Boiler flue gas denitration and dust removal device and application method thereof
Technical Field
The invention belongs to the technical field of denitration and dust removal of boiler flue gas, and particularly relates to a denitration and dust removal device for boiler flue gas and a using method thereof.
Background
The boiler smoke emission seriously pollutes the atmospheric environment, and has serious harm to human health, air quality and social sustainable development. The atmospheric pollutants discharged by the combustion of boiler fuel mainly comprise Particulate Matters (PM) and sulfur dioxide (SO)2) And Nitrogen Oxides (NO)x) These pollutants are key pollutants for atmospheric environmental management and pollution source emission control in China at present.
In recent years, more researches on environmental influence and management control of atmospheric pollution of coal-fired power plant boilers are carried out in China, and relatively less researches on environmental influence and management control of atmospheric pollution of various and wide small and medium-sized boilers are carried out. With the increasing requirements of atmospheric environment treatment and the increasing requirements of the emission concentration limit of boiler atmospheric pollution, the treatment of atmospheric pollutants discharged by smoke of small and medium-sized coal-fired and oil-fired boilers is urgent. And boiler NOxIf the emission of the nitrogen oxides is not enhanced, the total amount of the nitrogen oxides and the specific gravity of the nitrogen oxides in the air pollution are increased, and SO can be replaced2Becoming a major pollutant in the atmosphere.
Discharge standard of boiler atmospheric pollutants in Shandong province (DB 37-2374-2013) in 24 Ri Shandong province in 2013 for newly built boiler atmospheric pollutants NOxAnd the emission concentration limit of the smoke dust is required to be as follows:
unit: mg/m3(except for blackness of smoke)
The flue gas denitration treatment project is started later in China, the process adopted by the currently domestic running flue gas denitration project is also the denitration technology of developed countries such as Europe and America, and the flue gas denitration technology with independent intellectual property rights and manufacturing equipment are urgently required to be developed and put on the market in China. The main domestic methods for denitration of boiler flue gas are an SNCR (non-catalytic reduction) method and an SCR (selective catalytic reduction) method, and the two methods have large investment and cannot be applied to denitration of small and medium-sized industrial boilers.
SNCR method comprises spraying nitrogen-containing reducing agent (such as ammonia water and urea) into flue gas, and adding NOxThe method has the main advantages of more usable reducing agent types and low operating cost. The method has the defects that the temperature used in the working process is high (850-1100 ℃), the temperature dependence is strong, the denitration rate is low and is only 30-50%, and the method is only applied to large boilers at present.
The SCR method has the advantages that the method has the similar chemical principle to the SNCR method except that one catalyst is added, and NO can be removed within the temperature range of 200-400 ℃ due to the use of the catalystxThe denitration rate is high and can reach 80-90%, the defects are that the occupied area is large, the investment cost is high, and the catalyst needs WO3Or V2O5The catalyst is expensive, is easy to age and inactivate, needs to be replaced regularly, has high operation cost, and is only applied to denitration of large boilers at present.
The two methods have the defects of high investment and operation cost and large occupied area of facilities, so that the two methods can only be used for flue gas denitration of large boilers in power plants at present, and are difficult to popularize and use for medium and small boilers with large quantity. Most denitration dust collecting equipment used in the market at present has the defects of high cost, complex operation, low treatment efficiency, high operation cost and the like, and the popularization and the application of the product are restricted to a great extent.
The iron-carbon micro-electrolysis technology is mainly used for treating industrial wastewater at present, and the filler adopted by the technology is generally cast iron scraps and coke particles, and has strong reducing capability in a water medium with acidity and oxygen.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a boiler flue gas denitration and dust removal device. The device can be used for denitration and dust removal of flue gas of small and medium-sized boilers, and has the advantages of low investment, low operating cost, small occupied area of equipment, easy operation and high denitration and dust removal efficiency.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the utility model provides a boiler flue gas denitration dust collector which characterized in that: comprises a water film dust collector, a denitration tower, a draught fan, a chimney, a heat exchange device and NH4Cl solution reservoir, NH4A Cl solution circulating pump; the denitration tower is a cylindrical container with an upper end enclosure and a lower end enclosure, a glass fiber reinforced plastic anticorrosive coating is lined in the denitration tower, a liquid outlet is arranged at the bottom of the denitration tower, an air inlet and an air outlet are respectively arranged at the lower part and the upper part of the denitration tower, a steel supporting plate, pebbles and micro-electrolysis filler are sequentially arranged in the denitration tower from bottom to top above the air inlet and below the air outlet, a plurality of holes are uniformly arranged on the steel supporting plate, the steel supporting plate is tiled and fixed on the inner wall of the denitration tower, the pebbles are tiled on the steel supporting plate, the micro-electrolysis filler is tiled on the pebbles, a water distributor is fixedly arranged at the4The Cl solution circulating pump is connected with the NH through a pipeline4An electromagnetic valve and NH are arranged on the pipeline between the Cl solution circulating pumps4Cl solution circulating pump and NH4The Cl solution storage pool is connected through a pipeline, the two ends of the heat exchange device are respectively connected with the water film dust collector and the air inlet of the denitration tower through pipelines, the air outlet of the denitration tower is connected with the induced draft fan through a pipeline, and the induced draft fan is connected with the chimney through a pipeline.
