JPS60187306A - Process for washing ultrafiltration membrane module - Google Patents

Abstract

PURPOSE:To eliminate requirement for frequency restarting of a pump and to avoid severe using condition of the pump by driving a pump provided between a ultrafiltration membrane and a filtrate tank always and feeding and back-feeding the filtrate by changing over a changing circuit for changing the passage of the filtrate toward the forward and backward direction. CONSTITUTION:A pump 6 is driven continuously, and feeding of the filtrate from an ultrafilter membrane module 8 to a filtrate tank and feeding back of the filtrate for backwashing is executed by the operation of the three-way valves 81, 82 in a forward and backward change-over circuit 8 of the filtrate passage. In an electrodeposition process, the electrodeposition operation is performed usually in an electrodeposition tank 1 and the electrodeposition liquid is circulated through an ultrafiltration membrane module. The modules 2 is backwashed every fixed time. On a holiday during suspension of the electrodeposition work, the backwashing of the module is performed more frequently than usual days. Even in this case, the pump is driven continuously as usual but frequent restarting of the pump at time of each backwashing is unnecessary.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for cleaning ultramembrane modules.

In controlling the concentration of the electrodeposition paint in the electrodeposition process, it is necessary to keep the concentration of the electrodeposition solution constant by removing the liquid component as the solid content is consumed as the electrodeposition progresses. For this purpose, the electrodeposition solution is circulated through the ultramembrane module, and the p.
It is known to control the concentration of an electrodeposition solution by setting the amount of the solution to a predetermined amount.

In this case, the F liquid is sent to the P liquid tank, and most of the F liquid in this P liquid tank (approximately 95%) is used for cleaning the electrodeposited products, and the remainder is used for backwashing the module. There is. Figure 1 shows a conventional several-P circuit in a membrane module.
During the period when the P liquid from the module 1' is sent to the P liquid tank 2', the three-way valve 3' is opened in the direction of arrow A', and during the period of backwashing, the pump P' is driven and the three-way pulp valve 3' is opened. 3' is opened in the direction of arrow B'.

By the way, on holidays when electrodeposition is not being performed, there is no need to clean the electrodeposited products, so use most of the F solution for backwashing the module to thoroughly clean the module while electrodeposition is stopped. That is reasonable. However, while backwashing during electrodeposition is normally done once every 30 minutes,
It is effective to perform backwashing at a frequency of once every 5 minutes when electrodeposition is stopped; if this frequency is used, the pump will have to start and stop frequently, and the operating conditions of the pump will be harsh. Become.

In view of these points, the present invention proposes a method for cleaning an ultramembrane module that enables frequent backwashing when the electrodeposition is stopped while the pump is continuously operated.

In other words, the method for cleaning an ultramembrane module according to the present invention involves circulating the stock solution through the ultramembrane module, feeding the P solution from the module into the F solution tank, and using this P solution to clean the ultramembrane module at regular intervals. In the method of backwashing the module, a pump and a p-liquid flow path forward/reverse switching circuit are provided between the module and the lachrymal fluid tank, the pump is constantly operated, and the p-liquid flow path forward/reverse switching circuit is switched. This method is characterized by feeding the P liquid from the module to the P liquid tank and returning the P liquid from the F liquid tank in the backwash reservoir to the module.

The present invention will be explained below with reference to the drawings.

In Fig. 2, 1 is an electrodeposition tank, 2 is an ultramembrane module,
3 is a circulation pump, and 4 is a valve, and the electrodeposition paint in the electrodeposition tank 1 is circulated through the ultrafilm module 2 by operation of the circulation pump 3. 5 is P liquid tank, 6 is pump, 7
8 is a constant flow valve, 8 is a three-way valve 81 and 82, and piping 83 to 8
5 is a P liquid flow path forward/reverse switching circuit. Reference numeral 9 denotes a P liquid overflow receiver 10, which is a return pipe that communicates between the overflow receiver 9 and the electrodeposition tank 1, and a valve 11 is provided in the middle.

In the above, the pump 6 is in continuous operation, and the P liquid flow path forward/reverse switching circuit 8 is switched to the arrow A by operating the three-way valve 81,82.
If the flow is opened in the direction shown in FIG. Then, the P liquid in the P liquid tank 5 can be sent back to the F liquid chamber of the module 2 by the pump 6, and the module 2 can be backwashed.

In the above, electrodeposition is performed on weekdays, the electrodeposition paint is replenished, and the P liquid is collected from the module 2 in balance with the consumption of solid content in the electrodeposition paint, and this is sent to the P liquid tank 5. (Valve 4 of the circulation circuit is fully open). A portion (for example, about 50%) of this collected P solution is sent back at regular intervals (for example, once every 30 minutes for 30 patients) to backwash module 2.
The F liquid overflowing from the F liquid tank 5 acts to clean the electrodeposited product.

When electrodeposition is stopped on holidays, backwashing should be performed more frequently than on weekdays (for example, use approximately 60% of the P solution and backwash once every 5 minutes).
In this case, the P liquid overflowing from the P liquid tank 5 is returned to the electrodeposition bath 1 via the return pipe 10 by opening the valve 11 of the return pipe 10. Also,
It is advantageous if the valve 4 of the stock solution circulation circuit is left half-open to reduce the flow rate of the stock solution (the circulation pump 3 is continuously operated even on holidays), as it facilitates the removal of deposits by backwashing.

As mentioned above, in the ultra membrane module cleaning method according to the present invention, backwashing of the module with liquid F on holidays when electrodeposited articles are not cleaned with liquid P is replaced with backwashing on weekdays. Although the purpose is to perform the operation more frequently than in comparison, this purpose can be achieved by continuous operation of the pump on the other side of F, and there is no need to frequently re-drive the pump each time the backwash is performed, so it is possible to reduce the harshness of the pump. Terms of use can be avoided,
It's advantageous.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a conventional method of cleaning an ultramembrane module, and FIG. 2 is an explanatory diagram showing a method of cleaning an ultramembrane module according to the present invention. In the figure, 1 is an electrodeposition tank, 2 is an ultramembrane module, 3 is a circulation pump, 5 is an F liquid tank, 6 is a pump, and 8 is a P liquid flow path forward/reverse switching circuit. 6-

Claims (1)

[Claims] In a method in which the stock solution is circulated through an ultramembrane module, the P solution from the module is sent to the P solution tank, and the module is backwashed at regular intervals using this F solution, the module and tear tank are separated. A pump and a forward/reverse switching circuit for the F liquid flow path are installed between the modules, and the pump is constantly operated, and by switching the P liquid flow path forward/reverse switching circuit, the P liquid is supplied from the module to the P liquid tank and backwashing is performed. A method for cleaning an ultramembrane module, characterized in that liquid F is sent back from a Nodame liquid E tank to the module.