JP5590370B2 - Wet flue gas desulfurization equipment - Google Patents

Description

  The present invention relates to a flue gas treatment apparatus that removes harmful substances in exhaust gas discharged from a combustion apparatus such as a boiler, and in particular, a function that can reduce the drift of exhaust gas and prevent a decrease in desulfurization performance in a gas absorption part. The present invention relates to a wet flue gas desulfurization apparatus.

  Desulfurization systems that remove sulfur oxides from flue gas generated by fossil fuel combustion at thermal power plants, etc., mainly use the wet limestone-gypsum method, and among them, a highly reliable spray method is often adopted. ing. However, with the diversification of fuels and demands for reduction of wastewater, severe operating conditions are required for desulfurization equipment, and more advanced technology is required to maintain desulfurization performance and prevent troubles.

As a known example of a wet flue gas desulfurization apparatus employing a conventional spray system, a side view of an absorption tower constituting the desulfurization apparatus is shown in FIG. 6, and a sectional view taken along the line DD ′ in FIG. 6 is shown in FIG. . This wet flue gas desulfurization apparatus mainly includes an absorption tower body 1, an inlet duct 2, an outlet duct 3, an absorbing liquid circulation pump 4, a circulating tank 6, a stirrer 7, an air supply pipe 8, a mist eliminator 9, and an absorbing liquid extraction. It is comprised from the pipe | tube 10, the circulation piping 11, the spray header 12, the spray nozzle 13, etc. The exhaust gas discharged from the boiler is introduced into the absorption tower body 1 from the inlet duct 2 and discharged from the outlet duct 3 provided at the top of the tower. During this time, the carbonic acid sent by the absorption liquid circulation pump 4 provided in the circulation pipe 11 connecting the side wall of the circulation tank 6 at the lower part of the absorption tower body 1 and the empty tower part (gas absorption part) of the absorption tower body 1. The absorption liquid 5 containing calcium is injected from a plurality of spray nozzles 13 attached to the spray header 12 disposed in the empty tower portion of the absorption tower body 1, and the gas-liquid contact between the absorption liquid 5 and the exhaust gas is performed. Absorbs sulfur oxides (SO _x ). The absorbing solution that has absorbed SO _x once accumulates in the circulation tank 6 provided at the lower portion of the absorption tower body 1 and is oxidized by oxygen in the air supplied from the air supply pipe 8 while being stirred by the oxidizing stirrer 7. To produce calcium sulfate (gypsum).

  In the wet type flue gas desulfurization apparatus adopting this conventional spray system, a plurality of stages of spray headers 12 installed in the gas absorption part are arranged in parallel to each other at equal intervals in the gas flow direction. Further, the spray header 12 is structured such that the spray liquid with a uniform spray amount is obtained from the plurality of spray nozzles 13 attached to the spray header 12, so that the spray header 12 becomes thinner from the joint with the absorbent circulation pipe 11 toward the tip. ing. Depending on the structure and arrangement of the spray header 12, the size of the exhaust gas passage space differs when the vicinity of the joint with the absorbent circulation pipe 11 and the tip are compared. For this reason, the flow of the exhaust gas introduced from the inlet duct 2 is concentrated on the front end portion of the spray header having a relatively wide exhaust gas passage space, and exhaust gas blow-out occurs. As a result, the ratio of the absorption liquid flow rate to the exhaust gas flow rate in that portion is extremely reduced, so that the absorption liquid 5 and the exhaust gas cannot sufficiently come into contact with each other, causing a reduction in desulfurization performance.

  Further, FIG. 8 shows a wet type flue gas treatment apparatus provided with a perforated plate, and FIG. In this wet flue gas desulfurization apparatus, a porous plate 16 is installed in a direction perpendicular to the exhaust gas flow so as to partition the exhaust gas flow in the tower, and the desulfurization absorption liquid sprayed at the upper part of the absorption tower is retained on the porous plate 16. It is characterized in that the gas-liquid contact efficiency can be increased while preventing the drift of the exhaust gas, and the desulfurization performance is improved.

  In a wet desulfurization apparatus in which a plurality of spray headers are installed, an example in which a perforated plate is disposed between adjacent spray header stages or upstream of the spray header installed in the uppermost stream of the exhaust gas flow is disclosed in Japanese Patent Application Laid-Open No. 54-116386. Yes.

