JP6367447B1 - Oil tank draining system - Google Patents

Abstract

[PROBLEMS] An oil tank drainer capable of maximizing automation of the draining operation while improving the safety and equipment reliability of the tank draining operation without remodeling the oil tank for handling dangerous materials. Providing a system. An oil tank draining system S is provided in a water tank 59 connected to an oil tank 1 through a draining pipe 4, a water discharge pipe 30 connected to the water tank 59, and a water discharge pipe 30. A water transfer pump 33, a water level detector 32 of water W stored in the water tank 59, and a pump drive controller 26 for driving the water transfer pump 33 by a liquid level detection signal. And an oil film detector 57 for detecting the oil film LS in the water tank 59 and an edge valve driving controller 12 for closing the edge open / close valve 10 by detecting the oil film LS. . [Selection] Figure 1

Description

  The present invention relates to an oil tank draining system for performing draining work in an outdoor oil tank storing dangerous materials under the Fire Service Law.

  Conventionally, as this kind of oil tank draining system, what was described in the following patent document 1, for example is known. As shown in FIG. 11, the oil tank draining system 90 </ b> A described in this document 1 includes a draining pipe 4 with a main valve 2 connected to the oil tank 1 and an underground excavation unit that temporarily stores water W from the oil tank 1. A semi-underground water tank 98 installed in the GB, a water discharge pipe 30 connected to the water tank 98, an air-driven water transfer pump 33 provided in the water discharge pipe 30, and the water tank 98 An air-driven liquid level detector 97 that detects the level of the stored water W and oil L, and an air drive that drives the water transfer pump 33 based on the liquid level detection signal detected by the liquid level detector 97. A pump drive controller 26 of the type, and an automatic on-off valve 91 provided in the draining pipe 4 on the downstream side of the main valve 2.

  The automatic opening / closing valve 91 is housed in a main body casing 92 having a box-shaped main body casing 92 having a valve seat opening 93 connected to the flowing water pipe 94 in the lower part of the box and a valve seat opening 95 open to the atmosphere in the upper part of the box. The float body 96 </ b> A that opens and closes the valve seat port 95 and the float body 96 </ b> B that is accommodated in the main body casing 92 below the float body 96 </ b> A and opens and closes the valve seat port 93. The main casing 92 is connected to the tip of the draining pipe 4, and the flowing water pipe 94 is disposed above the water tank 98. This automatic opening / closing valve 91 has a float structure that sinks in oil L and opens the valve seat port 95 and closes the valve seat port 93, floats on water W and opens the valve seat port 93 and closes the valve seat port 95. The water W is allowed to flow into the water tank 98 while the oil L is stopped so as not to flow. The liquid level detector 97 is an air-driven level switch. The float body 100 floats on the water W or oil L in the water tank 98 and the air from the air pipe 53 is placed at the height position of the float body 100. The float valve 99 is adjusted to pilot air having a corresponding air pressure and output to the pump drive controller 26. The pump drive controller 26 is a three-way valve, and is provided in the middle of the air pipe 20 from the instrument air AM to the water transfer pump 33, and is based on the air pressure of the pilot air from the float valve 99. The pressure-adjusted air is sent to the water transfer pump 33 to control the pump water supply amount.

  On the other hand, for example, a system described in Patent Document 2 below is also known. As shown in FIG. 12, the oil tank draining system 90 </ b> B described in Document 2 includes a draining pipe 4 with a main valve 2 connected to the oil tank 1, and water W from the oil tank 1 disposed on the ground G. And a closed tank 101 for storing oil L, a water discharge pipe 30 connected to the closed tank 101, an electric automatic opening / closing valve 104 provided in the water discharge pipe 30, a top portion of the closed tank 101, and a side wall of the oil tank 1 And a boundary surface sensor 105H that detects that the boundary surface between the water W and the oil L in the closed tank 101 has reached the set high level 106H. A boundary surface sensor 105L for detecting that the boundary surface between the water W and the oil L in the sealed tank 101 has reached the set low level 106L, the boundary surface sensor 105H, and the boundary surface sensor 1 A valve drive controller 107 of the computation function to open and close control of the automatic opening and closing valve 104 based on the detection signal from the 5L, and a. In this oil tank draining system 90B, the valve drive controller 107 controls the automatic opening / closing valve 104 based on the detection signals of the boundary surface sensors 105H and 105L, and only the water W of the sealed tank 101 is downstream from the water discharge pipe 30. The oil is drained into the oil-containing drainage system.

JP-A-7-76394 JP-A-8-282798

  However, in the oil tank draining system 90 </ b> A (FIG. 11) described in the above-mentioned literature 1, the structure of the automatic opening / closing valve 91 becomes a liver, and when the foreign matter adheres to the valve seat surface of the valve seat ports 93, 95, the automatic opening / closing valve Since 91 cannot maintain the tight shut performance, oil water accompanying valve leak flows into the water tank 98, and these may overflow from the water tank 98.

  In addition, the oil tank draining system 90B (FIG. 12) described in the above-described document 2 is arranged so that the upper and lower sides of the small sealed tank 101 are placed at the same level as the boundary surface between the oil L layer and the water W layer of the oil tank 1. The nozzle of the part is connected to the oil tank 1. This system has the selling point of “automatic draining without any special processing on the existing storage tank”, but it is structurally located on the side wall of the oil tank 1 higher than the top of the sealed tank 101. A hole must be drilled and a nozzle that would normally not be installed must be welded to the hole. To that end, new nozzle construction work must be carried out after the regular maintenance timing of the oil tank 1 every several years, and it is also necessary to undergo strict government inspections. Further, in this oil tank draining system 90B, the boundary surface sensors 105H and 105L, the valve drive controller 107, and the automatic on-off valve 104 are all electrically driven, so that expensive and strict explosion-proof equipment must be used. There was also a problem of not obtaining. Incidentally, water tanks used for draining oil tanks are subject to various regulations under the Fire Service Act, but originally such water tanks temporarily store water from the oil tanks. Therefore, it is doubtful whether a tank that intentionally stores both water and oil as in Patent Document 2 can be used as a water tank that complies with the law.

  The present invention has been made in view of the above-described conventional problems, and becomes a key point in draining work without performing time-consuming and time-consuming modification work such as newly installing a nozzle in the oil tank itself. The objective is to provide an oil tank draining system that can maximize the automation of draining operations while improving safety and equipment reliability.