The micro-electrolysis filler is a mixture of cast iron scrap and coke particles, the mass ratio of the cast iron scrap to the coke particles is 10-20: 1, and the particle size ranges are 1-3 cm.
The aperture of the hole on the steel supporting plate is 10 mm.
The particle size of the pebbles is phi 40mm, and the laying height of the pebbles is 150 mm.
The NH4The Cl solution storage pool is positioned under the liquid outlet.
The heat exchange device is a heat exchanger.
The invention also aims to provide a method for applying the boiler flue gas denitration dust removal device, which comprises the following steps:
step one, spraying: open solenoid valve and NH4Circulation of Cl solution to make NH4NH of Cl solution reservoir4Solution of Cl with NH4Pumping out Cl solution by a circulating pump and conveying to a water distributor through a pipeline, and NH4Spraying Cl solution onto the micro-electrolysis filler through a water distributor to ensure that the micro-electrolysis filler is always soaked in NH4In the Cl solution, the reaction temperature of the micro-electrolysis filler and NOx gas is controlled to be 50-90 ℃, if the temperature of the flue gas of a boiler is too high, the reaction temperature can be controlled by adjusting a heat exchange device, the filling amount of the micro-electrolysis filler is 70% of the volume of the denitration tower, the micro-electrolysis filler is timely added according to the consumption amount of the micro-electrolysis filler, the flue gas generated by the boiler sequentially passes through a water film dust collector and the heat exchange device through a pipeline, the water film layer of the water film dust collector is alkali liquor with the pH =12, and the water film dust collector is used for removing smoke dust with large particles in the flue gas;
step two, denitration: the flue gas after dust removal enters the denitration tower from the air inlet of the denitration tower through a pipeline, and NH is arranged on the flue gas in an upward passing mode4NO in flue gas when Cl solution is used for soaking micro-electrolysis fillerxCarrying out oxidation reduction reaction with micro-electrolysis filler to generate N2And Fe3 +Generation of N2Under the action of a draught fan, the NH is discharged from an air outlet of the denitration tower and a pipeline flowing to a chimney4Fe in Cl solution3+Adsorbing fine soot particles with NH4Leaching Cl solution together to form iron mudThe liquid outlet is discharged and enters NH4The Cl solution is deposited in a storage pool, and the deposit is used for producing agricultural fertilizer or building bricks, is environment-friendly and pollution-free, and is NH4The concentration range of the Cl solution is 3% -5%, and NH is added4The Cl solution has a pH value ranging from 5 to 6, and is added at any time according to the consumption of NH4NH in Cl solution reservoir4NH for Cl solution4And the Cl solution circulating pump is recycled.
In the first step, NH4The spraying amount of the Cl solution per hour is 5-10 times of the volume of the micro-electrolysis filler in the denitration tower.
The invention has the following beneficial effects:
1. the invention applies the micro-electrolysis technology to the denitration and dust removal of the flue gas of the small and medium sized boiler, expands the application field of the micro-electrolysis technology, has less investment, low operation cost, small occupied area of equipment, easy operation and high denitration and dust removal efficiency, solves the denitration and dust removal treatment problem of the small and medium sized boiler, and ensures that the NO discharged by the treated flue gas of the small and medium sized boiler is NOxThe smoke dust meets the emission standard of boiler atmospheric pollutants in Shandong province at present and also meets the emission standard of boiler atmospheric pollutants newly revised by the department of environmental protection;
2. the flue gas and the iron in the micro-electrolysis filler of the invention are subjected to micro-electrolysis reaction to generate Fe2+,Fe2+Oxidation to Fe3+,Fe3+The flue gas dust remover exists in a micelle form, has strong adsorbability and coagulation, and can cause fine smoke dust particles in flue gas to be adhered and coagulated and be washed down together with water, thereby achieving the aim of dust removal;
3. n generated by micro-electrolysis reaction2The iron mud generated by the micro-electrolysis reaction has no toxicity, is used for producing agricultural fertilizers or building bricks, and is environment-friendly and pollution-free;
4. the micro-electrolysis filler has long service life, is mostly waste materials, has easily obtained raw materials, has the advantage of treating waste by waste, and has certain economic benefit and environmental benefit.
