JP2016055244A - Flue gas treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flue gas treatment apparatus having a desulfurization device equipped with spray nozzles smoothly spraying without increasing the flow rate of an exhaust gas flow rising in the vicinity of the plurality of spray nozzles spraying downward an absorbent in the desulfurization device.SOLUTION: In a flue gas treatment apparatus where a plurality of branch headers 39 disposed with a plurality of desulphurization spray nozzles 27 spraying a desulfurization liquid into an exhaust gas passage disposed in an absorption tower 5 and main headers 38 connected with the branch headers 39 are installed with multi-stages in a vertical direction and the spray nozzles 27 are installed so that an interval in a vertical direction becomes 0.2d or more and 0.5d or less to an interval d in a horizontal direction between adjacent spray nozzles 27 in the spray nozzles 27 installed on each stage of the branch headers 39,: power can be reduced by about 10% in comparison with a conventional structure while highly maintaining a desulphurization rate, pressure loss in the absorption tower can be reduced and, as a result, power for operating a desulfurization device can be reduced.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust gas treatment apparatus that removes sulfur oxides contained in the exhaust gas of a power generation boiler used in a thermal power plant, and more particularly to a wet desulfurization treatment technique in which a desulfurization liquid is sprayed into the exhaust gas.

FIG. 3 shows an example of an apparatus configuration using a wet desulfurization apparatus that absorbs and removes sulfur oxide (mainly SO ₂ ) in exhaust gas by spraying a desulfurization liquid into the exhaust gas as an exhaust gas treatment apparatus in a power plant. . The example shown in FIG. 3 is an example in which coal is used as the fuel, but it is general that the same configuration is used even with heavy oil having a high sulfur content. Coal 21 and combustion air 36 are supplied to the boiler 1, and high pressure steam is produced by a boiler heat exchanger (not shown) by heat generated by the combustion reaction of the coal 21. A turbine (not shown) is rotated by the obtained high-pressure steam, and power is generated by a generator connected to the turbine.

On the other hand, the flue gas discharged from the boiler 1 is subjected to heat exchange with the combustion air by the air preheater 3, and then dust is removed by the dust collector 4. Examples of the dust collector 4 include a bag filter using a filter cloth and an electric dust collector in which an electrode is installed in an exhaust gas passage. Bag filters have low equipment costs, but there are also problems such as large pressure loss and the need to replace the filter cloth regularly. Electric dust collection with low pressure loss and relatively easy maintenance. The bowl is widely used. Generally, the gas temperature of the dust collector section is about 160 to 200 ° C. The exhaust gas discharged from the dust collector 4 is supplied to the absorption tower 5 of the wet desulfurization apparatus, and after removing SO ₂ in the exhaust gas, the exhaust gas is discharged from the chimney 2.

Here, in the absorption tower 5 of the wet desulfurization apparatus, a plurality of nozzles 27 are installed inside, and the desulfurization liquid 28 is pressurized by the circulation pump 26 and sprayed. In general, a CaCO ₃ or NaOH solution is used as the desulfurization liquid 28. The desulfurization liquid 28 sprayed in the absorption tower 5 absorbs SO ₂ in the exhaust gas, is collected as a desulfurization liquid 28 in the lower part of the absorption tower 5, and is sent from a drain line 29 to a wastewater treatment facility (not shown).

In the prior art, the desulfurization liquid spray nozzles 27 are installed in multiple stages inside the absorption tower 5 of the desulfurization apparatus, and the desulfurization liquid is sprayed from the nozzles 27 and brought into gas-liquid contact with the exhaust gas. ₂ is absorbed and removed.

  An example of the arrangement structure of the nozzles 27 installed inside the absorption tower 5 of the desulfurization apparatus is shown in FIG. FIG. 8A shows a spray nozzle 27 arranged in one horizontal sectional direction of the absorption tower 5, and FIG. 8B shows a side sectional view of the absorption tower 5 in which the spray nozzles 27 are arranged in a plurality of vertical directions. FIG. 8C shows a partial cross-sectional side view of the absorption tower 5 provided with the spray nozzles 27 arranged in three stages in the vertical direction.

  The absorption liquid 28 stored in the lower part of the absorption tower 5 of the desulfurization apparatus is pressurized by the circulation pump 26, passes through the absorption liquid piping and the header 37, and is sprayed from the spray nozzle 27 installed inside the absorption tower 5. The header 37 is composed of a main header 38 and a branch header 39, and the spray nozzle 27 is arranged in the horizontal direction from the branch header 39.

