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[Display omitted] • Gas-processing routes studied: conventional and SS-THI-Reclamation with CO 2 capture. • SS-THI-Reclamation recovers methanol/ethanol/MEG from gas via supersonic separation. • SS-THI-Reclamation has −41% power demand, +10% revenues and +3% net present value. • SS-THI-Reclamation leverage affords post-combustion capture of 43% of CO 2 emissions. • SS-THI-Reclamation with carbon capture is the most sustainable raw-gas processing. Dew-point adjustments and reclamation of thermodynamic gas-hydrate inhibitors injected in subsea flowlines are common operations in offshore natural gas rigs characterized by high costs, power consumption and carbon emissions. Typically, offshore plants employ triethylene-glycol absorption for water dew-point adjustment and Joule–Thomson expansion for hydrocarbon dew-point adjustment, while hydrate inhibitor reclamation is applied only on aqueous-inhibitor streams for re-concentration. To implement economically sustained post-combustion carbon capture on offshore rigs, a more efficient gas processing is necessary. This work contemplates a new process – supersonic separator inhibitor-reclamation – which recovers inhibitors from saturated raw-gas via supersonic separation with liquid-water injection additionally yielding exportable liquefied-petroleum-gas and natural gas with adjusted dew-points. This process dramatically improves profitability for thermodynamic inhibitors methanol, ethanol and monoethylene-glycol, creating an economic leverage that affords a post-combustion capture plant avoiding about 43% of carbon emissions. Even including post-combustion capture penalties, the supersonic separator inhibitor-reclamation process achieves a higher net value than the conventional gas processing without carbon capture. A multi-criteria sustainability assessment, based on quantitative metrics and qualitative aspects over all sustainability dimensions, evinces the supersonic separator inhibitor-reclamation process with carbon capture as more sustainable than the conventional counterpart for all inhibitors, whereas among the three inhibitors, the gas processing with monoethylene-glycol was ranked as the more sustainable for offshore rigs. [ABSTRACT FROM AUTHOR]

Supersonic separators offer a cleaner offshore processing of natural gas with carbon dioxide content from deep-water oil-gas fields. Conventional offshore gas processing comprises water dew-point adjustment via glycol-absorption, hydrocarbon dew-point adjustment via Joule-Thomson expansion, and carbon dioxide removal via membrane-permeation. Alternative processing contemplates the use of supersonic separators for adjusting gas dew-points followed by carbon dioxide capture via membrane-permeation (so-called SS-MP scheme); or for adjusting gas dew-points and also accomplishing carbon dioxide abatement (so-called SS-SS scheme). The conventional process is environmentally and economically compared with SS-MP and SS-SS for application in offshore rigs treating raw gas (44%mol carbon dioxide) to produce exportable fuel-gas (≈20%mol carbon dioxide), while dispatching carbon dioxide rich fluid (≈75%mol carbon dioxide) for enhanced oil recovery in the oil-gas field. Results show that SS-MP requires 7.8% less power than the conventional process. Moreover, implementing SS-SS deepens the advantage against the conventional operation because SS-SS produces carbon dioxide rich fluid at high-pressure, requiring much less compression power for enhanced oil recovery than the low-pressure permeate from membrane-permeation. SS-SS has lowest carbon emission (−28.3%), lowest power consumption (−21.3%) and best economic performance: lowest manufacturing cost and lowest compressor investment. Thus, SS-SS is the overall best and cleanest solution, with highest 20 years net value (+860 MMUSD) and lowest environmental impact. Image 1 • Supersonic separator offshore processing of CO 2 -rich natural gas is investigated. • Conventional technologies are compared to full utilization of supersonic separators. • Supersonic separator is best economic and emissions option for dew-point adjustment. • Supersonic separator for CO 2 capture lowers emissions, gas-firing and investment. • Two consecutive supersonic separator units lead to cleaner CO 2 -rich gas processing. [ABSTRACT FROM AUTHOR]