  In order to achieve the above object, an oil tank draining system according to the present invention includes a draining pipe connected to an oil tank, a water tank connected to the oil tank via the draining pipe and temporarily storing water from the oil tank. A water discharge pipe connected to the water tank, an air driven water transfer pump arranged in the water discharge pipe, and an air driven liquid level detector for detecting the liquid level of the water stored in the water tank And an oil-driven drainage system for driving the water transfer pump based on the liquid level detection signal detected by the liquid level detector, and is disposed in the drainage pipe An air-driven edge-opening / closing valve, an oil film detector for detecting an oil film formed on the upper surface of the water stored in the water tank, and closing the edge-opening / closing valve when an oil film is detected by the oil film detector Air driven A cut valve drive controller, those consisting comprise.

  Moreover, in the said structure, the constant flow valve set to the flow volume smaller than the maximum water supply amount of a water transfer pump is arrange | positioned by the draining piping.

  In each configuration described above, a cylindrical casing having an inlet opening connected to the tank body of the water tank at the lower end and an outlet opening communicating with the atmosphere at the upper end, and vertically moved into the cylindrical casing. An air bleeder comprising: a float valve that floats freely in water accommodated therein; and a valve seat that is disposed in a cylindrical casing above the float valve and divides the cylindrical casing vertically. In the air bleeder, the float valve, which has opened the valve opening of the valve seat, floats due to water flowing into the cylindrical casing and closes the valve opening of the valve seat.

  Further, in each of the above-described configurations, the edge cut-off opening / closing valve has a main body casing provided in the draining pipe, a metal spherical valve body rotatably loaded in the valve chamber of the main body casing, and a main body casing communicating with the draining pipe. And a synthetic resin sheet body that is slidably in contact with the spherical valve body and opens and closes the flow path in the valve of the spherical valve body. It is what.

Also, before the Ki構 formed, edge cutting off valve, in which is provided a valve body drive mechanism for automatically driven to close the valve internal channel spherical valve body time of stopping supply of driving air.

  In each of the above-described configurations, at least a draining pipe, a water tank, a water discharge pipe, a water transfer pump, a liquid level detector, a pump drive controller, an oil film detector, and an edge cut-off opening / closing valve are provided on a common base in advance. The prefabric unit is configured by being attached, the prefabric unit is installed in the vicinity of the oil tank, and the draining pipe of the prefabric unit is connected to the oil tank.

  According to the oil tank draining system of the present invention, the edge cut-off valve between the oil tank, the oil film detector for detecting the oil film in the water tank, and the edge cut-off valve driving for closing the edge cut-off valve when detecting the oil film When the oil film is detected on the surface of the water temporarily stored in the water tank, the drainage operation of the oil tank is continuously performed using the downstream water tank. The edge cut valve drive controller closes the edge cut open / close valve to shut off the oil tank and the water tank. Therefore, it is possible to reliably prevent the oil in the oil tank from flowing into the water tank after the oil film is detected, thereby preventing the overflow of water and oil from the water tank. In addition, since the main components of the system are air-driven, high safety can be ensured even when draining oil tanks that handle hazardous materials. In addition, installation work such as nozzle installation on the oil tank side is not required.

  In the case of a constant flow valve that is set to a flow rate smaller than the maximum water supply amount of the water transfer pump, the water draining water from the oil tank is continuously received and the continuous transfer operation from the water transfer pump is in progress. However, since water and oil do not increase in the water tank, an overflow accident from the water tank can be reliably prevented, and the draining operation can be performed with peace of mind.

  In the case of an air bleeder connected to the water tank, when the liquid level in the water tank rises and oily water flows into the air bleeder from the vent pipe, the float valve floats and closes the valve seat. Therefore, it is possible to prevent draining water and oil film from overflowing into the atmosphere. Thereafter, when the liquid level in the water tank decreases and the pressure in the tank becomes equal to or lower than the atmospheric pressure, the float valve is lowered and opened, so that the air bleeder automatically returns to the atmosphere open state.

  Furthermore, in the case where the edge opening / closing valve is constituted by a ball valve, the ball operation is different from that in which the handle operation for opening / closing the valve has to be rotated a plurality of times, such as a gate valve widely used for a main valve or the like. For example, the valve can open and close the flow path only by rotating the valve drive shaft about 90 degrees, so that when the oil film is detected in the water tank, the rim opening / closing valve can be quickly closed. Oil flow into the water tank can be minimized. By the way, since oil refineries have a large number of oil tanks, a gate valve with an inexpensive and simple structure is adopted on the outlet side of the oil tank, and the ball valve is expensive and used routinely. However, it has now been found that the installation of a ball valve between the oil tank and the water tank is extremely suitable.

  Further, in the case where the edge cut-off valve is constituted by a so-called soft touch type ball valve in which the valve body and the seat body are not in contact with each other, the spherical valve body and the seat body are made of metal and synthetic resin. Therefore, there is no concern about low sealing properties such as metal-to-metal contact, foreign object biting, difficulty in rotation, or noise. Therefore, it is possible to perform a quick and smooth turning operation of the spherical valve body in response to an emergency state in the water tank.

  Also, in the case where the edge cut-off valve has a valve body drive mechanism, the valve body drive mechanism automatically drives the spherical valve body even when the supply of drive air is stopped for some reason. The road can be urgently closed. That is, even in such a situation, the flow path from the oil tank to the water tank can be blocked to reliably prevent overflow of water and oil from the water tank.

  And if the prefabricated unit is used, where the main components of the oil tank draining system are pre-installed on a common baseboard, the prefabricated unit is manufactured at the factory prior to installation near the tank, thus meeting the needs. It is possible to provide a highly versatile oil tank draining system in which parts of specified specifications and sizes are selected in advance. Also, since the prefabricated unit can be installed near the oil tank according to the oil tank draining process, there is no need to install more than necessary near the oil tank. The process can be shortened.

It is a schematic side view showing an oil tank draining system according to an embodiment of the present invention. It is a figure which shows the water tank of the said oil tank draining system, (a) is a top view, (b) is a side sectional view, (c) is a front sectional view. It is a figure which shows the edge cutting on-off valve of the said oil tank draining system, Comprising: (a) is a sectional side view, (b) is a BB arrow sectional drawing in (a). It is a side view including the partial cross section which shows the float body of the oil film detector of the said oil tank draining system. It is a schematic sectional side view which shows the metering valve of the said oil tank draining system. It is side sectional drawing which shows the air bleeder of the said oil tank draining system. It is a figure which shows the pre-fabric unit formed by installing the required component of the said oil tank draining system on a common base, Comprising: (a) is a schematic plane block diagram, (b) is a schematic side block diagram. It is a schematic side view block diagram which shows the oil tank draining system which has a semi-underground type water tank concerning another embodiment of this invention. It is a figure which shows the float body of the oil film detector of the oil tank draining system which concerns on other embodiment of this invention, Comprising: (a) is a schematic side view block diagram, (b) is a float body when the oil film on water is detected It is a schematic side view block diagram which shows the state. It is a figure which shows the float body of the oil film detector of the oil tank draining system which concerns on other embodiment of this invention, Comprising: (a) is a schematic side view block diagram, (b) is a float when the oil film on water is detected It is a schematic side block diagram which shows the state of a body. It is a schematic side view showing an example of a conventional oil tank draining system. It is a schematic side block diagram which shows another example of the conventional oil tank draining system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiment described below is merely an example embodying the present invention, and does not limit the technical scope of the present invention. FIG. 1 is a schematic side view showing an oil tank draining system according to an embodiment of the present invention.

