Foam prevention and removal device for ECS probe level sensor

Abstract

The foam prevention and removal device for the ECS probe type liquid level sensor comprises an ECS tank body, a foam removal device, a foam removal device and a foam removal device, wherein liquid is arranged in the ECS tank body; the foam removing device is connected to the inner side wall of the ECS tank body, and the bottom of the foam removing device is immersed in the liquid; the foam removing device comprises an overflow tank and a liquid storage tank which are communicated with each other at the lower end of the side wall. Aiming at the defects in the existing production technology, the foam prevention and removal device of the ECS probe type liquid level sensor is provided, the liquid level of an ECS tank body is indirectly reflected by detecting the liquid level in an overflow tank, and the accuracy and the stability of liquid level detection are improved; meanwhile, external interference is effectively isolated, the possibility of foam generation is reduced, and the cleanliness of washing liquid is guaranteed; and compressed air can be periodically introduced to remove overflow foam, so that the accumulation of the internal foam after long-time operation is prevented, and the compressed air is prevented from directly entering the overflow groove to generate new bubbles.

Description

Technical Field

[0001] The utility model relates to the technical field of wet etching, in particular to a foam prevention and removal device for an ECS probe type liquid level sensor. Background Art

[0002] In the semiconductor industry, since harmful gases are always inevitably generated when wet etching equipment is working, the factory must always provide air volume and air pressure to take away the harmful gases for treatment and then discharge. However, the air volume and air pressure provided by the factory are limited, which is not conducive to the treatment and discharge of harmful gases.

[0003] This requires a device, namely ECS, the full name is Exhaust Control System. ECS is a small and independent tail gas cleaning device, which is responsible for providing stable process air pressure and air volume for the main machine platform and treating the waste gas generated by the main machine platform. Before tail gas cleaning, various cleaning liquids are often used. The water (cleaning liquid) added with the liquid is sucked by a water pump in the ECS tank 200, then sprayed and finally flows back into the tank. In this circulation process, foam is easily and inevitably generated on the surface of the cleaning liquid. These foams will inevitably affect the ECS probe type liquid level sensor (brand: Keyence, model: FL-CP40) that must be used in the ECS electrical control, resulting in inaccurate real-time liquid level measurement or false alarm, thus seriously affecting the process. Referring to the Keyence ECS probe type liquid level sensor instruction manual, it is clearly stated in the manual that "If substances in the medium adhere to the probe in excess, it may cause unstable detection. At this time, please clean the probe to remove the adherents."

[0004] Therefore, we propose a foam prevention and removal device for an ECS probe type liquid level sensor. Summary of the Utility Model

[0005] The applicant of the present utility model aims at the above-mentioned disadvantages in the existing production technology and provides a foam prevention and removal device for an ECS probe type liquid level sensor. By detecting the liquid level in the overflow tank to indirectly reflect the liquid level in the ECS tank, the accuracy and stability of liquid level detection are improved; at the same time, external interference is effectively isolated, the possibility of foam generation is reduced, and the cleanliness of the cleaning liquid is ensured; in addition, the design of periodically introducing compressed air to remove the overflow foam not only prevents the accumulation of internal foam after long-term operation, but also avoids the direct entry of compressed air into the overflow tank to generate new bubbles.

[0006] The technical solution adopted by the present utility model is as follows:

[0007] It includes: an ECS tank, in which a liquid is provided; and,

[0008] A foam removal device is connected to the inner side wall of the ECS tank, and the bottom of the foam removal device is immersed in the liquid.

[0009] The foam removal device includes an overflow tank and a liquid storage tank with their lower side walls interconnected. Multiple main liquid inlets for docking with the ECS tank are also connected to the lower side wall of the overflow tank. An overflow port is provided on the side wall of the overflow tank above the liquid level. An air inlet / outlet for air pressure communication with the outside is provided on the top wall of the liquid storage tank.

[0010] Multiple liquid pushing ports are provided at the lower end of the connection surface between the overflow tank and the liquid storage tank.

[0011] Its further features are as follows:

[0012] The liquid pushing ports and the main liquid inlets are opposite to each other, and the number of main liquid inlets is less than that of the liquid pushing ports.

[0013] Both the liquid pushing ports and the main liquid inlets are arranged in an array, and the number of liquid pushing ports is twice that of the main liquid inlets.

[0014] The foam removal device is at the same height as the inner cavity of the ECS tank.

[0015] A three-way joint is provided on the air inlet / outlet for respectively docking high-pressure air and normal-pressure air.

