Oil and sludge recovery tank

Abstract

[Problem] To provide an oil and sludge recovery tank that can be installed on-site at a food factory or the like that discharges oil-containing wastewater and can recover oil and sludge from the oil-containing wastewater while reducing activity that involves the opening of a lid and the associated release of odors as much as possible. [Solution] An oil and sludge recovery tank according to the present invention comprises an oil extraction valve OV that is provided on a bottom surface side of a side surface of the oil and sludge recovery tank, a waste solid removal body 4 that is formed from three quadrangular prism–shaped waste solid removal plates 4a–4c that are erected on a bottom surface of the oil and sludge recovery tank so as to form a U shape as seen from above, and a suction space AS that is surrounded by the side surface and the waste solid removal body 4 and is for suctioning oil retained in the oil and sludge recovery tank through the oil extraction valve OV.

Description

Oil and sludge collection tank

[0001] The present invention relates to an oil and sludge recovery tank for recovering oil and sludge that can be reused as an energy source from oil-containing wastewater, which is a biomass resource discharged from food factories and commercial facilities.

[0002] Wastewater from food factories and other manufacturing plants contains various water pollutants (oils). If such wastewater is discharged without any treatment, the oils in the wastewater will adhere to and solidify in drainage pipes, causing blockages. This makes it difficult to purify the water in combined treatment tanks or sewage treatment plants, has a negative impact on the environment, and may result in legal restrictions that prevent businesses from continuing operations. Therefore, various methods and devices have been proposed for treating wastewater containing solids such as oils, sediments, and suspended matter at each facility where it is discharged.

[0003] One such method involves pooling oil-containing wastewater in a large tank such as an oil-water separator or raw water tank, periodically pumping out the large amount of floating oil and fat in the upper layer, and then adsorbing it with an adsorbent and filtering it, thereby physically removing the oil and other substances from the wastewater.

[0004] On the other hand, wastewater from commercial facilities such as restaurants, fast food establishments, restaurants, and hotels also contains various water pollutants. If such wastewater is discharged without any treatment, the oil and other substances in the wastewater will adhere to and solidify in drainpipes, causing blockages, making it difficult to purify the water in combined treatment tanks and sewage treatment plants, and also having a negative impact on the environment. Therefore, businesses that discharge wastewater containing solids such as oil, sediment, and suspended matter are equipped with treatment devices (grease traps, oil-water separators, raw water tanks) on a per-business basis, where the wastewater is temporarily pooled, allowing solids to settle and oil to float, and then periodically removing these substances through physical removal treatment.

[0005] Incidentally, for example, a simple device has been disclosed that selectively separates and removes waste solids and the like contained in waste oil collected from small-scale businesses that discharge waste oil and waste solid-containing wastewater, and transfers only the waste oil to a separate container for transportation and storage (see, for example, Patent Document 1). Also disclosed is an oil and sludge recovery tank for more efficiently recovering oil and sludge from the upper layer of an oil-water separation tank that pools oil-containing wastewater (see, for example, Patent Document 2).

[0006] Patent No. 5452814 Patent No. 7255941

[0007] However, the methods and devices for temporarily pooling oil-containing wastewater in large tanks such as oil-water separators and periodically pumping it out for treatment, as well as the methods and devices for extracting oil-containing wastewater from grease traps, require the lid of the device to be left open during operation, which results in the generation of a foul odor from the wastewater during operation, causing problems.

[0008] Furthermore, the conventional methods still require the periodic manual recovery of sludge remaining in large tanks such as oil-water separators and grease traps. For this reason, no device or tank has yet been developed that can automatically recover oil and sludge from oil-containing wastewater that can be reused as an energy source, without the need for manual work involving opening the lid.

[0009] Furthermore, the oil recovered from the oil-water separator or grease trap has excess debris removed in a refinement and transfer device before being stored in a refined oil tank, etc. However, the refinement and transfer device must be set up and put away at the site where the oil and sludge are recovered, which creates a workload.

[0010] Furthermore, in recent years, the problem of global warming has become more serious, and renewable energy that reuses waste has attracted attention. The amount of wastewater and fats, which are biomass resources, discharged from food factories and other sources amounts to more than 300,000 tons per year throughout Japan, and the amount is even greater when considering the entire world. For this reason, there is an urgent need to establish equipment and technology that can efficiently and automatically recover recyclable oil from wastewater and fats discharged from food factories and other sources.

[0011] The present invention has been made in view of the above-mentioned problems, and aims to provide an oil and sludge recovery tank that can be installed on-site at food factories, commercial facilities, etc. that discharge oil-containing wastewater, and that can recover oil and sludge from oil-containing wastewater while minimizing the need to open the lid, which causes bad odors. It is also an object of the present invention to provide an oil recovery system that utilizes this oil and sludge recovery tank.

