JP2007253032A - Gas-liquid contacting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas-liquid contacting apparatus enhancing absorption efficiency of sulfur oxides or the like and dedusting efficiency by enlarging gas-liquid contact area of treating object gas with the absorbing liquid while reducing a circulation amount of absorbing liquid thereby reducing the capacity of a circulation pump resulting in reduction in power consumption. <P>SOLUTION: A charged absorbing liquid jetting means 15 which charges the absorbing liquid while letting it flow down and drops the liquid as charged droplets, is disposed above supercooling spray nozzles 14 in a stack-integrated type absorption tower 7'. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a gas-liquid contact device for bringing a gas to be treated into contact with an absorbing liquid and processing the gas to be treated, and in particular, a degassing method for removing soot and dust in combustion exhaust gas discharged from a thermal power generation boiler. The present invention relates to a gas-liquid contact device suitable for desulfurization and the like for removing dust and sulfur oxides in the combustion exhaust gas.

In general, for example, the combustion exhaust gas discharged from a large coal-fired power generation boiler with a power generation output of 1000 MW (megawatt) class is about 3.3 million [m ³ / h] (≈ 917 [m ³ / s]). In order to detoxify such a large volume of flue gas, purified exhaust gas is discharged from the chimney to the atmosphere using a comprehensive flue gas treatment system that combines denitration, dedusting, desulfurization, gas and gas heaters, etc. Released.

  FIG. 6 is a system configuration diagram showing an example of a conventional large-scale coal-fired power generation boiler facility, in which 1 is a boiler that burns fuel such as coal and generates steam, and 2 is a combustion exhaust gas discharged from the boiler 1. A denitration apparatus 3 for removing nitrogen oxides contained in the heat exchanger 3 exchanges heat (not shown) such as combustion air supplied to the boiler 1 with combustion exhaust gas from which nitrogen oxides have been removed by the denitration apparatus 2. An air heater 4 is used to recover heat from the combustion exhaust gas whose temperature has dropped after passing through the air heater 3, and 5 is a heat recovery unit 4 for recovering heat from the air heater 3 and the gas / gas heater heat recovery unit 4. The wet-type electrostatic precipitator for collecting the soot and dust contained in the combustion exhaust gas, wherein 6 is an induction fan provided on the downstream side of the wet-type electrostatic precipitator 5, and 7 is the wet-type electrostatic precipitator 5. Invitation An absorption tower as a gas-liquid contact device for removing the soot remaining in the combustion exhaust gas sent through the machine 6 and the sulfur oxide contained in the combustion exhaust gas, 8 is an absorption tower 7, and soot and sulfur oxide are A mist separator 9 for removing mist from the removed combustion exhaust gas, 9 is a reheater of a gas / gas heater for reheating the combustion exhaust gas from which the mist has been removed by the mist separator 8 by the heat recovered by the heat recovery unit 10, 10 Is a desulfurization ventilator provided on the downstream side of the reheater 9 of the gas / gas heater, and 11 is a reheater 9 of the gas / gas heater, and releases the combustion exhaust gas pressurized by the desulfurization ventilator 10 into the atmosphere. For the chimney.

  In the conventional large coal-fired power generation boiler facility shown in FIG. 6, fuel such as coal is burned in the boiler 1 to generate steam, and the combustion exhaust gas discharged from the boiler 1 at that time is denitration device 2. In the air heater 3, the temperature of the air heater 3 is reduced by exchanging heat with air such as combustion air supplied to the boiler 1 by a forced air blower (not shown), and the heat recovery unit 4 of the gas / gas heater is used. After the heat is further recovered, the soot is collected by the wet electrostatic precipitator 5, the soot and sulfur oxide remaining in the absorption tower 7 are removed via the induction fan 6, and the mist is removed by the mist separator 8. In the reheater 9 of the gas / gas heater, it is reheated by the heat recovered by the heat recovery device 4, is pressurized by the desulfurization ventilator 10, and is discharged from the chimney 11 to the atmosphere.

  In addition, the combustion exhaust gas from which the sulfur oxide is removed by the absorption tower 7 and further the mist is removed by the mist separator 8 is discharged to a temperature of about 50 [° C.] and is saturated. If the combustion exhaust gas after desulfurization is discharged from the chimney 11 to the atmosphere as it is, white smoke is generated, and is discharged from the absorption tower 7 using a gas / gas heater comprising the heat recovery device 4 and the reheater 9. The combustion exhaust gas is reheated.

