Filter plate group for realizing deep dehydration of sludge and sludge filter pressing method

Abstract

The invention relates to the field of sludge dewatering treatment, in particular to a filter plate group for realizing deep sludge dewatering for sludge filter pressing and a sludge filter pressing method. The height of the sludge cavity of the filter plate group is 23-28mm; and filter screens are respectively arranged between the box plate and the filter cloth and between the membrane plate and the filter cloth. Calculating the sectional area of a sludge separation port according to the sludge flow and the sludge injection port flow velocity; the quantitative mud injection amount M required by the filter pressing mud cake is calculated according to the water content of the incoming mud, and quantitative mud injection is adopted. The supporting force of the filter screen effectively ensures the smoothness of the water delivery channel, and ensures that filter liquor obtained through filter pressing is rapidly discharged; the sectional area of the sludge separating hole is calculated to ensure that the sludge is sprayed out of the sludge outlet hole of the cloth clamping device at a certain speed instead of overflowing; and according to the change of the thickness of the mud cake and the water content of the incoming mud, the required mud injection amount is calculated, and the problems of large mud injection amount, long mud injection time, thick mud cake, high water content and the like in the prior art are avoided.

Description

Technical Field

[0001] The invention relates to sludge dewatering treatment equipment, in particular to a filter plate group for sludge filter pressing and realizing deep dewatering of sludge and a sludge filter pressing method. Background Art

[0002] At present, diaphragm plate and frame filter presses are widely used in the sludge treatment process of sewage plants. The diaphragm plate and frame filter plate group is one of the main filter pressing parts of the filter press. However, in order to improve the processing capacity, the diaphragm plate and frame filter plate group of the existing diaphragm plate and frame filter press is used to accommodate the sludge. The filter chamber height is relatively large, and the single mud injection volume is large. The mud cake after filtration is very thick, usually more than 30mm. Due to the thickness of the mud cake, the outer side of the mud cake is crusted, and the core appears "loose", and the water in the core is not easy to penetrate the outer mud shell. Even if the filtration pressure and filtration time are increased, the water in the core cannot be separated. The filtration time is long and the water content of the mud cake is high. In addition, the existing diaphragm plate and frame filter plate group does not discharge water smoothly during the filtration process, which is certain To a certain extent, the moisture content of the mud cake is high; in addition, for filter plate groups of the same specifications, the cross-sectional area of ​​the mud distribution port of the cloth clamp is usually proportional to the size of the sludge chamber of the filter plate group, regardless of the number of filter plate groups. However, in actual production, when the number of filter plate groups is large, the mud injection flow rate in the early stage of mud injection is relatively large, and when the number of filter plate groups is small, the mud injection flow rate in the early stage of mud injection is relatively small. When the cross-sectional area of ​​the mud distribution port of the cloth clamp is fixed, it will cause a large difference in pressure at the inlet position of each mud chamber, resulting in uneven mud cake thickness between each filter plate group. Due to the diaphragm stroke constraint of the diaphragm plate frame filter plate group, the chamber with less mud will cause the diaphragm to exceed the stroke and be damaged, and the thick mud cake has a "soft core" and a high moisture content. Summary of the invention

[0003] In view of the problems that the existing diaphragm plate-frame filter press has problems such as the mud cake being too thick, resulting in a long filtration time, and a high moisture content of the mud cake, the present invention provides a filter plate group and a sludge filtration method for achieving deep sludge dehydration: reducing the mud chamber height of the diaphragm plate-frame filter plate group, reducing the mud cake thickness, reducing the percentage of the "runny core" part, and the "runny core" moisture content is lower than the "runny core" moisture content of the thick mud cake, effectively reducing the mud cake moisture content, while ensuring that the diaphragm stroke does not exceed the safe use range; adding a filter cloth with a certain support force and a soft The tough filter screen has a supporting force that effectively ensures the smoothness of the water delivery channel and the rapid discharge of the filtrate from the filter press. The cross-sectional area of ​​the mud outlet holes of the filter plate group cloth clamp is calculated to ensure that the sludge is ejected from the mud outlet holes of the cloth clamp at a certain speed instead of overflowing. The total amount of mud injected is quantitatively injected, and the required amount of mud injection is calculated according to the changes in the mud cake thickness and the moisture content of the incoming mud, avoiding the existing problems of large mud injection volume, long mud injection time, thick mud cake and high moisture content, so as to ensure that the moisture content of the filter press mud cake is low and the equipment processing capacity is not affected.

