Introduction of RTO

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1 觸媒 / 蓄熱式焚化技術 (CTO/RTO) 介紹張豐堂 Feng Tang Chang 傑智環境科技股份有限公司總經理通訊 : fengtang_chang@yahoo.com.tw Mobile: 民國九十五年九月 1

2 觸媒 / 蓄熱式焚化技術 (CTO/RTO) 介紹技術原理優缺點安全性國內外發展現況應用可行性及成本評估未來應用建議 2

3 VOC Destruction Mechanism VOC + O 2 CO 2 + H 2 O+ HCl + SO 2 + N 2 More precisely: (where X is any one of halogen atoms (chlorine, flurine, bromine, iodine) C a H b N c O d S e X f +(a+e+o.25(b-f)-0.5d)o 2 aco (b-f)H 2 O+fHX+eSO cN 2 Operating parameters for 99% Destruction (3 T) Temperature : 750 ~ 850 ( 300 ~ 350. with Catalyst) Residence Time : 0.5 ~ 1 sec Turbulence : Re > 10,000 (Re = ρv D / μ) O 2 Concentration : Over 12% at 800 3

4 化法VOC THERMAL OXIDATION 焚依觸媒分類無觸媒直燃式焚化法 (Thermal Oxidizer ; TO) 具觸媒觸媒焚化法 (Catalyst Thermal Oxidizer; CTO) 依熱回收分類熱回收型恢復式直燃焚化法 (Recuptive Thermal Oxidizer) 熱再生型蓄熱式直燃焚化法 (Regenerative Thermal Oxidizer; RTO) 4

5 KINDS OF THERMAL OXIDIZER & COMPARISON Direct firing CTO RTO RCO System flow catalyst catalyst Exhaust gas Exhaust gas Exhaust gas Exhaust gas Operating Temp. Heat Exchange Type Thermal Recovery Eff. 750 ~ ~ ~ ~ 350 Recuperative Recuperative Regenerative Regenerative 40 ~ 70 % 40 ~ 70 % 95 % over 95 % over Low Fuel Consumption 5

6 Direct thermal oxidizer 6

7 Catalyst thermal oxidizer 7

8 CTO (Catalyst Thermal Oxidizer) 8

9 Conversion (%) Temperature ( )( 40,000 1/hr VHSV 9

10 觸媒成形型式 (Catalyst Type) Lifetime: approroximate 2~4years 10

11 DEVELOPMENT OF RTO 1 st generation 2 nd generation 3 rd generation 2 Bed 3 Bed Rotary type System flow Purge gas Purge Air Motor Problem & Development Untreated gas emit Develop when valve switch Pressure fluctuation when Valve switch Prevention of untreated gas Emission Pressure fluctuation Develop Many Numbers of valve Trouble factor No fluctuation of pressure Single valve (Rotary) 11

12 MECHANISM OF 2T-RTO Flow Schematic 1,400 F 1,500 F Heat Recover Media Heat Recover Media Valves switch every 90 ~180 secs. From Process T=150 F 250 F 12

13 MECHANISM OF 3T-RTO Independent Burners Clean Process Air Purge Air Heat Exchange Media Solvent-Laden Process Air 13

14 MECHANISM OF RRTO Pyro bloc A Bed B Bed Ceramic Media Bed A Bed B Heat Media A Temp. Heat Media B Outlet gas Inlet gas Exhaust gas Treated gas Purge Air A B Motor 14

15 ROTARY TYPE RTO LG Chem Kuck-Do Chem Cylindrical type Rectangular type 15

16 STRUCTURE OF R-RTO Burner Combustion chamber Ceramic media chamber Rotary valve Cylindrical type Rectangular type 16

17 R-RTO PRINCIPLE OF OPERATING N Straight-through Constant : Influent Air paths Flow path (No. Short : Effluent F Flushing Chamber Circuit) F N : Flushing : NON-FLOW F N F Inlet ZONE Outlet ZONE N F NON FLOW Chamber N F N 17

