JPH0143569B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is equipped with two adsorption towers, and one adsorption tower performs an adsorption process in which humid air is passed through, dehumidified and dried, and air is sent outside the system, while the other adsorption tower heats the adsorbent to adsorb the adsorbent. In a heating regeneration type adsorption dehumidification device in which a heating regeneration process is carried out in which the adsorbent is regenerated through steps such as cooling after desorption of moisture adsorbed by the agent, and processes in both towers are alternately switched. This invention relates to a method for switching adsorption towers. Conventionally, there is a two-column switching heat regeneration adsorption dehumidifier that has been used to dehumidify and dry air for instrumentation and various processes, and is capable of supplying dry air with a low dew point. This two-tower switching type dehumidification device has two adsorption towers each filled with an adsorbent such as silica gel, activated alumina, or synthetic zeolite as a desiccant, and humid air is introduced into one adsorption tower to An adsorption process is performed in which moisture in the air is adsorbed and removed and dry air is sent outside the system, and the other adsorption tower performs a heating regeneration process consisting of heating, cooling, and switching preparation steps. In the heating process in the heating regeneration process, the adsorbent is heated by an electric heater installed in the tower, or hot air generated from another heat source is heated to the adsorption tower. By heating the adsorbent, the water adsorbed by the adsorbent is desorbed, and in the same cooling step, air at room temperature with little moisture is sent into the adsorption tower, and in the heating step, the adsorbent is heated. The adsorption function is restored by cooling the adsorbent, which has been heated to a high temperature. When the cooling process is completed, the system enters a switching preparation state, and the adsorbent in the adsorption tower in the adsorption process is removed from water. Before the dehumidification reaches saturation, the adsorption process is transferred to the adsorption tower that is ready for switching, and the dehumidification work is continued continuously. Therefore, the dehumidifier generally performs the adsorption step for 6 (or 8) hours, the heating step for 3 (or 4) hours, and the cooling step for 2.5 (or 8) hours.
3.5) A fixed process with a switching preparation process of 0.5 hours is adopted. However, conventional dehumidifiers are designed assuming that there is moisture in the air during hot and humid summer months.
Although the absolute amount of moisture to be adsorbed is generally small during spring, autumn, and winter when the amount of moisture in the air is not very high, if a certain processing time has elapsed according to the fixed program as mentioned above, Since the switching is forcibly performed even if the adsorbed moisture load is small, the heating regeneration process is carried out with a considerable amount of unsaturated adsorption zone remaining, and the heating energy during this heating regeneration process is used by means such as electric heating. This is not desirable in terms of energy saving, and
Since the adsorbent has to be regenerated more times than necessary, the adsorbent deteriorates more quickly and is uneconomical. The present invention has been made in view of the above-mentioned difficulties in the switching method of the conventional heat-regenerating adsorption dehumidifier, and has been made for the purpose of providing a switching method that can expect an energy-saving effect in the dehumidifier. , equipped with two adsorption towers, one adsorption tower performs an adsorption process in which humid air is passed through, dehumidified and dried, and air is sent outside the system, while the other adsorption tower heats the adsorbent so that the adsorbent adsorbs. In a heating regeneration type adsorption dehumidification device that performs a heating regeneration step in which the absorbed moisture is desorbed and then regenerates the adsorbent through a step such as cooling, and the processes in both towers are alternately switched.
The relative humidity or moisture content of the dehumidified air at the outlet of the adsorption tower in the adsorption process is electrically detected and input to the control unit, and when the control unit detects that the adsorbent has reached the breakthrough point, At the same time as switching the adsorption tower, the temperature of the regenerated exhaust gas at the outlet of the adsorption tower in the heating regeneration process is detected and inputted to the control section, and when the control section detects that the temperature of the regeneration exhaust gas has suddenly increased, the heating is started. When the temperature of the regenerated exhaust gas is detected after the completion of heating and it is detected that the temperature of the exhaust gas has reached a drop point, a command to complete the cooling process is issued, and the switching preparation process of the adsorption tower is started. It is something to do. That is, the switching method of the present invention constantly and accurately measures the adsorption breakthrough time of the adsorption tower by detecting the humidity or moisture content of the outlet air of the adsorption tower in the adsorption process, thereby determining the adsorption capacity of the adsorbent. The adsorption time can be extended by making full use of the adsorbent, and the number of regenerations of the adsorbent can be reduced to save thermal energy, and the deterioration of the adsorbent can be improved to extend its lifespan, thereby reducing maintenance costs. In addition to making it possible to achieve resource saving effects, it also makes it easier to detect equipment accidents, and it also makes it possible to always accurately measure the exhaust gas temperature or humidity at the outlet of the adsorption tower in the heating regeneration process, and to In this case, by cutting off the heating time of the adsorbent at a time that suits the actual situation, it is possible to save thermal energy by reducing the number of regenerations mentioned above, and also to save the adsorbent. Even in the process,
For example, when dry air at the outlet of an adsorption tower in the adsorption process is used for cooling, the energy saving effect can be achieved by terminating the consumption at a rate commensurate with the actual situation, just as in the heating process. As a whole, it is possible to achieve energy saving and resource saving effects as well as reduce operating costs. An example of an apparatus for carrying out the method of the present invention will be described below with reference to the drawings. In Figure 1, 1, 1' are adsorption towers filled with adsorbent, 2, 2', 3, 3', 4, 4', 5,
