Sulfur-containing fuels

Carbonyl sulfide occurs as a by-product ia the manufacture of carbon disulfide and is an impurity ia some natural gases, ia many manufactured fuel gases and refinery gases, and ia combustion products of sulfur-containing fuels (25). It tends to be concentrated ia the propane fraction ia gas fractionation an amine sweetening process is needed to remove it. 

Sulfur Dioxide Emissions and Control. A substantial part of the sulfur dioxide in the atmosphere is the result of burning sulfur-containing fuel, notably coal, and smelting sulfide ores. Methods for controlling sulfur dioxide emissions have been reviewed (312—314) (see also Air POLLUTION CONTROL PffiTHODS COAL CONVERSION PROCESSES, CLEANING AND DESULFURIZATION EXHAUST CONTROL, INDUSTRIAL SULFURREMOVAL AND RECOVERY). 

Fluid bed boilers have also been applied as a cure to sulfur dioxide air pollution from power plants. Various schemes have been developed in which combustion of a sulfur containing fuel takes place in a fluidized bed of particles which absorb or react with sulfur dioxide. The particles are usually regenerated to recover sulfur, which often has enough by-product value to make a significant contribution to process economics. 

Because economizer tube bundles produce very hot FW within the tubes, they may be subject to serious waterside corrosion and deposition problems, in addition to gas-side dust erosion problems and cold-end acid attack from sulfuric acid (derived from sulfur-containing fuels). 

Kim H, Vohs JM, and Gorte RJ. Direct oxidation of sulfur-containing fuels in a solid oxide fuel cell. Chem Commun 2001 2334-2335. 

Aguilar L, Zha S, Cheng Z, Winnick J, and Liu M. A solid oxide fuel cell operating on hydrogen sulfide (H2S) and sulfur-containing fuels. J Power Sources 2004 135 17-24. 

Historically, the sulfur oxides have long been known to have a deleterious effect on the atmosphere, and sulfuric acid mist and other sulfate particulate matter are well established as important sources of atmospheric contamination. However, the atmospheric chemistry is probably not as well understood as the gas-phase photoxidation reactions of the nitrogen oxides-hydrocarbon system. The pollutants form originally from the S02 emitted to the air. Just as mobile and stationary combustion sources emit some small quantities of N02 as well as NO, so do they emit some small quantities of S03 when they bum sulfur-containing fuels. Leighton [2] also discusses the oxidation of S02 in polluted atmospheres and an excellent review by Bulfalini [3] has appeared. This section draws heavily from these sources. 

Desulfurization of fossil fuels was the subject of an authoritative review by J. B. Hyne (Alberta Sulphur Research Institute). This is a topic of increasing importance as Canada relies more and more on sulfur-containing fuels such as tar sands and heavy oils. Hyne reviewed the present state of the chemistry and technology for both precombustion desulfurization of natural gas and crude oils and postcombustion tailgas clean up of coals and cokes. He clearly identified areas of possible future research such as the high temperature-high pressure chemistry pertaining to in-situ desulfurization processes. 

In the case of sulfur-containing fuels (e.g. coal or oil), SO2 is produced during combustion in the boiler along with minor percentages of SO3 SO2 can further be oxidized to SO3 over the catalyst ... 

Source Any combustion of sulfur-containing fuels. Combustion installations are responsible for 2.9 X 106 t/yr released into the air and 68.3% of the total emissions from industry in Europe. 

Scrubbing of stack gases with limestone. Sulfur-containing fuels are burnt as received, and the S02 is removed by passing the flue gases up a column of wet limestone ... 

Gaseous S02 is created by combustion of sulfur-containing fuels, especially coal. Explain how S02 in the atmosphere makes acidic rain. 

Sulfur dioxide is slowly oxidized in the atmosphere to S03, which dissolves in rainwater to give sulfuric acid. The burning of sulfur-containing fuels is thus a major cause of acid rain (Section 9.9). In the laboratory, S02 is conveniently prepared by treating sodium sulfite with dilute acid ... 

Sulfur dioxide (boiling point, -10°C) is a gas that occurs as a result of the oxidation of sulfur as, for example, during combustion of sulfur-containing fuels. 

These gases evolve from the burning of sulfur-containing fuels from cars and factory chimneys to cause air pollution. On our planet, life can only be possible with clean air. Consequently, we should consider to decrease air pollution. 

The negative side is the formation of damaging air pollutants. Recall that sulfur dioxide, a toxic gas with a choking odor, is formed when sulfur-containing fuels are burned. However, it is sulfur trioxide that causes most of the environmental damage, mainly through the production of acid rain. When sulfur trioxide combines with a droplet of water, sulfuric acid is formed ... 

About 60% of the sulfur produced in the United States comes from the underground deposits of elemental sulfur found in Texas and Louisiana. This sulfur is recovered by using the Frasch process developed by Herman Frasch in the 1890s. Superheated water is pumped into the deposit to melt the sulfur (mp = 113°C), which is then forced to the surface by air pressure (see Fig. 19.16). The remaining 40% of sulfur produced in the United States either is a by-product of the purification of fossil fuels before combustion to prevent pollution or comes from the sulfur dioxide (S02) scrubbed from the exhaust gases when sulfur-containing fuels are burned. 

However, this reaction is very slow in the absence of a catalyst. One of the mysteries during early research on air pollution was how the sulfur dioxide produced from the combustion of sulfur-containing fuels is so rapidly converted to sulfur trioxide in the atmosphere. It is now known that dust and other particles can act as heterogeneous catalysts for this process (see Section 15.9). In the preparation of sulfur trioxide for the manufacture of sulfuric acid, either platinum metal or vanadium(V) oxide (V205) is used as a catalyst, and the reaction is carried out at approximately 500°C, even though this temperature decreases the value of the equilibrium constant for this exothermic reaction. 

With sulfur-containing fuels, attention has to be paid to the acid dew point of the flue gas. Acid dew point in flue gas is shown as a function of sulfur content in the fuel oil in Figure 7. To avoid corrosion in the upper bundles, it has to be ensured that the tube skin temperature is, in all cases, higher than the acid dew point. 

The current generation of catalysts would be sufficient to meet some of the most stringent requirements if sulfur were not present in essentially all hydrocarbon fuels. The combustion of sulfur-containing fuels produces SO2 in the engine exhaust. In high concentrations and for reducing environments, SOj poisons sites on the precious-metal catalysts by forming adsorbed sulfur atoms, which in turn block a portion of the active metal sites and reduce the activity of adjacent metal sites [5]. 

ABSTRACT Calcium-enriched bio-oil (CEB) can be used for flue gas desulfurisation in coal and waste combustion chambers. It is produced by mixing biomass derived fast pyrolysis oil with calcium oxide. The aim of the proposed project is to develop a technology i) to produce calcium-enriched bio-oil with a calcium content of 13 wt,%, and ii) to test the CEB in a combustion chamber by co-firing it with a sufur-containing fuel. In this paper the production method of CEB will be elucidated, and small-scale experiments related to CEB spraying will be presented. Finally, co-combustion experiments of a sulfur-containing fuel with CEB in a small flame tunnel (20 kW, ) will be reported. 

The aim of the present work is the development of a Calcium Enriched Bio-oil (CEB) that it is suitable to be co-fired with a sulfur containing fuel in a combustor to simultaneously reduce SO2 and NO. Where the capture of NO is important, CEB has greater flexibility. Additionally, CEB will reduce the higher N20-concentrations associated with this technology. The data below have been abstracted from the lEA Coal Research publication entitled "Air Pollution Control Costs for Coal-Fired Power Stations (1995). 

Sulfur dioxide is formed whenever sulfur-containing fuels are combusted in air. Sulfur dioxide can lead to the formation of acid rain and is a controlled pollutant in most countries. U.S. 5,196,176, assigned to Paques B.V, describes a biological process for removing sulfur dioxide from a vent gas and converting it to elemental sulfur. Estimate the cost (in /kWh) of using the Paques process to treat the flue gas from a 1000 MW power station that burns Illinois Number 6 coal in pressurized fluidized bed combustors. 

---