A double fixed-bed media filter

Abstract

A dual fixed-bed media filter of the present invention comprises a tank body, a lower water distributor, an intermediate water distributor, an upper water distributor, a filter media layer, a water inlet pipe, a lower water distributor inlet valve, an upper water distributor inlet valve, an upper water distributor outlet valve, a sewage discharge pipe, an intermediate water distributor sewage discharge outlet valve, an outlet valve, a bottom sewage discharge valve, a bottom sewage discharge pipe and a control system. The present invention adopts an upper and lower dual fixed-bed structure and an excellent inverse particle size filtration method. Compared with existing products, it has the characteristics of a large periodic water production capacity which is 2-5 times that of existing products, high filtration accuracy, a low flushing waste water volume of 2%, and being suitable for a high influent turbidity of 500 NTU, etc. It is an upgraded product of existing media filters.

Description

[0001] The present invention belongs to the field of solid-liquid separation, specifically to the field of chemical and water treatment filtration equipment, and relates to a double fixed-bed media filter, which is widely used to solve the problems of low filtration accuracy, unsuitability for high-turbidity water quality, short water production cycle, and large amount of backwash wastewater of existing media filters. Background Art

[0002] Fixed-bed media filters are currently widely used in industries such as petroleum, chemical, energy, and water treatment. Most existing fixed-bed media filters adopt a downward flow working mode, that is, the liquid to be filtered passes through the fixed filter bed from top to bottom; during backwashing, the backwash water passes through the filter bed from bottom to top. Due to the hydraulic classification effect during backwashing, the filter media particles in the filter media layer are distributed from top to bottom in terms of diameter as follows: from fine to coarse, with the smallest filter media particle diameter on the surface of the filter bed and the largest filter media particle diameter at the bottom of the filter bed. This working mode is the most unreasonable in media filters. Due to this arrangement structure and operation mode of the filter media in the filter bed, only the filter media accounting for 20% to 30% of the entire filter media layer near the top of the filter media layer is functioning, and the rest of the filter media layer does not play a role. The dirt-holding capacity of the filter media layer is low, resulting in a series of operation problems of existing fixed-bed media filters, such as low filtration accuracy, unsuitability for high-turbidity water quality, short water production cycle, frequent shutdown for backwashing, and generation of a large amount of backwash wastewater. Developing a new type of filter to replace the traditional filtration system can improve the filtration accuracy and efficiency of the filter, effectively extend the operation cycle of the filter, reduce the amount of filter media cleaning water, and lower the operation cost, which has great economic benefits. Summary of the Invention

[0003] The technical problem to be solved by the present invention is the low water production per cycle, low filtration accuracy, limited influent turbidity, and large amount of backwash wastewater in the prior art; a double fixed-bed media filter is provided, and this filtration system has high filtration accuracy, is suitable for high-turbidity water quality, has less backwash wastewater, increases the water production per cycle, and maintains stable filtration effect.

[0004] To achieve the above objectives, the technical solution of the present invention is realized as follows

[0005] A dual fixed-bed media filter, comprising a tank body 1, a lower water distributor 2, an intermediate water distributor 3, an upper water distributor 4, a filter media layer 5, a water inlet pipe 6, a lower water distributor inlet valve 7, an upper water distributor inlet valve 8, an upper water distributor outlet valve 9, a sewage discharge pipe 10, an intermediate water distributor sewage discharge valve 11, a water outlet valve 12, a bottom sewage valve 13, a bottom sewage pipe 14 and a control system; characterized in that: there is a lower water distributor 2 in the lower part of the tank body 1, and the lower water distributor 2 is connected to the water inlet pipe 6 through the inlet valve 7; the intermediate water distributor 3 is located in the filter media layer 5 in the middle of the tank body 1, and the filter media layer between it and the lower water distributor 2 is the lower fixed bed, and the thickness of the filter media layer is not less than 800 times the average particle size of the filter media particles between the two water distributors. The filter media layer between the intermediate water distributor 3 and the upper water distributor 4 is the upper fixed bed, and the thickness of the filter media layer is not less than 800 times the average particle size of the filter media particles between the two water distributors. The outlet of the intermediate water distributor 3 is respectively connected to the water outlet valve 12 and the intermediate water distributor sewage discharge valve 11; the filter media layer 5 is located in the middle of the tank body 1, the specific gravity of the filter media is greater than 1, and the distance between its top and the upper water distributor 4 is 30%-50% of the height of the entire filter media layer; the upper water distributor 4 is located at the top of the tank body 1, its water inlet is connected to the water inlet pipe 6 through the upper water distributor inlet valve 8, and the water outlet is connected to the sewage discharge pipe 10 through the upper water distributor outlet valve 9. The bottom sewage valve 13 is connected to the tank body 1 through the bottom sewage pipe 14.

[0006] The described dual fixed-bed media filter is characterized by the dual-bed structure of the fixed filter layer. One is inside the tank body 1, forming a lower fixed filter bed composed of the lower water distributor 2, the intermediate water distributor 3 and a single-media filter media layer between the two water distributors. The other is an upper fixed filter bed that can be composed of a single medium or a multi-media filter media layer between the intermediate water distributor 3 and the upper water distributor 4.

[0007] The described dual fixed-bed media filter is characterized in that: during operation, the lower fixed bed is in an up-flow reverse particle size filtration mode; when the upper fixed bed uses multi-media filter media, it is in a down-flow reverse particle size filtration mode, and when it uses a single-media filter media, it is in a down-flow ordinary filtration mode.

[0008] The described dual fixed-bed media filter is characterized in that: during filtration, the upper fixed bed and the lower fixed bed can work independently or simultaneously.

[0009] The described dual fixed-bed media filter is characterized in that when cleaning the filter media of the upper and lower fixed beds, the cleaning liquid can either pass through the filter media layer from top to bottom or from bottom to top.

[0010] The described dual fixed-bed media filter is characterized in that the filter media of the lower fixed bed is a single medium with a density greater than 1, and the filter media of the upper fixed bed is two or more media with densities greater than 1, and the density of the upper medium is lower than that of the lower medium.

[0011] Advantages of the present invention: It can ensure a long filtration cycle, high filtration accuracy, suitability for high-turbidity water quality, less flushing wastewater, and significant economic benefits. Brief Description of the Drawings

[0012] Figure 1 It is a schematic diagram of the overall structure of the double fixed-bed media filter.

[0013] A double fixed-bed media filter, as Figure 1 shown, includes a tank body 1, a lower water distributor 2, an intermediate water distributor 3, an upper water distributor 4, a filter media layer 5, a water inlet pipe 6, a lower water distributor inlet valve 7, an upper water distributor inlet valve 8, an upper water distributor outlet valve 9, a sewage discharge pipe 10, an intermediate water distributor sewage discharge outlet valve 11, an outlet valve 12, a bottom sewage valve 13, a bottom sewage pipe 14 and a control system.

[0014] Filtration process: The liquid to be filtered is divided into two paths by the water inlet pipe 6. One path enters the lower water distributor 2 through the lower water distributor inlet valve 7, passes through the lower fixed-bed filter media layer 5 and the intermediate water distributor 3, and then flows out of the tank body 1. The other path enters the upper water distributor 4 through the upper water distributor inlet valve 8, passes through the upper fixed-bed filter media layer 5 and the intermediate water distributor 3, and then flows out of the tank body 1. In this way, the filtration and purification of the liquid are completed.

