JP4069645B2 - How to remove dirt from heat exchangers - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention removes the internal fouling of the heating heat exchanger in the process of obtaining the object from the liquid containing the object and the heavy material while continuing the operation of the heat exchanger, and has a long-term heat exchange capability. On how to maintain.
[0002]
[Prior art]
The heating type heat exchanger is used for a distillation operation or the like for separating and purifying a target product from a liquid containing the target product and a heavy product. In this case, the dirt component of the heavy material adheres to the inside of the heat exchanger, and the heat transfer capacity of the heat exchanger decreases, so it is often necessary to stop the operation of the heat exchanger and remove the internal dirt. .
[0003]
As a method of removing dirt, the operation of the heat exchanger is temporarily stopped, the contents of the heat exchanger are taken out and the equipment is opened, and then the inside of the heat exchanger is washed with high-pressure water, buffed, mechanically cleaned A method for removing dirt by polishing or the like can be given. Such a method requires a great deal of labor, such as switching to a spare heat exchanger, opening the equipment and removing dirt, as well as ensuring the safety of the operation and the operational stability of the plant associated with the switching. Have problems.
[0004]
On the other hand, although the heat exchanger is stopped, there is also a method with a relatively small work amount in which the inside of the heat exchanger is cleaned with chemicals such as warm water and alkali without opening the equipment. However, this method has a problem in that dirt is not sufficiently removed, the heat exchange capacity is rapidly reduced after the operation is resumed, and the cleaning operation needs to be repeated frequently.
[0005]
[Problems to be solved by the invention]
Under such circumstances, the present invention provides a heat exchanger dirt removal method capable of maintaining the heat exchange capacity over a long period of time while continuing the operation without stopping the operation of the heating heat exchanger. The purpose is to do.
[0006]
[Means for Solving the Problems]
That is, the present invention is a liquid containing a target product and a heavy product, and is a chemical plant for separating and purifying a target product by distillation from a liquid containing dihydroxybenzenes and a heavy product obtained by decomposing aromatic peroxides. In the process, introducing the steam inside the heat exchanger while continuing the operation of the heat exchanger to remove the dirt based on the heavy material adhering to the inside of the heat exchanger that heats and evaporates the liquid containing the target product and the heavy material Is a heat exchanger dirt removal method that removes dirt, and is a multi-tube heating heat exchanger heat exchanger in which the heat exchanger is vertical and the pipe is straight, and dihydroxybenzenes and heavy substances Is a method for removing dirt from a heat exchanger introduced into the liquid from a nozzle provided at the bottom of the heat exchanger.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the liquid containing a target product and a heavy product is a liquid containing dihydroxybenzenes and a heavy product obtained by decomposing aromatic peroxides, and the heavy product separates and purifies the target product. At the same time, it adheres to the inside of the heating type heat exchanger provided at the bottom of the distillation column, etc., becomes dirty inside the heat exchanger, and inhibits the heat exchanging ability.
[0008]
Specifically, it includes a side reaction substance such as a polymer of an organic substance in the decomposition step and an inorganic substance such as a salt generated when neutralizing the acid catalyst used in the decomposition step. For example, in the case of the resorcinol process exemplified, resorcin polymer, resorcin and hydroxymethylstyrene adduct, etc., and other inorganic substances such as Na ₂ SO ₄ generated by the neutralization operation of the acid catalyst, etc. It becomes a dirty component of the exchanger.
[0009]
When a liquid containing such a target product and a heavy material is heated by a heating type heat exchanger, the heavy material adheres to the inside of the heat exchanger in a short period of time, and the heat exchange capacity is reduced, and the predetermined capacity of the heat exchanger can be exhibited. In addition, not only energy loss but also a decrease in production volume will cause problems in the stable operation of the entire plant.
[0010]
In order to remove the dirt inside the heat exchanger, as described above, the heat exchanger is stopped, the heat exchanger is switched to a spare machine, the equipment is opened, the dirt is removed, etc. And the operation of the chemical plant itself. Therefore, by introducing steam into the heat exchanger in the process, dirt inside the heat exchanger can be removed while the operation is continued without stopping the heat exchanger, and the heat exchange capability can be restored. . Introduction into the heat exchanger, and introduced a nozzle provided in the lower heat exchanger, an internal heat exchanger and a steam to pass through. Steam can be removed in that process or in a later process and does not affect product quality .
[0011]
One embodiment of the present invention is a multi-tube heating heat exchanger used when dihydroxybenzenes are distilled from a liquid containing dihydroxybenzenes and heavy substances obtained by acidolysis of aromatic peroxide. Is done.
[0012]
For example, in the resorcin production process, 1,3-diisopropylbenzene is oxidized to obtain a liquid containing 1,3-dihydroxyisopropylbenzene, etc., and this liquid is subjected to steps of extraction, concentration, decomposition, etc., and resorcin, acetone, Contains heavy material. When resorcin is refined and recovered from a liquid containing resorcin and heavy substances from which light boiling components such as acetone have been removed from this liquid, the heavy substances are removed by heating and distillation in a vertical multi-tube heating heat exchanger. To do.
[0013]
The heavy substance may contain a resorcin polymer, a resorcin and hydroxymethylstyrene adduct, and other inorganic substances such as Na ₂ SO ₄ generated by neutralization operation of an acid catalyst.
[0014]
Stops the operation of the multi-tube heating heat exchanger with dirt and heavy soil adherence and reduced overall heat transfer coefficient (hereinafter abbreviated as U), and heat exchanger with high pressure water of 1,300kg / cm ² When the operation of the heat exchanger is resumed after washing and removing the dirt, the initial U gradually decreases and decreases to about 1/3 after 200 days of operation. If U further decreases in this state, it becomes difficult to continue operation of the entire process. Therefore, while continuing the operation of the heat exchanger, the operation was continued while introducing steam that did not adversely affect the quality of the subsequent process of the process and the resorcinol as the target product from the nozzle at the bottom of the heat exchanger. However, U began to recover gradually. After 14 days, the process recovered to about twice that before the introduction of steam, and the process was running smoothly. After the steam is stopped, the recovered U will remain recovered for at least about 60 days. Therefore, the U can be recovered simply by introducing steam from the lower nozzle of the heat exchanger as needed while monitoring the U status. I can do it.
[0015]
According to this method, not only a great effort such as stopping the heat exchanger, switching to a spare machine, opening the equipment and removing dirt is unnecessary, but also the safety of the work accompanying these work, heat exchange. It is possible to ensure the stability of plant operation associated with the switching of the equipment.
[0016]
【Example】
Example 1
Stops the operation of the vertical multi-tube heating heat exchanger with dirt and U decreasing to about 60 Kcal / m ² · Hr · deg, and stains the heat exchanger with 1,300 kg / cm ² high pressure water After washing out, the heat exchanger was restarted. Immediately after resuming operation, U is 180 Kcal / m ² · Hr · deg. Met. As the operation continues, U gradually decreases. After 200 days of operation, U is 60 Kcal / m ² · Hr · deg. Declined. Therefore, while continuing the operation of the heat exchanger, steam of 1 kg / cm ² (120 ° C.) was introduced at the bottom of the heat exchanger at 16 kg / hr, and the operation was continued. After the introduction of steam, U began to recover gradually after the decrease in U, and after 14 days it recovered to 120 Kcal / m ² · Hr · deg. The steam stopped on the 14th day, but it was confirmed that the recovered U would continue for about 60 days thereafter.
[0017]
Comparative Example 1
The operation of the vertical multi-tube heating heat exchanger with dirt attached and U lowered to about 60 Kcal / m ² · Hr · deg. Was stopped, and the dirt was removed by washing with 100 ° C hot water. After the operation resumption U was recovered to ^{80Kcal / m 2 · Hr · deg} . , But dropped to ^{60Kcal / m 2 · Hr · deg} . In about 60 days, is no longer able to continue operation. The same operation stop and warm water washing were repeated several times, but in both cases, U decreased to 60 Kcal / m ² · Hr · deg. Within 60 days, and stable continuous operation was not possible.
[0018]
【The invention's effect】
By removing dirt by introducing steam into the heat exchanger while continuing the operation of the heating type heat exchanger in which dirt components based on heavy substances adhere to the inside and the heat exchange capacity is reduced by the present invention. , Removes dirt components and restores heat exchange capacity. By this method, it is possible to provide a heat exchanger dirt removal method that does not adversely affect the stable operation of the plant due to the stoppage of the heat exchanger and does not cause problems such as ensuring safety associated with the heat exchanger dirt removal work. became.
[Brief description of the drawings]
FIG. 1 is a view showing an example of a multi-tube heating vertical heat exchanger.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Inlet of the liquid containing a target object and a heavy material, 2 ... Steam inlet, 3 ... Heating medium inlet / outlet, 4 ... Heavy material outlet / outlet, 5 ... Outlet of target object

Claims (2)

In a process of a chemical plant for separating and purifying a target product by distillation from a liquid containing dihydroxybenzenes obtained by decomposing aromatic peroxides and a heavy product, the liquid containing the target product and a heavy product. The contamination based on the heavy material adhering to the inside of the heat exchanger that heats and evaporates the liquid containing the heavy material is removed by introducing steam into the heat exchanger while continuing the operation of the heat exchanger. This is a method for removing dirt from a heat exchanger, which is a multi-tube heating heat exchanger with a vertical heat exchanger and a straight pipe, and heat exchange is performed for liquids containing dihydroxybenzenes and heavy substances. A method of removing dirt from a heat exchanger, wherein steam passes through the chamber upward from the bottom, and steam is introduced into the liquid from a nozzle provided at a lower portion of the heat exchanger.   The method for removing dirt from a heat exchanger according to claim 1, wherein the dihydroxybenzene is resorcin.

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