JP3521077B2 - Freeze-thaw tank, sludge treatment equipment and freeze-thaw method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a freeze-thaw tank, a sludge treatment device, and a freeze-thaw method, and more specifically, a freeze-thaw tank capable of increasing dehydration efficiency when freeze-thawing an object to be treated such as sludge. And a freeze-thaw method.

[0002]

2. Description of the Related Art When sludge is treated, since sludge generally contains a large amount of water, it is necessary to separate sludge from water, that is, solid-liquid separation. However, the properties of sludge depend on the state of raw water and the coagulant used, and its components are generally composed of aluminum hydroxide, clay, colloids, microorganisms and other organic and inorganic substances, and have a high water content. It is gelatinous. Therefore, the filterability is poor, and the water content of the separated sludge is high, which causes a considerable burden on post-treatment such as transportation costs and landfill incineration. Therefore, a method of utilizing the aggregating action by chemical injection before post-treatment is used. When lime and ferric chloride, which are inorganic coagulants, are used as injection chemicals, the filterability is improved, but there is a problem that the amount of sludge to be disposed increases by injecting the chemicals.

Therefore, as a sludge treatment method for solving this problem, a method of freeze-thawing sludge using a freeze-thaw apparatus has been developed. This freeze-thaw device puts sludge to be treated into a freeze-thaw tank whose outer wall is covered with a heat insulating material, and also passes cold brine from an absorption refrigerator to a heat exchange pipe arranged inside the freeze-thaw tank. The sludge is frozen, and after freezing, warm brine is passed through the pipe to melt the frozen sludge. Then, after the completion of thawing, open the sludge opening / closing valve provided at the bottom of the freeze-thaw tank and introduce it into the dehydrator to introduce the substance to be treated into the solid-liquid separation tank to separate the sludge that has undergone dehydration. It has become.

The principle of the freeze-thaw method focuses on the existence of water contained in sludge and water adhering to its surface,
By being frozen, the water grows as ice crystals,
At that time, the sludge is pushed to the unfrozen zone and the fine particles are concentrated while being combined and combined into a large block to improve the filtration characteristics. Furthermore, when the whole is frozen, the expansive force of ice formation gives a strong compressive force to the sludge, which destroys the sludge structure (protein or carbohydrate micelle structure or gel-like structure of gel-like substance) and The contained water flows out, and the dehydration effect becomes higher.

The freezing and thawing tank is capable of accommodating sludge therein, and a meandering heat exchange pipe is arranged inside the tank, and cold brine is passed through this heat exchange pipe to remove sludge. Freeze and extract water from sludge. And
The hot brine is allowed to flow from the absorption refrigerator to melt the sludge, thereby effectively promoting the dehydration treatment in the next step.

[0006]

Generally, the sludge to be put into the freeze-thaw tank is stored in advance in the sludge thickening tank and naturally concentrated, and then the sludge is separated into 1/5 to 1/1 / th by a centrifugal separator.
The volume of the centrifuge is reduced to 8 to improve the dehydration property in the treatment process using a freeze-thaw tank. This has led to soaring processing costs.

In view of the above-mentioned problems of the prior art, an object of the present invention is to efficiently perform dehydration in a freeze-thaw tank and further dehydration treatment without using a large-scale and expensive centrifuge. The object of the present invention is to provide a freeze-thaw tank that can be used as an object, a sludge treatment device including the same, and a freeze-thaw method.

[0008]

The above objects can be achieved by the inventions described in the claims. That is, the characteristic configuration of the freeze-thaw tank according to the present invention is a tank capable of accommodating an object to be treated, a freeze-thaw means for freezing or thawing the object to be treated contained in the vessel, and an operation of the freeze-thaw means. A clearing liquid removing means capable of extracting the clearing liquid discharged from the object to be treated,
And the freeze-thaw means is disposed in the tank.
For heat exchange to pass cold / warm brine inside
And the clarified liquid removing means is provided on the side wall of the tank.
It is installed in the vertical direction so that the clear liquid can be extracted.
It is that it is a stub.

