A dual-medium auxiliary sealing device for flat gate valves

Abstract

A dual-medium auxiliary sealing device for a flat gate valve includes a first sealing chamber sealed by a liquid sealing medium and a second sealing chamber sealed by a gaseous sealing medium. The first sealing chamber is located between the valve body and the valve plate. A sealing medium with a pressure greater than the operating pressure at the bottom of the reactor where the flat gate valve is located is continuously injected into the first sealing chamber until the first sealing chamber is filled, achieving a first-medium auxiliary seal. The second sealing chamber is a pressure-bearing valve chamber surrounded by the valve body, small shell, and large shell. A gaseous sealing medium with a pressure greater than the first sealing chamber is continuously injected into the second sealing chamber to achieve a second-medium auxiliary seal. This technology improves equipment performance, reduces the impact on product quality, and optimizes the auxiliary sealing function of existing equipment (especially in needle coke production).

Description

Technical Field

[0001] The invention relates to high-temperature flat gate valve equipment in the field of delayed coking in the petrochemical industry, in particular to a dual-medium auxiliary sealing device for a flat gate valve. Background Art

[0002] At present, there are more than 100 sets of conventional coke delayed coking units in China that use vacuum residue oil or vacuum residue oil blended with asphalt and catalytic oil slurry as raw materials, as well as conventional coke delayed coking units that use heavy crude oil, heavy fuel oil or coal tar as raw materials.

[0003] In recent years, with the rapid development of social economy, the domestic demand for needle coke has increased significantly. As a petroleum product with high added value, needle coke has once again become one of the hot topics in the petrochemical field. Not only are existing production companies competing to expand production capacity through technological transformation, but traditional petrochemical companies such as Shanghai Petrochemical, Maoming Petrochemical, and Jinling Petrochemical are also interested in entering the needle coke market.

[0004] To improve the automation level of the unit, the coke tower bottom valve (bottom cover) in coking units now generally adopts a flat gate valve structure as a dedicated device for automatic opening and closing of the coke tower. The production of needle coke is closely related to the quality indicators of the needle coke product, and further puts forward higher performance requirements for the bottom valve.

[0005] The coking process is a critical stage in needle coke production. After pretreatment, the raw needle coke rapidly heats up before entering the coke drum, undergoing reactions such as cracking and condensation. During coking, pressure is applied to promote the growth and fusion of small mesophase globules, resulting in high-performance delayed coke, also known as green coke. Needle coke production requires precise control of process parameters such as coking temperature, coking pressure, coking cycle ratio, and calcination temperature.

[0006] Coking temperature is one of the most critical factors affecting needle coke quality. At lower temperatures, mesophase transformation is difficult to occur. Excessively high temperatures cause pellets to fuse and coalesce immediately upon formation, preventing them from fully growing. This makes it difficult to obtain a broad-based mesophase and produce needle coke with a low expansion coefficient. Repeated experimentation is required to determine the optimal thermal transformation temperature. Increasing coking tower pressure increases coke yield and density, but excessive pressure reduces the gas escape rate, making it difficult for the raw material to form a needle shape. Pressure regulation is typically employed—adjusting the pressure to allow sufficient gas escape time before solidification, thus facilitating the formation of a needle-like structure. In addition to temperature and pressure, reaction time also significantly influences the coking process. Prolonging the reaction time allows the system to accumulate more energy, allowing the formed mesophase macromolecules to further aggregate and fuse to form larger spheres. Time often interacts with temperature to influence mesophase changes. Within the appropriate temperature range, longer residence time promotes pellet growth and fusion. Optimizing and improving existing delayed coking units is currently a key task in improving delayed coking technology.

[0007] By further optimizing and improving the product structure and sealing technology of the common petroleum coke bottom valve in the existing coking unit, it can meet the needs of the needle coke production process, improve the equipment performance of the bottom valve, and enhance the control level of the needle coke unit equipment production system.

[0008] Currently, the bottom capping machine boasts a simple structure and excellent manufacturing processability. However, in actual production, the deformation of the metal seal caused by high-temperature media requires effective steam auxiliary sealing to compensate. Excessive steam entering the reaction tower can affect the quality of needle coke production. Therefore, optimizing and improving the existing sealing structure requires the use of other media to supplement the sealing of the equipment, achieving even better performance. Summary of the Invention

[0009] In order to solve the above technical problems, improve equipment performance and reduce the impact on product quality, the auxiliary sealing function of existing equipment (especially needle coke production) is optimized, and a dual-medium auxiliary sealing device for flat gate valves is proposed.

