CONSULTANT & CONSTRUCTION
欽總工程股份有限公司
台北市110信義區永吉路179號12樓之1 TEL: 886-2-8787-8763 FAX:886-2-8787-8651
www.cceng.com.tw
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CONSULTANT & CONSTRUCTION欽總工程股份有限公司 台北市110信義區永吉路179號12樓之1 TEL: 886-2-8787-8763 FAX:886-2-8787-8651www.cceng.com.tw
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B. Recuperative Thermal Oxidizer C. Regenerative Thermal Oxidizer (RTO) D. VOC Thermal Oxidizer Rotor system (TO)
A. Thermal Oxidizer (TO)
1.0 Preface
Generally dealing with the volatile organic compounds by heat oxidation or biological oxidation methods. but the biological oxidation is few in application because of high operation and high maintenance cost. methods by oxidation of heat nowadays, divided into:1.Thermal Oxidizer (TO), 2.Recuperative Thermal Oxidizer, 3.Regenerative Thermal Oxidizer (RTO).
1. Thermal Oxidizer gets no heat recycle just burning directly out. 2. Recuperative Thermal Oxidizer heat recycle 50% 3. Regenerative Thermal Oxidizer (RTO) heat recycle over 90%
Owing to the volatile organic compounds of this project contains hydrogen, may add to as an auxiliary fuel for incinerator, putting invest cost into consideration, final decision is Thermal Oxidizer.
2.0 Basic designation
DATA:
3.0 Scope
1 Duct 2 Combustion system 3 Refractory lining 4 Fresh air inlet valve 5 Exhaust stack 6 Blower and motor7 Combustion air blower 8 Ignition system 9 Control panelExternally Mounted Panel Components : · Selector switch for mode of operation - Off/On/Idle · Unit start/stop and run lights, system status indicator lights · System reset button · Operating temperature set point adjustments · Two pen thermographic chart recorder for charting combustion chamber and stack temperature · Audible alarm and flashing light · Allen-Bradley 900 Color LCD Panelview MMI (Man Machine Interface) with real time process data and diagnostic program
Internally Mounted Panel Components: · Main power supply at 460 VAC, 30 amp fused disconnect, with 120 volt control power transformer · Allen-Bradley PLC 5/04 controller · Hayes compatible modem for remote system telemetry · Burner controller with Honeywell Flame Safety Control System
10 The others · Flow control valve with solenoids and pressure regulator · Compressed air accumulator tanks · Compressed air low pressure switch · Proof of airflow switch at fan · Differential proof of airflow across each recovery chamber inlet · All field thermocouples for burner control and high temperature stack warning · All burner safety component supplied with IRF/FM approvable gas train
Remark: Dust, solid state granule and alkaline soil shall not be allow enterTO. The installed TO of this project, dealing with polymerizing chemicals, and the exhaust is less than 100ppm.
C. Regenerative Thermal Oxidizer (RTO)
RTO flow sheet
1 Description of plant and process 1.3 Automatisation and regulation 2.1 Gas quantity and composition 2.5 Specification of main equipment
1 Description of plant and process
Regenerative thermal oxidation is one of the most efficient technologies to remove pollutants from waste air exhausts evading from processing plants at low energy costs. One of the main features of the RTO- process is the low primary energy requirement and the high performance rate. The plant consists of three reactors with ceramic packing which are connected at the top with a combustion chamber. The waste gas and clean gas, inlet and outlet connection are located at the bottom of the reactors. Special designed shut off valves ensure, that no slip streams between waste and clean gas occur.
