Energy consumption treatment

The purpose of chemical processes is not to make chemicals The purpose is to make money. However, the profit must he made as part of a sustainable industrial activity which retains the capacity of ecosystems to support industrial activity and life. This means that process waste must be taken to its practical and economic minimum. Relying on methods of waste treatment is usually not adequate, since waste treatment processes tend not so much to solve the waste problem but simply to move it from one place to another. Sustainable industrial activity also means that energy consumption must be taken to its practical and economic minimum. Chemical processes also must not present significant short-term or long-term hazards, either to the operating personnel or to the community. 

Decrea.sed energy consumption. As mentioned previously, methods of energy conservation are often interrelated and complementary to each other. Energy expenditures associated with the treatment and transport of waste are usually but not always reduced when the amount of waste generated is lessened, while at the same time the pollution associated with energy consumed by these activities is abated. 

Pretreatment of wood with pectinolytic enzymes facilitates the debarking. The energy consumption during debarking of spruce in a laboratory scale debarker is clearly decreased after treatment with Pectinex Ultra (Table 1). Several hours is needed for effective preteatment (Table 2). 

Significant energy consumption and other operating costs are expected. This method of treatment becomes cost-effective when material recovery is significant. 

For a given energy consumption, fuel change is the only way to reduce C02 and SO emissions at source. Fuel switch from, say, coal to natural gas reduces the C02 emissions for the same heat release because of the lower carbon content of natural gas. Fuel change can also be useful for reducing NO, emissions. Once emissions have been minimized at source, then treatment can be considered to solve any residual problems. 

BIOHOCH An aerobic wastewater treatment process. Optimimum reactor design and a proprietary air injection system achieve 50 percent of the energy consumption of similar systems. Fifty systems had been installed worldwide by 1994. Licensed by Brown-Minneapolis Tank and Hoechst-Uhde Corporation. 

The process produces some organic waste derived from the thermal breakdown products of the wood, which is dealt with in a biological treatment facility. Volatile by-products are removed in a scrubber associated with a steam-condensing unit. Energy consumption is 2.8MJ to produce 1 kg of modified wood and the cost of production is about 150 Euros per m, with operational costs of 20 Euros per m. A plant capable of an annual production capacity of 75 000 m would require an initial investment of some 10-15 million Euros. 

A minor part of mined fossil fuels is used as a raw material for the chemical industry (e.g., plastics, synthetic fabrics, carbon black, ammonia, and fertilizers). The major part supplies the energy needs for modem society. Fossil fuels supply about 86% of global primary energy consumption (39% oil, 24% coal, and 23% natural gas), providing energy for transportation, electricity generation, and industrial, commercial, and residential uses (El A 2001). Coal, and to a lesser extent oil, combustion leaves a significant amount of solid waste. The treatment of solid waste from fossil fuel combustion is treated in different chapters of this book. In this chapter we focus on air emissions of fossil fuel combustion, and their impact on human health and the environment. 

Paillard et al. (1988) summarized that 02/UV treatment is not suitable for the removal of aliphatic organohalogen compounds because less energy was required to remove them using air stripping. They found that an energy consumption of about 290-380 Wh m" 3 was required for 90 % removal for unsaturated organohalogen compounds, whereby no optimization was done and could reduce these numbers. 

The gas is then cooled to 30-50 °C and the carbon dioxide is removed by amine absorption or other processes. The remaining impurities - carbon monoxide, methane, nitrogen, argon - are removed in a final pressure-swing adsorption (PSA) step to yield >99.5% pure hydrogen. One of the main problems with this process is that the carbon dioxide is removed by the amine unit as a low-pressure gas. This gas must be compressed to 80 bar to be pipelined for sequestration. This compression step alone requires massive compressors and uses 4—5% of the total power output of the plant. The amine treatment step itself uses even more energy, so the total energy consumption is 15% of the power produced by the plant. 

Calculate the treatment time and the specific energy consumption (kW h/kg COD eliminated). (Cominellis)... 

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