Disperser of sprayer-drier absorber

FIELD OF THE INVENTION

The present invention relates to a spray dryer absorber which serves for removing gaseous pollutants from a hot process gas and comprises a spray dryer chamber, and at least two disperser mounted on the roof of the spray dryer chamber, each such disperser used for dispersing a portion of the hot process gas around respective atomizer which atomizes the absorbent liquid, each disperser being provided with flow guiding devices, which gives parts of the hot process gas around a rotational movement of the sprayer, viewed from the top of the spray drying chamber.

The present invention further relates to a method of removing gaseous pollutants from a hot process gas by means of a spray dryer absorber.

BACKGROUND OF THE INVENTION

The combustion of fuels such as coal, oil, peat, waste, etc. for combustion installations, such as power plants, a hot process gas is generated, such a hot process gas, often referred to as a flue gas contains harmful substances, including acidic gases such as sulfur dioxide, SO2. It is necessary to remove as much as possible over the acid gases from the flue gas before the flue gas can be released into the surrounding atmosphere. For the removal of acid gases, including sulfur dioxide, from the flue gas can be used in the spray dryer absorber.

EXAMPLE spray dryer absorber can be found in US 4755366. The spray dryer absorber comprises a chamber which is equipped with a rotary atomizer having an atomizing wheel. Is fed into the rotary atomizer aqueous suspension, sometimes referred to as slurry, which comprises an absorbent, such as limestone. Atomizer wheel rotates at a high number of revolutions per minute and atomizes the aqueous suspension is such that very small droplets are formed. Small droplets absorb acid gas components from the flue gas, and then form a solid residue thanks to the drying effect of the spray dryer absorber.

A problem of the spray dryer absorber according to US 4755366 is that it is difficult to increase the capacity of a single spray dryer absorber with respect to the flow of flue gas. One reason for this difficulty is that a very high number of revolutions of the wheel creates a mechanical spraying obstacles increase its size. Thus, often it becomes necessary to build two, three, or more parallel spray dryer absorption chamber in order to adapt to the higher costs of the flue gas.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a spray dryer absorber which can be designed for a higher flue gas cost than the spray drying absorber and the prototype.

This object is achieved by means of a spray dryer absorber which serves for removing gaseous pollutants from a hot process gas and comprises a spray dryer chamber, and at least two disperser mounted on the roof of the spray dryer chamber, each such disperser used for dispersing a portion of the hot process gas around respective atomizer that sprays the absorption liquid, each disperser equipped with a device the flow direction, which gives the corresponding portion of the hot process gas rotary movement around the atomizer, as seen from above the spray drying chamber, wherein the spray drying absorber is characterized in that said at least two disperser located at substantially the same distance from the periphery of the spray dryer chamber, the device flow direction of at least one specific dispersant of the at least two dispersants serves to impart said portion of the hot process gas passing through that specific disperser, the rotational motion in a direction which is opposite to the rotational movement corresponding portion of hot process gas dispersible in at least one other dispersant, located closest to said at least one specific dispersant, as viewed along the periphery of the spray dryer chamber.

An advantage of this spray dryer absorber is that two or more of the dispersant can be installed in one and the same spray dryer chamber, without that these dispersants influence each other negatively. Therefore, the capacity with respect to the flow of flue gas and relative to the flow of the absorbing liquid spray dryer absorber can be increased, still maintaining an efficient drying of liquid droplets and efficient removal of gaseous pollutants.

According to one embodiment of the spray dryer absorber comprises at least three of the dispersant, where a maximum of two consecutive dispersant of the at least three dispersants as seen along the periphery of the spray dryer chamber, working for imparting feed to the hot process gas rotary motion in one and the same direction. An advantage of this embodiment is that it minimizes the harmful influence on the process-mixing between the gas and the liquid droplets which may be caused by neighboring dispersants, imparting to them the incoming gas in the same direction of rotational movement. Preferably when the total number of dispersants is even, such as in a spray drying absorber with a total of 4, 6 or 8 dispersers, each specific dispersant imparts incoming to gas direction of rotational motion, which is opposite to the direction of rotary motion imparted to corresponding portions of the process gas supplied to the closest adjacent to this particular dispersant dispersants. If the total number of dispersants is odd, as in the spray dryer absorber in total 3, 5, 7 or 9 dispersants case of two consecutive dispersants imparting enters them Process gas in the same direction of rotational motion are minimized in order to have the spray drying absorber is only one case of two consecutive dispersants, which give the same direction of the process gas rotary motion.

