JP2006175309A - Maintenance method of column body and maintenance device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a maintenance method of a column body capable of certainly avoiding a phenomenon that the large pressure caused by the head of a liquid is transmitted to an outlet valve, a circulating line, an inlet valve and the column body as an impact when the liquid remaining in the circulating pump positioned above the outlet valve is returned to the column body, and to provide a device therefor. <P>SOLUTION: At the time of stop of the circulating pump 5, the inlet valve 8 and outlet valve 9 of the circulating pump are once closed and a bypass line 17 for gently returning the absorbing liquid 1 remaining in the circulating line 4 to the liquid storage part 1a provided to the lower part of an absorbing tower 3 when the inlet valve 8 is opened is arranged so as to allow the outlet side and inlet side of the outlet valve 9 to communicate with each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a maintenance method and apparatus for a tower body used in an absorption tower or the like of a wet flue gas desulfurization apparatus.

In general, in a power plant or the like, a flue gas desulfurization device is provided to absorb and remove sulfur oxide (SO ₂ ) from exhaust gas discharged from a coal fired boiler or the like. There is known a wet flue gas desulfurization apparatus using a so-called lime-gypsum method in which calcium carbonate (CaCO ₃ ) is used as an absorbent and gypsum (CaSO ₄ ) is recovered.

  FIG. 2 shows an example of a wet flue gas desulfurization apparatus using a lime-gypsum method, and the wet flue gas desulfurization apparatus normally has a liquid reservoir of the absorbing liquid 1 in the lower part as shown in FIG. An absorption tower 3 as a tower body in which a portion 1a is formed and a large number of spray nozzles 2 are disposed at the top, and the absorption liquid 1 in a liquid reservoir 1a of the absorption tower 3 is pumped up to a circulation line 4 and the spray nozzle 2 And a circulating pump 5 to be circulated and an oxidized air blower 6 for supplying oxidized air to the liquid reservoir 1 a of the absorption tower 3.

In the case of the above-described wet flue gas desulfurization apparatus, the absorption liquid 1 is circulated while being sprayed from the spray nozzle 2 by the operation of the circulation pump 5, and the exhaust gas sent from the coal fired boiler or the like to the absorption tower 3 is By contacting with the absorbing liquid 1 sprayed from the nozzle 2, SO ₂ (sulfur oxide) is absorbed and removed, and then discharged to the flue 7 on the exit side of the absorption tower 3, from a chimney (not shown) to the atmosphere. To be released.

Further, the absorbing liquid 1 that has absorbed SO ₂ from the exhaust gas is dropped into the liquid reservoir 1 a and is forcibly oxidized by the oxidized air supplied into the liquid reservoir 1 a by the operation of the oxidizing air blower 6. Calcium sulfate (CaSO ₄ )) is generated, and a part of the absorbing liquid 1 in the liquid reservoir 1a containing the gypsum is extracted from an extraction line (not shown), and the gypsum is recovered. Yes.

  Incidentally, an inlet valve 8 and an outlet valve 9 are provided on the inlet side and the outlet side of the circulation pump 5 provided in the circulation line 4, and a drain line is provided in the circulation line 4 between the inlet valve 8 and the circulation pump 5. A drain line 11 having a valve 10 is branched and connected, and a drain line 13 having a drain valve 12 is also branched and connected to the outlet side of the outlet valve 9. Further, circulation between the circulation pump 5 and the outlet valve 9 is performed. A fresh water line 16 having a fresh water valve 15 is connected to the line 4.

  When performing maintenance on the circulation pump 5 or the like, in the conventional case, first, the circulation pump 5 is stopped, the inlet valve 8 and the outlet valve 9 of the circulation pump 5 are temporarily closed, and the drain valve 10 is opened. The absorbent 1 remaining in the circulation line 4 and the circulation pump 5 between the inlet valve 8 and the outlet valve 9 is discharged from the drain line 11, and the drain valve 12 is opened to be positioned above the outlet valve 9. After the absorbent 1 remaining in the circulation line 4 is discharged from the drain line 13, the fresh water valve 15 is opened to supply fresh water from the fresh water line 16, and the circulation line 4 and the circulation pump between the inlet valve 8 and the outlet valve 9 5 The inside and the drain line 11 are replaced with fresh water, then the drain valve 10 is closed, the outlet valve 9 is opened, the drain line 13 is replaced with fresh water, the drain valve 12 is further closed, and the outlet valve 9 is located above the outlet valve 9. Circulation located Flowing fresh water from line 4 to the spray nozzle 2, and performs their Shimizu substituted.

