VALVE SEALING SYSTEMS AND METHODS.

Abstract

Some aspects of the present invention relate to a sealing system for a decapitation or isolation valve in a petroleum refining process. Some aspects relate to a bellows seal to prevent the leakage of petroleum products and steam into the valve. Some aspects relate to a restrictor to limit the movement of a dynamic seat relative to a seat base structure.

Description

VALVE SEALING SYSTEMS AND METHODS MA / t / ZUZ I / UOUZZU FIELD OF INVENTION The invention relates in general to methods and systems for sealing valves. BACKGROUND OF THE INVENTION Oil refining operations that process crude oil typically produce residual oils of little value. The value of these residual oils can be increased through a process known as delayed coking. When processed in a delayed coker, the residual oils are heated in a furnace to a temperature sufficient to cause destructive distillation. In this process, a substantial portion of the residual oil is converted, or cracked, into usable hydrocarbon products, while the remainder becomes a residual petroleum byproduct that is pumped into a large vessel known as a coke drum. Coke production is a batch process. Each delayed coking unit typically contains more than one coke drum. In delayed coking, the feedstock is the typical residue from vacuum distillation columns and often includes other heavy oils. The feedstock is heated as it is fed into one of the coke drums. The feedstock arrives at a coke drum at a temperature ranging from 465.5 degrees Celsius (870 degrees Fahrenheit) to 487.7 degrees Celsius (910 degrees Fahrenheit). The typical top pressure of the drum ranges from 15 to 35 PSIG. The coke feedstock is deposited as a hot liquid slurry into a coke drum. Under these conditions, cracking occurs, and the lighter fractions produced exit the top of the coke drum and are sent to a fractionation tower where they are separated into vapor and liquid products.A solid residue called coke is also produced and remains inside the drum. When a coke drum is filled, residual oil from the furnace is diverted to another coke drum. When a coke drum is filled to the desired capacity, and after the feedstock is diverted to another drum, steam is typically introduced into the drum to release hydrocarbon vapors from the solid material. The material remaining in the coke drum cools and tempers. Solid coke forms as the drum cools and must be removed for reuse. While the coke cools in one drum and the cooled solid coke is being removed, a second drum is used to receive the continuous production of coke feedstock as part of the delayed coking process. The use of multiple coke drums allows the refinery to operate the furnace and fractionation tower continuously.The drum change frequency varies between 10 and 24 hours. In typical coking operations, dramatic heat variations occur in the components of the coking process. For example, a coke drum is filled with the incoming byproduct at approximately 482.2 degrees Celsius (900 degrees Fahrenheit) and is subsequently cooled after being tempered to near-ambient temperatures. It is not surprising that this repetitive thermal cycling can create or cause significant problems, including severe variations in heat distribution across various components of the valve system. The heated residual byproduct used in coking operations comes into contact not only with the coke drum but also with valve components and seats. This heating and subsequent cooling can cause the expansion of various elements within a valve system.As mentioned previously, the delayed coking process typically involves at least two vessels. While one is being filled, the other is being purged of material and prepared to receive another batch of byproduct. Thus, during the shutdown cycle, when one vessel is being purged of its contents, it will cool down and return to a state of equilibrium. This cyclical pattern of dispensing hot residual byproduct into a cooler coke drum and the subsequent cooling of the byproduct is what leads to thermal differentials and stress within the coke drum, a valve, valve parts, and piping. This cyclical loading and unloading, and the stress and release of stress on a coke drum, valve, or piping, is called thermal cycling. Thermal cycling often leads to the weakening or fatigue of a coke drum, valve, and its parts, which can result in a reduced service life for the components.Uneven heat distribution or thermal variations between the different components of the seat system can lead to a decrease in the longevity of the valve components and valve body. Furthermore, since coke is formed under pressure, the decoking valve must form a seal to allow pressure to build up inside the coke drum. This seal is typically formed using tight tolerances between the decoking valve components, such as between the seats and the shim. However, these tight tolerances increase the force required to slide the shim between the seats to open and close the valve. Additionally, due to this pressure, it is common practice to pressurize the internal compartments of the decoking valve, for example, by supplying steam to them. If a decoking valve does not provide a good seal, large quantities of steam will escape, increasing the total amount of steam required for production. In many cases, the cost of supplying steam to pressurize the valve can be significant.Consequently, valves that prevent excessive steam leakage provide additional economy to the system. In addition to decoking and deheading applications, other petroleum refining applications may utilize similar valve technology. For example, isolation valves are commonly used to control the flow of hydrocarbon products. These applications include decoking valves, diverter valves, transfer line valves, and others. These applications may also require vapor pressure in the valve body to compensate for line pressure and prevent the flow of hydrocarbon products into the valve. These valves can also benefit from superior sealing to prevent vapor loss and unnecessary valve maintenance. BRIEF DESCRIPTION OF THE INVENTION The present invention relates to valve systems for petroleum product pipelines and decoking and deheading valve applications. The present invention relates, in particular, to sealing and retention systems to prevent vapor loss while maintaining a proper seal to prevent product leakage. These and other features and advantages of the present invention will be established or made more evident in the following description and in the appended claims. The features and advantages can be realized and obtained by means of the instruments and combinations specifically mentioned in the appended claims. Furthermore, the features and advantages of the invention can be learned through the practice of the invention or will be obvious from the description, as set forth below. BRIEF DESCRIPTION OF THE DRAWINGS The objects and features of the present invention will become more evident from the following description and the accompanying claims, taken in conjunction with the accompanying drawings. It being understood that these drawings represent only typical embodiments of the invention and should therefore not be considered limiting of its scope, the invention will be described and explained in greater specificity and detail by means of the accompanying drawings, in which: Figure 1 shows the components of an exemplary valve, which may comprise elements of the embodiments of the present invention. Figure 2 shows an enlarged view of the internal components of a decapitating valve, which may comprise elements of the embodiments of the present invention. Figure 3 shows a three-dimensional cross-sectional view of the seat assembly of an exemplary valve. Figure 4 shows a cross-section of an embodiment of the present invention comprising a restrictor and a bellows seal. MA / t / ZUZ I / UOUZZU Figure 5 shows a perspective cross-section of an embodiment of the present invention comprising the restrictor and the bellows seal; and Figure 6 shows a cross-section of an embodiment of the present invention comprising a restrictor. DETAILED DESCRIPTION OF THE INVENTION The embodiments of the present invention are described below. It is expected that the present invention may take many other forms; therefore, the following disclosure is intended to be illustrative and not limiting, and the scope of the invention should be determined by reference to the appended claims and their equivalents. The embodiments of the present invention can be used in various types of valves used in the petroleum refining industry. Figure 1 illustrates an exemplary valve type. This is an example of a de-heading valve 100 typically used in a decoking process. This exemplary valve 100 comprises a main body 101 that is usually detachably attached to an upper bonnet 102. The upper bonnet 102 provides a gas-tight or pressurizable compartment for receiving at least a portion of a shim 104 during operation. A lower bonnet 103 can also be detachably attached to the main body 101 and can also provide a gas-tight and pressurizable compartment for receiving at least a portion of the shim 104. The main body 101 can include main line flanges 105 for coupling main line pipes whose flow can be controlled by the valve 100.The exemplary valve 100 may also comprise additional components 106 for actuating the shim 104. During an actuation process of the valve 100, the shim 104 slides within the main body 101 to permit or prevent flow in a main line (not shown) coupled to the main line flanges 105. During this actuation, the shim 104, or parts thereof, may enter and exit the upper and lower bonnets 102, 103. Figure 2 is an exploded view of some internal components of an exemplary valve 200. These components comprise a shim 205, which is typically a plate-shaped device with a shim hole or void 206 inside. This exemplary valve 200 also comprises the seat frame 207 and seat supports 208A and 208B. During opening, the shim 205 slides vertically (as illustrated in Figure 2) to align the shim 206 void with the corresponding holes or voids in the frame 207, supports 208A and 208B, and any connected piping, drum, or other equipment. This alignment of voids allows the flow of liquids and gases in the piping, drum, or other connected equipment. This alignment is shown in the configuration of Figure 2. MA / I / UOUZZU During opening, the slat 205 slides vertically (as illustrated in Figure 2) to align the solid