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Thermal Oxidizers for VinylChloride Monomer plant
Thermal Oxidizer Technical Forum, 2019
Nov. 13th ,Seoul
Minwoo Kwon, P.E. PMP
Director of Engineering | Thermal Oxidizer
CHLORINATED THERMAL OXIDIZER APPLICATIONS
2019
©2019 John Zink Company LLC **Proprietary & Confidential** 3
Process in Vinyl Chloride Monomer (VCM)
Vinyl Chloride Monomer, made from Ethylene and Choline by Pyrolysis. Feedstock for the common plastic material PVC.
Vapor Thermal Oxidizer
OXY
Chlorination
VCMPurification
Cracking
Furnace
EDCPurification
Direct
Chlorination
Drying
Column
Liquid Thermal Oxidizer
Emergency
Scrubber
Dry Process Vents
Light Components Vents
Wet Process Vents
HeavyComponents
Waste
LiquidDrain
RecycleEDC
VCMProduct
(Store inSpheres)
HCL
CrudeEDC
O2
C2H4
Start-upShut-Down
OXY Vent
Waste
Crude
EDC
Pure
EDC
EDC,HCL,VCM
Cl2 (Chlor-Alkali plant)
C2H4 (Ethylene)
©2019 John Zink Company LLC **Proprietary & Confidential** 4
What is a Chlorinated Compound?
Any chemical (usually organic) compound with at least one atom ofchlorine
Examples: Vinyl Chloride C2H3Cl
Chloroform CHCl3
Methyl Chloride CH3Cl
Dichloromethane CH2Cl2
Dichloroethene C2H2Cl2
Trichloroethane C2H3Cl3
Chlorobenzene C6H5Cl
Vinyl Chloride is a colorless, flammable gas.
Highly Toxic and Carcinogenic
C
H H
H Cl
C C
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Main System Objectives
Combust/Oxidize all hydrocarbons, Complete Combustion
CH4 + C2H3Cl + O2 + N2 CO2 + H2O + HCl + O2 + N2
Absorb and Recover HCl
Neutralize HCl
Major objective is the processing/elimination of the HClHCl = Hydrochloric Acid
H Cl
HCl
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General System Configurations
Chlorinated System Options:BurnerRefractory Lined Thermal Oxidizer ChamberWaste Heat Boiler w/ Quench System (stand-alone or combined)Stand-Alone Quench SystemCombined Quench/Absorber TowerAbsorber TowerScrubber TowerFine Drop DemisterGas-Gas Heat ExchangerRe-heat burner and chamberSCR SystemForced, Induced, or Balanced draft systems
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Overall System Configurations
VCM Thermal Oxidizer system withRMB Burner, Combustion Chamber, WHB, combined quencher/absorber tower, scrubber, fine drop demister, re-heat system, and SCR system
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Overall System Configurations
PFD Diagram
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Overall System Configurations
PFD Diagram
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Overall System Configurations
PFD Diagram
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Thermal Oxidizer Combustion System
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Burner
Provides the necessary energy to maintain unit operatingtemperature
Special MOC required for wet chlorinated streams come intocontact with burner metallic parts Hastelloy
Standard design philosophy
Can utilize standard Y-Burner technology or Ultra-Low NOxburner technology such as the Rapid Mix Burner (RMBTM)
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Thermal Oxidizer Chamber
Turbulence
Temperature
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Chemical Reactions and Products of Combustion
Oxidizing Chlorinated Compounds Results in Production of Acid Gas
Ideal – CO2, H20, N2, O2
CH4 + O2 + N2 CO2 + H2O + O2 + N2
Reality – VOC’s, CO, NOx, HCl, Cl2… etc
CH4 + CH3Cl + O2 + N2 CO2 + H2O + O2 + N2 + HCl + Cl2 + NOx + CO
+ UHC + Dioxin
C
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Chemical Reactions and Products of Combustion
Dioxin / Furan FormationChlorine Present
400 - 1,000°F (204 - 538°C) Temperature Range [Oxidize over 1,000°F(538°C)]
Heavy Metals Catalyze Reaction (Ash & Particulate)
Much more prominent in applications with waste heat recovery
