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Paraxylene Production

GTC's Marketing Department — Wed, 15 Jul 2009 14:00:00 GMT

Crystallization technology has improved dramatically over the last three decades. Recent advances in equipment and process control have answered many of the criticisms that have limited its application. Previous designs relied on small units arranged in multiple processing trains and were therefore deemed maintenance intensive. The new equipment is larger, more reliable, and capable of extended run lengths without maintenance.

Paraxylene Crystallization

The C₈ aromatic isomers are difficult to separate by distillation due to their close boiling points. In particular, the boiling points of paraxylene and metaxylene differ by less than 1°C. However, because paraxylene has a markedly higher freezing point than the other isomers, crystallization can be used to facilitate its separation.

Separation of paraxylene by freezing can be accomplished either by suspension crystallization or layer crystallization. For feedstocks containing low concentrations of paraxylene (i.e. 20-24%), suspension crystallization using two or more stages of separation is the only feasible option. For enriched feedstocks, crystallization is a very attractive method of recovery.

CrystPX^SM

Suspension crystallization of paraxylene in the xylene isomer mixture is used to produce paraxylene crystals. The design uses an optimized arrangement of equipment to obtain the required recovery and product purity. Washing the paraxylene crystal with the final product in a high efficiency pusher-centrifuge system produces the paraxylene product. Figure 1 shows a general flow scheme for the technology.

Figure 1. CrystPX Process Flow Scheme

When paraxylene content in the feed is enriched above equilibrium in the case of streams originating from selective toluene conversion processes, GTC’s crystallization process technology is one of the most economical means to produce high purity paraxylene product at high recoveries. The company takes advantage of recent advances in crystallization techniques and equipment to create this attractive method for paraxylene recovery and purification.

The process advantages of this new technology include:

High paraxylene purity and recovery (99.8+ wt% purity at 95% recovery).
Crystallization equipment is simple, easy to procure, and operationally trouble free.
Simple design requires small plot size and low capital investment.
The system is flexible, enabling it to meet market requirements for paraxylene purity.
The system is easily designed to allow for future incremental capacity increases.
Feed concentration of paraxylene is used efficiently.
Flexible technology allows a range of feed concentrations (75-95 wt% paraxylene) to be processed in a single stage refrigeration system.
Design variations are used to recover paraxylene efficiently from dilute mixed xylene feedstocks (22% PX) in a multistage system.

The design uses only crystallizers and centrifuges in the primary operation. This simplicity of equipment promotes low maintenance costs, easy incremental expansions, and controlled flexibility. High purity paraxylene is produced in the front section of the process at warm temperatures, taking advantage of the high concentration of paraxylene already in the feed. At the back end of the process, high paraxylene recovery is obtained through a series of crystallizers operated successively at colder temperatures. This scheme minimizes the need for recycling excessive amounts of filtrate, thus reducing overall energy requirements.

Case Study

LG-Caltex Oil Corporation will use CrystPX crystallization process technology for its new 400,000 tpy paraxylene production unit in Yosu, Korea.

The LG-Caltex Yosu Complex currently operates a world scale paraxylene production facility with a nominal capacity of 700 tpy. This expansion catapults LG-Caltex into the position of number one merchant producer of paraxylene from a single site in the world.

The award marks GTC’s full entry into the paraxylene technology licensing business. In today’s market, with changing feedstocks and market constraints, crystallization technology gives a producer the most flexibility, reliability, and lowest investment cost.

LG-Caltex believes that the CrystPX process is the most simple and reliable technology for its application. It provides and efficient recovery of PX from the feed and the flexibility to adjust process conditions to suit market requirements. The design and equipment are simple and easily procured. A fast startup and trouble-free operation is expected in January 2003.

LG-Caltex, a joint venture between Caltex and the LG Group in Korea, is one of the world’s largest oil refiners and petrochemical producers with a refinery capacity of 650,000 bpd crude oil.

*This article also appeared in Hydrocarbon Engineering.

15-Jul-09 9:00 AM

Optimizing crude unit design

GTC's Marketing Department — Wed, 15 Apr 2009 13:00:00 GMT

Introduction

The basic function of a crude distillation unit (CDU) is to provide initial separation of the crude oil feed mixture into the desired fractions to be further processed in the downstream units. The crude unit’s quality of performance impacts heavily on the downstream unit’s performance. A lot of crude units currently operate with different feed slates to their original feed specifications. This change in feed composition often results in inferior crude unit performance and reduces the unit’s run length. Re-optimizing the design and operation of the crude unit with current feed slates is essential to maximize a refiner’s economics. In addition, recent crude oil price fluctuations and increased economic pressure further emphasize the importance of optimizing crude unit performance.

Crude atmospheric column

The crude atmospheric column is the CDU’s core piece of equipment. In a typical crude unit design, crude oil is heated and introduced to the crude atmospheric column’s flash zone. The light products are typically recovered as distillates from multiple liquid product draws and the remaining crude is discharged at the column’s bottom. The original process arrangement relied on a single top reflux flow. The column top reflux provided condensation for all the required product draws, plus the overflash. This approach created high variations in the internal vapor-liquid traffic throughout the column (from column top to flash zone), with a maximum reflux loading at the top and the lower wash section receiving only a small amount of liquid, wash oil. The columns were then sized according to the greatest load, top section internal traffic, which resulted in an oversized column diameter. Moreover, the required size of the overhead condenser was substantially increased.

To minimize these liquid traffic variations, inter-condenser design philosophy was adapted in the crude atmospheric column design. Intercondensers can be configured as either pumpback or pumparound circuits. Figure 1 compares typical internal reflux rate variations through the crude atmospheric column (from column top to flash zone) among three reflux methods.¹ The pumparound reflux method achieves more uniform liquid balancing through the column than the other two reflux methods. This uniformity of liquid enables the column to be sized at a smaller diameter for reduced investment cost. The higher pumparound draw temperatures increase the opportunity for heat recovery for lower energy consumption. In addition, the overhead condenser size is reduced. The main trade-off is that the pumparound circuit design requires more trays and/or packing for heat transfer performance. In summary, the advantages of the pumparound reflux arrangements far outweigh any disadvantages, and as a result it has replaced the pumpback reflux method in most modern crude atmospheric column designs.

