JP7818296B2 - Drain discharge structure - Google Patents

Description

The present invention relates to a drain discharge structure, and more specifically to technology for collecting CO2 when drain is discharged.

In a compressed air circuit, when drain is discharged using a drain trap or the like, CO2 contained in the drain is adsorbed, thereby reducing CO2 in the atmosphere.
One possible method is to dissolve a larger amount of CO2 in the drain and then adsorb the CO2 in the drain in an adsorption tank.
However, the CO2 that did not dissolve was released into the atmosphere, so it could not be said that the adsorption was sufficient.
Furthermore, as the air pressure inside the drain pipe fluctuates, the amount of CO2 dissolved in the drain also changes, making it difficult to determine efficient adsorption performance in liquid and air.
Therefore, there was a need for a technology that could efficiently adsorb CO2 in liquids and CO2 in the air.

Various proposals have been made for such technology. For example, a drain discharge structure (see Patent Document 1) has been proposed and is a publicly known technology. More specifically, this technology involves making the diameter of a collecting pipe smaller than the diameter of the discharge pipe when collecting drain from multiple devices in a compressed air pressure circuit, thereby increasing the dissolution of CO2 into the drain and adsorbing oil and CO2 in the liquid in a tank, thereby increasing the CO2 adsorption efficiency.
However, CO2 remaining in the air cannot be adsorbed, and the above problem has not yet been solved.

Patent No. 7496150

In consideration of the above problems, the present invention aims to provide a drain discharge structure that stabilizes the ratio of CO2 in the liquid to CO2 in the air in a compressed air pressure circuit and enables efficient adsorption of CO2 in both the liquid and the air.

To solve the above-mentioned problems, the present invention provides a drain discharge structure comprising: a discharge pipe through which drain and compressed exhaust gas discharged from devices arranged in a compressed air circuit flow; a collecting pipe that sends the combined drain and compressed exhaust gas flowing in from one or more of the discharge pipes to a downstream oil and CO2 absorption tank; and an oil and CO2 absorption tank that purifies the drain and compressed exhaust gas flowing in from the collecting pipe. Each discharge pipe is provided with a drain trap, and while the drain trap is open, the volume of the discharge pipe with the open drain trap is smaller than the volume of the collecting pipe. The drain and compressed exhaust gas undergo a pressure drop as they move from the discharge pipe to the collecting pipe. The piping after the collecting pipe is open or nearly open, and the drain and compressed exhaust gas maintains its pressure drop. The oil and CO2 absorption tank has a section that adsorbs oil and CO2 in the drain and a section that adsorbs CO2 in the compressed exhaust.

The present invention also employs a means for making the cross-sectional area of the discharge pipe smaller than the cross-sectional area of the collecting pipe.

Furthermore, the present invention employs a control unit in which the drain traps each have a water level sensor, a solenoid valve that opens and closes each drain trap, and a time element related to the opening and closing time of the drain traps and a water level element related to the drain water level in each drain trap, and employs a means of control to discharge drain from only one drain trap and to prevent multiple drain traps from opening and closing simultaneously.

Furthermore, the present invention has a pressure sensor that detects the pressure inside the collecting pipe, and the control unit employs means for opening one drain trap to discharge condensate into the collecting pipe when the pressure inside the collecting pipe falls below a certain value.

The drain discharge structure of the present invention stabilizes the ratio of CO2 in the liquid to CO2 in the air, allowing for efficient adsorption of CO2 in both the liquid and the air.

1 is an overall view showing a schematic embodiment of a drain discharge structure according to the present invention; 1 is a schematic diagram showing the state of CO2 and oil in a pipe in a drain discharge structure according to the present invention. FIG. 1 is an overall view showing a specific embodiment of a drain discharge structure according to the present invention;

The drain discharge structure according to the present invention has the greatest feature of being able to efficiently adsorb CO2 in the drain.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a drain discharge structure according to the present invention will be described with reference to the drawings.
The overall configuration and the configuration of each part of the drain discharge structure according to the present invention are not limited to the examples described below, but can be modified as appropriate within the scope of the technical idea of the present invention, i.e., within the scope of shapes, dimensions, structures, etc. that can achieve the same functional effects.

