78JULY 2015 | HydrocarbonProcessing.com
Gas Treating
rinse water fractions. The recovery efficiency associated with a water injection rate of 1.5 gpm is higher compared to the 1-gpm water injection rate. This is expected, as it is generally observed that recovery increases at higher water injection rates. The inlet amine carryover was higher from the first sampling to the second by nearly 60%. This could be part of the normal fluctuation of the process, but the higher water injection rate caused a higher percent of amine recovery (by 9%) with a simi- lar residual amine concentration in the LPG effluent.
At a 1.5-gpm water injection rate, the amine recovery was calculated to be at 88.2%. The expected solubility of amine into the LPG is between 90 ppm to 150 ppm. The recovery system is able to remove the amine concentration below solu- ble levels. TABLE 6 highlights what it means in terms of amine
recovery under normal operation at a 1.5-gpm water injection rate. The following table is based on an LPG flow of 2,000 bpd and an LPG density of 0.52 kg/l.
TABLE 6 shows that a significant amount of amine is being
recovered daily by the amine recovery system (89%). The re- covery amount is the difference between the amine recovery system inlet and outlet. This equates to 57.6 lb/day of amine recovered. The recovered amine can be, in principle, added back to the amine unit, minimizing losses.
Options. The first phase of the evaluation determined the treatment capacity of the LPG amine contactor for a higher flow up to 2,000 bpd. The treater was simulated.2 It was concluded
that the treater was able to reduce the H2S content below the
10 ppm specification. The combination of the detrimental im- pacts on the caustic treater and higher amine-treater flowrates required use of an amine recovery system. The advanced amine recovery system was installed in the treat LPG stream, at the outlet of the amine unit.1, 3 The system was selected for its high
amine recovery efficiency and effective phase separation, in ad- dition to a small equipment envelope and low cost.
Comprehensive performance testing of the system was conducted using equipment designed specifically for LPG sampling and amine extraction. The sampling technique and
analysis of amine extracted from the LPG yielded accurate quantification of both amine losses and amine recovery using the advanced amine recovery system.3 The test data showed
that the recovery system was able to remove the MDEA amine solvent in the treated LPG to below soluble limits. After the advanced amine recovery system was installed and operated at 1.5-gpm injected water rate, the amine recovery efficiency was nearly 89%.3 This translated to a savings of about $120,000/
yr only in amine solvent. However, not only was the MDEA amine recovered, but the various impacts downstream at the caustic treating unit and other units were greatly reduced.1
An evaluation of the amine system equipment design and of the operation of that equipment in comparison to design guide- lines and best practices was also conducted. It was recommend- ed to change the packing rings and upgrade the inlet LPG dis- tributor in addition to adjusting the lean amine temperature.
NOTES
1 The THIOLEX process licensed by Merichem uses the FIBER FILM Contactor
as the mass-transfer device and caustic as the treating reagent to remove acid gas and mercaptan compounds from liquid and gas hydrocarbon streams.
2 ProTreat is a licensed simulation software.
3 The Exion system for amine recovery was designed to recover carried-over amine
and to extract residual dissolved amine in LPG streams; the process is licensed by Nexo Solutions.
4 A Dionex IonPac column.
DAVID ENGEL, managing director of Nexo Solutions, has more than 20 years of industrial experience in a variety of areas, including chemical synthesis, corrosion-resistant materials, sensors, light-to-energy conversion, membranes,
nanotechnology, separation technologies, analytical methods and chemical additives. Dr. Engel holds 17 US patents covering a wide array of engineering inventions, and is the author of several technical and scientific papers. He has developed business and technology for Eastman Kodak, Eli Lilly, Pentair, General Electric and Sulphur Experts. Dr. Engel has specialized in advanced process systems and multicomponent separation methods for removing or mitigating contaminants in process streams. He is the co-founder of Filtration Experts, a division of Sulphur Experts, and managing director of Nexo Solutions. Dr. Engel holds a BS degree in industrial chemistry and a PhD in organic chemistry, and is Six-Sigma certified. He is member of the American Chemical Society and the Gas Processors Association. He also serves as the president of the American Filtration & Separation Society (Southwest Region), a member of GLC Consulting, an editorial board member for Elsevier, and a member of the board for Genesis BioHealth Co. and Amine Filtration Co.
HEATH BURNS has over 14 years of experience in the oil, gas and process industries with regard to filtration and separation technology. He has a well-rounded background in
manufacturing, R&D, pilot testing, engineering design and business development. Mr. Burns has extensive field experience in solid/liquid, liquid/liquid and gas/liquid separations. He has worked extensively with chemical process plants and natural gas facilities, troubleshooting fouling issues and determining the best technology for mitigation of contaminants. Mr. Burns holds a BS degree in mechanical engineering technology from Texas A&M University.
BEN SPOONER, a 1998 graduate of the University of Alberta’s petroleum engineering program, has spent his entire career as a process engineer, focusing almost entirely on amine and sour water systems. He has been working for Sulphur Experts since 2003 and has been heavily involved with the troubleshooting, designing, testing and starting up of amine systems in over 25 countries around the globe. Mr. Spooner is also a principal member of the Amine Experts Seminar presentation team, co-author of Amine Treating and has authored several papers dealing with amine treating and sour water stripper optimization. Prior to joining Amine Experts, he worked as a roughneck on drilling rigs, an operator at a gas processing plant in northern Alberta, and as an engineer in the technical services department of a large amine vendor.
TABLE 5. MDEA concentration in the LPG stream at the inlet and outlet of the advanced amine recovery system3
Sample 1-gpm injection rate 1.5-gpm injection rate
Inlet LPG amine concentration, ppmm 110.3 179.2 Outlet LPG amine concentration, ppmm 20.6 21.1 Amine-recovery system effi ciency, % 81.3 88.2
TABLE 6. Amine recovery at 2,000 bpd of LPG and 1.5-gpm water injection rates
Parameter Amine-recovery system inlet
Amine-recovery system outlet
LPG fl ow, gpm 58.3 58.3
LPG mass fl ow, lb/min 253.0 253.0
Amine concentration, ppmm 179.2 21.1
Hydrocarbon Processing | JULY 201579
Management
B. GLASSCOCK, Solomon Associates, Dallas, Texas