국민대학교 수소 및 연료전지 시스템 연구

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화연 어
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1 신동훈국민대학교기계공학과

2 개질기성능해석 CFD Modeling 에너지시스템설계 Excel-Visual Basic / Cycle-Tempo Open-Modelica RAI 연소기술 Flameless Combustion

3 한전전력연구원, 005 년도 5kW 급 MCFC용평판형개질기해석모델 100kW 급 MCFC용원통형개질기해석모델 100kW 급 MCFC용촉매연소기설계개선 한국가스공사, 009 년도 5kW 급원통형개질기설계개선

4 주요반응 CH 4 + H O CO + 3H (1) CH 4 + H O CO + 4H () CO + H O CO + H (3) 반응속도식 / / / H O H O H CH CH H H CO CO CO H O H CO H CO H O H CH H CO H O H CH H P P K P K P K P K DEN DEN K P P P P P k r DEN K K P P P P P k r DEN K P P P P P k r

5 속도상수 k exp 8879 T kmol kg kpa h 0.5 k exp 9336 T kmol kg kpa h 0.5 k exp 8074 T.3 kmol kg kpa h 1 흡착평형상수 K CH exp 4604 T.8 [ kpa 1 ] K H O exp 1066 T.35 [ kpa 1 ] K H exp 9971 T.13 [ kpa 1 ] K CO exp 8497 T.71 [ kpa 1 ]

평형상수 K 1 1066.76 exp 6830 T 30.11 [ kpa ] K exp 4400 T 4.

6 평형상수 K exp 6830 T [ kpa ] K exp 4400 T [ ] 최종균, 정태용, 남진현, 신동훈, 수증기 - 메탄개질반응해석모델의비교연구, 대한기계학회논문집 B, 3:497~503, 008 J. Xu, G.F.Froment, Methane steam reforming, methanation and water gas shift. I. Intrinsic kinetics, AIChE J. 35 (1989)

7 반응 반응식 Activation Energy (E) Pre-exponential factor (A) CH 4 +H O3H +CO.4e+8 7e+17 STR CH 4 +H O4H +CO.439e+8 1.5e+16 CO+H O H +CO 6.413e HTS CO+H O H +CO 5.574e e+7 LTS CO+H O H +CO 5.574e+7 1.5e+8

9 속도벡터 온도분포 (K)

10 CH 4 몰분율 CO 몰분율 H 몰분율

11 온도 (K) CFD 측정값1 측정값 높이 (m) 개질공간온도분포측정값과전산해석결과의비교 연소공간온도분포측정값과전산해석결과의비교 전산해석에의한연소공간과개질공간중심에서의온도분포 (w1: 개질공간, comb_line: 연소공간 )

13 개질공간원형면유동형태해석 유속 : 174 m/s, 온도 : 1000 K

14 속도벡터계산결과 ( 보기속도영역 : 0~3m/s) 유선도계산결과 Y-velocity 등고선결과 반응공간하단면에서의 Y-velocity 분포

15 분산관형상 그림 5) 5 kw 급평판형개질기개질부분산관 분산관유동해석을위한계산격자 분산관내유선도 분산관내속도등고선

예연소가열식평판형개질기형상및격자시스템 항목 사양 개질실단위 chamber 18 chambers 로구성 Dimension 670 1675 13.5 mm (5t 분리판포함 ) 개질원료 CH 4 +H O 연소실단위 chamber 19 chambers 로구성 Dimension 670 1675 13.

16 예연소가열식평판형개질기형상및격자시스템 항목 사양 개질실단위 chamber 18 chambers 로구성 Dimension mm (5t 분리판포함 ) 개질원료 CH 4 +H O 연소실단위 chamber 19 chambers 로구성 Dimension mm (5t 분리판포함 ) 연소방식 예연소주입방식 원료와연료 flow pattern counter current 연소실 개질실 Case 1 Case Case 3 연소가스유량 (Nm 3 /hr) 연소가스온도 (K) 연소가스압력 (atm) CH 4 유량 (Nm 3 /hr) H O 유량 (Nm 3 /hr) 온도 (K) 압력 (atm)

17 Case 1 Case 3 온도분포 온도분포 ( 연소가스유량이.4 배인경우 ) 메탄몰분율분포메탄몰분율분포도 ( 연소가스유량이.4 배인경우 ) CO 몰분율분포 CO 몰분율분포도 ( 연소가스유량이.4 배인경우 ) H 몰분율분포 H 몰분율분포도 ( 연소가스유량이.4 배인경우 )

연소실 - 연료공급부 CH 4 : 0 Nm 3 /hr, 300 K, 1atm - 공기공급부 Air: 34 Nm 3 /hr, 300 K, 1atm 개질관열흡수총흡열량 : 5636 kcal/hr = 65405 W

