JPS6316028A - Gas dryer - Google Patents

Abstract

PURPOSE:To reduce regeneration energy, by a method wherein, operation is performed on the basis of the generation time of an operation signal synchronous to the operating load of a compressor and the dew point detected of inflow gas and, when an inflow moisture amount reaches a set value, a dehumidifying tower is changed over. CONSTITUTION:Compressed air from an air supply source 11 is supplied to a dehumidifying tower 2 through a receiver tank 15 and a pressure switch 16 emits an operation signal Sp corresponding to the air pressure of the receiver tank 15 and a compressor 13 is intermittently operated and the emitting flow rate thereof is operated by an operator 21. An inflow moisture amount signal Si is operated on the basis of the operation signal Sp and a dew point signal Sd by an operator 22 and, when said signal Si becomes the tolerant adsorbed moisture amount signal Sw or more emitted from a setting device 23, a tower change-over signal Sc is emitted by a comparator 24 and the dehumidifying tower 2 is changed over to regeneration mode while a dehumidifying tower 3 is changed over to adsorption mode.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a gas drying device for removing moisture from gas to obtain dry gas.

(Prior art) Generally, to obtain dry air or other dry gas used for instrumentation or painting, the gas to be dried is compressed using a compressor, cooled and dehumidified using a water-cooled aftercooler, and then supplied to a dehumidifier. dehumidification is performed.

This dehumidification equipment usually consists of a pair of dehumidification towers filled with a desiccant such as silica gel or activated alumina, one of which is selected alternately to dehumidify the gas, and the other dehumidification tower dehumidifies the desiccant. A gas dehumidifier configured to perform regeneration is used, and the towers used for dehumidification and drying are switched at regular intervals using a timer or the like.

However, the amount of drying gas used decreases, for example, at night or during lunch breaks, and the amount of water molecules adsorbed by the desiccant in the dehumidifying tower during this time is small. If the desiccant is regenerated at regular intervals, regardless of the amount of water absorbed, the desiccant will be heated frequently when the amount of adsorbed water is small, which wastes energy. Furthermore, due to annual changes in the cooling water temperature for the aftercooler and seasonal fluctuations in the gas temperature before compression,
The dew point of the compressed gas flowing into the dehumidification tower will fluctuate, but the regeneration heater capacity and heating time are determined so that the desiccant that dehumidified the gas with a high dew point can be sufficiently regenerated. The desiccant that dehumidifies the gas in a low state is heated more than necessary during regeneration, which is also not desirable from the point of view of energy saving.

Therefore, in order to solve these problems, the applicant proposed a gas system that can adjust the switching time interval of the dehumidifying and regenerating tower according to the dew point of the gas to be dried and the flow rate. We are proposing a dehumidifier.

In this dehumidifier, the amount of moisture flowing into the dehumidification tower is determined based on the dew point of the gas to be dried measured by the dew point detector and the flow rate of the gas to be dried determined by the flow rate detector, and when the amount of moisture reaches the set value. It is designed to perform time tower switching.

(Problem to be Solved by the Invention) However, while the dehumidifier disclosed in the above publication has the advantage of accurately determining the amount of water flowing into the dehumidifying tower, The flow rate detector is expensive and accounts for a relatively large proportion of the equipment cost of the entire device, which poses a problem in terms of cost.Furthermore, it is difficult to detect malfunctions of the flow rate detector or loss of accuracy due to use.
As a result, there was a risk of an accident in which the dew point of the drying gas increased abnormally.

This invention solves the above-mentioned conventional problems, and has a total of 5
! Provides a gas drying device that can automatically adjust the tower switching time interval according to the amount of water flowing into the dehumidification tower using a simple and economical device without using an expensive flow meter such as a daily meter. This is what I am trying to do.