The waste air which is polluted with styrene, butadiene and acrylonitrile is pre-heated to high temperatures of approx. 800°C before it enters the combustion chamber. The combustion chamber is equipped with a burner which increases the temperature up to 850 - 900°C. At this high temperature, together with a residence time of more than 1 second, all organic components are completely oxidized. The hot flue gases or the so called purified air, passes through a ceramic packing in which the heat of the purified air is transferred to the ceramic packing. The main advantage of the RTO technology is the low consumption of fuel for the process. This is achieved by the high pre-heating temperature prior to the incineration, combined with the high efficiency of the heat recovery system. The heat exchangers are in form of ceramic random packing which are filled in 3 metal reactors which are equipped with a internal refractory lining. The 3 reactors are connected which each other through the combustion chamber. The operation of the plant is cyclic. Polluted waste air is preheated in the 1st reactor, purified in the combustion chamber and is cooled in the 2nd reactor. In the 1st reactor the heat is transferred from the ceramic packing to the waste gas, in the 2nd reactor the heat is transferred from the clean gas to the ceramic packing. After a certain time period the flow through the reactors is changed, and the waste gas now passes through the 2nd reactor and is preheated and the clean gas flows through the 1st reactor. To minimize organic peaks which occur when switching from 1st to 2nd reactor a 3rd reactor is installed. All 3 reactors have the same dimensions. In reality the cyclic switching always includes 3 reactors whereas the reactor in which the waste gas passed through is purged before it is switched to the clean gas flow.
Since the waste gas sometimes contains organic substances, which may polymerise on the ceramic packing in the reactor, deposits may occur especially in the colder parts of the ceramic packing. It is therefore necessary to install a burn out system to remove these deposits. This burn out system is operated discontinuously only when the pressure drop exceeds set point limits. While the burn out system is running, it is necessary to interrupt the waste gas incineration. Air is blown through a special pipework to the preheating reactor, heated by the burner in the combustion chamber and flows through the burn out reactor. The ceramic packing in this reactor is heated to the ignition temperature of the deposits and the deposits are burned out. The flue gas is recycled to the inlet of the RTO-system and is cleaned in the 3rd reactor before it flows to the stack. During the burn out phase the RTO is not on stream. The system designed will oxidize the burn out products, so that no higher emissions than allowed are expelled into the surroundings. If requested from the client a burn out system during normal operation without interruption of the normal operating mode is possible. For this case the RTO-system has to be designed and executed with 4 reactors. During burn out 3 reactors are in normal operation to clean the waste gas and the 4th reactor is in burn out phase. This offer only refers to a system with 3 reactors.
1.3 Automatisation and regulation
The RTO incineration unit is equipped with a programmable control system. All field signals are registered in the automatisation system. The program controls the cyclic times, the incineration temperature and regulates a constant negative inlet suction pressure at the battery limits. The volume flow is regulated and controlled by a frequency converter, which adapts the rotation speed of the suction blower. The incineration temperature is regulated by the regulation valve of a burner fuel feed. All temperatures and pressures in the system are registered continuously. The valves for waste gas and clean gas are equipped with limit switches, so that the operation and position of the valves is continuously controlled.
The burner is operated with heavy oil. A special burner is equipped in the combustion chamber, which permits the incineration of heavy oil. This burner is equipped with a mechanical rotating atomisation disk, which enables a stable flame and a high combustion efficiency. The burner system is equipped with an ignition burner, which is connected with a LPG bottle. A continuous flame guard monitors the flame stability. The quantity of fuel supplied to the burner depends on the quantity of organic materials in the waste gas. When the content of organic wastes in the waste gas exeeds approximately 2,1 g/Nm3, no additional support fuel is required. The burner regulates automatically to the required fuel amount, so that only a minimum of fuel is needed for the operation of the plant.
2.1 Gas quantity and composition
The design capacities of the three versions of RTO-plants are 35.000, 50.000 and 100.000 Nm3/h. Impurities are styrene, butadiene and acrylonitrile.
