JP6740185B2 - Exhaust gas desulfurization method in pressurized fluidized-bed reactor system and pressurized fluidized-bed reactor system - Google Patents

Description

The present invention relates to an exhaust gas desulfurization method and a pressurized fluidized flow reactor system. The present invention relates to an exhaust gas desulfurization method and a pressurized fluidized-bed reactor system in a pressurized fluidized-bed reactor system that burns substances to be treated such as sewage sludge, biomass, and municipal waste.

Conventionally, a pressurized fluidized bed reactor system has been known as an incinerator that focuses on effectively extracting the energy of combustion exhaust gas discharged from an incinerator by burning an object to be treated such as sewage sludge, biomass, and municipal waste. There is. The pressurized fluidized-bed furnace system includes a pressurized fluidized-bed furnace that combusts an object to be processed while flowing it with combustion air, and a turbine that is rotated by combustion exhaust gas discharged from the pressurized fluidized furnace and the turbine that rotates with the rotation of the turbine. A system comprising a supercharger having a compressor driven to supply compressed air.

In a pressurized fluidized bed reactor system, the combustion exhaust gas generated when the material to be processed is completely combusted drives the turbine of the supercharger, and the compressed air discharged from the compressor provides the combustion air necessary for combustion of the material to be processed. It becomes possible to operate independently to cover all costs. It is known that by enabling self-sustaining operation, a flow blower and an induction fan, which have been required in the past, are not required and running costs are reduced.

When sewage sludge containing sulfur is incinerated, the residue contains sulfur oxides. This sulfur oxide can be a problem as equipment corrosion and purple smoke at the smoke outlet.

For this reason, in general, in the case of a sludge incinerator of a certain scale or more, a flue gas treatment device (for example, a wet desulfurization treatment tower) is installed, and sulfur oxides are removed as ammonium sulfite in the flue gas treatment device.
However, some of the sulfur oxides may become mist and become difficult to be captured, and may flow into the stack. Therefore, an electric dust collector is required before the chimney.

The most main method for efficient removal of sulfur oxides is to add ammonia injection equipment and inject ammonia into the exhaust gas duct to forcibly increase the conversion rate to ammonium sulfate and capture with dry EP. is there. There are also methods of “capture by dry EP+wet EP” and “capture by dissolved salt spray+wet EP”.

JP-A-11-151424 JP-A-9-103629 JP, 2006-326575, A

"Ammonia injection + dry EP method" (Patent Document 1)
The efficiency of removing the sulfur content is almost 100%, but ammonium sulfate produced by injecting ammonia is highly adherent and adherent, and therefore adheres to the electrode inside the EP to reduce the discharge current. As the discharge current decreases, the EP collection performance also decreases. Therefore, there is a possibility that the long-term stable operation of the equipment may be hindered.

"Wet EP method" (Patent Document 2)
Since the wet EP is installed at the outlet of the flue gas treatment apparatus to collect the sulfur, the sulfur content cooled in the flue gas treatment apparatus becomes mist. If a fine mist exists in the discharge space, a phenomenon called a space charge effect that hinders the flow of current occurs, and the EP collection performance deteriorates.

"Dissolved salt spray method" (Patent Document 3)
This is a method of spraying the dissolved salt into the inside of the duct to attach the sulfur oxide to the dust deposited after drying the dissolved salt droplets. The most effective temperature for the adhesion is “around 145° C.” (exit temperature after spraying: 130° C. or higher), which is in the dew point temperature range of ammonium sulfate. Therefore, there is concern about low-temperature corrosion of equipment.
Further, since the optimum temperature range is around 145° C., some of the dissolved salt may adhere to the inner wall of the duct, hindering stable continuous operation, and measures must be taken.

On the other hand, the inventors of the present invention, for example, when incinerating sewage sludge in a pressurized fluidized bed reactor system, the formation of sulfur oxides poses a problem. Therefore, for example, desulfurization treatment with sodium hydroxide is performed in a wet desulfurization treatment tower. Have found that it is effective.
However, although SO ₂ can be sufficiently treated, the operating conditions, it has been found the process of SO ₃ is not sufficient.
It can be inferred that this cause is caused by the pressurized fluidized incinerator operated at about 100 to 160 kPa·G, unlike the conventional bubble type fluidized bed furnace operated at almost normal pressure. ..