Drawings
The drawings are only for purposes of illustrating and explaining the present invention and are not to be construed as limiting the scope of the present invention. Wherein,
FIG. 1 is a schematic structural diagram of a boiler flue gas denitration dust removal device of the present invention.
Reference numerals:
1. the device comprises a water film dust remover, a denitration tower, a solenoid valve, a water distributor, a microelectrolysis filler, a draught fan, a chimney, a pebble, a liquid outlet, a liquid inlet, a steel supporting plate, a gas outlet, a heat exchange device, a water distributor, a micro-electrolysis filler, a chimney and a chimney, wherein the water film dust remover comprises 2, the denitration tower, 3, the solenoid valve, 4, the water distributor, 5, the microelectrolysis4Cl solution reservoir, 15.NH4And a Cl solution circulating pump.
Detailed Description
In order to make the technical features, objects, effects, and embodiments of the present invention more clearly understood, embodiments of the present invention will now be described with reference to the accompanying drawings.
As shown in figure 1, the boiler flue gas denitration dust removal device comprises a water film dust remover 1, a denitration tower 2, an induced draft fan 6, a chimney 7, a heat exchange device 13 and NH4Cl solution reservoir 14, NH4A Cl solution circulating pump 15; the denitration tower 2 is a cylindrical container with an upper end enclosure and a lower end enclosure, a glass fiber reinforced plastic anticorrosive coating is lined in the denitration tower 2, a liquid outlet 9 is arranged at the bottom of the denitration tower, an air inlet 10 and an air outlet 12 are respectively arranged at the lower part and the upper part of the denitration tower, a steel supporting plate 11, pebbles 8 and micro-electrolysis fillers 5 are sequentially arranged in the denitration tower 2 above the air inlet 10 and below the air outlet 12 from bottom to top, a plurality of holes with the aperture of 10mm are uniformly arranged on the steel supporting plate 11, the steel supporting plate 11 is tiled and welded on the inner wall of the denitration tower 2, the pebbles 8 are tiled on the steel supporting plate 11, the granularity of the pebbles 8 is phi 40mm, the laying height of the pebbles 8 is 150mm, the micro-electrolysis fillers 5 are tiled on the pebbles 8, a water distributor4The Cl solution circulating pump 15 is connected with the water distributor 4 and the NH through a pipeline4The pipeline between the Cl solution circulating pumps 15 is provided with an electromagnetic valve 3, NH4Cl solution circulating pump 15 and NH4The Cl solution reservoir 14 is connected with NH through a pipeline4Cl solution reservoir 14 is located under liquid outlet 9, and heat transfer device 13 both ends are connected with water film dust remover 1, denitration tower 2's air inlet 10 through the pipeline respectively, and denitration tower 2's gas outlet 12 passes through the pipe connection with draught fan 6, and draught fan 6 passes through the pipe connection with chimney 7.
The micro-electrolysis filler 5 is a mixture of cast iron scrap iron and coke particles, the mass ratio of the cast iron scrap iron to the coke particles is 10-20: 1, and the particle size ranges are 1-3 cm.
A plurality of holes with the aperture of 10mm are uniformly formed in the steel supporting plate 11, and upward circulation of smoke is facilitated.
The heat exchange device 13 is a heat exchanger.
