Chemical sludge drying system and method

Abstract

This invention provides a chemical sludge drying system that enables more reliable removal of liquid components from chemical sludge. [Solution] The system includes a chamber 47 from which liquid components are removed from chemical sludge by filtration with a filter, an openable / closable liquid supply valve 65 for supplying chemical sludge to the chamber 47, an openable / closable dewatering valve 67 for supplying compressed air to the chamber 47, an openable / closable filtrate valve 73 for discharging the filtrate from the chamber 47 during filtration, an openable / closable pressure reducing valve 69 for reducing the pressure of the chamber 47 with a vacuum source, and an openable / closable atmospheric release valve 70 for returning the chamber 47 to atmospheric pressure.

Description

Technical Field

[0001] The present invention relates to a chemical sludge drying system and method used for electrodeposition coating of products.

Background Art

[0002] Regarding the treatment of conventional chemical sludge, there is a chemical sludge treatment method shown in Patent Document 1. In this method, chemical sludge is discharged from a chemical treatment tank together with some chemical treatment liquid and sent to a sedimentation tank. Most of the chemical sludge is separated from the chemical treatment liquid by sedimentation treatment in the sedimentation tank and becomes a cake. After the chemical sludge that has become a cake is discharged from the sedimentation tank, the liquid component is removed by a cloth-like roll filter and temporarily stored in a storage tank.

[0003] There was a problem that the chemical sludge stored in the storage tank was likely to have insufficient removal of the liquid component and was not suitable for being discarded as it was.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem to be solved is that the removal of the liquid component from the chemical sludge was insufficient.

Means for Solving the Problems

[0006] The present invention includes a chamber from which liquid components are removed from a chemical sludge liquid by filtration with a filter; an openable and closable liquid supply valve for supplying the chemical sludge liquid to the chamber; an openable and closable deliquidation valve for supplying compressed air to the chamber; an openable and closable filtrate valve for discharging the filtrate from the chamber during filtration; an openable and closable pressure reducing valve for reducing the pressure inside the chamber; and a control panel for controlling the deliquidation valve and the pressure reducing valve. The chamber comprises an upper chamber and a lower chamber, which are joined together with a sealing member interposed between them, the lower chamber is supported so as to be tiltable relative to the upper chamber, and the filter is wound up to sequentially rearrange unused portions on the lower chamber. The present invention provides a chemical sludge drying system that, under the control of the control panel, opens the dewatering valve and supplies compressed air to press the chemical sludge on the filter against the filter, thereby removing the liquid components by filtration, and further removes the liquid components from the filtered chemical sludge by vaporization through vacuuming in the chamber via the vacuum valve, also under the control of the control panel.

[0007] Furthermore, the present invention provides a method for drying chemical sludge, which involves receiving the chemical sludge liquid from a separation tank into a chamber, removing the liquid components by filtration with a filter while receiving compressed air, and then reducing the pressure inside the chamber to further remove the liquid components from the filtered chemical sludge. [Effects of the Invention]

[0008] According to the present invention, the removal of liquid components from chemical sludge can be performed more reliably. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a conceptual diagram of an electrodeposition coating line according to one embodiment of the present invention. [Figure 2] Figure 2 is a conceptual diagram showing the chemical conversion process of the electrodeposition coating line in Figure 1. [Figure 3] Figure 3 is a conceptual diagram of a drying tank used in the chemical conversion process shown in Figure 2, employing a chemical conversion sludge drying system according to one embodiment of the present invention. [Figure 4] Figure 4 is a conceptual diagram showing the discharge of chemical sludge from the drying tank in Figure 3 to the containment tank. [Modes for carrying out the invention]

[0010] One embodiment of the chemical sludge drying system comprises a chamber 47, a liquid supply valve 65, a liquid removal valve 67, a filtrate valve 73, and a pressure reducing valve 69. The chamber 47 receives the chemical sludge liquid and removes liquid components from a filter. The liquid supply valve 65 is an openable and closable valve that supplies the chemical sludge liquid to the chamber 47. The liquid removal valve 67 is an openable and closable valve that supplies compressed air to the chamber 47. The filtrate valve 73 is an openable and closable valve that discharges the filtrate from the chamber 47. The pressure reducing valve 69 is an openable and closable valve that reduces the pressure in the chamber 47.

[0011] This chemical sludge drying system is contained within a chamber 47 and may include a heating section for heating the inside of the chamber 47.

