阅读说明：本技术 一种板框压滤机压滤工艺 (Filter pressing process of plate-and-frame filter press ) 是由 张悦 于 2021-08-28 设计创作，主要内容包括：本申请公开了一种板框压滤机压滤工艺,通过调整进料工艺,形成由低压大流量平滑过渡到高压低流量的进料特性；在初始阶段,由低压大流量进料迅速形成泥饼层,通过泥饼层的过滤对进料的固体颗粒物高效截留；随着泥饼密实度提高、过滤阻力增加,自动过渡到高压低流量阶段；进料完成后,进一步进行压榨。上述工艺,可显著降低压滤液的固体悬浮浓度,降低泥饼含水率,提高进料污泥含固率,减少压滤时间,提高滤布的使用寿命,降低压滤成本。(The application discloses a filter pressing process of a plate and frame filter press, which forms the feeding characteristic of smoothly transiting from low pressure and large flow to high pressure and low flow by adjusting the feeding process; in the initial stage, a mud cake layer is quickly formed by low-pressure large-flow feeding, and solid particles fed are efficiently intercepted through the filtration of the mud cake layer; automatically transitioning to a high-pressure low-flow stage along with the improvement of the compactness of the mud cake and the increase of the filtration resistance; after the feeding is completed, further pressing is performed. The process can obviously reduce the solid suspension concentration of the filter pressing liquid, reduce the water content of mud cakes, improve the solid content of the fed sludge, reduce the filter pressing time, prolong the service life of filter cloth and reduce the filter pressing cost.)

1. A filter pressing process of a plate and frame filter press comprises the following steps:

s1, performing large-flow initial feeding, wherein a high-pressure piston pump is adopted for feeding driving, the feeding pressure and flow are automatically adjusted according to the feeding state, the feeding pressure is increased from 0MPa to 1.5MPa within 0-20min, the feeding amount reaches 70% -80% of the total feeding amount, a plate frame sludge storage chamber is quickly filled with sludge to form a high-solid sludge cake layer, the sludge is firstly filtered by the sludge cake layer, and then the liquid is filtered by a filter cloth;

s2, feeding at high pressure and low flow, gradually increasing the feeding pressure from 1.5MPa to 2.0MPa after 15-25min, and feeding for 3-40min under the pressure of 2.0MPa, wherein the feeding amount reaches 20-30% of the total feeding amount;

s3, stopping feeding, and locking the plate frame;

s4, starting a squeezing hydraulic system, wherein the highest pressure reaches 2.8MPa and lasts for 1-2 h;

s5, finishing the filter pressing process, starting an air back blowing device, wherein the back blowing air pressure is not less than 0.8 MPa;

s6, opening the plate frame, and enabling the mud cakes to fall off automatically;

wherein the feed material is excess sludge of biochemical treatment of town sewage with the solid content of 18-22%, and the water content of the filter-pressed sludge cake is 38-45%.

2. The filter pressing process of a plate and frame filter press according to claim 1, wherein: preferably, the sludge is pretreated before entering the cooling tank, and the pretreatment comprises mixed feeding, hot alkali reaction and material cooling.

3. The filter pressing process of a plate and frame filter press according to claim 2, wherein: in the material cooling step, the material storage tank adopts a cooling tank which is of a jacket type, flowing cold water is pumped in as a cooling source, and the outlet water is cooled through a cooling tower and is recycled.

4. A filter pressing process of a plate and frame filter press according to claim 3, characterized in that: 30% of the cooled material is reserved in the cooling tank, the cooling temperature of the material is below 60 ℃, and a stirrer is arranged in the cooling tank.

5. A filter pressing process of a plate and frame filter press according to claim 3, characterized in that: the top of the cooling tank is connected with a negative pressure system, the gas in the cooling tank is condensed, the negative pressure system comprises a vacuum pump, a buffer tank and a cooling tower, and the condensate flows back into the cooling tank.