[0012] In order to achieve the above object, the present invention provides an oil and sludge recovery tank for recovering reusable oil and sludge from oil-containing wastewater, comprising an oil removal valve provided on the bottom side of the side of the oil and sludge recovery tank, a waste solids removal body erected from the bottom of the oil and sludge recovery tank, and a suction space surrounded by the side and the waste solids removal body for sucking oil stored in the oil and sludge recovery tank via the oil removal valve, wherein the waste solids removal body has an oil selection function that selectively allows oil to pass through.

[0013] In this oil and sludge recovery tank, it is preferable that the waste solid removal body has a U-shape when viewed from above and consists of three rectangular prism-shaped waste solid removal plates erected from the bottom surface of the oil and sludge recovery tank.

[0014] In this oil and sludge recovery tank, as the oil selection function, it is preferable that a plurality of punched holes are formed on the surface of the waste solids removal body, the internal space of the waste solids removal body is filled with glass wool, and a thin plate is placed on the bottom side of the waste solids removal body to act as a wall to prevent water from being pressed in.

[0015] In this oil and sludge recovery tank, it is preferable to provide a cover for covering the suction space and the waste solid remover from the outside.

[0016] In this oil and sludge collection tank, it is preferable that the cover device has three sides and a top formed of plate-shaped intrusion prevention walls, one side and a bottom open, and a vertically extending slide bar connected to the top surface of the cover device.

[0017] In this oil and sludge collection tank, the oil and sludge collection tank further includes a detachable cover plate that maintains a sealed state with the oil and sludge collection tank when closed, and it is preferable that the slide bar of the cover device passes through a through hole formed in the cover plate and be able to slide up and down.

[0018] In this oil and sludge recovery tank, it is preferable that a float plate is integrally provided on the upper surface of the cover.

[0019] In this oil and sludge collection tank, the oil and sludge collection tank has an approximately rectangular parallelepiped shape, and is provided on its bottom with a water discharge valve for discharging water and a sludge discharge valve for removing sludge, and it is preferable that at least one of its side and bottom is provided with a tank heating section arranged in a planar shape for heating the oil and sludge collection tank.

[0020] In order to achieve the above-mentioned object, the present invention provides an oil recovery system, which has a circulation pipe that runs from an oil supply pipe that sends the upper layer from an oil-water separation tank to the oil and sludge recovery tank and returns to the oil and sludge separation tank, and is characterized in that the oil and sludge recovery operation is performed from the oil-water separation tank using the oil and sludge recovery tank.

[0021] In order to achieve the above-mentioned object, the present invention provides an oil recovery system comprising an oil and sludge recovery tank, wherein the oil and sludge recovery tank further comprises a water / residue recovery valve provided on the bottom of the oil and sludge recovery tank for recovering the residue and water separated at the bottom, and the oil recovery system is characterized in that it also has a water / residue tank connected to the water / residue recovery valve for storing the water and residue extracted from the water / residue recovery valve.

[0022] In this oil recovery system, it is preferable that the water / residue tank further includes a detachable cover plate that maintains a sealed state between the water / residue tank and the tank when closed.

[0023] The present invention provides an oil and sludge recovery tank for recovering reusable oil and sludge from oil-containing wastewater, the oil and sludge recovery tank comprising an oil removal valve provided on the bottom side of the side of the oil and sludge recovery tank, a waste solids remover erected from the bottom of the oil and sludge recovery tank, and a suction space surrounded by the side and the waste solids remover for sucking oil stored in the oil and sludge recovery tank via the oil removal valve, the waste solids remover having an oil selection function for selectively passing oil. With this configuration, the present invention can be installed on-site at food factories, commercial facilities, etc. that discharge oil-containing wastewater, and can recover oil and sludge from oil-containing wastewater while minimizing the need to open the lid, which can cause odors.

[0024]

[0023] Figures 1A and 1B are diagrams illustrating an overview of an oil recovery system including an oil and sludge recovery tank according to a first embodiment of the present invention. (a) is a bottom view of the oil and sludge recovery tank, (b) is a side view of the oil and sludge recovery tank, (c) is an enlarged plan view of an oil selective separation mechanism provided in the oil and sludge recovery tank, and (d) is a side view of the oil and sludge recovery tank. (a) to (d) are explanatory diagrams of a cover plate provided in the oil and sludge recovery tank. (a) is a plan view of a waste solids removal plate provided in the oil and sludge recovery tank, and (b) is an explanatory diagram of the waste solids removal plate and suction space. (a) and (b) are explanatory diagrams of a cover provided in the oil and sludge recovery tank. (a) and (b) are diagrams illustrating a method of using the cover.

[0024] Figures 1A and 1B are diagrams illustrating a method of using the cover.

[0025] Figures 1A and 1B are diagrams illustrating a functional block diagram of the oil and sludge recovery tank. (a) and (b) are diagrams showing the transition state of the stored amount in the oil and sludge recovery tank of the same. (c) and (d) are diagrams showing the transition state of the stored amount in the oil and sludge recovery tank of the same. FIG. 1 is a diagram explaining an overview of an oil recovery system including an oil and sludge recovery tank and a water / residue recovery tank according to a second embodiment of the present invention. (a) is a bottom view of the water / residue recovery tank of the same, (b) is a side view of the water / residue recovery tank of the same, and (c) is a side view of the water / residue recovery tank of the same. (a) to (d) are explanatory views of a cover plate provided on the oil and sludge recovery tank of the same. (a) and (b) are diagrams showing the transition state of the stored amount in the oil and sludge recovery tank of the same. (c) and (d) are diagrams showing the transition state of the stored amount in the oil and sludge recovery tank of the same.

