JPH0373154A - Collecting method for ethylene oxide gas - Google Patents

Abstract

PURPOSE:To collect EOG used for sterilization as much as possible in a clean state and to reutilize it by accumulating and collecting treated EOG to an accumulating tank by a compressor and offering it for reuse, and also, exhausting rarefied EOG generated at the time of taking in and out to the outside of a system. CONSTITUTION:After the treatment is ended, EOG, etc., pass through valves A, H by the own pressure at first and fed to a cushion tank 2, and subsequently, pass through a valve C and accumulated in an accumulating tank 3 brought to pressure rise by driving of a compressor B-2. Next, at the time point when pressure of a sterilizing chamber 1 becomes 1.2atm, the valve H is closed and the valve B is opened, a vacuum pump B-1 operates, and the EOG passes though the valves A, B, the cushion tank 2, the valve C, and the compressor B-2 and accumulated in the accumulating tank 3. at the time when pressure of the sterilizing chamber 1 becomes 50Torr, the valves A, B and C, the vacuum pump B-1 and the compressor B-2 are stopped, the valve E is opened air flows into the sterilizing chamber 1, and the becomes 1atm. Thereafter, the valve E is closed, the vacuum pump B-1 operates, the valve A, G are opened, diluted EOG, etc., are led to the outside of a closed circuit, and at the time of the next sterilization treatment, the accumulated BOG is allowed to flow in.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for collecting EOG, and in particular, the collection of EOG discharged from sterilizers used in the field of hygiene management such as medical equipment, cosmetics, absorbent cotton, and packaging materials. Regarding the method.

[Conventional technology]

EOG is widely used as an intermediate raw material for ethylene glycol, etc., but it has oxidizing properties, and because of this sterilization effect, it is used as a fumigation disinfectant or a disinfectant in the field of sterilizing medical equipment, packaging materials, books, cultural properties, etc. ing.

EOG is toxic to the human body, including mental disorders and carcinogenicity, and a mixture of EOG and air has a wide explosive range (3
~100 qb) and is a flammable hazardous substance. For this reason, EOG is subject to regulations under the High Pressure Gas Control Law and the Industrial Safety and Health Law, but there are no particular regulations regarding air pollution prevention, and there are many cases where EOG is released into the untreated atmosphere.

However, in recent years, with increasing interest in pollution problems, incineration and wet treatment methods have become more common.

Simple water absorption is the simplest wet absorption method, but the solubility in water is chlorine gas (Henry's constant m, which is an index of solubility, is 13 at 25°C), and water absorption is reliable. I can't say it's a method.

When sulfuric acid is used as a catalyst, EOG is easily hydrolyzed to produce ethylene glycol as shown in the reaction formula below.

II, 80°CJ4aO+) I*OC*H4(OH) reaction was originally applied to the production of ethylene glycol, but E
It also exhibits excellent effects in removing OG. That is, since EOG physically dissolved in water is sequentially hydrolyzed into ethylene glycol, it exhibits an extremely high absorption rate compared to absorption of water alone.

The absorption method using this reaction was published in Japanese Patent Application Laid-Open No. 59-22215.
It was announced on 7th. In addition, the present inventors have patent application defect 63-1
7'7199, an improved EOG absorption method was proposed.

However, this absorption method ultimately disposes of valuable EOG, requires sulfuric acid and special soda for its neutralization, and eliminates the need to periodically extract and dispose of the ethylene glycol provided as a result of hydrolysis. It's not, it's a high BO
As wastewater from D is discharged, there is an expense involved in wastewater treatment.

On the other hand, the incineration method has the great advantage of 100% decomposition and removal rate compared to the wet method (-), but it requires high fuel and equipment costs, and above all, it causes a loss of resources due to the disappearance of the responsible EOG. There is a big disadvantage in this respect.

In this case, there was no way that I would be able to recover the waste even if I used to carry out detoxification treatment.

[Problem to be solved by the invention]

In view of the above-mentioned circumstances, the present invention is an improvement on these methods and aims to provide a method for recovering and reusing EOG used for sterilization in as clean a state as possible.

[Means to solve the problem]

The present invention to achieve its object consists of the following three claims. That is, my first invention connects a sterilization room, a vacuum pump, a kutsushiran tank, a compressor, and a pressure storage tank in sequence with piping to form a closed circuit that returns from the pressure storage tank to the sterilization room, and then processes the processed E.O. 3 is stored and recovered in a pressure storage tank using a compressor for reuse, and at the same time, diluted EOG that is generated when the objects to be processed are taken out and taken out of the sterilization room is discharged from the system.
Moreover, it is intended to replenish the shortage commensurate with this loss.

Furthermore, the invention of Assignment No. 2 stated in claim (2) is based on the above-mentioned EO
In the closed circuit for G recovery, a steam blowing means is installed in the sterilization room, and a dehumidifier is installed between the Cushion tank and the compressor ε to remove dead bacteria, fungal spores, dust, etc. generated during the sterilization process. This consists of discharging it out of the system together with condensed water. In addition, the third aspect of the invention described in claim (3) is that the dilute gOG-4 generated when taking in and out of the processed material in the sterilization room is guided to the absorption device by the vacuum pump to remove the gas, which is less than the recoverable limit, and then the air is removed. It consists of discharging the water.