Figure 1 - Comparison of internal-reflux rates for three methods of providing reflux.

The presence of a top pumparound circuit depends on overhead distillate yield/fractionation requirements, column top temperature control and overhead condenser size/limitations. Typical crude atmospheric column overhead configurations are depicted in Figure 2 for cases A-C. Case A shows that the top section reflux is provided by a top pumparound circuit only. In this configuration, the column top temperature is relatively high and the chance of water condensing at the column top can be minimized. In addition, the overhead condenser size can be minimized due to a lack of top reflux stream. However, the top pumparound trays and/or packing do not contribute towards fractionation. An additional fractionation section is required to achieve the desired fractionation between the overhead distillate and the first side product, which increases the overall column height.

Figure 2 - Typical crude atmospheric column overhead configurations

Case B depicts a crude atmospheric top section with a top reflux without a top pumparound circuit. This top reflux temperature is usually lower than the reflux through the top pumparound circuit. In this case, fractionation performance between the overhead distillate and the first side product can be maximized at the given column height. However, the required overhead condenser duty is higher and the column top temperature is lower than for Case A.

Case C is somewhat of a compromising design between Cases A and B. This configuration has a top reflux irrigation line as well as a top pumparound circuit. The amount of cold reflux (from top reflux) and hot reflux (from top pumparound) can be controlled at given processing conditions. This configuration is suitable for the crude atmospheric column, which faces high variations in overhead distillates and yields.

Crude column internal vapor and liquid traffic rely heavily on pumparound circuit locations. The number and location of pumparound circuits are determined by crude slate structures, product yield patterns, fractionation requirements, overhead condenser size and other factors. The crude atmospheric column is designed to provide the best performance for specific ranges of crude slates and product yields. Therefore, a large change from design conditions may induce performance downgrading in the crude unit. Fractionation performance between adjacent products requires specific design internal reflux at a given number of fractionating trays or packed bed depth. Crude overhead condenser duty is also determined by design heat balances.

In most cases, the actual crude slate structures processed in the crude unit deviate from the original design ranges. To maintain desired unit performances at changed feed conditions, most refiners adjust and rearrange the pumparound balances. These operation parameter changes shift the column traffic through the crude atmospheric column. The pumparound rate change impacts neighboring fractionation section internal reflux rates, so fractionation performance is affected.²Unbalanced column traffic often results in unit capacity limitations. The crude atmospheric column design should be re-evaluated with current operating blends to ensure the best performance possible.

The following actual retrofit case demonstrates how a crude unit can be successfully optimized, considering a more typical crude blend used by the refinery.

Retrofit background

The crude unit under discussion was originally commissioned in the early 1970s. Charged crudes are heated through two parallel preheat trains and furnaces, and then introduced into the crude atmospheric column. This column separates crudes to intermediate products: unstabilized naphtha, kerosene, light gas oil (LGO), medium gas oil (MGO), heavy gas oil (HGO) and reduced crude (R/C). Unstabilized naphtha is then fed to the naphtha stabilizer to separate the LPG and naphtha. The kerosene stream is transported to the hydrotreating unit. LGO, MGO and HGO are combined to the diesel pool after hydrotreating. Reduced crude is either transported to conversion units or blended to fuel oil.

The crude atmospheric column was originally constructed with four pumparound circuits: one top pumparound and three diesel pumparound circuits. A top reflux stream, which is recycled from the unstabilized naphtha (overhead distillate), is combined with the top pumparound stream before returning to the crude atmospheric column. The amount of top reflux stream is adjusted relative to the unstabilized naphtha boiling range of the processed crudes. To increase the crude charge rate and enhance unit performance, this crude unit had been previously retrofitted. During these prior retrofits, the HGO pumparound and wash sections were converted to structured packed beds. All four side strippers are steam-stripped. Figure 3 illustrates the crude atmospheric column configurations after these previous retrofits.

Figure 3 - Crude atmospheric column configurations - previous retrofit.

To meet required downstream unit balances, especially in the conversion units, the refiner decided to perform a new crude unit retrofit. The targets of this current retrofit were debottlenecking operating limitations and increasing crude unit capacity. One of the unit limitations the refiner faced was that the crude atmospheric column had difficulty processing crude slates containing a high percentage of kerosene boiling range materials. In the winter, kerosene product is usually more valuable than diesel and naphtha. Relieving any limitations on kerosene production was necessary to improve unit economics.

Replacing existing crude column trays with high-performance trays or packing is one of the most economical ways to improve column capacity in terms of overall downtime and cost. However, the preliminary evaluation was that a retrofit of the kerosene side stripper would not meet the required capacity. All four existing side strippers were stacked and erected as one single column shell with the kerosene stripper located on top. Therefore, it was not feasible to modify the shell/vessel to change the kerosene side stripper design only. Plot space and access to the unit were limited too, so adding and/or replacing the side strippers was impossible without substantial cost.

Test run and unit performance evaluation

Prior to any process evaluation, a dedicated crude unit test run was conducted to gather pertinent operating data. The importance of a test run cannot be stressed enough. Daily operating data do not always provide all the required information for reliable process evaluations. A crude slate containing high kerosene boiling range material was selected for the test run, as this represented a typical operating crude slate in the unit. For equipment limitation checking, the test run charge rate was determined as the maximum crude charge rate in which the crude unit operated without loss of fractionation efficiency.

In order to gather pertinent operating data, all associated instruments were calibrated prior to the test run. The measured flow rates were verified via flow meter orifice calculations and storage tankage levels, to establish whether mass balance closure error was within suitable range for reliable modeling.³ Traditional laboratory methods do not provide appropriate characterization for heavy oil boiling range material. The high temperature simulated distillation (HTSD) method was used for the reduced crude stream laboratory test to obtain better heavy boiling range material characterization.

