KR101023435B1 - Smart auto drain system of pneumatic tank - Google Patents

Abstract

PURPOSE: The intelligent auto-drain system of a compressive air tank for a pneumatic apparatus is provided to rapidly drain condensed water by precisely measuring the amount of condensed water in the tank. CONSTITUTION: The intelligent auto-drain system of a compressive air tank for a pneumatic apparatus includes a water level sensor(10), a controller(20), and a drain valve(30). The water level sensor detects the water level of condensed water based on an electric signal. The controller receives the detected water level. The drain valve is arranged at the water outlet of a compressive air tank and is operated by the controller.

Description

Smart auto drain system of pneumatic tank for pneumatic equipment

The present invention relates to a device for removing water (condensation water) in a tank of an air compressor, and includes a sensor for detecting a water level in a compressed air tank, a drain (drainage) control device linked to the sensor data, and an electronic drain valve. To a combined system.

An air compressor that supplies compressed air to a pneumatic machine sucks the surrounding air, compresses it using a reciprocating or turbine compression method, stores it in a tank, and then supplies it to the pneumatic pipe whenever necessary. It is structured to do.

Compressed air is an excellent energy storage medium stored in the tank, i.e. in the output standby state, which can be immediately supplied with maximum power to a large number of end-uses (power stages). It is possible and there is little risk of leakage before operation. Therefore, the pneumatic pipe network can be installed with a degree of freedom comparable to the electric network and can be operated at a low maintenance cost over the electric network.

However, condensed water is inevitably generated during cooling after adiabatic compression unless compressed air stored in the tank is subjected to advanced dehydration treatment by air combustion during suction. Condensed water flows into the pneumatic pipe as compressed air in the form of water and is sprayed inside the pneumatic machine, which causes rust and shortens the life of the machine. In addition, the air discharged through the pneumatic machines to the atmosphere is characterized by a rapid decrease in pressure and saturation (condensation) of the internal moisture. That is, the water rapidly condensed by rapid thermal expansion due to pressure drop is strongly sprayed on the surface of the workpiece in the form of larger water droplets, and has a very bad effect on the surface rust or paintability and corrosion resistance of the workpiece.

Therefore, most compressed air tanks are equipped with coke for discharging water (condensed water) at the bottom in order to minimize the moisture content of the stored air in the tank. Despite air loss, water must be drained periodically. In addition, the performance period of the draining operation should be flexibly adjusted according to the average absolute humidity and the total suction amount of the ambient atmosphere sucked during the total operation time of the compressor.

The oil supply device described in 2009 Patent No. 0939011, which is a prior application of the present inventors, has been invented to minimize the influence of moisture of the compressed air on the pneumatic device, and intelligently sprays lubricating oil or rust preventive oil on the pneumatic pipe to It has contributed to extending the life of pneumatic equipment from moisture.

The present invention, unlike the above-described invention of the invention to protect the pneumatic system by automatically supplying lubricating oil or rust preventive oil on the pneumatic pipe, relates to a technology for protecting the pneumatic system by automatically draining the condensed water in the compressed air tank as effectively as possible. In addition, the present invention relates to an optimal air compression storage technology capable of minimizing moisture accumulated in the entire pneumatic pipe and the pneumatic device as well as minimizing the amount of water injected into the workpiece.

(Patent 1) An air tank drain device for a vehicle brake that controls a drive valve by arranging a float (buoyancy body) in a tank and generating a detection signal according to a level rise. (Document 2) An air compressor for installing a drain valve in a condensed water discharge pipe and operating the drain valve by using an exhaust pressure according to overcharged air exhaust.

(Document 3) JP 20-1997-0002206 A compressor draining device using a drain control valve operating according to a timer setting time.

