JPH0239287B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method and apparatus for concentrating and dehydrating a slurry stock solution, which has extremely high operational efficiency and allows easy adjustment of the degree of concentration compared to conventional methods and devices for concentrating slurry stock solution, such as sludge water. When treating industrial wastewater in general industry, or treating water in sewers, water supplies, etc., a large amount of slurry-like sludge water is generated, and this sludge water often causes secondary pollution, so it is concentrated at least to the legally regulated value. It is necessary to dehydrate and reduce its volume.
In other words, when reducing the volume in the treatment of sludge, the currently common methods are to concentrate the sludge to near the liquid limit using a centrifugal separator after natural gravity settling in a thickening tank, or to There is a method of condensing using a chemical such as a molecular flocculant, and volume reduction is performed by such a method. By the way, methods using centrifuges and the like not only require high initial equipment costs, but also have high running costs such as power consumption during operation and maintenance, and furthermore require countermeasures against secondary pollution due to noise, vibration, etc. Furthermore, the method of using chemicals has the disadvantage that the running cost of the chemicals is high and secondary pollution countermeasures due to chemical injection are required. Further, it is generally widely practiced to concentrate and dehydrate not only sludge water but also slurry stock solution by overaction of cloth. However, when over-concentrating with a cloth, the concentrate adheres and accumulates on the surface of the cloth, so the concentration of the concentrate after over-dehydration becomes uneven as the operating time passes, and if you want to obtain a concentrate with a constant concentration, In addition, the concentrate adhering to the cloth surface exhibits a very large overresistance, resulting in a significant decrease in overcapacity and requiring a long time for concentration and dehydration. arise. The present invention was made in view of the above-mentioned actual situation and the various drawbacks of conventional concentration dehydration methods, and includes:
Basically, a scraping blade that is arranged almost vertically and revolves around the inside surface of the cloth tube in the form of a hose is used to constantly scrape off the concentrate adhering to the inside surface of the cloth tube, thereby increasing the over-performance of the cloth tube. At the same time, the stirring action eliminates the concentration gradient in the radial direction between the surface and center of the cloth tube, and creates a concentration gradient in the vertical direction with the maximum concentration in the lower part of the cloth tube. The purpose is to obtain a concentrate of uniform concentration continuously or intermittently from the lower part of the cloth tube. That is, the invention is a method for achieving the above object, in which a cloth tube having an upper supply end and a lower discharge end connected to a discharge valve is arranged almost vertically, and the slurry stock solution is fed into the cloth tube from the supply end. The liquid is discharged through the entire surface of the cloth tube, and the concentrate adhering to the inner surface of the cloth tube is removed by revolving a scraping blade in contact with the inner surface over almost the entire length of the cloth tube. A concentration gradient having a maximum concentration is formed on the discharge end side of the cloth cylinder by continuous scraping and sedimentation, and the rotational torque of the revolving scraping blade increases over time based on the increase in the maximum concentration over time. Detection is performed by a detection mechanism, and when the detected torque reaches a predetermined value, a valve opening/closing control mechanism is activated based on the predetermined value to open the discharge valve, thereby discharging concentrate of a predetermined concentration. The apparatus invention for carrying out the above-mentioned method invention is characterized in that the upper supply end is connected in communication with the slurry stock solution supply tank, and the lower discharge end is connected in communication with a funnel pipe with a discharge valve, so that the apparatus is almost vertically connected. A cloth tube disposed on the cloth tube, a concentrate scraping blade disposed so as to be able to revolve in contact with the inner surface of the cloth tube over almost the entire length thereof, and a drive mechanism for revolving the scraping blade. and a rotational torque detection mechanism for a scraping blade attached to the drive mechanism, and