JP7253182B2 - Air separation device and air separation method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an air separation technique for producing gases such as oxygen by separating air using a boiling point difference, and more particularly to an air separation technique characterized by adjusting the properties of air taken in by an air compressor.

The air separator compresses the air that has been dust-removed by the bag filter with an air compressor and separates the air using the difference in boiling points to produce oxygen and other gases. The produced oxygen is supplied to, for example, a refinery and the like for use.
Here, when the temperature of the air taken in is high, such as in summer, the density of the air compressed by the air compressor decreases, so when the temperature of the outside air rises, the amount of oxygen produced by the air separation device decreases.

For this reason, conventionally, in order to increase the production capacity in summer when the outside air temperature is high, there is a case where a facility configuration having a water cooling tower is adopted as a power-saving oxygen production facility and an oxygen production method using the same. In this equipment configuration, the temperature of the air supplied to the air compressor can be reduced by bringing the air into contact with the water film formed on the surface of the packing material tank of the water cooling tower. However, with this equipment configuration, the cost of installing a water cooling tower increases, it is difficult to secure the installation space for the water cooling tower, and the pressure loss in the filler tank increases against the air taken in, which makes it difficult to achieve power saving. There is

On the other hand, Patent Literature 1 describes that a spray chamber is provided in the front stage of the air compressor. The spray chamber consists of a spray nozzle placed in a duct that takes in air. Furthermore, by providing a filter cloth downstream of the spray nozzle in the duct, the spray chamber also serves as a bag filter. In the method described in Patent Document 1, water is sprayed on the air taken into the spray chamber that also serves as a bag filter, so that the air is cooled by the heat of vaporization, and the cooled air is applied to the filter cloth. After being dust-removed, it is sent to the air compressor.

JP 2007-255863 A

However, in the method described in Patent Document 1, it is necessary to install a spray chamber equipped with a water spray device.
Moreover, the configuration of Patent Document 1 has a structure in which the spray nozzle is arranged in front of the filter cloth in the duct that constitutes the bag filter. In this structure, when water is sprayed inside the duct, the flow speed of the air increases due to the suction of outside air into the duct. It needs to be set long enough for the water to evaporate sufficiently. As described above, when the structure of Patent Document 1 is applied, it is necessary to design a longer path (distance) from the intake of outside air to the filter cloth by providing a spray nozzle.

In addition, when water is sprayed in the duct in excess of the saturated steam content, the water droplets that cannot be evaporated are brought into the filter cloth, and the adhesion of the water droplets deteriorates the air permeability of the filter cloth and increases the pressure loss. there is a possibility. In particular, when the distance from the intake of outside air to the filter cloth is short, the moisture does not evaporate sufficiently, and the temperature of the taken-in air does not decrease sufficiently, and the air permeability deteriorates due to the adhesion of water droplets to the filter cloth. and air pressure loss may increase.
The present invention has been made by paying attention to the above-mentioned points, and even if it is applied to an existing air separation device, it is possible to lower the temperature of the air supplied to the air compressor and reduce the pressure loss in the bag filter. An object of the present invention is to provide an air separation technology that can more reliably suppress the increase.

In order to solve the problem, one aspect of the present invention provides an air compressor that compresses air, takes in air from an air suction port that is open to the outside air, and supplies the air after removing dust with a filter cloth to the air compressor. and a mist area forming device that sprays water onto the outside air existing around the air inlet of the bag filter to form a mist area that is an air area with high humidity around the air inlet. and the mist area forming device includes a water spraying device that sprays water into the outside air, a temperature/humidity measuring device that measures the temperature and humidity of the outside air at a position different from the position where the water is sprayed, a spray water amount estimating unit for estimating a spray water amount at which the relative humidity after spraying the water becomes a preset first set humidity from the temperature and humidity measured by the temperature/humidity measuring device; and spraying from the water spray device. a water amount adjustment unit that adjusts the amount of water supplied to the water spray device so that the amount of water supplied to the spray water amount estimating unit becomes the amount of spray water estimated by the water amount estimation unit; a second temperature/humidity measuring device for measuring the temperature and humidity in the passage located between the filter cloth and the temperature and humidity measured by the second temperature/humidity measuring device; When it is determined that the calculated relative humidity is equal to or higher than a preset second set humidity, a stop command for setting the estimated spray water amount to zero is supplied to the spray water amount estimating unit. and a stop determination unit.

