JP2010042331A - Ballast water treatment apparatus loaded with an ozone producing device using pressure swing adsorption method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing ozone used for sterilization of marine organisms in ballast water by adsorption and desorption of ozone according to pressure swing adsorption (PSA). <P>SOLUTION: A two-component gas of ozone and oxygen supplied from a silent discharge ozone generator 3, which is an ozone producing device, is subjected to ozone/oxygen separation using an ozone adsorbent 6 under a relatively high-pressure condition, and the recovered oxygen is reused as a raw material of the ozone generator. The adsorbed ozone is obtained by desorbing and recovering ozone as a two-component gas of ozone and air under a relatively low-pressure condition by using dry air as a purge gas. The low-cost two-component gas of ozone and air is used for sterilization 23 of marine organisms in the ballast water to enable provision of economical and compact marine organism sterilization in the ballast water. The ozone adsorbent is one or more kinds selected from the group consisting of pentasil zeolite, acid-treated pentasil zeolite, mesoporous silica, and acid-treated mesoporous silica. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a ballast water treatment device for killing marine organisms such as plankton, bacteria, and viruses contained in ship's ballast water by ozone, and ozone of an ozone adsorbent at a high adsorption pressure and a low desorption pressure. The present invention relates to a method for producing and storing ozone using a difference in adsorption amount. Specifically, the present invention relates to a method for producing ozone by adsorbing and desorbing ozone according to pressure swing adsorption (PSA) using a specific adsorbent having a high ozone adsorption capacity.

When navigating cargo ships that transport crude oil, etc., when there is little air cargo or cargo, ballast water will be installed before leaving the port due to the need to secure the depth of the propeller and ensure the stability of the hull. . On the other hand, this ballast water is discharged before entering the loading port.
By the way, since seawater is generally used for ballast water, it includes marine organisms such as plankton, bacteria, and viruses in the port where it is taken. Will also be released around the loading port. Therefore, the problem of these marine organisms breeding in foreign ports that are not their native habitat and adversely affecting coastal ecosystems has become serious.
Against this background, the Ballast Water Management Convention was adopted at the international conference of the IMO (International Maritime Organization), and since 2009, ballast water treatment has become mandatory.
The discharge standard of ballast water established by IMO is that the number of organisms (mainly zooplankton) of 50 μm or more contained in ballast water is less than 10 in 1 m ³ , and organisms (mainly phytoplankton) of 10 μm or more and less than 50 μm The number is less than 10 in 1 ml, the number of Vibrio cholerae is less than 1 cfu in 100 ml, the number of E. coli is less than 250 cfu in 100 ml, and the number of enterococci is less than 100 cfu in 100 ml.
Various methods are currently being researched and developed for ballast water treatment technology. Among them, the treatment method using ozone can achieve treatment at a low concentration and in a short time. Has been. By the way, ozone has a very strong oxidizing power and has bleaching, deodorizing, and sterilizing effects. For example, it is said that ozone has a power several hundred times that of activated carbon in deodorization, and it has been difficult to remove substances so far. Therefore, its application in water and air purification is increasing.
However, since ozone uses silent discharge using oxygen as a raw material, it is very expensive as an oxidant, which is one factor that hinders the widespread use of ozone as an oxidant. In addition, in ozone production using silent discharge, there is a problem that the apparatus has to be enlarged, and it is difficult to mount the apparatus as a ballast water treatment apparatus on a ship.

  The ozone-containing gas is generally produced using a low-pressure mercury lamp, a silent discharge device, or a water electrolysis device. The low-pressure mercury lamp has a simple device, but it can only produce ozone-containing gas with a low concentration of about 0.5% by mass, the generation amount is as small as about 1 g / h, and the power consumption per ozone unit is very high. Large and not practical for industrial use. The water electrolysis apparatus can obtain a high concentration of ozone-containing gas of about 20% by mass, but the generated amount is as small as about 1 kg / h and the power consumption required per ozone unit is considerably large, and a large amount of ozone is required. It is not suitable for use in cases or when economic efficiency is required. The silent discharge device can be mass-produced with a generated amount of about 30 kg / h and consumes the least amount of electricity per unit of ozone, but the ozone concentration of the resulting ozone-containing gas is about 3% by mass. And low. In these prior arts, the silent discharge device is the most preferable as the ozone generator, but improvement in both the power consumption and the ozone production cost including the oxygen production device has been desired.

