JP2012200721A - Spray-drying device for dehydrated filtrate from desulfurization wastewater, method of spray-drying dehydrated filtrate, and exhaust gas treatment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spray-drying device for dehydrated filtrate from desulfurization wastewater that can be stably operated and achieves the elimination of wastewater, a method of spray-drying dehydrated filtrate, and an exhaust gas treatment system.SOLUTION: The spray-drying device for spraying dehydrated filtrate 33 from desulfurization wastewater includes: a spray nozzle 52 that sprays dehydrated filtrate 33, obtained from desulfurization wastewater, into a spray-drying device body 51; an introduction port 51a that is provided in the spray-drying device body 51 and introduces exhaust gas 18 for drying a spray liquid 33a; a drying region 53 that is provided in the spray-drying device body 51 and in which the dehydrated filtrate 33 is dried by the exhaust gas 18; an exhaust port 51b that discharges the exhaust gas 18 contributed to the drying; and an adhesive material monitoring means 60 that monitors an adhesion state of adhesive materials adhering to the spray nozzle 52.

Description

  The present invention relates to a spray drying apparatus for dehydrated filtrate from desulfurization effluent generated during exhaust gas treatment for treating exhaust gas discharged from a boiler, a spray drying method for the dehydrated filtrate, and an exhaust gas treatment system.

  Conventionally, an exhaust gas treatment system for treating exhaust gas discharged from a boiler installed in a thermal power generation facility or the like is known. The exhaust gas treatment system includes a denitration device that removes nitrogen oxides from exhaust gas from a boiler, an air heater that recovers the heat of exhaust gas that has passed through the denitration device, a dust collector that removes soot and dust in the exhaust gas after heat recovery, and after dust removal And a desulfurization device for removing sulfur oxides in the exhaust gas. As the desulfurization apparatus, a wet desulfurization apparatus that removes sulfur oxide in the exhaust gas by bringing the lime absorbing liquid or the like into gas-liquid contact with the exhaust gas is generally used.

  Wastewater discharged from wet desulfurization equipment (hereinafter referred to as “desulfurization wastewater”) contains a large amount of various kinds of harmful substances such as ions such as chlorine ions and ammonium ions and mercury. For this reason, it is necessary to remove these harmful substances from the desulfurization effluent before the desulfurization effluent is discharged to the outside of the system, but the removal process of these various types of harmful substances contained in the desulfurization effluent is complicated, and the treatment cost There is a problem that is high. In order to reduce the treatment cost of the desulfurization waste water, a method for reusing the desulfurization waste water in the system without releasing it to the outside of the system has been proposed. For example, Patent Document 1 separately installs equipment for branching from a flue of a main line to which a denitration apparatus, an air heater, a dust collector, and a desulfurization apparatus are connected, and spraying and degassing desulfurization drainage. A part of the exhaust gas from the flue is introduced into this facility, and after desulfurization wastewater is sprayed and evaporated in the exhaust gas in the facility to deposit harmful substances, this gas is returned to the main line flue. An exhaust gas treatment device configured as described above is disclosed (Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 63-200188 Japanese Patent Laid-Open No. 9-313881

  However, in the exhaust gas treatment apparatus of Patent Documents 1 and 2, a part of the exhaust gas is branched from the flue, and a facility for spraying and gasifying the desulfurization waste water (or waste liquid) from the desulfurization apparatus is provided to evaporate the desulfurization waste water. However, the desulfurization effluent from the desulfurization apparatus has a problem that it cannot be spray-dried satisfactorily because it contains solids.

  Furthermore, in recent years, there has been a strong demand for eliminating wastewater in exhaust gas treatment facilities for environmental considerations for water resources in inland areas, etc., and the emergence of exhaust gas treatment facilities that can be operated stably is eagerly desired. Has been.

A spray dryer that dries desulfurization wastewater can be used as a facility for carrying out this drainage. However, when spraying desulfurization wastewater, there are the following problems.
1) Problems due to disturbance in the heat balance In order to evaporate the spray liquid, drying is promoted by the heat transfer between the spray liquid and hot air. appear.
2) Problems caused by the coarsening of the droplet diameter of the spray liquid due to ash adhesion When ash adheres to the tip of the spray nozzle, the diameter of the spray droplet generated from the nozzle changes and generally becomes coarse. The coarse droplets have a small specific surface area for heat exchange with warm air, and the heat exchange is slow, so that an evaporation delay occurs.

