WO2018051554A1

WO2018051554A1 - Method and device for recovering waste water from incineration plant

Info

Publication number: WO2018051554A1
Application number: PCT/JP2017/011130
Authority: WO
Inventors: 恵一水品; 邦洋早川
Original assignee: 栗田工業株式会社
Priority date: 2016-09-16
Filing date: 2017-03-21
Publication date: 2018-03-22
Also published as: JP2018043218A; CN109641765B; CN109641765A; JP6241525B1

Abstract

The present invention efficiently recovers heat from flue gas in an incineration plant and to achieve stable and efficient treatment of the flue gas. Waste water discharged from an incineration plant is subjected to water treatment by a water treatment device 6, the incineration plant being equipped with: an incineration device 1; a heat recovery device 2 for recovering heat from flue gas; a temperature lowering device 3 for further lowering the temperature of the flue gas having undergone heat recovery at the heat recovery device 2; a dust collector 4 for removing dust from the flue gas having undergone temperature-lowering; and a catalytic denitrification device 5. The treated water is delivered to the temperature lowering device 3 and injected into the flue gas so as to be evaporated to achieve lowering of the temperature of the flue gas. A control device 7 controls the amount of water to be delivered from the water treatment device 6 to the temperature lowering device 3 so that the temperature of the flue gas at the outlet of the temperature lowering device 3 is 150-200°C.

Description

Wastewater recovery method and apparatus for incineration plant

The present invention relates to a method and apparatus for collecting wastewater discharged from an incineration plant.

Emission from an incineration plant equipped with an incinerator for burning organic matter, a heat recovery device for recovering the heat of combustion exhaust gas discharged from the incinerator, and a temperature reducing device for further reducing the temperature of the exhaust gas recovered by heat recovery As a wastewater treatment method, a wastewater treatment method is known in which the wastewater is subjected to a coagulation treatment with a coagulant or the like and then filtered.

There is also known a wastewater treatment method in which wastewater discharged from an incineration plant is subjected to a biological treatment after being agglomerated with a flocculant or the like, and further subjected to a filtration treatment by sand filtration (Patent Document 1). Patent Document 1 describes that most of the purified water purified by this wastewater treatment method can be discharged.

In recent years, drainage closed systems that prevent wastewater from being discharged into sewers and public water areas by reusing wastewater generated in the facility have become widespread.
Therefore, in an incineration plant that burns solids such as general waste and industrial waste, wastewater is simply treated by the wastewater treatment method, etc., and then sprayed as temperature-reduced water using a temperature-reducing device that reduces the temperature of combustion exhaust gas. The method of evaporating is adopted. In this case, some of the wastewater is used for spraying into the furnace or humidifying water for fly ash, but most or all of the wastewater discharged in the facility is used as dehumidified water for combustion exhaust gas. used.

In the incineration plant, the amount of wastewater generated in the facility is large, and most of it is reused as temperature-reduced water as described above. Therefore, the outlet temperature of the heat recovery device (boiler) is determined based on the amount of spray water of the temperature-reduced water. . That is, in order to evaporate a large amount of water in the temperature reduction device, the amount of heat recovered from the combustion exhaust gas in the heat recovery device may be reduced in order to increase the outlet temperature of the heat recovery device (inlet temperature of the temperature reduction device). Necessary.

Thus, when trying to adopt a wastewater closed system in an incineration plant, since the amount of wastewater sprayed on the temperature reducing device is large, it is necessary to set a large temperature range to reduce the temperature by the heat of vaporization, and that much, In a heat recovery device such as a waste heat boiler on the upstream side of the temperature reducing device, the amount of heat recovered from the combustion exhaust gas has to be set small. That is, as the temperature range for reducing the temperature in the temperature reducing device is relatively large (ΔT is large), the amount of heat recovered from the combustion exhaust gas in the heat recovery device is further reduced (ΔT is small), and the incineration plant. The efficiency of heat recovery from the combustion exhaust gas at is reduced. A decrease in heat recovery efficiency in the heat recovery apparatus leads to a decrease in power generation amount and a decrease in power generation efficiency.

By reducing the amount of water supplied to and sprayed to the temperature reducing device, the outlet temperature of the heat recovery device can be lowered, and the heat recovery efficiency can be increased. In Patent Document 2, in order to reduce the amount of water sent to the temperature reducing device, the incineration plant wastewater is treated with an MF membrane, the permeate is treated with an RO membrane, and MF membrane concentrated water and RO membrane concentrated water are used. It is described that it is supplied to a temperature reducing device. If this method is used, the amount of water sprayed on the temperature reducing device can be reduced by concentrating the wastewater with the MF membrane and the RO membrane, and the reduction in heat recovery efficiency can be suppressed.

However, in the conventional method, almost all of the wastewater discharged from the incineration plant is sent to the temperature reducing device, and the amount of water supplied to the temperature reducing device is not controlled. As a result, the heat recovery efficiency could not be stably maintained high.

In the conventional method, since the processing efficiency in the exhaust gas treatment device on the downstream side after the temperature reduction device is not taken into consideration, there is a problem in that the reduced temperature of the combustion exhaust gas cannot be efficiently treated.

That is, the combustion exhaust gas reduced in temperature by the temperature reducing device is usually neutralized by adding sodium bicarbonate (sodium bicarbonate) or calcium hydroxide (slaked lime), then removed by a dust collector, and further NOx contained in the exhaust gas. In order to remove the gas, ammonia is added and brought into contact with a denitration catalyst, and NOx is decomposed and removed by a catalytic reduction reaction. Therefore, the temperature of the exhaust gas reduced in temperature by the temperature reducing device needs to be a temperature suitable for the treatment of these exhaust gases.

However, in the conventional method, since the amount of water supplied to the temperature reducing device is not controlled, the temperature of the exhaust gas from the temperature reducing device to be neutralized is not constant, depending on fluctuations in the amount of discharged water and the amount of water supplied. The exhaust gas treatment has become unstable. In particular, as in Patent Document 2, when the concentrated water of the RO membrane separator is sent to the temperature reducing device, the amount of concentrated water of the RO membrane separator is the quality of the raw water of the RO membrane separator (treated water of the MF membrane separator). Therefore, when the obtained concentrated water is sent to the temperature reducing device without controlling the water recovery rate of this RO membrane separation device, the amount of water supplied to the temperature reducing device will vary depending on the amount of drainage. In addition, it becomes even bigger.

