KR20020065215A - Backpulsing system for fouling reduction of membrane - Google Patents

Abstract

PURPOSE: An energy saving type backpulsing system capable of giving backpulsing only by the existing membrane process without additional units using operation principle of a pump to restrain irreversible fouling of the membrane and simplify an existing complicated backpulsing system is provided. CONSTITUTION: The backpulsing generating system is characterized in that effectiveness of backpulsing is obtained only by a backpulsing pump without additional units using backpulsing method which is effective in suppressing fouling of a membrane by cutting 1/10 to 1/2 of a support made of rubber or plastics at which balls(10) inside a diaphragm pump are placed, wherein water comes into the pump or piston as force pulling up balls at the downside is being acted when a diaphragm in the pump or a piston(13) is pulled back while water in the pump or piston pushes balls(10) at the upside so that the balls go out into the outside when the diaphragm in the pump or the piston(13) is pushed forward, the piston is operated as the operation of the diaphragm pump in the steady state when water comes into the pump or piston by cutting about 1/10 to 1/2 of an O-ring(11) supporting balls(10) of the downside, thereby pulling back the diaphragm or piston while a part of water is again flown down into a space of the cut O-ring(12) supporting the balls(10) of the downside although most of water pushes up the balls(10) of the upside so that the balls go out into the outside when the diaphragm or piston is pushed forward, and the membrane directly receives backpulsing effect reducing fouling of the membrane without other additional units by installing a membrane module at the side from which water of the downside comes into.

Description

Backpulsing system for fouling reduction of membrane

The present invention relates to a reverse shock system for reducing the contamination of the membrane, and more specifically, to reduce the contamination of the membrane, which is the biggest problem in the membrane separation process by using the operation principle of the diaphragm pump is a kind of backwashing The present invention relates to a system capable of applying a high frequency reverse shock.

The biggest problem in solid-liquid separation using a membrane is that the cake layer accumulates on the surface of the membrane as the filtration time elapses, leading to a sharp decrease in the amount of permeate. In order to overcome this problem, crossflow filtration, which prevents the formation of a cake layer by causing the fluid to flow in a direction parallel to the separator, unlike dead-end filtration, which causes the fluid to flow in a direction perpendicular to the separator. Filtration has been actively studied. However, cross flow filtration requires a large capacity circulation pump to obtain a sufficient amount of permeate, which consumes a lot of energy.

The causes of the decrease in permeability of the membrane are concentration polarization phenomenon in which the permeability decreases as the osmotic pressure increases due to the increase of the concentration of solute near the membrane, and fouling in which the permeability decreases due to the adsorption or deposition of the solute on the membrane surface or inside. ) There is a phenomenon. Concentration polarization does not affect the properties of the membrane itself and depends on the hydraulic condition of the membrane surface. However, membrane fouling causes changes in the properties of the membrane as substances accumulate or adsorb on the surface of the membrane, reducing the permeability. Concentration polarization reduces the effective permeation pressure at the membrane surface, but does not permanently change the material and permeability of the membrane, but it is possible to minimize the concentration polarization by considering the hydrodynamic aspects by developing various membrane modules. This is under study. However, membrane fouling may strongly reduce the permeability of the membrane when the contaminants are strongly bound and accumulated on the surface of the membrane according to the characteristics of the influent, and also change the properties of the membrane, thereby reducing the resolution.

Membrane processes have been an alternative to separation that can be used in many industries and medical fields, and as mentioned above, they cannot be rapidly spread due to fouling of the membrane. Many studies to overcome membrane fouling have focused on the removal of the concentration polarization layer, which has been considered as a major factor in reducing the permeability (Micheal, 1968; Blatt et al., 1970; Jonsson and Tragardh, 1990). However, the decrease in the transmittance due to concentration polarization resulted in an increase in the transmittance by changing the structure of the module or increasing the cross flow rate. However, the interaction between particles and membranes (adsorption, passage sealing), the interaction between particles and particles There is almost no way to prevent irreversible membrane closure associated with the process. In order to overcome irreversible membrane closure, backflushing method was introduced, which is used to intermittently flow the membrane reversely in the membrane separation process to reduce the adsorption of particles on the membrane surface or blocking membrane pores. Michaels, 1980; Von Baeyer et. Al., 1983, 1985; Belfort et al., 1980; Fane and Fell, 1987.

The purpose of backpulsing used to reduce membrane fouling in the present invention is to prevent adsorption and membrane pores over time by applying pressure at a very high frequency in the opposite direction to the flow from the concentrate to the permeate through the membrane. It is to reduce the phenomenon to maximize the permeate amount and separation efficiency. Reverse shock is fundamentally different from backwash in that pressure is applied in units of 0.1 seconds instead of minutes. When the pressure across the membrane is reversed, additional forces due to the acceleration and inertia of the fluid are given to the particles that are adsorbed or to block the membrane pore, effectively removing the particles from the membrane surface. The back shock process also facilitates the migration of particles from the membrane surface to the bulk flow, causing membrane closure and the like, which can reduce concentration polarization and increase permeate flow. The study of reverse shock was not carried out in Korea and outside of the country, VGJ Rodgers and RE Sparks used reverse shock for the classification of proteins with different molecular weights. Permeability increased from 6 to 64 times. Sanjeev G. Redkar and Robert H. Davis used reverse shock for the separation of yeast. The optimum reverse shock time was 0.1, 0.2 and 0.3 seconds when the forward filtration time was 1.5, 3 and 5 seconds, respectively. It was about eight times as compared with no reverse shock. G. Jonsson and IG Wenten used a reverse shock in the beer refining process, and obtained a 10-permeate permeate when the reverse shock was applied for 0.1 seconds at 5 second intervals, and even in the process of concentrating 500 L to 5 L. .