The drainage device of (1) does not have a compression tank for driving pneumatic machines, but has a similar purpose in that it aims to prevent corrosion of the mechanical parts inside the brake line by moisture. However, there is a technical limitation that relying on low-pressure, low-precision buoyancy bodies as a solution is possible only when the amount of condensation accumulated inside is considerably advanced. In other words, a float moving in a high-pressure compressed air is hard to make a small volume because it has a strong outer pressure-resistant material (usually a thin metal, which is not light in weight) and must float well in water. Therefore, the operation period is inevitably longer as the buoyancy stroke is large and the level detection accuracy is lowered accordingly.

The air compressor in (2) is limited to operating conditions only when the compression tank is in an overcharged state. However, most of the commercially available air compressors repeat the optimum operation of operating up to the set pressure and stopping almost precisely, so most of the cases of overcharging basically occur. In addition, when temporarily overcharged, the temperature of the compressed air in the tank is also very high due to the adiabatic compression effect, so that the condensation water is generated much less than usual due to the high saturated steam pressure of the compressed air. Therefore, draining (draining) immediately after the overcharge without any air in the tank is a waste of compressed air unnecessarily.

(3) The draining device of (3) is operated in accordance with the set time of the timer, regardless of the absolute humidity of the air to be compressed simply for a set time, for example, once a day, once every hour Configuration. Therefore, there is a high possibility of temporarily leaving the situation where excessive condensation occurs. Because the amount of condensation in the tank during the cooling process after adiabatic compression through the compressor varies greatly depending on the season, weather, and storage time. For example, the amount of condensation in the tank during winter, rainy season, wet or rainy days and dry This is because there is a big difference in the amount of condensation in the tank during the season and dry weather. Therefore, in order for the apparatus of Document 3 to be practically effective, an intelligent timer that operates at various operating cycles is required. The various operating cycles referred to here take into account not only the absolute humidity of the surrounding air, but also the total amount of air used at any given time and the total additional compressed amount, as well as the frequency and time of use of high-pressure precision machines and paint sprayers, which are more critical to moisture. Further construction of complex time programs is required.

After all, the key technical challenge to ultimately overcome the above technical limitations and economically remove residual water in the tank is to be able to measure the exact amount of condensate in the tank. However, it was very difficult to implement a technical means with simple and reliable quantity detection while being post-applied to various types of air compressor tanks already available or commercially available.

The present invention has solved the above problems by the following three technical means.

First, the condensed water in the tank is non pure water containing various inorganic ions or electrolytes by saturating water vapor contained in the ambient atmosphere. Therefore, considering that it is not an electrical insulator, current is generated when condensation water occurs in the tank after condensation occurs in the tank after the pair of energized terminals are separated from each other by a certain distance from the disconnected state. A water level detector means for detecting a change in value or a change in electrical resistance value and converting it into an electrical signal is introduced. At this time, the water level sensor is an elongated form that can be inserted into a narrow air outlet passage so that the existing manufacturer can easily install the ready-made pressure vessels that are manufactured and sold. It is placed as.

The water level sensor is characterized by being able to detect a change in the water level as well as the occurrence of the water level by arranging at least two pairs of energizing terminals having different lengths.

Next, an electric signal generated by the water level sensor is recognized as a level value generation, and a control unit and an electronic drain valve which are linked to and open and close the water discharge pipe are adopted.

In addition, due to the discharge structure in which compressed air escapes together in large quantities when condensate is discharged, the control flow rate of the condensed water level when opening the valve is a characteristic of the important control flow of the controller, which can theoretically make the condensate 0%. According to the magnitude of the rate of change of the water level compared to the pressure drop rate in the tank when opened, it is possible to determine the amount of water removal in the tank at this point and the economic efficiency of the water removal rate, and to intelligently control the flow back to the operation of the electronic drain valve. Added.

The present invention can be easily installed in a variety of high-pressure air tank regardless of shape and size, but can measure the amount of condensation in the tank with a relatively accurate, it can be discharged as soon as possible to the effective range.

