CN111425626B

CN111425626B - Oil switching valve and use method thereof in delayed coking device

Info

Publication number: CN111425626B
Application number: CN201910023383.7A
Authority: CN
Inventors: 张欣; 杨成炯
Original assignee: Sinopec Engineering Group Co Ltd; Sinopec Guangzhou Engineering Co Ltd
Current assignee: Sinopec Engineering Group Co Ltd; Sinopec Guangzhou Engineering Co Ltd
Priority date: 2019-01-10
Filing date: 2019-01-10
Publication date: 2021-10-08
Anticipated expiration: 2039-01-10
Also published as: CN111425626A

Abstract

The invention discloses an oil switching valve and a use method thereof in a delayed coking device. The oil switching valve is a five-way plug valve and is provided with a valve body (11), a plug (12), a valve cover (17), a valve rod (18), a valve actuating mechanism and the like. The oil switching valve is provided with an oil inlet (15) and four oil outlets (16), and the valve actuating mechanism comprises a lifting actuating mechanism (20) and a rotating actuating mechanism (21). The oil switching valve is used in the delayed coking unit to switch the feeding to three coke drums separately. Oil from the furnace enters the plug passageway of the oil diverter valve from the oil inlet, passes through the oil outlet and oil outlet lines and the bypass line into the coke drum. The oil is switched for the three coke drums by rotating the valve rod and the cock of the oil switching valve. The invention is mainly used for a delayed coking device which takes three coke drums as a group in an oil refinery.

Description

Oil switching valve and use method thereof in delayed coking device

Technical Field

The invention relates to an oil switching valve used in a delayed coking unit of an oil refinery and a use method thereof in the delayed coking unit.

Background

In the typical process flow of a delayed coker unit in an oil refinery, an oil switching valve is often installed at the junction before every two coke drums. The valve is typically a four-way valve, one valve comprising one oil inlet and three oil outlets. The oil switching valve is used for switching high-temperature oil from the upstream so that the oil alternately enters the two coke drums. This allows one coke drum to be decoked while the other coke drum is being coked, to ensure continuous production in a delayed coker (not shown).

As shown in fig. 1, in a new delayed coking unit, three coke drums 7 are grouped, two oil switching valves 2 (four-way valves) are used to switch oil, two coke drums 7 are fed and coke is formed, one coke drum is stopped and coke is removed. The oil inlet of each oil switching valve 2 is respectively connected with an oil inlet pipeline 1; the two oil outlets are connected with an oil outlet pipeline 3 respectively, and feed to a coke tower 7 through the oil outlet pipeline 3, and simultaneously carry out delayed coking reaction. A cut-off valve 4 is required to be arranged on an oil outlet pipeline 3 connected with an oil outlet, and a logic interlocking protection relation exists between the cut-off valve 4 and the oil switching valve 2 so as to ensure the feeding operation safety of high-temperature oil. When the number of the oil switching valves 2 is two, four cut-off valves 4 are arranged. One oil outlet of each oil switching valve 2 is respectively connected with a bypass pipeline 5, and the bypass pipeline 5 is connected with a tower top pipeline 9 so as to introduce high-temperature oil into a coke tower 7 for preheating before start-up; a bypass line 5 is provided with a bypass valve 6. The two kinds of oil from the heating furnace respectively enter two oil switching valves 2 through two oil inlet pipelines 1 and then respectively enter three coke towers 7. The delayed coking device uses two oil switching valves 2 (four-way valves) to switch the oil, and mainly has the following problems: (1) the number of the oil switching valves is two, the number of the stop valves is four, the number of the bypass valves is two, the equipment investment is increased, and the complexity and difficulty of oil switching operation are increased. (2) The number of the oil outlet pipelines and the bypass pipelines is large, and the workload of connection and arrangement is large. (3) The oil inlets and the oil outlets of the two oil switching valves are respectively connected with the oil inlet pipeline, the oil outlet pipeline and the bypass pipeline through flanges. The possibility of oil leakage is increased due to the large number of flange connections (eight total). The above problems increase the operating and maintenance costs of a delayed coker for long periods of operation.