  Here, a general description of sludge in the oil tank will be given first. According to the technical paper “Recovery technology of pyrolysis oil from fluidized sludge waste by fluidized bed (Hokkaido Industrial Development Laboratory)”, “Wax oil containing iron rust and sand mud during inspection and cleaning of oil storage tanks and tankers” A large amount of sludge is discharged, and the generated amount of sludge reaches 1% or more of the tank content when it is large, and accumulates as a mixture containing a large amount of wax-like materials that are difficult to handle at room temperature. 90% by weight or more of the sludge is oil that is difficult to handle at room temperature, and is composed of 3 wt% moisture, 3.5 wt% ash, 5.5 wt% residual carbon, and 2 Wt% sulfur. Then, when draining the oil tank, sludge containing iron rust and foreign matters is discharged from the draining pipe 4 to the outside of the tank while being pushed out into water with high fluidity. In addition, gasoline and naphtha products and semi-finished products that are classified as hazardous 1st Petroleum may contain rust and foreign matter inside equipment such as distillation towers, drums, and heat exchangers in the refining stage. is there. In addition, products belonging to the 1st petroleum are generally stored in floating roof tanks, but rainwater that falls on the floating roof has a structure that prevents inflow into the oil tank at the floating roof weather seal part, Rainwater on the floating roof is drained into an oil barrier outside the tank by a roof drainage system. However, because of the deformation or breakage of the floating roof weather seal, rainwater enters the tank through the inner wall of the oil tank and accumulates in the lower part. Therefore, it is necessary to drain the water before shipping the product. It is also implemented before maintenance.

Therefore, the oil tank draining system S according to the embodiment as shown in FIG. 1 is used for draining the oil tank 1. The oil tank 1 is constructed on a foundation GA higher than the ground G. However, the oil L is mainly stored in the oil tank 1, and the water W derived from rain water or the like is stored below the oil L. .
Thus, the oil tank draining system S includes a draining pipe 4 connected to the oil tank 1, a water tank 59 connected to the oil tank 1 through the draining pipe 4, and water connected to the water tank 59. Dispensing pipe 30 is provided. For example, a main valve 2 including a gate valve, a flexible metal hose 5, a strainer 6, and an air-driven edge cutting opening / closing valve 10 are disposed in the draining pipe 4 in order from the oil tank 1 side.

  The design specifications of the flexible metal hose 5 described above are assumed to be 7 years from the equipment for petroleum products or coal products manufacturing industry in “Appendix 2 Machines and Equipment Life Tables for Depreciable Assets”. ing. In addition, according to “Operations related to the timing of security inspections of specified outdoor tank storage (Fire Safety No. 45, February 25, 2011, General Manager, Dangerous Goods Safety Office, Fire Safety Agency, Safety of the ground related to bearing capacity and subsidence” As for, the annual average subsidence based on the measurement results of the subsidence over time is within 1 cm. From this, 7 cm of tank subsidence (1 cm / year x equipment lifespan 7 years = subsidence 7 cm) is a flexible metal hose. The design settlement amount is 5. In addition, the flexible metal hose 5 is a high-quality product rated as a fire-fighting product, and has the design specifications of the manufacturer's standard maximum operating pressure of 1.0 MPa, the maximum operating temperature of 100 ° C., and the maximum axis perpendicular displacement of 100 mm.

  The strainer 6 described above is, for example, a bucket type, and is installed for the purpose of preventing the inflow of foreign matter to the downstream constant flow valve 7 and the edge cut valve 10. The mesh size of the filtration wire mesh was set to 40 mesh or more with reference to an oval flowmeter strainer. Since the strainer 6 is clogged with the filtrate during operation, the opening area of the filtration wire mesh is secured to 3/3 of the inner cross-sectional area of the inlet pipe of the strainer 6, thereby reducing the filter wire mesh to 2/3 of the filtration wire mesh. The operation can be continued even if clogging occurs. In this case, since the fluid resistance when passing through the filtration wire mesh increases due to clogging of the filtration wire mesh, the filtration wire mesh is prevented from being damaged by setting the differential pressure strength of the filtration wire mesh to 0.3 MPa or more. In addition, the pressure difference between the upstream portion and the downstream portion of the strainer 6 is displayed on a differential pressure gauge so that it can be easily determined from the outside so that the clogged state of the bucket-type strainer 6 due to the filtrate can be easily recognized.

  Here, the amount of water W drained from the oil tank 1 will be described with reference to Table 1 below. For example, assuming that the internal volume of the target oil tank 1 is 5000 KL, the amount of water W is 84.5 KL {= (π × 23) when the tank inner diameter is about 23.2 m and the draining water is 20 cm high. .2 × 23.2 / 4) × 0.2 m}. When the water transfer pump 33 uses, for example, an air-driven diaphragm pump XPS400 type (drive air pressure: 0.56 MPa) manufactured by Wilden, the water supply time is about 6 hours at a discharge flow rate of 13.8 KL / Hr. However, since the amount of drainage is significantly large in crude oil tanks of 80,000 KL or more, a larger capacity Wilden air driven diaphragm pump XPS 1500 type (driving air pressure: 0.56 MPa) is used and divided into several days. Draining work may be performed.

  As shown in FIG. 2, the water tank 59 has a bottomed rectangular tube-shaped tank body 13, a top plate 25 that seals the upper surface opening of the tank body 13, and an opening formed in a part of the top plate 25. A rectangular tube-shaped manhole 8 erected on the periphery of the part and a lid plate 27 that seals the upper surface opening of the manhole 8 are hermetically sealed. The end of the draining pipe 4 is inserted and connected to one end of the tank body 13, and the end of the water discharge pipe 30 is inserted and connected to the other end of the tank body 13. A vent pipe 60 and a cylinder 28 of the liquid level detector 32 are inserted into and fixed to the top plate 25. The respective distal end portions of the cylindrical body 28 and the water discharge pipe 30 are suspended to the inside of the pit portion 31 formed lower than the bottom surface of the tank main body 13. In the manhole 8, guide poles 34, 34 each having a weight 35 attached to the lower end are suspended from the lower surface of the cover plate 27. The water tank 59 temporarily stores water W or a small amount of oil L that flows from the oil tank 1 through the draining pipe 4.