In addition, the present invention can detect the change in the condensed water level during the discharge of condensed water or during the operation of the compressor, it is possible to grasp the ratio of the amount of condensed water actually discharged to the amount of air discharged with the condensed water in the discharge process in real time. Therefore, regardless of the capacity and type of tank, it has a function to determine the condensate level, which maximizes the discharge efficiency compared to the air loss of the tank, thereby enabling practical and economical water removal without wasting too much compressed air. Rather, it has the effect of providing a basis for estimating the range of capacities of tanks that can be used in a specific use environment from the dischargeable effective level value.

In addition, the present invention can be used in combination with the conventional operation by the time timer, the operation by the compressor power supply, and the amount of air consumption per hour in the pneumatic piping system requiring a high moisture removal. Furthermore, if deployed prior to all of the above mentioned modes of operation of the discharge means, it may serve as a practical safety device in hazardous situations that the discharge means do not cover (where the air in the tank temporarily exceeds the water allowance). It has an excellent effect.

1 is a circuit diagram showing a system configuration when the system of the present invention is in a standby state (no condensed water discharged state).
Fig. 2 is a circuit diagram showing the system configuration when the system of the present invention is in an operating state (condensed water discharged state).
3 is a cross-sectional view showing a state in which a water level sensor is mounted toward the air outlet (2).
4 is a sectional view showing a state in which a water level sensor is mounted toward the water discharge port 3;
5 is a graph showing the relationship between the change of the current sensing value of the level sensor and the level change in the tank.
6 is a control flowchart showing the operation principle of the control unit 20.
7 is a graph showing the relationship between the rate of change of the water level in the tank and the rate of decrease of the tank pressure according to the operation of the system of the present invention.

With reference to the embodiment of the present invention included in the drawings in order to technically support the above-described solution of the present invention will be described in detail.

However, in the following specific embodiments, the components including the specific terminology and combinations thereof do not limit the technical spirit inherent in the present invention.

The circuit diagram of FIG. 1 shows the system configuration when the auto-drain system of the present invention is in the standby state (no condensate discharge state), and FIG. 2 shows the system configuration in the operating state (condensate discharge state). It is shown.

Here, the water level sensor 10, which plays a key role in detecting a change in the condensed water level in the tank, operates in the principle of being energized when it is submerged in water and submerged in water.

Pure water is a nonconductor whose insulation resistance is theoretically infinite. However, this is an ideal case and the distilled water obtained in the experiments has a specific resistance ranging from 5 M 5.cm (mega ohm * cm) to 18.4 MΩ.cm, and in the case of saturated water in the pneumatic tank to which the present invention is applied, Water containing a large amount of various inorganic ions or electrolytes due to the metal components of the tank inner wall and the compressor inner wall in contact with dust and air.

Usually, the specific resistance of condensed water is much less than 1 MΩ.cm, which can be measured by a commercial tester such as a mega tester, a device for measuring the insulation resistance of materials with high specific resistance. The measuring method mainly applies a high voltage such as 1000V to measure the amount of minute current flowing at this time. In the present invention, the thickness of the conducting wire connecting between the conducting terminal and the ammeter is around 1.6mm, and when the pair of conducting terminal is submerged in water in the state of being insulated from the tank bottom with an insulator or the like, the mechanical industry The current measuring range of about 4 ~ 20mmA was obtained based on the applied voltage of a common ammeter used in the field. (Based on a pair of energizing terminals) When it is converted into an electrical signal and sent to the control unit 20, the control unit receives and processes it. The open signal is sent to the electronic (solenoid type) drain valve 30 disposed at the water outlet 3 of the compressed air tank.

When the condensed water level in the compressed air tank is increased as shown in FIG. 2, the controller 20 detects the condensed water from the current change amount or the voltage change amount flowing through the variable resistor, and gives an open command to the electronic drain valve 30. . Of course, in any case the condensed water level is not zero (since water is generated as it cools almost simultaneously with compression), so that condensed water generation here is interpreted as the significant level of water generation described in Figures 5 and 7 described below. Can be.