Another aspect of the present invention is an air separation method comprising a step of compressing air after dust removal by a bag filter with an air compressor, wherein an air suction port of the bag filter is open to the outside air, and the air is Water is sprayed onto the outside air existing around the suction port, and the humidity of the outside air is increased, and the water is sprayed onto the outside air at a position where the water is sprayed. Measure the temperature and humidity of the outside air at a position different from the measured temperature and humidity, estimate the amount of spray water at which the relative humidity after spraying water becomes the preset first set humidity, and estimate the spray The temperature and humidity in a passage adjusted to the amount of water and further positioned in front of the air suction port or between the air suction port and the filter cloth are measured, and the air suction port is based on the measured temperature and humidity. The relative humidity of the air sucked in from the outside air is calculated, and when it is determined that the calculated relative humidity is equal to or higher than the preset second set humidity, spraying of water to the outside air is stopped.

According to the aspect of the present invention, by spraying spray water in the atmosphere against the air (outside air) before it is taken in from the air suction port, the temperature of the air can be lowered before it is taken into the bag filter, and the bag The temperature of the air can be further lowered by evaporating the water vapor in the air taken into the filter before reaching the filter cloth. Further, according to the aspect of the present invention, large-scale equipment such as a water cooling tower for cooling air in the upstream stage of the air compressor becomes unnecessary.
As described above, according to the aspect of the present invention, even if it is applied to an existing air separation device, it is possible to reduce the temperature of the air supplied by the air compressor even in summer with a simple configuration, and at the same time, An increase in pressure loss in the filter can be suppressed more reliably.

It is a figure showing an example of composition of an air separation device concerning an embodiment based on the present invention. It is a figure explaining a bag filter and a mist field formation device. It is a conceptual diagram explaining a bag filter and a mist area|region formation apparatus. It is a figure which shows the example of a process of a spray water amount estimation part. FIG. 10 is a diagram showing an example of a matrix for determining the number of stages; FIG. It is a figure which shows the example of a process of a spray stop determination part. It is a figure explaining an example of an Example.

Embodiments of the present invention will now be described with reference to the drawings.
(composition)
In the air separation device of this embodiment, for example, as shown in FIG. A spray nozzle 30 is provided.
After the air compressor 1, for example, a cooling tower 3, an MS adsorber 4, a heat exchanger 5, and a rectifying tower 7 are arranged in this order.

The cooling tower 3 cools the air that has been compressed by the air compressor 1 and raised in temperature. The MS adsorber 4 adsorbs and removes unnecessary CO, CO ₂ , H ₂ O, etc. from the air. The heat exchanger 5 cools the air by heat exchange using nitrogen gas and oxygen gas cooled and separated in the rectification tower 7 . If the heat balance in the heat exchanger 5 alone is insufficient for cooling, the expansion turbine 6 compensates for the insufficient cooling.
The rectification tower 7 further cools (deep-cools) the air cooled by the heat exchanger 5, and uses the difference in liquefaction temperature to separate the air into nitrogen gas and oxygen gas. In the rectifying column 7 , the raw material gas of argon gas is separated simultaneously with the purification and separation described above, and the separated gas is introduced into the crude argon column 8 . Here, since the liquefying temperature of argon is close to the liquefying temperature of oxygen, the gas introduced into the crude argon column 8 contains a large amount of oxygen. Therefore, after adding hydrogen through the argon heat exchanger 9 and the argon compressor 10 , the argon is further purified in the argon purifier 11 .

Next, the bag filter 2 and the mist area forming device 12 of this embodiment will be described.
The bag filter 2 of this embodiment consists of a raw air intake tower 2A as shown in FIG.
2 and 3, the raw air intake tower 2A includes an air intake section 21, an air chamber 22, a filter cloth storage chamber 23, and a plurality of filter cloths 24 arranged in the filter cloth storage chamber 23. .
The air intake portion 21 includes an intake duct 21A projecting upward from the top plate portion 2Aa of the suction tower 2A, and a cylindrical body 21B having a closed top surface and coaxially arranged so as to cover the upper end opening of the intake duct 21A. and The inner diameter of the cylindrical body 21B is larger than the outer diameter of the intake duct 21A, and the upper end surface of the cylindrical body 21B is arranged above the height of the upper end opening of the intake duct 21A.