6. A filter pressing process of a plate and frame filter press according to claim 3, characterized in that: the mixed feeding comprises lime solution preparation and synchronous mixed feeding, wherein the lime solution preparation comprises the following steps: adding water into the lime dry powder, stirring and dissolving to form saturated lime liquid, wherein the using amount of the lime dry powder is 2.5-4.5% of the sludge amount; the synchronous mixing feeding is as follows: the method comprises the steps of synchronously feeding the sludge and the lime liquid in proportion, wherein the feeding mode is that a lime liquid delivery pump and a sludge delivery pump are started and delivered to a reaction kettle through a pipeline static mixer.

7. A filter pressing process of a plate and frame filter press according to claim 3, characterized in that: the hot alkali reaction is specifically as follows: the method is characterized in that high-speed rotating mechanical force is directly acted on a mixture of the activated sludge and the lime, meanwhile, the mixture of the sludge and the lime forms hydraulic cyclone under the action of the high-speed rotating force, the cell walls of the activated sludge are damaged under the double actions of the high-speed rotating mechanical force and the hydraulic cyclone, and in the process, the activated sludge and the lime are subjected to thermokalite reaction for 40-60min at the reaction temperature of 110-130 ℃.

8. The filter pressing process of a plate and frame filter press according to claim 7, wherein: in the hot alkali reaction, a cold-hot material exchange mode is adopted for feeding, hot mud with the volume of 10-20% of the container is reserved in the reaction container, and the temperature of the hot mud is 110-.

Technical Field

The invention belongs to the technical field of filter pressing of a filter press, and particularly relates to a filter pressing process of a plate-and-frame filter press.

Background

The plate-and-frame filter press is important equipment in sludge treatment, the plate-and-frame filter press bears sludge through a cavity space between plate frames, the sludge squeezing and dewatering process is realized by means of the filtering action of filter cloth, wherein the sludge is fed by a screw pump or a diaphragm pump generally and is conveyed into a feeding channel in the middle of the plate-and-frame filter press from a storage bin, the feeding channel is filled into the plate-and-frame gap, the feeding pressure is increased along with the increase of the sludge filling amount in the plate-and-frame gap, the dewatering resistance is gradually increased, the feeding is stopped when the feeding pressure reaches a threshold value, and then the squeezing and dewatering are performed through a squeezing diaphragm. In the prior art, the research on the selection of a feeding pump, a feeding process and a squeezing process is less, the water content of a mud cake after squeezing and dewatering is still high and is usually more than 65%, and the content of suspended matters of filtrate discharged through filter pressing is more, so that the discharge requirement is not met, and the filtrate can still meet the reuse requirement by further treatment.

Among the current filter-pressing technology, patent CN 112274982A, it is through the continuous water content that reduces of multichannel process, utilizes plate and frame filter press to carry out the water content of one-step reduction filter cake at last, realizes making the water content of filter cake finally be less than sixty percent, and at the filter-pressing in-process, with the large-traffic sludge pump of low pressure at the filter-pressing initial stage, along with filter cake thickness increase, resistance increase, the filter-pressing speed descends and uses high-pressure low flow sludge pump this moment. Although improving feeding process in this patent, it uses two kinds of pumps to feed, and the cost is higher, and the process control degree of difficulty is big, and feeding process is complicated, does not subdivide specific feeding process moreover, and final mud cake moisture content still is about 60%, and feeding moisture content requires highly.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a filter pressing process of a plate-and-frame filter press.

A filter pressing process of a plate and frame filter press comprises the following steps:

s1, performing large-flow initial feeding, wherein a high-pressure piston pump is adopted for feeding driving, the feeding pressure and flow are automatically adjusted according to the feeding state, the feeding pressure is increased from 0 to 1.5MPa within 10-20min, the feeding amount reaches 70% -80% of the total feeding amount, a plate frame sludge storage chamber is quickly filled with sludge to form a high-solid sludge cake layer, the sludge is firstly filtered by the sludge cake layer, and then the liquid is filtered and discharged;

s2, feeding at high pressure and low flow rate, wherein the feeding pressure is increased from 1.5MPa to 2.0MPa after 15-25min, feeding is carried out for 30-40min under the pressure of 2.0MPa, and the feeding amount reaches 20-30% of the total feeding amount;

s3, stopping feeding, and locking the plate frame;

s4, starting a squeezing hydraulic system, wherein the highest pressure reaches 2.5MPa and lasts for 1-2 h;

s5, finishing the filter pressing process, starting an air back blowing device, wherein the back blowing air pressure is not less than 0.8 MPa;

s6, opening the plate frame, and enabling the mud cakes to fall off automatically;

wherein the feed material is excess sludge of biochemical treatment of town sewage with the solid content of 18-22%, and the water content of the filter-pressed sludge cake is 38-45%.

