Method and device for carrying out continuous back-and-forth multi-position folding and filter pressing on sludge by using filter cloth

Abstract

The invention relates to a method and a device for filter cloth continuous back-and-forth multi-position folding and filter pressing of sludge, and the method comprises the following steps: two folding systems and continuous filter cloth are used as a group of folding units, in each group of folding units, the continuous filter cloth is folded back and forth between the two folding systems, so that the sludge is folded into a folded sludge cake, and the folded sludge cake is used as a filter press. Carrying out filter pressing on the folded mud cake through a filter pressing system to obtain a filter-pressed mud cake; wherein when the filter pressing mud cake on the filter cloth is unloaded, the sludge is synchronously distributed on the filter cloth. The method provided by the invention can realize the continuous back-and-forth folding of the filter cloth in two folding systems and the continuous sludge treatment process, and belongs to the technical field of dehydration of sludge, coal slime, food and the like.

Description

Technical Field

[0001] The invention relates to the technical field of dehydration of sludge, coal slime, food and the like, and in particular to a method and a device for filtering sludge by folding a filter cloth continuously back and forth in multiple positions. Background Art

[0002] With the rapid development of my country's economy, people's quality of life has been steadily improved, and urbanization has become more and more perfect. At present, the output of sludge is still increasing year by year. Faced with a huge amount of sludge, my country's current sludge disposal method is mainly mechanical dehydration and drying, so that the sludge reaches a deep dehydrated state before disposal. However, the limitation of mechanical dehydration is that it is difficult to reduce the sludge moisture content to below 40% in one step. The energy-based drying method consumes a lot of energy and produces environmentally unfriendly gases that need to be treated, which is a high-cost disposal method.

[0003] Among the existing mechanical dewatering methods, plate-and-frame and belt dewatering are the main methods, which are difficult to make the sludge reach a moisture content of 40%. In recent years, the dewatering method of multi-layer folding filter press has appeared in the industry. Its working characteristics are to distribute the sludge on the filter cloth, and then distribute it in the frame by the folding system, and filter the folded sludge in the frame through the hydraulic element, thereby reducing the moisture content of the sludge. There are a series of shortcomings in the implementation of this method: 1. The sludge is unevenly distributed during the cloth, and it is easy to have vacancies and collapse during the folding process; 2. The filter cloth is prone to wrinkles during the cloth stage, which requires manual correction; 3. The sludge thickness is uneven, which is easy to cause uneven pressure, thereby affecting the dewatering effect of local sludge; 4. The filter cloth is wrapped around the roller during the unloading process, and the filter cloth is pulled out from the roller during the cloth, which consumes a lot of time; 5. The filter cloth works intermittently, consuming a lot of manpower and time, making the cost high. Therefore, in the existing multi-layer folded filter press dewatering method, the phenomenon that the sludge distribution state and dewatering effect are not ideal, and automation is difficult. Summary of the invention

[0004] In view of the technical problems existing in the prior art, the purpose of the present invention is to provide a method and device for filtering sludge by continuously folding the filter cloth back and forth in multiple positions, which can realize the process of continuously folding the filter cloth back and forth in two folding systems to continuously treat the sludge.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A method for filtering sludge by folding a filter cloth in multiple positions continuously back and forth, comprising the following steps: two folding systems and a continuous filter cloth are used as a group of folding units, in each group of folding units, the continuous filter cloth is folded back and forth between the two folding systems to fold the sludge into a folded mud cake, and the folded mud cake is filtered by the filter pressing system to obtain a filter press mud cake; wherein, when the filter press mud cake on the filter cloth is unloaded, the sludge is simultaneously placed on the filter cloth.

[0007] As a preferred embodiment, in each group of folding units, a pre-pressing system and a feeding system are symmetrically distributed from the outside to the inside between the two folding systems. The feeding system is used to transport the sludge to the continuous filter cloth, and the pre-pressing system is used to pre-press the filter cloth and sludge traveling back and forth between the two folding systems.