Disclosure of Invention

The invention aims to provide an oil switching valve and a using method thereof in a delayed coking device, which solve the problems of the prior art caused by more oil switching valves, cut-off valves, bypass valves, oil outlet pipelines and bypass pipelines and more flange connections, and the problem that a single four-way oil switching valve is not suitable for switching feeding for three coke drums.

In order to solve the problems, the invention adopts the technical scheme that: an oil diverter valve which is characterized in that: the valve is a five-way plug valve and is provided with a valve body, a plug, a valve cover, a valve rod, a packing gland and a valve actuating mechanism, wherein the plug is positioned in an inner cavity of the valve body, the valve rod is fixedly connected with the cock, the oil switching valve is provided with an oil inlet and four oil outlets, the oil inlet is positioned at the bottom of the valve body, the oil outlet is positioned at the side part of the valve body, a cock channel is arranged in the cock, the inlet of the cock channel is positioned at the bottom of the cock, the outlet of the cock channel is positioned on the outer side surface of the cock, the outer side surface of the cock is provided with a cock channel outlet sealing surface around a cock channel outlet, the inner cavity side surface of the valve body is provided with an oil outlet sealing surface around an oil outlet, the valve actuating mechanism comprises a lifting actuating mechanism and a rotating actuating mechanism, the lifting actuating mechanism is used for controlling the lifting of the valve rod and the cock, and the rotating actuating mechanism is used for controlling the rotation of the valve rod and the cock.

The use method of the oil switching valve in the delayed coking device is characterized in that: the delayed coking device takes three coke drums as a group, the three coke drums use an oil switching valve to switch oil, an oil inlet is connected with an oil inlet pipeline, an oil outlet is connected with a bypass pipeline, the other three oil outlets are respectively connected with one coke drum through an oil outlet pipeline, each oil outlet pipeline is provided with a stop valve, and the bypass pipeline is provided with a bypass valve;

when the oil switching valve switches oil, oil from the heating furnace enters an oil inlet pipeline connected with the oil inlet and then enters a cock channel of the oil switching valve from the oil inlet, the oil is switched according to three stages when the delayed coking device continuously produces, in the first stage, the valve rod and the cock are rotated to enable the oil to enter a coke tower through an oil outlet and an oil outlet pipeline connected with the oil outlet pipeline, the oil simultaneously carries out delayed coking reaction, in the second stage, the valve rod and the cock are rotated to enable the oil to enter a second coke tower through another oil outlet and an oil outlet pipeline connected with the oil outlet pipeline, the oil simultaneously carries out the delayed coking reaction, in the third stage, the valve rod and the cock are rotated to enable the oil to enter a third coke tower through a third oil outlet and an oil outlet pipeline connected with the oil outlet pipeline, the delayed coking reaction of oil is performed simultaneously, and the three stages are continuously and circularly performed in sequence.

One scheme of the present invention is that two or more kinds of oil from two or more oil inlet pipelines of two or more heating furnaces enter one oil inlet pipeline connected to the oil inlet of the oil switching valve, are mixed in the oil inlet pipeline, enter the oil switching valve from the oil inlet, and then enter three coke towers respectively.

When the three coke towers need to be preheated before start-up, the valve rod and the cock of the oil switching valve are rotated, so that high-temperature oil enters the bypass pipeline through the oil outlet connected with the bypass pipeline, and enters the three coke towers through the tower top pipeline connected with the bypass pipeline, and the three coke towers are preheated before start-up.