In this way, when the perforated plate is arranged in the absorption tower body 1 so as to partition the exhaust gas flow, the gas-liquid contact efficiency can be increased, so that the gas-liquid ratio is reduced by improving the desulfurization performance, and the absorption liquid is circulated. Pump power to be reduced can be reduced. However, the SO _x absorption by the droplets of the absorbing liquid sprayed from the spray nozzle 12 also affects the falling speed of the spray droplets, so that the space between the installed perforated plate and the spray header installed above it can be widened. Desirably, a space for installing the perforated plate must be secured in the height direction of the absorption tower. Therefore, even if the amount of the absorbing liquid circulated between the circulation tank 6 and the empty tower part (gas absorption part) of the absorption tower main body 1 can be reduced, the effect on downsizing the apparatus is small. Furthermore, as shown in FIGS. 8 and 9, it is difficult to secure a perforated plate installation space or attach a support for perforated plate installation, so it is difficult to remodel an existing desulfurization apparatus and attach a perforated plate. Therefore, application to existing desulfurization equipment is not easy.

JP 54-116386 A

  The above prior art has a problem that exhaust gas blow-out occurs in the absorption tower due to the structure and arrangement of the spray header, and the desulfurization performance deteriorates. In addition, when a plurality of perforated plates are installed between the spray headers in the absorption tower, exhaust gas blow-off is suppressed and the cost is reduced by reducing the gas-liquid ratio. Therefore, the effect on reducing the size of the desulfurization apparatus is small. Therefore, application to existing desulfurization equipment is difficult.

  An object of the present invention is to provide a wet-type flue gas desulfurization apparatus equipped with a perforated plate that can achieve cost reduction by reducing the gas-liquid ratio while achieving further high-efficiency desulfurization performance to solve the above problems There is.

The above-mentioned problem of the present invention is solved by the following means.
The invention described in claim 1 includes an inlet portion (2) for introducing exhaust gas discharged from the combustion apparatus, and a spray header (12) having a number of spray nozzles (13) in a cross section perpendicular to the flow of the introduced exhaust gas. Absorption tower main body (1) installed in a plurality of stages in the exhaust gas flow direction, a circulation tank (6) storing an absorption liquid containing calcium carbonate provided at a lower portion of the absorption tower main body (1) , and the circulation tank (6 ) comprises a circularly supplying absorption liquid circulation system the absorption solution spray nozzle (13) from, by contacting the gas-liquid absorption liquid and flue gas sprayed from the spray nozzles (13), the wet to remove sulfur oxides in the exhaust gas In flue gas desulfurization equipment,
The spray header (12) is installed in a plurality of stages in a direction orthogonal to the exhaust gas flow, and further includes a structure for retaining the absorbing liquid on the same plane as at least one stage of the spray header (12) , the structure comprising: (a) the spray header ( 12) A support (15) provided with a large number of openings for securing exhaust gas passages at uniform intervals by stretching flat plates in a lattice pattern between the spray headers (12) and the inner wall of the absorption tower body (1). Or (b) a perforated plate between the spray headers (12) and between the spray header (12) and the inner wall of the absorption tower body (1), with a support (15) and an upper or lower portion of the support (15). It is a wet flue gas desulfurization apparatus characterized by comprising the structure which arrange | positions (16) .

Same invention of claim 2, among the plurality of stages spray header (12), at least one stage or more spray headers except spray header (12) of the most downstream stage of the exhaust gas flow Re direction (12), wherein the spray header (12) The wet flue gas desulfurization apparatus according to claim 1 , further comprising a structure for retaining the absorbing liquid on a flat surface.

The invention according to claim 3 has a structure in which the absorbing liquid stays on the same plane as at least one stage of the spray header (12), and the opening ratio of the opening through which the exhaust gas passes through the plane of the one stage of the spray header (12) is determined by the spray header stage. 3. The wet flue gas desulfurization apparatus according to claim 1, wherein the wet flue gas desulfurization apparatus is 30% to 50% with respect to a cross-sectional area in a direction orthogonal to the gas flow of the absorption tower.

