JPS6231968B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semipermeable membrane dehumidifying device using a tube made of a semipermeable membrane that selectively transmits moisture.

Generally, in a semipermeable membrane dehumidifier, if moisture in the gas to be dried condenses on the surface of the semipermeable membrane, it cannot perform its original function of dehumidifying in the gas phase.
It is necessary to keep the gas to be dried above the dew point temperature. In addition, semipermeable membrane dehumidifiers are usually connected to the discharge side of a pump that absorbs and collects the gas to be dried, so the gas to be dried is pressurized by the pump, and the moisture concentration increases, making it easy to condense. Then, it is sent to a semipermeable membrane dehumidifier.

For this reason, conventionally, as shown in FIG. 1, a semipermeable membrane dehumidifier A and its attached equipment (pressure regulator a, flow meter b, filter c, constant differential pressure valve d, etc.) have been used.
was stored in thermostat B and kept at a high temperature (typically set at 40 to 50 degrees Celsius due to restrictions due to the heat resistance of semipermeable membranes) to prevent dew condensation. However, this method had the following drawbacks.

That is, as shown in FIG. 2, the semipermeable membrane has
(In addition, the gas to be dried is 20℃sat, H ₂ O, flow rate 1/
min, drying purge gas -70℃sat, _H2O , flow rate 3
/min) The higher the temperature, the lower the drying ability, and there is a characteristic that it decreases rapidly at 40 to 50°C. Therefore, in the conventional structure described above, the semipermeable membrane is used under temperature conditions where its drying ability is extremely reduced, and the efficiency of moisture removal is extremely low. When drying gases that contain high concentrations of moisture, such as combustion exhaust gas, it is necessary to use a large dehumidifier or to connect multiple dehumidifiers in series. Thermostatic chamber B was also large, which was very disadvantageous in terms of cost and space required. still,
In FIG. 1, e is a drain separator, f is a gas analyzer, and p is a suction pump.

The present invention is a semipermeable membrane dehumidifying device that solves the above-mentioned problems of preventing dew condensation and ensuring drying ability by simple means, and is capable of efficiently drying gas containing a high concentration of moisture. It provides:

Embodiments of the present invention will be described below based on the drawings.

FIG. 3 illustrates a semipermeable membrane dehumidifying device according to the present invention, and 1 is a semipermeable membrane [a polymer membrane that selectively permeates moisture; specifically, PERMA PURE PRODUCTS, INC. .) Product: Perma Pure Dryer (PERMA PURE
DRYER) is used. ] A multi-tube type inner tube (consisting of many thin tubes arranged in parallel, the diameter of each thin tube is usually 0.5 to 1.0
Set to mmφ. ), 2 is an outer tube fitted over this, the inner tube 1 is filled with a gas to be dried G ₁ containing moisture, and the gap formed between the inner and outer tubes 1 and 2 is filled with dry gas G ₂ for purging. By causing a water vapor pressure difference between the inside and outside of the semipermeable membrane forming the inner tube 1, the moisture in the gas to be dried _G1 moves into the semipermeable membrane.
It evaporates into the purge dry gas _G2 flowing outside the membrane and is carried away outside the vessel. 3a
is the inlet of the gas to be dried _G1 , 3b is its outlet, 4a
4b is the inlet of the dry gas G ₂ for purging, and 4b is its outlet, and these inlets and outlets are arranged so that the flow directions of both gases G ₁ and G ₂ are opposite to each other in order to increase the efficiency of moisture removal. ing.

In this embodiment, in the semipermeable membrane dehumidifier having the above configuration, heaters 5a and 5b are provided around the outer tube 2 on the side of the inlet _3a of the gas to be dried G1, so that only the inlet 3a side is connected to the side of the inlet of the gas to be dried _G1 . higher than the inlet temperature (this is the temperature of the gas to be dried G ₁ before entering the dehumidifier)
The temperature is set at 40 to 50°C, for example, in consideration of the water saturation temperature and the heat resistance of the semipermeable membrane. ), and keep the outlet 3b side at room temperature, or
Alternatively, an appropriate cooling means (not shown) may be used to cool down to room temperature or below, and the intermediate portion between the inlet 3a and the outlet 3b may be kept at an intermediate temperature.

