INFO

treating systems, the FeS particles form oleophilic encapsulated FeS particles which show a “filming” tendency on filter materials. As such, amine filters tend to plug quickly. The Refiner’s Problem Traditional string wound cartridges have a very limited dirt holding capacity, low efficiency and represent an increased risk of leakage due to inadequate mounting. All these op-erational characteristics result in short filtration (life)times, high operational costs, fouling of the system and off-spec sweetened gas. The subject refiner has been utilizing a traditional filter with 54 string wound cartridges. These re-quired to be exchanged every week, which is a labor intensive job and represented an increased risk on inadequate mounting of the elements. The low effi-ciency resulted in reduction of throughput, due to clogging and plugging of columns and heat ex-changers. This caused very frequent shut-downs, required cleaning of the system and reduction of reliability of the refinery. Dahlman’s Solution DAHLMAN was consulted and requested to analyze the process data and filtration performance. Based on decades of field experience in the filtration of amine solutions, it was obvious for DAHLMAN to propose the DAHLMAN T-Filter Technology as the most suitable solution. This tech-nology has been developed in close co-operation between DAHLMAN and a renowned International Oil &Gas Company over a decade ago. Oil & Gas Plants, Refineries and Petrochemicals have been using these filters for many years now successfully. Field Results Dahlman and the refiner mutually agreed to test on full scale. The full scale filter, which was delivered in 2010 to the refiner, has demonstrated that DAHLMAN’s T-Filter technology performs excellently in this application. It effectively captures the contaminant and as result of the de-sign with exceptionally large filtration area and high dirt holding capacity. It has reduced the mainte-nance costs (element consumption and labor costs) and contributes significantly to the reliability of the refinery. The figures in the below table provide a comparison of the total costs involved for the ini-tially installed traditional cartridge filter unit and he DAHLMAN Terraced Filter Technology.

Overview This is a case study on the largest refinery in the Middle-East which makes use of standard string wound filter elements for the filtration of amine as part of the refinery’s GTU (Gas Treating Unit). This refiner faced short cycle times of the filtration unit, a polluted amine loop and high maintenance costs (replacing elements and too fre-quent cleaning of the amine loop). DAHLMAN has performed an analysis of the currently installed fil-tration unit and as a result, proposed to test DAHLMAN’s Terraced Filter Technology (T-Filter). As DAHLMAN has gained a lot of field experience from the filtration systems that we have supplied for gas treatment plants all over the world, we were able to quickly and accurately identify the root cause of the problem. Based on the field results the refiner de-cided to nominate the DAHLMAN T-Filter Technolo-gy as the preferred filtration technology for all their amine systems. This case study focuses on the conventional approach (standard string wounded elements) and DAHLMAN’s approach in Amine filtration (DAHLMAN T-Filter Technology). Application Overview The treatment of (sour) gas by making use of amines, also known as gas sweetening, is a common process which uses aque-ous solutions of various alkyl and/or alkanol amines to remove hydrogen sulfide (H2S) and carbon dioxide (CO2) from gases. The process runs in a com-mon refinery unit named GTU (Gas Treating Unit), and is also used in petrochemical plants, natural gas processing plants and other industries. Processes within oil refineries or gas processing plants that remove hydrogen sulfide and/or mer-captans are commonly referred to as sweetening processes because they result in products which no longer have the sour, smelly odors of mercaptans and hydrogen sulfide. The construction material commonly used for pi-ping and process units is carbon steel. The sulfur components, present in the amine after being ab-sorbed, form Iron sulfide (H2S + Fe --> FeS + H2). This is an unavoidable process and it is this compound, which causes operational problems. In combination with injected anti-foaming agents into the gas

C A S E S T U D Y I M P R O V I N G A M I N E F I L T R A T I O N

INFO

DAHLMAN’s T-Filter Technology has provided a sound and satisfactory solution to the refiner by eliminating the problems encountered with the tra-ditional type of cartridge filters. The technology has proven to greatly surpass the traditional type, by combining highly efficient filtration and significant reduction of operation costs. The condition of the amine solution improves over time which contri-butes to the reliability and profit of the refinery.

Conclusion The formation of oleophilic encapsu-lated FeS particles are unavoidable in the gas treating process. When gas is sweetened, it is of top priority to keep the amine in excellent condition by filtering out impurities, as they influence the quality of the sweetened gas and reliability of the refinery. The traditional string wound filter elements are not efficient enough and the possibility of by-passing due to inadequate mounting results in high opera-tional costs.

W W W . D A H L M A N . N L | T . + 3 1 ( 0 ) 1 0 5 9 9 1 1 1 1 | E . D A H L M A N @ D A H L M A N . N L V O L U M E 2 , N O . 1 – F E B R U A R Y 2 0 1 2

Parameters Traditional string wound cartridge

Dahlman Terraced Filter Technology

Annual Savings

No. of elements per vessel 54 3

No. of change-outs per year 52 4

Total cost elements per year $ 75,816 $ 12,000 $ 63,816

Total cost on man-hours per year $ 7,800 $ 360 $ 7,440

Total cost gaskets per year $ 15,600 $ 1,200 $ 14,400

Total cost water and additives $ 43,424 $ 21,458 $ 21,966

Total annual savings $ 107,622

Supportive Tools DAHLMAN has a variety of test filters available for on-site testing. Sample analyses can be performed for sup-portive filter design. Computer software has been developed to predict amine filtration behavior and to calculate filtration cycle times before the maximum delta-P is achieved. Also for applications other than gas treating, DAHLMAN’s pilot testing units can be used to obtain the required design parameters. Related Documents Dahlman INFO Amine Filtration, Dahlman Technical Information Paper DAHLMAN Terraced Filters in Amine appli-cations, Dahlman Reference List Terraced Filters.