Some deep-water offshore fields produce oil with high gas/oil ratios and ultra-high %CO 2 (>60%mol) with the onus of processing low-grade gas simultaneously handling huge CO 2 dispatch goals. Thus, processing solutions are needed to make feasible such high-capacity gas rigs hundreds of kilometers offshore. Feasibility relies on the choices for CO 2 capture and adjustment of water and hydrocarbon dew-points of such high flow rate gas. This problem was approached adopting supersonic separators for dew-point adjustments and for CO 2 capture on a floating-hub processing 50 MMsm ³/d of CO 2 ultra-rich gas, reinjecting 96% of treated CO 2 -rich gas for enhanced oil recovery, while reserving 4% as fuel-gas after CO 2 abatement to 20%mol for power production. Process alternatives were assessed in terms of power demand and profitability comparing supersonic separator with membrane-permeation for CO 2 removal. Results show that 1st supersonic separator for dew-point adjustments of raw gas recycling condensate to the oil-gas-water separator and 2nd supersonic separator for CO 2 removal avoiding CO 2 freeze-out, give optimum net present value and minimum CO 2 emissions. On one hand, these facts are consequences of less compressor investment as 2nd supersonic separator ejects pressurized CO 2 condensate requiring 5% less compression power for enhanced oil recovery relatively to the power required by the low-pressure CO 2 -rich permeate from the membrane-permeation alternative. On the other hand, the best net value of supersonic separator alternative also reflects its highest revenues derived from recycling condensate from 1st supersonic separator entailing 18% higher oil production. Image 1 • Offshore gas-hub for high-scale processing of 68% CO 2 natural gas is investigated. • Two serial supersonic separator units are the best economic option for gas-hub. • 1st supersonic separator unit adjusts water and hydrocarbon dew-points ejecting C3+. • 2nd supersonic separator unit removes CO 2 without freeze-out ejecting liquid CO 2. • 2nd supersonic separator economically outperforms membranes for limited CO 2 capture. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • New air pre-purification uses supersonic separator and finishing adsorption unit. • Supersonic separator abates 99% of air moisture as main purification service. • Adsorbent bed and regeneration heat are reduced by upstream supersonic separator. • Supersonic separator and finishing adsorption lower purified air cost to Cold-Box. • Supersonic separator, finishing adsorption and heat integration give best air cost. Abstract In commercial cryogenic manufacturing of oxygen, air to the Cold-Box must pass through a Pre-Purification Unit (PPU) to remove water, CO 2 and other impurities. The conventional PPU – FULL-TSA – comprises compression, cooling pre-dehydration and temperature-swing adsorption (TSA) for dehydration and CO 2 removal, supplying treated air at 3.1 bar. This work discloses a new PPU concept – SS-TSA – prescribing a supersonic separator (SS) upstream to TSA handling 98.5% of dehydration, greatly lowering TSA costs. SS-TSA comprises compression, cooling pre-dehydration, SS dehydration and a smaller TSA for finishing dehydration and CO 2 removal. A SS-TSA variant – TSA-HI – additionally recovers compression heat lowering heating costs. SS-TSA, FULL-TSA and SS-SS-TSA-HI were analyzed. Flowsheets were simulated in HYSYS with full thermodynamic SS modeling via a new HYSYS Unit Operation Extension – SS-UOE – rigorously calculating the multiphase sound speed. SS was designed for only 3.5% of head-loss, recovering 98.5% of water as super-cooled liquid, lowering make-up and chilled-water costs, while shrinking the TSA service to 10% of the FULL-TSA counterpart. For commercial-scale PPU considering 20 years of operation at 10% interest rate, the purified 3.1 bar air breakeven prices reached 5.28 , 5.19 , and 5.18 US$/kNm3 , respectively for FULL-TSA, SS-TSA and SS-TSA-HI, establishing superiority of SS alternatives over the conventional FULL-TSA. [ABSTRACT FROM AUTHOR]

