KR100737832B1 - Recycling apparatus for extract water in methyl-amine plant - Google Patents

Abstract

The present invention relates to an extraction wastewater recycling apparatus of a methylamine plant, which is newly supplied after filtering some of the extraction wastewater discharged from the distillation column for separating monomethylamine (MMA) and dimethylamine (DMA) to remove foreign substances. It can be re-supplied to the distillation column where monomethylamine and dimethylamine are absorbed (extracted) together with the extracted water, thereby improving the process efficiency according to the recycling of the extracted wastewater, reducing the load on the wastewater treatment plant and reducing the wastewater treatment cost. And an extraction wastewater recycling apparatus of a methylamine plant that provides several advantages, such as reducing the amount of pure water supplied as extract water.

In addition, according to the present invention, by installing a filtering device for filtering various foreign matter in the extraction wastewater in the pipe line to extract the wastewater for reuse, it is possible to prevent the methanol from being excessively supplied by the extraction wastewater In addition, by blocking the concentration of methanol in the process and the accumulation of foreign matter there is an effect that can prevent the instability and reduced efficiency of the distillation column.

Methylamine, Extracted Water, Recycling, Distillation Column, Filter

Description

Recycling apparatus for extract water in methyl-amine plant

1 is a view showing a process facility after the distillation column in a conventional methylamine plant,

Figure 2 is a view showing a process facility after the distillation column in the methylamine plant to which the extraction wastewater recycling apparatus according to the present invention is applied.

<Explanation of symbols for the main parts of the drawings>

9: extraction water supply pipe 11: distillation column 2

12: distillation column 3 12a: extraction wastewater pipe

13: stripper 15, 16, 17: on-off valve

20: filtering device

20a: Extraction wastewater recovery piping (filter upstream piping)

20b: Extraction wastewater recovery piping (filter downstream piping)

21 filter 22 pure water supply

22a: pure water supply pipe 22b: discharge pipe

23, 24: on-off valve

The present invention relates to an extraction wastewater recycling apparatus of a methylamine plant, and more particularly, to filter out some of the extraction wastewater discharged from the distillation column for separating monomethylamine (MMA) and dimethylamine (DMA). After that, it can be re-supplied to the distillation column where monomethylamine and dimethylamine are absorbed (extracted) together with the newly supplied extract water, thereby improving process efficiency and reducing the load on the wastewater treatment plant and wastewater. The present invention relates to an extraction wastewater recycling apparatus for a methylamine plant, which provides several advantages, such as a reduction in treatment costs and a reduction in the amount of newly supplied pure water as extracted water.

In general, methylamine, which is widely used as a starting material for various solvents, pharmaceuticals, organic rubbers, surfactants and dyeing aids, consists of a mixture of monomethylamine (MMA), dimethylamine (DMA) and trimethylamine (TMA). The demand is mainly concentrated on dimethylamine, but the demand for monomethylamine and trimethylamine is gradually increasing with the market growth of related derivative products.

Typically, they are prepared by reacting methanol with ammonia in the gas phase at about 400 ° C. in the presence of a solid acid catalyst having dehydration and amination, such as γ-alumina, silica, silica-alumina and thoria. After that, the by-products are separated from the reaction product and then recovered and reused in the reaction system.

More specifically, when the raw material methanol (MeOH), ammonia solution (NH ₃ ), and recycled methylamine is supplied to the synthesis column through the raw material preheater and heat exchangers, methylamine is synthesized in the synthesis column, and the synthesized methyl The amine is a mixture of monomethylamine, dimethylamine, trimethylamine and unreacted materials, and then condensed and cooled through a heat exchanger and a cooler, and then purified into individual products through several distillation towers.

1 illustrates a process facility after a distillation column in a conventional methylamine plant, which will be described below.

After the reaction is carried out in the synthesis column, the mixture of monomethylamine, dimethylamine, trimethylamine and unreacted material is subjected to the above condensation and cooling, reheated in the distillation column 1 not shown, and then supplied to the distillation column 2 (1) shown in FIG. do.

Distillation column 2 (1) adds extract water (EW: Extct Water, PW: Pure Water) to separate trimethylamine (TMA), where trimethylamine (TMA) has a relatively low solubility in water. ) Is distilled off, and the remaining methylamines (MMA, DMA) are dissolved in extractive water (EW) and sent to the next stage of distillation column 3 (2).