With this configuration, the air intake portion 21 draws outside air from the lower end position (air intake port 21a) of the annular space formed between the outer wall surface of the intake duct 21A and the inner wall surface of the cylindrical body 21B. The air that is taken in moves upward along the annular space and moves into the intake duct 21A.
The air chamber 22 is formed below the top plate portion 2Aa of the suction tower 2A, and the air chamber 22 communicates with the lower end of the intake duct 21A.
A filter cloth storage chamber 23 is provided below the air chamber 22 , and a plurality of filter cloths 24 are arranged in the filter cloth storage chamber 23 . Each filter cloth 24 has a cylindrical shape with its axis directed vertically, and the upper end opening of the filter cloth 24 communicates with the air chamber 22 . An air discharge opening 23A is formed in the wall surface of the filter cloth storage chamber 23, and the air discharge opening 23A communicates with the suction portion of the air compressor 1. As shown in FIG.
A dust collection hopper 25 is provided below the filter cloth storage chamber 23 .

With such a configuration, the raw air intake tower 2A takes in outside air from the air intake section 21, and the taken-in air is supplied to the air chamber 22 through the intake duct 21A. The air moved to the air chamber 22 is dust-removed by each filter cloth 24 and then sent to the air compressor 1 through an air discharge opening formed in the wall surface of the filter cloth housing chamber 23 .
The mist area forming device 12 sprays water onto the outside air positioned around the air inlet 21a of the bag filter 2, so that mist of air with increased humidity around the air inlet 21a of the bag filter 2 is formed. This is an apparatus for forming a region MR (an air region in a mist atmosphere state).

The mist area forming device 12 includes a water spray device, a spray water amount estimating section 37 , a water amount adjusting section 40 , a second temperature/humidity measuring device 36 and a spray stop determining section 41 .
The water spray device has a plurality of spray nozzles 30 that spray water toward the outside air, a pump 33 that supplies water to the spray nozzles 30 , and a water pipe 32 that sends water from the pump 33 to the spray nozzles 30 . A plurality of spray nozzles 30 are communicated by nozzle headers 31 .
In this embodiment, the pump 33 is driven and adjusted so that the water discharge pressure (supply pressure) is constant. When a plurality of rows of water pipes 32 are arranged as described later (see FIG. 3), a pump 33 may be provided for each water pipe 32 . In this embodiment, water is pressure-fed from one pump 33 to a plurality of water pipes 32 provided in parallel in a circuit.

A plurality of spray nozzles 30 are arranged on the top plate portion 2Aa of the suction tower 2A so as to line up along the surface of the top plate portion 2Aa. Specifically, a nozzle header 31 is arranged on the top plate portion 2Aa of the suction tower 2A so as to surround the outer periphery of the air intake portion 21 in a plan view, and a plurality of nozzles are arranged in the nozzle header 31 at intervals. It is set open. Each of the spray nozzles 30 is arranged with the water injection port facing upward, and is capable of spraying water toward the outside air (air) positioned above. By spraying this water, the outside air (air) around the air suction port 21a is turned into a mist region MR (mist atmosphere state). It is preferable that the water spray direction of each spray nozzle 30 is not directed toward the air suction port 21a side or the air intake portion 21 side.

The spray nozzle 30 has, for example, a wall on which the high-pressure water supplied from the pump 33 collides. A known structure may be adopted as the structure for reducing the particle size of the high-pressure water. For example, a spray nozzle described in Japanese Patent Application Laid-Open No. 2009-36316 is employed.
Although it depends on the water pressure to the spray nozzle 30, the particle size of the water sprayed from the spray nozzle 30 is set to, for example, an average particle size of 20.0 μm or more and 23.0 μm or less.
Here, by setting the pressure of the high-pressure water supplied to the spray nozzle 30 to be constant, the diameter of the droplets of the sprayed water sprayed from the spray nozzle 30 can be set to the preset specification droplet diameter. That is, water with a stable particle size can be supplied to the air, and variations in the humidity of the air can be suppressed.

The spray nozzle 30 is connected to a discharge port of a pump 33 via a nozzle header 31 and water pipe 32 .
Based on the temperature and humidity of the outside air around the suction tower 2A measured by the temperature/humidity measuring device 35, the spray water amount estimator 37 estimates the amount of spray water at which the relative humidity of the mist area MR becomes the preset first set humidity. do. However, when a stop command is input from the spray stop determination unit, the spray water amount estimation unit 37 does not calculate the spray water amount until a spray restart command is input from the spray stop determination unit, and sets the calculated spray water amount to zero.