[0015] Filter media expansion cleaning process: The cleaning water enters the lower water distributor 2 through the lower water distributor inlet valve 7 from the water inlet pipe 6. The cleaning water flows upward through the filter media layers 5 of the upper and lower fixed beds, and the filter media expands to form a fluidized state. The suspended matter in the filter media layer 5 is separated from the filter media under the action of hydrodynamic shear force and the friction of the filter media particles, and flows upward with the cleaning water. It passes through the upper water distributor 4, the upper water distributor outlet valve 9, and the sewage discharge pipe 10 and is discharged. In this way, the expansion cleaning of the filter media is completed.

[0016] Filter media non-expansion cleaning process: The cleaning water enters the upper water distributor 4 through the upper water distributor inlet valve 8 from the water inlet pipe 6. The cleaning water flows downward through the filter media layers 5 of the upper and lower fixed beds. The suspended matter in the filter media layer is separated from the filter media under the action of hydrodynamic shear force and flows downward with the cleaning water. It passes through the bottom sewage pipe 14 and the bottom sewage valve 13 and is discharged. In this way, the non-expansion cleaning of the filter media is completed. The non-expansion cleaning is generally carried out before the expansion cleaning. Specific Embodiments

[0017] The present invention will be further described below with reference to the accompanying drawings.

[0018] Example 1, the lower fixed-bed filtration process is as shown in the attached Figure 1 figure,

[0019] The lower fixed-bed filtration process is as follows: Close the sewage outlet valve 11 of the middle water distributor, the inlet valve 8 of the upper water distributor, and the outlet valve 9 of the upper water distributor. Open the inlet valve 7 of the lower water distributor. The liquid to be filtered passes through the inlet pipe 6, the inlet valve 7 of the lower water distributor, the lower water distributor 2, the filter media layer 5, then through the middle water distributor 3 and the outlet valve 12, thus completing the filtration.

[0020] Example 2. The upper fixed-bed filtration process is as shown in the appendix Figure 1 as follows.

[0021] The upper fixed-bed filtration process is as follows: Close the sewage outlet valve 11 of the middle water distributor, the inlet valve 7 of the lower water distributor, and the outlet valve 9 of the upper water distributor. Open the inlet valve 8 of the upper water distributor. The liquid to be filtered passes through the inlet pipe 6, the inlet valve 8 of the upper water distributor, the upper water distributor 4, the filter media layer 5, then through the middle water distributor 3 and the outlet valve 12, thus completing the filtration.

[0022] Example 3. The simultaneous filtration process of the upper and lower fixed-beds is as shown in the appendix Figure 1 as follows.

[0023] The simultaneous filtration process of the upper and lower fixed-beds is as follows: Close the outlet valve 9 of the upper water distributor, the sewage outlet valve 11 of the middle water distributor, and the sewage valve 13. Open the inlet valve 7 of the lower water distributor and the inlet valve 8 of the upper water distributor. The liquid to be filtered passes through the inlet pipe 6. One path passes through the inlet valve 7 of the lower water distributor, the lower water distributor 2, upward through the filter media layer 5, reaches the middle water distributor 3, and flows out through the outlet valve 12. The other path passes through the inlet valve 8 of the upper water distributor, the upper water distributor 4, downward through the filter media layer 5, then through the middle water distributor 3 and the outlet valve 12, thus completing the simultaneous filtration process of the upper and lower fixed-beds.

[0024] Example 4. The non-expansion cleaning process of the filter is as shown in the appendix Figure 1 as follows.

[0025] The non-expansion cleaning process of the filter: Close the inlet valve 7 of the lower water distributor, the outlet valve 9 of the upper water distributor, the sewage outlet valve 11 of the middle water distributor, and the outlet valve 12. Open the inlet valve 8 of the upper water distributor and the bottom sewage valve 13. The cleaning water passes through the inlet pipe 6, reaches the upper water distributor 4 through the inlet valve 8 of the upper water distributor. The cleaning water flows downward through the entire filter media layer 5. The suspended matter detaches from the filter media under the action of hydraulic shear and flows downward with the water flow, and is discharged through the bottom sewage pipe 14 and the bottom sewage valve 13, thus completing the non-expansion cleaning of the filter media.

