TRIZ evolution of black oil coker units

CATEGORY: COKERS & COKING 
TRIZ evolution of black oil coker units

Type	Journal Article
Author	V.D. Berdonosov
Author	A.N. Kozlita
URL	http://dx.doi.org/10.1016/j.cherd.2015.08.013
Publication	Chemical Engineering Research and Design
Date	Aug. 22, 2015
Abstract	TRIZ-evolutionary approach provides an opportunity to list analyzed systems in order of increasing ideality. As employed in TRIZ, ideality is the ratio of the sum of parameters that characterize benefits to the sum of parameters that characterize costs. Generally, ideality estimation is characterized by the main technological parameter. Super-system tends to increasing ideality of the analyzed system, while its inner contradictions prevent the ideality increase. Further development of the system occurs when contradictions are resolved through the use of TRIZ tools. The tools are used consciously or unconsciously. Thus, the evolution of systems is being formed in the way ‘from contradiction to contradiction’. Such a forming-up enables systematizing knowledge about analyzed systems, as well as offering new high-efficiency, powerful solutions. Authors present the results of knowledge systematization of black oil coking units. They identify the major contradictions arising in the process of coker unit evolution, and describe the TRIZ tools that resolve these contradictions.

Method And System For Detecting Coking Growth And Maldistribution In Refinery Equipment (Patent Application ExxonMobil Research and Engineering)