Waste volume flow: type 1: 35.000 Nm3/h type 2: 50.000 Nm3/h type 3: 100.000 Nm3/h
Composition of waste gases Inlet temperature: 45 °C VOC content: 20 - 200 ppm type of organics: - styrene - butadiene - acrylonitrile Water saturated: .................. oxygene content in waste gas: 17 – 21 vol%
Clean gas outlet required expected NOx < 250 ppm < 50 mg/Nm3 SOx < 500 ppm < 100 mg/Nm3 CO < 2000 ppm < 50 mg/Nm3 Dust < 196 mg/Nm3 .................. VOC --- < 10 mg/Nm3
Waste gas inlet temperature 45°C Clean gas outlet temperature 80- 90 °C Reaction temperature 850 - 900°C Minimum reaction time 1 s RTO- Plant pressure drop approx. 40 mbar
Electrical power three phase A.C. 380/220 V, 60 Hz Fuel oil Class C- oil with sulphur content below 1% Heating value 9.750 kcal/kg Instrument air Supply pressure min. 6 bar gauge Dew point -23°C Pressurised air Supply pressure min. 6 bar gauge Dew point 15°C
Equipment design outdoor operation, 10 m above sea level 24 hour continuous operation Climatic data Ambient temperature 32°C Relative humidity max. 84% Wind velocity max. 60 m/sec ( 216 km/h ) Seismic data Zone coefficient 0,6 Facility factor 1,0 Site amplification factor 1,5 Codes and Standards Material DIN Mechanical parts DIN, ISO Electrical parts ICE
2.5 Specification of main equipment
The material, which is used for the manufacturing of the reactors is mild steel. For the reactor of the type 1) the reactor can completely fabricated in Austria and can be supplied in form of a cylinder. For the reactors type 2) and type 3) the steel shell is prefabricated and supplied in form of sheets, which have to be welded in cylindrical form on site.
Support grids for random packing: material 1.4571
Refractory lining Supplied in form of fire-resistant mineral wool including cement and connection pins. type 1 pre-installed in reactor approx. 50,0 m3 type 2 loose material approx. 62,5 m3 type 3 loose material approx. 100,0 m3 random packing: ceramic material
Steel structure and steel support structure prefabricated
Waste gas and clean gas collector piping including compensators and flanches, pre-fabricated.
Piping for combustion air, burn out, waste gas, heavy oil piping and pressurised air piping within the battery limits.
including shut off and regulation valves and combustion air blower 2 Burners
Burner line valves consisting of oil regulation valve, shut off valves, combustion air regulation valve
Waste air blower including frequency controller for waste air blower
Combustion air blower Regulation valves for blower including compensators
within the battery limits Ducts for waste/clean gas Ducts for combusrion air Pipes for heavy oil Heat tracing for heavy oil including compensators
3 inlet and outlet valves for waste gas and clean gas pneumatic operated, including pneumatic cylinders and limit switches 3 air purge valves, pneumatic operated 1 start up air valve, pneumatic operated 3 burn out valves, pneumatic operated All valves are equipped with pneumatic actuators, solinoid valves for pressurised air and two limit switches.
The electrical equipment consists of the following items: One power control board including Terminal clamps for connection to the incoming power cable, one main switch for power, one emergency- off switch, 380 Volt power distribution, 220 Volt control voltage distribution, frequency control for main fan, indication instrument for power, cubicle heating and illumination. One control board including Control voltage switch, programable logic control system software for automatic plant operation, standard display for plant operation, standard 12 channel point- plotter, indication lamps for operation and fault function of equipment, one emergency- off switch, cubicle heating and illumination. One burner control boards including Control voltage switch, standard burner contol device, indication lamps for operation and fault function of equipment, one emergency- off switch, safety thermostat switch, fuel pressure indication equipment, cubicle heating and illumination. Cable connection material including Power and control cables interconnecting the control boards and connecting local devices such as motors, limit switches, measuring equipment etc. Installation equipment like cable ducts, clamps, fastening equipment etc.
D. VOC Thermal Oxidizer Rotor system (TO) by DTC
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Update： 18th Aug. 2006 Contact us cceng.inc@msa.hinet.net
C＆C
ENGINEERING, INC
12-1, No.179, Yong Ji Rd., Taipei, Taiwan, R.O.C.
www.cceng.com.tw
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