JPS59197490A - Coke producing equipment - Google Patents

Abstract

PURPOSE:To produce high quality coke from raw material oils of various qualities, by connecting a heating oven to a coking tank with piping via an intermediate tank equipped with a low-volume pressure and temperature control device. CONSTITUTION:A raw material heavy oil consisting of residual oils of normal or reduced pressure direct distillation and thermal cracking of petroleum, coal tar, etc. fed through a pipe 5 is heated to about 450-500 deg.C in a heating oven 1 and is led into an intermediate tank 2 for preliminary thermal cracking in a dwell time of about 10-300sec. Heavy oil from the intermediate tank 2 is sent through a pipe 23 into one of coking tanks 3a, 3b, e.g. into 3a at the bottom in an increasingly larger amount and, after stay for a total of about 24-48hr, is subjected to additional thermal cracking and coking treatments. When the tank 3a has been nearly filled heavy oil is introduced into the tank 3b.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coking apparatus capable of producing product coke of good quality from raw material heavy oil of various properties.

Delayed coking equipment is widely used to obtain coke from petroleum-based or coal-based heavy oil. Generally, this delayed coking equipment basically consists of a heating furnace for raw material heavy oil and two or more coking tanks installed in parallel with each other, connected in series in this order. Heavy oil is heated by a pump to a temperature of 450 to 50
The coke that has reached a thermal decomposition temperature of 0°C is sent to a coking tank where it stays for a relatively long time, and the coke produced by decomposition of heavy oil is accumulated inside the coking tank, and the coke is decomposed from the top. A dilate coking process is carried out by distilling off the oil.

However, one problem with this delayed coking method is that high-quality coke cannot be obtained from sources other than heavy oil with limited properties. For this reason, several techniques have been proposed for producing high-quality coke from a variety of raw material heavy oils. As such technology,
For example, there is a method in which petroleum-based heavy oil is subjected to appropriate thermal decomposition in advance in a pyrolysis device, and the resulting tar is used as a raw material or as part of the raw material to supply a blended oil to a coking tank (Tokuko Showa). 49-33901, etc.), a method using clarified oil from a fused cracker as a blending stock oil (Japanese Patent Publication No. 18176, etc.), a method using two coking tanks in series, and A method of producing inferior coke from the early coking components in the feedstock oil in the tank, and producing high quality coke from the remaining oil in the second stage premises (Sekai 1989-899).
Publication No. 02). The former two methods are similar to the range of selection or pretreatment of raw material oil in the dilate coking method, and the latter aims at removing inferior components in the raw material oil, and in any case, it is not widely used. It can be said that this technology has seven characteristics: adjusting the composition of raw oil.

In a broad sense, the present invention relates to a technology for adjusting feedstock oil, but by relatively simple modification of equipment, the operating range of reaction conditions can be expanded, and high quality coke can be produced from a wide range of quality feedstock oils. The aim is to provide technology.

In conventional delay P coking equipment, a fluid heated to a predetermined temperature by a heating furnace is simply transferred to a coking tank where the temperature is maintained. Moreover, the coking tank requires a huge volume in order to proceed with the desired thermal decomposition and coking, and it is virtually impossible to heat and control the temperature of such a huge coking tank. Therefore, the temperature of the coking bath is only maintained at a natural temperature that balances the amount of heat introduced by the fluid heated in the furnace. j That is, the temperature of the coking bath depends only on the temperature at the outlet of the heating furnace. Of course, there are other operating variables such as the flow rate and pressure of feedstock oil, but in actual industrial manufacturing, the operating range is limited to an extremely narrow range due to design constraints, and it is difficult to improve the quality of product coke. Not free enough to be effective.

The inventors of the present invention have been engaged in coke production for many years and have conducted extensive research. As a result, the quality of the coke product depends not only on the temperature conditions in the coking tank, but also on the initial coking or thermal decomposition conditions of the feedstock oil. In particular, we discovered that the pyrolysis conditions from the heating furnace to the coking tank have a very important influence. In other words, it has been found that coke quality can be controlled not by controlling the reaction conditions in the coking tank, but by controlling the preliminary thermal decomposition conditions. Moreover,
Since the preliminary pyrolysis step is accomplished in a relatively short time, its control is significantly simpler than in huge coking tanks.