  In the conventional large coal-fired power generation boiler facilities as described above, high desulfurization / dust removal efficiency can be obtained, but in addition to the large wet electrostatic precipitator 5 and the absorption tower 7, the heat recovery device 4 and reheater 9 of the gas / gas heater are used. Etc. need to be provided separately, and an increase in cost is inevitable.

  By the way, in the case of 100 MW class business and overseas small and medium-sized coal-fired power generation boiler facilities, the restrictions on cost are particularly severe. If the heat recovery device 4 and the reheater 9 are installed, the cost increases. Therefore, in order to avoid this, for example, as shown in FIG. 7, a dry type is used instead of the wet electric dust collector 5 (see FIG. 6). An electric dust collector 5 ′ is provided, the absorption tower 7 (see FIG. 6) is a chimney-type absorption tower 7 ′, the heat recovery unit 4 of the gas / gas heater, the reheater 9, and the desulfurization ventilator 10 are eliminated. The construction of small and medium-sized coal-fired power generation boiler facilities has been carried out.

  Here, as shown in FIG. 8, the chimney-integrated absorption tower 7 ′ has a liquid reservoir 12 for absorbing liquid at the bottom, and a dust / desulfurization spray nozzle 13 and a supercooling spray nozzle at the top. 14 are arranged in a plurality of upper and lower stages (in the example of FIG. 8, the spray nozzle 13 for dedusting / desulfurization is two stages on the upper side and the spray nozzle 14 for supercooling is one stage on the lower side). The combustion exhaust gas introduced into the body-shaped absorption tower 7 ′ is supercooled by water sprayed from the supercooling spray nozzle 14, while dust and sulfur are absorbed by the absorbent sprayed from the dedusting / desulfurization spray nozzle 13. The oxide is removed and released into the atmosphere.

  As the absorption liquid, for example, a slurry containing about 20 [% wt] of limestone powder is used, and the absorption liquid in the liquid reservoir 12 is pumped up by operation of a circulation pump (not shown). It is sprayed from the spray nozzle 13 for dedusting / desulfurization and circulated.

In addition, by spraying water to supercool the flue gas, the moisture in the flue gas is condensed to promote the coagulation and enlargement of fine dust, increase the dust collection effect, and eliminate the wet electric dust collector. For example, Japanese Patent Application Laid-Open No. H10-228707 discloses a device for reducing the price of the apparatus.
JP 2002-35545 A

  However, in the conventional chimney-integrated absorption tower 7 ′ as described above, an amount of absorption liquid covering the entire range inside the absorption tower 7 ′ must be sprayed from the dust / desulfurization spray nozzle 13. It was necessary to increase the circulation pump capacity and increase the circulation pump capacity.

  Further, the mass transfer speed in the droplets of the absorbing liquid sprayed from the dust / desulfurization spray nozzle 13 is slow, and only a very small amount of the surface layer contributes to the absorption reaction, so that most of the spray amount is wasted. In addition, the power consumption of the circulation pump is increased.

  Furthermore, in order to reduce the droplet size in order to expand the gas-liquid contact area, it is necessary to increase the spray flow rate in the case of high-pressure spray. However, if the spray flow rate is increased, the spray pressure loss increases, and the circulation rate is also increased. This led to an increase in power consumption of the pump.

  On the other hand, in the case of the device described in Patent Document 1, small dust particles of several tens of [μm] or less get on the flow of combustion exhaust gas because the resistance force of air is relatively large against gravity. There is a possibility that it will not be able to fall and collect, and it has been difficult to increase the dust removal efficiency.

  In view of such circumstances, the present invention reduces the circulation amount of the absorbing liquid to reduce the circulation pump capacity, and reduces power consumption, while expanding the gas-liquid contact area between the gas to be treated and the absorbing liquid, An object of the present invention is to provide a gas-liquid contact device capable of improving the absorption efficiency of objects and dust removal efficiency.

The present invention is a gas-liquid contact device for bringing a gas to be treated into contact with an absorbing liquid and processing the gas to be treated,
The present invention relates to a gas-liquid contact device comprising charging absorbing liquid ejecting means for charging an absorbing liquid while flowing down and dropping it as charged droplets.

  According to the above means, the following operation can be obtained.

