JPH1052699A - Method for treating organic sludge slurry liquid and method for treating organic sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an org. sludge slurry liq. having excellent spraying characteristics by a method wherein a filter cake obtd. in a filtering process is made into fine particles and/or dissolved in a water medium incorporated with an alkali and/or a surface active agent and the water medium obtd. contg. sludge is added into the org. sludge slurry liq. SOLUTION: A raw material org. sludge is introduced into a liquified process 11, where it is heated with high temp. steam fed from a line 27 to liquify it, and then, the high temp. and high pressure sludge slurry liq. is introduced into a flash process 12, where water content in the sludge slurry liq. is evaporated to make a conc. liq. by concentrating it through this water evaporation. The conc. liq. obtd. is introduced into a centrifugal process 18, where it is separated into a highly conc. liq. of sludge slurry and separated water, and then, the highly conc. liq. of sludge slurry is introduced into a filtering process 19, where screen filtering is performed. Then, filtered cake is introduced into a dispersing and dissolving process 20, where it is put into a water medium to make it into fine particles and/or to dissolve it. In addition, the sludge slurry liq. from the filtering process 19 is introduced into a combustion process, where it is sprayed for combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for treating organic sludge slurry and a method for treating organic sludge.

[0002]

2. Description of the Related Art Sewage sludge, a typical organic sludge, is:
Approximately 50 million m ³ annually throughout Japan (based on concentrated sludge: water content 9)
8%), which is increasing year by year.
Generally, organic sludge such as sewage sludge contains large amounts of organic substances such as proteins, fats and carbohydrates together with water, so it is easy to rot, and it is necessary to stabilize, detoxify, and reduce its volume from the viewpoint of preventing odors and public health. It has been. Many sewage treatment plants in large cities burn sludge from the viewpoint of difficulty in securing landfills. According to Japanese Patent Application Laid-Open No. 7-35318, a method is proposed in which an organic sludge is previously subjected to high-temperature and high-pressure treatment to form an organic sludge slurry liquid, and then the sludge slurry liquid is subjected to a combustion treatment. Have been. According to this method,
Since organic sludge is supplied to the combustion furnace as sludge slurry with good fluidity, a spray combustion method with good combustion efficiency can be adopted for the combustion treatment, which makes it possible to reduce the size of the combustion furnace and operate it. There is an advantage that it becomes easy. In this method, usually, the sludge slurry liquid is once discharged into a low-pressure flash tank in order to increase the flame temperature during combustion, where the steam is evaporated and concentrated. Then, the obtained sludge slurry concentrate is supplied to a combustion furnace, and spray combustion is performed.

However, this sludge slurry liquid contains:
Generally, it has been found that the sludge in the form of coarse particles is contained, and therefore, the spray characteristics of the sludge slurry are poor, and the spray nozzle may be blocked when spraying and burning the sludge.

[0004]