(Function)
In the wet type flue gas desulfurization apparatus, SO _x such as SO ₂ in the exhaust gas is absorbed when it comes into contact with the absorbing liquid injected from the spray nozzle attached to the spray header. However, the spray header structure that becomes narrower as it goes from the base side to the tip of the prior art, and a large number of spray headers are arranged in parallel with each other at equal intervals in the direction crossing the gas flow. Occurs, the contact between the absorbing liquid and the exhaust gas becomes insufficient, and the desulfurization performance is deteriorated.

  Conventionally, this problem has been dealt with by devising the arrangement method of the spray nozzle or installing a perforated plate between a plurality of installed spray header stages. In the conventional technique of installing a perforated plate, the exhaust gas blow-out by the perforated plate is alleviated, and the gas-liquid contact is promoted by the retention of the absorbing liquid on the perforated plate, so that highly efficient desulfurization performance can be obtained. It was possible. However, although the exhaust gas flow is rectified by the perforated plate, the drift reappears due to the above-described structure of the spray header installed above the perforated plate (downstream of the gas flow). Moreover, in the conventional perforated plate, in order to secure the installation space, the effect of making the apparatus compact by reducing the gas-liquid ratio is small, and the application to the existing desulfurization apparatus is not easy.

  On the other hand, in the present invention, the spray header is one or more (preferably other than the most downstream) spray headers whose longitudinal direction is oriented in a direction orthogonal to the flow of exhaust gas, in which exhaust gas drift is likely to occur, and which are installed in a plurality of stages in the exhaust gas flow direction. By making the portion have a structure in which the absorbing liquid is retained, it becomes possible to rectify the exhaust gas and obtain higher desulfurization performance. At the same time, it is not necessary to newly secure a perforated plate installation space as in the prior art, and the apparatus can be effectively downsized as the gas-liquid ratio is reduced by improving the desulfurization performance. Also, as a structure for retaining the absorbing liquid on the spray header plane, the absorbing liquid comprising the spray header and a support provided in a lattice form around the spray header or a porous plate integrated with the spray header and the spray header is retained. By adopting the structure, it is only necessary to fix the porous plate to the existing spray header, and it is easy to apply to the existing desulfurization apparatus without impairing the desulfurization performance.

According to the first aspect of the invention, it is possible to improve the gas-liquid contact efficiency and prevent the desulfurization performance by preventing blow-off and drift of exhaust gas at the spray header installation portion inside the absorption tower. Thus, it is not necessary to secure a new perforated plate installation space, and the existing desulfurization apparatus can be easily adapted to existing projects because only the spray header is modified. Thus, the apparatus can be effectively downsized with the reduction of the gas-liquid ratio by improving the desulfurization performance.

According to the invention of claim 2 Symbol placement, in addition to the effect of the first aspect, on the plane formed of the spray header of the most downstream stage of the exhaust gas flow, without the structure for retention of the absorbed liquid to the desulfurization rate Since the influence of is small, it can be omitted. In addition, the amount of circulating absorbent liquid can be reduced by improving the desulfurization performance, and the number of spray headers can be reduced more than before.

According to the invention described in claim 3 , in addition to the effect of the invention described in claim 1 or 2 , orthogonal to the gas flow of the absorption tower in the spray header stage having a structure in which the absorbing liquid is retained on the same plane of the spray header. The desulfurization performance is effectively improved without causing flooding (a state in which the absorbing liquid continues to stay and overflow without flowing) by setting the porosity of the porous area to the cross-sectional area in the direction of 30% to 50%. be able to.

According to the invention described in claim 5, in addition to the effect of the invention described in claim 1, the direction orthogonal to the gas flow of the absorption tower in the spray header stage configured to retain the absorbing liquid on the same plane of the spray header. with 30% to 50% of the void rate of the porous to the cross-sectional area of the and to Turkey, without causing flooding (oversubscribed without falling continues absorbing liquid retained), to improve the desulfurization performance effectively be able to.