  In view of the above problems, the present invention is to provide a spray drying apparatus for dehydrated filtrate from desulfurized effluent that can be stably operated, and a method for spray drying dehydrated filtrate and an exhaust gas treatment system. And

  The first invention of the present invention for solving the above-mentioned problems is provided in the spray drying apparatus main body, the spray nozzle for spraying the dehydrated filtrate from the desulfurization effluent, and the spray drying apparatus main body for drying the spray liquid. An introduction port for introducing exhaust gas, a drying area provided in the spray drying apparatus main body for drying the dehydrated filtrate with exhaust gas, an exhaust port for discharging exhaust gas contributing to drying, and the adhesion state of the deposits of the spray nozzle And a deposit monitoring unit for monitoring the dehydrated filtrate from the desulfurization effluent.

  According to a second aspect of the present invention, there is provided the spray drying apparatus for dehydrated filtrate from desulfurized effluent, wherein the deposit monitoring means monitors the growth state of the ash deposit by ultrasonic or laser. .

  According to a third aspect of the present invention, there is provided the spray drying apparatus for dehydrated filtrate from desulfurization waste water according to the first or second aspect, further comprising deposit removing means for removing deposits.

  A fourth invention is the spray drying apparatus for dehydrated filtrate from desulfurization drainage according to the third invention, wherein the ash deposit removing means is a scraper movably provided on the outer periphery of the spray nozzle. .

  According to a fifth aspect of the present invention, there is provided the spray drying apparatus for dehydrated filtrate from the desulfurization waste water according to the third aspect of the invention, wherein the ash deposit removing means is a spray nozzle cleaning means.

  6th invention is provided in any one of the 1st thru | or 5 and is provided with two or more in the drying area | region, and spraying and drying a dehydrated filtrate by the thermometer which measures an internal temperature, and the measurement result of a thermometer. A desulfurization waste water comprising: a determination unit that determines whether the state is good; and a control unit that adjusts exhaust gas or dehydrated filtrate when it is determined that spray drying is defective as a result of the determination by the determination unit. From the dehydrated filtrate from the spray drying equipment.

  The seventh invention includes a boiler for burning fuel, an air heater for recovering heat of exhaust gas from the boiler, a dust collector for removing dust in the exhaust gas after heat recovery, and sulfur oxidation contained in the exhaust gas after dust removal 6. A desulfurization apparatus for removing matter with an absorbing liquid, a dehydrator for removing gypsum from desulfurization drainage discharged from the desulfurization apparatus, and a spraying means for spraying dehydrated filtrate from the dehydrator. An exhaust gas treatment system comprising any one spray dryer and an exhaust gas introduction line for introducing a part of the exhaust gas into the spray dryer.

  According to an eighth aspect of the present invention, there is provided an exhaust gas treatment system according to the seventh aspect, further comprising a solid-liquid separation device that removes suspended solids in the dehydrated filtrate from the dehydrator.

  According to a ninth aspect of the present invention, in the spray drying method of the dehydrated filtrate, the dehydrated filtrate is sprayed into the spray drying apparatus main body and the spray liquid is dried by the introduced exhaust gas. The spray drying method of the dehydrated filtrate is characterized in that it is determined whether or not it is appropriate, and when spraying is inappropriate, the spray nozzle is washed and the ash deposits adhering to the vicinity of the spray nozzle are removed.

  According to a tenth aspect, in the ninth aspect, the temperature distribution in the spray drying apparatus main body is measured, the drying state is monitored by the temperature distribution in the gas flow direction, and if the dehydrated filtrate is insufficiently dried, the exhaust gas The method of spray drying the dehydrated filtrate is characterized by adjusting the amount and the supply amount of the dehydrated filtrate.

  According to the method of the present invention, using the exhaust gas from the boiler, using the dehydrated filtrate obtained by removing gypsum from the desulfurization effluent separated from the desulfurization device, when spraying with a spray dryer, grasp the spray drying state, If there is a spray failure, it can be stably sprayed by removing it. This makes it possible to eliminate the desulfurization drainage from the desulfurization apparatus.