According to this structure, the solid material is deposited in the lower layer and the liquid material discharged from the object to be processed is separated into the upper layer during the freeze-thawing process, and the liquid in the upper layer is used. By extracting the product as a clarified liquid, the amount of material to be processed required for the dehydration process in the next step can be significantly reduced, the dehydrator can be downsized, and the dehydration process in the entire process can be efficiently performed. Therefore, it is not necessary to use a centrifugal separator. So
Then, the freeze-thaw means is disposed in the tank,
With piping for heat exchange that allows cold and hot brine to flow inside the
Yes, the clarified liquid removing means is provided in the vertical direction of the side wall of the tank.
It has been installed over the
Since it is a pipe stub, the freeze-thawing process can be performed efficiently.
In addition to being able to do so, the clearing liquid removing means is complicated and large-scale.
Since it is not necessary to make it expensive, it is possible to prevent the equipment cost from rising sharply.
In addition to being able to reliably improve the dehydration efficiency
Is good. The number and shape of the nozzles are the size of the freeze-thaw tank,
It can be selected as appropriate depending on the amount and properties of the object to be processed.
It is not limited to.

As a result, the freeze-thaw tank can be efficiently dehydrated in the freeze-thaw tank and the subsequent dehydration treatment without using a large-scale and expensive centrifuge, and therefore the treatment cost can be reduced. Could be provided.

[0011]

[0012]

Outside the tank of the nozzle provided on the side wall of the tank
It is preferable that a heating means is provided at the location .

According to this configuration, it is possible to reliably prevent the possibility that the pipette is cooled during withdrawal of the clear liquid and the clear liquid in the pipette is frozen, and the subsequent withdrawal is stopped.
The heating means may be, for example, one that covers the heater around the nozzle, or one that supplies heated water around the nozzle, and is particularly limited to the structure. Not a thing.

By the freeze-thaw means, the cover in the tank is
When freezing the processed product, the pipe should be released to the tank.
It is preferable that the vibrating means is provided on the inlet side and the inlet side .

According to this structure, when the object to be treated is frozen in the tank, the vibrating means gives vibration to the object.
As freezing progresses and the solid content that has agglomerated at the freezing interface is forced to move through the freezing interface due to vibration, a frozen water flow path is reliably secured, and the object to be processed is trapped in ice under supercooling. Can be reliably prevented. That is,
To prevent solids from freezing in the separated state,
It is possible to increase the aggregation and aggregation of solids, thereby improving the filtration characteristics of the object to be treated. Further, since supercooling is unlikely to occur, freezing is consequently accelerated, and the freezing process is accelerated, so that a remarkable dehydrating effect can be exhibited. Therefore, it is convenient that the clear liquid is removed more efficiently.

The vibrating means may be a means for mechanically striking continuously or intermittently, a means for mechanically vibrating from an electric signal, or a means for imparting ultrasonic vibration. . It is preferable that the vibrating means is used to periodically or intermittently vibrate the heat exchange pipe for passing the cold / warm brine from the time when the temperature of the object to be treated reaches 0 ° C. The vibration by the vibrating means is directly transmitted to the object to be processed in the tank, which can effectively prevent the supercooling of the object to be processed, and the vibrating means is not structurally complicated, which increases the installation cost. Can be prevented,
Maintenance is also easy.

The sludge treatment apparatus according to the present invention is characterized by a sludge supply tank capable of storing sludge and a sludge supply tank
The freeze-thaw tank according to any one of claims 1 to 3, which is fed.
And connected to this freezing and thawing tank to send cold and hot brine
And a possible absorption refrigerator.
Is an ammonia absorption refrigerator,
The absorber to be cooled that constitutes the refrigerator is frozen,
The purpose is to utilize the cold heat source that is generated when the object melts .