Further, the sludge is pretreated before entering a cooling tank, and the pretreatment comprises mixed feeding, hot alkali reaction and material cooling;

further, in the material cooling step, a cooling tank is a material storage tank, the cooling tank is of a jacket type, flowing cold water is pumped in as a cooling source, and outlet water is cooled through a cooling tower and is recycled;

further, 30% of cooled materials are reserved in a cooling tank, the cooling temperature of the materials is below 60 ℃, and a stirrer is arranged in the cooling tank;

and furthermore, the top of the cooling tank is connected with a negative pressure system, the gas in the cooling tank is condensed, the negative pressure system comprises a vacuum pump, a buffer tank and a cooling tower, and the condensate flows back into the cooling tank.

Further, the mixed feeding comprises lime solution preparation and synchronous mixed feeding, wherein the lime solution preparation comprises the following steps: adding water into the lime dry powder, stirring and dissolving to form saturated lime liquid, wherein the using amount of the lime dry powder is 2.5-4.5% of the sludge amount; the synchronous mixing feeding is as follows: the method comprises the steps of synchronously feeding the sludge and the lime liquid in proportion, wherein the feeding mode is that a lime liquid delivery pump and a sludge delivery pump are started and delivered to a reaction kettle through a pipeline static mixer.

Further, the hot alkali reaction is specifically as follows: the method is characterized in that high-speed rotating mechanical force is directly acted on a mixture of the activated sludge and the lime, meanwhile, the mixture of the sludge and the lime forms hydraulic cyclone under the action of the high-speed rotating force, the cell walls of the activated sludge are damaged under the double actions of the high-speed rotating mechanical force and the hydraulic cyclone, and in the process, the activated sludge and the lime are subjected to thermokalite reaction for 40-60min at the reaction temperature of 110-130 ℃.

Further, the hot alkali reaction adopts a cold and hot material exchange mode for feeding, hot mud with the volume of 10-20% of the container is reserved in the reaction container, and the temperature of the hot mud is 110-.

Compared with the prior art, the invention forms the feeding characteristic of smoothly transiting from low pressure and large flow to high pressure and low flow by adjusting the feeding process; in the initial stage, a mud cake layer is quickly formed by low-pressure large-flow feeding, and solid particles fed are efficiently intercepted through the filtration of the mud cake layer; automatically transitioning to a high-pressure low-flow stage along with the improvement of the compactness of the mud cake and the increase of the filtration resistance; after the feeding is completed, further pressing is performed. The feeding time and the pressing time are both reduced by 30%, the solid content of the feeding sludge can be improved to 18-22%, the solid content is improved by about one time compared with the prior art, the water content of a mud cake obtained after filter pressing is as low as 38.5-45%, the content of volatile organic matters (VSS) is lower than 28%, the press filtrate is clear and rich in protein, the suspended solid concentration (SS) is 30mg/L, and compared with the suspended solid concentration in the conventional press filtrate in the prior art, the suspended solid concentration of the press filtrate obtained in the application is remarkably reduced, and the heavy metal content is remarkably reduced. The obtained pressure filtration liquid has the safety meeting various agricultural standards, can improve the biological and abiotic stress resistance of crops, improve the nutrient absorption capacity of plants, prevent the use of pesticides and fertilizers from being reduced by 30 percent in the planting process, and ensure the safety of agricultural production. In addition, the mud cake interception and filtration effect is obvious, the service life of the filter cloth can be prolonged, and the filter pressing cost is reduced.

