JPS5934122B2 - Ozone production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing ozone by silent discharge, in which air is separated into oxygen and nitrogen by an adsorption method, ozone is generated by the obtained oxygen, and the gas pressure required for adsorption separation is reduced. Adsorption and ozone generation operations are performed at low temperatures using the resulting cold temperature, making it possible to produce inexpensive ozone.

Ozone has an extremely wide range of uses as an oxidizing agent for pollution prevention and chemical industry applications, but its drawback is that it is generally impractical on an industrial scale due to its high original cost.

For example, ozone is usually generated by using air as a raw material and producing it by silent discharge, but the energy efficiency of the silent discharge method is low, at about 50 gO3/kwhr, which is about 4.5 gO3/kwhr, which is about 4.5 gO3/kwhr compared to the theoretical value. It's only the 5th section.

If this is made from oxygen, it will be approximately 100 gO3/kwh.
There are advantages such as the amount of ozone generated is approximately twice that of air, and the scale of the equipment is relatively small.
The efficiency is low even though it uses oxygen, which is a valuable substance, and it is difficult to put it into practical use unless cheap oxygen is supplied and ozone generation efficiency is improved.

In the present invention, air is separated into oxygen and nitrogen by an adsorption method and the obtained oxygen is used as a raw material gas for ozone. However, by performing the adsorption operation at a low temperature, the adsorption separation effect is improved. The purpose of this invention is to increase the efficiency of ozone generation by lowering the temperature of oxygen and sending it to the ozonizer.

In general, adsorption efficiency is improved by operating at low temperature in adsorption separation, not just for air, and in ozonizers, ozone decomposes at room temperature due to heat generated by discharge, so operating at low temperature is effective. is publicly known.

However, in order to operate these at low temperatures, a cooling source is required, and if a refrigerator or the like is used for this purpose, the power cost increases, and the above-mentioned effects are canceled out and it is meaningless.

It has also been proposed to utilize the cooling power of LNG.
For safety reasons, it is necessary to use a refrigerant such as an inert gas, which not only complicates the device, but also leaves problems such as limited usage conditions.

For this reason, the present invention adiabatically expands adsorbed and separated pressurized oxygen and pressurized nitrogen to make them into low-temperature gases, and sends the low-temperature oxygen to an ozonizer to generate ozone at low temperatures. In addition, the low-temperature nitrogen cools the feed air to remove easily condensable components and serves as a cold source for low-temperature adsorption, and also recovers power by obtaining mechanical energy through the adiabatic expansion.

An example of the embodiment will be explained below using figures.

Raw air is sucked into a compressor 2 through a pipe 1, and after being pressurized, the heat of compression is removed by a water cooler 3, and then introduced into a regenerative heat exchanger 6 such as a regenerator through a pipe 4 and a valve 5. .

A plurality of regenerators 6 are provided and are used by switching at regular intervals, and when raw air is flowing in one, the other is in the regenerative cooling period.

G) If the regenerator 6a is used and the regenerator 6b is in the regenerative cooling period, raw air is introduced into the regenerator 6a through the valve 5a, and as it flows through the regenerator 6a, the regenerator cooled in the previous cycle is used. It exchanges heat with the material to lower the temperature, and condenses and removes easily condensable components such as moisture and carbon dioxide.

(In the following description, valves and devices with the same numbers are assumed to be used alternately, and when one is open or in use, the other is closed or not in use.

) The raw material air, which has become low temperature and purified in the regenerator 6a, passes through the valve 7a, the pipe 8, and the valve 9, and is led to the adsorber 10, which is composed of a plurality of units and is used selectively.

The adsorbent 10 is filled with an adsorbent that selectively adsorbs nitrogen, and is used by switching at regular intervals so that when one adsorbent is in the adsorption period, the other is in the regeneration period.

Assuming that the adsorber 10a is currently in the adsorption period and the adsorber 10b is in the regeneration period, the feed air from the pipe 8 is introduced into the adsorber 10a through the valve 9a, and nitrogen is selectively removed as it flows through the device 10a. is adsorbed and removed.

As a result, oxygen is led out from the valve 11a as a non-adsorbed component gas, but this oxygen is introduced into the expansion turbine 13 through the pipe 12 and is adiabatically expanded to a pressure close to atmospheric pressure to become low-temperature oxygen.

At this time, mechanical energy is obtained by driving the expansion turbine, and power is recovered by driving the generator 14.

The low-temperature oxygen gas that has exited the expansion turbine 13 branches off into oxygen gas that will be used as a scavenging gas for regenerating the adsorber 10, which will be described later, and reaches the ozonizer 16 via a pipe 15.

In the ozonizer 16, ozone is generated by silent discharge at low temperatures, and the ozone-containing oxygen gas is turned into the tube 1.
Supplied from 7.

Next, explaining the adsorber 10b and regenerator 6b in the regeneration period, the nitrogen adsorbed in the adsorber 10b in the previous cycle is extracted by opening the valve 18b.
This is sent to the nitrogen expansion turbine 19 and adiabatically expanded.

As a result, as in the case of oxygen, power is recovered and low temperature nitrogen gas is obtained, which is introduced into the regenerator 6b in the regeneration period via the pipe 20 and valve 21b.

