KR100545094B1 - Method for cleaning the distilation tower with tar and ammonia water - Google Patents

Abstract

The present invention relates to a method for cleaning an ammonia distillation column that removes ammonia in the ordination generated when the high temperature coke oven gas discharged from the coke process is directly cooled. Supplying a washing liquid to the upper part of the distillation column, and supplying a washing liquid accumulated in the lower part of the distillation column to circulate the washing liquid, wherein the washing liquid is a mixture of a lipophilic substance and a hydrophilic substance. The dissolution of the pitch and the dissolution of the sludge proceed by dissolving and removing the deposit of the ammonia distillation column in the mixture of oily pitch and hydrophilic sludge. You can complete In addition, since the ammonia and tar content rates in the cleaning liquid are limited to 0.5 to 3% by mass and 1 to 40% by mass, respectively, the cleaning solution can be washed under conditions in which the cleaning solution dissolving power is maintained and the corrosion of the apparatus is alleviated.

Lipophilic substances, hydrophilic substances, ordination, tar

Description

Method for cleaning the distilation tower with tar and ammonia water}             

1 is a view showing a general ordination distillation process.

2 is an enlarged cross-sectional view of a tray in a distillation column.

3 is a process chart for removing ammonia from ordination.

<Description of the code for the main part of the drawing>

1: ammonia distillation column

2: Ordination Storage Tank

4: circulation pump

7: steam supply piping

10: Tar Storage Tank

11: tar pump

12: Tar charging line

30: tray

31 tray body

34: bubble cap

The present invention relates to a method of washing a distillation column for distilling ammonia (NH ₃ ) in ordination, ie, ammonia water, generated when the high temperature coke oven gas (COG) discharged from the coke oven is directly cooled. The present invention relates to a method for cleaning an ammonia distillation column using a cleaning liquid in which a substance and a lipophilic substance are mixed.

In general, large amounts of sludge containing tar powder and inorganic substances are mixed in the ordinal water. Therefore, if the operation for removing ammonia in the ordinal water is continued for a long time, the pitch and sludge from the tar powder are piled up on the bottom of the tray of the distillation column. And the amount increases. Increasing the deposits in the distillation column increases the pressure loss of the gas passing through the distillation column, so that the operation is not performed smoothly.

In this state, the operation must be stopped to clean the ammonia distillation column. That is, according to the conventional embodiment, the operator stops the operation, opens the distillation column 1, and disassembles each stage, and the worker artificially dismantles the pitches and sludges attached to the tray 30 and the bubble cap 34. Open cleaning method is implemented to clean and remove. For reference, the ammonia distillation column has a bubble cap tray of 20 stages.

This open-cleaning method is expensive due to human cleaning of the distillation column, and there is a risk of safety accidents to workers, and a long-term work schedule is required. The problem of degradation is caused.

The present invention has been made to solve the conventional problems as described above, to provide a distillation column cleaning method for quickly dissolving the cleaning operation for the distillation column by quickly dissolving the pitch and sludge attached in the distillation column. Its purpose is to.

In order to achieve the above object, according to the present invention, a method for cleaning an ammonia distillation column to remove ammonia in the ordination generated when the high-temperature coke oven gas directly discharged from the coke process is to discharge the solution in the ammonia distillation column And a step of supplying a washing liquid to the upper part of the distillation column, and circulating the washing liquid by supplying the washing liquid accumulated in the lower part of the distillation column to the upper part of the distillation column, wherein the washing liquid is a mixture of a lipophilic material and a hydrophilic material. It is characterized by.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention.

In order to distill the ammonia in the ordination generated when cooling the high temperature coke oven gas discharged from the coke process, the ordination is supplied from the ordination storage tank 2 to the distillation tower 1 via the ordination supply pipe 5. In the distillation tower (1), ammonia distilled from the water by the steam flowing from the lower portion through the steam supply pipe (7) is discharged to the top of the distillation tower (1). As described above, in the distillation of the ordination, the components contained in the ordination accumulate in the distillation column 1.

Therefore, according to the present invention, in order to remove deposits in the distillation column, the washing liquid is supplied to the upper part of the ammonia distillation column 1 and flows down to the lower part. Then, the washing liquid accumulated at the bottom of the column flows back into the distillation column (1) via the circulation pipe (6) by the circulation pump (4).