Since distillation equipment pressure drop is related to column traffic, a survey of measured pressure drops across the column was required. This is a useful tool in column troubleshooting and evaluation. In particular, the survey allows the troubleshooter to pinpoint equipment locations that require further evaluation. The measured pressure drop profile through the column showed that the top pumparound pressure drop was over two times higher than the LGO and MGO pumparound section pressure drop on the same basis. In addition, the measured HGO packed bed pressure drop was much higher than expected. This pressure drop survey indicated that the column top and bottom sections might be more loaded than the middle sections.

Reliable simulation modeling is another cornerstone of successful process evaluation. Throughout the modern hydrocarbon industry, simulation is widely used to design and/ or analyze distillation column performance and it has become a basic tool for process engineering. Many design firms rely heavily on simulation modeling to establish heat and material balances. Commercially available steady-state process simulators are regularly upgraded with regards to thermodynamic packages, component and property databases, properties calculation, numerical method algorithms, software interfaces and other capabilities.

Nevertheless, selecting reputable simulation software does not guarantee the reliability of simulation modeling. Accurate simulation modeling still requires extensive knowledge and understanding of the process and equipment that need to be modeled. Inherent gaps between actual condition and theoretical simulation modeling should not be overlooked. It has been observed that unreliable simulation modeling that neglects these issues can lead to design flaws and performance deterioration. In an earlier article,⁴ it was discussed that conventional flow-sheeting topology does not adequately address refinery fractionators such as crude vacuum distillation columns. Actual flash zones operate in a non-equilibrium state, and fluid mixing through transfer lines is highly non-ideal. Conventional simulation topology commonly used in the industry does not predict crude column performance properly. This especially applies to the flash zone, transfer line, and wash and stripping sections.

During this crude atmospheric column simulation modeling, it was observed that conventional topology did not properly simulate energy loss through the transfer lines. Therefore, process solutions based on conventional simulation potentially under- or over-predict operating parameters. Such results may induce a performance shortfall or failure in a retrofit solution. To obtain reliable simulation modeling results, this crude atmospheric column was modeled using modified simulation topology. This updated modeling procedure dissected the column into multiple blocks to model the crude atmospheric column, the furnaces and the transfer line properly. The interval of pseudo components was adjusted to match the obtained laboratory distillation temperature span. Tray efficiency for each fractionation section was determined through various sensitivity analyses.

Root cause identification

This crude unit was originally designed and constructed to process high diesel and low kerosene content crude slates. That is why three pump around circuits were located in the diesel section, while a pump around circuit was omitted in the kerosene section. The design philosophy in this crude unit showed the best performance with diesel-rich and kerosene poor crude slates.

For the first step of root cause identification, the crude slate structure for the test run was compared with previous retrofit design crude slates. The test run crude and previous crude yield structure are illustrated in Figure 4. These yield structures were obtained using blending programs. The blending program predicts recoverable material yield with a clear-cut basis between products and does not take into consideration actual distillation column performance. Nevertheless, this crude structure comparison helps comprehend any deviation between the prior design and current operation environment. This graph shows that the test run crude slate contains much more kerosene boiling range materials than the previous retrofit design crudes. Petroleum gas and naphtha content were also increased in the test run crude slate, while diesel boiling range material percentages are almost the same for the two crude slates.

Figure 4 - Comparison of crude slate structure.

To scrutinize unit limitation and identify the root cause, the column traffic profiles were reviewed at the test run conditions. Existing tray and packing capacities for the test run case were calculated with simulated traffic extracted from the test run simulation. In Figure 5, the red line indicates simulated pumparound capacity at the test run condition. Capacities of previous retrofit design cases are plotted in green. These plots show that the top and HGO pumparound sections were run at high capacities, while the LGO and MGO pumparound sections were run at lower capacities. Relative loads among the four pumparound circuits were not optimized at the previous retrofit design stage, so this problem was exaggerated due to the current high kerosene crude slates.

Figure 5 - Simulated pumparound capacity.

One of the ways to improve pumparound balancing is to shift the top and HGO pumparound loads to LGO and MGO pumparound circuits. However, simple pumparound rate redistribution will impact fractionation in the existing column arrangement. Vapor and liquid traffic is decreased above the section where the pumparound rate is increased.² In this particular column, increasing the LGO and/or MGO pumparound rates would result in a reduction in the internal reflux of the naphtha-kerosene fractionation section and downgrade the separation between these products. One possible result is a reduced kerosene flash point and difficulty in meeting the specification. Simulation modeling for the test run case also verified that the fractionation sections in the crude atmospheric column were overly sensitive to the internal reflux rates. To compensate for this sensitivity, the crude column had been operated with high top pump-around rates and high internal reflux for naphtha and kerosene fractionation. Through these evaluations, it was determined that the pumparound design had not been optimum since the initial design stage. In addition, the crude feedstock change further aggravated the pumparound capacity. It was necessary to optimize the crude column design, including the pumparound rearrangement at current crude slate conditions, for maximum crude unit capacity and performance.

Current retrofit design

Based on the test run simulation results, a new simulation model for the current retrofit was developed. The existing tray performance with simulated traffic predicted that the existing single kerosene draw configuration could not produce the required kerosene yield. The current retrofit target yield required a much larger kerosene side stripper as well. As mentioned earlier, installation of a larger kerosene side stripper was not feasible. To increase the kerosene yield with a minimum mechanical modification scenario, the existing LGO draw was converted to a heavy kerosene draw. In this case, the number of kerosene draws was increased from one to two, while the gas oil draws were reduced from three to two. This retrofit strategy did not require any column nozzle and external piping configuration changes.

