CN1923341A - Device and method for coal-burning boiler fume ozone oxidation and simultaneous desulfurization and denitrification - Google Patents

Abstract

The invention relates to a device for removing several pollutants of boiler smoke. Wherein, it comprises (1), before or after the static deduster 5 of smoke channel 4, ejecting into ozone O3 at low temperature section as 110-150Deg. C, while the ratio between ejected amount and nitrogen oxide is 0.5-1.5, to oxidize the low-level nitrogen oxide insoluble into soluble high-level nitrogen oxide, and the sulfur oxide is transformed into sulfur trioxide, and the reaction time is more then 0.5s; (3), feeding treated smoke into alkali washing tower 7 to wash, and absorbing high-level nitrogen oxide and sulfur oxide.

Description

Coal-burning boiler fume ozone oxidation and simultaneous desulfurization denitrification apparatus and method thereof

Technical field

The present invention relates to environmental protection technical field, relate in particular to a kind of coal-burning boiler fume ozone oxidation and simultaneous desulfurization denitrification apparatus and method thereof.

Background technology

The oxysulfide that produces in the using energy source process, nitrogen oxide have caused serious day by day harm to the atmospheric environment of China.Present existing desulfur technology can be divided into several classes such as dry method, semidry method and wet method.Dry method, semidry method investment operating cost is low, but often has the not high shortcoming of desulfuration efficiency, and large-sized boiler combustion apparatus such as station boiler etc. often can not reach environmental requirement.What station boiler extensively adopted at present is limestone/gypsum wet process of FGD technology (WFGD), and this method desulfuration efficiency height is stable, but exists water consumption big, waste discharge secondary pollution, investment and the more high shortcoming of operating cost.

The control technology of nitrogen oxide mainly contains two classes: the first generic stove combustion process control mode, mainly contain the low-NOx combustor technology, and OFA (Over fire air) technology, the low oxygen combustion technology, combustion technology etc. is controlled NO by the combustion process adjustment again _xDischarging, can be with NO _xBe controlled at medium emission level, general denitration efficiency is about 30～50%.But these technology cause combustion stability to descend easily on the one hand, and burner region forms local reduction atmosphere easily, cause ash fusion point to descend, and cause the pickup slagging scorification phenomenon of water-cooling wall, influence the normal safe operation of boiler.Along with the further raising of environmental requirement, be difficult to realize NO on the other hand _xFurther emission control.The second class technology is a gas denitrifying technology, and countries use such as the present U.S., Japan, Europe technology the most widely are SCR technology (SCR).SCR technology denitration efficiency height, stable, but under the high grey deployment scenarios in the flue gas higher dust granules cause the problems such as wearing and tearing, obstruction of catalyst easily, the heavy metal in the flying dust can cause the poisoning of catalyst, operation and investment cost be costliness very.Environmental Protection in China work is started late, the control of sulfur dioxide just just begins, nitrogen oxide certainly will be brought into schedule from now on, if the thinking that adopts developed country to administer item by item, adopt the desulfurization of wet process of FGD WFGD device, the method of selectivity catalysis SCR denitration certainly will increase huge investment, operating cost, and some old units even have problems such as difficult arrangement, so developing low-cost, high efficiency while desulphurization denitration technology just seem particularly important.

Flue gas and desulfurizing and denitrifying technology in research has dry method while desulphurization denitration technology in the stove, electro-catalysis while desulphurization denitration technology etc. at present.Electro-catalysis desulphurization denitration technology removal efficiency height simultaneously wherein, operating cost is low, is becoming the focus of people's research.Present electro-catalysis technology comprises electron beam technology, pulsed discharge plasma technology, technology such as steam ammonia corona discharge activation.Mainly utilize the neutral molecule (N in high energy electron and the flue gas ₂, O ₂, H ₂O etc.) collision produces some living radicals (O, OH, O ₃, HO ₂Deng), the SO in these free radicals and the flue gas ₂And NO _xMolecular reaction generates SO ₃, high valence state nitrogen oxide, nitric acid, sulfuric acid etc. are at NH ₃Generate byproducts such as ammonium sulfate, ammonium nitrate under the condition that exists.Advantage is a dry removal, does not produce waste water and dregs, and energy is desulphurization denitration simultaneously, and accessory substance can recycling.But because the free radical time-to-live is very short, the generation and the smoke reaction device of free radical need be united two into one, discharge at whole flue, and contain a large amount of N in the boiler smoke ₂, CO ₂, H ₂Material such as O, dust, discharging condition is abominable, simultaneously N ₂, CO ₂Consume a large amount of input energy, cause capacity usage ratio low, overall operation expense costliness.