SUMMARY OF THE INVENTION The present invention provides a method for treating an organic sludge slurry to obtain an organic sludge slurry having excellent spray characteristics, and a method for treating organic sludge including the method. Is the subject.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, in the method for treating an organic sludge slurry, (a) the organic sludge slurry is filtered using a screen to include a filter cake composed of coarse sludge particles and fine sludge particles. A filtration step of separating into a filtrate composed of a sludge slurry liquid, and (b) a filter cake for forming fine particles and / or dissolving the filter cake obtained in the filtration step in an aqueous medium to which an alkali and / or a surfactant is added. (C) adding an aqueous medium containing the sludge obtained in the filter cake dispersing / dissolving step in the form of fine particles and / or dissolved to an organic sludge slurry liquid to be supplied to the filtering step. Or an adding step of adding the filtrate to the filtrate obtained in the above-mentioned filtration step. Also,
According to the present invention, in the method for treating organic sludge showing a solid state, (i) the organic sludge is treated with high-temperature steam to form
While indirectly heating to a reaction temperature of 0 to 275 ° C,
A liquefaction step of liquefying while maintaining the pressure at or above the saturated steam pressure at the reaction temperature, (ii) a concentration step of obtaining a concentrated liquid from the sludge slurry liquid obtained in the liquefaction step,
(Iii) a combustion step of burning the sludge slurry concentrate obtained in the concentration step, and (iv) a high-temperature steam that supplies the high-temperature flue gas obtained in the combustion step to a waste heat boiler to generate high-temperature steam. (Vi) a high-temperature steam supply step in which the high-temperature steam obtained in the high-temperature steam generation step is sent to the liquefaction step through a flow control valve and used as a heat source for indirect heating of organic sludge; The amount of high-temperature steam supplied to the liquefaction step is adjusted by a flow control valve in relation to the reaction temperature of the liquefaction step so that the reaction temperature of the liquefaction step is always 1
Adjusting the high-temperature steam amount in the range of 50 to 275 ° C.,
Prior to supplying the concentrated sludge slurry obtained in the concentration step to the combustion step, (a) filtering using a screen, a filter cake comprising coarse sludge particles,
A filtration step of separating into a filtrate consisting of a sludge slurry liquid containing fine sludge particles, (b) forming the filter cake obtained in the filtration step into fine particles in an aqueous medium to which an alkali and / or a surfactant has been added and / or Dispersion of filter cake to be dissolved
The dissolving step and (c) adding the aqueous dispersion or solution of the sludge obtained in the dispersing / dissolving step to the organic sludge slurry liquid to be supplied to the filtering step, or passing through the adding step of adding to the filtrate. Thereafter, a method for treating organic sludge, which is supplied to the combustion step, is provided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As the organic sludge slurry used in the present invention, a sludge slurry obtained from an organic sludge liquefaction step or a concentrate thereof, which is a concentrate thereof, is used. The sludge slurry liquid in this case can be obtained by maintaining the organic sludge liquid showing a solid state under high temperature and high pressure conditions. Hereinafter, the organic sludge liquefaction step will be described in detail. Organic sludge in the solid state used as a raw material to be treated in the organic sludge liquefaction process includes sewage sludge discharged from ordinary sewage treatment plants and excess sludge discharged from various organic wastewater biological treatment devices. And organic solid sludge discharged from various manufacturing processes. Organic sludge is usually dehydrated by mechanical dehydration (vacuum dehydration, pressure dehydration, screw press dehydration, belt press dehydration, centrifugal dehydration, etc.)
Is used, but is not particularly limited. However, it is desirable to add sludge conditioning chemicals to the organic sludge before dehydration.
The addition of a polymeric flocculant is advantageous. Therefore, regarding the dehydration method, belt press dehydration or centrifugal dehydration, which is suitable for adding a polymer flocculant, is desirable. The organic sludge is dehydrated so that the moisture content of the obtained dewatered sludge is in the range of 60 to 90% by weight, preferably 65 to 75% by weight.

[0007] In order to liquefy organic sludge showing a solid state, high-temperature steam is used as a heating medium and organic sludge is reduced to 15%.
Indirect heating is performed to a reaction temperature of 0 to 275 ° C, preferably 250 to 275 ° C, and the pressure is maintained at a pressure equal to or higher than the saturated steam pressure at the reaction temperature. This liquefaction step can be performed, if necessary, in the presence of an alkaline substance as a liquefaction accelerator. This alkaline substance is contained in an amount of 0 to 20% by weight, preferably 0 to 20% by weight, based on the solid content in the organic sludge.
It is preferred to add at a ratio of ５5% by weight. Examples of the alkaline substance include, for example, alkali metal compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, sodium formate, potassium formate, calcium oxide, calcium hydroxide, and hydroxide. And alkaline earth metal compounds such as magnesium. The time for keeping the organic sludge under the reaction conditions varies depending on the type of the target sludge, but is generally within 120 minutes, usually 0 to 60 minutes. The liquefaction apparatus may be any indirect heating type heat exchange type reactor, but since it handles sludge having a solid state, a scrape type heat exchange type reactor having a scraper inside and a screw type having a helical blade are used. The use of a heat exchange reactor is preferred. As the pressure in the liquefaction reaction, a self-generated pressure due to water vapor from sewage sludge can be used. However, if necessary, the pressure can be increased using, for example, nitrogen gas, carbon dioxide gas, argon gas, or the like. The sludge slurry liquid obtained in this way has very good fluidity,
Pumping is sufficiently possible.

