JPH03186315A - Dehumidifier device - Google Patents

Abstract

PURPOSE:To rapidly obtain dry gas of low dew point by providing drying agent for adsorbing moisture in a passage for dehumidified gas discharged from a membrane housing and feeding the dehumidified gas to a low pressure region to effect purging. CONSTITUTION:High pressure gas to be dehumidified flows into hollow fiber membranes 2 and then into a passage 1b. The outer surface side of the membranes 2 communicates with the atmosphere through a purge outlet hole 1d, while a chamber S1 is divided into a high pressure region in the hollow fiber membranes 2 and a low pressure region outside the membranes 2. The high pressure dehumidified gas having undergone osmotic separation action and having passed through the membranes 2 is passed through a passage 1b, into the chamber S2 and then through drying agent 5 therein to be dehumidified. The gas having undergone adsorption and having passed through the agent 5 flows into the low pressure region in the chamber S1 from a purge hole 1c and flows over the outer surfaces of the membranes 2 and then to the atmosphere from the hole 1d. As a result, dry gas having low dew point can be rapidly obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dehumidifying device that removes moisture from compressed gas using a polymer separation membrane.

[Prior Art] This type of dehumidification device is disclosed in Japanese Patent Application Laid-Open No. 62-42723. In this device, a large number of hollow fiber membranes made of polymer separation membranes are bundled together in a sealed container, and the inside of the sealed container is divided into an area inside the hollow fiber membrane and an area outside the hollow fiber membrane. High-pressure water vapor mixed gas is supplied to the area outside the hollow fiber membrane, and dehumidified gas is supplied into the hollow fiber membrane. Moisture in the steam mixture gas permeates and separates into the hollow fiber membrane through the hollow fiber membrane, and the water that permeates and separates into the hollow fiber membrane is discharged to the outside of the sealed container together with the dehumidified gas (purge gas) flowing inside the hollow fiber membrane. be done. This polymer separation membrane system has various advantages such as continuous dehumidification, long life of the separation membrane, and non-vibration-free structure.

[Problem to be solved by the invention] In a dehumidifying system using a polymer separation membrane, not only the pressure difference between the high and low pressure regions bordering the polymer permeable membrane, but also the water vapor partial pressure difference between the two regions can be reduced by the polymer separation membrane. The lower the humidity on the low-pressure region side, the higher the osmotic separation effect. In order to increase the water vapor partial pressure difference between the two pressure areas, the low pressure area side is purged with gas after dehumidification, but at the beginning of the supply of high pressure water vapor mixed gas, there is a difference in the water vapor partial pressure between the high and low pressure areas. do not have. Therefore, the necessary permeation separation effect cannot be obtained at the initial stage of supply of the water vapor mixed gas, and it takes time until the required low dew point is achieved. Such drawbacks are particularly fatal when water vapor mixed gas is supplied intermittently.

SUMMARY OF THE INVENTION An object of the present invention is to provide a dehumidifying device that can shorten the time required to achieve the required low dew point.

[Means for Solving the Problems] To this end, the present invention provides a desiccant that adsorbs moisture on the path of the dehumidified gas discharged from the membrane housing, which is separated into a high pressure region and a low pressure region by a polymer separation membrane. A part of the adsorbed and dehumidified gas that has passed through the desiccant is supplied to the low pressure region for purging.

[Operation] When the supply of high-pressure pre-dehumidification gas to the high-pressure region in the membrane housing starts, there is no water vapor partial pressure difference between the high and low pressure regions, and the pre-dehumidification gas undergoes osmotic separation based solely on the pressure difference between the high and low pressure regions. be affected. Therefore, in the early stage of supply of high-pressure pre-dehumidification gas, the degree of dehumidification of the post-dehumidification gas which is extracted to the outside of the membrane housing due to the permeation separation effect is low, but the dew point of the high-pressure gas that has passed through the desiccant and been adsorbed and dehumidified is It is lower than the high pressure gas immediately after passing through the membrane housing. A portion of the adsorbed and dehumidified gas that has passed through the desiccant is supplied to the low pressure region to purge the low pressure region. Therefore, compared to the case where the dehumidified gas immediately after passing through the membrane housing is used for purging, the water vapor partial pressure decreases faster in the low pressure region, and the dew point of the dehumidified gas that has passed through the membrane housing is at the required level. rapidly decreases to .

[Example] Hereinafter, an example embodying the present invention will be described based on the drawings.

A pair of chambers St and S! are partitioned by a partition wall 1a in the middle of the housing 1. One chamber SI accommodates a large number of hollow fiber membranes 2 made of polymer separation membranes, and both chambers SI,
S! are communicated by a passage lb on the partition wall la. A large number of hollow fiber membranes 2 are bound at both ends by seal members 3 and 4, and the seal members 3 and 4 are tightly fitted and fixed to the peripheral wall of the chamber S+. The other room S! A desiccant 5 is housed in, and is held between a pair of holding plates 6 having a large number of through holes 6a. Both chambers St, S! A cap 7.8 is tightly fitted into the opening, and the cap 7 has a supply port 7a extending therethrough, and the cap 8 has a discharge port 8a extending therethrough. The high-pressure pre-dehumidification gas is supplied from the supply port 7a via the supply pipe 9,
It passes through a large number of hollow fiber membranes 2 and exits to the passage 1b. The high pressure gas discharged to the passage ib passes through the desiccant 5 and flows out from the discharge port 8a to the discharge pipe 10.

A purge hole 1c and a purge outlet 1d are transparently provided in the housing l so as to communicate with the chamber S1.
d communicates with the atmosphere. The purge inlet 1c and the discharge pipe 1O are connected by a purge pipe 11, and a flow rate regulating valve 12 is interposed on the purge pipe 11.

The high-pressure pre-dehumidification gas supplied into the housing l from the supply port 7a of the cap 7 enters the hollow fiber membrane 2 and passes through the passage 1.
The withdrawal goes to b. The outer surface side of the hollow fiber membrane 2 communicates with atmospheric pressure via the purge outlet 1d, and the chamber S1 is divided into a high pressure region inside the hollow fiber membrane 2 and a low pressure region outside the hollow fiber membrane 2. Moisture in the high-pressure gas passing through the hollow fiber membrane 2 permeates to the outside of the membrane due to the difference between the high pressure on the inner surface of the hollow fiber membrane 2 and the atmospheric pressure on the outer surface of the hollow fiber membrane 2, and the difference in water vapor partial pressure between the inside and outside. The high-pressure dehumidified gas that has passed through the hollow fiber membrane 2 under the osmotic separation action flows into the chamber S through the passage 1b, and then flows into the chamber S! Desiccant inside 5
go through. The dehumidified gas passing through the desiccant 5 is subjected to the adsorption action of the desiccant 5 and is further dehumidified.

The adsorbed and dehumidified gas that has passed through the desiccant 5 is passed through the flow rate adjustment valve 12.
Depending on the degree of adjustment, the flow is diverted to the purge pipe 11 side, and flows into the low pressure region in the chamber SI through the purge inlet 1c. Then, it sweeps the outer surface of the hollow fiber membrane 2 and exits to the atmosphere through the purge hole 1d.

When the pre-dehumidification gas supply starts, there is almost no water vapor partial pressure difference between the high and low pressure regions in the chamber S1, so the osmotic separation effect of the hollow fiber membrane 2 is low, and immediately after the pre-dehumidification gas supply starts, the water vapor passes through the hollow fiber membrane 2. The degree of dew point reduction of the dehumidified gas, that is, the degree of dryness, is low. This dehumidified gas with a low degree of dryness passes through the desiccant 5 and is subjected to an adsorption action, and the degree of dryness of the adsorbed and dehumidified gas that has passed through the desiccant 5 increases. By using a part of this highly dry adsorbed post-dehumidifying gas as the purge gas, the water vapor partial pressure on the low-pressure region side can be quickly lowered. The pressure difference decreases quickly. As a result, the dew point of the high-pressure gas that has passed through the hollow fiber membrane 2 is reduced to a desired value in a short time, and smooth dehumidification without dew point deficiency is possible even at the initial stage of gas supply before dehumidification.

When the dew point of the dehumidified gas that has passed through the hollow fiber membrane 2 becomes sufficiently low, the dehumidified gas that has passed through the hollow fiber membrane 2 begins to remove moisture adsorbed by the desiccant 5, and the pre-dehumidification gas supply starts. Sometimes the desiccant 5 is dried and regenerated. Therefore,
When the supply of the pre-dehumidification gas is started, the dehumidification device is always in the best dehumidification start condition, and even when the pre-dehumidification gas is supplied intermittently, continuous dehumidification is performed without insufficient dew point.

Of course, the present invention is not limited to the above-mentioned embodiments. For example, the housing of the hollow fiber membrane and the desiccant housing may be separated, or the adsorption may be carried out only on the purge pipe 11 branching from the discharge pipe 10 in the above-mentioned embodiments. It is also possible to use an agent or to use a high pressure region outside the hollow fiber membrane.

[Effects of the Invention] As detailed above, the present invention provides a desiccant that adsorbs moisture on the path of the dehumidified gas discharged from the membrane housing, which is separated into a high-pressure region and a low-pressure region by a polymer separation membrane. Since the purge is performed by supplying a part of the gas after adsorption and dehumidification that has passed through the desiccant to the low pressure region, the dew point of the purge gas supplied to the low pressure region can be quickly adjusted from the time when the supply of the pre-dehumidification gas starts. As a result, the partial pressure of water vapor in the low-pressure region can be quickly reduced, and the supply of the pre-dehumidification gas can be started quickly to obtain dry gas with a low dew point, which is an excellent effect.

[Brief explanation of drawings]

The drawing is a longitudinal sectional view showing an embodiment embodying the present invention. A housing 11 serving as a membrane housing, a chamber St serving as a passage for the hollow fiber membrane 2, the desiccant 5, and the dehumidified gas.

Claims (1)

[Claims] 1 Supply high-pressure gas before dehumidification from outside the membrane housing (1) along the membrane surface on the high-pressure area side into the membrane housing (1), which is separated into a high-pressure area and a low-pressure area by a polymer separation membrane, and In a dehumidifier that purges the low pressure region by discharging the dehumidified gas to the outside of the membrane housing (1) and supplying a portion of the dehumidified gas discharged to the outside of the membrane housing (1) to the low pressure region, A desiccant (5) that adsorbs moisture is interposed on the path (S_2) of the dehumidified gas to be discharged,
A dehumidifying device characterized in that a part of the adsorbed and dehumidified gas that has passed through the desiccant (5) is supplied to the low pressure region for purging.