Air Pollution Control Plant

Air control Engineering Co., Ltd.

RTO (Regenerative Thermal Oxidizer)

Product Introduction

  • RTO (Regenerative Thermal Oxidizer) is a device that combusts Volatile Organic Compounds (VOCs) at high temperatures of 800°C, achieving over 99% removal efficiency.
  • It utilizes ceramic heat exchangers to recover more than 95% of the heat generated during the combustion of VOCs, thereby minimizing the consumption of auxiliary fuels.

Operating parameters for 99% Destruction

  • Temperature : 750 ~ 850 ℃ ( 300 ~ 350 ℃. With Catalyst)
  • Residence time : 0.5 ~ 1 sec
  • Turbulence : Re > 10,000
  • O2 Concentration: Above 12% at 800℃

Characteristics

  • Very high removal efficiency for volatile organic compounds (over 98%).
  • Low operating costs due to heat recovery, with a thermal recovery(over 95%)
  • Capable of operation without auxiliary fuel when the organic compound concentration is 1.5~2g/Nm³.
  • Reducing fuel costs by utilizing waste heat for heating due to high incoming concentrations.
  • No pressure fluctuations (inlet suction) during long-term operation.
  • Long durability with minimal breakdowns.
  • Compact design compared to activated carbon adsorption systems.
  • Low secondary air pollution factors (minimal NOx emissions)

Application Areas

  1. 1Printing and Plating Industry
  2. 2Plating and Surface Treatment
  3. 3Petrochemical Industry
  4. 4Facilities Using Organic Solvents

Disadvantages

  • Initial installation costs are higher compared to adsorption towers.
  • Low incoming concentrations can result in higher fuel costs.

배출농도에 따른 최적 VOCs 처리시스템

입구 THC 농도(ppm) 처리 방법 상세설명
~ 35 ~ 흡착 교환법 흡착제를 이용하여 흡착 후 포화되면 새 것으로 교체함
흡착 재생법 흡착 후 포화되면 열, 압력 등을 이용하여 흡착제를 재생
~ 350 ~ 농축기 + 직접 소각법 농축기로부터 농축, 탈착된 성분을 직접 소각함
축열 소각법(RTO) 농축기로부터 농축, 탈착된 성분을 축열식 소각기로 소각함
촉매 소각법(RCO) 농축기로부터 농축, 탈착된 성분을 촉매식 소각기로 소각함
~ 3,500 ~ 직접 소각법 (TO) 유입되는 성분을 직접 소각함
축열 소각법(RTO) 유입되는 성분을 축열식 소각기로 소각함
촉매 소각법(RCO) 유입되는 성분을 촉매식 소각기로 소각함
~ 35,000 희석 소각법 유입되는 성분을 폭발하한 농도로 희석하여 직접 소각함
농축 회수법 유입되는 성분을 흡착, 탈착(농축)한 후 냉각, 응축하여 회수함
> 35,000 응축 회수법 유입되는 성분을 냉각, 응축하여 회수함

