Wood pulp, pellets

The Code of Safe Practice for Solid Bulk Cargoes (COS) recognizes that certain solid materials transported in large volumes present particular hazards due to their extreme bulk that are not present when shipped in smaller quantities or when packaged. These hazards are maximized when transported in the cargo space of ships without any intermediate containment. 

Certain cargo can shift during transportation if improperly stored, or it may cause structural damage to the ship. These include stone chips and pebbles, some ores and minerals, sands, etc. Some may harden to solids on exposure to moisture. 

Through a combination of existing moisture content, moisture buildup, and small particle size, cargoes may liquefy and become viscous fluids. Vibration and the motion of transportation will aid mixing and cause instability, particularly in bad weather, possibly to the point of capsizing the ship. Materials prone to liquefaction include mineral concentrates, other fine particulates, and cargoes already high in moisture such as fish and peat. 

Coal emits methane and hydrogen gas and carbon monoxide on oxidation. Self-ignition is also possible. 

Direct reduced iron, produced from the reduction of iron oxide, can react with air and moisture to produce hydrogen gas and heat. Ferrophosphorus is an iron and phosphorus alloy (18 to 25% phosphorus) used to adjust phosphorus concentration in steel. 

---

Wood pulp pellets, see also Solid Bulk Materials, p.221... 

Wood products such as sawdust, woodchips, and wood pulp pellets oxidize leading to self-heating, depletion of oxygen, and the buildup of carbon dioxide. 

It should be emphasised that many figures used are average values and that the variations are large. For instance, a wood fuel (pellet) manufacturer located close to a pulp industry most certainly docs not pay the raw material prices used in the assessment. Nor does a biofuel producer pay the power and steam prices when located close to a utility company (using wood fuel). In these cases, co-production is so intimate with backpressure steam, milling, etc., that it is hard to calculate even a rough figure on the specific costs. 

For the pellet manufacture as well as the pyrolysis unit a raw material intake of 100.000 tons of dry substance wood per year is assumed. The amount is available within a transportation distance of 100 km in many places in Sweden. At present most of the wood fuel manufacturing is supplied with raw material from forest industries pulp industry, saw mills, etc. Residues and waste products may be obtained in a range of prices and only a very minor part of the potential raw material from forestry is actually collected today. 

As far as possible, the costs are quoted om data valid for today s activities in Sweden. Some 20 wood pellet plants produce three hundred thousand tons of biofuel for commercial use mainly in utility cortqianies. The reason for this is the CO2 tax in Sweden laid on all fossil fuels, The total use of wood fuel in Sweden is about 1 million tons or 5 TWh, excluding the use of black liquor in the pulp industry and other similar utilisations. The issue about CO2 taxation on fossil fuels in Sweden is here left out of the discussion although that, of course, forms the basis for the situation. 

---