CATEGORY: COKERS & COKING 
Method And System For Detecting Coking Growth And Maldistribution In Refinery Equipment (Patent Application ExxonMobil Research and Engineering)
United States Patent Application 20150268078
September 24, 2015
Assignee: ExxonMobil Research and Engineering
Abstract
Systems and methods for detecting coking in a wash bed of a vacuum pipe still with a sensing cable including an optical fiber sensor array aligned with a heating element disposed in the vessel. An optical signal interrogator is configured to measure a first temperature profile at a plurality of sensor locations to determine a flow distribution. An excitation source is configured to propagate at least one heat pulse through the heating element and the optical signal interrogator is configured to measure a second temperature profile corresponding to the heat pulse at the sensor locations. A control unit is configured to detect coking by determining one or more properties of the media exposed to the sensing cable at each of the plurality of sensor locations based on the second temperature profile corresponding thereto.
Description
FIELD
[0002] The presently disclosed subject matter relates to methods and systems for detecting coking and flow maldistribution in a wash bed of a vacuum pipe still distillation tower. More particularly, the presently disclosed subject matter relates to detecting coking and flow maldistribution in a wash bed of a vacuum pipe still distillation tower using a sensing cable including an optical fiber sensor array aligned with a heating element.
BACKGROUND
[0003] Components of certain equipment, such as that used in the petroleum and petrochemical industry, which includes the exploration, production, refining, manufacture, supply, transport, formulation or blending of petroleum, petrochemicals, or the direct compounds thereof, are often monitored to maintain reliable operation. However, such components can involve harsh conditions, such as high temperature, high pressure, and/or a corrosive environment, making it difficult or costly to obtain reliable measurements.
[0004] Detection of coking formation in a wash bed of a vacuum pipe still (VPS) distillation tower can allow operators to alter operating parameters to increase utilization of the bed and thus enhance operations. For example, detecting coking formation at an early stage and knowing its location within the wash bed in the VPS distillation tower can allow for mitigation strategies such as increasing the flow rate of wash oil to remove the coking.
[0005] Conventional techniques for detection of coking/fouling, and/or corresponding maldistribution resulting from such coking in such equipment as catalytic hydroprocessing reactors, can include monitoring temperature distribution to identify hotspots and infer flow distribution. Such techniques often rely on multiple thermocouples to monitor temperature distribution, e.g., inside fixed bed catalytic hydroprocessing reactors. However, the number of thermocouples used for hot-spot detection within a VPS wash bed or reactor catalyst bed can be limited by the space inside the bed and the cost of installation and maintenance. Thus, it can be difficult to provide adequate coverage inside the fixed bed space for sufficient hot spot detection. Likewise, flow conditions inferred from the limited point temperature measurements provided by thermocouples, constrained by the physical size of the thermocouples as well as the cost of installation and maintenance, can be inaccurate.
[0006] Other techniques to detect coking, and/or corresponding flow maldistribution, can include monitoring the delta pressure between the top and bottom of the wash bed. However, this technique is not without disadvantages, such as for vacuum tower wash beds, where the pressure drop is typically only on the order of a few mmHg in these wash beds when coking occurs. Thus, pressure measurement can be a highly unreliable indicator of coking. Similarly, temperature differentials between bulk temperatures have also been used to detect coking. However, this technique involves a gross measurement and thus not necessarily accurate.
[0007] Accordingly, there is a continued need for improved techniques for detecting coking/fouling growth and maldistribution in components of refinery equipment such as a wash bed of a VPS distillation tower.
SUMMARY
[0008] The purpose and advantages of the disclosed subject matter will be set forth in and apparent from the description that follows, as well as will be learned by practice of the disclosed subject matter. Additional advantages of the disclosed subject matter will be realized and attained by the methods and systems particularly pointed out in the written description and claims hereof, as well as from the appended drawings. To achieve these and other advantages and in accordance with the purpose of the disclosed subject matter, as embodied and broadly described, the disclosed subject matter includes systems and methods for detecting coking in a wash bed of a vacuum pipe still. Although the disclosures herein may be described in relation to the use in a wash bed of a vacuum pipe still, such technology as described herein will generally also be applicable in a similar manner to the installation and use in detecting localized coking, as well as flow maldistributions, in a catalytic hydroprocessing reactor catalyst bed.
[0009] In accordance with one aspect of the disclosed subject matter, a method for detecting coking in a wash bed of a vacuum pipe still includes providing within a vacuum pipe still a sensing cable including an optical fiber sensor array aligned with a heating element and measuring a first temperature profile of the sensing cable at a plurality of sensor locations. The method includes determining a flow distribution of fluids within the vacuum pipe still by identifying a first set of sensor locations of the sensing cable exposed to vapor and a second set of sensor locations of the sensing cable exposed to liquid based on the first temperature profile. The includes propagating at least one heat pulse through the heating element along at least a portion of the sensing cable to affect an exchange of thermal energy between the heating element and media, including the fluids, exposed to the sensing cable. The method includes measuring, over time, at least a second temperature profile of the sensing cable corresponding to the heat pulse at each of the plurality of sensor locations of the optical fiber sensor array. The method includes detecting coking by determining one or more properties of the media exposed to the sensing cable at each of the plurality of sensor locations based on the second temperature profile corresponding thereto.
[0010] In certain embodiments, measuring the first temperature can further include propagating a heat pulse through the heating element along at least a portion of the sensing cable and, for each sensor location, measuring at least a heating temperature measurement during propagation of the heat pulse over the sensor location, a peak temperature measurement, and a cooling temperature measurement after propagation of the heat pulse over the sensor. Determining the flow distribution of the fluids exposed to the sensing can include calculating a difference in the heating temperature measurement, the peak temperature measurement, the cooling temperature measurement, or combination thereof, between sensor locations, wherein the difference indicates a change in fluid characteristic proximal at least one of the plurality of sensor locations if the difference exceeds a predetermined threshold.