[0004] The technical scheme of the present invention is: a filter plate group for realizing deep dehydration of sludge, comprising a box plate assembly, a membrane plate assembly, a main cloth clamp, an auxiliary cloth clamp, a mud dividing port and a sludge chamber, wherein the box plate assembly and the membrane plate assembly are arranged side by side and spaced apart, and the space between the box plate assembly and the membrane plate assembly forms a sludge chamber; the end face of the main cloth clamp of the box plate assembly and the end face of the auxiliary cloth clamp of the membrane plate assembly are in close contact, and a mud dividing port is formed between the groove of the end face of the main cloth clamp of the box plate assembly and the end face of the auxiliary cloth clamp of the membrane plate assembly; the height of the sludge chamber is 23-28 mm; a sealing ring and a filter screen I are respectively arranged on both sides of the box plate in the middle of the box plate assembly, and the outer ring size of the filter screen I is smaller than the inner ring size of the sealing ring; filter cloth I is arranged on both sides of the box plate, and the filter cloth I covers the sealing ring and the filter screen I; a sludge channel I is arranged at the center of the box plate, and the main cloth clamp and the auxiliary cloth clamp are respectively arranged at both ends of the sludge channel I and fix the filter screen I and the filter cloth I; Filter screens II are respectively arranged on both sides of the membrane plate in the middle of the membrane plate assembly, and filter cloths II are respectively arranged on the outer sides of the two filter screens II, and the filter cloths II cover the filter screens II; a sludge channel II is arranged in the center of the membrane plate, and a main cloth clamp and an auxiliary cloth clamp are respectively arranged at both ends of the sludge channel II to press the filter screen II and the filter cloth II.

[0005] In the above technical solution, the cross-sectional area of ​​the mud outlet 4 is calculated according to the formula S=q0 / v / 3600: Wherein: S- cross-sectional area of ​​the mud outlet of the cloth clamp, the sum of the cross-sectional areas of several grooves; q0- sludge flow rate in the early stage of mud injection when the number of sludge chambers is 1, unit: m³ / h, the value is 9.5~12.5 times the volume of a single sludge chamber, unit: m³; v- flow velocity of the mud outlet of the cloth clamp, unit: m / s.

[0006] A sludge filter pressing method for achieving deep sludge dehydration includes two stages: sludge injection and filter pressing; Mud injection stage I: According to the water content of the incoming mud, the formula "M=G 干 / (1-W%) + dosage of medicine" to calculate the quantitative mud injection amount M required for the filter cake; Where: M-single mud injection volume, m³; G 干 -The amount of dry sludge, that is, the capacity of the filter press during actual production, unit: t / time; W%-the moisture content of the incoming sludge; Mud injection stage II: Based on the quantitative mud injection volume M calculated in mud injection stage I, the entire mud injection process is carried out in the following steps: Step 1: Calculate the sludge flow rate Q0 at the initial stage of sludge injection according to the formula Q0=K×N×q0, where: Q0-total sludge flow rate at the initial stage of sludge injection, unit: m³ / h; N-number of sludge chambers, unit: pieces; K-calibration coefficient; q0-sludge flow rate at the initial stage of sludge injection when the number of sludge chambers is 1, unit: m³ / h; Step 2, mud injection: Step sequence 1, the sludge flow rate Q0 in the initial stage of mud injection, the set pressure is P0. When the mud injection duration reaches T0, when the cumulative flow rate M0 of the flowmeter < M, enter step sequence 2. When M0 = M, the mud injection pump stops mud injection; set the sludge flow rate Q1 in the initial stage of mud injection, the set pressure is P1. When the mud injection duration reaches T1, when the cumulative flow rate M1 of the flowmeter < M, enter step sequence 3. When M1 = M, the mud injection pump stops mud injection, and so on. When the set mud injection pump flow rate is Q n-1 When n-1 seconds, but the mud injection pressure reaches P n-1 , through program control, finely adjust the mud injection flow rate of the mud injection pump. When the mud injection duration reaches T n-1 , and M n-1 < M, enter the next step sequence; if the mud injection duration reaches T n-1 seconds, the mud injection pressure is less than P n-1 , M n-1 < M and enter the next step sequence; during this process, if M n-1 = M, at the moment when M n-1 = M, the mud injection pump stops mud injection; Wherein: Q1, Q2, Q n-1 are the sludge flow rates in different stages, and n > 1; Filter pressing stage: After the mud injection ends, inject pressing water into the pressing water cavity of the diaphragm filter plate group to squeeze the sludge in the sludge cavity until the filter pressing ends.