The invention has the following beneficial effects: (1) the oil switching valve special for the delayed coking device is a five-way plug valve, can switch oil for three coke towers, and meets the requirement of the oil switching valve on the delayed coking device. (2) The oil switching valve can realize the sequential actions of lifting, rotating and descending of the valve rod and the cock through the valve actuating mechanism, so that the action process of the oil switching valve is flexible, and the problem of blocking cannot occur. (3) The valve actuating mechanism can be an electric, pneumatic or hydraulic actuating mechanism, and the automatic sequential operation of ascending, rotating and descending of the valve rod and the cock can be realized by using a programmable controller, so that the automatic control of the switching process is realized. (4) In a delayed coking unit with a triple coke drum, only one oil switching valve of the present invention, three shut-off valves and one bypass valve, need be used. The valves are special valves used at high temperature, and the price of each valve is hundreds of thousands to hundreds of thousands, so the equipment investment can be reduced by adopting the invention. Because the number of the valves is less, the complexity and difficulty of oil material switching operation can be reduced, and the process flow is simplified. (5) The number of the oil outlet pipelines and the bypass pipelines is less, and the workload of connection and arrangement is less. (6) And one oil inlet and four oil outlets of one oil switching valve are respectively connected with the oil inlet pipeline, the oil outlet pipeline and the bypass pipeline through flanges. The possibility of oil leakage is reduced due to the smaller number of flange connections (five total). In the invention, one oil inlet pipeline connected with the oil inlet can be respectively connected with one, two or more oil inlet pipelines from one, two or more heating furnaces. Since the above-mentioned line connection can be made by welding, there is no problem of leakage.

The invention is mainly used for a delayed coking device which takes three coke drums as a group in an oil refinery, and oil is switched for the three coke drums (the oil comprises oil used for delayed coking reaction and oil used for preheating the coke drums before start-up). The invention can solve the problems of the existing oil switching method of the delayed coking device and the four-way oil switching valve, and reduce the operation and maintenance cost of the long-period operation of the delayed coking device.

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. The drawings and detailed description do not limit the scope of the invention as claimed.

Drawings

FIG. 1 is a schematic flow diagram of a prior art delayed coker with three coke drums as a battery.

FIG. 2 is a schematic flow diagram of a delayed coker of the present invention utilizing three coke drums.

Fig. 3 is a schematic view of an oil switching valve used in the present invention.

Fig. 4 is a sectional view taken along line a-a in fig. 3.

Fig. 5 is a sectional view taken along line B-B in fig. 4. The tap in figure 5 is rotated to show the complete tap channel.

In fig. 1 to 5, the same reference numerals denote the same technical features.

Detailed Description

Referring to fig. 2, 3, 4 and 5, the delayed coking unit according to the present invention is composed of three coke drums 7, and the three coke drums 7 switch oil using an oil switching valve 2. The oil switching valve 2 is a five-way plug valve and is provided with a valve body 11, a plug 12, a valve cover 17, a valve rod 18, a support 19, a packing 14, a packing gland 10 and a valve actuating mechanism. The plug 12 is located in the inner cavity of the valve body 11 and the valve stem 18 is fixedly connected to the plug 12. The valve cover 17 is fixed to the upper portion of the valve body 11 by bolts, and the bracket 19 is fixed to the valve cover 17 by bolts. The valve stem 18 passes through the center of the bonnet 17, and the packing 14 is arranged in a packing box between the valve stem 18 and the bonnet 17 and is pressed by the packing gland 10.