plate area 210 with the corresponding holes or spaces in the frame 207, the supports 208A and 208B, and any attached pipes, drums, or other equipment. This alignment of the solid plate area 210 with the empty spaces prevents the flow of liquids and gases into the pipes, drums, or other attached equipment. Some embodiments of the present invention can be described with reference to Figure 3. Figure 3 is a perspective view of a cross-section through the exemplary headless valve 300. This exemplary valve comprises a main body 301 comprising an upper main line flange 302 and a lower main line flange 303 for joining the main line pipe (not shown). Inside the upper main line flange 302 is an upper seat assembly 304 for sealing the valve 300 against its shim (not shown for clarity). The valve 300 also comprises a lower seat assembly 305 for sealing the valve 300 against its shim (not shown). The shim of the valve 300, during operation, slides between the upper seat assembly 304 and the lower seat assembly 305, while the seats provide a seal against leakage of steam and line products. Figure 4 illustrates a cross-sectional view of an exemplary seat assembly 400, which can be used in a de-coking and de-heading valve, an isolation valve, or similar devices. This exemplary seat assembly 400 comprises a seat base structure 401 configured and shaped to engage a main valve body such as the main valve body 301. In one exemplary embodiment, the seat base structure 401 is connected to the main valve body 301 by a static connection, such that the seat base structure 401 remains in a static, motionless orientation relative to the main body 301. The seat assembly 400 further comprises an inner liner 403 that can follow the contour of the main pipe, a de-coking drum, or another coupled component.The inner liner 403 is statically coupled to the seat base structure 401 so that it does not move relative to the main valve body during valve actuation. The inner liner 403 may be coupled to the seat base structure 401 by a compression friction fit, or it may simply be held in its static position by means of a tab or other fitting that is bolted or otherwise attached adjacent to the inner liner 403, forcing it against a projection 418 on the seat base structure 401. The seat assembly 400 further comprises a dynamic seat 402 capable of movement relative to the seat base structure 401 and the inner lining 403. The dynamic seat 402 can be movably coupled to the seat base structure 401. MA / t / ZUZ I / UOUZZU by means of a series of structures and connections, which may include springs and restrictors. In one exemplary embodiment, the dynamic seat 402 is deflected from the seat base structure 401 by an assembly of springs (not shown in Figure 4) compressed between the dynamic seat 402 and the seat base structure 401. These springs can be compressed in corresponding recesses in both the seat base structure 401 and the dynamic seat 402, thereby forcing the dynamic seat 402 away from the seat base structure 401. This deflection or force, in one exemplary embodiment, can be directed in a direction parallel to a centerline 420 of a connected pipe or drum or perpendicular to the face of the valve shim (the vertical direction in Figure 4). The movement of the dynamic seat 402 with respect to the seat base structure 401 can be limited or restricted by the restrictor 405, which is attached to a base recess 406 in the seat base structure 401 and to a seat recess 407 in the dynamic seat 402. The restrictor 405 can comprise one or more base tabs of the restrictor 409 and one or more seat tabs of the restrictor 408, which are shaped to connect the base protrusion 410 and the seat protrusion 411. This connection between the base tab of the restrictor 409 and the base protrusion 410, and between the seat tab of the restrictor 408 and the seat protrusion 411, restricts the movement of the dynamic seat 402 with respect to the seat base structure 401. Consequently, in these embodiments, the dynamic seat 402 deviates from the structure of seat base 401 by means of compressed springs, while being held in place by the restrictor 405.Restrictor 405 holds dynamic seat 402 in place relative to seat base structure 401 when dynamic seat 402 is not in contact with a slat (not shown). However, when dynamic seat 402 is in contact with a slat and is compressed against seat base structure 401 beyond the limit of restrictor 405, dynamic seat 402 is allowed to flex with the contour of the slat it contacts, thus creating a tighter and more efficient seal. Some embodiments of the present invention may comprise a seat bellows recess 414 and a base bellows recess 413. This chamber contains a bellows 415 that connects to the seat base structure 401 and the dynamic seat 402, forming a flexible seal between these structures. In some embodiments, the bellows 415 may be welded to the seat base structure 401 and the dynamic seat 402. In some embodiments, the bellows 415 may be composed of a metal that cannot be directly welded to the seat base structure 401 and / or the dynamic seat 402 without special procedures. In this case, these embodiments may comprise a seat chloride pass-through layer 416 and / or a chloride pass-through layer of MA / t / ZUZ I / UOUZZU base 417 where compatible metals can be welded or otherwise deposited to allow more efficient welding of the bellows 415 to the seat base structure 401 and / or the dynamic seat 402. When the bellows 415 is coupled to the seat base structure 401 and the dynamic seat 402, the dynamic seat 402 is permitted to move relative to the seat base structure 401 through flexing of the bellows 415. However, the bellows 415 prevents the passage or escape of steam and other gases or fluids through the interface between the seat base structure 401 and the dynamic seat 402. In a preferred embodiment, the 415 bellows may be made of an Inconel alloy. In another embodiment, the 415 bellows may be made of a Monel alloy. Some embodiments of the present invention can be described with further reference to Figure 4. These embodiments comprise one or more packings 412 recessed into the dynamic seat 402. These packings 412 may be provided with packing material 404 to provide a sliding seal against leakage of gases and liquids from inside the pipe, drum, or other vessel served by the valve. The use of the packings 412 and packing material 404 allows the inner liner 403 to remain stationary while the dynamic seal 402 slides to accommodate variations in the slat plate, at the same time preventing fluid leakage through the joint between them. Some embodiments of the present invention can be described with reference to Figure 5. Figure 5 is a cross-section through the seat assembly 400 at the position of a restraint 405. From this view, it can be seen that one of the functions of the restraint 405 is to prevent the dynamic seat 402 from moving away from the seat base structure 401. The springs 510 can be compressed between the seat base structure 401 and the dynamic seat 402 to repel the dynamic seat from the seat base structure 401. However, this movement induced by the spring forces must be restricted to prevent the disassembly of the seat assembly 400 and the unwanted movement of the dynamic seat 402.This can be affected by the restraints 405, comprising restraint tabs 408 and 409 that join the base shoulder 410 and the seat shoulder 411 to limit or restrict the movement of the dynamic seat 402 away from the seat base structure 401 in a direction parallel to the axis 420 or perpendicular to the seat face 419. This joining prevents the seat base structure 401 from moving in direction 501A and prevents the dynamic seat 402 from moving in direction 501B. Similarly, the restrictor 405 can prevent movement in the opposite direction, which can be described with reference to Figure 6. In these embodiments, the restrictor 405 has a length between tabs 603, which is the distance between the inside of the MA / t / ZUZ I / UOUZZU tabs, and an overall length 601, which is the distance between the outer edges of the tabs. These distances can be specifically set to restrict the movement of the dynamic seat 402 relative to the seat base structure 401. For example, the length between tabs 603 can be set to be greater than the distance between the outer edges of the seat shoulder 411 and the base shoulder 410 – distance 604. This difference in distances or lengths allows the dynamic seat 402 to move to an outer limit of the seat base structure 401. Similarly, the overall length 601 of the restrictor 405 can be set to a specific value relative to the sizes of the seat recess 407 and the base recess 406. This length ratio can limit the minimum distance between the seat base structure 401 and the dynamic seat 402.This limitation can prevent the crushing of the 510 springs, the 415 bellows, and other parts of the seat assembly. In some embodiments, the restrictor 405 can also restrict movement in yet another direction. As shown in Figures 3 and 5, the seat assembly 400 can be circularly ring-shaped around a central axis 420. In this configuration, the seat base structure 401 can rotate about the axis 420 relative to the position of the dynamic seat 402. This rotation is illustrated as directions 503A and 503B in Figure 5. This relative rotation can jam the springs and other valve parts and is generally undesirable. Consequently, this relative movement 503A, 503B can be restricted or avoided by paying close attention to the relative sizes of the widths of the restrictors 605 and 607 with respect to the widths of the recesses 606 and 608. When these widths are fitted very close together, they can allow movement parallel to the axis 420 while preventing rotational movement between the base structure 401 and the dynamic seat 402.Consequently, a properly sized restrictor can restrict the movement of the dynamic seat 402 relative to the seat base structure 401 in multiple directions, thereby maintaining proper alignment and protecting the parts from damage and wear. The present invention can be embodied in other specific forms without departing from its spirit or essential characteristics. The embodiments described herein should be considered in all respects as illustrative only and not restrictive. Therefore, the scope of the invention is indicated by the appended claims, rather than by the foregoing description. All changes that affect the meaning and scope of the claims should be included within their scope.