3 and 4 are cross-sectional views showing the tank mounting structure of the water level sensor 10 of the present invention. Most compressed air tanks have an air outlet (2) located at the top of the tank to prevent the condensed water from entering the inside when the stored air supply. Therefore, it is very easy to insert and fix the water level sensor 10 through the existing air outlet (2) as shown in FIG. Of course, it is necessary to connect the existing safety valve and the air supply pipe to the left and right by using a separately modified pipe joint.

The illustrated water level detector 10 arranges a power line insulated coated on an insulator 11a having an elongated rod shape up to a distal end thereof, and is connected to the power line and is exposed to air without an insulation coating. ) To combine. The conducting terminal pair is at least several mm away from the end of the insulator. Therefore, electricity is not energized through the bottom of the tank and only a small current flows when the pair of terminals is immersed in condensed water. Non-ferrous metals such as silver and copper are suitable because the conducting terminal pairs have high solubility and corrosion potential due to discharge, and the terminal ends are condensed by narrowing the terminal spacing and making the ends sharp so that they can be easily energized even at a relatively low voltage. It is desirable to design it in vertical contact with the water surface.

4 shows two types of water level detectors that can be inserted and installed toward the water outlet 3, and are designed to be smaller and easier to install than the water level sensors installed and inserted into the air outlet 2 of FIG. 3. If the water outlet 3 is not installed at the bottom of the tank, the additional insulator 11b that is bendable is further coupled to the insulator 11a, so that the bend angle opens naturally after insertion even if inserted into the water outlet below the tank. Can reach center

When the water outlet 3 is installed at the height of the tank bottom surface, the length of the insulator 11a is shortened and a simple and reliable structure is realized. 3 and 4, two to ten pairs or more of the pair of conductive terminals 12a and 12b connected to the power line may be additionally arranged at different lengths. In this case, as the condensed water level changes, the number of conductive terminal pairs contacting the surface of the condensed water is changed.As the condensed water level increases, the parallel connection is increased by many conducting terminal pairs, so the resistance decreases. More current flows through the.

Figure 5 is a graph showing the concept of easy to understand the level measurement according to the vertical arrangement of the energized terminal pair. If the current level of the level sensor is near 60mmA, it means that the three pairs of energized terminals are all 15mm or more in the energized state, and whenever the current level falls roughly (not a complete staircase), the level is lowered and energized. It can be seen that the energized terminal pair at is reduced to 2 pairs and 1 pair. In this way, it is possible to calculate the total amount of condensate present in the tank, which is difficult to observe inside, from the change in the current value.

6 is a control flow chart showing the operation principle of the control unit 20 of the present invention, Figure 7 is a graph deriving the drain valve opening time for the most economical condensate discharge pursuant to the control flow chart.

In the case of exceeding the allowable current value, which is the first determination step in FIG. 6, the condensed water discharge is started. Although not shown in Figure 6, at the same time the pressure change in the tank is also started and the pressure information in the tank is transmitted to the controller in real time as shown in Figures 1,2. Since the amount of air in the tank is very large compared to the amount of condensation, the pressure change is substantially linear as shown in FIG. 7, and the change in the condensation water level is represented by a curve. The condensed water level appears as a curve because the lower the condensed water level, the less condensed water emissions and the greater the amount of air released.

When the condensate is discharged by opening the drain valve and the water level is lowered, the number of pairs of energized terminals submerged below the surface is reduced and the value of energized current is decreased (larger insulation resistance). At this time, if the current value is input once again and compared with the maximum efficiency current value previously stored in the control unit, if it falls short of it, it means that the economic condensation water level which is set in advance is below. Therefore, the controller may close the drain valve 30 by determining that the rate of change of water level will be slower than this level. For example, this level can be set to a value close to the minimum level where the air level is near 5 mm and the air level is high and the level is hardly lowered.

