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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)


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


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


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


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



PFD Diagram



PFD Diagram



PFD Diagram


Thermal Oxidizer Combustion System


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)


Thermal Oxidizer Chamber

Turbulence

Temperature


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



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


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




Temperature Contours Through Thermal Oxidizer with Exothermic Waste gas



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



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.




Waste Heat Boiler


Waste Heat Boiler

Firetube Boiler Example

DowncomerPipe

Riser Pipe

Steam Drum

ExchangerSection

Tubesheet

Refractory

Hot FlueGas

Steam Mist Pad

Warm FlueGas


Quencher/Absorber + Scrubber


Stand-Alone Quench System

Water Wier

Contactor

Tank



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)



Water Weir Assembly



Contactor Assembly



Tank Assembly


Packed Quench/Absorber Tower

Pump

Make-up

Water

Acid Blowdown

Packing Bed

Clean Flue Gas Exit

To Scrubber

Flue Gas Inlet



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.



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


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


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


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


Demister


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


Fine Drop Demister

FLEXIFIBERTM Mist Eliminators


ReHeater + SCR


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


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


Summary

Chlorinated Waste Characteristics

Operational Goals

Major Equipment: Thermal Oxidizer

Waste Heat Boiler

Direct Quench

Absorber Tower

Scrubbing Tower

Vent Stack

QUESTIONS?


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.


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.

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Documents

Thermal Oxidizers for Vinyl Chloride Monomer plantWaste Heat Boiler Firetube Boiler Example Downcomer Pipe Riser Pipe Steam Drum Exchanger Section Tubesheet Refractory Hot Flue Gas