[0025] (Embodiment 1) An oil recovery system including an oil and sludge recovery tank according to Embodiment 1 of the present invention will be described with reference to Figures 1 to 9. This oil and sludge recovery tank is a tank that pumps out and temporarily stores a large amount of floating upper layer (floating oil and fat) in an oil-water separation tank (raw water tank) that pools manufacturing wastewater discharged from a food factory or the like. The upper layer of the oil-water separation tank contains water, sludge, and oil, in descending order of specific gravity. This oil recovery system efficiently recovers oil and sludge from the floating oil and fat pumped out of the oil-water separation tank, thereby achieving energy reuse (recycling), and is an on-site food factory recycling type that is installed on-site at a food factory or the like that discharges manufacturing wastewater.

[0026] First, an oil recovery system S equipped with an oil and sludge recovery tank (hereinafter referred to as a recovery tank) according to the first embodiment will be described with reference to Fig. 1. The oil recovery system S includes an oil-water separation tank OS and a recovery tank T. The oil-water separation tank OS is also called a grease trap, oil trap, grease interceptor, etc., and its basic structure generally employs a natural separation and flotation method that utilizes the difference in specific gravity between water and oil.

[0027] The piping of the oil recovery system S includes an inlet pipe P1 (oil supply path (corresponding to arrow A)) for sending the floating oil (upper layer) in the oil-water separation tank OS to the recovery tank T, and a circulation pipe P2 (return path (corresponding to arrow B)) for returning the influent stored in the recovery tank T to the oil-water separation tank OS. The function of performing the circulation operation shown in this figure makes it possible to efficiently recover oil and sludge in the recovery tank T, and to circulate the influent to return it to the oil-water separation tank OS. Pumps are provided in the inlet pipe P1 and the circulation pipe P2.

[0028] The recovery tank T receives floating oil (upper layer) from an oil-water separation tank OS, which temporarily stores oil-containing wastewater, via an inlet pipe P1. The recovery tank T also has an inlet valve 11 that controls the inflow rate of the floating oil pumped from the oil-water separation tank OS via the inlet pipe P1. Oily water, sludge, and water flow into the recovery tank T from the oil-water separation tank OS.

[0029] An oil removal valve OV, such as a 25A HT ball valve, for exclusive use in recovering oil is provided on the side of the recovery tank T (the lower right side in FIG. 1 ). The oil removal valve OV is fixed horizontally, for example, with its cylindrical lower end positioned 3 cm above the bottom of the recovery tank T. The oil removed through the oil removal valve OV is pumped by an electromagnetic pump or other pump and flows into a purification and transfer device 12, which separates excess solids contained in the oil.

[0030] The recovery tank T has dimensions of, for example, 1500 mm wide x 1100 mm deep x 570 to 650 mm high (1200 mm high when the support columns 2 are included) (approximate capacity 1000 L), and has a roughly rectangular parallelepiped shape with a gentle slope on one side at the bottom to prevent excess waste from accumulating inside. Note that the shape of the recovery tank T is not limited to the shape shown in the figure, and other shapes such as a cylinder may be used as long as the same function is achieved.

[0031] The refined transfer device 12 has a centrifugal separator function such as Filstar (registered trademark), and after excess solids other than oil are collected in a train cup, the clean refined oil from which the excess solids have been removed is finally collected in a refined oil tank (e.g., a 1000 L IBC container) 13.

[0032] A water discharge valve WV, such as a 40A motorized ball valve, is provided on the bottom of the recovery tank T to recover water, and the discharged water is returned to the oil-water separation tank OS as wastewater via the circulation pipe P2. A discharge valve 14 may also be provided to control the amount of water discharged. The inlet valve 11 and the discharge valve 14 are, for example, motorized valves that control the opening and closing states of the valves in response to command signals from a control unit (described later). The oil removal valve OV and the water discharge valve WV may be either motorized valves or manual ball valves that are opened and closed manually without receiving a command signal.

[0033] A sludge discharge valve DV is provided on the bottom side of the recovery tank T for the exclusive use of removing sludge, and the sludge stored in the recovery tank T is removed. The removed sludge is separated by a sludge removal device 15, and the separated sludge is collected in a sludge tank 16.

[0034] The recovery tank T is provided with vertically extending supports 2 at the four corners of the bottom surface to support it in a hollow state. These supports 2 allow the top surface of the recovery tank T to be elevated to a height of, for example, 1200 mm, making it easier for workers to recover oil and sludge.