  As an ozone generator that improves the disadvantages of the silent discharge device described above, oxygen is used as the raw material for ozone generation supplied to the ozone generator, and ozone is generated twice as much as when air is used as the raw material with the same power consumption. Thus, an oxygen recycle ozone generator for reducing power consumption has been proposed (see, for example, Patent Document 1). In this apparatus, liquid oxygen is used as an oxygen raw material, this liquid oxygen is introduced into an ozone generator to generate ozone, the ozone-containing gas is cooled to about −60 ° C. with a heat exchanger and a refrigerator, It is introduced into an ozone adsorption tower packed with silica gel to adsorb ozone.

Silica gel is known as an ozone adsorbent as described above, but its ozone adsorption amount is not so large and a large amount of silica gel is required to ensure a constant gas treatment amount, and the adsorption device must be large. I didn't get it.
Therefore, in the prior art, in the above apparatus, liquid oxygen is used as an oxygen raw material, and the purge gas is previously dried and then introduced into the adsorption tower, so that the ozone adsorption amount is increased using the low temperature of liquid oxygen. did.

However, the amount of ozone adsorbed on the silica gel is larger as the temperature is lower, but it is difficult to make the temperature lower than −60 ° C. even if a special refrigerator is removed. In general, in order to increase the amount of processing gas, it is necessary to use a large amount of adsorbent, and the apparatus must be increased in size, increasing the manufacturing cost and running cost of the apparatus. In particular, the apparatus disclosed in Patent Document 1 has a problem in practical use because the manufacturing cost and running cost of the apparatus are extremely high.
In order to solve the drawbacks of the oxygen recycling ozone generator using silica gel described above, a specific high silica ozone having a SiO ₂ / Al ₂ O ₃ molar ratio of 20 or more, which has excellent ozone adsorption capacity even in a system in which moisture exists There has been proposed a method and apparatus for producing a high-concentration ozone-containing gas capable of efficiently concentrating ozone by using an adsorbent and applying the adsorbent to a PSA apparatus (see, for example, Patent Document 2).
JP-A-53-64690 JP-A-11-292514

  The use of ozone for sterilization of marine organisms in ballast water is a very effective sterilization method because sterilization can be achieved in a low concentration and in a short time. However, in the ozone production method, even in the production of ozone by silent discharge using the most efficient oxygen as a raw material, only about 3% of oxygen is converted into ozone by the volume ratio of supplied oxygen, and the remaining 97% of oxygen is It is very inefficient, flowing down with ozone.

The present inventors have intensively studied to solve the above-mentioned problems. As a high silica zeolite adsorbent having a high SiO ₂ / Al ₂ O ₃ molar ratio, (1) pentasil-type zeolite and (2) acid treatment were performed. It has been found that at least one selected from pentasil-type zeolite, (3) mesoporous silica, and (4) acid-treated mesoporous silica can provide an excellent ozone adsorption ability and has a low ozone decomposition rate. Therefore, it has been found that ozone can be produced with a minimum amount of raw material oxygen by using such an ozone adsorbent as an ozone adsorbent in PSA.
Specifically, as an ozone adsorbent, an adsorbent that has a better ozone adsorbing ability than the prior art is used, and oxygen is recovered from ozone and oxygen binary gas and reused as an ozone raw material. Using dry air as purge gas and desorbing and recovering as ozone and air two-component gas, ozone and air two-component gas production method is used to produce low-cost ozone, which is dissolved in ballast water and ocean By disinfecting organisms, an inexpensive and compact marine organism disinfection method is provided. The present invention has been completed based on these findings.

Thus, according to the present invention, the following inventions 1 and 2 are provided.
1. Ozone produced by an ozone production device that uses oxygen as a raw material, and a gas containing two components of oxygen are introduced into an adsorption tower containing an ozone adsorbent bed, ozone is adsorbed by the adsorbent, and the flowing oxygen is recovered. When it is reused as an oxygen raw material and ozone adsorption is completed, the introduction of ozone-containing gas is stopped, and dry air is introduced as purge gas from the back of the tower to the adsorbent bed at a reduced atmospheric pressure or pressure according to the first formula, A method for producing ozone gas that is desorbed and recovered as ozone and air two-component gas, wherein the ozone adsorbent includes (1) pentasil-type zeolite, (2) mesoporous silica, (3) acid-treated pentasil-type zeolite, ( 4) Ballast characterized by using ozone and air binary gas produced using at least one selected from acid-treated mesoporous silica. Water treatment equipment.
Gp = k ・ G ₀・ Pd / Pa (Formula 1)
Gp: amount of dry air used as purge gas (m ³ N / h), k: countercurrent purge rate k> 1.2,
G ₀ : Inlet gas amount (m ³ N / h), Pd: Regeneration pressure (kPa), Pa: Adsorption pressure (kPa)
2. There are two or more adsorption towers containing the adsorbent bed in parallel, ozone is produced by introducing ozone and oxygen two-component gas into one adsorption tower and adsorbing ozone to the adsorbent to collect the flowing oxygen. While in the adsorption process to be reused as equipment raw material, dry air is supplied to the countercurrent as a purge gas under the atmospheric pressure or reduced pressure conditions from the back of another adsorption tower that has completed the adsorption process, and ozone is desorbed from the adsorbent bed. The ozone and the desorption step of recovering ozone gas as two components of air, and then introducing the ozone-containing gas from the adsorption tower that has completed the adsorption step to the adsorption column that has completed the desorption step, and repeating the above steps. Production of ozone and air two-component gas, and as the ozone adsorbent, (1) pentasil-type zeolite, (2) acid-treated pentasil-type zeolite, (3) mesoporous silica, (4 Ozone using at least one selected from acid-treated mesoporous silica, ballast water treatment system, characterized in that air is used two-component gas.