For example, since the temperature suitable for the neutralization treatment with baking soda is relatively high, if the amount of water supplied to the temperature reduction device increases and the temperature at the outlet of the temperature reduction device decreases, neutralization treatment with sodium bicarbonate cannot be performed sufficiently. Since the neutralization temperature with slaked lime is slightly lower than with baking soda, neutralization can be performed stably using slaked lime even if the amount of water supplied to the temperature reducing device increases and the temperature at the outlet of the temperature reducing device decreases. However, if the temperature reducing device outlet temperature is too low, the processing efficiency in the denitration catalyst device after the dust collector deteriorates or cannot be processed. Therefore, it is necessary to perform heating with boiler steam or electricity in the denitration catalyst device.

In the conventional method, since the exhaust gas temperature after the temperature reducing device is unstable and unpredictable, it is difficult to control the chemical injection for the exhaust gas treatment, which is a troublesome and safety-side treatment required for the exhaust gas treatment. Therefore, the cost was increased.

As described above, in the conventional method, the amount of water supplied to the temperature reducing device is not controlled, and the temperature at the outlet of the temperature reducing device fluctuates. There was a problem that reheating was required and thermal efficiency was poor.

JP-A-10-99898 Japanese Patent No. 5636163

An object of the present invention is to provide a wastewater recovery method and apparatus for an incineration plant that can efficiently recover the heat of the combustion exhaust gas in the incineration plant and that can stably and efficiently treat the combustion exhaust gas.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have reduced the temperature by controlling the amount of water supplied to the temperature reducing device so that the temperature reducing device outlet temperature is within a predetermined range. It has been found that the treatment of the combustion exhaust gas can be performed stably and efficiently, and the heat recovery in the heat recovery apparatus can be performed stably and efficiently.

The gist of the present invention is as follows.

[1] An incinerator that combusts organic matter, a heat recovery device that recovers the heat of the combustion exhaust gas discharged from the incinerator, a temperature reduction device that reduces the temperature of the combustion exhaust gas recovered by the heat recovery device, A wastewater recovery method for wastewater discharged from an incineration plant comprising an exhaust gas treatment device for processing combustion exhaust gas reduced in temperature by the temperature reduction device, wherein the water treatment clarifies the wastewater discharged from the incineration plant A process for supplying the treated water of the water treatment process to the temperature reducing device, and reducing the combustion exhaust gas by blowing and evaporating the treated water fed into the combustion exhaust gas in the temperature reducing device. In the wastewater recovery method for an incineration plant having a temperature reducing step for heating, the amount of water sent to the temperature reducing device for the treated water in the water treatment step is set so that the flue gas temperature at the outlet of the temperature reducing device is 150 to 200 ° C. To control Waste water recovery method of incineration plants characterized by.

[2] A wastewater recovery method for an incineration plant according to [1], wherein the water treatment step includes a membrane separation step, and the water supply amount is controlled by adjusting a water recovery rate in the membrane separation step.

[3] A wastewater recovery method for an incineration plant according to [2], wherein the membrane separation step is a reverse osmosis membrane separation step.

[4] Incineration according to any one of [1] to [3], wherein sodium bicarbonate and / or calcium hydroxide is added to the temperature-reduced combustion exhaust gas and treated with the exhaust gas treatment device. Wastewater recovery method for the plant.

[5] In any one of [1] to [4], the exhaust gas treatment device includes a dust collector and a catalyst denitration device that treats the exhaust gas removed by the dust collector, and between the dust collector and the catalyst denitration device. A wastewater recovery method for an incineration plant, wherein the temperature of the exhaust gas is not adjusted.

[6] The wastewater recovery method for an incineration plant according to any one of [1] to [5], wherein the flue gas temperature at the outlet of the heat recovery device is 230 ° C. or higher.

[7] An incinerator that burns organic matter, a heat recovery device that recovers the heat of the combustion exhaust gas discharged from the incineration device, a temperature reduction device that reduces the temperature of the combustion exhaust gas heat recovered by the heat recovery device, A wastewater recovery device for wastewater discharged from an incineration plant comprising an exhaust gas treatment device for processing combustion exhaust gas reduced in temperature by the temperature reduction device, wherein the water treatment clarifies the wastewater discharged from the incineration plant An apparatus, water supply means for supplying treated water from the water treatment device to the temperature reducing device, and reducing the combustion exhaust gas by blowing and evaporating the treated water fed into the combustion exhaust gas in the temperature reducing device. In a wastewater recovery apparatus of an incineration plant having a blowing means for heating, control for controlling the amount of water fed from the water treatment apparatus to the temperature reducing apparatus so that the combustion exhaust gas temperature at the outlet of the temperature reducing apparatus is 150 to 200 ° C means Waste water recovery system of incineration plants, characterized in that it comprises.

[8] In [7], the water treatment device includes a membrane separation device, and the control means is a means for controlling the water supply amount by adjusting a water recovery rate in the membrane separation device. Wastewater recovery equipment for incineration plants.

[9] A waste water recovery device for an incineration plant according to [8], wherein the membrane separation device is a reverse osmosis membrane separation device.

[10] In any one of [7] to [9], there is provided a chemical addition means for adding sodium bicarbonate and / or calcium hydroxide to the temperature-reduced combustion exhaust gas, and the sodium bicarbonate and / or A wastewater recovery apparatus for an incineration plant, wherein the exhaust gas to which calcium hydroxide is added is processed by the exhaust gas processing apparatus.

[11] In any one of [7] to [10], the exhaust gas treatment device includes a dust collector and a catalyst denitration device that treats the exhaust gas removed by the dust collector, and between the dust collector and the catalyst denitration device. A waste water recovery device for an incineration plant, wherein the temperature of the exhaust gas is not adjusted.

[12] The wastewater recovery apparatus for an incineration plant according to any one of [7] to [11], wherein the combustion exhaust gas temperature at the outlet of the heat recovery apparatus is 230 ° C. or higher.

According to the present invention, by controlling the amount of water supplied to the temperature reducing device so that the temperature at the outlet of the temperature reducing device is within a predetermined range, it is possible to stably and efficiently treat the reduced temperature combustion exhaust gas. In addition, heat recovery in the heat recovery apparatus can be performed stably and efficiently.

It is a block diagram of the incineration plant concerning an embodiment. It is a flowchart of an embodiment. It is a flowchart of an Example. It is a flowchart of a comparative example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Hereinafter, the temperature of the combustion exhaust gas discharged from the heat recovery device, the temperature reducing device, or the like may be simply referred to as “exit temperature”.

As shown in FIG. 1, the incineration plant to which the present embodiment is applied includes an incinerator 1 that combusts organic matter, a heat recovery device 2 that recovers heat of combustion exhaust gas discharged from the incinerator 1, and the heat recovery device. 2, a temperature reducing device 3 for further reducing the temperature of the combustion exhaust gas recovered in heat (hereinafter also referred to as heat recovery combustion exhaust gas), a dust collector 4 for removing dust from the reduced temperature combustion exhaust gas, Based on the measurement results of a catalytic denitration device 5 that decomposes and removes NOx gas, a water treatment device 6 that treats wastewater generated and discharged in the incineration plant, and a thermometer T that measures the outlet temperature of the temperature reducing device 3. A control device 7 that controls the amount of water supplied to the temperature reducing device 3 among the treated water treated by the water treatment device 6 is provided. However, you may have apparatuses other than the apparatus shown in figure.