  In order to avoid the water tank 59 being an outdoor tank under the Fire Service Act, that is, No. 20 tank, the amount of oil flowing into the water tank 59 is set to oil film thickness detection sensitivity of 10 ± 1 mm or less, as shown in Table 2 below. The oil inflow is managed to be less than 1/5 of the specified quantity corresponding to the dangerous goods. Thereby, the oil tank draining system S, which is a draining work automation facility, can be used as an incidental facility for the oil tank 1. The size of the water tank 59 is not limited to the draining pipe 4 and the water discharging pipe 30, but also includes an oil film detector 57 for detecting and managing the oil content of the water W, and a liquid level detector 32 for automatically operating the water transfer pump 33. And a size capable of arranging necessary nozzles such as the vent pipe 60 of the air bleeder 61. Here, when the oil tank 1 is a tank that handles the first petroleum, the dimensions of the water tank 59 are a width of 800 mm, a depth of 800 mm, and a height of 500 mm. Therefore, the oil amount corresponding to the oil film thickness detection sensitivity of 10 ± 1 mm is 7L, and from Table 2 below, it can be made less than 1/5 of the specified quantity.

  Further, the water tank 59 includes a liquid level detector 32 for detecting the level of water W and trace oil stored in the water tank 59, and an oil film LS generated on the upper surface of the water W in the water tank 59. The float part 3 of the oil film detector 57 for detecting the above is provided. The water discharge pipe 30 is provided with an air-driven water transfer pump 33, a sight glass 37, a check valve, and the like. The tip of this water discharge pipe 30 is connected to an oil-containing drainage system DW such as an oil-water separator.

  The liquid level detector 32 described above uses, for example, an air-driven displacer liquid level detector A10-2G3B-KOF manufactured by Magnetol Corporation. The liquid level detector 32 includes a cylindrical body 28 suspended in the tank from the ceiling of the water tank 59, a control air adjuster 19 that is a level switch provided on the upper part of the cylindrical body 28, and the cylindrical body 28. A high level float 24H for setting a high water level and a low level float 24L for setting a low water level, which are housed inside and suspended by a control air regulator 19, are provided. When the high level float 24H reaches the high water level setting position (a height position of 90% or less of the total height of the water tank 59), the valve in the control air adjuster 19 of the liquid level detector 32 is mechanically opened to control air. The pilot air from the regulator 19 turns on the pump drive controller 26 for driving the water transfer pump on the downstream side of the air pipe 67 and supplies air to the water transfer pump 33 from the air pipe 20 for operation. On the other hand, when the low float 24L reaches the low water level setting position (60 mm height from the bottom of the water tank 59), the valve in the control air adjuster 19 of the liquid level detector 32 is mechanically closed and the air piping 67 is closed. When the pilot air is not supplied to the pump, the pump drive controller 26 for driving the water transfer pump is turned off to stop the operation of the water transfer pump 33.

  That is, the pump drive controller 26 is an air-driven three-way valve type provided in the air pipe 20, and is driven to the water transfer pump 33 based on the liquid level detection signal detected by the liquid level detector 32. The amount of water transferred is controlled by turning on and off the air supply. Here, since the lower limit of the low water level setting of the liquid level detector 32 is required to be 60 mm or more from the bottom surface of the water tank 59, as shown in the water tank 59 of FIG. A pit portion 31 that is 60 mm deeper than the bottom surface of the water tank 59 is formed at a position below the tip on the suction side of the water discharge pipe 30 so that as much water W in the water tank 59 as possible can be taken out. The water transfer pump 33 is configured to withstand emptying.

  As shown in FIG. 3, the above-described edge opening / closing valve 10 includes a valve portion V (ball valve) and an actuator portion Q that drives the valve portion V to open and close. The valve portion V includes a main body casing 36 provided in the middle of the draining pipe 4, a metal spherical valve body 40 rotatably mounted in the valve chamber of the main body casing 36, and a main body communicating with the draining pipe 4. The sheet body 42 is provided with an inlet-side channel 38 and an outlet-side channel 39 (axial center C) of the casing 36, respectively. Each sheet body 42 is made of a synthetic resin, and is slidably and elastically in contact with the spherical valve body 40 so as to open and close the in-valve flow path 41 of the spherical valve body 40. That is, the edge cut-off opening / closing valve 10 is configured by a ball valve of a type (soft touch method) in which metals do not slidably contact each other.

  The actuator portion Q includes a horizontal cylindrical (axial center C1) cylinder 44 having both ends opened, a pair of yoke pistons 47, 47 mounted in an air chamber 52 in the cylinder 44, and yoke pistons 47, 47. Shaft bodies 49, 49 attached to each other, link plates 48 having guide grooves for housing the shaft bodies 49, 49, bottomed cylindrical spring cases 45, 45 respectively attached to both ends of the cylinder 44, and spring cases 45, 45 and coil springs 46, 46 that elastically urge the yoke pistons 47, 47 toward the ring plate 48 in the direction of the axis C1.

  And the lower part of the cylinder 44 of the actuator part Q is connected with the upper part of the main body casing 36 of the valve part V, and the driving shaft 43 facing the saddle is inserted in this connecting part. The drive shaft 43 is interposed between the link plate 48 of the actuator part Q and the spherical valve body 40 of the valve part V to drive and connect them. The cylinder 44 facing the air chamber 52 is formed with an air inlet 51 for taking air into and out of the air chamber 52.

  In the edge cut-off opening / closing valve 10, the air pipe 20 is connected to the air inlet 51, and when air is injected from the air inlet 51 into the air chamber 52, the yoke pistons 47, 47 in the cylinder 44 are connected to the coil spring 46, 46 is pushed outward in the direction of the axis C against the elastic biasing force 46 (in the directions of arrows D and D). Thereby, when the ring plate 48 is rotated, the spherical valve body 40 is rotated via the drive shaft 43 to open the in-valve channel 41 with respect to the seat bodies 42 and 42. On the other hand, when the injection of air into the air chamber 52 is stopped, the yoke pistons 47 and 47 are automatically pushed back by the elastic biasing force of the coil springs 46 and 46, and the spherical valve body 40 is rotated to turn the flow path in the valve. 41 is closed. That is, the configuration comprising the spring cases 45 and 45, the coil springs 46 and 46, the yoke pistons 47 and 47, the shaft bodies 49 and 49, and the link plate 48 on both sides is the spherical shape of the edge cut-off valve 10 when the supply of driving air is stopped. This is a configuration of an air-to-open setting spring return type valve element drive mechanism 29 in which the valve element 40 is automatically driven to close the in-valve flow path 41. Due to the existence of the valve body drive mechanism 29, even when the air supply is stopped due to some trouble, the oil tank 1 and the water tank 59 can be bordered on the safe side.

