JPH01199602A - Membrane demister - Google Patents

Abstract

PURPOSE:To completely exclude nonvolatile components and to perform high- purity separation and purification even in the rapid evaporation wherein droplets are inevitably entrained by completely removing the liq. droplets entrained by the supply vapor with the use of a hydrophobic membrane. CONSTITUTION:The liq. to be treated is vaporized under the conditions where liq. droplets are entrained, the entrained liq. droplets are removed by the demister, and only the vapor is passed. The demister for distilling and separating devices is formed with a hydrophobic membrane (e.g., polyethylene membrane) permeable to the liq. vapor and impermeable to the liq. As a result, nonvolatile components are completely excluded even in the rapid evaporation wherein liq. droplets are inevitably entrained, and high-purity separation and purification can be performed.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a membrane demister used in addition to a distillation/separation device.
It is related to.

<Prior Art> Distillation is a well-known traditional method for separating and purifying liquids.

In order to speed up the separation and purification in this distillation method,
It is necessary to increase the evaporation rate.

However, under such high speeds, the accompanying droplet bones increase and are mixed in the steam, and the non-volatile solute bones in the droplets are inevitably mixed into the steam condensation, resulting in a decrease in purification purity. I can't escape it.

<Problem to be Solved> For this reason, it has been proposed to evaporate the liquid at high speed under conditions with accompanying droplet bones, and to drain and remove the droplet bones by passing the droplet-containing vapor through a demister. There is. Although it has been considered to provide the demister with a baffle plate or a curved circuit in the ventilation passage, it is difficult to completely remove droplets with such a demister.

An object of the present invention is to provide a demister with excellent removal efficiency.

<Technical means for solving the problem> The membrane demister according to the present invention vaporizes the liquid to be treated under conditions that entrain droplets, removes the entrained droplets with the demister, and allows the vapor to pass through. The above demister for distillation/dissection equipment
This structure is characterized by being constructed of a hydrophobic membrane that does not allow liquid to pass through, but allows vapor of the liquid to pass through.

<Explanation of Examples> The present invention will be explained below with reference to the drawings.

In Figure 1, a is the raw water tank, b is the supply pump, and C
is an evaporator. d is a membrane demister according to the present invention, in which a porous membrane 2 is provided between the firebox and the secondary chamber, which does not allow liquid to pass therethrough but allows vapor of the liquid to pass therethrough. e is a condenser and f is a condensate tank. 7! ,...
is a pipe, solid lines indicate that the fluid is in a liquid state, and dotted lines indicate that the fluid is in a vapor state.

The hydrophobic membrane may include polyolefins such as polyethylene, polypropylene, and poly4-methylpentene-1, polysulfones such as polysulfone, and polyethersulfone,
Fluororesin-based materials such as polytetrafluoroethylene, polyvinylidene fluoride, and ethylene-tetrafluoroethylene copolymer can be used. It is also possible to use a hydrophilic membrane coated with a fluorine-based or silicone-based 18-aqueous resin to impart a hydrophobic function to the surface.

In order to process the raw liquid by the above separation system, the liquid in the raw water tank a is supplied to the evaporator C by the supply pump b and evaporated at a high speed. In this case, a large amount of droplets are involved.

This vapor is forced into the primary chamber of the membrane demister d. Therefore, vapor passes through the pores of the membrane 2 due to its gaseous state, but even if droplets try to pass through the pores of the membrane 2, their passage is blocked due to the aqueous nature of the membrane 2. be done. Therefore, as the droplets pass through the membrane, they adhere and accumulate on the surface of the membrane on the firebox side, drip through the membrane, and are returned to the evaporator C through the drain pipe 10. Therefore, the vapor that can pass through the membrane of the membrane demister d does not contain liquid droplets (therefore, it does not contain non-volatile components), and by condensing it in the condenser e, it becomes highly concentrated. A purity 9 permeate can be obtained.

The membrane demister may be of the platem frame type, hollow fiber type, spiral type or cartridge type, and the platem frame type is shown as a representative example in FIGS. 21gA to 2F.