  In the method of sterilizing marine organisms in the ballast water with ozone according to the present invention, the ozone to be used has a small decomposition rate of the generated ozone, and ozone can be efficiently produced as ozone and air two-component gas with a minimum amount of raw material oxygen. it can. As a result, it is possible to inexpensively manufacture ozone, to reduce the size of an oxygen production apparatus necessary for ozone production, and to significantly reduce the production cost and running cost of the ozone production apparatus. Therefore, the present invention can provide an inexpensive and compact treatment apparatus using marine organism ozone in ballast water.

The adsorbent used in the ozone / oxygen separation unit of the present invention must adsorb ozone to a high degree and suppress ozonolysis. As such an adsorbent, the present invention provides an adsorbent selected from at least one of (1) pentasil-type zeolite, (2) acid-treated pentasil-type zeolite, (3) mesoporous silica, and (4) acid-treated mesoporous silica. Is adopted.
Such adsorbents have low ozonolysis and high ozone adsorption capacity. Therefore, when used in the PSA method, there is little ozonolysis, and a low-cost ozone-containing gas is produced by replacing ozone with high concentration or air. Found to get.
Preparation method and ozone adsorption characteristics of (1) pentasil-type zeolite, (2) acid-treated pentasil-type zeolite, (3) mesoporous silica, (4) acid-treated mesoporous silica, which are ozone adsorbents used in the present invention Is referred to the prior application (Japanese Patent Application No. 2008-144154, ozone production / storage method using an adsorbent).

  As an ozone generator (ozonizer) for generating ozone-containing gas used for ballast underwater marine organism sterilization used in the present invention, any known silent discharge method, ultraviolet lamp method, water electrolysis method, etc. can be applied. it can. Preferably, a high-pressure silent discharge device is used, and the oxygen flowing out from the adsorption process of the ozone concentration PSA device is returned to the raw material side of the silent discharge device and used as an oxygen raw material, thereby greatly reducing oxygen consumption. it can. In the regeneration process, by using dry air as the purge gas, the desorbed ozone-containing gas can be recovered as ozone and air two-component gas, reducing the burden on the desorption vacuum pump used in the ozone / oxygen separation PSA device can do. Note that the use of high-concentration oxygen gas produced by, for example, a PSA apparatus for oxygen concentration, as the oxygen source gas supplied to the silent discharge ozone generator is effective for improving the efficiency and performance of the entire apparatus.

  From the adsorption tower transferred to the desorption process of the ozone / oxygen separation PSA apparatus, ozone and air two-component gas are recovered under atmospheric pressure or reduced pressure conditions using, for example, dry air as a purge gas in a counterflow.

The conditions for the adsorption process and the desorption process are not particularly limited. The adsorption step is usually carried out at a pressure in the range of 106 to 507 kPa (1.05 to 5 atm) and a temperature in the range of -60 ° C to 25 ° C.
In addition, the desorption step is carried out in a pressure range of 4 to 760 kPa (0.04 to 1 atm), and the temperature is not particularly limited, and usually depends on the temperature of the adsorption step. Considering utilization of the recovered ozone-containing gas, the temperature of the desorption process is preferably close to room temperature.

When the adsorption process is completed, for example, the ozone concentration of the gas at the outlet of the adsorption tower opposite to the inlet of the ozone-containing gas is monitored, and when ozone breakthrough begins to be observed or the switching time, that is, the recycling time is reached. When the adsorption is completed, the introduction of the ozone-containing gas into the adsorption tower can be stopped.
The desorption process is terminated by, for example, stopping recovery of ozone and two-component gas from the adsorption tower, assuming that desorption is completed when the minimum desorbable pressure and switching time, that is, the recycle time is reached. Can do.