With these product layout conversions, the existing LGO and MGO pumparound circuits were converted to new heavy kerosene and new LGO pumparound circuits, respectively. The pumparound balance was optimized between the new LGO and HGO pumparound sections to improve overall capacity as well. The pumparound capacities of the current retrofit design are plotted in blue in Figure 5. These capacities are based on a new higher crude charge rate using new high-performance trays and new structured packing, as part of the current retrofit. A recognizable improvement in pumparound balancing is demonstrated in this graph. Process configuration changes per product and pumparound rearrangement are highlighted in Figure 6.

Figure 6 - Crude atmospheric column configurations after current retrofit.

These product and pumparound rearrangements resulted in a lower logarithmic mean temperature difference (LMTD) for the new heavy kerosene and new LGO pumparound circuits compared to previous services. A careful evaluation of the preheat train was required to make sure the new configuration did not result in a lower preheat temperature to the furnace and/or possibly reduced recovery or higher energy consumption. Some modifications to the preheat train and exchangers were completed to optimize the heat recovery at the new conditions.

An overall heat balance check, including furnaces, showed the desired feed temperature would be achieved at the current retrofit design condition. An existing distillation equipment evaluation with simulated traffic showed that the existing trays and HGO pumparound packing were unable to handle the required traffic at the current retrofit rates. To increase distillation equipment performance, all trays in the crude atmospheric column were replaced with high-performance trays.

One important point when tying simulation design to actual distillation equipment performance involves the effect of internal vapor and liquid distribution and the internal liquid-to-vapor (L/V) ratio in each section of the tower. Figure 7 illustrates the multiple internal vapor and liquid streams in a four-pass tray. Steady-state simulation modeling assumes that the ratios are equal, while in actual operation it is rarely this close. Poorly designed or imbalanced multi-pass trays and/or improper feed arrangements can exacerbate this problem, resulting in lower-than-expected tray efficiencies or, in some cases, a reduced ultimate capacity. Previous references have noted balancing methods for multi-pass trays in order to achieve this L/V ratio.⁵

Figure 7 - Multiple internal vapor and liquid streams in four-pass tray

The top pumparound return liquid distribution design was addressed during the current retrofit. In particular, four-pass trays were used for most of the pumparound circuits, and the existing top tray downcomers were positioned as two off center locations. Liquid must be irrigated to three inlet panels: one center and two side-positioned inlet panels. In this case, it is very difficult to achieve desired distribution using a conventional distributor, as each inlet needs a specific metered amount of liquid. The new distributor coupled with a balanced tray design must meter this liquid properly to insure the new targets are met.

During a previous turnaround, it was found that the top pumparound trays had lost a significant number of movable valve units from the tray decks. Valve/perforation hole wear and corrosion, which are common problems in this section, were the root cause. To alleviate the problem, the top pumparound active areas were replaced with fixed-valve decks. However, there were performance/fractionation variations after this previous replacement. Petroleum gas and naphtha yield structure and cooler performance varied the top pumparound circulation rates significantly. The liquid and vapor profile from the top to the bottom of the pumparound varied greatly. Detailed tray evaluation at various ranges of operation and crude slate structure showed an excessive tray-opening area, causing heavy weeping at the top tray of the pumparound. A review of tray drawings revealed that the same number of holes (same valve open area) was applied for each pumparound tray deck to simplify tray manufacture and reduce cost. For the current retrofit design, each top pumparound tray open area was re-arranged and optimized per simulated traffic. Tray open areas were progressively increased through the section to mitigate weeping. High-performance fixed valves were applied to meet the required top pumparound capacity.

The transition section design between fractionation and the LGO pumparound section also had distribution issues. However, space constraints meant it was not a simple matter of designing a feed pipe and transition to balance the tray flows. In this case, the number of passes for the LGO pumparound was changed from four to two, as four-pass trays were unnecessary. This change coupled with the new pumparound return piping alleviated any distribution issues.

The structured packing for the HGO pumparound was replaced with new packing as well. To increase packing capacity, a higher capacity packing was chosen. In this case, a big concern was a possible reduction in heat transfer efficiency, as higher capacity packing will generally result in lower efficiencies. However, careful understanding of the heat transfer coefficient calculations will allow the process designer to meet any duty requirements.

The bottom stripping section was also modified to maximize distillate recovery. Steam stripping trays are operated at low vapor and high liquid traffic. While a high amount of reduced crude is transported through the stripping tray downcomers, only stripped hydrocarbon and stripping steam are included in the vapor phase. The result is that the active area is not a controlling factor in determining stripping section capacity. Oversized open areas over an active area decrease vapor velocity. This low velocity does not generate enough froth for vapor and liquid contact and downgrades stripping efficiency. Weeping at the bottom stripping trays is a common problem in this section, especially as the vapor traffic at the bottom stripping tray contains only the stripping steam. The original stripping section consisted of five four-pass trays. Although five trays were assigned to this section, it was found that the last stripping tray was designed as a blind tray. The existing four-pass tray did not provide adequate steam distribution across the active panels and caused vapor channeling. This cross channeling can downgrade stripping efficiency as well. Increased stripping steam rates were used to compensate for the efficiency loss at the penalty of increased condenser load.

For the new tray design, the flow path quantity was reduced from four to two. New two-pass trays with optimum downcomer design would be able to handle the required flow rates, and many of the distribution issues would easily be solved. The average flow path of the liquid on each tray was increased as well, which helped enhance tray efficiency. The tray open area was optimized to maintain good vapor velocity. Special active area modifications also helped maintain the plug flow regime in the liquid phase. Cross channeling was corrected in the new tray design. The new light kerosene stripper trays were also modified with similar design philosophies.

Startup

The crude unit was shut down and modified according to the current retrofit design. The startup procedures of the crude distillation unit were reviewed and updated to match the current modifications. The effect of the lower pressure drop through the column and high-performance trays needed to be evaluated for successful unit startup and operation. Every aspect of the startup was considered to avoid undesired delays that might impact the refiner’s economics.