18 연소실 - 연료공급부 CH 4 : 0 Nm 3 /hr, 300 K, 1atm - 공기공급부 Air: 34 Nm 3 /hr, 300 K, 1atm 개질관열흡수총흡열량 : 5636 kcal/hr = W 전열면적 : m 면적당흡열량 : 7310 W/m ( 균일한흡열로가정 ) 100 kw 급 NG 개질기형상및전산해석을위한격자시스템 벽면열손실 ( 가정 ) 외벽면온도 77 내화재두께 00mm 열전도도 1 w/m K

19 100kW 급개질기연소공간내속도벡터 (m/s) 100kW 급개질기연소공간내유선및온도분포 (K)

20 100kW 급개질기연소공간내온도분포 (K) 100kW 급개질기개질관및벽면온도분포 (K)

21 100kW 급개질기 NG 버너근처의메탄농도분포 100kW 급개질기 NG 버너근처의 CO 농도분포 100kW 급개질기연소공간내산소분포

100 kw 급 NG 개질기개질기관형상 100 kw 급 NG 개질기개질기관내부속도벡터도 (m/s, 굵기를 5 배확대해서본것임 ) 100 kw 급 NG 개질기개질기관내부온도분포도 (K, 굵기를 5 배확대해서본것임 ) 유입관내경 개수 총단면적 CH4 HO 총유량 유입온도 가스유속 0.017 m 16 개 0.

22 100 kw 급 NG 개질기개질기관형상 100 kw 급 NG 개질기개질기관내부속도벡터도 (m/s, 굵기를 5 배확대해서본것임 ) 100 kw 급 NG 개질기개질기관내부온도분포도 (K, 굵기를 5 배확대해서본것임 ) 유입관내경 개수 총단면적 CH4 HO 총유량 유입온도 가스유속 m 16 개 m 6.07 Nm3/hr 78.4 Nm3/hr Nm3/hr 300 oc 573 K m/s CH4 질량비율 HO 질량비율 외벽면복사열전달연소실버너화염온도 : 1400 K, 연소실외벽면온도 : 100 K 외관두께 6mm의 steel 으로가정

23 100 kw 급 NG 개질기개질기관내부메탄몰분율 (K, 굵기를 5 배확대해서본것임 ) 100 kw 급 NG 개질기개질기관내부 CO 몰분율 (K, 굵기를 5 배확대해서본것임 ) 100 kw 급 NG 개질기개질기관내부 H 몰분율 (K, 굵기를 5 배확대해서본것임 )

24 Jul 13, 009 FLUENT 6. (axi, segregated, spe, rngke) 촉매의부피고정 STR 촉매 :.00 liter HTS 촉매 : 1.65 liter LTS 촉매 : 1.65 liter tip 크기에따른변화 35, 40, 45 mm 촉매공간의 H/D 에따른변화 -0%, -10%, 0%( 도면 ), +10%, +0% 촉매부피유지하도록직경은수정 냉각관의형상은격자의용이성을위해단순화

25 m/s

$fraction$ (tip40,

26 결과 - Mole fraction (tip40, H/D 0%) CH 4 H CO H O CO

27 35mm 40mm 45mm

28 35mm 40mm 45mm

29 H/D 변화율에따른해석 -0% -10% 0% +10% +0%

30 H/D 증가율에따른 H mol-fraction(wet) 70% 65% 6.15% 6.75% 63.38% 65.40% 60% 55% 50% 50.97% -0% -10% 0% 10% 0%

31 H/D 증가율에따른메탄전환율 100% 90% 91.18% 94.68% 94.75% 99.9% 80% 70% 69.95% 60% -0% -10% 0% 10% 0%

32 1kW 결과대비 5kW 는개질기출구 CO 농도가다소높은것으로예상됨. Tip 의크기에따라연소공간내유동흐름에변화가있으나효율에큰차이는없는것으로사료됨. Tip 의크기 45mm 가개질공간주변연소가스공간에서고른하강형태를보였으며효율이가장좋은것으로나타남. 개질기길이 (H/D) 가늘어날수록열전달율이높아져메탄의전환율및수소생산량이높아짐. 개질기길이는설계치보다 10~0% 늘어난값이적정한것으로판단됨. H/D 와 CO 잔량의상관관계는비교적적은것으로판단됨.

33 연소공간설계 연소실열부하 ( 체적당발열에너지 ) 기본설계 연소가스체류시간 ( 버너의형식과관련 ) 전산유체역학 벽면열손실 기본설계 개질공간설계 개질기면적당열전달율 기본설계 물질의흐름방향과열교환형식 전산유체역학

35 Excel-VB를이용한기본설계 공정해석을통한공정최적화 Cycle-Tempo CFD 해석을이용한요소별상세설계 Solidworks simulation/ansys Fluent 동특성해석을통한운전최적화 Modelica/Open-Modelica

Flameless combustion Flameless Oxidation(FLOX TM ) High Temperature Air Combustion (HiTAC) MILD combustion a technology capable of accomplishing high efficiency and low emissions