According to one embodiment, the spray drying chamber is circular when viewed from above. An advantage of this embodiment is that it can avoid the harmful effects associated with the gas flow in the corners of the absorber. Moreover, the circular spray-drying chamber makes it easier to arrange the dispersers in suitable positions relative to each other in terms of the properties of the gas stream.

According to one embodiment, the total number of dispersant is from 2 to 9. It was found that this number gives a spray dryer absorber which is efficient with respect to investment and with regard to removal of gaseous pollutants.

Another object of the present invention is to provide a method of removing gaseous pollutants from large volumes of hot process gas by means of a spray dryer absorber is more efficient in respect of investment and contaminant removal efficiency than the prior art methods.

This object is achieved by a method of removing gaseous pollutants from a hot process gas by means of a spray dryer absorber comprising a spray dryer chamber, and at least two disperser mounted on the roof of the spray dryer chamber, each such disperser used for dispersing a portion of the hot process gas around a respective atomizer which sprays the absorption liquid, each disperser equipped with a device the flow direction, which gives the corresponding portion of the hot process gas rotary movement around the atomizer, as viewed from the top of the spray drying chamber, wherein the method is characterized by causing a corresponding portion of the hot process gas passing through at at least one specific dispersing of said at least two dispersants acquire rotational motion in a direction which is opposite to the rotational motion of the respective portion of the hot process gas dispersible in at least one other dispersant, located closest to said at least one particular dispersant, if look at the periphery of the spray dryer chamber.

The advantage of this method is that the risk of obtaining unwanted effects, such as formation of large droplets, weakening of the rotational movement, etc. is reduced in the areas where flow fields interact dispersants disposed adjacent to each other. This improves the efficiency of removing gaseous pollutants from a hot process gas and of drying the absorption liquid droplets.

According to one embodiment of the process said spray dryer absorber comprises at least three of the dispersant, where a maximum of two consecutive dispersant of the at least three dispersants as seen along the periphery of the spray dryer chamber, working for giving the feed back flue gas rotary motion is direction.

The following goals and characteristic features of the present invention will be apparent from the description and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to the accompanying drawings, in which:

1 is a schematic side view of the power plant;

2 is a schematic three-dimensional projection of the dispersant;

3a is a three-dimensional projection of the spray dryer absorber in accordance with the prior art;

3b is a top view of the spray dryer absorber of Figure 3;

4a is a three-dimensional projection of the spray dryer absorber in accordance with a first embodiment of the present invention;

4b is a top view of the spray dryer absorber of Figure 4;

5 is a top view of the next spray dryer absorber in accordance with the prior art;

6 is a top view of the spray dryer absorber in accordance with the second embodiment of the present invention;

7 is a top view of the spray dryer absorber in accordance with a third embodiment of the present invention;

8 is a side view and illustrates a trajectory of the droplets of liquid 7 with compared to prototype embodiments of Figures 3a and 3b;

9 is a top view of a further spray dryer absorber in accordance with the prior art;

10 is a top view of the spray dryer absorber in accordance with a fourth embodiment of the present invention;

11 is a diagram showing the amount of liquid fed to the respective wall of the spray dryer absorber in various embodiments.

DESCRIPTION OF PREFERRED EMBODIMENTS

1 is a schematic side view and shows a power plant 1. The power plant 1 comprises a boiler 2 in which combusted fuel such as coal or oil. Combustion of the fuel generates a hot process gas in a flue gas 2. Sulphur substances contained in the coal or oil will form sulfur dioxide, which will form part of the flue gas. The flue gas flows from the boiler 2 to an electrostatic precipitator 4 via a duct 6. The electrostatic precipitator 4, an example of which is described in US 4,502,872, serves to remove dust particles from the flue gas.