High-performance trays in this crude atmospheric column utilize a dynamic downcomer seal design. In this advanced design, the downcomer clearance is greater than the outlet weir height. The downcomer sealing is easily maintained with adequate liquid flow to prevent vapor from bypassing up the downcomer. However, extremely low liquid and vapor rates (below normal minimum operating conditions) may be encountered during initial startup. Thus, the downcomer seal may be lost, resulting in poor fractionation and other operating difficulties.³ To eliminate potential downcomer unsealing problems, the initial crude charge rate and the pumparound rates at startup were increased from previous startup initial charge rates, and the refinery operations team was trained in how to avoid such problems.

Light/heavy kerosene and LGO draw temperatures were also changed per pumparound rearrangement. The temperature profile change increased the difficulty in establishing heat and material balances during startup. Before increasing the initial charge rate to target capacity, all operating parameters were monitored and reviewed sufficiently after establishing heat and material balances at the initial charge rate.

Post current retrofit performance

This crude unit was successfully revamped and its target capacity was met. Table 1 summarizes pre and post current retrofit operating data. Two sets of test run data are shown to check unit performance. Test run 1 and 2 indicate operating data at kerosene- and diesel rich crude slates, respectively.

Table 1

Overall unit capacity has been expanded and kerosene-rich crude slates are processed without any limitation. Although the number of diesel pumparound circuits was reduced, the crude unit produces much higher diesel yields.

Column fractionation efficiencies are substantially improved. Fractionation efficiencies among products are enhanced at higher distillate production rates, lower stripping steam injection rates and lower furnace outlet temperature. The final processed crudes are actually heavier feedstock containing more atmospheric residue boiling range material. Separation between diesel and reduced crude is improved and the reduced crude 5% distillation temperature is increased, indicating improved diesel recovery.

Pressure drop is maintained or reduced at higher product yields. Lower flash zone pressures lift more distillates at the same furnace outlet temperature or reduce the furnace outlet temperature at the same distillates. This pressure drop improvement also help to minimize the energy consumption of the crude unit. Stripping steam savings help the refiner’s economics too.

References

1. Perry RH, Green D, Perry's Chemical Engineers' Handbook, McGraw-Hill Company, 6th Edition.

2. Libermann N P, Troubleshooting Process Operations, Pennwell Publishing Company, 3rd Edition.

3. Kister H Z Distillation Operation, McGraw-Hill Company, 1990.

4. Golden S, et al, Improved flow sheet topology for petroleum refinery crude vacuum distillation simulation,

44th Annual CSChE Conference, 1994

5. Bolles W L, Multipass flow distribution and mass transfer efficiency for distillation plates, AIChE Journal,

22,1, January 1976.

Authors

Soun Ho Lee is the Manager of Refining Application for GTC Technology, Irving, Texas, and specializes in process design simulation and troubleshooting for refining applications.

Ian Buttridge is the Manager of Technical Marketing for GTC Technology, Irving, Texas, and specializes in column revamps and energy saving for distillation trains in refining and petrochemical applications.

Jay J (Jae Jun) Ha is Senior Process Engineer of the project execution team for GS Caltex Corporation, Yeosu, Korea, and works in various retrofit projects including crude units.

This article also appears in PTQ Q2 2009 Issue (www.eptq.com )

15-Apr-09 8:00 AM

GTC Technology Secures Saudi Aramco Approval, Process Equipment Technology Contract

noemail@gtctech.com — Wed, 11 Aug 2010 13:00:00 GMT

HOUSTON, Texas, August 11, 2010 - GTC Technology, a global provider of process equipment technology and mass transfer solutions, is pleased to announce that it has secured on-going supplier approval and an immediate contract approval by Saudi Aramco, the largest oil corporation in the world, to provide mass transfer equipment through its manufacturing facility in South Korea. Following an extensive contractor review and evaluation process, GTC Technology Korea, a subsidiary of GTC Technology International LP, was selected to provide mass transfer equipment for Acid Gas Treating and Sour Water Stripping Units at the Saturated Gas Plant of the Jubail Export Refinery Project. This 400,000 barrel per day, full conversion facilitated refinery is owned by Saudi Aramco Total Refining and Petrochemical Company (SATORP), a joint venture between Saudi Aramco and Total S.A. Saudi Aramco, Saudi Arabia's state-owned national oil company, restricts products and services to only...

Holly Corporation Selects GTC Technology's Benzene Management Technology for Oklahoma, Utah Refineries

noemail@gtctech.com — Wed, 12 May 2010 14:00:00 GMT

HOUSTON, Texas, May 12, 2010 — GTC Technology US, LLC announced today it was selected by Holly Corporation (NYSE: HOC) and two subsidiaries to provide process design engineering and its licensed GT-BenZap® technology for benzene management and reduction. The licensed technology will support Holly’s efforts for compliance with EPA-mandated Mobile Source Air Toxics (MSAT2) benzene regulations. GTC’s benzene saturation process, GT-BenZap®, will reduce benzene concentration in the reformate gasoline stream at Holly Refining and Marketing’s refineries in Tulsa, Oklahoma and Woods Cross, Utah. GT-BenZap® is designed as a cost-efficient alternative for refiners with limited economy of scale for benzene recovery, or where the refinery is located far away from benzene consumers. “When the demands of MSAT2 required us to make facility modifications, we knew we needed a reliable, yet competitively priced alternative,” said Gary Fuller, Senior...

GTC Unveils New Brand Identity

noemail@gtctech.com — Fri, 12 Mar 2010 14:00:00 GMT

Houston, Texas, March 12, 2010 – Today GTC Technology US, LLC (GTC) formally unveiled a new brand identity. The new identity represents a significant milestone in GTC’s history. The new branding system simplifies and unifies GTC’s identity across all product lines and services in order to better communicate important characteristics and value to customers.

Pinti Wang, President and CEO of GTC Technology noted that “As GTC continued to evolve, we recognized the need to consolidate our visual identity in line with our growth and diversification of products and services in the hydrocarbon processing industry. Our new identity enables us to establish and communicate stronger connections with our clients and strengthen our overall position in the marketplace.”