FIG. 1 is a schematic configuration diagram of an exhaust gas treatment system according to a first embodiment. FIG. 2 is a schematic view of a spray dryer for dehydrated filtrate from desulfurization effluent according to the first embodiment. FIG. 3A is a schematic diagram illustrating a monitoring state of deposits by the deposit monitoring unit. FIG. 3B is a schematic diagram illustrating a monitoring state of the deposit by the deposit monitoring unit. FIG. 3-3 is a schematic diagram illustrating a monitoring state of the deposit by the deposit monitoring unit. FIG. 4 is a schematic view of a spray dryer of dehydrated filtrate from another desulfurization effluent according to the first embodiment. FIG. 5-1 is a diagram illustrating a state of removal of an adhesion portion by a scraper provided around the spray nozzle. FIG. 5-2 is a diagram illustrating a state in which an attached portion is removed by a scraper provided around the spray nozzle. FIG. 5C is a diagram illustrating a state of removal of an adhesion portion by a scraper provided around the spray nozzle. FIG. 6 is a schematic diagram of a spray nozzle according to the second embodiment. FIG. 7 is a schematic view of a spray dryer according to the third embodiment. FIG. 8-1 is a relationship diagram between the distance from the nozzle to the thermometers (T _{1 to} T ₇ ) provided at seven locations in the spray drying apparatus main body and the measured temperature. FIG. 8-2 is a relationship diagram between the distance from the nozzle to the thermometers (T _{1 to} T ₇ ) provided at seven locations in the spray dryer main body and the measured temperature. FIG. 9 is a schematic configuration diagram of an exhaust gas treatment system according to a fourth embodiment. FIG. 10 is a schematic configuration diagram of another exhaust gas treatment system according to the fifth embodiment.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this Example, Moreover, when there exists multiple Example, what comprises combining each Example is also included. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

FIG. 1 is a schematic configuration diagram of an exhaust gas treatment system according to a first embodiment. An exhaust gas treatment system 10A exemplified in FIG. 1 includes nitrogen oxide (NO _x ), sulfur from exhaust gas 18 from a boiler 11 such as a coal fired boiler using coal as a fuel or a heavy oil fired boiler using heavy oil as a fuel. This is a device for removing harmful substances such as oxide (SO _x ) and mercury (Hg).

The exhaust gas treatment system 10A includes a boiler 11 that burns fuel F, an air heater 13 that recovers heat of the exhaust gas 18 from the boiler 11, a dust collector 14 that removes soot and dust in the exhaust gas 18 after heat recovery, and a post-dust removal A desulfurization device 15 that removes sulfur oxides contained in the exhaust gas 18 with a lime slurry 20 that is an absorbing solution, a dehydrator 32 that removes gypsum 31 from a desulfurization drain 30 discharged from the desulfurization device 15, and the dehydrator The spray dryer 50 provided with the spraying means for spraying the dehydrated filtrate 33 from 32 and the exhaust gas introduction line L ₁₁ for introducing a part of the exhaust gas 18 into the spray dryer 50 are provided. Thereby, since it spray-drys with the spray dryer 50 using the dehydrated filtrate 33 from which the gypsum has been removed, it is possible to perform stable spraying.
As a result, clogging in the spray dryer does not occur, and the desulfurization drainage can be stably drained.

Denitration device 12 is a device for removing nitrogen oxides in the exhaust gas 18 supplied from the boiler 11 through the gas supply line L _1, and has inside thereof denitration catalyst layer (not shown). A reducing agent injector (not shown) is disposed upstream of the denitration catalyst layer, and the reducing agent is injected into the exhaust gas 18 from the reducing agent injector. Here, for example, ammonia, urea, ammonium chloride or the like is used as the reducing agent. The nitrogen oxides in the exhaust gas 18 introduced into the denitration device 12 come into contact with the denitration catalyst layer, so that the nitrogen oxides in the exhaust gas 18 are decomposed and removed into nitrogen gas (N ₂ ) and water (H ₂ O). Is done. Further, as the mercury in the exhaust gas 18 increases in the chlorine (Cl) content in the exhaust gas 18, the proportion of divalent mercury chloride soluble in water increases, and mercury is easily collected by the desulfurization device 15 described later. .

  The denitration device 12 is not essential, and when the nitrogen oxide concentration or mercury concentration in the exhaust gas 18 from the boiler 11 is very small, or when these substances are not contained in the exhaust gas 18, denitration is performed. It is also possible to omit the device 12.

The air heater 13 is a heat exchanger that recovers heat in the exhaust gas 18 supplied through the gas supply line L ₂ after nitrogen oxides are removed by the denitration device 12. Since the temperature of the exhaust gas 18 that has passed through the denitration device 12 is as high as about 350 ° C. to 400 ° C., heat exchange is performed between the high temperature exhaust gas 18 and normal temperature combustion air by the air heater 13. The combustion air that has reached a high temperature due to heat exchange is supplied to the boiler 11. On the other hand, the exhaust gas 18 subjected to heat exchange with room temperature combustion air is cooled to about 150 ° C.

Precipitator 14 after heat recovery, is to remove the dust in the flue gas 18 supplied through the gas supply line L _3. Examples of the dust collector 14 include an inertial dust collector, a centrifugal dust collector, a filtration dust collector, an electric dust collector, and a cleaning dust collector, but are not particularly limited.