Flue gas from which removed most of the dust is fed to the spray dryer absorber 8 via a duct 10. The spray dryer absorber 8 comprises a spray dryer chamber 12 and four disperser 14, 16, 18, 20, which are mounted on the roof 22 of the spray dryer chamber 12 . Each of the dispersers 14, 16, 18, 20 comprises a dispenser 24. Nozzles 24 may be a so-called centrifugal spray type in which rotating at a high speed wheel is used to spray the absorption liquid. In this regard, by way of illustration and not limitation, reference may be made, for example, a centrifugal atomizer described in US 4755366, the idea of ​​which is hereby incorporated herein by reference. Another alternative is to use as spray nozzles 24 which spray the supplied absorbent liquid therein under pressure.

Each disperser 14, 16, 18, 20 is provided with a device 26, 28, 30, 32 flow direction. The distribution channel 34 is used to supply each of the dispersers 14, 16, 18, 20, a portion of the flue gas supplied through the channel 10. Each of the devices 26, 28, 30, 32 the flow direction is used to give the corresponding portion of the flue gas rotary motion around respective atomizer 24 disperser 14, 16, 18, 20. Two of the flow direction devices, namely the guides 26 and 30, 14 and dispersers 18, serve to impart a corresponding portion of the flue gas supplied to them, the rotational motion around the respective atomizer 24 in the clockwise direction, when viewed from the top of the spray dryer chamber 12.

Two of the devices the flow direction, namely the guides 28 and 32 of the dispersers 16 and 20 serve to impart a corresponding portion of the flue gas supplied to them, the rotational movement around the respective atomizer 24 in the counter-clockwise when viewed from the top of the spray dryer chamber 12.

The tank 36 serves to supply each of the nozzles 24, the flow of the absorbing liquid through the dispensing conduit 38; such absorbing liquid includes, for example, a limestone slurry (slurry).

Action respective dispersers 14, 16, 18, 20 results in the mixing of flue gas with absorption liquid. The result is that the absorption liquid absorbs gaseous pollutants, such as sulfur dioxide, SO2 from the flue gas. At the same time the absorption liquid is dried by hot flue gas, resulting in a dry product, which is collected from the bottom 40 of the spray dryer chamber 12. The dry product is removed for disposal via line 42. The flue gas, which has been removed from most of the gaseous pollutants is passed substantially vertically downward from the dispersers 14, 16, 18, 20 into the spray drying chamber 12 and leaves the spray dryer absorber 8 via a duct 44. The flue gas is directed through the channel 44 in the second filter, which may be, for example, an electrostatic precipitator 46. As alternative, the second filter may be a bag filter or any other suitable filtering device. The second filter 46 removes most of the remaining dust particles, and all the dried residues of the absorption liquid. The cleaned flue gas may then be released into the surrounding atmosphere via a clean gas duct 48.

2 shows the disperser 16 in more detail. The disperser 16 is illustrated as a bottom angle. The flow guide means 28 dispersant 16 includes a plurality of external vanes 50 and a plurality of inner guide vanes 52. The portion of the flue gas entering the disperser 16 from the distribution channel 34 as shown in Figure 1, has a general downward direction, as shown in Figure 2 by arrow F. All of the guide vanes 50, 52 have such a direction that they are forced to part of the flue gas begin to rotate around the atomizer 24. Arrows FCC indicate how the guide vanes 50, 52 will deflect the flue gas so that it is formed by rotation of the flue gas flow in a downward spiral around 24. The spray was found that such rotation of the flue gas must be very efficient for mixing the flue gas with the absorption liquid, spray atomizer 24. The direction of rotation of such flue gas flow FCC will, when viewed from the top of the spray dryer chamber 12 illustrated in Figure 1 , counter-clockwise for 16 dispersant.

It should be clear that Dispersant 20 will have a design similar to dispersant 16 shown in Figure 2. Devices 26, 30 flow direction dispersers 14 and 18 shown in Figure 1, should, on the other hand, have guide vanes that have the opposite setting compared to the guide vanes 50, 52 flow direction device 28 shown in Figure 2, so that the direction of rotation of the flue gas stream 14 from dispersants, was 18, when viewed from the top of the spray dryer chamber 12 illustrated in Figure 1, a clockwise motion.