©2019 John Zink Company LLC **Proprietary & Confidential** 16
Acid Gases— HCl, HBr, HF, HI (Halogen Acids)
Free Halogen Gas— Cl2, Br2, F2, I2 (Diatomic)
Oxidizing Halogen Containing Compounds Forms Acid Gases & Free HalogenGases
Free Halogen Gas Concentration is Based on Operating Parameter of System &O2 / H2O Ratio in Formation Area (Water in Thermal Oxidizer SuppressesFormation of CL2)
C
Chemical Reactions and Products of Combustion
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Thermal Oxidizer Chamber
Temperature Contours Through Thermal Oxidizer with Exothermic Waste gas
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Thermal Oxidizer Chamber
Provides the necessary time, temperature, and turbulence for propercombustion/oxidation of waste streams
Carbon steel construction
Minimum 1 second residence time
Waste Gas Injection
Elevated operating temperatures
Brick lined vessel with IFB or ceramic fiber board as backup material
Mastic lining
CRITICAL: Ensure steel operating temperature is above the acid dewpoint of theacid gas Temperatures under 300°F (149°C) have a VERY sharp increase in electromechanical
corrosion
©2019 John Zink Company LLC **Proprietary & Confidential** 19
Thermal Oxidizer Chamber
Dew Point Corrosion Sulfur and Chlorine convert to oxides through combustion process.
H2S + O2 -> SO2
SO2 + H2O -> H2SO4
CH3Cl + O2 -> HCl
Combine with water vapor to form H2SO4 and HCl. Acid Dew Point Corrosion
Heat transfer analysis of shell dew point calculation.
Maintain the shell temp hot.
Apply shell coating or mastic materials.
Acid Attack In Refractory System. Sulfur and Chlorine react with “free” CaO present in refractory castable cemment.
Minimize CaO in the refractory system.
Chlorine, High reactivity. More reactive than Sulfur.
Minimize the CaO in the refractory system.
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Thermal Oxidizer Chamber
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Waste Heat Boiler
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Waste Heat Boiler
Firetube Boiler Example
DowncomerPipe
Riser Pipe
Steam Drum
ExchangerSection
Tubesheet
Refractory
Hot FlueGas
Steam Mist Pad
Warm FlueGas
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Quencher/Absorber + Scrubber
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Stand-Alone Quench System
Water Wier
Contactor
Tank
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Stand-Alone Quench System
Provides sufficient water to achieve saturation of the entering flue gasEvaporation of the cooling water is much MORE effective in cooling the flue
gas than convective/conductive effects between the liquid and gas phases
Components and MOCWater Weir and Liquid Atomizers Zirconium
Contactor Hastelloy
Tank FRP (Fiber Reinforced Plastic)
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Stand-Alone Quench System
Water Weir Assembly
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Stand-Alone Quench System
Contactor Assembly
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Stand-Alone Quench System
Tank Assembly
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Packed Quench/Absorber Tower
Pump
Make-up
Water
Acid Blowdown
Packing Bed
Clean Flue Gas Exit
To Scrubber
Flue Gas Inlet
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Packed Quench/Absorber Tower
Provides the necessary surface area to increase mass transfer of HClfrom the vapor phase to the liquid phase
Can easily achieve 90%+ HCl removal efficiencies from the flue gas
HCl concentrations in liquid phase can easily achieve up to 18% wt.Above this value, additional pieces of equipment such as recirculation coolers
and/or multiple packing stages are required
Typical MOC is FRP
Absorber tower becomes more desirable as the price of water increases.