[0008] In the method of the present invention, the sludge slurry obtained from the organic sludge liquefaction step or the concentrate thereof is subjected to a filtration treatment using a screen to obtain a filter cake comprising coarse sludge particles and a fine sludge. It is separated into a filtrate consisting of a sludge slurry containing particles. The size of the mesh of the screen is smaller than the pore size of the spray nozzle used in the combustion step, and is usually 0.25 to 2 mm, preferably 0.25 to 1 mm. By this filtration process, among the sludge particles contained in the sludge slurry liquid, coarse particles having a particle size larger than the mesh size of the screen are separated on the screen, and the screen is composed of the coarse sludge particles. A filter cake is formed.

In the present invention, the filter cake obtained in this filtration step is atomized and / or dissolved in an aqueous medium to which an alkali and / or a surfactant has been added, so that the sludge is in the form of fine particles and / or dissolved. To obtain an aqueous medium containing In order to make the sludge cake fine and / or dissolved in the aqueous medium, the sludge cake may be put into the aqueous medium and stirred. The proportion of the aqueous medium used is 50 to 500 parts by weight, preferably 100 to 300 parts by weight, based on 100 parts by weight of sludge (dry matter basis).
It is the ratio of parts by weight. In this case, examples of the alkali to be added to the aqueous medium include alkali metal compounds (such as sodium hydroxide, potassium hydroxide and sodium carbonate), alkaline earth metal compounds (such as calcium hydroxide and magnesium hydroxide), and ammonium hydroxide. Further, examples of the surfactant include a nonionic surfactant and an anionic surfactant. Coarse-particle sludge, which is contained in the sludge slurry liquid and induces blockage of the spray nozzle, is formed in such a manner that a large number of fine particles are adhered by organic matter. The sludge is filtered by the filtration step to form a filter cake. The filter cake is poured into an aqueous medium to which an alkali and / or a surfactant has been added, and the mixture is stirred to dissolve the organic substance adhering to the fine particles, or It is considered that the adhesive force is weakened, so that the coarse particles are dispersed in many fine particles. In addition,
When an aqueous medium to which no alkali or surfactant is added, for example, water, is used, the above-mentioned effects such as making the coarse particles fine are not achieved. The aqueous medium used in the present invention is usually prepared by adding the above alkali to water in an amount of 1 to 1
A solution in which 0% by weight is dissolved, usually a solution in which approximately 3% by weight is dissolved, or a solution in which the above-mentioned surfactant is dissolved in 0.25 to 5% by weight, usually a solution in which approximately 1% by weight is dissolved are used. It should be noted that even a solution in which a surfactant is dissolved together with an alkali in water may be used as an aqueous medium,
A water-soluble organic solvent such as alcohol can also be mixed. The aqueous medium containing the sludge thus obtained in the form of fine particles and / or dissolved is added to the sludge slurry sent to the filtration step or to the filtrate obtained in the filtration step. According to the present invention, the sludge slurry sent to the combustion step does not contain coarse particles, and therefore has excellent spray characteristics, and does not block the spray nozzle of the combustion burner.

In the present invention, it is preferable to use a concentrated liquid of an organic sludge slurry as a raw material for the filtration treatment.
Hereinafter, a concentration method for obtaining a concentrated liquid from a high-temperature organic sludge slurry liquid in a pressurized state obtained in the organic sludge liquefaction step will be described in detail. To concentrate the sludge slurry from the organic sludge liquefaction process, discharge this sludge slurry into the flash tank (flash)
Then, water contained in the slurry liquid is evaporated to obtain a concentrated liquid. The pressure in the flash tank is 5 atmospheres or less,
Preferably it is normal pressure. In FIG. 1, from the sludge slurry liquid,
FIG. 3 is an explanatory diagram of a flash step for obtaining the concentrated liquid. In FIG. 1, 1 denotes a flash tank, 2 denotes a controller, 3 denotes a liquid level detector, 4 denotes a liquid level control valve, F denotes a concentrated liquid, and S denotes a liquid level of the concentrated liquid. Is shown. The sludge slurry liquid is flushed from the middle part of the flash tank through the line 5 into the low-pressure flash tank 1 in which the sludge slurry concentrate is retained. The temperature of the sludge slurry liquid is at most 150 ° C., and its pressure is at most 5 atm. The sludge slurry liquid flushed into the flash tank 1 is reduced in pressure to the pressure in the flash tank, and the water in the sludge slurry liquid is evaporated and removed at the same time as the boiling point of water at that pressure (for example, in the tank). Is cooled to 100 ° C. if atmospheric pressure). In this case, the amount of evaporation of water from the sludge slurry liquid is an amount corresponding to a value obtained by subtracting the sensible heat amount of the concentrated liquid from the sensible heat amount of the sludge slurry liquid before being introduced into the flash tank. Water vapor generated from the sludge slurry liquid is discharged from the upper part of the flash tank through the line 6. The sludge slurry liquid from which water has been removed by evaporation is retained as a concentrated liquid in the lower portion of the flash tank, and is discharged from the lower side wall or bottom of the flash tank through the line 7. The solid content concentration in the concentrated liquid is 10 to 40% by weight, preferably 20 to 40% by weight.

In the present invention, the liquid level S of the concentrated liquid in the flash tank is always higher than the concentrated liquid discharge port of the flash tank by a combination of the liquid level detector 3, the controller 2, and the liquid level adjusting valve 4. It is preferred to be located at That is, when the liquid level S of the concentrated liquid drops below a predetermined liquid level, the liquid level detector 3 detects this, and this liquid level information is sent to the controller 2 as an electric signal, where The signal is converted into an electric signal for actuating the liquid level control valve 4 and sent to the liquid level control valve 4, and the liquid level control valve is closed or its opening is reduced. Thereby, the liquid level of the concentrated liquid F rises to a predetermined position. The liquid level S is 5 to 100 cm, preferably 10 to 50 cm above the upper end of the concentrate outlet.

When the sludge slurry concentrate is discharged from the discharge port provided in the flash tank, the concentrate is
It contains a high concentration of solids, and since the solids are sticky and have the property of being easily solidified by drying, the sludge slurry liquid can be stored in the flash tank without remaining in the flash tank. If the concentrated liquid generated by the discharge to the outlet is immediately discharged from the outlet, a trouble of closing the pipe communicating with the outlet occurs. That is, if the concentrated liquid generated in the tank is immediately discharged from its outlet without allowing the concentrated liquid to stay in the tank, the liquid component of the concentrated liquid is more easily discharged. It remains in the pipe near the outlet, and after a lapse of time, accumulates in the pipe at a high concentration. Then, when the deposit does not come into contact with the concentrated liquid, the deposit is dried and solidified to block the pipe. On the other hand, when the concentrated liquid is always retained in the tank, the solid content in the retained concentrated liquid becomes uniform, there is no accumulation of the solid content in the piping, and the solid content in the concentrated liquid is dried. The solidified solution can be smoothly discharged from the discharge port without solidification. In the present invention, it is preferable that the scraper 8 is installed in the flash tank, and the scraper 8 is rotated by the motor 9 so as to scrape off the solid matter adhering to the inner wall surface of the flash tank.

The concentrated liquid discharged from the flash tank as described above is directly sent to the processing step according to the present invention in order to dissolve and / or dissolve coarse particles contained in the liquid. You can do it,
After being sent to the candlestick process to further increase the concentration ratio, it is preferable to send to the treatment process according to the present invention. Hereinafter, this centrifugation step will be described in detail.

In order to centrifuge the sludge slurry from the flashing step, the sludge slurry is introduced into a centrifugation step, centrifuged and further concentrated. In this case, the centrifugation step is performed at a temperature of 50 ° C. or less, preferably 40 ° C. or less, and 500 G or less, preferably 400 G or less, more preferably 250 G or less. When the centrifugal temperature is higher than 50 ° C., the viscosity of the sludge particles in the sludge slurry liquid, which is the raw material to be treated, increases, so that the sludge particles adhere to each other to form massive solids, thereby causing troubles such as clogging of pipes and the like. Will occur. On the other hand, when the centrifugal weight is higher than 500 G, the sludge particles are compacted, so that a massive solid is generated, which causes a blockage trouble in a pipe or the like. By subjecting the sludge slurry liquid from the flash step to centrifugal treatment under the centrifugal conditions, a highly concentrated sludge slurry liquid and separated water separated from the sludge slurry are obtained.
The sludge slurry highly concentrated liquid in this case is concentrated at a high rate as compared with the sludge slurry liquid obtained from the liquefaction step, and has a solid content of 20 to 40% by weight, preferably 30 to 40% by weight. %. In addition, this sludge slurry highly concentrated liquid is centrifuged under specific conditions, despite being obtained by centrifugal treatment, and therefore does not contain any lump solids. On the other hand, since the separated water is obtained by the centrifugal treatment under relatively low centrifugal gravity conditions as described above, the separated water contains a solid content, and the solid content concentration is 20% by weight or less, usually 3 to 5%. 10% by weight.