In the distillation column 3 (2), monomethylamine (MMA) and dimethylamine (DMA) are distilled and recovered, and the extracted water is generated as wastewater and discharged to the bottom of the distillation column 3 (2).

Thus, the extraction wastewater generated in the manufacturing process of methylamine is water used as extraction water of methylamines, and the extraction wastewater discharged from the distillation column 3 (2) is mostly water, but not completely distilled methylamines (MMA, DMA, TMA) and some of the active ingredients such as unreacted methanol (MeOH) as a reaction raw material.

In the treatment of such extraction wastewater, all of the conventional wastewater treatment, but if the extraction wastewater is sent directly to the wastewater treatment plant, there is an unreasonable problem of increasing the load of the wastewater treatment plant, high wastewater treatment cost, and the disposal of active ingredients such as raw materials. .

Therefore, at present, the extraction wastewater from the distillation column 3 (2) is passed through a stripper 3 to separate and recover methylamines and active ingredients such as methanol, and the active ingredients are separated while passing through the stripper 3. The remaining liquid is sent to the wastewater treatment plant for wastewater treatment.

The stripper 3 separates and recovers the active ingredient, which is a low boiling point organic substance, from the methylamine extraction wastewater sent from the distillation column 3 (2) using a direct steam method. Because of the large difference, most are distilled and recovered.

The active ingredient separated and recovered while passing through the stripper 3 is condensed by cooling water in the heat exchanger 4 and then recovered by methylamine synthesis process, and recycled methyl consisting of monomethylamine, dimethylamine and trimethylamine. After mixing with the amine and reused as a raw material used in the production of methylamine, the remaining liquid separated from the active ingredient in the stripper (3) is discharged through the bottom of the stripper (3) and sent to the waste water treatment plant.

However, in the conventional methylamine plant process equipment made as described above, since all of the extraction wastewater separated from the distillation column 3 (2) and the active ingredient separated from the stripper 3 is discharged to the wastewater treatment plant, a considerable amount of the extraction wastewater is continuously discharged. As it was sent to the wastewater treatment plant, the load of the wastewater treatment plant was excessively increased, and the wastewater treatment cost was increased.

Therefore, the present invention was invented to solve the above problems, and after filtering some of the extraction wastewater discharged from the distillation column for separating monomethylamine (MMA) and dimethylamine (DMA) to remove foreign substances. It is configured to be re-supplied to the distillation column where monomethylamine and dimethylamine are absorbed (extracted) together with the extracted extract water, thereby improving the process efficiency by reducing the extraction wastewater, reducing the load of the wastewater treatment plant and wastewater treatment cost. The purpose is to provide an extraction wastewater recycling apparatus for a methylamine plant that offers several advantages, such as reducing the amount of water and reducing the amount of fresh water supplied as extractant.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

In the present invention, when a mixture of methylamines (MMA, DMA, TMA) and unreacted substances synthesized from the reaction raw materials is introduced, trimethylamine (TMA) is distilled and separated therefrom, and the remaining methylamines and unreacted substances are absorbed into the extract water. Into the methylamine plant comprising a distillation column 2 to be discharged, and distillation column 3 in which the extracted water discharged from the distillation column 2 comes in. Monomethylamine (MMA) and dimethylamine (DMA) are distilled and separated, and the remaining extraction wastewater is discharged. book,

Extraction wastewater recovery pipe for recovering part of the extraction wastewater discharged from the distillation tower 3 to the distillation tower 2 between an extraction wastewater pipe through which the extraction wastewater is discharged from the distillation column 3 and an extraction water supply pipe through which new extraction water is supplied to the distillation tower 2. The connection is installed, characterized in that the filtering device comprising a filter for filtering the methanol (MeOH) and various foreign substances from the extracted wastewater recovered on the extraction wastewater pipe is installed.

In particular, the filter of the filtering device is characterized in that the sand filter is filled with sand particles as a filtering means in the filter housing.

The filtering device may further include a backwashing device unit for back flushing the filtering means of the filter in a state in which an on / off valve installed in the upstream pipe and the downstream pipe of the filter is locked.

Here, the backwashing device unit, a pure water supply unit capable of supplying pure water, a pure water supply pipe connected between the pure water supply unit and the filter downstream pipe so that the pure water for backwashing can be supplied, and the filter station It characterized in that it comprises a discharge pipe installed in the filter upstream pipe and the on-off valve installed in the pure water supply pipe and the discharge pipe so that the water passed after the cleaning is discharged.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

The present invention relates to an extraction wastewater recycling apparatus of a methylamine plant, and recovers and filters some of the extraction wastewater sent to the stripper from the distillation column, and then mixes the filtered portion of the extraction wastewater with the newly supplied extraction water. The present invention relates to an extraction wastewater recycling apparatus of a methylamine plant, which is configured to provide a distillation column of the previous stage, that is, a distillation column in which absorption (extraction) of monomethylamine and dimethylamine is performed.

According to the present invention, it is possible to reduce the amount of extract water newly supplied to the distillation column while recycling a part of the extraction wastewater that has been conventionally treated with the total amount of wastewater (water saving), reducing the load of the wastewater treatment plant and reducing the cost of wastewater treatment Can be provided.

FIG. 2 is a view illustrating a process facility after a distillation column in a methylamine plant to which an extraction wastewater recycling apparatus according to the present invention is applied, and roles of the distillation tower 2 (11), the distillation tower 3 (12), and the stripper 13 are the same as in the related art. However, the process of separating the methylamine and the extraction wastewater through these facilities has been described in detail above, the description of the same components as in the conventional methylamine plant will be omitted.

First, in the present invention, a part of the extraction wastewater (extracting wastewater sent to the stripper from the distillation column 3) generated in the distillation column, that is, distillation column 3 (12) and discharged to the bottom thereof, is extracted from the extract water. Distillation column 3 (12) was connected to the stripper 13 to be supplied to the distillation column of the previous stage, that is, the absorption (extraction) of monomethylamine and dimethylamine, again as water. A portion of the extraction wastewater is recovered between the extraction wastewater pipe (12a) through which the extraction wastewater generated in the flow through (12a) and the extraction water supply pipe (9) to which the new extraction water is supplied to the distillation tower 2 (11). Connect piping 20a, 20b.

In addition, a filtering device 20 for filtering methanol (MeOH) and various foreign substances from the extraction wastewater is installed in the middle of the extraction wastewater recovery pipe 20a, 20b.

The filtering device 20 is configured to include a filter 21 installed in the middle of the extraction wastewater recovery pipe (20a, 20b) to pass the extraction wastewater, in the preferred embodiment the filter 21 is a non-fixed pores A sand filter which is a filter may be used.

The sand filter refers to a sand particle 21b filled as a filtering means in the filter housing 21a. When the sand filter is used, the sand filter is extracted into the upper portion of the filter housing 21a through the extraction wastewater return pipe 20a. As the wastewater passes through the sand particles 21b filled in the filter housing 21a, methanol and various foreign substances are filtered by the sand particles, and then the filtered extraction wastewater from which the methanol and the foreign substances have been removed is lowered to the filter housing 21a. After being discharged, it can be supplied again through the extraction wastewater recovery pipe 20b.

As a result, the extraction wastewater recovery pipe 20a, 20b is branched from the extraction wastewater pipe 12a and connected to the inlet side of the filter 21, and the extraction water supply pipe at the outlet side of the filter 21. It becomes the pipe connected in the middle of (9).

In addition, the opening and closing valves 15, 16, and 17 for controlling the extraction wastewater flowing through the pipes are respectively provided in the pipe 20a on the upstream side of the filter and the pipe 20b on the downstream side of the filter in the extraction wastewater recovery pipe 20a, 20b. Are installed.

Also in a preferred embodiment, in order to enable continuous use of the filter without replacing the filtering means inside the filter 21, for example, sand particles 21b, and to reduce particle unloading that may occur when used for a long time, The filtering device 20 preferably further includes a separate backwashing device for back flushing the filtering means of the filter after a certain time of use.

To this end, it is configured to be used only during backwashing of the filtering means, and includes a pure water supply unit 22 capable of supplying pure water (PW), and the pure water supplied by the pure water supply unit 22 is the filter. (21) Install a pure water supply pipe (22a) connected between the pure water supply unit 22 and the downstream filter side so that the downstream side can be supplied, and the filter upstream side discharges the foreign substances filtered along with the filter backwashing and discharged with water Connect the pipe (22b).

In addition, the pure water supply pipe 22a and the discharge pipe 22b are provided with on and off valves 23 and 24, respectively, and these on and off valves 23 and 24 are normally provided to be opened only during backwashing.