5', 6, and 6' are switching valves with actuators that switch the adsorption towers 1 and 1' for each process; 7 is a blower for supplying air during heating and regeneration; 8 is an air heater for heating and regeneration; 9 is a throttle valve that adjusts the amount of cooling air, 1
0 is a sensor for measuring the humidity of the air after dehumidification, 11 is a sensor for measuring the temperature of exhaust gas during heating regeneration, 12, 12', 13, 13',
14, 14', 15, 15', 16, 16' are the respective switching valves 2, 2', 3, 3', 4, 4', 5, 5',
Control solenoid valves corresponding to 6 and 6'; 17 an input section for inputting and amplifying electrical signals output from the humidity sensor 10 and exhaust temperature sensor 11; and 18 for inputting and amplifying electrical signals from the input section 17. , a calculation control unit that performs calculations based on the signal and sends a control signal to the control output unit 19; B is the outlet of the dehumidified air, C is the inlet of the air for heating and regeneration, D is the outlet of the regenerated exhaust gas, and E is the control solenoid valve. This is an inlet that supplies compressed air for operation. Next, an example of operation when the method of the present invention is carried out by the above-mentioned apparatus will be explained. Now, assuming that an adsorption process is being performed in the adsorption tower 1 and a heating regeneration process is being performed in the adsorption tower 1', the switching valves 2, 3, 4', and 5' are open;
3', 4, 5, 6, and 6' are in a closed state, and the humid air to be dehumidified is introduced from the lower part of the adsorption tower 1 from the inlet A through the switching valve 2, and flows inside the adsorption tower 1. As it rises, the adsorbent absorbs moisture and becomes dry air, which is discharged from the top of the tower to the outside of the tower, passes through the switching valve 3, and is supplied to processes outside the system.Meanwhile, in the adsorption tower 1', the air is heated Air for regeneration is sucked in by the blower 7 from its inlet C, and then passed through the air heater 8.
It is heated to become hot air, which is introduced into the tower from the upper part of the tower through the switching valve 4', descends inside the tower while desorbing the moisture adsorbed by the adsorbent in the tower, and flows out of the tower from the lower part of the tower. The exhaust gas passes through the switching valve 5' and is discharged from the outlet D to the outside of the system as regenerated exhaust gas. During this time, in the adsorption process, the humidity of the dehumidified air is measured by the humidity measuring sensor 10, and the humidity is sent to the input section as an electrical signal.
7, which is converted into a control signal and sent to the calculation control unit 18. When the calculation control unit 18 detects that the adsorbent has reached the breakthrough point based on the signal, it sends a signal to that effect. is sent to the control output section 19, and a tower switching command is issued from the output section 19. On the other hand, in the adsorption tower 1' which is in the heating regeneration process, the heating, cooling, and switching preparation processes are all completed while the adsorption process is being performed in the adsorption tower 1. , the exhaust gas temperature is measured by the exhaust gas temperature measuring sensor 11, and a signal is sent to the calculation control unit 18 via the input unit 17, and the control unit 18 detects that the exhaust gas temperature has suddenly increased. Then, a signal to that effect is sent to the control output unit 19 to issue a control command to complete heating and start cooling. According to this command, when cooling starts, the heat from the high temperature distribution zone of the adsorbent in the tower comes out to the exhaust gas, so the exhaust gas temperature rises once at first, and as the cooling process progresses, the exhaust temperature gradually decreases. Therefore, when the sensor 11 detects that the exhaust gas temperature has reached the drop point, it issues a command to complete cooling in the same manner as above and enters the switching preparation process. When the above heating step of the adsorption tower 1' is completed, the operation of the blower 7 and the air heater 8 is stopped by a signal from the control output section 19, while
The switching valve 4' is closed via the solenoid valve 14' and the switching valve 6' is opened via the electromagnetic valve 16', so that a part of the dry air discharged from the adsorption tower 1 is transferred to the adsorption tower 1'. The cooling process is started by supplying water from the top, and when the cooling process is completed, the switching valve 6' is closed again via the solenoid valve 16' to enter the switching preparation process. The switching valve 5' is also closed. When the adsorption tower 1' is in the switching preparation process as described above, when the adsorption process of the adsorption tower 1 is completed and a tower switching command is issued from the control output section 19, The switching valves 2, 3 are closed, and the switching valves 2', 3', 4, 5 are opened via the solenoid valves 12', 13', 14, 15, and the adsorption towers 1,
By switching the step 1', the adsorption tower 1' enters the adsorption process, and the adsorption tower 1 enters the heating regeneration process. If the adsorption process in one adsorption tower ends while the regeneration process of heating or cooling is being performed in the other adsorption tower, the calculation control unit 18 issues an alarm and sends a trip to the annunciator etc. The system shall send a signal to investigate whether the problem is due to deterioration of the adsorbent or a failure in another regeneration system, and take appropriate action. In addition, when using a relatively inexpensive and economical humidity sensor 10, the measurement range of the sensor is 30 to 100% relative humidity, while the specification required by the dehumidifier is 0.5% relative humidity (relative humidity 0.5%). Ball temperature 40℃,
In a case where the dew point temperature is -30 DEG C. or lower, the measurement position of the humidity sensor shown in FIG. 1 is inconvenient because it will be detected at a point that exceeds the permissible value. Therefore, in such a case, as shown in FIG. 2, the dehumidified air outlet ends a,
Sample air outlet b located slightly below a′,
b' is provided, and when the dehumidified air taken out from the air intake port reaches a humidity that can be measured by the sensor 10,
If the dehumidified air outlet ends a and a' of the adsorbent layer are designed to reach adsorption breakthrough, the same operation as the apparatus shown in FIG. 1 can be achieved. That is, in FIG. 2, 20, 20' are check valves,
Reference numerals 21 and 22 indicate valves, and 23 indicates a housing to which the humidity sensor 10 is attached. Dehumidified air whose humidity is to be measured passes through the air intake ports b and b', the check valves 20 and 20', and the valve 21 to the housing 23. humidity is detected and discharged outside the system through valve 22.