The separated water is guided to a combustion furnace, and is jetted into the furnace through a furnace wall. Thereby, the organic sludge in the separated water is easily pyrolyzed. In this case, by ejecting the separated water along the furnace wall, the separated water can be evaporated and the furnace wall can be cooled. The spray position of the separated water is not limited to one position, and the sprayed water can be injected into the furnace from a plurality of positions. In addition, this separated water can be separated into separated water and sludge slurry by subjecting to a second centrifugal treatment under centrifugal gravity higher than 500 G, preferably 550 to 1000 G. The separated water in this case has a low solid concentration, and the solid concentration is 10%.
% By weight, usually 1 to 5% by weight. On the other hand, the sludge slurry liquid has a high solid content, and the solid content is 40% by weight or more, usually 30 to 40% by weight. The separated water obtained by the second centrifugal treatment can be guided to a combustion furnace and jetted out of the furnace wall into the furnace. On the other hand, the sludge slurry liquid has a high solid content and excellent flammability. Therefore, the sludge slurry liquid is added to the sludge slurry highly concentrated liquid obtained in the first centrifugal treatment and sent to the above-described treatment step of the present invention. Process.

The sludge slurry liquid containing no coarse sludge particles obtained in the treatment step of the present invention is sent to a combustion step,
Here, fine particles are ejected from the spray nozzle of the burner of the combustion furnace together with the oxygen-containing gas for combustion into the furnace and burned. As the oxygen-containing gas for combustion, air, oxygen-enriched air or oxygen gas is used. The particle diameter of the concentrated liquid ejected from the burner nozzle is 300 μm or less, preferably 3 μm or less.
0 to 150 μm. The type of burner is not particularly limited, but it is preferable to use an external or internal mixed two-fluid spray burner or a low-pressure air spray burner.

The high-temperature flue gas obtained in the combustion step is supplied to a waste heat boiler to generate high-temperature steam in a high-temperature steam generation step. In this case, various types of conventionally known waste heat boilers can be used. The temperature of the steam generated by the waste heat boiler is a temperature required to heat the organic sludge to a range of 150 to 275 ° C, and is usually 190 to 315 ° C, preferably 2 to 275 ° C.
90-315 ° C.

The high-temperature steam obtained as described above is sent to the liquefaction step through a flow control valve and used as a heat source for heating organic sludge. In this case, the flow control valve is controlled by a temperature controller electrically connected to a reaction temperature detector attached to a reaction device used in the liquefaction process.

The amount of high-temperature steam supplied to the liquefaction step by the flow rate control valve is adjusted in relation to the reaction temperature of the liquefaction step, so that the reaction temperature of the liquefaction step is always 150 to 275 ° C. Adjust to the range. In this way,
By keeping the reaction temperature of the liquefaction reaction process within a specific range, carbonization of organic sludge in the liquefaction process is avoided, and the occurrence of the phenomenon of thickening of solids in the sludge liquefaction is prevented. Is done. As a result, the occurrence of blockage troubles in pipes and flash tank outlets due to highly viscous solids and blockage troubles in the concentrate transport pipe are prevented, and a spray nozzle for spraying the concentrate into the combustion furnace. This also prevents the occurrence of blockage troubles.

Next, FIG. 2 shows a flow sheet of an organic sludge treatment method including an organic sludge slurry liquid treatment step according to the present invention. In FIG. 2, 11 is a liquefaction process, 12 is a flash process, 13 is a combustion process, 14
Is a high-temperature steam generation step, 15 is a solid-gas separation step, 16 is a high-temperature steam flow rate control valve, 17 is a concentrated liquid level control valve, 1
8 indicates a centrifugation step, 19 indicates a filtration step, and 20 indicates a dispersion / dissolution step. In order to carry out the treatment of organic sludge according to the flow sheet of FIG. 2, the raw organic sludge is introduced into the liquefaction step 11 through the line 21, where the high temperature steam supplied through the line 27 and the flow control valve 16 is used. , 150
Heat indirectly to a temperature of ２275 ° C. to liquefy. The pressure in the liquefaction step is a pressure higher than the saturated steam pressure at the reaction temperature in order to prevent boiling of water.