[0008] As a preferred method, the method for pre-pressing and folding the sludge into a folded mud cake is: first feed the sludge from the feeding system to the continuous filter cloth, and convey it through the pre-pressing system for pre-pressing, and then continue to convey it to the folding system after pre-pressing, and the folding system folds the sludge to obtain a folded mud cake.

[0009] As a preferred method, the folded mud cake is subjected to filter pressing treatment to obtain a filter press mud cake by conveying the folded mud cake to a filter press frame of a filter press system, moving the filter press frame toward the filter press position, applying pressure to the folded mud cake, and obtaining a filter press mud cake.

[0010] As a preference, when the number of folding units is two or more, the number of filter press systems is two, the two or more folding units are distributed side by side, and the filter press systems are distributed on both sides of the two or more folding units, corresponding to the folding systems of the two or more folding units; wherein each filter press system has the same number of filter press positions as the folding units, and the filter press workpiece of each filter press system can move at the filter press position.

[0011] A device for filtering sludge by folding filter cloth in multiple positions continuously and reciprocally, the device is applied to a method, and comprises a feeding system, a pre-pressing system, a folding system, a filter pressing system and a discharging system;

[0012] Among them, a discharge system, a feed system, a pre-pressing system and a folding system are connected in sequence to form a sludge pre-treatment system;

[0013] The number of sludge pre-treatment systems shall be at least two;

[0014] Every two sludge pre-treatment systems are symmetrically distributed to form a folding unit;

[0015] The number of the filter pressing systems is two, and the two filter pressing systems correspond to the two folding systems of the folding unit respectively.

[0016] As a preference, when the number of folding units is two or more, the filter pressing system has filter pressing positions, the number of which is the same as the number of folding units, each filter pressing position corresponds to the folding system of the folding unit, and the filter pressing workpiece of the filter pressing system can move between the filter pressing position and the position to be filtered.

[0017] As a preference, the distance between the upper pressing component and the lower pressing component of the pre-pressing system is adjustable.

[0018] As a preferred embodiment, when the sludge moves from one folding system of the folding unit to another folding system, the sludge in the filter cloth falls off after passing through the unloading system. The filter cloth after unloading is spread through the feeding system downstream of the unloading system, and enters the pre-pressing system and the folding system after carrying the sludge.

[0019] As a preferred embodiment, the pre-pressing system is used as a pre-treatment device for the sludge, which performs low-pressure treatment on the sludge so that the sludge is evenly distributed between the two layers of filter cloth.

[0020] In general, the present invention has the following advantages:

[0021] The method and device for continuous reciprocating multi-position folding of filter cloth for sludge filtering of the present invention can realize continuous reciprocating folding of filter cloth in two folding systems, achieve the state of unloading and cloth spreading at the same time, continuously process the sludge, shorten the time required for multiple folding and filtration of sludge, and improve the dehydrated dryness and output of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the front view of the device in specific application example 1.

[0023] Figure 2 It is a top view of the device in specific application example 1.

[0024] Figure 3 It is a left view of the device in specific application example 1.

[0025] Figure 4 It is a front view of the device in the specific application example 1, which illustrates the positional relationship of the movement of the filter press frame of the filter press system.

[0026] Figure 5 for Figure 4 A top view of the illustrated device.

[0027] Figure 6 It is a top view of the device in specific application example three.

[0028] Among them, 1 is the filter press system, 11 is the filter press frame, 12 is the filter press position, 2 is the folding system, 3 is the pre-pressing system, 4 is the feeding system, 5 is the cleaning system, 6 is the unloading system, and 7 is the filter cloth. DETAILED DESCRIPTION

[0029] The present invention will be further described in detail below in conjunction with specific implementation methods.