  Absorbing liquid flowing down from the charging absorbing liquid ejecting means is charged and dropped as charged droplets, and particles of soot and dust of several tens [μm] or less due to Coulomb force generated between the soot and dust contained in the gas to be treated. Also, the flocculation is enlarged and the dust is collected without falling on the flow of the gas to be treated, thereby improving the dust removal efficiency.

  Further, in the present invention, it is possible to reduce the circulation amount of the absorbing liquid and to reduce the circulation pump capacity as compared with the conventional case.

  On the other hand, since the liquid droplet contact area can be expanded by reducing the droplet diameter of the absorbing liquid, almost the entire amount of droplets contributes to the absorption reaction of sulfur oxides and the like, and most of the spray amount is wasted as before. It is avoided that the power consumption of the circulation pump increases.

  In addition, as in the case of conventional high-pressure sprays, the droplet diameter of the absorbing liquid can be reduced and the gas-liquid contact area can be expanded without increasing the spray flow rate. Can also be avoided.

In the gas-liquid contact device, the charging absorbing liquid ejecting means is
An absorbent nozzle that allows the absorbent to flow down and a high voltage to be applied;
And a ground electrode disposed directly below the absorbing liquid nozzle so as to surround the absorbing liquid flowing down from the absorbing liquid nozzle.

The absorbent nozzle is
A nozzle header that is arranged to extend in the horizontal direction, into which an absorbing liquid is introduced and to which a high voltage is applied;
The nozzle header is configured to project from the lower surface side of the nozzle header so as to be able to flow the absorbing liquid downward, and is provided with a plurality of tubular nozzles arranged at a required pitch in the longitudinal direction of the nozzle header.

The absorbent nozzle is
A nozzle header that is arranged to extend in the horizontal direction, into which an absorbing liquid is introduced and to which a high voltage is applied;
A plurality of pores that are perforated so that the absorbing liquid can flow downward from the lower surface side of the nozzle header and are arranged at a required pitch in the longitudinal direction of the nozzle header;
You may comprise from the needle inserted so that it may protrude below in this pore, and the flowing-in absorption liquid in the said nozzle header along a surface from the clearance gap between pores.

  The ground electrode can be constituted by a metal plate in which an opening through which the absorbing liquid flowing down from the absorbing liquid nozzle can pass is formed.

  The ground electrode is preferably coated with an anti-discharge coating.

  According to the gas-liquid contact device of the present invention, the circulation amount of the absorption liquid is reduced to reduce the circulation pump capacity, and the power consumption is reduced while the gas-liquid contact area between the gas to be treated and the absorption liquid is increased. An excellent effect of improving the absorption efficiency of oxides and the like and the dust removal efficiency can be obtained.

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

  1 to 3 show an example of an embodiment of the present invention. In the figure, the same reference numerals as those in FIGS. 7 and 8 denote the same parts, and the chimney-integrated absorption tower 7 '. A charging absorbing liquid ejecting means 15 for charging the absorbing liquid while flowing down and dropping it as charged droplets is disposed above the supercooling spray nozzle 14 inside.

  As shown in FIG. 2, the charging absorbing liquid ejecting means 15 includes an absorbing liquid nozzle 16 that causes the absorbing liquid to flow down and to which a DC or AC high voltage is applied, and the periphery of the absorbing liquid that flows down from the absorbing liquid nozzle 16. And a ground electrode 17 disposed immediately below the absorbing liquid nozzle 16 so as to surround.

  In the case of the illustrated example, the absorbing liquid nozzle 16 is provided with a nozzle header 18 into which the absorbing liquid is introduced so as to extend in the horizontal direction so that a high voltage is applied thereto. On the side, a plurality of narrow tubular nozzles 19 are provided so as to flow downward in the longitudinal direction of the nozzle header 18 so as to allow the absorbent to flow downward.

  The droplet diameter of the absorbing liquid flowing down from the thin tubular nozzle 19 contributes to the absorption reaction of sulfur oxide within the time until dust is collected and rides on the flow of combustion exhaust gas as the gas to be treated. However, in order to obtain the required optimum droplet diameter, the narrow tubular nozzle 19 may be used. It is effective to adopt an attachment system for the nozzle header 18 so that nozzles with different nozzle diameters can be selected as appropriate.