According to this structure, it is possible to provide a sludge treatment device which can efficiently perform dehydration in a freeze-thaw tank and further dehydration treatment without using a large-scale and expensive centrifuge. You can Moreover, the absorption refrigerator is
It is a near absorption refrigerator, and this ammonia absorption refrigerator is
The cooling of the constituent absorbers is performed by melting the frozen object to be treated.
I try to make use of the cold heat source that sometimes occurs
The cooling of the absorber is usually done by a cooling tower.
However, in addition to this, the cold heat source generated when the frozen sludge is thawed
When it is used, the low drive energy of the refrigerator
And higher coefficient of performance, further energy saving and
Power saving can be achieved.

In this case, the term "sludge" is used to generically refer to dirty mud-like substances containing a relatively large amount of water, including sludge generated in water treatment plants and sewage treatment plants, industrial wastewater treatment sludge,
It is used as a concept that includes all types of sludge such as landfill wastewater treatment sludge and human waste treatment sludge.

It is preferable to have a premix tank for preparing a premix of sludge and ice nucleation active protein-like substance, and a mechanism for charging the premix into the freeze-thaw tank from the premix tank.

According to this configuration, by putting the mixture mixed in the premixing tank into the freeze-thaw tank, the freezing start temperature of the sludge rises and the ice-nucleus active protein-like substance uniformly dispersed is frozen from the periphery. With the large number of fine sludges that started freezing as the core, the freezing of sludge in the freeze-thaw tank can grow efficiently without unevenness, and the freezing efficiency can be made extremely high. convenient.

Furthermore, the characteristic constitution of the freeze-thaw method according to the present invention is that the object to be treated is contained in the bath constituting the freeze-thaw tank.
Then, using the freeze-thaw means, the object to be treated contained in the bath
When freeze-thawing a product, the action of the freeze-thawing means
For the method of extracting the clear liquid discharged from the object to be treated
The freeze-thaw device that constitutes the freeze-thaw means is
Freeze and thaw the material to be processed with an ammonia absorption refrigerator.
Perform the cooling of the absorber that constitutes this ammonia absorption refrigerator.
A cold heat source generated when the frozen object to be processed is thawed
And withdrawing the clarified liquid as described above.
It is installed in the vertical direction of the side wall of the tank and drains the clear liquid.
It is done by a nozzle that can be put out .

According to this structure, when the object to be processed is freeze-thawed, the solid matter is deposited in the lower layer and the liquid material discharged from the object is separated into the upper layer. By extracting the liquid material of the upper layer as a clear liquid,
The amount of material to be processed in the dehydration process in the next step can be significantly reduced, the dehydrator can be downsized, and the dehydration process in the entire process can be made efficient. It is possible to provide a freeze-thaw method which does not need to be used and therefore has low processing costs. Only
Also, the freeze-thaw device that constitutes the freeze-thaw means is
The processed product is frozen and thawed by an ammonia absorption refrigerator.
Cooling the absorber that constitutes this ammonia absorption refrigerator
A cold heat source generated when the frozen processed object is thawed.
Since it is done by using it, usually the absorber is cooled.
In addition to this, frozen sludge is used.
If you use the cold heat source that is generated when the
Decrease drive energy of freezers and increase coefficient of performance
To achieve further energy savings and power savings
You can

When freezing and thawing the object to be treated in the tank by the freezing and thawing means, it is preferable to vibrate the object to be treated.

According to this structure, since supercooling is unlikely to occur during freezing, freezing can be promoted and a remarkable dehydrating effect can be exhibited, so that the clear liquid can be more efficiently removed. Is good.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic overall structure of a sludge treatment device according to an embodiment of the present invention, and FIG. 2 shows a schematic sectional structure of a freeze-thaw tank used in FIG.

This sludge treatment device comprises a sludge supply tank 1 for temporarily storing a sludge which is a kind of an object to be treated, a freeze-thaw tank 2 for freeze-thawing the sludge fed from the sludge supply tank 1, and this It is provided with a dehydrator 4 for dehydrating the sludge modified by the melting tank 2. Further, the freeze-thaw tank 2 is connected to the absorption refrigerator 6 and the sludge in the freeze-thaw tank 2 is frozen by indirect contact with the heat medium fed from the absorption refrigerator 6 via the pipe. The heat medium is called brine, and antifreeze liquid such as calcium chloride and ethylene glycol is used.