By the circulation of such a washing | cleaning liquid, the deposit in the ammonia distillation tower 1 is dissolved and removed. As the washing liquid, a mixed liquid of a lipophilic substance and a hydrophilic substance is used, more preferably a mixed liquid of ordination and tar. In such a washing liquid, the concentration of Free-NH _{3 in} ordination is 10,000 to 30,000 ppm, and the tar content is about 1 to 40 mass%.

On the other hand, the deposit in the ammonia distillation column 1 contains a large amount of tar powder and a sludge mainly composed of an inorganic substance. In general, pitches are lipophilic and sludge is hydrophilic, and since the substance is a mixture of several substance components, the other components are not dissolved even when the distillation column is cleaned by using a cleaning solution that can dissolve only one component of the deposit. In the stage where the melting of the deposit proceeds, the complete cleaning process is not performed.

Therefore, the washing | cleaning liquid used when melt | dissolving such a deposit needs to have the property which can melt | dissolve and wash two or more other components.

According to the present invention, a mixed liquid of a lipophilic substance and a hydrophilic substance is used as a washing liquid, more preferably a mixed liquid of ordination and tar. That is, by using such a mixed solution as a washing liquid, tar dissolves lipophilic pitches, and ammonia (NH ₃ ) in the water of hydrophilic sludge dissolves.

Therefore, since the dissolution of the pitch and the dissolution of the sludge proceed at the same time, the deposit dissolving surface is considerably transformed to promote the dissolution of the deposit.

Example 1

In the first embodiment, the cleaning operation is performed along the tar storage tank 10, the tar supply pump 11, and the tar charging line 12. That is, after the operation is stopped and all the liquid in the distillation column is discharged, the tar pump 11 is started to charge a predetermined amount of tar into the lower part of the ammonia distillation column. Then, the ordinal pump 3 is started to supply a predetermined amount of ordinal water to the tray 30 at the top of the distillation column. Thereafter, the circulation pump 4 is started to perform a circulation operation of supplying the mixed liquid of ordination and tar accumulated in the lower part of the distillation column to the tray at the upper part of the distillation column.

Steam is supplied from the steam line (7) to heat the cleaning liquid to 50 ~ 90 ℃. The circulation of the cleaning liquid is continued while adjusting the amount of steam so that the cleaning liquid temperature reaches the above range.

After circulating the washing liquid for a predetermined time, the washing liquid is discharged through the circulating liquid discharge pipe 9, and the discharged washing liquid is supplied to the tar treatment facility.

On the other hand, when the temperature of the cleaning liquid is 90 ° C or more, the amount of evaporation of ammonia (Free-NH ₃ ) in the ordinal water increases, and the cleaning effect is rapidly lowered. When the temperature of the cleaning liquid is 50 ° C or less, the cleaning power is weakened.

Regarding the cleaning liquid composition, the ammonia (Free-NH ₃ ) concentration is in the range of 10,000 to 30,000 ppm, and the tar content rate is preferably maintained in the range of 1 to 40 mass%. If the ammonia (Free-NH ₃ ) content is less than 0.1 mass%, that is, 10,000 ppm or less as a concentration, the rate at which the cleaning liquid dissolves the sludge is slowed and the cleaning power to the deposit is weakened. If the content of ammonia (Free-NH ₃ ) exceeds 3.0% by mass, that is, 30,000 ppm, the corrosion of the cleaning liquid is strong, which is not good because the loss of equipment or piping is severe.

The cleaning liquid having a tar content of less than 1% by mass has a slow rate of dissolving pitches and a weak cleaning power of deposits. When the tar content in the cleaning liquid exceeds 40% by mass, the amount of ordination (ammonia content) decreases so that the sludge does not dissolve.

Tar mixed with ordination is preferably a coal-based tar containing a lot of aromatic hydrocarbons having a boiling point of 260 ° C. or less, for example, one or two benzene nuclei such as benzene, toluene, methylnaphthalene, diphenyl, and the like.

