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1. What is the "ultra -low emissions" of coal -fired power plants?
The smoke and dust emitted by the coal -fired power plant, sulfur dioxide and nitrogen oxide three air pollutants Compared with the combustion engine specified in the "Film Plant Air Pollution Emissions Standards" (GB13223-2011), the combustion machine must be performed, which will be called the "ultra-low low low value of the burning machine emissions limit value, which will reach or lower than the liberal discharge limit value. emission". Among them, in the case where the coal quality is more suitable, the use of technology and economy's feasible flue gas pollution treatment technology makes the discharge of smoke, sulfur dioxide, and nitrogen oxides less than 10 mg/cubic meter, 35 mg/cubic meter, 50 mg/50 mg//50 mg/50 mg/50 mg/50 mg//50 mg//50 mg//50 mg/50 mg/50 mg/50 mg/50 mg/50 mg/50 mg/50 mg//50 mg//50 mg//50 mg//50 mg/50 mg/50 mg/50 mg. Cubic meter of coal electrical units are called ultra -low -emission coal electrical units; the discharge of smoke, sulfur dioxide, and nitrogen oxides is less than 5 mg/cubic meter, 35 mg/cubic meter, 50 mg/cubic meter of coal power units. In order to meet the emission standards of the vapor wheel unit.
2. What is a electrostatic dust collector? Which part of it is formed?
static dust collector is a device that uses electric halo to discharge, so that the gray belt in the flue gas is separated by static electricity.
is composed of discharge electrodes, dust collection, high -voltage DC power supply device, vibration device and shell.
3. What is the working principle of electricity?
In the uneven electrical field composed of electrical poles and dust collecting poles, it uses the electrode (electric halo pole) as the negative pole. The dust collection is extremely positive. Silicon rectifier transformer flows 380V AC electricity to 72kV high -voltage DC power, and is generated by the beam by introducing high -voltage electrostatic fields by electromotive pole). When the intensity of this electric field is more alert to a certain value, negative halo is formed around the electromotive pole, and the ionization effect of the gas molecules is strengthened to produce a large number of positive and negative ions. Positive and negative ions are divided into electromotive poleness, and negative ions and free electrons are transferred to dust. When the gas with powder passes, these particles with electricity loads are constantly encountered and adsorbed on the dust particles in exercise to make the dust powder electricity. Under the influence of the electric field force, the dust powder quickly moved to the dust collection pole (anode plate), released negative charge, and it was deposited on the dust plate.
During the running of a positive ion, the dust in the electromotive area is charged with a positive charge and moves to the electromotive plate. The collected dust dropped through the vibration device, and it was discharged by the ash drainage motor in the lower gray bucket that gathered in the lower part, so that the gas was purified.
4. What are the main factors that affect the efficiency of electric dust collector efficiency?
The main factors that affect the efficiency of electrical dust collectors are: dust ratio, gas temperature, flue gas speed, gas humidity, dust concentration, electromotivity, airflow distribution, air flow distribution Uniformity, vibration method, etc.
5. What are the causes of uneven distribution of electricity removal?
1) Unewal distribution caused by boilers;
2) Cultivation caused by friction in the flue;
3) due When turning around Due to great reduction due to the inner speed;
4) Dust dust deposits too much in the flue to severely disorders the airflow;
5) The spread of imported cigarette cases is too fast to cause uneven flow distribution of the central flow rate;
6) Boiler leakage.
6. What are the impact of unevenness in the airflow on electrical dust removal?
1) The dust caught in areas with different airflow speeds is different, and the dust removal efficiency with low airflow speed is high. In general, the impact of too high wind speed is greater than the low wind speed;
2) Awescases with high local air flow velocity appear to produce secondary flying;
3) Take away:
4) dust collector some parts of some parts in turn will further destroy the uniformity of airflow.
7. What are the reasons for the electric field of electricity elimination machine?
1) The anti -electrical halo of high ratio resistance dust will produce secondary flying;
2) The flue flow velocity is too high to produce secondary fly; Two flights;
4) The frequency of the vibration is too fast, so that the dust is fascinated from the dust from the dust and the flue gas is taken away by the flue gas, which generates a fly;
5) Take away the dust and generate a second fly.
8. How to prevent the electric dust collector from generating a second flight?
1) Makes a good airflow distribution inside the electric dust collector; Enough High -voltage group electric fields are connected in series;
4) take turns to balance the high -voltage packet electric field;
5) Strictly prevent the air flow and leakage of air flow in the gray bucket.
