Installation for flue gas treatment

 

(57) Abstract:

The invention can be used in the treatment of flue gases from nitrogen oxides and/or sulfur oxides. Installation raw material gas is mixed with ammonia and irradiated with electron beams, and the ammonia injected into the flue gas stream above the center electron beam entering the reactor, at a distance of not more than 2.5 times the radius of action of electron beams, most preferably at a distance of from 0.5 to 1 range of these electron beams. Ammonia is injected in one of the following ways: (1) serves only ammonia; (2) serves ammonia and air together; (3) serves ammonia and water together; (4) serves ammonia, air and water together. From the point of view of installation ammonia preferably in diluted form in the form of a mixture of heated ammonia and dry air (with a dew point of about - 15oOr less, at a pressure of 1 atmosphere). Now submit the ammonia through the pipelines, which are located so that they form the contour of the spherical divergence of electron beams. The plant reduces the amount of added ammonia to a minimum, meet two requirements - to improve the effectiveness of the

The invention relates to the field of flue gas treatment and moreover concerns an installation for flue gas treatment.

Known installation for flue gas treatment in which the raw flue gas is mixed with ammonia and irradiate electron beams to remove oxides of nitrogen and/or sulfur oxides (EP, A, 0326686).

In this case, the diffusion and the adulteration of ammonia in the flue gases or improve due to the injection of ammonia in the position at the beginning of the stream or near the inlet of the reactor so that it remains in the flue gas over a long time, or by using perforated metal for mixing with the gas.

Usually consider that the denitration reaction and desulfuromonas occur almost simultaneously, and low efficiency denitration was initially associated with insufficient mixing and insufficient diffusion of ammonia, so there was no assumption about the introduction of ammonia close to the irradiation of electron beams.

In connection with the enlarged recently, the requirements in respect of leak concentration of ammonia in the flue gas was necessary to control leakage of ammonia. However, in reality, in the previously known processes ammonia under the direction.

However, excessive addition of ammonia increased the amount of ammonia that remains in the flue gas. As the last requirement to exhaust flue gases require not only control for NOx, SOxand dust particles, but also control the leakage of ammonia at the outlet, it was necessary to inject ammonia into the optimum phase in the minimum required amount that provides the desired efficiency of the denitration reactions and desulfuromonas.

The present invention is the task of creating installations for flue gas treatment by irradiation of electron beams, which would provide a reduction in the addition of ammonia to the required minimum number which meets simultaneously two criteria: on the one hand, increases the efficiency of the denitration and desulfuromonas, and on the other hand, reduces the amount of leakage of ammonia to several tens of ppm.

The problem is solved in that the installation for the treatment of flue gases, in which the raw flue gas is mixed with ammonia and irradiate electron beams to remove oxides of nitrogen and/or sulfur oxides, according to izobreteny the e is more than 2.5 times the radius of action of electron beams.

It is desirable that this distance was not more than 2.0 range electron beams, preferably not more than 1.5 times the radius of action of electron beams, and even more preferably from 0.5 to 1 range electron beams.

Perhaps ammonia to enter any of the following ways: feeding only ammonia, serve together ammonia and air, feeding together ammonia and water, feeding together ammonia, air and water.

Suitable ammonia to enter through the pipelines, which are located so that they form the contour of the spherical divergence of the input beam.

In a preferred embodiment, ammonia and air are injected together so that the ammonia is mixed for dilution with dry air, the dew point temperature which is 15oC or less, at a pressure of 1 ATM.

According to the invention, the position of the inlet ammonia sets the distance from the zone of irradiation of electron beams and install it rather closer than further away from the zone of irradiation in the reactor. It is also effective to reduce the concentration of leakage of ammonia to a low level.

If ammonia is added to the normal area first will be the reaction of de is given by the flue gas reaches the irradiation zone, part of the injected ammonia to be spent in thermochemical reaction desulfuromonas.

On the other hand, the larger the excess of ammonia, the higher the denitration efficiency, but actually part of the added ammonia is spent in reaction desulfuromonas, and the course of the reaction denitration be not the same as I would like. This will lead to a higher efficiency of the reaction desulfuromonas than the denitration reaction.

The invention is further explained in the description of specific variants of its implementation to the attached drawings, in which:

Fig. 1 depicts a process flow fixtures, which are used to control the operation of the installation according to the invention;

Fig. 2 is a graph of the efficiency of the denitration reactions and desulfuromonas depending on the input position ammonia;

Fig. 3 is a graph of the concentration of leakage of ammonia from the input position ammonia;

Fig. 4 - scheme of the provisions of the input of ammonia, which is used to check performance;

Fig. 5 - scheme of the provisions of the input ammonia according to the present invention;

Fig. 6 is a front view illustrating the position of the input ammonia, which correspond to the contour divergence eloader the invention ammonia is introduced into the position in the direction of flow of the flue gases above the center electron beam, introduced into the reactor, and which is separated from it by a distance of not more than 2.5 times the radius of action of electron beams, preferably not more than 2.0 times, more preferably not more than 1.5 times, and most preferably from 0.5 to a value equal to the specified range.

Taking into account various factors such as the condition of the flue gases, the desired degree of denitration and desulfurization, efficiency and limitations associated with the installation, ammonia serves any of the following ways:

1) serves only ammonia;

2) serves at the same time ammonia and air;

3) serves at the same time the ammonia and water;

4) serves simultaneously ammonia, air and water.

From the point of view of operation, it is preferable to apply the ammonia diluted in a mixture of heated ammonia and dry air (with a dew point of approximately -15oC or less in the open air). Now submit the ammonia pipes, which are arranged so that they form the contour of the spherical divergence of electron beams.

