A sludge plate and frame filter press system based on wastewater recycling and its application method

Abstract

This invention discloses a sludge plate and frame filter press system and its usage method based on wastewater recycling, comprising: a sludge unloading silo; a sludge storage silo; a conditioning tank; a plate and frame filter press; a dry sludge storage silo; a three-waste co-firing furnace; a dust collector; a desulfurization tower; an ash silo; an evaporation tower; and a secondary dust collector. The sludge unloading silo, sludge storage silo, conditioning tank, plate and frame filter press, dry sludge storage silo, three-waste co-firing furnace, dust collector, and desulfurization tower are sequentially connected. The conditioning tank is connected to the desulfurization tower, the dust collector is connected to the ash silo, and the plate and frame filter press, ash silo, and secondary dust collector are respectively connected to the evaporation tower. This invention achieves the application of plate and frame filter press technology in the field of three-waste co-firing furnace by comprehensively utilizing desulfurization wastewater and recycling filter press wastewater. It solves the problem of large dilution water consumption when applying plate and frame filter press technology in the field of three-waste co-firing furnace. It also utilizes the high temperature and large ash content of the co-firing furnace to evaporate the filter press wastewater, thus realizing the efficient and low-cost utilization of sludge and the recycling and zero discharge of wastewater.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a sludge plate and frame filter press system based on wastewater recycling and its usage method. Background Technology

[0002] The three-waste co-combustion furnace (third-generation gasification blast gas recovery device) is a device that mixes blast gas, gasification slag, and fine ash from the gasification dust collector generated during the gasification process with some coal gangue, bituminous coal, sludge, and anthracite powder, and then performs fluidized combustion within the furnace to generate high-temperature flue gas for centralized heat recovery. Because the fuel burned has a low calorific value and a high ash content, the amount of fly ash produced is enormous, and the fly ash temperature is high, generally around 1000℃, indicating significant heat potential. Therefore, it should still have some utilization value, but currently no measures have been taken to recover and utilize the fly ash.

[0003] Meanwhile, due to its unique structure, the three waste co-firing furnace can incinerate sludge with a moisture content of about 50%. However, most of the sludge from sewage treatment plants is wet sludge with a high moisture content, which needs to be pre-treated before it can be burned in the three waste co-firing furnace. However, the current sludge pre-treatment process has the problems of complex system and high cost. Summary of the Invention

[0004] To address the technical problems existing in the prior art, the purpose of this invention is to provide a sludge plate and frame filter press system based on wastewater recycling and its usage method.

[0005] To achieve the above objectives and technical effects, the technical solution adopted by this invention is as follows:

[0006] A sludge plate and frame filter press system based on wastewater recycling includes:

[0007] sludge unloading silo;

[0008] sludge storage silos;

[0009] Conditioning pool;

[0010] Plate and frame filter press;

[0011] Dry sludge storage silo;

[0012] Three-waste co-firing furnace;

[0013] dust collector;

[0014] Desulfurization tower;

[0015] Gray warehouse;

[0016] Evaporation tower;

[0017] Secondary dust collector;

[0018] The sludge unloading silo, sludge storage silo, conditioning tank, plate and frame filter press, dry sludge storage silo, three wastes co-firing furnace, dust collector, and desulfurization tower are connected in sequence. The conditioning tank is connected to the desulfurization tower, the dust collector is connected to the ash silo, and the plate and frame filter press, ash silo, and secondary dust collector are respectively connected to the evaporation tower.

[0019] Furthermore, sludge conveying pumps are respectively installed below the sludge unloading silo, sludge storage silo, and dry sludge storage silo.

[0020] Furthermore, the conditioning tank and the plate and frame filter press are respectively connected to the buffer water tank. A valve L1 and a water quality detection device are installed between the plate and frame filter press and the buffer water tank. The buffer water tank is connected to the desulfurization tower and a valve L2 is installed between the two.

[0021] Furthermore, the evaporation tower can be connected to the plate and frame filter press via valve L5, the main valve and valve L3. The evaporation tower can also be connected to the plate and frame filter press via valve L6, the emergency slurry tank, valve L4, the main valve and valve L3. Valve L5 and the emergency slurry tank are arranged in parallel between the main valve and the evaporation tower.

[0022] Furthermore, the ash silo is connected to a blower.

[0023] Furthermore, the secondary dust collector is connected to the induced draft fan.

