JPH0223203B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dewatering method and apparatus for a filter press.

Conventionally, dehydration using a filter press requires a low pump pressure in the initial process until the filtration chamber is filled with the stock solution, but gradually higher pressure is required as dehydration begins. Therefore, in the dehydration process, it is preferable to use a pump that can deliver the stock solution at a large volume and low pressure in the early stage and at a small volume and high pressure in the latter stage. However, in reality, it is difficult to use the pump properly, so it is necessary to control the time to carry out the process. For what we need, we select a pump with a high head and the required capacity, but in practical terms, a high head will cause a rapid pressure rise, which can easily damage the filter cloth of the filter press, so we recommend using a variable speed motor. In some cases, equipment costs increase, and Montblanc pumps are sometimes used, but they have drawbacks such as their capacity, which is not comparable to that of centrifugal pumps, although they can perform high-pressure dewatering in a short period of time.

In order to solve the above-mentioned drawbacks, the present invention connects a low head main pump and an auxiliary pressure booster injection device for high pressure generation in parallel on the water injection side of a filter press, and connects the main pump for low pressure and the auxiliary pressure booster injection device for high pressure generation in parallel. 0 during one dehydration process while operating the injection device alternately.
This is a method and device for efficient dewatering by repeatedly performing sawtooth injection pressure from pressure to maximum pressure in one cycle.The main pump has low horsepower, reducing equipment and operating costs, and the filter cloth It is characterized by less damage to the water and efficient dehydration.

Hereinafter, the configuration of the present invention will be explained with reference to practical example diagrams.

In a filter press 6 in which a filter frame 3 mounted at a distance between fixed plates 1 and 2 is pressed by a press plate 5 connected to an extrusion cylinder 4, the water injection pressure is 5.
The main pump 7 with a low head of up to ² Kg/cm is connected to the inlet of the filter press 6 through a lift pipe 8, and a solenoid valve 9 is connected to the lift pipe 8, and a piston is connected to the rod of a hydraulic cylinder 10. The discharge port 12 of a cylinder-type pressure booster pump 11 capable of generating a water injection pressure of up to 20 kg/cm ² is connected to the water pump 8 at a position closer to the filter press 6 than the solenoid valve 9, and the water is removed during the dewatering process of the filter press 6. , the main pump 7 injects water and performs low-pressure dehydration, then closes the solenoid valve 9 and operates the pressure booster pump 11 with the hydraulic cylinder 10 while injecting the raw water in the pressure booster pump 11 into the pumping pipe 8 at high pressure. Then, the dehydration pressure of the filter press 6 is increased to the maximum pressure to perform high-pressure dehydration, and then the dehydration pressure is returned to 0 while retracting the piston in the pressure booster pump 11 using the hydraulic cylinder 10, and the solenoid valve 9 is opened again. The dewatering process is then repeated, and the raw water liquid is dehydrated while repeatedly pressurizing the filter press 6 with a sawtooth type dewatering pressure that combines low-pressure dehydration and high-pressure dehydration. In addition, 13,1 in the figure
3' is a hydraulic unit, 14 is a flow meter, and 15 is a high-pressure pump for injecting ground water into the piston of the pressure booster pump.

Next, the effects of the present invention will be explained with reference to practical example diagrams.

In the dehydration method and apparatus of the present invention,
First, each filter frame 3 of the filter press 6 is pressed and joined with the press plate 5 linked to the extrusion cylinder 4, and when the oil pressure of the extrusion cylinder 4 rises and maintains a constant pressure, the main pump 7 starts and the solenoid valve 9 starts. The valve is opened and the raw liquid is sent to the filter press 6 at low pressure to start dehydration. At this time, the piston of the pressure booster pump 11 is retracted in a no-pressure state, and the main pump 7 is used for low-pressure dehydration for several seconds. Afterwards, the solenoid valve 9 closes, the hydraulic unit 13' starts, and the hydraulic cylinder 10 moves the piston of the pressure booster pump 11 forward while pumping the raw liquid in the pressure booster pump 11 into the pumping pipe 8.
The dewatering pressure in the filter press 6 is increased to a predetermined maximum pressure, and the pressurization speed by the pressure booster pump 11 is controlled by the flow rate adjustment valve in the hydraulic unit 13'. It is possible to adjust the efficiency dehydration pressure according to the type of stock solution by adjusting it at will. The high-pressure dehydration time is determined by detecting the dehydration flow rate using a timer or a flow meter, and after holding it for a certain period of time (about 1 minute), the hydraulic cylinder 10 operates in reverse and the piston of the pressure booster pump 11 retreats.
The dewatering pressure immediately goes from zero pressure to negative pressure, and after a few seconds, the solenoid valve 9 is opened again, and the piston in the booster pump 11 retreats, and low-pressure dehydration is carried out while pressurizing the stock solution from the pumping pipe 8 into the filter press 6. It is a beginning. FIG. 2 shows a diagram of the dehydration pressure applied to each filter frame of the filter press 6. In the first dehydration cycle, OA shows the low pressure applied by the main pump 7, and this is applied by the pressure booster pump 11.
The pressure is increased to the maximum pressure along AB, and after maintaining the maximum pressure as shown in BC, the piston of the pressure booster pump 11 retreats at point C, and the dewatering pressure decreases to point D, where it becomes 0 pressure, and as shown in DE. This shows a state in which the solenoid valve 9 is opened again at point E due to negative pressure acting on it. Figure 3 shows a dehydration flow rate diagram when the dehydration pressure shown in Figure 2 is applied to the filter press, and the first dehydration flow rate is as shown in 0-a-b-c-d. It's changing. By repeating the dewatering pressure as shown in Figure 2, the dewatering flow rate changes as a'-b'-c', a''-b''-c''. The dewatering flow rate line F using a conventional high-head pump is shown.
The dehydration flow rate curve according to the present invention is located upwards, and the amount of dewatering clearly increases, that is, the amount of dewatering increases more with repetitive dehydration using sawtooth pressure than with constant pressure type dehydration, especially the DE in Figure 2. The negative pressure shown in Fig. 1 acts on the filter frame and detaches part of the particulates clogging the filter cloth, which can increase the dewatering flow rate during the next pressurization. Therefore, equipment costs can be greatly reduced, operating costs can be reduced, and high pressure does not act directly on the filter cloth, preventing damage, etc., and making dewatering using a filter press more efficient. , which has the remarkable effects mentioned above.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a dewatering method and dewatering apparatus according to an embodiment of the present invention, FIG. 2 is a diagram of the dewatering pressure applied in the filter press, and FIG. 3 is a diagram of the dewatering flow rate.

Claims (1)

[Claims] 1. In a filter press, the injection pressure of the stock solution is changed from 0 pressure to a lower pressure and then to a higher pressure, and the sawtooth type dehydration pressure is cycled from 0 pressure to the maximum pressure in one cycle. A dehydration method in a filter press, which is characterized by repeatedly dehydrating a stock solution. 2 Connect a low head main pump to the water injection side of the filter press via a solenoid valve, and further connect a pressure booster pump for generating high pressure to the water injection side of the solenoid valve to repeatedly perform low pressure dehydration and high pressure dehydration in combination. A dewatering device for a filter press, which is characterized by: