As a technological entrepreneur, after years of poring through scientific and technical literature for a versatile, adaptable, state-of-art waste remediation platform, I unexpectedly discovered a fascinating body of work which asserts that global warming, human-induced climate change and other environmental impacts can to some extent be averted through a comprehensive, global effort to use sulphur as an ancillary fuel. Is this notion feasible?
It is valid to say that aside from carbon and hydrocarbons, sulphur is the only other naturally-occurring material from which energy can be harnessed by combustion. However, the utilization of sulphur for direct heat energy generation is an idea very alien to the power engineering community, which traditionally identified it in power production as an undesirable source of pollution and corrosion. Sulphur dioxide (SO2), a product of sulphur combustion, when dissolved in water droplets forms acid and when discharged to environment interacts with other gases and particles in the air to form sulphates and other products that can be harmful to people and the environment. Therefore, the combustion of sulphur has been limited to sulphuric acid production.
Furthermore, in contrast to other liquid fuels, sulfur does not have a light fraction and has a rather high boiling point (450° C). It has a greater heat of evaporation, surface tension, ignition temperature, and specific gravity, but a lower heat of combustion than, for example fuel oil. Sulfur also loses out to fuel oil with regards to conditions for spraying because of the low-pressure drop across the spray jet due to its higher viscosity and surface tension.
In addition, sulphur vapor constitutes a dissociating system consisting of all molecules from S2 to S8 in temperature- and pressure-dependent equilibria and the sulphur enters the oxidation reaction only as molecule S2, the "diatomic sulphur" a predominant species in sulphur vapor at temperatures above 600° C. Therefore, in the conventional sulphur burner more than 60% of the heat reaction (about 9,400 kJ/kg S) liberated in the combustion of sulphur to sulphur dioxide is theoretically required for preheating the air and sulphur and for evaporation and decomposition of the sulphur. Even so, a sulphuric acid plant produces a prodigious amount of high-level waste heat and nearly all of the high-level waste heat is utilized to produce electricity through a steam turbo/generator.
Be that as it may, there are advantages in sulphur properties that hardly can be ignored. To begin with, is has the capability to attain a very high temperature when burning sulphur in oxygen. The theoretical temperature of adiabatic burning of sulphur vapour in oxygen taking in to consideration dissociation process is about 3000-3500° C. However, burning diatomic sulphur (S2) in pure oxygen in stoichiometric quantities would produce an even higher temperature - more than 5,000° C! To makes possible to burn sulphur directly in a stream of oxygen sulphur can be evaporate by bubbling oxygen through molten sulphur at a temperature at which the sulphur boils, which ensures maximum evaporation of sulphur. This industrial proven method is called submerged combustion.
In addition, sulphur dioxide (SO2), if dry, is not corrosive and, in contrast to carbon dioxide, can be relatively easily reduced by carbonyl sulphide (COS) to yield carbon dioxide (CO2) in a form that can readily be captured, in addition to forming sulphur in a potentially 100% conversion process. Lastly, if the sulphur compound COS is generated by conversion of CO2 from power plants, industrial facilities or the atmosphere and utilised as an intermediate a hybrid correlation energy system can be designed whereby energy is obtained from two different prime sources, such as coal and sulphur, without detrimental atmospheric impact of sulphur oxides. It is important to note that CO2 conversion is a proven commercial process. Also, every element in this proposed system has passed beyond the laboratory bench; most are already implemented somewhere at demonstration and/or full industrial scale.
As a technological entrepreneur I committed myself to the specific technology which can provided a versatile, adaptable, state-of-art waste remediation platform for processing most common waste stream within one integrated system. To provide a versatile, adaptable, state-of-art waste remediation platform I obtained Battelle Memorial Institute license of vitrification technology to effectively treat and dispose of municipal waste materials without creating undue environmental contamination. In the same time, I initiates research on application vitrification technology for treatment of phosphogypsum (PG), a by-product of processing phosphate ore into fertilizer with sulfuric acid. It is radioactive due to the presence of naturally occurring uranium and radium in the phosphate ore. With two of US Department of Energy's (DOE) Pacific Northwest National Laboratory (PNNL) vitrification technology leading researches, Chris Chapman and Richard Peters, I initially obtained research grants from Florida Institute of Phosphate Research (FIPR) to investigate the manufacture of vitrified glass products from PG. Manufacture was successfully demonstrated on a pilot scale; however, the economics of the process would not justify commercial implementation due to the energy requirements of the process.
A subsequent grant from FIPR addressed the energy issue by attempting to recover sulphur in the process that could be utilized to drive the process. A process was developed whereby energy co-produced in sulfuric acid production could be substantially increased. During these investigations it became apparent that the energy values available through sulfur combustion are potentially enormous. Current energy production from sulfur combustion is limited to co-production at sulfuric acid production facilities, which provides sufficient energy to power the phosphate fertilizer production complex. Presently the only large scale industrial practice that can utilize sulphur dioxide is in the production of sulphuric acid. In fact, more than 90% of the world’s consumption of sulphur is dedicated to the production of sulphuric acid, and the vast majority of this is produced by the global phosphate fertilizer industry which employs sulphuric acid in the acidulation of phosphate rock for phosphoric acid production.
There are vast resources of sulphur, both natural, and by-product, available in the world beyond the current requirements of industry. It was thought that if an alternative means of dealing with the products of sulphur combustion could be found, energy derived through sulphur combustion could be freed from its dependence on sulphuric acid production, thereby unlocking the key to the widespread utilization of sulphur as a source of energy.
Methods and Systems for Transporting Sulphur as a COS, patent: CA2791963.