JP4083707B2 - Method and apparatus for testing activity of alkali metal dispersant - Google Patents

Description

  The present invention relates to an activity test method and apparatus for an alkali metal dispersant used when dechlorinating an organic chlorine compound such as polychlorinated biphenyl (PCB) which is an environmental pollutant. The present invention also relates to a regeneration method and apparatus for reactivating an alkali metal dispersant having reduced activity.

  Alkali metals are used in the manufacture of various chemical industrial products because of their high reducibility. In order to obtain as many reduction products as possible per unit time, it is necessary to make the alkali metal fine and to increase the contact surface area with other substances as much as possible. For this reason, in a liquid having good coexistence with alkali metal and chemical industrial products, the alkali metal is often made into fine particles and dispersed to be used as a liquid colloid (referred to as a suspension or a dispersant).

  The alkali metal in the alkali metal dispersant is covered with a liquid medium such as mineral oil, and is isolated from oxygen and moisture (including moisture) in the air. For this reason, the alkali metal dispersant is easier to handle than the single alkali metal. On the other hand, the alkali metal in the liquid is very useful because it maintains its properties and is highly reactive, and is used, for example, as a dechlorinating agent for persistent organic chlorine compounds such as PCB.

  However, it may take several months to use the produced alkali metal dispersant as a dechlorination agent for organochlorine compounds. During this time, the activity of the alkali metal is lowered, and the desired dechlorination reaction is performed. It may not be obtained.

  The reason why the activity decreases when the alkali metal dispersant is left for a long time is, for example, that oxygen and moisture in the air gradually dissolve in the medium, and the extreme surface layer of the alkali metal particles is altered by the dissolved oxygen and moisture. It is possible to do. In addition, it is conceivable that the fine alkali metal in the dispersed state settles and the fine particles are bonded to each other and the surface area contributing to the reaction is reduced because the original dispersed state is not recovered by simple stirring.

  As an improvement measure to prevent these activity declines, the production and storage of a dispersant is performed in an inert gas atmosphere such as nitrogen or argon gas to prevent alteration of alkali metal due to oxygen or moisture ( For example, see Patent Document 1). In addition, it is known to stir during storage and transportation in order to prevent sedimentation of the dispersant during storage (see, for example, Patent Document 2).

JP 59-20179 (Claims 8 and 9)

JP 2002-58979 A (summary)

  Although the prior art is one method for preventing the decrease in the activity of the alkali metal dispersant, it is still unclear whether the alkali metal activity can be maintained when the alkali metal dispersant is stored for a long period of time. The problem remains. Although it is conceivable to dispose of the alkali metal dispersant when the expiry date has been set and the expiry date has expired, there is a case where it is discarded even though the activity is not lowered, which is uneconomical.

  An object of the present invention is to provide a method and apparatus for simply examining the activity of an alkali metal dispersant used as a dechlorinating agent for dechlorinating a hardly decomposable organochlorine compound such as PCB, and an alkali with reduced activity. It is an object of the present invention to provide a regeneration method and apparatus for reactivating a metal dispersant.

  The activity inspection method of the present invention is to react an alkali metal dispersant in the presence of an organic chlorine compound and a hydrogen donor, and to determine the presence or absence of the activity of the alkali metal dispersant from the degree of temperature change due to the heat of reaction. .

  The reaction between the alkali metal dispersant, the organic chlorine compound, and the hydrogen donor is an exothermic reaction. If the alkali metal dispersant has activity, the reaction raises the temperature. The greater the temperature rise at this time, the better the activity. In addition, the shorter the elapsed time to reach the maximum temperature, the better the activity.

  For the inspection of the activity, there are a method of allowing a liquid to flow from one end using a tubular reactor and a method of reacting using a batch type inspection container.

  In the method using a tubular reactor, an inlet for an alkali metal dispersant and an inlet for a mixed liquid of an organic chlorine compound and a hydrogen donor are provided at one end, and the two liquids are combined inside the reaction tube to cause a reaction. It is desirable to inspect the presence or absence of the activity of the alkali metal dispersant from the temperature change accompanying the flow and the distance that the liquid has moved before reaching the maximum temperature after flowing into the reaction tube.

  In addition, in a batch method using an inspection container, a hydrogen donor is dropped into a mixed liquid of an alkali metal dispersant and an organochlorine compound in the container to cause a reaction, and a temperature change accompanying the reaction and a maximum temperature are reached. It is desirable to check whether the alkali metal dispersant is active from the time required to reach it.

  In the reactivation method of the present invention, the alkali metal dispersant having reduced activity is subjected to a dispersion treatment in a state where the alkali metal is melted, and the altered layer on the surface of the alkali metal or / and the bond between particles is broken. is there. In the regeneration treatment of the present invention, it is necessary to prepare a dispersing device for dispersing an alkali metal dispersant having reduced activity and a heater for heating the alkali metal dispersant to the melting temperature of the alkali metal. Preferably, a cooler is further provided for cooling the alkali metal dispersant whose activity has been recovered to a temperature not higher than the melting point of the alkali metal.

  The dispersion treatment of the alkali metal dispersant is preferably performed by any one of a Cowles blade high-speed rotation method, a homomixer method, a pressurization homogenizer method, and an ultrasonic homogenizer method.

  The activity-reduced alkali metal dispersant to which the activity recovery method of the present invention is applied is, for example, a dispersant in which the inside of the alkali metal is maintained only by alteration of the surface layer portion of the alkali metal, and the dispersant is bonded to each other. Some of them are coarse, some have expired, and some have been determined to be inactive by the activity test of the present invention.

  According to the present invention, the inspection of the activity of the alkali metal dispersant can be quickly performed by a simple method. Moreover, the alkali metal dispersing agent with reduced activity can be regenerated by a simple method.

  Hereinafter, the activity test method according to the present invention and the method for reactivating an alkali metal dispersant having decreased activity will be described with reference to specific examples. However, the present invention is not limited to these embodiments.

(Activity test)
FIG. 1 shows a schematic diagram of a flow-type inspection apparatus for inspecting the activity of an alkali metal dispersant. The flow type inspection apparatus of the present embodiment includes a container 1 containing an alkali metal dispersant, a container 2 containing an organic chlorine compound to which a hydrogen donor is added, a pump 3 for feeding the alkali metal dispersant, It comprises a pump 4 for feeding an organochlorine compound to which a hydrogen donor is added, a tubular activity test tube 5, a temperature sensor 6, and a drainage recovery container 7.

  The inspection of the activity by the flow type is that the alkali metal dispersant to be inspected is supplied from the container 1 to the activity inspection tube 5 by the pump 3 and the organochlorine compound to which the hydrogen donor is added is supplied from the container 2 to the activity inspection tube 5 by the pump 4 The temperature change due to the reaction heat generated by the flow and mixing of the two liquids is measured by the temperature sensor 6 and carried out. Here, the temperature sensor 6 is preferably arranged with a plurality of thermocouples along the flow direction so that the temperature distribution of the liquid can be measured, but the surface temperature distribution of the active test tube 5 is measured. Also good.

  Whether or not the sodium dispersant is active is determined by the maximum temperature of the temperature distribution obtained by the temperature sensor 6. Preferably, the determination is based on both the maximum temperature and the time to reach the maximum temperature. Here, the maximum temperature and the time to reach the maximum temperature differ depending on the specific conditions such as the composition and flow rate of the mixed liquid, the shape and material of the activity test tube 5, and the heat radiation characteristics. For this reason, it is necessary to carry out a preliminary test to grasp the inspection conditions in which the concentration of organic chlorine remaining in the reaction solution is within a desired range and the temperature distribution of the activity test tube 5. The specific example of an activity test result is shown below.

  As the activity test tube 5, a fluororesin tube having an outer diameter of 6 mm, a wall thickness of 1 mm, and a length of 1 m was used. Thermocouples as temperature sensors 6 were attached to the outer surface of the activity test tube 5 at intervals of 100 mm. Further, the alkali metal dispersant to be inspected was a sodium dispersant in which sodium was dispersed in an electrical insulating oil. PCB oil was used as the organic chlorine compound.

  As the sodium dispersant, an average particle diameter of sodium particles at the time of production of about 6 μm and a concentration of 10% by mass was used. The test of activity is conducted on the sodium dispersant immediately after production, the sample left in air for about 2 months, and the sample left in air for about 4 months. Used.

  As the PCB oil, a PCB mixed oil diluted to 5% by mass with an electrical insulating oil and alcohol as a hydrogen donor (hereinafter simply referred to as a PCB mixed oil) was used.

  In the activity test, sodium dispersant and PCB mixed oil were supplied to the activity test tube 5 at 5 ml / min, respectively, and the temperature distribution in the flow direction of the activity test tube 5 was measured. An example of the obtained temperature distribution is shown in FIG.

  The sodium dispersant immediately after production shows a slight temperature rise due to the reaction of sodium and alcohol at the merge with the PCB mixed oil, and then a rapid temperature rise due to the dechlorination reaction from the position of about 400 mm, at a position of about 550 mm. Maximum temperature reached 95 ° C. When the time obtained by dividing the volume of the activity test tube 5 from the junction to the position where the maximum temperature is reached by the total flow rate is defined as the residence time, the residence time of the active sodium dispersant is about 42. Second.

  On the other hand, in the case of standing for about 2 months, the residence time was as long as about 53 seconds, and the maximum temperature was lowered to 70 ° C. Furthermore, when the sample was left standing for about 4 months, a rapid temperature increase due to the dechlorination reaction was not observed, and the decrease in the activity of the sodium dispersant could be clearly determined.