As already stated, usually ammonia was injected into the situation at the beginning of the flue gas stream in the reactor in order to improve the diffusion and peremeshivaniya, and part of the injected ammonia was spent, what was slowed last reaction, thereby reducing its effectiveness.

In the present invention this problem is solved by the introduction of ammonia into the positions indicated in Fig. 4, and is located in the flow direction of the flue gases from the centre introduced into the reactor electron beams at a distance of not more than 2.5 times the radius of action of electron beams, preferably not more than 2.0 times, more preferably not more than 1.5 times, and most preferably from 0.5 to a value equal to the specified range.

If we accept such an arrangement, the amount of ammonia, which otherwise would be consumed in the reaction desulfuromonas, is reduced, and the amount of ammonia that enters the denitration reaction increases, which consequently leads to increased efficiency denitration.

However, the intended effect of the invention cannot be achieved, if the ammonia to enter the position at a distance of more than 2.5 times the radius of action of electron beams. On the other hand, if you enter ammonia in a position that is too close to the area of irradiation of electron beams, part of the injected electron beam is as beams, but when bombarded by electrons pipeline, which supplies ammonia, so much heat that you have to take special precautions that requires security.

The following examples are given to further illustrate the invention but does not limit.

Flue gas is treated in the reactor 13 (see Fig. 4) with the cross-section of 1,100 mmn1,000 mmwdue to the irradiation of electron beams coming from the electron beam generator 11. Ammonia, diluted about 100 times the dry air (with a dew point of 15oC at 1 ATM) is fed through line 12 and enter in three positions, which are located at the beginning of the flue gas stream at a distance of 1,100 mm (equal to the radius of electron beams which are designated 14 in Fig. 4, which is defined taking into account losses of electron beams, which are caused by the window in the area of irradiation of electron beams, where it creates the electron beam generator 11 when the acceleration voltage of 0.5 MeV), 1,500 mm and 4.00 mm, under constant conditions of irradiation of electron beams.

Calculate the efficiency of denitration and desulfurization, which in this case can be achieved. Usl is on Fig. 1.

In accordance with Fig. 1 flue gas generated in the boiler 1 and contains SOxand/or NOx, is cooled in the cooling tower 2 and is introduced into the reactor 4, which is provided with a pipeline for supplying ammonia 3. Flue gas is irradiated with electron beams from the electron beam generator 5, so SOxand NOxbecome, respectively, in the ammonium sulfate and ammonium nitrate in solid form, which are then captured by electroanalytical 6 and bag filter 7. After that, the cleaned gas enters the atmosphere through the suction fan 8 and the exhaust pipe 9.

The test results presented in table 2 and Fig. 2 and 3.

It is obvious that improved the efficiency of the denitration while reducing leakage of ammonia, if the ammonia is introduced into the situation, which is located to the center of the electron beam (in the direction of flow) at a distance in the reactor, not more than 2.5 times the radius of action of electron beams, preferably not more than 2.0 times, more preferably not more than 1.5 times, and most preferably from 0.5 to 1.0 times. In the test interval efficiency desulfuromonas comparable with values obtained in the known methods. what≪ E < 2.5 MeV) is called the "radius" of the electron, which is expressed by the following empirical formula:

R = (0,412 E1,256-0,0954 LnE)/,

where R is the radius (cm) of the electron;

E represents the acceleration voltage (MeV);

represents the density (g/cm3).

The results of the calculation range for accelerating voltage of 0.5-1.0 MeV are presented in table 3 without taking into account the energy loss through Windows, through which the electron beams coming from the electron beam generator. In this example, the range of electron beams is estimated as 1,100 mm at an accelerating voltage of 0.5 MeV, depending on the distance of electron beams and energy loss through the window.

In accordance with the method of the present invention ammonia is introduced into the position in the direction of the gas flow of the flue gases, i.e. to the center of the electron beam, which is injected into the reactor at a distance of not more than 2.5 times larger than the radius of electron beams, preferably not more than 2.0 times, more preferably not more than 1.5 times, and most preferably from 0.5 to 1.0 range of electron beams, which effectively increases the efficiency of the denitration while still reducing the enitrely, which in the previously known methods was less than 80%, can be increased to such a high magnitude as 85-90% by the method of the present invention when the same power of the electron beam generator output. This means that you can achieve the denitration efficiency, comparable with previously known methods even when the reduction in the output power of the electron beam generator.

Further, reduced production costs for processing flue gas by irradiation with electron beams, and this is an additional advantage of reducing power consumption in addition to the existing benefits of flue gas treatment due to their irradiation with electron beams.

1. Installation for flue gas treatment in which the raw flue gas is mixed with ammonia and irradiate electron beams to remove oxides of nitrogen and/or sulfur oxides, characterized in that the ammonia injected into the flue gas stream above the center electron beam entering the reactor, at a distance of not more than 2.5 times the radius of action of electron beams.

2. Installation under item 1, wherein the specified distance is not more than 2 range e pushvalue electron beams.

4. Installation under item 1, wherein the specified distance is from 0.5 to 1 range electron beams.

5. Installation under item 1, characterized in that the ammonia impose any of the following ways: served only ammonia; served together ammonia and air; served together ammonia and water; served together ammonia, air and water.

6. Installation according to any one of the preceding paragraphs, characterized in that the ammonia is injected through the pipelines, which are located so that they form the contour of the spherical divergence of the input beam.

7. Installation under item 5, characterized in that the ammonia and air are injected together so that the ammonia is mixed for dilution with dry air, the dew point temperature which is 15oC or less, at a pressure of one atmosphere.

Priority items: (specification of signs);

11.08.95 on PP.1, 2 and 6;

18.08.94 on PP.3 - 7.

 

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