VOC 처리시설의 특징 및 장단점

구분 특징 및 장점 단점 적용공정
직연식연소로 (TO)
  • 가스를 700~900℃에서 산화분해
  • 완전연소시 고효율(99%)가능
  • 타르, 분진의 허용성 높음
  • 낮은 초기투자비용
  • 불연성용제 적용 불가
  • 연소시 2차 공해발생 주의
  • 높은 운전비 (고온연소,보조연료多)
  • 열교환기 이용
  • 고온연소에따른 설비대형화
  • 풍량변화가 없는 공정 저/중풍량
  • 고농도 (LEL20~25%)
촉매산화장치 (CO)
  • 열교환기와 촉매를 이용
  • 가스를 300~450℃에서 산화분해
  • 낮은 운전비 (저온연소)
  • 저온연소에따른 COMPACT한설비
  • 전기열원 사용가능
  • 유기실리콘등 촉매독 주의필요
  • 주기적 촉매재생 필요
  • 촉매독없는 중/대풍량(1000CMM 이하)
  • 중간 농도 (LEL10~20%)
축열식연소로 (RTO)
  • 가스를 800~850℃에서 산화분해
  • 축열체에서 95%이상의 열회수
  • 열회수율 높아 운전비 저렴
  • 2차 공해요인이 적음
  • 불연성용제 적용 불가
  • 높은 초기투자비
  • 심한 풍량/농도변화에 적응곤란
  • 중풍량 ( 100CMM 이상)
  • 중간농도 (LEL10%)
축열촉매연소 (RCO)
  • 가스를 250~400℃에서 산화분해
  • 축열체에서 92%이상의 열회수
  • 열회수율 높아 운전비 저렴
  • 2차 공해요인이 적음
  • 유기실리콘등 촉매독 주의필요
  • 주기적 촉매재생 필요
  • 높은 초기투자비
  • 심한 풍량/농도변화에 적응곤란
  • 비교적 대풍량 (300CMM 이상)
  • 낮은 농도 (LEL4%)
흡착(농축) (ROTOR)
  • 풍량, 농도변화에 대응용이
  • 불연성, 가연성 모두 처리가능
  • 운전비 저렴
  • 타르, 분진의 허용성 높음
  • 폭발하한의 1/3~1/4이상 농축불가
  • 고비점물질, 분진, MIST등이 포함시 전처리필요
  • 흡착제 주기적 재생/교체 필요
  • 농축가스의 2차처리 필요 (산화/회수)
  • 대풍량저농도공정

Feature of VALVE-RTO

  • The rotary rotation method experiences a significant drop in treatment efficiency in the event of a leak and is difficult to maintain; therefore, ACE applies a valve opening and closing method.

Comparison of DISK Rotary TYPE vs. VALVE TYPE

Category DISK Rotation TYPE VALVE TYPE
Advantages
  • Relatively simple structure.
  • Constructed with cast materials to ensure durability.
  • Slightly lower cost.
  • Usable at 150~200℃ high temperatures.
  • No leaks at all.
  • High treatment efficiency.
  • Usable above 250℃
  • imple maintenance (easy for anyone to repair).
  • Minimal pressure loss.
  • Valve usage is semi-permanent.
Disadvantages
  • Requires replacement if wear-related failure occurs.
  • Treatment efficiency decreases with prolonged use due to wear.
  • The rotary is integrated and cannot be repaired outside the manufacturer, requiring a significant amount of time for maintenance.
  • Difficult sealing due to cast structure, leading to leaks.
  • High pressure loss in rotary.
  • Control systems are somewhat complex.
  • Higher cost.
  • Periodic maintenance of actuator solenoid required
Maintenance Cycle
  • 1 year (packing within 6 months)
  • Actuator guaranteed for 2 years.
Treatment Efficiency
  • 93~95%
  • 99%
  • Combustion Chamber Temp. (750℃~800℃)

PERFECT – Advantage of RTO

  • Excellent VOC removal efficiency(99~99.5%).
  • Sustainable processing efficiency rate
  • Robust design for temp. change and rotary sealing
  • Easy rotary self-maintenance
  • Operating even with some of valve malfunction
  • Controllable rotary size depending on air flow, operating with large air flow as well
  • Easy to operate & maintain
  • Good heat recovery rate due to large air distribution range
  • Power cost saving due to low pressure loss
  • Low cost for maintenance

RTO [VALVE ROTARY SYSTEM]

  • Combustion chamber, Floor structure & Distribution chamber are divided into fan-shaped 5 cells.
  • They perform pre-heating and heat-recovering for each sequentially changing 2 BED of cool or heat zone with rotary rotation.
  • For this moment, there is purge zone b/t cool & heat zone to prevent mixing raw gad and treated gas by holding raw gas
  • while transferring from cooling to heating.