Therefore, the main object of the present invention is to provide an exhaust gas desulfurization method in a pressurized fluidized reactor system, which requires a low equipment cost for SO ₃ removal and is capable of appropriately removing sulfur oxides (especially SO ₃ ) in exhaust gas. And to provide a pressurized flow furnace system.

MEANS TO SOLVE THE PROBLEM This invention which solved the said subject is as follows.
That is, the exhaust gas desulfurization method in the pressure fluidized reactor system of the present invention,
Pressure fluidized furnace,
A supercharger including a turbine that is rotated by combustion exhaust gas discharged from the pressurized fluidized furnace, and a compressor that is rotated with rotation of the turbine and that supplies combustion air to the pressurized fluidized furnace.
In a pressure fluidized furnace system equipped with
Regarding the combustion exhaust gas that has passed through the turbine of the supercharger, wet desulfurization is attempted by using a smoke treatment device with sodium hydroxide as a desulfurizing agent, and the gas after desulfurization treatment is released to the atmosphere through a chimney,
While spraying the sodium hydroxide solution with a spray nozzle to the combustion exhaust gas at 300° C. to 550° C. in the combustion exhaust gas post-path between the turbine and the flue gas treatment device,
The combustion exhaust gas discharged from the pressurized fluidized furnace is not provided with an electric precipitator in the path until it is discharged to the atmosphere through the chimney,
It is characterized by that.

As described above, in the pressurized fluidized reactor system, the combustion exhaust gas generated when the material to be processed is completely burned drives the turbine of the supercharger, and the compressed air discharged from the compressor is used to burn the material to be processed. Independent operation that covers all required combustion air becomes possible. By enabling the self-sustaining operation, the flow blower and the induction fan, which were required in the past, are not required, and the running cost is reduced. The Applicant has demonstrated that it brings many other advantages, and has been highly evaluated.
On the other hand, there are various methods for desulfurizing combustion exhaust gas, but so-called sulfurous acid method and sodium sulfate method using NaOH are widely used in a flue gas treatment device (for example, a wet desulfurization treatment tower). The reaction is as follows.
Na ₂ SO ₃ +SO ₂ +H ₂ O → 2NaHSO ₃ (1)
NaHSO ₃ +NaOH → Na ₂ SO ₃ +H ₂ O (2)
Na ₂ SO ₃ +1/2O ₂ → Na ₂ SO ₄ (3)
However, in the sulfurous acid method or the sodium sulfate method, SO ₃ is not sufficiently removed, and in order to remove SO ₃ , it is necessary to introduce an expensive and large-sized electrostatic precipitator before the chimney, as described above. , Installation of such equipment should be avoided as much as possible.
However, in the pressurized fluidized flow system, the high temperature of about 300° C. to 550° C. is high in the rear path of the combustion exhaust gas between the turbine and the flue gas treatment device, and sodium hydroxide (NaOH) is added to this high temperature exhaust gas. It was found that spraying the liquid has a high reaction efficiency and has no substantial effect on the desulfurization efficiency in the flue gas treatment device.
Thus, according to the present invention, basically, it suffices to install the spray nozzle in the rear path of the combustion exhaust gas (no introduction of an electric dust collector or other large-sized equipment), which is excellent in economical efficiency and It exhibits a practically sufficient SO ₃ removal effect.

The pressure fluidized furnace is operated at a pressure of 100 to 160 kPa·G, and the pressure of the combustion exhaust gas post-path between the turbine and the flue gas treatment device exceeds 0 kPa·G, preferably exceeds 3 and 5 kPa. -It can be G or less.
By such conditions, the effect of the pressurized fluidized flow reactor system is remarkably exhibited.

During the wet desulfurization, desulfurization can be achieved with a wet scrubber.
Desulfurization with a wet scrubber increases desulfurization efficiency.

In the middle of the combustion exhaust gas rear path between the turbine and the flue gas treatment device, a white smoke prevention heat exchanger for preventing white smoke from the chimney is provided,
The white smoke prevention heat exchanger is a shell and tube type installed vertically,
Sodium hydroxide liquid can be sprayed by a spray nozzle in the middle of the route after the combustion exhaust gas.

White smoke can be prevented by providing a white smoke prevention heat exchanger. As this white smoke prevention heat exchanger, it is preferable to use a shell-and-tube heat exchanger having high heat exchange efficiency.
In addition, since sodium hydroxide solution is sprayed from the spray nozzle in the post-combustion exhaust gas passage, mixing with the exhaust gas can be performed sufficiently uniformly, evaporation is fast, salt precipitation speed is also high, and smoke exhaust This is a route prior to the treatment device, and as a result, it becomes possible to secure the reaction time, and the sulfur oxide removal efficiency is improved.
In this way, due to the improved removal efficiency, at least one spray (injection) nozzle is sufficient, and large equipment such as the conventional dissolved salt spray method is unnecessary. Further, since the spraying is performed at a high temperature, the precipitated salt particle size can be increased, the spraying can be performed at a low pressure, and the equipment cost required for a high pressure can be suppressed.
The shell-and-tube heat exchanger is installed vertically because the adhesion to the tube sheet and the tube side is suppressed and the maintenance is easy.

In the middle of the combustion exhaust gas rear path between the turbine and the flue gas treatment device, a white smoke prevention heat exchanger for preventing white smoke from the chimney is provided, and the turbine and the white smoke prevention heat exchanger are provided. In the meantime, it is also possible to spray the sodium hydroxide solution with a spray nozzle.

Further, the sodium hydroxide solution can be sprayed by the spray nozzle between the white smoke prevention heat exchanger and the smoke exhaust treatment device.

On the other hand, if the spray nozzle is provided so that its injection direction is toward the downstream side of the combustion exhaust gas rear passage, the flow of the sodium hydroxide liquid and the exhaust gas will be the same, so there will be no adhesion of particles in the flow path. , Becomes highly reactive.
On the other hand, for example, when the spraying direction of the spray nozzle intersects with the flow of the exhaust gas, particles may be attached to the flow channel, which may eventually cause the flow channel to be blocked.

In particular, in the descending path of the combustion exhaust gas rear path, it is desirable that the spray nozzle is provided so that the injection direction thereof is toward the downstream side of the descending path.
In the descending path, if the injection direction is set to the downstream side, in other words, the injection direction is set to the downward direction, even if the particles try to adhere to the inner wall of the pipeline, they will flow downward due to the action of gravity. Therefore, the adhesion to the inner wall of the pipeline is suppressed.

The exhaust gas desulfurization method in a pressurized fluidized reactor system according to claim 4 or 5, wherein the spray liquid from the spray nozzle has a Sauter particle size of 30 to 150 µm.
The spray liquid preferably has a Sauter particle size of 30 to 150 μm. In some cases, even if the Sauter particle size is large in the range of more than 100 μm to 150 μm, sufficient reaction efficiency is exhibited.

The pressurized fluidized flow reactor system according to the embodiment of the present invention is
A supercharger including a pressurized fluidized furnace, a turbine that is rotated by combustion exhaust gas discharged from the pressurized fluidized furnace, and a compressor that is rotated with the rotation of the turbine and that supplies combustion air to the pressurized fluidized furnace. A pressure fluidized furnace system having a machine,
Regarding the combustion exhaust gas passing through the turbine of the supercharger, a flue gas treatment device for performing wet desulfurization using sodium hydroxide as a desulfurizing agent,
A chimney that emits gas after flue gas treatment to the atmosphere,
A spray nozzle for spraying sodium hydroxide solution, which is provided at a position where the temperature of the combustion exhaust gas in the post-combustion exhaust gas passage between the turbine and the smoke exhaust treatment device is 300°C to 550°C,
Have
Combustion exhaust gas discharged from the pressurized fluidized furnace, the electrostatic precipitator is not installed in the path until it is discharged to the atmosphere through the chimney,
It is characterized by

In the middle of the combustion exhaust gas rear path between the turbine and the flue gas treatment device, a white smoke prevention heat exchanger for preventing white smoke from the chimney is provided,
The white smoke prevention heat exchanger is a shell and tube type installed vertically,
It is possible to provide a pressurized fluidized flow reactor system in which the spray nozzle is provided so that the injection direction is toward the downstream side of the post-combustion exhaust gas passage.