  The above-described edge-opening / closing valve 10 is a shut-off valve for edge-separating the oil tank 1 and the water draining system, and when the valve leaks from the inner valve, the oil tank 1 existing tank flows out to the outside and becomes an abnormal state. Tight shut reliability is required as the most important valve. Accordingly, a ball valve with a tight shut valve having a high reliability is selected as the valve type, the spherical valve body is made of SCS13A (stainless steel casting), and the valve seat material is a synthetic resin having a high sealing property, such as PTFE (Teflon: registered trademark). ).

  As shown in FIG. 4, the float body 3 of the edge cut valve drive controller 12 includes a floating member F having a donut shape in plan view, a computing unit 64 installed at a central opening of the floating member F, and a computing unit 64. The tuning fork type sensor 62 and the conductivity sensor 63 provided on the lower surface of the electric wire 17 and the electric wire 17 that connects the arithmetic unit 64 and the oil film detector 57 to supply power and transmit signals. A sealed air chamber 54 is formed in the floating member F. Guide holes 55 and 55 penetrating vertically are formed in the floating member F. The guide poles 34, 34 described above are passed through the guide holes 55, 55 to guide the float body 3 up and down. In this float body 3, the floating member F floats on the oil film LS and the water W, the tuning fork sensor 62 detects the presence of a liquid such as the oil film LS and the water W, and the conductivity sensor 63 detects the presence of the oil film LS. It has become. The tuning fork type sensor 62 detects that the film thickness of the oil film LS has reached a predetermined film thickness (for example, 10 mm thickness) based on a preset height position of the operating point. The float body 3 is provided with a wave removing plate (not shown) for preventing wave generation due to the flow of fluid in the water tank 59.

  The oil film detector 57 described above discriminates the tuning fork type sensor 62 for discriminating the presence of liquid (water W or oil L) and the absence of liquid (air), and conductor (water W) / non-conductor (air or oil L). An endless Hauser explosion-proof oil leak detector NAR300 system is used in combination with the conductivity sensor 63. The detection object condition is a water-insoluble liquid having a specific gravity of 0.7 or more and less than 1.0. The power supply is a DC power source DC converted from AC 100V (50/60 Hz). The electric signal when the oil film LS having a thickness of 10 ± 1 mm is detected is sent from the oil film detector 57 to the electropneumatic converter 56 via the electric wire 11 to stop the supply of driving air from the air pipe 50 and open / close the edge. The valve 10 is closed. On the contrary, the supply of driving air is continued by the electrical signal when the oil film LS is not detected, so that the edge cut-off valve 10 is open. Further, the oil film detector 57 is attached to the 400 mm square manhole 8 to facilitate the inspection and repair of the float body 3 (inner diameter 304 mmΦ) for detecting the oil film installed in the water tank 59. That is, the air-driven edge cut-off valve drive control that closes the edge cut-off valve 10 when the oil film LS is detected by the oil film detector 57 from the float body 3, the oil film detector 57, and the electropneumatic converter 56. A container 12 is configured.

  The main drive source of the drive device of the oil tank draining system S is air, and this air is supplied from, for example, an air piping network of instrument air AM installed in the plant. Air from the instrument air AM is sent to the drive unit of the water transfer pump 33 through the air pipe 20 which is the main pipe. From the water transfer pump 33 side, a pump drive controller 26 that is a three-way valve, an air filter, a pressure reducing valve 21B, an air livestock pressure drum 21A, and the like are disposed in the air pipe 20. A bypass pipe 23 having a manual on-off valve 22 is bypass-connected to the air pipe 20 on both sides of the pump drive controller 26. An air pipe 50 and an air pipe 53 are branched and connected from the middle of the air pipe 20. The tip of the air pipe 50 is connected to the electropneumatic converter 56. The tip of the air pipe 53 is connected to the air inlet of the control air adjuster 19 in the liquid level detector 32. The air outlet 14 of the electropneumatic converter 56 and the actuator of the edge cut-off valve 10 are connected by an air pipe 14 with a check valve 16. The outlet side of the check valve 16 in the air pipe 14 and the air pipe 50 are connected by a bypass pipe 15 with a manual on-off valve 22. In addition, power from the DC power source DC is sent to the oil film detector 57 via the electric wire 58. The float unit 3 and the oil film detector 57 in the water tank 59 are connected by an electric wire 17 that sends a detection signal from the float unit 3. The oil film detector 57 and the electropneumatic converter 56 are connected by an electric wire 11 that sends a calculation signal from the oil film detector 57.

  As shown in FIG. 5, the above-described constant flow valve 7 is disposed on the upstream side in the water discharge direction of the edge cut-off opening / closing valve 10 in the middle of the drainage pipe 4. The constant flow valve 7 includes a cylindrical main body casing 65 interposed in the middle of the draining pipe 4 and a bottomed body that is disposed in the main body casing 65 and supported in a suspended manner by the support members 83, 83, 83, 83. A cylindrical bottomed cylinder 66, a strainer 68 that covers the opening of the bottomed cylinder 66 so that water can pass through, a piston damper 69 accommodated in the bottomed cylinder 66, and a downstream side of the bottomed cylinder 66 in the water flow direction. A conical disc 73 disposed in the bottom, a connecting rod 72 that connects the piston damper 69 and the conical disc 73 through the rod hole 71 of the bottomed cylinder 66, and a piston damper 69 accommodated in the bottomed cylinder 66 in the direction of water flow. The coil spring 70 is elastically biased to the upstream side, and the contracted curved surface body 74 is attached to the inner surface of the main body casing 65 on the downstream side of the bottomed cylinder 66. The constant flow valve 7 is configured such that when the amount of water flowing through the draining pipe 4 is increased, the piston damper 69 and the conical disc 73 are pushed downstream against the elastic biasing force of the coil spring 70, thereby causing the conical disc 73. The water channel between the curved surface 74 and the contracted curved surface 74 is narrowed so that the amount of water flowing through the narrowed water channel is suppressed to a constant amount. The set water amount of the constant flow valve 7 is set to a flow rate smaller than the maximum water supply amount of the water transfer pump 33.