The desulfurization device 15 is a device that removes sulfur oxide in the exhaust gas 18 supplied via the gas supply line L ₄ in a wet manner after the dust is removed. In this desulfurization apparatus 15, lime slurry 20 (aqueous solution in which limestone powder is dissolved in water) is used as an alkali absorbing liquid, and the temperature in the apparatus is adjusted to about 30 to 80 ° C. The lime slurry 20 is supplied from the lime slurry supply device 21 to the tower bottom 22 of the desulfurization device 15. The lime slurry 20 supplied to the tower bottom 22 of the desulfurization apparatus 15 is sent to a plurality of nozzles 23 in the desulfurization apparatus 15 via an absorption liquid supply line (not shown), and ejected from the nozzle 23 toward the tower top 24 side. Is done. When the exhaust gas 18 rising from the tower bottom 22 side of the desulfurization apparatus 15 comes into gas-liquid contact with the lime slurry 20 ejected from the nozzle 23, sulfur oxide and mercury chloride in the exhaust gas 18 are absorbed by the lime slurry 20, It is separated from the exhaust gas 18 and removed. The exhaust gas 18 purified by the lime slurry 20 is discharged from the tower top 24 side of the desulfurization device 15 as the purified gas 26 and is discharged out of the system from the chimney 27.

Inside the desulfurization apparatus 15, the sulfur oxide SO _x in the exhaust gas 18 causes a reaction represented by the lime slurry 20 and the following formula (1).
CaCO ₃ + SO ₂ + 0.5H ₂ O → CaSO ₃ · 0.5H ₂ O + CO ₂ (1)

Further, the lime slurry 20 that has absorbed SO _x in the exhaust gas 18 is oxidized by air (not shown) supplied to the tower bottom 22 of the desulfurization device 15, and the reaction represented by the following equation (2) with air. Produce.
CaSO ₃ · 0.5H ₂ O + 0.5O ₂ + 1.5H ₂ O → CaSO ₄ · 2H ₂ O (2)
In this way, SO _x in the exhaust gas 18 is captured in the form of gypsum CaSO ₄ .2H ₂ O in the desulfurization apparatus 15.

In addition, as described above, the lime slurry 20 is obtained by pumping the liquid stored in the tower bottom 22 of the desulfurization device 15, and the lime slurry 20 to be pumped is accompanied by the operation of the desulfurization device 15. Gypsum CaSO ₄ .2H ₂ O is mixed according to the reaction formulas (1) and (2). Below, this lime-gypsum slurry (lime slurry mixed with gypsum) to be pumped is called an absorbent.

Absorbing solution used for desulfurization (limestone gypsum slurry) is discharged from the bottom portion 22 of the desulfurization apparatus 15 to the outside as a desulfurization effluent 30 is sent to the dehydrator 32 through the drain line L ₂₀ to be described later, wherein the dehydration treatment Is done. In addition to gypsum, the desulfurization effluent 30 contains heavy metals such as mercury and halogen ions such as Cl ⁻ , Br ⁻ , I ⁻ and F ⁻ .

The dehydrator 32 separates the solid content containing the gypsum 31 in the desulfurization waste water 28 and the dehydrated filtrate 33 of the liquid content. As the dehydrator 32, for example, a belt filter, a centrifugal separator, a decanter type centrifugal sedimentator or the like is used. From the desulfurization waste water 30 discharged from the desulfurization device 15, the gypsum 31 is separated by a dehydrator 32. At that time, mercury chloride in the desulfurization waste water 30 is separated from the liquid together with the gypsum 31 in a state of being adsorbed on the gypsum 31. The separated gypsum 31 is discharged to the outside of the system (hereinafter referred to as “outside system”).
On the other hand, a separated liquid dehydrating filtrate 33 is sent to a spray dryer 50 via a dehydration line L _21. The dehydrated filtrate 33 may be temporarily stored in a drain tank (not shown).

The spray dryer 50 includes gas introduction means for introducing a part of the exhaust gas via the branch line L ₁₁ branched from the exhaust gas line L _2, and spray means for spraying or spraying the dehydrated filtrate 33. Then, the dehydrated filtrate 33 sprayed by the heat of the introduced exhaust gas 18 is evaporated and dried.