The outside air whose temperature and humidity are measured is the outside air which is considered to have little influence on the spray of water. In this embodiment, the temperature and humidity of the outside air around the lower part of the suction tower 2A are measured. That is, the temperature/humidity measuring device 35 is installed near the bottom of the suction tower 2A.
The first set humidity is set to 80%, for example. To obtain the maximum effect, the first set humidity should be set as high as the dew point. However, if the target value of humidity is set to 100%, there is concern that water vapor condensation will occur frequently due to external disturbances such as wind, and that the filter cloth 24 will become clogged, causing a sudden increase in the differential pressure of the filter. In some cases, it may be difficult to continue long-term operation. Considering that humidity changes due to external influences such as wind direction and wind speed, the first set humidity, which is a target value, is set, for example, in the range of 70% or more and 95% or less. It is preferably 75% or more and 90% or less, more preferably 80% or more and 85% or less.

In this embodiment, the temperature/humidity measuring device 35 is installed in the vicinity of the lower part of the suction tower 2A in order to reduce external influences such as wind direction and wind speed.
Here, in the present embodiment, the basic humidity control for forming the mist area MR is not the feedback control based on the measured temperature and humidity of the mist area MR itself, but the temperature of the outside air other than the mist area MR.・Feed-forward control based on humidity.
The reason for this is that since the mist area MR is formed by supplying spray water to the outside air with disturbance, the measurement position in the mist area MR (the position in the three-dimensional space including the height position) also affects the humidity. In addition, the direction of the sprayed water changes due to wind and other disturbances to the outside air, and the fluctuation of humidity may increase even at the same position. On the other hand, the outside air around the suction tower 2A outside the mist region MR formed by the water spray is more stable in temperature and humidity than in the mist region MR. From the temperature and humidity of the outside air around the suction tower 2A in areas other than the area MR, the amount of spray water for setting the relative humidity to the first set humidity is estimated.

Next, a method for estimating the amount of sprayed water in the sprayed water amount estimating section 37 will be described.
A saturated water vapor amount mx0 at the temperature T0 is obtained from the measured temperature T0. The saturated water vapor amount mx0 may be calculated from a known conversion formula or conversion table data based on a moist air table or the like. Let m0 be the amount of water vapor corresponding to the measured humidity H0 (absolute humidity).
At this time, the relative humidity RH0 (%) at the measurement position can be calculated by the following formula.
RH0=m0/mx0×100 (1) The relative humidity in the mist region MR is also close to RH0 if there is no spray of water. However, the water spray causes a temperature drop. Therefore, the relative humidity RH1 (%) in the mist region MR after spraying can be estimated, for example, from the following considerations.

That is, from the measured temperature T0 measured by the temperature/humidity measuring device 35, an assumed temperature T1 after the temperature is lowered by spraying is assumed, and the saturated water vapor amount mx1 at the assumed temperature T1 is obtained. Let m0 be the amount of water vapor corresponding to the measured humidity H0 (absolute humidity) measured by the temperature/humidity measuring device 35, and let Δm be the amount of water vapor increased by spraying water.
Then, the relative humidity RH1 (%) after spraying can be estimated by the following formula (2).
RH1 (%) = (m0 + Δm)/mx1 × 100 (2) Then, based on the formula (2), the relative humidity RH1 after spraying becomes the first set humidity (for example, 80%), the increase The amount of water vapor Δm or the amount of water corresponding to the amount of water vapor Δm is obtained as the water spray amount.

Here, the assumed temperature T1 is set, for example, as follows. Calculate the temperature at which the relative humidity RH0 becomes the first set humidity (for example, 80%) at the water vapor amount m0 corresponding to the current measured humidity H0 from a known conversion formula or conversion table data based on a humid air table, The calculated temperature is assumed temperature T1. In this case, there is a possibility that the assumed temperature T1 is set lower than the actual temperature after the temperature is lowered. can be done. The method for estimating the assumed temperature T1 is not limited to this. For example, the value obtained by simply multiplying the temperature of the water to be sprayed by a preset coefficient (<1) may be set as the temperature drop ΔT, and the value obtained by subtracting the temperature drop ΔT from the measured temperature T0 may be set as the assumed temperature T1. Also, a temperature measured by a second temperature/humidity measuring device 36, which will be described later, may be employed as the assumed temperature T1.

Here, as will be described later, in this embodiment, by opening and closing each water pipe 32, the amount of water supplied to the spray nozzle 30 is adjusted so as to change stepwise.
In consideration of this, the spray water amount estimator 37 of the present embodiment sets the spray water amount as a plurality of stages in which the water amount increases stepwise. The number of stages TP corresponds to the number of water pipes 32 to be supplied. In the present embodiment, the stepwise increase in water volume is assumed to be equal, but the set water volume (pipe diameter) corresponding to each step may be different. It suffices if the amount of water in each stage is determined in advance.