The receiving flow rate of the water W to the constant flow valve 7 receives the head pressure corresponding to the liquid level of the oil tank 1, and therefore, when the main valve 2 is fully open, from the Trichery theorem (v = √2 gh) The displacement head is 17 m, the oil specific gravity is 0.75, the pipe inner diameter is 3 inches, the flow rate is 13.7 m / sec, and the flow rate is 688 m ³ / Hr. When the water W of this flow rate is received as it is in the water tank 59, the tank capacity is 288L, so that overflow occurs instantly. In addition, if the flow rate of the constant flow valve 7 is larger than the discharge flow rate value of the water transfer pump 33 in the water tank 59, the insufficient water transfer due to continuous pump operation accumulates and causes overflow. By keeping the set flow rate constant at 230L / min ± 5% or less and setting the flow velocity as low as about 0.8m / sec, the water tank 59 is prevented from overflowing, and the float sensor and level detector float trouble To prevent this.

The vent pipe 60 from the ceiling of the water tank 59 is connected to the draining pipe 4 on the downstream side of the main valve 2. An air bleeder 61 (so-called vacuum breaker valve) is branched and connected in the middle of the vent pipe 60. Instead of installing the air bleeder 61, a vent pipe 60A (two-dot chain line) that is raised to the vicinity of the upper end of the oil tank 1 and opened to the atmosphere may be branched and connected. The air bleeder 61 is used as an automatic exhaust valve for the water tank 59. As shown in FIG. 6, the inlet bleed 77 connected to the tank body 13 of the water tank 59 through the vent pipe 60 is provided at the lower end. A cylindrical casing 75 having an outlet opening 82 at the upper end and communicating with the atmosphere, and a hollow spherical float valve 79 floating in water accommodated in a storage chamber 76 below the cylindrical casing 75 so as to be vertically movable. And a ring-shaped valve seat 80 arranged in a cylindrical casing 75 above the float valve 79. The inside of the cylindrical casing 75 is vertically divided by the valve seat 80. In this air bleeder 61, the float valve 79 that has opened the valve opening 81 of the valve seat 80 is floated by the water W that flows into the cylindrical casing 75 from the inlet opening 77, and opens the valve opening 81 of the valve seat 80. It comes to close. When the inside of the cylindrical casing 75 is empty, the float valve 79 is hollowly supported by a float receiver 78 in the accommodation chamber 76.
By installing this air bleeder 61, even when the liquid level detector 57 fails and the water transfer pump 33 cannot be operated while the water tank 59 is at a high water level, or when the water transfer pump 33 stops due to a failure or the like, The overflow of the water tank 59 can be prevented.

  As shown in FIG. 7, the oil tank draining system S is provided as a pre-fabric unit U in which most of the components are gathered together. The prefabricated unit U includes a part of the draining pipe 4, a part of the water tank 59, a part of the water discharging pipe 30, a water transfer pump 33, a liquid level detector 32, a rim opening / closing valve 10, a constant flow valve 7, an oil film detector. 57, the float body 3, the air bleeder 61, a part of the air pipe 20, and the like are mounted on the common base 9 in advance at a factory or the like. The water transfer pump 33 is installed on a frame 9 </ b> A assembled to the common base 9. This prefabricated unit U is carried from the production factory to a position near the oil tank 1 (dangerous goods outdoor tank), for example, a position 1 m away from the foundation GA, and is a unit made of concrete, for example, partially embedded in the ground G in advance. Installed on the foundation UA. A strainer 6 and a flexible metal tube 5 separately installed in the vicinity of the unit are connected to the flange of the constant flow valve 7 of the prefabric unit U via a draining pipe 4, and further connected to the flange of the main valve 2. Thus, the prefabricated unit U is connected to the oil tank 1. The prefabricated unit U is preferably installed on the ground at a position 1 m or more away from the outside of the foundation GA (tank ring wal) so as not to adversely affect the foundation of the oil tank 1.

Next, the operation of the oil tank draining system S configured as described above will be described.
The drain water W that has flowed into the water tank 59 is transferred to the oil-containing drainage system DW by the water transfer pump 33. When transferring to the existing oil-impregnated drainage DW drain tank by the water transfer pump 33, the required pump discharge pressure, which is the sum of the pressure loss of the water discharge pipe 30 and the drain tank head, is calculated to calculate the final capacity of the air pump. Select. Since the discharge pressure of the water transfer pump 33 is determined by the air pressure for driving the pump, the general instrument air pressure is set to 0.56 MPa here, but actually, the individual instrument air pressure is confirmed and used. The air-driven diaphragm pump XPS400 manufactured by Wilden has a discharge flow rate of 230 L / min and a discharge pressure of 0.28 MPa when the driving air pressure is 0.56 MPa. Since the water transfer pump 33 is a kind of reciprocating pump, it is easy to give pressure fluctuations to the air pipe 20 which is the main line from the instrument air AM. Therefore, an air pressure drum 21A is installed in the middle of the air pipe 20. The pressure in the air pipe 20 is stabilized.

  As described above, when the drainage amount is 20 cm in the 5000 KL oil tank 1, the water amount is 85 KL, and the transfer time by the water transfer pump 33 (13.8 KL / Hr) is about 6 hours. Further, in the oil tank 1 for crude oil of 110,000 KL, the amount of water is about 1216 KL. In this embodiment, an operation by the operator is required at the start of operation of the draining device, but after the start, it is possible to safely automate until the end of the draining operation.

  And as a return method of the tank draining system S after the edge cut-off valve 10 is closed due to the oil film detection, the main valve 2 is closed and the manual open / close valve of the bypass pipe 15 for the edge cut-off valve 10 at the timing when the draining operation is performed again. By opening 22, the edge opening / closing valve 10 is opened, and when the manual opening / closing valve 22 of the vent pipe 60 is opened, the oil remaining in the draining pipe 4 is received in the water tank 59. The oil remaining in the draining pipe 4 collected in the water tank 59 drives the water transfer pump 33 by opening the manual on-off valve 22 of the bypass pipe 23 for driving the water transfer pump 33, and supplies water to the oil-containing drainage system DW. Water W in the tank 59 is sent. Thereafter, the main valve 2 is opened, the manual on-off valves 22, 22, and 22 are closed as they are, and the automatic draining operation is resumed.