[0035] As shown in Fig. 3, three detachable plate-shaped cover plates 3 are provided on the top surface of the recovery tank T. As shown in Fig. 3, the cover plates 3 are each fixed at the four corners thereof with a knob bolt 33 via a packing 32 so that they can be opened and closed. The cover plates 3 normally keep the recovery tank T sealed, preventing odors and other contaminants from being released to the outside. However, if necessary, the cover plates 3 can be removed by removing the knob bolts 33, allowing cleaning of the interior of the recovery tank T and visual inspection of the interior of the recovery tank T. Note that although the cover plates 3 are rectangular in shape in this drawing, they may also be other shapes such as square or circular.

[0036] The recovery tank T is equipped with a tank heating section H such as a planar silicon rubber heater (three-phase 200V) made of a nickel alloy sandwiched between silicon rubber sheets that heats the bottom and the front, back, left and right sides of the tank, a temperature sensor TS that detects the temperature inside the recovery tank T, and an oil detection sensor ODS that detects oil on the bottom of the recovery tank T.

[0037] The tank heating unit H is provided in a planar form along five surfaces, for example, the side and bottom surfaces of the recovery tank T, and the on / off state of the heating unit can be selected on the side or bottom. The temperature sensor TS is a temperature sensor that measures the temperature of the stored contents in the recovery tank T by utilizing the fact that the electrical resistance of a semiconductor or the like changes with temperature. The oil detection sensor ODS is a sensor that detects the presence of oil at a predetermined position (for example, the bottom side) of the recovery tank T, and uses, for example, an optical fiber to detect a change in output caused by the propagating light being attenuated by being scattered to the outside when oil adheres or being absorbed by the oil.

[0038] A stainless steel (SUS) waterproof cover is attached to the surface of the tank heating section H using packing and screws, and a heat insulating material is sealed inside. By sealing the heat insulating material in this way, the temperature inside the recovery tank T can be maintained at a range of about 65 to 70 degrees for a long period of time, which in turn promotes efficient separation of oil, sludge, and water inside the recovery tank T.

[0039] The recovery tank T is equipped with a float sensor FS, which is a level gauge capable of detecting the interface between the water layer and the oil mud layer (a mixture of oil and sludge) inside the tank. This float sensor FS is a measuring instrument that uses the fact that a float moves up and down due to the weight of the oil mud to measure the interface between the water layer and the oil mud layer stored in the recovery tank T, and functions to accurately measure the interface between the water layer and the oil mud layer inside the recovery tank T. This float sensor FS can detect the approximate amount of oil and sludge inside the recovery tank T.

[0040] Next, the oil selective separation mechanism S1 provided inside the recovery tank T according to the first embodiment will be described with reference to Figures 4 to 6. As shown in Figure 4, the recovery tank T has three rectangular prism-shaped waste solids removal plates 4a to 4c connected together, and a waste solids removal body 4 having a U-shape in top view erected from the bottom of the tank. The waste solids removal body 4 and the side surface on which the oil removal valve OV is formed form an oil suction space AS. Note that the waste solids removal body 4 is not limited to a U-shape in top view, and may have any other shape, such as a semicircular shape in top view, as long as it has the function of removing the waste solids.

[0041] The waste solid remover 4 is erected at a predetermined height (e.g., 250 mm) from the bottom of the recovery tank T and has dimensions of, for example, about 500 mm long x 350 mm short when viewed from above. The suction space AS has dimensions of about 300 mm long x 250 mm short x 250 mm high (e.g., a capacity of 18.75 L).

[0042] This waste solids removal body 4 (as well as the three waste solids removal plates 4a to 4c) has an oil selection function. It has a mesh structure made of metal or synthetic resin (for example, glass wool or stainless steel punching) that can filter and remove waste solids such as dust and floating matter. Specifically, to achieve the oil selection function, multiple punched holes 42 are formed on the surface of the waste solids removal body 4, and the internal space is filled with glass wool 43 as a filler. However, other structures and shapes may be used as long as they are capable of selectively absorbing oil.

[0043] Furthermore, as shown in Figure 4(b), a thin plate 41 made of stainless steel (SUS) may be welded about 50 mm from the bottom of the waste solid remover 4 to act as a water pressure prevention wall. This thin plate 41 will prevent water from flowing into the suction space AS, even if water remains at the bottom of the recovery tank T and the waste solid remover 4 is subjected to water pressure from the outside. In addition, assuming that water will flow into the suction space AS, it may be possible to provide a water discharge valve WV and an oil detection sensor on the bottom side of the suction space AS to discharge the water that has flowed into the suction space AS.

[0044] As shown in Fig. 5, the recovery tank T also includes a cover 5 for externally covering the suction space AS formed by the waste solid remover 4 and the waste solid remover 4. The cover 5 has a rectangular parallelepiped shape with three side surfaces and the top surface formed by plate-shaped intrusion prevention walls 51 and one side surface and the bottom surface open, and a vertically extending slide bar 52 is connected to the top surface of the cover 5. The slide bar 52 passes through a through-hole 32 formed in the cover plate 3 of the recovery tank T, allowing the cover 5 to slide up and down. When the cover 5 is positioned at the lowest position, it has a shape that externally covers the waste solid remover 4 (i.e., the suction space AS).