18 ADVANCED STRUCTURED BLOCK (HEAT MEDIA) RTO--Honeycomb Monoliths 18

19 CONTROL & MONITORING PC SCREEN (Example) 19

20 20

21 Issue#1 腐蝕性氣體 Acid Gas Dewpoints (Halogenated gases and SO 2 /SO 3 become corrosive to metals when they reach their dewpoint (liquid condensation). Hydrochloric acid (HCl) 1000/T dp = ln(p H2O ) ln(P HCl ) ln(P H2O )ln(p HCl ) Hydrofluoric acid (HF) 1000/Tdp= ln(p H2O ) ln(P HF ) ln(P H2O )ln(p HF ) Hydrobromic acid (HBr) 1000/Tdp= ln(p H2O ) ln(P HCl ) ln(P H2O )ln(p HCl ) Sulfuric acid (H 2 SO 4 ) 1000/Tdp= ln(p H2O ) ln(P SO3 ) ln(P H2O )ln(p SO3 ) Where: T dp dewpoint temperature (K) P partial preesure (atm) (Source: Kiang. Y.H., Predicting dewpoints of acid gas, chem. Eng.,1981 & Pierce, R.R., Chem., April 11, 1977.) 21

22 Issue#1 腐蝕性氣體 Acid Gas Dewpoints --- example Combustion of waste gas containing hydrogen sulfide produces com bustion products at atmospheric with the following composition: CO % ; H 2 O 11.41% ; N % ; O % ; SO % ; SO %, Please caculate sulfur acid dewpoint. ============================================ Using the equation for sulfuric acid (H 2 SO 4 ): 1000/Tdp= ln(p H2O ) ln(P SO3 ) ln(P H2O )ln(p SO3 ) P H2O = (11.41/100)= atm P SO3 =(0.003/100)= atm Substituting into the equation: Tdp = 400 K = 127 o C = 261 o F 22

23 Issue #2 理論空氣量 (Stoichiometric air) 維持繼續燃燒需不斷地供應空氣, 但空氣量過多時燃燒瓦斯之溫度降低熱效率則變低, 當空氣量過少則成為不完全燃燒為保持完全燃燒所需最少空氣量稱為理論空氣量 (1) 燃料之理論空氣量對碳為主之燃料而言, 燃燒時有下列反應 C + O 2 CO 2 當 12g 碳與 22.4L 氧反應時生成 22.4L 二氧化碳, 易燃物在空氣中燃燒時倘需計算理論空氣量時依下列方法則可空氣中氧與氮之比例為 21:79, 為燃燒 lkg 純碳時依上式為燃燒 1kg 純炭時則需 8.9m 3 空氣再以甲烷及丙烷在燃燒時所需空氣以下式而得 23

24 Issue #2 理論空氣量 (Stoichiometric air) 24

25 Issue #2 理論空氣量 (Stoichiometric air) 25

26 Issue #3 Energy balance LHV = HHV (N x 18.02) / MW VOC x 120 Where: LHV lower heating value (kcal/kg) HHV higher heating value (kcal/kg) N number of moles of water vapor produced per mole of VOC MW VOC molecular weight of VOC 120 heat (kcal/kg) required to evaporate water at 25 o C(77 o F) & 1 atm. Usually, a value of 90% of the HHV is a close approximation to the LHV. LHV 0.9 HHV Assume: 1 NM 3 /hr 600,000ppm(60% vol.) 的丙烷 (propane;c 3 H 8 ) 自常溫 25 o C 燃燒到 700 o C 所須理論空氣量至少為 28.3 x 0.6=17 NM 3 /hr a.) 丙烷 (propane;c3h8) 燃燒熱值 (Q release) = 60% x 1 NM 3 /hr x 1.82kgs/NM 3 x 12,034 kcal/kg x 0.9 =11,827 kcal/hr b.) 空氣溫升需熱值 (Q require) 17 NM 3 /hr x 1.293kgs/NM 3 x 0.26 kcal/hr. o Cx (700-25) o C = 3,858 kcal/hr c.) 至少需要冷卻空氣量 11,827 kcal/hr (1.293x0.26x(700-25))= 52 NM 3 /hr. 26