Hereinafter, the present invention will be described with reference to the drawings.
FIG. 1 shows the oxygen produced by the PSA oxygen production apparatus 1 as a raw material and is supplied to a silent discharge ozone generator 3 by a pipe 2 to produce ozone and oxygen two-component gas to produce two-column ozone and two air components It is a conceptual diagram of the apparatus which supplies the gas manufacture PSA apparatus 4 and manufactures ozone and two air components. Adsorption tower 5a (the left adsorption tower is numbered after the number and the right adsorption tower is numbered b) and 5b are one or more ozone selected from the group of ozone adsorbents mentioned above The adsorbent 6 is filled.

The sequence at this time is shown in Table 1.

  In FIG. 1, the adsorption process proceeds in the adsorption tower 5a by opening the switching valves 7a and 8a and closing the switching valves 9a and 10a. The adsorption tower 5b shows the state held in the desorption process, and the process can be switched from adsorption to desorption by closing the switching valves 7b and 8b and opening the switching valves 9b and 10b. The ozone-containing gas from the ozone generator 3 is pressurized to the adsorption pressure by the blower 11 and supplied to the adsorption tower 5a in the adsorption process to adsorb ozone to the ozone adsorbent. The oxygen gas flowing out from the adsorption tower 5a is pipe 12 Is recirculated to the inlet of the ozone generator 3 to reduce the supply amount of the raw material oxygen, thereby reducing the power consumption of the ozone generator 3.

On the other hand, the ozone recovery system is held at a desorption pressure, and ozone is recovered from the adsorption tower 5b in the desorption process by desorption under reduced pressure by opening the switching valve 9b connected to the vacuum pump 13. Here, dry air 14 is used as a purge gas, the pressure is reduced to the desorption pressure by the pressure reducing valve 16 provided in the purge gas supply conduit 15, and the desorption is accelerated by supplying it to the adsorption tower 5 b in the desorption process and performing a countercurrent purge. Is done. If a large amount of purge gas is used, the ozone concentration decreases accordingly. A preferred purge rate is in the range of 1-2, and a more preferred purge rate is in the range of 1.2-1.5.
Here, the use amount Gp of the purge gas is expressed by the first equation.
Gp = k ・ G ₀・ Pd / Pa (Formula 1)
Gp: amount of dry air used as purge gas (m ³ N / h), k: countercurrent purge rate k> 1.2,
G ₀ : Inlet gas amount (m ³ N / h), Pd: Regeneration pressure (kPa), Pa: Adsorption pressure (kPa)
In FIG. 1, the PSA device 1 for oxygen concentration is attached to the front stage of the silent discharge ozone generator 3. This oxygen concentration PSA device 1 is effective in improving the efficiency and performance of the entire device.

In connection with the ozone / air two-component gas production PSA device 4, the oxygen flowing out from the adsorption tower 5 a in the adsorption process is returned to the oxygen raw material supply conduit of the silent discharge ozone generator 3 via the conduit 11. Can be used effectively. In addition, the use of a high-pressure silent discharge ozone generator can reduce the burden on the compressor for supplying ozone-containing gas to the PSA device, which is effective in improving the overall efficiency and performance of the device. It is.
The adsorbent of the present invention can be used by molding it into an arbitrary shape such as a granular shape, a pellet shape, a Raschig ring shape, or a honeycomb shape, either alone or in the form of a mixture depending on the purpose of use.

  The marine organisms supplied from the outlet of the vacuum pump 13 to the ballast water sterilization tank 23 from the seawater storage tank 20 through the seawater pump 21 to the ballast water sterilization tank 23 are obtained from the obtained ozone / air two-component gas through the outlet 17 of the vacuum pump 13. The seawater is supplied as ozone-containing microbubbles 19 to sterilize marine organisms in the seawater and supply them from the conduit 24 to the ballast tank.

The present invention will be described more specifically with reference to the following examples.
For the preparation of (1) pentasil-type zeolite, (2) acid-treated pentasil-type zeolite, (3) mesoporous silica, and (4) acid-treated mesoporous silica used in the present invention, a prior application (Japanese Patent Application No. 2008- 144,154. Production and storage method of ozone using adsorbent).