[0045] 5(b), a float plate 53 may be integrally provided on the upper surface of the covering device 5. This configuration of the float plate 53 allows the covering device 5 to move up and down without separating from the float plate 53, and prevents the covering device 5 from sinking due to the weight of oil or the like that has flowed into the recovery tank T. Specifically, in the present embodiment 1, the float plate 53 is a polystyrene foam plate.

[0046] Next, a method for using the cover device 5 will be described with reference to Figure 6. First, when floating oil and fats flow in from the oil-water separation tank OS and when the tank heating section H of the collection tank T is used to heat the oil and fats, the cover device 5 is slid to the lowest end so as to cover the outer periphery of the waste solids remover 4, as shown in Figure 6(a). This prevents sludge from adhering to the waste solids remover 4, and appropriately prevents the waste solids remover 4 from becoming dirty and reducing the oil recovery efficiency.

[0047] 6(b), when recovering oil from the oil removal valve OV, the slide bar 52 is used to slide the cover 5 upward so that the oil comes into contact with the waste solids remover 4 (i.e., so that the oil can enter the suction space AS). This allows the waste solids remover 4 to come into contact with the oil stored in the recovery tank T, or allows the oil to flow in from the upper surface of the suction space AS.

[0048] Next, the function of the ECU (Electronic Control Unit) 31 provided on the control panel provided in the recovery tank T will be described with reference to Fig. 7. Note that the control panel is not an essential component of the recovery tank T according to the first embodiment. The control panel may be provided integrally with the recovery tank T, or may be separate from the recovery tank T.

[0049] The ECU 31 opens the inlet valve 11 to allow oil-containing wastewater from the oil-water separation tank OS to flow into the recovery tank T. When the inlet valve 11 is closed, the ECU 31 also controls the tank heating unit H to start heating. When the temperature detected by the temperature sensor TS reaches a predetermined temperature (65-70 degrees), the ECU 31 also controls the tank heating unit H to stop heating. In this way, the tank heating unit H is controlled to repeatedly operate on and off.

[0050] Thereafter, the ECU 31 controls the water discharge valve WV to open, thereby allowing only the water to be efficiently returned from the recovery tank T to the oil-water separation tank OS.

[0051] Furthermore, thereafter, when oil is detected by the oil detection sensor ODS provided on the bottom surface of the recovery tank T, the ECU 31 manually or electrically slides the cover 5 upward, and then opens the oil extraction valve OV. This allows only the oil to be efficiently sent from the recovery tank T to the refinement and transfer device 12.

[0052] 7, the ECU 31 includes a control unit 31a, a predetermined amount calculation unit 31b, a signal transmission unit 31c, and an input unit 31d. The control unit 31a determines whether or not it is necessary to receive an oil detection signal from the oil detection sensor OS in order to heat the floating oil filled in the recovery tank T and efficiently separate it into oil, sludge, and water, and when it receives an oil detection signal, it transmits a control signal to start operation to the tank heating unit H via the signal transmission unit 31c.

[0053] The predetermined amount calculation unit 31b performs calculation processing of a predetermined value based on various parameter information (the capacity of the recovery tank T, the inflow amount from the inlet valve 11, the discharge amount from the discharge valve 14, the temperature of the TS, and oil detection). The signal transmission unit 31c transmits an on / off control signal for the heating operation to the tank heating unit H. It also transmits a valve opening adjustment signal to the inlet valve 11 and the discharge valve 14. The input unit 31d provided on the control panel is an operation setting device, a remote control, or the like, and enables input of various parameter information required for calculation of the predetermined amount by the predetermined amount calculation unit 31b, as well as input setting of the predetermined amount.

[0054] Next, the transition state of the stored contents in the recovery tank T according to the first embodiment will be described with reference to Figures 8 and 9. First, the floating oil and grease flows from the oil-water separation tank OS into the recovery tank T, and when the liquid level detected by the float sensor FS or the like reaches a predetermined position, the inlet valve 11 is closed. This flow path switching may be performed manually. At this time, the cover device 5 is fixed in its lowest position.

[0055] Next, the tank heating section H is started, and the inflow is heated to about 70°C. When the temperature reaches about 70°C, the inflowing oils and fats are separated in order of their specific gravity, and as shown in Figure 8(a), from the bottom, the floating oils and fats are separated into layers of water, oil-containing floating sludge (so-called black oil), and oil.

[0056] When the temperature sensor TS provided on the tank body reaches, for example, 70°C and the heating of the wastewater is completed (i.e., the separation into layers is completed), the water discharge valve WV formed on the bottom of the recovery tank T is opened, and the water at the bottom of the recovery tank T is returned to the oil-water separation tank OS via the discharge valve 14. When the removal of the inflow water is completed, sludge (oil-containing floating sludge) and oil are stored in the recovery tank T from the lower layers, as shown in Figure 8(b). This sludge may be manually collected via the sludge discharge valve (manual valve) DV formed on the bottom of the recovery tank T as shown in Figure 8(b).

