GTC’s innovations center around:
- Technology licensing
- Engineering services
- Technical services
- Process equipment technology (PET)
- Energy saving services
- Chemicals and catalysts
- Research and development
Our patented suite of technologies fall broadly into the Petrochemical, Refinery, Gas Processing and Polyester Intermediates market segments. GTC’s petrochemical technologies available for license focus on value-added products from the steam cracker including BTX, styrene, naphthalene and various C5s. It is important for crackers using liquid feedstocks to upgrade all of the by-products in order to maintain competitiveness with the crackers using low-cost ethane feedstock. Our refining technologies upgrade fuel streams or convert fuel to higher value petrochemicals. These include CCR naphtha reforming, light naphtha isomerization and direct recovery of BTX from FCC gasoline.
GTC’s portfolio also includes a range of processes for meeting the clean fuels mandate for benzene reduction and low-sulfur products. In the polyester value chain, GTC’s licensees can benefit from breakthrough technology to reduce bromine and burning losses in the PTA oxidation system and avoid the high-pressure hydrogenation system to purify the TA. We offer a hybrid adsorption/crystallization scheme for PX recovery, and conversion of all aromatics in the raw material in xylenes, with the option for zero benzene co-production using our toluene alkylation process.
Our portfolio comrpises, among others:
GT-BTX®: Aromatics Recovery
Using Extractive Distillation GT-BTX® removes benzene, toluene and xylenes (BTX) from refinery, petrochemical or coke oven aromatics streams such as catalytic reformate, pyrolysis gasoline or coke oven light oil (COLO).
GT-BTX® is an aromatics recovery technology that uses extractive distillation to remove benzene, toluene and xylene (BTX) from refinery, petrochemical or coke oven aromatics streams such as catalytic reformate, pyrolysis gasoline or coke oven light oil (COLO). With lower capital and operating costs, simplicity of operation, a wider range of feedstock and solvent performance, extractive distillation is superior to conventional liquid-liquid extraction processes. Flexibility of design allows use for grassroots aromatics recovery units, debottlenecking, or expansion of conventional extraction systems.
Sulzer GTC’s GT-BTX process is a result of extensive testing of extractive distillation solvents and blends. Our experience indicates that certain combinations of solvent components enhance extraction performance. Co-solvents also provide an additional parameter for the optimization of unit performance (e.g., stability, mass transfer efficiency). GT-BTX utilizes the Techtiv-100® extractive distillation solvent which provides optimum extractive distillation performance. GT-BTX has no special feed preparation requirements and is capable of handling a wide-range (BTX) feedstock while producing very high aromatics purities (99.99 wt.% plus) at high recoveries (99.9 % plus).
The flow scheme of the GT-BTX process consists of two columns: an extractive distillation column (EDC) and a solvent recovery column (SRC).
Since the basic separation in the GT-BTX process is achieved by distillation, the operation of the unit is very simple and intuitive. Control of the main process parameters are achieved in a manner similar to that of a regular distillation column.
Hydrocarbon feed is preheated with hot circulating solvent and fed at a mid-point into the EDC. Lean solvent is fed at an upper point and selectively extracts the aromatics into the tower bottoms in a vapor/liquid distillation operation. The non-aromatics hydrocarbons exit from the top of the column. A portion of the overhead stream is returned to the top of the column as reflux, which washes back any entrained solvent.
Rich solvent from the bottom of the EDC is routed to the SRC, where the aromatics are stripped overhead. The SRC is operated under a vacuum to reduce the boiling point at the bottom of the column.
Lean solvent from the bottom of the SRC is passed through a heat exchanger before returning to the EDC. A small portion of the lean circulating solvent is processed in a solvent regeneration step to remove heavy decomposition products.
The SRC overhead mixed aromatics product is routed to the purification section, where it is fractionated to produce chemical-grade benzene, toluene and xylenes.