  As described above, according to the oil tank draining system S according to this embodiment, the oil film detection that detects the edge cut-off valve 10 disposed between the oil tank 1 and the water tank 59 and the oil film LS in the water tank 59. When the oil tank 1 is continuously drained using the water tank 59 on the downstream side, the water tank 59 and the edge cut-off valve drive controller 12 that closes the edge cut-off valve 10 when the oil film is detected are provided. When the oil film LS is detected on the surface of the water W temporarily stored in the water tank 59, the edge cut valve drive controller 12 closes the edge cut open / close valve 10 to shut off the oil tank 1 and the water tank 59. To do. Accordingly, it is possible to reliably prevent the oil L in the oil tank 1 from flowing into the water tank 59 after the oil detection, and thus the overflow of the water W and the oil L from the water tank 59 can be prevented. In addition, since the main components of the oil tank draining system S are all air-driven, high safety can be ensured even in the draining operation of the oil tank 1 that handles dangerous substances.

  In addition, since the edge-opening / closing valve 10 is constituted by a ball valve, as compared with the gate valve for opening / closing the valve, such as a gate valve that is generally used for the main valve 2 or the like, For example, since the valve passage 41 can be opened and closed simply by rotating the drive shaft 43 by about 90 degrees, the edge-closing valve 10 can be quickly closed when an oil film LS is detected in the water tank 59. The oil inflow from the oil tank 1 to the water tank 59 can be suppressed as much as possible.

  The edge cut-off valve 10 is constituted by a so-called soft touch ball valve in which the spherical valve body 40 and the sheet bodies 42 and 42 are not in contact with each other, so that the spherical valve body 40 is made of metal and the sheet body. Since 42 and 42 are made of a synthetic resin such as polytetrafluoroethylene, there are no concerns such as low sealing properties such as metal-to-metal contact, foreign object biting, difficulty in rotation, and noise. Accordingly, it is possible to perform a quick and smooth turning operation of the spherical valve body 40 in response to an emergency state in the water tank 59.

  Further, since the edge cut-off valve 10 includes the coil spring 46 that is the valve body drive mechanism 29, the valve body drive mechanism 29 is provided even when the drive air from the instrument air AM is stopped for some reason. The spherical valve body 40 can be automatically driven to rotate and the valve flow path 41 can be urgently closed. That is, even in such a situation, the flow path from the oil tank 1 to the water tank 59 can be blocked to prevent overflow of the water W or oil L from the water tank 59.

  In addition, since the constant flow valve 7 is set to a flow rate smaller than the maximum water supply amount of the water transfer pump 33, the water W drained from the oil tank 1 is being continuously received and the water transfer pump 33 is continuously transferred. Even during operation, water W and oil L do not increase in the water tank 59. Accordingly, an overflow accident from the water tank 59 can be prevented. For example, when the draining pipe 4 has a pipe inner diameter of 3 inches, the set flow rate of the constant flow valve 7 is set to a value smaller than the maximum water supply amount 230 L / min (13.8 KL / Hr) ± 5% of the water transfer pump 33. By doing so, overflow from the water tank 59 during continuous operation can be reliably prevented, and the draining operation can be performed with peace of mind.

  In addition, a bucket-type strainer 6 of about 60 mesh is installed in the draining pipe 4 upstream of the edge opening / closing valve 10 and the constant flow valve 7 so that the sludge accumulated on the bottom surface of the oil tank 1 flows in. By doing so, it is possible to eliminate the cause of trouble such as a foreign matter biting into the strainer 68 in the edge cut-off valve 10 or the constant flow valve 7 and clogging. In particular, the constant flow valve 7 is effective because it has a small mesh opening area of the strainer 68 and is easily affected by clogging.

  Since the vent pipe 60 is provided with the air bleeder 61, when the liquid in the water tank 59 rises and flows into the air bleeder 61 from the vent pipe 60, the float valve 79 floats to close the valve seat 80. It is possible to prevent the water W and the oil film LS from overflowing into the atmosphere. Thereafter, when the liquid level in the water tank 59 falls and the tank internal pressure becomes equal to or lower than the atmospheric pressure, the float valve 79 is lowered and opened, so that the air bleeder 61 automatically returns to the atmosphere open state.

  Since the prefabricated unit U in which the main components of the oil tank draining system S are mounted on the common base 9 in advance is applied, the tank is installed in the vicinity of the oil tank 1 and then the oil tank 1 It can be used simply by connecting a pipe to the valve 2. In addition, since the prefabricated unit U is manufactured in a factory or the like prior to the installation in the vicinity of the tank, it is possible to provide an oil tank draining system S that is extremely versatile. Further, since the prefabricated unit U can be installed in the vicinity of the oil tank 1 in accordance with the process of draining the oil tank, there is no need for an unnecessary attachment process in the vicinity of the oil tank 1. Accordingly, the period of the draining process can be strictly observed, and the process can be shortened.

  The oil tank draining system S is installed in a dangerous area such as the storage oil barrier of the outdoor oil tank 1, so that the oil film detector 57, which is an electric supply device, uses an explosion-proof type. Since other devices are air-driven, all components are necessarily explosion-proof. In particular, the liquid level detector 32 and the water transfer pump 33 are also air-driven explosion-proof devices.

  In the above-described embodiment, the prefabricated unit U provided with the water tank 59 and the like is installed on the ground G in the vicinity of the oil tank 1, but the present invention is not limited thereto. For example, a semi-underground tank type system in which a water tank 59 is partially buried in a previously excavated underground excavation part GB as in the oil tank draining system Sa shown in FIG. 8 is also included in the present invention. In that case, it is preferable to form the underground excavation part GB 2 m or more away from the outside of the foundation GA so as not to adversely affect the foundation GA of the oil tank 1.

  In the above description, the electric oil film detector using the float body 3 having the tuning fork type sensor 62 and the conductivity sensor 63 is exemplified, but the present invention is not limited thereto. For example, an air-driven oil film detector using a float body 3a as shown in FIG. 9 is also included in the present invention. The float body 3a includes a horizontal pivot shaft 84 rotatably supported on the inner wall of the water tank 59, a balance rod 85 having a longitudinal center portion fixed to the pivot shaft 84, and both ends of the balance rod 85. A pair of drooping rods 86, 86 suspended swingably at positions, a high level detection float 87 A that is attached to one drooping rod 86 and floats on water W and oil L, and is attached to the other drooping rod 86. And a low detection float 87B that does not float on the oil L but floats on the water W.