Example 1
For the sterilizing effect and oxygen for ozone generation when sterilizing marine organisms in the ballast water supplied at 3,000 ton / h using ozone and air binary gas produced by the ozone / oxygen separation unit of FIG. PSA-oxygen capacity and power consumption of each unit were evaluated. As a reference, PSA-oxygen capacity for oxygen for ozone generation when using conventional ozone and oxygen binary gas directly without using ozone / oxygen separation unit, and power consumption comparison of each unit were also performed. .
Table 2 shows (1) ozone generator capacity, (2) ozone generator capacity, (3) dry air consumption, and (4) ballast water ozone when the ozone concentration of ballast water is changed from 0.5 to 15 ppm. Concentration, (5) PSA-O ₂ power consumption, (6) PSA-O ₃ / O ₂ power consumption, (7) PSA-O ₂ power consumption, (8) Ozone generator power consumption, (9) Total power consumption (10) Evaluation of bactericidal effect.
As shown in Table 2, the marine organism sterilization effect by ozone is effective at an ozone concentration of 5 ppm or more. Next, when the PSA-ozone / oxygen separation unit is used, the conventional example (R-1 to R-5) not using the PSA-ozone / oxygen separation unit of the example and the example using the present invention (S- 1 to S-5), the PSA-oxygen capacity in the embodiment of the present invention is reduced to 1/20 of the conventional oxygen capacity, so that the power consumption for ozone production is reduced from 47 kW of the conventional method. It will be reduced to 21 kW.

  A ozone generator widely used as a powerful oxidizer and disinfectant, ozone and oxygen two-component gas supplied from a silent discharge ozone generator, using ozone adsorbent under relative high pressure conditions Ozone / oxygen separation is performed, and the recovered oxygen is reused as a raw material for the ozone generator. The adsorbed ozone is obtained by desorbing and collecting dry air as a purge gas using ozone and a two-component gas under relatively low pressure conditions. An economical and compact ballast water treatment apparatus can be provided by using this low-cost ozone and two-component gas of air for sterilizing marine organisms in ballast water.

1 shows a first embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 PSA oxygen production apparatus 2, 12, 15, 17, 22, 24 Flow path, piping 3 Silent discharge ozone generator 4 Ozone and air 2 component gas production PSA apparatus 5a, 5b Ozone adsorption tower 6 Ozone adsorption agent 7a, 7b. 8a, 8b, 9a, 9b, 10a, 10b Automatic valve 11 Blower 13 Vacuum pump 14 Dry air source 16 Pressure reducing valve 18 Ozone diffuser pipe 19 Microbubble 20 Seawater storage tank 21 Seawater pump 23 Ballast water sterilization tank

Claims (2)

Ozone produced by an ozone production device that uses oxygen as a raw material, and a gas containing two components of oxygen are introduced into an adsorption tower containing an ozone adsorbent bed, ozone is adsorbed by the adsorbent, and the flowing oxygen is recovered. When it is reused as an oxygen raw material and ozone adsorption is completed, the introduction of ozone-containing gas is stopped, and dry air is introduced as purge gas from the back of the tower to the adsorbent bed at a reduced atmospheric pressure or pressure according to the first formula, A method for producing ozone gas that is desorbed and recovered as ozone and air two-component gas, wherein the ozone adsorbent includes (1) pentasil-type zeolite, (2) mesoporous silica, (3) acid-treated pentasil-type zeolite, ( 4) Ballast characterized by using ozone and air binary gas produced using at least one selected from acid-treated mesoporous silica. Water treatment equipment.
Gp = k ・ G ₀・ Pd / Pa (Formula 1)
Gp: amount of dry air used as purge gas (m ³ N / h), k: countercurrent purge rate k> 1.2,
G ₀ : Inlet gas amount (m ³ N / h), Pd: Regeneration pressure (kPa), Pa: Adsorption pressure (kPa)   There are two or more adsorption towers containing the adsorbent bed in parallel, ozone and oxygen two-component gas are introduced into one adsorption tower, the adsorbent adsorbs ozone, and the flowing oxygen is recovered to generate ozone. While in the adsorption process that is reused as a raw material for manufacturing equipment, dry air is supplied to the countercurrent as a purge gas under the atmospheric pressure or reduced pressure from the back of another adsorption tower that has completed the adsorption process, and ozone is supplied from the adsorbent bed. A desorption process is performed to desorb ozone gas as two components of ozone and air, and then the introduction of the ozone-containing gas is switched from the adsorption tower that has completed the adsorption process to the adsorption tower that has completed the desorption process, and the above process is repeated. , Ozone and air two-component gas, wherein as the ozone adsorbent, (1) pentasil-type zeolite, (2) acid-treated pentasil-type zeolite, (3) mesoporous silica, ( ) Ozone to use at least one selected from acid-treated mesoporous silica, ballast water treatment system, characterized in that air is used two-component gas.

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