Figure 3a shows a spray dryer absorber 108 in accordance with the construction of the prototype. This spray dryer absorber 108 has a spray dryer chamber 112 and a roof 122. At its roof of the spray dryer absorber 108 is provided with three dispersers 116. Each of those dispersers 116 has a construction similar dispersant 16 described above with reference to Figure 2. 3b shows a top view of the spray dryer absorber 108 in accordance with the construction of the prototype. Since each of the dispersers 116 has a construction similar dispersant 16 described above with reference to Figure 2, the flow of the flue gas supplied to each of the dispersers 116 will be given a rotational motion in the counterclockwise direction when viewed from the top of the spray dryer absorber 108. This is illustrated in Figure 3b by means of arrows FCC. However, it was found that the operation of the spray dryer absorber 108 on the prototype shown in Figures 3a and 3b, resulting in serious problems with absorption liquid hitting the wall of the spray dryer chamber 112, e.g., in the position X shown in FIG. 3b. Contact with the absorption liquid on the wall of the spray dryer chamber 112 may result in the formation of large aggregates causing difficulties in the spray dryer absorber 108. Furthermore, it has been found that during operation of the spray dryer absorber 108 formed large droplets of absorption liquid. For the drying of large droplets require much time. Therefore, droplets that are not completely dried may fall to the bottom of the spray dryer chamber 112, or output filter, resulting in a difficulty in operation.

4a shows the spray dryer absorber 6 in accordance with a first embodiment of the present invention has been explained above with reference to Figures 1 and 2. 4a clearly shows how the spray dryer chamber 12 is equipped on its roof 22, with four dispersants 14, 16, 18, 20.

4b shows the spray dryer absorber 8 in plan view. As described above with reference to Figure 2, the dispersers 16 and 20 are attached to the feed flue gas rotary motion in a counterclockwise direction when viewed from above, as shown in Figure 4b. 4b this counter-clockwise rotation shown by arrows FCC. Further, dispersants 14 and 18 have a different design compared to the dispersers 16 and 20 and attach them to the incoming flue gas to a rotary motion in a clockwise direction when viewed from the top, as shown in Figure 4b. 4b this clockwise rotation indicated by the arrow FC.

Each of the dispersers 14, 16, 18, 20 is located at substantially the same distance D from the periphery P of the spray dryer chamber 12. Looking disperser 16, the flow directing device of this dispersant, denoted as 50 and 52 and shown in detail in Figure 2, serves to imparting portion of the flue gas passing through that specific disperser 16, rotational movement in the counter-clockwise sense when viewed from above, which is opposite to the direction of rotary motion in a clockwise direction when viewed from above, the respective portions of the flue gas, dispersible two dispersers 14 and 18 are arranged closest as seen along the periphery P of the spray dryer chamber 12 to this particular dispersant Dispersant 16. Similarly, 14 imparting feed therethrough of the fuel gas rotary motion in a clockwise direction when viewed from above, has as its closest "neighbors" two dispersant 16 and 20, the flue gas which impart the rotational motion counterclockwise. As a consequence, each of the dispersers 14, 16, 18, 20 has its closest "neighbors" two dispersant which impart flue gas opposite direction compared with the rotational movement to be given to the flue gas by that specific disperser.

As an example, at the point N1, where the dispersers 14 and 16 are located closest to each other, the flow fields from both dispersers 14 and 16 have the same direction. A similar flow behavior will be played at the points N2, N3 and N4. Hence, for all four points N1, N2, N3, N4, where the flow fields of two adjacent dispersers 14, 16, 18, 20 may interact, the flow field of the two dispersers will always have the same direction unlike the prototype design shown in Figure 3a and 3b.

The construction shown in Figures 4a and 4b, apparently creates a situation where the number of collisions between liquid droplets occurring from any two adjacent dispersers is much reduced. The result is a reduction in the formation of large droplets compared to the prior art shown in Figures 3a and 3b, further, in the spray dryer absorber 8 illustrated in Figures 4a and 4b, the rotary movement of the flue gas caused by the dispersers 14, 16, 18, 20, apparently continued for a longer time, resulting in improved contact between the absorption liquid droplets and the flue gas; such improved contact resulting in an improved removal of gaseous pollutants and a shorter drying time of the liquid droplets. The risk of formation of large aggregates on the wall of the spray dryer chamber 12 also appears to decrease as compared with the construction of the prototype.

