KR100742956B1 - A METHOD FOR PREVENTING THE DEGRADATION OF ???Benzene.Toluene.Xylene ABSORPTION OIL IN COKE GAS REFINING PROCESS - Google Patents

Abstract

The present invention is to prevent the deterioration of the absorbent oil by absorbing and removing the material that deteriorates the absorbent oil in advance when using the absorbent oil to remove naphthalene contained in the coke gas in the refining process, the coke gas cooler Absorbs oil such as naphthalene and tar by absorbing oil into the naphthalene absorption tower located at the bottom, and absorbs oil such as BTX by absorbing oil into the BTX absorption tower into which coke gas flows from the naphthalene absorption tower. In the process of removing BTX from the distillation column into which the absorption oil from which the pitch is removed is introduced, and the BTX supplying the absorption oil to the BTX absorption tower to purify the coke gas, the naphthalene absorption tower is used for absorbing impurities. Blocking the valve member so that the absorbed oil does not flow into the BTX absorption tower; The naphthalene absorption tower is used for the impurity absorption operation so that the absorption oil containing a large amount of impurities can be separated and treated through the discharge line connecting the absorption circulation line of the naphthalene absorption tower and the de-pitching tower to the de-pitching tower. Supplied; The main point is to supply only the absorption oil collected in the BTX absorption tower through an orifice into the naphthalene absorption tower.

Absorption oil, gas cooler, naphthalene absorption tower, BTX absorption tower, distillation tower, de-pitching tower

Description

A METHOD FOR PREVENTING THE DEGRADATION OF ＢＴＸ (Benzene.Toluene.Xylene) ABSORPTION OIL IN COKE GAS REFINING PROCESS}

1 is a schematic view showing a general coke gas purification process,

2 is a schematic view showing a coke refining process employing a method for preventing the absorption of COT absorption in the coke gas purification according to the present invention;

Figure 3 is a graph showing the naphthalene absorption efficiency according to the change in naphthalene content in the absorption oil supplied to the naphthalene absorption tower.

Explanation of symbols on the main parts of the drawings

1 ..... gas cooler 2 ..... naphthalene absorption tower

4 ..... Circulation Pump 7 ..... BTX Absorption Tower

8 ..... heating furnace 9 ..... distillation column

10 ... Depitch Top 13 .... Orifice

15 ... control valve 19 .... valve member

The present invention is to improve the coke gas refining process to prevent the deterioration of the absorbent oil by absorbing and removing the material deteriorating the absorbent oil in advance when using the absorbent oil to remove naphthalene contained in the coke gas in the refining process. It relates to a method for preventing BTX absorption oil deterioration.

In general, naphthalene generated during the refining of the coke gas generated in steel mills causes the closure of various facilities and pipes when condensing, so the removal of naphthalene occupies a very important position during the refining process of the coke gas.

Currently, one of the methods for removing naphthalene from coke gas is to remove naphthalene by using absorbent oil. This is to reduce the amount of absorbent oil used and to avoid the complexity of the process, to absorb BTX (Benzene.Toluene.Xylene) absorbent oil. (Hereinafter referred to as BTX absorbent oil), and the used absorbent oil is mixed with the BTX absorbent oil again to be recycled, so that a large amount of impurities are introduced into the absorbent oil system in the naphthalene absorption tower to degrade the absorbent oil. It will play its main role.

Here, the BTX absorbent oil is an absorbent oil used to absorb BTX (benzene, toluene, xylene) components in the coke gas.

On the other hand, impurities are introduced from the naphthalene absorption tower as follows.

That is, as shown in Figure 1, the naphthalene absorption tower (2) is integrally disposed at the lower end of the gas cooler (1) in order to prevent clogging of the gas cooler (1) for cooling the coke gas, The gas cooler 1 absorbs much more material capable of deteriorating the absorbed oil than the BTX absorption tower 7 that meets coke gas in which some impurities are removed.