9. What is a flying ash ratio resistance?
unit area and unit thickness flyy ash resistance is often expressed in its resistivity, the unit is ω/cm. The resistance of the length and cross -section is the resistance of the resistance when each unit, that is, the wire length of the wire is 1cm and the cross -sectional area is 1cm2.
dust is usually divided into low -ratio resistance dust (ρ ρ ρ ρ ρ 1010Ω · cm), which is an important factor that affects the efficiency of the dust collector.
10. What is the effect of resistance on the dust removal effect?
is usually between 104 ~ 5 × 1010Ω · cm. The effect of the effect on the dust removal effect is more than 5 × 1010Ω · cm than 5 × 1010Ω · CM It affects the electricity current, the amount of dust and the amount of dust and the yield, and reduce the dust removal efficiency;
2) High ratio resistance will increase the dust adhesion of the dust, it is not easy to be beaten down, and it is easy to generate secondary flying, which reduces the dust removal efficiency.
3) Low -ratio is easy to obtain positive charge due to static and electrostatic induction, so that the dust on the pole plate is rejected into the electric field space.
11. Why should the unit be pay attention to the time of the power dust collector during the startup?
boiler If the fuel gun is not atomized, the unburned oil droplets will defile the electrocomputer dust collector's pole, thereby reducing the dust removal efficiency of the dust collector's dust removal efficiency Therefore, the early operating units required that the dust collector or the use of the wing flue was required during the startup period. At the same time, the power heater and the electrocomputer are used to prevent the surface of the porcelain bottle from being exposed to the short circuit of the flashes, and it can timely make the dust on the pole plate from being beaten down to prevent the efficiency of dust removal.
is generally upgraded through oil gun upgrades to improve the combustion efficiency and avoid the impact of unbustly droplets on the dust collector.
12. What are the safety precautions of electric dust collector when running?
electric dust collector has high voltage and high dust in each electric field. When stopping and running, there will also be high -voltage induction electricity inside the electric field, so you must pay attention to the following safety matters:
1) Dust -proof at the running high -voltage switching cabinet When working inside the dust collector, you must strictly implement the work ticket system, cut off all the power supply, isolate the flue gas channel, when the temperature inside the dust collector drops below 40 ° C, the working part should have reliable grounding and formulate reliable security measures;
3) Enter the electric field into the electric field Before, the high voltage isolated switch knife was shot to the "grounding" position to discharge the electric field, reliable ground to eliminate residual static electricity;
4) Before entering the electric field, the ash storage in the gray bucket should be placed to fully ventilate.
13. What is the impact of flue gas humidity on the dust removal efficiency?
boiler flue gas contains moisture, the more moisture in the flue gas is analyzed in principle, the higher the dust removal efficiency, The temperature level reaches the dew point, especially when the sulfur dioxide content in smoke is relatively large, the high humidity will corrode the electrode system and metal components, which will damage the equipment and affect the effect of dust removal. For the bag dust collector, there is still risk of damage to the cloth bag after the dampness of the flue gas is too large.
14. What effect does the electric dust removal leakage affect it?
1) The electric dust removal machine is at a negative pressure operation. If the shell has a leakage point, the external air will leak, causing the smoke speed of the electric dust collector;
2) The leakage from the lower part of the ash fight will cause the ash in the ash to generate a second fly, which will reduce the dust removal efficiency.
15. The working principle of the cloth bag dust collector?
gas -containing gas enters the unit room from the pipe from the pipe. Under the action of the derivative device, the large particle dust is separated directly into the ash fight. The dust is uniformly entered into the filter bag in each warehouse filter area. When the dust -containing gas passes through the filter bag, the dust is adsorbed on the filter bag, and the purified gas is eliminated from the filter bag. When the dust adsording on the filter bag reaches a certain thickness solenoid valve, the spraying air enters the filter bag from top to bottom from top to bottom from top to bottom exit of the filter bag. In the ash bucket, the dust was discharged by the ash dumping system after the dust removal valve was discharged.
16. What are the advantages of cloth bag dust collectors?
dust removal efficiency is high; the ability to capture small dust is strong; large amount of smoke; strong adaptability to coal type.
17. What are the basic mechanisms of the dust particles deposited on the filter bag fiber?
basic mechanism includes: interception, inertia collision, diffusion, gravity, static attraction.
18. What are the advantages of the electric bag dust collector?
combines the advantages of electric dust removal and cloth bag dust collector.