[0016] A liquid level sensor installation port is provided on the top of the overflow tank, and an ECS liquid level sensor extending into the overflow tank to measure the liquid level is inserted into the liquid level sensor installation port.

[0017] It further includes an electrical control system, including a circuit component and a gas circuit component, which are the basis for realizing control.

[0018] The height of the overflow port is between the normal operating liquid level and the alarm liquid level of the ECS tank, and the alarm liquid level is greater than the normal operating liquid level.

[0019] The beneficial effects of the present utility model are as follows:

[0020] The structure of the utility model is compact and reasonable, and it is convenient to operate. Through the liquid level balance principle, the accurate monitoring and control of the liquid level in the ECS tank are realized. Its beneficial effects are mainly reflected in the following aspects: First, by detecting the liquid level in the overflow tank to indirectly reflect the liquid level in the ECS tank, the accuracy and stability of liquid level detection are improved; Second, the design of the overflow tank and the liquid storage tank effectively isolates external interference, reduces the possibility of foam generation, and ensures the cleanliness of the washing liquid; Third, the design of periodically introducing compressed air to remove overflow foam not only prevents the accumulation of internal foam after long-term operation but also avoids the direct entry of compressed air into the overflow tank to generate new bubbles; Fourth, the application of the internal algorithm of the PLC effectively shields the abnormal detection of the liquid level sensor during the overflow process and ensures the accuracy of liquid level detection; Fifth, the overall structure is compact, the operation is simple, the maintenance cost is low, and it has high practical value and popularization value. Brief Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of the utility model.

[0022] Figure 2 It is a cross-sectional view of the foam removal device in the utility model.

[0023] Wherein:

[0024] 100. Foam removal device; 200. ECS tank

[0025] 1. Overflow port; 2. Overflow tank; 3. Main liquid inlet; 4. Air inlet and outlet; 5. Liquid storage tank; 6. Liquid pushing port 6; 7. Liquid level sensor installation port; 8. Liquid level sensor. Specific Embodiments

[0026] The following combines the drawings to illustrate the specific embodiments of the utility model.

[0027] As Figure 1 - Figure 2 shown, this embodiment discloses a foam prevention and removal device for an ECS probe type liquid level sensor. The structure of this device is simple and ingenious. The additional auxiliary device is only a tee at the air inlet end and a corresponding matching electric control valve. Therefore, neither mechanical installation nor electrical control will be difficult. This device can be directly welded and installed inside the ECS tank 200 during the ECS production process, which can save the back panel, bottom panel, and upper panel to achieve the purpose of integration. Of course, this device can also be directly customized for production and installed in the equipment tank that uses an ECS probe type liquid level sensor and needs to remove foam. This device can not only prevent foam from adhering to the probe of the liquid level sensor but also isolate the interference of the surging liquid surface in the ECS tank 200 on the measurement.

[0028] As Figure 1As shown, it includes: an ECS tank body 200 with liquid therein; and,

[0029] A foam removal device 100, which is connected to the inner side wall of the ECS tank body 200, and the bottom of the foam removal device 100 is immersed in the liquid;

[0030] The foam removal device 100 includes an overflow tank 2 and a liquid storage tank 5 with their lower side walls communicating with each other. The lower side wall of the overflow tank 2 is also connected with a plurality of main liquid inlets 3 docked with the ECS tank body 200. An overflow port 1 is provided on the side wall of the overflow tank 2 above the liquid level. An air inlet and outlet 4 for air pressure communication with the outside is provided on the top wall of the liquid storage tank 5.

[0031] A plurality of liquid pushing ports 6 are provided at the lower end of the connection surface between the overflow tank 2 and the liquid storage tank 5.

[0032] The liquid pushing ports 6 and the main liquid inlets 3 are opposite to each other, and the number of the main liquid inlets 3 is less than that of the liquid pushing ports 6.

[0033] Both the liquid pushing ports 6 and the main liquid inlets 3 are arranged in an array, and the number of the liquid pushing ports 6 is twice that of the main liquid inlets 3.

[0034] The foam removal device 100 is at the same height as the inner cavity of the ECS tank body 200.

[0035] A three-way joint is provided on the air inlet and outlet 4 for respectively docking high-pressure air and normal-pressure air.

[0036] A liquid level sensor installation port 7 is provided on the top of the overflow tank 2, and an ECS liquid level sensor 8 extending into the overflow tank 2 and measuring the liquid level is inserted into the liquid level sensor installation port 7.

[0037] It also includes an electrical control system, including a circuit component and a gas circuit component, which is the basis for realizing control.

[0038] The height of the overflow port 1 is between the normal operating liquid level and the alarm liquid level of the ECS tank body 200, and the alarm liquid level is greater than the normal operating liquid level.