In particular, it absorbs a large amount of sulfuric acid solution that is present after the facility for absorbing and removing ammonia in sulfuric acid to play a critical role in absorbing oil degradation. In addition, it absorbs intene, which is a substance mainly causing polymerization in absorbent oil, and acts as a sulfur component in coke gas to promote polymerization of absorbent oil. In addition, it absorbs acenaphthene, tar and the like to further promote sludge production.

On the contrary, in this case, when the absorbent oil used in the naphthalene absorption tower 2 is disposed of without reuse, the naphthalene absorption tower 2 removes some of the substances absorbed by the absorbent oil and may cause deterioration. Since the coke gas can be supplied to the BTX absorption tower 7, it can be assumed that it can play a role in preventing the absorption oil degradation.

Next, a method of removing naphthalene from the gas cooler 1 of the general coke gas purification process will be described.

First, the gas cooler 1 and the naphthalene absorption tower 2 communicate with each other as hollow hollow towers, and in the gas cooler 1 by contacting the coke gas supplied from the bottom to the top by spraying cooling water from the top to the bottom. Allow the gas to cool. In addition, since the naphthalene absorption tower 2 is installed at the lower end of the gas cooler 1, the absorption tower 2 includes the gas flowing from the lower portion to the upper portion by injecting the absorbing oil from the upper portion to the lower portion. Try to absorb naphthalene.

Accordingly, the coke gas supplied to the lower portion of the naphthalene absorption tower 2 allows the naphthalene to be absorbed by the absorption oil circulated by the circulation pump 4 inside the absorption tower 2, and then the cooler 1. It goes up to) and comes in contact with coolant to cool.

Here, the absorption oil used in the naphthalene absorption tower (2) is a portion of the absorption oil used for absorption of benzol in the BTX absorption tower (7) of the circulation pump (5) connected to the lower end of the BTX absorption tower (7) The naphthalene absorption tower (2) is circulated through the distribution pipe (5a), and the absorbent oil discharged from the naphthalene absorption tower (2) is returned to the original benzene conversion oil pipe. In this way, naphthalene is continuously absorbed and treated.

In the gas cooler 1, the gas is cooled in contact with the circulated cooling water, and the condensed water condensed therein is passed through a distillation process as waste water and then sent to a wastewater treatment process. The problem with the naphthalene absorption tower (2) during this process is that the absorbent oil supplied to the absorption tower (2) is in contact with the coke gas from which impurities are not removed in front of the gas purification process. Since a large amount of impurities are absorbed and the absorbent oil in the naphthalene absorption tower 2 flows back into the BTX absorption tower 7 and is mixed with the absorbed oil contained therein, it acts to contaminate the entire absorbent oil, thereby degrading absorbed oil. It is a major cause.

Means for maintaining the quality of the absorbent oil in such a process is to remove the pitch or sludge component generated in the absorbent oil, which is mounted at the bottom of the distillation column 9 for distilling the absorbent oil supplied through the heating furnace 8. Absorbent oil is circulated and supplied to the BTX absorption tower 7 as the absorption oil circulating pump 6, and a part of the reused absorption oil is sent to the depitching tower 10 to recover the absorption oil component, and the remaining pitch is mixed with tar. External discharge, and the upper portion of the distillation column (9) is made of BTX recovery.

However, this method is so deterioration of the absorbent oil is too fast, because the sludge component is not effectively discharged in the absorbent oil sent to the de-pitching tower 10, its utility is not effective so much, and only the waste oil is discarded. The role as a passage became the main role.

Therefore, the present invention has been proposed to solve the conventional problems as described above, the object of which is that the absorbent oil used when the absorbent oil is used in the naphthalene removal process is originally mixed with the absorbent oil for BTX absorption deteriorates the entire absorbent oil system To prevent and, furthermore, to provide a method for preventing deterioration of BTX absorption oil in the coke gas purification that can remove impurities in advance in the naphthalene absorption tower.

As a technical configuration for achieving the above object, the present invention,

Absorbs oil into the naphthalene absorption tower located at the bottom of the coke gas cooler to absorb impurities such as naphthalene and tar, and absorbs oil into the BTX absorption tower into which coke gas flows from the naphthalene absorption tower to remove impurities such as BTX. In the process of absorbing and removing the BTX in the distillation column in which the absorption oil is removed from the de-pitching column flows, BTX feeds the absorption oil to the BTX absorption tower to purify the coke gas,

Blocking the valve member so that the absorption oil used for the impurity absorption operation in the naphthalene absorption tower does not flow into the BTX absorption tower,

The naphthalene absorption tower is used for the impurity absorption operation so that the absorption oil containing a large amount of impurities can be separated and treated through the discharge line connecting the absorption circulation line of the naphthalene absorption tower and the de-pitching tower to the de-pitching tower. Supplied,

In the refining of coke gas, the absorption of deteriorated BTX absorption oil is provided by supplying only the absorption oil collected in the BTX absorption tower through an orifice into the naphthalene absorption tower.

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

Figure 2 is a schematic diagram showing a coke refining process employing a method for preventing carbon deterioration oil absorption in the coke gas purification according to the present invention, Figure 3 is a naphthalene absorption efficiency according to the change in the naphthalene content in the absorption oil supplied to the naphthalene absorption tower. Is a graph.

Absorbing oil is introduced into the upper part of the naphthalene absorption tower 2 integrally located at the lower end of the coke gas cooler 1 employing the method of the present invention to absorb impurities such as naphthalene and tar contained in the coke gas supplied from the bottom. Do it. At this time, the absorbent oil used is discharged from the lower part of the BTX absorption tower 7 which absorbs the BTX contained in the absorbent oil, and reuses the absorbent oil containing BTX.

Here, the absorbent oil supplied from the upper portion to the lower portion of the naphthalene absorption tower 2 absorbs various impurities that may degrade the absorbent oil from the coke gas, and the absorbent oil used in the operation of absorbing a large amount of impurities may be The BTX absorption tower, which is circulated by the absorption oil circulation line and the circulation pump of the naphthalene absorption tower 2 and used in the impurity absorption operation in the naphthalene absorption tower 2, contains a large amount of impurities, is conventionally used in the BTX absorption tower. (7) by closing the valve member 19 of the connection pipe connecting between the naphthalene absorption tower (2) and the BTX absorption tower (7) so as not to be introduced into it to block the supply flow of the absorbent oil.

Here, it is not necessary to provide a configuration of a supply line for supplying absorption oil from the naphthalene absorption tower 2 to the BTX absorption tower 7 side through a connecting pipe.

Subsequently, since the amount of absorbent oil supplied into the naphthalene absorption tower 2 is discarded after it is used for absorbing naphthalene in principle, the amount of supply absorbed in consideration of naphthalene absorption capacity, pipe blockage, etc. in order to minimize the loss of absorbent oil. Keep it to a minimum.

That is, the method of reducing the absorbed oil inflow must be reduced to very small amount by more than one-hundredth of the amount introduced in the conventional method, so that the flow rate of the small amount cannot be controlled by the simple opening / closing operation by the valve alone. Therefore, by using the orifice 13 together with the control valve 13a, the diameter of the existing pipe is reduced to 3 mm or less.

In this case, the orifice 13 has a diameter of 3 mm or less, and the amount of absorption oil supplied into the naphthalene absorption tower 2 supplied through the orifice 13 is preferably 0.0003 to 0.0014 kg per 1 Nm3 of coke gas.

This makes it possible to discard the waste after being used in the naphthalene absorption tower (2) without exceeding the amount previously discarded by a certain amount, and it is not used anywhere, and the discarded oil absorbs impurities in the coke gas to absorb impurities. Higher concentrations are discarded in a finite state, resulting in a more efficient process.

In the naphthalene absorption tower 2, the method of disposing the absorbent oil used to absorb the impurities contained in the coke gas is an absorption containing a large amount of impurities due to the absorption operation in the naphthalene absorption tower 2. In order to separate the oil, the entire amount of the naphthalene absorption tower 2 is supplied to the de-pitching tower 10 through a discharge line 16 connecting between the absorption circulation line and the de-pitching 10 tower. Accordingly, tar is removed together with the pitch included in the absorbent oil in the de-pitching tower 10, and the pitch and the tar removed from the absorbed oil supplied to the lower part are discharged to the outside, and the upper part is recovered. Absorbent oil, which is a useful component, is fed to the bottom of the distillation column (9).

The distillation column (9) continuously removes and collects the BTX contained in the absorption oil flowing from the de-pitching tower (10), and the remaining absorption oil passes through the gas cooler as a circulating pump (6). The absorption oil used to absorb impurities contained in the coke gas in the BTX absorption tower 7 is supplied to the upper portion of the BTX absorption tower 7, and the naphthalene absorption tower 2 is supplied through the orifice 13. ) Is supplied.

In this way, the absorbent oil including the deteriorated material absorbed by the naphthalene absorption tower 2 is not supplied back into the BTX absorption tower 7 and is not circulated to the naphthalene absorption tower 2, and the total amount depitching tower 10 is performed. Since it effectively removes the impurities absorbed and absorbed, the deterioration rate of the absorbent oil used in the naphthalene absorption tower 2 is reduced, thereby reducing the amount of absorbent oil used.

However, even if the deterioration of the absorbent oil is reduced, it is difficult to reduce the amount of disposal to a certain degree or less, because when the amount of absorbed oil discharged to a certain degree or less, the blockage of the piping of the absorbent oil circulation line and the blockage of the orifice 13 occur. . In such a process change, in order to maintain the oil level of the naphthalene absorption tower 2, the discharge amount of the absorption oil discharged to the de-pitching tower 10 using the automatic control valve 15 is supplied to the naphthalene absorption tower 2. Adjust according to the oil level.

In this process, even if the amount of absorbed oil supplied into the naphthalene absorption tower 2 is reduced to 1/100 or more, the problem remains that the naphthalene contained in the supplied coke gas can be properly absorbed and removed. This can be solved by keeping the naphthalene content contained in the absorption oil to be supplied and used in the naphthalene absorption tower 2 from the experimental results as shown in FIG. 3.

In other words, this experiment was conducted before the naphthalene absorption tower (2) with a naphthalene content of 5 g / Nm ³ in the coke gas.

When operating in this way, naphthalene contained in the coke gas is absorbed and treated in the naphthalene absorption tower (2), the absorption oil absorbed naphthalene is depitched column 10, distillation tower (9) and BTX absorption tower (7) Since naphthalene is removed during the process, the naphthalene content of the absorbent oil used in the naphthalene absorption tower 2 can be kept low at all times. Accordingly, in the present invention, even if the amount of absorption oil supplied into the naphthalene absorption tower 2 is reduced as compared with the conventional one, there is no problem in the absorption process of naphthalene contained in the coke gas.

By blocking the absorption of the absorption oil from the naphthalene absorption tower (2) to the BTX absorption tower (7) to reduce the inflow of impurities into the BTX absorption tower (7), which prevents the deterioration of the absorbent oil reused It will play a role.

The indene component is efficiently removed because it reacts with the sulfur component in the coke gas to cause polymerization, and also removes the sulfuric acid component to prevent polymerization of other absorbent oil components. In addition, since it serves to remove the acenaphthene contained in the coke gas or tar component having a large molecular weight that is not well treated in the pretreatment process, it serves to prevent the absorbent oil from deteriorating.

Existing de-pitching tower's role is to recover the absorbing oil as much as possible and completely discard the pitch before the absorbing oil is completely discarded, but the effect of this is proved to be insignificant since the deterioration rate of absorbing oil is very fast. .

However, the present invention plays a much more efficient role because it has a function of selecting and treating a substance that degrades the absorbent oil.