42 Flameless combustion Flameless Oxidation(FLOX TM ) High Temperature Air Combustion (HiTAC) MILD combustion a technology capable of accomplishing high efficiency and low emissions without flame instability phenomena. uses delayed mixing of fuel and oxidizer combined with high level of dilution by flue gas in the main reaction zone. Flame mode Flameless mode 4

Queted in Recirculation of combustion products at high temperature (> 1000 C) Reduced oxygen concentration at the reactants Distributed combustion

43 Queted in Recirculation of combustion products at high temperature (> 1000 C) Reduced oxygen concentration at the reactants Distributed combustion zone Uniform temperature distribution Reduced temperature peaks Low adiabatic flame temperature High concentration of CO & H O Low NOx and CO emission 43

Conventional Combustor High Peak Temperature Thin reaction zone

(Flameless combustor) Low temperature peak Distributed flame

Levy, Low NOx Flameless Combustion for Jet Engines and Gas

44 Conventional Combustor High Peak Temperature Thin reaction zone High Temperature Gradients High NOx production Low NOx Combustor (Flameless combustor) Low temperature peak Distributed flame Temperature Uniformity Low NOx production Queted in Yeshayahou Levy, Low NOx Flameless Combustion for Jet Engines and Gas turbines, 9 th Israeli Symposium on Jet Engines and Gas Turbines, October 7 010, 44

Flameless combustion furnace in TU Delft, Netherlands Study the configuration effects of multi-pair regenerative burners Develop the CFD model D. Shin et.al.

45 Flameless combustion furnace in TU Delft, Netherlands Study the configuration effects of multi-pair regenerative burners Develop the CFD model D. Shin et.al., Configuration effects of natural gas fired multi-pair regenerative burners in a flameless oxidation furnace on efficiency and emissions, Applied Energy,

and cycle times Result of computational fluid dynamic simulation temperature contour (K)

46 Multi-burner installation map for the definition of configurations and operating modes. Trends of furnace temperature as a function of exhaust gas O (%) for all configurations and cycle times Result of computational fluid dynamic simulation temperature contour (K) Trends of CO emission as a function of exhaust gas O (%) for all configurations and cycle 46times

Specific burner of heat regeneration with a

47 Advantages of Flameless comb. Low temperature peak Distributed flame Temperature uniformity Low NOx production FLOX TM burner with honeycomb Previous flameless combustion facilities Specific burner of heat regeneration with a honeycomb Heat exchanger for preheating air or fuel Recirculation ducts / gas 47

48 Simple flameless combustion No preheating air/fuel No specific burner No recirculation duct But, have flameless combustion characteristics Find a possibility of simple flameless combustion 48

49 Air Air flow counter for fuel Air is heated by exhaust gas Fuel and air are diluted by exhaust gas Mixing of fuel and air is delayed by dilution Fuel 49

(99.95%), 11.6 lpm Stoichiometry ratio: 1.15 Fuel and air temp.: ambient temp.

50 Furnace is 0.7 m high The inner diameter is 0. m Several air inlet ports(id 4.mm) to various conditions and configurations Only ports used in this study Fuel: CH 4 (99.95%), 11.6 lpm Stoichiometry ratio: 1.15 Fuel and air temp.: ambient temp. Air supply by compressor Fuel: bottom of furnace Air Bottom (flame mode) top nozzle (flameless mode) 50

51 0.5 m T/ C T/ C T/ C T/ C T/ C Flame mode Flameless mode Temperature distribution(as same range) Temp. uniformity of the flameless mode is an increase of dramatic Peak temp. of flameless mode is a decrease Fuel 51

52 flame flameless Unit CO 7 14 ppm Flame mode Flameless mode NO ppm T_max T_min T_avg o C o C o C T_stde o C NO emission: decreased Various Temp.: decreased CO: slightly increased The contour of temperature as independent ranges 5

53 Exhaust gas Air inlet Turbulent: standard k-ε Reaction: 16 species EDC Radiation: DO model Grid: about 110,000 cells A quarter of the size Fuel 53

54 Flame mode Temp. CH4 CH3 OH Flameless mode Low temperature peak Distributed flame Temperature Uniformity Distributed combustion zone 54

55 개질기가열연소실버너로활용 강한난류에의한높은열전달율및장치크기감소 균일한온도분포에의한국부가열감소및내구성향상

56 무화염연소기술을적용한고효율컴팩트개질기개발 CFD 해석및구조해석을통한최적설계 수소스테이션공정해석및설계최적화 Excel-VB 및 Cycle-Tempo 를활용한공정해석및설계개발 에너지효율극대화를위한최적화 이용한수소스테이션운전동특성예측및성능최적화 Modelica/Open-Modelica 를이용한동적모델개발 시스템안정성및안전도향상

DBPIA-NURIMEDIA

DBPIA-NURIMEDIA 수증기-메탄개질반응해석모델의비교연구 최종균 정태용 신동훈 남진현 김영규 * A comparative study for steam-methane reforming reaction analysis model Chong-gun Choi, Tae-yong Jung, Dong-hoon Shin, Jin-hyn Nam and Yong-gyu Kim Key Words: