JPH0739572B2 - Evaporation suppressant and evaporation suppression method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention discloses that liquefied gas that produces toxic and irritating gases such as ammonia water and acetic acid leaks from a closed container during storage due to an earthquake or other unexpected accident. In this case, the present invention relates to a gas evaporation inhibitor that covers the surface of the leaked evaporative liquid and a gas evaporation suppression method using the same in order to urgently suppress the evaporation of toxic and irritating gases.

[Conventional technology]

For example, if the high-concentration aqueous ammonia leaks during storage, a large amount of the stimulating gas evaporated in the atmosphere may diffuse to cause serious damage.

Therefore, a method is generally used in which the storage tank is surrounded by a dike to prevent the effluent from diffusing and a large amount of water is injected to dilute it. Also, Japanese Patent Publication No. 61-17768 proposes a method of covering the surface of liquid ammonia that has flowed out with bubbles to prevent evaporation. This is because, for example, an aqueous solution of a water-soluble bubble forming agent consisting of an anionic surface active agent which is a foaming agent and glycol ether which is a foaming stabilizer is widely sprayed on the liquid surface of liquid ammonia leaking in the dike, By generating bubbles containing gas and covering the liquid surface with the bubbles, the evaporation and diffusion of ammonia is suppressed.

[Problems to be Solved by the Invention]

However, in the conventional dilution method using water injection, an extremely large amount of water must be used, and -30 to -40 ° C.
Injecting room temperature water into the leaking ammonia, which is the low temperature of
The leaked ammonia explosively evaporates at the beginning of water injection. Therefore, there is a drawback that the subsequent secondary treatment of a large amount of water becomes difficult.

On the other hand, the method of covering the liquid surface with bubbles to suppress evaporation has the following problems.

The retention time of bubbles is as short as about 30 minutes, and the leaked liquefied gas in the dike must be pumped out by a vacuum car etc. within the duration.

The bubbles are easily blown off and the liquid surface of the leaked liquefied gas is easily exposed. Moreover, once the bubbles are blown off, it is necessary to newly add a bubble-forming agent to foam the bubbles.

Since the bubble forming agent is used as an aqueous solution, the inside of iron containers, pipes and the like are easily rusted, and rust preventive measures are expensive.

Since the bubble forming agent is sprayed with an aqueous solution of about 6%, a large-capacity water storage tank along with a storage tank for the bubble forming agent is required for leaked liquefied gas that stays in a large levee. Becomes expensive.

In order to spray the aqueous solution of the air bubble forming agent on average over the entire liquid surface of the liquid ammonia leaked into the levee, install a large number of spray nozzles in the pipe with a long extension distance and spray equipment over the entire liquid surface. Is required, and the equipment cost and maintenance cost are high.

Therefore, the present invention has been made by paying attention to the above-mentioned conventional problems, and the purpose thereof is to cover the liquid surface of the liquid to be treated with a non-water-soluble liquid having an extremely long duration and a toxic gas, An object of the present invention is to solve the problems of the prior art by providing an evaporation inhibitor and a method for suppressing evaporation of liquefied liquefied gas that urgently suppresses evaporation of irritating odorous gas.

[Means for Solving the Problems]

In order to achieve the above object, the method for suppressing evaporation of an evaporated liquefied gas according to the present invention is characterized in that the liquid surface of the evaporated liquefied gas is covered with a liquid whose main component is a saturated hydrocarbon.

Further, the gas evaporation inhibitor of the present invention is represented by the general formula C _n H _{2n + 2} and n is 10 to 46, and a paraffinic hydrocarbon And a naphthene-based hydrocarbon having n of 10 to 46 are mixed.

In order to further improve the evaporation suppressing effect, the gas evaporation suppressing agent, an organic compound having a hydrophilic group such as carboxyl group COOH, hydroxyl group OH, amino group NH ₂ and sulfonic acid group SO _{3 at} the end group, for example, Etc. are mixed.