27 Issue #3 Energy balance Assume: 1 NM 3 /hr 20,000ppm(2% vol.) 的丙烷 (propane;c 3 H 8 ) 自常溫 25 o C 燃燒到 700 o C 所須理論空氣量至少為 28.3 x 0.02=0.57 NM 3 /hr a.) 丙烷 (propane;c3h8) 燃燒熱值 (Q release) = 2% x 1 NM 3 /hr x 1.82kgs/NM 3 x 12,034 kcal/kg x 0.9=394 kcal/hr b.) 17 NM 3 /hr 空氣溫升需熱值 (Q require) 17 NM 3 /hr x 1.293kgs/NM 3 x 0.26 kcal/hr. o C x (700-25) o C = 3,858 kcal/hr ( 需補充熱能 : 3, = 3,464 kcal (add 0.18 NM 3 PG fuel)) 如直燃爐加 (65%) 熱回收 Q require = 3,858 x (1-0.65) = 1,350 kcal/hr 如為 RTO (90%) 熱回收 Q require = 3,858 x (1-0.90) = 386 kcal/hr (Self sustain) c.) 至少需要冷卻空氣量 394 kcal/hr (1.293x0.26x(700-25))= 1.7 NM 3 /hr. 27

28 Issue #3 Energy balance 28

29 Issue #4 觸媒毒化 / 失活 29

30 Issue #4 觸媒毒化 / 失活 30

31 Issue #5 Safety & others 回火之預防 : Flame arrestor 燃燒爐點爐 ( 點火 ) 前須 fresh air purge 直燃爐 : 高溫出口煙囪結構強度高濃度之燃燒過溫保護裝置燃燒爐之正常暖機升溫率為 : 25 o C/min 直燃爐約需 30 mins, 直燃爐 +65% 熱交換器約需 60 mins, 觸媒焚化爐約需 30 mins, 蓄熱式焚化爐約需 mins. 31

32 Issue #5 Safety & others Flashback prevention techniques: Minimum velocity technique for flashback prevention. Flashback flame arrestor. Flashback prevention by using air to dilute waste stream to below LEL. Seal pot (sealing fluid) flash arrestor. Flashback velocity (ft/s) = x G x D Where G critical bounadry velocity gradient (1/s) D duct or pipe diameter (ft) (G value: Methane=400 ; Ethane=650 ; Propane=600 ; Propylene=700) Source from Nutcher,P.B. Maximum achievable control technology AWMA 87th Annu.,

33 Issue #5 Safety & others Explosive limit in air C m H x O y + zo 2 mco 2 + x/2 H 2 O LEL,(%) = 0.55 (100)/(4.7m x y) UEL,(%) = 3.50 (100)/(4.76m x y) LEL mixture, (%) = 1 / Σ (y i /LEL i ) UEL mixture, (%) = 1 / Σ (y i /UEL i ) y i mole fraction of component i on a combusitible basis. Example: Propane(C 3 H 8 ) LEL=2.1 vol.% ; UEL=9.5 vol.% Acetone(C 3 H 6 O) LEL=2.6 vol.% ; UEL=12.8 vol.% 33

34 觸媒價格 (Catalyst Price) Catalyst Description: PRO-PEL 14518, SPH, 1/8" Catalyst Type: Platinum and palladium catalyst on alumina spheres. Catalyst size: Nominal 1/8" diameter spheres Catalyst Space Velocity: ~10,000 1/hr Minimum Catalyst Depth: 10" Catalyst Price: $ 765 USD per cubic foot 1,000 scfm 6 cubic foot $4,590USD (NT$151,470) Catalyst Description: PRO-VOC 1A, MS, 400C, 22.25x23.25x3.5" Catalyst Type: Platinum and palladium support catalyst. Catalyst Support: Metal Monolith Honeycomb substrate(ms) Support Cell Density: 400 cells per square inch(400c) Catalyst Space Velocity: ~40,000 1/hr Catalyst Price: $ 3,250 USD per cubic foot (module) 1,000 scfm ~2 cubic foot $6,500USD (NT$214,500) 觸媒壽命一般約為 : 2~4 年 (offer by Sud-Chemie Prototech ) 34