The present invention will be described with reference to FIGS.
FIG. 1 is an overall view showing a schematic embodiment of a drain discharge structure according to the present invention.
2A and 2B are schematic diagrams showing the state of CO2 and oil in the pipes in the drain discharge structure according to the present invention, where (a) is a schematic cross-sectional view of the discharge pipe and (b) is a schematic cross-sectional view of the collecting pipe.
FIG. 3 is an overall view showing a specific embodiment of the drain discharge structure according to the present invention, and shows a case where a control unit is provided.
The drain discharge structure 1 is a structure that collects drains from various devices in a compressed air circuit, adsorbs oil and CO2, and discharges them.
The compressed air circuit includes devices such as an air compressor 2, an air tank 3, an air dryer 4, and an air filter 5, and the air tank 3, the air dryer 4, and the air filter 5 discharge drain D. There is a drain trap 20 that temporarily retains the discharged drain D, a collecting pipe 25 that collects the drain D from each device, and an oil and CO2 absorption tank 30 that processes the drain D from the collecting pipe 25.

The air compressor 2 is a device that compresses atmospheric air to generate compressed air and sends it to a subsequent stage.
There are various types of air compressors 2, such as reciprocating, rotary, centrifugal, and axial flow types, depending on the structure for generating compressed air. Furthermore, among these various types, there are oil-supplied types that use lubricating oil and oil-free types that do not use lubricating oil.
The air compressor 2 draws in atmospheric air through an air intake port, increases the pressure to a predetermined value (e.g., 0.7 MPa), and compresses it. Because atmospheric air contains water vapor and foreign matter suspended in the air, the compressed air discharged from the air compressor 2 will naturally contain water vapor and foreign matter.
The compressed air generated by the air compressor 2 is sent to the air tank 3 .

The air tank 3 is a tank that temporarily stores compressed air and then sends it to a downstream stage. The provision of the air tank 3 stabilizes the pressure of the compressed air being sent, which helps to suppress the water hammer effect of the fluid (compressed air) when starting or stopping the air compressor 2, and helps to reduce the load on the air dryer 4 and other compressed air-using equipment connected downstream.
The temporarily stored compressed air is sent to the air dryer 4.

The air dryer 4 is a device that cools the compressed air sent from the air tank 3 by utilizing the latent heat of evaporation of the refrigerant, condenses the moisture contained in the compressed air, and removes it as drain.
The air dryer 4 may be of a refrigeration type, hollow fiber membrane type, adsorption type, or the like, depending on the moisture removal method. The air dryer 4 used in the present invention may be of any of the refrigeration type, hollow fiber membrane type, and adsorption type, and is not particularly limited, but the most commonly used is a refrigeration type air dryer. A refrigeration type air dryer is a device that uses the latent heat of evaporation of a refrigerant to cool the compressed air A and condense and remove the contained moisture, and is therefore preferable because it can be introduced relatively inexpensively.
The compressed air from which moisture has been removed by the air dryer 4 is then sent to the air filter 5.

Air filters separate and remove dust particles contained in compressed air. The specific structure and materials of such air filters can be any structure that separates dust particles from compressed air, and filters made using conventional technology such as laminated nonwoven fabrics or wool-like polyester can be used.

The drain trap 20 is provided in the air tank 3, the air dryer 4, and the air filter 5 to discharge drain generated in each device such as a refrigerated air dryer.
A small amount of compressed air is also discharged along with the drain. This compressed air is called compressed exhaust air.
By providing the drain trap 20 at the bottom of the equipment, it is possible to efficiently discharge the drain that hangs down due to gravity to the outside via the drain trap 20, and it also contributes to improving maintainability. The drain trap 20 may be, for example, an electromagnetic type, a float type, or a disk type.
A pipe for a drain trap 20 is provided at the bottom of each compressed air device, and a valve 23 is disposed therein for use in restricting drain discharge from each device.
The valve 23 is connected to the inlet pipe 21 , which is connected to the inlet of the drain trap 20 .
By opening the valve 23, the drain generated inside the equipment is allowed to drip into the drain trap 20 as needed.
The drain accumulated in the drain trap 20 is discharged from the discharge pipe 22 as needed, depending on the amount of accumulated drain, etc. At this time, a portion of the compressed exhaust gas is also discharged.
The drain discharged to the discharge pipe 22 is at high pressure, so it passes through the check valve 24 as is and enters the collecting pipe 25 .

