Sandmeyer Steel Company’s stainless steel and nickel alloy plate and plate products are used extensively in the ethanol, biodiesel, and biogas industries.
304L/304 and 316L/316 are capable of handling most of the corrosive conditions encountered in the fabrication of biofuels process equipment. However, in specific areas of the plants requiring superior corrosion resistance, duplex, superaustenitic, and nickel alloys are specified. Some high temperature applications in the ethanol process also require special stainless or nickel alloys.
The pre-treatment phase of the ethanol process is more corrosive than the balance of the plant. In those areas, duplex 2205, super duplex 2507, superaustenitic 904L, and SSC-6MO and nickel alloy C-276 are used. Alloys 317L/317, and lean duplex LDX-2101® (large tanks) are also used in ethanol plants.
Biodiesel plants are usually designed for a blend of feedstocks. As in the ethanol process, 304L/304 and 316L/316 are the most widely used grades in biodiesel plants. Duplex 2205 and 2507 are used where weak hydrochloric or sulfuric acids are present in the pretreatment systems and in the washing and glycerin removal process. Centrifuges used in biodiesel plants can be made of 317L/317 and 2205, and large tanks are fabricated out of LDX-2101®.
Biogas is produced by the anaerobic digestion or fermentation of biomass, energy crops, green waste, manure, sewage, and municipal waste. It is considered moderately corrosive. However, during the process, hydrogen sulfide and ammonia are formed in the digester. Also some of the feedstocks contain chlorides which will also increase the corrosive levels.
304L/304 and 316L/316 are specified in the majority of the equipment in the biogas process. 904L will be used in areas of the plant where hydrogen sulfide is present. In the section of the plant that is acidic with high chloride levels, SSC-6MO is used.