The oil switching valve is provided with one oil inlet 15 and four oil outlets 16. An oil inlet 15 is located at the bottom of the valve body 11 and an oil outlet 16 is located at the side of the valve body 11. The four oil outlets 16 are positioned on a horizontal plane and are uniformly distributed at equal angles, and the included angle between the axial leads of two adjacent oil outlets 16 is 90 degrees. The tap 12 is provided with a 90 degree turn tap channel inside, with the tap channel inlet at the bottom of the tap 12 and the tap channel outlet on the outside face of the tap 12. A cock channel outlet sealing surface is arranged on the outer side surface of the cock 12 around the cock channel outlet, an oil outlet sealing surface is arranged on the inner cavity side surface of the valve body 11 around the oil outlet 16, and the two sealing surfaces are opposite to each other and are mutually matched in a sealing mode. The outer side surface of the bottom of the cock 12 is provided with a cock channel inlet sealing surface, the position of the bottom of the inner cavity side surface of the valve body 11 corresponding to the cock channel inlet sealing surface is also provided with an inlet sealing surface, and the two sealing surfaces are opposite in pairs and mutually matched when in sealing. The sealing surface is generally a metal hard sealing surface, is formed by adopting a high-temperature resistant surface hardening technology (such as chromium plating, surfacing welding high-temperature resistant hard alloy and the like), and can resist the abrasion of solid particles such as coke powder and the like. The valve body 11, the valve cover 17, the valve rod 18 and the cock 12 can be made of high-temperature resistant materials such as chromium-containing alloy steel, austenitic stainless steel and the like.

The valve actuator includes a lift actuator 20 and a rotation actuator 21. A lift actuator 20 is used to control the lift of the valve stem 18 and the cock 12 and a rotary actuator 21 is used to control the rotation of the valve stem 18 and the cock 12. The lifting actuator 20 and the rotary actuator 21 may be existing electric, pneumatic or hydraulic actuators (preferably electric actuators), with optional spare manual actuators. The lifting actuator 20 and the rotating actuator 21 of the present invention are two independent actuators.

The tap 12 generally comprises an upper inverted frusto-conical body and a lower cylindrical body. The cone angle alpha of the inverted truncated cone is generally 15-30 degrees; the taper angle is large, which can avoid the self-locking of the cock 12 and prevent the locking under high temperature. The outer side surface of the cylinder is provided with a plug channel inlet sealing surface.

Typically, the oil switching valve 2 is provided with a plurality of steam purge connections 13, the steam purge connections 13 being connected to the steam purge channel. The steam purging channels are arranged on the valve body 11 and the valve cover 17, and outlets of the steam purging channels are respectively positioned on the lower surface of the valve cover 17, the side surface of the inner cavity of the valve body 11 and the filler 14. During the operation of the oil switching valve, steam enters the steam purging connecting pipe 13 and flows out from the outlet of each steam purging channel, enters the part of the inner cavity of the valve body 11 between the cock 12 and the valve cover 17, between the side surface of the inner cavity of the valve body 11 and the outer side surface of the cock 12 and the packing 14, can prevent oil containing coke powder from entering the area, and prevents coking and coke powder from leaking. After the oil switching valve 2 is switched in place, steam generally cannot enter the oil inlet pipeline 1 and the oil outlet pipeline 3 through the oil inlet 15 and the oil outlet 16, and cannot leak out of the oil switching valve 2 through the filler 4; thus, the steam cannot flow away, and the amount of steam used can be reduced. In the event of slight leakage from the contacting sealing surfaces, the steam can block the oil containing coke fines from entering the interior cavity of the valve body 11. Even if the oil containing coke powder enters the inner cavity of the valve body 11, the steam can be prevented from leaking out of the oil switching valve 2 through the packing 14.

When the oil switching valve 2 of the present invention is installed, the oil inlet 15 is connected to one oil inlet pipeline 1, and the oil inlet pipeline 1 is connected to one, two, or more (generally one, two, or three) oil inlet pipelines 1 from one, two, or more (generally one, two, or three) heating furnaces, respectively. In fig. 2, one oil inlet line 1 connected to the oil inlet 15 is connected to three oil inlet lines 1 from three heating furnaces. Each heating furnace heats an oil (single oil or mixed oil) and is connected (welded) to an oil inlet line 1 connected to an oil inlet 15 through an oil inlet line 1. An oil outlet 16 of the oil switching valve 2 is connected with a bypass pipeline 5, the bypass pipeline 5 is connected (welded) with an overhead pipeline 9 of the three coke drums 7, and a bypass valve 6 is arranged on the bypass pipeline 5. The other three oil outlets 16 of the oil switching valve 2, each oil outlet 16 is connected with a coke tower 7 through an oil outlet pipeline 3, and each oil outlet pipeline 3 is provided with a stop valve 4. A logic interlocking protection relationship exists between the oil switching valve 2 and the cut-off valve 4; the shut-off valve 4 on the oil outlet line 3 feeding oil to the coke drum 7 is opened and the shut-off valve 4 on the oil outlet line 3 not feeding oil to the coke drum 7 is closed. In fig. 2 (and fig. 1), the oil inlet line 1 is shown by a chain line, the oil outlet line 3 is shown by a thick solid line, and the bypass line 5 is shown by a broken line.