[0029] The absorption refrigeration machine 6, it is preferable to use the ammonia absorption refrigeration machine. When ammonia is used as the refrigerant, it is convenient because it functions as a refrigerant that is inexpensive and has excellent thermodynamic properties without using CFCs that are harmful to the environment. Although not shown, the ammonia absorption refrigerator 6 includes a condenser for radiating and liquefying ammonia as a refrigerant by heat radiation, an evaporator for evaporating ammonia, and an absorber for absorbing ammonia vapor evaporated by this evaporator into water as an absorbent. And a container. Then, a generator that pressurizes and feeds an aqueous ammonia solution sufficiently containing a refrigerant by an absorber with a solution pump, and a rectifier that raises the concentration of ammonia and sends it to a condenser may be provided. Furthermore, as a drive source for operating the absorption refrigerator, waste heat energy such as incineration of sludge and cogeneration may be supplied.

In the mud supply tank 1, sufficiently stir with the stirrer 5.
The mixed sludge is sent to the freeze-thaw tank 2 by the feed pump P. As shown in detail in FIG. 2, the freeze-thaw tank 2 has a side wall of the tank covered with a heat insulating material 2a,
Cold brine or hot brine is supplied from the absorption refrigerator 6 into the tank via a pipe. That is, the brine sent from the absorption refrigerator 6 is introduced into the brine header 2b, and in order to send the brine from the brine header 2b into the tank, the brine for freezing or thawing the sludge stored in the tank is introduced. The heat exchange pipe 2c (a kind of freeze-thaw means, which is shown in FIG. 2 has a simple structure to avoid complication) is arranged in a meandering shape. It is connected to the header 2b.

Further, on the side surface of the tank, water (clarified liquid) separated and separated in the upper layer when sludge is frozen and thawed.
The stub 10 for pulling out is attached at three positions in the vertical direction. If the sludge is allowed to stand as it is, it takes a lot of time to separate the solid matter and the liquid matter, and it should be difficult to practically perform the solid-liquid separation. Solid-liquid separation proceeds. For example, in the case of sludge that has not been freeze-thawed, the ratio of the concentrated layer to the clarified liquid remains at 8: 2 even after standing for 120 minutes, whereas in the case of freeze-thawed sludge, after 15 minutes. As a result, the ratio of the concentrated layer to the clear solution was 1: 9. Utilizing such a phenomenon, the clear liquid (in this case, water) is supplied to the nozzle 1
By extracting from 0, the dehydration treatment in the subsequent step becomes easy and effective.

The nozzle 10 is connected to the on-off valve 11 and connected to the downstream side so as to collect the respective pipes in order to collect the water extracted from the three nozzles 10 at one position. . A heater wire 12, which is a kind of heating means, is wound around each nozzle 10 to prevent water from freezing and clogging inside the nozzle 10. The heater wire 12 is connected to the temperature controller, and the nozzle 10
It is preferable that the freezing can be surely prevented.

As the opening / closing valve 11, various types such as a solenoid valve, a float type valve and the like can be adopted. The water in the tank is remarkably removed by appropriately extracting the water discharged by the freeze-thawing process from the nozzle 10, so that the dehydrator for receiving the sludge discharged from the sludge discharge port at the bottom of the tank through the on-off valve 9. 4 may be smaller and have a smaller capacity than the prior art device. The water extracted from the nozzle 10
It is sent to the wastewater treatment facility for treatment.

[Other Embodiments] (1) As shown in FIG. 3, a pair of vibrators 7 as vibrating means are attached to the brine header 2b for introducing cold / warm brine into the freeze-thaw tank, respectively, and Vibration of appropriate amplitude and frequency may be applied to the pipe 2c when the sludge stored therein is frozen. The strength and frequency of vibration to be applied and the vibration mode (for example, continuous vibration is initially applied and then switched to intermittent vibration at 0 ° C.) may be appropriately selected depending on the amount and properties of sludge. . The vibrator 7 may be attached only to one of the pair of brine headers 2b.