[0007] The beneficial effects of the present invention are: Adding a filter screen to prevent partial blockage of the hydrophobic channels during the sludge filter pressing process, effectively improving the smoothness of the hydrophobic channels during the mud injection and filter pressing processes, and being beneficial to reducing the water content of the mud cake; The sludge at the inlet of the mud injection hole 4 has a certain pressure and the pressure difference at each mud injection hole 4 is controllable, so that the sludge jets out at a certain speed, effectively solving the problem of uneven mud cake thickness in each mud cavity; During the sludge filter pressing process, a crusting phenomenon will occur at the positions of the filter cloths on both sides of the sludge cavity, making the water in the sludge in the center of the cavity unable to be quickly filtered and separated. The mud cavity formed by the traditional diaphragm plate and frame filter plate group has a large height and a very thick mud cake, usually more than 30 mm. After filter pressing, a "soft center" appears in the center of the formed mud cake, resulting in a very high water content of the mud cake. The present invention reduces the height of the sludge cavity, and the filtration area of the filter cloth remains unchanged, which can achieve rapid mud injection. At the same time, the thickness of the formed mud cake is controlled at about 15 mm, greatly reducing the water content and proportion of the "soft center", and effectively reducing the water content of the mud cake; Adopting quantitative mud injection according to the water content of the sludge, making the thickness of the mud cake controllable, avoiding the problems of too thick mud cake and uneven mud cake thickness, and avoiding damage to the diaphragm plate and frame template caused by too thin mud cake in individual chambers.

[0008] The production cycle is short. Due to different types of sludge, the production cycle is between 1.5 hours and 2.5 hours. Under the premise of meeting the processing capacity, the moisture content of the mud cake is lower, the mud cake is thinner, and it is easy to unload the mud. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 yes Figure 1 A partial enlarged view of middle A; Figure 3 It is a schematic diagram of the structure of the box plate assembly of the present invention; Figure 4 It is a schematic diagram of the structure of the template assembly of the present invention; Figure 5 yes Figure 3 A partial enlarged view of B in the middle; Figure 6 yes Figure 4 A partial enlarged view of middle A; Figure 7 is a front view of the auxiliary cloth clamp of the present invention; Figure 8 is a cross-sectional view of the auxiliary cloth clamp of the present invention; Fig. 9 is a front view of the main cloth clamp of the present invention; Fig.10 It is a cross-sectional view of the main cloth clamp of the present invention.

[0010] Wherein: 1. box plate assembly; 1-1. box plate; 1-1-1. sealing ring I; 1-1-2. box plate base plate; 1-2. sealing ring; 1-3. filter cloth I; 1-4. filter screen I; 1-5. sludge channel I; 2. membrane plate assembly; 2-1. membrane plate; 2-1-1. sealing ring II; 2-1-2. diaphragm; 2-3. filter cloth I; 2-4. filter screen II; 2-5. sludge channel II; 3-1. main cloth clamp; 3-1-1. groove; 3-2. auxiliary cloth clamp; 4. mud dividing port; 5. sludge chamber. DETAILED DESCRIPTION

