Patent Application
20140116871
The field of the invention is multiple drum coking systems.
The following background discussion includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Delayed coking is a well known thermal cracking process used in various refineries that converts a residual feed into solid carbonaceous material (e.g., petroleum coke). The use of multiple drums in coking systems allows the coke drums to operate continuously. Generally, while one drum in a multiple drum system is being filled with a feed stream, another is being stripped, cooled, decoked, pressure checked, or warmed up (See e.g., http://www.coking.com/DECOKTUT.pdf and http://www.coking.com/SeminarUSA/PresentationPDFs2012/FLUOR_BMilletKKirkpatrick_FreshLookAt3DrumCokers_CokingCom_Galv—2012.pdf).
These and all other extrinsic materials discussed herein are incorporated by reference in their entirety. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
Oftentimes, cycles (e.g., step cycle (e.g., warm up time, drain time, etc.), drum cycle, system cycle, etc.) are shortened to increase throughput of coke drums. Where only two drums are used, continuous operation of both drums generally requires that the on-stream and decoking steps take the same amount of time. However, step cycles can only be shortened by a limited amount due to minimum time requirements of each step in the process. Moreover, shortening cycle times can lead to shortened coke drum life spans and frequent need for repairs, among other problems. As used herein, a “step cycle” is the amount of time it takes one drum to complete a step (e.g., warm up, stripping, filling, etc.) in the delayed coking process. A “drum cycle” is the amount of time it takes a single drum to complete all steps in the delayed coking process, from warming up to decoking. A “system cycle” is the amount of time it takes for all drums in the delayed coking process to complete a drum cycle. Each of the cycles can be altered (e.g., shortened or expanded).
U.S. Pat. No. 3,472,761 to Cameron attempts to address the problems associated with shortened cycle times and describes a delayed coking process using three or more coke drums. Under Cameron's system, one drum processes a first type of feed, while a second drum processes a different type of feed. The third coke drum allows the first and second drums to be decoked without interrupting a continuous production of coke.
U.S. Pat. No. 4,634,500 to Elliot and U.S. Pat. No. 5,795,445 to Boswell each attempt to address the problems associated with coke drum life spans, and each discloses controlling quench to prevent excess stress in the coke drum wall.
U.S. Pat. No. 4,929,339 to Elliot, U.S. Pat. No. 3,745,110 to Allred, and U.S. Patent Publication No. 2002/0179493 to Etter each further attempt to improve coking systems or products thereof.
Unfortunately, each of the above cited references fails to adequately address (1) the problems that could arise when one or more of the coke drums require repair or replacement, (2) how to reduce the need for repairs and replacements, or (3) how to increase throughput/efficiency of coke drums and systems. Thus, there is still a need for improved coking systems.
The inventive subject matter provides apparatus, systems and methods in which a drum is coupled to a piping sub-system and valve that allows the drum to receive a vapor from at least two different coke drums simultaneously or sequentially. Such systems can better assure that the loss of one coke drum (e.g., for repairs, replacement, or even maintenance) will not affect the productivity or profitability of remaining coke drums of a system.
As used herein, and unless the context dictates otherwise, the term “coupled to” is intended to include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). Therefore, the terms “coupled to” and “coupled with” are used synonymously.
Such coupling allows a vapor of a first drum to be received by two or more different drums, while allowing the first drum to receive a vapor from two or more different drums. It is contemplated that the receiving drum can receive pure vapor streams or mixed streams, directly or indirectly. As used herein, a “pure vapor stream” is a stream that comprises the vapor of only a single drum (other than residue of a piping subsystem). A “mixed stream” is a stream that comprises vapor of at least two drums. The term “directly” means without passing through another drum. Thus, a vapor of a first drum received by a second drum is received directly unless there is an intervening drum.
One example of a vapor of an on-line coke drum is a hot vapor configured to warm up a second drum. The vapor is circulated into a substantially empty drum (e.g., second drum), thereby heating it to a desired temperature. The condensed vapor is then emitted from the second drum. Once the second drum has been heated to a desired temperature, it is ready to be filled with a different stream (e.g., a feed stream).
Contemplated coking systems can comprise three, five, ten, or even twenty or more coke drums. Two of the drums can be functionally paired with one another such that one drum is warmed, stripped, quenched, etc. by an emission (e.g., a vapor, a liquid, etc.) of another drum. In some embodiments having at least four drums, it is contemplated that drums could be paired in interchangeable groups (e.g., A-B, C-D, A-C, A-D, etc.). Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints, and open-ended ranges should be interpreted to include commercially practical values. Similarly, all lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary.
The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
One or more sensors could be included in a coking system. This sensor could comprise a feedback mechanism during any sub-cycle of a coking cycle, including for example, a filling step, a heating step, or a quenching step.
Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.
