JP2008007713A - Cleaning method within overhead piping in reactor tower of heavy oil thermal cracking apparatus, cleaning apparatus and cleaning pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for cleaning of coke adhered inside of an overhead piping in a reactor tower of a heavy oil thermal cracking apparatus. <P>SOLUTION: The cleaning method of a piping 25 set in the overhead of reactor tower of a batch or semi-batch heavy oil thermal cracking apparatus such as a delayed coker, Eureka<SP>RTM</SP>process and Flexicoker with high-pressure water, comprised of setting up high pressure water, attaching a high pressure water cleaning tube 23 on the outside of the overhead of reactor tower giving the high pressure water in the piping 25 from an exhaust nozzle 27 of the high pressure water cleaning tube to remove cokes adhered in the tubing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a method for cleaning an overhead pipe in a reaction tower of a heavy oil pyrolysis apparatus and a high-pressure water cleaning apparatus capable of achieving the same.

  At present, various processes (equipment) using a pyrolysis reaction method in petroleum refining have been proposed. For example, delayed coker, fluid coker that co-produces individual petroleum coke, bisbreaker for reducing viscosity of vacuum residual oil, yurika process that co-produces binder pitch for coke production for steel, coke gasification to fluid coker (Heavy oil) pyrolysis equipment such as flexi coker with equipment has been developed.

  Conventionally, in a heavy oil pyrolysis apparatus, a heavy carbonaceous component (referred to as a “coke precursor”) formed from asphaltenes or the like is generated along with cracked gas and cracked oil generated by thermal decomposition. For this reason, in the piping system of the heavy oil pyrolysis apparatus, in particular, in the top piping system of the reaction tower, this coke precursor adheres and cokes with time to form a coke layer. The thickness is increased to narrow the inner diameter of the piping system, causing an increase in internal pressure in the reaction tower. And if a coke layer grows too much, it will eventually be necessary to stop the operation of the heavy oil pyrolysis apparatus and remove the coke layer. In particular, in heavy oil pyrolysis apparatus (for example, Yurica process) using a thermal decomposition reaction with high-temperature steam, the amount of gas from the reaction tower is large, and the entrainment of the coke precursor is relatively large. During the period (about 1 year), it was necessary to stop the operation and remove coke existing in the piping system around the top of the reaction tower.

  Conventionally, the following has been proposed as a method for suppressing adhesion of coke precursors and coke layer growth in a piping system of a reaction tower of a heavy oil pyrolysis apparatus. For example, according to Japanese Examined Patent Publication No. 57-15797 (Patent Document 1), there is a method in which a pyrolysis distillate oil fraction is sprayed on the inner wall of a pipe and the adhesion of the coke precursor to the inner wall of the pipe is prevented by the wet wall effect. Proposed.

  However, in heavy oil pyrolysis equipment, especially heavy oil pyrolysis equipment (Yureka process) using the thermal decomposition function by high-temperature steam, coke precursor adhesion and coke layer growth are sufficiently suppressed. It was difficult to do.

Therefore, at present, in heavy oil pyrolysis equipment, especially heavy oil pyrolysis equipment using the thermal decomposition function using high-temperature steam, the growth of the coke layer is monitored to minimize the impact on the operation of the equipment. Therefore, development of a new technology for efficiently removing coke is required.
Japanese Patent Publication No.57-15797

  At the time of the present invention, the present inventors provided a high-pressure water washing device in the piping at the top of the reaction tower of the heavy oil pyrolysis device without stopping the operation of the device or changing the operating conditions. That is, it was found that coke can be effectively removed in the tower top pipe during normal operation of the apparatus. Therefore, the present invention remarkably achieves the removal of the coke layer in the tower top piping of the reaction tower, significantly reduces the number of coke removal work and maintenance inspections involving the shutdown of the heavy oil pyrolysis apparatus, The present invention provides a high-pressure water cleaning apparatus and a high-pressure water cleaning method capable of extending the operating period of a quality oil pyrolysis apparatus.