[0039] In this embodiment, the specific structural functions are as follows:

[0040] ECS tank body 200: The carrier of the foam removal device 100;

[0041] Foam removal device 100: Install the ECS probe type liquid level sensor 8 and achieve the purpose of removing foam;

[0042] Overflow tank 2: Store and isolate the cleaning liquid in the ECS tank body 200;

[0043] Overflow port 1: ①Overflow the foam in the overflow tank 2, ②Balance the air pressure to make the liquid levels in the overflow tank 2 and the ECS tank body 200 consistent;

[0044] Main liquid inlet 3: ① Feeds liquid into the overflow tank 2; ② Feeds liquid into the liquid storage tank 5.

[0045] Liquid pushing port 6: ① Pushes the cleaning liquid in the liquid storage tank 5 into the overflow tank 2; ② Feeds liquid into the liquid storage tank 5.

[0046] Liquid storage tank 5: Stores and isolates the cleaning liquid, and is used to push out the liquid in the overflow tank 2 to remove foam; Air inlet and outlet 4: It is arranged at the top of the liquid storage tank 5, and a tee is connected to the air inlet and outlet 4.

[0047] ① Only one end of the tee extends into the liquid storage tank 5. One end of the tee outside the liquid storage tank 5 is connected to the compressed air pipe. The cleaning liquid in the liquid storage tank 5 is pushed out by introducing compressed air; The other end of the tee outside the liquid storage tank 5 is connected to a normally open electric control valve, which is used to balance the air pressure so that the liquid levels in the liquid storage tank 5 and the ECS tank body 200 are almost the same; Normally open electric control valve: Controlled by the PLC, it is powered on and closed when compressed air is blown in, and powered off and open at other times.

[0048] PLC control system: Controls the blowing-in of compressed air and the opening and closing of the electric control valve through the PLC to achieve the purpose of periodically overflowing to remove foam.

[0049] Electrical control system: Composed of a circuit part and a gas path part, which is the basis for realizing control.

[0050] Description of the structure and mutual position:

[0051] Regarding the foam removal device 100 for the ECS probe type liquid level sensor 8, it is installed at the initial installation position of the ECS probe type liquid level sensor according to the actual working conditions.

[0052] The main process structure components of this device include:

[0053] Since the initial design of this device is for the ECS, the control logic is based on the ECS as the reference object. The depth of the ECS tank body 200 is about 500 mm. For every 1 mm increase in the liquid level in the tank body design, the liquid increases by about 2.4 L. The detection period of the ECS probe type liquid level sensor 8 is 4 s / time, the detection accuracy is 1 mm, and the liquid inlet and outlet rate < 0.5 L / S. Therefore, the liquid in the overflow tank 2 has enough time to reach the same height as the liquid in the ECS tank body 200. The cleaning liquid is clean without solid impurities, so the main liquid inlet 3 and the liquid pushing port 6 of the device will not be blocked.

[0054] The above proves the rationality of obtaining the liquid level of the ECS tank body 200 by detecting the liquid level in the overflow tank 2 for this device.

[0055] When the ECS is operating normally, the liquid level is 195mm - 290mm, and the equipment alarm liquid level is 350mm. Therefore, the height of the overflow port 1 is designed to be 310mm, that is, the lowest height of the overflow port 1 is between the normal operating liquid level and the alarm liquid level.

[0056] The cleaning liquid in the ECS tank 200 flows into the overflow tank 2 through the main liquid inlet 3 at the lower end of the foam removal device 100, and the air pressure in the overflow tank 2 is balanced by the overflow port 1; the normally open solenoid valve at the upper right end of the tee connected by the air inlet and outlet 4 balances the air pressure in the liquid storage tank 5, so that the cleaning liquid slowly flows from the overflow tank 2 into the liquid storage tank 5. Finally, the liquid levels of the ECS tank 200, the overflow tank 2, and the liquid storage tank 5 are almost the same. Since the cleaning liquid enters from the lower end of the device and is isolated by the overflow tank 2, the possibility of generating foam in the overflow tank 2 has been greatly reduced. The liquid storage tank 5 has only one air inlet and outlet 4 at the top and the liquid is fed in from the lower liquid pushing port 6, and the rest is almost completely isolated from the external cleaning liquid, so it will not generate foam due to external influence.