Summary of the invention

The objective of the invention is to discharge at whole flue at various electro-catalysis technology, the energy consumption problem of higher provides a kind of coal-burning boiler fume ozone oxidation and simultaneous desulfurization denitrification apparatus and method thereof.

The coal-burning boiler fume ozone oxidation and simultaneous desulfurization denitrification apparatus has boiler furnace, back-end ductwork, the alkali liquid washing tower that is connected successively, alkali liquid washing tower top is provided with demister, alkali liquid washing tower bottom is provided with reservoir, alkali liquid washing top of tower and chimney join, alkali liquid washing tower bottom and nitrate sulfate concentration and crystallization device join, back-end ductwork joins with ozone generating-device, dry filter oxygenerator successively, is provided with electrostatic precipitator on described back-end ductwork.

The coal-burning boiler fume ozone oxidation and simultaneous desulfurization method of denitration may further comprise the steps:

1) 110～150 ℃ of low-temperature zone spray into ozone O before or after the electrostatic precipitator (5) of boiler flue (4) ₃The nitrogen oxide molar ratio that sprays in ozone and the boiler smoke is 0.5～1.5, water-fast lower valency nitrogen oxide in the boiler smoke is oxidized into high valence state nitrogen oxide soluble in water, oxidizing sulfur dioxide generates sulfur trioxide, and the reaction time was at least 0.5 second;

2) will send into alkali liquid washing tower (7) through the rapid boiler smoke of handling of previous step, in the alkali liquid washing tower, flue gas be washed, absorb high valence state nitrogen oxide and oxysulfide in the flue gas simultaneously.

Described alkali lye is that NaOH, potassium hydroxide, calcium hydroxide, calcium oxide, calcium carbonate, ammoniacal liquor are wherein at least a.

The invention has the beneficial effects as follows: flue gas and desulfurizing and denitrifying new method provided by the invention, can reach denitration efficiency and 95% above desulfuration efficiency more than 80% simultaneously, cheap 30～60% through estimation output investment ratio tradition SCR+WFGD mode, operating cost saves about 60%

Description of drawings

Fig. 1 is a coal-burning boiler fume ozone oxidation and simultaneous desulfurization denitrification apparatus I structural representation;

Fig. 2 is a coal-burning boiler fume ozone oxidation and simultaneous desulfurization denitrification apparatus II structural representation;

Among the figure: boiler furnace 1, dry filter oxygenerator 2, ozone generating-device 3, back-end ductwork 4, electrostatic precipitator 5, reservoir 6, alkali liquid washing tower 7, demister 8, chimney 9, nitrate sulphate crystal treating apparatus 10.

The specific embodiment

The present invention is directed to local air or oxygen discharge produces and to spray into flue behind the ozone nitrogen oxide and oxysulfide are carried out oxidation, afterbody removes simultaneously in conjunction with the wet scrubbing device, if wet desulphurization device being installed then can carry out effective combination with it, realize desulphurization denitration simultaneously.

O ₃Extensively exist in electron beam, pulsed plasma discharge as a kind of of free radical, and O ₃Life cycle is longer relatively, therefore can with little air or oxygen at first ionization generate O ₃, send into boiler flue then, reduce the power consumption of system in just greatly, through estimation O ₃Only need discharge and just can meet the demands the gas of total exhaust gas volumn about 3%.