Therefore, the present invention is a method for washing the inside of a pipe disposed at the top of a reaction tower of a heavy oil pyrolysis apparatus with high-pressure water,
Prepare high-pressure water,
High pressure water is applied to the inside of the pipe,
Washing and removing coke existing in the pipe.

The high-pressure water washing apparatus provided by another aspect of the present invention is arranged in the top piping of the reaction tower of the heavy oil pyrolysis apparatus,
A high-pressure water supply,
A high-pressure water delivery department;
With a high-pressure water washing tube,
The high-pressure water washing pipe is provided with a discharge nozzle at an end thereof, and high-pressure water is applied from the discharge nozzle to the inside of the pipe to wash away coke existing in the pipe.

The high-pressure water washing pipe is provided with a discharge nozzle at an end of the high-pressure water washing pipe, and gives high-pressure water from the discharge nozzle to the inside of the pipe during operation of the heavy oil pyrolysis device, The coke precursor or coke present in the pipe is washed,
It is inserted into the top pipe of the reaction tower only when the coke existing inside the pipe is washed.

  The high-pressure water washing method (apparatus) according to the present invention is a heavy oil pyrolysis apparatus, particularly a heavy oil pyrolysis apparatus utilizing a thermal decomposition function by high-temperature steam, and is preferably, preferably periodically, when the pressure in the reaction tower rises. Can be implemented automatically. In particular, the high-pressure water washing method (apparatus) according to the present invention can remarkably remove coke by washing the inside (inner wall) of a pipe disposed at the top of the reaction tower with high-pressure water. As a result, there is an effect that the blockage in the piping is prevented, the increase in the internal pressure in the reaction tower is suppressed within a certain value, and the heavy oil pyrolysis apparatus can be continuously operated for two years or more.

Definition
(Heavy oil) pyrolysis device In the present invention, "(heavy oil) pyrolysis device" can realize a batch or semi-batch pyrolysis method such as delayed coker, yurika process, flexi coker, etc. Say. Here, these processes are outlined below. In the delayed coker, petroleum refined residual oil is gently decomposed under heating and coked with a coke drum. The flexi coker is a fluid coker with a coke gasifier, and the coke is gasified in a gasifier. The Yurika process (apparatus) is described below.

Eureka process (equipment)
The Eureka process (apparatus) will be outlined with reference to FIG. A vacuum residue obtained by distillation of crude oil is heated in the raw material preheating furnace 1 and supplied to the bottom of the distillation column 3. The raw material oil (reduced pressure residue) for the pyrolysis reaction is introduced into the cracking furnace 5 from the bottom of the distillation column 3. The vacuum residue is partially decomposed by heating in the cracking furnace 5, and then supplied to the reaction tower 7a or 7b (two sets constitute one reaction tower). The vacuum residue is supplied alternately (semi-batch method) to the reaction tower 7a or 7b by the switch valve 8 or the like. That is, while the raw material oil is supplied to one of the reaction towers 7a or 7b, each process such as a steam pyrolysis reaction, cooling, and blow-down is performed in the other reaction tower 7a or 7b. In one reaction tower, when the steam pyrolysis reaction is performed, superheated steam is supplied from the steam heating furnace 9 to the reaction tower. In the reaction tower 7a or 7b, the superheated steam is supplied for the purpose of supplying cracking heat, stripping cracked oil and cracked gas, and stirring in the reaction tower. The cracked oil and cracked gas are supplied to the distillation tower 3 together with steam from the top of the reaction tower 7a or 7b. In the reaction liquid phase of the reaction tower 7a or 7b, pitch is generated, and when the degree of polycondensation of the pitch is adjusted by the softening point (temperature ° C.) and reaches a specific softening point, the reaction tower 7a or 7b Water is directly supplied and cooled to complete the pyrolysis reaction. The pitch is sent to a pitch receiving tank 11 provided at the lower part of the reaction tower 7a or 7b, and is cooled and conveyed by a pitch flaker 13 to be a pitch product 20.