5 illustrates a spray dryer absorber 208 in accordance with another prior art design. The spray dryer absorber 208 has a spray dryer chamber 212 and a roof 222. At its roof 222 of the spray dryer absorber 208 is equipped with five dispersers 216. Each of those dispersers 216 will have a structure similar to dispersant 16 described hereinbefore with reference to Figure 1, therefore , a construction similar dispersant 16 described above with reference to Figure 2. Five dispersers 216 placed in accordance with the same principles as the dispersant three 116 spray dryer absorber 108. As a result, the flue gas supplied to each of the five dispersers 216 will be given a rotational motion in the counterclockwise direction when viewed from the top of the spray dryer absorber indicated in Figure 5 as the FCC. In Figure 5 we were also included droplet trajectory T shown as lines starting from the respective dispersers 216. These trajectories T shows the path traversed by the individual droplets of atomized fluid within one second after they leave corresponding respective atomizer disperser 216 described herein above with reference to Figure 2. The trajectories of T based on computer calculations of the hydro- aerodynamics. The end of the path indicates the location in which almost all the liquid is dried. From Figure 6 it can be seen that the fall trajectory T on the wall of the spray dryer chamber 212, in particular at locations indicated by the letter H. This shows that the droplets are not dried, fall on the wall of the spray dryer chamber 212, in these areas, which may result in the formation of aggregates, leading to great difficulties in the spray dryer absorber 208.

6 illustrates a spray dryer absorber 308 in accordance with a second embodiment of the present invention in plan view. As can be seen, the spray dryer absorber 308 has a spray dryer chamber 312 having a roof 322. The roof 322 is equipped with five dispersers 314, 316, 318, 320 and 321 are located at equal distances from the periphery of the chamber 312. As a consequence, and as can be seen 6, five dispersers 314, 316, 318, 320 and 321 are arranged in a ring. The first and fourth 314 dispersant dispersant 320, seen in the periphery of the chamber 312, set to give them the incoming flue gas to the direction of clockwise rotation as shown in Figure 6 symbol FC. Second Dispersant 316, third 318 and fifth dispersant Dispersant 321 installed, in order to give them the incoming flue gas to the direction of rotation counter-clockwise, as shown in Figure 6 symbol FCC. Consequently, dispersants 316, 318 and 321 are constructed like dispersant 16, shown in detail in Figure 2, while dispersing 314 and 320 have guide vanes that have the opposite setting for giving the flue gas in the opposite direction of rotation, like dispersant 14 described with reference to Figure 1.

Consequently, when both the structure 6, a maximum of two of consecutive as seen along the periphery of the spray dryer chamber 312, dispersant, namely, dispersants 316, and 318 are attached to the feed flue gas in rotary motion in the same direction FCC.

Figure 6 shows the calculated trajectory T path of liquid droplets within one second after they leave the dispenser 24 corresponding to the respective disperser 314, 316, 318, 320 and 321. As can be seen from Figure 6, no path misses the wall spray-drying chamber 312. Therefore, with this arrangement will be much less of a problem with the formation of aggregates.

7 illustrates a spray dryer absorber 408 in accordance with a third embodiment of the present invention in plan view. As can be seen, the spray dryer absorber 408 has a spray dryer chamber 412 having a roof 422. The roof 422 is equipped with three dispersers 414, 416 and 418. As can be seen from Figure 7, three of the dispersant 414, 416 and 418 are arranged like three dispersants spray 116 dryer absorber 108 according to the prototype illustrated hereinbefore with reference to Figures 3a and 3b. However, returning to Figure 7, the first dispersant and second dispersant 414 416 are arranged so as to give them the incoming flue gas to the direction of rotation counter-clockwise, as shown in Figure 7 the symbol FCC. Third Dispersant 418 is arranged to impart to it the incoming flue gas to the direction of clockwise rotation as shown in Figure 7 the symbol FC. Consequently, dispersants 414, and 416 are constructed like dispersant 16, shown in detail in Figure 2, while the dispersant 418 has vanes having opposite setting for giving the flue gas in the opposite direction of rotation, like dispersant 14 described with reference to Figure 1 .

