JPH0757345B2 - Multi-stage flash deaerator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a deaerator for a pure production apparatus by an evaporation method used in, for example, the semiconductor industry and other electronic industries, and more specifically, it relates to a deaerator for oxygen dissolved in a solution. The present invention relates to a multi-stage flash deaerator for effectively deaerating volatile gases such as carbon dioxide.

[Prior Art] Conventionally, as this type of deaerator, for example, the one shown in FIG. 2 has been known. In this deaerator, industrial water heated to a temperature higher than the operating temperature in the deaerator (1) enters the deaerator (1) from the outside through the solution introduction pipe (2), and the industrial water of the solution introduction pipe (2) is discharged. Filling part (4) filled with molding filler such as Raschig rings from the spray nozzle (3) attached to the tip
Sprayed on top. The industrial water sprayed by the spray nozzle (3) as the self-evaporation promoting means in this way becomes a droplet shape and, at the same time, is heated to a temperature higher than the deaerator operating temperature and self-evaporates to generate water vapor. Most of the volatile gas such as oxygen dissolved in is degassed.
For example, the operating temperature in the deaerator (1) is set to 38 ° C, the temperature before spraying with the industrial water spray nozzle is set to 38.5 ° C, and the dissolved oxygen dissolved in the industrial water at the inlet of the deaerator (1) is set. Amount 7p
If it is pm, the industrial water introduced into the spray nozzle (3) is sprayed by the spray nozzle (3) and at the same time self-evaporates by a temperature difference of 0.5 ° C. to generate water vapor. As a result, the oxygen partial pressure in the gas phase inside the deaerator (1) becomes lower than the equilibrium partial pressure, and about 90% (about 6.3 ppm) of the dissolved oxygen is degassed.
The residual volatile gas dissolved in industrial water (for example, about 10% of dissolved oxygen) is stripped under the deaerator (1) while the industrial water flows down the surface of the packing in the packing part (4). The vapor introduced from the vapor introducing pipe (7) comes into gas-liquid contact with the vapor,
Most of the remaining volatile gases are degassed. For example, when a pole ring is used as the molding filling, and the height of the filling portion is 4 m and the amount of dissolved oxygen on the upper surface of the filling is about 700 ppb, the volatile gas is degassed to about 10 ppb at the bottom of the filling portion. The molded packing is supported by, for example, a grid-shaped packing support (9) so as not to fall to the bottom of the deaerator, and the rising force of the stripping steam rising inside the packing section (4) on the top of the packing section. Thus, a wire mesh-shaped packing holder (10), for example, is attached so that the packing does not jump and break in the upper part of the deaerator (1).

The degassed water of the industrial water that has been degassed until the dissolved amount of the volatile gas becomes a trace amount is led out of the deaerator (1) from the bottom of the deaerator (1) through the outlet pipe (6). The degassed volatile gas, water vapor by self-evaporation, and stripping water vapor rising from the bottom of the filling part (4) are vent pipe (5).
Is discharged from the container.

[Problems to be Solved] As described above, in the conventional deaerator, the height of the filling portion (4) is high, and the filling support (9) and the filling retainer (10) are provided.
It has a complicated structure in which is attached, and has a drawback that the manufacturing cost is high. Further, when the filling section (4) is omitted and the degassing is performed only by the spray nozzle (3) in order to reduce the manufacturing cost, it is possible to degas the dissolved amount of the volatile gas in the degassed water to an extremely small amount. It was difficult.

In addition, when the amount of industrial water as treated water is abnormally increased due to dribbling during operation, the liquid flow velocity in the filling section (4) becomes excessive and stripping steam reaches the upper part of the filling section (4). There is a drawback that it is condensed in industrial water, and the partial pressure of the volatile gas in the gas phase becomes high, which lowers the degassing performance.

Further, in this type of deaerator, as the liquid descends in the filling section (4), the liquid tends toward the peripheral wall, and the stripping steam tends to flow in the central portion to cause a drift. Due to this tendency, stripping steam and industrial water do not come into contact with each other under a substantially uniform load, and there is a drawback that deaeration performance is deteriorated. In order to eliminate this drawback, a device shown in FIG. 3 was devised, for example. This is provided with a straightening plate (8) provided with a stripping steam rising pipe (11) and a perforated liquid flow hole (15) in the original filling section, and this is divided into two stages, upper and lower, and divided into upper and lower compartments. A packing support (9) and a packing retainer (10) are provided to fill the packing, and constitute the upper and lower packing parts (4a) and (4b) to almost uniformly redisperse industrial water and stripping steam. Is. However, in this device, the current plate (8)
There is a drawback that the height of the deaerator increases by the space for installing the space, and the number of installations of the packing support (9) and the packing retainer (10) is doubled to increase the manufacturing cost.