[0030] Embodiment 1;

[0031] The present embodiment provides a method for filtering sludge by continuously folding a filter cloth back and forth in multiple positions, comprising the following steps: two folding systems 2 and a continuous filter cloth 7 are used as a group of folding units, in each group of folding units, the continuous filter cloth 7 is folded back and forth between the two folding systems 2 to fold the sludge into a folded mud cake, and the folded mud cake is filtered by the filter pressing system 1 to obtain a filter press mud cake; wherein, when the filter press mud cake on the filter cloth 7 is unloaded, the sludge is simultaneously laid on the filter cloth 7.

[0032] In each group of folding units, a pre-pressing system 3 and a feeding system 4 are symmetrically distributed between the two folding systems 2 from the outside to the inside. The feeding system 4 is used to transport the sludge to the continuous filter cloth 7, and the pre-pressing system 3 is used to pre-press the filter cloth 7 and the sludge traveling back and forth between the two folding systems 2.

[0033] The method for pre-pressing and folding the sludge into a folded mud cake is as follows: first, the sludge is fed from the feeding system 4 to the continuous filter cloth 7, and is transported through the pre-pressing system 3 for pre-pressing, and then is continuously transported to the folding system 2 after pre-pressing, and the folding system 2 folds the sludge to obtain a folded mud cake.

[0034] The method for obtaining a filter press mud cake by filter pressing the folded mud cake is as follows: the folded mud cake is transported to the filter press frame 11 of the filter press system 1, the filter press frame 11 moves toward the filter press position 12, and pressure is applied to the folded mud cake to obtain a filter press mud cake.

[0035] When the number of folding units is two or more, the number of filter press systems 1 is two, the two or more folding units are distributed side by side, and the filter press systems 1 are distributed on both sides of the two or more folding units, corresponding to the folding systems 2 of the two or more folding units; wherein each filter press system 1 has the same number of filter press positions 12 as the folding units, and the filter press workpiece of each filter press system 1 can move at the filter press position 12.

[0036] By treating the sludge with the method provided in this embodiment, the filter cloth 7 can be continuously folded back and forth in the two folding systems 2 to continuously treat the sludge.

[0037] Embodiment 2:

[0038] like Figure 1-Figure 5 As shown, the present embodiment provides a device for filtering sludge by folding filter cloth in multiple positions continuously back and forth, and the device is applied to the method, comprising a feeding system 4, a pre-pressing system 3, a folding system 2, a filter pressing system 1 and a discharge system 6;

[0039] Among them, a discharge system 6, a feed system 4, a pre-pressing system 3 and a folding system 2 are connected in sequence to form a sludge pre-treatment system;

[0040] The number of sludge pre-treatment systems shall be at least two;

[0041] Every two sludge pre-treatment systems are symmetrically distributed to form a folding unit;

[0042] There are two filter pressing systems 1 , and the two filter pressing systems 1 correspond to the two folding systems 2 of the folding unit respectively.

[0043] When the number of folding units is two or more, the filter press system 1 has filter press positions 12, and the number of filter press positions 12 is the same as the number of folding units. Each filter press position 12 corresponds to the folding system 2 of the folding unit. The filter press workpiece of the filter press system 1 can move between the filter press position 12 and the position to be filtered 12. The filter cloth folded by the folding system is in the filter press frame of the filter press system, and the filter press frame of the filter press system can move between the folding system and the filter press position.

[0044] The distance between the upper pressing part and the lower pressing part of the pre-pressing system 3 can be adjusted.

[0045] When the sludge moves from one folding system of the folding unit to another folding system, the sludge in the filter cloth falls off after passing through the unloading system. The unloaded filter cloth is fed through the feeding system downstream of the unloading system, and enters the pre-pressing system and the folding system after carrying the sludge.

[0046] The pre-pressing system is used as a pre-treatment device for sludge. It treats the sludge at low pressure so that the sludge is evenly distributed between the two layers of filter cloth.

[0047] The device also includes a cleaning system 5, which is arranged downstream of the unloading system 6. After the unloading system 6 unloads the sludge on the filter cloth 7, the filter cloth 7 is pulled to the cleaning system 5 to clean the filter cloth 7, and then the next round of sludge feeding, pre-pressing and folding work is carried out.