[0011] As embodied herein, measuring the second temperature profile corresponding to the heat pulse at each of the plurality of sensor locations can include, for each sensor location, measuring a plurality of temperatures over a period of time upon arrival the heat pulse at the sensor location. Detecting coking can include, for each temperature profile, performing a regression of the plurality of temperatures over a logarithm of corresponding measurement times for a predetermined time window in the period of time to generate a slope and an intercept of the regression, wherein the slope and the intercept indicate a coking deposit proximal the sensor location. Additionally or alternatively, detecting coking can include, for each temperature profile, generating a time derivative by calculating a derivative of the plurality of temperature measurements with respect to time, applying a transform to the time derivative to generate a complex spectrum, and determining an amplitude and a phase of the complex spectrum, wherein the amplitude and the phase of the complex spectrum indicate a coking deposit proximal the sensor location. Detecting coking can further include generating a frequency derivative spectrum by calculating the derivative of the complex spectrum with respect to frequency, and determining an amplitude and a phase of the frequency derivative spectrum, wherein the amplitude and the phase of the frequency derivative spectrum indicate a coking deposit proximal the sensor location.
[0012] In certain embodiments, determining the flow distribution of the fluids can further include detecting a misdistribution condition in the wash bed by monitoring the second temperature profile corresponding to each of the plurality of sensor locations, and comparing the monitored temperature profiles to predetermined temperature profiles corresponding to a desired operation condition. Alternatively, determining the flow of the fluids within the vacuum pipe still can further include detecting a misdistribution condition in the wash bed by monitoring the second temperature profile corresponding to each of the plurality of sensor locations and at least a third temperature profile corresponding to each of the plurality of sensor locations, and comparing the second and third temperature profiles to detect a change in operation condition. The sensing cable can disposed in a grid configuration within the wash bed, and the method can include generating a multi-dimensional flow distribution based on the first temperature profile corresponding to each sensor location.
[0013] In accordance with another aspect of the disclosed subject matter, a system for detecting coking in a wash bed of a vacuum pipe still includes a sensing cable including an optical fiber sensor array aligned with a heating element disposed in the wash bed, the optical fiber sensor array having a plurality of sensor locations. The system includes an optical signal interrogator coupled with the optical fiber sensor array and adapted to receive a signal from each of the plurality of sensor locations and configured to measure a first temperature profile of the sensing cable at the plurality of sensor locations. The system includes a control unit, coupled with the heating element and the optical signal interrogator, configured to determine a flow distribution of fluids within the vacuum pipe still by identifying a first set of sensor locations of the sensing cable exposed to vapor and a second set of sensor locations of the sensing cable exposed to liquid based on the first temperature profile. The system includes an excitation source coupled with the heating element configured to propagate at least one heat pulse through the heating element along at least a portion of the sensing cable to affect an exchange of thermal energy between the heating element and media, including the fluids, exposed to the sensing cable. The optical signal interrogator is configured to measure, over time, a second temperature profile of the sensing cable corresponding to the heat pulse at each of the plurality of sensor locations on the optical fiber sensor array. The control unit is configured to detect coking by determining one or more properties of the media exposed to the sensing cable at each of the plurality of sensor locations based on the second temperature profile corresponding thereto.
[0014] As embodied herein, the optical signal interrogator can be configured, for each of the plurality of sensor locations, to measure a plurality of temperatures over a period of time upon arrival of the heat pulse at the sensor location. The control unit can be configured, for each temperature profile, to perform a regression of the plurality of temperatures over a logarithm of corresponding measurement times for a predetermined time window in the period of time to generate a slope and an intercept of the regression, wherein the slope and the intercept indicate a coking deposit proximal the sensor location. Additionally or alternatively, the control unit is configured, for each temperature profile, to generate a time derivative by calculating a derivative of the plurality of temperature measurements with respect to time, apply a transform to the time derivative to generate a complex spectrum, and determine an amplitude and a phase of the complex spectrum, wherein the amplitude and the phase of the complex spectrum indicate a coking deposit proximal the sensor location. The control unit can further be configured to generate a frequency derivative spectrum by calculating the derivative of the complex spectrum with respect to frequency, and determine an amplitude and a phase of the frequency derivative spectrum, wherein the amplitude and the phase of the frequency derivative spectrum indicate a coking deposit proximal the sensor location.
[0015] In certain embodiments, the control unit can further be configured to detect a misdistribution condition in the wash bed by monitoring the second temperature profile corresponding to each of the plurality of sensor locations, and compare the monitored temperature profiles to predetermined temperature profiles corresponding to a desired operation condition. Alternatively, the control unit can be further configured to detect a misdistribution condition in the wash bed by monitoring the second temperature profile corresponding to each of the plurality of sensor locations and at least a third temperature profile corresponding to each of the plurality of sensor locations, and comparing the second and third temperature profiles to detect a change in operation condition. The sensing cable can be disposed in a grid configuration within the wash bed, and the control unit can be further configured to generate a multi-dimensional flow distribution based on the first temperature profile corresponding to each sensor location.
[0016] It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the disclosed subject matter claimed. Also, as noted, although, for simplicity purposes, the disclosures herein may be described in relation to the use in a wash bed of a vacuum pipe still, such technology as described herein will generally also be applicable in a similar manner to the installation and use in detecting localized coking, as well as flow maldistributions, in a catalytic hydroprocessing reactor catalyst bed.
[0017] The accompanying drawings, which are incorporated in and constitute part of this specification, are included to illustrate and provide a further understanding of the disclosed subject matter. Together with the description, the drawings serve to explain the principles of the disclosed subject matter.
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Metal organic framework membranes for carbon dioxide separation