Then, in the spray water amount estimating unit 37 of the present embodiment, the temperature T0 and the humidity H0 of the measured outside air are used as parameters, and the stage number TP at which the measured humidity is the first set humidity or near the first set humidity is set in advance. A conversion formula or matrix table data for converting the number of stages TP from the two parameters of the measured temperature and the measured humidity of the outside air is obtained by experiments or theoretical formulas and stored. For example, from the two parameters of measured temperature and humidity, the temperature at which the relative humidity RH can be reduced to the first set humidity is calculated. The stage number TP of the matrix is determined by estimating in advance the amount of sprayed water required for the temperature reduction obtained by (the difference in the amount of heat held by the air before and after the water spray and the latent heat of vaporization of water).

Then, the spray water amount estimating unit 37 inputs the actually measured outside air temperature T0 and humidity H0 ( FIG. 4 : step S20), and uses the entered outside air temperature T0 and humidity H0 as parameters to set a conversion formula or matrix. The data in the table is referred to and the number of stages TP corresponding to the amount of spray water is obtained (FIG. 4: step S30).
For example, FIG. 5 shows an example of a matrix table in which the number of stages TP is three.
As can be seen from the matrix table shown in FIG. 5, the higher the temperature and the lower the measured humidity, the higher the step number TP. The number of stages TP may be four or more.

Further, when a spray stop command is input from the spray stop determination unit 41 ( FIG. 4 : step S10), the spray water amount estimation unit 37 sets the estimated spray water amount to zero (step number TP=0), and the spray stop determination unit 41 The estimated amount of spray water is set to zero (step number TP=0) until a restart command is input ( FIG. 4 : step S40).
The water amount adjusting unit 40 adjusts the amount of water sprayed from the spray nozzle 30 of the water spray device so that the water amount estimated by the spray water amount estimating unit 37 (for example, the water amount corresponding to the number of stages TP). The water volume adjustment section 40 includes a flow rate adjustment valve and a flow rate control section 38 . That is, the water amount adjustment unit 40 has a flow rate adjustment valve provided in the water pipe 32, and the flow rate control unit 38 supplies the flow rate adjustment valve with an opening degree command corresponding to the amount of water obtained by the spray water amount estimation unit 37, The flow regulating valve becomes the opening of the opening instruction.

In this embodiment, as shown in FIG. 3, two water pipes 32 connected to the nozzle header 31 are provided in parallel in a circuit, each water pipe 32 is provided with an on-off valve 34, and the plurality of on-off valves 34 It is an example in which a flow control valve is configured. The water pressure from the pump 33 to each water pipe 32 is set to the same pressure, and the water supply amount of the water pipe 32 is set to be constant. Thus, by opening and closing the on-off valve 34, the water pressure is set to be constant even if the amount of water supplied to the spray nozzle 30 changes.

Then, the flow rate control unit 38 supplies open commands to the on-off valves 34 of the number corresponding to the stage number TP corresponding to the water amount obtained by the spray water amount estimating unit 37 . The on-off valve 34 is closed as an initial value. That is, when the humidity is high due to rainfall or the like and the step number TP is "0", both of the two on-off valves 34 are supplied with the closing command. If the stage number TP is "1", the open command is supplied to only one of the on-off valves 34, and if the stage number TP is 2 or more, the open commands are supplied to both the on-off valves 34. Here, when the close command is supplied to both the two on-off valves 34, the drive stop command may be supplied also to the pump 33 because water is not sprayed.
Further, in this embodiment, even if the stage number TP is 3 or more, the stage number TP is regarded as 2 and the two on-off valves 34 are set to be opened so as not to spray water excessively. Three or more water pipes 32 may be arranged in parallel, each water pipe 32 may be provided with an on-off valve 34, and control may be performed so that the on-off valves 34 are opened by the number corresponding to the number of stages TP.

As shown in FIG. 3, the second temperature/humidity measuring device 36 is installed in front of the air inlet 21a of the bag filter 2 to measure the temperature and humidity of the air sucked into the bag filter 2. FIG. For example, the second temperature/humidity measuring device 36 is positioned outside the intake duct 21A below the annular space formed between the outer wall surface of the intake duct 21A and the inner wall surface of the cylindrical body 21B. Attach to wall.

