JPS6071028A - Removal of so2 and nox in exhaust gas - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to reducing SO2 and/or nitrogen oxide NO in exhaust gas.
and a method for reducing the amount of SOl (here represented by -ship rNOxJ).

A method has been proposed for removing NOx from exhaust gas by mixing NHs with exhaust gas and exposing the mixture to ultraviolet light.

According to this method, N](3 is photodecomposed as shown in the formula below to generate an amino group.

N (] 3 → N Hi + 11 (1) ° The amino group as shown in the formula below reacts with NOx, which is an inert gas that is widely accepted to be inert and harmless in the atmosphere, nitrogen, water. and generates NtO.

61NHi 10No -+Nt 4-1-120 (2)N
11 s 10N 02→N'20+802 (a) It is now known that the most efficient practical application of ultraviolet light is obtained when ultraviolet light with a wavelength within a specific range is used. Furthermore, one object of the present invention is to provide a method for reducing the emission of NO and NOz in I gases which often contain l-120, in which the exhaust gas is mixed with N Hs and the wavelength ranges from about 190 to about 220 r+n+. irradiating the mixture with ultraviolet radiation containing a small amount of constituents in the range 190 nm, said radiation containing substantially no constituents with wavelengths below 190 nm, and furthermore, said method does not require a solid catalyst. This method is characterized in that:

It will be appreciated that efficiency when using vote rays is important from an economic perspective. Of course, this method is usually applied to flowing gases and requires long exposures to the radiation 11 with low efficiency of irradiation. this is,
This requires ultraviolet lamps to be placed over very long distances and to illuminate a large portion of the pipe carrying the exhaust gases.

This not only increases the operating cost of providing the energy necessary to power the UV lamp, but also significantly increases the capital cost of installing the UV ring emitter.

When using wavelengths in the range of about 190 to about 220 nm,
The NOx removal reactions that occur mainly are the reactions (1), (2), and (3) above, and as a result, Nz O,t-1t
01N1 is formed in the waste gas stream. These products are considered safe to release into the atmosphere. Approximately 190n
Undesirable side reactions can be avoided by using radiation that does not contain sub-m components. For radiation below 190 nm, a significant amount of 01-11 is formed due to photolysis of the water vapor naturally present in the exhaust gas stream. Usually, due to the high concentration of water vapor, the predominant reaction is H20→O]~I +l-1(4). OH groups react with N O2 to produce acidic substances.

Oto1 + N Ot → HN O! (5) Normal,
It is desirable to remove these acidic substances in the presence of moisture, ie, steam, using an alkaline reaction medium, ie, by reacting with excess ammonia gas to form the nitrate salt N84NOs.

Since nitric acid jn may form a particulate second phase,
It is usually desirable to remove particulate salt with a gas stream before passing it to the atmosphere. In this case, particulate salt is obtained as a by-product. The particulate salt may be recovered and have value as a fertilizer, for example.

However, NH4NOx is an explosive and difficult to handle. Release*! If Ii is almost completely free of components below 190 nl, the formation of explosive N Ht N Os precipitates can be significantly reduced or completely avoided.

The wavelength of the unexpected radiation used in the ultraviolet irradiation stage is approximately 19
When from 0 to about 220rv, the N H3 in the mixture
NOx has a satisfactory f! i! removed. The absorption rate of Nt(s radiation drops off sharply at wavelengths above about 2201'lll1, and the efficiency of this method is compromised since only a small concentration of amino groups occurs. Therefore, when the wavelength of the 111 m radiation is much greater than 220 nIn, the amount of ammonia used and the intensity of the radiation required become too rapid to achieve NOx removal in a reasonable amount of time. It becomes thick.

The absorption of radiation by N Hs reaches a peak at about 195 mm, and as shown in Table 1, it falls off as the wavelength decreases to about 170 nm and below. At the same time, as shown in Table 1, the radiation is naturally quite strongly absorbed by the normally present O2 and H2O.

Table 1 Extinction coefficient 1 mol-"C+Il-") 10- The extinction coefficient ε is determined by 1- Io16-Ed-, in which IO- of the light incident on the chamber containing the photodegradable substance. Intensity r - Intensity of light passed through the chamber C - Concentration of photodegradable substance (mol dm''□8) L -
Cl) represents the extinction coefficient (1 mol-ICl11-1').