[0057] The extracted oil-containing floating sludge is classified as industrial waste and can be stored in a sludge waste tank and treated as industrial waste sludge. This sludge can be used, for example, for biogasification (methane power generation, clean hydrogen), and the first step in turning this unused sludge into a resource is expected to be biogasification (methane power generation, green hydrogen) at a biogas plant that performs methane fermentation.

[0058] As the sludge layer is discharged, oil falls and accumulates, but when the oil reaches the bottom of the recovery tank T, the recovery tank T enters the state shown in Figure 9(c), and oil is detected by the oil sensor OS. Then, the oil refining / transfer lamp lights up, and the operator closes the sludge discharge valve (manual valve) DV. Note that the sludge discharge valve (manual valve) DV may be controlled to close automatically.

[0059] 9(c), when oil has accumulated in the recovery tank T, the operator releases the cover device 5, and the float plate 53 causes the top surface of the cover device 5 to automatically float above the oil. Alternatively, the operator may slide the cover device 5 upward, for example, to a height of about 350 mm of the waste solid remover 4, or even higher, to the extent that a gap is created between the top surface of the suction space AS and the bottom surface of the cover device 5. Then, the oil removal valve OV is opened, and the electric pump is turned on.

[0060] Then, the oil in the recovery tank T is automatically recovered, and the inside of the recovery tank T transitions to the state shown in Figure 9(d). The recovered oil is purified by the refinement and transfer device 12 to remove fine impurities, and is then recovered in the refined oil tank 13.

[0061] In the past, a refinement and transfer device, a separator for waste solids, waste oil impurities, and waste water layers, as shown in Patent No. 5452814, was used, and by opening the lid each time and pouring this into the tank from the top, the waste solids, waste oil impurities, waste water, etc. contained in the waste oil were further selectively separated and removed, and only the waste oil usable as an alternative fuel was transferred to a separate container for transportation and storage. On the other hand, in the present invention, there is no need to open the lid plate 3 of the recovery tank T each time and pour in the refinement and transfer device, which efficiently recovers only the oil layer in the recovery tank T, improving work efficiency and greatly reducing the frequency of opening the lid, thereby reducing the generation of odors.

[0062] In this way, the oil, sludge, and water in the recovery tank T are separated, completing the series of recovery operations. After this, when the capacity of the oil-water separation tank OS installed in the same facility becomes full, the processes of Figures 8(a) to (d) are repeated, and the oil and sludge are transferred to the recovery tank T, and the separation and recovery of the oil and sludge is automatically and efficiently repeated.

[0063] As described above, the present invention provides an oil and sludge recovery tank T that recovers reusable oil and sludge from oil-containing wastewater, comprising an oil removal valve OV provided on the bottom side of the side of the oil and sludge recovery tank T, a waste solids removal body 4 that has a U-shape when viewed from above and is made up of three rectangular pillar-shaped waste solids removal plates 4a to 4c that are erected from the bottom of the oil and sludge recovery tank T, and a suction space AS that is a space surrounded by the side and the waste solids removal body 4 and is used to suck up oil stored in the oil and sludge recovery tank T via the oil removal valve OV, and the waste solids removal body 4 has an oil selection function that selectively passes oil through.

[0064] With this configuration, the recovery tank T according to this embodiment has the following advantages: (1) the recovery (recycling) of oil from wastewater oils can be performed with almost no need to open the cover plate 3, and odors are reduced. (2) By simply installing the recovery tank T on-site within a facility, the oil refining and transfer and sludge removal can be nearly automated, eliminating the burden of manual work on the part of workers each time, and recycling of wastewater oils can be completed.

[0065] In other words, the recovery tank T is installed on-site in an energy-saving and space-saving manner in a food factory or the like that discharges oil-containing wastewater, and can almost automatically extract, recover, and recycle oil and sludge from the oil-water separation tank OS that pools the oil-containing wastewater while preventing the generation of odor. Also, some food factories generate several tons of floating oil and fat every day, and by installing an on-site recovery tank T like the present invention on the factory premises, it is possible to provide an on-site recycling service.

[0066] Furthermore, sludge can be extracted and efficiently recovered via a sludge discharge valve (manual valve) DV provided in the recovery tank T. Furthermore, the inflow water that flows into the recovery tank T can be returned directly to the oil-water separation tank OS via the circulation pipe P2.

[0067] (Embodiment 2) Next, an oil recovery system according to Embodiment 2 of the present invention will be described with reference to Figures 10 to 14. This oil recovery system S2 is used in commercial facilities, restaurants such as fast food chains, and fuel manufacturing plants that discharge wastewater containing solids such as oil, sediment, and suspended matter. The oil and sludge recovery tank T according to Embodiment 2 also serves as a tank for temporarily storing floating oils and sludge pooled in treatment devices (e.g., grease traps) conventionally provided at each business establishment.

[0068] Furthermore, this oil recovery system S2 removes water and garbage from the pooled wastewater, efficiently recovers oil, sludge, and other components, and aims to reuse energy (resource recovery). This oil recovery system S2 can be installed on-site within a facility, such as a fuel production plant or a commercial facility (e.g., a fast food chain). Note that, for example, a field agent (a specialist provided with unique know-how, training, and certification by the applicant) may clean and manage grease traps at restaurants and also provide a service to manage this oil recovery system S2.