The height of the oil absorption surface of the bottom of the naphthalene absorption tower 2 is automatically measured and transmitted to the automatic control device, and automatically adjusted by adjusting the opening degree of the control valve 15 using the difference between the measured value and the set value. Be sure to

EXAMPLE

A coke gas having a flow rate of about 30000 Nm ³ / h is passed from the bottom of the tower having a diameter of 3 m, 10 m of naphthalene absorption tower 2, 16 m of gas cooler 1, and 26 m in total height to the top of the naphthalene absorption tower 2. The absorbed oil was circulated at 180 m ³ / h as the circulation pump 4, and the absorbed oil was supplied at 0.12 ton / h. The tower was a hollow spray tower, maintaining a temperature of 50 ° C.

The naphthalene content was 4% and the naphthalene content was 12% after passing through the naphthalene absorption tower 2 in the absorption oil supplied into the naphthalene absorption tower 2. The viscosity of the absorbent oil was maintained at 1.4 ° E when supplied to the naphthalene absorption tower, the viscosity of the absorbed oil discharged to 1.5 ° E.

Maintaining the viscosity of the absorbent oil supplied into the naphthalene absorption tower 2 at 1.4 ° E indicates that the viscosity is maintained well while consuming the absorbed oil in an amount of 0.12 ton / h.

On the other hand, the benzene content in the absorption oil supplied into the naphthalene absorption tower (2) and the absorption oil passing through the naphthalene absorption tower (2) was similarly maintained as about 1%. This shows that benzene hardly occurs absorption because the naphthalene absorption operation temperature is as high as 50 ° C.

Comparative Example 1

A coke gas having a flow rate of about 30000 Nm ³ / h is passed through a ³ m diameter, 10 m naphthalene absorption tower (2), 16 m gas cooler (1), and a total height of 26 m, and absorbed oil through the naphthalene absorption tower (2). It was circulated at 180 m ³ / h and the absorption oil feed amount was supplied at 20 ton / h. The naphthalene content was 7% and the naphthalene content was 7.5% after passing through the naphthalene absorption tower. The viscosity of the absorbent oil was 1.55 ° E when supplied to the naphthalene absorption tower 2, and the absorbed oil discharged was similarly maintained at 1.56 ° E.

At this time, the amount of absorbent oil discarded through the depitching tower 10 was maintained at 0.12 ton / h similar to the first embodiment. Here, however, the viscosity of the absorbent oil supplied is 1.55 ° E, which shows that the viscosity of the absorbent oil is not kept low compared to the embodiment according to the present invention, which means that the production of sludge proceeds faster.

In addition, since the absorption oil of the naphthalene absorption tower (2) which absorbed naphthalene is supplied to the BTX absorption tower (7) through the valve member (19) opened, and it continues to combine with the original absorption oil, the naphthalene absorption tower The content of naphthalene increased in the absorption oil used in (2). The benzene content in the absorbent oil supplied and the absorbent oil passed through the naphthalene absorption tower remained similar at around 1%. This shows that benzene hardly occurs because the naphthalene absorption operation temperature is as high as 50 ° C.

Comparative Example 2

A coke gas having a flow rate of about 30000 Nm ³ / h is passed through a tower having a diameter of 3 m, a 10 m naphthalene absorption tower (2), a 16 m gas cooler (1), and a total height of 26 m, and absorbing oil 180 m into the naphthalene absorption tower (2). ^It was circulated at ³ / h, the absorption oil feed amount was supplied at 0.1 ton / h. The tower was a hollow spray tower and maintained at a temperature of 50 ° C. At this time, the content of naphthalene in the absorption oil supplied into the naphthalene absorption tower (2) was 5%, the naphthalene content after passing through the naphthalene absorption tower (2) was 15%. In addition, when the viscosity of the absorbent oil was supplied to the naphthalene absorption tower 2, the viscosity of the absorbed oil discharged was maintained at 1.6 ° E.