Therefore, the extinction coefficient indicates the degree of absorption of radiation by a photodegradable substance, and the higher the coefficient, the more lean the absorption.

The extinction coefficient of water vapor is zero below 190 nm.
Since no OH group is substantially formed, reaction formula <5) is
It doesn't happen enough to be a problem.

In the range from 170 to 220 nm, 02 and t
Although the coefficients of 120 are substantially lower than those of Nl-13, as can be seen in the table above, these coefficients increase rapidly towards the lower end of this range, and furthermore the coefficients of 020 in the reaction mixture The concentration of IzO and IzO is considerably lower than that of NHs. In the method according to the invention, the m degree of N Hs in the mixture to be photolyzed is from about 5x10 to about 5x1
It is desirable that it is 0-3 mol/1. If the S ratio of NH3 is less than 5 x 10-"-E/1, the efficiency of NOx removal tends to be impaired, and long-term exposure to ultraviolet radiation Q. It is inconveniently necessary to remove to the extent that approximately 5X10-
NHsmm of more than 8 mol/1 is unnecessary, and maintaining a high NHs of 11 degrees in the photolysis reaction region is
! -13, thus increasing the operating costs of the method, as well as a significant amount of unconsumed N H3.
This is not desirable as it may lead to the release of water into the atmosphere. Furthermore, the NHs concentration is about 1X10=about 1X10-a
Mol/J! It is preferable that it is within the range of , and furthermore,
Preferably, it is within the range of about 1.times.10@-5 to about 2.times.IO@-5 moles/L.

Due to incomplete consumption of 02 in the combustion air, 0 in the exhaust gas
2 (molar) amount is typically about 100 times the N1]3 molar concentration desired to be maintained in the reaction mixture, and during the I'20 vapor produced as a result of combustion, the
It is approximately 200 times the H3 molar concentration. Therefore 190n
At wavelengths well below m, the concentrations of 0□ and HzO are significantly higher than the lImaro of NHs and 02o. Lbi H20
The extinction coefficient of increases rapidly. On the other hand, the extinction coefficient of NHs rapidly decreases and reverses at about 190rv1 meter, so 0□
The absorption of H20 and H20 competes significantly with that of NHs, thus severely limiting the formation of NHzM below 190 nm.

As a result, when the ultraviolet radiation includes components having wavelengths of about 190 nm or less, the efficiency of radiant energy utilization is considerably reduced because a large portion of the radiant energy is directed to the production of unnecessary substances.

In this reaction, NHz! ! binding occurs, producing toxic hydramine.

N1-h+N1-1. → N 2 14 Of course, it is preferable to maintain the concentration of hydramine in the reaction mixture and keep the concentration in the photolytic region as low as possible. Otherwise, more hydramine will be absorbed than in the reaction mixture. special measures must be taken to

Hydramine is a strong absorber of radiation at wavelengths within the range of about 180 to about 270 r+m and dissociates to reform amino groups.

Nt H4+ hν→2NH2 1 component with a wavelength in the range of 190 to 22Onlll
By using an ultraviolet light source containing one or more hydrazine, the content of hydrazine in the reaction mixture can be kept to an acceptable level, since the hydrazine is reconverted to free radicals.

Another object of the invention is to provide at least about 1×10 −B mol/
In the method of reacting exhaust gas containing 100% S2Oz to convert the S20z to an oxidized acidic substance without a solid catalyst, the gas also contains Okawa H1O vapor and 02O2. characterized by at least about 190
A method is provided which consists of irradiating a gas with ultraviolet radiation containing components of sub-nm wavelength.

14- The radiation preferably includes a component in the range of about 170 to 1901 m. 2, photolysis of water vapor by radiation below 190nl11, more preferably in the range of 170 to 190nn+, results in the efficient formation of a large amount of OH groups through reaction equation (5).

Hydrogen groups react with SO2 to produce oxidized acidic substances.

01-l + S O2→HS O3 (6) These acidic substances can be absorbed in the presence of moisture, or can be reacted with ammonia gas by alkaline reaction #A to form sulfates. Alternatively, absorb by traditional means such as a souffler. Alternatively, it can be used as a feed material in the sulfuric acid production process and removed.

