JPS58128103A - Temperature controlling method of distilling column - Google Patents

Abstract

PURPOSE:To economize fuel consumption by subjecting a pressure control valve for fuel to be supplied to a heating furnace to cascade control by the temp. signal obtained by detecting the temp. in the upper part in a distilling column and the pressure signal obtained by detecting the supply pressure of the fuel to be supplied to the heating furnace. CONSTITUTION:Part of the liquid in the bottom of a distilling column 1 is discharged and is introduced into a heating furnace 10, where heat is applied thereto and the liquid is fed into the column 1. In this stage, the supply pressure of the fuel to be supplied into the furnace 10 is detected with a pressure detector 9 by which a pressure signal is obtained. At the same time, the temp. in the upper part of the column 1 is detected with a temp. detector 6 by which a temp. signal is obtained. Cascade control is accomplished by both signals to control a pressure control valve 11 for the fuel to be supplied into the furnace 10. Thus, the accuracy of the temp. control is improved additionally, and the fuel to be consumed in the furnace 10 is economized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a distillation column temperature control method KIIL, more specifically, a distillation method for distillation column IIK, which improves temperature controllability in the distillation column and reduces fuel consumption in the heating furnace. @ORegarding temperature control method.

Conventionally, temperature control of distillation columns in petroleum oii* refining is
The tower J[0 temperature is controlled by changing the reflux amount, while the tower bottom O temperature is controlled by changing the amount of fuel supplied to the heating furnace.
The top temperature and bottom temperature of the distillation column were controlled separately (11th visit).

Therefore, both temperature controls interfere, making it extremely difficult to perform optimal temperature control, and as a result, surplus reflux has to be carried out for product quality control, which requires a large amount of heat.

An object of the present invention is to provide a method for controlling the temperature of a distillation column that eliminates such inconveniences. A distillation column characterized in that the pressure control valve for the fuel supplied to the heating furnace is cascade-controlled based on the temperature signal obtained by detecting the temperature signal obtained by detecting the supply pressure of the fuel supplied to the heating furnace, and the pressure signal obtained by detecting the supply pressure of the fuel supplied to the heating furnace. This is a temperature control method.

The method of the present invention differs from the conventional method in which the top temperature and bottom temperature within the distillation column are controlled separately, and is characterized in that both temperatures are linked and controlled in a unified manner.

The method of the present invention will be explained below with reference to the drawings while comparing it with the conventional method. giI! g is a process diagram showing an example of a conventional method. According to this conventional method, raw oil is first charged into a distillation column 1 and distilled, and the resulting column top vapor is extracted from the top of the column and passed through a cooler 2. It is cooled down, a part of it is condensed, and it is introduced into the receiving tank 3. A portion of the liquid in the receiving tank 3 is refluxed to control the temperature at the top of the tower, and the remainder is discharged as a product. Here, the liquid oil flow rate is determined by the temperature signal from the temperature detector 6 at the top of the tower and the flow rate detector 7.
The flow control valve 5 is controlled by cascade control using the flow rate signal from K and the flow rate signal K, and the flow rate is adjusted to an appropriate flow rate. By adjusting the reflux amount in this way, the tower top temperature is controlled within a desired range. Note that the gas in the receiving tank 3 is extracted elsewhere, and the pressure within the system is maintained constant. On the other hand, a part of the moat at the bottom of the tower is extracted and pumped into the heating furnace 1 by pump 12.
0, where it is heated and returned to the distillation column 1.

At this time, the temperature at the outlet of the heating furnace is detected by the temperature detector 8, and the fuel supply amount is detected by the pressure detector 9, thereby performing cascade control to determine the fuel supply amount. Controlling the amount of fuel supplied in this way
This allows the bottom temperature to be adjusted within the desired range. Note that here, a part of the bottom liquid is cooled by a cooler 13 and extracted as a product.

As described above, in the above-mentioned conventional method, the temperature control at the top of the column and the temperature control at the bottom are performed completely separately and unrelatedly, so that they interfere with each other, making it difficult to control the temperature optimally.