[0012] In one embodiment of the chemical sludge drying method, the liquid components are removed by filtration with a filter while compressed air is applied in a chamber 47 that receives the chemical sludge liquid, and then the pressure inside the chamber is reduced to further remove the liquid components from the filtered chemical sludge by vaporization. [Examples]

[0013] Figure 1 is a conceptual diagram of an electrodeposition coating line according to one embodiment of the present invention.

[0014] As shown in Figure 1, the unpainted workpiece W (see Figure 2), which is a product after pressing or other processes, is transported to the electrodeposition coating line by an overhead conveyor 1. Note that a standard overhead conveyor 1 can be used, and is shown conceptually only by arrows in the figure.

[0015] Work W is a line that transports products of varying sizes and shapes, such as large parts like truck bed frames and other small parts, and is electrodeposited on the same line. However, it is also possible to transport only identical workpieces. In the diagram, work W is shown conceptually only.

[0016] This workpiece W is sequentially passed through a preliminary degreasing process 3, a degreasing 1 process 5, and a degreasing 2 process 7 to remove press oil, iron powder due to welding, and other dust. Next, the workpiece W is washed through a water washing 1 process 9 and a water washing 2 process 11.

[0017] After washing, the workpiece W is processed by a chemical conversion treatment liquid in the chemical conversion process 13, and reaches the electrocoating process 21 through a water washing 3 process 15, a water washing 4 process 17, and a pure water washing process 19. In the electrocoating process 21, electrocoating is applied to the surface of the workpiece W.

[0018] From the electrocoating process 21, excess paint is recovered through a UF water washing 1 process 23, a UF water washing 2 process 25, and a UF water washing 3 process 27.

[0019] Finally, a drying process is performed in the drying process 29, and the electrocoated product is discharged.

[0020] [Chemical Conversion Process] Figure 2 is a conceptual diagram showing the chemical conversion process of the electrocoating line in Figure 1.

[0021] As shown in Figure 2, the chemical conversion process 13 includes a chemical conversion treatment tank 31. Inside the chemical conversion treatment tank 31, a zinc phosphate chemical conversion treatment liquid 33 is contained as the chemical conversion treatment liquid.

[0022] In the chemical conversion process 13, for the chemical conversion treatment tank 31, a painting hanger 35 carrying the workpiece W is transferred on the line by an overhead conveyor 1. In the chemical conversion treatment tank 31, the painting hanger 35 descends, and the workpiece W is immersed in the chemical conversion treatment liquid 33.

[0023] A separation tank 39 is connected to the chemical conversion treatment tank 31 via a pump 37, and a drying treatment tank 43 is connected to the separation tank 39 via a pump 41. A sludge box 45 is arranged at the discharge port of the drying treatment tank 43.

[0024] Therefore, the pump 37 drives the chemical sludge containing the chemical treatment liquid out of the chemical treatment tank 31 and sends it to the separation tank 39. After separation treatment in the separation tank 39, the slurry-like chemical sludge is transferred to the drying treatment tank 43 by the drive of the pump 41.

[0025] In the drying tank 43, the slurry-like chemical sludge is dewatered and dried, and the dewatered and dried cake-like chemical sludge is discharged into the sludge box 45. The chemical treatment liquid removed from the chemical sludge is circulated back to the chemical treatment tank 31.

[0026] [Drying tank] Figure 3 is a conceptual diagram of a drying tank used in the chemical conversion process shown in Figure 2, employing a chemical conversion sludge drying system according to one embodiment of the present invention. Figure 4 is a conceptual diagram of the case when chemical conversion sludge is discharged from the drying tank in Figure 3 to a storage tank.

[0027] As shown in Figures 3 and 4, the drying tank 43 includes a chamber 47. The chamber 47 receives the chemical sludge from the separation tank 39 and removes liquid components such as water by filtration with a filter 55.

[0028] Chamber 47 partitions a sealed space. Liquid components are removed from the chemical sludge within this sealed space. In this embodiment, chamber 47 is configured by combining an upper chamber 49 and a lower chamber 51, with a sealing member 50 interposed between them. The upper chamber 49 is fixed to the base frame 53, and the lower chamber 51 is supported so as to be able to tilt relative to the upper chamber 49.

[0029] The filter box 57 of the filter 55 is attached to the upper chamber 49, and the winding roller 59 is attached to the lower chamber 51. The arrangement of the filter box 57 and the winding roller 59 can be set arbitrarily.