Claims

1. A valve sealing system for use in a decapitation or isolation valve in a petroleum refining process, characterized in that said sealing system comprises: a seat base structure fixedly coupled to a main body of said valve; a dynamic seat movably coupled to said seat base structure, such that said dynamic seat can move with the contour of a valve shim; and a bellows seal coupled to said seat base structure and said dynamic seat, such that said bellows seal can flex with the movement of said dynamic seat, while maintaining a seal between said seat base structure and said dynamic seat.

2. The system according to claim 1, characterized in that it further comprises a plurality of springs arranged to deflect said dynamic seat from said seat base structure.

3. The system according to claim 1, characterized in that it further comprises at least one restrictor for restricting the movement of said dynamic seat in relation to said seat base structure, wherein said restrictor restricts the movement of said dynamic seat in a direction away from said seat base structure.

4. The system according to claim 3, characterized in that said restrictor further restricts the movement of said dynamic seat in a direction towards the seat base structure.

5. The system according to claim 3, characterized in that said restrictor further restricts the rotation of said dynamic seat about its central axis in relation to said seat base structure.

6. The system according to claim 1, characterized in that said bellows seal is welded to said seat base structure and said dynamic seat.

7. The system according to claim 6, characterized in that said bellows is welded to a chloride flow layer in said dynamic seat.

8. The system according to claim 1, characterized in that said MA / t / ZUZ I / UOUZZU bellows is made of a material selected from the group consisting of Inconel and Monel.

9. The system according to claim 1, characterized in that it further comprises at least one gasket in said dynamic seat, said gasket being shaped to receive packing material and positioned to keep said packing material in contact with an inner lining.

10. The system according to claim 1, characterized in that said restrictor has at least one flange with protrusions at a first end and at a second end, wherein said protrusions are joined to the seat base structure and to the dynamic seat.

11. The system according to claim 1, characterized in that it further comprises a bellows recess, wherein said bellows resides in said bellows recess between said seat base structure, said dynamic seat and an inner lining.

12. The system according to claim 1, characterized in that said seat base structure, said dynamic seat and said bellows seal are circular and extend completely around a valve opening.

13. A valve sealing system for use in a decapitation or isolation valve in a petroleum refining process, characterized in that said sealing system comprises: a seat base structure fixedly coupled to a main body of said decapitation or isolation valve; a dynamic seat movably coupled to said seat base structure, such that said dynamic seat can move with the contour of a valve shim; a restrictor for restricting the movement of said dynamic seat with respect to said seat base structure, wherein the tabs of said restrictor engage with base projections in said seat base structure and with seat projections in said dynamic seat to restrict said movement.

14. The system according to claim 13, characterized in that a general length of said restrictor restricts the movement of said dynamic seat towards said seat base structure to a maximum value.

15. The system according to claim 13, characterized in that a length between tabs of said restrictor positions the tabs of the restrictor to restrict the movement of said dynamic seat with respect to the seat base structure to a maximum value.

16. The system according to claim 13, characterized in that a length between tabs of said restrictor positions the tabs of the restrictor to restrict MA / t / ZUZ I / UOUZZU the movement of said dynamic seat in relation to the seat base structure to a maximum value and a total length of said restrictor restricts the movement of said dynamic seat towards the seat base structure to a maximum value.

17. The system according to claim 13, characterized in that a width of said restrictor in relation to a width of a recess in said seat base structure restricts the rotation of said dynamic seat, about an axis, in relation to said seat base structure to a maximum value.

18. The system according to claim 13, characterized in that it further comprises a bellows seal, wherein a length between tabs of said restrictor positions the tabs of the restrictor to restrict the movement of said dynamic seat in relation to said seat base structure to a maximum elastic deformation value for a bellows seal.

19. The system according to claim 13, characterized in that it further comprises a bellows seal, wherein a length between tabs of said restrictor positions the tabs of the restrictor to restrict the position of said dynamic seat in relation to said seat base structure to a position in which said bellows seal can be welded.

20. The system according to claim 13, characterized in that it further comprises at least one gasket in said dynamic seat, said gasket being shaped to receive packing material and positioned to keep said packing material in contact with an inner lining.

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