Issue
Korean Chemical Engineering Research,
Vol.52, No.6, 814-820, 2014
토크 측정과 시차주사열량계를 이용한 수용성 고분자 화합물의 하이드레이트 저해 성능 평가
Evaluation of Hydrate Inhibition Performance of Water-soluble Polymers using Torque Measurement and Differential Scanning Calorimeter
본 연구에서는 토크 측정과 고압 시차주사 열량계를 이용하여 pyrrolidone, caprolactam, acrylamide 계열 수용성 고분자들의 하이드레이트 저해 성능을 평가하였다. 실험 결과, 세 종류의 고분자가 모두 동역학적인 하이드레이트 생성억제제 효과를 나타내는 것으로 확인되었으며, 특히 0.5 wt% polyvinylcaprolactam (PVCap)의 경우 34.4분의 하이드레이트 유도 시간, 15.9 K의 subcooling 성능을 보이며 12.3 분, 6.0 K의 순수 물 시스템보다 월등한 저해 성능을 나타내었다. 0.5 wt% polyvinylpyrrolidone (PVP)의 경우 중간 정도의 저해 성능을 보였으며, polyacrylamide-co-acrylic acid partial sodium salt (PAM-co-AA)의 경우 각각 0.5 wt%와 5.0 wt%의 농도에서 미미한 하이드레이트 저해 성능을 보였다. 반면에 생성된 하이드레이트 입자의 성장속도와 생성 양에서는 PAM-co-AA가 PVCap과 더불어 가장 월등한 저해 효과를 나타내었다. 또 다른 주요 성능 평가 요소 중 하나인 토크 변화의 경우에는 PVCap이 평균 토크 6.4 N cm로 가장 좋은 성능을 보였으며, 0.5 wt%의 PAM-co-AA 시스템이 평균 7.2 N cm의 값으로 그 뒤를 이었다. 고압 시차주사 열량계를 이용한 수용성 고분자 물질의 저해 성능 평가 실험의 결과는 autoclave 실험의 결과와 유사하였다. PVCap을 첨가한 경우 하이드레이트가 생성되기까지의 유도시간이 가장 길어서 저해성능이 뛰어난 것을 확인하였다.
In this work, hydrate inhibition performance of water-soluble polymers including pyrrolidone, caprolactam, acrylamide types were evaluated using torque measurement and high pressure differential scanning calorimeter (HP μ-DSC). The obtained experimental results suggest that the studied polymers represent the kinetic hydrate inhibition (KHI) performance. 0.5 wt% polyvinylcaprolactam (PVCap) solution shows the hydrate onset time of 34.4 min and subcooling temperature of 15.9 K, which is better KHI performance than that of pure water - hydrate onset time of 12.3 min and subcooling temperature of 6.0 K. 0.5 wt% polyvinylpyrrolidone (PVP) solution shows the hydrate onset time of 27.6 min and the subcooling temperature of 13.2 K while polyacrylamide-co-acrylic acid partial sodium salt (PAM-co-AA) solution shows less KHI performance than PVP solution at both 0.5 and 5.0 wt%. However, PAM-co-AA solution shows slow growth rate and low hydrate amount than PVCap. In addition to hydrate onset and growth condition, torque change with time was investigated as one of KHI evaluation methods. 0.5 wt% PVCap solution shows the lowest average torque of 6.4 N cm and 0.5 wt% PAM-co-AA solution shows the average torque of 7.2 N cm. For 0.5 wt% PVP solution, it increases 11.5 N cm and 5.0 wt% PAM-co-AA solution shows the maximum average torque of 13.4 N cm, which is similar to the average torque of pure water, 15.2 N cm. Judging from the experimental results obtained by both an autoclave and a HP μ-DSC, the PVCap solution shows the best performance among the KHIs in terms of delaying hydrate nucleation. From these results, it can be concluded that the torque change with time is useful to identify the flow ability of tested solution, and the further research on the inhibition of hydrate formation can be approached in various aspects using a HP μ-DSC.
[References]
  1. Sloan ED, Koh CA, Clathrate Hydrates of Natural Gases. 3rd ed.; CRC Press, Taylor & Francis Group: Boca Raton, FL, 2008
  2. Seo YT, Lee H, Korean J. Chem. Eng., 20(6), 1085, 2003
  3. Lee H, Seo Y, Seo YT, Moudrakovski IL, Ripmeester JA, Angew. Chem. Int. Ed., 42, 5048, 2003
  4. Sloan ED, Koh CA, Sum AK, Natural Gas Hydrates in Flow Assurance, Elsevier, Amsterdam, 2010
  5. Brustad S, Loken KP, Waalmann JG, “Hydrate Prevention using MEG Instead of MeOH: Impact of Experience from Major Norwegian Developments on Technology Selection for Injection and Recovery of MEG,” In Offshore Technology Conference, Houston, Texas, USA, May 2-5, 2005
  6. Cha M, Shin K, Kim J, Chang D, Seo Y, Lee H, Kang SP, Chem. Eng. Sci., 99, 184, 2013
  7. Joshi SV, Grasso GA, Lafond PG, Rao I, Webb E, Zerpa LE, Sloan ED, Koh CA, Sum AK, Chem. Eng. Sci., 97, 198, 2013
  8. Kelland MA, Energy Fuels, 20(3), 825, 2006
  9. Townson I, Walker VK, Ripmeester JA, Englezos P, Energy Fuels, 26(12), 7170, 2012
  10. Del Villano L, Kommedal R, Kelland MA, Energy Fuels, 22(5), 3143, 2008
  11. Kvamme B, Kuznetsova T, Aasoldsen K, J. Mol. Graph. Model, 23, 524, 2005
  12. Anderson BJ, Tester JW, Borghi GP, Trout BL, J. Am. Chem. Soc., 127(50), 17852, 2005
  13. Moore JA, “Understanding Kinetic Hydrate Inhibitor and Corrosion Inhibitor Interactions,” In Proceeding of the Offshore Technology Conference. Houston, TX, USA, May 4-7, 2009
  14. Daraboina N, Linga P, Chem. Eng. Sci., 93, 387, 2013
  15. Yang JH, Tohidi B, Chem. Eng. Sci., 66(3), 278, 2011
  16. Anderson R, Mozaffar H, Tohidi B, “Development of a Crystal Growth Inhibition Based Method for the Evaluation of Kinetic Hydrate Inhibitors,” In Proceedings of the 7th International Conference on Gas Hydrates, Edinburgh,Scotland, U.K., July 17-21, 2011
  17. Lee S, Park S, Lee Y, Kim Y, Lee JD, Lee J, Seo Y, Korean Chem. Eng. Res., 50(4), 666, 2012
  18. Lee S, Lee Y, Lee J, Lee H, Seo Y, Environ. Sci. Technol., 47, 13184, 2013
  19. Lee Y, Lee S, Lee J, Seo Y, Chem. Eng. J., 246, 20, 2014
  20. Daraboina N, Linga P, Ripmeester J, Walker VK, Englezos P, Energy Fuels, 25(10), 4384, 2011
  21. Ke W, Svartaas TM, Abay HK “An Experimental Study on sI Hydrate Formation in Presence of Methanol, PVP and PVCap in An Isochoric Cell,” In Proceedings of the 7th International Conference on Gas Hydrates, Edinburgh, Scotland, U.K., July 17-21, 2011
  22. Cha M, Shin K, Seo Y, Shin JY, Kang SP, J. Phys. Chem. A, 117(51), 13988, 2013