(Means for Solving the Problems) However, the device of the first invention of this application includes a compressor, a water-cooled aftercooler connected to the gas outlet side of the compressor, and a gas outlet of the aftercooler. A dehumidifying device that is connected to the side of a pair of dehumidifying towers and filled with a desiccant, one dehumidifying tower dehumidifies the gas and the other dehumidifying tower regenerates the desiccant. In the apparatus, an operation signal generator that emits an operation signal that is synchronized with the load operation of the compressor, a dew point detector that detects the dew point of the gas flowing into the one dehumidification tower, and a generation time of the operation signal and the dew point. and a tower switching control device that performs calculations based on the dew point detected by the detector and issues a tower switching signal when the amount of water flowing into the one dehumidifying tower reaches a set value, and based on the tower switching signal, This gas drying apparatus is characterized in that the towers used for dehumidification and regeneration are switched.

Further, the device of the second invention of this application includes a compressor, a water-cooled aftercooler connected to the gas outlet side of the compressor, and a water-cooled aftercooler connected to the gas outlet side of the aftercooler, the inside of which is filled with a desiccant. In a gas drying apparatus comprising a dehumidifying device which dehumidifies gas in one dehumidifying tower of a pair of dehumidifying towers and regenerates a desiccant in the other dehumidifying tower, synchronization with the load operation of the compressor is provided. a dew point setting unit that sets the dew point of the gas flowing into the one dehumidifying tower; A tower switching control device is provided which issues a tower switching signal when the amount of water flowing into one of the dehumidifying towers reaches a set value, and the towers for dehumidification and regeneration are switched based on the tower switching signal. This is a gas drying device characterized by:

(Function) In the gas drying apparatus of the present invention, the flow rate of the gas to be dried flowing into the dehumidification tower is calculated by the product of the generation time of the operation signal issued by the operation signal generator and the discharge amount of the compressor. In the first invention, the amount of water flowing into the dehumidifying tower is calculated from the flow rate of the gas to be dried and the dew point of the gas detected by the dew point detector, and when the amount of water reaches the allowable amount of adsorbed water of the desiccant, a tower switching signal is sent. is emitted, and the tower that performs dehumidification and regeneration is switched. Further, in the second invention, the set value of the gas dew point expected from the cooling water temperature of the aftercooler and the suction gas temperature of the compressor and the amount of water flowing into the dehumidification tower from the flow m of the gas to be dried are calculated.

(Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In the figure, 1 is a dehumidifying device for air dehumidification, 2.3 is a dehumidifying tower which is the main part of the dehumidifying device, and the casing is filled with a desiccant such as silica gel, activated alumina, or synthetic zeolite. 4 is an inlet for air to be dried, 5 and 6 are four-way valves, 7 is a flow rate adjustment valve for regeneration air, 8 is an on-off valve, 9 is a discharge port for regeneration air, and 1o is a dry air outlet, which is the dry air usage side. It is connected to the. Reference numeral 11 denotes an air supply source, which mainly consists of a compressor 13 driven by a motor 12 and a water-cooled aftercooler 14 connected to its gas outlet side.The gas outlet side of the aftercooler 14 is connected to a receiver tank 15. It is connected to the air to be dried 4 of the dehumidifier 1 via the dehumidifying device 1 . 16
is a pressure switch which is an operation signal generator for the compressor 13,
When the gas pressure in the receiver tank 15 falls below a specified value, an operation signal S is issued, and upon receiving this operation signal, the compressor control device 17 operates the unloader (not shown) of the air supply source 11 to operate the compressor 113 under load. It is now possible to switch to . Further, 18 is a thermometer for measuring the temperature of the air in the air supply pipe between the drying air inlet 4 and the four-way valve 5.

Note that since the air to be dried is cooled and dehumidified by the aftercooler 14 and is in a substantially saturated state, the temperature detected by the thermometer 18 is approximately equal to the dew point of the air to be dried. 20 is a tower switching control device that calculates the amount of moisture in the air that has flowed into the dehumidification tower 2 after the start of dehumidification from the operating signal @Sp issued by the pressure switch 16 and the dew point signal S issued by the thermometer 18, and It is a switching control device that issues a tower switching signal S when the amount reaches a predetermined value, and measures the time when the operation signal S occurs and changes the air flow ff.
1s, an arithmetic unit 21 that converts the amount of air discharged from the compression unit 113, and this air flow rate S.

and a dew point signal S, a computing unit 22 that computes the amount of water flowing into the dehumidifying tower 2, Si, a set value 23 that generates a signal Sw of the allowable adsorption moisture content of the desiccant in the dehumidifying tower 2, and this signal S and the computing unit. 22 and a comparator 24 which compares the inflow water quantity signal S and outputs a tower switching signal S when the latter exceeds the former. The above-mentioned allowable adsorption amount of moisture for the desiccant means the effective moisture absorption capacity of the desiccant that can be adsorbed by the desiccant until the dew point of the dry air reaches the allowable upper limit after regeneration (reactivation), plus the drying capacity of the desiccant in the dehumidifying tower. This is the amount of water multiplied by the weight of the liquid, or the amount of water lowered by a certain amount of margin.