The coking apparatus of the present invention is based on such knowledge, and more specifically, in a delayed coking apparatus in which a heating furnace and a coking tank are connected in this order by piping, the coking width is An intermediate tank having a relatively small capacity and having independent pressure and temperature control means is provided, and substantially the entire amount of the material to be processed in the intermediate tank is supplied to the coking tank.
This is an opportunity to do something like this.

Hereinafter, the present invention will be explained in more detail based on the drawings.

The drawing is a layout diagram of each part of the coking apparatus of the present invention. This device consists of a heating furnace 1, an intermediate tank 2, a pair of coking units (coke 3a, 3b, and a fractionating column 4) arranged in parallel.
In this order, pipes 12, 23; 34 +1
They are connected in series. In addition, 5 raw material supply pipes (not shown) are connected to the heating furnace 1 and a raw material heavy oil tank (not shown), and a shield ring pipe 41 for the bottom part of the fractionating column 4 is connected to this pipe 5. Further, a superheated steam introduction pipe 6 is connected to the lower part of the intermediate tank 2, and a cooling oil introduction pipe 7 is connected to the upper part, and a pressure control valve 8 is provided at the outlet pipe of the intermediate tank 2.1-1. The volume of the intermediate tank 2 is suitably about 1 to 5% of the volume of the coking tank 3a or 3b.

A typical operating mode of the above device will be explained.

First, from the pipe 5, raw material heavy oil consisting of petroleum-based normal pressure (reduced straight-run residual oil, pyrolysis residual oil, coal tar, etc.) is supplied, and it passes through the heating furnace 1 to a temperature of 450 to 500 After heating it to ℃, it was introduced into the intermediate tank 2 and heated to
Preliminary thermal decomposition is performed with a residence time of approximately 0 seconds. At this time, if the outlet temperature of the heating furnace 1 is too low for the type of raw material oil used, superheated steam or the like is introduced from the steam pipe 6 to heat the contents; Cooling oil heated to a temperature lower than 7 is introduced to cool the contents. In this way, the reason for controlling the temperature again in the intermediate tank 2, rather than the outlet temperature of the heating furnace 1, is to control the temperature of the heating furnace 1 once set for the standard oil type, heating, turning, etc. This is because the factor cannot be changed accordingly even if the raw material oil type changes, and ideal preliminary pyrolysis conditions may not be adopted depending only on the heating furnace 1.

Furthermore, the pressure in the intermediate tank 2 is controlled to 5-30 Ky/crn''G, which is equal to or higher than the pressure in the coking m3a, 3b, by opening and closing the control valve 8.

As shown in the example below, we found that increasing the pressure for preliminary pyrolysis within a certain limit is advantageous for improving the quality of coke product (see practical example below); Control of the pressure in the tank 2 not only adjusts the pressure as a pre-pyrolysis reaction condition, but also has the effect of adjusting the residence time in the intermediate tank 2.The volume of the intermediate tank 2 is the same as that of the coking tank 3a, Since the volume is significantly smaller than that of coke 3b, the same initial pyrolysis pressure can be applied to coke 3a,
Carrying out the process in the intermediate tank 2 instead of in the intermediate tank 3b is far more advantageous in terms of the economics of the device as a pressurized container.

The heavy oil subjected to the initial thermal decomposition treatment in the intermediate tank 2 is converted into coke 't43a in the same way as in the normal dilate coking method.
, 3b, further coking treatment is carried out.

That is, the heavy oil from the intermediate tank 2 is charged into one of the coking Wis 3a and 3b (for example, the bottom part of the coke Wi 3a) through the pipe C, and is held in the tank 3a for a total of 24 to 48 hours while gradually increasing the amount. During the process, it is further subjected to thermal cracking and coking treatment. When tank 3a is almost full, heavy oil is introduced into tank 3b. On the other hand, tank 3
In a, thermal cracking and coking are continued for a while, and the cracked oil is introduced into the fractionating column 4 through the piping.
Pipes 9a, 9b,
The cracked gas or product light oil is recovered through 9c, etc., and the heavy oil is circulated from the bottom of the tower to the upstream side of the heater 1 through a pipe 41.