CATEGORY: CARBON CAPTURE 
Metal organic framework membranes for carbon dioxide separation

Type	Journal Article
Author	Surendar R. Venna
Author	Moises A. Carreon
URL	http://www.sciencedirect.com/science/article/pii/S0009250914005752
Volume	124
Pages	3-19
Publication	Chemical Engineering Science
Date	March 3, 2015
Abstract	Reviews research progress on metal organic framework membranes which have demonstrated ability to separate carbon dioxide from different light gases. Authors concentrate on CO2/N2, CO2/CH4, and CO2/H2, gas separations which are highly relevant compositions in flue gas treatment, natural gas purification, and hydrogen purification, respectively. They discuss several conventional and novel strategies developed by several research groups for the continuous defect-free MOF membrane fabrication. They conclude with a description of the advantages of using MOFs in mixed matrix membranes and improvements in gas separation performances with the MOF based mixed matrix membranes.

Integrated substance and energy flow analysis towards CO2 emission evaluation of gasoline & diesel production in Chinese fuel-refinery

CATEGORY: CARBON CAPTURE 
Integrated substance and energy flow analysis towards CO2 emission evaluation of gasoline & diesel production in Chinese fuel-refinery

Type	Journal Article
Author	Yibin Weng
Author	Guangxu Yan
URL	http://www.sciencedirect.com/science/article/pii/S0959652615010872
Publication	Journal of Cleaner Production
Date	August 8, 2015
Abstract	Fuel refineries in China emit high levels of CO2. The conventional method of CO2 emission evaluation is based on substances flow analysis (SFA), focusing on the cost control. However, as the importance of low carbon development in fuel refineries increases, CO2 emissions control has become the main objective of evaluation. In addition, it is difficult for SFA to estimate CO2 emission accurately because of the indirect CO2 emissions in energy consumption which SFA does not take into account. In this study, a CO2 emission evaluation method that combines SFA with energy flow analysis (EFA) is established. Researchers applied the method to a Chinese fuel refinery. Results suggested that the quantity of CO2 emission evaluated by combined SFA and EFA was about 14.40% higher than emissions evaluated only by SFA.

A Selection of Amine Sorbents for CO2 Capture from Flue Gases

CATEGORY: CARBON CAPTURE 
A Selection of Amine Sorbents for CO2 Capture from Flue Gases

Type	Journal Article
Author	Andrzej Wilk
Author	Lucyna Więcław-Solny
URL	Free Full Text Source:  http://www.degruyter.com/view/j/cpe.2015.36.issue-1/cpe-2015-0004/cpe-2015-0004.xml
Volume	36
Issue	1
Pages	49-57
Publication	Chemical and Process Engineering
Date	2015/03/01
Abstract	Amine absorption processes are widely used in the industry to purify refinery gases, process gases or natural gas. Recently, amine absorption has also been considered for CO2 removal from flue gases. It has a number of advantages, but there is one major disadvantage - high energy consumption. This can be reduced by using an appropriate sorbent. From a group of several dozen solutions, three amine sorbents were selected based on primary, tertiary and sterically hindered amines. The solutions were used to test CO2 absorption capacity, absorption kinetics and heat of CO2 absorption. Additional tests were performed on the actual absorber-desorber system to indicate the most appropriate sorbent for capturing CO2 from flue gases.