It is a figure which shows the principal part structure of the flue gas processing apparatus which implemented this invention. FIG. 2 is a cross-sectional view taken along the line A-A ′ of the embodiment in FIG. 1. It is a schematic diagram in the dotted line B in FIG. FIG. 2 is a cross-sectional view taken along the line A-A ′ of the embodiment in FIG. 1. FIG. 5 is a cross-sectional arrow view taken along line C-C ′ in FIG. 4. It is a figure which shows the principal part structure of the conventional wet flue gas desulfurization apparatus. FIG. 7 is a sectional view taken along line D-D ′ in FIG. 6. It is a figure which shows the principal part structure of the wet flue gas desulfurization apparatus at the time of installing the conventional perforated panel. FIG. 9 is a sectional view taken along line E-E ′ of FIG. 8.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a main part configuration of a wet flue gas desulfurization apparatus which is an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA ′ of the absorption tower in FIG. The outline | summary of the structure which has a function to make a liquid retain on a spray header plane is shown. FIG. 3 is a schematic diagram within a dotted line B in FIG. 2 and shows a structure in which the absorbing liquid is retained by spreading the spray header support in a lattice shape. FIG. 4 is a cross-sectional view taken along the line AA ′ of the absorption tower in FIG. 1 when the method of integrating the spray header and the porous plate is adopted as a method for retaining the absorbing liquid on the spray header plane. FIG. 5 is a cross-sectional view taken along the line CC ′ in FIG. 4 and shows the positions of the spray header, the spray header support, and the porous plate when the spray header and the porous plate are integrated using the spray header support. is there.

  An embodiment of the present invention will be described with reference to FIG. In each stage of the spray header 12 except for the most downstream stage of the plurality of stages of the spray header 12 provided in the absorption tower main body 1, the absorbent is retained on the spray header plane.

  In one embodiment, as shown in the schematic diagram of FIG. 3, the exhaust gas flow path is formed in a lattice pattern by the support 15 provided at appropriate intervals between the spray headers 12 and between the spray header 12 and the inner wall of the absorption tower body 1. However, the arrangement of the support 15 is not limited to that shown in FIG. 3 and can be arranged according to the shape of the spray header.

  4 and 5 show the configuration of another embodiment. Supports 15 are provided at appropriate intervals between the spray headers 12 and between the spray headers 12 and the inner wall of the absorption tower body 1, and a perforated plate is provided between the spray headers 12 or between the spray header 12 and the inner wall of the absorption tower body 1. 16 is arranged. In the present embodiment, as shown in the cross-sectional view of FIG. 5, the porous plate 16 is arranged on the plane formed by the spray header 12 and the support 15 in one stage, but the arrangement of the porous plate 16 is not limited to that shown in FIG. You may arrange | position to the lower part of the support 15, you may attach directly to the upper part or lower part of the spray header 12, and an equivalent effect is acquired by arrange | positioning on the same plane as the spray header 12. FIG.

In FIG. 1, the absorption liquid retention structure in which the retention portion 14 is formed in each stage of the spray header 12 prevents the exhaust gas from flowing through and drifting, and also prevents the recurrence of the exhaust gas drift in the spray header installation portion. It is possible to obtain desulfurization performance. The spray header 12 at the most downstream stage of the exhaust gas flow (uppermost stage in FIG. 1) has a small influence on the desulfurization rate, and thus the structure for retaining the absorbing liquid on the spray header 12 as described above can be omitted. Further, the amount of circulating absorbent is reduced by improving the desulfurization performance, and the number of stages of the spray header 12 can be reduced. Unlike the conventional wet flue gas desulfurization device in which the perforated plate 16 is installed between the two stages of the spray headers 12, 12 or upstream of the spray header 12 installed at the uppermost stream of the exhaust gas flow, on the plane of the spray header 12. Therefore, it is not necessary to provide a space for installing the perforated plate 16 in the height direction of the absorption tower body 1, and the height of the desulfurization absorption tower is reduced with the reduction of the circulation volume of the absorption liquid. Therefore, the running cost is reduced and the apparatus is made compact.

開口率が３０％未満では、排ガスの圧力損失が著しく増加するだけでなく、スプレヘッダ部に滞留した吸収液が落下せずに溢れてしまう可能性が高くなる。一方、前記開口率が５０％を超えて大きくなり過ぎると、吸収液の滞留が起こりにくく、十分な脱硫性能向上効果が得られない。

In addition, when the present invention is applied, in order to effectively improve the desulfurization performance without causing flooding (a state in which the absorbing liquid stays and overflows without flowing down), the exhaust gas passes through a single spray header plane. From the data shown in Table 1, it is preferable to set 30 to 50% of the horizontal cross-sectional area of the absorption tower.