In the present invention, since the dehydrated filtrate 33 from which the gypsum 31 has been removed from the desulfurization waste water is spray-dried, clogging by the spraying means can be prevented.
That is, since the desulfurization wastewater itself is not sprayed, the amount of dry particles generated as the desulfurization wastewater evaporates can be greatly reduced. As a result, clogging due to adhesion of dry particles can be reduced. Further, by dehydrating the desulfurization waste water 30, mercury chloride is separated and removed together with the gypsum 31, so that it is possible to prevent the mercury concentration in the exhaust gas 18 from increasing during spraying of the waste water.

In the present embodiment, part of the exhaust gas flowing into the air heater 13 is branched from the exhaust gas line L ₂ via the branch line L ₁₁ , so that the temperature of the exhaust gas is high (350 to 400 ° C.), and the dehydrated filtrate 33 Can be efficiently spray-dried.

FIG. 2 is a schematic view of a spray dryer (spray dryer) for dehydrated filtrate from desulfurization effluent according to the first embodiment. FIG. 4 is a schematic view of a spray dryer (spray dryer) for dehydrated filtrate from another desulfurization effluent according to the first embodiment.
As shown in FIG. 2, the spray dryer 50 of the present embodiment is provided in the spray drying apparatus main body 51, the spray nozzle 52 for spraying the dehydrated filtrate 33 from the desulfurization waste water, and the spray drying apparatus main body 51. An inlet 51a for introducing the exhaust gas 18 for drying the liquid 33a, a drying region 53 for drying the dehydrated filtrate 33 with the exhaust gas 18 provided in the spray drying apparatus main body 51, and an outlet for discharging the exhaust gas 18 that contributes to drying 51b and the deposit | attachment monitoring means 60 which monitors the adhesion state of the deposit | attachment of the said spray nozzle 52 are comprised. Reference numeral 56 indicates the separated solid matter.

  As the deposit monitoring means 60, an ultrasonic measuring instrument (microwave measuring meter) or the like can be used. As this ultrasonic measuring instrument, for example, a “high range equipment micro rangefinder micro ranger” (trade name: manufactured by WADECO) can be exemplified.

FIGS. 3-1 to 3-3 are schematic views showing the monitoring state of the deposit by the deposit monitoring means.
In FIG. 3A, the attached matter monitoring means 60 is provided on the side wall of the spray drying apparatus main body 51 to monitor the presence or absence of attached matter by aiming at the tip of the spray nozzle 52.
Here, as the deposit of the dehydrated filtrate 33, an umbrella-shaped scale grows at the tip of the nozzle, and is an deposit of ash in the exhaust gas.
When spraying the dehydrated filtrate 33, the spray liquid 33 a hits the umbrella-shaped deposit 61, and the spray liquid 33 a becomes coarse, resulting in deterioration of the evaporability of the dehydrated filtrate 33.

Therefore, as shown in FIGS. 3-2 and 3-3, the microwave 63 is generated from the deposit monitoring means 60, and the distance to the deposit generation position in the tip end space portion of the spray nozzle 52 is measured.
In FIG. 3-2, it is a case where there is no generation | occurrence | production of the deposit | attachment, and it becomes the measurement distance x, and this is judged to be normal (no adhering portion).
On the other hand, in FIG. 3C, it is a case where the deposit | attachment 61 has generate | occur | produced, it becomes the measurement distance y, and this is judged to be abnormal (the deposit | attachment exists).
When the ash adhesion growth is detected from the measurement result of the deposit monitoring means 60, an instruction (* 10) to remove the deposit is issued.
In addition to installing the deposit monitoring means 60, the presence or absence of the deposit 61 may be confirmed by visual observation by an operator.
Here, when the operator visually observes, a monitoring observation window (not shown) provided in the spray drying apparatus main body 51 is used.

  Here, in order to remove the deposits, 1) supply of the dehydrated filtrate is stopped, replacement with the working water is performed, and the nozzle and the inside of the pipe are cleaned by the spray nozzle cleaning means. 2) The deposits are forcibly removed by the ash removal means.

Substitution of the industrial water, as shown in FIG. 4, the exhaust gas treatment system 10B, by closing the valve V ₁₁ to stop the supply of the dehydration filtrate 33, supplying industrial water 70, industrial water by opening the valve V ₁₂ 70 is supplied to perform replacement, and the nozzle and piping are cleaned by the spray nozzle cleaning means.
The frequency of replacement with the working water may be appropriately changed from once / day to 1 to 3 times / day depending on the degree of adhesion of the deposit. Moreover, the supply time of the engineering water 70 may be about 1 hour / 1 time, for example.
At this time, a chemical solution for dissolving the deposit may be supplied.

  As the ash removing means, a striking means (not shown) is provided in the spray nozzle 52 to drop the adhering portion. The hitting means may be installed at a position where the spray does not reach.