Abstract Offshore oil/gas productions are power intensive and CO 2 emitters from gas-fired power generation. This work investigates supersonic separator as a strategy for affording post-combustion capture backed up by cost reductions. Conventional offshore gas processing usually loses thermodynamic hydrate inhibitor methanol in processing and exported gas. This work analyses a supersonic separator variant gas processing simultaneously reducing methanol losses. Such process dramatically improves gas-plant profitability via cost-reduction of methanol make-up and power-consumption, simultaneously increasing revenues from liquefied-petroleum-gas by-product. This economic leverage affords post-combustion carbon capture, including subsequent CO 2 dehydration and compression for exportation of high-pressure liquid CO 2. This corresponds to abate 43% of CO 2 emissions boosting revenues via enhanced oil recovery. Moreover, CO 2 is dehydrated via another supersonic separator operating with minimum head-loss, minimizing compression costs. Despite its much higher investment, the new process with carbon capture presents higher net value (865.63 MMUSD) than the conventional processing without carbon capture (829.31 MMUSD), being economically feasible and more environmentally adequate with cleaner natural gas production and successful CO 2 management. The new process is superior in several scenarios and particularly favored by oil prices above 55 USD/bbl. Rising oil price from 40 to 100 USD/bbl, the new process net value rises 29%, whereas the conventional counterpart rises only 7.5%. In addition, as a plausible future scenario, CO 2 taxation favors the new process, which always has superior economic performance, even without CO 2 taxation. In summary, implementing supersonic separators in offshore natural gas processing aiming at anti-hydrate recovery and CO 2 dehydration for enhanced oil recovery creates economic leverage sustaining Carbon Capture & Storage without loss of competitiveness. This result, backed up by rigorous thermodynamic simulations and economic-environmental assessments, configure an original achievement to the literature. Graphical abstract Image 1 Highlights • Novel design of CCS unit employing a supersonic separator is disclosed. • Supersonic separator-based gas processing is coupled to the novel CCS unit. • Supersonic separator alternative with CCS and conventional gas plant are simulated. • Reduction of 43% of CO 2 emissions is achieved with superior economic performance. • Economic sensitivity analysis shows CCS feasibility in several scenarios. [ABSTRACT FROM AUTHOR]

In offshore natural gas (NG) production, hydrate formation is a big concern that can impact the production and even stop NG flow. In this context, the injection of Thermodynamic Hydrate Inhibitors (THIs) in wellheads is widely employed in order to avoid these undesirable problems on subsea flowlines to gas processing rigs. However, in the main three-phase high-pressure separator in the gas rig, THI losses for gas phase are significant, particularly when the adopted THI is volatile like methanol and ethanol. This work discloses a new supersonic separator (SS) THI recovery process – SS-THI-Recovery – that treats the gas effluent from three-phase high-pressure separator achieving four simultaneous results: (i) gas water dew-point adjustment (WDPA); (ii) gas hydrocarbon dew-point adjustment (HCDPA); (iii) production of C3+ (propane and heavier) liquids as LPG; and (iv) recovery of almost all THI which would be lost in the gas otherwise. The proposition employs a supersonic separator (SS) battery followed by an anti-hydrates separator (LTX), a liquid-liquid THI extraction step and auxiliary THI distillation. SS-THI-Recovery was evaluated with HYSYS 8.8 simulator using methanol, ethanol and monoethylene glycol (MEG) as THIs. Supposing that the THI in the gas phase would be totally lost along with the exported gas otherwise, with SS-THI-Recovery the losses of methanol, ethanol and MEG were reduced by 91.9%, 79.3% and 99.2%, respectively, and such recovery factors could be further improved by increasing water flow rate in liquid-liquid THI extraction. Such high THI recovery entails reduction of THI costs with make-up, storage and transportation. Additionally, SS-THI-Recovery process is simple, with low footprint, and of easy implementation even for non-volatile THIs like MEG. Furthermore, the produced NG is ready for commercialization, dismissing additional treatment steps, not counting the commercial value of LPG. Therefore, new SS-THI-Recovery process configures an innovative and profitable alternative for gas treatment and THI recovery on gas processing offshore platforms. [ABSTRACT FROM AUTHOR]