[0024] This invention also discloses a method for using a sludge plate and frame filter press system based on wastewater recycling, comprising the following steps:

[0025] Wet sludge is dumped into a sludge unloading bin, then transported to a sludge storage bin, and then conveyed to a conditioning tank. In the conditioning tank, the wet sludge is diluted to a slurry with a moisture content of 95-97%, and then enters a plate and frame filter press to be filtered into dry sludge with a moisture content of 50%-60%. At the same time, a large amount of filter press wastewater is generated. The water quality of the filter press wastewater is tested by a water quality testing device, and the decision on whether to reuse the filter press wastewater is made based on the test results.

[0026] After the dry sludge exits the plate and frame filter press, it falls into the dry sludge storage silo and is then transported to the three-waste co-combustion furnace for combustion. The flue gas after combustion enters the dust collector for dust removal and is then collected and falls into the ash silo. The flue gas continues to enter the desulfurization tower for desulfurization treatment. The blower sends air into the ash silo, and the high-temperature ash is transported to the evaporation tower by pneumatic conveying. The evaporation tower contains filter press wastewater drawn from the plate and frame filter press. The filter press wastewater and high-temperature ash undergo indirect heat exchange in the evaporation tower. The water is heated into steam, and the salt in the filter press wastewater crystallizes due to water evaporation. Some of the salt and ash accumulate at the bottom of the evaporation tower and are collected. Some of the salt, ash, water vapor, and flue gas are drawn out by the exhaust fan at the tail end. During the drawing process, they are captured again in the secondary dust collector to avoid environmental pollution.

[0027] Furthermore, when the wastewater from the filter press is of qualified quality and meets the requirements, the control valve L1 is opened to introduce the wastewater from the plate and frame filter press into the buffer tank, and then transport it to the conditioning tank as dilution water.

[0028] Furthermore, when the quality of the filter press wastewater is unqualified or does not meet the requirements, control valve L1 is closed and control valve L3 is opened, and the filter press wastewater is directly discharged from the plate and frame filter press. At this time, control valve L2 needs to be opened to introduce desulfurization wastewater from the desulfurization tower into the buffer tank, and then transport it to the conditioning tank as dilution water. After the filter press wastewater is directly discharged from the plate and frame filter press, the flow direction of the filter press wastewater is determined according to whether the evaporation tower has sufficient water.

[0029] Furthermore, if the water volume in the evaporation tower is insufficient, control valve L3, main valve, and valve L5 will be opened, and the filter press wastewater will reach the evaporation tower in sequence through valve L3, main valve, and valve L5.

[0030] If there is sufficient water in the evaporator, control valve L3, main valve, and valve L4 are opened. The filter press wastewater passes through valve L3, main valve, and valve L4 in sequence to reach the emergency slurry tank and is temporarily stored in the emergency slurry tank. At this time, when the evaporator needs to be replenished with water, control valve L6 is opened directly to send the filter press wastewater in the emergency slurry tank to the evaporator.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] This invention discloses a sludge plate and frame filter press system and its usage method based on wastewater recycling, comprising: a sludge unloading silo; a sludge storage silo; a conditioning tank; a plate and frame filter press; a dry sludge storage silo; a three-waste co-firing furnace; a dust collector; a desulfurization tower; an ash silo; an evaporation tower; and a secondary dust collector. The sludge unloading silo, sludge storage silo, conditioning tank, plate and frame filter press, dry sludge storage silo, three-waste co-firing furnace, dust collector, and desulfurization tower are sequentially connected. The conditioning tank is connected to the desulfurization tower, the dust collector is connected to the ash silo, and the plate and frame filter press, ash silo, and secondary dust collector are respectively connected to the evaporation tower. The sludge plate and frame filter press system and its usage method based on wastewater recycling provided by this invention realizes the application of plate and frame filter press technology in the field of three-waste co-firing furnace through comprehensive utilization of desulfurization wastewater and recycling of filter press wastewater. It solves the problem of large dilution water consumption when the plate and frame filter press technology is applied in the field of three-waste co-firing furnace, and takes advantage of the high temperature and large ash content of the co-firing furnace to evaporate the filter press wastewater, achieving zero wastewater discharge, reducing wastewater treatment costs, and realizing efficient and low-cost utilization of sludge and recycling and zero discharge of wastewater. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the present invention;

[0034] Figure 2This is a flowchart of the present invention;