Exhaust gases that are often treated contain both NOx and SO2. In such cases, as explained above ()
Before undergoing the SO2 oxidation reaction, first of all, NO
It is preferable to undergo an x removal step. by this,
In the SOz oxidation reaction, the desirable l-I N O
3. Can prevent the formation of acidic substances. According to the second object of the invention, the present invention provides a method for reducing the content of NOx and SO2 in exhaust gas containing a large amount of H20 water vapor and 01, in which the exhaust gas is converted into NHs
and irradiating the mixture with ultraviolet radiation tJJ radiation containing at least one component with a wavelength in the range of about 190 to about 220 nm, said radiation having a wavelength of about 190 nm to about 220 nm.
It contains almost no constituents with wavelengths below 0 nm, thereby obtaining a gas with a reduced content of NOX, and furthermore,
Ultraviolet radiation that contains gas with reduced Ox content and at least one component with a wavelength below 190 nm! The present invention provides a method for converting SOx into an oxidized acidic substance by irradiating with X-11 radiation and without using a solid catalyst.

The advantage of this method is that since the NOX removal reaction is carried out without a solid catalyst, there is no need to remove catalyst residue SOt and other sulfur compounds from the exhaust gas before carrying out the reaction.

The type of UV lamp used is determined by the claimed wavelength range. In one type of case above,
One type of lamp suitable for use is a low pressure mercury arc lamp, where the lamp preferably includes at least one constituent fortification in the range of about 170 to about 190 nm.

Kowara, along with the strong late OA line at 184.5 nm,
It also has strong radiation at 3.7 nm and an emission line that is weaker than other wavelengths. These lamps can therefore be used in the S02 oxidation method described above. Other filffi lamps that can be used consist of high pressure mercury xenon lamps. These have a continuous spectrum output from 190 nm to over 30 OnIn. Although it also emits wavelengths below 190 nm, it can be filtered out into the cylinder with a suitable filter. Therefore, these lamps have 2
These outputs cannot be used efficiently because they include radiation with wavelengths of 20 r + m or more, but from 19'0 to 2
By irradiation of 20 nm of N)-13 containing reaction mixture,
It is particularly useful for photolytic removal of NOx from exhaust gas streams.

It should be noted that the low pressure mercury arc lamp and high pressure mercury xenon lamp described above are commercially available and can be easily obtained. One advantage of the method according to the invention is that it can be carried out using commercially available UV lamps.

An embodiment of the method according to the invention is illustrated by the attached figures.

In the figures, the same reference numerals indicate the same parts. FIG. 1 represents a combustion device, namely a boiler 1, to which combustion air is supplied from an inlet pipe 2 through a preheater 3. Heated air is supplied from the preheater 3 to the boiler via a pipe 4. Exhaust gas from the boiler is sent directly to the preheater 3 through a transport pipe 6.

Boiler 1 may generally be any type of combustion device;
Atmospheric air is used to sustain the combustion, the fuel contains sulfur and produces SOt in the exhaust gas, and/or the fuel is burned at a sufficiently high temperature that large amounts of NOx are formed. At high temperatures, especially when solid fuels are used, the nitrogen present in the combustion air combines within the fuel itself and reacts with the oxygen present in the combustion air to form NO.

18- Nt+Oz→2NO Oxidation of No to NO2 also occurs, so the NO-containing exhaust gas is mixed with some Not.

2 N O-1-02' 2 N O2 Therefore, the fuel is
For example hydrogen gas, or primarily carbon or hydrocarbon fuels. These are the so-called excavated fuels, ie oil, coal and natural gas, or oil gas and coal gas obtained from excavated fuels.

Ammonia gas is injected into the transport pipe 7, which is connected to the preheater 3
The cooled exhaust gas is transported to a conventional device, in this embodiment an electrostatic precipitator 8, for separating particulate matter, i.e., fly dust.

This ammonia is injected through the introduction pipe 9, but
The valve 10 allows and controls the introduction of ammonia at a metered rate. Often the exhaust gas is Kamaishi's SO
i and l (contains OA. These react with NH3 to form particulate ammonia salts, namely NH4H80a and NH4
CJ! , generates. If ammonia is added downstream of the other combustion devices in boiler 1, there is no risk of ammonium bisulfate or ammonium chloride condensing on critical components such as boiler 1 or preheater 2, causing corrosion or fouling.

