JPS6339848B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for sterilizing a device for measuring volatile components in liquid.

The volatile components in the liquid mentioned here include a wide range of volatile compounds such as volatile aromatic compounds or their halides, such as alcohols, aldehydes, ketones, organic acids, mercaptans, lower aromatics, and fats. hydrocarbons and their derivatives, such as halides. Furthermore, various monomers such as vinyl chloride monomers are also included. Furthermore, the liquid referred to herein includes aqueous solutions, non-aqueous solutions, and liquids in which solids are dispersed or suspended in these solutions. The liquid in which solids are dispersed is, for example, a latex in which a polymer such as an oligomer is suspended, an aqueous slurry liquid, a culture liquid of microorganisms, industrial wastewater, or the like.

As a method for measuring the concentration of vaporizable components in these liquids, a porous tube (hereinafter referred to as
A method for measuring the concentration of volatile components in a liquid using a porous tube (simply referred to as a porous tube) is known.

The principle of an apparatus for measuring the concentration of volatile components in a liquid using a porous tube is as follows.

A porous tube with carrier gas supply and exhaust conduits connected to both ends is immersed and installed in a container filled with the liquid to be measured. The porous tube is made of a material with strong liquid repellency, so
No liquid enters into the continuous micropores. Therefore, a gas-liquid interface is formed on the surface of the porous tube. When carrier gas is supplied from the carrier gas supply section to the porous tube, vaporizable components in the liquid permeate and diffuse into the carrier gas through the continuous micropores of the porous tube. By guiding this carrier gas to the component detection section, the concentration of the volatile component in the liquid can be indirectly determined as the concentration of the volatile component in the carrier gas.

A device that uses a porous tube to measure the concentration of volatile components in a liquid is effective in measuring the concentration of by-product components and substrate components present in the culture solution during the cultivation process of various microorganisms. This is the case when measuring . In the culture process of microorganisms, for example, in the culture process of baker's yeast, it is important to control the concentration of ethanol produced as a by-product during culture. Furthermore, when producing alcohol using microorganisms, it is important to constantly monitor the concentration of the product and control production.

In culture processes using such microorganisms, it is important to suppress the proliferation of bacteria other than the target bacteria, that is, germs, so all equipment and instruments used that come into contact with the culture solution must be sterilized. It will be used after applying. Sterilization methods include chemical sterilization and heat sterilization, but heat sterilization using steam is the most effective method for sterilizing the entire culture tank, and is generally used. In particular, it is extremely effective to increase the pressure of the steam blown into the culture tank, slightly pressurize the entire tank, and keep the internal temperature high. For example, by keeping the tank under pressure of 1.0 Kg/cm ² G or higher and performing high-temperature sterilization at a temperature of 120° C. or higher, most of the bacteria that would be an obstacle to yeast production in general can be killed.

For a device for measuring the concentration of volatile components in liquid using a porous tube with liquid repellency and continuous micropores,
There are several problems with carrying out heat sterilization under pressure. The first problem is the heat resistance of the porous tube material itself. Regarding this point, it is necessary to select a material that is sufficiently heat resistant at the heat sterilization temperature. By selecting porous tetrafluoroethylene, which is the most commonly used material for conventional porous tubes, it can withstand high temperatures of 200°C or higher. The second problem is that the shape of the tube cannot withstand the pressurized conditions and is deformed or crushed. Once the circular cross section of the porous tube is crushed and deformed, deformation tends to occur in that part, and even if the pressure condition is restored, the deformation often remains and does not return to its original state. If the cross section of the tube remains deformed, the passage of the carrier gas will be narrowed during the measurement state, resulting in a change in the flow rate of the carrier gas passing through the porous tube or a change in pressure, causing instability in the measurement. becomes. Furthermore, if the porous tube were completely collapsed, no carrier gas would naturally flow and measurements would be completely impossible. The third problem is that under pressurized conditions, steam is forced into the carrier gas through the continuous micropores of the porous tube. The fourth problem is that since the atmosphere outside the porous tube is filled with water vapor, water vapor diffuses into the porous tube through the continuous micropores of the porous tube. The third and fourth problems are that extremely large amounts of water vapor end up flowing into the carrier gas within the porous tube. Since the amount of water vapor flowing into the carrier gas is extremely large, the water vapor condenses in the carrier gas and forms droplets, which accumulate in the porous tube and the carrier gas supply/exhaust conduit, clogging the carrier gas flow path. In extreme cases, water droplets often reach the component detection section, causing damage to the component detection section. Further, even after heat sterilization is completed, a large amount of water droplets remain in the carrier gas flow path and in the continuous micropores, so if measurement is started in this state, a big problem will occur. In other words, when a large amount of water exists in the continuous micropores, the outside and inside of the porous tube become electrically conductive, and when the porous tube is placed in the liquid to be measured in this state, the repellency of the porous tube material increases. Despite its liquid nature, the liquid to be measured is in conduction with the inside of the porous tube through the water droplets in the continuous micropores, allowing only vaporizable components to permeate from the liquid to be measured, which is required for porous tubes. This basic function cannot be performed at all. If measurement of the concentration of volatile components in the liquid is started with even a small amount of water droplets present inside the porous tube or in the carrier gas supply/exhaust pipe, the volatile components in the liquid collected in the carrier gas will dissolve into the water droplets. As a result, the concentration of volatile components in the carrier gas changes, which greatly affects measurement accuracy. Furthermore, as described above, water droplets in the carrier gas flow path may reach the component detection section due to the carrier gas and cause damage to the detection section.

As mentioned above, heat sterilization using steam, which is essential for the microbial culture process, is extremely inconvenient for conventional measuring devices for measuring the concentration of volatile components in liquid, which use a porous tube with liquid repellency and continuous micropores. be. Regarding chemical sterilization other than steam sterilization,
This is particularly disadvantageous in that it impairs the liquid repellency that is essential for porous tube materials.

The present invention uses a porous tube with liquid repellency and continuous micropores in the tube method, and a switching device is provided in the middle of the conduit that supplies carrier gas to the porous tube. When sterilizing a porous tube with steam, a large amount of pressurized gas is sent from the pressurized gas supply section to prevent deformation of the porous tube and to remove a large amount of steam that diffuses into the porous tube. By making it possible to smoothly discharge out of the carrier gas line,
To provide a method for sterilizing an in-liquid vaporizable component measuring device that can handle the conditions during sterilization and component measurement with simple operations in the microbial culture process where steam heat sterilization at high temperatures of 100°C or higher is an essential condition. It is something.

The present invention provides an in-liquid vaporizable component concentration measuring device that uses a liquid-repellent, heat-resistant, porous tube with continuous micropores as a sampler, in which the tube is immersed in a liquid to be measured at the beginning of use. First, the outer surface of the tube is exposed to the pressurized steam atmosphere for heat sterilization while passing a vaporizer having a pressure higher than the pressure of the pressurized steam atmosphere for heat sterilization through the tube. The contents include a method for sterilizing the tube of a device for measuring volatile components in liquid.

Below, the content of the present invention will be explained in detail.

The basic configuration of the tube method for measuring the concentration of volatile components in a liquid using a porous tube with liquid repellency and continuous micropores is to install a carrier gas at each end of the porous tube that is immersed in the liquid to be measured. Air supply and exhaust conduits are connected, and the carrier gas supply conduit is connected to a carrier gas supply section, and the carrier gas exhaust conduit is connected to a component detector via a throttle section. Gases used as carrier gas include inert gas and air. There may be restrictions on the carrier gas used depending on the type of component detection unit used, but nitrogen gas or air is suitable for hydrogen flame ionization detectors, catalytic combustion type detectors, semiconductor type detectors, etc. It is.

The flow rate and pressure of the carrier gas supplied to the porous tube are regulated by both the carrier gas supply section and the throttle section. The flow rate and pressure of the carrier gas through the porous tube must be determined keeping in mind the following points: In other words, regarding the pressure, the internal pressure in the porous tube must be such that the carrier gas does not blow out from the continuous micropores of the porous tube in the liquid, and the pressure of the liquid applied to the porous tube does not force the liquid into the continuous micropores. must be maintained. In other words, it is optimal for the carrier gas to pass through the porous tube portion at a pressure slightly lower than the pressure of the liquid across the porous tube. Regarding the flow rate of the carrier gas, it is desirable that the concentration of the vaporizable components in the carrier gas reach the vapor-liquid equilibrium concentration under the current pressure and temperature conditions of the liquid while the carrier gas passes through the porous tube portion. This relationship is related to the total amount of vaporizable components in the liquid that passes through the porous tube, and the larger the membrane area of the porous tube, the more
The larger the aperture ratio of the porous tube and the lower the flow rate of the carrier gas, the closer the concentration of vaporizable components in the carrier gas will be to the vapor-liquid equilibrium concentration in the state at that time. For example, inner diameter 0.3cm, length 10cm, porosity approx.
When using a 50% porous tube, the carrier gas flow rate is preferably 30 ml/min to 60 ml/min.