[0010] In order to achieve the above technical objectives, the technical solution adopted is: a dual-medium auxiliary sealing device for a flat gate valve, comprising a first sealing chamber sealed by a liquid sealing medium and a second sealing chamber sealed by a gas sealing medium. The first sealing chamber is arranged between the valve body and the valve plate, and a sealing medium with a pressure greater than the operating pressure at the bottom of the reactor where the flat gate valve is located is continuously injected into the first sealing chamber until the first sealing chamber is filled to realize the first medium-assisted sealing. The second sealing chamber is a pressure-bearing valve chamber surrounded by the valve body, the small shell and the large shell. A gas sealing medium with a pressure greater than the first sealing chamber is continuously injected into the second sealing chamber to realize the second medium-assisted sealing.

[0011] The first sealing chamber is composed of the collecting ring groove on the valve seat sealing surface and the valve plate sealing surface. Annular collecting ring grooves are provided on the upper and lower surfaces of the valve seat. Multiple channels connecting the upper and lower collecting ring grooves are provided in the valve seat. The first medium-assisted sealing is achieved by injecting liquid sealing medium into the collecting ring groove on the upper surface of the valve seat.

[0012] A flow channel is provided in the valve body, the inlet of the flow channel is connected to the outside for injecting liquid sealing medium, and the outlet of the flow channel is provided corresponding to the collecting ring groove on the upper surface of the valve seat.

[0013] The liquid sealing medium is wax oil.

[0014] The gas sealing medium is steam.

[0015] The first sealing chamber pressure, the second sealing chamber pressure and the operating pressure at the bottom of the reactor are interlocked and controlled. The medium pressure control hardware is realized by two separate control module components. The two control module components respectively control the pressure and flow supply of the liquid sealing medium and the gas sealing medium. The two control module components respectively assume the dynamic adjustment function control of the sealing medium pressure and flow; the pressure difference between the two control module components is set according to the requirements of the sealing control.

[0016] The beneficial effects of the present invention are as follows: the flat gate valve adopts a dual-medium auxiliary sealing structure and control technology, which can meet the process production needs of needle coke products and effectively improve the automation level of flat gate valve equipment in the needle coke production field. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the present invention.

[0018] Figure 2 It is a medium sealing pressure trend diagram of the present invention.

[0019] Figure 3 It is a cross-sectional view of the housing sealing medium channel of the present invention.

[0020] Figure 4 It is a cross-sectional view of the medium channel of the first sealed cavity of the present invention.

[0021] Figure 5 It is a cross-sectional view of the flow channel of the present invention.

[0022] Figure 6 It is an axonometric view of the valve seat of the present invention.

[0023] Figure 7 It is an enlarged cross-sectional view of the valve seat of the present invention.

[0024] Figure 8 It is the joint control principle diagram of the present invention.

[0025] Figure 9 It is an axonometric view of the sealing medium circuit of the present invention.

[0026] In the figure: 1. small shell, 2. support seat, 3. reactor, 4. valve seat, 5. valve plate, 6. valve body, 7. large shell, 8. flow channel, 9. interface flange, 10. collecting ring groove, 11. gate valve, 12. orifice plate, 13. transmitter, 14. regulating valve, 15. gate valve, 16. stop valve, 17. one-way valve, 18. first sealing chamber, 19. second sealing chamber. DETAILED DESCRIPTION

[0027] like Figure 1 、 Figure 2 As shown, a dual-medium auxiliary sealing device for a flat gate valve includes a first sealing chamber 18 sealed by a liquid sealing medium and a second sealing chamber 19 sealed by a gas sealing medium. The first sealing chamber 18 is arranged between the valve body 6 and the valve plate 5. A sealing medium with a pressure greater than the operating pressure at the bottom of the reactor where the flat gate valve is located is continuously injected into the first sealing chamber 18 until the first sealing chamber 18 is filled to achieve a first medium auxiliary seal between the valve body 6 and the valve plate 5. The second sealing chamber 19 is a pressure-bearing valve chamber surrounded by the valve body 6, the small shell 1 and the large shell 7. A gas sealing medium with a pressure greater than the first sealing chamber 18 is continuously injected into the second sealing chamber 19 to achieve a second medium auxiliary seal.