The process of switching oil from the oil switching valve 2 to the three coke drums 7 according to the present invention will be described with reference to fig. 2 to 5. Two or more kinds of oil (three kinds of oil in fig. 2) from two or more oil inlet lines 1 (three oil inlet lines 1 in fig. 2) of two or more heating furnaces (three heating furnaces in fig. 2, not shown) enter one oil inlet line 1 connected to an oil inlet 15 of an oil switching valve 2, are mixed in the oil inlet line 1, and then enter a cock passage of the oil switching valve 2 from the oil inlet 15. The delayed coker is operated continuously with three stages of oil transfer. In the first stage, the valve stem 18 and the cock 12 are rotated to allow the oil to pass through an oil outlet 16 connected to the oil outlet line 3 and the oil outlet line 3 into a coke drum 7, where the oil undergoes a delayed coking reaction. In the second stage, the valve stem 18 and the cock 12 are rotated to allow the oil to pass through the other oil outlet 16 connected to the oil outlet line 3 and the oil outlet line 3 into the second coke drum 7, and the oil is simultaneously subjected to delayed coking reaction. In the third stage, the valve stem 18 and the cock 12 are rotated to allow the oil to pass through the third oil outlet 16 connected to the oil outlet line 3 and the oil outlet line 3 into the third coke drum 7, and the oil is simultaneously subjected to the delayed coking reaction. The three stages are continuously and circularly carried out in sequence; the oil is switched into three coke drums 7 in sequence, the oil reacts in one coke drum 7, and the other coke drum 7 performs decoking operation. The oil gas generated by the delayed coking reaction enters a coking fractionating tower through an overhead pipeline 9, and the removed coke 8 is sent to a coke storage tank.

When the oil is one kind, a heating furnace is used for heating, and the heated oil enters the oil switching valve 2. The process of switching the oil is the same as that described in the previous paragraph, and the detailed description is omitted.

The oil heated by the heating furnace is high-temperature oil, the temperature is generally 500-550 ℃, and the oil is easy to coke. The oil is typically in the form of slurry oil, wax oil, vacuum residue, or other suitable heavy oil.

When the three coke drums 7 need to be preheated before start-up, the valve rod 18 and the cock 12 of the oil switching valve 2 are rotated, so that high-temperature oil enters the bypass pipeline 5 through the oil outlet 16 connected with the bypass pipeline 5, and enters the three coke drums 7 through the tower top pipeline 9 connected with the bypass pipeline 5, and the three coke drums 7 are preheated before start-up.

When the oil switching valve 2 of the invention is in oil inlet, the inlet of the cock channel is always communicated with the oil inlet 15, and the outlet of the cock channel is always communicated with one oil outlet 16, thus forming a closed oil channel. Referring to fig. 3, 4 and 5, in each stage of switching the coking-prone oil, the lifting actuator 20 first lifts the valve stem 18 and the cock 12 (for example, by about 1-2 mm), then the rotating actuator 21 rotates the valve stem 18 and the cock 12, and the cock 12 rotates 90 degrees, so that the cock channel outlet is communicated with one oil outlet 16 and the other oil outlet 16; then the lifting actuator 20 controls the valve rod 18 and the cock 12 to descend, so that the sealing surface of the outlet of the cock channel and the sealing surface of the oil outlet 16 communicated with the outlet of the cock channel are contacted with each other, pressed and sealed, and the oil switching valve 2 completes one stage of one oil switching operation (including oil switching for preheating the coke tower 7 before starting operation).

