Understanding Spray Technology to Optimize Sulfur Burning

Understanding Spray
Technology to Optimize
Sulfur Burning
Presenters:
Chuck Munro
Dan Vidusek
About Spraying Systems Co.
• 75 year nozzle engineering &
manufacturing company
• Leader in spray technology
• Manufacturing facilities in 9 countries
• Global sales and support
• More than just nozzles:
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•
•
•
headers
injectors
spray controls
spray research & testing
It always starts with the nozzle
• Provides a specific volume of fluid at a
specified pressure drop
• Converts fluid into a predictable drop size
spectrum with a specific spray coverage
• The nozzle is the heart of the process –
a small component that greatly
affects system performance
Hydraulic Atomizer Types
Hollow
Cone
Full
Cone
Flat
Spray
Hollow Cone Spray
• Spray is formed within the nozzle
by an inlet that is tangential to a
whirl chamber
• The resulting whirling liquid
forms a hollow cone as it leaves
the orifice
• Large free passages for good
clog resistance
Sulfur Burning Nozzle
• 1/2BA-309SS70
— Hollow cone spray pattern
— Small to medium sized
droplets
— Large, unobstructed flow
passages to minimize
clogging
— Relatively low cost to operate
Dual Fluid – Air Atomizing
• Gas and liquid are mixed in an internal chamber;
spray exits orifice in a flat or round spray pattern
• General nozzle characteristics:
— Smallest drop size
— Narrow
drop size spectrum
Air Caps
— Sensitive to changes in operating pressures
— Large free passage
— Relatively high resistance to clogging
GAS
LIQUID
High Volume
Dual Fluid Nozzle
Stage Three:
Gas cap acts as a final
mixing chamber.
Pressure drop across
orifices provides final
atomization.
Stage Two:
Focused stream
impacts the target bolt
forcing additional
mechanical break-up.
Stage One:
Gas and Liquid
converge at the
annulus allowing high
velocity air to shear the
liquid column.
Common factors affecting
molten sulfur atomization
• Plugged Nozzles
• Spray Atomization
— Sulfur Carryover
• Turndown
• Gun Design
— Sulfur temperature consistency
— Steam migration into sulfur line
Nozzle Pluggage
• “Carsul” or other contaminants in the molten sulfur can
buildup and plug nozzle orifices. These unwanted particles
can be of different sizes, so maximizing the free passage
for a particular type of nozzle is critical.
• Particulates can harden at the exit orifice from residuals
during low flow or shut-down procedures.
Spray Atomization
• Atomization is ‘Key’ to successful and proper combustion.
• If the molten sulfur droplets are too large, they do not
vaporize in time and can carry over and cause problems
downstream.
• It is important to have the sprayed droplet sized correctly
so that the burner is run most efficiently.
• Computational Fluid Dynamics (CFD) is an excellent tool
to model optimum droplet size.
Turndown
• A large turndown of the nozzle(s) flow rate is required for
startup and low production times and also to accommodate
peak production.
• Can be achieved by:
— Adding or removing guns
— Adjusting operating pressure of the guns / nozzles
• Greater Turndown AND producing smaller droplets can be
achieved with two-fluid nozzles.
Gun Design
• Allow for thermal expansion and to withstand temperature
loading without bending.
• Steam recirculation for tight control of molten sulfur
temperature and associated physical properties
• Design criteria should stipulate that proper testing and
validation is performed and welders are properly trained.
• Critical that each pathway (molten sulfur, atomizing
medium, jacketing steam) are isolated from each other.
Injector Design
Hydraulic Sulfur Gun
Sulfur-Burning Injector 53686-001
Injector Design
Two-Fluid Sulfur Gun
Increase in Surface Area
Mass transfer is proportional to the droplet surface area!
100 µm
150 µm
200 µm
250 µm
300 µm
400 µm
500 µm
2012 P&P: Crude/Vacuum Distillation & Coking
Atomization Mechanics
• Primary Break-up
—Conical Sheet
Atomization Mechanics
• Secondary Break-up
—Droplet Break-up
Series of photos showing “bag break-up” of a liquid drop ( Courtesy: Laurence
Livermore National Laboratories, USA)
Source: University of Darmstadt, Germany
Are all nozzles created equal?
Furnace CFD Set-up
Main Inlet
Secondary Inlets
•
•
•
•
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• Air
• ṁtotal = 1 kg/s
• T = 122ºC
Air
Q = 308,000 Nm3/hr
ṁ = 113.9 kg/s
T = 122ºC
Poperating = 11 barg
Side View
Outlet
Tout ~ 1160ºC
Injections
• (6x) 53686-001 injectors with 1/2BA309SS70 WhirlJet® nozzle
• Liquid sulfur
• Qtotal = 29 m3/hr
• ṁtotal = 14.6 kg/s (2.4 kg/s per nozzle)
• T = 132ºC
Top View
Temperature Profiles
Temperature
(°C)
2000
Injection Planes
1075
150
T OUT = 1434 (°C)
Species Content (Sulfur)
Mass Fraction
Sulfur
.063
.032
Full Combustion Prior to
Outlet
.000
Sulfur Combustion Prior
to Baffle Wall
Species Content (Oxygen)
Mass Fraction
Oxygen
.063
.032
.000
Oxygen Depleted Prior to
Baffle Wall
Spray Visualization
Furnace CFD with FloMax
nozzles
Injection Parameters
2.5 m
Liquid: Molten Sulfur
units
Flomax® FM5A
Liquid Flow Rate
lpm
80.5
Liquid Mass Flow Rate
kg/s
2.44
Liquid Temperature
°C
132
Droplet Velocity
m/s
35
°
55
DV0.01 - Minimum
μm
11
DV0.50 - Average
μm
66
DV0.99 - Maximum
μm
144
-
2.4
Per nozzle
Spray Angle
N (RR spread parameter)
Temperature profile
Temperature
(°C)
2000
1075
150
T OUT = 1547 (°C)
Species Content (Sulfur)
Mass Fraction
Sulfur
.063
.032
Full Combustion Prior to
Outlet
.000
Sulfur combustion not
complete prior to baffle
wall
Species Content (Oxygen)
Mass Fraction
Oxygen
.063
.032
.000
Oxygen Depleted Prior to
Baffle Wall
Secondary Air Imbalance
in Oxygen
Spray Visualization
CFD Conclusions
Velocity
Wall Impingement
• Good alignment with velocity
contours of inlet air - Hydraulic
• Impingement with base of
combustion chamber - Hydraulic
• Poor alignment with velocity
contours of inlet air - Hydraulic
• No impingement with base of
combustion chamber – Dual Fluid
In Summary…
• Begin with the end in mind!
• Nozzle wear affects spray droplet
performance.
• Think in terms of drop size
requirements.
• Use CFD when many factors
influence the spray.
• Contact Spraying Systems Co.
early to help solve your spray
application.
Thank You!