Now, when a container in which a porous tube is installed is sterilized using steam, there is a problem that the porous tube is deformed and a large amount of steam flows into the porous tube as described above. For this purpose, a carrier gas switching device is installed in the middle of the carrier gas supply and exhaust conduits, and the pressure gas supply section is connected to the air supply conduit, and the pressurized gas discharge section is connected to the exhaust conduit through the throttle section. do. During sterilization, these carrier gas switching devices are used to stop the carrier gas supplied to the porous tube during measurement, and pressurized gas is supplied from the pressurized gas supply section, so that the pressurized gas that has passed through the porous tube is still The carrier gas switching device releases the pressurized gas from the pressurized gas release section to the outside of the system.

The pressure of the pressurized gas passing through the porous tube is
It must be set to a higher value than the pressure inside the container during sterilization. The flow rate of the pressurized gas needs to be sufficient to smoothly remove the steam flowing into the porous tube. If the porous tube described above is used, a flow rate of about 1 to 2 per minute is sufficient.

The type of pressurized gas may be the same as the carrier gas. Furthermore, it is important that the pressurized gas itself is not harmful to microorganisms, and that it does not contain harmful components. Furthermore, it is desirable to use a gas that does not contain germs or a sterilized gas.

The throttle part connected to the pressurized gas discharge part is used together with the pressurized gas supply part to adjust the flow rate and pressure of the pressurized gas.

The carrier gas switching device is a 2-way valve, 3-way valve, 2-way valve,
It is constructed using one-way solenoid valves, three-way solenoid valves, Kotsukku, multi-way Kotsukku, etc.

The carrier gas switching device must, of course, be leak-free, but it also needs to have a structure that does not accumulate internally. If there is a pool in the switching device and pressurized gas is supplied during sterilization, if the steam contained in the pressurized gas condenses and forms water droplets in the pool, the switching device switches to the measurement state and the carrier gas is This is because if air is supplied, the carrier gas flow path may be blocked or the component detection section may be damaged by water droplets.

As mentioned above, during sterilization, the pressurized gas sent from the pressurized gas supply section passes through the carrier gas switching section, the carrier gas supply conduit, the porous tube, the carrier gas exhaust conduit, the carrier gas switching section, and the squeeze section. The gas flows and is discharged from the pressurized gas discharge section to the outside of the system. On the other hand, the carrier gas supplied from the carrier gas supply section is stopped at the carrier gas switching section, so that the carrier gas is not supplied to the component detection section.

Although it varies depending on the type of component detection unit used,
Some detectors require a considerable amount of time to stabilize after being energized. Furthermore, during energization aging, it is often better for the stability of the detection unit to maintain the same state as that at the time of measurement. For example, this is the case when a catalytic combustion type detection section, a metal oxide semiconductor type detection section, etc. are used. This is because the temperature and atmosphere of the detection section differ depending on whether the carrier gas passes through or not. When using these component detection sections, it is desirable that the carrier gas flows into the component detection section during sterilization as well as during measurement. Therefore, the carrier gas can be switched at two locations, from one point between the carrier gas supply section and the carrier gas switching device to one point between the second carrier gas switching device via the porous tube and the throttle section connected to the component detection section. It is preferable to provide a bypass line through which the carrier gas flows directly without passing through the device. That is, during sterilization using this bypass line, the carrier gas supplied from the carrier gas supply section directly reaches the component detection section via the bypass line and the aperture section.

Note that when measuring the vaporizable components in the liquid, the carrier gas passes through the porous tube, so a bypass line is not required. Therefore, the bypass line also requires a switching device to open and close during sterilization and measurement. The length of the bypass line is such that the flow rate and pressure of the carrier gas are the same when the carrier gas flows through the bypass line during sterilization and when the carrier gas is sent through the porous tube during measurement. It is desirable to consider the size and caliber. This allows the carrier gas to flow under the same conditions in both sterilization and measurement conditions.