As noted, ammonia may be added upstream of the precipitator 8 to remove bisulfuric acid to prevent excess turbidity in the gas stream and loss of efficiency in the subsequent photolysis step. The rate of ammonia addition may be determined to be sufficient to react with the SOs and HCJ, and still leave the necessary ammonia in the concentrator during the photolysis step. That is, it is generally 5x10-6 to 5x10-a mole/
1 in the above range. Or, more preferably, N
It is preferable that the rate at which Hs is added be automatically adjusted in response to a sensor provided in the chimney 13 of the transport pipe 7. The former sensor reacts to SOx and/or NOx, and when the concentration of S02 and/or NOx increases, N
The latter sensor responds to the presence of NHs by increasing the rate of addition of 113
Once the FIi degree of Hs exceeds a predetermined limit, the rate of addition is reduced.

The ammonium bisulfate and chloride mixture collected in the dust collector is separated from the fly assico and recovered. Depending on the chemical composition of the exhaust gases, if the recovered mixture does not contain excessive amounts of heavy metals and other toxic substances, these can be used as valuable by-products.

As indicated above, the addition of ammonia is preferably carried out at a point upstream of the normally provided ventilation fan 11, which directs the purified gas from the dust collector @ 8 into the transport pipe 12. The exhaust gas is sent along the chimney 13 from where it is discharged into the atmosphere. Passage of the mixture of exhaust gas and NHs through fan 11 ensures uniform mixing of N]'3 into the gas stream. It is one of the advantages of the method according to the invention that the introduction and photolysis of ammonia takes place in the area of the exhaust gas transport tube adjacent to the electrostatic precipitator.

In the area of This is because it is not necessary and can be carried out at low temperatures.

Since these areas of the exhaust gas transport pipes are usually easily accessible, the installation of tedious inlet pipes, lamps, etc. in implementing the method can be readily done with existing combustion stages. Can be implemented.

The lamp 14 is provided adjacent to the transport pipe 12 and
Irradiate the gas stream flowing through 2. As shown in FIG. 2, the lamp may have a lamp body 16 covered with a metallic reflective surface 17 and separated from the interior of the transport tube by an ultraviolet-transmissive window 18, ie, a quartz crystal. Furthermore, the space between the reflective surface 11 and the window 18 constitutes a seal filled with an ultraviolet inert gas, i.e. nitrogen, to prevent ozone from being induced in the atmosphere adjacent to the lamp, or to absorb it by reducing it. It is preferable to take measures to prevent losses due to Since the exhaust gas normally contains a significant amount of particulate matter even after passing through the dust collector, which may contaminate the lamp structure, it is preferable to mount the lamp outside the transport pipe 12 as shown. . It is usually best to provide the window 18 with an automatic cleaning device 22 (not shown) to remove any dirt that may accumulate on the window surface in contact with the interior of the transport pipe 12.

Successive NOX and SO2 removal steps, i.e. first of all, the N H3-containing coalescence is illuminated at 190 to 220 nm.
, 1'4 to remove NOx and then irradiate the photolytic reaction mixture at 170 to 190 nm to oxidize the SOz to acidic substances, the lamps 14 each have a wavelength of the required wavelength. It may have two spaced apart ultraviolet sources that generate radiation of 1311 m.

2, the efficiency of NOx and/or SOz removal is highly dependent on the wavelength of the '1g external itt radiation used. However, the efficiency of T culmination when operated in a particular range of wavelengths, which means the degree of removal of undesirable materials, is relatively related to the 15 degrees of other materials in the reaction mixture. It is convenient to measure the NOx removal efficiency of a 1-aT culm by measuring the percentage of NOx removed. Thus, for example, when a reaction mixture consisting of a particular exhaust gas composition and Nl-13 is irradiated with ultraviolet light at a wavelength of 193 nm, the rate of reduction in NO contained will be lower than when the irradiation is performed at a wavelength of 213.9 am. This is approximately 2.5 times the rate obtained when This rate (given a certain minimum concentration of N Hs) will depend on changes in the initial N01S02, or N1]3 concentration, and on changes in the concentrations of other substances normally present in the reaction mixture, which are normally present in the exhaust gas. amounts of HλO vapor (at least 1×10 −4 mol/1) are relatively unaffected.