High Pressure Water Cleaning Method / High Pressure Water Cleaning Device The contents of the high pressure water cleaning device and the high pressure water cleaning method according to the present invention will be described with reference to FIGS. FIG. 2 is an enlarged view of the tower top piping of the reaction tower 7a or 7b (hereinafter referred to as “reaction tower 7” as appropriate) shown in FIG. FIG. 2 shows an enlarged view of the arrangement of the high-pressure water washing apparatus 21 and an enlarged view of the high-pressure water washing pipe 23 according to the present invention. A high-pressure water washing pipe 23 can be attached to the outside of the tower top pipe 25 of the reaction tower 7. The tower top pipe 25 is installed to supply the cracked oil or cracked gas obtained in the reaction tower 7 to the distillation tower 3 together with steam. The high-pressure water washing pipe 23 enters the inside from the outside of the tower top pipe 25, and a discharge nozzle 27 provided at the tip of the high-pressure water washing pipe 23 exists in the pipe of the tower top pipe 25. High pressure water is supplied to the upper part of the high pressure water washing pipe 23 from a high pressure water supply device through a high pressure water distributor. The supplied high pressure water is supplied from the discharge nozzle 27 of the high pressure water washing pipe 23 into the pipe of the tower top pipe 25 to remove coke existing in the tower top pipe 25.

1) High-pressure water supply device A high-pressure water supply device applies a predetermined pressure, which will be described later, to water from a water supply source. The water supply source may be directly from industrial water, or boiler water, petroleum refining process (distillation process, etc.), or recovered water from heavy oil pyrolysis apparatus may be used.

2) High-pressure water delivery section The high-pressure water discharged from the high-pressure water feeder is supplied to the high-pressure water washing pipe 23 by an appropriate high-pressure water delivery section (means), for example, a pipe, a (high pressure resistant) hose, or the like. From the high-pressure water supply to the high-pressure water washing pipe 23, it is preferable to include a regulating valve, a valve, a pressure regulator, etc. (these may be automatically controlled variable).

3) High-pressure water washing tube The high-pressure water washing tube 23 may be made of a material having pressure resistance and durability, and preferably made of a metal such as stainless steel. The starting point of cleaning the inside of the tower top pipe 25 with the high pressure water supplied from the discharge nozzle 27 of the high pressure water washing pipe 23 to the inner pipe of the tower top pipe 25 is the internal pressure of the reaction tower 7 of the heavy oil pyrolysis apparatus. The determination is made based on the degree of increase in the differential pressure of the bottom pressure of the distillation column 3, but more simply, the determination may be made based on the internal pressure of the reaction column 7. In the present invention, the high-pressure water washing is preferably started when the differential pressure from the internal pressure of the reaction tower 7a or 7b is 30 kPa or more, preferably 20 kPa or more. According to a preferred aspect of the present invention, once the above-described differential pressure of the internal pressure has increased, it is preferable to periodically perform high-pressure water washing thereafter. This makes it possible to operate the reaction tower 7 for a long time. The internal pressure of the reaction tower 7 and the bottom pressure of the distillation tower 3 can be measured by a pressure gauge installed in each. In addition, when the measured value is transmitted, the differential pressure between the internal pressure of the reaction column 7 and the bottom pressure of the distillation column 3 is calculated, and the high pressure water washing is automatically performed when the internal pressure difference exhibits the above value. It is also possible to further use an automatic control device provided with information processing means programmed beforehand.

  The water pressure of the high-pressure water may be determined as appropriate, but the water pressure at the discharge part of the discharge nozzle 27 of the high-pressure water washing tube 23 is 5 MPa or more, preferably 20 MPa or more, and more preferably the lower limit value is 30 MPa or more. . This water pressure adjustment may be performed by a high-pressure water supply device, or an adjustment valve, a valve, and a pressure adjustment device installed in a high-pressure water distribution section (means) from the high-pressure water supply device to the high-pressure water washing pipe 23. It may be performed by a vessel or the like. These devices may also be operated and controlled by the automatic control device described above.