The present invention will be specifically explained below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment combining the first and third inventions, and FIG. 2 is a diagram showing an embodiment of the second invention. 1st
As shown in the figure, the first invention includes a sterilization chamber l, a vacuum pump B-
1% Cushion Tank 2. The compressor/row 2 and the pressure accumulator tank 3 are connected by pipes 15 to 18, and a closed path returning to the sterilization room 1 via the pressure accumulator tank 3 and pipes 19 to 20 is formed. Further, the closed circuit is connected to a BOG supply source (cylinder) 7 and a discharge port described later through pipes 22 and 24, respectively, and further connected to a purge air supply for the sterilization chamber 1 via a pipe 14. It is preferable that the purge air is air that has been previously sterilized by heat or ultraviolet light.

The EOG for sterilization used in the sterilization room 1 is prepared in advance with 10 to 30 vol qb of EOG, C0 to prevent explosion.
The mixed gas has a composition of 190 to 70 vol% (hereinafter simply referred to as EOG, etc.), and has a pressure of 2 ata at the beginning of operation. After processing is completed, EOG, etc. is initially operated by υ valve A due to its own pressure.
and H are sent to the compression tank, and then passed through valve C to be pressurized by driving the compressor B-2 and stored in the pressure storage tank 3.

Next, when the pressure in the sterilization chamber 1 reaches 1.2 ata, valve H is closed and valve B is opened, vacuum pump B-1 is activated, and valves A, B, gas tank 2, and valve C1 are compressed. B-2
is accumulated in the pressure accumulation tank 3. The pressure accumulator tank is appropriately heated with hot water or the like to prevent condensation of E and OG within the pressure accumulator tank, and there is no change in the composition of gases such as EOG, thereby avoiding the risk of explosion and operating safely. Valve switching can also be performed automatically in conjunction with a pressure indicating controller (not shown). Further, in EOG and the like, dust, rust, etc. are filtered through a filter 12 installed before and/or after the pressure accumulating tank 3.

For example, this filter can filter out 99% of foreign matter larger than 0.1μ.
It is recommended to use a clean room filter that collects one or more particles.

When the pressure in sterilization chamber 1 reaches 5 Q Torr, close valves A, B, and C (all other valves D-H were closed in the previous process), and turn on vacuum pump B-1 and compressor. Machine B-2
stops, valve E opens and air flows into sterilization chamber 1.
Become ata. At this time, EOG, etc. are diluted with a large amount of air, and valve E is closed, vacuum pump B-1 is activated, valves A and q are opened, and the diluted EOG, etc. is passed through piping 24. It is led out of the closed circuit and is subjected to separate detoxification treatment, taking into account the scale of the equipment, environment, etc.

FIG. 1 shows an example of such a dilute EOG absorption device as the third invention. In this EOG absorption device, as shown in Japanese Patent Application No. 63-177199, EOG and the like are absorbed as diethylene glycol by a sulfuric acid solution in a scrubber 4, and exhaust gas is discharged into the atmosphere from an outlet 30.

This absorption process ends when the pressure in the sterilization chamber reaches 50 Torr, and the vacuum pump B-1 is stopped. Then, valves A and Cx are closed and valve E is opened to introduce air into the sterilization chamber 1 to return the sterilization chamber to normal pressure, after which the sterilized articles are taken out.

When performing the next sterilization process, the pressure in the sterilization chamber is reduced, CO is replaced as necessary, and then only the valve is opened to allow the EOG, etc. stored in the pressure accumulation tank 3 to flow into the sterilization chamber 1. Next, the EOG that is discharged and reduced in volume when the article is taken out is replenished into the cylinder 7.

In addition, in order to avoid condensation as a temperature condition in the sterilization room, it is necessary to operate within the range of 15 to 50°C since EOG condenses at a pressure of 2.12 ata or more at 30°C.

Next, the second invention will be explained based on FIG. The process shown in FIG. 2 is obtained by adding the following two steps to the process shown in FIG. 1 described above.

That is, l) introducing steam into the sterilization chamber to reduce the volume of the sterilization chamber -
The sterilizing effect is enhanced by adding approximately 49 cc of water per bottle. 2) A condensing type dehumidifier 34 is installed on the suction side of the compression stem to condense moisture around dust, dead bacteria, and mold spores and remove them, thereby purifying the EOG to be recycled. It is. Any known dehumidifier can be used as long as it is a condensing type dehumidifier using chiller water. This dehumidification device is provided with a finned tube inside, and chiller water from the chiller 35 circulates within the dehumidifier 34 and condensed water is discharged from the trap 36. At this time, water condenses on the surfaces of dead bacteria, mold spores, etc., and these impurities are efficiently removed, which improves the image of cleaning that can be achieved by recycling EOG. Incidentally, with the installation of the dehumidifier 34, gas is returned from the pressure storage tank 3 to the gas tank 2 via the conduit 40, and the temperature of the pressure storage tank 3 is adjusted.

