JP4206949B2 - Cleaning method for water-soluble waste liquid treatment equipment - Google Patents

Description

The present invention relates to a cleaning method for a water-soluble waste liquid treatment apparatus for treating a waste liquid such as water-soluble cutting oil, and more particularly to a method for cleaning a heat transfer tube of a water-soluble waste liquid treatment apparatus for evaporating and concentrating water-soluble waste liquid using a heat transfer pipe. .

  As a device for treating waste liquid such as water-soluble cutting oil, this water-soluble waste liquid is sprayed on the outer surface of the heat transfer tube, concentrated by heating, and the evaporated water is taken out as condensed water, and then the oil is separated and removed from this condensed water. The structure which performs is known (for example, patent document 1). In such a waste liquid treatment apparatus, the concentrated waste liquid adheres as a scale to the outer surface of the heat transfer tube with the passage of time, and the heat transfer efficiency decreases. The surface is cleaned.

  However, since the waste liquid of chemicals used for cleaning is difficult to reuse and must be treated as waste, it not only increases the running cost but also causes an environmental burden.

As a configuration for removing the scale attached to the heat transfer tube, Patent Document 2 discloses that the scale is scattered by rotating the heat transfer tube (rotating coil) itself, but the equipment configuration becomes complicated. Moreover, it is difficult to improve existing facilities.
JP 2002-336841 A JP-A-8-243543

The present invention has been made in view of the above problems, and an object of the present invention is to provide a cleaning method for a water-soluble waste liquid treatment apparatus capable of efficiently cleaning a heat transfer tube for evaporating and concentrating water-soluble waste liquid.

The object of the present invention is to provide a heat transfer tube through which a heating medium passes and a nozzle for spraying liquid on the outer surface of the heat transfer tube, and the water-soluble waste liquid supplied from the waste liquid spray line through the nozzle A cleaning method for a water-soluble waste liquid treatment apparatus, comprising: an evaporator for evaporating and concentrating with a heat transfer tube; and a condenser for condensing steam generated in the evaporator to generate condensed water, wherein the water-soluble waste liquid is an interface It contains an activator and an insoluble oil, and vapor condensation water containing a surfactant is generated by evaporating and concentrating with the heat transfer tube, and an insoluble oil not containing the surfactant adheres to the surface of the heat transfer tube. This is achieved by a cleaning method for a water-soluble waste liquid treatment apparatus, wherein condensed water containing a surfactant is sprayed from the nozzle to the heat transfer tube.

According to the cleaning method of the water-soluble waste liquid treatment apparatus of the present invention, the heat transfer tube for evaporating and concentrating the water-soluble waste liquid can be efficiently cleaned.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram showing a water-soluble waste liquid treatment apparatus according to an embodiment of the present invention. This water-soluble waste liquid treatment apparatus 1 condenses the vapor generated in the evaporator 20, a waste liquid tank 10 that stores a water-soluble waste liquid such as a water-soluble cutting oil (coolant), an evaporator 20 that evaporates and concentrates the water-soluble waste liquid. The condenser 30 is provided.

  The waste liquid tank 10 is connected to the evaporator 20 via a waste liquid supply line 11, and an oil / water separator 12 is provided in the middle of the waste liquid supply line 11. The oil / water separator 12 has a known configuration (for example, a gravity type) that separates oil from waste liquid supplied from the waste liquid tank 10 to the evaporator 20, and the separated oil is supplied to the recovery tank 14 via the separation line 13. Collected.

  The evaporator 20 is a horizontal tube type evaporator in which a plurality of heat transfer tubes 21 are arranged so as to extend in the horizontal direction. Both ends of each heat transfer tube 21 are connected to the introduction chamber 22 and the discharge chamber 23, respectively. A heating medium supply line 24 is connected to the introduction chamber 22, and a heating medium such as heating steam supplied from a boiler (not shown) or the like is introduced into the introduction chamber 22 via the heating medium supply line 24. Then, it passes through the inside of the heat transfer tube 21 and is discharged into the discharge chamber 23.