[0030] The filter 55 is a paper filter, which is pulled out from the filter box 57 and placed on the lower chamber 51 within the chamber 47. This filter 55 can be pulled out of the chamber 47 and wound onto the winding roller 59. Therefore, the unused portion of the filter 55 placed on the lower chamber 51 can be sequentially rearranged on the lower chamber 51 by winding it onto the winding roller 59 as needed.

[0031] The lower chamber 51 is formed in a concave shape below the area where the filter 55 is placed, so that it can receive the chemical treatment liquid filtered by the filter 55.

[0032] A branch pipe 61 is connected to the upper chamber 49, and a portion of a separate hot water pipe 63 is routed inside, forming a heating section.

[0033] Each outlet of the branch pipe 61 is fitted with a liquid supply valve 65, a liquid removal valve 67, a pressure reducing valve 69, and an atmospheric release valve 70, which can be opened and closed.

[0034] The liquid supply valve 65 is connected to the separation tank 39 via the pump 41. In other words, the liquid supply valve 65 is interposed between the separation tank 39 and the chamber 47, and when open, it allows chemical sludge to be supplied from the separation tank 39 to the chamber 47, particularly onto the filter 55.

[0035] The liquid supply valve 65 can be opened and closed by control from a PLC (control panel) (not shown). The PLC is a computer that has a processor and memory, and controls the chemical sludge drying system by executing a program in the memory with the processor.

[0036] The dewatering valve 67 is connected to a compressed air source, such as a compression pump, via dewatering piping. In other words, when the dewatering valve 67 is open, compressed air can be supplied to the chamber 47. The dewatering valve 67 is also opened and closed by control of the PLC.

[0037] The pressure reducing valve 69 is connected to a vacuum pump, which is the vacuum source. In other words, when the pressure reducing valve 69 is open, it is possible to reduce the pressure in the chamber 47. The pressure reducing valve 69 is also opened and closed by control of the PLC.

[0038] The atmospheric release valve 70 opens the chamber 47 to the atmosphere and is an openable and closable valve that returns the chamber 47 to atmospheric pressure. The atmospheric release valve 70 is also opened and closed by control of the PLC.

[0039] The hot water pipe 63 is connected to a hot water source via a pump (not shown). Therefore, the hot water pipe 63 generates heat from the hot water source passing through it, heating the inside of the chamber 47.

[0040] A filtrate pipe 71 is connected to the lower chamber 51. A filtrate valve 73, which can be opened and closed, is attached to the filtrate pipe 71. Therefore, when the filtrate valve 73 is open, the filtrate can be discharged from the chamber 47. This valve 73 is opened and closed by control of a PLC. The filtrate valve 73 is interposed between the filtrate pipe 71 and the pipe connecting it to the chemical treatment tank 31. The filtrate valve 73, the liquid supply valve 65, the liquid removal valve 67, the pressure reducing valve 69, and the atmospheric release valve 70 may also be manually openable and closable.

[0041] A tilting drive mechanism 75 is interposed between the lower chamber 51 and the base frame 53. The tilting drive mechanism 75 includes a cylinder 77 and a link mechanism 79. The cylinder 77 is connected to the base frame 53, and the link mechanism 79 is connected to the lower surface of the lower chamber 51. As a result, the lower chamber 51 is in a non-tilted state relative to the upper chamber 49 when the cylinder 77 is extended, and tilted relative to the upper chamber 49 when the cylinder 77 is retracted.

[0042] The PLC controls not only the opening and closing of the liquid supply valve 65, the liquid removal valve 67, the pressure reducing valve 69, the atmospheric release valve 70, and the filtrate valve 73, but also the driving of the cylinder 77 and the winding roller 59.

[0043] In the drying tank 43, the deliquidation valve 67, pressure reducing valve 69, and atmospheric release valve 70 are initially closed, and the filtrate valve 73 and liquid supply valve 65 are opened. When the liquid supply valve 65 is opened, the chemical sludge is sent from the separation tank 39 to the filter 55 in the chamber 47 via the branch pipe 61.

[0044] The chemical sludge liquid sent into the chamber 47 is received by the filter 55, where the chemical sludge is collected and the liquid components permeate through the filter 55. Thus, the chemical sludge is filtered. The filtrate that has passed through the filter 55 is discharged from the filtrate piping 71 through the filtrate valve 73. The filtrate discharged from the filtrate valve 73 is circulated to the chemical treatment tank 31.

[0045] As a certain amount of chemical sludge liquid is sent into the chamber 47 while this filtration is being performed, the liquid supply valve 65 is closed and the liquid removal valve 67 is opened. When the liquid removal valve 67 is opened, compressed air is sent into the chamber 47 via the branch pipe 61. At this time, hot water is passed through the hot water pipe 63.