[0028] like Figure 4 As shown, the valve body 6 is a conventional component of a flat gate valve, including a valve body, a valve seat 4 connected to or located on the valve body, a support seat 2 and other components.

[0029] The large and small shells can be formed by casting or welding, and the required medium channel structure can be cut and processed according to requirements.

[0030] like Figure 3 As shown, the second sealed cavity 19 is a conventional structure of a flat gate valve, which communicates with the small shell, the large shell and the valve body, and is surrounded by the outside of the first sealed cavity 18.

[0031] like Figure 4 、 Figure 6As shown, the first sealing chamber 18 is realized by the valve seat 4, and the valve seat is forged by high-temperature alloy steel. The collecting ring groove 10 and the channel on the valve seat 4 are formed by cutting. The upper surface sealing surface of the valve seat 4 is in contact with the valve body 6, and the lower surface sealing surface of the valve seat is in contact with the valve plate 5. Annular collecting ring grooves 10 are provided on the upper and lower surfaces of the valve seat 4, and multiple channels connecting the upper and lower collecting ring grooves 10 are provided in the valve seat 4. By injecting liquid sealing medium into the collecting ring groove 10 on the upper surface of the valve seat 4, the first medium auxiliary seal is realized. The liquid sealing medium first flows into the collecting ring groove on the upper surface, and then flows into the collecting ring groove on the lower surface through the channel to form a sealing defense line.

[0032] like Figure 5 As shown, a flow passage 8 is provided within the valve body 6. The inlet of the flow passage 8 is connected to the outside for injection of a liquid sealing medium. The outlet of the flow passage 8 corresponds to the collecting ring groove 10 on the upper surface of the valve seat. The inlet of the flow passage 8 can be connected to an interface flange 9 for connection to an external pipeline. The interface flange 9 is provided on the valve body 6. The flow passage 8 can only be connected to the first sealing cavity 18 and will not divert flow to other parts. The flat gate valve shell can be manufactured by casting or welding, and the flow passage 8 is cut and processed according to requirements.

[0033] The liquid sealing medium is wax oil or diesel, which is a by-product obtained from the reactor (coke drum). The gaseous sealing medium is steam.

[0034] like Figure 8 As shown, the pressures of the first sealed chamber 18, the second sealed chamber 19, and the reactor bottom operating pressure are jointly controlled. The pressure control hardware for the media is implemented by two separate control module assemblies, each controlling the pressure and flow of the liquid and gaseous sealing media, respectively. Each control module assembly dynamically regulates the pressure and flow of the respective sealing media. A pressure differential is established between the two control modules based on the sealing control requirements, implementing gradient management and ensuring the servo requirements of the reactor's process production (variable pressure operation). The flat gate valve requires that the pressure of the sealing medium (e.g., wax oil) in the first sealed chamber be maintained at a constant value higher than the reactor bottom operating pressure ΔP. The housing requires that the pressure of the sealing medium (e.g., steam) in the second sealed chamber be maintained at a constant value higher than the pressure of the first sealed valve chamber (wax oil) ΔP. When the pressure at the reactor bottom is detected as P, the supply pressure of the liquid sealing medium is P + ΔP, and the supply pressure of the gaseous sealing medium is P + ΔP'. ΔP' > ΔP, and the most convenient design result is ΔP' = 2ΔP. The pressure difference requirement is to ensure that the medium raw materials in the reactor will not leak into the bottom valve cavity and cause seal failure.

[0035] like Figure 8As shown in the pipeline instrument process control principle diagram, the dual-media auxiliary sealing control technology consists of two different sealing medium control loops. Each set of control module components includes gate valves, stop valves, one-way valves, regulating valves, pressure transmitters, differential pressure transmitters, orifice plates, pressure gauges and other control elements. Each set of control module components has the function of dynamic adjustment of pressure and flow, display, measurement, pressure setting and other control means. The two sets of control module components perform pressure interlock control and conduct continuous dynamic measurement and comparison with the bottom operating pressure of the coke tower (reactor) to ensure the realization of the loop auxiliary sealing function. Figure 8 PY is the pressure difference calculation module, PV is the regulating valve, PT is the pressure transmitter, PG is the pressure gauge, and FT is the flow transmitter.

[0036] Example 1:

[0037] like Figure 1 As shown, a dual-medium auxiliary sealing device for flat gate valves mainly consists of a small shell 1, a valve body 6 and a large shell 7 together to form a pressure-bearing valve chamber, which is the second sealing chamber 19 of the equipment. Figure 3 As shown in FIG. 1 , a liquid sealing medium (such as steam) is injected into the second sealing cavity 19 for sealing.

[0038] like Figure 4 As shown, the first sealed chamber 18 is located at the original sealing position where the valve body and valve plate meet. The valve seat on valve seat 4 and valve plate 6 together form a pressure-bearing sealed chamber, which serves as the equipment's first sealed chamber. A sealing medium (such as wax oil) is injected through interface flange 9 and flows through flow channel 8 to the sealed chamber, sealing the medium feedstock and preventing the feedstock oil in the coke drum from leaking through the sealing surface.

[0039] like Figure 5 、 6 As shown in Figure 7, the seal of the first sealing chamber starts from the interface flange, passes through the flow channel to the upper collecting ring groove, and then passes through the channel to the lower surface collecting ring groove until it is filled and reaches the set pressure.

[0040] like Figure 8 、 9 As shown, the sealing medium circuit includes pipelines, a pipeline gate valve 11, an orifice plate 12 for flow restriction, a transmitter 13 for measuring pipeline pressure, a medium flow control valve 14, a pipeline drain gate valve 15, a bypass stop valve 16, a check valve 17, a pressure gauge, and other components. Transformer 13 transmits the sealing medium pressure signal to the control system in real time. After processing, the system sends a signal to the regulating valve 14 to set the pressure, ensuring that the dual-medium auxiliary seal meets the set pressure differential.

Claims

1. A dual-medium auxiliary sealing device for a flat gate valve, characterized by: The invention comprises a first sealing cavity (18) sealed by a liquid sealing medium and a second sealing cavity (19) sealed by a gas sealing medium. The first sealing cavity (18) is arranged between a valve body (6) and a valve plate (5). A sealing medium having a pressure greater than the operating pressure at the bottom of the reactor where the flat gate valve is located is continuously injected into the first sealing cavity (18) until the first sealing cavity (18) is filled to realize auxiliary sealing of the first medium between the valve body (6) and the valve plate (5). The second sealing cavity (19) is a pressure-bearing valve cavity surrounded by the valve body (6), a small shell (1) and a large shell (7). A gas sealing medium having a pressure greater than the pressure of the first sealing cavity (18) is continuously injected into the second sealing cavity (19) to realize auxiliary sealing of the second medium.

2. A dual-medium auxiliary sealing device for a flat gate valve according to claim 1, characterized in that: The first sealing cavity (18) is composed of a collecting ring groove (10) on the sealing surface of the valve seat (4) and a valve plate sealing surface. Annular collecting ring grooves (10) are provided on both the upper and lower surfaces of the valve seat (4). A plurality of channels connecting the upper and lower collecting ring grooves (10) are provided in the valve seat (4). By injecting a liquid sealing medium into the collecting ring groove (10) on the upper surface of the valve seat (4), a first medium-assisted seal is achieved.

3. A dual-medium auxiliary sealing device for a flat gate valve according to claim 2, characterized in that: A flow channel (8) is provided in the valve body (6), the inlet of the flow channel (8) is connected to the outside for injecting liquid sealing medium, and the outlet of the flow channel (8) is provided corresponding to the collecting ring groove (10) on the upper surface of the sealing ring.

4. A dual-medium auxiliary sealing device for a flat gate valve according to claim 1, 2 or 3, characterized in that: The liquid sealing medium is wax oil or diesel.

5. A dual-medium auxiliary sealing device for a flat gate valve according to claim 1, characterized in that: The gas sealing medium is steam.

6. A dual-medium auxiliary sealing device for a flat gate valve according to claim 1, characterized in that: The pressure of the first sealing chamber (18), the pressure of the second sealing chamber (19) and the operating pressure at the bottom of the reactor are interlocked and controlled. The pressure control hardware of the medium is realized by two sets of independent control module components. The two sets of control module components respectively control the pressure and flow supply of the liquid sealing medium and the gas sealing medium. The two sets of control module components respectively assume the dynamic regulation function control of the pressure and flow of the sealing medium. The pressure difference between the two sets of control module components is set according to the requirements of the sealing control.

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