[0057] To prevent the generation of foam in the overflow tank 2 that cannot be removed after long-term operation, it is controlled by the PLC to periodically (according to the actual situation, for example, after the equipment continuously operates for 72 hours, and the liquid level is at 290mm or close to the position of the overflow port 1 for easy overflow) open the solenoid valve to introduce compressed air into the air inlet and outlet 4 (the appropriate air pressure can be adjusted by a mechanical pressure regulating valve or a throttle valve first), and at the same time close the normally open solenoid valve at the right end of the tee to push out the cleaning liquid in the liquid storage tank 5 (the duration is controlled by the PLC according to the actual situation to ensure that it is not all pushed out to prevent compressed air from entering the overflow tank 2 and generating bubbles). Since the number of openings of the liquid pushing port 6 is twice that of the main liquid inlet 3, after the compressed air is introduced, the cleaning liquid in the overflow tank 2 will flow out from both the main liquid inlet 3 and the overflow port 1. Since the liquid volumes in the liquid storage tank 5 and the overflow tank 2 are the same in the balanced state, there is enough cleaning liquid flowing out from the overflow port 1 to carry away the foam in the overflow tank 2. After the overflow ends, close the solenoid valve of the air inlet and outlet 4 and open the normally open solenoid valve at the right end of the tee.

[0058] During the entire process of overflowing foam, due to the sudden change of the liquid level in the overflow tank 2, to prevent the ECS probe type liquid level sensor 8 from detecting abnormal liquid levels, the liquid levels detected by the liquid level sensor during this process are shielded by the internal algorithm of the PLC. After a few seconds of delay after the overflow ends (when the liquid level in the overflow tank 2 is the same as that in the ECS tank 200), the PLC algorithm shielding ends. At this time, since the air inlet and outlet 4 is small, the process of the liquid in the liquid storage tank 5 flowing back and filling through the overflow tank 2 is relatively slow, and the filling rate is much lower than the rate at which the cleaning liquid in the ECS tank 200 enters the overflow tank 2.

[0059] The above description is an explanation of the present invention, not a limitation of the invention. The scope defined by the present invention is referred to the claims, and any form of modification can be made within the protection scope of the present invention.

Claims

1. Foam prevention and removal device for ECS probe type liquid level sensor, characterized in that, Comprising: An ECS tank body (200) with liquid provided therein; And A foam removal device (100) connected to the inner side wall of the ECS tank body (200), and the bottom of the foam removal device (100) is immersed in the liquid; The foam removal device (100) includes an overflow tank (2) and a liquid storage tank (5) with their lower side walls communicating with each other; The lower side wall of the overflow tank (2) is further connected with a plurality of main liquid inlets (3) docked with the ECS tank body (200), and an overflow port (1) is provided on the side wall of the overflow tank (2) above the liquid level, and an air inlet and outlet port (4) for air pressure intercommunication with the outside is provided on the top wall of the liquid storage tank (5).

2. The foam prevention and removal device for the ECS probe type liquid level sensor according to claim 1, characterized in that: A plurality of liquid pushing ports (6) are provided at the lower end of the connection surface between the overflow tank (2) and the liquid storage tank (5).

3. The foam prevention and removal device for the ECS probe type liquid level sensor according to claim 2, characterized in that: The liquid pushing ports (6) are opposite to the main liquid inlets (3), and the number of the main liquid inlets (3) is less than that of the liquid pushing ports (6).

4. The foam prevention and removal device for the ECS probe type liquid level sensor according to claim 3, characterized in that: Both the liquid pushing ports (6) and the main liquid inlets (3) are arranged in an array, and the number of the liquid pushing ports (6) is twice that of the main liquid inlets (3).

5. The foam prevention and removal device for the ECS probe type liquid level sensor according to claim 1, characterized in that: The foam removal device (100) is at the same height as the inner cavity of the ECS tank body (200).

6. The foam prevention and removal device for the ECS probe type liquid level sensor according to claim 1, characterized in that: A three-way joint is provided on the air inlet and outlet port (4) for respectively docking high-pressure air and normal-pressure air.

7. The foam prevention and removal device for the ECS probe type liquid level sensor according to claim 1, characterized in that: A liquid level sensor mounting port (7) is provided on the top of the overflow tank (2), and an ECS liquid level sensor (8) extending into the overflow tank (2) and measuring the liquid level is inserted into the liquid level sensor mounting port (7).

8. The foam prevention and removal device for the ECS probe type liquid level sensor according to claim 1, characterized in that: It further includes an electrical control system, including a circuit component and a gas circuit component, which is the basis for realizing control.

9. The foam prevention and removal device for the ECS probe type liquid level sensor according to claim 1, characterized in that: The height of the overflow port (1) is between the normal operating liquid level and the alarm liquid level of the ECS tank body (200), and the alarm liquid level is greater than the normal operating liquid level.

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