It is desirable that the porous tube used in the measuring device of the present invention have stronger liquid repellency, smaller continuous micropores, and larger porosity. In terms of material, tetrafluoroethylene resin is the best, and the pore size is
A material with a pore size of about 0.1 to 1.0 μm and a porosity of about 20 to 80% can be used. Among these, in view of the relationship between pore size and porosity, one with a pore diameter of about 0.5 μm and a porosity of about 50% is preferable.

As mentioned above, a porous tube with liquid repellency and continuous micropores is used in the tube method, and a carrier gas switching device is installed at both ends of the porous tube.
During measurement, carrier gas is guided from the carrier gas supply section to the component detection section via the porous tube and squeeze section, and during sterilization, the carrier gas switching device is switched and pressurized gas is sent from the pressurization gas supply section to the porous tube. , a measuring device with a structure that releases gas to the outside of the system through a squeezing part and a pressurized gas release part, and a measuring method using the same can easily be used for processes that require steam sterilization at high temperature and high pressure, such as microbial culture processes. This means that it can handle sterilization and measurement conditions.

Examples will be described below with reference to the drawings.

Example 1 Continuous measurement of ethanol concentration in a microorganism culture process was carried out using an in-liquid vaporizable component concentration measuring device having the structure shown in FIG.

The porous tube 1 was a tube made of tetrafluoroethylene resin having liquid repellency and continuous micropores, and had a pore diameter of 0.45 μm, a porosity of 60%, an inner diameter of 0.3 cm, and a length of 10 cm. The carrier gas switching units 5 and 8 are a combination of a two-way solenoid valve and a three-way solenoid valve with little accumulation. The bypass line switching device 11 also used a two-way solenoid valve. Nitrogen gas was used as the carrier gas, a fixed aperture using a thin tube with an inner diameter of 0.3 mm was used as the aperture part 9, and a hydrogen flame ionization detector was used as the component detection part 10. Sterilized air was used as the pressurized gas, and the throttle section 14 was a variable throttle using a needle valve. Measurement liquid container 2 has a capacity of approximately 300
m ³ and the liquid volume is about 150 m ³ .

To sterilize container 2 before measurement, use steam to sterilize the container.
It was maintained at 120° C. and 1 Kg/cm ² G for about 5 hours. During sterilization, pressurized gas was fed from the pressurizing gas feeding section 13 so that the pressure was about 1.2 Kg/cm ² and the flow rate was about 1.5/min when passing through the porous tube 1. meanwhile,
The carrier gas continued to be supplied to the component detection section 10 via the bypass line switching device 11 and the bypass line 12.

After the inside of the container 2 was left to cool and the pressure was reduced, the carrier gas switching devices 5, 8, and 11 were switched, and the ethanol concentration in the liquid was continuously measured.

For an object in which the pressure of liquid 3 applied to porous tube 1 changes from 0.35 Kg/cm ² G to 0.50 Kg/cm ² G over time, the flow rate of the carrier gas is 40 ml/min, and the pressure in the porous tube is 0.30 Kg. Air was supplied with the setting set to /cm ² G.

Switch the carrier gas switching devices 5, 8, 11,
When measurements started, stable continuous measurements were obtained for about 70 hours (Figure 2).

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of one example of the apparatus of the present invention, and FIG. 2 is a diagram of continuous measurement of ethanol concentration in Example 1 using the measuring apparatus shown in FIG. DESCRIPTION OF SYMBOLS 1...Porous tetrafluoride ethylene tube, 2...Measurement liquid container, 3...Measurement liquid, 4...Carrier gas air supply part, 5...Carrier gas switching device, 6...Carrier gas air supply conduit, 7...Carrier gas exhaust conduit, 8
...carrier gas switching device, 9...throttle section, 10...
Component detection unit, 11... Bypass line switching device, 1
2... Bypass line, 13... Pressurizing gas supply section,
14... Squeezing part, 15... Pressurized gas discharge part.

Claims (1)

[Claims] 1. In a device for measuring the concentration of volatile components in a liquid that uses a water-repellent, heat-resistant porous tube with continuous micropores as a sampler, the tube is pressurized before being immersed in the liquid to be measured at the beginning of use. Submerged vaporization, characterized in that the outer surface of the tube is exposed to the pressurized steam atmosphere for heat sterilization while passing a gas having a pressure higher than the pressure of the pressurized steam atmosphere for heat sterilization into the tube. How to sterilize the tube of a sexual component measuring device.