Next, a method of drying the air and regenerating the desiccant using the air drying device having the above configuration will be described. The drawing shows a state in which air is dehumidified in the dehumidification tower 2 and desiccant is regenerated in the dehumidification tower 3, with the double-lined portion showing the dehumidification path and the single-lined portion showing the regeneration path. Compressed air supplied from the air supply source 11 via the receiver tank 15 flows into the dehumidifier 1 from the air to be dried 4, passes through the four-way valve 5, the dehumidification tower 2, and the four-way valve 6, and then flows from the dry air outlet 10 to the use side. supplied to When the air pressure in the receiver tank 15 decreases due to the supply of air to the dehumidifier 1, the pressure switch 16 issues an operation signal Sp, the compressor 13 in the idle link (no load operation) state is switched to the load operation state, and the receiver This load operation continues until the gas pressure in the tank 15 recovers to a predetermined value. In this way, the compressor 13 calculates the amount of dry air used on the user side, that is, the air population to be dried 4
It is operated under load intermittently so as to discharge an air flow rate corresponding to the amount of air flowing into the pump, and the discharge flow rate is calculated by a computing unit 21. In the dehumidification tower 3, a part of the dry air from the dehumidification tower 2 is caused to flow into the dehumidification tower 3 via the flow rate control valve 7,
The desiccant is discharged from the discharge port 9 via the four-way valve 6 and the on-off valve 8, while the desiccant is heated by a built-in electric heater for a predetermined period of time (for example, 2 hours), and then the electric heater is turned off to release a portion of the dry air. The desiccant is cooled for a predetermined time (for example, 2 hours) to complete the regeneration, and the on-off valve 8 is closed to wait. On the other hand, the amount of moisture in the air to be dried (total 11) that has flowed into the dehumidifying tower 2 after the previous tower switching is determined by the calculator 22 for each intermittent operation of the compression 113 based on the operation signal Sp and the dew point signal S. It is calculated and integrated as an inflow moisture m signal S. When the inflow moisture amount signal S exceeds the allowable adsorption moisture m signal Sw issued by the setting device 23, the comparator 24
is the tower switching signal S. As a result, the four-way valve 5.6 switches to the state shown by the broken line, and the dehumidification tower 3 dehumidifies and the dehumidification tower 2 regenerates the desiccant in the same manner as described above, and thereafter this process is repeated alternately.

FIG. 2 shows the calculation procedure in the tower switching control device 20 described above. Compress first! ! When the operation signal S of 1113 is issued, the computing unit 21 counts the time, and when the cumulative time h (seconds) exceeds the time setting value T1 (for example, 30 minutes), the computing unit 22 sets the air dew point S. Temperature 1. (for example, 35℃) or higher, and if it is t1 or higher, 1
Count the pulses. Also, if the air dew point S is less than the set temperature t1, the cumulative time is the time set value T (T1
<■ For example, T2-40 minutes), the air dew point S is set at 1. , (11>t
For example, it is checked whether the temperature is above t2-30°C), and if it is above t2, one pulse is counted. Also, if the air dew point S is less than the set temperature t2, the cumulative time is set to 1.
After continuing to count the time until 1T3 (T2 < T3, for example, T3 = 50 minutes), one pulse is counted. After each count, the cumulative time is reset, and the pulse count cumulative value CNT is a count set value 1 corresponding to the allowable adsorbed moisture amount Sw issued by the setting device 23.
When it becomes equal to 00, after confirming the completion of regeneration of the dehumidification tower 3,
A tower switching signal S is generated by the comparator 24 to perform tower switching. In this embodiment, the air dew point S is divided into three stages, and the air containing the moisture content at the dew point of each stage is maintained for a set time T -
The inflow moisture amount is counted by assuming that equal m of moisture is brought into the dehumidification tower 2 at each T3, but if the above set dew point and corresponding time setting value are roughly divided into stages, the inflow moisture amount can be calculated as follows. It is possible to calculate more accurately.