Process For Separating Benzene From A Reactor Effluent (Patent Application UOP)

CATEGORY: BENZENE 
Process For Separating Benzene From A Reactor Effluent (Patent Application UOP)
United States Patent Application 20150251978
September 10, 2015
Assignee: UOP LLC
Abstract
A process for separating benzene from a reactor effluent in which the reactor effluent is passed to a first separation zone to separate the effluent into a bottom benzene lean stream and an overhead stream. The bottom benzene lean stream does not need to be processed further to remove benzene. The overhead stream may be cooled and is passed to a second separation zone in which it is separated into a bottom benzene rich stream and a second overhead stream. The bottom benzene rich stream contains at least 80% of the benzene from the reactor effluent. The operating temperature of the first separation zone is greater than the operating temperature of the second separation zone.
Description
BACKGROUND OF THE INVENTION
[0001] The demand for clean and safe transportation fuel is increasing worldwide. This increased demand is, in part, a result of government regulations in various countries which attempt to reduce and/or eliminate certain chemicals that are typically contained in the transportation fuel. These government regulations can impose challenges on fuel refiners and producers to provide transportation fuel which contains lower amounts of the specified chemicals in order to comply with the various governmental regulations.
[0002] In the United States, a recent example of this is the Mobile Source Air Toxics 2 (MSAT2) benzene control program. Benzene is a byproduct of one or more chemical reactions in the reforming process associated with the refining of light petroleum distillate. Beginning in 2011, the MSAT2 regulations limit the level of benzene, a known carcinogen, in gasoline sold in the United States to an average of 0.62% of the total liquid volume of the gasoline.
[0003] It is believed that a typical reforming process might result in a reformate that has approximately 10% or less by weight of benzene. Generally, in a reforming process light petroleum distillate is contacted with catalyst in the presence of hydrogen at high temperatures to produce a high-octane liquid effluent that is rich aromatic compounds. Typically, there are a series of reactors in which the feedstock passes. After a reactor effluent from the last reactor is cooled, it is typically sent to a separator where a part of overhead vapor can be compressed and recycled to the reactor. The remaining reactor effluent can be sent to a product recovery section which includes passing the reactor effluent through various processing units and separating units some of which are designed to remove the benzene from the reactor effluent.
[0004] While current processes may be successful at obtaining appropriate benzene levels in separation steps of the entire process, the current methods require large amounts of heat and energy input. Additionally such methods typically also require large equipment sizes.
[0005] Additionally, competition in the gasoline refining industry constantly demands development of more energy efficient processing technology and methods--especially technology and methods that can competitively meet the current requirements.
[0006] Finally, beyond the current standards, future government regulations may further limit the amount of benzene in gasoline to an even lower level--creating a greater challenge for refiners and producers.
[0007] Therefore, it would be desirable to have a process that can effectively and efficiently separate benzene from a reactor effluent.
SUMMARY OF THE INVENTION
[0008] Accordingly, in an embodiment of the present invention, a method for separating benzene from a reactor effluent is provided in which a reactor effluent is recovered from a reaction zone. The reactor effluent includes at least benzene. The reactor effluent is passed to a first separation zone to separate the reactor effluent into an overhead stream and a bottom stream. It is contemplated that the reactor effluent is cooled prior to passing from the reactor effluent to the first separation zone.
[0009] The first separation zone has an operating temperature. In some embodiments of the present invention, it is contemplated that the operating temperature of the first separation zone is between 65.degree. C. to 130.degree. C., and preferably between 85.degree. C. to 110.degree. C.
[0010] In some embodiments of the present invention, a temperature of the reactor effluent as it is passed to the first separation zone is measured. Based upon the temperature of the reactor effluent, the operating temperature of the first separation zone may be adjusted.
[0011] The overhead stream from the first separation zone is recovered from the first separation zone and cooled to produce a cooled overhead stream. The cooled overhead stream is passed to a second separation zone to separate the cooled overhead stream into a benzene rich bottom stream and a second overhead stream.
[0012] The second separation zone has an operating temperature lower than the operating temperature of the first separation zone. It is preferred that the operating temperature of the second separation zone is approximately ambient temperature.
[0013] The benzene rich bottom stream from the second separation zone may be recovered and passed to a debutanizer or a recontact zone or both.
[0014] It is further contemplated to recover the second overhead stream from the second separation zone and pass it to a recontact zone. In the recontact zone, the second overhead stream is separated into a recontact light stream and a recontact bottom stream. The recontact bottom stream may be recovered from the recontact zone and passed to a debutanizer.
[0015] In other embodiments of the present invention, a method for separating benzene from a reactor effluent is provided in which a naphtha feedstock is reacted in the presence of a catalyst in a reaction zone to produce a reactor effluent. Again, the reactor effluent includes at least benzene. The reactor effluent is recovered from the reaction zone and passed to a first separation zone.
[0016] In the first separation zone, the reactor effluent is separated into an overhead stream and a bottom stream. Again, the first separation zone may have an operating temperature between 65.degree. C. to 130.degree. C., and preferably between 85.degree. C. to 110.degree. C., and an operating pressure between approximately 345 to 689 KPa (approximately 50 to 100 psi). In a preferred embodiment of the present invention, a temperature of the reactor effluent is measured, and an operating temperature of the first separation zone is controlled and adjusted based upon the temperature of the reactor effluent.
[0017] The bottom stream includes mostly hydrocarbons containing seven carbons or more. The bottom stream is recovered from the first separation zone.
[0018] The overhead stream from the first separation zone includes mostly hydrocarbons containing six carbons or less. The overhead stream is also recovered from the first separation zone and may be cooled to a temperature of approximately 40.degree. C. to produce a cooled overhead stream. Thereafter, the cooled overhead stream is passed to a second separation zone.
[0019] In the second separation zone, the cooled overhead stream is separated into a benzene rich bottom stream and a second overhead stream. In some embodiments, the first separation zone has an operating temperature that is higher than the operating temperature of the second separation zone. The second separation zone may have an operating temperature that is an ambient temperature
[0020] It is further contemplated that the second overhead stream is recovered from the second separation zone and passed to a recontact zone. In the recontact zone, the second overhead stream is compressed and separated into a recontact light stream and a recontact bottom stream. The recontact zone may have an operating pressure between approximately 2760 to 3450 KPa (approximately 400 to 500 psi). The recontact bottom stream may be recovered from the recontact zone and passed to a debutanizer. Additionally, the recontact light stream may also be recovered from the recontact zone and passed to a hydrogen purification unit.
[0021] In one or more embodiments of the present invention, the benzene rich bottom stream includes approximately 80% of a total benzene amount in the reactor effluent. It is contemplated that the bottom stream of the first separation zone includes less than 15% of a total benzene amount in the reactor effluent and preferably between approximately 5 to 10% of a total benzene amount in the reactor effluent.
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Alkylation of Asphaltenes Using a FeCl3 Catalyst

