JPH03267183A - Method for discharging washing treatment liquid - Google Patents

Abstract

PURPOSE:To make improvement in the capacity to discharge sewage by stopping a vacuum pump and driving a discharge pump to discharge the sewage when the sewage in a strainer box attains a prescribed volume, then stopping the discharge pump and driving the vacuum pump. CONSTITUTION:To vacuum pump 11 connected to the discharge port side of a liquid sealing valve 9, the discharge pump 14 connected to a piping 13 provided in the bottom of the strainer box and a 2nd pressure switch 16 connected to the discharge port side of the pump 14 are provided. The sewage in the tank 1 is introduced into the box 7 by the negative pressure in the box 7 generated by the driving power of the pump 11. The vacuum pump 11 is stopped and the discharge pump 14 is driven by the operation of the 1st pressure switch 10 to discharge the sewage in the box 7 when the sewage in the box 7 attains the prescribed volume. The pump 14 is stopped and the pump 11 is restarted by the drop of the discharge pressure by the pump 14. Consequently, the capacity to discharge the sewage in the tank 1 is improved in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for discharging a cleaning liquid generated when cleaning the inside of a tank such as a crude oil tank.

(・Prior art) Inside a crude oil tank that stores crude oil, impurities contained in the crude oil precipitate and become sludge due to long-term storage of the crude oil.Therefore, after the crude oil is consumed, the crude oil is It is necessary to dissolve, discharge and clean the precipitated sludge in the tank.A wide variety of devices (washing machines) are known as cleaning devices for dissolving and discharging the precipitated sludge in the crude oil tank. The precipitated sludge is dissolved using the powerful jetting force of the cleaning oil ejected from the cleaning nozzle, and the dissolved sludge is discharged to the outside of the tank along with the cleaning oil to clean the inside of the tank.

[Problem a that the invention seeks to solve]

However, since a large amount of air is mixed into the sludge-dissolved cleaning oil that is stirred by the jetting force of the cleaning oil in the crude oil tank, this aerated liquid is pumped by a centrifugal pump, piston pump, screw pump, etc. However, the above-mentioned pump could not be used effectively because cavitation occurs and effective discharge of waste liquid cannot be achieved, resulting in a decrease in the waste liquid recovery ability or the inability to use the pump. . To compensate for this drawback, it is possible to use a vacuum pump. In other words, with a vacuum pump, even if air is mixed in the drained liquid, the liquid can be drained out of the tank without any problem, but on the other hand, the discharged liquid discharged from the vacuum pump has almost no discharge pressure. Therefore, there is a problem in that there is no lift for the drained liquid, and it is difficult to transport the drained liquid to the desired high place.

[Means to solve the problem]

The present invention has been made in view of these conventional problems, and its first purpose is to drain the air-containing sewage inside the tank, which is generated by cleaning sludge inside the crude oil tank, into a strainer box installed outside the tank. Once stored, the waste liquid and air are separated in this strainer box, and this air is exhausted to the outside of the strainer box by a vacuum pump, and the waste liquid that has settled at the inner bottom of the strainer box is discharged to the outside of the strainer box by a discharge pump. The objective is to improve the ability to drain waste liquid from the tank.

The second purpose is to automatically operate the attached vacuum pump and discharge pump by detecting the amount of air and liquid stored in the strainer box, and when the amount of air and liquid exceeds a predetermined amount. By adopting an intermittent drive means to increase pump drive energy savings.

〔Example〕

The present invention will be explained in detail below based on embodiments shown in the drawings.

In FIG. 1, 1 is a crude oil tank, and a cleaning liquid transfer vibrator 3 connected to a cleaning pump 2 for pumping cleaning liquid (oil) is piped to the outside of the ceiling of this crude oil tank 1. A plurality of branch pipes 4 to which a liquid suction port of an in-tank washer (not shown) can be connected are connected to the branch pipe 3 through respective valves 5. That is,
This cleaning pump is used to inject cleaning liquid from the cleaning machine into the tank, thereby dissolving the sludge that has settled in the tank 1.

The sludge thus dissolved is mixed with the cleaning liquid to become dirty liquid and is supplied into the strainer box 7 of the liquid drainage device 6 which is the gist of the present invention. Furthermore, this liquid drainage device 6
are arranged at appropriate positions in the outer circumferential direction of the tank 1. A liquid seal valve 9 and a first pressure switch 10 are connected in parallel to a pipe 8 provided on the upper surface of the strainer box 7, and a vacuum pump 11 is connected to the liquid seal valve 9 via a pipe 12. It is connected. Further, a discharge pump 14 such as a centrifugal pump is connected to the drain pipe 13 provided at the bottom of the strainer box 7, and a discharge pipe 15 connected to the discharge side of the discharge pump 14 is connected to a discharge pipe 14 such as a centrifugal pump. 2 pressure switches 16 are connected. Note that FIG. 3 shows an actual configuration diagram of the liquid draining device 6, and a strainer brush 71 is incorporated in the strainer box 7, and the strainer brush 7 can be rotated at appropriate times with a handle 72. By moving the strainer, impurities adhering to the inside of the strainer can be removed.

