How OLI Has Been Used to Tackle the Nasty Problem of Refinery Sour Water DART Steve Grise, Joe Flowers, Carlos Cavalca, Steve Meyer, Zeru Tekie, Mateus Panosso and Steve Puricelli - DuPont October 16/17, 2012
Agenda Brief introduction to DuPont and Clean Technologies DART TM Technology Drivers sustainability, economics and environment DART concept Key advantages of the process Process description Simulation results Sour Water What s in Sour Water? Determining DART feed 2
DuPont is applying our science to find solutions to some really BIG challenges FEEDING THE WORLD REDUCING OUR DEPENDENCE ON FOSSIL FUELS KEEPING PEOPLE AND THE ENVIRONMENT SAFE WE ARE A MARKET-DRIVEN SCIENCE COMPANY National Geographic images 3
DuPont Clean Technologies A global leader in integrated Clean Air and Clean Fuel sustainability solutions through best-in-class technologies, equipment and service offerings to improve productivity, reduce air emissions and produce cleaner fuels Alkylation Hydroprocessing Global Engineered Solutions Air Pollution Control Sulfuric Acid Technology STRATCO IsoTherming GES BELCO Technology and proprietary equipment for refiners to produce clean alkylate for blending into gasoline Technology and proprietary equipment for refiners to hydrotreat middle petroleum distillates to reduce sulfur content and for the production of renewable fuels Comprehensive products and technical services for sulfur management, sulfuric acid alkylation units and sulfuric acid plants Dynawave Technology and proprietary equipment for scrubbing emissions of SOx, NOx and particulates Technology, proprietary equipment, and catalysts for sulfur management, sulfuric acid production, and spent acid regeneration 4
Crude Demand and Nitrogen Content Trends World Crude Demand and Quality 2000 to 2020 100.0 Other 90.0 High TAN 10000 80.0 Heavy Sour Light Sour 1000 Production (MBPD) 70.0 60.0 50.0 40.0 Light sweet N content / ppm 100 10 1 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 30.0 crude API 20.0 10.0 0.0 2000 2005 2010 2015 2020 Source EIA Long Term Outlook, OPEC World Oil Outlook 2009
Problem Description Increasing Sour Water Stripper (SWS) off-gas production Roughly 1/1/1 molar ratio NH 3 /H 2 S/H 2 O Gas contains some additional hydrocarbons Sulfur has value Solutions? H 2 S sent to Claus to be converted to Sulfur NH 3 is problematic in Claus (salt formation and loss of capacity) Separate NH 3 from H 2 S Chevron WWT Haldor Topsoe ATS Other? Optimize Claus operation with NH 3 present Can we recover the N value in the ammonia? With H 3 PO 4? With H 2 SO 4? 6
Partial Pressure of NH 3 versus NH 3 /H 3 PO 4 Ratio 7
Partial Pressure of NH 3 versus NH 3 /H 2 SO 4 Ratio 8
Developed OLI model Basic OLI Model (ESP) Major components H 2 O, H 2 S, NH 3, H 2 SO 4 Minor components CO 2, Hydrocarbons Methyl- and Ethyl- Mercaptan Standard sets of equilibrium reactions Used ESP to develop concept and Patent Straight forward task with OLI Assume a standard SWS off-gas feed 1/1/1 molar ratio NH 3 /H 2 S/H 2 O @ about 185 o F 9
Feed acid to control ph; Water to maintain balance Technology Description Includes cooler to remove DHrxn Neutralize Scrubber to remove NH 3 Stripper to remove H 2 S 10
Preliminary Design Case Processing 30 TPD SWS ammonia yielding 284 STPD ammonium sulfate liquor product (41% w/w) nominally 42.5M tons per year 100% basis, 104M tons per year Commodity basis Ammonium Sulfate product specification (modeling results). Final Product H 2 O 59.0 wt% (NH 4 ) 2 SO 4 41.0 wt% ph 7.0 pp(h 2 S) 0.00004 ppm pp(nh 3 ) 326.1 ppm pp(mmcptn) 0.002 ppm pp(emcptn) 0.00004 ppm f.p. 1.5 deg C NH 3 /SO 4 2.00 11
Ammonium Sulfate Solubility Ammonium Sulfate Solubility in Water 80 70 60 (NH4)2SO4 (wt %) 50 40 30 Proposed final product 20 10 0 Commy nullamcor ilis exeros alit dolobor percipsummy nonsed min henibh ex exeros nullaore Temperature molesto. (C) -40-20 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 12