Example 2

The experiment which melt | dissolved the pitch powder attached to the tray of the ammonia distillation column was performed. In this experiment, tar of the composition shown in [Table 1] was added to 500 g of ordination (NH ₃ : 3 mass%, tar content: 0.05 mass%), respectively, to prepare three types of washing liquids. Next, the temperature of each washing liquid was set at 70 ° C., and the pitch was crushed to about 3 mm, and 200 g was added thereto while maintaining the temperature while stirring.

In parallel with the above experiments, a pitch powder dissolution test was performed using a washing solution of only ordination without tar. Then, the pitch that had been deposited was taken out and dried at 50 ° C. for 10 hours, and then the weight thereof was measured to determine the difference with the weight before deposition, and the difference was taken as the dissolved amount.

These results are shown in the following [Table 1]. When comparing the numerical values of the examples with the comparative examples with respect to the amount of dissolution of the pitch component, the data of 9 mass% of tar in the cleaning solution (No. There is more than 2 times difference and compared with the effect of tar was confirmed.

TABLE 1

No. Tar addition amount (g) Tar content rate (mass%) in washing liquid Pitch Melt Amount (g) One 50 9 27 2 150 23 41 3 250 33 43 Comparative Example 1 0 One 12

Example 3

The ratio of tar to ordination (NH ₃ : 3% by mass, tar content: 0.05% by mass) in the washing solution used in this example was mixed at 9: 1. The cleaning solution was circulated while controlling the steam flow rate so that the cleaning solution temperature was maintained at 70 ° C, and cleaning was performed for 48 hours. Therefore, the cleaning effect was confirmed by comparing the pressure loss of the ammonia distillation column during operation and the pressure loss after washing. And the cleaning by the washing | cleaning liquid which did not add tar was also performed for the comparison.

In this example, the conditions other than the cleaning liquid composition were maintained in the same manner as the above experiment. The results are shown in the following [Table 2]. Looking at the pressure loss of the examples and the comparative example, it can be seen that in the comparative example, the pressure loss was about 300 mmH ₂ O higher than the difference between the examples and the cleaning was insufficient. Therefore, in the case of washing under the comparative example conditions, in order to wash the same degree as in the case of Example, the result of having to continue washing for a long time was obtained.

TABLE 2

division Pressure loss (mmH ₂ O) Before cleaning After cleaning Example 2 1500-1600 800 to 1000 Comparative Example 2 1500-1600 1300

Therefore, according to the present invention, since the mixed solution of ordination and tar is used as the washing liquid, it is possible to dissolve both the lipophilic substance and the hydrophilic substance. Thus, the deposit of the ammonia distillation column containing the lipophilic pitch and the hydrophilic sludge mixture is removed. The dissolution of the pitch and the sludge dissolving and dissolving proceed at the same time so that the deposit dissolving surface is considerably transformed, the dissolution of the deposit is promoted, and the cleaning can be completed in a short time.

The foregoing is merely illustrative of the preferred embodiments of the present invention and those skilled in the art to which the present invention pertains may make modifications and changes to the present invention without departing from the spirit and gist of the invention as set forth in the appended claims. It should be recognized.

Claims (6)

In the method of washing the ammonia distillation column to remove ammonia in the water generated when the high-temperature coke oven gas directly discharged from the coke process, Discharging the solution in the ammonia distillation column; Supplying a washing liquid to an upper portion of the distillation column; And circulating the washing liquid by supplying the washing liquid accumulated in the lower portion of the distillation column to the upper portion of the distillation column, The cleaning solution is ammonia distillation column cleaning method, characterized in that the mixture of lipophilic tar and hydrophilic water. The method of claim 1, And supplying steam through the lower portion of the distillation column while the washing liquid is circulated. The method of claim 2, The supply amount of the steam is ammonia distillation column cleaning method characterized in that it is adjusted to maintain the temperature of the cleaning liquid at 50 ~ 90 ℃. The method of claim 1, The washing liquid comprises 0.5 to 3% by mass of ammonia (Free-NH ₃ ) and 1 to 40% by mass of tar, the ammonia distillation column washing method. The method of claim 1, The tar is an ammonia distillation column washing method characterized in that the boiling point is a coal-based tar containing a large number of aromatic hydrocarbons having one or two benzene cores selected from benzene, toluene, methylnaphthalene, diphenyl and the like having a boiling point of 260 ℃ or less. delete

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