For example, Patent Document 1 shows a technical level related to the absorption tower of the above-described wet flue gas desulfurization apparatus.
JP-A-9-271632

  However, in the absorption tower 3 of the wet flue gas desulfurization apparatus as described above, the circulation line 4 is a pipe having a large diameter (for example, about φ1000 [mm]), and the outlet valve 9 is closed when the outlet valve 9 is closed. Since the capacity of the absorbent 1 remaining in the circulation line 4 located above 9 is very large, when the absorbent 1 is discharged from the drain line 13 with the drain valve 12 open, the discharged absorbent 1 There is a possibility that 1 overflows on the road around the absorption tower 3.

  In order to avoid such problems, the circulation pump 5 is stopped when maintenance of the circulation pump 5 or the like is performed, and the absorbent 1 remaining in the circulation line 4 located above the outlet valve 9 is returned to the absorption tower 3. Then, after the liquid level of the liquid reservoir 1a and the liquid level of the circulation line 4 are set to the same level, the drain valve 10 and the drain valve 12 are opened with the inlet valve 8 closed, and the remaining in the circulation line 4 It is considered that the absorbing liquid 1 to be discharged is extracted from the drain line 11 and the drain line 13 to reduce the discharge amount as drain.

  However, as described above, when maintenance of the circulation pump 5 and the like is performed, the circulation pump 5 is stopped and the absorption liquid 1 remaining in the circulation line 4 located above the outlet valve 9 is returned to the absorption tower 3. In this case, a large pressure due to the head of the absorbing liquid 1 is transmitted as an impact to the outlet valve 9, the circulation pump 5, the inlet valve 8, and the absorption tower 3, which is not preferable.

  In view of such circumstances, the present invention, when returning the liquid remaining in the circulation line located above the outlet valve to the tower body, a large pressure due to the liquid head is generated by the outlet valve, the circulation pump, the inlet valve, and the tower. It is an object of the present invention to provide a tower maintenance method and apparatus capable of reliably avoiding transmission to the body as an impact.

The present invention is a maintenance method for a tower body in which the liquid in the liquid reservoir at the lower part of the tower body is pumped and circulated by a circulation pump to a circulation line that is set up so as to connect the lower part of the tower body and the upper part of the tower body,
Stop the circulating pump, close the inlet and outlet valves of the circulating pump once, then open the inlet valve and let the liquid remaining in the circulating line pass through the bypass line that connects the outlet side and inlet side of the outlet valve. The present invention relates to a tower maintenance method characterized by gently returning to the liquid reservoir at the bottom of the tower body and then replacing the circulating line with fresh water.

In the tower maintenance method, an absorption tower of a wet flue gas desulfurization apparatus that absorbs and removes SO ₂ in the exhaust gas by circulating the tower body while pumping up and spraying the absorbing liquid from the liquid reservoir, and contacting the exhaust gas; can do.

Further, the present invention is a tower maintenance apparatus having a circulation pump for pumping and circulating the liquid in the liquid reservoir at the lower part of the tower to a circulation line that is set up so as to connect the lower part of the tower and the upper part of the tower. There,
An inlet valve provided on the inlet side of the circulation pump;
An outlet valve provided on the outlet side of the circulation pump;
When the outlet side and the inlet side of the outlet valve are in communication, and when the circulation pump is stopped, the inlet valve and outlet valve of the circulation pump are once closed and then the inlet valve is opened. The present invention relates to a tower maintenance apparatus comprising a bypass line for returning to a liquid reservoir at a lower part of the tower body.

  In the tower maintenance apparatus, the pipe diameter of the bypass line can be made small with respect to the large-diameter circulation line.

Further, in the tower maintenance apparatus, absorption of a wet flue gas desulfurization apparatus that absorbs and removes SO ₂ in the exhaust gas by circulating the tower body while pumping up the absorption liquid from the liquid reservoir and spraying the absorption liquid. Can be a tower.

  According to the tower maintenance method and apparatus of the present invention, when returning the liquid remaining in the circulation line located above the outlet valve to the tower body, a large pressure due to the liquid head is generated by the outlet valve, the circulation pump, and the inlet. The valve and the tower body can be effectively prevented from being transmitted as an impact.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows an example of an embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 2 denote the same components, and the basic configuration is the same as that of the conventional one shown in FIG. However, as shown in FIG. 1, when the circulating pump 5 is stopped, the inlet valve 8 and the outlet valve 9 of the circulating pump 5 are once closed and then the inlet valve 8 is opened as shown in FIG. At this time, a bypass line 17 for gently returning the absorbent 1 remaining in the circulation line 4 to the liquid reservoir 1a at the lower part of the absorption tower 3 is disposed so that the outlet side and the inlet side of the outlet valve 9 communicate with each other. In the point.

  The bypass line 17 has a small diameter (for example, about φ50 [mm]) with respect to the circulation line 4 having a large diameter (for example, about φ1000 [mm]).

  Next, the operation of the illustrated example will be described.