CATEGORY: ASPHALTENES 
Alkylation of Asphaltenes Using a FeCl3 Catalyst

Type	Journal Article
Author	Glaucia H. C. Prado
Author	Arno de Klerk
URL	http://dx.doi.org/10.1021/acs.energyfuels.5b01292
Volume	29
Issue	8
Pages	4947-4955
Publication	Energy & Fuels
Date	August 20, 2015
Abstract	Researchers studied Friedel/Crafts alkylation as a strategy for conversion of asphaltenes to maltenes. Their hypothesis was that conversion of polar hydroxyl groups in the asphaltenes would make the product more soluble in light hydrocarbons. They conducted reactions with oilsands bitumen-derived materials using FeCl3 as a catalyst and o-xylene and methanol, separately. Only the reaction of o-xylene with asphaltenes was mildly beneficial, producing 6% conversion of asphaltenes to maltenes and an increase of 9% in straight-run distillate and vacuum gas oil. To gain a better understanding of the nature of the conversion, the reactions were repeated with model compounds. With 2-naphthol, it was found that dimerization of 2-naphthol to produce (1,1?-binaphthalene)-2,2?-diol (BINOL) and the subsequent coordination with iron were the two dominant reactions. The adverse consequences of FeCl3-catalyzed conversion could be explained by such intermolecular addition reactions. The reaction of 2-naphthol with methanol and FeCl3 also caused some chlorination of the product. The possibility that FeCl3 as a catalyst affected ethers was explored by performing the reaction with dibenzyl ether as feed.