The drain pipes 22 that discharge the drain D from each device are all connected to and combined into a collecting pipe 25. The drain D combined in the collecting pipe 25 is sent to an oil and CO2 absorption tank 30.
A check valve 24 is disposed at the connection point from the discharge pipe 22 to the collecting pipe 25. By providing the check valve 24, the drain D in the collecting pipe 25 does not flow back to the discharge pipe 22 side, so that the drain D can be discharged from the drain trap 20 without any problems.
The volume of the collecting pipe 25 is larger than the volume of any of the discharge pipes 22. Therefore, when the drain and compressed exhaust gas flow from the discharge pipes 22 into the collecting pipe 25, the pressure on the drain and compressed exhaust gas decreases.
If the lengths of the collecting pipe 25 and the discharge pipe 22 are approximately the same, the cross-sectional area of the collecting pipe 25 can be made larger than the cross-sectional area of the discharge pipe 22, thereby making the volume of the collecting pipe 25 larger than the volume of the discharge pipe 22.

The oil and CO2 adsorption tank 30 is a tank that adsorbs oil and CO2 in the drain and adsorbs CO2 in the compressed exhaust gas.
The oil and CO2 adsorption tank 30 comprises an oil and CO2 adsorption section 31 and a gaseous CO2 adsorption section 32 .
The oil and CO2 adsorption section 31 is a section that adsorbs oil and CO2 in the liquid, and occupies the lower half of the oil and CO2 adsorption tank 30 .
For example, by forming the nonwoven fabric into a strip of laminated amine-impregnated nonwoven fabric, the liquid can come into contact with a large amount of nonwoven fabric, so that the oil and CO2 in the drain can be efficiently collected in the oil/CO2 adsorption section 31.
The gaseous CO2 adsorption section 32 is a section that adsorbs CO2 in the compressed exhaust gas, and occupies the upper half of the oil and CO2 adsorption tank 30.
For example, by using a mineral band such as activated carbon or zeolite, CO2 in the compressed exhaust gas can be efficiently adsorbed. If oil is contained in the compressed exhaust gas, it will adhere to the micropores in the mineral band and block the micropores, reducing the CO2 adsorption performance. However, because the oil is adsorbed in the oil/CO2 adsorption section 31, the reduction in adsorption rate due to the oil is small.

Drain from each device passes through a valve 23 and an inlet pipe 21 and enters the drain trap 20. When a certain amount of drain accumulates in the drain trap 20, the drain trap 20 discharges the drain D and compressed exhaust gas into a discharge pipe 22.
The drain and compressed exhaust gas that enter the discharge pipe 22 are sent to a collecting pipe 25 via a check valve 24 by compressed air pressure.
Since the volume of the collecting pipe 25 is larger than the volume of each exhaust pipe 22, the pressure of the drain and compressed exhaust gas decreases as it enters the collecting pipe 25. Then, due to the action described below, the CO2 in the compressed exhaust gas increases appropriately.
The piping after the collecting pipe is in an open state or a state close to an open state, so that the drain and compressed exhaust maintain a state of pressure drop.
When the drain trap 20 is activated, the CO2 accumulated in the collecting pipe 25 and the CO2 dissolved in oil are caused to flow into the oil and CO2 adsorption tank 30 by compressed air under pressure.
In the oil and CO2 adsorption tank 30 , the oil and CO2 in the drain D are adsorbed in the flowing CO2 outflow pipe 40 , and the CO2 that has increased moderately during the compressed exhaust is adsorbed in the gaseous CO2 adsorption section 32 .
In the oil and CO2 adsorption tank 30, both the CO2 in the drain D and the CO2 in the compressed exhaust gas are adsorbed, so the amount of CO2 in the flowing CO2 outflow pipe 40 can be made extremely small.

When the drain traps 20 open and send the drain to the collecting pipe 25, if multiple drain traps 20 open simultaneously, the volume of the discharge pipe 22 may become larger than the volume of the collecting pipe 25. This may result in no pressure drop in the drain, etc., and no increase in the CO2 being compressed and exhausted, which may reduce the adsorption effect of the gaseous CO2 adsorption section by half.
However, in many cases, the time during which the drain trap 20 is open is much shorter than the time during which it is closed, and it is rare for multiple drain traps 20 to open at the same time.
Therefore, without performing special sensor control or the like, only one of the drain traps 20 can be opened to discharge the drain into the collecting pipe.

