JPH05263417A - Sludge reforming apparatus and method thereof - Google Patents

Abstract

PURPOSE:To reform sludge into ordinary soil efficiency without the need of such large equipment as a refrigerator or a compressor in treating the sludge by freezing and melting it. CONSTITUTION:A heat exchanger 2 is installed int an LNG pipeline 1 and this is connected to a cooler 4 installed in a sludge refrigeration chamber 6 with a refrigerant pipe 4. A controlling device 3 is then installed on the line of the refrigerant pipe 5, thereby enabling control of temperature of the sludge refrigeration chamber 6. In a sludge reforming apparatus constituted like that, an efficiency cylcle of freezing sludge at a temperature of -10 deg.C--60 deg.C and melting it by returning the temperature to normal temperature is repearted, so that the sludge is reformed into soil close to ordinary. Accordingly, the highly efficient sludge modification of freezing at a refrigenration temperature and then melting is made possible very easily without the need of freezing machinery including a compressor etc., so that equipement cost is reduced and sludge-reformed soil close to ordinary is obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an apparatus and method for reforming sludge in sludge treatment.

[0002]

BACKGROUND ART Sludge treatment can be started by first dehydrating sludge. As a method for dehydrating this sludge, if the sludge is frozen and the fine grains in the sludge are separated by ice crystals, the Since the ice crystals are separated from the fine-grained sludge to form water, the dewatering up to the fine-grained sludge can be performed efficiently, and further, this freezing and thawing method has the function of modifying the sludge. Is commonly known. For this reason, this freeze / sludging process has traditionally been used in sludge treatment and sludge reforming processes.
The melting method is often used.

[0003]

However, the sludge reforming treatment by the conventional freeze / thaw method using a refrigerator requires a large amount of equipment cost and operating cost of the refrigerator. There's a problem. Further, the cooling temperature and the number of times of freezing at the time of freezing are largely related to the sludge reforming efficiency by this freezing / thawing method.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a sludge reforming apparatus and an efficient sludge reforming method which do not require a great deal of cost. is there.

[0005]

A sludge reforming apparatus and a reforming method according to the present invention include a sludge reforming apparatus using a freezing device that utilizes the cold heat of LNG and a sludge containing water at a temperature of -10 ° C.
Provided is a reforming method in which a cycle of freezing at -60 ° C and then thawing is repeated twice or more.

[0006]

By utilizing the cold heat of LNG by the heat exchanger, a refrigerating machine including a compressor and having a large equipment scale is not required. Also, the temperature is -10 ° C or lower and -60 ° C
By repeating the cycle of freezing and then thawing as described above, sludge can be efficiently reformed.

[0007]

EXAMPLE FIG. 1 is a block diagram of a sludge reforming apparatus according to an example of the present invention. In the figure, 1 is the LNG pipeline, 2
Is a heat exchanger, 3 is a control device, 4 is a cooler, 5 is a refrigerant pipe that connects between the heat exchanger 2 and the cooler 4, and circulates a refrigerant such as CFC or ethylene glycol aqueous solution, and 6 is a heat insulating material. Refrigerator made by, 7 is sludge.

Next, this operation will be described. After LNG (-162 [deg.] C.) is introduced into the heat exchanger 2 through the LNG pipeline 1 to exchange heat with the refrigerant, the refrigerant is introduced through the refrigerant pipe 5 to the cooler 4 installed in the insulated freezing room 6 and the freezing room. Cool the inside of 6. The sludge 7 is carried into the refrigerating room 6 cooled in this way, and the temperature is set to -25 ° C. by the control device 3.
Freeze sludge while adjusting to. After the completion of freezing, the sludge 7 was taken out of the freezing chamber 6 and melted, and then the particle size distribution and the Atterberg limit were measured and compared with the raw sludge. The results are shown in Fig. 2 particle size distribution diagram and Fig. 3 plasticity diagram.

In the figure, α is raw sludge, β is frozen sludge, and γ
Is general soil. As shown in the figure, the raw sludge has a clay content of 64
%, The silt content was 36%, and the freezing content changed to 31% clay content and 69% silt content. That is, fine particles aggregated and coarsened due to ice crystal separation by freezing.

[0010] Looking at this change in the plasticity diagram of Fig. 3, it can be seen that due to freezing, the liquid limit water content ratio / plasticity index has dropped significantly and has changed to a completely different soil quality. Here, when the soil properties of the general soil γ are represented on the plasticity diagram, W _L ≦ 150%,
Since I _P ≦ 100%, it is clear that when the raw sludge α is frozen as described above, it is modified so as to approach the general soil γ.

Further, when the freezing treatment was carried out by changing the atmospheric temperature during the freezing treatment variously, the degree of modification was almost the same from -10 ° C to -50 ° C, but it was improved when frozen at -60 ° C or lower. The quality decreased and the reformability deteriorated. Also, −
If the freezing process is performed at a temperature of 10 ° C. or higher, it takes a long processing time and the efficiency is lowered. From the above, it was revealed that the freezing temperature for sludge reforming is highly efficient at -10 ° C to -60 ° C.

Next, in order to further promote sludge reforming, another sludge was subjected to two freeze / thaw cycles at a freezing temperature of -25 ° C. and the reformability was measured. 5 shows the plasticity diagram. In the figure, α is raw sludge,
β ₁ is frozen sludge of -25 ℃ 1 cycle, β ₂ is -25 ℃
Two cycles of frozen sludge. According to FIG. 4, the raw sludge α having a clay content of 73% and a silt content of 26% is a frozen sludge β ₁ having a clay content of 67% and a silt content of 33% in one freeze treatment.
It became clear that the coarsening of the particles occurred in the frozen sludge β ₂ having the clay content of 61% and the silt content of 39% by the further two freeze treatments. At the same time, it was revealed that the change in the plasticity diagram of Fig. 5 was also modified correspondingly to the general soil γ as the freeze-thaw cycle increased.

[0013]

EFFECTS OF THE INVENTION By using the reformer utilizing the cold heat of LNG, the present invention does not require a refrigerating machine, so that equipment cost and operating cost can be reduced. Also,
By repeating a cycle of freezing at a temperature of −10 ° C. to −60 ° C. and then melting as a reforming method, the sludge can be efficiently reformed so as to approach the general soil.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a reformer of the present invention.

FIG. 2 is a particle size distribution diagram of raw sludge and frozen sludge.

FIG. 3 is a plasticity diagram of raw sludge and frozen sludge.

FIG. 4 is a particle size distribution diagram of raw sludge and frozen sludge.

FIG. 5 is a plasticity diagram of raw sludge and frozen sludge.

[Explanation of symbols]

 1 LNG pipeline 2 Heat exchanger 3 Control device 4 Cooler 5 Refrigerant pipe 6 Freezing room 7 Sludge α Raw sludge β Frozen sludge γ General soil

Claims (2)

[Claims] 1. An apparatus for treating sludge by a freeze / thaw method, comprising a heat exchanger utilizing cold heat of LNG, a cooler provided in a freezing chamber, and connecting the heat exchanger and the cooler. A sludge reforming apparatus comprising: a refrigerant pipe for circulating a refrigerant; and a control device provided on the refrigerant pipe. 2. In sludge treatment by the freeze / thaw method,
A sludge reforming method, characterized in that the sludge is frozen at a freezing temperature of -10 ° C to -60 ° C, and then a cycle of melting the sludge is repeated twice or more.