  At this time, FIG. 9 shows an enlarged view of the spray nozzle 27 shown in a portion surrounded by a broken line in FIG. FIG. 9 shows a side view of the three spray nozzles 27. The desulfurized liquid ejected from the spray nozzle 27 forms a liquid film 40 in the vicinity of the outlet of the spray nozzle 27, and the liquid film 40 is dispersed as the distance from the spray nozzle 27 increases. Droplet 41 is obtained.

  Since there is the liquid film 40 in the vicinity of the spray nozzle 27, the exhaust gas does not flow in the vicinity of the spray nozzle 27, and a gas flow that bypasses the vicinity of the spray nozzle 27 is formed as shown by an arrow in FIG. Therefore, the conventional arrangement of the spray nozzle 27 has a problem that the flow path of the exhaust gas rising between the two spray nozzles 27, 27 becomes narrow, the gas flow rate increases, and the pressure loss also increases.

  In Patent Document 1 (Japanese Patent No. 5289668), regarding a plurality of spray nozzles installed in a plurality of stages in the vertical direction inside an absorption tower of a desulfurization apparatus, the upward flow of exhaust gas in the tower passes through the tower wall portion of the absorption tower. In order to prevent this, in addition to a normal spray nozzle, a configuration is disclosed in which an auxiliary spray nozzle is disposed at a position one step lower than the spray nozzle and closer to the tower wall.

  In Patent Document 2 (Japanese Patent Application Laid-Open No. 11-179144), a sub spray nozzle is arranged at a position one step lower than the spray nozzle in the gaps of a plurality of spray nozzles installed in a plurality of stages in the vertical direction inside the absorption tower of the desulfurization apparatus. Thus, a configuration has been disclosed in which the lean portion of the spray absorbing liquid is reduced to effectively make contact between the spray absorbing liquid and the exhaust gas.

  In Patent Document 3 (Japanese Patent Laid-Open No. 11-128651), the local concentration of absorbing droplets ejected from spray nozzles arranged in a grid on the same horizontal surface of an absorption tower is measured, and a predetermined concentration value is calculated. A configuration is disclosed in which the arrangement position of the spray nozzle having a large deviation is changed.

Japanese Patent No. 5289668 JP 11-179144 A JP-A-11-128651

  According to the above prior art, the arrangement of the spray nozzles is not sufficient for the exhaust gas flow rising in the absorption tower, and it is difficult to say that the flow rate of the exhaust gas flow between adjacent spray nozzles is uniform. As a result, the desulfurization rate was not at a desirable level and there was room for improvement.

  As described above, an object of the present invention is to provide an absorption tower equipped with a spray nozzle that can smoothly perform without increasing the flow rate of the flow of exhaust gas that rises in the vicinity of a plurality of spray nozzles that spray the absorbent in the desulfurization device downward. It is providing the flue gas processing apparatus which has.

The problems of the present invention are solved by the following means.
That is, a branch header provided with a plurality of desulfurization spray nozzles for spraying a desulfurization liquid in an exhaust gas passage provided in an absorption tower of a desulfurization apparatus and a main header connecting the branch headers are installed in a plurality of stages in the vertical direction, In the flue gas treatment apparatus that absorbs and removes sulfur oxides in the vertical direction, with respect to the distance d between adjacent spray nozzles in the spray nozzle provided in the branch header of each stage, the distance in the vertical direction is 0.2 d or more and 0.5 d or less. It is a flue gas processing apparatus characterized by installing a spray nozzle to become.
(Function)
FIG. 4 shows the state in the vicinity of the spray nozzle provided in the absorption tower according to the present invention. The spray nozzles installed at intervals of d (m) in the vertical direction with respect to the gas flow are arranged so as to be shifted from 0.2 d to 0.5 d with respect to the flow direction of the exhaust gas. It can be seen that a wide flow path narrowed by the liquid film formed in the vicinity of the spray nozzle can be secured by disposing the spray nozzle with respect to the flow direction of the exhaust gas.

The image of the gas flow velocity distribution when such a spray nozzle is arranged is described in the drawing, and it can be seen that the pressure loss of the gas flow is smaller than in the case of the conventional structure.
On the other hand, the spray nozzle arrangement in the horizontal cross-section direction of the exhaust gas flow channel in the absorption tower is the same as the conventional one, and the range where the exhaust gas and the absorbing droplets contact does not change, so the desulfurization performance of the absorption tower itself will change. There is no.