The benefits of extractive distillation, particularly those highlighted by GT-BTX technology, may be summarized as follows:
- Simple two-column ED system which requires 30-40 percent lower capital cost than conventional liquid-liquid extraction systems
- Carbon steel construction throughout
- Smaller plot requirement than other systems
- Lower solvent inventory that further reduces investment requirement
- Solvent blend exhibits highest selectivity among all others in commercial use. Solvent properties allow wide boiling range materials (C5- C9) to be fed into unit, with varying aromatics content
- A short time is required to stabilize unit (few hours vs. few days with liquid-liquid extraction systems)
- Lowest specific energy consumption (20-30 percent less than others)
- Very low solvent consumption and circulation rates
- Higher product purity and aromatic recovery
- Insignificant fouling compared to liquid-liquid contactors
- The benzene product from GT-BTX is nitrogen free. Unlike some competing solvents, GTC’s solvent is free of basic nitrogen containing components, which permanently poison the catalyst in many benzene consuming units
FCC Gasoline Desulfurization Technology
Meeting the World’s Clean Gasoline Needs
GT-BTX PluS is a variation of GT-BTX that uses extractive distillation technology for simultaneous recovery of BTX and thiophenic sulfur species from refinery or petrochemical aromatic-containing streams. The technology helps produce low sulfur gasoline meeting the 10 ppm limit of sulfur without change in octane value. An alternative use of GT-BTX PluS is to generate a large volume of aromatics to produce paraxylene without the requirement of a typical naphtha reformer unit. The aromatics recovery is especially attractive for use with feedstocks produced from high severity FCC operations.
The process is optimally installed on the FCC mid-cut naphtha stream. GT-BTX PluS removes all thiophenes and some of the mercaptan species from the FCC gasoline feed. The olefin-rich raffinate can be sent directly to the gasoline pool for blending, or to a caustic treating unit to remove the mercaptan-type sulfur compounds before being sent to the gasoline. The desulfurized aromatics extract stream can be directly fed into petrochemical production units instead of recycling to the naphtha reformer. GT-BTX PluS provides an effective solution for meeting today’s clean gasoline requirements and gives refiners the ability to convert lower-value gasoline components into higher-value petrochemicals.
The optimum feed is the mid fraction of FCC gasoline from 70°C to 150°C. This material is fed to the GT-BTX PluS unit, which extracts the sulfur and aromatics from the hydrocarbon stream. The sulfur-containing aromatic components are processed in a conventional hydrotreater to convert the sulfur into hydrogen sulfide (H2S). Because the portion of gasoline being hydrotreated is reduced in volume and free of olefins, hydrogen consumption and operating costs are greatly reduced. In contrast, conventional desulfurization schemes must process the majority of the gasoline through hydrotreating units to remove sulfur, which inevitably results in olefin saturation, octane downgrade and yield loss.
FCC gasoline is fed to the extractive distillation column (EDC). In a vapor-liquid operation, the solvent extracts the sulfur compounds into the bottoms of the column along with the aromatic components while rejecting the olefins and non-aromatics into the overhead as raffinate. Nearly all of the non-aromatics, including olefins, are effectively separated into the raffinate stream. The raffinate stream can be optionally caustic washed before routing to the gasoline pool or to an aromatization unit to further increase benzene, toluene and xylene (BTX) production.
Rich solvent, containing aromatics and sulfur compounds, is routed to the solvent recovery column (SRC), where the hydrocarbons and sulfur species are separated, and lean solvent is recovered in columns bottoms. The SRC overhead is hydrotreated by conventional means and either used as desulfurized gasoline or directed to an aromatics plant. Lean solvent from the SRC bottoms is recycled back to the EDC.
- Reduced OPEX and CAPEX in desulfurization from treating full-range naphtha.
- Less hydrogen consumed than if the full-range material were hydrotreated.
- HDS function required only for sulfur removal.
- Octane value fully retained due to the diversion of feed olefins from hydrotreater.
- Gasoline yield completely maintained.
- High-quality aromatics produced from FCC gasoline.
- Sulfur content of the FCC gasoline fraction being sent to the gasoline pool reduced to less than 20 ppm.
- Segregated olefin-rich stream may be converted into propylene or additional aromatics.
- Greater utilization of the naphtha reformer, compared to units that recycle the cracked gasoline.
- Opportunity to feed more fresh naphtha and generate more hydrogen.
GT-DWC® - Dividing Wall Column Design Saves Costs and Energy
Dividing Wall Column Design Saves Costs and Energy
Sulzer GTC Technology’s process equipment technology offerings can include the dividing wall column (DWC), which separates a multi-component feed into three or more purified streams within a single tower, thereby eliminating the need for a second column. This design saves capital and energy costs normally invested in a separation unit.