[0046] Inside the chamber 47, compressed air passes through the filter 55 and exits to the filtrate valve 73. At this time, the compressed air presses the chemical sludge on the filter 55 against the filter 55, and the liquid components contained in the chemical sludge permeate the filter 55 and are discharged from the filtrate valve 73. The filtrate discharged from the filtrate valve 73 is circulated to the chemical treatment tank 31. This performs pressurized filtration of the chemical sludge.

[0047] The chemical sludge filtered in this manner forms a cake-like substance on filter 55.

[0048] Next, the dewatering valve 67 and the filtrate valve 73 are closed, and the pressure reducing valve 69 is opened.

[0049] The chamber 47 is depressurized by a depressurizing pump via a depressurizing valve 69. This depressurization lowers the boiling point inside the chamber 47, causing the liquid components in the chemical sludge on the filter 55 to vaporize and be dehydrated. At this time, the chamber 47 is heated by hot water or hot water passing through a hot water pipe, which further promotes the vaporization of liquid components from the chemical sludge.

[0050] Thus, in this embodiment, the liquid component is more reliably removed from the chemical sludge by pressurizing and depressurizing within the same chamber 47. The vaporized liquid component is discharged from the depressurization valve 69.

[0051] Next, the pressure reducing valve 69 is closed and the atmospheric release valve 70 is opened to return the area around the sludge in the chamber 47 to atmospheric pressure.

[0052] Then, as shown in Figure 4, the cylinder 77 is driven to tilt the lower chamber 51. As the lower chamber 51 tilts, the winding roller 59 winds up the filter 55, and the chemical sludge with reduced moisture content or that has dried is discharged out of the chamber 47 and collected in the sludge box 45.

[0053] Therefore, in the chamber 47 that receives the chemical sludge liquid, the liquid components are first removed by filtration with compressed air using a filter 55, and then the pressure inside the chamber 47 is reduced to further remove the liquid components from the filtered chemical sludge by vaporization.

[0054] [Effects and Effects] As explained above, in the chamber 47 that receives the chemical sludge, the liquid components are removed by filtration with compressed air using a filter 55. Then, the pressure inside the chamber 47 is reduced to further remove the liquid components from the filtered chemical sludge by vaporization. This reduces the liquid component content of the chemical sludge discharged into the sludge box 45. As a result, the disposal of the chemical sludge can be carried out easily and inexpensively.

[0055] Furthermore, the chamber 47 is heated or warmed by hot water or hot water passing through the hot water pipe 63 to promote vaporization from the chemical sludge, thereby reliably reducing the liquid component content of the chemical sludge.

[0056] Furthermore, since the chamber 47 that performs pressurized filtration is equipped with a function to vaporize the liquid components from the sludge inside the chamber 47 by vacuuming with a vacuum pump or the like, the chamber 47 and its sealing structure can be shared, making the device compact and inexpensive. [Explanation of symbols]

[0057] 39 Separation tank 47 Chambers 55 filters 63 Hot water piping (heating section) 65 Liquid delivery valve 67 Dehydration valve 69 Pressure Reducing Valve 70 Atmospheric release valve 73 Filtrate valve Double job

Claims

1. A chamber from which liquid components are removed from chemical sludge by filtration, A liquid supply valve that can be opened and closed for supplying the chemical sludge to the chamber, A removable dewatering valve that supplies compressed air to the chamber, A filtrate valve that can be opened and closed for discharging the filtrate from the chamber during filtration, A pressure reducing valve that can be opened and closed to reduce the pressure inside the chamber, An openable and closable atmospheric release valve that returns the inside of the chamber to atmospheric pressure, A control panel for controlling the liquid removal valve and the pressure reducing valve, Includes, The aforementioned chamber consists of an upper chamber and a lower chamber, The upper chamber and the lower chamber are joined together with a sealing member interposed between them. The lower chamber is supported so as to be able to tilt relative to the upper chamber, The filter, by winding, sequentially rearranges the unused portion on the lower chamber. The control panel opens the dewatering valve and the compressed air supplied pushes the chemical sludge on the filter against the filter, thereby removing the liquid components by filtration. The liquid components are further removed from the filtered chemical sludge by vaporization through the vacuum pump in the chamber via the pressure reducing valve controlled by the control panel. Chemical sludge drying system.

2. A chemical sludge drying system according to claim 1, The chamber includes a heating unit that heats the inside of the chamber, Chemical sludge drying system.

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