HYBRID C02 CAPTURE
Cement manufacture accounts for as much as 7% of global greenhouse gas (GHG) emissions. A new hybrid technology being developed at Sintef (Tronheim, Norway; www.sintef.no) promises to make it easier and less expensive to capture and purify C02 from the fluegas of cement plants. The technology, which combines membrane separation and “forced liquification” of C02, can be retrofitted to an existing plant.
Sintef researchers anticipate that the method can be utilized by cement factories and in other industrial processes in coastal areas and along European rivers, because liquefied CO2 can be transported by ship.
Normally, the fluegas emitted from a cement factory contains about 20 vol.% C02. In order to transport or store the C02 from these gases, the C02 has to be captured and concentrated to a minimum of 95% purity. However, conventional scrubbing technology requires large amounts of heat for regenerating solvents.
In Sintef’s hybrid approach, membrane separation is first used to generate 70% purity C02. Then, an in-house developed system is used to liquefy the C02 by cooling it under pressure. In a laboratory test rig, the system has achieved a C02 purity of up to 99,8%. The process uses electricity to cool and compress the gas. instead of steam to regenerate solvents, which is important for facilities lacking a steam generator.
PENNYCRESS OIL
Researchers from the University of North Texas (Denton, Tex.; www.unt.edu) are working on a project to boost the production of seed oil produced by the pennycress plant. This research, supported by the U.S. Dept, of Energy’s Office of Biological and Environmental Research, aims to optimize the amount of seed oil produced per plant. “This can be done using traditional cross-breeding methods or bioengineering (or both),” says Ana Alonso, associate professor in the BioDiscovery Institute and the Dept, of BioJogical Sciences. Alonso is planning to increase the seed-oil yield because, when properly processed, the common pennycress can produce 100 gal/acre of oil, which can then be processed into aviation fuel. “The main variety of pennycress found in the U.S. produces around 30 wt.% seed oil. But, we have found some varieties that can produce upwards of 42 wt.%,” she says.
Renewable JET Fuel
At the end of last October, euglena Co. (Tokyo, Japan; www.euglena.jp) completed the construction of Japan’s first demonstration plant for the production of renewable jet and diesel fuel in Yokohama. The S58-million pilot plant, located at the company’s Yokohama site, has a production capacity of 5 barrels per day (bbl/d; about 125,000 IVyr) of renewable liquid fuels, using the Biofuels isoconversion Process (BIC). Euglena expects to supply a next-generation renewable diesel fuel this summer, and to achieve revenue-generating flights with renewable jet fuel in 2020. On this project, euglena is collaborating with the City of Yokohama, Chiyoda Corp., Itochu Enex Co.. Isuzu Motors Ltd.. ANA Holdings Inc., and Hiroshima Council for the Promotion of Collaboration between Government, Academia and the Automobile Industry.
The demonstration plant will begin full-scale operation in spring 2019 and begin producing renewable jet and diesel fuel using Euglena, microaigae and waste cooking oil as raw material.
P-RECOVERY
A 10-gal/min pilot system for a phosphorus-recovery technology was operated at the Madison (Wisconsin) Metropolitan Sewerage District during October and November 2018. The technology, known as CalPrex. incorporates a thickened sludge fermentation tank to increase the amount of soluble and reactive species of phosphorus, thereby increasing the recovery potential of that phosphorus, and produces a P-containing mineral for use as agricultural fertilizer (see Chem. Eng., June 2017, p. 9). The pilot project is being run by the Water Research Foundation (WRF), and the technology was developed at the University of Wisconsin at Madison. Results of the project will help water-resource recovery facilities evaluate and benchmark state-of-the-art alternatives for removing phosphorus from sludge going to digesters. An expert review of he project findings will be conducted, and the results will be disseminated to industry professionals in May 2019.
Hg Removal
Researchers from Chalmers niversity of Technology (Goteborg, Sweden; www.chalmers.se) have developed a patent-pending method for emoving mercury from wastewater. The technique, known as electrochemical alloying, is described in a recent issue of Nature Communications.