Drawings

FIG. 1 is a structural view of a device for a filter-pressing process of a filter press according to the present application

FIG. 2 is a graph of feed pressure versus feed

FIG. 3 shows the cooled sludge

FIG. 4 shows the mud cake formed after filter pressing

FIG. 5 is a press filtrate

Reference numerals:

1. the system comprises a plate-and-frame filter press, 2 parts of a storage tank, 2 parts of 1 part of a cooling tower, 2 parts of a circulating water tank, 2 parts of 3 parts of a circulating pump, 3 parts of a high-pressure piston pump, 4 parts of an air reverse blowing device, 4 parts of 1 parts of a reverse blowing air storage tank, 4 parts of 2 parts of a screw air compressor, 4 parts of 3 parts of an instrument air storage tank, 4 parts of a cold dryer, 5 parts of a negative pressure system, 5 parts of 1 part of a buffer tank, 5 parts of 2 parts of a condenser, 5 parts of 3 parts of a vacuum pump.

Detailed Description

Examples

As shown in fig. 1, the plate-and-frame filter press 1 is driven by the high-pressure piston pump 3 to feed and is connected with the air back-blowing device 4, the feeding pressure and the flow are automatically adjusted according to the feeding state, the high-pressure piston pump 3 is connected with the storage tank 2, and the plate-and-frame filter press process is as follows:

s1, performing large-flow initial feeding, wherein a high-pressure piston pump is adopted for feeding driving, the feeding pressure and flow are automatically adjusted according to the feeding state, the feeding pressure is increased from 0 to 1.5MPa within 20min, the feeding amount reaches 70-80% of the total feeding amount, a plate frame sludge storage chamber is quickly filled with sludge to form a high-solid-content sludge cake layer, the sludge is firstly filtered by the sludge cake layer, and then the liquid is discharged by a filter cloth; along with continuous feeding, the mud cake layer is gradually compact, forms the filtration system of big resistance high entrapment, and the solid-liquid separation effect promotes more and more, and mud carries out preliminary filter-pressing in the feeding process.

S2, feeding at high pressure and low flow, wherein the feeding pressure is increased from 1.5MPa to 2.0MPa within 20min, feeding is carried out for 30-40min under the pressure of 2.0MPa, and the feeding amount reaches 20-30% of the total feeding amount; the feed pressure versus feed curve is shown in figure 2.

S3, stopping feeding, and locking the plate frame;

s4, starting a squeezing hydraulic system, wherein the highest pressure reaches 2.5MPa and lasts for 1-2 h;

s5, finishing the filter pressing process, starting an air back blowing device, wherein the back blowing air pressure is not less than 0.8 MPa;

s6, opening the plate frame, and enabling the mud cakes to fall off automatically; and (5) conveying, crushing and storing the mud cakes.

Wherein the feed material is excess sludge of biochemical treatment of town sewage with the solid content of 18-22%, and the water content of the filter-pressed sludge cake is 38-45%.

The mud cake formed after filter pressing in the embodiment is shown in fig. 4, as is apparent from fig. 4, the mud cake is obviously layered, the middle mud cake layer is a mud cake layer formed in a high-pressure low-flow feeding stage, the two sides of the mud cake layer are mud cake filtering layers formed in a high-flow initial feeding stage, the traditional filter cloth filtering is replaced by a high-resistance mud cake filtering mechanism, the solid particle interception efficiency is improved by 99.9%, the quality of filtrate is greatly improved, the suspended solid concentration of the filtrate is reduced to the maximum extent, the inorganic matter and heavy metal content of the liquid is reduced, meanwhile, the water content of the mud cake is ensured to be reduced to be below 45%, and the organic matter (VSS) content is not more than 28%. The press filtrate is clear and transparent, and is rich in protein, as shown in FIG. 5. In the pressure filtration liquid obtained by the pressure filtration process in the embodiment, the concentration of Suspended Solids (SS) is 30mg/L, and the concentration of suspended solids in the conventional pressure filtration liquid in the prior art is 226 mg/L.

In an alternative embodiment, as shown in FIG. 1, the blowback device 4 comprises a blowback air storage tank 4-1, a screw air compressor 4-2, an instrument air storage tank 4-3 and a cold dryer 4-4.