35 Operating cost for treating general VOCs laden exhaust air 90 Required Heat (10,000 kcal/h) 45 Direct firing (η : 50%) CTO(η : 50%) VOC Combustion Heat T 1 Furnace Temp. q t q re Outlet Temp. t o q t q re T (750 ~ 850 ) 1 (300 ~ 350 ) q re T 2 T 2 q re q VOC q t t o q t RTO(90%) RTO(95%) t i Inlet Temp. q s Direct firing q VOC q VOC t o qs q s q VOC t o RTO CTO RCO Concentration (ppmv) Direct Thermal Oxidation Catalyst Oxidation Remark : q t q re q VOC q s Total Required Heat Recovered Heat VOC Combustion Heat Burner Supply Heat 35

36 OPERATING COST COMPARISON (Example) Operational Costs ($/hr) Process Stream Thermal Recuperative Oxidizer Catalytic Recuperative Oxidizer Regenerative Thermal Oxidizer Regenerative Catalytic Oxidizer 1,000 SCFM Percent LEL (Direct firing) (CTO) (RTO) (RCO) 6% LEL NT$93/hr NT$35/hr NT$20/hr NT$8/hr 60% LEL NT$56/hr NT$12/hr Assumes a 1,000 SCFM process stream with an inlet temperature of 70 o F. 2. Assumes a process mixture of 16,720 BTU/LB with a mixture LEL of 6%. 3. Assumes an electrical cost of NT$ 2.0 per KWH. 4. Assumes a natural gas cost of NT$150 per MMBTU. 5. The Catalytic Recuperative Oxidizer assumes a 65% efficient heat exchanger. 6. The Thermal Recuperative Oxidizer assumes a 65% efficient heat exchanger. 7. The Regenerative Catalytic Oxidizer assumes a 95% efficient heat exchanger. 8. The Regenerative Thermal Oxidizer assumes a 95% efficient heat exchanger. Data Source : Anguil VOC Hand Book. 36

37 Technology Destruction efficiency Capital Cost Operating Cost Maintenance Install time R-RTO 99% + AVG Low Low Low Conventional RTO 99% High AVG AVG High RCO 98% High Low AVG AVG Incinerator (Recuperative) 99% + AVG High Low Low Adsorber ( 活性碳 ) 98% Low Low High Low (Adsorbent exchange) Bio-filter 95% High Low High High 37

38 PICTURES OF Oxidizer 8,000 scfm RRTO 4,000 scfm TO 40,000 scfm RRTO 2,500 scfm 2T RTO 38

39 PICTURES OF RTO 39

40 VOC ADSORPTION ONTO ACTIVE CARBON ( 供參考 ) Adsorption capacity correlation: log 10 Q = A + B (log 10 y) + C (log 10 y) 2 where Q adsorption capacity at equilibrium, g voc /100g of carbon. y concentration in gas at 25 o C and 1 atm, ppmv. A,B and C correction constants. Name A B C ymin ymax Q@1000ppmv 吸附熱 (kcal/mol) 丙酮 E E , 丙烷 E E , 丁烷 E E , 戊烷 E E , 己烷 E E , MTBE E E , 吸附熱一般介於 12.0~15.5kcal/mol 之間. 40

41 THANK YOU!! 41

Building Technology Experience Center concept air conditioning concept heat pump special energy-saving techniques in hydraulics Concrete core conditio

Building Technology Experience Center concept air conditioning concept heat pump special energy-saving techniques in hydraulics Concrete core conditioning Initial situation Passive House Technology Experience