Clean energy – dimethyl ether
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Dimethyl ether, also known as methyl ether and abbreviated as DME, is a colorless gas with a slight ether-like odor. Its relative density as a gas at room temperature is 1.592, while its relative density as a liquid is 0.666. The melting point is -141.5 °C and the boiling point is -24.9 °C. The saturated vapor pressure at 20 °C is approximately 0.53 MPa. Its physical properties are very similar to those of liquefied petroleum gas, and it is soluble in water as well as in various organic solvents such as alcohols, diethyl ether, propane, and chloroform. Dimethyl ether is flammable, and its flame emits a slight glow when burning. At room temperature, dimethyl ether has chemical properties such as inertness, non-corrosiveness, non-carcinogenicity, and low toxicity; however, it can decompose into methane, ethane, formaldehyde, and other substances under conditions of radiation or heating. Unlike diethyl ether, dimethyl ether does not form peroxides upon prolonged exposure to air. Dimethyl ether has a lower saturated vapor pressure than liquefied petroleum gas, making it safer for storage and transportation. It also exhibits good combustion properties and high thermal efficiency; there are no residues or black smoke during combustion, and emissions of CO and NO are low. Dimethyl ether can be blended with liquefied petroleum gas, artificial gas, or natural gas for mixed combustion, thereby increasing their calorific value. Dimethyl ether with a purity of ≥99% can be used directly as a fuel alternative to liquefied petroleum gas.
At present, the production of dimethyl ether is also facing difficult times. Dimethyl ether is produced by the dehydration of methanol, and currently the price of methanol is quite high, at over 2,000 yuan per ton; it takes 1.5 tons of methanol to produce 1 ton of dimethyl ether. Meanwhile, the price of liquefied petroleum gas has dropped significantly – on April 10th, the cost of liquefied gas upon arrival at the port was only 3,200 yuan, while the selling price of liquefied gas from domestic refineries was 3,300 yuan per ton. As a substitute for liquefied petroleum gas and gasoline, dimethyl ether lacks competitiveness at present, and its development is hindered by the current economic crisis. This post was last edited by leefun on 2009-4-13 08:37
It seems that there are large-scale projects for coal-to-methanol production these days, so dimethyl ether is still a good option
I wonder what the calorific value of dimethyl ether is; can it be used to blend with fuel oil?