[0026] Example 5. The expansion cleaning process of the filter is as shown in the appendix Figure 1 as follows.

[0027] Filter expansion cleaning process: Close the upper distributor inlet valve 8, outlet valve 12, and bottom drain valve 13, and open the lower distributor inlet valve 7, upper distributor outlet valve 9, and middle distributor drain outlet valve 11. The cleaning water enters from the inlet pipe 6, reaches the lower distributor 2 through the lower distributor inlet valve 7, and the cleaning water flow passes upward through the entire filter media layer 5 from bottom to top. The filter media layer expands and is in a fluidized state. Suspended solids are detached from the filter media under the action of hydrodynamic shear, friction, and collision with the filter media and flow upward with the water flow. One part is discharged through the middle distributor 3 and the middle distributor drain outlet valve, and the other part is discharged through the upper distributor 4 and the upper distributor outlet valve 9. In this way, the expansion cleaning of the filter media is completed.

[0028] Such a design can enable the filter to operate in a long cycle, improve the filtration accuracy, reduce the cleaning wastewater, greatly improve the filter efficiency and application range, and save water resources.

Claims

1. A double fixed-bed media filter, comprising a tank body, a lower water distributor, an intermediate water distributor, an upper water distributor, a filter media layer, a water inlet pipe, a lower water distributor inlet valve, an upper water distributor inlet valve, an upper water distributor outlet valve, a sewage discharge outlet pipe, an intermediate water distributor sewage discharge outlet valve, an outlet valve, a bottom sewage discharge valve, a bottom sewage discharge pipe and a control system; characterized in that: There is a lower water distributor at the lower part inside the tank body. The lower water distributor is connected to the water inlet pipe through a water inlet valve. The middle water distributor is located inside the filter media layer in the middle of the tank body. The filter media layer between it and the lower water distributor is the lower fixed bed. The thickness of the filter media layer is not less than 800 times the average particle diameter of the filter media particles between the two water distributors. The filter media layer between the middle water distributor and the upper water distributor is the upper fixed bed. The thickness of the filter media layer is not less than 800 times the average particle diameter of the filter media particles between the two water distributors. The outlets of the middle water distributor are respectively connected to the water outlet valve and the sewage outlet valve of the middle water distributor. The filter media layer is located in the middle of the tank body. The specific gravity of the filter media is greater than 1. The distance from its top to the upper water distributor is 30%-50% of the height of the entire filter media layer. The upper water distributor is located at the top of the tank body. Its water inlet is connected to the water inlet pipe through the upper water distributor water inlet valve. Its water outlet is connected to the sewage discharge pipe through the upper water distributor water outlet valve. The bottom sewage valve is connected to the tank body through the bottom sewage pipe. The double-bed structure of the fixed filter layer, one is inside the tank body, forming a lower fixed filter bed composed of a lower water distributor, a middle water distributor and a single-medium filter media layer between the two water distributors, and the other is an upper fixed filter bed that can be composed of a single-medium or multi-medium filter media layer between the middle water distributor and the upper water distributor. During operation, the lower fixed bed is in an upward-flow reverse particle size filtration mode. The upper fixed bed is in a downward-flow reverse particle size filtration mode when using multi-medium filter media and in a downward-flow ordinary filtration mode when using single-medium filter media.

2. The dual fixed-bed media filter according to claim 1, wherein: During filtration, the upper fixed bed and the lower fixed bed can work independently or simultaneously.

3. The dual fixed-bed media filter according to claim 1, characterized in that When cleaning the filter media of the upper and lower fixed beds, the cleaning liquid can pass through the filter media layer from top to bottom or from bottom to top.

4. The dual fixed-bed media filter according to claim 1, characterized in that The filter media of the lower fixed bed is a single medium with a density greater than 1. The filter media of the upper fixed bed is two or more media with densities all greater than 1, and the density of the upper medium is lower than that of the lower medium.

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