According to the present invention, the facility cost for removing SO ₃ is inexpensive, and the sulfur oxides (particularly SO ₃ ) in the exhaust gas can be removed properly.

It is explanatory drawing of the pressurization flow furnace system which concerns on this invention. It is a schematic explanatory drawing of the structural example of a wet wall. It is a 3-3 line arrow line view.

Hereinafter, this embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the pressurized fluidized-bed furnace system 1 stores a treatment object M (for example, dehydrated cake of sewage sludge) and a storage device 10 that burns the treatment object M supplied from the storage device 10. A pressure fluidizing furnace 20, an air preheater 40 that heats the combustion air supplied to the pressure fluidizing furnace 20 by the combustion exhaust gas discharged from the pressure fluidizing furnace 20, a dust collector 50 that removes dust and the like in the combustion exhaust gas, A supercharger 60 that is driven by the combustion exhaust gas to supply combustion air to the pressurized fluidized furnace 20, and white smoke prevention air that is supplied after the smoke exhaust treatment device (tower) 80 by the combustion exhaust gas discharged from the supercharger 60. A white smoke prevention heat exchanger 70 that heats the exhaust gas and a smoke exhaust treatment device 80 that removes impurities (sulfur oxides) in the combustion exhaust gas are provided.

(Storage device)
The material to be processed stored in the storage device 10 is, for example, sewage sludge that has been dehydrated to a water content of 70 to 85% by mass, and the material to be processed contains combustible organic matter. The material to be treated is not limited to sewage sludge as long as it is a water-containing organic matter, and may be biomass, municipal waste, or the like.

A fixed amount feeder (supply device) 11 for supplying a predetermined amount of the object to be processed to the pressurization flow furnace 20 is arranged below the storage device 10, and the object to be processed is pressurized and flowed on the downstream side of the constant amount feeder 11. A charging pump (not shown) that pressure-feeds the furnace 20 is provided. In addition, a uniaxial screw type pump, a piston pump or the like can be used as the charging pump.

(Pressure flow furnace)
The pressurized fluidized furnace 20 is a combustion furnace in which solid particles such as fluidized sand having a predetermined particle size as a fluidized medium are filled in the lower portion of the furnace, and the fluidized bed is fluidized by the combustion air supplied into the furnace. While maintaining the state, the object to be processed supplied from the outside and the auxiliary fuel supplied as necessary are burned.
An auxiliary fuel combustor (not shown) for heating the fluidized sand having a particle size of about 400 to 600 μm filled in the pressurized fluidized furnace 20 is disposed at the lower part of the one side wall. A starter burner (not shown) that heats the fluidized sand at the time of start-up is arranged in a region near the upper side, and a supply port 13B for the object to be processed is provided in a region above the starter burner.
Further, below the pressurized fluidized furnace 20, a combustion air supply pipe 24 is installed to supply combustion air that provides oxygen required for combustion and kinetic energy for maintaining a fluidized state of a fluidized bed in the furnace. .. As the combustion air supply pipe 24, it is possible to use a dispersion pipe in which a plurality of pipes having a plurality of openings are arranged, or a dispersion plate in which a plurality of openings are provided in a plate-shaped iron plate or the like.
The pressure fluidized furnace operates at a pressure of 100 to 160 kPa·G, and the pressure in the post-combustion exhaust gas path between the turbine 61 and the smoke treatment device 80 exceeds 0 kPa·G, preferably exceeds 3 and 5 kPa·G. It can be:

(Air preheater)
The air preheater 40 is installed in the latter stage of the pressurized fluidized furnace 20 and indirectly communicates the combustion exhaust gas (combustion gas or a gas in which combustion gas and steam are mixed) and the combustion air discharged from the pressurized fluidized furnace 20. It is a device that heats the combustion air to a predetermined temperature by exchanging heat.
Combustion air from the air preheater 40 is connected to the combustion air supply pipe 24 of the pressurized fluidized furnace 20 via a pipe (flow path) 91.