In FIG. 1, the dust collector 4 and the catalyst denitration device 5 are provided as the exhaust gas treatment device, but the exhaust gas treatment device is not limited to these. For example, only the dust collector 4 may be used, or an activated carbon device may be provided after the catalyst denitration device 5.

As the incinerator 1, a stoker furnace, a fluidized bed furnace, a gasification melting furnace, an ash melting furnace, an incineration plant, or the like can be used.

The burning organic matter is not particularly limited, and examples thereof include municipal waste, industrial waste, sewage sludge, and waste wood. The combustion exhaust gas discharged from the incinerator 1 is usually at a temperature of about 800 to 1300 ° C.

The heat recovery device 2 recovers the heat of the combustion exhaust gas discharged from the incinerator 1. Examples of the heat recovery device 2 include a waste heat boiler. The outlet temperature of the heat recovery apparatus 2 is usually 230 ° C. or higher, particularly 250 ° C. or higher. If this temperature is less than 230 ° C., corrosion may occur. The upper limit of the outlet temperature of the heat recovery apparatus 2 is usually 400 ° C. or less from the viewpoint of heat recovery efficiency.

The temperature reducing device 3 further reduces the temperature of the combustion exhaust gas (heat recovery combustion exhaust gas) recovered by the heat recovery device 2. The temperature reducing device 3 sprays (or injects) the treated water from the water treatment device 6 onto the heat recovery combustion exhaust gas introduced from the heat recovery device 2 so that the temperature of the heat recovery combustion exhaust gas is reduced by the heat of vaporization of water. It is configured. As described above, the temperature of the heat recovery combustion exhaust gas introduced into the temperature reducing device 3, that is, the outlet temperature of the heat recovery device 2, is usually about 230 to 400 ° C.

In the present invention, the temperature of the outlet of the temperature reducing device 3, that is, the temperature of the combustion exhaust gas reduced in temperature by the temperature reducing device 3 is 150 to 200 ° C., preferably 160 to 190 ° C. The amount of water supplied from the processing device 6 to the temperature reducing device 3 and sprayed (or sprayed) is controlled. When the outlet temperature of the temperature reducing device 3 is lower than 150 ° C., clogging due to deliquescence (CaCl ₂ ) or low temperature corrosion of the dust collector occurs in the dust collector (bag filter) 4 at the subsequent stage. When this temperature is higher than 230 ° C., re-synthesis of dioxins occurs and the total amount of dioxins increases. The generated dioxin needs to be processed by the catalyst denitration device 5 or the activated carbon device at the subsequent stage, which increases the load of the exhaust gas processing device at the subsequent stage or requires a separate processing facility.

The exhaust gas reduced in temperature by the temperature reducing device 3 is neutralized by adding an acid gas treatment agent such as sodium bicarbonate (bicarbonate) or calcium hydroxide (slaked lime), and then removed by the dust collector 4.

When garbage is incinerated at an incineration plant, toxic gases such as HCl and SOx, dioxins, fly ash containing heavy metals, etc. are generated, and a process for treating these is required. In FIG. 1, sodium bicarbonate or slaked lime (may be dolomite hydroxide) is added in order to treat the acidic gas before the dust collector 4. In addition, when performing an acidic gas process in the temperature reduction apparatus 3 or a scrubber, well-known process means, such as neutralization process using alkalis, such as NaOH, are applied. Known methods are also applied in the dioxin treatment and fly ash treatment.

The relationship between the outlet gas of the temperature reducing device 3, that is, the gas composition of the inlet gas of the dust collector 4, etc., and suitable processing conditions is as follows.
Gas composition:
HCl (O ₂ : 12% conversion value) = 100 to 800 ppm, especially 200 to 600 ppm
SOx = 10-100ppm, especially 30-50ppm
Exhaust gas amount: 1,000 to 200,000 Nm ³ -dry / hr
Moisture content in exhaust gas: 10-40%
Acid gas treatment chemical addition amount:
Baking soda = 1.0 to 1.2 equivalents (HCl / SOx concentration of dust collector inlet gas)
Slaked lime = 2.0-4.0 equivalents (concentration of HCl and SOx in the dust collector inlet gas)

When baking acid is used for acid gas treatment, stable treatment is possible at an exhaust gas temperature of 150 to 200 ° C., particularly 180 to 200 ° C. The baking soda to be added preferably has a particle size of 30 μm or less, for example, 5 to 20 μm.

When using highly reactive slaked lime that has been subjected to activation (activation, specific surface area improvement) treatment, stable treatment at an exhaust gas temperature of 150 to 170 ° C. is possible. The slaked lime added preferably has a particle size of 10 μm or less, for example, 4 to 8 μm.

The exhaust gas removed by the dust collector 4 is then decomposed and removed by NOx in the gas by a catalytic reduction reaction in which the exhaust gas is brought into contact with the denitration catalyst as a mixed gas with ammonia in the catalyst denitration device 5, and the processing gas is discharged out of the system. .

The inlet gas temperature in the catalyst denitration device 5 is required to be 180 ° C. or higher, preferably 190 ° C. or higher, for example, 190 to 230 ° C. If the temperature is lower than this, NOx cannot be decomposed and removed, so that the exhaust gas is recycled. It is necessary to heat. The inlet gas conditions of the catalyst denitration device 5 are usually as follows.
Exhaust gas NOx concentration: 50-300ppm
Exhaust gas amount: 1,000 to 200,000 Nm ³ -dry / hr
Moisture content in exhaust gas: 10-40%

A water treatment apparatus for treating wastewater of an incineration plant suitable for the present invention will be described with reference to FIG. 2, but the water treatment apparatus according to the present invention is not limited to that shown in FIG.

In the present invention, the waste water discharged from the incineration plant means waste water generated within the site of the incineration plant. Examples of the waste water generated in the premises of the incineration plant include boiler blow water blown from the heat recovery device 2 such as a waste heat boiler, boiler maintenance filled in the can of the heat recovery device when stopped, and discharged before restarting In addition to canned water, cooling tower blow water, floor washing wastewater generated when washing floors in incineration plants, car wash wastewater generated when washing waste collection vehicles, domestic wastewater and miscellaneous wastewater are listed. Examples of miscellaneous wastewater include incineration residue generated from an incinerator 1 such as an incinerator, residue cooling wastewater that cools slag, and wastewater other than the above that does not contain a surfactant and oil generated in an incineration plant.