Humidity can be measured even under pressure by operations 1 and 22. Next, we actually used adsorption towers 1 and 1' in the apparatus shown in Figure 1, which were made of pressure-resistant vessels with an inner diameter of 300 mm and a total height of 2200 mm, and contained spherical particles with a diameter of 3 to 4 mm as an adsorbent. Filled with 80 kg of activated alumina and operated continuously for 1 year (7800 hours) at a pressure of 7 kg/ ^cm2 .
Table 1 shows a comparison between the results and the results when the same operation was performed according to conventional specifications.

[Table] In the conventional method, operation is performed throughout the year according to specifications that match the annual peak load, so the switching time is always 6 hours, of which the heating process is 3 hours and the cooling process is 3 hours.
2.5 hours, changeover preparation time 0.5 hours, etc., the number of times the adsorbent is regenerated is high, resulting in not only high power consumption but also high cooling air consumption. However, in the method of the present invention, by detecting the humidity or moisture content of the outlet air of the adsorption tower in the adsorption process, the adsorption breakthrough time of the adsorption tower is always accurately measured. In addition to making full use of the adsorption capacity of the adsorption tower and extending the adsorption time, the exhaust temperature or humidity at the outlet of the adsorption tower during the heating regeneration process is always accurately measured to ensure that the actual heating and cooling times are always updated. Compared to conventional methods, the number of adsorbent regenerations is reduced to 52%, power consumption is reduced to 49%, and cooling air consumption is also reduced to 48%. %, so
In addition to achieving a remarkable energy saving effect, the number of times the adsorbent is regenerated can be halved compared to the conventional method, and as a result, the life of the adsorbent can be approximately doubled, and a resource saving effect can be expected. It is extremely economical as maintenance costs can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an example of a heating regeneration type adsorption dehumidification apparatus for carrying out the method of the present invention, and FIG. 2 is a diagram showing a partially modified version of the apparatus shown in FIG. 1. 1, 1'...adsorption tower, 2, 2', 3, 3', 4,
4', 5, 5', 6, 6'...Switching valve, 7...Blower,
8... Regeneration air heater, 9... Throttle valve, 10... Humidity sensor, 11... Temperature sensor, 12, 12', 13,
13', 14, 14', 15, 15', 16, 1
6'... Solenoid valve, 17... Control input section, 18... Calculation control section, 19... Control output section, A... Humid air inlet, B... Dehumidified air outlet, C... Regeneration air inlet, D
...Regeneration exhaust outlet, E...Control compressed air inlet.

Claims (1)

[Claims] 1 Equipped with two adsorption towers, one adsorption tower performs an adsorption process in which humid air is passed through, dehumidified and dried, and air is sent outside the system, while the other adsorption tower heats the adsorbent so that the adsorbent adsorbs. In a heating regeneration type adsorption dehumidification apparatus, a heating regeneration process is performed in which the adsorbent is regenerated through a process such as cooling after desorption of moisture, and the processes in both towers are alternately switched. The relative humidity or moisture content of the dehumidified air at the outlet of the adsorption tower is electrically detected and input to the control unit, and when the control unit detects that the adsorbent has reached the breakthrough point, the adsorption tower At the same time, the temperature of the regenerated exhaust gas at the outlet of the adsorption tower in the heating regeneration process is detected and inputted to the control section, and when the control section detects that the temperature of the regenerated exhaust gas has suddenly increased, the heating is terminated. The heating method further comprises detecting the temperature of the regenerated exhaust gas after the completion of heating, and when it is detected that the temperature of the exhaust gas has reached a drop point, issues a command to complete the cooling step, and enters the switching preparation step of the adsorption tower. How to switch a regenerative adsorption dehumidifier.