JPS6336838B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for treating sludge from a dry cleaning machine, and more particularly to a method for treating sludge discharged from a dry cleaning machine, which recovers valuables and makes the sludge pollution-free. Sludge (mainly filter sludge and oil sludge consisting of dust, oil, fibers, etc. entrained from filter sludge and clothing) that accumulates in the storage tank of cleaning solvents (e.g., benzine, carbon tetrachloride, trichlorethylene, tetrachlorethylene, etc.) in dry cleaning machines is Because it contains a cleaning solvent, it poses the problem of being unable to be disposed of as is, due to the recovery of valuables and its toxicity. In other words, in the past, it was customary to periodically stop the equipment, manually scrape out the sludge that accumulated in the cleaned solvent storage tank, and then process it separately. There were problems such as the generation of bad odors and treatment costs, and there was an urgent need to consider measures to treat the sludge. Therefore, the present inventors investigated and tested in detail the properties of the sludge discharged from dry cleaning machines, and as a result of many experiments, the sludge accumulated in the storage tank was thoroughly mixed with the solvent again, and the oil was removed from the sludge. The present invention was achieved as a result of the discovery that the sludge can be disposed of as it is by extracting the activator and the like into a solvent. That is, the present invention accumulates oily sludge discharged from a washing drum and sludge derived from filter material discharged from a filter in a collection tank,
The accumulated sludge is left for a certain period of time to separate into liquid and solid content, and the separated liquid is led to an evaporator, where the solvent and oil contained in the liquid are separated and the solvent is recovered. After that, the solvent is sent to the recovery tank, brought into contact with the solid content in the recovery tank, left for a certain period of time, separated into liquid and solid content again, and the separated liquid is sent to the evaporator again. to recover the solvent by heating it to separate the solvent and oil contained in the same liquid, and then further heating the solid content remaining in the recovery tank to recover the solvent contained in the solid content. The present invention relates to a method for treating sludge in a dry cleaning machine solvent tank, characterized in that the solvent and oil contained in the sludge accumulated in the recovery tank are removed and recovered. In the present invention, as the solvent added to the sludge solid content, it is preferable to use a part of the solvent recovered after separating it from the oil and refluxing it, but it is also possible to newly add it from the outside. The contact between the solvent and the sludge solids can be effectively carried out by stirring, mixing, shaking, etc., thereby adding oil to the solvent phase.
Extract surfactant, separate into liquid and solid,
After repeatedly separating the solvent and oil in the liquid and heating the remaining solids to recover the contained solvent,
The sludge that remains at the end is disposed of. The present invention will be specifically explained based on the flow sheet of FIG. 1, taking as an example the case where percrene (tetrachlorethylene) is used as a cleaning solvent. Put clothes, etc. into washing tub W, then into tank T ₂
clean cleaning _{solvent 1} and _/ or _detergent S (ABS,
Supply cationic, anionic, nonionic surfactants such as DBS and wash with stirring. The cleaning solvent that becomes dirty as the washing progresses is sent to the filter F via the valve V ₄ by the pump P ₂ to remove solids, fibers, etc. At the same time as washing is completed, it is sent to the washing tub W, and before deodorization and drying, the cleaning solvent is sent to the filter F through the valve V 4. ₅ and then extracted into tank T ₁ . Tank T ₁
The contaminated cleaning solvent stored in the tank has a composition as shown in Table 1.

[Table] This contaminated cleaning solvent is sent to evaporator E via valve V ₆ , pump P ₁ , and valve V ₂ , heated by heater H ₂ to vaporize the cleaning solvent, and then passed through valve V ₇ and condenser C to vaporize the cleaning solvent. The coexisting moisture is discharged from line 10, and the cleaning solvent is removed from line 1.
1 back to line 1 and/or line 4 for reuse. The recovered cleaning solvent has the composition shown in Table 2. Formation of emulsion was observed in this product due to the presence of moisture.

[Table] From this table, it can be seen that the recovered perclean is of high purity. On the other hand, liquid substances such as oil and surfactant remaining at the bottom of the evaporator E are drained from the valve V ₈ into the oil tank T ₃ after several cycles of operation or when the amount exceeds a certain level. After the liquid components have been separated in this way, sludge with the properties and composition shown in Table 3 remains in tank _T1 .

[Table] When a considerable amount of sludge has accumulated at the bottom of tank T ₁ , use the cleaning solvent sent from decanter D through line 4, or a new solvent of the same type as the cleaning solvent used, or stir the remaining liquid in tank T ₁ . , mixed;
Leave it to stand for a certain period of time, and then remove the liquid from valve V ₆ , pump P ₁ ,
The cleaning solvent is sent to the evaporator E through the valve V ₂ , the cleaning solvent is collected in the decanter D, and the oil is extracted from the valve V ₈ to the oil tank T ₃ . This extraction operation is carried out 4 to 5 times at a cleaning solvent:sludge ratio of approximately 1:1 (the contact ratio of extraction cleaning solvent and sludge is 4 to 5 solvent/sludge by volume),
Repeat to extract oil and activator from the sludge at the bottom of tank _T1 . The extraction solvent/sludge ratio, extracted oil concentration (g/ml), and extraction rate are shown in Figure 2 (extraction temperature 23°C). As can be seen from this figure, 90% of the oil content is extracted into percrene at an extraction solvent/sludge ratio of 2 to 3. The sludge after this extraction operation has almost all of the oil removed as described above and is made up of solids and solvent.This sludge is heated by the heater _H1 at the bottom of the tank _T1 , Air blower B
By blowing heated air from the tank T 1 through the air heater H ₃ onto the sludge surface of the tank T ₁ .
The cleaning solvent remaining in the sludge is vaporized and recovered from the condenser C and decanter D via valve _V9 . Note that the heating of the sludge can also be performed using either the heater H ₁ or the air heater H ₃ if the processing time is sufficient. This sludge with no residual oil has a relatively wide heating range.
The temperature is significantly higher than the boiling point of the cleaning solvent, allowing the cleaning solvent to be dissipated and recovered. Figure 3 shows the dissipation and recovery rate of percrene in the sludge.
Can be collected. The sludge after perclean extraction and air dispersion loses oil, surfactants, and cleaning solvents, so its volume is reduced to about 1/3 of its initial volume, and it has a harmless composition as shown in Table 4, so it can be safely used as it is. Can be disposed of.

【table】

【table】 [Brief explanation of the drawing]

Figure 1 is a flow sheet showing the outline of the method of the present invention, and Figure 2 shows the oil extraction rate by solvent and the
The figure is a graph showing the dispersion and recovery rate of the solvent by air.

Claims (1)

[Claims] 1. The oily sludge discharged from the washing drum and the sludge derived from the filter material discharged from the filter are accumulated in a collection tank, and the accumulated sludge is left for a certain period of time to separate into liquid and solid components. The separated liquid is led to an evaporator, the solvent and oil contained in the liquid are separated, and the solvent is recovered.Then, the solvent is fed to the recovery tank and comes into contact with the solid content in the recovery tank. and leave it for a certain period of time,
The separated liquid is again separated into a liquid and a solid, and the separated liquid is again led to the evaporator and heated to separate the solvent and oil contained in the liquid and recover the solvent. A dry cleaning machine solvent characterized in that the solvent and oil contained in the sludge accumulated in the collection tank are removed and recovered by heating the solid content remaining in the sludge and recovering the solvent contained in the solid content. Sludge treatment method in tank.