In FIG. 2, after treating the mixed waste water which mixed boiler canned water, boiler blow water, and cooling tower blow water (however, boiler canned water may be excluded) with the pre-processing apparatus 8, it is a membrane separation apparatus. In step 9, membrane separation is performed.

The miscellaneous wastewater is treated with the first pretreatment device 10A, then mixed with boiler canned water, boiler blow water, and cooling tower blow water, and supplied to the pretreatment device 8. Preliminary treatment of miscellaneous wastewater in this way suppresses the clogging of the membrane of the membrane separation device 9.

As the pretreatment device 8, a sand filter, a microfiltration (MF) membrane, an ultrafiltration (UF) membrane separation device, or the like can be used. By pretreating the mixed waste water in this way, the membrane of the membrane separation device 9 is prevented from being blocked. As the membrane separation device 9, a reverse osmosis (RO) membrane separation device is suitable.

As the first pretreatment device 10A for treating miscellaneous wastewater, at least one of neutralization, aggregation, precipitation, filtration, and biological treatment device is preferable.

Car wash wastewater and floor wash wastewater are treated by the second pretreatment device 10B that removes organic components for SS. The second pretreatment device 10B is preferably at least one of neutralization, aggregation, precipitation, filtration, and biological treatment device.

The concentrated water of the membrane separation device 9 and the treated water of the second pretreatment device 10B are supplied to the temperature reducing device 3.

In the present invention, the amount of treated water supplied to the temperature reducing device 3 (the amount of mixed water of the concentrated water of the membrane separation device 9 and the treated water of the second pretreatment device 10B in FIG. 2) is The controller (the control device 7 in FIG. 1) controls the outlet temperature of the temperature reducing device 3 to be 150 to 200 ° C., preferably 160 to 190 ° C.

Although there is no restriction | limiting in particular as this water supply amount control method, the water recovery rate of the membrane separation apparatus 9 is controlled, the amount of concentrated water supplied to the temperature reduction apparatus 3 is controlled, or the membrane of the membrane separation apparatus 9 is controlled. A method of controlling the amount of concentrated water by adjusting the number of modules and the amount of permeated water is preferable.

In each device in the water treatment device, by bypassing some devices, circulating the treated water of the subsequent device to the previous device, increasing or decreasing the amount of water supplied to the subsequent device and the residence time, etc. A method of adjusting the amount of treated water discharged from the water treatment device per hour can also be adopted. When it is desired to reduce the amount of water supplied, the amount of water returned to the pit or the amount of water used as the cooling water for the fly ash humidification or main ash cooling device may be increased. Conversely, in order to increase the amount of water supplied, it is also possible to mix industrial water and water from other processes.

In the present invention, a thermometer T for measuring the outlet gas temperature of the temperature reducing device 3 is provided, and based on the measured value of the thermometer T, the measured value of the thermometer T is 150 to 200 ° C., preferably 160 to 190. By controlling the amount of water supplied from the water treatment device 6 to the temperature reducing device 3 by the control device 7 so that the temperature becomes 0 ° C., the temperature of the exhaust gas that has been reduced in temperature is maintained at a predetermined temperature, and then the acidity It is possible to stably perform exhaust gas treatment such as gas treatment and deNOx treatment. That is, for example, the outlet gas temperature of the temperature reducing device 3 can be adjusted to a temperature suitable for the chemical used in the aforementioned acidic gas treatment, and the acidic gas treatment can be performed stably and efficiently.

Furthermore, even when the NOx removal process by the catalyst denitration apparatus is performed at the subsequent stage, the exhaust gas temperature flowing into the catalyst denitration apparatus is stabilized, so that a stable and efficient process can be performed.

For example, the temperature suitable for the NOx removal treatment in the catalyst denitration apparatus is 180 ° C. or higher, preferably 190 to 230 ° C. as described above, so that the preceding acid gas treatment is performed at 180 to 200 ° C. using baking soda. Further, temperature adjustment such as heating can be eliminated between the dust collector and the catalyst denitration device. Therefore, in this case, it is preferable to set the outlet temperature of the temperature reducing device to a range of 180 to 200 ° C. by controlling the amount of water supplied to the temperature reducing device.

As described above, the preferred temperature of the acid gas treatment with slaked lime is 150 to 170 ° C., which is lower than the temperature suitable for removing NOx in the catalytic denitration device. Therefore, when using slaked lime, the boiler is disposed between the dust collector and the catalytic denitration device. Reheating with steam or electricity may be required.

From this point of view, when NOx removal by the catalytic denitration device is performed after the acidic gas treatment, the acidic gas treatment is performed at 180 to 200 ° C. using baking soda, and the treatment gas is sent to the catalytic denitration device without heating. It is preferable to supply.

In the present invention, since the temperature at the outlet of the temperature reducing device can be kept within a certain range by controlling the amount of water supplied to the temperature reducing device, the heat recovery device at the preceding stage is based on the amount of waste water discharged from the incineration plant. Thus, there is no need to adjust the heat recovery amount or the heat recovery device outlet temperature, and the heat recovery device can also perform stable and efficient heat recovery. As described above, the outlet temperature of the heat recovery apparatus is preferably 230 ° C. or higher, particularly 230 to 400 ° C.

Below, it demonstrates in detail about the water treatment apparatus shown in FIG.
When the MF membrane or UF membrane separator is used in the pretreatment device 8, it is preferable to treat the MF or UF membrane concentrated water with the first pretreatment device 10A to remove the organic component from SS. However, the processing may be performed by the second preliminary processing apparatus 10B. By not spraying the MF or UF membrane concentrated water of the pretreatment device 8 with the temperature reducing device 3, the spray nozzle is prevented from being blocked and a stable temperature reduction treatment is possible.

Water treatment chemicals such as anti-corrosion agents, dispersants and slime control agents, condensate amine agents, and oxygen scavengers in boiler canned water, boiler blow water, and cooling tower blow water for stabilization and efficiency of treatment. It is included. As these chemicals, those that do not adversely affect the membrane treatment and contribute to the stabilization of the membrane treatment are selected, and the boiler can water, the boiler blow water, and the cooling tower blow water are pretreated in the pretreatment device 8. By performing only the RO membrane treatment, efficient membrane separation treatment can be performed without newly adding a water treatment chemical for the RO membrane treatment. In addition, when the chemical concentration is insufficient, a necessary chemical may be added.

Dispersant contained in boiler blow water and cooling water blow water becomes an impediment to the coagulation treatment. Therefore, when the boiler blow water and the cooling water blow water are caused to flow into the first pretreatment device 10A, the necessary amount of the flocculant is remarkably increased. In addition, the slime control agent has an adverse effect on the biological treatment, and there are cases where the biological activity is reduced. Therefore, by supplying these waters to the pretreatment device 8 without introducing them into the first pretreatment device 10A, the pretreatment device 10A can be reduced in size.