[0035] The components include: 1. Sludge unloading silo; 2. Sludge conveying pump; 3. Sludge storage silo; 4. Conditioning tank; 5. Plate and frame filter press; 6. Dry sludge storage silo; 7. Three wastes co-combustion furnace; 8. Dust collector; 9. Desulfurization tower; 10. Ash silo; 11. Evaporation tower; 12. Secondary dust collector; 13. Exhaust fan; 14. Emergency slurry tank; 15. Main valve; 16. Buffer water tank; 17. Blower; 18. Water quality testing device. Detailed Implementation

[0036] The present invention will now be described in detail so that its advantages and features can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0037] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0038] Plate and frame filter presses are a low-cost method for sludge drying. The principle involves filling the filter plates with sludge containing 95% moisture. A feed pump uses pressure to squeeze the water out of the filter plates, and the sludge is then filtered through a filter cloth, ultimately achieving dewatering. After feeding, a press pump injects high-pressure water into the diaphragm plates of the filter press, using diaphragm tension to forcefully squeeze and dewater the sludge. The filtrate passes through the filter cloth and is discharged, while solids are trapped by the filter cloth, forming dry matter with low moisture content. Currently, its automation level has significantly improved, and the moisture content of the sludge cake is gradually reaching 50%–60%. However, directly applying plate and frame filter presses to sludge dewatering in waste gas co-firing furnaces presents several problems:

[0039] (1) The moisture content of the sludge entering the plant is usually 80%, which needs to be diluted first to reach a moisture content of more than 95%. This requires a large amount of dilution water. For example, 100t / d of sludge with a moisture content of 80% needs to be diluted to 95% moisture content, which requires 300t of dilution water. The final sludge volume is 400t / d, which puts high demands on the water supply system of the three wastes co-fired furnace.

[0040] (2) The moisture content of sludge after filtration usually needs to reach 50% to 60% so that it will not cause system blockage when entering the pulverizing system. Based on a volume of 400t / d, 160t / d to 200t / d of waste liquid is generated. The wastewater generated from sludge drying has relatively higher COD, ammonia nitrogen, and SS than domestic sewage. Direct entry into the domestic sewage system may cause shock and affect the compliance of the domestic sewage treatment system. Therefore, it is necessary to add sewage treatment equipment.

[0041] Obviously, the plate and frame filter press process for treating sludge requires a large amount of dilution water and generates a large amount of wastewater after filtration, which limits its application in the field of sludge drying in co-fired furnaces.

[0042] To address the aforementioned problems, this invention, after extensive research, proposes a sludge plate and frame filter press system and its application method based on wastewater recycling, such as... Figure 1-2 As shown, the sludge plate and frame filter press system based on wastewater recycling includes:

[0043] A sludge unloading silo 1 is provided with a sludge conveying pump 2 below it;

[0044] A sludge storage silo 3 is provided with a sludge transfer pump 2 below it;

[0045] Conditioning pool 4;

[0046] Plate and frame filter press 5;

[0047] A dry sludge storage silo 6 is provided with a sludge transfer pump 2 below it;

[0048] 7. Waste co-firing furnace;

[0049] Dust collector 8;

[0050] Desulfurization tower 9;

[0051] Ash silo 10 is connected to dust collector 8 and blower 17;

[0052] Evaporation tower 11 is connected to ash silo 10;

[0053] The secondary dust collector 12 is connected at both ends to the evaporation tower 11 and the induced draft fan 13, respectively.

[0054] An emergency slurry tank 14 is installed in parallel with valve L5 between the main valve 15 and the evaporation tower 11. Valves L4 and L6 are connected to both ends of the emergency slurry tank 14, respectively. One end of the emergency slurry tank 14 is connected to the plate and frame filter press 5 through valve L4, main valve 15 and valve L3, and the other end of the emergency slurry tank 14 is connected to the evaporation tower 11 through valve L6. The evaporation tower 11 can also be connected to the plate and frame filter press 5 through valve L5, main valve 15 and valve L3.

[0055] Buffer water tank 16;

[0056] Water quality testing device 18;

[0057] The sludge unloading silo 1, sludge storage silo 3, conditioning tank 4, plate and frame filter press 5, dry sludge storage silo 6, three wastes co-firing furnace 7, dust collector 8, and desulfurization tower 9 are connected in sequence. The conditioning tank 4 is also connected to the buffer water tank 16. The buffer water tank 16 is connected to the desulfurization tower 9 and a valve L2 is installed between the two. The plate and frame filter press 5 is also connected to the buffer water tank 16 and a valve L1 and a water quality testing device 18 are installed between the two.