An exhaust port 92A for exhausting the combustion exhaust gas from the air preheater 40 is formed in the lower part of the other side of the air preheater 40. A shell-and-tube heat exchanger is preferable as the air preheater.

(Dust collector)
The dust collector 50 is provided in a stage subsequent to the air preheater 40, and is a device that removes impurities such as dust and finely granulated fluidized sand contained in the combustion exhaust gas sent from the air preheater 40.
As the filter incorporated in the dust collector 50, for example, a ceramic filter or a bag filter can be used, and the dust collector 50 has a supply port 92B for supplying combustion exhaust gas into the device at the lower part of the side wall on one side. An exhaust port 93A for exhausting clean combustion exhaust gas from which impurities and the like have been removed is formed in the upper part. Further, the combustion exhaust gas supply port 92B is connected to a combustion exhaust gas discharge port 92A of the air preheater 40 via a pipe 92.

Inside the dust collector 50, a bag filter (not shown) is installed at a portion between the supply port 92B formed in the lower part and the discharge port 93A formed in the upper part in the up-down direction. Impurities IM and the like in the combustion exhaust gas removed by the filter are temporarily stored at the bottom of the dust collector 50 and then periodically discharged to the outside.

(Supercharger)
The supercharger 60 is provided in the subsequent stage of the dust collector 50, and is rotated by the turbine 61 that is rotated by the combustion exhaust gas sent from the dust collector 50, the shaft 63 that transmits the rotation of the turbine 61, and the shaft 63. Is transmitted to the compressor 62 to generate compressed air. The generated compressed air is supplied as combustion air to the pressurized fluidized furnace 20 via the air preheater 40.

The compressor 62 of the supercharger 60 is formed with an intake port for inhaling air into the device, and has an exhaust port for exhausting compressed air obtained by pressurizing the inhaled air A to 0.05 to 0.3 MPa to the outside of the device. Has been formed. It is also connected to a startup blower (not shown) that supplies combustion air to the pressurized fluidized furnace 20 at the time of startup. The compressed air discharge port is connected to the air preheater 40 via a pipe (flow path) 94.

(White smoke prevention heat exchanger)
The white smoke prevention heat exchanger 70 supplies the combustion exhaust gas discharged from the turbine 61 of the supercharger 60 and the white smoke prevention blower 71 in order to prevent white smoke of the combustion exhaust gas discharged from the chimney 87 to the outside. It is a device that indirectly exchanges heat with the white smoke prevention air. By the heat exchange process, the combustion exhaust gas is cooled and the white smoke prevention air is heated. The combustion exhaust gas, which has been heat-exchanged and cooled by the white smoke prevention heat exchanger 70, is sent to the flue gas treatment device 80 in the subsequent stage. A shell-and-tube heat exchanger, a plate heat exchanger, or the like can be used as the white smoke prevention heat exchanger 70, but the shell-and-tube heat exchanger is most suitable. In the chimney 87, warmed and dried white smoke prevention air is mixed at the outlet 99B with the combustion exhaust gas at the outlet, which tends to be wet and condensed in the air to form a mist, thereby reducing the relative humidity of the combustion exhaust gas. This will prevent white smoke.

(Smoke exhaust treatment device)
The flue gas treatment device 80 is a device that prevents the discharge of impurities and the like contained in the combustion exhaust gas outside the device 80, and is discharged from the discharge port 98A of the white smoke prevention heat exchanger 70 at the lower part of the side wall on one side. A supply port 98B for supplying the combustion exhaust gas into the smoke exhaust treatment device 80 is formed.

A spray pipe (not shown) for spraying water supplied from the outside into the equipment is arranged on the upper part of the other side wall of the smoke treatment device 80, and a circulation pump is provided on the middle part and the lower part, respectively. A spray pipe 85 for spraying sodium hydroxide water containing sodium hydroxide stored in the bottom portion of the flue gas treatment device 80 via 83 is arranged. Further, the sodium hydroxide water stored in the flue gas treatment device 80 is supplied from a sodium hydroxide tank (not shown) via a sodium hydroxide pump (not shown) and is always maintained at an appropriate amount.