The low-temperature nitrogen gas introduced into the regenerator 6b cools the regenerator material as it flows through the regenerator 6b, and also carries with it water and carbon dioxide, which were condensed and removed by the raw material air in the previous cycle, and passes through the valve 22b1. It is led out of the system through the pipe 23.

This depressurization operation is carried out until the inside of the adsorber 10b reaches almost atmospheric pressure.
A portion of the low-temperature oxygen introduced into the expansion turbine 13 and expanded is scavenged.

That is, a part of the low-temperature oxygen gas exiting the expansion turbine 13 is branched from the valve 24b and flows back into the adsorber 10b, scavenging the inside of the adsorber 10b by entraining the remaining adsorbed nitrogen.
At the same time as cleaning, the adsorbent is cooled, and this gas is discharged from the pipe 23 through the valve 18b1, the expander 19, the pipe 20, the valve 21b and the regenerator 6b, like the vacuum nitrogen.

The regenerator 6 and the adsorber 10 perform the above operations in one cycle, and are switched at regular intervals.

The method of the present invention is carried out as described above, but if oxygen with a concentration of 80% is to be obtained with a yield of 50%, the raw material air/N711/
hr, the amount of gas introduced into the expansion turbine 13 is 0.
262 Nm/hr, and the amount of gas flowing into the ozonizer 16 is 0.131 Nm/hr % expansion turbine 1
The amount of gas expanded in step 9 is 0.738Nm3/hr
, the amount of gas released from the pipe 23 is 0.869Nm3/h
It is r.

Now, if the adsorber 10 is operated at -70°C, the feed air pressure is 6 ata, the expansion turbine outlet pressure is 1.2 ata, and the ozonizer is operated at these pressures, the inlet state of the expansion turbine 13 is the gas pressure ( P)=6ata, temperature (Tl--70℃, enthalpy (()-101,4
kc,n/Nm3.

When this is expanded at an expansion turbine efficiency of 80%, the outlet state is P-1,2ata, T--118°C, H=87.
1kca#/Nm3, so the energy released by the turbine 13 is (101,4-87,1)Xo,2
62-3.75 kcal/Nm3-Air" h
It is r.

In addition, the inlet state of the expansion bottle 19 is immediately after switching (adsorber 1
Immediately after depressurization at 0b), P = 6 ata, T = -70°C
, H-101, 4kcal! /Nm3, the exit state is P
= 1.2 ata.

T--118℃, H=87.1 kcal/N772
” However, the pressure inside the adsorber gradually decreases due to depressurization,
Eventually, both the entrance and exit will be in the same state.

Therefore, the energy released by the expansion turbine 19 is (1
01,4-s 7.1)X O,869xK= 6.2
1 kca#/Nm3・Air-hr, and when combined with the release energy of the expansion turbine 13, it is 9.96 kc
al/Nm3・Air r-hr, which is 0,01
15 KW/Nrrl/hr.

On the other hand, if the ozonization rate when oxygen with a concentration of 80 parts is supplied to the ozonizer is 4 parts, then 0.138 Nm-03/h
rX0.04=0.00552Nm3-03/hr ozone is generated, power consumption is 0.00552N772"
03/hr10.0467Nm/KW-hr= 0
．． Since it is 118 KW, the recovered power corresponds to about 10 times the power consumption of the ozonizer.

In addition, since the oxygen supplied to the ozonizer has an expansion turbine outlet temperature of -118°C, ozonation is possible at low temperatures even considering the temperature rise due to ozonizer discharge, and the ozonization efficiency can be reduced to room temperature. It can be expected to be more than twice as large as in the case of .

Therefore, according to law, generally humid air (dew point 15 ° C)
However, it is known that dry air (dew point -60°C) can generate approximately twice the ozone generation efficiency, and that oxygen at a concentration of 80 times that of air can also approximately double the efficiency.
Combined with the improvement in ozone generation efficiency at low temperatures, this has the advantage of being extremely effective.

[Brief explanation of drawings]

The drawings are process diagrams showing one embodiment of the present invention. 6a, 6b...Regenerator, 10a, 10b...
...adsorber, 13.19...expansion turbine,
14... Generator, 16... Ozone generator (ozonizer).

Claims (1)

[Claims] 1 In an ozone production method in which air is adsorbed and separated using the pressure swing method, and the obtained oxygen is converted into ozone by silent discharge, the pressurized air is guided to a regenerative heat exchanger and cooled, and the moisture contained in it is condensed. After removing the nitrogen, it is introduced into an absorber to selectively adsorb and separate the nitrogen, and the pressurized oxygen obtained is expanded in an adiabatic expansion engine to become low-temperature oxygen, and this low-temperature oxygen is turned into ozone by silent discharge. At the same time, when the adsorber is regenerated, the adsorbed nitrogen derived from the adsorber is expanded in an adiabatic expansion engine to become low-temperature nitrogen, and then this low-temperature nitrogen is introduced into the regenerative heat exchanger, and the adsorbed nitrogen is A method for producing ozone, characterized in that the gas pressure of pressurized oxygen and adsorbed nitrogen introduced into an engine is converted into mechanical energy by driving the engine, and recovered as motive power.