After holding the coke in the tank 3a for a required period of time, the tank 3a is opened and the product coke produced is recovered.

In the above, preferred embodiments of the device of the present invention have been described, but various modifications can be made to the concave circle of the present invention. For example, in the above example, additional heating and cooling means are provided in the intermediate tank 2, but this may be either heating or cooling means, and the heating and cooling may be indirect rather than direct heat exchange. It may also be done by heat exchange. Further, the intermediate tank 2 may have any shape or structure as long as the above objective is achieved. Therefore, in addition to the tank wall type described above, there may be a tubular type or a type in which a tube is arranged in a coiled manner.

As described above, according to the present invention, a conventional delayed coking apparatus is modified to provide an intermediate tank equipped with independent pressure and temperature control means, thereby making it possible to handle a variety of feedstock heavy oils. It becomes possible to set the optimal initial pyrolysis treatment according to changes, and it becomes possible to improve the quality of product coke obtained from the same raw material heavy oil.

Hereinafter, the effects of using the device of the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Two heating furnaces equipped with heating pipes with an inner diameter of 3 mm and a length of 9 m, an intermediate tank with an internal volume of 2 tons connected to the heating furnaces, and a tank with an internal volume of 80 tons connected to the intermediate tanks. A plant-scale coking unit consisting of a coking tank and a coking tank was constructed. This intermediate tank had a high temperature steam supply device as a heating means, a quenching oil supply device as a cooling means, and a control knob as a pressure control means.

Table 1 shows the properties of the raw material heavy oil used. Note that the raw material heavy oil shown in Table 1 was also used in Example 2 and Comparative Examples 1 and 2 below.

Table 1 The raw material heavy oil having the above properties was supplied to the heating furnace at a rate of 200.9/min, and delayed coking was performed under the conditions shown in Table 2. The results are shown in Table 3.

Example 2 Delayed coking of feedstock heavy oil was carried out under the conditions shown in Table 2 in the same manner as in Example 1 except that the intermediate cracking tank pressure in the intermediate tank was changed, and the results are shown in Table 3.

Comparative Example 1 A ξ pilot plant similar to that of Example 1 was constructed except that no intermediate heat was provided, and dirate coking of feedstock heavy oil was carried out under the conditions shown in Table 2 in the same manner as in Example 1. are shown in Table 3.

Table 2 Table 3 *Thermal expansion coefficient values between 30 and Zoo℃ (drain direction)
Looking at the results in Table 3, it can be seen that Example 1.2, in which initial pyrolysis was carried out under pressure in intermediate tank 2, was carried out under optimal conditions as a normal delayed coking method for the raw material used. Compared to the comparative example, the decomposition of the feedstock oil has progressed,
It can be seen that not only the yield of light valves (gas, gas oil, diesel oil) has improved, but also the apparent specific gravity of the product coke has improved, resulting in high-quality coke with a small coefficient of thermal expansion.

Comparative Example 2 The heating furnace temperature was 490°C and the coking temperature was 46o-
Delay P coking of the raw material heavy oil was carried out as c, but at that time, the coking tank was heated from 2/cfn2G to 7.
The pressure was increased to K9/CITL2G. The obtained coke had an apparent specific gravity of 1.25 (,9/Cm3) and 2.
It had 00C, T, E.

This shows that coke with good properties cannot be obtained simply by increasing the pressure in the coking tank without providing an intermediate tank.

[Brief explanation of the drawing]

The drawing is a layout diagram of a trough of a coking apparatus according to an embodiment of the present invention. 1... Heating furnace, 2... Intermediate, 1.3a, 3b
. . . Coking tank, 4. Fractionation tower, 6. Superheated steam piping, 7. Cooling oil piping, 8. Pressure control valve.

Claims (1)

[Claims] In a delayed coking apparatus in which a heating furnace and a coking tank are connected in this order by piping, an intermediate tank having a smaller capacity than the coking tank and equipped with independent pressure and temperature control means is provided, and the intermediate tank is equipped with an independent pressure and temperature control means. A coking apparatus characterized in that substantially the entire amount of the processed material is supplied to a coking tank.