  The evaporator 20 includes a waste liquid spraying line 25 that externally circulates the liquid inside. The waste liquid spraying line 25 is provided with a circulation pump 26 in the middle, and a nozzle 27 is attached to the tip. The liquid staying at the bottom is pumped up by the circulation pump 26 and sprayed from the top to the heat transfer tube 21 through the nozzle 27. Is configured to do. High concentration concentrated waste liquid evaporated and concentrated on the surface of the heat transfer tube 21 is supplied to the recovery tank 14 via a concentrated liquid discharge line 28 branched and connected to the waste liquid spraying line 25.

  On the other hand, the steam generated when the water-soluble waste liquid is heated by the heat transfer tube 21 is supplied to the condenser 30 via the steam discharge line 31. The steam discharge line 31 is branched and connected to an ejector 29 provided in the middle of the heating medium supply line 24, and a part of the steam generated by the evaporator 20 is sucked into the heating medium supply line 24 by the ejector 29, It is supplied again to the evaporator 20. A demister 201 that collects mist contained in the vapor is disposed in the upper part of the evaporator 20.

  The condenser 30 condenses steam by exchanging heat with cooling water stored in a cooling tower (not shown) to generate condensed water. A liquid-sealed vacuum pump 32 is connected to the condenser 30, and the inside of the condenser 30 and the inside of the evaporator 20 and the discharge chamber 23 communicating with the condenser 30 are operated by the operation of the vacuum pump 32. It is comprised so that it may hold | maintain in a pressure reduction state. The discharge side of the vacuum pump 32 is connected to a gas-liquid separator (not shown), and the separated liquid is used as a liquid sealing gas of the vacuum pump 32.

  Further, a condensed water discharge line 33 is connected to the condenser 30, and the generated condensed water is, for example, a membrane-type oil-water separator by a condensed water pump 34 provided in the middle of the condensed water discharge line 33. 35. The condensed water introduced into the oil / water separator 35 by the condensed water pump 34 includes condensed water condensed in the discharge chamber 23 of the evaporator 20.

  The oil component separated by the oil / water separator 35 is collected in the collection tank 14 via the separation line 36, while the condensed water from which the oil component has been removed passes through a water treatment device (not shown) using microorganisms or the like to the river. And so on.

  In the water-soluble waste liquid treatment apparatus 1, a first opening / closing valve 41 is provided on the downstream side of the condensed water pump 34 in the condensed water discharge line 33, and between the condensed water pump 34 and the first opening / closing valve 41. A branch water condensate tank 42 is provided. The condensed water tank 42 includes a water level sensor 42a, and the opening / closing of the first on-off valve 41 is controlled based on detection of the water level sensor 42a. These configurations can be easily retrofitted to existing equipment.

  The condensed water tank 42 is connected to the waste liquid spraying line 25 via the condensed water supply line 43. Condensed water can be supplied from the condensed water tank 42 by opening and closing a supply valve (not shown) of the condensed water tank 42. The condensed water supply line 43 may be connected to the evaporator 20 instead of being connected to the waste liquid spraying line 25.

  According to the water-soluble waste liquid treatment apparatus 1 having the above configuration, a water supply waste liquid is supplied from the waste liquid tank 10 to the evaporator 20 via the waste liquid supply line 11 by opening a supply valve (not shown) of the waste liquid tank 10. Then, the circulation pump 26 is operated to circulate the water-soluble waste liquid to the outside, and the heating medium is passed through the heat transfer tube 21 through the heating medium supply line 24. Thereby, the water-soluble waste liquid is evaporated and concentrated on the surface of the heat transfer tube 21, and the concentration of the waste liquid gradually increases. The concentrated waste liquid is discharged from the concentrated liquid discharge line 28 to the recovery tank 14.