A method is presented for calculating the thermodynamic sound speed of multiphase multi-reactive streams. A rigorous formula for the thermodynamic sound speed is developed via a steady-state, unidimensional, horizontal, adiabatic, frictionless, multiphase and multi-reactive equilibrium plug-flow. The main theoretical point is a correspondence between a multiphase multi-reactive plug-flow element and an Equilibrium Closed System (ECS), which has only two equilibrium state coordinates. Momentum and energy flow balances are processed via the ECS framework allowing the sound speed derivation for complex streams. The method uses ECS thermodynamic properties provided by multiphase Flash ( P,T ) of HYSYS 8.8 simulator. Unit Operation Extensions (UOE) are developed for calculating the multiphase multi-reactive sound speed by HYSYS. HYSYS solves the multiphase multi-reactive equilibria, including liquid water separation, to feed the ECS sound speed formula with required properties. The sound speed is also investigated in the critical neighborhood via the Landau Model approach to prove that it does not exhibit ± ∞ singularities at the critical point, despite the critical lambda-shape ± ∞ singularities of C ¯ P and ( T,P ) derivatives of the density. Multiphase examples are solved by the sound speed UOEs for simultaneous adjustments of water and hydrocarbon dew points of natural gas with supersonic separator. Multi-reactive multiphase sound speeds are also predicted in supersonic reactors for natural gas pyrolysis (GTL) and for two-phase methanol oxidation to formaldehyde. [ABSTRACT FROM AUTHOR]

The supersonic separator (SS) was investigated for treating humid natural gas with 44%mol CO 2 in offshore rigs and compared to the conventional Water Dew Point Adjustment (WDPA) via TEG Absorption, Hydrocarbon Dew Point Adjustment (HCDPA) via Joule-Thomson Expansion (JTE) and CO 2 removal via Membrane Permeation (MP). SS was tested as a single-step operation for WDPA + HCDPA. To simulate SS and MP, two Unit Operation Extensions (UOE) were developed for simulator HYSYS 8.8 (AspenTech). MP-UOE uses an empirical approach calibrated with operation data, whereas SS-UOE is entirely funded on thermodynamics, not demanding calibration. MP-UOE and SS-UOE use the thermodynamic infrastructure of HYSYS: property packages and several proved multiphase flash algorithms. MP-UOE and SS-UOE performed accordingly the expected characteristics of the respective operations and were critical to accomplish this analysis as SS and MP are not available in simulators. In terms of final gas quality (WDP ≤ -45 o C @ 1.01 bar , HCDP ≤ 0 o C @ 45 bar , %CO 2 ≤ 15%mol ) the best process configuration was found to be a hybrid one: SS WDPA + HDPA and MP CO 2 removal, with low footprint and low power demand (- 6.9% ) relative to conventional 3-step way. If used for CO 2 removal, SS could abate CO 2 from 44% to 21.85%mol . Albeit less effective than MP, SS CO 2 removal is a noticeable option that produces fuel gas for power generation with %CO 2 ≈ 20% as required by new turbo-shafts. Moreover, CO 2 is withdrawn from SS as a pumpable liquid allowing a cut of 44% in the power demanded for CO 2 separation and injection as EOR agent. [ABSTRACT FROM AUTHOR]