©2019 John Zink Company LLC **Proprietary & Confidential** 31
Packed Quench/Absorber Tower
An azeotrope between HCl and Water forms at approximately 20.2%wt. (at atmospheric conditions)To achieve concentrations above 20.2% wt., the azeotrope must first be
broken/shifted (altering pressures/temperatures and/or the addition of anotherchemical)
Main benefits of an absorber:Recovery of a potential productSmaller scrubber blowdown rates to plant water treatment facility
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Caustic Scrubber
Clean Flue Gas Exit
Stack
Flue Gas Inlet
Packing Bed
Pump
Mist Pad Wash
Recirculating Liquid Sump
Liquid Distributor
Feed
Intermittent Wash
Salt Water Effluent(7% by Weight)
Caustic (20% SodiumHydroxide)
Make up water
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Caustic Scrubber
Chemical Reaction:HCl + NaOH -> H2O + NaCl
Typical MOC is FRP
pH is controlled to about 8-9Too acidic: removal efficiency decreasesToo basic: begin scrubbing out CO2
Scrubber necessary to achieve emission requirements
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Caustic Scrubber – Cl2 Removal
To remove Cl2 gas from flue gas stream, inject one of the two thefollowing solutions:
Sodium Thiosulfate Na2S2O3
Sodium Sulfite Na2SO3
Other chemicals are available
Can be injected in the absorber, scrubber, or both as needed
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Demister
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Fine Drop Demister
Inertial impaction
> 5 to 20 microns
Direct interception
<1 to 5 microns
Brownian diffusion
< 1 micron
Mesh
Vanes
CollectionMechanism
Mist Eliminator Type
Mesh
Fiberbeds (IC)
Fiberbeds (BD)
Note
• Particles collide withfiber
• Efficiency increaseswith velocity
• Particles touch fiber• Efficiency independent
of velocity
• Particles hit fiber asa result of random
movement• Efficiency increases
as velocity decreases
©2019 John Zink Company LLC **Proprietary & Confidential** 37
Fine Drop Demister
FLEXIFIBERTM Mist Eliminators
©2019 John Zink Company LLC **Proprietary & Confidential** 38
ReHeater + SCR
©2019 John Zink Company LLC **Proprietary & Confidential** 39
Re-heat System
Burner and small furnace used to heat the cleaned, saturated flue gasfor treatment in an SCR system
Usually re-heats the flue gas to approximately 500°F (260 °C)
Not refractory lined
Typical MOC is 316SS or Hastelloy
Can include Gas/Gas Heat Exchanger for further heat recovery
©2019 John Zink Company LLC **Proprietary & Confidential** 40
SCR System
Selective Catalytic Reduction
Uses a reagent (NH3) to break down the NOx
Injected upstream so that it is evenly distributed
Reactor flue gas temperature between 450-800°F
Predictable, guaranteed NOx emissions down to 2 ppm
NOx N2 + H2O + NH3NOx +NH3
©2019 John Zink Company LLC **Proprietary & Confidential** 41
Summary
Chlorinated Waste Characteristics
Operational Goals
Major Equipment: Thermal Oxidizer
Waste Heat Boiler
Direct Quench
Absorber Tower
Scrubbing Tower
Vent Stack
QUESTIONS?
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Safety Notice
As a simple safety reminder, the equipment discussed during the presentation may differ somewhat from thatthat the student operates.
The student must take into account that the training material is in addition to and does not replace the student’scompany’s existing procedures and policies regarding specific equipment safety, operation and maintenance.
©2019 John Zink Company LLC **Proprietary & Confidential** 44
Important Notice
The information contained in these materials is for informational purposes only and is provided “AS IS”, withoutwarranties of any kind. Your use of the information contained herein is at your sole risk. We expressly disclaimany express or implied representations, warranties or guaranties, including without limitation, the impliedwarranties of merchantability and fitness for a particular purpose. We will have absolutely no liability (whetherdirect, indirect or consequential) in connection with these materials (and/or the information contained therein)including without limitation, any liability for damage to person or property. We also reserve the right to makesubsequent changes to the materials without prior notice. For purposes of this notification, “We” includes JohnZink Company, LLC and its affiliates and their respective employees, partners, principles, agents andrepresentatives, and any third-party providers or sources of information or data.
This presentation may contain confidential and proprietary information of John Zink Company, LLC and itsaffiliates and may not be disclosed or reproduced without John Zink’s written permission.
The views, statements, and recommendations expressed by any presenters who are not employees of John ZinkCompany LLC do not necessarily reflect the position of John Zink Company LLC.
For information on patents and trademarks see johnzinkhamworthy.com/legal-notices.
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