JP2000053404A - Apparatus and method for ozone condensation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ozone condensing apparatus which is capable of reducing ozone loss in the case where the cooling capability of a refrigerator is lost by a blackout, fault, or the like, and may be rapidly restarted after resetting, and a method therefor. SOLUTION: This apparatus for condensing the ozone by successively changing over an adsorption stage for adsorbing the ozone by cooling an adsorbent and a desorption stage for desorbing the ozone by heating the adsorbent is provided with a main cooling system for cooling the adsorbent by the refrigerant from the refrigerator 13 and an auxiliary cooling system for cooling the adsorbent by a low-temp. liquefied gas supplied from a low-temp. liquefied gas supplying means 22 or a low-temp. gas formed by vaporizing the low-temp. liquefied gas or the auxiliary refrigerant cooled by the low-temp. liquefied gas or the low-temp. gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for concentrating ozone.
The present invention relates to an ozone concentrating apparatus and method for supplying high-concentration ozone at a stable concentration to equipment using relatively high-concentration ozone.

[0002]

2. Description of the Related Art When supplying ozone to equipment utilizing relatively high concentration of ozone, such as pulp bleaching or water treatment, the concentration generated by an ozone generator is about 6 to 7% by mass, at most about 10% by mass. Ozone is supplied after being concentrated to about 20% by mass.

[0003] As a means for concentrating ozone, there is known a temperature fluctuation type adsorption separation (TSA) method utilizing a property that ozone is adsorbed to an adsorbent such as silica gel at a low temperature. The concentration of ozone by the TSA method is usually performed using a plurality of adsorption columns filled with an adsorbent such as silica gel that preferentially adsorbs ozone. An ozone-containing gas supplied from an ozone generator is introduced into the cooled adsorption column to adsorb ozone to the adsorbent, and the adsorbent in the adsorption column after the adsorption step is heated to desorb ozone. A desorption step of introducing a scavenging gas into the adsorption column to introduce desorbed ozone together with the scavenging gas, and a cooling step of cooling the adsorbent of the adsorption column after the desorption step to the adsorption step temperature. , Are sequentially switched.

[0004]

Generally, in an ozone concentrator for concentrating ozone by the TSA method as described above,
As a cold heat source for cooling the adsorbent, a refrigerator having a low cooling cost is used. However, if a refrigerator is used and the cooling of the adsorbent becomes difficult due to a power outage or breakdown of the refrigerator, the adsorbent that has absorbed ozone will not be able to retain ozone. Or ozone loss occurs due to excess ozone. In addition, since the temperature of the adsorbent rises, the adsorbent must first be cooled to a predetermined temperature at the time of recovery, and there is a problem that it takes time to restart.

Accordingly, the present invention provides an ozone concentrator based on the TSA method using a refrigerator as a main cold heat source, which can reduce ozone loss when the cooling capacity of the refrigerator is lost due to a power outage or failure, and can restore the ozone. It is an object of the present invention to provide an ozone concentrating apparatus and method that can be restarted later in a short time.

[0006]

In order to achieve the above object, an ozone concentrating apparatus of the present invention comprises an adsorbing step of adsorbing ozone by cooling an adsorbent, and desorbing ozone by heating the adsorbent. A main cooling system for cooling the adsorbent with a low-temperature refrigerant obtained from a refrigerator, a low-temperature liquefied gas supplied from a low-temperature liquefied gas supply unit, or the low-temperature liquefied gas; A sub-cooling system for cooling the adsorbent with a low-temperature gas obtained by vaporizing a gas or an auxiliary refrigerant cooled by the low-temperature liquefied gas or the low-temperature gas is provided.

Further, the ozone concentrating device of the present invention is provided with cooling system switching means for switching the cooling of the adsorbent to be performed by the sub-cooling system when the cooling capacity of the main cooling system decreases. The switching means includes an emergency power supply that operates in the event of a power failure. Further, the sub-cooling system supplies the low-temperature liquefied gas supplied from the low-temperature liquefied gas supply unit to the adsorbent cooling unit, and supplies the low-temperature gas or auxiliary refrigerant to the adsorbent cooling unit. A low-temperature gas supply path, and an inlet temperature detecting means for detecting a temperature of an inlet of the adsorbent cooling unit; and an outlet for detecting a temperature of an outlet of the adsorbent cooling unit. Low-temperature liquefied gas supply amount control means for controlling the supply amount of low-temperature liquefied gas from the low-temperature liquefied gas supply path so that the temperature detected by the inlet-portion temperature detection means does not fall below a predetermined temperature. A low-temperature gas supply amount control means for controlling the supply amount of the low-temperature gas or the auxiliary refrigerant from the low-temperature gas supply path so that the temperature detected by the outlet temperature detection means does not exceed a predetermined temperature. It is characterized in that it comprises and.