A novel carbon-capture-and-utilization route from extra-carbonated natural gas using low-cost/low-carbon chloralkali hydrogen is disclosed. Methanol and methane-rich gas are produced without direct carbon emissions and also with low indirect emissions assuming the local electricity-matrix as 87% non-emitting. Carbon dioxide removed from raw natural gas via cryogenic extractive distillation with methanol entrainer, feeds a new Carbon-Dioxide-to-Methanol hydrogenation route intensified by supersonic separators with liquid water injection for greater methanol conversion per pass in the synthesis-loop and greater methanol recovery in the separation system. Intensified Carbon-Dioxide-to-Methanol is designed economically optimizing water/methanol injection-ratios and maximum Mach numbers of supersonic separators. Extra-carbonated natural gas processing coupled to intensified Carbon-Dioxide-to-Methanol is techno-economically assessed, demonstrating that supersonic intensification entails 2% greater methanol production, 11% less power consumption and 7.5% greater net value comparatively to non-intensified counterpart. The intensified process removes 99.2% of CO 2 from extra-carbonated gas and was analyzed at two methanol scales [8021. 5 t/d , 1692. 3 t/d ] giving, respectively, [9.5, 41.5] payback-years, and [2896.4MMUSD, 41.37MMUSD] net values (60years). A critical feasibility factor is low-cost/low-carbon by-product hydrogen from chloralkali industries, for which the break-even prices were respectively evaluated for the two scales as [685USD/t H2 , 358USD/t H2 ]. A third, better and safer, option is to couple intensified Carbon-Dioxide-to-Methanol to large-scale Carbon-Dioxide-to-Enhanced-Oil-Recovery providing hedging against insufficient offer of low-cost/low-carbon hydrogen while practically keeping the project net value (60years) despite twofold investment. [Display omitted] • Supersonic separator with H 2 O injection intensifies CO 2 -to-Methanol process. • New carbon-capture-&-utilization from 72%CO 2 natural gas using CO 2 -to-Methanol. • Economic viability depends on low-price/low-carbon H 2 as chloralkali by-product. • Intensified CO 2 -to-Methanol financially enables 72%CO 2 natural gas processing. • CO 2 capture via cryogenic CH 3 OH extractive distillation with refrigeration-cascade. [ABSTRACT FROM AUTHOR]

Offshore processing of natural gas with 44%mol carbon dioxide at remote deep-water oil-and-gas fields is invariably characterized by low-efficiency power generation via gas-fired turbines releasing hot flue-gas and entailing high degradation of resources, high carbon emissions and low sustainability. This work demonstrates how to upgrade exergy utilization and consequently process sustainability by using supersonic separators in some gas processing steps; namely: (i) water dew-point adjustment; (ii) hydrocarbon dew-point adjustment; and (iii) carbon dioxide abatement to 20%mol. To accomplish this, the exergy performance of two supersonic separator gas processing alternatives are compared with conventional gas processing comprising triethylene-glycol absorption for water dew-point adjustment, Joule-Thomson expansion hydrocarbon dew-point adjustment and membrane-permeation carbon dioxide removal. Since exergy is measured relatively to a reference environmental reservoir, two such reference reservoirs are used: RER-1: standard atmosphere with 2%mol water containing hydrocarbons at combustion chemical equilibrium with air species; and RER-2: 1atm water-saturated raw natural gas in equilibrium with liquid water. Aspen-HYSYS simulations are used to solve mass/energy balances and thermodynamic property calculations. With RER-2 the conventional gas processing conserves 63.3% of the inlet exergy, while the two alternative supersonic separator processes attain 66.5% and 72.4% of exergy conservation, proving the associate gains of exergy efficiency and sustainability. [Display omitted] • Executed exergy analysis of CO 2 -rich natural gas upgrading via supersonic separator. • Raw natural gas reference reservoir allows obtaining realistic exergy efficiencies. • Gas processing with supersonic separators entails 35% less exergy destruction. • About 50% of destroyed exergy occurs in the compression systems of all routes. • Supersonic Separator overcomes membrane-permeation in exergy efficiency (93%:80%). [ABSTRACT FROM AUTHOR]

• New air pre-purification uses low-pressure supersonic separator for air dehydration. • Rigorous thermodynamic modeling of supersonic separator and multiphase sound speed. • Supersonic separator abates 98.65% of H 2 O from saturated-air at 10 °C & 3.165 bar. • 98.59% pressure-recovery of supersonic separator entails low exergy destruction. • Supersonic air purification has less exergy loss than traditional adsorption route. Air fractionation in cryogenic plants demands a Pre-Purification Unit for air compression and removal of water, carbon dioxide and trace-species. The conventional Pre-Purification Unit – FULL-TSA – adopts temperature-swing adsorption (TSA) with an activated-alumina bed for dehumidification followed by a molecular-sieve bed removing carbon dioxide and trace-species. A novel scheme – SS-TSA – prescribes a Supersonic Separator abating ≈98.5% of moisture followed by a small single-bed molecular-sieve removing remaining impurities. SS-TSA-HI is a SS-TSA variant allocating compression heat for molecular-sieve regeneration. This work compares thermodynamic performances of FULL-TSA, SS-TSA and SS-TSA-HI via exergy analyses and discloses better utilization of resources. Exergy analyses are supported by HYSYS simulator running with unit-operation extensions for calculating the phase-equilibrium sound speed and simulating the supersonic separator. Since exergy rates depend on Reference Environmental Reservoirs, two Reference formalisms are employed at 1 atm and 25 °C. Reference#1 prescribes air with 60% relative humidity (the raw air feed), while Reference#2 adopts water-saturated air. It is shown that Reference#1 is appropriate for overall system analysis, while Reference#2 is better for sub-systems analysis as it dramatically lowers cooling-water exergy flows. SS-TSA has 61% less exergy losses than FULL-TSA in the purification step as the supersonic separator accomplishes bulk dehumidification drastically reducing steam and nitrogen for bed regeneration. Reference#1 exergy efficiencies of FULL-TSA, SS-TSA and SS-TSA-HI attained 57.9% , 60.0% , and 60.3% , respectively. [ABSTRACT FROM AUTHOR]

