Chemistry of inorganic compounds – Sulfur or compound thereof – Oxygen containing
Patent
1997-06-03
2000-04-04
Dunn, Tom
Chemistry of inorganic compounds
Sulfur or compound thereof
Oxygen containing
422160, 422161, 422164, 423539, 423533, 423532, C01B 1754
Patent
active
060457708
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to methods and apparatuses for generating gaseous sulfur dioxide by combusting sulfur, and more particularly, to a method and apparatus for generating gaseous sulfur dioxide by combusting a granulated sulfur or emulsoid sulfur feedstock.
BACKGROUND ART
Sulfur dioxide is used as an intermediate in a number of different applications, including sulphonation, the generation of sulfuric acid, and to produce sulfur trioxide in electrostatic flue gas conditioning systems which use sulfur trioxide as a flue gas conditioning agent. Electrostatic flue gas conditioning systems are used to condition the exhaust flue gas of coal burning systems, such as coal fired electric generating systems, to enhance the efficiency of the electrostatic precipitator in removing particulate matter, such as fly ash, from the flue gas. Typically, in an electrostatic flue gas conditioning system, elemental sulfur is combusted or burned to generate sulfur dioxide (SO.sub.2). The SO.sub.2 is then catalyzed to convert it into sulfur trioxide (SO.sub.3). The SO.sub.3 is then injected into an electrostatic precipitator to condition the flue gas passing therethrough to enhance the efficiency of the electrostatic precipitator in removing particulate matter from the flue gas. Such a SO.sub.3 flue gas conditioning system is disclosed in U.S. Pat. No. 5,032,154.
Heretofore, elemental sulfur has been used as a source of sulfur which is combusted to generate SO.sub.2. Elemental sulfur is sulfur in its molten state. While it is inexpensive and does not readily burn, it has a number of characteristics which make it difficult to handle and store.
Elemental sulfur is delivered molten at about 280.degree. F. and must be kept at or near this temperature for successful pumping and handling. The viscosity of sulfur varies greatly with temperature. Below about 260.degree. F. the viscosity of sulfur increases quickly so that it can no longer be pumped by conventional means. Above about 300.degree. F., sulfur polymerizes into a toothpaste-like consistency and again cannot be pumped by conventional means. Elemental sulfur also has trace amounts of hydrogen sulfide which must be vented to atmosphere. Elemental sulfur also sublimates (changes from a solid to a gas and back to a solid) so that all elemental sulfur storage equipment must be steam jacketed to prevent sulfur crystal accumulations.
For these reasons, elemental sulfur storage and handling systems must be carefully designed to keep the elemental sulfur molten by keeping it within a very narrow temperature range of 270.degree. F.-290.degree. F. SO.sub.3 flue gas conditioning systems which use elemental sulfur as the feedstock typically store the molten elemental sulfur in insulated steel tanks or concrete pits. This storage vessel is heated, usually by steam coils installed in the bottom of the storage vessel. The steam coils are typically formed in a U-shape so condensate is formed in the coils as the steam cools. Thus, the elemental sulfur storage vessel must have provisions for a steam supply and for condensate disposal to a drainage facility.
Elemental sulfur storage vessels are also exposed to attack from small quantities of sulfuric acid which forms on the surface of the sulfur. Although rare, this occasionally necessitates repairs which are costly, time consuming, and carry the risk of fire.
When the elemental sulfur is pumped from the storage vessel to the sulfur furnace, where it is combusted to form SO.sub.2, its temperature must be kept within the above described narrow range of 270.degree. F.-290.degree. F. Consequently, the elemental sulfur is typically pumped through steam jacketed piping with close temperature control maintained. To maintain the elemental sulfur at the proper temperature throughout the steam jacketed piping, steam must typically be introduced at several points and condensate must also be drained from several points. Steam jacketed sulfur piping lines must also allow for pipe expansion. As a result, steam jacketed sulfur piping lin
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Batttles Richard L.
Duncan, deceased Kent S.
Lentz Michael J.
Woracek David L.
Dunn Tom
Fowler, II Russell E.
Taylor Jay G.
Wilhelm Environmental Technologies
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