[0011] like Figures 1 to 10 As shown, a filter plate group for achieving deep dehydration of sludge includes a box plate assembly 1, a membrane plate assembly 2, a main cloth clamp 3-1, an auxiliary cloth clamp 3-2, a mud separation port 4 and a sludge chamber 5; A plurality of grooves 3-1-1 are arranged on the end surface of the main cloth clamp 3-1 of the box plate assembly 1; sealing rings 1-2 are arranged on both sides of the sealing ring 1-1-1 of the box plate 1-1, and filter screens I1-4 are arranged on both sides of the box plate 1-1, and the outer ring size of the filter screen I1-4 is smaller than the inner ring size of the sealing ring 1-2; the sealing ring 1-2 and the filter screen I1-4 are covered with filter cloth I1-3; the sludge channel I1-5 is arranged at the center of the box plate 1-1, and the main cloth clamp 3-1 and the auxiliary cloth clamp 3-2 are respectively installed at both ends of the sludge channel I1-5, and the main cloth clamp 3-1 and the auxiliary cloth clamp 3-2 respectively fix the filter screen I1-4 and the filter cloth I1-3 at corresponding positions; The filter screen II2-4 is arranged on both sides of the membrane plate 2-1 in the middle of the membrane plate assembly 2, and the outer sides of the two filter screens II2-4 are covered with filter cloth II2-3; the sludge channel II2-5 is arranged in the center of the membrane plate 2-1, and the main cloth clamp 3-1 and the auxiliary cloth clamp 3-2 are respectively installed at both ends of the sludge channel II2-5 and press and fix the filter screen II2-4 and filter cloth II2-3 at the corresponding positions; The box plate assembly 1 and the membrane plate assembly 2 are hung side by side on the crossbeam of the filter press at intervals. The space between the box plate assembly 1 and the membrane plate assembly 2 forms a sludge chamber 5. The height of the conventional sludge chamber is reduced to about 25 mm by the following method to ensure that the thickness of the sludge produced by the filter press is between 8 mm and 15 mm. The specific method is: thicken the thickness of the box plate base plate 1-1-2 of the box plate 1-1 so that the height difference between the sealing surface of the box plate 1-1 sealing ring Ⅰ1-1-1 and the surface of the box plate base plate Ⅰ1-1-2 is L1=12 mm; reduce the thickness of the sealing ring Ⅱ2-1-1 of the membrane plate 2 so that the height difference between the sealing surface of the sealing ring Ⅱ2-1-1 and the surface of the diaphragm 2-1-2 is L2=3 mm, and at this time the sludge chamber height is about 25 mm. The end face of the main cloth clamp 3-1 of the box plate assembly 1 is in close contact with the end face of the auxiliary cloth clamp 3-2 of the membrane plate assembly 2, and a plurality of mud dividing ports 4 are formed between the plurality of grooves 3-1-1 on the end face of the main cloth clamp 3-1 of the box plate assembly 1 and the end face of the auxiliary cloth clamp 3-2 of the membrane plate assembly 2.