Car wash wastewater and floor washing wastewater are pretreated by the second pretreatment device 10B and then sprayed by the temperature reducing device 3. Car wash wastewater and floor wash wastewater may contain substances that block the MF membrane or RO membrane, such as oil and surfactant, and the concentration is not constant, making it difficult to perform membrane separation treatment stably. is there. Therefore, the car wash wastewater and the floor wash wastewater are treated by the second pretreatment device 10B having at least one of neutralization, aggregation, precipitation, filtration, and biological treatment equipment to remove SS components and organic components. After performing, it sprays with the temperature decreasing apparatus 3. FIG.

In the first and second pretreatment devices 10A and 10B, for the purpose of reducing the SS component and the organic component contained in the water to be treated, a flocculant is added to the waste water, and the suspended matter is mainly agglomerated. A filtration process such as sand filtration may be performed, or a precipitation step may be performed instead of filtration. Further, when the load is high, a pressure levitation process can be added. In order to appropriately perform the aggregation treatment, a pH adjustment step can be added. By carrying out a series of pretreatments in the first and second pretreatment devices 10A and 10B, aggregates are removed from the waste water, and SS components and organic components contained in the car wash wastewater and floor washing wastewater etc. Can be reduced.

In the first and second pretreatment apparatuses 10A and 10B, the submerged MF membrane separation apparatus can be used instead of the sand filtration apparatus to perform the treatment by the membrane separation activated sludge method. Aggregates captured by the submerged MF membrane separation device are extracted and then put into a garbage pit and incinerated by the incinerator 1.

In the water treatment apparatus shown in FIG. 2, the following effects are obtained.
Similarly to Patent Document 2, in the membrane separation device 9, the waste water discharged from the incineration plant is concentrated by the separation membrane to obtain concentrated water having a reduced volume, and this concentrated water is supplied to the temperature reducing device 3. The amount of concentrated water supplied to the temperature device 3 is small, and the temperature of the combustion exhaust gas introduced into the temperature reduction device 3 can be lowered. As a result, it is possible to increase the amount of heat recovered from the combustion exhaust gas in the heat recovery device installed on the upstream side of the temperature reducing device.

In the water treatment apparatus shown in FIG. 2, since the mixed waste water is subjected to membrane separation treatment by the RO membrane, the following effects can be obtained.

In boiler canned water, boiler blow water, and cooling water blow water, water treatment chemicals such as a dispersant and a slime control agent are contained in order to stabilize and increase the efficiency of the treatment. By selecting and using these chemicals that do not adversely affect the membrane treatment and contribute to stabilization of the membrane treatment, at the time of RO membrane treatment, without newly adding or almost no water treatment chemicals, A membrane separation process can be stably performed.

Especially, the dispersant contained in the boiler blow water and the cooling water blow water becomes an impediment to the coagulation treatment. Slime control agents have an adverse effect on biological treatment and may reduce biological activity. As shown in FIG. 2, after treating these waters with a simple pretreatment device consisting of sand filtration, MF membrane or UF membrane separation device, the size of the wastewater treatment facility is reduced by membrane separation treatment. Can do.

As shown in FIG. 2, wastewater is treated with a pretreatment device having at least one of neutralization, agglomeration, precipitation, filtration, and biological treatment equipment, and after removing SS components and organic components in the wastewater. By performing the concentration operation by membrane treatment, the organic component can be reduced by the SS content contained in the waste water, the separation membrane is not easily clogged, and the continuous use period of the separation membrane can be extended. Thereby, the exchange frequency of a separation membrane becomes low, concentrated water can be obtained efficiently, and the heat | fever of the combustion exhaust gas in an incineration plant can be collect | recovered more efficiently.

Examples of the flocculant used in the water treatment apparatus include iron-based flocculants such as ferrous sulfate, ferric sulfate, and ferric chloride, and aluminum-based flocculants such as aluminum sulfate (sulfuric acid band) and polyaluminum chloride (PAC). Examples thereof include a flocculant and a mixture thereof. The amount of the flocculant added can be adjusted as appropriate.

Examples of the polymer flocculant to be added to the water to be treated as a flocculant include poly (meth) acrylic acid, a copolymer of (meth) acrylic acid and (meth) acrylamide, and anions such as alkali metal salts thereof. Organic polymer flocculants, nonionic organic polymer flocculants such as poly (meth) acrylamide, dimethylaminoethyl (meth) acrylate or its quaternary ammonium salt, dimethylaminopropyl (meth) acrylamide or its 4 Homopolymers composed of cationic monomers such as quaternary ammonium salts, and cationic organic polymer flocculants such as copolymers of nonionic monomers copolymerizable with these cationic monomers, and the above anionic monomers, Copolymerization with cationic monomers and nonionic monomers copolymerizable with these monomers Organic polymer flocculant of amphoteric is united and the like. The amount of the polymer flocculant added is not particularly limited, and may be adjusted according to the properties of the water to be treated. However, the solid content is generally 0.01 to 10 mg / L with respect to the water to be treated. A phenol type flocculant described in International Publication WO2011 / 018978 can also be used.

When the RO membrane is used in the membrane separation device 9, examples of impurities removed by the RO membrane include ionic components and organic substances. Examples of ionic components include cationic substances, anionic substances, and the like. Specifically, calcium ions, magnesium ions, etc. that easily form scales that are ion-bonded to anions and are not easily dissolved in water. Illustrated. Moreover, as an organic substance, the water-soluble organic substance etc. which are melt | dissolving in the waste_water | drain are mentioned.

When the MF membrane separation device is used in the pretreatment device 8, the MF membrane differential pressure increases due to adhesion of scale, turbidity, organic matter, etc. to the MF membrane surface. In this case, back pressure cleaning and chemical cleaning of the MF membrane are performed. In the back pressure cleaning of the MF membrane, it is preferable to periodically / irregularly wash with water containing hypochlorite such as sodium hypochlorite in that the increase in the MF membrane differential pressure can be further suppressed. .

MF membranes usually have pores with a pore size of about 50 nm to 10 μm. As the MF membrane, for example, a membrane unit in which a hollow fiber membrane, a spiral membrane, and a tubular membrane are held in a vessel can be used. A hollow fiber membrane or a flat membrane can be used as it is by immersing it in the water to be treated. Instead of the MF membrane, a UF membrane having a pore diameter of about 2 to 200 nm can also be used.

The MF membrane is preferably PVDF, the UF membrane is polysulfone, and the RO membrane is preferably made of polyamide, but is not limited thereto.

Examples of the RO membrane include a composite membrane composed of a dense layer of an asymmetric membrane and a fine porous layer.