[0058] A method for using a sludge plate and frame filter press system based on wastewater recycling includes the following steps:

[0059] After being transported to the plant by vehicle, the wet sludge is dumped into the sludge unloading silo 1. Then, it is transported by the sludge transfer pump 2 located below the sludge unloading silo 1 to the sludge storage silo 3 for storage. The wet sludge is then transported by the sludge transfer pump 2 located below the sludge storage silo 3 to the conditioning tank 4. In the conditioning tank 4, the wet sludge is diluted to a slurry with a moisture content of 95-97%. It then enters the plate and frame filter press 5 to be pressed into dry sludge with a moisture content of 50-60%, generating a large amount of filter press wastewater. Obviously, this sludge conditioning process in the conditioning tank 4 requires a large amount of water. Therefore, this invention introduces two water sources: one is the filter press wastewater introduced from the plate and frame filter press 5 as dilution water, and the other is a desulfurization wastewater pipeline introduced from the desulfurization tower 9 to the buffer tank 16, with the filter press wastewater being the preferred source. However, since the filter press wastewater contains a large number of impurity ions from the sludge, repeated recycling will cause the sludge to become unusable for filter pressing. Therefore, this invention introduces a water quality testing device 18. After the filter press wastewater flows out of the plate and frame filter press 5, the water quality testing device 18 tests the water quality to determine if it meets the requirements. When the filter press wastewater is qualified and meets the requirements, the control valve L1 opens, and the filter press wastewater reaches the buffer tank 16. When the filter press wastewater is unqualified and does not meet the requirements, the control valve L1 closes, the control valve L3 opens, and the filter press wastewater is directly discharged. At this time, the control valve L2 opens, controlling the discharge from the desulfurization tower 9. The desulfurization wastewater enters the buffer tank 16 and then flows into the conditioning tank 4 to dilute the sludge. When the quality of the filter press wastewater cannot meet the conditioning requirements, it is discharged. The evaporator 11 is judged based on whether there is enough water. If the result is no, the filter press wastewater passes through valve L3 and main valve 15, and then through valve L5 to reach the evaporator 11. If the result is yes, that is, the evaporator 11 does not need so much wastewater, the filter press wastewater passes through valve L3 and main valve 15, and then through valve L4 to reach the emergency slurry tank 14, where it is temporarily stored. When the evaporator 11 needs wastewater, the control valve L6 is opened, and the filter press wastewater reaches the evaporator 11.

[0060] After exiting the plate and frame filter press 5, the dried sludge falls into the dry sludge storage silo 6. Then, it is transported by the sludge conveying pump 2 and the dry sludge conveying belt located below the storage silo 6 to the waste gas co-firing furnace 7 for combustion. The sludge combustion in the furnace 7 produces a large amount of high-temperature ash, which enters the dust collector 8 and is collected before falling into the ash silo 10. The flue gas continues forward to the desulfurization tower 9, where it reacts with the limestone slurry. If the reacted flue gas meets the standards, it can be discharged. The reacted limestone slurry becomes desulfurization wastewater, which can be transported to the buffer tank 16 for recycling. Air is delivered to the ash silo 10 via a duct by a blower 17, and the high-temperature ash is conveyed to the evaporation tower 11 by pneumatic conveying. The evaporation tower 11 has a filter press wastewater sourced from the plate and frame filter press 5. The filter press wastewater and the high-temperature ash achieve indirect heat exchange in the evaporation tower 11. The water is heated to a steam state, and the salt in the wastewater crystallizes due to the evaporation of water. Some of the salt and ash are enriched at the bottom of the evaporation tower 11 and collected. Some of the salt, ash, water vapor, and flue gas are drawn out by the exhaust fan 13 at the tail end. During the drawing process, they are captured again in the secondary dust collector 12 to avoid environmental pollution.

[0061] Any parts or structures not specifically described in this invention can be made using existing technologies or products, and will not be elaborated upon here.