[0012] Example: Take the sludge injection process of a sludge treatment plant's municipal sludge treated by a filter press equipped with 120 filter chambers of 1820×1820×25 mm as an example: Calculate the cross-sectional area of ​​the mud outlet 4 according to the formula S=q0 / v / 3600; Where: q0-sludge flow rate at the initial stage of sludge injection when the number of sludge chambers is 1, unit: m³ / h; q0=1.82×1.82×0.025×12.5=1.035(m³ / h); v-Flow rate of the mud outlet of the clamp, unit: m / s, the value is the mud flow rate in the mud channel at the initial stage of mud injection, the total length of the mud chamber in the center of 120 filter plates is 22.4m, the time for the mud to flow from the center hole of the first filter plate group to the center hole of the last filter plate group is set to 2min, calculation: v=22.4 / 2 / 60=0.187 (m / s) The cross-sectional area of ​​the mud opening of the cloth clamp is the sum of the cross-sectional areas of several grooves: S=1.035 / 0.187 / 3600=0.0015(㎡) A sludge filter pressing method for achieving deep sludge dehydration includes two stages: sludge injection and filter pressing; Mud injection stage I: According to the water content of the incoming mud, the formula "M=G 干 / (1-W%) + dosage" to calculate the quantitative mud injection volume M required for the filter cake; where: According to the laboratory experimental data, the thickness of the mud cake after filtration is 12.5mm, and the best state is when the moisture content after filtration is 57%. 干 =N×(1.82×1.82×mud cake thickness)×(1-mud cake moisture content)×mud cake density =120×(1.82×1.82×0.0125)×(1-57%)×1.2 =2.56 (m³ / time) The moisture content of the incoming mud is 92%. The amount of incoming mud is: M=2.56 / (1-92%)+dose =32+13 =45 (m³ / time) Mud injection stage II: Based on the quantitative mud injection volume M calculated in mud injection stage I of 45m³ / time, the entire mud injection process is carried out according to Table 1: Table 1: Mud injection process flow chart Step sequence <![CDATA[Slurry injection pump flow rate Q n-1 (m³ / h)]]> <![CDATA[Maximum pressure P n-1 (Bar)]]> <![CDATA[Injection mud duration T n-1 (s)]]> <![CDATA[Cumulative flow rate M of the flowmeter n-1 (m³)]]> 1 145 2.0 240 <![CDATA[M0]]> 2 105 3.0 240 <![CDATA[M2]]> 3 75 4.0 480 <![CDATA[M3]]> 4 40 5.0 300 <![CDATA[M4]]> 5 35 6.0 300 <![CDATA[M5]]> 6 25 7.0 600 <![CDATA[M6]]> 7 20 8.0 800 <![CDATA[M7]]> Q0=K×N×q0, M0, M2, M3, M4, M5, M6, M7 are the cumulative flow rate of the flow meter at step 1, step 2, step 3, step 4, step 5, step 6, step 7 respectively, unit: m³ / h; K-calibration coefficient, here the value is 1.15; N-number of mud cavities (mud cakes), unit: pieces, 120 pieces; q0-When the number of sludge chambers is 1, the sludge flow rate at the initial stage of sludge injection is 1.035m³ / h; Q0-total sludge flow rate at the initial stage of sludge injection, unit: m³ / h; Q0=1.15×120×1.035=143 m³ / h; Table 1 shows the mud injection process when a plate filter press with 120 filter cavities sized 1820×1820×25 mm is used to treat municipal sludge from a certain sludge treatment plant. The incoming sludge has a moisture content of 92%. After pressure filtration, the thickness of the filter cake is 8 - 15 mm, and the moisture content of the filter cake is 60%. The data in Table 2 vary slightly according to different sludge properties. When the set flow rate Q of the mud injection pump n-1 is such that if the mud injection duration is less than T n-1 seconds, but the mud injection pressure reaches P n-1 , the mud injection flow rate of the mud injection pump is micro-adjusted through program control until the mud injection duration reaches T n-1 , and when M n-1 < 45 m³, it enters the next step; if the mud injection duration reaches T n-1 seconds and the mud injection pressure is less than P n-1 , and M n-1 < M, it enters the next step; during this process, if M n-1 = 45 m³, the mud injection pump stops injecting mud at the moment when M n-1 = 45 m³, and so on. During the 7th step, the working duration is the set duration of 800 s, but when M7 < 45 m³, the 7th step is automatically repeated.

[0013] Pressure filtration stage: After mud injection, press water is injected into the press water cavity of the diaphragm filter plate group to squeeze the sludge in the sludge cavity 5 until the pressure filtration is completed.

Claims

1. A filter plate assembly for achieving deep dehydration of sludge, comprising a box plate assembly (1), a membrane plate assembly (2), a main cloth clamp (3-1), an auxiliary cloth clamp (3-2), a mud separation port (4) and a mud chamber (5), wherein the box plate assembly (1) and the membrane plate assembly (2) are arranged side by side and spaced apart, and the space between the box plate assembly (1) and the membrane plate assembly (2) forms the mud chamber (5); the end surface of the main cloth clamp (3-1) of the box plate assembly (1) and the end surface of the auxiliary cloth clamp (3-2) of the membrane plate assembly (2) are in close contact, and the mud separation port (4) is formed between the groove (3-1-1) on the end surface of the main cloth clamp (3-1) of the box plate assembly (1) and the end surface of the auxiliary cloth clamp (3-2) of the membrane plate assembly (2); characterized in that: The height of the sludge chamber (5) is 23-28 mm; a sealing ring (1-2) and a filter screen I (1-4) are respectively arranged on both sides of the box plate (1-1) in the middle of the box plate assembly (1), and the outer ring size of the filter screen I (1-4) is smaller than the inner ring size of the sealing ring (1-2); a filter cloth I (1-3) is arranged on both sides of the box plate (1-1), and the filter cloth I (1-3) covers the sealing ring (1-2) and the filter screen I (1-4); a sludge channel I (1-5) is arranged at the center of the box plate (1-1), and a main cloth clamp (3-1) and an auxiliary cloth clamp (3-2) are respectively arranged at both ends of the sludge channel I (1-5) and fix the filter screen I (1-4) and the filter cloth I (1-3); Filter screens II (2-4) are respectively arranged on both sides of the membrane plate (2-1) in the middle of the membrane plate assembly (2), and filter cloths II (2-3) are respectively arranged on the outer sides of the two filter screens II (2-4), and the filter cloths II (2-3) cover the filter screens II (2-4); a sludge channel II (2-5) is arranged in the center of the membrane plate (2-1), and a main cloth clamp (3-1) and an auxiliary cloth clamp (3-2) are respectively arranged at both ends of the sludge channel II (2-5) and press the filter screen II (2-4) and the filter cloth II (2-3).