The high-temperature sludge slurry in the pressurized state obtained in the liquefaction step 11 is introduced into the flash step 12 through a line 22 to evaporate water contained in the sludge slurry, The generated steam is discharged through a line 24. The sludge slurry liquid is concentrated by the evaporation of the water to become a concentrated liquid. This flash step is performed using a flash tank, and the concentrated liquid stays in the tank. The liquid level of the staying liquid is determined by a liquid level detector and a liquid level controller SI provided in the tank. It is controlled by a liquid level control valve 17 which is electrically connected through the control unit. The concentrated liquid obtained in the flashing step 12 is introduced into the centrifuging step 18 through the line 23, where it is centrifuged to separate into a highly concentrated sludge slurry and separated water. The highly concentrated sludge slurry is introduced into the filtration step 19 through a line 31, where it is screen-filtered. The filter cake obtained by this screen filtration is introduced into the dispersing / dissolving step 20 through a line 34, and is introduced into an aqueous medium supplied through a line 35, where the cake is formed into fine particles and / or fine particles.
Or it is dissolved. The obtained sludge-containing aqueous medium is supplied to line 3
6 and is added to the sludge slurry liquid passing through line 31. This sludge-containing aqueous medium may be added to the sludge slurry liquid passing through the line 33 in some cases.

The sludge slurry from the filtration step 19 is introduced into the combustion step 13 through a line 33, where it is sprayed and burned by a combustion air supplied through a line 25 by a burner (not shown). By this combustion process, 9
High temperature combustion exhaust gas of 00 ° C. or more is generated. This flue gas contains trace amounts of combustion ash, which is introduced into the high temperature steam generation step 14 through line 26, where:
The heating medium is heated and evaporated to generate high-temperature steam. The separated water obtained in the centrifugation step 18 is sent to the combustion step 13 through the line 32, where it is jetted into the furnace through the furnace wall.

The high-temperature steam generated in the high-temperature steam generation step 14 is supplied to the liquefaction step 11 through the line 27 and the flow control valve 16. The reaction temperature in the liquefaction step 11 is determined by a temperature detector and a temperature controller TI provided in the reactor.
Is controlled by a flow control valve 16 which is electrically connected through That is, the flow control valve 16 operates in relation to the reaction temperature of the liquefaction step 11, and when the reaction temperature rises so as to maintain the reaction temperature at a predetermined value,
The flow rate of the high-temperature steam supplied to the liquefaction process is reduced by reducing the opening of the valve, and, on the other hand, when the reaction temperature decreases, the high-temperature steam supplied to the liquefaction process is increased by increasing the opening of the valve. Increase the flow rate.

In the high-temperature steam generation step 14, the flue gas used as a heat source for steam generation is introduced into the solid-gas separation step 15 through a line 28. The solid-gas separation step 15 is a step of removing a small amount of combustion ash contained in the combustion exhaust gas. For this purpose, a conventional solid-gas separation device such as a wet dust collector or a dry electric dust collector is used. The flue gas after removal of the combustion ash is discharged through line 29, while the combustion ash is discharged through line 30.

[0025]

Next, the present invention will be described in more detail with reference to examples.

Example 1 Sewage sludge was selected as the organic sludge, and a dewatered cake of mixed raw sludge discharged from a treatment plant using the standard activated sludge method was used for the test. This sludge is obtained by adding a polymer flocculant and then dewatering it by a belt press. Its typical properties are
It has a water content of 79% by weight, an organic matter ratio of 78% by weight, and a lower calorific value of 3940 kcal / kg.

The dewatered sludge was liquefied using a continuous sludge liquefaction facility (processing capacity: 200 kg / hr). This equipment consists of a press-in device, a reactor (scratch surface heat exchanger), a pressure reducing valve, and a steam jacket. The amount of heat to the reactor is transferred to a steam jacket attached to the outer peripheral surface of the reactor. Was introduced. The dehydrated sludge was introduced into the reactor with a press-in device, and heated to about 270 ° C. while performing scraping to prevent clogging and promote heat transfer. The residence time at the reaction temperature was about 60 minutes. The dewatered sludge is sufficiently liquid at the outlet of the reactor. next,
This high temperature (270 ° C.) sludge liquefied substance (sludge slurry liquid) was flushed into a normal pressure flash tank via a pressure reducing valve attached to the reactor. In this tank, a sludge slurry liquid concentrate (solid concentration 2
9% by weight) was stored up to a position 30 cm above the concentrated liquid discharge port, and the concentrated liquid generated by flushing the sludge slurry liquid was allowed to flow down onto it. The liquid level of the concentrated liquid is adjusted to a predetermined level by operating a concentrated liquid level control valve by a control system electrically connected to a liquid level detection sensor disposed in the tank and adjusting the valve opening. It was held at the height position. By discharging the concentrated liquid generated by evaporating the water from the sludge slurry liquid in the flash tank from the tank as described above, the concentrated liquid could be smoothly discharged from the tank. The solid content of this concentrated liquid was 29% by weight. The temperature was 100 ° C.