8 shows the operation of the spray dryer absorber 408 described above with reference to Figure 7, in comparison with the operation of the spray dryer absorber 108 on the prototype described with reference to Figures 3a and 3b. Trajectory T show the calculated paths of individual droplets of atomized fluid within one second after they leave the respective atomizer 24 corresponding disperser 414, 416, 418 and 116, respectively, of the spray dryer absorber 408 and 108, wherein the spray dryer absorbers 408 and 108 are shown Figure 8 is a side view. As can be seen, referring to Figure 8, the trajectory T of the spray dryer absorber 408 all preferably gather toward the center of the spray dryer chamber 412. As a result, the problem of liquid droplets impinging on a wall and forming aggregates in the spray dryer absorber 408 is strongly limited. On the other hand, the trajectory T formed in the spray dryer absorber 108 according to the prototype, it is much more random, and a substantial portion of droplets reaches the wall of the spray dryer chamber 112, e.g., in place of X, is likely to occur where the solid aggregates. As a consequence, one can expect that the spray dryer absorber 408 provides a much more stable operation with less operational problems than the spray dryer absorber 108 according to the prototype.

9 illustrates a spray dryer absorber 508 in accordance with another prior art design. The spray dryer absorber 508 has a spray dryer chamber 512 and a roof 522. At its roof 522 spray dryer absorber 508 has two dispersers 514. Each of those dispersers 514 will have a structure similar to dispersant 14 described hereinbefore with reference to Figure 1, therefore , a construction similar dispersant 16 shown in Figure 2, but with guide vanes having opposite setting. These two disperser 514 are arranged symmetrically around the center of the roof 522, and hence the same distance from the periphery of the spray dryer chamber 512. The flue gas supplied to each of the two dispersers 514 will be given a rotational motion in a clockwise direction, as shown in Figure 9 as the FC when viewed from the top of the spray dryer absorber 508. T trajectories indicate the path traversed by the individual droplets of atomized fluid within one second after they leave corresponding respective atomizer disperser 514, after one second, almost all the liquid is dried flue gas. The trajectories of T based on computer calculations of the hydro- aerodynamics. From Figure 9 it can be seen that the fall trajectory T on the wall of the spray dryer chamber 512, in particular at the place designated by the letter X. This may result in the formation of aggregates, leading to great difficulties in the spray dryer absorber 508.

10 shows the spray dryer absorber 608 in accordance with a fourth embodiment of the present invention in plan view. As can be seen, the spray dryer absorber 608 has a spray dryer chamber 612 having a roof 622. The roof 622 is equipped with two dispersers 614 and 616. As can be seen in Figure 10, two of the dispersant 614, 616 are arranged symmetrically around the center of the roof 622 and equidistantly from the periphery of the chamber wall 612. The first dispersing 614 is arranged to inject gas inflowing direction of clockwise rotation as shown in Figure 10 labeled FC. The second dispersant 616 is arranged so as to give it the gas flows into the direction of rotation counterclockwise, as shown in Figure 10 designation FCC. As a result, the dispersant 616 is constructed like a dispersant 16, shown in detail in Figure 2, while the dispersant 614 has vanes having opposite setting to make the flue gas in the opposite direction of rotation, like dispersant 14 described with reference to Figure 1.

Calculated trajectory T indicates the path of liquid droplets within one second after they leave the dispenser 24 corresponding to the respective disperser 614 or 616, after one second, almost all the liquid is dried flue gas. As can be seen from Figure 10, no path misses the wall of the spray dryer chamber 612. Consequently, in this arrangement will be much less of a problem with the formation of aggregates at the wall compared to the implementation of a prototype 8.

11 is a bar graph showing the amount of spray liquid water entering the wall of the spray drying chamber in various embodiments. Consequently, each of the bar shows the amount of water (kg / s) of a liquid spray, into the walls of spray drying chamber is calculated by means of computer hydrodynamic calculations. The lower the amount of water entering the wall, the less the risk of formation of aggregates on the wall.

From Figure 11 it can be seen that the spray dryer absorber 508 according to the prototype having two disperser 514 as shown in Figure 9, generating a stream of about 0.125 kg / s of water hits the wall of the spray dryer chamber 512, while the spray dryer absorber 608 having two disperser 614, 616, as shown in Figure 10, generates a flow of only about 0.035 kg / s of water hits the wall of the spray dryer chamber 612, being only 28% of the spray dryer 508 in the prototype.