[0048] The above-mentioned feeding system 4, pre-pressing system 3, folding system 2, cleaning system 5, filter pressing system 1 and unloading system 6 are all existing equipment used for sludge treatment, which can respectively realize the feeding of sludge onto the filter cloth 7, pre-pressing the sludge on the filter cloth 7, folding the filter cloth 7 and the sludge on the filter cloth 7, filtering the folded folded mud cake, and unloading the filtered filter cake from the filter cloth 7. Since they are all existing equipment, the feeding system 4 used in this embodiment is a double-roller strip cutter, and the gap of the strip cutter is adjusted to cut the incoming sludge into thin strips and evenly distribute them on the filter cloth; the pre-pressing system 3 adopts The crawler dewatering unit of the step-boosting deep dewatering machine uses the advantage of preset angles to control the thickness of the incoming sludge and the uniformity of its distribution on the filter cloth; the folding system 2 uses the working characteristics of the servo motor to fix the filter cloth on the folding system, and drives the servo motor to make the filter cloth move back and forth at a preset width; the cleaning system 5 uses a high-pressure pump to spray water evenly into the filter cloth so that the filter cloth can be cleaned before feeding; the filter pressing system 1 uses a hydraulic cylinder to apply sufficiently large pressure to the folded sludge; the unloading system 6 installs a scraper to allow the filter cloth to scrape off the sludge when it passes the scraper position.

[0049] The parts not mentioned in this embodiment are the same as those in the first embodiment.

[0050] Specific application example 1:

[0051] like Figure 1-5 As shown, taking three groups of folding units as an example, the three groups of folding units are arranged side by side, wherein two filter pressing systems 1 are respectively on both sides of the three groups of folding units, and each filter pressing system 1 has three filter pressing positions 12, as shown in FIG. Figure 2-Figure 3 As shown, Figure 2 The three filter press positions 12 on the left are the first left frame position, the second left frame position and the third left frame position. Figure 2 The filter press system 1 on the left is the left press. Figure 2 The three filter pressing positions 12 on the right are respectively the first right frame position, the second right frame position and the third right frame position. Figure 2 The system on the right is the right press; the working process is as follows:

[0052] 1. The sludge is distributed on the lower filter cloth 7 through the feeding system 4. The upper and lower filter cloths 7 start to pre-press the sludge as the pre-pressing system 3 moves;

[0053] 2. The relative height of the feed end of the pre-pressing system 3 is lower than that of the discharge end. The sludge is pre-pressed along with the upper and lower filter cloths 7 through the pre-pressing system 3, so that the sludge can achieve a uniform thickness.

[0054] 3. The sludge filtered by the pre-pressing system 3 is folded by the folding system 2 through reciprocating motion to fold the filter cloth 7. The filter press frame 11 lifts the load-bearing plate to a state nearly flush with the frame surface through the lifting device. As the number of layers of sludge by the folding system 2 increases, the lifting device gradually moves the load-bearing plate downward until the folding system 2 folds the sludge to a preset height or the filter cloth 7 of the prefabricated length stops working;

[0055] 4. After the first sludge pretreatment system of each group of sludge pretreatment systems folds the sludge into the filter press frame 11, the folding system 2 is moved to a position where it does not interfere with the filter press system 1, and the filter press system 1 starts to pressurize the multiple layers of sludge in the filter press frame 11;