The method for concentrating ozone according to the present invention is a method for concentrating ozone by sequentially switching between an adsorption step of cooling the adsorbent to adsorb ozone and a desorption step of heating the adsorbent to desorb ozone. When the cooling of the adsorbent during normal operation is performed by the refrigerant obtained from the refrigerator, and when the cooling operation by the refrigerator becomes difficult due to a power failure or the like,
The adsorbent is cooled and held at a predetermined temperature by a low-temperature liquefied gas, a low-temperature gas obtained by evaporating the low-temperature liquefied gas, or an auxiliary refrigerant cooled by the low-temperature liquefied gas or the low-temperature gas.

[0009]

FIG. 1 is a system diagram showing an embodiment of an ozone concentrating device according to the present invention. This ozone concentrator has three adsorption cylinders A filled with an adsorbent such as silica gel,
B and C, an ozone generator 11 for generating ozone by high-voltage silent discharge using oxygen gas as an ozone source gas, and an ozone concentration stabilizer 12 provided for further stabilizing the concentration of the concentrated ozone to be supplied. The refrigerator includes a refrigerator 13 forming a main cooling system, a liquefied oxygen storage tank 14 and an evaporator 14a which are a means for supplying oxygen gas serving as an ozone raw material and also a means for supplying a low-temperature liquefied gas in a sub-cooling system.

Each of the adsorption tubes A, B, and C is provided with a main cooling coil 15 through which a refrigerant supplied from the refrigerator 13 flows, and a liquefied oxygen supplied from the liquefied oxygen storage tank 14 or a low-temperature liquid vaporized by the evaporator 14a. It is housed in a cool jacket 18 having a sub-cooling coil 16 through which oxygen gas flows and a heater 17 for heating. The ozone concentration stabilizer 12 is also housed in a cool jacket 21 having a main cooling coil 19 and a sub cooling coil 20 similar to the above.

Incidentally, the main cooling coil 1 of the adsorption cylinders B and C portions
5 and the sub-cooling coil 16 and the main cooling coil 19 and the sub-cooling coil 20 of the ozone concentration stabilizer 12 are also provided with the same piping path as the main cooling coil 15 and the sub-cooling coil 16 of the adsorption column A. However, illustration of these is omitted.
The sub-cooling coil 16 of the adsorption column A will be described below, but the other adsorption columns B and C and the ozone concentration stabilizer 12 will be described.
The sub cooling coils 16 and 20 of a part are formed similarly.

The sub-cooling coil 16 serving as an adsorbent cooling unit
The low temperature liquefied gas supply path 22 connected to the liquefied oxygen storage tank 14 via a valve 22V is provided at the inlet of the evaporator 14a.
Is provided with a low-temperature gas supply path 23 connected to the secondary side via a valve 23V. An outlet path 24 having a valve 24V is provided at the outlet of the sub-cooling coil 16.

Further, at the inlet of the sub-cooling coil 16,
An inlet temperature detecting means (temperature indicating controller (TIC)) 25 for detecting the temperature of the inlet and controlling a flow control valve 25V provided in the low-temperature liquefied gas supply passage 22 is provided.
At the outlet of the sub-cooling coil 16, the temperature of the outlet is detected and the flow control valve 2 provided in the low-temperature gas supply path 23 is provided.
An outlet temperature detecting means (temperature indicating controller (TIC)) 26 for controlling 6 V is provided.

Next, the outline of the ozone concentration operation at the time of steady operation will be described. In the first stage, it is assumed that the adsorption cylinder A is in the adsorption step, the adsorption cylinder B is in the desorption step, and the adsorption cylinder C is in the cooling step. At this time, the adsorption cylinder A in the adsorption process
The adsorbent such as silica gel filled therein is cooled to a predetermined temperature, for example, −80 ° C. by a refrigerant supplied from the refrigerator 13 to the main cooling coil 15 via the paths 13 a and 13 b. The oxygen gas containing ozone having a concentration of 6 to 7% by mass generated by the ozone generator 11 is introduced into the adsorption column A via the path 31 and the valve 31V, and the ozone is adsorbed by the adsorbent to be separated from oxygen, and is adsorbed. The unreacted oxygen gas is led out to the valve 32V and the path 32, returned to the inlet of the ozone generator 11 from the path 34 by the fan 33, and used again as an ozone raw material.

In the adsorption cylinder B in the desorption step, the heater 1
7, the adsorbent is heated to about −20 ° C., and a predetermined amount of scavenging gas is introduced through the passage 35 of the scavenging gas supply system and the valve 35V. Ozone desorbed from the adsorbent is converted into scavenging gas. After being led out from the valve 36V to the path 36, it is introduced into the ozone concentration stabilizer 12. Further, the adsorption cylinder C in the cooling step is being cooled to the operating temperature of the adsorption step by the refrigerant supplied from the refrigerator 13 to the main cooling coil 15.

