7mg/Nm ³ , a reduction of about 33.8%, meeting the latest national coal-fired power plant particle emission standards.

Example 3

Sodium acetate 0.007%

Dipotassium hydrogen phosphate 0.007%

Sodium Lignin Carbonate 0.005%

The rest is water.

Example 4

Sodium acetate 0.01%

Dipotassium hydrogen phosphate 0.1%

Sodium Lignin Carbonate 0.005%

The rest is water.

Example 5

Sodium acetate 0.003%

Dipotassium hydrogen phosphate 0.003%

Sodium lignin carbonate 0.002%

The rest is water.

Example 6

Sodium acetate 0.007%

Dipotassium hydrogen phosphate 0.05%

Sodium Lignin Carbonate 0.005%

The rest is water.

Example 7

Sodium acetate 0.01%

Dipotassium hydrogen phosphate 0.01%

Sodium Lignin Carbonate 0.003%

The rest is water.

Claims (8)

1. for reducing a ratio resistance conditioning agent for fly ash resistivity, it is characterized in that, described ratio resistance conditioning agent is the aqueous solution containing alkali metal salt, and described alkali metal salt comprises sodium acetate and dipotassium hydrogen phosphate.

2. the ratio resistance conditioning agent for reducing fly ash resistivity according to claim 1, is characterized in that, the mass percent concentration of described sodium acetate is 0.001%-0.01%, and the mass percent concentration of described dipotassium hydrogen phosphate is 0.001%-0.1%.

3. the ratio resistance conditioning agent for reducing fly ash resistivity according to claim 1, is characterized in that, the mass percent concentration of described sodium acetate is 0.005%-0.01%, and the mass percent concentration of described dipotassium hydrogen phosphate is 0.01%-0.1%.

4. the ratio resistance conditioning agent for reducing fly ash resistivity according to any one of claim 1-3, it is characterized in that, described alkali metal salt also comprises lignin sodium carbonate.

5. the ratio resistance conditioning agent for reducing fly ash resistivity according to claim 4, is characterized in that, described lignin sodium carbonate mass percent concentration is in the solution 0.001%-0.005%.

6. the application in high specific resistance flying dust removed by the ratio resistance conditioning agent described in any one of claim 1-5 in power plant's dedusting.

7. the using method of ratio resistance conditioning agent in power plant's dedusting described in any one of claim 1-5, it is characterized in that, sprayed into 10-40 μm of particle diameter by ratio resistance conditioning agent in flue before deduster, described ratio resistance conditioning agent is adsorbed on fly ash granule, thus reduces the ratio resistance of flying dust.

8. the described using method of ratio resistance conditioning agent in power plant's dedusting according to claim 7, is characterized in that, 10000m per hour ³needed for flue gas, the amount of ratio resistance conditioning agent is 1t.