The new brand is communicated through a new website, marketing literature, presentations, newsletters, and a range of additional marketing materials. “Engineered to Innovate,” is GTC’s unique brand promise to clients and was developed to concisely communicate GTC’s rich heritage of innovation focused on delivering world-class products and services to the hydrocarbon processing industry.

Headquartered in Houston, Texas, GTC Technology US, LLC is a global licensor of process technologies, offering engineering services, process equipment solutions, chemicals and catalysts to the chemical, petrochemical, refining and gas processing markets. With engineering, manufacturing facilities and a knowledgeable sales force located throughout the globe, GTC combines unparalleled industry expertise, powerful research capabilities and innovative thinking to deliver high-quality, strategic solutions for clients worldwide. www.gtctech.com

GTC Technology Opens New Office in Brno, Czech Republic

noemail@gtctech.com — Wed, 10 Feb 2010 17:00:00 GMT

Brno, Czech Republic, February 10, 2010 — GTC Technology today announced the launch of a new office located in Brno, Czech Republic. The new office will focus on serving the European and CIS markets, offering the full range of GTC products and services. The office will house a team of engineering, sales and technical service personnel.

“This move reflects GTC’s interest in reaching one of the international markets we have targeted for development. We are committed to our clients’ success and the new office will provide us with strategic access to better serve our growing regional client base,” said Pinti Wang, President and CEO of GTC Technology.

GTC Europe s.r.o. is a subsidiary of GTC International LP, a global licensor of process technologies, offering engineering services, process equipment solutions, chemicals and catalysts to the chemical, petrochemical, refining and gas processing markets. With engineering, manufacturing facilities and a knowledgeable sales force located throughout the globe, GTC combines unparalleled industry expertise, powerful research capabilities and innovative thinking to deliver high-quality, strategic solutions for clients worldwide. www.gtctech.com

GTC Technology Partners with NPP Neftehim to Offer a C5 C6 Isomerization Technology and Catalyst

noemail@gtctech.com — Tue, 17 Nov 2009 15:00:00 GMT

Houston, Texas, November 17, 2009 — GTC Technology US, LLC (GTC) today announced that it has signed an engineering and exclusive marketing agreement with NPP Neftehim to offer clients a proven mixed metal oxide isomerization catalyst “SI-2” and isomerization technology “Isomalk-2SM”. The new technology is capable of converting unbranched low-octane C5-C6 paraffins to octane boosting isomers with simultaneous benzene saturation in refinery streams. The SI-2 catalyst is a novel, highly effective Pt-containing, mixed metal, sulfated oxide isomerization catalyst. The technology is noted for its higher tolerance to moisture and other impurities and its ability to process a significant quantity of C7 components. “This isomerization technology allows refineries to process a heavier naphtha fraction, which often accompanies the operational changes to meet the MSAT II gasoline specifications for benzene, aromatics and sulfur. This partnership enables GTC...

GTC Technology Becomes a Member of Fractionation Research Inc.

noemail@gtctech.com — Fri, 22 May 2009 21:00:00 GMT

Houston, Texas, May 22, 2009 — GTC Technology US, LLC (GTC) today announced that it has joined Fractionation Research Inc. (FRI), a non-profit research consortium that independently tests commercial scale distillation equipment. FRI has put together a strong coalition of over 60 members including fortune 500 companies, linking suppliers and buyers together while promoting best practices in the industry. GTC intends to conduct tests at FRI and allow members to vigorously evaluate GTC Process Equipment Technology product lines. FRI will play an essential role in providing unbiased assessments of GTC’s products, offering clients a deeper understanding of product performance and function. “FRI is one of the most respected non-profit organizations in the industry and an influential voice in efforts to promote best practices and improve fractionation devices. Joining FRI further demonstrates our commitment to quality products and ultimately better value for our...

GTC Mexico Expands to New Manufacturing Facility

noemail@gtctech.com — Fri, 24 Apr 2009 19:30:00 GMT

Corregidora, Queretaro, Mexico, April 24, 2009 — GTC México (GTC) announced today that it has relocated to a larger manufacturing facility in Queretaro, Mexico. The new facility doubles fabrication space and includes investments in new equipment to accommodate the growing business needs and better serve GTC’s clients.

The new facility is expected to generate significant manufacturing efficiencies by improving production capability, flexibility, and flow of operations. The plant’s staff will initially focus on manufacturing of mass transfer products, reactors and drums. This includes conventional distillation equipment and unique high performance products such as the GT-OPTIM™ product line.

“The new facility will help sustain continued growth of GTC’s process equipment technology product lines. It will enable us to continue to fill our long-term commitment to delivering world class products to clients around the world,” said Casey Bowles, General Manager of GTC Mexico.

GTC Mexico is a joint venture between GTC International LP and Chemisa, S.A. The Mexico office serves the Mexican and Latin American markets by providing technical process solutions and state of the art equipment, including equipment for distillation units in refineries, petrochemical plants, and chemical plants. www.gtctech.com

Chemisa is an engineering company that offers equipment installation services to the chemical, petrochemical and refining industries. For more information visit www.chemisa.com.

PEMEX awards GTC Mexico EPC Contract at Ethylene Oxide Plant

noemail@gtctech.com — Mon, 30 Mar 2009 13:00:00 GMT

Queretaro, Mexico, March 30, 2009 — GTC Technology US, LLC (GTC) today announced that Petróleos Mexicanos (PEMEX) has awarded GTC México (GTC) an EPC contract to revamp their Ethylene Oxide plant. GTC was chosen based on proven solutions, plant operation reliability, and safety. As part of the agreement, GTC will provide major distillation columns, mass transfer equipment, reactors, chemicals, field engineering and installation work. This project will conclude the final phase of the 250,000 MTA Ethylene Oxide plant revamp.