The pure water supply pipe 22a may be connected to the filter downstream pipe 20b connected to the lower end of the filter housing 21a or may be connected to an inlet installed separately, and the discharge pipe 22b may be a filter connected to the upper end of the filter housing 21a. It may be connected to the upstream pipe 20a or to a separate outlet.

In addition, since the pure water supplied by the pure water supply unit 22 at the time of back washing should flow back only to the filter 21, the upstream pipe 20a so that pure water does not flow into the filter upstream pipe 20a and the downstream pipe 20b. Valves 15, 16, and 17 are installed in the pipe 20b and downstream pipes, and these valves 15, 16, and 17 should be locked during backwashing.

Hereinafter, the operational effects according to the present invention will be described.

Monomethylamine, dimethylamine, trimethylamine and unreacted materials are then reheated in distillation tower 1, not shown, and then fed to distillation tower 2 (11) shown in FIG.

Distillation column 2 (11) is supplied with extract water in which monomethylamine and dimethylamine are absorbed in order to separate trimethylamine (TMA), and this extractor is combined with fresh pure water provided from an external supply. The extracted wastewater which has been recovered and filtered by the water is provided and used.

That is, a predetermined amount of the extraction wastewater from the extraction wastewater from the distillation column 3 (12) is opened while a proper amount of the opening / closing valves 15, 16, and 17 of the filter upstream pipe 20a and the downstream pipe 20b is opened. Passed through (21) is recovered through the extraction wastewater recovery pipe (20a, 20b), wherein the extracted wastewater is provided to the extraction water supply pipe (9) while the methanol and various foreign substances filtered through the filter 21 As a result, it is re-supplied to the distillation column 2 (11) together with the freshly supplied extraction water (pure water).

As such, the extraction wastewater discharged from the distillation tower 3 (12) is filtered and then recovered and reused in the distillation tower 2 (11), thereby improving process efficiency according to wastewater recycling, and of the extraction wastewater discharged through the stripper 13. Since the amount can be reduced, there is an effect of reducing the load of the wastewater treatment plant and reducing the cost of wastewater treatment, and also reducing the amount of newly supplied extract water, that is, the amount of pure water.

As described above, when pure water and filtered extraction wastewater are supplied to the distillation tower 2 (11), trimethylamine (TMA) having a relatively low solubility in water is distilled off, and the remaining methylamines (MMA, DMA) are distilled out. ) Is dissolved in extractive water (EW) and sent to distillation column 3 (12) of the next stage.

In the distillation column 3 (12), monomethylamine (MMA) and dimethylamine (DMA) are distilled and recovered. At this time, the extraction wastewater is generated and discharged to the bottom of the distillation column 3 (12), and then sent to the stripper (13).

Then, a part of the extraction wastewater sent to the stripper 13 after exiting the distillation tower 3 (12) passes through the filter 21 through the extraction wastewater recovery pipes 20a and 20b as described above, and then again distillation tower 2 ( 11) and reused as extraction water.

In the present invention, the filter 21 plays an important role of filtering methanol (MeOH) and various foreign matters in the extracted wastewater to be recovered. If the filter is not installed, problems of MeOH concentration and foreign matter accumulation in the distillation column 2 (11) occur. This puts a strain on the safety of the distillation column operation.

That is, foreign substances in the extraction wastewater discharged from the distillation column 3 (12) include methanol (MeOH), which is unreacted raw material, and rust generated from carbon steel materials such as tanks and pipes. If methanol and foreign substances are provided to the distillation column 2 (11) as it is, the concentrated methanol acts as a significant burden for stabilizing the process in the distillation column, and foreign substances such as rust are also deposited on the trays in the distillation column, thereby distilling efficiency. Greatly decreases.

Due to the nature of chemical plants that perform regular maintenance within 18 months or 24 months, it is a factor that greatly reduces the process efficiency if the foreign substances in the distillation column are not cleaned for a long time without a filter installed.

Therefore, only unreacted methanol and foreign substances contained in the extraction wastewater must be removed through the filter 21 to prevent methanol concentration and foreign matter accumulation in the process, and to prevent instability and deterioration of the distillation column 2 (11). can do.

On the other hand, in order to remove the foreign matter and the like filtered in the filter 21, the pure water can be supplied to the filter 21 in the reverse direction for cleaning, the filter upstream pipe 20a and the downstream pipe 20b for this filter backwashing. The on / off valves 15, 16, and 17 of the valves, all of the on / off valves 23 and 24 of the pure water supply pipe 22a and the discharge pipe 22b are opened, and then pure water is supplied through the pure water supply unit 22. do.