[0056] Taking 30 minutes as an example, the filtration process is completed from the left frame position, folded and transferred to the filtration area of ​​the left press, and the left press starts working, which is counted as 0 minutes. At this time, the filter cloth 7 in the left frame position is pulled and transported to the right frame position, and the sludge is laid, pre-pressed and folded at the 15th minute. At the same time, the right press performs filtration on the right frame position. During the period of 16-30 minutes, the right frame position is pulled to transport the filter cloth 7 to the left frame position, and the cloth, pre-pressing and folding are completed at the 30th minute. When the cumulative time reaches 30 minutes, the filtration of the left frame position is completed, and the left press corresponding to the left frame position moves to the left frame position at this time and realizes filtration. During the period of 31-45 minutes, the filter cloth 7 in the left frame carries the squeezed sludge and is transported to the right frame. The process includes unloading, laying, pre-pressing and folding. When the 45th minute is reached, the right frame completes laying, pre-pressing and folding. At this time, the right second frame is pressed for 30 minutes, and the right press moves to the right frame and realizes the filtration. The filter cloth 7 in the right second frame carries the squeezed sludge and is transported to the left second frame during the period of 46-60 minutes. The process includes unloading, laying, pre-pressing, and folding. When the time reaches the 60th minute, the left second frame completes unloading, laying, pre-pressing, and folding. At the same time, the filtration time of the left third frame reaches 30 minutes, and the left press moves to the left second frame and performs filtration. The six frames have two frame status switches corresponding to every 15 minutes to achieve continuous operation.

[0057] Similarly, during the 61st to 75th minute, the filter cloth 7 in the left three frames carries the squeezed sludge to the right three frames for unloading, spreading, pre-pressing, and folding. When the 75th minute is reached, the right three frames are folded, and the right frame is pressed for 30 minutes, then the right press moves to the right three frames and realizes filtration. At this time, the right frame starts to unload, spread, pre-press, and fold toward the left frame from the 76th minute. When the 90th minute is reached, the left frame is folded, the left second frame is pressed, and the left press moves to the right three frames. The left first frame moves and realizes filtration pressing; during the 91st-105th minute, the left second frame unloads, distributes, pre-presses, and folds toward the right second frame. At the 105th minute, the right second frame completes folding, the right third frame completes filtration pressing, and the right press moves toward the right second frame to realize filtration pressing; the right three frames that have completed filtration pressing move toward the left three frames, and the process goes through unloading, distribution, pre-pressing, and folding. When the time reaches the 120th minute, the three frames complete folding, the left first frame completes filtration pressing, and the left press moves toward the left three frames to realize filtration pressing.

[0058] The parts not mentioned in this embodiment are the same as those in the second embodiment.

[0059] Specific application example 2:

[0060] Taking four groups of folding units as an example, the four groups of folding units are distributed side by side, wherein two filter pressing systems 1 are respectively on both sides of the four groups of folding units, each filter pressing system 1 has four filter pressing positions 12, wherein the four filter pressing positions 12 of one filter pressing system 1 are respectively the first left frame position, the second left frame position, the third left frame position and the fourth left frame position, and the filter pressing system 1 is a left press, and the four filter pressing positions 12 of another filter pressing system 1 are respectively the first right frame position, the second right frame position, the third right frame position and the fourth right frame position, and the other filter pressing system 1 is a right press; the working process is as follows:

[0061] 1. The sludge is distributed on the lower filter cloth 7 through the feeding system 4. The upper and lower filter cloths 7 start to pre-press the sludge as the pre-pressing system 3 moves;

[0062] 2. The relative height of the feed end of the pre-pressing system 3 is lower than that of the discharge end. The sludge is pre-pressed along with the upper and lower filter cloths 7 through the pre-pressing system 3, so that the sludge can achieve a uniform thickness.

