Additives, petroleum processing

Inhibitors The use of various substances or inhibitors as additives to corrosive environments to decrease corrosion of metals in the environment is an important means of combating corrosion. This is generally most attractive in closed or recirculating systems in which the annual cost of inhibitor is low. However, it has also proved to be economicaUv attrac tive for many once-through systems, such as those encountered in petroleum-processing operations. Inhibitors are effective as the result of their controlling influence on the cathode- or anode-area reactions. 

The technology cannot be used to treat nonvolatile compounds, lubrication oils, and heavy end products from petroleum processing except when the technology is configured for bioventing with air injection and nutrient addition. 

The use of various substances as additives to process streams to inhibit corrosion has found widespread use and is generally most economically attractive in recirculation systems, however, it has also been found to be attractive in some once-through systems such as those encountered in the petroleum industry. Typical inhibitors used to prevent corrosion of iron or steel in aqueous solutions are chromates, phosphates, and silicates. In acid solutions, organic sulphides and amides are effective. 

Since this estimated share pattern was derived mainly from projection of trends (particularly long term trends), it seems appropriate to focus on oil and speculate as to how possible future events might alter its forecast future role. Events related to pollution control tend to indicate increases in petroleum demand. The use of lead free gasoline, for instance, requires additional refinery processing, which in turn consumes more petroleum fuel. Increasingly tighter controls on sulfur dioxide emissions from thermal-electric plants will cause a shift from coal to low sulfur fuel oil if there is no economic flue-gas desulfurization to cope with coals sulfur content. 

EPA) to aid in registering chemicals under the federal Toxic Substances Control Act (TSCA) of 1976. CAS numbers are assigned to generic refinery process streams, such as kerosene and lube base stocks, that contain no additives. Petroleum products containing additives are termed "mixtures" by the TSCA and, as such, do not have CAS numbers. All chemical substances used in such mixtures are assigned CAS numbers and must be listed with the EPA by the refiner or the additive supplier. 

An additional problem in processing of shale oil compared with petroleum processing is the presence of appreciable quantities of arsenic in shale oil. Arsenic can be a poison for hydrodenitrification catalysts (19). Various pretreatment steps, such as contacting with sodium hydroxide (19) or using a catalytic guard bed (20) or noncatalytic heat treatment (21), have been proposed to remove the arsenic prior to hydrodenitrification. 

The worldwide exploration and shipment of crude oil and petroleum products have led to a number of catastrophic environmental disasters. A wealth of information exists on these events however, long-term consequences are poorly understood. In addition, the processing and utilization of coal and petroleum fuels invariably lead to low levels of pollution in the terrestrial and marine environment by a variety of molecules including polycyclic aromatic hydrocarbons (PAHs). Pollution occurs at different levels which can either be acute or chronic. TTie effects of the latter are the most difficult to discern. 

Furthermore, additional processes are required in order to provide the petroleum processing units with steam, electric power and cooling water that are needed for these units to function. In modern refinery complexes, the energy consumption is low (lower than 5% of the crude oil throughput). Water consumption is low as well (below 1 m3 per ton of crude oil). 

The distillation tower is the most important equipment used in rectification units. The different types of rectification towers and schemes have been described already in the preceding sections. In addition to towers, there are also other major items of equipment used in the rectification unit. These are essentially units used for heat transfer. Heat exchangers play a very important role not only in rectification units, but also in petroleum processing as a whole. All the heat exchangers used in the petroleum industry can be classified as follows ... 

Field practice shows that in order to sustain in situ combustion, one must inject into the bed at least, 400,000-440,000 m of air per day under pressures ranging from 75 to 250 kg/cm, depending on specific parameters of the petroleum reservoir. In this process, the air consumption per one ton of additional petroleum produced from the reservoir can range anywhere fiom 850 to... 

We depend on burning fossil fuels (coal, natural gas, or petroleum) for energy. We burn coal and natural gas to produce electricity, we burn gasoline in the internal combustion engine, and we burn natural gas, oil, wood, and coal to heat homes. In addition, industrial processes burn fuel to produce heat. As a result of all this burning of fossil fuels, the carbon dioxide level in the atmosphere has risen from 318 parts-per-million (ppm) in 1960 to 362 parts-per-million (ppm) in 1998. (For a discussion of the concentration unit ppm, see Chapter 11.) The excess carbon dioxide has led to an increase of about a half-degree in the average temperature of the atmosphere. 

In actual practice, heat-transfer surfaces do not remain clean. Dirt, soot, scale, and other deposits form on one or both sides of the tubes of an exchanger and on other heat-transfer surfaces. These deposits form additional resistances to the flow of heat and reduce the overall heat-transfer coefficient U. In petroleum processes coke and other substances can deposit. Silting and deposits of mud and other materials can occur. Corrosion products may form on the surfaces which could form a serious resistance to heat transfer. Biological growth such as algae can occur with cooling water and in the biological industries. 

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