VOCs combustion treatment process

VALVE TYPE RTO Photo

Concentration+RTO

Concentration + RTO

  • Low-concentration, high-flow VOC-containing air is concentrated by a concentrator into high-concentration, low-flow air before oxidation in a combustion device.
  • The concentration process reduces the size of the combustion device, allowing for a cost-effective and compact solution.
  • The concentration process reduces fuel consumption of the combustion device, utilizing the regeneration heat source from the combustion exhaust.

CONCENTRATOR

  • The concentrator is a device that processes low-concentration, high-flow VOC-containing gases into high-concentration, low-flow gases for exhaust treatment, efficiently handling VOCs in combination with an RTO.
  • Concentrated zeolite is a porous material with micro-pores (0.2–1.0 nm) that generates molecular vibrations to facilitate adsorption within these micro-pores.
  • The adsorption characteristics can vary significantly depending on the type of zeolite.

Operational Description of the Concentrator

  1. 1VOCs are introduced and adsorbed as they pass through the adsorption rotor, designed for an adsorption efficiency of 90–95%.
  2. 2Other clean air is discharged through the stack.
  3. 3The VOCs adsorbed on the rotor are separated and desorbed by hot air in the high-temperature zone (180°C–200°C) as the rotor rotates.
  4. 4The heated area is then regenerated to restore its adsorption capacity.
  5. 5The desorbed high-concentration gas is combusted in the RTO, achieving a concentration 3 to 20 times greater than the incoming VOC concentration.
  6. 6The rotor continuously processes the cycle of adsorption, desorption, cooling, and re-adsorption at a constant speed driven by the motor.
  7. 7The motor and rotor are connected through a driving chain.

Characteristics

  1. 1The rotary design is simple, making maintenance convenient.
  2. 2Continuous concentration processing of VOCs is possible.
  3. 3Suitable for handling low-concentration, high-flow volumes, reducing running costs.
  4. 4The rotor uses hydrophobic zeolite as the adsorbent, which is non-combustible.
  5. 5Capable of processing a wide variety of solvents (VOCs).
  6. 6Concentration of VOCs can be increased by 3 to 20 times.

Application Examples

  • Painting Booths
  • Local Exhaust in Printing Lines
  • Exhaust in Coating Zones

Typical VOC Application Table 1

Performance Ratings: A: Excellent, B: Good, C: Possible, D: Not Applicable

VOC ROTOR LINEUP
HZ-AM HZ-BM HZ-XM
Aromatic compounds Toluene B A B
Xylene A C A
Trimethyle benzene A D A
Styrene D A D
Ketones Acetone C B B
MEK B A A
MIBK B A A
Cyclohexanone A C A
Esters Ethyl Acetate B A A
Butyl Acetate B A A
PGMEA B A A
Alcohols Methanol C C C
Ethanol C B C
IPA C B B
Butanl B A A
others Naphtha A~D A~D A~D
NMP A C B
DCM D B C

