JPH0127770B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for regenerating a desiccant in a pressurized gas dehumidifier that removes moisture from pressurized gas such as compressed air.

One way to obtain dry gas by removing moisture from the gas is to pass the gas to be dried through a dehumidifying tower filled with a desiccant such as silica gel or activated alumina. When used, it becomes saturated with water and loses its dehumidifying ability, so it needs to be regenerated. However, when the gas to be dried is a pressurized gas such as compressed air with a pressure of about 7 kg/cm ² , conventionally the pressure inside the dehumidifying tower performing regeneration is first lowered to atmospheric pressure, and heated gas such as heated air and room temperature air are Cooling gas such as the above gas is passed through the dehumidification tower at almost atmospheric pressure as a regeneration gas, and the desiccant is heated and cooled to restore the dehumidification capacity, and then the to-be-dried gas is fed into the regeneration dehumidification tower little by little. The pressure inside the dehumidification tower was increased by flowing into the dehumidification tower, thereby eliminating the shock when switching between regeneration and dehumidification towers. The pressure inside the dehumidifying tower must be gradually lowered and raised using on-off valves, etc., so it takes time to lower and raise the pressure, which shortens the original regeneration time (heating and cooling). Gas supply blowers, heaters, coolers, etc. have become larger, and if towers are switched without sufficient pressure reduction or pressure increase due to clogged on-off valves, etc., accidents such as crushing of the desiccant and damage to the dehumidification tower may occur. There was a problem.

This invention solves the above-mentioned conventional drawbacks,
We would like to provide a method for regenerating the desiccant in a pressurized gas dehumidifier, which performs dehumidification and regeneration of the desiccant under almost the same pressurized state, thereby eliminating the need for lowering or increasing the pressure before and after switching the tower, and which can achieve downsizing of the equipment. The gist of this is that pressurized gas is dehumidified in one of a pair of dehumidifying towers filled with a desiccant, which are selected alternately, and the pressurized gas is dried in the other dehumidifying tower. In a desiccant regeneration method in which the desiccant is regenerated by heating and then cooling the desiccant, a cooler, a drain separator, a blower, and a heater are connected in series to the other dehumidification tower to form a closed circuit, and the closed circuit is At the same time, the pressurized gas flow path of one of the dehumidification towers and the closed circuit are connected with a pressure equalizing pipe, and the desiccant is heated and cooled by circulating the regeneration gas inside the dehumidification tower. The purpose is to make the pressure in the closed circuit almost the same as the pressure in the pressurized gas flow path of the one dehumidification tower.

An embodiment of the present invention will be described below with reference to the drawings.

In the figure, 1 is a dehumidifying device for dehumidifying compressed air, 2 and 3 are dehumidifying towers, and a pressure-resistant casing is filled with a desiccant such as silica gel, activated alumina, or synthetic zeolite. 4 is a gas inlet connected to a compressed air supply source, 5 is a dry gas outlet connected to the use side, and 6 and 7 are four-way valves for column switching. Further, reference numeral 8 denotes a four-way valve for switching the direction of heating and cooling flow inserted into the pipe line 9 connecting the four-way valves 6 and 7;
0 is a loop-shaped pipe connecting the other two ports of this four-way valve. Inside this conduit 10, a cooler 11 using cooling water, a drain separator 12, a blower 13, and an electric heater 14 are inserted and connected in series. 15 is a drain trap for discharging drain water. Further, 16 is a pressure equalizing pipe connecting the suction side of the blower 13 and the vicinity of the gas outlet 5, and 17 is a check valve provided in the middle of this pressure equalizing pipe.

Next, a method for regenerating the desiccant using the dehumidifying device 1 having the above configuration will be explained. The drawing shows the dehumidification of compressed air at a pressure of, for example, 7 kg/cm ² in the dehumidification tower 2, and the regeneration of the desiccant in the dehumidification tower 3. The arrow indicates the direction in which the regeneration gas flows while the desiccant is being heated, and the dashed arrow indicates the direction in which the regeneration gas flows during the cooling of the desiccant.

First, compressed air, which is the gas to be dried, flows from the gas inlet 4 through the four-way valve 6 into the dehumidifying tower 2, and after dehumidifying, passes through the four-way valve 7 and flows out from the gas outlet 5, where it is used as pressurized dry air. On the other hand, when the four-way valve 8 is in the switching state shown by the solid line, the pipes 9 and 10 form a closed circuit 18 connected to the dehumidification tower 3. Further, the pressure equalizing pipe 16 adjusts the pressure in the pressurized gas flow path of the dehumidification tower 2 to the closed circuit 18.
The pressure is transmitted to the inside and the pressure is maintained at approximately the same level between the two. Therefore, when the blower 13 is operated and heating is performed by the heater 14, the air in the closed circuit 18 discharged by the blower 13 passes through the four-way valves 8 and 7 and flows into the dehumidifying tower 3 as heating gas for regeneration. The desiccant is heated by flowing in the opposite direction to that during dehumidification through the four-way valves 6 and 8.
The condensed water is then cooled by the cooler 11, and the condensed water is separated by the drain separator 12.
Return to step 3 and repeat the cycle. When the pressure in the closed circuit 18 drops as the condensed water is removed by the drain separator 12 and discharged from the drain trap 15, pressurized air is discharged from the pressurized gas flow path of the dehumidification tower 2 via the pressure equalization pipe 16. is replenished into the closed circuit 18 to maintain the pressure in the closed circuit at approximately the same pressure as the pressure in the pressurized gas flow path. The check valve 17 also prevents moist air in the closed circuit 18 from being supplied to the gas outlet 5.