  When performing maintenance of the circulation pump 5 or the like, in the case of the illustrated example, first, the circulation pump 5 is stopped, the inlet valve 8 and the outlet valve 9 of the circulation pump 5 are once closed, and the inlet valve 8 is opened. The absorbent 1 remaining in the circulation line 4 located above the outlet valve 9 is gently returned to the liquid reservoir 1a at the lower part of the absorption tower 3 via the small-diameter bypass line 17, and the liquid in the liquid reservoir 1a After the surface level and the liquid level of the circulation line 4 become the same level, the inlet valve 8 and the outlet valve 9 are closed, the drain valve 10 is opened, and the circulation line between the inlet valve 8 and the outlet valve 9 is opened. 4 and the absorption liquid 1 remaining in the circulation pump 5 is discharged from the drain line 11, the drain valve 12 is opened, and the absorption liquid 1 remaining in the circulation line 4 located above the outlet valve 9 is discharged from the drain line 13. While discharging, open the Shimizu valve 15 to Fresh water is supplied from the inlet 16 and the fresh water replacement of the circulation line 4 between the inlet valve 8 and the outlet valve 9, the inside of the circulation pump 5, the drain line 11, the bypass line 17, and the drain line 13 is performed. The valve 10 and the drain valve 12 are closed, the outlet valve 9 is opened, fresh water is allowed to flow from the circulation line 4 located above the outlet valve 9 to the spray nozzle 2, and the fresh water is replaced.

  As a result, by providing the bypass line 17, when the absorbent 1 remaining in the circulation line 4 located above the outlet valve 9 is returned to the absorption tower 3, a large pressure due to the head of the absorbent 1 is It is not transmitted as an impact to the outlet valve 9, the circulation pump 5, the inlet valve 8, and the absorption tower 3.

  Further, since the pipe diameter of the bypass line 17 is smaller than that of the large-diameter circulation line 4, there is a problem when the circulation pump 5 is driven and the absorbent 1 is circulated through the circulation line 4 during normal operation. No worries.

  Thus, when the absorption liquid 1 remaining in the circulation line 4 located above the outlet valve 9 is returned to the absorption tower 3, a large pressure due to the head of the absorption liquid 1 causes the outlet valve 9, the circulation pump 5, the inlet valve 8, In addition, it is possible to reliably avoid the transmission to the absorption tower 3 as an impact.

  In addition, the maintenance method and apparatus of the tower body of the present invention are not limited to the above-described illustrated examples, but are not limited to the absorption tower of the wet flue gas desulfurization apparatus, and any type can be used as long as the liquid is circulated. Needless to say, various modifications can be made without departing from the scope of the present invention, such as being applicable to a tower body.

It is a schematic block diagram which shows an example of the form which implements this invention. It is a schematic block diagram which shows an example of the conventional wet flue gas desulfurization apparatus.

Explanation of symbols

1 Absorbing liquid (liquid)
1a Liquid reservoir 3 Absorption tower (tower)
4 Circulation line 5 Circulation pump 8 Inlet valve 9 Outlet valve 17 Bypass line

Claims (5)

A maintenance method for a tower body in which the liquid in the liquid reservoir at the lower part of the tower body is pumped and circulated by a circulation pump to a circulation line that is set up so as to connect the lower part of the tower body and the upper part of the tower body,
Stop the circulating pump, close the inlet and outlet valves of the circulating pump once, then open the inlet valve and let the liquid remaining in the circulating line pass through the bypass line that connects the outlet side and inlet side of the outlet valve. A maintenance method for a tower, wherein the circulation line is replaced with fresh water after slowly returning to the liquid reservoir at the bottom of the tower. _2. The tower body according to claim 1, wherein the tower body is an absorption tower of a wet flue gas desulfurization apparatus that absorbs and removes SO ₂ in the exhaust gas by circulating the absorption liquid from the liquid reservoir while spraying it and bringing it into contact with the exhaust gas. Maintenance method. A tower maintenance device having a circulation pump for pumping and circulating the liquid in the liquid reservoir at the lower part of the tower to a circulation line that is raised so as to connect the lower part of the tower and the upper part of the tower,
An inlet valve provided on the inlet side of the circulation pump;
An outlet valve provided on the outlet side of the circulation pump;
When the outlet side and the inlet side of the outlet valve are in communication, and when the circulation pump is stopped, the inlet valve and outlet valve of the circulation pump are once closed and then the inlet valve is opened. A tower maintenance apparatus comprising: a bypass line for returning to a liquid reservoir at a lower part of the tower body.   The tower maintenance apparatus according to claim 3, wherein the diameter of the bypass line is smaller than that of the large-diameter circulation line. The tower according to claim 3 or 4, wherein the tower body is an absorption tower of a wet flue gas desulfurization device that absorbs and removes SO ₂ in the exhaust gas by circulating the absorption liquid from the liquid reservoir while spraying it and bringing it into contact with the exhaust gas. Body maintenance device.

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