19. What are the technical principles of wet -type dust removal?
Wet -type dust removal metal discharge wires ionize the surrounding gas, the dust in the electric field and the electric field power under the electric field power under the influence of DC Exercise, when exercise to the surface of the dust collection, it is removed with the liquid membrane flowing down. Use liquid to rinse the dusty surface to clear the ash, and at the same time, the dust forms the slurry and discharged.
20. What are the advantages and disadvantages of wet electricity dust removal?
Wet dust removal and dust collection performance has nothing to do with the characteristics of dust, which can be effectively collected for large or high -resistant dust dust. Without a second dust, the export dust concentration can be less than 5mg/nm3. Because there is no rotating parts like a hammer device, the reliability is high, which can effectively collect sulfuric acid fog solids and sub -micron grapees in flue gas.
The design flow velocity of conventional electrocomputer dust flue flue is 15m/s, and the design flow rate of wet electrocompany dust collector is 2 ~ 3 m/s. Large area. Due to the large volume of the wet dust collector and heavy weight, the need for a stand is heavier than the conventional flue bracket. Because the wet dust collector uses hydraulic ash, waste water will be generated during the operation. Due to the stickiness of the gypsum slurry adsorbed by the wet dust collector, there is a risk of scaling on the dust collector's plate, which has high requirements for operation. Due to the corrosiveness of the plaster pulp absorbed by the dust collector, the appropriate anti -corrosive material needs to be selected.
21. Common desulfurization method?
at home and abroad can currently be divided into three categories: desulfurization before burning, desulfurization during burning, and after burning.
before burning desulfurization is to wash the coal with coal washing technology, wash out most of the combustible inorganic sulfur in the coal, reduce the sulfur content in the combustion coal, thereby achieving the purpose of reducing pollution; Desequent) is to invest a certain amount of desulfurization agent at the same time during the burning of the coal powder, and the sulfur dioxide is removed from desulfurization during combustion. Typical technology is circulating fluidized bed technology; desulfurization (that is, the flue gas desulfurization) after combustion, which is a method of decorating the deoxy equipment outside the flue. The typical technology is limestone-gypsum method, spray drying method, electronics, electronics, electronics, and electronics. Bid method, ammonia method, etc. Among them, the most applications are limestone-gypsum method.
22. What is the wet fans?
Wet Fun Sulfur desulfurization uses a liquid absorbent to wash the flue gas to absorb SO2 and high desulfurization efficiency. Wet desulfurization technology is advanced and mature, safe and reliable operation, high desulfurization efficiency, suitable for large units, wide coal adaptability, and by -product recovery. The main disadvantages systems are complicated, the equipment is large, the area is large, the one -time investment is large, the operating cost is high, and the water consumption is large.
23. What is dry fans?
dry smoke desulfurization means that the desulfurization agent is dry or wet, and the final reaction product of desulfurization is dry.The cost of drying of dried flue gas desulfurization is relatively low; desulfurization products are dry and mixed with fly ash; no mixture and flue gas heaters are not required; the equipment is not easy to corrode, and it is not easy to occur and blockage. However, the use of dry smoke desulfurization absorbers is low; it is used for poor economy for high sulfur and coal; mixing of fly ash and desulfurization products may affect comprehensive utilization.
24. What is NOX emissions control technology?
uses the nitrogen -based middle product generated by the combustion process or spray ammonia to the flue. It restores NOX at the right temperature, atmosphere or catalyst. mechanism. This derived from the selective non -catalytic reducing flue gas denitration (referred to as SNCR) and the selective catalytic rejuvenation of the furnace of the fang (Referred to as SCR) three types of technologies, these technologies can be used alone or in combination.
25. What is SCR and SNCR denitration?
SCR is the abbreviation of selective catalytic restoration. Under the action of catalysts, spray ammonia to restore the NOX in the flue gas to N2 and H2O. Non -precious metals.
SNCR is the abbreviation of selective non -catalytic reduction. The reducing agent containing the NH3 base is sprayed into the area with a furnace temperature of 800 ~ 950 ° C. NOX reaches the process of generating N2.
26. What are the main technical means of circulating fluidized bed boiler denitration device?
SNCR mainstream, some new crew crews use the method of reserving SCR space to meet the ultra -low emissions.
27. What is the reducing agent of recycling fluidized bed boiler SNCR denitration?
denitration systems are mainly three types: liquid ammonia, ammonia water, and urea . one. Most power plants use urea, a small part of ammonia water, and some chemical self -provided plants or experienced power plants also use liquid ammonia.