This concentrated solution is cooled to 40 ° C. and sent to a centrifugal separator (a decanter-type centrifugal separator).
The centrifugation was performed with the centrifugal gravity of G. The obtained highly concentrated solution had a solid content of about 35% by weight and was sent to a dispersing / dissolving step. On the other hand, the separated water obtained in the centrifugation step (first centrifugation step) showed a solid concentration of 11%, which was sent to the second centrifugation step, where it was centrifuged under the condition of centrifugal gravity of 550 G. By this second centrifugation, a concentrated solution having a solid content of 35% by weight and separated water having a solid content of 5% by weight were obtained. The concentrated solution obtained in the second centrifugation step is
It was added to the highly concentrated solution from the centrifugation step and sent to the dispersion / dissolution step. Separated water was sent to the combustion step and was injected into the furnace through the furnace wall.

The sludge slurry sent to the dissolving and dispersing step was filtered using a screen having an opening of 1 mm to obtain a filter cake consisting of coarse sludge particles and a sludge slurry containing fine sludge particles. . The filter cake composed of the coarse sludge particles was charged into alkaline water containing sodium hydroxide at a concentration of 3% by weight and stirred. By the stirring treatment in the alkaline water, the coarse sludge particles were atomized, and a part thereof was dissolved in the water. Thus, a sludge-containing aqueous medium containing fine sludge particles and having a solid content of 30% by weight was obtained. This was subjected to a filtration treatment in addition to the sludge slurry supplied to the filtration step.

The sludge slurry obtained in the filtration step is sent to a combustion step, where it is sent to a middle-mixing high-pressure two-fluid spray burner using a snake pump at a flow rate of 150 kg / h, and sprayed into a combustion furnace. At the same time, it was burned. At this time, oxygen-enriched air containing 30 vol% oxygen was used as the oxygen-containing gas for combustion. Under these conditions, the liquefied material formed a flame and burned, and the burning continued. The flame combustion was continued for 1 hour or more, and the combustion flame temperature at this time was 1,200 ° C or more.

The high temperature obtained in the combustion furnace (temperature 900
The combustion exhaust gas of (° C.) was introduced into a waste heat boiler to heat the heating medium oil to generate high-temperature steam having a temperature of 310 ° C. and a pressure of 2.5 atm. This high-temperature steam is introduced into the jacket of the sludge liquefaction apparatus through a flow control valve,
It was used as a heat source for heating sludge. The flow control valve is electrically connected to the temperature detector attached inside the sludge liquefaction device,
The internal temperature of the apparatus was maintained at about 270 ° C. by adjusting the flow rate of the high-temperature steam flowing through the valve.

The flue gas having passed through the waste heat boiler is cooled to a temperature of 400 ° C. and introduced into a dry electric dust collector.
Here, after removing the combustion ash contained in the exhaust gas, it was discharged to the atmosphere through a mist separator.

Example 2 In the dispersing / dissolving step of Example 1, a nonionic surfactant was used in place of sodium hydroxide in an amount of 30 per liter of water.
The experiment was carried out in the same manner except that g was added at a ratio of g. Also in this case, the coarse sludge particles were effectively atomized.

[0034]

The sludge contained in the organic sludge slurry treated according to the present invention is in the form of fine particles. Therefore, this sludge slurry liquid has excellent spray characteristics, and can be spray-burned smoothly without closing the spray nozzle.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a flash step for obtaining a concentrated liquid from an organic sludge slurry liquid.

