JPS6336300B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for separating and recovering solids, etc., which efficiently separates solids mixed in a liquid by centrifugal force and recovers only the solids, which is more systematic than conventional methods. The purpose of this project is to simplify the single tank and dramatically improve the recovery efficiency and properties of the recovered solids. More specifically, when treating sewage containing organic matter, sand, etc., the present invention uses a liquid cyclone to separate solids, and stores the solids in a separation storage tank that is directly connected to the liquid cyclone at the bottom of the cyclone. Solids are stored, bubbling air sucked from the atmosphere by the negative pressure in the separation storage tank is introduced into the separation storage tank, the separated solids are washed, the washed and separated solids are dehydrated, and the system The purpose of this system is to improve the efficiency of collecting solids, to wash solids, and to continuously separate and collect solids by reducing the underflow flow rate of the liquid cyclone to zero. The method is simple and provides a continuous method for separating, washing and recovering solids in a wide range of liquids. A conventional method for removing sand from sludge and the like will be explained with reference to FIG. FIG. 1 is an explanatory diagram of the system of the sludge removal device. In the figure, 1 is a hydrocyclone, which has the function of separating sludge and sand by centrifugal force. 2 is an inlet pipe for sludge containing sand from which large impurities such as wood chips and metals have been removed, that is, raw sludge from which the sand content is to be removed. The inflow Q ₂ from the inlet pipe 2 is separated and classified into sand and mud by centrifugal acceleration inside the hydrocyclone 1 , and the mud with lower specific gravity flows out from the upper outlet pipe 3 of the hydrocyclone 1 . flow Q ₃
and is discharged to the next process outside the system. On the other hand, the sand with high specific gravity becomes an inflow flow _Q4 from the lower outlet pipe 4 of the hydrocyclone 1 and flows into the undertrough 5.
It will be collected at This undertrough 5 has the function of re-sedimenting and separating the mud and sand contained in the lower outflow stream Q ₄ , but the mud is transferred from the upper outlet pipe 7 of the undertrough 5 to the outflow stream Q ₇ . Then, it is returned to the place where the mud quality is almost the same as the previous process, that is, the inflow stream _Q2 . On the other hand, the sand that has settled in the undertrough 5 is transferred by the sand transport conveyor 6, and although there are differences depending on the operating specifications of the conveyor 6, a certain degree of dewatering function is activated due to the potential energy of the slope. The sand is collected as recovered sand S from a discharge port 8 provided at the top of the conveyor 6. The above is an example of a conventional method for separating and recovering sand from sludge containing sand as a solid substance, but the problems in this case will be described below. A typical treatment result of a test using the method described above using sludge drawn from a settling tank at a certain treatment plant in Tokyo shows that when using a hydrocyclone 1 with a cylindrical diameter D ₁ of 152 mm (6 inches), The 50% separation limit particle diameter _d50 was approximately 140 (μm), and the sand recovery rate of the hydrocyclone 1 was 79.4%, which was relatively satisfactory. However, this 79.4% sand content and upper runoff flow _Q3
The mud other than the bottom flow of cyclone 1 is Q ₄
Therefore, depending on the area and capacity of the undertrough 5, the inside of the trough may be disturbed, and the desired sedimentation separation may not necessarily take place, making it impossible to obtain a satisfactory result. Test results similar to those above show that undertrough 5
Since the sand recovery rate in hydrocyclone 1 is as low as 54.6%, even if the sand recovery rate in hydrocyclone 1 is relatively satisfactory at 79.4%, the entire system, that is, the amount of sand recovered as recovered sand S, is For the sand content flowing into hydrocyclone 1 by minute Q ₂
The amount of sand recovered is less than half of 79.4% x 54.6% = 43.4%, which is extremely low and it is difficult to say that the recovered sand is of good quality. Furthermore, the upper outflow of undertrough 5
_Q7 is approximately equal to the bottom outflow of cyclone 1 _Q4 , which returns to the previous process, so
The processing capacity increases due to repetition, which causes problems in terms of energy and when the equipment becomes larger. As mentioned above, in the conventional method of separating and recovering solids using a liquid cyclone, although the liquid cyclone has a high solids recovery rate, the recovery rate of solids is low in the separation and discharge method or device for the separated and recovered solids. As a result, the solids recovery rate for the entire system is low at less than 50%. Therefore, the repeated processing amount is 10 to 20 times per hydrocyclone inlet flow.
%, and in large-scale sludge treatment, there is an energy problem, and it is undesirable to increase the size of the equipment because it becomes complicated. Furthermore, there are inherent problems such as the inability to obtain recovered solids of good quality, and a method for separating and recovering solids has been desired to solve these problems. The present invention was made in order to solve the problems of the conventional method as described above, and uses a liquid cyclone to recover high quality solids at a high recovery rate and solids etc. suitable for large-scale processing. This provides a separation and recovery method for The present invention provides a method for separating and recovering solids using a device in which a lower outlet of a hydrocyclone, a separated material storage tank, and a separating and discharging means are connected in an airtight manner. By adjusting the inlet inflow pressure and inlet velocity of the liquid cyclone, the liquid cyclone is provided at a higher position than the separated product storage tank, so that the pressure in the separated product storage tank is made negative, and the negative pressure energy is used to separate and discharge the liquid cyclone. A method for separating and recovering solids, etc., characterized in that air is sucked into the separated product storage tank from the water level of the tank, the solids in the separated product storage tank are washed, and the solid separated products are discharged by the discharge means. It is. The present invention will be described below based on explanatory drawings that are examples of embodiments of the present invention. FIG. 2 is an explanatory diagram of the principle of the method of the present invention. Note that parts having the same functions as those in FIG. 1 are indicated by the same reference numerals, and explanations thereof will be omitted. The structural features of the present invention are:
The volume and shape of the undertrough 5 shown in the conventional device shown in FIG. 1 are changed and the undertrough 5 is directly connected to the hydrocyclone 1 in an airtight manner, so that only the sand separated and classified by the hydrocyclone 1 is deposited in a separated storage tank. 9
(hereinafter referred to as storage tank 9) is provided in an airtight manner. When operating a general hydrocyclone, the pressure of the inflow from the inlet pipe of the hydrocyclone is 1
~2 (Kg/cm ² ) is normal. Now, when the separator of the present invention shown in FIG. 2 is operated, the fluid flows out only from the upper outlet pipe 3 of the hydrocyclone 1. There is also a concern that the gauge pressure of the pressure gauge 10 provided in the inlet pipe 2 of the hydrocyclone 1 may be approximately the same as the gauge pressure. However, as a result of research focusing on the flow state of the fluid inside the hydrocyclone 1, the present inventors found that even under normal conditions, this flow forms a super turbulent vortex, and the center of the vortex flow field is in a vacuum state. Therefore, it was found that by adjusting the inlet inflow pressure and inlet velocity determined by the shape of the hydrocyclone 1 to certain conditions, it is possible to bring the pressure inside the storage tank 9 into the negative pressure range. I learned. In this case, the fluid flows between the hydrocyclone 1 and the storage tank 9.
It descends while performing a vortex motion near the wall surface of the liquid cyclone 1, reaches the lower end, then rises near the center, and is discharged from the upper outlet 3 of the hydrocyclone 1 to the outside of the system. Based on the above premise, the inventors conducted a water test using the apparatus according to the present invention shown in FIG. We have found a special configuration and operating conditions that bring the pressure inside the storage tank 9 into a negative pressure range. That is, according to the test results, the diameter D ₁ of the cylindrical part of the hydrocyclone 1 is 380 mm (15 inches), the diameter D ₂ of the inlet pipe 2 is 107 mm, and the diameter D ₃ of the upper outlet pipe 3 is 115 mm.
mm, and when the diameter D ₄ of the lower outlet pipe 4 is 60 mm, when the inlet speed of the hydrocyclone 1 is 5.6 m/sec and the inflow pressure is 2.01 Kg/cm ² , the gauge pressure in the storage tank 9 is -0.90 Kg/cm 2 It was found that a value close to a vacuum of cm ² was obtained, and that the pressure inside this storage tank 9 could be set and adjusted within a certain range. Based on the above results, the inventors developed the principle configuration shown in Figure 2 in order to conduct a practical test of the method of the present invention, and used the above-mentioned hydrocyclone to enable continuous operation. , Separate storage tank volume 135
An example device as shown in FIG. 3 in which the height H of the recovered sand outlet is 2 m was completed and tested. Note that the parts indicated by numerals 1 to 8 in Fig. 3 are the same as those shown in Figs. 1 and 2, and are the same as those shown in Figs. Height H to discharge port 8
has been newly added. If the test results for the device shown in FIG. 2 are applied to the device shown in FIG. 3, the water level 12 in the sand conveyor 6 can be set at an appropriate position within a certain range depending on the magnitude of the negative pressure in the storage tank 9. It is possible to do so. In addition, since the outlet 8 is provided at a position higher than the water level 12 that balances the negative pressure force in the storage tank 9, no water can be ejected from the upper outlet 8 of the sand conveyor 6. Instead, only the dehydrated sand can be recovered. Compared to the conventional device described in Figure 1, this method dramatically improves the sand recovery rate of the entire system, and most of the mud separated from the sand is transferred to the outflow of the hydrocyclone 1. _This is revolutionary because it is able to reduce the undertrough upper part flow Q ₇ to zero in the conventional method shown in Fig. . Furthermore, in the present invention, when the device is operated under conditions that increase the negative pressure in the storage tank 9, this negative pressure is utilized to increase the height H of the discharge port 8 of the sand discharge conveyor 6 to be higher than the separated product storage tank 9. By providing a water seal at the position, the air in the sand discharge conveyor 6 can be sucked in from the water level surface 12 in the sand discharge conveyor 6 and introduced into the lower part of the separated material storage tank 9. Due to this air mixture, the sand separated and classified by the liquid cyclone 1 and stored in the storage tank 9 is bubbled,
When the sand particles collide with each other, the organic matter adhering to the sand particles is washed away. As a result, the concentration of organic matter in the recovered sand S is reduced, the water content is lowered, and the odor is reduced, making post-treatment of the recovered sand S easier, and washing with secondary treated water, etc. Since the sand process is labor-saving or simplified, a comprehensive sand washing system including a sand washing process can be realized. According to the results of Example 1 described later, when the pressure inside the storage tank is -0.04 Kg/cm ² and the air intake amount is 1.10 Nm ³ /min, the sand recovery rate is 87.3% and the organic matter removal rate is 73.3.
% of good sales. In addition to the above-mentioned sludge removal, the method of the present invention can be used as a substitute for sewage and rainwater settling basins in sewage treatment plants or pump stations, and for subsequent slurry removal in various slurry transportation fields such as construction and civil engineering. can also be used. Next, an example will be described. Example 1 Sludge from a certain treatment plant in Tokyo (organic matter concentration 24.5%,
A processing test was carried out using the apparatus shown in FIG. 3 to obtain the test deposits shown in Table 1. Note that the device specifications in this case are as follows. Hydrocyclone Cylindrical diameter (D ₁ ) 380 mm (15 inches) Inlet pipe diameter (D ₂ ) 107 mm Upper outlet pipe diameter (D ₃ ) 115 mm Lower outlet pipe diameter (D ₄ ) 60 mm Separate storage tank Capacity 135 Example 2 Sewage The sand mixed in the sewage from the treatment plant is mixed with secondary treated sewage water and adjusted to the same sand concentration as the inflowing sewage (organic matter concentration 50%, sand 3.8g/total solids 0.2%). The test was conducted using the same equipment as in Example 1 as the influent raw water. The results are shown in Table 1. As shown in Table 1, the sand recovery rate and the removal rate of organic matter concentration were high, and the moisture content of the recovered sand was low, and the recovered sand was of good quality and could be reused as sand for settling basins at sewage treatment plants.

【table】

[Table] As detailed above, the method of the present invention solves all the problems of the conventional separation and recovery method of solids using a liquid cyclone, and because the system is simple, it is possible to process a large amount. It is meant to be. In addition, according to the present invention, since organic matter can be effectively removed from recovered sand in sewage treatment, etc., it has great practical effects, such as reducing offensive odors and greatly expanding the scope of use of recovered sand. be.

[Brief explanation of the drawing]

FIG. 1 is a system explanatory diagram of a conventional sludge and sand removal apparatus, FIG. 2 is an explanatory diagram of the principle of the present invention, and FIG. 3 is a system explanatory diagram of an embodiment of the present invention. 1...Liquid cyclone, 2...Inlet pipe, 3...
Upper outlet pipe, 4...Lower outlet pipe, 6...Sand conveyor, 8...Discharge port, 9...Separated material storage tank, 12...Water level.

Claims (1)

[Scope of Claims] 1. A method for separating and recovering solids using a device in which a lower outlet of a hydrocyclone, a separated material storage tank, and a separating and discharging means are connected in an airtight manner, comprising: By providing an outlet at a higher position than the separated product storage tank and adjusting the inlet inflow pressure and inlet velocity of the hydrocyclone, the pressure in the separated product storage tank is made negative, and the negative pressure energy causes the A method for discharging solid substances, etc., characterized in that air is sucked into the separated substance storage tank from the water level of the separation and discharge means, the solid substances in the separated substance storage tank are washed, and the solid separated substances are discharged by the discharge means. Separation and recovery method.