“In today’s economic climate, where it is essential to do more with less, GTC Mexico can provide a strong technology foundation that is highly reliable while reducing PEMEX’s overall plant costs,” said Pinti Wang, President and CEO of GTC Technology.

GTC Mexico is a subsidiary of GTC International LP. The subsidiary serves the Mexican and Latin American markets by providing technical process solutions and state of the art equipment, including equipment for distillation units in refineries, petrochemical plants, and chemical plants. www.gtctech.com

For more information on PEMEX Petrochemicals visit www.ptq.pemex.com.

GTC Technology Reaches Marketing Cooperation Agreement with CrystaTech

noemail@gtctech.com — Wed, 14 Jan 2009 14:00:00 GMT

Houston, Texas, January 14, 2009 — GTC Technology US, LLC (GTC) has reached an agreement with CrystaTech to take their eco-friendly Mobile Sulfur Recovery Unit process technology into the China, India, and Russian markets. This technology will expand on GTC’s gas processing portfolio to a new method for H2S removal. The agreement also covers regional marketing of CrystaSulf, a liquid phase Claus H2S removal process. As part of the agreement, GTC will provide marketing support, engineering expertise and local experience to ensure the successful delivery of the advanced technologies to clients. “GTC chose to collaborate with CrystaTech because of their unique technology portfolio. This partnership will provide GTC with an expanded offering for sulfur removal in gas streams. By working with CrystaTech we will be able to deliver greater value to existing clients and offer the latest cutting edge technology to the gas processing industry. We look forward to a...

Petrochemical Holding GmbH chooses GTC Technology for Large Aromatics Project at Rafo

noemail@gtctech.com — Thu, 16 Oct 2008 20:00:00 GMT

Houston, Texas, October 16, 2008 — GTC Technology US, LLC (GTC) today announced that Petrochemical Holding GmbH, has chosen eight of GTC’s proprietary process technologies, CrystPXSM, GT-BTX PluSSM, GT-BTX®, GT-IsomPXSM, GT-TransAlkSM, GT-Aromatization, Pygas Hydrotreating, and Hydrodesulfurization for a major petrochemical project in its 3 MM tpa crude oil refinery in Oneşti, Romania. The aromatics complex, operated by S.C. Rafo S.A. is designed to produce 400 kta of Paraxylene and 200 kta of Benzene. The objective of the project is to generate paraxylene and benzene from low-value fuel streams. GTC’s innovative approach will upgrade the catalytic cracked products by direct recovery of aromatics from the FCC gasoline, with additional aromatics production from mixed olefins. The new configuration will completely eliminate motor gasoline production at the refinery. This approach is significantly less expensive and distinct from other processes, which...

Office Locations

Thu, 26 Aug 2010 19:55:08 GMT

Houston, Texas - Headquarters GTC Technology US, LLC 1001 S. Dairy Ashford, Suite 500 Houston, Texas 77077 USA Main: +1-281-597-4800 Fax: +1-281-597-0942 Toll Free: +1-877-693-4222 Directions to our office in Houston Bozeman, Montana GTC Research and Development 910 Technology Boulevard, Suite F Bozeman, Montana 59718 USA Main: +1-406-582-7417 Fax: +1-406-922-6440 Dallas, Texas GTC Process Equipment Technology 1333 Corporate Drive, Suite 320 Irving, Texas 75038 USA Main: +1-972-887-3802 Fax: +1-972-887-3826 China GTC (Beijing) Technology Inc. Room 2801 Building C of Kaixuancheng...

History

Thu, 27 May 2010 17:46:46 GMT

Headquartered in Houston, Texas, GTC Technology US, LLC (GTC) is a global licensor of process technologies, offering engineering services, process equipment solutions, chemicals and catalysts to the petrochemical, refining and gas processing markets. Our heritage of innovation expands more than a decade, dating back to 1994 as a process technology solutions division of Glitsch Inc., a mass transfer equipment company owned by Foster Wheeler Corporation. In 2002, GTC was taken private in a 50-50 joint venture between the GS Group and our management team, who recognized the need for an independent technology licensor in the chemical process industry. Over the next seven years, GTC experienced unprecedented growth, celebrating dozens of successful licenses while gaining quick recognition in the aromatics and refining fields. In 2009, GTC announced a change in ownership structure, selling individual minority interest in the company to SCG Chemicals and Süd-Chemie AG. The...

Technical Services

Thu, 27 May 2010 17:46:26 GMT

GTC's technical service team offers:

Process specific training for your operating and engineering staff
Plant inspection to ensure compliance with GTC's design requirements
Guidance on developing plant specific operating procedures
On-site advisory services 24 hours a day, 7 days a week during the pre-commissioning, commissioning, start-up, and initial operating phases of plant operation
Direction to enable safe achievement of full-scale production in a timely manner
Assistance in conducting performance guarantee test runs
On-going support in maintaining optimum process performance

Training is key to successfully adopting and implementing new technology. GTC's training courses are designed to enable our licensees to commission and operate their plants safely and efficiently. Utilizing customized operating guidelines developed by GTC, our classroom training courses provide in-depth coverage of the following topics:

Process fundamentals & operating variables
Startup and shutdown procedures
Troubleshooting guidelines
Process safety

Additional training needs are discussed with our licensees on a case-by-case basis and enhanced support is provided by GTC as required.

GTC also participates in HAZOP studies in conjunction with our proprietary technologies. HAZOP evaluations can be carried out at a client site, contractor site or in GTC's offices. Technical recommendations are based on our most recent units in operation while also incorporating the most up-to-date improvements in safe operation of plants.

Please contact us to learn more about our technical services available.

Heater Cleaning Technology

Thu, 27 May 2010 17:46:16 GMT

GTC can help clients eliminate slag buildup and other fire side fouling and extend time between major fired heater/boiler maintenance jobs with our advanced fired heater/boiler chemical cleaning technology. Our technology can improve heater efficiency without shutting down plant operations in a range of applications including refinery heaters, petrochemical fired heaters and oil-fired boilers.