FIG. 2 shows an example of a flow sheet for treating organic sludge.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flash tank 2 Controller 3 Liquid level detector 4 Concentrated liquid level control valve 11 Sludge liquefaction process 12 Flash process of sludge slurry liquid 13 Spray combustion process of concentrated solution 14 High temperature steam generation process 15 Solid-gas separation process 16 Steam flow rate Control valve 17 Concentrated liquid level control valve 18 Centrifugation step 19 Filtration step 20 Dispersion / dissolution step

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeo Terada 2-81-1, Nishi-Shinjuku, Shinjuku-ku, Tokyo Inside the Tokyo Metropolitan Sewerage Bureau (72) Inventor Chisato Tomizawa 2-2-1, Nishi-Shinjuku, Shinjuku-ku, Tokyo Tokyo Metropolitan Sewerage Bureau (72) Inventor Shinji Ito 5-5-16-1 Hongo, Bunkyo-ku, Tokyo Organo Corporation (72) Inventor Shinji Asada 2-4-2, Kyomachibori, Nishi-ku, Osaka City, Osaka Chugai Furnace Industrial Stock In company

Claims (5)

[Claims] 1. A method for treating an organic sludge slurry liquid, comprising: (a) filtering the organic sludge slurry liquid using a screen to form a filter cake composed of coarse sludge particles and a sludge slurry liquid containing fine sludge particles. (B) dispersing the filter cake into fine particles and / or dissolving the filter cake obtained in the filtration step in an aqueous medium containing an alkali and / or a surfactant.
A dissolving step, (c) adding an aqueous medium containing the sludge obtained in the filter cake dispersing / dissolving step in the form of fine particles and / or dissolved to an organic sludge slurry liquid supplied to the filtering step, or A method for treating an organic sludge slurry, comprising an addition step of adding the filtrate to the filtrate obtained in the filtration step. 2. The method for treating an organic sludge slurry according to claim 1, wherein the organic sludge slurry is an organic sludge slurry obtained from an organic sludge liquefaction step or a concentrate thereof. 3. The method for treating organic sludge exhibiting a solid state, comprising: (i) subjecting the organic sludge to high-temperature steam for 150 minutes.
A liquefaction step in which the mixture is indirectly heated to a reaction temperature of about 275 ° C. and liquefied by holding it at a pressure higher than the saturated steam pressure at the reaction temperature, and (ii) a sludge slurry liquid obtained in the liquefaction step A concentration step of obtaining the concentrate from (ii)
i) a combustion step of burning the sludge slurry concentrate obtained in the concentration step; (iv) high-temperature steam generation in which the high-temperature combustion exhaust gas obtained in the combustion step is supplied to a waste heat boiler to generate high-temperature steam (V) a high-temperature steam supply step in which the high-temperature steam obtained in the high-temperature steam generation step is sent to the liquefaction step through a flow control valve and used as a heat source for indirect heating of organic sludge; The amount of high-temperature steam supplied to the liquefaction step is adjusted by the control valve in relation to the reaction temperature of the liquefaction step, so that the reaction temperature of the liquefaction step is constantly 150.
A high-temperature steam amount adjustment step of adjusting the temperature to a range of 濃縮 275 ° C., wherein the sludge slurry concentrate obtained in the concentration step is
Prior to supplying to the combustion step, (a) a filtration step using a screen to separate into a filter cake composed of coarse sludge particles and a filtrate composed of a sludge slurry liquid containing fine sludge particles; A step of dispersing and dissolving the filter cake obtained in the filtration step by atomizing and / or dissolving the filter cake in an aqueous medium to which an alkali and / or a surfactant has been added, and (c) the filter cake obtained in the dispersion and dissolution step. Adding an aqueous dispersion or solution of sludge to an organic sludge slurry liquid to be supplied to the filtration step, or passing through an addition step to be added to the filtrate, and then supplying the same to the combustion step. Sludge treatment method. 4. The organic method according to claim 3, wherein the concentration step is a step of discharging the sludge slurry liquid obtained in the liquefaction step into a flash tank to evaporate water contained in the sludge slurry liquid. Treatment method for anaerobic sludge. 5. A first concentration step of discharging the sludge slurry liquid obtained in the liquefaction step into a flash tank to evaporate water contained in the sludge slurry liquid; 4. The method for treating organic sludge according to claim 3, comprising a second concentration step in which the sludge slurry concentrate obtained in the first concentration step is centrifuged at a temperature of 50 ° C. or less and a centrifugal gravity of 500 G or less.