The NOx and/or SOz removal rate also depends on the ml of radiant energy to which the reaction mixture is exposed. Thus, for example, if a mol/1 and exhaust gas mixture is irradiated with UV radiation in the preferred wavelength range of 190 to 220 nm, the mixture is continuously exposed to 1018
irradiate with an intensity of photons/ci/s or continuously 10
At an intensity of 1017 photons/cd/sec for 0 milliseconds and an intensity of 11 degrees, approximately 80% of NOx is removed. These intensities are typical of those obtained with suitable types of UV lamps. For example, the flow velocity of exhaust gas through a viscous cross-transport pipe installed in a conventional coal-fired power plant is approximately 10 m7 seconds, so the length of the transport pipe to be irradiated is approximately the same as that of a high-intensity lamp. Approximately 20 cm is required when a lamp is used, and 2 m is required when a low-power lamp is used. The required NOx removal rate in any case will, of course, depend on the initial concentration of NOx present in the exhaust gas and the required concentration of NOx in the furnace gas discharged to the atmosphere. , a removal rate of at least about 80% of NOxal+ is usually observed. Therefore, during photolysis, the reaction mixture in the irradiated area of the exhaust gas transport tube is generally
Preferably, the irradiation is performed at intervals in the range of 8 photons/ci.

The removal rate of SO2 in the absence of NOx is S
Ox-containing gas was heated at 175 nm for 10 μIJ seconds, 3×
When irradiated with an intensity of 10I8 photons/Ca/sec, about 72% of 802 is removed.

The embodiment shown in FIG. 1 is particularly suitable for use in either of the following cases. The first requires an FJ clause for NOx emission only, the irradiation is performed at 190 to 220 nm, and the gaseous photolysis products Nz, NzO are emitted from the chimney 13, the second requires SOz only, or 802 and NO
Both radiations of x are adjusted and the irradiation is from 170 to 190n
m, and the particulate photolysis 25- products, namely (NH4)2804 and Nt-14NO3
This is a case where it is permissible to emit into the air.

In Figure 1a, firstly bringing about the reaction of NOx with NHzl produced by photolysis and secondly leading to the oxidation of SO and H8O3 substances by irradiation with ultraviolet radiation with a wavelength in the range of 170 to 190 nm. After irradiation with the binary lamp arrangement 14, the 1-ISOs material becomes nearly neutral and reacts with excess ammonia in the presence of moisture to form particulate (Nlli)zSO4. The reaction mixture is transferred to the solid matter separator shown in Fig. 2, i.e., the second electrostatic precipitator 1.
9, where particulate products are removed. Depending on the chemical composition of the exhaust gas, and especially if the exhaust gas does not contain toxic metal substances, the separated sulfates can be used, for example, as agricultural fertilizer. Instead of supplying too much ammonia to the exhaust gas before the irradiation step, add the ammonia necessary to neutralize the acidic substances! It is usually more efficient to provide a controlled release of unreacted ammonia into the air by means of a hinge in an auxiliary fan, as shown at 111121.

In Figure 3, NOX or NOx and SO2
Preferred equipment for the removal of is shown. Here, ammonia is added through a pipe 9 after the exhaust gas passes through a dust collector 8. In the case of high temperature, the exhaust gas from boiler 7 contains 11 OA and SOs, which react with NHs to form particulate ammonia salts.

Adding ammonia after passing through the dust collector @8 prevents these soluble salts from being dissolved from the dust collector #8 together with the fly associator. In many cases, it is preferable to recover a fly assico that is relatively free of soluble materials. This is because soluble substances tend to be released when in contact with water, causing problems for some weighing purposes, such as landfill, and making fly assicos unsuitable. In some cases, it is preferable to remove particulate ammonia salts produced by adding ammonia before the exhaust gas is exposed to the ultraviolet light source.

Even if the lamp 14 is a -gen type NOx removal type, it
A dual armament for the continuous removal of x and S Ot may be used, and a device for removing the bamboo-resistant A5 particulates may be provided between the lamp 14 and the chimney 13, for example a conventional flapper.

The optimum conditions necessary for the photolysis reaction for aerobic gases of any composition, in particular the exposure time to ultraviolet radiation, i.e. the length of the transport tube irradiated by any ultraviolet radiation, and the light when using a monochromatic radiation source. Optimal investigation can be performed by performing Combicota Shikomi 1-nosion of the decomposition reaction. Such combicoter sicomilation requires the provision of a set of parametric variables that are input to the computer program. Parameters are the initial concentration of all reactive chemicals present in the exhaust gas and the extinction coefficient applicable to the wavelength at which the investigation of photolytic reactions of all photodegradable substances present in the gas mixture is carried out. Consisting of For the avoidance of doubt, the extinction coefficients are expressed in Table 2 for certain wavelengths. Other extinction coefficients applicable to different wavelengths can be obtained from general texts.

Table 2 NHs→−hν→NHt +I−(10001500
100S () a +h sea 480 ten ('P) 17
5 1000 1501-1. Q+hν→0H1-H1
4000s 10hν→Oz -1-Q ('D) 1!
i6 100 15002+h sea+20 ('P)
4,2 0,3 0.002No2-+-hNo+
O(3P) 68 68 100NzO+hν→N2+
Q ('D) 36 35 < IN2 11 4 -
Toh C12NN 2 850 1000 600
Further variables include the intensity of the irradiation and the trace coefficients of the important chemical reactions that occur during the photolysis reaction. As a result of extensive chemical research on reactions, 52 chemical reactions in particular! I was able to list the important points. These are listed in Table 3 along with their respective quick reaction coefficients.

29- Table 3 1, NH2+0=NHz 2, NL +NO2=N2 0+Ht O1,3X10
'mouth 3, NHz +NHh =N2 HL 1.5X
10”4, NHh + (h = NO + Hz O1゜2x
10”5, NHz +RH=NHs +R5,0X1
0'6, NHh +0=NHz 1.0X10”7,
NHz +Na =NHs +)l 8.7x10'
8, N14 +o=HI'Jo+HORHO+NH2,
1x1099, NHz +0H=HNO+Hh OR
NH+hb O6,0X10'10, NH2+tlO
a = NHO + HIO2, 0x10B11, NHs
+0=NHz +14 3,0xlO”12,NHs
10H=NHt +820 1,0X10B13, N
Hs +0=NHz +ot-+ 4.0xlO514
,0+N01=02 +NO5,6X10'15,0+
Oz = Os 8.7xlCP16, 0+N0=NO2
""0L1 17, NO+O* =NO1+(h 1.0XIO'
18,0 ('D) +H20=2011 1.3X
10"19, O('D)(+M)=O(' P)(+
M) 8.2x10"s-'20 at 1 atm, l-l+
ot = lot 8.0X10”21, HOz +
0=NHz +HO5,0X10922,0+5O=S
Oz 5.0X10'23, C)a +5O=SOz
+O(s p> 5.0x10424, 0s +5O
=802+Ot 4.5x10725, SO+5O=
SCh +S OR (So) 2 2.0X1 (F26
, OH+OH=th O10 (s p> 1.lX1
0'30- Table 3 (continued) 28.0+03-202 5.7X 629.0f-l
+C0=cO2+l-19,0x10'30,SO+N
Ot = SO2 + NO8, 5X10"31, t-l-1
-i-10t =l-h -tO□ 8,4x109-
201-1 1.9x109 -F+2 0+0 5.7x10" 32, 0+0H-Oz +l-12,3xlO"33,
Ol'+HO2=)h O+02 2. lX10”34
, H(h +l-10z =Ht O2+Q□ 1.4
x10935, Os 10=HOz +02 4.
9X10736, Os +HCh =OH=Ch i
, 2X10'37, OH 1 Sot = 1-1303 6
．． 6x10”38, H+Os =OH+02 1.7
X10"39, 0-1-Ht 0=Ot-11-021
,9x10'1140, O+0=Ot 6.9xlO
'41.0 issue-I=I-102, 9x10"42.14
+0-OH+H4,0XIO'43,S01+0=S
O31・1x10'44, 0+C0=CCh 3.0x
10445, N2 f−h +t−1=Nz 1−I
3+1-12 1. lXl0'46,01-(+H=l
h O7, 2x1o947, Of-ill-12=L1
2o+H3, 9x10648, SCh +HOz =S
Os +OH5, 4x10549, O+N0=N-)-
(h 7.7X10'50, NO+H=l-INO8
,3x101151, NOz +1-(=NO-+-
Of-17,5x1011152, @@ group → final termination reaction 7,5X10-2 Note 1 = Many of these reactions were tertiary reactions under atmospheric pressure. Rate coefficients for pseudo-second-order reactions are listed, which were obtained using 1 atm instead of tertiary reactants.