(Activity test)
FIG. 3 is a schematic view of a batch type inspection apparatus for inspecting the activity of the alkali metal dispersant. The batch type inspection apparatus includes an inspection container 20, a mixed liquid 21 of an alkali metal dispersant and an organochlorine compound, a stirring device 22, a temperature sensor 23, a liquid inlet 24, a hydrogen donor inlet 25, an inert gas supply pipe 26, and A liquid discharge pipe 27 is used.

  In the batch-type activity inspection, an inert gas is supplied into the inspection container 20 from the inert gas supply pipe 26 and replaced with air, and then a predetermined amount of the alkali metal dispersant to be inspected and the organochlorine compound are liquid-injected. Injecting from the inlet 24, stirring with the stirring device 22, and further, the temperature when dropping a hydrogen donor such as alcohol from the hydrogen donor inlet 25 is measured with the temperature sensor 23.

  The presence or absence of the activity of the sodium dispersant is determined by the maximum temperature change with time obtained by the temperature sensor 23. The maximum temperature of the mixed liquid due to the reaction depends on the concentration of the organochlorine compound and has a relationship as shown in FIG. 4. However, the temperature of the mixed liquid, the stirring speed, the shape and material of the cuvette 20, the heat dissipation characteristics, etc. Depending on the conditions, the maximum temperature and the time to reach the maximum temperature are different. For this reason, it is desirable to carry out a preliminary test to grasp the inspection conditions under which the concentration of organic chlorine remaining in the reaction solution falls within a desired range and the temperature change over time. Specific examples of the activity test are shown below.

  In a test container, 5 g of a sodium dispersant immediately after production having a sodium concentration of 10% by mass and 5 g of PCB oil diluted to 5% by mass with mineral oil were charged, and a hydrogen donor was gradually added dropwise while stirring to react. The temperature was measured. As a result, dechlorination reaction occurred and a rapid temperature increase was observed, reaching about 110 ° C. On the other hand, as a result of inspecting the sodium dispersant after standing for about 4 months used for the flow-type inspection under the same conditions, no rapid temperature increase was observed, and a decrease in activity could be clearly determined.

  In this embodiment, the case where the sodium dispersant and the PCB mixed oil are injected into the inspection container in advance is shown. However, the PCB mixed oil to which the alcohol is added after the injection of the sodium dispersant to be inspected is dropped or the alcohol is added. Even if the sodium dispersant is added dropwise after injecting the PCB mixed oil to which is added, the activity can be tested.

(Recovery of activity)
An example of the structure of an apparatus for recovering the activity of the alkali metal dispersant is shown in FIG. The regenerator of the present embodiment is one in which a liquid feed pump 41, a heater 42, a dispersing device 43, and a cooler 44 are connected to a storage tank 40 of an alkali metal dispersant as a redispersing device system by piping.

  The storage tank 40 is for storing the manufactured sodium dispersant, and includes a stirring function during storage and a storage container that also serves as a transfer container assuming that the manufacturing site and the usage location are different. When the present invention is applied, if the reservoir 40 is equipped with an inert gas adjustment system and an alkali metal dispersant inlet and outlet, no special modification is required. As the dispersion device 43, any dispersion method that is normally used can be used. For example, a Cowles blade high-speed rotation system, a homomixer system, a pressure homogenizer system, and an ultrasonic homogenizer system can be used. Further, as the liquid feed pump 41, it is preferable to use a tube pump or a leak tight pump that can be heated to a melting point or higher of the alkali metal, for example, where the alkali metal dispersant does not easily block. The heater 42 is not particularly limited as long as it can be heated to the melting point of the alkali metal or higher. Further, the cooler 44 may be any type as long as it can cool to the melting point of the alkali metal or less, and the type is not limited. If these devices are unitized and made portable, they can be transported together with the storage tank 40 and can be used at the place where the alkali metal dispersant is used, so the convenience is greatly improved.

  The recovery of activity can be performed using an apparatus for producing an alkali metal dispersant. This embodiment will be described with reference to FIG.

  FIG. 6 shows an alkali metal dispersant production apparatus / regeneration apparatus in which an alkali metal dispersant injection unit 51 with reduced activity is connected to a dispersion apparatus in the alkali metal dispersant production apparatus 50. The alkali metal dispersant having a lowered activity is injected after being heated to the melting temperature of the alkali metal or higher.

  The alkali metal dispersant production apparatus 50 is a general one, and a dispersion medium such as mineral oil is added to a dispersion apparatus provided with the above-described Cowles blade high-speed rotation system, homomixer system, pressure homogenizer system, ultrasonic homogenizer system, and the like. Then, an alkali metal dispersant is produced by filling the heated and melted alkali metal. The dispersed alkali metal dispersant is cooled to a temperature below the melting point of the alkali metal by a cooler. Further, the concentration and particle size distribution of the dispersant are measured by a concentration / particle size distribution measuring apparatus. Once the desired dispersion concentration and particle size are obtained, they are stored in storage and transport containers until used for the dechlorination reaction of organochlorine compounds.