The above is the configuration of this embodiment.Next, we will discuss its operation.When cleaning the inside of the tank 1, when the vacuum pump 11 is driven to create a negative pressure inside the strainer box 7, this negative pressure effect As a result, the aerated liquid in the tank 1 is sequentially introduced into the strainer box 7, and the volume of the aerated liquid in the strainer box 7 increases. The upper layer inside this strainer box 7 becomes an air layer, and the lower layer becomes a liquid layer, and the amount of liquid inside this strainer box 7 becomes full. Since the pressure inside the strainer box 7 is increased by this filling action, this pressure increase is detected by the first pressure switch 10, and as a result, the vacuum pump is stopped and the discharge pump 14 is driven to cause the inside of the strainer box 7 to increase. sewage is discharged. By driving this discharge pump 14, the dirty liquid in the strainer box 7 is sequentially discharged, and when the dirty liquid in the strainer box 7 is exhausted, the discharge pressure of the dirty liquid by the discharge pump 14 becomes low. The pressure switch 16 detects this and stops driving the discharge pump 14. In addition, as the dirty liquid in the strainer box 7 is discharged, the strainer box 7 becomes negative pressure again, so this negative pressure state is detected by the first pressure switch, and the vacuum pump 11 is restarted. , the dirty liquid in the tank 1 is re-supplied into the strainer box 7. When the inside of the strainer box 7 becomes full and the pressure inside the strainer box increases, the pressure switch 1 of ¥%1
0 is operated, and as a result, the vacuum pump is stopped and the discharge pump 14 is driven, and the same liquid draining operation as described above is repeated.

〔Effect of the invention〕

As described above, the liquid draining method of the present invention includes a strainer box that communicates with the inside of the tank, a first pressure switch and liquid seal valve that are connected to piping provided on the top surface of this strainer box, and this liquid seal valve. A vacuum pump connected to the exhaust port side of the vacuum pump, a discharge pump connected to the piping provided at the bottom of the strainer box, and a second pressure switch connected to the discharge port side of the discharge pump are provided. The filthy liquid in the tank is introduced into the strainer box by the negative pressure in the strainer box due to the driving force of , and when the filthy liquid in the strainer box reaches a predetermined amount, the first pressure switch is operated to stop the vacuum pump and discharge it. Drive the pump to drain the waste liquid in the strainer box,
This reduction in the discharge pressure caused by the discharge pump causes the discharge pump to stop and the vacuum pump to be restarted. According to this method, the aerated liquid supplied to the strainer box 7 is mixed with air and the liquid. The effect is that the waste liquid is effectively separated and the waste liquid can be effectively drained by the discharge pump. In addition, the vacuum pump and discharge pump are operated intermittently and automatically according to the amount of sewage in the strainer box, which reduces the amount of drive energy required to drive the pumps and reduces labor costs. It is also movable and has the effect of providing an economical wastewater treatment method.

[Brief explanation of drawings]

7fS1 is an explanatory diagram showing an embodiment of the apparatus used to carry out the method of the present invention, FIG. 2 is an explanatory diagram of the route of the apparatus, and FIG. 3 is an explanatory side view of the apparatus. 1...Tank 2...Washing pump 3...
・Cleaning liquid transfer pipe 4...Branch pipe 5...Valve
6...Drainage device 7...Strainer box 8...Piping 9...Liquid seal valve 10...First pressure switch 11...Vacuum pump 12...Piping 13...
Drain pipe 14...Discharge pump 15...Discharge pipe 16...Second pressure switch and 4 others Fig. 2 11

Claims (1)

[Claims] 1 A strainer box that communicates with the inside of the tank, a first pressure switch and liquid seal valve that are connected to piping provided on the top surface of this strainer box, and a vacuum pump and strainer box that are connected to the exhaust port side of this liquid seal valve. A discharge pump connected to the piping provided at the bottom of the tank and a second pressure switch connected to the discharge port side of the discharge pump are installed. sewage is introduced into the strainer box, and when the sewage in the strainer box reaches a predetermined amount, the first pressure switch is operated to stop the vacuum pump and drive the discharge pump to drain the sewage in the strainer box. A method for discharging cleaning processing liquid, characterized in that the discharge pump is stopped and the vacuum pump is restarted due to the decrease in the discharge pressure caused by the discharge pump.