〔Example〕

The experiment was conducted under the following conditions.

Sterilization chamber capacity 5Wt EOG composition used 80G20t, Co, 8Ot Sterilization room pressure 2 ata ~50 Tory vacuum pump discharge ffk 2,0? F/A injection tank capacitance 0. Sr & Compressor 2.2 Synthetic pressure accumulator tank pressure 8 ata Pressure accumulator tank storage 1. ．． 5tt/ When valves A-H are closed and the sterilization process is completed, valve A11 is closed.
1 and C are opened and the pressure in the sterilization chamber is controlled by the PSA (pressure regulator) so that the pressure in the sterilization chamber reaches 2 at, and from a to 1. ．． 2at
It became a.

Next, the vacuum pump B-1 operates, opens the valve ■, and opens the valve 11.
The sterilization chamber went from 1.2 ala to 5Q Tor in 7 minutes after closing.
r, and the LE power of the pressure accumulator tank 3 when it is 7.5
The pressure was increased to ata.

Valves A, B, and C are then closed, and valve B is opened to allow air to flow into the sterilization chamber, from 5 Q Torv to 1. It became ata. The EOG concentration in the Konotaki sterilization room is 13,000 p.
It was plTl.

The seventh vent valve E was closed, valves A and G were opened, the vacuum pump was activated, and the sterilization chamber was heated from 1 ata to 50 Torr in 6 minutes.

Close valves A and (3) and open valve B again to allow air to flow into the sterilization chamber, and the pressure in the sterilization chamber iJ: from 50 Torr to 1 al
It became a. The time required for this is 1 minute and the EOG concentration is s
It was oo ppm. Next, valve E is closed again and valves A and G are opened, and the vacuum pump is activated for 1.2.6 minutes. ata
It became 5 Q Torr. Then stop:
When air is introduced in an ε-like manner, the concentration of EOG is 50pp.
It became m. A mixture of my own 3 (b) air, :) TaJkuO
G and the like were absorbed as ethylene glycol by the scrubber 5 of the EOG absorption device.

After taking the workpiece that has been sterilized with EOG, etc., and performing IE, close valve E, open valves A and G, and turn on vacuum pump B-1.
The sterilization chamber was evacuated with 5Q Torri. Then valve A
(After closing 3 and stopping the vacuum pump, the valve was opened to allow EOG, etc. to flow from the pressure accumulation tank 3 into the sterilization chamber in preparation for the next sterilization process.

The pressure of the pressure storage tank is 7.5 ata to 1.85 ata.
A and the pressure in the sterilization chamber became 1.85 ata, so the valve was closed and valve F was opened to replenish EOG and the like from the EOG cylinder to the sterilization chamber to bring the pressure to 2 ata. The time required for this was 2 minutes υ, and the total time required for 1 cycle was 4
It was 5 minutes.

In this case, the amount of ethylene glycol absorbed by the EOG absorption device was 0.13 Kf, and the amount was equivalent to 4 tons of EOG used.

〔Effect of the invention〕

In conventional operation, EOG cylinder (EOG 20%, cot
80% mixed gas) was consuming 600 KzA, but by the method of the present invention, EOG etc.
i'I4 could be recovered and absorbed as 4 EOGFi ethylene glycol, resulting in almost no air pollution.

[Brief explanation of drawings]

Figure 1 is a flow sheet showing one embodiment of the present invention. FIG. 2 is a flow sheet showing another embodiment of the present invention.

Claims (3)

[Claims] (1) A sterilization chamber, a vacuum pump, a cushion tank, a compressor, and a pressure storage tank are sequentially connected by piping to form a closed circuit that returns from the pressure storage tank to the sterilization chamber, and the ethylene oxide gas (hereinafter referred to as ethylene oxide gas) after sterilization in the sterilization chamber is The EOG (hereinafter referred to as EOG) is stored and recovered in a pressure storage tank using a compressor for reuse, and the unrecoverable diluted EOG generated when the objects to be processed are taken out and taken out of the sterilization chamber is discharged from the system, and the insufficient EOG is replenished. A method for collecting EOG characterized by the following. (2) In the closed circuit according to claim (1), a steam blowing means is provided in the sterilization chamber, and a dehumidifier is provided between the cushion tank and the compressor to remove dead bacteria and fungi generated during the sterilization process. EO characterized by discharging spores, dust, EOG reaction products, etc. out of the system together with condensed water
How to collect G. (3) A claim characterized in that the dilute residual EOG, which is less than the recoverable limit, generated when the material to be processed is taken out and taken out of the sterilization chamber is guided to an absorption device by a vacuum pump, detoxified, and then discharged into the atmosphere. The EOG recovery method described in (1) and (2).