a discharge valve opening/closing control mechanism for controlling opening and closing of the discharge valve based on detection of a predetermined torque value by the rotational torque detection mechanism. It is characterized by this. DESCRIPTION OF THE PREFERRED EMBODIMENTS The principles of the present invention and some specific devices for carrying out the present invention will be described in detail below with reference to the drawings. Figures 1 and 2 show an outline of a super-dehydration device that performs superconcentration using only natural gravity based on the present invention. The lower discharge end thereof is connected in communication with a funnel pipe 3 having a discharge valve 4 and is fixedly arranged substantially vertically. In the supply tank 2,
The slurry stock solution is supplied from the slurry stock tank 14 through the pipe line 17 by driving the pump 15 and opening the valve 16 . The slurry stock solution is filled in a cloth tube 1 and a supply tank 2, and overflows in the supply tank 2 so as to maintain a constant water level. It's getting old. A drive shaft 6 that is rotatably driven by a motor 7 via a drive pulley 8 is disposed in the center of the cloth tube 1, and the drive shaft 6 includes an upper support member 6 ₁ , a lower support member 6 ₂ , and a center position holding member. A member 6 ₃ is integrally fixed, and the center position holding member 6 ₃ is provided at such a position that it lightly contacts the conical inner surface of the funnel tube 3 . In addition, each of the upper and lower support members 6
₁ and 6 ₂ are approximately equal to the diameter of the cloth tube 1, and the supporting portion 6
Scraping blades 5, 5 are provided which vertically connect the radial ends of the tubes ₁ , 6, ₂ , and contact the inner surface of the cloth tube 1 over almost the entire length thereof. The motor 7, drive pulley 8, and drive shaft 6
constitutes a drive mechanism for rotating the scraping blades 5, 5 in contact with the inner surface of the cloth tube 1 at a slow speed of, for example, about 0.1 to 10 times per minute. To explain the concentration and dehydration effect of the above configuration, the slurry stock solution filled in the cloth tube 1 is
The water head causes the liquid to be discharged through the entire surface of the cloth tube 1, and the liquid is received by the liquid recovery tank 13 and recovered through the pipe line 19. On the other hand, concentrates adhere to and accumulate on the inner surface of the cloth tube (1), but the concentrates are constantly scraped off by the scraping blade that revolves in contact with the inner surface of the cloth tube (1). It sinks to the lower discharge end of 1. At this time, the scraping blades 5, 5 exert a stirring action on the slurry stock solution, so
Although the concentration gradient in the radial direction between the surface and center of the cloth tube is relatively small, a concentration gradient with the maximum concentration is formed in the lower portion in the vertical direction of the cloth tube. The cloth tube 1 is a hose-shaped thing made of chemical fiber similar to that used in filter presses, and the degree of stirring action and the size of the maximum water head depend on the diameter and length of the cloth tube. Since the diameter is different, the concentration and dehydration ability will also be slightly different, but the thinner and longer the diameter, the more remarkable the difference in the degree of concentration in the vertical direction becomes. Generally, cloth tubes have a diameter of 100mmφ to 300mm.
A φ length of about 1 m to 2 m is suitable. Furthermore, in order to increase the processing capacity, as shown in FIG. 3, a large number of cloth cylinders 1, 1, . Further, in the present concentration and dehydration apparatus, as shown in FIG. 4, the slurry stock solution supply tank 32 can be a pressurized type supply tank with a closed structure. That is, the slurry stock solution is once put into the pressure tank 33 from the slurry stock solution tank 14 by the pump 15, and then transferred to the compressor 31.
By this operation, the pressure is supplied into the pressurized supply tank 32. This pressurized state is useful for increasing the overpressure and increasing the water removal rate, and the pressurizing force can be arbitrarily selected depending on the concentration of the slurry stock solution and the concentration of the target concentrate, but is usually 5 kg. / ^cm2 ~10
Approximately Kg/ ^cm2 is appropriate. In the embodiment device shown in FIGS. 1 to 4,
As mentioned above, the concentrate has reached its maximum concentration at the lower discharge end side of the cloth tube 1, and in all embodiments, the concentrate is taken out by opening the discharge valve 4, and the concentrate is taken out from the concentrate receiving tank. It is accommodated in 12.
In this case, the discharge valve 4 can be opened and closed manually to discharge the concentrate of a desired concentration to the receiving tank 12 continuously or intermittently at an appropriate frequency. However, as the slurry stock solution is concentrated in the cloth tube 1, its viscosity changes and its viscous resistance increases, so the driving torque for rotating the scraping blade 5 also increases as the concentration progresses. Become. Therefore, in the present invention, for example, a torque detector 9 is attached to the drive shaft 6 to detect the rotational torque, and when the torque is detected at a predetermined value, the valve opening/closing controller 11 is connected to the circuit 20 and the torque setting device 10. A signal is sent to the exhaust valve 4, and the opening and closing of the discharge valve 4 is controlled based on the signal. The torque detector 9, the torque setting device 10, and the valve opening/closing controller 11 collectively constitute a discharge valve opening/closing control mechanism for controlling the opening and closing of the discharge valve 4, and by providing the control mechanism, a desired constant concentration can be achieved. Concentrates can be withdrawn continuously or intermittently. Generally, the most efficient concentration operation for a slurry stock solution is to concentrate it to near the liquid limit, but it is extremely difficult to control this concentration, and conventionally this has been done based on the experience and intuition of the operator. In particular, when the concentration of the slurry stock solution changes, the amount of water removed by filtration changes, making it extremely difficult to maintain a constant concentration level of the concentrate. However, when using the method and apparatus of the present invention equipped with a discharge valve opening/closing control mechanism, a torque value corresponding to a desired concentration level is set in a torque setting device, and a torque value detected by a torque detector is set in advance. Based on this relationship, it is possible to control the opening and closing of the discharge valve to obtain a concentrate with a desired concentration. Furthermore, according to the apparatus of the above embodiment, even when the concentrate is discharged intermittently, the operation is close to continuous operation, and it is possible to perform automatic and continuous operation instead of conventional concentration by filtration, which was mainly batch operation (batch processing). The process can be changed to a very simple process of continuous operation, and the operations that conventionally relied on experience and intuition can be eliminated, and high-quality concentrates can be obtained. Although it is possible to control the amount of concentrate discharged from the discharge valve by setting the opening degree of the valve, in general, depending on the concentration of the supplied slurry stock solution, it passes through the cloth cylinder in an unconcentrated state. In this case, it is better to open and close the discharge valve intermittently to achieve a normal operating state. This is because the intermittent discharge allows only the highly concentrated portion at the lower discharge end of the cloth tube to be drawn out.
Note that when carrying out the present invention, in particular when a pressurized supply tank is used, excessive dehydration is further promoted, so automatic batch operation is also possible. In the case of batch operation, when a predetermined torque is detected, the supply pump 1
5 and open the discharge valve 4 to discharge the entire amount of concentrate in the cloth tube 1. The scraping blade used in the embodiment device described above is provided so as to be able to revolve around the inner surface of the cloth tube arranged almost vertically over almost the entire length thereof, but the point is that the scraping blade Any material may be used as long as it scrapes off the concentrate adhering to the inner surface of the cloth cylinder, and any material such as metal or hard rubber can be used. FIGS. 5 to 7 show some modifications of the scraping blade. The scraping blade ₅₁ shown in FIG. It is a fixed blade with reduced friction, and the scraping blade ₅₂ shown in FIG.
This is a rolling type blade designed to further reduce the friction and drive torque. Furthermore, the scraping blade ₅₃ shown in FIGS. 7A and 7B is a band-shaped spiral blade that has the function of pushing the concentrate downwards in the cloth tube according to the direction of rotation thereof. In the example device shown in Fig. 1, a cloth tube with a diameter of 150 mm and a length of 1.0 mH was used, and sludge water with a concentration of 3.1% obtained from a coagulation and sedimentation tank at a water treatment plant was supplied as the object to be treated. Take the blade 3r.
Table 1 shows the experimental results when the spacecraft revolved at pm and the opening time of the discharge valve with a diameter of 25 Å was set to 1 sec each time.
Note that the valve opening/closing frequency indicates the number of times the valve is opened/closed per hour.

[Table] Furthermore, when the above experimental apparatus was compared with centrifugal separation having the same throughput, the results shown in Table 2 were obtained.

[Table] As you can see from Table 2, the power consumption ratio is: Concentrator/centrifuge = 57.6/532.1 = 1/9.23 = 10.
8%, while the initial equipment cost is 30% lower than that for a centrifuge.
A reduction of more than % was achieved. As is clear from the above detailed description, according to the present invention, the concentrate adhering to the inner surface of the cloth cylinder is constantly renewed by the revolving scraping blade, and there is no deterioration in overfunction, so that moisture is removed. It has excellent removal ability and has the advantage of shortening the concentration time and making it possible to downsize the device. Further, according to the present invention, as the concentration progresses,
We provide a high-performance automatic concentrator that can control the concentration by utilizing the increase in viscosity of the concentrate inside the cloth tube, detecting the driving torque against viscous resistance, and controlling the frequency of opening and closing of the discharge valve. Ru.
Moreover, the device of the present invention consumes less energy when concentrating by filtration, and because the number of revolutions of the scraping blade is low, the power consumption of the drive motor is also small, which is about one-tenth that of conventional centrifuges. This contributes to energy saving in the concentration operation, and since the surface of the cloth tube is scraped, it has various advantages such as being able to be used for a long period of time without having to wash the cloth.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing a first embodiment of the slurry stock solution concentration and dehydration apparatus according to the present invention, and FIG.
3 is a partially cutaway side sectional view of the second embodiment of the present invention using a plurality of cloth tubes; FIG.
The figure is a partially cutaway side sectional view of a third embodiment of the present invention in which the slurry stock solution supply tank is a sealed pressurized supply tank, and Figures 5 to 7 A and B are respectively the scraping blades of the present invention. It is a side view which shows the modification of . 1...Cloth tube, 2...Slurry stock solution supply tank, 3
... Funnel pipe, 4 ... Discharge valve, 5 ... Scraping blade, 6 ... Drive shaft, 7 ... Motor, 8 ... Drive pulley, 9 ... Torque detector, 10 ... Torque setting device, 11 ...Valve opening/closing controller, 12...Concentrate receiving tank, 13...Liquid recovery tank.

Claims (1)

[Scope of Claims] 1. A cloth tube having an upper supply end and a lower discharge end connected to a discharge valve is disposed almost vertically, a slurry stock solution is supplied from the supply end into the cloth tube, and the cloth tube is The liquid is discharged through the entire surface of the cloth tube, and a scraping blade in contact with the inner surface of the cloth tube is revolved over almost the entire length of the cloth tube to continuously scrape off and settle the concentrate adhering to the inner surface of the cloth tube, forming a concentration gradient having a maximum concentration on the discharge end side of the cloth tube, and detecting an increase over time in the rotational torque of the revolving scraping blade based on the increase over time in the maximum concentration using a torque detection mechanism; When the detected torque reaches a predetermined value, a valve opening/closing control mechanism is activated based on the predetermined value to open the discharge valve, thereby discharging a concentrate having a predetermined concentration. Concentration dehydration method. 2. The slurry stock solution concentration and dehydration method according to claim 1, wherein the slurry stock solution is supplied under pressure into the cloth cylinder. 3. A cloth cylinder arranged almost vertically with its upper supply end connected to the slurry stock solution supply tank and its lower discharge end connected to a funnel pipe with a discharge valve, and its inner surface over almost the entire length of the cloth cylinder. a concentrate scraping blade arranged to be able to revolve in contact with the concentrate, a drive mechanism for revolving the scraping blade, a rotational torque detection mechanism for the scraping blade attached to the drive mechanism, and the rotational torque. A slurry stock solution concentration and dehydration apparatus comprising: a discharge valve opening/closing control mechanism for controlling opening/closing of the discharge valve based on detection of a predetermined torque value by a detection mechanism. 4. The slurry stock solution concentrating and dehydrating apparatus according to claim 3, wherein a plurality of the cloth tubes according to the preceding clause are arranged in parallel and connected to a common slurry stock solution supply tank. 5. The slurry stock solution concentration and dehydration apparatus according to claim 3 or 4, wherein the slurry stock solution supply tank in claim 3 or 4 is a sealed pressurized supply tank. 6. The scraping blade according to claim 3 or 4 is a fixed blade having a rounded part in contact with the inner surface of the cloth cylinder. Slurry stock solution concentration dehydration equipment. 7. The scraping blade in claim 3 or 4 is a rolling blade whose contact portion with the inner surface of the cloth cylinder is in the form of a freely rotatable roller. The slurry stock solution concentration and dehydration device according to item 4. 8. The slurry stock solution concentrating and dehydrating apparatus according to claim 3 or 4, wherein the scraping blade in claim 3 or 4 is a band-like spiral blade.