[0069] Next, an oil recovery system S2 according to the second embodiment will be described with reference to Figure 10. In this oil recovery system S2, a water / residue tank WRT is also provided in addition to the recovery tank T in the first embodiment described above. Note that although a float sensor is not essential in the recovery tank T according to the second embodiment, the other configurations are substantially the same as those in the first embodiment described above, and therefore detailed description thereof will be omitted.

[0070] This water / residue tank WRT is a tank for storing the residue and water separated at the bottom of the recovery tank T when the recovery tank T is heated, which is removed from a water / residue recovery valve (e.g., a 40A electric hole valve drain) WI located on the bottom of the recovery tank T. The water / residue tank WRT has a rectangular parallelepiped shape, with dimensions of, for example, 1500 mm wide x 570-650 mm high x 1100 mm deep (capacity approximately 300 L). Note that the shape of the water / residue tank WRT is not limited to the shape shown in this diagram, and other shapes such as a cylinder may be used as long as the same function is achieved.

[0071] As shown in Figure 12, the water / residue tank WRT has a number of detachable cover plates 6 on its top surface. These cover plates 6 are fixed to the top surface of the water / residue tank WRT using knob bolts 62 via packing 61. In addition, a water / residue removal valve W2 such as a 40A socket is provided on the side.

[0072] In the second embodiment, wastewater is directly introduced into the recovery tank T from a grease trap or the like, so it is expected that floating debris will remain in the upper layer. In this case, a floating debris recovery valve (manual valve) with a relatively large diameter may be provided on the side of the recovery tank T for this purpose, and the floating debris may be efficiently removed using a suction pump through this valve. Alternatively, the floating debris may be manually recovered by periodically opening the cover plate 6 of the recovery tank T.

[0073] Next, the transition state of the stored contents in the recovery tank T according to the second embodiment will be described with reference to Figures 13 and 14. First, wastewater from a grease trap or the like is transferred into the recovery tank T. This transfer is performed within the same facility and may be performed manually by an operator using a dedicated tool, or may be performed automatically via an inlet pipe by turning on an electric pump switch.

[0074] Next, when the wastewater reaches a predetermined amount inside the recovery tank T, the tank heating unit H starts to heat the inflowing water until it reaches about 70 degrees Celsius. When the temperature reaches about 70 degrees Celsius, the wastewater is separated into layers of residue, water, oil-containing floating sludge (so-called black oil), oil, and floating garbage from the bottom up, as shown in Figure 13(a).

[0075] Then, when the heating of the wastewater is completed (i.e., the separation into each layer is completed), the water / residue removal valve W1 formed on the bottom of the recovery tank T is opened, and the residue and water on the bottom side of the recovery tank T are transferred to the water / residue tank WRT. Once the residue and inflow water are removed from the recovery tank T, sludge, oil, and floating debris are stored in the recovery tank T from the bottom layer, as shown in Figure 13(b).

[0076] The discharged residue and water are temporarily stored in the water / residue tank WRT. The residue is discharged from the water / residue tank WRT via a 40A HT hole valve or the like formed on the bottom side of the tank and collected in a dedicated tank, where it can be disposed of as industrial waste. On the other hand, the water is discharged into the wastewater treatment reactor 17 after impurities and other contaminants have been removed using, for example, a purification and transfer device 12.

[0077] Next, if a sludge layer is included, the sludge will accumulate on the bottom side of the recovery tank T as shown in Figure 13(b), and this sludge may be manually recovered using the manual valve 18. The recovered sludge will be transferred via the sludge removal device 15 to a sludge industrial waste tank (for example, a lorry tank 16 (W 800 mm x L 630 mm x H 630 mm, capacity 200 L)) and can be disposed of as industrial waste.

[0078] As the sludge layer is discharged, oil falls and accumulates, but when the oil reaches the bottom of the recovery tank T, the recovery tank T enters the state shown in Figure 14(c), and oil is detected by the oil sensor OS. The oil purification and transfer lamp then lights up, so the operator uses the slide bar 52 to release the cover 5. The float plate 53 then acts to automatically raise the top of the cover 5 above the oil, after which the oil removal valve OV is opened and the electric pump is turned on.

[0079] Then, only the oil in the recovery tank T is recovered, and the inside of the recovery tank T transitions to the state shown in Figure 14(d). The recovered oil is purified using the refinement and transfer device 12 to remove excess impurities, and is then recovered in the refined oil tank (IBC container) 13.

[0080] 14(d) does not invade the oil suction space AS due to the presence of the waste solids remover 4 and the cover 5. For example, if floating debris is mixed in, the floating debris can be appropriately prevented from invading the suction space AS by moving the cover 5 up and down in accordance with the liquid level detected by the float sensor FS. This floating debris can be removed periodically or when it reaches a predetermined amount, for example, from a dedicated outlet provided on the bottom side of the recovery tank T, or an operator can open the cover 3 of the recovery tank T and manually collect it.