[Action]

For example, when a high-concentration aqueous ammonia solution leaks into the dike, if a gas evaporation inhibitor containing a mixture of saturated hydrocarbons as the main component is sprayed on the liquid surface of the leaked liquid, it spreads and covers the liquid surface, which is irritating. It is possible to suppress evaporation of ammonia gas over a long period of time.

The physical properties of a mixture of paraffin hydrocarbons and naphthenic hydrocarbons are inert to heat, light, chemicals such as acids and alkalis, and have excellent long-term stability, and they are not corrosive to metals and are suitable for containers, piping, etc. There is no risk of rusting.

Further, since the liquid surface can be covered with a layer having a certain thickness, it is not blown away by the wind like bubbles, and exhibits a stable gas evaporation suppressing effect for a long time.

Therefore, it is possible to process the leaked liquid over time. Further, even when the leaked liquid is collected, the gas inhibitor coating does not break, and gas evaporation is completely prevented. Moreover, since the gas suppressor itself is not toxic, it is possible to work extremely safely.

An organic compound having a hydrophilic group at the terminal group, such as a methacrylic acid polymer mixed in a gas evaporation inhibitor, promotes diffusion of saturated hydrocarbons to the liquid surface to be treated, and fluidly spreads over the entire liquid surface.

Further, in the gas evaporation suppressing device, it is not necessary to provide a water storage tank other than the storage tank for the gas evaporation suppressing agent, and the equipment cost and installation space are small.

This will be described in more detail below.

The gas evaporation inhibitor of the present invention comprises a paraffinic hydrocarbon represented by the general formula C _n H _{2n + 2} and n is 10 to 46, and a general formula And a mixture with a naphthene-based hydrocarbon having n of 10 to 46 is preferable, and when n is less than 10, it is not preferable because the flash point is lowered even if it is gaseous or liquid. On the other hand, when n exceeds 46, the liquidity is insufficient.

The mixing ratio of paraffinic hydrocarbon to naphthenic hydrocarbon is appropriately in the range of 6: 4 to 8: 2, and particularly 7: 3.

If the ratio of the paraffinic hydrocarbon is less than 6, the viscosity becomes too low, while if it exceeds 8, the fluidity is lowered and the usability becomes poor.

Liquid paraffin with n = 15-34 and paraffin hydrocarbon: naphthene hydrocarbon = 7: 3 has a flash point of about 220 ℃, 20 ℃.
It has a specific gravity of 0.82 to 0.89 g / cc and can be suitably used.

The liquid paraffin may be used as it is by spraying it onto the surface of the liquid to be treated such as ammonia water, but it is a polymer that has good compatibility with the above hydrocarbons and is hydrophilic. It improves the spreadability on the surface to be treated, especially because it has a good affinity with the concrete surface of the levee, so the liquid paraffin and the meniscus on the concrete surface become concave, and the effect can be further improved. I can.

It was confirmed by experiments that the amount of the above polymer added is preferably in the range of 0.01 to 10 W / V%.

The liquid to be treated to which the gas evaporation inhibitor of the present invention can be applied is, for example, high-concentration aqueous ammonia, acetic acid, amines such as monomethylamine, dimethylamine, trimethylamine, and hydrogen cyanide. And has a larger specific gravity than saturated hydrocarbons.

〔Example〕

 Examples of the present invention will be described below.

(First Example) As a liquid to be treated in an open container having a side length of 1 m and a depth of 20 cm.
29% ammonia water was added, and as a gas evaporation inhibitor, specifically, C _n H _{2n + 2} (n = 15 to 34) paraffinic hydrocarbon: (N = 15 to 34) naphthenic hydrocarbons = 7: 3 liquid paraffin was added to the ammonia water weight loss with time without gas evaporation inhibitor (blank)
Compare with.

The amount of weight loss due to the evaporation of ammonia gas is placed on a platform type load cell (Kyowa Dengyo Co., LCL-F), and the strain amount is measured with a dynamic strain measuring instrument (the same as DPM-611A).
Record on the recorder.