When the sludge is frozen, vibration is applied by the vibrator 7 to solidify the solids that have been frozen at the freezing interface and are forced to move at the freezing interface due to the vibration. Surely secured,
It is possible to reliably prevent the sludge from being trapped in ice in a supercooled state. That is, it is possible to prevent the solid content from being frozen in a state where it is appropriately separated, to increase the aggregation and aggregation amount of the solid content, and to improve the sludge filtration property.

As described above, by vibrating the sludge during freezing, it is possible to surely prevent the supercooling of the sludge, promote the growth of ice, and prevent the sludge in the tank from being locally disturbed. It can be frozen substantially uniformly without causing uniform freezing. Therefore, in this way, in addition to eliminating the clear water, the dehydration effect of the freezing treatment is effectively exerted, and the freeze / thaw treatment can be effectively performed.

Another vibrator, which is a vibrating means, may be provided on the side wall of the tank. Even in this case, the sludge can be similarly vibrated, and the supercooling of the sludge can be effectively prevented. However, both of the vibrators 7 are not necessarily required, and at least any one of them may be provided, and the installation location and the number of the vibrators are not particularly limited. The vibrating means is not limited to a device that directly applies mechanical vibration, and an ultrasonic vibrator connected to an ultrasonic wave generator may be used.

The sludge that has been frozen and drained of water is thawed by the supply of warm brine from the absorption refrigerator 6. Then, by opening the on-off valve 9, the sludge is discharged from the bottom discharge port and introduced into the dehydrator 4, where the sludge is sufficiently dehydrated and discharged as the reformed sludge.

(2) When the sludge is frozen in the freeze-thaw tank 2, an ice nucleus active protein-like substance may be put into the tank together with the sludge to accelerate the freezing. In that case, it is preferable to put a mixture of previously prepared sludge and ice nucleus active proteinaceous substance into the freeze-thaw tank 2 to freeze / thaw it. That is, a premix tank (not shown) for preparing a premix of sludge and ice-nucleus active protein-like substance is provided in advance, and the premix is put into the freeze-thaw tank 2 from this premix tank.

As the ice nucleation active protein-like substance, there are ice nucleation active bacteria such as Erwinia herbicola and Pseudomonus fluore.
It is possible to use scens, Pseudomonas syringage, etc., which are cultivated in an L medium or the like to collect the bacteria, physically destroy and sterilize them, freeze-dry this, and then pulverize it into a powder form.

In this way, a mixture of sludge and ice-nucleus active protein-like substance is prepared in advance, so that they are mixed uniformly and mixed, and when this is put into the freeze-thaw tank, the ice-nucleus active protein-like substance is mixed. The freezing temperature of the sludge rises due to the presence of the sludge, and the freezing starts around the uniformly dispersed ice nuclei active proteinaceous substance. The freezing can be efficiently grown without causing unevenness, and the freezing efficiency can be made extremely high. Therefore,
The filtration specific resistance at the time of dehydration becomes small, water is easily eliminated, and the dehydration process can be efficiently performed.

Since the ice nucleation active protein-like substance to be used is obtained from ice nucleation active bacteria and is not a viable bacterium, it does not cause contamination or other problems, is easy to handle, and has good working efficiency. Is also expensive. By efficiently freezing an object to be treated such as sludge, the energy required for freezing can be reduced, and moreover, the efficiency of the dehydration treatment in the next step can be improved to further improve the dehydration property.

[0043]

( 3 ) The hot brine circuit and the cold brine circuit may be always operated for a plurality of freeze-thaw tanks. That is, the cold brine circuit is operated to freeze the sludge in one freeze-thaw tank, while the warm brine circuit is operated to thaw the sludge already frozen in the other freeze-thaw tank. By sequentially performing such an operation on a plurality of freeze-thaw tanks, the pre-dewatering treatment of sludge can be efficiently performed, and the treatment efficiency can be increased.