The second temperature/humidity measuring device 36 may measure the temperature and humidity in the passage located between the air inlet 21 a of the bag filter 2 and the filter cloth 24 . That is, the second temperature/humidity measuring device 36 is placed in an annular space formed between the outer wall surface of the intake duct 21A and the inner wall surface of the cylindrical body 21B, inside the intake duct 21A, or in an air chamber. 22 may be provided. However, since it is preferable to acquire the temperature and humidity early, it is preferable to measure before the air inlet 21 a of the bag filter 2 . Even if the second temperature/humidity measuring device 36 is provided in the passage located between the air suction port 21a of the bag filter 2 and the filter cloth 24, the outer wall surface of the intake duct 21A and the cylindrical body 21B It is preferable to install the second temperature/humidity measuring device 36 in an annular space formed between the inner wall surface.
Then, the second temperature/humidity measuring device 36 measures the actual temperature and humidity of the air sucked from the air suction port 21a.

The spray stop determination unit 41 inputs the temperature and humidity measured by the second temperature/humidity measuring device 36 (FIG. 6: step S100), and based on the input temperature and humidity, the air inlet 21a of the bag filter 2 A relative humidity RH2 of the sucked air is calculated ( FIG. 6 : step S110). Further, when it is determined that the calculated relative humidity RH2 is equal to or higher than the preset second set humidity (FIG. 6: step S120), a spray stop command is supplied to the spray water amount estimator 37 (FIG. 6: step S130). The second set humidity is higher than the first set humidity, and is set to 90%, for example.

Furthermore, when the spray stop determination unit 41 determines that the relative humidity RH2 calculated from the temperature and humidity measured by the second temperature/humidity measuring device 36 is equal to or less than the preset third set humidity ( FIG. 6 : step S140). , to the spray water amount estimator 37 ( FIG. 6 : step S150). The third set humidity is set to a value lower than the second set humidity, for example, set to 80%, which is the same as the first set humidity.
Here, the relative humidity RH2 (%) is, for example, calculated from the measured temperature to the saturated water vapor amount MX2 at that temperature from a known conversion formula or conversion table data, and the calculated saturated water vapor amount MX2 and the measured humidity (absolute humidity) From the corresponding water vapor content M2, it is obtained based on the following formula.
RH2 (%) = (M2/MX2) x 100

(Other operations)
In this embodiment, a water cooling tower is not arranged upstream of the bag filter 2, and the air suction port 21a of the bag filter 2 is open to the outside air. By driving the air compressor 1 , air (outside air) is sucked into the air compressor 1 through the bag filter 2 .
At this time, in the present embodiment, at least part of the air sucked from the air suction port 21a of the bag filter 2 is high humidity air (outside air) that sprays the spray water to form the mist region MR. It has become. It is preferable that 50% or more, preferably 90% or more of the air sucked from the air suction port 21a of the bag filter 2 is high humidity air that forms the mist region MR.

The air (outside air) that forms the mist region MR is taken into the bag filter 2 from the air inlet 21a in a state of high-humidity air while the temperature is lowered by spraying water. At this time, the temperature of the sucked air decreases due to the heat of vaporization before it is taken into the bag filter 2, and even after it is taken into the bag filter 2, the air moves until it reaches the filter cloth 24. , the temperature of the air decreases due to the heat of vaporization when the water vapor in the air evaporates. Evaporation of water vapor is accelerated by higher air velocity, higher temperature, and higher pressure. Therefore, the target relative humidity of the mist area MR may be set to be higher as the outside air temperature is higher.

By taking in the air (outside air) in the mist area MR, air having a temperature lower than the outside air temperature is supplied to the air compressor 1 after dust is removed by the filter cloth 24 . That is, even if an existing bag filter is used, the air taken into the air compressor 1 can be efficiently cooled.
Here, when a nozzle for spraying is installed in the bag filter 2 as in the past, the flow velocity of the air inside the bag filter 2 increases due to the suction of air, so sufficient evaporation of water vapor should be ensured. Therefore, it is necessary to design the path from the nozzle installation position in the bag filter 2 to the filter cloth 24 to be long, or to suppress the nozzle spray according to the path to the filter cloth 24 .