  According to the apparatus of FIG. 6, reactivation can be performed only by allowing the alkali metal dispersant having reduced activity to be injected into the dispersion apparatus of the alkali metal dispersant production apparatus 50 without providing a new dispersion apparatus. it can. This eliminates the need for new capital investment for regeneration.

  The activity of the sodium dispersant, which had been allowed to stand for about 4 months after production in which a decrease in activity was observed in Example 1, was recovered by the method shown in FIG. The dispersing device 43 was an ultrasonic homogenizer system.

  In the activity recovery operation, a sodium dispersant was injected into the storage tank 40, and the heater 42 was controlled at 110 ° C., and the dispersion apparatus 43 was circulated for about 2 hours. After this regeneration operation, an activity test was performed using the flow-type activity test apparatus shown in Example 1.

  The activity test results are shown in FIG. 7 in comparison with those before regeneration. In the sodium dispersant which was allowed to stand for about 4 months after the production before the regeneration, no temperature increase was observed due to the reaction with the PCB mixed oil, but after the regeneration, the maximum temperature recovered to 90 ° C. with a residence time of 30 seconds.

  In the above-described embodiment, PCB oil is used as the organic chlorine compound, but the same inspection can be performed even if it is substituted with trichlorobenzene or the like.

  According to the present invention, the activity of an alkali metal dispersant can be inspected by a simple method. In addition, it has become possible to reactivate those whose activity has decreased due to prolonged standing or the like. Since the present invention is a very simple method, its utility value is very large.

1 is a schematic view of an alkali metal dispersant activity inspection apparatus according to an embodiment of the present invention. Explanatory drawing of temperature distribution when an alkali metal dispersant is tested for activity. The schematic of the alkali metal dispersing agent activity test | inspection apparatus by the other Example of this invention. Explanatory drawing which shows the relationship between an organic chlorine compound density | concentration and liquid mixture temperature. The schematic of the apparatus which reactivates the alkali metal dispersing agent with which activity fell. Schematic which shows one Example of an alkali metal dispersing agent manufacturing apparatus and reproduction | regeneration apparatus. Explanatory drawing which showed the temperature distribution when reproducing | regenerating the alkali metal dispersing agent in which activity fell compared with the temperature distribution when not performing a regeneration process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Container, 2 ... Container, 3 ... Pump, 4 ... Pump, 5 ... Activity test tube, 6 ... Temperature sensor, 7 ... Collection container, 20 ... Test container, 21 ... Mixed liquid of alkali metal dispersant and organochlorine compound 22 ... Stirrer, 23 ... Temperature sensor, 24 ... Liquid inlet, 25 ... Hydrogen donor inlet, 26 ... Inert gas supply pipe, 27 ... Discharge pipe, 40 ... Storage tank, 41 ... Liquid feed pump, 42 ... Heater, 43 ... dispersing device, 44 ... cooler, 50 ... alkali metal dispersant producing device, 51 ... injecting section.

Claims (5)

  The activity of an alkali metal dispersant characterized by reacting an alkali metal dispersant in the presence of an organic chlorine compound and a hydrogen donor and determining the presence or absence of the activity of the alkali metal dispersant from the magnitude of the temperature change caused by the reaction. Inspection method.   Changes in the temperature of the fluid accompanying the reaction, with the mixture of the organochlorine compound and hydrogen donor, and the alkali metal dispersant, flowing from one end of the tubular reaction tube until they flow out from the other end. And determining the presence or absence of the activity of the alkali metal dispersant from the distance that the fluid has flowed to reach the maximum temperature after flowing into the reaction tube.   The presence or absence of the activity of the alkali metal dispersant from the temperature change caused by the reaction and the time required to reach the maximum temperature by reacting the hydrogen donor dropwise in the mixture of the alkali metal dispersant and the organic chlorine compound. Determining the activity of an alkali metal dispersant.   A tubular reaction tube having an inlet of an alkali metal dispersant and an inlet of a mixed solution of an organic chlorine compound and a hydrogen donor at one end; and a tubular reaction tube which can be merged therein; the surface temperature of the tubular reaction tube and the interior of the tubular reaction tube And a temperature measuring device for measuring at least one of the temperatures of the fluid flowing through the alkali metal dispersant activity test apparatus.   A test container for containing a mixed liquid of an alkali metal dispersant and an organic chlorine compound, a hydrogen donor dropping device for dropping a hydrogen donor into the mixed liquid in the test container, and measuring the temperature of the liquid in the test container And an alkali metal dispersant activity test apparatus.

Images