Below in conjunction with the drawings and specific embodiments the present invention is described in further detail.

As shown in the figure, the coal-burning boiler fume ozone oxidation and simultaneous desulfurization denitrification apparatus has boiler furnace 1, back-end ductwork 4, the alkali liquid washing tower 7 that is connected successively, alkali liquid washing tower top is provided with demister 8, alkali liquid washing tower bottom is provided with reservoir 6, alkali liquid washing top of tower and chimney 9 join, alkali liquid washing tower bottom and nitrate sulfate concentration and crystallization device 10 join, back-end ductwork 4 joins with ozone generating-device 3, dry filter oxygenerator 2 successively, is provided with electrostatic precipitator 5 on described back-end ductwork 4.

The coal-burning boiler fume ozone oxidation and simultaneous desulfurization method of denitration may further comprise the steps:

1) 110～150 ℃ of low-temperature zone spray into ozone O before or after the electrostatic precipitator 5 of boiler flue 4 ₃The nitrogen oxide molar ratio that sprays in ozone and the boiler smoke is 0.5～1.5, water-fast lower valency nitrogen oxide in the boiler smoke is oxidized into high valence state nitrogen oxide soluble in water, and oxidizing sulfur dioxide generates sulfur trioxide, and the reaction time was at least 0.5 second;

2) will send into alkali liquid washing tower 7 through the rapid boiler smoke of handling of previous step, in the alkali liquid washing tower, flue gas be washed, absorb high valence state nitrogen oxide and oxysulfide in the flue gas simultaneously.

The NO of boiler smoke discharging _xIn, NO accounts for more than 95%, and other is NO ₂, N ₂O etc., and NO is water insoluble, is one of gaseous contamination material that is difficult to handle, and the NO of high valence state ₂, NO ₃, N ₂O ₅Can generate HNO with the water reaction ₂, HNO ₃, very easily removed by the wet scrubbing device.By spraying into ozone, O in 110～150 ℃ of temperature ranges of boiler flue ₃/ NO molar ratio gets 0.5 ~ 1.5, NO can be oxidized to high valence state material soluble in water, removes part SO by the wet scrubbing tower ₂Also can oxidized generation SO ₃, wet scrubbing is to SO ₂Remove quite effective, SO ₃Compare SO ₂Easier dissolving and water cooperate the wet scrubbing device just can realize efficient while desulphurization denitration at the ozone oxidation afterbody, and denitration efficiency is with to spray into ozone amount relevant.If be equipped with limestone/gypsum wet process of FGD equipment, perhaps water dust scrubber then can carry out integrating the cost of reducing investment outlay with this method after the appropriate reconstruction to it.

Detailed process is: spray into ozone in 110～150 ℃ of temperature ranges of boiler back end ductwork, spraying into the position can be before or after electrostatic precipitator, and the ozone straying quatity is pressed O according to NO concentration in the flue gas ₃/ NO mol ratio 0.5～1.5: 1 is chosen, and nitrogen oxide after the oxidation and oxysulfide remove by the wet scrubbing tower, and absorption liquid is an alkali lye, and absorption liquid is recycling, sells behind the sulfate nitrate condensing crystallizing of enrichment or further handles.Further specify below in conjunction with accompanying drawing:

Embodiment 1

Coal-burning boiler fume ozone oxidation and simultaneous desulfurization denitration arrangement I, as shown in Figure 1.The air drying is sent into the dry filter oxygenerator after purifying, the oxygen that produces is sent into ozone generating-device with the preparation high-concentrated ozone, the preceding temperature of electrostatic precipitator was about 150 ℃ dust-laden flue after ozone was sent into air preheater, straying quatity is according to flue gas nitrogen oxide concentration, press ozone and nitrogen oxide mol ratio and constantly adjust at 1.1: 1, guarantee the 0.5s reaction time at least.Spout adopts perforated grill to spray, and sprays into the position at air preheater exhanst gas outlet 1m place.Flue gas after the processing enters the wet scrubbing tower after electrostatic precipitator, absorption liquid is recycling, and flue gas is sent into chimney through wet scrubbing tower, demister after handling, and the sulfate of absorption and nitrate carry out condensing crystallizing to be handled.Scrubbing tower adopts alkali lye as absorbent, and scrubbing tower is spray column or packed tower.Alkali lye as absorbent is NaOH, also can be in water, potassium hydroxide, calcium hydroxide, calcium oxide, calcium carbonate or the ammoniacal liquor one or more.