4) Discharge nozzle The high pressure water discharge portion of the discharge nozzle 27 may have any form as long as it corresponds to the shape of the pipe to be cleaned, and the discharge direction may be various forms. FIG. 3 shows a specific example of the discharge direction of the discharge nozzle 27, and high-pressure water may be discharged in the illustrated direction. The shape and quantity of the holes of the discharge nozzle 27 may be determined as appropriate, but preferably the average diameter of the holes is 1 mm or more and 10 mm or less, preferably the lower limit is 3 mm or more and the lower limit is 6 mm or less. The number of holes is preferably plural, and more preferably about 2 or 3. By setting the shape of the hole of the discharge nozzle 27, the hole diameter, and the quantity, the amount of cleaning water is also determined.

  According to a preferred aspect of the present invention, the discharge nozzle 27 is prepared in various forms according to the shape of the tower top piping, considering efficient removal of the grown coke layer, and if necessary It is preferable that it can be applied. Further, the discharge nozzle 27 is preferably one that can rotate itself. According to a more preferable aspect of the present invention, it is preferable that the high-pressure water washing pipe 23 provided with the discharge nozzle 27 is not inserted into the inner pipe of the tower top pipe 25 during normal operation. Therefore, it is preferable that the high-pressure water washing pipe 23 is inserted into the inner pipe of the tower top pipe 25 only during washing, and does not exist in the tower top pipe 25 before and after washing. According to a preferred embodiment of the present invention, the high-pressure water washing pipe 23 is preferably provided with means that is automatically inserted into and discharged from the inner pipe of the tower top pipe 25. In the present invention, the insertion / discharge of the high-pressure water washing tube 23, the rotation of the discharge nozzle 27, and the high-pressure water discharge may be controlled by the automatic control device described above.

Preferred Embodiment The washing apparatus or washing method according to the present invention is used in a heavy oil pyrolysis apparatus, in particular, in a pipe arranged at the top of a reaction tower of a heavy oil pyrolysis apparatus utilizing a high temperature steam pyrolysis function. Can be used. In the present invention, the heavy oil pyrolysis apparatus can be used with one reaction tower, and preferably with a plurality of reaction towers. According to a preferred embodiment of the present invention, as shown in FIG. 1, a heavy oil pyrolysis apparatus (including a reaction tower 7 a and 7 b, and further equipped with a pitch receiving tank 11 as required) utilizing a pyrolysis reaction with high-temperature steam ( It is most preferable to use it in the Eureka apparatus.

  The washing apparatus or washing method according to the present invention is preferably used in a yurika apparatus in which the reaction towers 7a and 7b are operated in a semibatch mode. It is preferable to wash the inside of the top piping of one reaction tower with high-pressure water using a specific period in which the reaction tower 7a or 7b is switched in a semibatch. If high-pressure water washing can be performed within the (specific) period of semi-batch switching, the temporary increase in the operating pressure of the distillation tower 3 due to evaporation of the high-pressure washing water is suppressed, and the effect of pressure fluctuations is minimized. It becomes possible to keep. Further, the weakening of the metal material due to the temperature difference between the temperature of the high-pressure washing water and the temperature in the reaction tower and in the tower top pipe can be alleviated.

  According to a preferred embodiment of the present invention, when the inside of the tower top pipe of the reaction tower 7a or 7b is washed with high-pressure water, the reaction tower of the pipe system is in a state immediately before the next semi-batch operation (feeding of raw material oil). Is preferred. Here, the semi-batch operation of the reaction towers 7a and 7b will be described. When the semi-batch operation cycle of the reaction tower 7a or 7b is, for example, 3 hours, the reaction tower 7a or 7b is supplied with the feed oil every 1.5 hours. Then, during the 1.5-hour process in which one of the reaction towers 7a or 7b is supplied with raw material oil, the other reaction tower 7a or 7b is subjected to thermal decomposition for a certain period of time in the latter half after receiving the raw material oil. After the reaction step, a cooling step for stopping the reaction and a blow-down step for extracting the generated petroleum pitch are performed, and if necessary, low-temperature feedstock oil (vacuum residue oil) for adjusting the reaction time distribution is supplied. Although the process proceeds to the initial supply process, a standby process is set before the next feed oil supply process for the purpose of adjusting the overall time required for these processes. When the inside of the tower top piping of the reaction tower 7a or 7b is washed with high-pressure water, it is preferably carried out immediately before the next feed oil supply process, that is, during the standby process.

