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| Sulphuric Acid on the WebTM | Technology Manual | DKL Engineering, Inc. |
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Knowledge for
the Sulphuric Acid Industry Introduction
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Sulphur is transported both as a solid in bulk and as a liquid in the molten form. Each form has its own special requirements in order to transport sulphur safely, with minimal environmental impact and minimal contamination of the sulphur. Molten Sulphur The key to transporting sulphur in molten form is maintaining its temperature at approximately 140oC. Transport over short distances can be done in well insulated containers. The low thermal conductivity of sulphur minimizes heat loss and helps it to retain heat so it does not solidify. Over longer distances, a heating system is required to maintain the sulphur in the liquid state. A typical semi-trailer for transporting molten sulphur is shown below. The capacity of the tank is approximately 3,800 USGal and is constructed of stainless steel and is insulated.
Standard Molten Sulphur Trailer Where permitted, the amount of sulphur transported per trip can be increased by going to a B-train arrangement. The equipment shown below is a B-train arrangement manufactured by Bedard Tankers and has a capacity of 5,500 Imp. Gal.
5,500 Imp. Gal. Super B-Train (Bedard Tankers) Tank trailers designed for molten sulphur are generally dedicated to hauling molten sulphur. A tank that has just carried molten sulphur cannot be easily cleaned so that the trailer can carry a different commodity on the return trip or to another destination. The result is that the tank is full on the delivery trip but is empty on the return trip. To maximize what is known as "loaded miles", a specially designed tank trailer combines a tank for molten sulphur and a bulk carrier. On one trip, the trailer carries molten sulphur and on the return trip carries a bulk commodity such as fertilizers. This type of trailer is called a backhaul double and is used in the Florida region by fertilizer manufacturers to improve the trucking economics. Backhaul doubles are also used in western Canada but instead of a sulphur/bulk carrier, a sulphur/fuel carrier is used.
Backhaul Double Sulphur can be shipped in either solid or liquid form over long distances by ocean going ships. Solid sulphur can be shipped in virtually any bulk carrier provided care has been taken to thoroughly cleanout the hold. Molten sulphur is transported in specially designed ships equipped with heating systems. Some of the vessels designed to carry molten sulphur are shown in the table below.
Large quantities of molten sulphur are transported by rail. An insulated sulphur railcar loaded with 40 to 70 tonnes of sulphur at 135oC (275oF) will stay molten for 10 to 14 days even in cold climatic conditions. This is possible because of the solidification of a small amount of sulphur on the inner wall of the tank that effectively insulates the remainder of the tank contents. When the tank car arrives at the customer, the car is heated using steam to melt the small amount of solid sulphur on the inner walls before the tank car is unloaded.
Typical Molten Sulphur Rail Car
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