  On the other hand, the steam generated in the evaporator 20 is condensed in the condenser 30 via the steam discharge line 31 and becomes condensed water. The generated condensed water is conveyed by the condensed water pump 34, but when the water level of the condensed water tank 42 is less than a predetermined value, the first on-off valve 41 is closed based on the detection of the water level sensor 42a. The condensed water is supplied to the condensed water tank 42. When the water level sensor 42a detects that the water level in the condensed water tank 42 has reached a predetermined value, the first on-off valve 41 is switched to the open state, and the condensed water generated by the condenser 30 is transferred to the oil / water separator 35. Supplied towards.

  If the heat transfer tube 21 needs to be cleaned due to the accumulation of scale on the surface of the heat transfer tube 21 due to the treatment of the water-soluble waste liquid described above, the apparatus is stopped and the liquid in the evaporator 20 is recovered. After all the fuel is discharged to the tank 14, a cleaning operation is performed. In the washing operation, the supply valve (not shown) of the condensed water tank 42 is opened and the circulation pump 26 is operated. Thereby, the condensed water stored in the condensed water tank 42 is sprayed to the heat transfer tube 21 via the waste liquid spraying line 25.

  A water-soluble waste liquid such as a water-soluble cutting oil contains a surfactant in order to have a water-soluble property. Since most of the contained surfactants have a low boiling point (for example, 60 to 80 ° C.), most of the surfactant evaporates with water on the surface of the heat transfer tube 21. That is, the scale components adhering to the surface of the heat transfer tube 21 are mainly insoluble oil components (mineral oil, fatty oil, etc.) that do not contain a surfactant. The surfactant contained in the water-soluble waste liquid is not particularly limited, such as anionic, cationic, nonionic, and amphoteric.

  On the other hand, the condensed water stored in the condensed water tank 42 contains evaporated surfactant. Therefore, by spreading this condensed water from the nozzle 27 to the heat transfer tube 21, the scale attached to the heat transfer tube 21 is water-solubilized, and cleaning can be performed efficiently. The condensed water staying at the bottom of the evaporator 20 is externally circulated by the operation of the circulation pump 26.

  After the heat transfer tube 21 is cleaned, the water-soluble waste liquid can be supplied from the waste liquid tank 10 to the evaporator 20 and the treatment of the water-soluble waste liquid can be started again. In the present embodiment, since the condensed water obtained by condensing the evaporated portion of the water-soluble waste liquid is used as the cleaning liquid for the heat transfer tube 21, it is necessary to discard the water-soluble waste liquid before supplying it to the evaporator 20 like the conventional cleaning liquid. The water-soluble waste liquid can be supplied in a state where the condensed water used for cleaning remains in the evaporator 20. Therefore, it is possible to speed up the processing work, and it is possible to reduce waste of resources and environmental load by suppressing waste.

1 is an overall configuration diagram showing a water-soluble waste liquid treatment apparatus according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water-soluble waste liquid processing apparatus 10 Waste liquid tank 20 Evaporator 21 Heat transfer pipe 25 Waste liquid spraying line 26 Circulation pump 27 Nozzle 30 Condenser 33 Condensate water discharge line 34 Condensate water pump 41 First on-off valve 42 Condensate water tank 43 Condensate water supply line

Claims (2)

Evaporation having a heat transfer tube through which the heating medium passes and a nozzle for spraying liquid on the outer surface of the heat transfer tube, and evaporating and concentrating the water-soluble waste liquid supplied from the waste liquid spray line through the nozzle through the heat transfer tube And a water-soluble waste liquid treatment apparatus cleaning method comprising a condenser and a condenser for condensing steam generated in the evaporator to produce condensed water,
The water-soluble waste liquid contains a surfactant and an insoluble oil, and vaporized condensed water containing a surfactant is generated by evaporating and concentrating with the heat transfer tube, and the insoluble oil containing no surfactant is added to the water-soluble waste liquid. Adheres to the surface of the heat transfer tube,
A method for cleaning a water-soluble waste liquid treatment apparatus, characterized in that condensed water containing a surfactant is sprayed from the nozzle to the heat transfer tube. The method for cleaning a water-soluble waste liquid treatment apparatus according to claim 1, wherein the water-soluble waste liquid is a water-soluble cutting oil.

Images