In the process, a platinum electrode is used to draw the mercury ions out of solution to form a stable alloy. Because each Pt atom can “bond” with four Hg atoms, the electrode has a high capacity, and it can be regenerated when loaded in a controlled way. The method is selective for removing only Hg from water, and has been shown to reduce Hg concentrations in a liquid by more than 99%. A company, Atium AB (Goteborg, Sweden; www.atium.se), has been established to commercialize the discovery. Currently, a prototype device is being developed for performing field tests.
White Oil and Wax Hydrotreating Process by Uhde
Application: Process to produce white oils and waxes.
Feeds: Nonrefined as well as solvent- or hydrogen-refined naphthenic or paraffinic vacuum distillates or deoiled waxes.
Products: Technical- and medical-grade white oils and waxes for plasticizer, textile, cosmetic, pharmaceutical and food industries. Products are in accordance with the US Food and Drug Administration (FDA) regulations and the German Pharmacopoeia (DAB 8 and DAB 9) specifications.
Description: This catalytic hydrotreating process uses two reactors. Hydrogen and feed are heated upstream of the first reaction zone (containing a special presulfided NiMo/alumina catalyst) and are separated downstream of the reactors into the main product and byproducts (hydrogen sulfide and light hydrocarbons). A stripping column permits adjusting product specifications for technical-grade white oil or feed to the second hydrogenation stage.
When hydrotreating waxes, however, medical quality is obtained in the one-stage process. In the second reactor, the feed is passed over a highly active hydrogenation catalyst to achieve a very low level of aromatics, especially of polynuclear compounds. This scheme permits each stage to operate independently and to produce technical- or medical-grade white oils separately. Yields after the first stage range from 85% to 99% depending on feedstock. Yields from the second hydrogenation step are nearly 100%. When treating waxes, the yield is approximately 98%.
Licensor: Uhde GmbH.
Wax Hydrotreating Process by Bechtel Corp
Application: Hydrogen finishing technology has largely replaced clay treatment of low-oil-content waxes to produce food- and medicinalgrade product specifications (color, UV absorbency and sulfur) in new units. Advantages include lower operating costs, elimination of environmental concerns regarding clay disposal and regeneration, and higher net wax product yields.
Bechtel has been offering for license the Wax Hy-Finishing process. Bechtel now is marketing a line of modular, standard hydrogen finishing units for wax treatment. Standard sizes are 500, 1,000, 2,000 and 3,000-bpsd feedrate.
The core of the unit is standardized; however, individual modules are modified as needed for specific client needs. This unit will be fabricated to industry standards in a shop environment and delivered to the plant site as an essentially complete unit. Cost and schedule reductions of at least 20% over conventional stick-built units are expected. The standard licensor’s process guarantees and contractor’s performance guarantees (hydraulic and mechanical) come with the modules.
Description: Hard-wax feed is mixed with hydrogen (recycle plus makeup), preheated, and charged to a fixed-bed hydrotreating reactor (1). The reactor effluent is cooled in exchange with the mixed feed-hydrogen stream. Gas-liquid separation of the effluent occurs first in the hot separator (2) then in the cold separator (3). The hydrocarbon liquid stream from each of the two separators is sent to the product stripper (4) to remove the remaining gas and unstabilized distillate from the wax product, and the product is dried in a vacuum flash (5). Gas from the cold separator is either compressed and recycled to the reactor or purged from the unit if the design is for once-through hydrogen.
Licensor: Bechtel Corp.
Slack Wax Deoiling Process by Uhde GmbH
Application: Process to produce high-melting and low-oil containing hard wax products for a wide range of applications.
Feeds: Different types of slack waxes from lube dewaxing units, including macrocrystalline (paraffinic) and microcrystalline wax (from residual oil). Oil contents typically range from 5–25 wt%.
Products: Wax products with an oil content of less than 0.5 wt%, except for the microcrystalline paraffins, which may have a somewhat higher oil content. The deoiled wax can be processed further to produce highquality, food-grade wax.
Description: Warm slack wax is dissolved in a mixture of solvents and cooled by heat exchange with cold main filtrate. Cold wash filtrate is added to the mixture, which is chilled to filtration temperature in scraped-type coolers. Crystallized wax is separated from the solution in a rotary drum filter (stage 1). The main filtrate is pumped to the soft-wax solvent recovery section. Oil is removed from the wax cake in the filter by thorough washing with chilled solvent.