In an alternative embodiment, as shown in fig. 1, the plate-and-frame filter press 1 is connected to the storage tank 2 through a pipeline, and the pressure-filtered liquid in step S1 can flow back to the storage tank 2 for reuse, so as to: at large-traffic low pressure feeding initial stage, the mud cake filter layer forms fast, but the density is not enough, can produce a small amount of initial liquid of holding back the filtration not thorough, its suspension solid concentration is slightly high, probably not conform to the requirement and abandonment is discharged, so during the pressure filtrate backward flow to storage tank 2 that produces this stage, can utilize the low temperature of pressure filtrate this moment to cool off the mud in the storage tank 2 on the one hand, on the other hand can further reduce the suspension solid concentration of final pressure filtrate, can avoid producing high concentration sewage, reduce sewage treatment's demand.

In an alternative embodiment, the sludge is pretreated before entering the storage tank 2, and the pretreatment comprises mixed feeding, hot alkali reaction and material cooling;

in the material cooling step, as shown in fig. 1, a storage tank 2 is a cooling tank, the cooling tank is a jacket type, flowing cold water is pumped in as a cooling source, clear water enters a circulating water tank 2-2, water is circulated through a circulating pump 2-3, and discharged water is cooled through a cooling tower 2-1 and is recycled; the temperature of the sludge after the thermokalite reaction is reduced from 110 ℃ to below 60 ℃ after the sludge is introduced into the cooling tank, the fluidity of the sludge is greatly improved, the solid content can be improved to 20%, the cooled sludge still keeps high fluidity under the condition that the solid content is as high as 20% as shown in figure 3, and good basic conditions are provided for improving the sludge filter-pressing efficiency and reducing the water content of sludge cakes, so that the sludge with high solid content can be subjected to high-efficiency filter-pressing.

In an alternative embodiment, 30% of cooled sludge is reserved in the cooling tank, the cooling temperature of the sludge is below 60 ℃, and a stirrer is arranged in the cooling tank to mix cold and hot sludge and accelerate the reduction of the temperature of the sludge;

in an alternative embodiment, as shown in fig. 1, the top of the cooling tank is connected with a negative pressure system 5, and the gas in the cooling tank is condensed, wherein the negative pressure system 5 comprises a vacuum pump 5-3, a buffer tank 5-1 and a cooling tower 5-2; the gas enters a cooling tower 5-2 for condensation, and the condensate flows back to the cooling tank.

In an alternative embodiment, the mixed feed includes a lime dissolving solution preparation and a simultaneous mixed feed, the lime dissolving solution preparation being: adding water into the lime dry powder, stirring and dissolving to form saturated lime liquid, wherein the using amount of the lime dry powder is 2.5-4.5% of the sludge amount; the synchronous mixing feeding is as follows: the method comprises the steps of synchronously feeding the sludge and the lime liquid in proportion, wherein the feeding mode is that a lime liquid delivery pump and a sludge delivery pump are started and delivered to a reaction kettle through a pipeline static mixer.

In an alternative embodiment, the hot base reaction is specifically: the method is characterized in that high-speed rotating mechanical force is directly acted on a mixture of the activated sludge and the lime, meanwhile, the mixture of the sludge and the lime forms hydraulic cyclone under the action of the high-speed rotating force, the cell walls of the activated sludge are damaged under the double actions of the high-speed rotating mechanical force and the hydraulic cyclone, in the process, the activated sludge and the lime are subjected to thermokalite reaction to obtain hot slurry, the reaction time is 40-60min, and the reaction temperature is 110-130 ℃.

In an alternative embodiment, the hot alkali reaction is carried out by adopting a cold-hot material exchange mode, hot mud with the volume of 10-20% of the container is reserved in the reaction container, and the temperature of the hot mud is 110-.

The device and the using method adopted by the mixed feeding and the thermokalite reaction in the pretreatment can be specifically disclosed by the invention patent with the publication number of CN111547975A and the invention name of the invention of the method for separating the activated sludge biomass by high-speed mechanical cyclone.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention. Furthermore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the description of the present invention, reference to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.