This increased the viscosity of the absorbent oil supplied to 1.5 ° E compared with the first embodiment, which shows that the viscosity control of the absorbent oil is difficult when the absorbed oil is consumed in an amount of 0.1 ton / h. The increase in naphthalene content to 15% in the absorbed oil discharged indicates that the amount of absorbed oil supplied to the naphthalene absorption tower 2 decreases, so that naphthalene is accumulated in the absorbed oil. The benzene content in the absorbent oil supplied into the naphthalene absorption tower 2 and the absorbent oil passing through the naphthalene absorption tower 2 was similarly maintained as about 1%. This shows that benzene hardly occurs absorption because the naphthalene absorption operation temperature is as high as 50 ° C.

Comparative Example 3

A coke gas having a flow rate of about 30000 Nm 3 / h is passed through a 3 m diameter, 10 m naphthalene absorption tower (2), 16 m gas cooler (1), and a total height of 26 m, and absorbing oil 180 m into the naphthalene absorption tower (2). ^It was circulated at ³ / h, the absorption oil feed amount was supplied at 0.12ton / h. The tower was a hollow spray tower and maintained at a temperature of 50 ° C. At this time, however, it was located near the front of the coke refining process and operated without an electrostatic precipitator for removing fine tar particles from the coke gas, and the naphthalene content in the absorbed oil supplied was 4% and passed through the naphthalene absorption tower (2). Afterwards the naphthalene content was 10%. The viscosity of the absorbent oil was maintained in the same manner as in the first example when supplied to the naphthalene absorption tower (2), but the discharged absorbed oil showed a sharp viscosity increase due to the inflow of tar as the viscosity is 4 ° E. This shows that the development of sludge in the absorbent oil is rapidly increased by tar, and when the absorbent oil is mixed with the original absorbent oil system, it means that the absorbent oil deteriorates rapidly, so that the absorbent oil is degraded by the present invention. Another effect can be prevented.

In addition, the content of benzene in the absorbent oil supplied into the naphthalene absorption tower 2 and the absorbent oil passing through the naphthalene absorption tower () 2 was maintained at about 1%. This shows that benzene hardly occurs because the naphthalene absorption operation temperature is as high as 50 ° C.

Therefore, according to the present invention having the above-described configuration, by separating the absorbent oil used to absorb impurities in the naphthalene absorption tower and containing a large amount of impurities and removing them before being re-supplied into the naphthalene absorption tower, It is possible to drastically prevent deterioration of the absorbent oil and to reduce the amount of absorbed oil used in the naphthalene absorption tower to significantly reduce the total consumption of the absorbent oil as compared with the conventional art.

While the invention has been shown and described with respect to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit or scope of the invention as set forth in the claims below. I would like to clarify that knowledge is easy to know.

Claims (2)

Absorbs oil into the naphthalene absorption tower located at the bottom of the coke gas cooler to absorb impurities such as naphthalene and tar, and absorbs oil into the BTX absorption tower into which coke gas flows from the naphthalene absorption tower to remove impurities such as BTX. In the process of absorbing and removing the BTX in the distillation column in which the absorption oil is removed from the de-pitching column flows, BTX feeds the absorption oil to the BTX absorption tower to purify the coke gas, Blocking the valve member so that the absorption oil used for the impurity absorption operation in the naphthalene absorption tower does not flow into the BTX absorption tower, The naphthalene absorption tower is used for the impurity absorption operation so that the absorption oil containing a large amount of impurities can be separated and treated through the discharge line connecting the absorption circulation line of the naphthalene absorption tower and the de-pitching tower to the de-pitching tower. Supplied, The method for preventing deterioration of BTX absorption oil in the coke gas refining, wherein only absorption oil collected in the BTX absorption tower is supplied through the orifice into the naphthalene absorption tower. The method of claim 1, The orifice has an aperture of 3 mm or less, and the amount of absorption oil supplied into the naphthalene absorption tower 2 supplied through the orifice is 0.0003 to 0.0014 kg per 1 Nm3 of coke gas. How to prevent oil deterioration.

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