At this time, as the pure water passes back into the filter 21, the sand particles 21b are washed, and the washed foreign substances are discharged through the discharge pipe 22b together with the water, and the water discharged during the backwashing process is treated with wastewater. .

Thus, according to the present invention, after filtering some of the extraction wastewater discharged from the distillation column for separating monomethylamine and dimethylamine through a filter, the absorption of monomethylamine and dimethylamine together with the newly supplied extract water By being able to be re-supplied to the distillation column is made, a number of advantages are provided, such as reducing the load of the wastewater treatment plant, reducing the cost of wastewater treatment, reducing the amount of pure water supplied as extracted water, improving the process efficiency.

On the other hand, when the extraction wastewater from the distillation column 3 was filtered through a sand filter and reused in the distillation column 2, it was examined by examining whether the methanol (MeOH) in the extract water is concentrated by circulating the extraction wastewater. Even when recycled to the distillation column 2, it was found that the methanol in the extract water was not increased by the sand filter installed in the extraction wastewater recovery pipe.

In the process of checking, a predetermined amount of the extracted wastewater from distilled water 3 was taken, and the amount of methanol in the extracted wastewater was measured at various times and periodically measured during a predetermined test run. The results are shown in Table 1 below.

As can be seen in Table 1, even if the recovered wastewater is recovered and reused, the amount of methanol in the extracted wastewater does not increase significantly and remains at a certain level. By passing through, it was found that the extraction wastewater can be reused stably, and confirmed that there is no problem in the reuse of the extraction wastewater.

As described above, according to the extraction wastewater recycling apparatus of the methylamine plant according to the present invention, the extraction is newly supplied after filtering some of the extraction wastewater discharged from the distillation column for separating monomethylamine and dimethylamine through a filter It can be re-supplied to distillation column where monomethylamine and dimethylamine are absorbed together with water, thereby reducing the load on the wastewater treatment plant, reducing the cost of wastewater treatment, reducing the amount of pure water supplied as extracted water, and improving process efficiency. Several advantages are provided.

In particular, by installing a filtering device for filtering various foreign matters in the extraction wastewater in the pipe line where the extraction wastewater is recovered for reuse, it is possible to prevent the oversupply of methanol by the extraction wastewater, and to concentrate the methanol in the process and the foreign matters. By blocking accumulation, it is possible to prevent instability and deterioration of the distillation column.

Claims (4)

When a mixture of methylamines (MMA, DMA, TMA) and unreacted materials synthesized from the reaction raw materials comes in, trimethylamine (TMA) is distilled and separated therefrom, and the remaining methylamines and unreacted substances are absorbed in the extract water and discharged. And, in the methylamine plant comprising a distillation column 3, when the extracted water discharged from the distillation column 2, monomethylamine (MMA) and dimethylamine (DMA) is distilled and separated and the remaining extraction waste water is discharged. Extraction wastewater recovery pipe for recovering part of the extraction wastewater discharged from the distillation tower 3 to the distillation tower 2 between an extraction wastewater pipe through which the extraction wastewater is discharged from the distillation column 3 and an extraction water supply pipe through which new extraction water is supplied to the distillation tower 2. The connection wastewater recycling apparatus for methylamine plant, characterized in that a filtering device is installed on the extraction wastewater recovery pipe including a filter for filtering methanol (MeOH) and various foreign matters from the extracted wastewater. The method according to claim 1, The filter of the filtering device is an extraction wastewater recycling apparatus of a methylamine plant, characterized in that the sand filter is filled with sand particles as a filtering means in the filter housing. The method according to claim 1 or 2, The filtering device further includes a methyl amine plant for back flushing the filtering means of the filter in a state in which an on / off valve installed at an upstream pipe and a downstream pipe of the filter is locked. Extraction wastewater recycling unit. The method according to claim 3, The backwashing unit may include: a pure water supply unit capable of supplying pure water; a pure water supply pipe connected between the pure water supply unit and the downstream pipe of the filter so that pure water for backwashing may be supplied; Extraction wastewater recycling apparatus for a methylamine plant, characterized in that it comprises a discharge pipe installed in the filter upstream pipe and the on-off valve installed in the pure water supply pipe and the discharge pipe so that the water passed through.

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