Sustainability must be always assured in process design. Not rarely, multiple sustainability criteria point oppositely, entailing a need for more systematic and coherent assessments. The Sustainable Process Systems Engineering method is introduced as a two-level hierarchical evaluation of process designs. The first level selects the best design via four-dimensional indicators (environment, efficiency, health-&-safety, and economic), while in the second level, sustainability hotspots of the best design are pinpointed to unveil possible improvements. The method is applied for sustainability assessment of two ethylene oxide processes: the conventional and a novel route employing supersonic separator to prevent ethylene oxide losses using liquid-water injection. Supersonic separator route reduces oxide losses by 83.33 kg/h, representing +0.9% greater ethylene oxide production, 95% less ethylene oxide losses, entailing 2.5% higher net value for 20 operation years despite 0.11% higher investment, and consequently exhibiting the best environmental, technical, health-&-safety and economic performances. Photochemical-oxidation and aquatic-ecotoxicity are environmental indicators with highest improvement due to supersonic separator inclusion. Ethylene oxidation reactor, carbon dioxide stripping-column and cooling-water tower are the main unit-operations with sustainability hotspots. Image 1 • New ethylene oxide production route with loss prevention via supersonic separator. • Conventional and supersonic separator routes assessed in terms of sustainability. • Plant impacts on environment, efficiency, health-&-safety and economy were compared. • Supersonic separator increases annual revenue in 0.9% and net present value in 2.5%. • Main sustainability upgrades: environment (smog/aquatic-ecotoxicity) and economic. [ABSTRACT FROM AUTHOR]

Offshore oil/gas production with high %CO 2 and gas-to-oil ratio impose processing large volumes of CO 2 -rich gas. This requires first-of-a-kind designs and creates design uncertainties besides offshore operation uncertainties. Therefore, the design of offshore units under influence of stochastic factors is recommended to avoid oversized worst-case designs or underachieved specifications implying economic/environmental losses. This work presents a novel Computer-Aided Engineering tool, MCAnalysis , a VB.NET/XML interoperability framework between HYSYS and MATLAB to statistically assess design performance via Monte-Carlo analysis. Designs of offshore processing of CO 2 -rich gas via Conventional-Route and a novel Supersonic-Separator-Route were tested submitting stochastic populations of gas flow rate, %CO 2 and gas-to-oil ratio. Supersonic-Separator-Route presented higher resilience to input overshoots and less necessity of design changes to accomplish specifications in at least 75% of sampled cases compared to Conventional-Route. Supersonic-Separator-Route also showed 15% less average power consumption and hydrocarbons dew-point adjustment with lower %CO 2 in the condensate. Image 1 • Monte-Carlo analysis of offshore processing of CO 2 -rich natural gas is investigated. • Analysis of process alternatives: conventional-route and supersonic separator route. • Monte-Carlo analysis unveils design limitations and bottlenecks of alternatives. • Alternatives are re-designed and submitted to Monte-Carlo analysis for approval. • Supersonic separator route statistically confirmed with 15% less power consumption. [ABSTRACT FROM AUTHOR]