  Or the scraper which has the annular blade provided in the spray nozzle is operated, and the deposit | attachment adhering to the front-end | tip is cut off.

FIGS. 5A to 5C are diagrams illustrating how the attached portion is removed by a scraper provided around the spray nozzle.
FIG. 5A is a front view of the spray nozzle, in which the deposit 61 is attached around the spray nozzle 52. FIG. 5B is a side view of the spray nozzle, and the scraper 65 is in a standby state. FIG. 5C is a side view of the spray nozzle, in which the scraper 65 is activated, and the deposits are crushed and dropped by the annular blade at the tip. The dotted line is the part of the deposit that falls off.

  Further, not only when the deposit 61 is present but also when the scraper 52 is operated at a predetermined frequency, the deposit 61 can be removed early.

FIG. 6 is a schematic diagram of a spray nozzle according to the second embodiment. In addition, the same code | symbol is attached | subjected to the structure same as Example 1 mentioned above, and the description is abbreviate | omitted.
As shown in FIG. 6, the spray nozzle 52 according to the present embodiment is provided with an outer cylinder 67 around the nozzle, supplies a barrier gas 68 from a supply port 67a, and supplies air from the nozzle tip portion to form an air film. It is formed to suppress ash adhesion due to dust.
The supply of the barrier gas 68 is performed at a speed equal to the spray spray speed for spraying the spray liquid 33a, thereby preventing the generation of peripheral vortices.
In this embodiment, since the scraper 65 is also provided, the scraper is operated as needed to remove the deposit 61.
In FIG. 5, reference numeral 66 denotes a scraper operating handle.

  According to the spray nozzle 52 of the present embodiment, the introduction of the barrier gas 68 suppresses the growth of the deposit 61 and enables stable spraying at the spray nozzle 52.

FIG. 7 is a configuration diagram of the spray dryer according to the third embodiment.
The spray dryer according to the present embodiment is the same as the spray dryer according to the first embodiment, and further includes thermometers T _{1 to} T ₇ that measure the internal temperature in the drying region 53, and the dehydrated filtrate 33 according to the measurement result of the thermometer. And a control means 55 for adjusting the exhaust gas or the dehydrated filtrate when it is determined that the spray drying is defective as a result of the determination by the determination means 54. Is.

In the present embodiment, thermometers (T _{1 to} T ₇ ) are provided at seven locations, but the present invention is not limited to this, and is appropriately changed according to the length of the dry region 53.
Although the temperature measurement is installed on the vertical axis portion of the apparatus main body, the present invention is not limited to this, and may be installed anywhere as long as it can be installed at a position where the evaporation state can be confirmed.

8A and 8B are relationship diagrams between the distances from the nozzles to the thermometers (T _{1 to} T ₇ ) and the measured temperatures at seven locations.
Here, in the liquid evaporation process, heat is required for the temperature rise and evaporation of the droplets of the spray liquid 33a. In this case, since the heat of the exhaust gas 18 is used for increasing the temperature or evaporating the droplets, the temperature of the exhaust gas 18 is lowered. The quality of drying is judged by detecting the decrease in temperature.
FIG. 8-1 is a relationship diagram when drying is good, and FIG. 8-2 is a relationship diagram when drying is poor.
In FIG. 8A, the temperature decrease stops from around T ₄ and the temperature is constant. This is because there is no droplet of the spray liquid 33a.
In contrast, in Figure 8-2, the temperature decrease is intermittently reduced to T _7. This is because a large amount of droplets of the spray liquid 33a remain.

This result is judged by the judging means 54.
If the result of determination by the determination means 54 is that the drying is good, spray drying of the dehydrated filtrate 33 is continued as it is.

  On the other hand, as a result of the determination by the determination means 54, when it is determined that the drying is defective, the control means 55 adjusts the exhaust gas 18 or the dehydrated filtrate 33.

Specifically, adjustment of the dehydrated filtrate 33 is performed by operating the adjustment valve V ₁ to increase or decrease the supply amount of the dehydrated filtrate 33 or increase or decrease the supply amount of atomized air supplied to the spray nozzle 52. Make adjustments.
Further, a buffer tank for storing a predetermined amount of the dehydrated filtrate 33 may be provided for adjustment.

  For this reason, flow rate information (* 1) obtained by measuring the flow rate of the dehydrated filtrate 33 (not shown) is input to the control means. Based on this information, the valve opening is adjusted or the pump flow rate (not shown) is adjusted. ing.

The exhaust gas 18 is adjusted by controlling the amount of exhaust gas introduced.
The introduction amount is adjusted by controlling the opening degree of the valve V ₂ or the damper by adjusting the pressure loss with the exhaust gas introduction line L ₁₁ .