Further, the spray dryer absorber 108 according to the prototype having three disperser 116 as shown in Figure 3b, generating a stream of about 0.130 kg / s of water hits the wall of the spray dryer chamber 112, while a spray dryer absorber 408 having three disperser 414, 416, 418, as shown in Figure 7, generates a stream of only about 0.07 kg / s of water hits the wall of the spray dryer chamber 412, being only 54% of the spray dryer 108 in the prototype.

Further, as the calculations were made for the spray dryer absorber 708 with the prototype having four dispersant. The spray dryer absorber 708 with the prototype has not been shown in detail but have a structure similar to the spray dryer absorber 8 illustrated with reference to Figure 4b, except for the fact that all four dispersant spray dryer absorber 708 attached to the prototype comes into them flue gas countercurrent direction. The spray dryer absorber 708 with the prototype having four countercurrent dispersant, generates a stream of about 0.08 kg / s of water strike the walls of the spray drying chamber, while the spray dryer absorber 8, having four disperser 14, 16, 18, 20, as shown in Figure 4b, generates a stream of only approximately 0.015 kg / s of water hits the wall of the spray dryer chamber 12, being only 19% of the spray dryer 708 in the prototype.

Finally, the spray dryer absorber 208 according to the prototype having five dispersants, as shown in Figure 5, generates a stream of about 0.205 kg / s of water hits the wall of the spray dryer chamber 212, while a spray dryer absorber 308 having five dispersants 314, 316, 318, 320 and 321, as shown in Figure 6 generates a stream of only approximately 0.015 kg / s of water hits the wall of the spray dryer chamber 412, making up only 7% of the spray dryer 208 in the prototype.

Consequently, for each of the spray dryer absorber dispersants unexpectedly much better in regard to the risk of aggregate formation on the walls of spray drying chamber to place these dispersants in accordance with the principles of the present invention over the prior art according to their placement.

It should be understood that numerous modifications to the above embodiments are possible within the scope of the appended claims.

Above it has been described that the spray dryer absorber 8, 308, 408, 608 may be provided with 2, 3, 4 or 5 dispersants. It should be clear that the same effect can be achieved with a different number of dispersants of two or more, spaced the same distance D from the periphery P of the spray dryer chamber 12. Typically, the spray drying absorber, designed in accordance with the present invention should be between 2 and 9 dispersers located at substantially the same distance D from the periphery P of the spray dryer chamber.

Above it has been described that the spray dryer absorber having at least three of the dispersant, preferably to a maximum of two of consecutive dispersant of the at least three dispersants worked to give them the incoming flue gas to rotary motion in the same direction. Consequently, in the spray drying absorber having five dispersants and designed in accordance with a further embodiment of the present invention, it should be possible, as an example, have four of these dispersants imparting gas counterclockwise rotation (FCC), and only one dispersant, giving Gas clockwise rotation (FC), or, as another example, to have three successive dispersant imparting gas counterclockwise rotation (FCC), and two consecutive dispersant imparting gas clockwise rotation (FC ). However, these alternative embodiments are generally less preferred than those shown in Figure 6, where a maximum of two of the dispersant, i.e. dispersers 316 and 318 are attached to the feed gas in rotary motion in the same direction, FCC.

To summarize, a spray dryer absorber used for removing gaseous pollutants from a hot process gas and comprises at least two dispersant. Each such disperser used for dispersing a portion of the hot process gas around a respective atomizer and for imparting a corresponding portion of the hot process gas around a rotational motion sprayer. At least one specific dispersant serves to impart passing through that specific disperser hot process gas rotational motion in a direction which is opposite to the rotational motion of the respective portion of the hot process gas dispersible by at least one other dispersant, located closest to that specific dispersant.

Although the invention has been described with reference to several preferred embodiments, those skilled be understood that there may be made various changes in the elements and their equivalents may be substituted without departing from the scope of the invention. Furthermore, there may be many modifications are made to adapt a particular situation or material to the teachings particular invention and without departing from the basic scope. It is therefore intended that the invention is not limited to the particular embodiments disclosed as the best mode for implementing the proposed invention, but the invention should include all of the falling within the scope of the appended claims. Furthermore, use of the terms "first", "second", etc. It does not denote any order of importance, but rather the terms "first", "second", etc. It is used to distinguish one element from another.