[Means for Solving the Problems] An object of the present invention is to provide a deaerator that overcomes all of the above problems.

That is, according to the present invention, the inside of the casing is divided into a plurality of evaporative degassing stages that are vertically continuous by a plurality of horizontal partition plates arranged at predetermined intervals, and the operating temperatures of these evaporative degassing stages are from the upper stage. It is set so that the temperature gradually decreases from the high temperature toward the lower stage, and the first evaporative degassing stage is provided with a solution introducing means for introducing a solution heated to a temperature higher than the operating temperature of the stage from outside the device. A self-evaporation promoting means for promoting self-evaporation of the solution, and a vent means for discharging the volatile gas deaerated from the solution together with the vapor and self-evaporation generated by the self-evaporation of the solution, 2 Each of the evaporating / desorbing stage to the final evaporating / deaerating stage has a solution introducing means, a self-evaporation promoting means, and a self-evaporating promoting means for introducing into the relevant stage a deaerating solution that is accumulated at the bottom of the previous stage and is kept at a higher temperature than that stage. Bent hand It is provided, in the end evaporation degassing stage bottom, characterized in that the deriving means for withdrawing the final degassed solution outside the vessel is provided, a multi-stage flash deaerator.

Here, the solution to be degassed is preferably industrial water, tap water, well water, etc., but is not limited thereto.

A spray nozzle is generally used as a means for promoting self-evaporation.

The number of evaporative degassing stages is, for example, three, but this is not a limitation.

[Operation] Each operating temperature of multiple evaporative degassing stages is set to gradually decrease from higher temperature as going from the upper stage to the lower stage, and the first evaporative degassing stage is heated to a temperature higher than the operating temperature of the stage. When the prepared solution is introduced and atomized into fine droplets, the solution itself generates water vapor by self-evaporation and is cooled. The water vapor generated by this self-evaporation lowers the partial pressure of the volatile gas in the vapor phase of the first evaporative degassing step to an average partial pressure or less, and also dissolves the volatile gas in the solution, such as oxygen or carbon dioxide gas. Degas most of the gas in the gas phase.

In addition, in each of the second evaporative degassing stage to the final evaporative degassing stage, when the degassing solution that is accumulated at the bottom of the previous stage and is kept at a higher temperature than that stage is introduced into that stage, the first evaporative degassing stage is introduced. Most of the remaining dissolved volatile gases are degassed from the solution, similar to the degassing action in.

The degassed final degassed solution is taken out of the device by the outlet means, and the volatile gas is discharged out of the device by the vent means.

[Example] An example of the deaerator of the present invention is shown in FIG.

In FIG. 1, the inside of the casing (14) is composed of two upper and lower horizontal partition plates (12) and (13) to form a chamber (I) of three upper, middle and lower stages.
It is divided into (II) and (III). In the upper room (I),
Industrial water introduction pipe (2), spray nozzle (3) for promoting self-evaporation attached to the tip of the introduction pipe, and water vapor generated by self-evaporation and deaerated volatile gas A vent pipe (5) for discharging to the is attached.

In the middle chamber (II), an opening is provided in an upper partition plate (12) that separates the upper chamber (I) from the middle chamber (II), and an industrial water introduction pipe (2) is hung in the opening. And a spray nozzle (3) for promoting self-evaporation at the tip of the introduction pipe (2), and a vent pipe for discharging steam generated by self-evaporation and deaerated volatile gas to the outside of the device. (5) is attached.

Similar to the middle chamber (II), the lower chamber (III) has an industrial water introducing pipe (2), a spray nozzle (3) and a vent pipe (5).
And a discharge pipe (6) for discharging degassed water obtained by degassing dissolved volatile gas from industrial water to the outside of the device.

In the deaerator (1) having the above configuration, the operating temperatures of the upper chamber (I), the middle chamber (II) and the lower chamber (III) are, for example, 38 ° C., 37.5 ° C. and 37 ° C., respectively. To
It is regulated by a vacuum device connected to each vent pipe (5). Then, the industrial water heated to 38.5 ° C. is introduced into the upper chamber (I) by the industrial water introduction pipe (2) and is made into fine droplets by the spray nozzle (3). As a result, the industrial water itself cools from 38.5 ° C to 38 ° C by generating steam by self-evaporation. The water vapor generated by this self-evaporation lowers the partial pressure of the volatile gas in the vapor phase of the upper chamber (I) space below the average partial pressure, and
Most of the volatile gases dissolved in industrial water, such as oxygen and carbon dioxide, are degassed from the industrial water into the gas phase. If the amount of dissolved oxygen in industrial water is 7 ppm, about 90% (about 6.
3ppm) is degassed.