Claims

1. A use method of an oil switching valve in a delayed coking device is characterized in that: the oil switching valve is a five-way plug valve and is provided with a valve body (11), a plug (12), a valve cover (17), a valve rod (18), a packing (14), a packing gland (10) and a valve actuating mechanism, the plug (12) is positioned in an inner cavity of the valve body (11), the valve rod (18) is fixedly connected with the plug (12), the oil switching valve is provided with an oil inlet (15) and four oil outlets (16), the oil inlet (15) is positioned at the bottom of the valve body (11), the oil outlet (16) is positioned at the side part of the valve body (11), a plug channel is arranged inside the plug (12), the plug channel inlet is positioned at the bottom of the plug (12), the plug channel outlet is positioned on the outer side surface of the plug (12), a plug channel outlet sealing surface is arranged on the outer side surface of the plug (12) around the plug channel outlet, an oil outlet sealing surface is arranged on the inner cavity side surface of the valve body (11) around the oil outlet (16), the valve actuating mechanism comprises a lifting actuating mechanism (20) and a rotating actuating mechanism (21), the lifting actuating mechanism (20) is used for controlling the lifting of the valve rod (18) and the cock (12), and the rotating actuating mechanism (21) is used for controlling the rotation of the valve rod (18) and the cock (12);

the use method of the oil switching valve in the delayed coking device comprises the following steps: the delayed coking device takes three coke drums (7) as a group, the three coke drums (7) use an oil switching valve to switch oil, an oil inlet (15) is connected with an oil inlet pipeline (1), an oil outlet (16) is connected with a bypass pipeline (5), the rest three oil outlets (16), each oil outlet (16) is connected with one coke drum (7) through an oil outlet pipeline (3), each oil outlet pipeline (3) is provided with a stop valve (4), and the bypass pipeline (5) is provided with a bypass valve (6);

when the oil switching valve switches oil, oil from a heating furnace enters an oil inlet pipeline (1) connected with an oil inlet (15) and then enters a cock channel of the oil switching valve from the oil inlet (15), the oil is switched according to three stages when the delayed coking device is continuously produced, the first stage is to rotate a valve rod (18) and a cock (12) to enable the oil to enter a coke tower (7) through an oil outlet (16) and an oil outlet pipeline (3) connected with an oil outlet pipeline (3), the oil is simultaneously subjected to delayed coking reaction, the second stage is to rotate the valve rod (18) and the cock (12) to enable the oil to enter a second coke tower (7) through another oil outlet (16) and an oil outlet pipeline (3) connected with the oil outlet pipeline (3), the oil is simultaneously subjected to delayed coking reaction, and the third stage is to simultaneously perform delayed coking reaction, the oil is fed into a third coke drum (7) through a third oil outlet (16) connected to the oil outlet line (3) and the oil outlet line (3) by rotating a valve stem (18) and a cock (12), and the oil is subjected to a delayed coking reaction simultaneously, and the three stages are continuously circulated in sequence.

2. The method of claim 1, wherein: more than two kinds of oil from more than two oil inlet pipelines (1) of more than two heating furnaces enter one oil inlet pipeline (1) connected with an oil inlet (15) of an oil switching valve, are mixed in the oil inlet pipeline (1), enter the oil switching valve from the oil inlet (15), and then enter three coke towers (7) respectively.

3. The method according to claim 1 or 2, characterized in that: and rotating a valve rod (18) and a cock (12) of the oil switching valve to enable oil with the temperature of 500-550 ℃ to enter the bypass pipeline (5) through an oil outlet (16) connected with the bypass pipeline (5), and enter the three coke drums (7) through a tower top pipeline (9) connected with the bypass pipeline (5) to preheat the three coke drums (7) before start-up.