28. What SNCR denitration reactor cigarette window?
reactive temperature range is called reaction cigarette window, sometimes also called temperature windows. The temperature interval suitable for the occurrence of SNCR reaction is generally 800 ~ 950 ° C. When the reaction temperature is too high, due to the decomposition of ammonia, the NOX reduction rate will be reduced. On the other hand, when the reaction temperature is too low, the escape of ammonia increases and will also reduce the NOX reduction rate.
29. Why is the efficiency of circulating fluidized bed boiler SNCR denitration higher than that of the coal boiler?
CFB boiler unique structure can help uniform mixing of flue gas and spray into the reducing agent. Strong mixed effect. Industrial experimental research also shows that the spraying point of the horizontal flue setting before the separator can significantly reduce the ammonia nitrogen ratio, increase the denitration efficiency, and reduce the amount of ammonia escape. The denitration efficiency of conventional SNCR smoke denitration technology is greatly affected by the size of the boiler structure. It is mostly used as a supplementary process of low NOX combustion technology. The CFB boiler unit, due to the use of low -nitrogen combustion technology, the burning temperature is low, the secondary wind grading is given, the hypoxia combustion of the lower part of the furnace, and the hypoxia reduction area in the center of the furnace can effectively suppress NOX generation. The nOX emissions of the coal flood is 40%~ 60%. Therefore, the CFB boiler denitration is most suitable for SNCR technology. The current trend is to replace ammonia with more secure urea as a reducing agent.
30. Why should not adopt SCR denitration?
will bring inconvenience to boiler design and installation, and the problem of limited space in boiler is put into installation and installation on the boiler design and installation. On the other hand, the gray concentration of the tail of the CFB boiler is much higher than that of the coal flour boiler. The service life of the catalyst is short, and the related operating costs have increased. Because the addition of catalysts will oxidize SO2 to SO3 and react with the escape ammonia reaction to form ammonia sulfate and ammonium sulfate, which can easily cause ash block and corrosion of the air pre -ash, affecting the operation safety of the unit.
31. When using urea solution as a reducing agent, the effect of SNCR on boiler efficiency?
sprayed into the furnace concentration is about 10%. The effect on the efficiency of the boiler is mainly the heat loss caused by water vaporization in the solution. Several parts of the heat absorption and ammonia reaction of ammonia when the thermal dissolving into ammonia in the furnace:
can be seen from the above formula, the reaction is the heat -to -boiler efficiency, but considering that the reaction is PPM level, the reaction is PPM level, but the reaction is PPM level. Can ignore its impact on efficiency. Based on the NOX concentration based on 150mg/nm3 and NSR based on 1.5, the heat loss caused by water vaporization in the solution will reduce the efficiency of the boiler by about 0.1%.
32. After adding SCR/SNCR, what are the special requirements for air preheat?
In view of the increasingly stricter environmental standards, fluidized bed boilers also need to add deep denitrification equipment. Due to a small amount of NH3 escape, it is inevitable. SO3 also exists objectively, so it is bound to produce some hydrogen sulfate. The substance is liquid and strongly adhesive between 146 and 207 ° C. Therefore It is easy to clean up, it is best to use a dedicated plate -type enamel plate rotary heater. If a tube -type heater is used, enamel tube should also be adopted in the low temperature section.
33. What does the SNCR denitration device affect the boiler's heating surface?
SNNCR denitration technology is sprayed with urea solution in the furnace as a reducing agent. During the normal operation of the boiler, it will not cause significant corrosion of the heating surface system in the furnace:
1) The denitrization system is sprayed to the furnace is that the denitration agent does not increase the acidity of the atmosphere in the furnace. Urea is weakly alkaline, so the dehydrated dehydration is weakly alkaline. From the perspective of acid and alkali corrosion, it is conducive to reducing corrosion. From the perspective of the chemical process of denitration, the NH3 consumes the NOX reaction to generate neutral N2 and water, and NOX is more acidic than cyanide. Therefore, after the denitration reaction, the acidity of the atmosphere in the furnace will be reduced; The spray -sprayed denitration in the furnace only occupies a small part of the material and gas in the furnace, except for selectively remove NOX (the content of NOX in the flue gas is also low). The nature of the nature does not have a significant impact;
3) The injection point of the reducing agent is at the inlet of the whirlwind separator. The main reaction area of the denitration is the whirlwind separator. This area is applied to the refractory wear material, which has a good corrosion resistance.
4) The CFB furnace decreased in the CFB furnace, which reduces the content of SO2 and SO3, which reduces the possibility of generating ammonium compound NH4HSO4 and (NH4) 2SO4. There may be corrosive and heating surfaces.
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