Note 2 - In reality, the final termination reaction was only applied to NH21fj to give modest results.

The specific speed coefficients and extinction coefficients pointed out in Tables 2 and 3 are uncertain because there are contradictory records in the literature. These are mainly the extinction coefficients of NHs, Oz, HzO and Sow, and the rate coefficients of the reactions numbered 1 and 2 in Table 3. However, the effects of these uncertainties can be checked in the cylinder by changing the input parameters of the computer program and are found to have a very small or negligible effect on the residual rate of NO removal.

As is obvious to those skilled in the art, 52 in Table 3
15 rate formulas expressed in the reaction of NHZ,
NHs, 01No, O('D), To1, HOz
,Ox,Os,SO,OH,SOx,Nz1
A rate equation consisting of one each of
tem). These equations can be converted using conventional methods, e.g.
integration of ordinary d
Hfere-nential equations ”G
ear C, W,,Comn+un A CM, 14
．． 17 (p. 3 (1971)).Using units of microchromoles and microseconds rather than moles and seconds shortens the calculation interval n and is more stable. It should be noted that this yields numerical concentrations and speeds such that errors in approximation are less important than when using conventional units.

It will be understood that the solution obtained by this method allows *i to be produced immediately at any time during the photolysis reaction of any substance.

As mentioned above, this analysis is based on hydrogen gas, fossil fuels, 33
- Exhaust gases obtained from conventional combustion methods involving the combustion of various fuels, including those derived from fossil fuels, at high temperatures in air, containing natural SO and/or NOx, typically 1xio- s to 1X10-4 mol/! So
l, and typically 1000 to 2000 ppm S
ot, I X10-' to 1 x 10''5 mol/12
of N O2, I x 10-8 to 1xio-' mol/
N of L.

Applicable to all exhaust gases containing

The concentrations of substances normally present in such fuel gases are shown in Table 4.

Table 4 LUL Concentration range Mol/1 S03 0 to 1xio-'1 SOx O to lX1O-4 N Ot O to 1xlO-5 N10 0 to lX1O-7 No O to 1X10-' 1-I Cj! O to 1X10-'OH1xlO-' Kara1 xlO-" -34~ Table 4 (continued) Substance Concentration range Mol/1 Hz O1X 10-' to 1x10-202 1
10-' to 1xlo(R]-1 (hydrocarbon) 0 to 1xio-6Co 1xlO-' to 1x1O-FI
CO21x10-' to 1x10-2 Other (mainly nitrogen) As an example only, standard exhaust gas compositions obtained from coal-fired power plants are shown in Table 5.

Table 5 -1-Working [o2 A] 3+(1/2) to 9% in main volume (full load to partial load) 10% in HzO volume N O300 to 7QQppm (Vl) SO211
00-1600ppm (VOj!) Table 5 (continued) Substance 11 degrees I-I CA 1100pp (voA) 80s 1
0~16ppm (vow)N O230~701)p
m (VOA)

[Brief explanation of the drawing]

Figure 1 shows the combustion equipment N, that is, the boiler, and the NOx and/or SO generated from the exhaust gas to the boiler.
Schematic diagram of related equipment for removing t, Figure 1a is the first
Another embodiment of the apparatus shown in the figure is shown, FIG. 2 is a perspective view showing a longitudinal section of a part of the wall of the exhaust gas transport pipe of the apparatus shown in the figure, and FIG. 3 is another embodiment of the apparatus shown in FIG. FIG. FIG.3

Claims (1)