Typical VOC Application Table 2

GROUP NAME VOC CONCENTRATION ROTOR
V-MAX
Ⅰ Ⅱ Ⅲ Ⅴ
Alphatic hydrocarbons n-Hexane ○ ○ ◎ ◎
Cyclohexane △ △ △ △
Alcohols Methanol × × △ ○
Ethanol △ ○ △ ◎
n-Propanol ○ ○ ○ ◎
Isopropanol (IPA) ○ ○ ○ ◎
n-Butanol ◎ ◎ ◎ ◎
Diacetone alcohol ◎ ◎ ◎ ◎
Ketones Acetone △ △ ○ ◎
Diacetone alcohol ○ ◎ ◎ ◎
Methyl ethyl ketone (MEK) ◎ ◎ ◎ ◎
Methyl isobutyl ketone (MIBK) ◎ ◎ ◎ ◎
Methyl amyl ketone (MAK) ◎ ◎ ◎ ◎
Methyl propyl ketone ◎ ◎ ◎ ◎
Cyclohexanone ◎ ◎ △ △
Esters Ethyl acetate ○ ○ ◎ ◎
n-Propyl acetate ○ ◎ ◎ ◎
n-Butyl acetate ◎ ◎ ◎ ◎
Methyl cellosolve acetate ◎ ◎ ○ ○
Ethyl cellosolve acetate ◎ ◎ ○ ○
Butyl cellosolve acetate ◎ ◎ ○ ○
Propylene glycol monomethyl ether acetate (PGMEA) ◎ ◎ ○ ○
Ethers Methyl cellosolve ◎ ◎ ◎ ◎
Cellosolve ◎ ◎ ○ ○
Butyl cellosolve ◎ ◎ ○ ○
Propylene glycol methyl ether (PGME) ◎ ◎ ◎ ◎
Aromatic hydrocarbons Benzene △ △ ○ ○
Toluene ○ ○ ○ ○
o-Xylene ◎ ◎ × ×
m-Xylene ◎ ◎ × ×
p-Xylene ◎ ◎ ○ ○
Styrene × × ◎ ◎
Ethyl benzene ◎ ◎ ○ ○
Chlorinatec hydrocarbons Dichloro methane × △ ○ ○
Trichloro ethane △ △ ○ ○
Others N-methyl-2-pyrrolidone (NMP) ◎ ◎ ○ ◎
N,N-dimethylformamide (DMF) ○ ◎ ◎ ◎
N,N-dimethylacetamide (DMAC) ◎ ◎ ○ ○
Dimethylcarbonate (DMC) ○ ◎ ◎ ◎
Tetrahydrofuran (THF) ○ ○ ◎ ◎

Example of Valve Rotary replacement

< RTO 18,000 + Concentrator 90,000 m3/hr >

Design Elements of the RTO System

Review Items Details Design Approach
Inlet THC Concentration Variation High Concentration Inlet Risk of explosion if LEL concentration is exceeded. Concentration balancing using adsorbents (zeolite) (prevent explosions and reduce fuel costs)
Low Concentration Inlet Excess fuel gas consumption due to lack of thermal energy
Risk of explosion and fire THC Concentration Management If the THC concentration exceeds the LEL concentration, it poses a risk of explosion and fire
  • Monitoring combustible gas concentrations with IR temperature sensors and THC sensors
  • Maintain the LEL concentration below 25% at 25°C
  • In the case of high concentration inflow, introduce fresh air and execute shutdown (emergency vent) if control is lost after an alarm
  • Control combustion chamber temperature during high concentration inflow (Hot Bypass, Cool Bypass System)
  • After re-start, purge with outside air before igniting the burner
Device Protection Even in the event of an explosion, pressure, backfire, and other phenomena are suppressed to protect related devices
  • Install explosion relief vents or rupture disks where necessary
  • Prevent system backfire using a wet scrubber (flame arrester)
Clogging Issues
  • Clogging from incoming dust, mist, and tar
  • Manual cleaning
  • Replace Adsorbent
  • Removal of fine particulate matter using fine filters
  • Removal of particulate matter through cooling, condensation, and inertial collision using a wet scrubber
  • Apply bottom-layer adsorbent separation for easy maintenance
  • Execute bake-out sequence after shutdown to eliminate smoke and odor
  • Implement high-temperature positive pressure purge system and pre-heating for continuous operation to prevent adsorbent blockage
  • Protect upper adsorbent from damage (control burner step during heating, proportional control of hot bypass)
Performance Guarantee Fuel Consumption
  • Emergency discharge to prevent overheating during high concentrations
  • Excessive fuel gas usage due to thermal energy shortage during low concentrations
  • Fuel consumption varies based on inlet concentration and thermal efficiency
  • Concentration balancing by the adsorbent layer reduces fuel consumption
Thermal Efficiency Guaranteed above 95% unless specified by the customer
  • Reinforcement of insulation and adsorbent
  • Guarantees above 97% if requested by the customer
  • Application of separated rotary to prevent uneven flow
THC Treatment Efficiency Guaranteed above 99% unless specified by the customer
  • Increase in combustion chamber volume and temperature
  • Application of high-temperature positive pressure purge system and pre-heating
  • RTO reprocessing system