  By attaching the spray nozzle to the spray header according to the present invention, it becomes possible to reduce the power by about 10% compared to the conventional structure while keeping the desulfurization rate of the desulfurization apparatus high. By changing the arrangement of the spray nozzle, desulfurization is achieved. The pressure loss in the absorption tower can be reduced without degrading the performance, and as a result, the power for operating the desulfurization apparatus can be reduced, and the power consumption can be reduced.

They are a principal part plane sectional view (Drawing 1 (A)) and a principal part side sectional view (Drawing 1 (B)) which show spray nozzle arrangement in a desulfurization device of a flue gas processing device based on the present invention. It is a schematic sectional side view of the absorption tower of the flue gas processing apparatus of FIG. It is a figure which shows the structure of a general smoke removal processing apparatus. It is a figure which shows the mode of the desulfurization liquid and gas flow of the spray part vicinity in the spray nozzle arrangement | positioning in the desulfurization apparatus absorption tower based on this invention. It is a figure which shows the relationship between the height direction distance inside a desulfurization apparatus absorption tower of this invention, and a prior art, and a pressure loss. It is a figure which shows three types of spray nozzle arrangement | positioning aspects based on this invention. It is a figure which shows the result of having evaluated the difference of power consumption from the result which evaluated the spray nozzle height inside a desulfurization apparatus based on this invention, the pressure loss, and the desulfurization rate by numerical analysis. The principal part plane sectional view (Drawing 8 (A)) and the principal part side sectional view (Drawing 8 (B)) which show arrangement of the spray nozzle in the desulfurization device absorption tower of the conventional flue gas treatment device, and the schematic side sectional view of the absorption tower ( FIG. 8C). It is a figure which shows the mode of the desulfurization liquid and gas flow of the spray part vicinity in the spray nozzle arrangement | positioning in the desulfurization apparatus absorption tower of the conventional flue gas treatment apparatus.

  An embodiment of the present invention is shown in FIG. FIG. 1 shows a configuration in which spray headers 37 (consisting of a main header 38 and a branch header 39) having a spray nozzle 27 for spraying an absorbing liquid installed in the desulfurization apparatus 5 of the exhaust gas treatment system shown in FIG. 3 are arranged in three stages. FIG. 2 is a cross-sectional plan view (FIG. 1A) and a side cross-sectional view (FIG. 1B). FIG. 2 shows the absorption liquid 28 from the bottom of the absorption tower 5 to the main header 38 having the spray nozzle 27 of FIG. It is a partial sectional side view of the desulfurization apparatus absorption tower 5 which shows the structure which circulates and supplies.

  As shown in FIG. 1, the spray nozzles 27 attached to the branch header 39 branched from the main header 38 are of two types having different attachment heights, and are installed so that the adjacent spray nozzles 27 do not have the same height.

  FIG. 5 shows changes in pressure loss inside the desulfurization apparatus absorption tower 5 having the above-described configuration. FIG. 5 shows the distance in the height direction of the desulfurization apparatus absorption tower 5 on the vertical axis, and the difference between the pressure at the outlet of the uppermost spray nozzle 27 and the pressure at each height position on the horizontal axis. For comparison, FIG. 5 also shows the pressure loss inside the desulfurization apparatus absorption tower 5 in the arrangement mode of the prior art spray nozzle 27 shown in FIGS. 8 and 9.

  In the pressure loss of the gas flow in the arrangement mode of the conventional spray nozzle 27 (indicated by a broken line in the figure), a sudden pressure loss occurs in the spray nozzle 27 portion of each stage. This is due to the liquid film in the vicinity of the spray nozzle 27. This is because the flow rate of the exhaust gas rising inside the desulfurization apparatus absorption tower 5 has increased. On the other hand, there is a gradual increase in pressure loss between the spray nozzles 27, which is due to contact between the droplets and the exhaust gas.

  On the other hand, in the case of the arrangement mode of the spray nozzle 27 of the present embodiment, the pressure loss of the exhaust gas upward flow is shown by a solid line, but the pressure loss in the spray nozzle 27 portion becomes small, and as a result, the pressure of the entire exhaust gas upward flow It can be seen that the loss is reduced compared to the prior art.

  Numerical analysis of the relationship between the distance d between the two adjacent spray nozzles 27 in the horizontal direction (d is the distance between the two adjacent spray nozzles 27 in the horizontal direction) and the distance between the two spray nozzles 27 according to this embodiment in the height direction. The results of the evaluation are shown below. Numerically analyzing the pressure loss and desulfurization rate on the gas side when droplets are sprayed from a plurality of spray nozzles 27 and the distance in the height direction of two adjacent spray nozzles 27 is changed from 0 to 0.9 d. The results are shown in FIG.