As shown in FIG. 2A, the plate frame type membrane demister includes a unit 3 consisting of a support plate 1 having a corrugated shape and membranes 2 disposed on both sides of the support plate 1, which are spaced apart and have the same phase. It is a so-called laminated membrane demister formed by laminating a large number of layers, and the meandering gap formed between each unit 3 by being sandwiched between the membranes 1 is the supply steam passage 4, and the gap between each membrane and the support plate is is defined as a permeation vapor passage 5.

The specific structure of such a laminated membrane demister is shown in FIGS. 2B to 2F.

FIG. 2B shows a plan view of an example of the membrane support plate, and FIG. 2C
shows a cross-sectional view along vAc-c in FIG. 2B. The illustrated membrane support plate 1 has a flat band 11 formed along its longitudinal centerline, and this band is used as a collection path for permeated vapor. Further, a through hole 13 having a flat annular portion 12 is bored in the center of the band, and this through hole forms a permeated vapor outflow hole in the membrane demister, as will be described later. Further, flat annular portions 1 are provided at both ends of the membrane support plate on both sides of the center line.
A through hole 15 with 4 is drilled, which in the device forms a feed steam inlet hole 1&. The membrane support plate 1 has a corrugated shape 17 formed by machining, etc., except for its peripheral edge 16 and the flat annular portion around the through hole. The flat annular portions around each of the through holes 13 and 15 are formed in order to bring the ring spacer into close contact between the units 3, as will be described later.

The second diagram shows a laminated membrane demister in which a large number of units 3 each having membranes 2 disposed on both sides of such a corrugated membrane support plate 1 are laminated at intervals and in the same phase. , each unit 3 is fixed and sealed at one end via a banking 21 and furthermore, at an inner position adjacent to said banking 21, as will be described below. A supply steam inflow hole 23 is formed between the ring spacers 22 and for introducing supply steam into the supply steam passage 4 . Similarly, the other end of each unit 3 is also fixed and sealed by a banking 24, and is sandwiched between ring spacers 25 to discharge the supplied steam from the supplied steam passage 4, as will be described later. A supply steam outlet hole 26 is formed for the purpose of supplying steam.

The permeated vapor extraction hole 27 is formed at the center of the unit 3. That is, the center portion of the support plate constituting the unit is formed by a ring spacer 28, as will be described later.

FIG. 2E shows the details of the supply steam inflow hole 23, and each unit 3 is sandwiched between a first ring spacer 31 and a second ring spacer 33 with a communication groove 32, so that the unit A supply steam inflow hole 23 is formed therethrough. The supply steam is guided from the supply steam inflow hole to the supply steam passageway 4 through the communication groove 32 of the second ring spacer 33 . The supply steam outlet hole 26 is also formed in exactly the same manner.

FIG. 2F shows details of the permeated vapor outlet 27, in which the membrane support plate l is sandwiched between ring spacers 43 having the same communication grooves 42 as the second one, and the adjacent membranes 2 of the adjacent units 3 and the ring spacers are in watertight contact to form a permeate vapor outlet hole 27 passing through the unit. The permeated vapor passes from the permeated vapor passage 5 through the i+11 groove 42, joins the permeated vapor outflow hole 27, and is led out of the apparatus.

<Effects of the Invention> The membrane demister according to the present invention has the configuration as described above, and the use of a hydrophobic membrane can completely remove droplets accompanying the supplied steam, so that droplets are unavoidably accompanied by the supplied steam. Even with high-speed evaporation, it is possible to achieve high-purity separation and purification that completely eliminates unresolved components.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing a separation system using a membrane demister according to the present invention, Figure 2A, Figure 2B, Figure 2C1, Figure 2.
FIG. D, FIG. 2E, and FIG. 2F are explanatory diagrams showing one embodiment of the present invention. In the figure, d is a membrane demister 12,2'' is a hydrophobic membrane. and -11ゝ-1) 7'2mA r2(y γ2 group F

Claims (1)

[Claims] The liquid to be treated is vaporized under conditions that entrain droplets, and the demister of the distillation/separation device removes the entrained droplets and allows the vapor to pass through.The liquid does not pass through the demister, but the vapor of the liquid does. A membrane demister characterized by being composed of a hydrophobic membrane.