The DWC design uses a vertical wall to divide the middle of the column into two sections. The feed is sent to one side of the column called the pre-fractionation section. There the light components travel up the column where they are purified while the heavy components travel down the column. The liquid flow from the column’s top and the vapor flow from the bottom are routed to their respective sides of the dividing wall.
From the opposite side of the wall, the side product is removed from the area where the middle boiling components are most concentrated. This arrangement is capable of producing a much purer middle product than a conventional side draw column of the same duty, and at a higher flow rate. And for the same product specifications, GTC-DWC requires substantially lower capital and operating cost than a conventional two-column system.
The technology is especially suited for removing a heartcut from a multi-component mixture, where the alternative is a series of fractionating Towers
Benefits of GT-DWC
Process Design and Control Scheme
- Conceptual design to basic engineering package of the dividing wall column, coupled with dynamic simulation modeling, ensures reliable process design and a solution that is optimized for your specific application.
- DWC Internals
- Sulzer GTC is a leading supplier for column internals of all types.
- Our integration of process and application knowledge results in innovative designs of DWC internals.
- Sulzer GTC internals ensure correct pressure balance and arrangement along with internal distribution. This is the key to reliable, trouble-free operation of dividing wall columns.
- Sulzer GTC provides detailed engineering, procurement and construction management for all DWC applications.
Maximizing LPG Recovery from Fuel Gas Using a Dividing Wall Column
Refinery off gas is a mixture of hydrogen and hydrocarbons from various units within the refinery, pooled together to be used as a fuel for heating purposes. The fuel gas contains valuable components such as propane, which can provide additional revenue to the refinery. The economics of LPG recovery fluctuates with LPG pricing and energy cost. GT-LPG Max provides a cost-effective solution for recovering LPG product using a novel process concept of absorption plus distillation within the same fractionating vessel. The technology is well suited for low-pressure refinery off gas as well as associated natural gas streams. The process is based on avoiding thermodynamic inefficiencies in conventional absorption and distillation columns by incorporating the unit operations in a single top dividing wall column (DWC). The feed side of the top DWC recovers the C3+ components from the fuel gas through absorption. The other side of the DWC uses distillation to split between C3 and C4 components to produce LPG product.
GT-LPG Max offers the following benefits:
- 99% propane recovery without the use of external refrigeration
- Lower operating pressure (200 – 250 psig)
- Lower CAPEX and OPEX
- PX in xylenes reaches thermodynamic equilibrium after reaction
- EB dealkylation to benzene or isomerization to xylenes. With the EB-dealkylation catalyst, the by-product benzene is produced at high purity by simple distillation
- Low H2/HC, high WHSV, low xylenes loss
- Long cycle length
- Efficient heat integration scheme reduces energy consumption
- Turnkey package for high purity benzene, toluene, and paraxylene production available
Styrene recovery from raw pyrolysis gasoline (pygas) derived from the steam cracking of naphtha, gas oils, and natural gas liquids (NGL)
GT-Styrene is Sulzer GTC’s extractive distillation process that directly recovers styrene from the raw pyrolysis gasoline derived from the steam cracking of naphtha, gas oils, and natural gas liquids (NGL). The styrene, produced at high purities and suitable for polymerization, is a less costly alternative to conventional styrene production routes. If desired, the mixed xylenes can also be extracted from the pygas, raising their value as a chemical feedstock. Our GT-Styrene process is economically attractive to steam cracker operators which produce greater than 500 KMTA ethylene from liquids feedstock.
Raw pyrolysis gasoline is prefractionated into a heartcut C8 stream. The resulting styrene concentrate is fed to an ED column and mixed with a selective solvent, which extracts the styrene to the tower bottoms. The rich solvent mixture is routed to a solvent recovery column (SRC), which recycles the lean solvent back to the ED column and recovers the styrene overhead. A final purification step produces a 99.9% styrene product containing less than 50-ppm phenyl acetylene. The ED column overhead can be further processed to recover a high-quality mixed-xylene stream. A typical world-scale cracker can produce approximately 25,000 tpy styrene and 75,000 tpy mixed xylenes from pyrolysis gasoline.
- Produces polymer-grade styrene at 99.9% purity
- Allows the recovery of isomer-quality mixed xylenes for paraxylene production
- Debottlenecks pygas hydrotreater and extends cycle length
- Reduces hydrogen consumed in hydrotreating
- Optimized solvent system and design provide economical operating costs