The present invention operates in particular as follows,
step one, spraying: opening solenoid valve 3 and NH4Cl solution circulating pump 15, NH4NH of Cl solution reservoir 144Solution of Cl with NH4The Cl solution is pumped out by a circulating pump 15 and is conveyed to the water distributor 4, NH through a pipeline4Cl solution is sprayed on the micro-electrolysis filler 5 through the water distributor 4, so that the micro-electrolysis filler 5 is always soaked in NH4In the Cl solution, the reaction temperature range of the micro-electrolysis filler 5 and NOx gas is controlled to be 50-90 ℃, if the temperature of the flue gas of a boiler is too high, the reaction temperature can be controlled by a heat exchange device 13, the filling amount of the micro-electrolysis filler 5 is 70% of the volume of the denitration tower 2, and NH is added into the denitration tower4The spraying amount of the Cl solution per hour is 5-10 times of the volume of the micro-electrolysis filler 5 in the denitration tower 2, and NH is ensured4The flow rate of the Cl solution enables the micro-electrolysis filler 5 to be soaked by the liquid all the time, and the micro-electrolysis filler 5 is not activated (NH)4Cl solution is catalyst), the micro-electrolysis filler 5 is timely added according to the consumption of the micro-electrolysis filler 5, the filling amount of the micro-electrolysis filler 5 is kept to be 70% of the volume of the denitration tower 2, flue gas generated by a boiler sequentially passes through the water film dust remover 1 and the heat exchange device 13 through pipelines, the water film layer of the water film dust remover 1 is alkali liquor with the pH =12, and the water film dust remover 1 is used for removing the alkali liquorRemoving the smoke dust with larger particles in the smoke;
step two, denitration: the flue gas after dust removal enters the denitration tower 2 from the air inlet 10 of the denitration tower 2 through a pipeline, and NH is upwards passed through the flue gas4NO in flue gas when micro-electrolysis filler 5 is soaked in Cl solutionx(mainly NO and NO)2) Carrying out oxidation reduction reaction with the micro-electrolysis filler 5 to generate N2And Fe3+Generation of N2Under the action of the draught fan 6, the NH gas is discharged from the gas outlet 12 of the denitration tower 2 and the pipeline flowing direction chimney 74Fe in Cl solution3+Adsorbing fine soot particles with NH4The Cl solution is leached together to form iron mud which is discharged from a liquid outlet 9 and enters NH4The Cl solution is deposited in the storage tank 14, the deposit is used for producing agricultural fertilizer or building bricks, the environment is protected, no pollution is caused, and NH is added4The concentration range of the Cl solution is 3-5%, the pH value range is 5-6, the Cl solution is added at any time according to the consumption amount, and NH is added4NH in Cl solution reservoir 144NH for Cl solution4The Cl solution circulating pump 15 is recycled.
Wherein the reaction principle of the denitration process in the second step is as follows:
microelectrolysis is a technology that cast iron scrap iron and coke particles form countless tiny primary batteries in a slightly acidic aqueous medium due to the electrode potential difference between iron and carbon, and the primary batteries have redox electrode behaviors so that certain pollutants are reduced and removed. In these particulate cells constructed with iron as the anode and carbon as the cathode, the following electrochemical reactions occur in the presence of oxygen:
anode (Fe): 2Fe → 2Fe2++4e E0Fe2+/Fe=0.44v
Cathode (C) 4H++4e-→4[H]→H2E0H+/H2=0.00v
In the presence of dissolved oxygen, O2+2H2O+4e-→4OH-E0O2/OH-=0.40v
In the electrolyte solution with subacid oxygen, the potential difference is large, the reaction speed is high, and a large amount of Fe2+In the solution, because the micro-electrolysis filler 5 is in the electrolyte soaking state, and the boiler flue gas is acidic, the micro-electrolysis filler can generate nascent hydrogen, has strong reducing capability, and performs the following chemical reaction:
2NO- 3+12H++10e →N2+6H2O EoNO3 -/N3=1.24v
2NO+4H++4e →N2↑+H2O EoNO/N2=1.68v
3NO2+H2O → 2HNO3+NO↑
2NO+2H2→N2+2H2O
the flue gas and the iron in the micro-electrolysis filler 5 are subjected to micro-electrolysis reaction to generate Fe2+,Fe2+Oxidation to Fe3+,Fe3+The dust remover exists in a micelle form, has strong adsorbability and coagulation, can make fine smoke dust particles in smoke be adhered and coagulated and washed down together with water, and achieves the aim of dust removal.
The invention can ensure NO discharged by the treated boiler flue gasxAnd the smoke dust not only meets the emission standard of boiler atmospheric pollutants in Shandong province at present, but also meets the emission standard of boiler atmospheric pollutants newly revised by the department of environmental protection. The invention applies the micro-electrolysis technology to the denitration and dust removal of the flue gas of the small and medium sized boilers, expands the application field of the micro-electrolysis technology, expands the treatment of the air pollution from the industrial sewage treatment, has less investment, low operating cost, small occupied area of equipment, easy operation and high denitration and dust removal efficiency, and solves the denitration and dust removal treatment problem of the small and medium sized boilers; n produced by micro-electrolysis2The iron mud generated by the micro-electrolysis reaction has no toxicity, is used for producing agricultural fertilizers or building bricks, and is environment-friendly and pollution-free; the micro-electrolysis filler 5 has a long service life,most of the raw materials are waste materials, the raw materials are easy to obtain, the method has the advantage of treating wastes with wastes, and has certain economic and environmental benefits.
The above description is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that various modifications, alterations, and combinations of these features can be made without departing from the spirit and scope of the invention.