2. A filter plate assembly for achieving deep sludge dehydration according to claim 1, characterized in that: Calculate the cross-sectional area of ​​the mud outlet (4) according to the formula S=q0 / v / 3600; Wherein: S- cross-sectional area of ​​the mud outlet of the cloth clamp, the sum of the cross-sectional areas of several grooves; q0- sludge flow rate in the early stage of mud injection when the number of sludge chambers is 1, unit: m³ / h, the value is 9.5~12.5 times the volume of a single sludge chamber, unit: m³; v- flow velocity of the mud outlet of the cloth clamp, unit: m / s.

3. A sludge filter press method for achieving deep sludge dehydration is characterized by: It includes two stages: mud injection and filter pressing; Mud injection stage I: According to the water content of the incoming mud, the formula "M=G 干 / (1-W%) + dosage of medicine" to calculate the quantitative mud injection amount M required for the filter cake; Where: M-single mud injection volume, unit: m³; G 干 -The amount of dry sludge, that is, the capacity of the filter press during actual production, unit: t / time; W%-the moisture content of the incoming sludge; Mud injection stage II: Based on the quantitative mud injection volume M calculated in mud injection stage I, the entire mud injection process is carried out in the following steps: Step 1: Calculate the sludge flow rate Q0 at the initial stage of sludge injection according to the formula Q0=K×N×q0, where: Q0-total sludge flow rate at the initial stage of sludge injection, unit: m³ / h; N-number of sludge chambers, unit: pieces; K-calibration coefficient; q0-sludge flow rate at the initial stage of sludge injection when the number of sludge chambers is 1, unit: m³ / h; Step 2, sludge injection: In step sequence 1, the sludge flow rate Q0 at the initial stage of sludge injection, with the set pressure P0. When the sludge injection duration reaches T0, when the cumulative flow rate M0 of the flowmeter < M, enter step sequence 2. When M0 = M, the sludge injection pump stops injecting sludge; the sludge flow rate Q1 at the initial stage of sludge injection, with the set pressure P1. When the sludge injection duration reaches T1, when the cumulative flow rate M1 of the flowmeter < M, enter step sequence 3. When M1 = M, the sludge injection pump stops injecting sludge, and so on. When the set sludge injection pump flow rate is Q n-1 If the sludge injection duration is less than T n-1 seconds, but the sludge injection pressure reaches P n-1 , the sludge injection flow rate of the sludge injection pump is micro-adjusted through program control. When the sludge injection duration reaches T n-1 , and M n-1 < M, enter the next step sequence; if the sludge injection duration reaches T n-1 seconds, the sludge injection pressure is less than P n-1 , M n-1 < M and enter the next step sequence; during this process, if M n-1 = M, at the moment when M n-1 = M, the sludge injection pump stops injecting sludge; When the set mud injection pump flow rate is Q n-1 If the mud injection duration is less than T n-1 seconds, but the mud injection pressure reaches P n-1 , the mud injection pump flow rate is micro-adjusted through program control until the mud injection duration reaches T n-1 , and when M n-1 <M, it enters the next step; if the mud injection duration reaches T n-1 seconds and the mud injection pressure is less than P n-1 , M n-1 <M and it enters the next step; during this process, if M n-1 =M, the mud injection pump stops injecting mud at the moment when M n-1 =M; Among them: Q1, Q2, Q n-1 is the sludge flow rate at different stages, n is greater than 1; Filter pressing stage: After the sludge injection is completed, press water is injected into the press water cavity of the membrane filter plate group to squeeze the sludge in the sludge cavity (5) until the filter pressing is completed.

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