[0062] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A sludge plate and frame filter press system based on wastewater recycling, characterized in that, include: Sludge unloading silo; sludge storage silos; Conditioning pool; Plate and frame filter press; Dry sludge storage silo; Three-waste co-firing furnace; dust collector; Desulfurization tower; Gray warehouse; Evaporation tower; Secondary dust collector; The sludge unloading silo, sludge storage silo, conditioning tank, plate and frame filter press, dry sludge storage silo, three wastes co-firing furnace, dust collector, and desulfurization tower are connected in sequence. The conditioning tank is connected to the desulfurization tower, the dust collector is connected to the ash silo, and the plate and frame filter press, ash silo, and secondary dust collector are respectively connected to the evaporation tower. The conditioning tank and the plate and frame filter press are respectively connected to the buffer water tank. A valve L1 and a water quality detection device are installed between the plate and frame filter press and the buffer water tank. The buffer water tank is connected to the desulfurization tower and a valve L2 is installed between the two. The evaporation tower can be connected to the plate and frame filter press through valve L5, main valve and valve L3. The evaporation tower can also be connected to the plate and frame filter press through valve L6, emergency slurry tank, valve L4, main valve and valve L3. Valve L5 and emergency slurry tank are arranged in parallel between the main valve and the evaporation tower. The ash silo is connected to the blower; The secondary dust collector is connected to the induced draft fan.

2. The sludge plate and frame filter press system based on wastewater recycling according to claim 1, characterized in that, Sludge conveying pumps are respectively installed below the sludge unloading silo, sludge storage silo, and dry sludge storage silo.

3. A method of using the sludge plate and frame filter press system based on wastewater recycling as described in claim 1, characterized in that, Includes the following steps: Wet sludge is dumped into a sludge unloading bin, then transported to a sludge storage bin, and then to a conditioning tank. In the conditioning tank, the wet sludge is diluted to a slurry with a moisture content of 95-97%, and then enters a plate and frame filter press to be filtered into dry sludge with a moisture content of 50-60%. At the same time, a large amount of filter press wastewater is generated. The water quality of the filter press wastewater is tested by a water quality testing device, and the decision on whether to reuse the filter press wastewater is made based on the test results. After the dry sludge exits the plate and frame filter press, it falls into the dry sludge storage silo and is then transported to the three-waste co-combustion furnace for combustion. The flue gas after combustion enters the dust collector for dust removal and is then collected and falls into the ash silo. The flue gas continues to enter the desulfurization tower for desulfurization treatment. The blower sends air into the ash silo, and the high-temperature ash is transported to the evaporation tower by pneumatic conveying. The evaporation tower contains filter press wastewater drawn from the plate and frame filter press. The filter press wastewater and high-temperature ash undergo indirect heat exchange in the evaporation tower. The water is heated into steam, and the salt in the filter press wastewater crystallizes due to water evaporation. Some of the salt and ash accumulate at the bottom of the evaporation tower and are collected. Some of the salt, ash, water vapor, and flue gas are drawn out by the exhaust fan at the tail end. During the drawing process, they are captured again in the secondary dust collector to avoid environmental pollution.

4. The method of using a sludge plate and frame filter press system based on wastewater recycling according to claim 3, characterized in that, When the wastewater from the filter press is of qualified quality and meets the requirements, the control valve L1 is opened, and the wastewater from the plate and frame filter press is introduced into the buffer tank and then transported to the conditioning tank as dilution water.

5. The method of using a sludge plate and frame filter press system based on wastewater recycling according to claim 3, characterized in that, When the quality of the filter press wastewater is unqualified or does not meet the requirements, control valve L1 is closed and control valve L3 is opened, and the filter press wastewater is discharged directly from the plate and frame filter press. At this time, control valve L2 needs to be opened to introduce desulfurization wastewater from the desulfurization tower into the buffer tank, and then transport it to the conditioning tank as dilution water. After the filter press wastewater is discharged directly from the plate and frame filter press, the flow direction of the filter press wastewater is determined according to whether the evaporation tower has sufficient water.

6. The method of using a sludge plate and frame filter press system based on wastewater recycling according to claim 5, characterized in that, If the water volume in the evaporator is insufficient, control valve L3, main valve, and valve L5 will be opened, and the filter press wastewater will reach the evaporator in sequence through valve L3, main valve, and valve L5. If there is sufficient water in the evaporator, control valve L3, main valve, and valve L4 are opened. The filter press wastewater passes through valve L3, main valve, and valve L4 in sequence to reach the emergency slurry tank and is temporarily stored in the emergency slurry tank. At this time, when the evaporator needs to be replenished with water, control valve L6 is opened directly to send the filter press wastewater in the emergency slurry tank to the evaporator.

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