After a lapse of a predetermined time, the valves before and after the adsorption cylinder open and close in a predetermined sequence, so that the adsorption cylinder A shifts from the adsorption step to the desorption step, the adsorption cylinder B shifts from the desorption step to the cooling step, C is switched from the cooling step to the adsorption step. In the following, concentrated ozone is continuously discharged from any of the adsorption cylinders in the desorption step by sequentially switching and repeating each adsorption cylinder in the order of the adsorption step, the desorption step, and the cooling step.

In the ozone concentration stabilizer 12 in which the adsorbent (eg, silica gel) filled therein is cooled to a predetermined temperature by the refrigerant supplied to the main cooling coil 19,
The ozone concentration in the ozone-containing gas derived from the adsorption column during the desorption process is leveled and supplied to the destination through the path 37 and the valve 37V.

In the apparatus for concentrating ozone by the TSA method as described above, when the refrigerator 13 of the main cooling system is stopped or its capacity is reduced due to a power failure or failure,
An abnormality of the refrigerator 13 is detected, and the adsorbent is cooled by liquefied oxygen or oxygen gas supplied to the sub-cooling coil 16 of the sub-cooling system.

The detection of an abnormality such as a stop or a failure of the refrigerator 13 can be performed by a usual method such as monitoring the power supply voltage, monitoring the pressure and temperature of the refrigerant, and the like. When an abnormality of the refrigerator 13 is detected, the cooling system switching means incorporated in the operation panel or the like operates to stop the generation of ozone in the ozone generator 11 and shut off the valves in each path through which ozone flows. At the same time, the valve 22V of the low-temperature liquefied gas supply path 22
The valve 23V of the low-temperature gas supply path 23 and the valve 24V of the outlet path 24 are opened. At the same time, the inlet temperature detecting means 25 and the outlet temperature detecting means 26 operate to operate the flow control valve 25.
Adjust the opening of V and 26V.

The inlet temperature detecting means 25 measures the temperature of the inlet of the sub-cooling coil 16 and
The flow control valve 25V is controlled so that the supply amount of liquefied oxygen is adjusted so that the cooling temperature of the adsorbent due to the above does not become lower than the liquefaction temperature of ozone. On the other hand, the outlet temperature detecting means 26 controls the temperature of the sub-cooling coil 16 so that
By controlling the flow control valve 26V, the supply amount of oxygen gas is adjusted.

As a result, liquefied oxygen from the low-temperature liquefied gas supply path 22 and the evaporator 14a
And the oxygen gas from the low-temperature gas supply path 23 evaporated in
Each will be supplied at the optimal flow rate. That is, the inlet temperature detecting means 25 and the outlet temperature detecting means 2
By adjusting the flow rates of the liquefied oxygen and the oxygen gas by the use of 6, the entire sub-cooling coil 16 can be maintained in an optimum temperature range.

Therefore, the adsorbent filled in each of the adsorption cylinders A, B, C and the ozone concentration stabilizer 12 can be cooled to a predetermined temperature, and the ozone adsorbed on the adsorbent is desorbed. Can be prevented. In addition, by providing an emergency power supply that operates in the event of a power failure in the cooling system switching means, even if operation from the operation panel or the like becomes impossible due to a power failure, switching to the sub-cooling system can be reliably performed. it can.

As described above, the refrigeration system 1 is
Even if 3 stops or the cooling capacity decreases,
Since ozone can be held in a state of being adsorbed by the adsorbent, unnecessary ozone is not supplied to the equipment used, and ozone loss does not occur. At this time, the amount of liquefied oxygen consumed is only the amount corresponding to the amount of heat entering the adsorption column or the like, so that a very small amount is sufficient. Furthermore, since the emergency power supply is only used for controlling the temperature indicating controller and the like after the first valve opening / closing operation, the power consumption is small and a small capacity power supply can be used.

When the refrigerator 13 returns to a predetermined operation state due to recovery from a power failure or the like, all of the adsorbents are cooled to a predetermined temperature. This eliminates the need to perform an operation for cooling the fuel cell to a predetermined temperature, and restarts to a steady operation in a short time.

