Understanding Spray Technology to Optimize Sulfur Burning

Transcription

1 Understanding Spray Technology to Optimize Sulfur Burning Presenters: Chuck Munro Dan Vidusek

2 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: headers injectors spray controls spray research & testing

3 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

4 Hydraulic Atomizer Types Hollow Cone Full Cone Flat Spray

5 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

6 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

7 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 LIQUID GAS

8 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.

9 Common factors affecting molten sulfur atomization Plugged Nozzles Spray Atomization Sulfur Carryover Turndown Gun Design Sulfur temperature consistency Steam migration into sulfur line

10 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.

11 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.

12 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.

13 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.

14 Injector Design Hydraulic Sulfur Gun Sulfur-Burning Injector

15 Injector Design Two-Fluid Sulfur Gun

16 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

17 Atomization Mechanics Primary Break-up Conical Sheet

18 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

19 Are all nozzles created equal?

20 Furnace CFD Set-up Main Inlet Air Q = 308,000 Nm 3 /hr ṁ = kg/s T = 122ºC P operating = 11 barg Secondary Inlets Air ṁ total = 1 kg/s T = 122ºC Side View Outlet T out ~ 1160ºC Injections (6x) injectors with 1/2BA- 309SS70 WhirlJet nozzle Liquid sulfur Q total = 29 m 3 /hr ṁ total = 14.6 kg/s (2.4 kg/s per nozzle) T = 132ºC Top View

21 Temperature Profiles Temperature ( C) 2000 Injection Planes T OUT = 1434 ( C)

22 Species Content (Sulfur) Mass Fraction Sulfur Full Combustion Prior to Outlet.000 Sulfur Combustion Prior to Baffle Wall

23 Species Content (Oxygen) Mass Fraction Oxygen Oxygen Depleted Prior to Baffle Wall

24 Spray Visualization

25 Furnace CFD with FloMax nozzles 2.5 m Injection Parameters Liquid: Molten Sulfur Per nozzle 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 Spray Angle 55 D V Minimum μm 11 D V Average μm 66 D V Maximum μm 144 N (RR spread parameter) - 2.4

26 Temperature ( C) 2000 Temperature profile T OUT = 1547 ( C)

27 Species Content (Sulfur) Mass Fraction Sulfur Full Combustion Prior to Outlet.000 Sulfur combustion not complete prior to baffle wall

28 Species Content (Oxygen) Mass Fraction Oxygen Oxygen Depleted Prior to Baffle Wall Secondary Air Imbalance in Oxygen

29 Spray Visualization

30 CFD Conclusions Velocity Good alignment with velocity contours of inlet air - Hydraulic Wall Impingement 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

31 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.

32 Thank You!