As the RO membrane unit, a unit in which a filtration membrane installed in a state of a hollow fiber membrane, a spiral membrane, a tubular membrane or the like is held in a vessel can be used.

Dispersants used for cooling water treatment etc. include inorganic polyphosphoric acids such as sodium hexametaphosphate and sodium tripolyphosphate, phosphonic acids such as hydroxyethylidene diphosphonic acid and phosphonobutane tricarboxylic acid, maleic acid, acrylic acid, itaconic acid, etc. Carboxyl group-containing material, and optionally combined with vinyl monomers having sulfonic acid groups such as vinyl sulfonic acid, allyl sulfonic acid, 2-methacrylamide-2-methylpropane sulfonic acid, and nonionic vinyl monomers such as acrylamide Copolymers and the like can be used, but materials other than those listed here can also be applied. Further, as the third component of the dispersant, a terpolymer can be used by using other components. For example, N-tert-butylacrylamide is used as the third component. Among them, the dispersant is most preferably a polymer containing HAPS, AMPS and acrylic acid and / or methacrylic acid. (HAPS is 3-allyloxy-2-hydroxy-1-propanesulfonic acid, and AMPS is 2-acrylamido-2-methylpropanesulfonic acid.)

The molecular weight of the dispersant is preferably 1,000 or more and 30,000 or less. If the molecular weight is less than 1,000, a sufficient dispersion effect cannot be obtained, and if it exceeds 30,000, it may be removed by the pretreatment film.

Slime control agents include hypochlorites such as sodium hypochlorite (NaClO), chlorine agents such as chlorine gas, chloramine, and chlorinated isocyanurates, chlorine such as monochlorosulfamic acid, amide sulfate, and amide sulfate. Bonded chlorine agent reacted with a compound having hydrogen, bromine agent such as dibromohydantoin, hypobromite such as sodium hypobromite, organic agent such as DBNPA (dibromonitrilopropionate), MIT (methylisothiazolone) . Examples of the chlorine-based oxidizing agent that can be used in the present invention include the above chlorine gas, hypochlorous acid or a salt thereof, chlorous acid or a salt thereof, chloric acid or a salt thereof, perchloric acid or a salt thereof, chlorinated isocyanur. An acid or a salt thereof can be used. Examples of the salt include alkali metal salts such as sodium and potassium, alkaline earth metal salts such as barium, other metal salts such as nickel, ammonium salts, and the like. One or more of these can be used. Among these, sodium hypochlorite is preferable because of its excellent handleability.

Nitrogen compounds to which free chlorine is bound include ammonia or its compounds, melamine, urea, acetamide, sulfamide, cyclolamic acid, sulfamic acid, toluenesulfonamide, succinimide, phthalimide, isocyanuric acid, N-chloro Examples thereof include toluenesulfonamide, uric acid, saccharin, and salts thereof. The bonded chlorine agent used in the present invention is a compound in which the above-mentioned free chlorine is bonded to these nitrogen compounds. As the combined chlorine agent used in the present invention, those obtained by mixing and reacting the above nitrogen compound and free chlorine agent, particularly those obtained by mixing and reacting each in the state of an aqueous solution are preferable.

Examples of such bonded chlorinating agents include chloramine, chlorinated oxidant and sulfamic acid compound, chloramine-T (sodium salt of N-chloro-4-methylbenzenesulfonamide), chloramine-B. (Sodium salt of N-chloro-benzenesulfonamide), sodium salt of N-chloro-paranitrobenzenesulfonamide, trichloromelamine, sodium salt or potassium salt of mono- or di-chloromelamine, trichloro-isocyanurate, mono- or 5 such as sodium salt or potassium salt of di-chloroisocyanuric acid, sodium salt or potassium salt of mono- or di-chlorosulfamic acid, monochlorohydantoin or 1,3-dichlorohydantoin, 5,5-dimethylhydantoin 5-alkyl derivatives.

In boiler water treatment, cleansing agents, oxygen scavengers, and amines are used alone or in combination. Examples of the canning agent include phosphoric acid and / or salt thereof, polymerized phosphoric acid and / or salt thereof, phosphonic acid and / or salt thereof, chelating agent such as EDTA, poly (meth) acrylic acid and / or salt thereof, and AMPS. And a polymer containing acrylic acid and / or methacrylic acid can be applied. Examples of the oxygen scavenger include 1-amino-4-methylpiperazine, hydrazine, carbohydrazide, erythorbic acid and / or its salt, gluconic acid and / or its salt, N, N-diethylhydroxylamine, sulfurous acid and / or its salt Bisulfite and / or a salt thereof, tannic acid and / or a salt thereof, gallic acid and / or a salt thereof, isopropylhydroxylamine and the like can be applied. Examples of amines include neutralizing amines such as monoisopropanolamine, 3-methoxy-propylamine, cyclohexylamine, 2-aminoethanol, 2-amino-2-methyl-1-propanol, morpholine, 2-diethylaminoethanol, and the like. A film-forming amine such as octadecylamine can be applied.

A part of the MF membrane permeated water of the pretreatment device 8 can be used as car wash water. The RO membrane permeated water of the membrane separation device 9 can be used as boiler raw water for waste heat boilers, equipment cooling water, plant water, and the like. Permeated water such as the MF membrane permeated water and the RO membrane permeated water may be discharged to the sea, rivers, sewage, or the like.

Since the catalyst denitration device that removes NOx gas from combustion exhaust gas uses ammonia, ammonia remains in the exhaust gas after treatment, so the waste water discharged from the incineration plant contains ammonia (ammonium ions). May be. Therefore, a biological treatment device may be provided on the upstream side of the pretreatment device 8 to reduce ammonium ions and the like. In this case, as the biological treatment apparatus, for example, a biological treatment provided with a nitrification tank that performs a nitrification process using aerobic microorganisms and a denitrification tank that performs a denitrification process using facultative anaerobic microorganisms. A device or the like can be used.

Hereinafter, the present invention will be described more specifically with reference to examples.

[Example 1]
The combustible waste incineration plant shown in FIG. 1 was operated under the following conditions.
Heat recovery device 2 outlet temperature: 230 ° C
Temperature reducing device 3 outlet temperature: 188 ° C
Temperature difference between heat recovery device 2 outlet temperature and temperature reduction device 3 outlet temperature: 42 ° C

Boiler blow water, cooling tower blow water, miscellaneous waste water, domestic waste water, car wash waste water and floor washing waste water discharged from the incineration plant at the following flow rates were treated according to the flow of FIG.
Boiler blow water: 9m ³ / day
Cooling tower blow water: 9m ³ / day
Miscellaneous drainage: 13m ³ / day
Domestic wastewater: 11m ³ / day
(Total above: 42 m ³ / day)
Total of car wash wastewater and floor wash wastewater: 6.5 m ³ / day

Boiler blow water and cooling tower blow water were supplied as they were to the pretreatment (MF membrane separation device 11).