[Claims] 1. N in exhaust gas that also contains large amounts of l-120 steam. and in a method of reducing the content of NOx, the exhaust gas is mixed with NH3 and the mixture is irradiated with ultraviolet radiation containing at least one of the components in the wavelength range from about 190 to about 220 nm. The radiation contains almost no components with a wavelength of 190 nm or less,
A method further characterized in that said method is carried out without a solid catalyst. 2. The method according to claim 1, wherein the number 011 is produced from high pressure mercury xenon. 3. The method according to claim 1, characterized in that the gaseous mixture after irradiation is sent directly to the atmosphere. 4. A method as claimed in claim 1, characterized in that the gaseous mixture receives a total of 1017 to 1018 photons/cd of radiant energy flux in the wavelength range in the irradiated region. 5. The mixture is about 5 x 10-8 to about 5 x 1o
The method according to claim 1, characterized in that it contains -a mole/1 of NHs. 6. The content of NHs is about 1X10-5 to about 1X
The method according to claim 5, characterized in that the amount is 10-8 mol/L. 7. The content is about 1X10-' to about 2X10
'Mole/! Claim 6 is characterized in that
The method described in section. 8. The method of claim 1, wherein the NHs is added to the exhaust gas when the temperature of the exhaust gas is within about 400°C. 9. The method of claim 8, wherein the temperature is about 150<0>C to about 250<0>C. 10. The method according to claim 1, characterized in that the mixture containing NHs is sent to the irradiated position by a fan. 11. The method of claim 1, wherein the gas contains about 1.times.10-" moles/1 of 802. 12. The gas contains from about 1.times.10-" to about 1.times.10-4 moles/l.
12. A method according to claim 11, characterized in that it contains 1 SOz. 13. Gas is 802 from about 1000 to about 2oooppm
12. The method according to claim 11, characterized in that the method comprises: 14. A method for converting the SO of an exhaust gas containing at least about 1 x 10-'' mol/i of SO to an oxidized acidic material without a solid catalyst, wherein the gas is and comprising irradiating the gas with at least one component having a wavelength of about 190 nm or less with ultraviolet radiation. 15. The method of claim 14, wherein the radiation comprises a component ranging from about 170 to about 1100 nm. 16. The SO2 content in the exhaust gas is approximately 1×10″6
15. A method according to claim 14, characterized in that from about lx10-j mol/, I2. 17. The radiation is a strong radiation of 184.9 nm,
15. A method according to claim 14, characterized in that it is obtained from a low-pressure mercury arc lamp providing a wavelength of 253.7 nm and 253.7 nm. 18. The gaseous mixture has a total flux of radiant energy in the wavelength range of about 5×1017 to about 5×
Special i characterized by receiving 1018 photons/ctl
i! I. The method according to claim 14. 19. The method of claim 14, which comprises contacting the irradiated mixture with an alnochemical reaction medium or water to absorb the acidic substance. 20. Claim 1 comprising contacting the irradiated mixture with gaseous ammonia to absorb acidic substances.
The method described in Section 4. 21, the exhaust gas is from 1xio-' to 1X10-2
mol/night HzO vapor and 1x10-6 to lx10
15. The method according to claims 1 to 14, characterized in that the content of 02 is -2 mol/1. 22. The method according to claims 1 to 14, characterized in that the exhaust gas does not contain hydrocarbons of 1 x 10 -8 mol/1 or more. 23.820 Steam and a method for reducing the content of NOX and SO in an exhaust gas containing frequently 02, in which the exhaust gas is mixed with NHs and the mixture is
irradiation with ultraviolet radiation containing at least one component with a wavelength ranging from 0 to about 220 rv to obtain a NOxOx-containing gas, said radiation having a wavelength of about 19
irradiating a gas with substantially no constituents at wavelengths below 0 nm and a reduced NOx content with ultraviolet radiation containing constituents at wavelengths below about 190 nm to convert S Oz into oxidized acidic substances; A method characterized in that step (1) is carried out without a solid catalyst. 24. The method of claim 23, wherein the second irradiation is performed with radiation comprising a component in the range of about 170 to about 190 nlll. 25. The method of claim 23, further comprising contacting the irradiated mixture containing the oxidized acidic material with an alkaline reaction medium to absorb the acidic material. 26. The method of claim 23, comprising contacting the irradiated mixture containing the oxidized M material with gaseous ammonia to absorb the acidic material.