Further, the exhaust gas introduction line L ₁₁ may be a plurality of series, and two or more spray dryers 50 may be installed to adjust the supply amount of the exhaust gas.

  Also, by measuring the temperature profile over time and confirming a transient change from a good dry state to a poorly dry state by measuring the temperature, it is possible to determine the cause of the dry defect. You may make it perform the operation mentioned above to improve.

  According to this embodiment, when the dehydrated filtrate from which the gypsum has been removed from the desulfurization effluent discharged from the desulfurization apparatus is spray-dried with a part of the exhaust gas, the spray-dried state of the dehydrated filtrate is monitored for the temperature state in the drying region. Therefore, the spray-dried state can be maintained stably, and desulfurization drainage can be eliminated. In addition, since the deposit nozzle 52 monitors the deposit growth in the spray nozzle 52, it is possible to perform stable operation by taking measures to remove the deposit before the spray abnormality occurs.

  Further, in the spray drying method of the dehydrated filtrate in which the dehydrated filtrate 33 is sprayed into the spray drying apparatus body 51 and the spray liquid 33a is dried by the introduced exhaust gas 18, the spray state of the spray nozzle 52 is confirmed, and the dehydrated filtrate 33 is It is determined whether or not spraying is appropriate. If spraying is inappropriate, the spray nozzle 52 is washed and the adhering matter 61 adhering to the vicinity of the spray nozzle 52 is removed. Spray drying can be performed.

  Further, the temperature distribution in the drying region 53 inside the spray drying apparatus main body 51 is measured, the drying state is monitored by the temperature distribution in the gas flow direction, and if the dehydrated filtrate 33 is insufficiently dried, the amount of exhaust gas, dehydrated filtrate By adjusting the supply amount, a more stable dehydrated filtrate can be spray-dried.

  Thus, according to the present invention, as a method for monitoring the quality of the spray state, (1) grasping the evaporation state by temperature and (2) grasping the growth of the deposit 61 by, for example, ultrasonic waves, (a) In the case of poor evaporation, the introduction amount of the exhaust gas or desulfurized filtrate is adjusted. (b) In the case where the drop diameter change of the spray liquid 33a is the cause, the spray nozzle 52 is washed or the ash removal device. Can be restored to an appropriate spray state, and stable dehydration of the dehydrated filtrate 33 can be performed.

Next, an exhaust gas treatment system according to Example 4 will be described.
FIG. 9 is a schematic configuration diagram of an exhaust gas treatment system according to a fourth embodiment. In addition, the same code | symbol is attached | subjected to the structure same as Example 1 mentioned above, and the description is abbreviate | omitted. The exhaust gas treatment system 10C illustrated in FIG. 8 is a solid-liquid separation that removes suspended solids (SS) or suspended substances in the desulfurized filtrate 33 in the exhaust gas treatment system 10A according to the first embodiment. the device 41 is obtained by interposing a dewatering line L _21.
Examples of the solid-liquid separation device 41 include a liquid cyclone, a belt filter, a classifier, and a membrane separation device.

The solid-liquid separation device 41 removes suspended substances (SS) in the dehydrated filtrate 33, and the SS concentration in the separation liquid 42 is 1% by weight or less, more preferably 0.1 to 0.5% by weight.
Thereby, SS density | concentration reduces and clogging of the nozzle, piping, etc. in the spray dryer 50 can further be suppressed.
That is, by setting the SS concentration to 1% by weight or less, and more preferably 0.1 to 0.5% by weight, it is possible to prevent the spray-dried material from adhering to the tip of the spray nozzle during spray-drying or the growth of dust. , The occurrence of spray failure is suppressed. As a result, the shortage of drying due to the stoppage of operation due to the blockage and the prolonged required drying time due to the coarsening of the spray droplet diameter are solved. In addition, drying unevenness, insufficient drying, and the like due to the spraying range being eliminated are eliminated.

The separation residue 43 separated by the solid-liquid separation device may be joined to the dust collection ash 16 so that the dehydrated filtrate 33 contains water.
When the dust collection ash 16 is separately used separately, the dust collection ash 16 and the residue may be sprayed with the dehydrated filtrate 33 in different places.

Also, either one or both of the front side or the rear stage of the spray dryer 50 provided in the exhaust gas introduction line L ₁₁ to provide a compact dust collector, the dust in the exhaust gas so as to remove at the exhaust gas introduction line L ₁₁ Also good.

