Sulfur presents a unique challenge for oil and gas producers. Sulfur compounds occur naturally in both crude oil and raw natural gas. The concentration of sulfur depends on the wells where the oil or gas is gathered. Since hydrogen sulfide is highly corrosive and toxic, these sulfur compounds must be reduced or removed during refining or processing. This process is called sulfur recovery or sweetening.
Fortunately, the byproduct from sulfur recovery, elemental sulfur, can be re-purposed and sold. It is primarily used in the production of sulfuric acid and production of phosphate fertilizer, but sulfur is also used in many household products such as detergent, paint, carpet and even cosmetics.
Most sulfur recovery takes place through the Claus process. A sulfur recovery unit removes as much as 99.9 percent of hydrogen sulfide in natural gas or crude oil to meet applicable government regulations. Liquid sulfur is recovered from the Claus condensers.
Owner/ operators need a dependable sulfur recovery unit to minimize downtime at the refinery or processing facility. If this facility is not functioning correctly, it will shut down the entire operations. Sulfur must be removed from natural gas or crude oil before it can continue down the supply chain. Regulations require the removal of sulfur for environmental and health reasons. These mandates are the primary driver for sulfur recovery. The ability to market the byproduct is essentially an added bonus.
Molten Sulfur Storage Options
Once the sulfur is in the molten form, more strategic decisions must be made. In the liquid form, sulfur can be stored in aboveground storage tanks, aboveground surge vessels or sulfur pits/vats. Molten sulfur tanks require special design considerations for heating, due to sulfur’s unique temperature requirements to remain in the molten state, and to address the corrosive nature of sulfur. Sulfur transports used in molten sulfur service must remain in sulfur service for the remainder of it’s effective life-cycle. Sulfur must be molten before being consumed in the sulfuric acid process; therefore, offering potential challenges by potentially viable options.
Solid Sulfur Storage & Transportation
Liquid sulfur can also be solidified into small pellets that can be handled as dry bulk. Storing sulfur in this way makes loading and unloading sulfur within the facility easier and also opens up transportation options for sulfur as it travels to market. Solid sulfur can be stored inside or outside depending on environmental requirements and conditions, and transported in any vessel to it’s final destination.
Prilled sulfur can easily travel on bulk collier ships in sizes ranging from 10K to 50K depending on origin and destination ship size restrictions.
Solid Sulfur Block Storage
Finally, sulfur can be stored in large, solid blocks. This can be a good option if sulfur prices drop or the infrastructure to transport sulfur is not in place. This option is also the lowest cost solution as molten sulfur is transported via pipe to the blocking area, distributed across a large rectangular area surrounded by forms. As the sulfur solidifies, large blocks of solid sulfur are created. These blocks are typically used for emergency purposes; however, areas in the world with transportation logistic challenges have millions of tons in blocks today.
Solid Sulfur Melting
As mentioned, solid sulfur is the world’s preferred method for transportation. Once at the final destination, the sulfur must be melted and stored in the molten phase before being consumed in the downstream process. Various sizes of sulfur melters and filtration processes are available to meet the operation demand.
There are many options for sulfur byproduct. The positives and negatives of each option must be carefully weighed against operational goals. Whether you are looking to simply store elemental sulfur or take it to market, there is sure to be a solution that will complement your processing or refining plans.