In a dehumidifying tower that dehumidifies in this way, dehumidification is carried out to the fullest capacity of the desiccant, so dehumidification is carried out for the longest allowable time depending on the dew point of the inflowing air to be dried and 81 calculations. Compared to the conventional case where the towers were switched at regular intervals regardless of the dew point of the air to be dried or the amount of drying air used, it is possible to The tower switching time interval is greatly extended, the number of desiccant regenerations per year is reduced, and the energy consumption m, such as electricity for heating the desiccant, is reduced. In addition, the air flow rate, which is the basis for calculating the amount of water flowing into the dehumidification tower, is measured by integrating the generation time of the operating signal of the pressure switch 16, so there is no need for an expensive flow meter, and the pressure Since a failure of the switch 16 can be easily detected as a malfunction of the compressor 13, it is more convenient to use a flow meter, in which failure or deterioration of accuracy is not easy to detect, and the air flow rate can always be measured with high accuracy. Furthermore, in this embodiment, the amount of inflowing moisture is calculated by detecting the dew point of the air flowing into the dehumidification tower, so the amount of inflowing moisture can be determined with high accuracy, and the tower switching time interval can be adjusted especially depending on the desiccant capacity. It has the advantage of being able to be postponed until the end.

FIG. 3 shows a second embodiment of the present invention, in which a tower switching control device 30 is provided with a dew point setting section 31 instead of the thermometer 18 in the first embodiment, and the other points are as follows. It has the same configuration as the first embodiment.

In this embodiment, the dew point of the air flowing into the dehumidification tower is set to a constant dew point S3 predicted from the cooling water temperature of the aftercooler 4 and the suction air temperature of the compressor 13, and under this set dew point, the above-mentioned implementation is performed. As in the example, the inflow water m is calculated, compared with the allowable amount of adsorbed water, etc., and tower switching is performed. If different set values are used as the set dew point S depending on the seasons, for example, spring, summer, fall, and winter, the dew point of the incoming air can be approximated with relatively good accuracy, so this approximated dew point and
By calculating the amount of moisture flowing into the dehumidifying tower using an air flow layer compatible with "Using Dry Air," the tower switching time interval can be extended to fully correspond to the actual moisture inflow layer, compared to the conventional tower switching at fixed intervals. It is possible to make changes. Note that the allowable amount of moisture adsorbed by the desiccant is fixed, so setting the inflow air dew point to a constant dew point means setting the allowable inflow air m to the dehumidification tower or the allowable load operating time of the compressor 13 to a constant value. Nothing but. Therefore, the structure of the tower switching control device 30 is such that the inflow water content is indirectly calculated by calculating the inflow air or load operation time without actually numerically calculating the water content as shown in Fig. 4 or 5. configuration, which further simplifies the device.

In FIG. 4, reference numeral 21a measures and integrates the generation time of the operating signal S to produce an integrated air flow rate signal S2. Arithmetic unit that converts into 2
3a is a setting device 24 which generates an allowable inflow air port signal Swl determined from the set dew point S and the allowable amount of moisture adsorbed by the desiccant;
A is a comparator which compares this signal Sw1 with the integrated air flow rate signal Sfl issued by the computing unit 21a, and issues a tower switching signal S when the latter exceeds the former. Further, in FIG. 5, 21b is an arithmetic unit that measures the generation time of the operation signal Sp and outputs the cumulative operation time Sr2, and 23b is the set dew point S, the allowable adsorption moisture content of the desiccant, and the unit i interval of the compressor 13. a setting device that issues an allowable operating time Sw2 determined from the discharge amount;
Reference numeral 24b is a comparator that compares this signal Sw2 with the cumulative operating time signal S,2 issued by the calculator 21b, and issues a tower switching signal SC when the latter exceeds the former.