If the opening ratio is less than 30%, not only the pressure loss of the exhaust gas is remarkably increased, but also the possibility that the absorbing liquid staying in the spray header portion overflows without falling. On the other hand, if the opening ratio exceeds 50% and becomes too large, the stagnation of the absorbing solution hardly occurs, and a sufficient desulfurization performance improvement effect cannot be obtained.

Moreover, when integration of the spray header 12 and the perforated plate 16 is adopted as a method for retaining the absorbent on the spray header plane, the spray header 12 is disposed between the inner wall of the absorption tower and the spray header 12 on the same horizontal plane as shown in FIG. The perforated plate 16 can be installed on the support 15 provided between the spray header 12 and the structure in which the perforated plate 16 is supported by the spray header 12, thereby greatly reducing the amount of fixing support material for the perforated plate 16. can do. Therefore, the existing desulfurization apparatus can be easily applied by installing the porous plate 16 in the gap between the spray headers 12 as shown in FIGS. In addition, the hole diameter of the perforated plate 16 provided in the spray header installation portion needs to be set in consideration of the occupied horizontal sectional area of the spray header 12 and the spray nozzle 13 and needs to be larger than the conventional perforated plate by the occupied area of the spray header 12. There is. The hole shape of the conventional perforated plate is circular, but in this embodiment, it is desirable to improve the strength by making the perforated plate 16 into a quadrilateral or hexagonal shape. The hole shape shown in FIG. 4 is a regular hexagon, which is an example.

  The present invention is considered to be one of the effective measures for solving the cost reduction of the desulfurization absorption tower and the exhaust gas blow-off at the spray header in the absorption tower.

DESCRIPTION OF SYMBOLS 1 Absorption tower body 2 Inlet duct 3 Outlet duct 4 Absorption liquid circulation pump 6 Circulation tank 7 Stirrer 8 Air supply pipe 9 Mist eliminator 10 Absorption liquid extraction pipe 11 Circulation pipe 12 Spray header 13 Spray nozzle 14 Absorption liquid retention part 15 Support 16 Perforated plate

Claims (3)

An inlet portion (2) for introducing exhaust gas discharged from the combustion apparatus and a spray header (12) having a plurality of spray nozzles (13) in a cross section perpendicular to the flow of the introduced exhaust gas are installed in a plurality of stages in the exhaust gas flow direction. absorption and the absorption tower body (1), circulation tank which stores an absorbent liquid containing a calcium carbonate provided in the lower portion of the absorption column body (1) and (6), from said circulation tank (6) to spray nozzles (13) In a wet flue gas desulfurization apparatus that includes an absorbing liquid circulation system that circulates and supplies liquid, and that makes gas-liquid contact between the absorbing liquid sprayed from the spray nozzle (13) and the exhaust gas,
The spray header (12) is installed in a plurality of stages in a direction orthogonal to the exhaust gas flow, and further includes a structure for retaining the absorbing liquid on the same plane as at least one stage of the spray header (12) .
(A) Between the spray headers (12) and between the spray header (12) and the inner wall of the absorption tower main body (1), a large number of openings are provided in which a flat plate is stretched around in a lattice shape to ensure exhaust gas passages at uniform intervals. Structure with the provided support (15) or
(B) A support (15) and a perforated plate (16) are arranged above or below the support (15) between the spray headers (12) and between the spray header (12) and the inner wall of the absorption tower body (1). A wet flue gas desulfurization apparatus characterized by comprising the above structure . Of the plural stages spray header (12), at least one stage or more spray headers except spray header (12) of the most downstream stage of the exhaust gas flow Re direction (12), is retained absorption liquid in the same plane as the spray header (12) The wet flue gas desulfurization apparatus according to claim 1 , further comprising a structure. The absorption liquid is allowed to stay on the same plane as at least one stage of the spray header (12), and the opening ratio of the opening through which the exhaust gas passes through the plane of the one stage of the spray header (12) is changed to the gas flow of the absorption tower at the spray header stage. The wet flue gas desulfurization apparatus according to claim 1 or 2, characterized in that it is 30% to 50% with respect to the cross-sectional area in the orthogonal direction.

Images