Sulfur nozzles

Position of sulfur nozzles. For best results, the spray nozzle header is located parallel to the axis of the sulfur-coating drum. The nozzles in the header are 8 in. apart on centerline. The header is located so each nozzle is spraying vertically down 4% in. onto the fastest moving section of the rolling bed. If the nozzles are placed farther away, the sulfur dust loading in the drum is increased and the quality of the product is decreased. Increasing the spray distance beyond about 8 in. from the bed is both impractical and hazardous as sulfur explosions may occur if... 

Position of the sulfur nozzles. For best results, the nozzles are oriented to spray sulfur perpendicularly onto the falling curtain of urea at a point 2 in. above the bottom of the curtain. The distance between the nozzles and the curtain is 5% in. The nozzles in the header are 7% in. apart. 

Number of sulfur nozzles. The number of sulfur nozzles should be minimized. Four nozzles/ton of production/hr appear to give optimum results. 

In any procedure involving the handling of molten sulfur, the lines and spray nozzles must be steam-jacketed, and steam pressure must hold the molten sulfur within the range of 135—155°C, where its viscosity is at a minimum. Above 160°C, the viscosity rises sharply, and at 190°C its viscosity is 13,000 times that at 150°C. 

Spent Acid or Burning. Burners for spent acid or hydrogen sulfide are generally similar to those used for elemental sulfur. There are, however, a few critical differences. Special types of nozzles are required both for H2S, a gaseous fuel, and for the corrosive and viscous spent acids. In a few cases, spent acids maybe so viscous that only a spinning cup can satisfactorily atomize them. Because combustion of H2S is highly exothermic, carehil design is necessary to avoid excessive temperatures. 

A variation of the n on regen erabi e absorption is the spray dry process. Time slurry is sprayed through an atomizing nozzle into a tower where it countercurtendy contacts the flue gas. The sulfur dioxide is absorbed and water in the slurry evaporated as calcium sulfite-sulfate collects as a powder at the bottom of the tower. The process requires less capital investment, but is less efficient than regular scmbbing operations. 

Feedstocks. Feedstocks are viscous aromatic hydrocarbons consisting of branched polynuclear aromatics with smaller quantities of paraffins and unsaturates. Preferred feedstocks are high in aromaticity, free of coke and other gritty materials, and contain low concentrations of asphaltenes, sulfur, and alkah metals. Other limitations are the quantities available on a long-term basis, uniformity, ease of transportation, and cost. The abiUty to handle such oils in tanks, pumps, transfer lines, and spray nozzles are also primary requirements. 

The hydrocarbon gas feedstock and Hquid sulfur are separately preheated in an externally fired tubular heater. When the gas reaches 480—650°C, it joins the vaporized sulfur. A special venturi nozzle can be used for mixing the two streams (81). The mixed stream flows through a radiantly-heated pipe cod, where some reaction takes place, before entering an adiabatic catalytic reactor. In the adiabatic reactor, the reaction goes to over 90% completion at a temperature of 580—635°C and a pressure of approximately 250—500 kPa (2.5—5.0 atm). Heater tubes are constmcted from high alloy stainless steel and reportedly must be replaced every 2—3 years (79,82—84). Furnaces are generally fired with natural gas or refinery gas, and heat transfer to the tube coil occurs primarily by radiation with no direct contact of the flames on the tubes. Design of the furnace is critical to achieve uniform heat around the tubes to avoid rapid corrosion at "hot spots."... 

Up to 5 kg of gunpowder mixture comprising saltpetre (10) charcoal (2) and sulfur (1) is packed into the pine cylinder where a blasting hole (nozzle) is bored at the bottom of the cylinder. 

For scrubbing of sulfur dioxide and a large portion of catalyst fines, a countercurrent spray tower with a multiple stage nozzle system is typically applied. The WESP is applied after the scrubber section to remove the residual particulate matter with a... 

In fuel combustion systems, S02 and S03 can form upon the burning of fuel sulfur. When sulfur oxides combine with water vapor, acids form. This problem of acid formation and accumulation is a known phenomena and usually occurs under low-speed and load operating conditions. The acids which condense on fuel system components can initiate corrosion of valves, piston rings, and fuel injector nozzles. 

Large sulfuric acid plants are based on spray burners, where the sulfur is pumped at 1030—1240 kPa (150—180 psig) through several nozzles into a refractory-lined combustion chamber. An improved nozzle, resistant to plugging or fouling, has been introduced (256). The combustion chambers are typically horizontal baffle-fitted refractory-lined vessels. The largest plants in fertilizer complexes bum up to 50 t/h of sulfur. 

One of the major results Berman et al. obtained is that the mole ratio of Ca in the absorbent to S in the flue gas has the most important effect. The experimental results for the influence of the Ca/S ratio on the sulfur-removal efficiency, jjs, at different concentrations of C02 in the flue gas are shown in Fig. 7.7. These data were obtained in a reactor with two co-axial cylinders the experimental conditions were flue gas flow rate Vo = 0.001 m3-s 1, diameter of Cylinder I in the reactor D, = 0.06 m, diameter of flue gas exit of the nozzle d = 10 mm, clearance between Cylinders I and II A2 = 5 mm. The results in Fig. 7.7 show the significant influence of C02 in flue gas on the sulfur-removal efficiency %. The reason for this is clear C02 reacts with the absorbent Ca(OH)2, too ... 

In the range of 7 to 20 m s 1 of the flue gas flow exit velocity from the nozzles, the sulfur-removal efficiency increases as the velocity increases, but the tendency to increase gradually becomes weaker. 

The results of the comparative experiments on the influence of nozzle placement are listed in Table 7.6. Obviously, all four sets of experiments yielded the same results the sulfur-removal efficiencies with the nozzle placed at Point A were lower than those with the nozzle placed at Point B represented in Fig. 7.9. The reason for this was discussed in Section 7.5.1.3. These results show that the repositioning of the nozzles from Point A to Point B is reasonable and efficient. 

Sulfur-removal efficiencies with nozzles at different positions... 

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