Test conditions Average temperature: Approx. 25 ℃ Ammonia water amount: 25.78kg Ammonia water temperature before injection: 23 ℃ Ammonia water concentration before injection: 29% Gas evaporation inhibitor injection amount: 8.42kg Coating layer thickness of injection inhibitor: 1cm Fig. 1 [Fig. 3] is an ammonia gas evaporation amount diagram obtained in the above test.

From this figure, the gas evaporation suppressing effect of the gas evaporation suppressing agent of the present invention is clear.

(Second Example) A change in developability and a change in meniscus when a methacrylic acid polymer having a carboxyl group as a hydrophilic group in a terminal group are mixed with the same liquid paraffin as in the first example will be examined.

Into the center of the liquid surface of 29% ammonia water in a container, slowly pour 50 ml of a gas evaporation inhibitor, which is a mixture of liquid paraffin and a predetermined amount of methacrylic acid polymer. Since the gas evaporation inhibitor floats in a nearly perfect circle on the surface of ammonia water, its diameter and thickness are measured on a scale. The results are shown in Table 1.

Next, when 50 ml of the gas evaporation inhibitor is added, the gas evaporation inhibitor on the ammonia water surface completely reaches the container wall and seals the ammonia water surface. FIG. 2 shows the state of the meniscus between the concrete container 1 and the gas evaporation inhibitor 3 covering the ammonia water 2 at this time.
Represents the thickness of the evaporation suppressor in a place not in contact with the concrete wall, and B represents the thickness of the evaporation suppressor in a place in contact with the concrete wall. The changes in the dimensions of A and B are measured on a scale. The results are shown in Table 2.

By adding a small amount of methacrylic acid polymer, the developability of the gas evaporation inhibitor is greatly improved. this is,
By the action of the methacrylic acid polymer, which is hydrophilic and compatible with liquid paraffin, which is the main component for suppressing gas evaporation,
This is because the interfacial tension between liquid paraffin and ammonia water is reduced. Further, the reason why the meniscus of the concrete and the evaporation inhibitor is improved is that the affinity of the methacrylic acid polymer having the hydrophilic group (hydroxyl group) and the hydrophilic group (carboxyl group) on the concrete side is good, With this addition, the evaporative gas sealing performance is improved and the amount of the gas evaporation inhibitor used can be reduced.

In addition, other organic compounds having a hydrophilic group at the terminal group also exhibited the same developability of fluidity and change of meniscus.

[Effects of the Invention] As described above, according to the present invention, the liquid level of the evaporative liquefied gas is covered with the gas evaporation inhibitor whose main component is saturated hydrocarbon, and the following remarkable effects are obtained. Can be obtained.

The surface of the leaked liquid can be completely covered, and gas evaporation can be suppressed for a long time. Moreover, it is difficult to be blown away by the wind, and even if blown away, it will be restored.

Saturated hydrocarbons are inert to heat, light and chemicals and can be stored for long periods.

In addition, it is not corrosive to metals and is easy to maintain and handle.

It is possible to process the leaked liquid to be processed over time and work safely.

[Brief description of drawings]

FIG. 1 is an ammonia gas evaporation amount diagram for explaining the effect of the gas evaporation inhibitor of the present invention, and FIG. 2 is a diagram for explaining a method for measuring a change in meniscus between concrete and the gas evaporation inhibitor.

Claims (2)

[Claims] 1. A paraffinic hydrocarbon represented by the general formula C _n H _{2n + 2} , where n is 10 to 46, and a general formula Which is selected from the group consisting of methacrylic acid polymer, acrylic acid polymer, polyvinyl alcohol, polyacrylamide, polyethyleneimine, and polyethylenesulfonic acid, in the liquid paraffin mixed with a naphthenic hydrocarbon represented by A gas evaporation inhibitor formed by mixing one or more substances. 2. A method for suppressing evaporation of liquefied volatile gas, which comprises covering the liquid surface of the liquefied volatile gas with the gas evaporation inhibitor according to claim 1.