The exhaust gas 18 is introduced into the spray dryer 50 due to a difference in pressure loss between the exhaust gas line and the exhaust gas introduction line L ₁₁ , or the exhaust gas 18 is exhausted using an induction fan or the like as necessary. 18 is introduced.

Next, an exhaust gas treatment system according to Example 5 will be described. In addition, the same code | symbol is attached | subjected to the structure same as Example 1 mentioned above, and the description is abbreviate | omitted.
FIG. 10 is a schematic configuration diagram of an exhaust gas treatment system according to a fifth embodiment. The exhaust gas treatment system 10D according to the present embodiment, as shown in FIG. 10, and performs a branch of the exhaust gas 18 from the exhaust gas line L ₃ of the air heater 13, again the same portion of the exhaust gas which has contributed to the spray drying in a spray dryer 50 It is returned to the exhaust gas line L _3.
Thereby, it becomes unnecessary to provide a bypass line as in the first embodiment.

10A to 10D Exhaust gas treatment system 11 Boiler 12 Denitration device 13 Air heater 14 Dust collector 15 Desulfurization device 16 Dust collection ash 18 Exhaust gas 20 Lime slurry 21 Lime slurry supply device 22 Tower bottom 23 Nozzle 24 Tower top 26 Purified gas 27 Chimney 30 Desulfurization drainage 32 Dehydration Machine 33 Dehydrated filtrate 50 Spray dryer

Claims (10)

A spray nozzle that sprays the dehydrated filtrate from the desulfurization effluent into the spray dryer body,
An inlet provided in the spray drying apparatus body for introducing exhaust gas for drying the spray liquid;
A drying area provided in the spray drying apparatus main body, and drying the dehydrated filtrate with exhaust gas;
An exhaust port for exhaust gas that contributed to drying;
A spray drying apparatus for dehydrated filtrate from desulfurized effluent, comprising: a deposit monitoring means for monitoring a deposit state of the deposit on the spray nozzle. In claim 1,
The said deposit | attachment monitoring means monitors the growth state of the ash deposit | attachment by an ultrasonic wave or a laser, The spray-drying apparatus of the dehydrated filtrate from the desulfurization waste water characterized by the above-mentioned. In claim 1 or 2,
Furthermore, the spray drying apparatus of the dehydrated filtrate from the desulfurization waste water characterized by providing the deposit removal means which removes deposits. In claim 3,
An apparatus for spray-drying dehydrated filtrate from desulfurization effluent, wherein the ash deposit removal means is a scraper movably provided on the outer periphery of the spray nozzle. In claim 3,
The spray drying apparatus for dehydrated filtrate from desulfurization waste water, wherein the ash deposit removing means is spray nozzle cleaning means. Provided in any one of claims 1 to 5,
A thermometer that is provided in the drying area and measures the internal temperature;
Based on the measurement result of the thermometer, a determination means for determining the quality of the sprayed / dried state of the dehydrated filtrate,
An apparatus for spray drying dehydrated filtrate from desulfurized effluent, comprising: a control means for adjusting exhaust gas or dehydrated filtrate when it is determined that spray drying is defective as a result of determination by the determining means. A boiler that burns fuel;
An air heater for recovering heat of exhaust gas from the boiler;
A dust collector to remove the dust in the exhaust gas after heat recovery;
A desulfurization device that removes sulfur oxides contained in the exhaust gas after dust removal with an absorbing solution;
A dehydrator for removing gypsum from the desulfurization effluent discharged from the desulfurization device;
The spray drying apparatus according to any one of claims 1 to 5, further comprising spray means for spraying the dehydrated filtrate from the dehydrator;
An exhaust gas treatment system comprising an exhaust gas introduction line for introducing a part of the exhaust gas into the spray drying apparatus. In claim 7,
An exhaust gas treatment system comprising a solid-liquid separation device for removing suspended solids in the dehydrated filtrate from the dehydrator. In the spray drying method of the dehydrated filtrate in which the dehydrated filtrate is sprayed into the spray drying apparatus main body and the spray liquid is dried by the introduced exhaust gas.
Check the spray state of the spray nozzle, determine whether spraying the dehydrated filtrate is appropriate,
A spray-drying method of a dehydrated filtrate, characterized in that when spraying is inappropriate, washing of the spray nozzle and removal of ash deposits adhering to the vicinity of the spray nozzle are performed. In claim 9,
Measure the temperature distribution inside the spray dryer body,
Monitor the dry state by the temperature distribution in the gas flow direction,
A method for spray-drying a dehydrated filtrate, comprising adjusting an exhaust gas amount and a supply amount of a dehydrated filtrate when drying of the dehydrated filtrate is insufficient.

Images