Spent Caustic Thermal Oxidizer Application · Mist Eliminator Make-Up Water Recycle Quench Water Make-Up Water Contactor Section ©2019 John Zink Company LLC Proprietary & Confidential

Spent Caustic Thermal Oxidizer Application

Gianluca Tanda

©2019 John Zink Company LLC **Proprietary & Confidential** 2

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Spent CausticThermal Oxidizer


Ethylene market

► Ethylene is a key building block for plastics, polyester

and synthetic rubber. China is the world’s largest

petrochemical consumers and importers


Spent Caustic Incinerator

► SPENT CAUSTIC : blow down from caustic scrubber towers used

to remove acid gases and traces of other impurities from raw

cracked gas streams in ethylene plants.

► Typical compositions:

► small amounts of hydrocarbon

► approx. 5-7 wt. % sodium carbonate

► approx. 3 to 4 wt. % sodium hydroxide

► less than 1 to 3 wt. % sodium chloride

► Balance: water.



► DESIGN PHILOSOPHY AND GENERAL DESIGN

CONSIDERATIONS

► Usually 2 trains – 100% back-up

► Typical size: 6000 Kg/hr of spent caustic

► Systems are operations and maintenance intensive

► Refractory is typically a critical part of the package due to

salt attack


Basic Process

❖ NOX

❖ CO

❖ TOC

❖ Dioxins

❖ Optimal fuel consumption

❖ HCl / Cl2

❖ Particles

❖ (Dioxins)

❖ NOX removal

❖ others ?

Combustion System

Flue Gas Treatment

Waste Streams

To stack

Target Variable


Typical Emission Limit

NOX

Carbon Monoxide

[DRE]

EMISSION LIMIT

Particulate

100 mg/Nm3

CHINA

80 mg/Nm3

Up to 99.9999

20 mg/Nm3

Dioxine 0.1 ng TEQ/Nm3


Basic Process

▪ BASIC PROCESS SECTIONS

Burner

ThermalOxidizer

ConditioningTower

SaturationQuench

Particulate /Acid Gas Removal

CombustionSection

CoolingSection

Dry Removal

Wet Removal



► DESIGN PHILOSOPHY: DOWN FIRED CONFIGURATION

- Prevent build up of material that

would occur in horizontal or

vertical up-flow units

- In horizontal or vertical up-flow

chamber — Material would collect

at bottom of T.O. & could not be

removed unless system was

shutdown

- As solid or melted material “falls”

downward (gravity) during

operation, it will pass through the

oxidizer into next section for

further treatment


JZ Y burner


Dioxin

► Group of chlorinated dioxins and furans of similar chemical

structure.

► The most Toxic form of dioxins is 2,3,7,8 Tetrachlorodibenzodioxin ( 2,3,7,8

TCDD) which is sometimes referred to Seveso poison.


Dioxin


JZ KEU Combustor burner

- Multi purpose liquid

combustion system

- BAT for Dioxin Free

combustion of Chlorinated

hydrocarbons



WORKING PRINCIPLE



OPTIMIZED COMBUSTION PROCESS OF THE 3T OF COMBUSTION,

TEMPERATURE, TIME AND TURBOLENCE

ADVANTAGES:

► Equal temperature level across the section of flame

► Zero Dioxine formation

► Low formation of Nox

► High destruction efficiency



- BAT for Dioxin Free combustion of

Chlorinated hydrocarbons

- Clean shape

- Good Mixing

- No Hot Spot


Combustion section

- Regulations require 850 ⁰C

operating temperature for 2

seconds for hydrocarbon

wastes and 1100 ºC for 2

seconds for > 1% halogenated

substances

- JZ demonstrated good

performance @ 950-980 ⁰ C

Burner /Combustion

Zone

ThermalOxidizer


Refractory

Alkali attack (sodium attack)

- Castable is not suitable.

- Brick should be considered

- Alkali reacts with free Al2O3

- Minimize free Al2O3 and porosity in

the refractory system


Cooling Section

▪ Dry - Conditioning Tower Hot Flue Gas Inlet

Cooled Flue Gas

ConditioningWater, Air, or

Recycled Flue Gas

Clean OutConnection


Cooling Section

▪Wet Conditioning Tower

QuenchWater

QuenchedFlue GasInternal

Downcomer

Manway

Clean Out / Blow Down at Bottom of

Cone

Contactor Tube

Weir

Hot Flue Gas


Particulate Removal— Wet

▪ Venturi-Type Scrubber

ScrubbingWater

QuenchedFlue Gas

ToSeparator

ConvergingInlet Diverging

OutletThroat

EncapsulatedParticulate

Particulate


Particulate Removal— Dry

▪ Baghouse

Flue Gas w/Particulate

CleanedFlue GasCleaned Gas Plenum

Hanging Bag Section

ParticulateCollectionHoppers


Equipment Configurations

▪ Downfired Salt System – Quench to Saturation

CombustionAir Blower

ThermalOxidizer

VentStack

Fuel

QuenchPot

WasteInjection

High Velocity Scrubber

Mist Eliminator

Make-Up Water

Make-Up WaterRecycle Quench Water

ContactorSection


Equipment Configurations

▪ Downfired Salt System— Condition to Low Temperature

ConditioningTower

ThermalOxidizer

ESP OPTION

BAGHOUSE OPTION

Stack

Air

Fuel

WasteInjection

Flue Gas

600 oF

350 oF

Dry Salt

Dry Salt

Air and/orH2O

Dry Salt


Waste Heat Boiler

BurnerCombustion

ProcessWaste Heat

BoilerParticulate

RemovalStack


Waste Heat Boiler: water tube type

- Cooling below melting points of

the solids formed in the

combustion process

- Soot blowers will be required .


Waste Heat Boiler: membrane type

- The external surface of the

boiler are completely covered

by tubes full of water;

- The heat transfer between the

hot flue gas and the water will

occurs thanks to the radiation

phenomena.

- A layer of salt may freeze on

the wall acting as “refractory”

REFERENCES


References

Saudi Kayan (Al-Jubail, Saudi Arabia)

SCOPE OF SUPPLY

- Thermal oxidizer burner

- Combustion chamber

- Conditioning chamber

- Combustion air blower

- Quench air blower

- Bag-house filters

- Flue gas stack


References

Sharq (Al-Jubail, KSA) SCOPE OF SUPPLY

- Burner

- Combustion chamber

- Quencher

- Flexiventuri

- Scrubber

- Reheater

- SCR Catalyst

- Stack


Al-Jubail, Saudi Arabia

References


References

Repsol (Puertollano, Spain)

Thank You!

Documents

Spent Caustic Thermal Oxidizer Application · Mist Eliminator Make-Up Water Recycle Quench Water Make-Up Water Contactor Section ©2019 John Zink Company LLC **Proprietary & Confidential**

Spent Caustic Thermal Oxidizer Application · Mist Eliminator Make-Up Water Recycle Quench Water Make-Up Water Contactor Section ©2019 John Zink Company LLC Proprietary & Confidential