It should be noted that any language directed to a computer should be read to include any suitable combination of computing devices, including servers, interfaces, systems, databases, agents, peers, engines, controllers, or other types of computing devices operating individually or collectively. One should appreciate the computing devices comprise a processor configured to execute software instructions stored on a tangible, non-transitory computer readable storage medium (e.g., hard drive, solid state drive, RAM, flash, ROM, etc.). The software instructions preferably configure the computing device to provide the roles, responsibilities, or other functionality as discussed below with respect to the disclosed apparatus. In especially preferred embodiments, the various servers, systems, databases, or interfaces exchange data using standardized protocols or algorithms, possibly based on HTTP, HTTPS, AES, public-private key exchanges, web service APIs, known financial transaction protocols, or other electronic information exchanging methods. Data exchanges preferably are conducted over a packet-switched network, the Internet, LAN, WAN, VPN, or other type of packet switched network.
The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.
The systems illustrated in the figures are diagrammatic in nature for explanatory purposes, and should not be construed as operational.
In
All known types of valves, pipes, and coke drums, made of any suitable material(s) are contemplated. Valves of a coking system can be manual or automatic, including for example, automatic control valves, a valve with a timed switch mechanism, a ball valve, a butterfly valve, and a gate valve. A valve could be configured to split a stream in two or more directions, for example, to a second, third, and fourth drum simultaneously.
As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
It is contemplated that each stream could comprise a feed medium, a heating medium, a quenching medium, any other suitable medium of a coking system, or a combination thereof, regardless of the source. It is contemplated that a stream could comprise a vapor of one or more coke drums or originate external to the coking system (e.g., a furnace, etc.). Where a stream comprises a vapor of another coke drum, contemplated streams include, for example, a vapor stream released during a quenching cycle, and have a temperature of at least 400 degrees, 500 degrees, or even 800 degrees F.
The use of three of more drums in a coking system (e.g., system 100) could allow for a longer or more gradual step cycle(s) (e.g., warming up, quenching, conditioning, decoking, etc.) without decreasing the productivity of a coke drum. Thus, the addition or use of additional drum can allow for a more gradual quenching that requires an increase in step cycle time, versus a system prior to the addition.
In
Paired systems can better assure that the reduced life (i.e., required maintenance, repair, or replacement) of one coke drum does not affect the productivity of other coke drums in the system. For example, third drum 208 and fourth drum 209 are functionally paired such that, in normal operations, a vapor of the fourth drum (e.g., 211) is used by the third drum, and visa versa (via stream 217). If the fourth drum needs to be taken off-line for repairs, third drum 208 can still function by using a vapor of the third drum 208 or first drum 206 or second drum 207 (e.g., 210 or 216). Without a piping subsystem and valves 204 and 205, third drum 208 would not receive a vapor and thus would be less or non-functional.
Where a coke drum is configured to receive vapors from at least two other drums, it is contemplated that the receiving drum could receive two separately maintained streams directly from the two discharging drums. Alternatively, the receiving drum could receive one or all streams indirectly from another drum, or receive a mixed stream (e.g., a mix of the first and second vapors).
The valve(s) and coking drums of a system can be configured to operate simultaneously, sequentially, or in any suitable manner. Thus, it is contemplated that two of four drums in a system could be on-line while the remaining two drums are decoked, all four drums in a system could be filled at the same time, three of the four drums could be quenched at the same time, and so forth.
In
Second piping subsystem 316 comprises third and fourth valves, 304 and 305, respectively. Second stream 310 (e.g., a vapor from first drum 306 or second drum 307) is directed to third valve 304, which is configured to further direct stream 310 to at least one of first drum 306, second drum 307, third drum 308, and fourth drum 309 via fourth valve 305.
Third stream 311 (e.g., a vapor of fourth drum 309) is directed to fourth valve 305 via second piping subsystem 316, and is further directed to third drum 308 or another drum or other unit (e.g., fractionator, thermal cracking unit, etc.) (not shown).
It is contemplated that at least one coke drum in a delayed coking system could be coupled to a sensor, e.g., first sensor 313 or second sensor 314. First sensor 313 is coupled to the first drum 306 and can be configured to provide feedback to an operator at any time during a drum cycle. Additionally or alternatively, each of the drums in a coking system could be coupled to one or more sensors. Second sensor 314 is coupled to first, second, third, and fourth drums (306-309) such that the sensor can provide feedback to an operator related to any and all of the drums (e.g., when an ideal temperature is reached, a threshold temperature is exceeded, a temperature gradient between two points of a coke drum is excessive, a drum is not working properly, etc.).
Contemplated sensors include for example, all relevant temperature sensors, steam sensors, pressure sensors, corrosion sensors, stress sensors, and liquid sensors. A feedback mechanism coupled to the sensor could include any suitable mechanism, including for example, still imagery, video imagery, alarm, printout of relevant information, and other visual and audio signals.
Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.
It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the scope of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C . . . and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.