The degassed volatile gas is discharged from the vent pipe (5) to the outside of the device by a vacuum device (not shown) together with water vapor generated by self-evaporation.

The industrial water from which most of the dissolved volatile gas has been degassed in the upper chamber (I) falls on the upper partition plate (12). Only the industrial water degassed in the upper chamber (I) is introduced into the middle chamber (II) from the partition plate (12) through the industrial water introducing pipe (2), and the upper chamber (I). The self-evaporating water vapor and the volatile gas therein are all discharged from the vent pipe (5) of the upper chamber (I).

The industrial water introduced into the middle chamber (II) at its own temperature of 38 ° C is sprayed into the space of the middle chamber by the spray nozzle (3) and self-evaporates by the temperature difference of 38 ° C, resulting in the upper chamber (I). Most of the residual dissolved volatile gases are degassed from industrial water as well as the degassing action. For example, in the case of dissolved oxygen, about 90% (630 ppb) of the dissolved amount of about 700 ppb is desorbed, and the dissolved oxygen amount in the industrial water at the bottom of the intermediate chamber (II) becomes 70 ppb.

The degassed volatile gas and self-evaporated water vapor are all discharged from the vent pipe (5) of the intermediate chamber (II) to the outside of the device by a vacuum device.

In the lower chamber (III), the same degassing action as in the middle chamber (II) is performed, and the dissolved volatile gas in the industrial water is finally degassed to an extremely small amount. For example, lower room (III)
The dissolved oxygen content in the degassed water at the bottom is about 63 ppb degassed if the dissolved oxygen content in the industrial water introduced into the lower chamber is 70 ppb,
It is a very small amount of about 7ppb.

The industrial water in which the dissolved volatile gas has been treated to this extremely small amount, that is, deaerated water, is led out of the deaerator through the outlet pipe (6) at the bottom of the lower chamber (III).

[Advantages of the Invention] According to the deaerator of the present invention, unlike the conventional deaerator, the filling part, the filling support, the filling retainer and the flow straightening plate are not required, and the structure is simple and the manufacturing cost is low. Tsuku.

Also, even if the amount of industrial water increases excessively due to an abnormal phenomenon during operation, dissolved volatile gas is degassed with self-evaporation, so degassing performance is not deteriorated and there is no filling part. Therefore, the degassing performance does not deteriorate due to the increase in the liquid load.

Further, since stripping steam is not used, degassing performance is not deteriorated due to non-uniform contact of steam and solution.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a deaerator showing an embodiment of the present invention,
2 and 3 are vertical cross-sectional views of a conventional deaerator. (2) …… Industrial water inlet pipe, (3) …… Spray nozzle, (5) …… Vent pipe, (6) …… Outlet pipe, (12)
(13) …… Partition plate, (14) …… Casing, (I) ……
Upper room, (II) …… Middle room, (III) …… Lower room.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Suematsu 1-6-14 Edobori, Nishi-ku, Osaka-shi, Osaka Prefecture Hitachi Shipbuilding Co., Ltd. (72) Kazunori Kiba 1-6-14 Edobori, Nishi-ku, Osaka-shi, Osaka Within Hitachi Zosen Corporation

Claims (1)

[Claims] 1. A casing is divided into a plurality of evaporative degassing stages that are vertically continuous by a plurality of horizontal partition plates arranged at predetermined intervals, and the operating temperatures of these evaporative degassing stages are from upper to lower stages. The temperature was set to gradually decrease from high temperature as it went to the first evaporative degassing stage, and the solution introducing means for introducing the solution heated to a temperature higher than the operating temperature of the stage from the outside was introduced. A self-evaporation promoting means for promoting self-evaporation of the solution, and a vent means for discharging volatile gas deaerated from the solution together with vapor and self-evaporation generated by the self-evaporation of the solution are provided. Each of the stages from the evaporative degassing stage to the final evaporative deaerator stage has a solution introducing means, a self-evaporation promoting means and a vent for introducing the degassing solution accumulated in the bottom part of the previous stage and kept at a higher temperature than that stage. Means provided Is the final evaporation the degassing step bottom, characterized in that the deriving means for withdrawing the final degassed solution outside the vessel is provided, a multi-stage flash deaerator.