The contents of the present invention will be described in detail with reference to the following examples, but the scope of the present invention should not be construed as being limited to these examples.
Example 1 (Short-term operation test)
A semi-batch reactor A equipped with a high-pressure water washing mechanism according to the present invention in a tower top pipe using a Yurica pyrolysis reactor of 3,800 kiloliters / day of raw material vacuum residue processing capacity shown in the schematic diagram of FIG. And the pressure transition of the reaction tower A and the reaction tower B when the reaction tower B was operated for 2 months in the steady operation state was measured. The measurement results were as shown in Table 1 below. In Table 1, the horizontal axis indicates the number of operating days (days) for two months, and the vertical axis indicates the reactor can pressure [kPa]. The reaction towers A and B are a pair of reduced pressure residue pyrolysis reaction towers that are operated to be switched. However, as the operation (continuous operation) showed a tendency to increase the pressure (can pressure) of the reaction tower A, Coke removal during operation was carried out by a high-pressure water washing mechanism according to the present invention for a rising pipe portion having a diameter of 600 mm at the outlet. From the results shown in Table 1, coke removal during operation was sufficiently achieved by the high-pressure water washing method (apparatus) of the present invention, and a reduction in can pressure in the reaction tower A was clearly recognized.

Example 2 (long-term operation test)
Using the same Yurika pyrolysis reactor as in Example 1, the change in the can pressure of the reaction tower A during a long-term continuous operation for 2 years was recorded. In the measurement, two types of cleaning methods, that is, a method of cleaning appropriately (randomly) and a method of periodically cleaning were performed separately (twice), respectively. The measurement results were as shown in Table 2 below. In Table 2, the horizontal axis represents the number of operating days (days) of long-term continuous operation for 2 years, and the vertical axis represents the can pressure [kPa] of the reactor A. Both of these two operations were long-term continuous operations with a high operation rate of about 90% on average, but either of the method of cleaning appropriately or the method of periodically cleaning by the high-pressure water cleaning mechanism according to the present invention. In this case, it was understood that the removal of coke during operation was achieved, and any increase in the can pressure of the reaction tower A was within the allowable range. In particular, when the method of periodically washing with the high-pressure water washing mechanism according to the present invention is used after an increase in the can pressure of the reaction tower A is observed, coke removal during operation can be sufficiently performed, and it is nearly two years. Even after the operation period has passed, the increase in can pressure is slight, and there is no effect on the pyrolysis reaction conditions and other operating conditions due to the increase in can pressure, enabling long-term stable and continuous operation of the Yurika pyrolysis reactor. It was understood that

FIG. 1 is a schematic view of a heavy oil pyrolysis apparatus. FIG. 2 shows an enlarged view of the arrangement of the high-pressure water washing apparatus according to the present invention and an enlarged view of the high-pressure water washing pipe. FIG. 3 shows a specific example of the discharge nozzle of the high-pressure water washing pipe according to the present invention.

Claims (3)

A method of washing the inside of a pipe arranged at the top of a reaction tower of a heavy oil pyrolysis apparatus with high-pressure water,
Prepare high-pressure water,
Giving the high-pressure water inside the pipe,
A cleaning method comprising removing coke existing in the pipe. A high-pressure water washing apparatus arranged in a pipe at the top of a reaction tower of a heavy oil pyrolysis apparatus,
A high-pressure water supply,
A high-pressure water distribution department;
With a high-pressure water washing tube,
The high-pressure water cleaning pipe is provided with a discharge nozzle at an end thereof, and applies high-pressure water to the inside of the pipe from the discharge nozzle to remove coke existing in the pipe. Cleaning device. A high-pressure water washing pipe for washing the top pipe of the reaction tower of the heavy oil pyrolysis apparatus,
A discharge nozzle is provided at an end of the high-pressure water washing pipe, and high-pressure water is applied from the discharge nozzle to the inside of the pipe to remove coke existing in the pipe.
A high-pressure water washing pipe inserted into the top pipe of the reaction tower only when removing coke existing inside the pipe.

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