Impurities (mainly sulfur oxides) are removed from the combustion exhaust gas supplied to the smoke emission processing device 80, and the processed gas 99A is mixed with white smoke prevention air 72 supplied from the white smoke prevention blower 71. , Is discharged from the chimney 87 to the outside.

Now, in the present invention, the sodium hydroxide solution is sprayed by the spray nozzle N on any one or a plurality of locations of the rear paths 41, 42 of the combustion exhaust gas between the turbine 61 and the smoke treatment apparatus 80.

In FIG. 1, the X1 position between the turbine 61 and the white smoke prevention heat exchanger 70, the X3 position between the white smoke prevention heat exchanger 7 and the smoke exhaust treatment device 80, and the smoke exhaust treatment device 80. An example in which a spray nozzle N is provided at each of the X5 positions inside the is representatively shown.
The illustrated white smoke prevention heat exchanger 70 is of a shell-and-tube type installed vertically, and has an upper header 70U and a lower header 70D.
The structure of the spray nozzle N is not limited, but a two-fluid spray nozzle is most suitable.

The installation position of the spray nozzle N of the sodium hydroxide solution is, as indicated by the symbol X1, an inlet side path 41 of the white smoke prevention heat exchanger 70 of about 400° C. to 550° C., about 300° C. to 450° C. It may be the outlet portion of the white smoke prevention heat exchanger 70 indicated by reference numeral X2, or the outlet side path 42 of the white smoke prevention heat exchanger 70 indicated by X3 and reference numeral X4.
The spray nozzle N preferably sprays toward the downstream side of the flow of the combustion exhaust gas. This outline is shown in a partially enlarged view of reference numerals X1 and X3.

Further, providing the spray nozzle N at the outlet of the white smoke prevention heat exchanger 70 has the following advantages.
Since the sodium hydroxide solution is sprayed from the spray nozzle N to the upper header above the tube plate of the white smoke prevention heat exchanger 70, the mixing with the exhaust gas can be performed sufficiently uniformly, and the evaporation is fast, The salt precipitation rate is increased, and the distance from the smoke treatment apparatus 80 is not short (sufficiently long), and as a result, the reaction time can be lengthened and the sulfur oxide removal efficiency is improved.
Particularly preferably, as shown in the drawing, the discharge passage is provided substantially horizontally so as to communicate with the upper header above the tube sheet, and the injection direction is the opposite side of the upper header facing the discharge passage. When the spray nozzle N is provided toward the discharge passage, the sodium hydroxide solution and the exhaust gas flow in the same flow, so that particles do not adhere to the flow passage and the reactivity becomes high.

The combustion exhaust gas discharged from the discharge port 98A of the white smoke prevention heat exchanger 70 descends in the outlet path 42 of the white smoke prevention heat exchanger 70 reaching the supply port 98B of the smoke emission processing device 80. It is particularly preferable to provide the spray nozzle N on the path 42a. As described above, in the descending path 42a, if the injection direction is provided to the downstream side, in other words, provided so as to be directed downward, even if the particles try to adhere to the inner wall of the pipe line, the downward movement is caused by the action of gravity. Since it will flow down to the inner wall of the pipe, it will be prevented from adhering to the inner wall of the pipe.
Here, the descending path 42a is included in the "descending path" because the injection direction is downward even at the position of the symbol X3.

In the descending path, for example, in the descending path 42a, it is desirable to configure a wetting wall as shown in FIGS. 2 and 3 in order to prevent adhesion of particles. Illustrated example, forms a triangular weir 43 in the path 42a, supplies such as water W supplied from the outside, is an aspect which constitutes the wall wet path 42a inner surface flowed Yue a triangular weir 43.

In the flue gas treatment device 80, sodium hydroxide water for flue gas treatment is circulated and sprayed. The spray nozzle for this purpose is not a two-fluid spray nozzle, and the effect of removing SO ₃ is not high. Therefore, separately from the circulating sodium hydroxide water, the sodium hydroxide liquid can be sprayed by the two-fluid spray nozzle N at the position of the symbol X5 to improve the contact efficiency.