The wax cake of the first filter stage consists mainly of hard wax and solvent but still contains some oil and soft wax. Therefore, it is blown off the filter surface and is again mixed with solvent and repulped in an agitated vessel. From there the slurry is fed to the filter stage 2 and the wax cake is washed again with oil-free solvent. The solvent containing hard wax is pumped to a solvent recovery system. The filtrate streams of filter stage 2 are returned to the process, the main filtrate as initial dilution to the crystallization section, and the wash filtrate as repulp solvent.
The solvent recovery sections serve to separate solvent from the hard wax respectively from the soft wax. These sections yield oil-free hard wax and soft wax (or foots oil).
Utility requirements (slack wax feed containing 20 wt% oil, per metric
ton of feed):
Steam, LP, kg 1,500
Water, cooling, m3 120
Electricity, kWh 250
Licensor: Uhde GmbH.
Dewaxing/wax Deoiling Process by Bechtel
Application: Bechtel’s Dewaxing/Wax Fractionation processes are used to remove waxy components from lubrication base-oil streams to simultaneously meet desired low-temperature properties for dewaxed oils and produce hard wax as a premium byproduct.
Description: Bechtel’s two-stage solvent dewaxing process can be expanded to simultaneously produce hard wax by adding a third deoiling stage using the Wax Fractionation process. Waxy feedstock (raffinate, distillate or deasphalted oil) is mixed with a binary-solvent system and chilled in a very closely controlled manner in scraped-surface doublepipe exchangers (1) and refrigerated chillers (2) to form a wax/oil/solvent slurry.
The slurry is filtered through the primary filter stage (3) and dewaxed oil mixture is routed to the dewaxed oil recovery section (6) to separate solvent from oil. Prior to solvent recovery, the primary filtrate is used to cool the feed/solvent mixture (1).
Wax from the primary stage is slurried with cold solvent and filtered again in the repulp filter (4) to reduce the oil content to approximately 10%. The repulp filtrate is reused as dilution solvent in the feed chilling train. The low-oil content slack wax is warmed by mixing with warm solvent to melt the low-melting-point waxes (soft wax) and is filtered in a third stage filtration (5) to separate the hard wax from the soft wax. The hard and soft wax mixtures are each routed to solvent recovery sections (7,8) to remove solvent from the product streams (hard wax and soft wax). The recovered solvent is collected, dried (9) and recycled back to the chilling and filtration sections.
Licensor: Bechtel Corp.
Dewaxing Process by Chevron Lummus Global LLC
Application: Selectively convert feedstock’s waxy molecules by isomerization in the presence of ISODEWAXING Catalysts. The high-quality products can meet stringent cold flow properties and viscosity index (VI) requirements for Group II or Group III baseoils.
Description: ISODEWAXING Catalysts are very special catalysts that convert feedstocks with waxy molecules (containing long, paraffinic chains) into two or three main branch isomers that have low-pour points. The product also has low aromatics content. Typical feeds are: raffinates, slack wax, foots oil, hydrotreated VGO, hydrotreated DAO and unconverted oil from hydrocracking.
As shown in the simplified flow diagram, waxy feedstocks are mixed with recycle hydrogen and fresh makeup hydrogen, heated and charged to a reactor containing ISODEWAXING Catalyst (1). The effluent will have a much lower pour point and, depending on the operating severity, the aromatics content is reduced by 50– 80% in the dewaxing reactor.
In a typical configuration, the effluent from a dewaxing reactor is cooled down and sent to a finishing reactor (2) where the remaining single ring and multiple ring aromatics are further saturated by the ISOFINISHING Catalysts. The effluent is flashed in high-pressure and lowpressure separators (3, 4). Small amounts of light products are recovered in a fractionation system (5).
Yields: The base oil yields strongly depend on the feedstocks. For a typical low wax content feedstock, the base oil yield can be 90–95%. Higher wax feed will have a little lower base oil yield.
Licensor: Chevron Lummus Global LLC.