The miscellaneous wastewater was treated with the first pretreatment device (flocculation treatment device 13 and gravity two-layer sand filtration treatment device 14 by adding PAC 10 mg / L and high polymer 2 mg / L), and then supplied to the MF membrane separation device 11. The permeated water (water recovery rate 95%) of the MF membrane separator 11 was supplied to the RO membrane separator 12, and the permeated water (water recovery rate 80%) was supplied to the cooling tower as make-up water.

RO concentrated water 0.33 m ³ / hr was supplied to the temperature reducing device 3 and sprayed. The concentrated water of the MF membrane separation device 11 was supplied to the aggregation treatment device 13.

The domestic wastewater was treated with the biological treatment device 15 and then supplied to the first preliminary treatment device.

Car wash wastewater and floor washing wastewater are treated with the second pretreatment device (flocculation treatment device 16 with PAC 10 mg / L and high polymer 2 mg / L and gravity two-layer sand filtration treatment device 17), and then the temperature reduction device 3 And sprayed (0.27 m ³ / hr).
All of the above amounts of drainage were average values, and actually varied within a range of ± 20%. The same applies to Examples and Comparative Examples described later.

The boiler blow water contains a dispersant, and the cooling water blow water contains a dispersant and a slime control agent. After the mixed waste water containing these is treated by the MF membrane separator 11, the RO membrane separator 12 performs the treatment. Thus, the treatment can be stably performed without adding the slime control agent and the dispersant in the RO membrane treatment. By treating floor washing wastewater and car washing wastewater separately from these systems, the water recovery rate of the RO membrane separation device 12 could be increased. The permeated water of the RO membrane separation device 12 can be reused as the replenishing water for the cooling water, and the amount of the replenishing water is reduced accordingly.

While controlling the water recovery rate of the RO membrane separation device 12 in this water treatment device to be always 80%, adjusting the amount of treated water in each treatment device, reducing the total drainage amount (returning to the cooling tower pit, (Applied to humidifier and main ash cooling device) and controlled so that the amount of water supplied to the temperature reducing device 3 is constant at 0.60 m ³ / hr, and the outlet temperature of the temperature reducing device is set to 188 ° C. as described above. Maintained.

The processing conditions in the dust collector 4 are as follows.

<Dust collector inlet acid gas treatment conditions>
Exhaust gas amount: 30,000 Nm ³ -dry / hr
Inlet HCl concentration: 380 ppm (O ₂ : 12% conversion value)
Inlet SOx concentration: 50ppm
Moisture content: 20%

<Dust collector outlet acid gas treatment concentration (regulated value)>
Outlet HCl concentration: 35 ppm (O ₂ : 12% conversion value)
Outlet SOx concentration: 10ppm

<Additional amount of baking soda (particle size: 7 to 13 μm)>
Addition amount: 54 kg / hr, equivalence ratio: 1.00 (to inlet HCl, SOx)

In the present example, the acidic gas treatment was performed while maintaining the outlet temperature of the temperature reducing device 3 constant.
The exhaust gas (about 200 ° C.) after the dust removal treatment is fed to the catalyst denitration device 5 using a catalyst in which platinum is supported on a vanadium oxide honeycomb, and NOx is efficiently removed without heating. .

[Example 2]
In Example 1, acid gas treatment was performed by adding slaked lime under the following conditions instead of baking soda.
<Addition amount of slaked lime (particle size 4-8 μm)>
Amount added: 60 kg / hr, equivalence ratio: 2.52 (to inlet HCl, SOx)
In the case of treatment with slaked lime, the exhaust gas temperature is preferably 150 to 170 ° C., so that the water recovery rate of the RO membrane separation device 12 is 65%, the RO concentrated water amount is 0.58 m ³ / hr, and the water supply amount to the temperature reducing device is Example 1 except that it was controlled to 0.85 m ³ / hr and the temperature reducing device outlet temperature was 170 ° C. (temperature difference between the heat recovery device 2 outlet temperature and the temperature reducing device 3 outlet temperature: 60 ° C.). Processing was carried out in the same manner.

As a result, the catalyst denitration apparatus required a little reheating, but otherwise, the same efficient treatment as in Example 1 was performed.

The amount of boiler steam used for reheating (about 200 ° C.) in the catalyst denitration apparatus was 2.4 t / day, and 72 t in one month. This amount of steam used corresponds to 69301 (ΔT: 30 ° C. loss) kWh as a power generation loss.

[Comparative Example 1]
In Example 2, when the water recovery rate of the RO membrane separation device was not controlled and the water supply amount to the temperature reducing device was not controlled, the fluctuation of the drainage amount and the fluctuation of the water recovery rate of the RO membrane separation device were accompanied. Thus, the amount of water supplied from the RO membrane separator varied between 0.47 and 0.67 m ³ / hr, and the amount of water delivered to the temperature reducing device varied within the range of 0.74 to 0.94 m ³ / hr.

As a result, the temperature reduction device outlet temperature fluctuated between 165 and 179 ° C. (temperature difference between the heat recovery device outlet temperature and the temperature reduction device outlet temperature: 51 to 65 ° C.).

When the amount of water fed to the temperature reducing device was too small, the temperature at the outlet of the temperature reducing device became too high, and it was necessary to add an excessive amount of slaked lime as follows in order to perform an appropriate acid gas treatment.
<Addition amount of slaked lime (particle size 4-8 μm)>
Addition amount: 74 kg / hr, equivalence ratio: 3.11 (to inlet HCl, SOx)

Since the dioxins were re-synthesized due to the high temperature, it was necessary to treat dioxins separately (increase the load in the catalyst denitration equipment or further activated carbon treatment).

When the amount of water supplied to the temperature reducing device was too large, the temperature before the dust collector became too low, and it was necessary to adjust the reheating temperature at the catalyst denitration device inlet. In this case, it is necessary to constantly control the reheating conditions, the NOx treatment is also unstable, and energy loss for temperature rise occurs.

In particular, when the amount of water supplied is too small and the temperature in front of the dust collector becomes high, it is necessary to add slaked lime excessively, so the chemical must be changed to baking soda.

[Comparative Example 2]
Each waste water of the incineration plant of Example 1 was treated according to the flow of FIG. 4 and performed in the same manner as in Example 1 except that control of water supply to the temperature reducing device 3 was not performed. That is, each of the above-mentioned wastewaters other than domestic wastewater (each flow rate is the same as in Example 1) was directly treated by the flocculation treatment device 21 by adding PAC 200 mg / L and high polymer 2 mg / L. About domestic wastewater, after processing with the biological treatment apparatus 25, it supplied to the coagulation treatment apparatus 21. FIG. The treated water of the agglomeration treatment device 21 is processed by the gravity two-layer sand filtration treatment filtration device 22, and then supplied to the MF membrane separation device 23, the permeate is supplied to the RO membrane separation device 24, and the RO permeate is supplied to the cooling tower. Used as water. The concentrated water of the MF membrane separator 23 and the concentrated water of the RO membrane separator 24 were sprayed by the temperature reducing device 3.

In Comparative Example 2, since the raw water amount of the RO membrane separation device 24 greatly fluctuates and the water quality greatly fluctuates in addition to the fluctuation of the drainage amount, the water recovery rate of the RO membrane separation device 24 varies in the range of 45 to 65%. However, since the water recovery rate of the RO membrane separation device was not controlled, the amount of water supplied to the temperature reducing device varied greatly between 1.07 and 0.68 m ³ / hr.

As a result, the temperature reducing device outlet temperature fluctuates greatly at 156 to 183 ° C. (temperature difference between the heat recovery device outlet temperature and the temperature reducing device outlet temperature: 47 to 74 ° C.). The problem caused by fluctuations in

In Comparative Example 2, since oil was mixed from the floor washing wastewater and the car washing wastewater, the water recovery rate of the RO membrane separation device 24 decreased to 15 to 35% as the treatment continued. In addition, the amount of water for the agglomeration treatment increased, and a huge pretreatment facility was required.

The amount of PAC added was 200 mg / L because of the dispersant contained in the boiler blow water and cooling water blow water. In addition, a slime control agent and a dispersant are necessary for stabilizing the membrane treatment. As a membrane treatment slime control agent, Krivater EC-503 5 mg / L was used. As the membrane treatment dispersant, Krivator N-500 5 mg / L was used.

[Comparative Example 3]
In Comparative Example 2, the same procedure was performed except that the MF membrane separation device 23 and the RO membrane separation device 24 were omitted. However, although the variation in the amount of water supplied to the temperature reducing device was small, the amount of water supplied was 1.9 m ³ / hr. Therefore, the heat recovery device outlet temperature is 305 ° C., whereas the temperature reducing device outlet temperature is 170 ° C. (temperature difference between the heat recovery device outlet temperature and the temperature reducing device outlet temperature: 135 ° C.), which is very low. Value.

For this reason, it was necessary to increase the amount of drug added in the acid gas treatment or to change the drug. In addition, power loss occurred due to reheating in the catalyst denitration equipment.

Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2016-181746 filed on Sep. 16, 2016, which is incorporated by reference in its entirety.

Claims

An incinerator for burning organic matter, a heat recovery device for recovering the heat of the combustion exhaust gas discharged from the incineration device, a temperature reducing device for reducing the temperature of the combustion exhaust gas heat recovered by the heat recovery device, and the temperature reduction A wastewater recovery method for wastewater discharged from an incineration plant equipped with an exhaust gas treatment device for treating combustion exhaust gas reduced in temperature by the device,
A water treatment step for clarifying waste water discharged from the incineration plant, a water supply step for sending treated water of the water treatment step to the temperature reducing device, and the combustion in the temperature reducing device In a wastewater recovery method for an incineration plant having a temperature reducing step for reducing the temperature of the combustion exhaust gas by blowing it into the exhaust gas and evaporating it,
A method for recovering wastewater from an incineration plant, characterized in that the amount of water supplied to the temperature reducing device in the water treatment step is controlled so that the combustion exhaust gas temperature at the outlet of the temperature reducing device is 150 to 200 ° C.
The wastewater recovery method for an incineration plant according to claim 1, wherein the water treatment step includes a membrane separation step, and the water supply amount is controlled by adjusting a water recovery rate in the membrane separation step.
3. The wastewater recovery method for an incineration plant according to claim 2, wherein the membrane separation step is a reverse osmosis membrane separation step.
The wastewater of an incineration plant according to any one of claims 1 to 3, wherein sodium bicarbonate and / or calcium hydroxide is added to the reduced temperature of the combustion exhaust gas, and the exhaust gas treatment device treats the exhaust gas. Collection method.
5. The exhaust gas treatment device according to claim 1, wherein the exhaust gas treatment device includes a dust collector and a catalyst denitration device that treats the exhaust gas removed by the dust collector, and the exhaust gas is disposed between the dust collector and the catalyst denitration device. The waste water recovery method of an incineration plant characterized by not adjusting the temperature of this.
6. A method for recovering wastewater from an incineration plant according to any one of claims 1 to 5, wherein the flue gas temperature at the outlet of the heat recovery device is 230 ° C or higher.
An incinerator for burning organic matter, a heat recovery device for recovering the heat of the combustion exhaust gas discharged from the incineration device, a temperature reducing device for reducing the temperature of the combustion exhaust gas heat recovered by the heat recovery device, and the temperature reduction A wastewater recovery device for wastewater discharged from an incineration plant equipped with an exhaust gas treatment device for treating combustion exhaust gas reduced in temperature by the device,
A water treatment device for clarifying waste water discharged from the incineration plant, water supply means for supplying treated water of the water treatment device to the temperature reducing device, and the combustion in the temperature reducing device for supplying the treated water to the temperature reducing device In a wastewater recovery apparatus for an incineration plant having blowing means for reducing the temperature of the combustion exhaust gas by blowing it into the exhaust gas and evaporating it,
A wastewater recovery apparatus for an incineration plant, comprising control means for controlling the amount of water fed from the water treatment apparatus to the temperature reducing apparatus so that the combustion exhaust gas temperature at the outlet of the temperature reducing apparatus is 150 to 200 ° C.
8. The incineration plant according to claim 7, wherein the water treatment device includes a membrane separation device, and the control means is a means for controlling the amount of water supplied by adjusting a water recovery rate in the membrane separation device. Wastewater recovery equipment.
9. The wastewater recovery device for an incineration plant according to claim 8, wherein the membrane separation device is a reverse osmosis membrane separation device.
10. The method according to claim 7, further comprising chemical addition means for adding sodium bicarbonate and / or calcium hydroxide to the temperature-reduced combustion exhaust gas, the sodium bicarbonate and / or calcium hydroxide. A wastewater recovery device for an incineration plant, wherein the exhaust gas to which is added is treated by the exhaust gas treatment device.
11. The exhaust gas treatment device according to claim 7, wherein the exhaust gas treatment device includes a dust collector and a catalyst denitration device that treats the exhaust gas removed by the dust collector, and the exhaust gas is disposed between the dust collector and the catalyst denitration device. Waste water recovery device for an incineration plant, characterized in that no temperature adjustment is performed.
The wastewater recovery apparatus for an incineration plant according to any one of claims 7 to 11, wherein the exhaust gas temperature at the outlet of the heat recovery apparatus is 230 ° C or higher.