On the other hand, as the flue gas treatment device according to the present invention, known devices can be used, for example, those having a structure described in various drawings of "Environmental Process Engineering" Maki Shoten 1976, 224 to 225 pages can be used.

The operation and effect of the above-described embodiment has already been described in the section of the operation and effect of the present invention, and thus duplicated description will be omitted.

(Examples and comparative examples)
In the flow shown in FIG. 1, in the case where the sodium hydroxide solution is not sprayed by the spray nozzle in the combustion exhaust gas rear path between the turbine and the smoke treatment apparatus (comparative example), the sodium hydroxide solution is sprayed by the spray nozzle. When the position to be sprayed is between the turbine and the white smoke prevention heat exchanger (position X1) (Example 1), the amount of spray is between the white smoke prevention heat exchanger and smoke treatment device (position X3). Is 350 (L/Hr) (Example 2), the spray amount is 300 (L/Hr) between the white smoke prevention heat exchanger and the flue gas treatment device (position X3) (Example). Regarding 3), the dust concentration was measured by the cylindrical filter paper method specified in JIS Z 8808. The results are shown in Table 1. The dust concentration is shown as a relative value in Examples 1 to 3 when the comparative example is "1".

It can be seen from Table 1 that the dust concentration can be significantly reduced by spraying the sodium hydroxide solution with the spray nozzle.
In particular, it can be seen that the reduction effect is remarkable when it is between the turbine and the white smoke prevention heat exchanger (Example 1).
From this, it is considered that the effect is higher when the arrival time to the white smoke prevention heat exchanger is longer (the distance to the white smoke prevention heat exchanger is longer) before the white smoke prevention heat exchanger. It is speculated that the reason is that the temperature of the exhaust gas is high and the evaporation time is short, and the distance to the flue gas treatment device is long and the reaction time is sufficient. Further, spraying in a place where the exhaust gas temperature is high also has the effect of shortening the evaporation time and suppressing adhesion.

On the other hand, the gas flow velocity at the spraying position in Examples 1 to 3 is about 10 to 15 m/sec, and the arrival time from the spraying position to the flue gas treatment device is that of Example 1 (exhaust gas temperature is generally 400 to 550° C. ) In about 2.2 seconds, and in Examples 2 and 3 (exhaust gas temperature is higher than the temperature from the spray position to the flue gas treatment device, generally 300 to 450°C) in about 0.7 seconds. there were. Including this, referring to other experimental examples, it was found that the gas arrival time from the spray position to the smoke treatment device is 1.0 second or more, and more preferably 1.5 seconds or more.

20 pressurized flow furnace 40 air preheater 42 exit side path 42a descending path
50 Dust collector 60 Supercharger 61 Turbine 62 Compressor 70 White smoke prevention heat exchanger 70D Lower header 80 Smoke exhaust treatment device N Spray nozzle

Claims (12)