Our fired heater/boiler chemical cleaning technology can be used to clean air preheaters (APH) by spraying our proprietary liquid chemical through specially designed nozzles, indirectly onto the radiant and convection tubes of the fired heater. The chemical vaporizes and covers the targeted exposed tube surfaces in a similar manner as the firebox chemicals. This process can also be completed without an APH bypass.

Our fired heater cleaning process has been proven to significantly increase feed throughput, lower fuel costs and reduce greenhouse gas emissions all without plant facility modifications. Our experienced staff can deliver online fired heater cleaning services in 2 -5 days depending on heater geometry, layout, operations and conditions. Please contact us to learn more about our advanced fired heater technology.

Chemicals & Catalysts

Thu, 27 May 2010 17:46:05 GMT

GTC's proprietary chemicals and catalysts are used within all of GTC-licensed technologies, and are available as part of a comprehensive technology transfer package for either grassroots projects or for revamp and replacement of existing process units. We offer a portfolio of Techtiv® series high-performing solvents that allow us to extend the range of operation and upgrade additional petrochemical components from wide boiling fractions. Our solvents have versatile applications which transform low-value materials into premium value petrochemicals. Our portfolio of catalysts include a selective toluene disproportionation catalyst (STDP), transalkylation catalyst, xylene isomerization catalyst, pygas hydrotreating catalyst and aromatization catalyst. To learn more about our chemicals and catalysts please contact us. Techtiv Series Solvents Techtiv® 100 Extractive Distillation Solvent Techtiv 100 is a proprietary blended solvent used in GTC's...

Site Services

Thu, 27 May 2010 17:45:57 GMT

Proper installation of process equipment is critical to a smooth and reliable unit start-up. GTC's Site Services can dispatch engineers and technicians to assist in efficiently installing equipment and upgrades.

GTC's approach will cover all of the project phases, including:

On-site supervision
Procurement
Scheduling
Mechanical completion
Pre-commissioning activities
Start-up and test runs

GTC is readily available to assist you in troubleshooting your operation before scheduled turnaround and during emergency shutdowns. For more information on our site services, please contact our site services team.

Replacement Services

Thu, 27 May 2010 17:45:48 GMT

GTC has worldwide distributors that can provide equivalent replacement to any kind of non-proprietary process equipment. With tight linkages between manufacturing and design we can respond quickly to regional demands with manufacturing and engineering facilities located in the U.S., Korea, China, Czech Republic, Singapore and Mexico as well as sales agents stationed around the globe. GTC offers:

Installation hardware
Conventional trays
Random packing and structured packing
Liquid and vapor distributors
Customized designs

For urgent replacement needs, please contact our replacement fast track team 24 hours a day, 7days a week.

Random Packing

Thu, 27 May 2010 17:45:38 GMT

GTC offers all commercial sizes and shapes of each generation of rings in metallic, non-metallic, carbon and alloy steel materials to achieve the optimum performance. We recommend random packing for high pressure gas absorption systems, cryogenic demethanizers, and other high pressure and/or high liquid rate systems where trays or structured packing are not the preferred choice.

Second Generation Plastic and Metal Rings

GTC's GT-PR^TM, second generation plastic and metal rings are easy to install and feature a 1:1 height and diameter aspect ratio. Clients can expect to achieve a low pressure drop and higher capacity and efficiency when using GTC's second generation plastic and metal rings.

Third Generation Plastic and Metal Rings

GT-IR^TM and GT-CR^TM are GTC's third generation plastic and metal rings that are well-suited to handle very high liquid applications, in particular where foaming is a concern. The geometric packing shapes have been developed to minimize foam while allowing greater liquid and vapor loads than older generations of packing.

Please contact us to learn more about our random packing.

Structured Packing

Thu, 27 May 2010 17:45:28 GMT

GTC's structured packing is designed to help clients achieve higher capacity, higher efficiency and lower pressure drop. When selecting structured packing, we advise our clients to consider several parameters that influence the performance of the equipment including crimp height, crimp inclination angle, element height, surface treatment, fouling tendency, system properties and service. Our corrugated sheet structured packing, the industry standard clients have come to expect, can be modified through the packing geometry, surface treatment and manipulation of variables in order to increase efficiency and capacity. Below is a full listing of our structured packing offerings, for more information please contact us. Industry Standard Corrugated Sheet Packing GTC's high efficiency structured packing, GT-PAKTM is designed to achieve maximum efficiency in column revamps or grassroots units and is available in perforated, textured or corrugated sheet metal and can be customized for all...

High Performance Fractionation Tray Tower Solutions

Thu, 27 May 2010 17:45:11 GMT

At GTC we work with each client to customize our extensive line of mass transfer technology trays for different process conditions from high pressure to vacuum conditions, fouling, polymerization and chemical reaction. We offer a wide variety of active devices including floating or fixed, rectangular or round, sieve, bubble caps and shed decks among others. All of our trays are designed to achieve optimum capacity and efficiency and our technology applies fundamental principles such as:

Liquid gradient elimination
Static head control
Plug flow optimization
Vapor dispersion injectors/contactors
Optimum vapor-liquid-distribution
Liquid flux management
Anti-fouling capability

Our GT-OPTIM^TM state-of-the-art high performance trays have been commercially proven in refinery, petrochemical, and chemical applications to achieve efficiency and capacity improvements over conventional trays. All of our trays can be constructed of standard or exotic materials with various downcomer designs such as straight, sloped, stepped, swept and truncated. In addition, our trays deliver performance improvement through higher turndown, less weepage and lower entrainment.

Please contact us to learn more about our high performance trays.

Lorem ipsum survey

noemail@gtctech.com — Thu, 10 Jan 2008 23:05:04 GMT

Objectives:

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Release Date: 10-Jan-08 5:05 PM
Expiration Date: 10-Apr-08 5:05 PM

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2008-01-10T23:05:04Z

Instructor: Instructor

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