  The ground electrode 17 is constituted by a metal plate 21 having an opening 20 through which an absorbing liquid flowing down from a thin tubular nozzle 19 constituting the absorbing liquid nozzle 16 can pass. As the metal plate 21, for example, a punching metal or the like can be used. Further, the opening 20 formed in the metal plate 21 is not limited to a circle as shown in FIG. 2, but may be a square or a slit. Further, the ground electrode 17 is coated with Teflon (registered trademark) for preventing discharge.

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

  When the absorbing liquid in the nozzle header 18 is caused to flow down from the tubular nozzle 19 in a state where a high voltage is applied to the absorbing liquid nozzle 16 of the charging absorbing liquid ejecting means 15, As shown in FIG. 3, Maxwell stress acts in an electric field represented by an equipotential line, so that a long and stable liquid column of the absorbing solution is formed. However, after the ground electrode 17 passes, the stress does not work. Instability occurs, and fine droplets having a minus (-) charge are formed. Incidentally, for example, when an electric field of 8 [kV / cm] is applied to an absorbing liquid having a conductivity of 4 [μS / cm], a droplet of about φ0.5 [mm] is dropped by about 30 [piece / s]. The charge amount of the droplet is about 0.1 [C].

Here, as shown in FIG. 4B, in the case of an electrostatic precipitator, the dust is charged by corona discharge from the electrode 22 and is attracted to and collected by the ground dust collecting plate 23, but has the same polarity. Because of the positive charge, there is no binding between the dust, and as a result, the dust is
Those with a Coulomb force <several tens of [μm] that have an air resistance cannot be collected. On the other hand, as shown in FIG. 4A, in the case of the charging absorbing liquid ejecting means 15 in the illustrated example, + (plus) opposite to the fine absorbing liquid droplets having a minus (-) charge. The dust having the electric charge of 10 μm is attracted to the droplet of the absorbing liquid even if it is a particle of several tens [μm] or less, and is condensed and enlarged using the droplet of the absorbing liquid as a nucleus. It is possible to increase the dust removal efficiency by falling and collecting without riding on. In addition to collecting and collecting the dust that has been agglomerated and enlarged with the absorbing liquid droplets as nuclei, a dust collecting plate is further provided at a required position below the ground electrode 17 of the charging absorbing liquid ejecting means 15, It is also possible to adsorb the dust that has been agglomerated and enlarged to the dust collecting plate.

  In addition, in the chimney-integrated absorption tower 7 'of the illustrated example, for example, while one droplet falls 1 [m], dust in the range of about 0.1 [m] can be adsorbed. Since the dropping amount of the absorbing liquid is only a few [l / min], the absorbing liquid in an amount covering the entire range inside the absorption tower 7 'is removed from the absorbing nozzle 7' as in the prior art (see FIG. 8). ), The circulation rate of the absorption liquid can be reduced and the circulation pump capacity can be kept low.

  Furthermore, since the droplet diameter of the absorbing liquid can be reduced by increasing the applied voltage without forcibly reducing the nozzle diameter of the tubular nozzle 19, it is useful for preventing clogging of the tubular nozzle 19. It will be.

  On the other hand, since the liquid droplet contact area can be expanded by reducing the droplet diameter of the absorbing liquid, almost the entire amount of droplets contributes to the absorption reaction of sulfur oxides and the like, and most of the spray amount is wasted as before. It is avoided that the power consumption of the circulation pump increases.

  In addition, as in the case of conventional high-pressure sprays, the droplet diameter of the absorbing liquid can be reduced and the gas-liquid contact area can be expanded without increasing the spray flow rate. Can also be avoided.

  In this way, while reducing the circulating amount of the absorbing liquid to reduce the circulation pump capacity and reducing power consumption, the gas-liquid contact area between the combustion exhaust gas as the gas to be treated and the absorbing liquid is expanded to absorb sulfur oxides, etc. Efficiency and dust removal efficiency can be improved.

  FIG. 5 shows a modification of the charging absorbing liquid ejecting means 15 in an example of the embodiment of the present invention. The basic configuration is the same as that shown in FIG. As shown in FIG. 5, the absorbing liquid nozzle 16 of the charging absorbing liquid ejecting means 15 is disposed so as to extend in the horizontal direction, the absorbing liquid is introduced, and a high voltage is applied to the nozzle header 18. A plurality of pores 24 which are perforated so as to allow the absorbing liquid to flow downward from the lower surface side of the nozzle header 18 and are arranged at a required pitch in the longitudinal direction of the nozzle header 18, and project downward into the pores 24 The needle 25 is inserted into the nozzle header 18 so as to flow down along the surface from the gap with the pores 24.