However, this reverse shock method has significantly increased the permeability as reported in the above study and shows that it can be operated for a long time without chemical or physical membrane cleaning. However, the conventional reverse shock system shows the basic membrane separation as shown in FIG. Pressurized cylinder (7), counter-impact tank (7) for additional back shock to the process, timer (4) and solenoid valve (for controlling forward filtration time and reverse filtration (back shock) time) 4) such a device is required, and there is a problem that more energy is used accordingly.

In view of the above problems, the present invention uses the pumping principle to suppress irreversible contamination of the membrane and simplify the existing complicated reverse shock system. To provide an energy-saving reverse shock system.

1 is a conventional membrane reverse shock system process diagram.

Figure 2 is a membrane reverse impact system process according to the present invention.

3 and 4 show the main section and the operating principle of the present invention,

3 is a sectional view of main parts of the diaphragm pump before deformation;

4 is a sectional view of main parts of the diaphragm pump after deformation;

5 to 9 show an experimental apparatus and an experimental result using the reverse shock system of the present invention,

5 is a membrane reverse shock system experimental apparatus for demonstrating the efficiency of the present invention

Figure 6 is a view showing the pressure change of the membrane module using a deformed diaphragm pump.

7 is a view showing the pressure change of the membrane module using a diaphragm pump after deformation.

8 is a view showing a change in transmittance with time.

9 is a view showing the change in transmittance according to the reverse shock frequency

Explanation of symbols on the main parts of the drawings

1: inlet tank 2: pressure pump 3: membrane module 4: timer

5: solenoid valve 6: counter impact tank 7: pressurized cylinder

8: Permeate tank 9: Reverse shock pump 10: Ball 11: Normal O-ring

12: cutting O-ring 13: piston 14: pressure transducer 15: computer

The process diagram of the membrane reverse shock system using the present invention is shown in FIG. 2, but only the pump was replaced with the reverse shock pump 9 in the same process as the conventional membrane separation process.

Figure 3 illustrates the principle of operation of the piston diaphragm pump is pulled back by the action of the diaphragm or the piston 13 in the pump when the force to pull up the lower ball 10 is applied to open the water to enter, forward When pushed in, the water that came in will push out the upper ball (10) to go out. However, if the O-ring supporting the lower ball 10 is cut about 1/10 to 1/2, as shown in FIG. When pushed, most of the water pushes the upper ball 10 out, but a portion of the water is lowered back into the cut space of the O-ring 12 supporting the lower ball 10. At this time, if the membrane module (3) is installed on the side of the water coming in, as described above, it is possible to directly transmit the effect of the reverse shock to reduce the fouling phenomenon of the membrane without any additional device.

The membrane separation process according to the present invention is to demonstrate the efficiency through the following experiments to effectively apply to all water treatment.

<Example>

As in Figure 5, the process according to the membrane reverse shock system of the present invention was experimented with 10,000 ppm of the solution.

Experimental conditions;

The solution used in the experiment was a latex solution with a high concentration of 10,000 ppm, and the experiment was performed by immersing a polyacrylonitile hollow fiber membrane directly in the solution and measuring the instantaneous pressure when a reverse shock occurred. In order to receive the data from the pressure transducer 14 directly to the computer 15 to prepare a graph.

Experiment result;

6 and 7 are diagrams illustrating when the reverse shock system according to the present invention is not applied and when the reverse shock system is applied, respectively, in which a peak portion of the graph flows in through the separator and flows out by the reverse shock. It can be seen that the peak is almost flat when the reverse shock system is not applied (FIG. 6) while the peak is substantially high when the reverse shock is applied (FIG. 7).

FIG. 8 shows the change in transmittance ratio (J / Jo) with time when the piston 13 cycle of the diaphragm pump is 2 Hz and when the reverse shock system is applied. Where Jo is the pure transmittance and J is the transmittance at each time. It can be seen that the contamination rate of the separator is less than that of the case where the reverse impact system is not applied, which is about 60% higher after 7200 seconds.

9 is a diagram comparing the application of the reverse shock system with and without the piston 13 cycle of the diaphragm pump from 0.67 to 2 Hz. As shown in the graph, it can be seen that the higher the period of the piston, the greater the difference between the effect of the reverse shock and the effect of no.

Thus, according to the present invention, the effect of the reverse shock system which modified the diaphragm pump without any other additional device was confirmed.

The present invention can use the operating principle of a diaphragm pump, an air diaphragm pump, a piston pump, etc. to impart a reverse shock to the separator without additional devices. This overall device is shown in FIG. 2, but can have the same effect as the conventional anti-shock device (FIG. 1) without additional devices. When the reverse shock is applied using the conventional complex reverse shock system, the pump must be stopped during the reverse shock time to stop the suction of the permeate passing through the membrane, but the permeation system of the present invention enables continuous permeation. This ensures more permeate volume during the same time and significantly reduces energy consumption since no additional power source is required.

Claims (1)

A method of reverse shock effective for suppressing contamination of the membrane by cutting the rubber or plastic bearing from which the ball 10 inside the diaphragm pump is located from 1/10 to 1/2 is performed by using only the reverse shock pump 9 without additional equipment. System to generate the impact of the impact