[0081] In this way, in the second embodiment, as in the first embodiment, there is no need to open the cover plate 3 of the recovery tank T and insert the refined transfer vessel each time, which improves work efficiency. Also, since the oil recovery (recycling) work can be performed without opening the cover plate 3 of the recovery tank T or the cover plate 6 of the water / residue tank WRT, odors are less likely to be generated.

[0082] In this manner, the water, sludge, and oil in the recovery tank T are separated, completing the series of recovery operations. After this, when the capacity of the grease trap or the like is filled, the wastewater is transported to the recovery tank T, and the process is repeated from the state shown in Figure 13(a).

[0083] As explained above, the second embodiment can also achieve the same effects as the first embodiment. That is, (1) Recycling work can be performed without opening the cover plate 3 of the recovery tank T or the cover plate 6 of the water / residue tank WRT, which reduces the generation of odors. (2) Both the oil purification and transfer and the sludge removal are nearly automated, which reduces the workload. (3) Because the recovery tank T is equipped with the water / residue tank WRT, even if residue flows into the recovery tank T, the water and residue can be easily transferred to and managed in the water / residue tank WRT.

[0084] The present invention is not limited to the configuration of the above embodiment, and various modifications are possible within the scope of the invention. For example, in order to increase the speed of oil recovery, multiple oil selective separation mechanisms S1 can be provided in the oil and sludge recovery tank T.

[0085] S, S2 Oil recovery system S1 Oil selective separation mechanism T Oil and sludge recovery tank (recovery tank) OV Oil removal valve OS Oil-water separator AS Suction space H Tank heating section WRV Water and residue recovery tank W1 Water and residue recovery valve WV Water discharge valve DV Sludge discharge valve P1 Oil supply pipe P2 Circulation pipe 3, 6 Cover plate 4 Waste solid removal body 4a to 4c Waste solid removal plate 5 Covering fixture 11 Inlet valve 14 Discharge valve 32 Through hole 41 Thin plate 42 Punched hole 43 Glass wool 51 Intrusion prevention wall 52 Slide bar 53 Float plate

Claims

1. An oil and sludge recovery tank for recovering reusable oil and sludge from oil-containing wastewater, comprising: an oil removal valve provided on the bottom side of the side of the oil and sludge recovery tank; a waste solids removal body erected from the bottom of the oil and sludge recovery tank; and a suction space surrounded by the side and the waste solids removal body, for sucking oil stored in the oil and sludge recovery tank via the oil removal valve, wherein the waste solids removal body has an oil selection function that selectively allows oil to pass through.

2. The oil and sludge recovery tank according to claim 1, characterized in that the waste solid removal body has a U-shape when viewed from above and is composed of three rectangular prism-shaped waste solid removal plates erected from the bottom of the oil and sludge recovery tank.

3. The oil and sludge recovery tank according to claim 2, characterized in that, as the oil selection function, a plurality of punched holes are formed on the surface of the waste solids removal body, the internal space of the waste solids removal body is filled with glass wool, and a thin plate is placed on the bottom side of the waste solids removal body to act as a wall to prevent water from being pressed in.

4. An oil and sludge recovery tank according to claim 1 or 2, further comprising a cover for covering the suction space and the waste solids remover from the outside.

5. The oil and sludge recovery tank according to claim 4, wherein the cover has three sides and a top formed of plate-shaped intrusion prevention walls, one side and a bottom open, and a vertically extending slide bar is connected to the top of the cover.

6. The oil and sludge collection tank according to claim 5, further comprising a detachable cover plate that maintains a sealed state with the oil and sludge collection tank when closed, and the slide bar of the cover passes through a through-hole formed in the cover plate and is slidable in the vertical direction.

7. An oil and sludge recovery tank according to claim 4, characterized in that a float plate is integrally provided on the upper surface of said cover.

8. The oil and sludge recovery tank according to claim 1, characterized in that the oil and sludge recovery tank has a substantially rectangular parallelepiped shape, is provided on its bottom with a water discharge valve for discharging water and a sludge discharge valve for removing sludge, and is provided with a tank heating section provided in a planar shape on at least one of its side and bottom.

9. An oil recovery system characterized by having a circulation pipe that returns from an oil supply pipe that sends the upper layer from an oil-water separation tank to the oil and sludge recovery tank described in claim 1, and which performs oil and sludge recovery operations from the oil-water separation tank using the oil and sludge recovery tank.

10. An oil recovery system comprising an oil and sludge recovery tank as described in claim 1, wherein the oil and sludge recovery tank further comprises a water and residue recovery valve provided on the bottom of the oil and sludge recovery tank for recovering the residue and water separated at the bottom, and the oil recovery system further comprises a water and residue tank connected to the water and residue recovery valve for storing the water and residue extracted from the water and residue recovery valve.

11. An oil recovery system as described in claim 10, characterized in that the water / residue tank further comprises a detachable cover plate that maintains a sealed state between the water / residue tank and the tank when closed.

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