After heating the desiccant in the dehumidifying tower 3 for a predetermined period of time (for example, 2 hours) as described above, the four-way valve 8 is switched to the state shown by the broken line, and the heating of the heater 14 is cut off. As a result, the air in the closed circuit 18 cooled by the cooler 11 and discharged from the blower 13 passes through the four-way valves 8 and 6 and circulates in the dehumidifying tower 3 as cooling gas for regeneration in the opposite direction to that during heating. After the desiccant is cooled, it is cooled by the cooler 11 via the four-way valves 7 and 8, and after the condensed water is separated by the drain separator 12, it returns to the blower 13, and the cycle is repeated. At this time, the pressure equalization pipe 16 provides a pressure equalization effect similar to that during heating of the desiccant described above, and the pressure in the closed circuit 18 is maintained at approximately the same pressure as the pressure in the pressurized gas flow path of the dehumidification tower 2.

After cooling the desiccant in the dehumidifying tower 3 for a predetermined period of time (for example, one hour) as described above, when the desiccant is cooled, the four-way valves 6 and 7 are switched to the flow state shown by the dotted line, and the desiccant in the dehumidifying tower 3 is cooled. The gas is dehumidified by regenerating the desiccant in the dehumidifying tower 2 in the same manner as described above, but when switching the tower, the dehumidifying tower 2
Since the pressure inside the chamber and the column 3 are almost the same, switching of the columns can be carried out in a very short time with few shocks, and dehumidification and regeneration can be started immediately.

In the above embodiment, the direction of flow of the heated gas in the dehumidification tower during regeneration is reversed to that during dehumidification, so that when dehumidifying a large amount of water, the desiccant on the upstream side is turned to the downstream side and the heated gas is flowed. , moisture evaporation is completed in a short time, and the flow direction of the cooling gas in the dehumidification tower during regeneration is the same direction as during dehumidification (opposite direction to that during heating), so a large amount of moisture is adsorbed during dehumidification. By cooling the desiccant on the side to a lower temperature, the dehumidifying ability can be recovered quickly, resulting in a shorter regeneration time compared to a parallel flow system in which the gas flows during dehumidification, heating, and cooling all flow in the same direction. This has the great advantage of requiring only about half the cost. Note that the present invention is also applicable to the case of the above-mentioned parallel flow type, and in this case, the four-way valve 8 can be omitted, and the apparatus is simplified. Further, in the above embodiment, the pressure equalizing pipe 16 is connected to the vicinity of the gas outlet 5, which is approximately the lowest pressure part on the dehumidification side, and to the blower 1, which is approximately the lowest pressure part in the closed circuit 18.
3 is connected to the suction side of dehumidifier 13, which is a reasonable connection position where the pressure difference between dehumidification towers 2 and 3 is particularly small. In particular, when the pressure equalization pipe 16 is connected to the vicinity of the gas inlet 4 before dehumidification, the check valve 17 becomes unnecessary.

Although the present invention has been described above in a case where it is applied to a dehumidifying device for compressed air, the present invention can also be applied to a dehumidifying device for N ₂ gas and other various pressurized gases.

As explained above, according to the present invention, dehumidification of pressurized gas and regeneration of desiccant are performed at almost the same pressure in both dehumidification towers, so there is no need to lower or raise the pressure when switching towers. Even if the tower is switched at this point, accidents such as crushing of the adsorbent and damage to the dehumidification tower will not occur. In addition, since no time is required for pressure reduction and pressure increase, the regeneration time can be fully utilized for heating and cooling the desiccant, resulting in less regeneration air volume and, since the pressure during regeneration is high, the apparent regeneration gas Since the flow rate is a fraction of that in low-pressure regeneration, the heater, cooler, blower, piping, etc. can all be small. Further, since the pressure of the drying gas flow path and the regeneration gas flow path is approximately the same, there is almost no problem with sealing performance (passing through) at the four-way valve portion for switching the column. In addition, in the case of conventional low-pressure regeneration, a troublesome sealing mechanism such as a water seal was required to discharge the condensate, but with this invention, since there is no suction of outside air with high-pressure regeneration, an automatic opening/closing system using a float that is easy to maintain. A drain trap or the like can be used.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an example of an apparatus for carrying out the method of the present invention. DESCRIPTION OF SYMBOLS 1... Dehumidification device, 2... Dehumidification tower, 3... Dehumidification tower, 6... Four-way valve, 7... Four-way valve, 8... Four-way valve, 9... Pipe line, 10... Pipe line, 11... ... Cooler, 12 ... Drain separator, 13 ... Blower, 14 ... Heater, 16 ... Pressure equalization pipe, 18 ...
closed circuit.

Claims (1)

[Claims] 1 Out of a pair of dehumidifying towers filled with desiccant inside, pressurized gas is dehumidified in one of the dehumidifying towers selected alternately, and in the other dehumidifying tower, the desiccant is heated and then cooled to regenerate the desiccant. In the desiccant regeneration method, a cooler, a drain separator, a blower, and a heater are connected in series to the other dehumidification tower to form a closed circuit, and a regeneration gas is circulated within the closed circuit to heat the desiccant. At the same time, the pressurized gas flow path of the one dehumidifying tower and the closed circuit are connected with a pressure equalizing pipe, and the pressure in the closed circuit during the regeneration is controlled by the dehumidifying tower of the one dehumidifying tower. A method for regenerating a desiccant in a pressurized gas dehumidifier, characterized in that the pressure is made to be approximately the same as the pressure in a pressurized gas flow path.