The relationship between the amount of CO2 in the drain and the discharge pipe 22 and the collecting pipe 25 will be described with reference to FIG.
2A is a schematic diagram showing drain, CO2, and oil in the discharge pipe 22, with oil U and CO2 dissolved in the drain D. Some CO2 is also contained in the air.
Figure 2(b) is a schematic diagram showing the drain, CO2, and oil in the collecting pipe. The upper half of the collecting pipe contains CO2 gas, and the lower half contains drain (liquid) and dissolved oil and dissolved CO2.
In FIG. 2(a), according to Henry's law, CO2 is dissolved in the drain at a pressure equivalent to the compressed air pressure.
The drain D and compressed exhaust air flow from the discharge pipe 22 to the collecting pipe 25. The volume and cross-sectional area of the collecting pipe 25 are larger than those of the discharge pipe 22, so the pressure is reduced accordingly. According to Henry's law, CO2 gas equivalent to the reduced pressure in the drain is released into the air. Oil and CO2 equivalent to the reduced pressure remain dissolved in the drain.
Therefore, the proportion of CO2 in the air increases by the amount of pressure reduced.
Furthermore, the piping after the collecting pipe 25 is in an open state or a state close to that, so the pressure drop state is maintained.
Since the drain is nearly open, the pressure in the drain is roughly the same as atmospheric pressure. According to Henry's law, the amount of CO2 in the drain is equivalent to atmospheric pressure.

Since the pressure is reduced to about atmospheric pressure in the collecting pipe 25, the ratio of CO2 in the drain to CO2 in the air becomes approximately the same as the ratio of CO2 in the liquid to CO2 in the air in the atmosphere.
The oil and CO2 adsorption section 31 of the oil and CO2 adsorption tank 30 adsorbs the CO2 and oil in the drain, and the gaseous CO2 adsorption section 32 adsorbs the CO2 in the air. By making the ratio of the adsorption amounts the same as the ratio of CO2 in the liquid to CO2 in the air at atmospheric pressure, it is possible to adsorb CO2 in the liquid and CO2 in the air at the same ratio.
Therefore, it can effectively adsorb CO2 both in liquid and in air, which is preferable because it can efficiently reduce CO2 in the atmosphere.

In this way, the circuit configuration shown in FIG. 1 can efficiently adsorb CO2 in the drain and compressed exhaust gas, but the present invention employs a system in which only one drain trap 20 opens more reliably.
The description will be made with reference to Fig. 3. The same parts as in Fig. 1 will be omitted.
A control unit 50, a water level sensor 51, a solenoid valve 52, and a pressure sensor 53 are added.
In summary, the drain trap 20 to be opened is identified from the value of the water level sensor 51 of each drain trap 20, and the drain trap 20 is opened by the solenoid valve 52. At that time, the timing of opening is adjusted according to the pressure value of the collecting pipe 25.

The control unit 50 is a part that controls the discharge of drainage in accordance with the amount of drainage in each drain trap 20 and the pressure value in the collecting pipe.
The control unit 50 has as inputs a part that receives the value of a water level sensor 51 that detects whether the drain amount of each drain trap 20 has reached a specified value, and a part that receives the value of a pressure sensor 53 that measures the pressure value inside the collecting pipe.
The control unit 50 outputs control of the solenoid valves 52 that discharge the drain from each drain trap 20. The solenoid valves can be opened and closed individually for each drain trap 20.

The water level sensor 51 is installed in the portion where the drain D accumulates in each drain trap 20. When the amount of drain D in each drain trap 20 reaches a predetermined amount indicating full water, the water level sensor 51 sends a signal to the control unit 50 indicating that drainage is possible.
The water level sensor 51 stops the signal indicating that drainage is possible when the amount of drain D falls below a predetermined amount of water required for drainage completion.

The pressure sensor 53 is a sensor that measures the pressure inside the collecting pipe 25. The maximum pressure inside the collecting pipe 25 is compressed air pressure (for example, 0.7 MPa), and when stable, it is close to an open state and is approximately 1 atmosphere (0.1 MPa).
When the pressure in the collecting pipe 25 is high, the pressure of the drainage or the like cannot be sufficiently reduced when the drainage or the like flows in from the discharge pipe 22. Therefore, the pressure sensor 53 can adjust the timing of the inflow.