  Even if the absorbing liquid nozzle 16 of the charging absorbing liquid ejecting means 15 is configured as shown in FIG. 5, the same effects as those of the example shown in FIG. 2 can be obtained.

  Further, in the case of the example shown in FIG. 5, in the unlikely event that the pore 24 is clogged, the clogging of the pore 24 can be eliminated by moving the needle 25 up and down. By moving it up and down, it is effective in preventing clogging of the pores 24, and stable operation can be continued.

  The gas-liquid contact device of the present invention is not limited to the illustrated example described above, and is not limited to the absorption tower as the flue gas desulfurization device, but also absorbs the refrigerant vapor as the gas to be treated in the absorption liquid. Needless to say, various modifications can be made without departing from the gist of the present invention, such as being applicable to an absorber of a refrigerator.

1 is an overall schematic diagram illustrating an example of an embodiment for carrying out the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the charge absorption liquid ejection means in an example which implements this invention, Comprising: (a) is a sectional side view, (b) is a front sectional view, (c) is a perspective view. It is a dripping part enlarged view of the charge absorption liquid ejection means in an example which embodies the present invention. It is an operation principle figure which shows the difference between the electrification absorption liquid ejecting means and the general electric dust collector in an example which carries out the present invention, and (a) is an operation principle figure of electrification absorption liquid ejection means, and (b) electricity It is an operation principle figure of a dust collector. It is a block diagram which shows the modification of the charge absorption liquid ejection means in an example which implements this invention, Comprising: (a) is a sectional side view, (b) is a front sectional view, (c) is a perspective view. It is a system block diagram which shows an example of the conventional large sized coal-fired power generation boiler equipment. It is a system block diagram which shows an example of the conventional medium and small-sized coal thermal power generation boiler equipment. It is the whole schematic figure which shows an example of the chimney-integrated absorption tower used for the conventional medium and small-sized coal-fired power generation boiler equipment.

Explanation of symbols

7 'Absorption tower (gas-liquid contact device)
14 Supercooling Spray Nozzle 15 Charged Absorbing Liquid Ejecting Means 16 Absorbing Liquid Nozzle 17 Ground Electrode 18 Nozzle Header 19 Narrow Tubular Nozzle 20 Opening 21 Metal Plate 24 Pore 25 Needle

Claims (6)

A gas-liquid contact device for bringing a gas to be treated into contact with an absorbing liquid and processing the gas to be treated,
A gas-liquid contact device comprising charging absorbing liquid ejecting means for charging an absorbing liquid while flowing down and dropping it as charged droplets. Charge absorbing liquid ejection means,
An absorbent nozzle that allows the absorbent to flow down and a high voltage to be applied;
The gas-liquid contact device according to claim 1, further comprising: a ground electrode disposed immediately below the absorption liquid nozzle so as to surround the absorption liquid flowing down from the absorption liquid nozzle. Absorbing liquid nozzle
A nozzle header that is arranged to extend in the horizontal direction, into which an absorbing liquid is introduced and to which a high voltage is applied;
The gas liquid according to claim 2, comprising a plurality of narrow nozzles protruding so as to allow the absorbing liquid to flow downward from the lower surface side of the nozzle header and disposed at a required pitch in the longitudinal direction of the nozzle header. Contact device. Absorbing liquid nozzle
A nozzle header that is arranged to extend in the horizontal direction, into which an absorbing liquid is introduced and to which a high voltage is applied;
A plurality of pores that are perforated so that the absorbing liquid can flow downward from the lower surface side of the nozzle header and are arranged at a required pitch in the longitudinal direction of the nozzle header;
The gas-liquid contact device according to claim 2, further comprising: a needle that is inserted into the pore so as to protrude downward and causes the absorbent in the nozzle header to flow down along the surface from the gap with the pore.   The gas-liquid contact device according to any one of claims 2 to 4, wherein the ground electrode is configured by a metal plate in which an opening through which the absorbing liquid flowing down from the absorbing liquid nozzle can pass is formed.   The gas-liquid contact device according to claim 5, wherein a coating for preventing discharge is applied to the ground electrode.

Images