Pressure fluidized furnace,
A supercharger including a turbine that is rotated by combustion exhaust gas discharged from the pressurized fluidized furnace, and a compressor that is rotated with rotation of the turbine and that supplies combustion air to the pressurized fluidized furnace.
In a pressure fluidized furnace system equipped with
Regarding the combustion exhaust gas that has passed through the turbine of the supercharger, wet desulfurization is attempted by using a smoke treatment device with sodium hydroxide as a desulfurizing agent, and the gas after desulfurization treatment is released to the atmosphere through a chimney,
While spraying the sodium hydroxide solution with a spray nozzle to the combustion exhaust gas at 300° C. to 550° C. in the combustion exhaust gas post-path between the turbine and the flue gas treatment device,
In the descending path in the post-combustion exhaust gas path, an overflow port forms a triangular weir, and water supplied from the outside is supplied, and the triangular weir overflows and flows into the descending path. A wet wall is formed on the inner surface of the route,
The combustion exhaust gas discharged from the pressurized fluidized furnace is not provided with an electric precipitator in the path until it is discharged to the atmosphere through the chimney,
An exhaust gas desulfurization method in a pressurized fluidized reactor system, which is characterized in that The pressure fluidized furnace is operated at a pressure of 100 to 160 kPa·G, and the pressure in the post-combustion exhaust gas path between the turbine and the flue gas treatment device is more than 0 kPa·G and 5 kPa·G or less. An exhaust gas desulfurization method in the pressurized fluidized flow reactor system described. The exhaust gas desulfurization method in a pressurized fluidized reactor system according to claim 1, wherein desulfurization is performed by a wet scrubber during the wet desulfurization. In the middle of the combustion exhaust gas rear path between the turbine and the flue gas treatment device, a white smoke prevention heat exchanger for preventing white smoke from the chimney is provided,
The white smoke prevention heat exchanger is a shell and tube type installed vertically,
The exhaust gas desulfurization method in a pressurized fluidized reactor system according to claim 1, wherein the sodium hydroxide solution is sprayed by a spray nozzle in the middle of the post-combustion exhaust gas passage. In the middle of the combustion exhaust gas rear path between the turbine and the flue gas treatment device, a white smoke prevention heat exchanger for preventing white smoke from the chimney is provided, and the turbine and the white smoke prevention heat exchanger are provided. The exhaust gas desulfurization method in the pressurized fluidized reactor system according to claim 1, wherein the sodium hydroxide liquid is sprayed by the spray nozzle during the period. A white smoke prevention heat exchanger for preventing white smoke from the chimney is provided in the middle of the combustion exhaust gas rear path between the turbine and the smoke exhaust treatment device, and the white smoke prevention heat exchanger and the smoke exhaust are provided. The exhaust gas desulfurization method in a pressurized fluidized-furnace system according to claim 1, wherein the sodium hydroxide liquid is sprayed from the treatment device by a spray nozzle. The exhaust gas desulfurization method in a pressurized fluidized reactor system according to claim 1, 4 or 5, wherein the spray nozzle is provided so that its injection direction is directed toward the downstream side of the post-combustion exhaust gas passage. The exhaust gas desulfurization method in a pressurized fluidized reactor system according to claim 7, wherein the spray nozzle is provided in a descending path of the combustion exhaust gas rear path so that an injection direction thereof is directed to a downstream side of the descending path. The exhaust gas desulfurization method in a pressurized fluidized reactor system according to claim 1, 4 or 5, wherein the spray nozzle is provided at an outlet of the white smoke prevention heat exchanger. The exhaust gas desulfurization method in a pressurized fluidized-furnace system according to claim 1, wherein the spray liquid from the spray nozzle has a Sauter particle size of 30 to 150 µm. Pressure fluidized furnace,
A supercharger including a turbine that is rotated by combustion exhaust gas discharged from the pressurized fluidized furnace, and a compressor that is rotated with rotation of the turbine and that supplies combustion air to the pressurized fluidized furnace.
A pressurized fluidized flow reactor system comprising:
Regarding the combustion exhaust gas passing through the turbine of the supercharger, a flue gas treatment device for performing wet desulfurization using sodium hydroxide as a desulfurizing agent,
A chimney that emits gas after flue gas treatment to the atmosphere,
A spray nozzle for spraying sodium hydroxide solution, which is provided at a position where the temperature of the combustion exhaust gas in the post-combustion exhaust gas passage between the turbine and the smoke exhaust treatment device is 300°C to 550°C,
In the descending path in the post-combustion exhaust gas path, an overflow port forms a triangular weir, and water supplied from the outside is supplied, and the triangular weir overflows to flow into the descending path. A wet wall forming means in which a wet wall is formed on the inner surface of the path;
Have
Combustion exhaust gas discharged from the pressurized fluidized furnace, the electrostatic precipitator is not installed in the path until it is discharged to the atmosphere through the chimney,
A pressurized flow furnace system characterized by the above. In the middle of the combustion exhaust gas rear path between the turbine and the flue gas treatment device, a white smoke prevention heat exchanger for preventing white smoke from the chimney is provided,
The white smoke prevention heat exchanger is a shell and tube type installed vertically,
The pressurized fluidized bed reactor system according to claim 11, wherein the spray nozzle is provided so that an injection direction is directed to a downstream side of the combustion exhaust gas rear passage.

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