FIG. 7A shows the relationship between the spray nozzle height (the distance in the height direction between two adjacent spray nozzles 27) and the pressure loss. It can be seen that by shifting the arrangement of the two spray nozzles 27 adjacent to each other in the height direction, the gas easily passes and the pressure loss decreases. FIG. 7B shows the relationship between the height of the spray nozzle 27 and the desulfurization rate. When the height of the spray nozzle 27 is 0.3 d or more, the liquid droplets ejected from the spray nozzle 27 installed above collide with the liquid film portion of the spray nozzle 27 shifted downward or the spray nozzle 27 body. It can be seen that the contact efficiency between the droplet and the gas is deteriorated, and the performance of the absorbing solution to absorb SO ₂ is lowered.

  The decrease in the pressure loss is an advantage that the power of the fan that conveys the exhaust gas to the desulfurization apparatus can be reduced.However, since the desulfurization rate decreases, in order to achieve the same desulfurization performance as before the decrease in the pressure loss, It is necessary to increase the spray amount of the desulfurization liquid, that is, the power of the desulfurization liquid circulation pump is increased, which is a disadvantage.

  FIG. 7C shows the result of rearranging the power ratio based on the results shown in FIGS. 7A and 7B in order to comprehensively evaluate the influence of both. From this result, it can be seen that by changing the heights of the two adjacent spray nozzles 27, the power consumption is minimized when the difference in height between the two adjacent spray nozzles 27 is in the vicinity of 0.3d. From this, it is most effective to set the position of the spray nozzle 27 based on the present embodiment in the range of 0.2d to 0.5d with respect to the nozzle height of two conventional adjacent spray nozzles 27. I understand.

  Moreover, the Example of the arrangement | positioning aspect of the other spray nozzle 27 of this invention is shown in FIG. As a method for attaching the spray nozzle 27 to the branch spray header 39, there are attachment methods such as FIG. 6 (A), FIG. 6 (B) and FIG. 6 (C).

  6A, 6B, and 6C, the spray nozzle 27 is attached to a position on the opposite side of the branch header 39. In FIG. 6A, one spray nozzle 27 is the branch spray header 39. The other spray nozzle 27 branches through a zigzag bent connecting pipe 42 in which the droplet spraying portion at the tip is at a lower position than the branching spray header 39. Attach to spray header 39. Further, in FIG. 6B, one spray nozzle 27 is attached to the branch spray header 39 through a linear connecting pipe 42 at the same height as the branch spray header 39, and the other spray nozzle 27 has a droplet spraying portion at the tip branching. Attached to the branching spray header 39 via an L-shaped bent connecting pipe 42 at a lower height than the spray header 39. Further, in FIG. 6C, one spray nozzle 27 is attached to the branch spray header 39 via an L-shaped bent communication pipe 42 in which the droplet spraying portion at the tip is higher than the branch spray header 39, and the other spray nozzle. 27 is attached to the branch spray header 39 via an L-shaped bent connecting pipe 42 in which the liquid droplet spraying portion at the tip is positioned lower than the branch spray header 39.

  With respect to the method of attaching the spray nozzle 27 to the branch spray header 39, the same effect as described in FIG. 7 can be expected by any of the methods shown in FIGS. 6 (A), 6 (B), and 6 (C).

DESCRIPTION OF SYMBOLS 1 Boiler 2 Chimney 3 Air preheater 4 Dust collector 5 Desulfurization device 21 Coal 26 Absorption liquid circulation pump 27 Spray nozzle 28 Desulfurization absorption liquid 29 Drain line 36 Combustion air 38 Main header 39 Branch header 40 Liquid film 41 Droplet 42 Connection pipe

Claims (1)

A branch header provided with a plurality of desulfurization spray nozzles for spraying a desulfurization liquid in an exhaust gas passage provided in an absorption tower of a desulfurization apparatus, and a main header connected to the branch header are installed in a plurality of stages in the vertical direction. In flue gas treatment equipment that absorbs and removes sulfur oxides,
The spray nozzle is characterized in that the spray nozzle is installed so that the distance d between the adjacent spray nozzles in the spray nozzle provided in the branch header of each stage is 0.2 d or more and 0.5 d or less in the vertical direction. Processing equipment.

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