According to the above configuration, a heater is provided on the outer circumference of the outer tube on the side where the gas to be dried is introduced to heat the gas to be dried and the gas to be dried G introduced into the inner tube 1 is heated. Since the temperature is set to be higher than ₁ , the gas to be dried _G1 is heated on the introduction side, and a part of the moisture contained therein is removed and the moisture concentration decreases, so the dew point temperature decreases.
Condensation is prevented. In addition, near the introduction side of the gas to be dried G ₁ , the temperature of the drying gas G ₂ for purging flowing in the opposite direction to that of the gas to be dried G ₁ is also appropriately heated, which is more effective in preventing the above-mentioned dew condensation. Be effective.

As mentioned above, the gas to be dried G ₂ from which a portion of moisture has been removed comes into contact with the semipermeable membrane at room temperature or lower, that is, in a temperature range where the semipermeable membrane has a high drying ability. Moisture removal by the membrane is effectively carried out without causing dew condensation.

FIG. 4 shows another embodiment. In this embodiment, the flow path of the dry gas _G2 for purging, which is formed by the gap between the inner tube 1 and the outer tube 2, is divided into two (or more) by a partition plate 6 provided in the middle part of the dehumidifier. Each divided flow path has an inlet 4a, 4a' and an outlet ₄ of the dry gas G2 for purging, respectively, at a position where the gas to be dried _G1 and the dry gas _G2 for purging flow counter-currently.
b, 4b' are provided to introduce the purge dry gas _G2 in parallel, and the purge dry gas _G2 is located upstream of the dry gas G1 (on the inlet 3a side of the dry gas _G1 ). Heater 5d at inlet 4a of G ₂
The drying gas _{G1 on the inlet 3a side is heated to a temperature higher than the moisture saturation temperature by heating the purge drying gas G2 ,} and the above-mentioned temperature gradient is obtained. be. In addition, as shown in the figure, it is desirable to provide a heat-insulating layer 7 around the outer tube 2 located on the upstream side to suppress heat loss due to heat radiation.

According to this embodiment, the following effects can be obtained in addition to the effects provided by the embodiments described above. That is, when the purge drying gas G ₂ is made countercurrent to the flow of the gas to be dried G ₁ , the purge drying gas G ₂
As it moves from the inlet to the outlet side, the amount of moisture permeated from the inner tube increases, so the moisture concentration of the dry purge gas _{G2 gradually} increases, and 3a side), the moisture carrying effect decreases. In this regard, in this embodiment, since the purge drying gas G ₂ is introduced in parallel into the flow path divided by the partition plate 6, the drying capacity near the inlet 3a of the gas to be dried G ₁ can be greatly improved. It is.

Although not shown, the embodiment shown in FIG. 3 may be implemented by adding a configuration in which the dry gas G ₂ for purging is introduced in parallel.

An outer tube is fitted over an inner tube made of a semi-permeable membrane that selectively permeates moisture, and a gas to be dried containing moisture is introduced into the inner tube from one end of the inner tube and taken out from the other end, Purge drying gas is flowed into the gap between the inner tube and the outer tube in a direction opposite to the direction in which the gas to be dried flows, and a heater is further provided on the outer periphery of the outer tube on the side where the gas to be dried is introduced. Since the drying gas inlet side is kept at a higher temperature than the gas to be dried, and the drying gas outlet side is kept at room temperature or lower, there is no moisture condensation, and the drying properties of the semipermeable membrane are maintained. You can make the most of your abilities,
The drying efficiency can be significantly increased by using an extremely simple structure that merely provides an appropriate temperature gradient to the dehumidifying device.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram illustrating a conventional dehumidifying drying device, FIG. 2 is a diagram showing the drying ability characteristics of a semipermeable membrane, and FIGS. 3 to 4 are dehumidifying drying devices illustrating embodiments of the present invention. FIG. 1... Inner tube, 2... Outer tube, 5a, 5b... Heater, _G1 ... Gas to be dried, _G2 ... Drying gas for purging.

Claims (1)

[Claims] 1. An outer tube is fitted over an inner tube made of a semi-permeable membrane that selectively permeates moisture, and a gas to be dried containing moisture is introduced into the inner tube from one end of the inner tube and drawn out from the other end. , a purge drying gas is flowed into the gap between the inner tube and the outer tube in a direction opposite to the direction in which the to-be-dried gas flows, and a heater is further provided on the outer periphery of the outer tube on the side where the to-be-dried gas is introduced. A semi-permeable membrane dehumidifying device characterized in that a side where a gas to be dried is introduced is kept at a higher temperature than the gas to be dried, and a side where the gas to be dried is led out is kept at room temperature or lower.