Embodiment 2

Scheme II is put in the coal-burning boiler fume ozone oxidation and simultaneous desulfurization denitration, as shown in Figure 2.Ozone is sent into electrostatic precipitator about about 110 ℃ low cloud of dust compression ring border afterwards, and the ozone straying quatity is pressed ozone and nitrogen oxide mol ratio 1.0 and is dynamically adjusted according to flue gas nitrogen oxide concentration, sprays into a position and guarantees apart from the scrubbing tower inlet above time of staying of 0.5s.Ozone adopts perforated grill shape spray regime to carry out, and the flue gas after the oxidation enters the alkali liquid washing tower and absorbs, and absorption liquid is recycling, and flue gas is sent into smoke stack emission after washing, demist, and the sulfate of absorption and nitrate carry out condensing crystallizing to be handled.Scrubbing tower adopts alkali lye as absorbent, and scrubbing tower is spray column or packed tower.Alkali lye as absorbent is NaOH, also can potassium hydroxide, in calcium hydroxide, calcium oxide, calcium carbonate or the ammoniacal liquor one or more.

At last, it is also to be noted that what more than enumerate only is specific embodiments of the invention.Obviously, the invention is not restricted to above embodiment, many distortion can also be arranged.

The present invention can summarize with other the concrete form without prejudice to spirit of the present invention and principal character.Therefore, no matter from which point, above-mentioned embodiment of the present invention all can only be thought can not limit the present invention to explanation of the present invention, claims have been pointed out scope of the present invention, and scope of the present invention is not pointed out in above-mentioned explanation, therefore, in implication suitable and any change in the scope, all should think to be included in the scope of claims with claims of the present invention.

Claims (3)

1. coal-burning boiler fume ozone oxidation and simultaneous desulfurization denitrification apparatus, it is characterized in that, it has the boiler furnace (1) that is connected successively, back-end ductwork (4), alkali liquid washing tower (7), alkali liquid washing tower top is provided with demister (8), alkali liquid washing tower bottom is provided with reservoir (6), alkali liquid washing top of tower and chimney (9) join, alkali liquid washing tower bottom and nitrate sulfate concentration and crystallization device (10) join, back-end ductwork (4) successively with ozone generating-device (3), dry filter oxygenerator (2) joins, and is provided with electrostatic precipitator (5) on described back-end ductwork (4).

2. the coal-burning boiler fume ozone oxidation and simultaneous desulfurization method of denitration that use is installed according to claim 1 is characterized in that, may further comprise the steps:

1) 110～150 ℃ of low-temperature zone spray into ozone O before or after the electrostatic precipitator (5) of boiler flue (4) ₃The nitrogen oxide molar ratio that sprays in ozone and the boiler smoke is 0.5～1.5, water-fast lower valency nitrogen oxide in the boiler smoke is oxidized into high valence state nitrogen oxide soluble in water, and oxidizing sulfur dioxide generates sulfur trioxide, and the reaction time was at least 0.5 second;

2) will send into alkali liquid washing tower (7) through the rapid boiler smoke of handling of previous step, in the alkali liquid washing tower, flue gas be washed, absorb high valence state nitrogen oxide and oxysulfide in the flue gas simultaneously.

3, a kind of boiler smoke ozone oxidation and simultaneous desulfurization method of denitration according to claim 2 is characterized in that described alkali lye is one or more in NaOH, potassium hydroxide, calcium hydroxide, calcium oxide, calcium carbonate, the ammoniacal liquor.