The operation of the control unit 50 will be described with reference to FIG.
The control unit 50 detects the state of drain accumulation based on a signal from the water level sensor 51 of each drain trap 20.
When the water level sensor 51 of one drain trap 20 sends a signal indicating that draining is possible to the control unit 50, the control unit 50 confirms that the other drain traps 20 are not in a draining state. Then, the solenoid valve 52 of that drain trap 20 is opened, and drainage, etc. is sent to the collecting pipe 25 via the drain pipe 22.
Do not open other solenoid valves until drainage is complete.
Such a water level factor makes it possible to more reliably send drainage etc. from only one drain trap 20 to the collecting pipe 25.
As a time factor, it is also possible to wait a certain time after the drain enable signal from one drain trap 20 is released, and then open the solenoid valves 52 of the other drain traps 20.

In addition, by using the pressure sensor 53, drainage or the like can be sent to the collecting pipe 25 depending on the condition of the collecting pipe 25.
For example, when drainage from a certain drain trap 20 is discharged into the collecting pipe 25, the pressure inside the collecting pipe 25 increases slightly accordingly.
In this state, if drain or the like enters from another drain trap 20, the amount of pressure drop will be small, and it is thought that CO2 will not be released sufficiently into the compressed exhaust gas.
Therefore, the pressure inside the collecting pipe 25 is detected by the pressure sensor 53, and after the pressure inside the collecting pipe 25 falls below a certain pressure, the drain trap 20 is opened. Then, by allowing drainage or the like to flow into the collecting pipe 25, CO2 can be stably released into the compressed exhaust gas, which is preferable.

In addition, the control unit 50 can open the solenoid valve 52 for short periods at regular intervals, allowing drainage and other liquids to be discharged while preventing air binding.

In this way, the drain discharge structure of the present invention stabilizes the ratio of CO2 in the liquid to CO2 in the air, allowing for efficient adsorption of CO2 in the liquid and CO2 in the air.

Furthermore, according to the present invention, if the volume of the exhaust pipe and the volume of the collecting pipe can be controlled by the cross-sectional area of the pipes, it is preferable to make the cross-sectional area of the collecting pipe smaller than the cross-sectional area of the exhaust pipe, as this allows the amount of CO2 dissolved to be controlled.

Furthermore, according to the present invention, the opening of each drain trap can be controlled using a water level sensor, ensuring that only one drain trap is always open, which is advantageous because the volume of the collecting pipe can be made larger than the volume of the discharge pipe.

The drain discharge structure of the present invention is a technology that can efficiently collect CO2 from drains, and is not limited to any particular field, but can be used in compressed air circuits in any field. Therefore, it is believed that the present invention has great industrial applicability.

1 Drain discharge structure 2 Air compressor 3 Air tank 4 Air dryer 5 Air filter 20 Drain trap 21 Inlet pipe 22 Discharge pipe 23 Valve 24 Check valve 25 Collector pipe 30 Oil and CO2 absorption tank 31 Oil and CO2 absorption section 32 Gaseous CO2 absorption section 40 Flowing water CO2 outflow pipe 50 Control section 51 Water level sensor 52 Solenoid valve 53 Pressure sensor U Oil D Drain

Claims (2)

a discharge pipe through which drain and compressed exhaust gas discharged from devices disposed in the compressed air pressure circuit flow;
a collecting pipe that sends the combined drain and compressed exhaust gas flowing in from one or more of the discharge pipes to a downstream oil and CO2 absorption tank;
and an oil and CO2 adsorption tank that purifies the drain and compressed exhaust gas that flow in from the collecting pipe.
Each discharge pipe is equipped with a drain trap.
While the drain trap is open, the volume of the discharge pipe in which the drain trap is open is smaller than the volume of the collecting pipe, and the pressure of the drain and compressed exhaust gas drops when they move from the discharge pipe to the collecting pipe,
The piping after the collecting pipe is in an open state or a state close to an open state, and the drain and compressed exhaust maintain the pressure drop,
The oil and CO2 adsorption tank has a section that adsorbs oil and CO2 in the drain, and a section that adsorbs CO2 in the compressed exhaust gas.
The drain trap has a water level sensor,
It has a solenoid valve that opens and closes each drain trap.
The control unit is provided with a time element related to the opening and closing time of the drain trap and a water level element related to the water level of the drain in each drain trap,
Drain is discharged from only one drain trap,
Control is performed to prevent multiple drain traps from opening at the same time,
a pressure sensor for detecting the pressure in the collecting pipe;
The control unit is configured to open one of the drain traps to discharge drain into the collecting pipe when the pressure in the collecting pipe falls below a certain value . The drain discharge structure described in claim 1, characterized in that the cross-sectional area of the discharge pipe is smaller than the cross-sectional area of the collecting pipe.