On the other hand, according to method K of the present invention (see Figure 2), the raw oil is first charged into the distillation column 1 and distilled, and the resulting column top vapor is extracted from the top of the column and cooled in the cooler 2. A part of the water is condensed and guided to the receiving tank 3. Part of the liquid in receiver 3 is refluxed and the remainder is taken out as a product. Here, the amount of liquid reflux is set at a constant ratio to the amount of product withdrawn from the top of the column, and is controlled from temperature control. Therefore, cascade control of the temperature detector 6 and the flow rate detector 7 at the top of the tower is not necessary. A portion of the liquid at the bottom of the column is extracted and introduced into a heating furnace 10 by a pump 12, where it is heated and returned to the distillation column 1. At this time, the pressure of the fuel supplied to the heating furnace 10 is detected by the pressure detector 9 and used as a pressure signal. The temperature at the location is detected by the temperature detector 6 and used as a temperature signal, and cascade control is performed using these two signals to adjust the pressure control valve 11 for fuel supplied to the heating furnace 10. In this way, the method of the present invention, which controls the bottom temperature by controlling the fuel pressure control valve while considering the temperature at the top of the distillation column 1, centrally controls the temperature inside the column. This method is significantly superior to conventional methods.

According to the method of the present invention described above, there is no interference between the temperature control at the top or upper part of the column and the temperature control at the bottom or lower part of the column, and the accuracy of temperature control is further improved. The amount of fuel consumed can be reduced by 5 to 7 times compared to conventional methods.

Therefore, the method of the present invention can be widely used in petroleum refining, petrochemical industry, and chemical industry.

Next, examples of the present invention will be shown.

Example A mixture of LPG and naphtha was hydrodesulfurized and the treated oil was used as a raw material for debutanization. As a debutanizer, the distillation column and its process shown in Figures 11 and 2 were used. As a result, the changes in the reflux amount of the tower top liquid, the changes in the tower top temperature, and the changes in the heating furnace outlet temperature were as shown in Figures 3 (translation), Figure 4 (translation), and Figure 5-), respectively.

Comparative Example The procedure was the same as in the example except that the process shown in FIG. 1 was used instead of the process shown in FIG. 2 in the example. As a result, the changes in the reflux amount of the tower top liquid, the changes in the tower top temperature, and the changes in the heating furnace outlet temperature are shown in Figure 3(b), respectively.
It was as shown in FIG. 4(b) and FIG. 5(b).

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process diagram showing an example of a conventional method, and FIG. 2 is a process diagram showing an embodiment of the method of the present invention. FIG. 3 is a graph showing changes in the reflux amount of tower top liquid, FIG. 4 is a graph showing changes in tower top temperature, and FIG. 5 is a graph showing changes in heating furnace outlet temperature. 1--Distillation column, 2--Cooler, 3--Receiving tank, 4--Pump, 5--Flow rate control valve, 6--Temperature detector, 7--
・Flow rate detector, 8-temperature detector, 9...pressure detector. 10-heating furnace, 11-pressure control valve, 12...pump,
13-Cooler. Patent Applicant: Idemitsu Kosan Co., Ltd. Procedural Amendment (Voluntary) June 14, 1980 Director-General of the License Agency Kazuo Wakasugi - Incident O Mugi Show Maro Sho 54-254-2l? 2 Title of the invention Temperature control method The numerical value on the vertical axis in Figure 5 (a) and 2) is the meter reading, and the value obtained by multiplying this value by the flow rate coefficient SSO is the actual reflux volume <ht1 day).'' (2) No. S
Figures (&) and (b) are corrected to the attached notice (above) Figure 3 (b) Procedural amendment (voluntary) May 2, 1920 Showa SS Commissioner of the Japan Patent Office Kazuo Wakasugi t Case O indicated patent @ 54-11001? 1. Title of the invention: Temperature control method for distillation towers; Case to be amended and relation to O; Patent applicant: Idemitsu Kosan Co., Ltd. Principal Agent Address: 1-1-10-5 Kyobashi, Chuo-ku, Tokyo 104 Address: Meirinsho subject to amendment O O departure beak 01111 Rinna explanation O column table correction aP! Contents (1) Page 2, line 5, 10r of the specification, add "on quality control" and "surplus" on management. (2) Page 5, lines 12-15 O "Improved" and "Also" 0111K r The reflux ratio can also be reduced to a minimum of K1ml. ” to join. (that's all)

Claims (1)

[Claims] (1) In a method for controlling the temperature of a petroleum distillation column, a temperature signal obtained by detecting the O upper temperature in the distillation column;
A method for controlling the temperature of a distillation column, characterized in that a pressure control valve for fuel supplied to a heating furnace is cascade-controlled based on a pressure signal obtained by detecting the supply pressure of fuel supplied to the heating furnace.