This invention is not limited to the above embodiments; for example, in the above embodiments, a thermometer is used as a detector for detecting the dew point of the air to be dried, so the device has the advantage of being inexpensive. However, a dew point meter may be used instead of this thermometer 18.

Further, in the above embodiment, the pressure switch 16 for commanding intermittent drive of the compressor is used as an operation signal generator that issues an operation signal synchronized with the load operation of the compressor. A dedicated operation signal generator or the like that generates a load operation signal may also be used. Also compression 81
When using a multi-cylinder type or single-acting double-acting switching type reciprocating compressor as 13, and changing the discharge amount of the compressor according to the degree of pressure drop in the receiver tank 15, the discharge amount at each load operation is It is sufficient to calculate the air flow ms according to the amount. Furthermore, the present invention can also be applied to a gas drying device that does not have the receiver tank 15.

Although the present invention has been described above in the case where it is applied to an air drying device, the present invention can also be applied to drying devices for various gases other than N2 gas, H2N2 gas, and air.

(Effects of the Invention) As explained above, according to the present invention, the amount of water flowing into the dehumidification tower can be adjusted by using an economical device with a simple configuration without using an expensive flowmeter such as an integrating flowmeter. The switching time interval of the tower that performs dehumidification and regeneration can be automatically adjusted according to It is possible to achieve energy saving by reducing energy consumption IR days.

[Brief explanation of drawings]

Fig. 1 is a system diagram of a gas drying device showing a first embodiment of the present invention, Fig. 2 is a flowchart showing calculation contents in the tower switching control device of Fig. 1, and Fig. 3 is a second embodiment of the invention. 1, FIG. 4, and FIG. 5 are system ports showing embodiments of the tower switching control device shown in FIG. 3. DESCRIPTION OF SYMBOLS 1... Dehumidification device, 2.3... Dehumidification tower, 4... Dry air inlet, 5.6... Four-way valve, 10... Dry air outlet, 11... Air supply source, 12...Motor, 13
...Compressor, 14...Aftercooler, 15...
Receiver tank, 16... Pressure switch (operation signal generator), 17... Compressor control device, 18... Thermometer (dew point detector), 20-... Tower switching control TM device, 21.
21a, 21b-- Arithmetic unit, 22... Arithmetic unit, 2
3.23a, 23b...setting device, 24.24a, 24
b...Comparator, 30-...Tower switching control device, 31...
・Dew point setting section.

Claims (1)

[Claims] 1. A compressor, a water-cooled aftercooler connected to the gas outlet side of the compressor, and a pair of dehumidifiers connected to the gas outlet side of the aftercooler and filled with a desiccant. The gas is dehumidified in one of the dehumidifying towers,
A gas drying device comprising a dehumidifying device that regenerates a desiccant in the other dehumidifying tower, and an operating signal generator that emits an operating signal synchronized with the load operation of the compressor, and a dehumidifying device that regenerates the desiccant into the one dehumidifying tower. A dew point detector detects the dew point of the gas, and a calculation is performed based on the generation time of the operation signal and the dew point detected by the dew point detector, and the amount of water flowing into the one dehumidification tower reaches a set value. 1. A gas drying apparatus comprising: a tower switching control device that issues a tower switching signal; and a tower that performs dehumidification and regeneration is switched based on the tower switching signal. 2 A compressor, a water-cooled aftercooler connected to the gas outlet side of this compressor, and one of a pair of dehumidification towers connected to the gas outlet side of this aftercooler and filled with a desiccant inside. Gas is dehumidified in a dehumidification tower,
A gas drying device comprising a dehumidifying device that regenerates a desiccant in the other dehumidifying tower, and an operating signal generator that emits an operating signal synchronized with the load operation of the compressor, and a dehumidifying device that regenerates the desiccant into the one dehumidifying tower. It is equipped with a dew point setting section that sets the dew point of the gas, and performs calculations based on the set dew point and the generation time of the operation signal, and switches the tower when the amount of water flowing into the one dehumidifying tower reaches the set value. 1. A gas drying device comprising: a tower switching control device that emits a signal, and switching between towers for dehumidification and regeneration is performed based on the tower switching signal.