[0063] 3. The sludge filtered by the pre-pressing system 3 is folded by the folding system 2 through reciprocating motion to fold the filter cloth 7. The filter press frame 11 lifts the load-bearing plate to a state nearly flush with the frame surface through the lifting device. As the number of layers of sludge by the folding system 2 increases, the lifting device gradually moves the load-bearing plate downward until the folding system 2 folds the sludge to a preset height or the filter cloth 7 of the prefabricated length stops working;

[0064] 4. After the first sludge pretreatment system of each group of sludge pretreatment systems folds the sludge into the filter press frame 11, the folding system 2 is moved to a position where it does not interfere with the filter press system 1, and the filter press system 1 starts to pressurize the multiple layers of sludge in the filter press frame 11;

[0065] Taking 30 minutes of the filtration process as an example, the left press and the right press start to act on the left first frame position and the right fourth frame position respectively. During the period of 0-30 minutes, the filter cloth 7 of the right second frame position and the left third frame position simultaneously moves to the left second frame position and the right third frame position, and the steps of (unloading), cloth, pre-pressing and folding are performed on the way. At the 31st minute, the left press moves from the left first frame position to the left second frame position, and the right press moves from the right fourth frame position to the right third frame position to continue to realize filtration dehydration. At the same time, during the 31st to 60th minute, after the filter pressing is completed in the left frame and the right four frames, the filter cloth 7 containing sludge moves to the left four frames and the right frame respectively, and after the steps of unloading, spreading, pre-pressing, and folding, at the 61st minute, the left press moves to the left four frames, and the right press moves to the right frame to continue the filter pressing and dehydration. At this time, the filter cloth 7 with sludge in the left two frames and the right three frames moves to the left three frames and the right two frames respectively, after unloading, spreading, pre-pressing, and folding, after the 91st minute, the left press and the right press act on the left three frames and the right two frames respectively to achieve filter pressing and dehydration. At the same time, the filter cloth 7 containing sludge in the right frame and the left four frames moves to the left one frame and the right four frames respectively, and after unloading, spreading, pre-pressing, and folding, the left press and the right press act on the two frames again to achieve cyclic non-intermittent filter pressing.

[0066] The parts not mentioned in this embodiment are the same as those in the second embodiment.

[0067] Specific application example three:

[0068] like Figure 6 As shown, taking a group of folding units as an example, the two filter pressing systems 1 matched with the folding units are respectively on both sides of the folding units, and the filter pressing position 12 of each filter pressing system 1 is fixed, which is recorded as the left frame position. The filter pressing system 1 is the left press, and the other filter pressing system 1 is recorded as the right frame position, and the other filter pressing system 1 is the right press; the working process is as follows:

[0069] 1. The sludge is distributed on the lower filter cloth 7 through the feeding system 4, and the upper and lower filter cloths 7 start to pre-press the sludge as the pre-pressing system 3 moves;

[0070] 2. The relative height of the feed end of the pre-pressing system 3 is lower than that of the discharge end. The sludge is pre-pressed along with the upper and lower filter cloths 7 through the pre-pressing system 3, so that the sludge can achieve a uniform thickness.

[0071] 3. The sludge filtered by the pre-pressing system 3 is folded by the folding system 2 through reciprocating motion to fold the filter cloth 7. The filter press frame 11 lifts the load-bearing plate to a state nearly flush with the frame surface through the lifting device. As the number of layers of sludge by the folding system 2 increases, the lifting device gradually moves the load-bearing plate downward until the folding system 2 folds the sludge to a preset height or the filter cloth 7 of the prefabricated length stops working;

[0072] 4. After the sludge is folded into the filter press frame 11 by the sludge pretreatment system, the folding system 2 is moved to a position where it does not interfere with the filter press system 1, and the filter press system 1 begins to pressurize the multiple layers of sludge in the filter press frame 11;

[0073] Taking the 30-minute filtration process as an example, the filter press system 1 starts to pressurize the folded sludge in the filter press frame 11. After 30 minutes, the left press stops working. At this time, the sludge in the filter press frame 11 is discharged, spread, pre-pressed, and folded by the sludge pre-treatment system. The filter press frame 11 on the other side folds the sludge, and the right press presses the sludge. At this time, the left press is in a standby state. In this way, the sludge is discharged and spread at the same time.

[0074] The parts not mentioned in this embodiment are the same as those in the second embodiment.