In this embodiment, a three-cylinder TSA device is exemplified. However, the number of adsorbing cylinders is optional, and the ozone concentration stabilizer is optional. In addition, when liquefied oxygen is used as an ozone raw material supply source, the low-temperature liquefied gas used in the sub-cooling system is preferable because it can be formed only by simple piping by using this liquefied oxygen as a cold heat source. Other low-temperature liquefied gas such as liquefied nitrogen can be used depending on environmental conditions and the like. Further, depending on the size of the adsorption cylinder, the temperature of the low-temperature liquefied gas, etc., only the low-temperature liquefied gas can be used, and only the low-temperature gas obtained by evaporating the low-temperature liquefied gas with the evaporator can be used. . Further, the auxiliary refrigerant cooled to an appropriate temperature by exchanging heat between the low-temperature liquefied gas or the low-temperature gas and another appropriate refrigerant (auxiliary refrigerant) by a heat exchanger or the like can be used in the sub-cooling system. In addition, as an auxiliary refrigerant, in addition to various refrigerants,
Oxygen gas, nitrogen gas, or the like can be used.

[0026]

As described above, according to the present invention,
Even when an abnormality occurs in the refrigerator of the main cooling system, the adsorbent can be cooled to a predetermined temperature by the low-temperature liquefied gas or the low-temperature gas supplied from the sub-cooling system.
Ozone is hardly lost, and the apparatus can be restarted in a short time.

[Brief description of the drawings]

FIG. 1 is a system diagram showing one embodiment of an ozone concentrating device of the present invention.

[Explanation of symbols]

A, B, C: adsorption cylinder, 11: ozone generator, 12: ozone concentration stabilizer, 13: refrigerator, 14: liquefied oxygen storage tank, 1
5: Main cooling coil, 16: Sub cooling coil, 17: Heating heater, 18: Cooling jacket, 19: Main cooling coil, 20: Sub cooling coil, 21: Cooling jacket, 22
... Low-temperature liquefied gas supply path, 23 ... Low-temperature gas supply path, 2
4 outlet path, 25 inlet temperature detecting means, 26 outlet temperature detecting means

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Jun Furuya 3-4-2, Marunouchi, Chiyoda-ku, Tokyo F-term in Mitsubishi Paper Mills Co., Ltd. 4D012 CA13 CB16 CD05 CE01 CE02 CF02 CF04 CH05 CJ05 CK04 4G042 CA05 CB15 CB16 CB19 CB23 CC23

Claims (6)

[Claims] 1. An apparatus for concentrating ozone by sequentially switching between an adsorption step of cooling the adsorbent to adsorb ozone and a desorption step of heating the adsorbent to desorb ozone. A main cooling system for cooling the adsorbent with a refrigerant, a low-temperature liquefied gas supplied from a low-temperature liquefied gas supply unit, or a low-temperature gas obtained by vaporizing the low-temperature liquefied gas, or an auxiliary cooled by the low-temperature liquefied gas or the low-temperature gas An ozone concentrating device, comprising: a sub-cooling system for cooling the adsorbent with a refrigerant. 2. A cooling system switching means for switching the cooling of the adsorbent to be performed by the sub cooling system when the cooling capacity of the main cooling system is reduced. Ozone concentrator. 3. The ozone concentrator according to claim 2, wherein said switching means includes an emergency power supply that operates when a power failure occurs. 4. The low-temperature liquefied gas supply path for supplying the low-temperature liquefied gas supplied from the low-temperature liquefied gas supply means to an adsorbent cooling section, and the low-temperature gas or auxiliary refrigerant is supplied to the adsorbent cooling section. 2. The ozone concentrating device according to claim 1, further comprising a low-temperature gas supply path for supplying the ozone to the apparatus. 5. The sub-cooling system according to claim 1, wherein the sub-cooling system includes an inlet temperature detecting unit for detecting a temperature of an inlet of the adsorbent cooling unit, and an outlet temperature detecting unit for detecting a temperature of an outlet of the adsorbent cooling unit. A low-temperature liquefied gas supply amount control means for controlling a supply amount of the low-temperature liquefied gas from the low-temperature liquefied gas supply path so that the temperature detected by the inlet-portion temperature detection means does not become lower than or equal to a predetermined temperature; Low-temperature gas supply amount control means for controlling the supply amount of the low-temperature gas or the auxiliary refrigerant from the low-temperature gas supply path so that the temperature detected by the temperature detection means does not exceed a predetermined temperature. Item 5. An apparatus for concentrating ozone according to Item 4. 6. A method of concentrating ozone by sequentially switching between an adsorption step of cooling the adsorbent to adsorb ozone and a desorption step of heating the adsorbent to desorb ozone, wherein the adsorption during normal operation is performed. The cooling of the agent is performed by a refrigerant obtained from a refrigerator, and when the cooling operation by the refrigerator becomes difficult due to a power failure or the like, a low-temperature liquefied gas, a low-temperature gas obtained by vaporizing the low-temperature liquefied gas, or the low-temperature liquefaction A method for concentrating ozone, wherein the adsorbent is cooled and maintained at a predetermined temperature by an auxiliary refrigerant cooled by gas or low-temperature gas.