[0045]

( 4 ) The freeze-thaw tank and the freeze-thaw method according to the present invention can be applied to the food industry which employs a concentration treatment step using a freeze-thaw method, such as a fruit juice concentration step and a waste liquid concentration step, in addition to sludge treatment. It can also be applied to a freezing process in an ice heat storage system and other solid-liquid separation processes in general chemical industry.

[Brief description of drawings]

FIG. 1 is a schematic overall configuration diagram of a sludge treatment device according to an embodiment of the present invention.

FIG. 2 is a schematic sectional configuration diagram of a freeze-thaw tank used in the sludge treatment device of FIG.

FIG. 3 is a schematic overall configuration diagram of a sludge treatment device according to another embodiment.

[Explanation of symbols]

1 mud tank 2 Freeze-thaw tank 2c Freezing and thawing means (piping for heat exchange) 6 absorption refrigerator 7 Vibration means 10 Clearing liquid removal means (tube base) 12 Heating means

Continuation of the front page (56) Reference JP-A-56-58600 (JP, A) JP-A-4-126600 (JP, A) JP-A 52-86257 (JP, A) JP-A-2-76595 (JP , A) Actual development Sho 51-2060 (JP, U) Actual development Sho 50-134960 (JP, U) Nakae Hideo, Coagulation Engineering, Japan, Agne Co., Ltd., September 10, 1987, 69-71p (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 11/00-11/20 B01J 19/00 A23L 2/12

Claims (7)

(57) [Claims] 1. A tank capable of accommodating an object to be treated, a freezing and thawing means for freezing or thawing the object to be treated contained in the tank, and a clarification discharged from the object to be treated by the action of the freezing and thawing means. In a freeze-thaw tank comprising a clearing liquid removing means capable of extracting a liquid , the freeze-thawing means is disposed in the tank,
It is a pipe for heat exchange that allows cold and hot brine to flow through
The clarified liquid removing means extends vertically in the side wall of the tank.
A stub that is installed in order to allow the clear liquid to be extracted.
A freeze-thaw tank characterized in that . 2. The tank of the nozzle provided on the side wall of the tank
The freeze-thaw tank according to claim 1 , wherein a heating means is provided at an external location . 3. The inside of the tank by the freeze-thaw means
When freezing the object to be processed,
The vibrating means is provided on the outgoing side and the incoming side.
1 or 2 freeze-thaw tanks. 4. A mud supply tank capable of storing sludge, and this mud supply tank
Freezing according to any one of claims 1 to 3, wherein sludge is sent from
A freeze / thaw tank connected to this freeze / thaw tank
And an absorption refrigerating machine capable of supplying a gas, wherein the absorption refrigerating machine is an ammonia absorption refrigerating machine.
Freezing the cooling of the absorber that constitutes the ammonia absorption refrigerator
Using the cold heat source generated when the above-mentioned processed material is melted
A sludge treatment device characterized by performing . 5. A sludge and an ice-nucleus active protein-like substance in advance
A premix tank to create a premix of
A contractor having a mechanism for charging the premix into the freeze-thaw tank
The sludge treatment device of claim 4 . 6. An object to be treated is placed in a tank forming a freeze-thaw tank.
It is stored in the tank using freeze-thaw means.
When freeze-thawing the processed product, the operation of the freeze-thawing means is performed.
Freezing to extract the clear liquid discharged from the object to be processed
In the thawing method, the freeze-thaw device that constitutes the freeze-thaw means is the
Freeze and thaw the product with an ammonia absorption refrigerator,
Cooling the absorber that constitutes this ammonia absorption refrigerator,
Utilizes a cold heat source generated when the frozen processed object is thawed
In addition, the clarified liquid is drawn out vertically on the side wall of the tank.
A pipe that is installed vertically so that the clear liquid can be drawn out.
Freezing and thawing method characterized in that it is performed by a table . 7. Heating provided outside the tank of the nozzle.
By means of freezing of water inside the nozzle and clogging
The freeze-thaw method according to claim 6, which prevents