Then, when a large amount of air loss, which is higher than the economic condensation water level, is unexpected, the control unit 20 may also close the drain valve. In the drawing, the step of obtaining the allowable current reduction rate is the key, where the allowable current reduction rate can be interpreted as the allowable level reduction rate, and this speed can be easily preset as the average pressure reduction rate (linear reduction) of the compressed air tank. If the present invention is set to be economical, the drain valve can be closed, although not satisfactory at this point. If the pneumatic machine or the material to be processed contains a lot of moisture during this operation, it may be because the volume of the compressed air tank is too large and the condensate level is too high even with the air at the same pressure, or the atmospheric humidity around the compressor installation site is high. It may be interpreted as high or a problem with the maintenance of the compressor. Therefore, it may be necessary to readjust the allowable current reduction rate or check the pneumatic system at another time.

While the embodiments of the present invention have been described in detail with reference to the drawings, the technical spirit of the present invention is not limited to the above embodiments.

In other words, those of ordinary skill in the art to which the present invention pertains can utilize the technical spirit contained in the specification and drawings of the present invention, and, if necessary, simply change and simplify the description and drawings of the present invention. Although extended examples may be implemented, these are also clearly included in the scope of the present invention as expressed by the following claims.

The present invention can be directly reflected in the design of the manufacturer in the production process of the air compressor including a tank, and also can be easily installed in the compressor already in use, so it is very marketable as a product for independent aftermarket. In addition, as an additional extension of the present invention, when implementing two or more stages of the multi-stage compressor, it is possible to remove condensed water by applying different water level values in the primary storage tank of the initial compressor and the secondary storage tank of the late compressor. It is possible to provide a cost-effective means of improving the performance of the cost-effective multi-stage air compressor that is comparable to the combustion type dehydration air compressor.

In addition, as an extended application form of the present invention, when combined with a residual moisture tester in compressed air, it can also be used as an air compressor performance meter to reach an acceptable amount of moisture in the air in a particular pneumatic system. For example, when an air compressor installed in a specific pneumatic system is operated, it is possible to perform a cumulative measurement experiment combining the present invention with a water tester to see if the water content allowance is met. At this time, if the air compressor is operated for a certain period of time while the water tolerance is kept constant, and the cumulative operating data of the auto drain system is analyzed, if the accumulated air charge amount is significantly higher than the total water level change value (condensate removal amount), the specific air pressure In a system environment, it may be determined that the compression scheme of the air compressor is not suitable or that the tank capacity is uneconomically large.

1: compressed air tank
2: air outlet 3: water outlet
PG: Pressure gauge M: Motor
C: Compressor AC: Power
A: Ammeter V: Voltmeter
10: water level detector
11 (a, b): Insulator 12 (a, b): Current pair
20: control unit 30: drain valve

Claims (4)

delete It is arranged to reach the inner bottom of the compressed air tank (1), the water level sensor 10 for detecting the water level by the electrical signal generated by applying a voltage or current; and the water level sensor A controller 20 to which one level value is input; And a drain valve 30 disposed at the water discharge port 3 of the compressed air tank and operated by the control unit.
The water level detector 10 is inserted into and fixed to the tank through an air outlet 2 or a water outlet 2 of the compressed air tank, and at least one conducting terminal pair 12a and 12b are disposed at intervals. An auto drain system for a compressed air tank, further comprising (11a). The water level sensor 10 of claim 2,
Compressed air, characterized in that it further comprises at least one bendable additional insulator (11b), wherein the pair of conducting terminal pairs (12a, 12b) of two to 10 pairs of different lengths are arranged at intervals. Tank's auto drain system. The method of claim 3, wherein the control unit 20,
When the drain valve 30 is closed when the average reduction speed of the condensation water level is less than or equal to a preset allowable speed, or when the average reduction speed of the condensation water level is less than the pressure reduction speed of the compressed air tank 1. Auto drain system of the compressed air tank, characterized in that for closing the drain valve (30).

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