[0075] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for filtering sludge by folding filter cloth in multiple positions continuously back and forth, characterized in that: The method comprises the following steps: two folding systems and a continuous filter cloth are used as a group of folding units; in each group of folding units, the continuous filter cloth is folded back and forth between the two folding systems to fold the sludge into a folded mud cake; and the folded mud cake is filtered by a filter press system to obtain a filter press mud cake; wherein, when the filter press mud cake on the filter cloth is unloaded, the sludge is simultaneously laid on the filter cloth.

2. A method for filtering sludge by folding filter cloth in multiple positions continuously back and forth according to claim 1, characterized in that: In each group of folding units, a pre-pressing system and a feeding system are symmetrically distributed from outside to inside between the two folding systems. The feeding system is used to transport the sludge to the continuous filter cloth, and the pre-pressing system is used to pre-press the filter cloth and sludge traveling back and forth between the two folding systems.

3. A method for filtering sludge by folding filter cloth in multiple positions continuously back and forth according to claim 2, characterized in that: The method for pre-pressing and folding the sludge into a folded mud cake is as follows: firstly, the sludge is fed from a feeding system to a continuous filter cloth, and is transported through a pre-pressing system for pre-pressing, and then, after pre-pressing, is continuously transported to a folding system, and the folding system folds the sludge to obtain a folded mud cake.

4. A method for filtering sludge by folding filter cloth in multiple positions continuously back and forth according to claim 2, characterized in that: The method for obtaining a filter press mud cake by filter pressing the folded mud cake is as follows: the folded mud cake is transported to a filter press frame of a filter press system, the filter press frame moves toward the filter press position, and pressure is applied to the folded mud cake to obtain a filter press mud cake.

5. A method for filtering sludge by folding filter cloth in multiple positions continuously back and forth according to claim 1, characterized in that: When the number of folding units is two or more, the number of filter pressing systems is two, the two or more folding units are distributed side by side, and the filter pressing systems are distributed on both sides of the two or more folding units, corresponding to the folding systems of the two or more folding units; wherein each filter pressing system has the same number of filter pressing positions as the folding units, and the filter pressing workpiece of each filter pressing system can move at the filter pressing position.

6. A device for filtering sludge by folding filter cloth in multiple positions continuously and back, the device being applied to the method according to any one of claims 1 to 5, characterized in that: Including feeding system, pre-pressing system, folding system, filter pressing system and unloading system; Among them, a discharge system, a feed system, a pre-pressing system and a folding system are connected in sequence to form a sludge pre-treatment system; The number of sludge pre-treatment systems shall be at least two; Every two sludge pre-treatment systems are symmetrically distributed to form a folding unit; The number of the filter pressing systems is two, and the two filter pressing systems correspond to the two folding systems of the folding unit respectively.

7. A device for filtering sludge by continuous reciprocating folding of filter cloth in multiple positions according to claim 6, characterized in that: When the number of folding units is two or more, the filter pressing system has filter pressing positions, the number of which is the same as the number of folding units, each filter pressing position corresponds to the folding system of the folding unit, and the filter pressing workpiece of the filter pressing system can move between the filter pressing position and the position to be filtered.

8. A device for filtering sludge by continuous reciprocating folding of filter cloth in multiple positions according to claim 6, characterized in that: The distance between the upper pressing part and the lower pressing part of the pre-pressing system can be adjusted.

9. A device for filtering sludge by continuous reciprocating folding of filter cloth in multiple positions according to claim 6, characterized in that: When the sludge moves from one folding system of the folding unit to another folding system, the sludge in the filter cloth falls off after passing through the unloading system. The unloaded filter cloth is fed through the feeding system downstream of the unloading system, and enters the pre-pressing system and the folding system after carrying the sludge.

10. A device for filtering sludge by continuous reciprocating folding of filter cloth in multiple positions according to claim 6, characterized in that: The pre-pressing system is used as a pre-treatment device for sludge. It treats the sludge at low pressure so that the sludge is evenly distributed between the two layers of filter cloth.

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