On the other hand, in the present embodiment, by spraying water onto the outside air (air) existing outside the bag filter 2, water vapor in the air evaporates even during movement to the air suction port 21a where the flow velocity is slow. is generated, and vaporization of water vapor occurs from the time it is taken into the air suction port 21a. Therefore, the filter cloth 24 can be designed to ensure that the water vapor in the air is sufficiently evaporated. In the case of the idea of arranging the spray nozzle inside the bag filter 2, since the nozzle is arranged at a position on the filter cloth 24 side by a predetermined length from the air suction port 21a, the distance from the air suction port 21a to the nozzle installation position is Do not use the path as a path for evaporation.

Thus, by installing the spray nozzle 30 around the air inlet 21a, such as in front of the air inlet 21a of the bag filter 2, the path space required for sufficient vaporization of water vapor can be reduced to the existing bag filter 2. available in space. Furthermore, the temperature drop due to the heat of vaporization of the air can be designed to be greater than in the case where the bag filter 2 is provided, and the air taken into the air compressor 1 can be cooled more efficiently. The spray direction of the spray nozzle 30 is preferably directed in a direction different from the side of the air inlet 21a so that the sprayed water does not splash on the air inlet 21a. Therefore, in this embodiment, the spray direction of the spray nozzle 30 is set upward. A roof may be provided on the top plate portion 2Aa of the suction tower 2A, and the roof may support the spray nozzle 30 to spray water downward. When a roof is provided, it leads to suppression of disturbance due to wind or the like to the outside air that is sucked in.

Here, if spraying is performed by feedforward control, there is a possibility that the air (outside air) that forms the mist region MR will be sprayed with water that is equal to or greater than the saturated water vapor amount.
Even if the amount of water that is equal to or greater than the saturated water vapor is sprayed, in this embodiment, since the water is sprayed against the outside air outside the bag filter 2, part of the condensed water falls outside the bag filter 2. Therefore, the amount of condensed water taken into the bag filter 2 from the air inlet 21a can be suppressed.
Furthermore, in the present embodiment, the air taken in from the air suction port 21a is designed to move upward in the annular space, move to the upper end opening of the intake duct 21A, and flow toward the air chamber 22. As shown in FIG. Even when the air moves upward in the annular space, the amount of condensed water droplets moving into the intake duct 21A is suppressed.

Here, considering the temperature drop due to the heat of vaporization when air is taken into the bag filter 2, and the prevention of the intake of condensed water when the amount of water above the saturated water vapor is sprayed, The distance from the air suction port 21a to the position of the spray nozzle 30 is, for example, preferably 50 cm or more, more preferably 1 m or more. However, if the distance is too large, the intake amount of the air forming the mist region MR from the air suction port 21a may not be sufficient. More preferably, it should be 3 m or less.

Moreover, when the water droplets that have not been evaporated are carried into the bag filter 2 and adhere to the filter cloth 24, the pressure loss increases due to deterioration of air permeability. In contrast, in the present embodiment, the amount of spray water is adjusted so that the relative humidity obtained from the temperature and humidity of the outside air becomes the first set humidity. This suppresses the supply of water in excess of the saturated water vapor amount to the mist region MR. Furthermore, a second temperature/humidity measuring device 36 is provided in the vicinity of the air intake of the bag filter 2, and when the relative humidity based on the measured value of the second temperature/humidity measuring device 36 becomes equal to or higher than the second set humidity, the water is The feedback control to stop the spraying prevents the air in the bag filter 2 from condensing. After the relative humidity based on the measured value of the second temperature/humidity measuring device 36 becomes equal to or higher than the second set humidity, the relative humidity of the air taken into the bag filter 2 becomes equal to or less than the third set humidity. Then, when the humidity atmosphere inside the bag filter 2 is lowered, the spraying of water to the outside air is resumed.

Here, although it is possible to control the water spray only based on the relative humidity measured by the second temperature/humidity measuring device 36, there is a possibility that control switching will occur frequently, and the amount of air that is taken in will increase. Humidity itself can also vary greatly.
Further, in this embodiment, a plurality of water pipes 32 are arranged in parallel, and while the discharge pressure of the pump 33 to each water pipe 32 is set constant, the flow path of each water pipe 32 is turned on and off to supply high-pressure water to the nozzle. It is adjusted so that the pressure of is constant.
As a result, it becomes possible to stabilize the water droplet diameter during water spraying within a predetermined particle diameter range.

Here, the position of the spray nozzle 30 is determined so as to ensure the evaporation time calculated from the specified particle size of the spray water. Water vapor may not evaporate sufficiently.
On the other hand, in the present embodiment, by stabilizing the water droplet diameter during water spraying, it becomes possible to sufficiently evaporate the water vapor in the air before reaching the filter cloth 24 more reliably.
Further, according to this configuration, there is no need to control the amount of water using a regulating valve or the like, and there is no or little decompression loss.