  According to the oil film detector having the float body 3a, when the liquid in the water tank 59 is almost water W, the high level detection float 87A and the low level detection float 87B are substantially the same as shown in FIG. Since it is in the height position, the balance rod 85 is in a horizontal posture and the rotation angle of the pivot shaft 84 is 0 degree. On the other hand, when the oil film LS occurs on the water surface of the water W, as shown in FIG. 9B, the low detection float 87B floats on the boundary surface between the water W and the oil film LS, but the high detection float 87A It rises to match the upper surface of LS. As a result, a height deviation H is generated between the floats, the balance rod 85 is tilted, and the pivot shaft 84 rotates, for example, clockwise in the drawing. The specified rotation angle of the pivot shaft 84 when the deviation H becomes, for example, 10 mm is obtained in advance, and the oil film LS having a predetermined thickness is generated when the pivot shaft 84 reaches the specified rotation angle. It is detected by an air drive type float valve of the oil film detector, and the edge cut-off valve 10 is closed by the edge cut-off valve drive controller.

  Alternatively, an air-driven oil film detector using a float body 3b having a uniaxial holding rod 88 as shown in FIG. 10, for example, instead of the float body 3a of FIG. 9 is also included in the present invention. The float body 3b is fixed to the bottom end of the holding rod 88, which is supported by a top plate in the water tank 59 so as to be movable up and down, and fixed to the lower end of the holding rod 88. A floating low detection float 89B, and a floating high detection float 89A, which is inserted on the holding rod 88 so as to be movable up and down and disposed on the low detection float 89B and floating in water W and oil L, are configured.

  According to the oil film detector having the float body 3b, when the liquid in the water tank 59 is almost water W, as shown in FIG. 10 (a), the high level detection float 89A placed on the low level detection float 89B is Floating on the surface of water W. On the other hand, when the oil film LS is generated on the water surface of the water W, as shown in FIG. 10B, the low detection float 89B floats on the boundary surface between the water W and the oil film LS, and the high detection float 89A. Rises along the upper surface of the oil film LS. Thereby, a height deviation H is generated between the floats, and this deviation H is detected by the oil film detector as an increase amount. When the deviation H becomes, for example, 10 mm, the oil-driven float valve of the oil film detector detects that the oil film LS has a predetermined thickness, and the edge-cut valve drive controller closes the edge-cut valve 10. is there. That is, since the oil film detector having the float body 3a in FIG. 9 and the oil film detector having the float body 3b in FIG. 10 are both air-operated, a complete explosion-proof system is realized together with other components that are air-driven. This leads to the provision of an oil tank draining system.

  Further, in each of the above-described embodiments, the system using the ball valve as the edge cut-off opening / closing valve 10 is illustrated, but an air-driven valve other than the ball valve may be used as the edge cut-off opening / closing valve according to the present invention.

  Crude oil stockpiling bases, oil refining, product terminals, etc. are becoming more automated and labor-saving, while automation and labor-saving of water draining operations essential for oil tank management are delayed. The reason for this is presumed to be to avoid the risk of serious troubles due to concerns about the reliability of the work automation equipment. The present invention is intended to solve such problems, and is urged to be widely introduced into crude oil storage bases, petroleum refining, product terminals and the like.

DESCRIPTION OF SYMBOLS 1 Oil tank 3, 3a, 3b Float body 4 Water draining pipe 7 Constant flow valve 9 Common base board 10 Edge cutting on-off valve 12 Edge cutting valve drive controller 19 Control air regulator 20 Air piping 24H High float 24L Low float 25 Top plate 26 Pump Drive controller 29 Valve body drive mechanism 30 Water discharge pipe 32 Liquid level detector 33 Water transfer pump 36 Main body casing 38 Inlet side channel 39 Outlet side channel 40 Spherical valve body 41 Intravalve channel 42 Sheet body 43 Drive shaft 44 Cylinder 46 Coil spring 47 Yoke piston 56 Electropneumatic converter 57 Oil film detector 59 Water tank 60 Vent piping 61 Air bleeder 75 Cylindrical casing 77 Inlet opening 79 Float valve 80 Valve seat 80 Valve opening 82 Outlet opening AM Instrument air L Oil LS Oil film S, Sa Oil tank draining system U Prefabricated unit W Water

Claims (6)

A draining pipe connected to an oil tank, a water tank connected to the oil tank via the draining pipe and temporarily storing water from the oil tank, a water discharge pipe connected to the water tank, and the water An air-driven water transfer pump disposed in the discharge pipe, an air-driven liquid level detector for detecting the liquid level of the water stored in the water tank, and the liquid detected by the liquid level detector An oil-driven drainage system comprising: an air-driven pump drive controller that drives the water transfer pump based on a surface detection signal;
An air-driven edge-closing on-off valve disposed in the draining pipe;
An oil film detector for detecting an oil film formed on the upper surface of the water stored in the water tank;
An oil tank draining system comprising: an air driven edge cut valve drive controller that closes the edge cut opening / closing valve when the oil film is detected by the oil film detector. 2. The oil tank draining system according to claim 1, wherein a constant flow valve set to a flow rate smaller than a maximum water feeding amount of the water transfer pump is provided in the draining pipe. A cylindrical casing having an inlet opening connected to the tank body of the water tank at the lower end and an outlet opening communicating with the atmosphere at the upper end, and water accommodated in the cylindrical casing so as to be movable up and down An air bleeder comprising: a float valve that floats in the air; and a valve seat that is disposed in a cylindrical casing above the float valve and divides the inside of the cylindrical casing vertically. 2. The float valve that has opened the valve opening of the valve seat is floated by water flowing into the cylindrical casing, and the valve opening of the valve seat is closed. The oil tank draining system according to claim 2. The edge cut-off valve is a main body casing provided in the draining pipe, a metal spherical valve body rotatably mounted in a valve chamber of the main body casing, and an inlet side of the main casing that communicates with the draining pipe And a synthetic resin seat body that is provided in each of the flow path and the outlet flow path and that slidably contacts the spherical valve body and opens and closes the flow path in the valve of the spherical valve body. The oil tank draining system according to any one of claims 1 to 3, wherein the oil tank draining system is provided. The edge cutting off valve, 請 Motomeko 4 the spherical valve body automatically driven to the time of stopping supply of driving air you characterized by comprising a valve body drive mechanism for closing the valve in the flow path oil tank draining system according to. At least, the draining pipe, the water tank, the water delivery pipe, the water transfer pump, and the liquid level detector, the pump drive control, the oil film detector, and the edge cutting-off valve in advance to the common base surface plate The prefabricated unit is configured by being attached, the prefabricated unit is installed at a position near the oil tank, and a draining pipe of the prefabricated unit is connected to the oil tank. Item 6. The oil tank draining system according to any one of Items 5.

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