Lab Validation Experiment 1 Lab scale stripping of synthetic stripper feed Synthetic scrubber effluent Strip batch-wise Validated model ability to predict stripping 13
Potential Technology Benefits Sour Water Stripper (SWS) gas recovery of NH 3 species Increased Claus SRU capacity and minimization of Claus process downstream problems Up to 3.75 tons additional sulfur processing capacity gain per ton of NH 3 removed. Catalyst and equipment fouling with ammonium sulfate salt deposits minimized Reduced water feed to Claus; Total volumetric reduction in Claus feed by ~50% Elimination of SWS NH 3 separation costs Elimination of NH 3 incineration (incinerator OPEX, NO x & SO 2 emissions associated with ammonia incineration) Production of Ammonium Sulfate Liquor Feedstock for Fertilizer or Blending Product. Refinery downstream integration (e.g. agrochemicals) converting a waste product into a commodity chemical Production of N-containing fertilizer mostly uncoupled from natural gas cost (e.g., versus urea production) Helps enabling expansion of markets for high N-crudes when coupled with DART technology. Sustainable solution conversion of N-waste into N-fertilizer providing environmental and operational benefits 14
DART - NH 3 SWS Gas Scrubbing - Ammonium Sulfate Production On-Site Facility Refinery DART NH 3 -Scrubbing Ammonium Sulfate Plant SWS gas (H 2 S, NH 3, H 2 O) Fresh + Waste Acid Scrubbed SWS gas to SRUs (H 2 S, H 2 O) Ammonium Sulfate Liquor (or solids) to Merchant Market 15
What is the DART feed composition? A standard SWS off-gas is 1/1/1 molar ratio NH 3 /H 2 S/H 2 O, plus CO 2 and hydrocarbons, but WHICH hydrocarbons? Hydrocarbons depend on refinery operations (hydrotreater, cracker, coker, etc ) What is the analysis of the SWS? Refineries don t really care Hazardous (deadly) gas stream How do we determine our feed composition so that we can design our DART plant? 16
Sour Water Strippers (primer) There are generally two types: Single column Two column (Chevron WWT) Proprietary part of refinery Costly to operate and maintain High energy consumer Corrosion issues Don t publish knowledge We need to simulate the SWS designs -- OLI 17
What is the feed to the SWS? Class of compound Expected compounds? Sour Water systems have been described as garbage disposals or toilets of refineries. Armstrong et al, Today s Refinery, June 1996. Any or all of these classes of compounds could be present. Worked with partner to characterize their SW. Alkyls Alcohols Ethers/Epoxides Carboxylic acids Aldehydes/Ketones Phenols Aromatics Polynuclear Aromatics Sulfides Amines (exc NH3) "C" Compounds C3 - C8? Branched isomers Anything one might find in gasoline! Unlikely Unlikely Unlikely Methyl Ethyl Ketone (somewhat surprizing) Phenol Cresol Benzene Toluene Xylene Ethyl Benzene Naphthalene Decalin Anthracene "S" Compounds Methyl Mercaptan Ethyl Mercaptan "N" Compounds Organic amines Nitriles HCN Acetonitrile Propionitrile 18
Beefing up the OLI database! Many of the compounds we found in the SW sample were not in the OLI database. Used data from Dortmund Database to calculate K(T) Built database of remaining compounds 19
Simulations of SWS s Required to simulate performance and off-gas composition from both single column and two-column systems. Worked with partners to match simulation versus readily measureable variables (T, P, flow, duty) Off-gas composition not available! Results agreed very well for both systems. Assume the off-gas composition was close enough for MECS to prepare design and basic engineering package for DART pilot. 20
Summary Utilized the power of the OLI software to Develop DART process concept and Patent Validate versus lab experiment Build a database to include the myriad of hydrocarbons Develop simulations for single column and two column sour water strippers Design pilot facility Success will be defined by the operation of the pilot Looking forward to sharing the successful operating data at the 2014 OLI Simulation Conference! 21
Thank You!!