Here, in the air separation device having the above configuration, the outside air temperature, the relative humidity of the air taken into the bag filter 2 based on the measurement of the second temperature/humidity measuring device 36 in the bag filter 2, and the second temperature/humidity measurement A change in the intake temperature, which is the temperature measured by the device 36, was sought. The results are shown in FIG. It should be noted that this example was carried out in the summer.
As can be seen from FIG. 7, when this embodiment is employed, the relative humidity of the air taken into the bag filter 2 is controlled within a range of about 80% to 90%, and dew condensation does not occur. In addition, since the suction temperature is lower than the outside air temperature, the production capacity in summer can be increased, and the power consumption of the air compressor 1 can be reduced.

1 Air Compressor 2 Bag Filter 2A Raw Air Intake Tower 2Aa Top Plate Part 21 Air Intake Part 21A Intake Duct 21B Cylindrical Body 21a Air Intake Port 22 Air Chamber 23 Filter Cloth Storage Chamber 23A Opening 24 Filter Cloth 25 Dust Collection Hopper 30 Spray nozzle 31 Nozzle header 32 Water pipe 33 Pump 34 On-off valve 35 Temperature/humidity measuring device 36 Second temperature/humidity measuring device 37 Spray water amount estimation unit 38 Flow control unit 40 Water amount adjustment unit 41 Spray stop determination unit MR Mist region

Claims (4)

an air compressor for compressing air;
a bag filter that takes in air from an air suction port that is open to the outside air and supplies the air after removing dust with a filter cloth to the air compressor;
a mist area forming device that sprays water onto the outside air existing around the air inlet of the bag filter to form a mist area that is an air area with high humidity around the air inlet;
The mist area forming device is
a water spray device for spraying water to the outside air;
a temperature/humidity measuring device for measuring the temperature and humidity of the outside air , which is considered to have little effect on the spraying of water by the water spraying device at a position distant from the position where the water is sprayed;
a spray water amount estimating unit for estimating a spray water amount at which the relative humidity after spraying the water becomes a preset first set humidity from the temperature and humidity measured by the temperature/humidity measuring device;
a water amount adjustment unit that adjusts the amount of water supplied to the water spray device so that the amount of water sprayed from the water spray device becomes the spray water amount estimated by the spray water amount estimation unit;
a second temperature/humidity measuring device for measuring the temperature and humidity in a passage positioned in front of the air suction port or between the air suction port and the filter cloth;
Calculate the relative humidity of the air sucked from the air inlet based on the temperature and humidity measured by the second temperature/humidity measuring device, and determine that the calculated relative humidity is equal to or higher than the preset second set humidity , a spray stop determination unit that supplies a stop command for setting the estimated spray water amount to zero to the spray water amount estimation unit;
An air separation device comprising: The water spray device includes a spray nozzle that sprays water toward the outside air existing around the air inlet, and a pump that pumps water to the spray nozzle,
The water amount adjusting unit includes a plurality of water pipes arranged in parallel between the spray nozzle and the pump, a plurality of on-off valves respectively interposed in each water pipe, and the spray water amount estimating unit estimated 2. The air separation apparatus according to claim 1, further comprising a flow rate control unit that controls opening and closing of each of the plurality of on-off valves so that the amount of spray water is obtained. 3. The air separation apparatus according to claim 2, wherein the discharge pressure of said pump is set constant. An air separation method comprising a step of compressing air after dust removal with a filter cloth of a bag filter with an air compressor,
opening the air intake port of the bag filter to the outside air;
At least a part of the air sucked from the air suction port is used as the outside air whose humidity is increased by spraying water on the outside air existing around the air suction port;
The spraying of water to the outside air is performed by measuring the temperature and humidity of the outside air , which are considered to have little effect on the spraying of water at a position distant from the position where the water is sprayed, and spraying water from the measured temperature and humidity. After estimating the amount of spray water at which the relative humidity is the preset first set humidity, the amount of spray water is adjusted to the estimated amount,
Furthermore, the temperature and humidity in a passage located in front of the air suction port or between the air suction port and the filter cloth are measured, and the temperature and humidity of the air sucked from the air suction port are measured based on the measured temperature and humidity. An air separation method, comprising: calculating a relative humidity, and stopping spraying water to the outside air when the calculated relative humidity is determined to be equal to or higher than a preset second set humidity.

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