Who knows where I can find information on dimethyl ether as an aerosol?

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DME retrofit plan for fuel boilers 1. Current status of fuel and gas energy in China China’s economy is developing at a rapid pace, and data shows that it has become the world’s second-largest oil consumer after the United States. Its high energy consumption has also made China one of the largest oil importers in the world. According to BP, China accounted for about 30% of the global increase in oil demand in 2007, with daily oil consumption rising by 900,000 barrels. China’s automotive, steel, and chemical industries are all in a period of rapid development, and the upward trend in oil demand will continue. It is foreseeable that China’s oil demand will maintain strong growth in the future. The issue facing us at present is how to overcome the bottleneck posed by oil in our country’s economic development. Against this backdrop, our country’s government and its enterprises have begun to formulate global energy strategies, seeking overseas energy cooperation or acquisition opportunities, as well as expanding into foreign markets through various channels to secure a stable supply of oil. This should be a key priority for Sinopec and indeed our country’s government at this stage. Due to rising oil prices, the operating costs of fuel boilers continue to increase. Among new energy sources, dimethyl ether has a relatively high calorific value and high combustion efficiency; it is a clean and economical green fuel. In areas facing energy shortages, switching from oil to gas can be an effective solution. 2. Combustion properties of dimethyl ether: Dimethyl ether (DME for short) is a flammable gas that can be easily liquefied for storage and transportation. It is in gaseous state at normal temperature and pressure, and in liquid state at normal temperature and a pressure of 0.6 MPa. Dimethyl ether has a slight ether-like odor and very low toxicity. Inhalation or skin absorption of excessive amounts of dimethyl ether can cause **, loss of consciousness, and damage to the respiratory organs. Dimethyl ether has excellent environmental performance characteristics; it is not carcinogenic and does not damage the atmospheric ozone layer. Dimethyl ether is a colorless, easily liquefiable gas, and its flame appears slightly luminous when burning. Dimethyl ether has good miscibility; it can mix with most polar and non-polar organic solvents, such as gasoline, carbon tetrachloride, benzene, chlorobenzene, propylene, and methyl acetate. With the addition of a small amount of additives, it can be mixed with water in any proportion. Dimethyl ether is an oxygen-containing compound with a higher cetane number than diesel; its combustion properties are superior to those of liquefied petroleum gas and diesel. It can be used as both a fuel for vehicles and for domestic use. In recent years, dimethyl ether has begun to be used as a fuel, and some countries around the world have gained a new understanding of its importance. In-depth research and development have been carried out in areas such as dimethyl ether production processes, catalyst preparation, and its various applications. 2.1 Physical and chemical properties of dimethyl ether The main physical and chemical properties of dimethyl ether, methane, propane, and n-butane are shown in Table 1. Table 1 Physical and chemical properties of dimethyl ether compared to methane, propane, and n-butane
Property | Dimethyl ether | Methane | Propane
---|---|---|---
Relative molecular mass | 46 | 16 | 44
Boiling point/°C | -24.9 | -161.5 | -42.1
Relative density | 1.59 | 0.55 | 1.55
Freezing point/°C | -141.4 | -182.5 | -187.7
Vapor pressure at 20°C/MPa | 0.53 | 0.83
Lower heating value in liquid state/(MJ/kg) | 29.8 | 46.34
Lower heating value in gaseous state/(MJ/m³) | 59.3 | 35.90 | 93.24
Lower explosion limit (volume percentage)/% | 3.4 | 5.0 | 2.1
Upper explosion limit (volume percentage)/% | 18.2 | 15.0 | 9.5
Theoretical air volume | 14.28 | 9.52 | 23.80
Auto-ignition temperature/°C | 235 | 540 | 460
Oxygen content (mass percentage)/% | 34.8 | 0 | 0
Combustion air demand index/kcal/m³ of air | 993.5 | 902.2 | 937.2

2.2 Flame propagation speed of dimethyl ether
Table 2 Maximum flame propagation speed of single combustible gases mixed with air
Gas | H2 | CO | CH4 | C3H8 | C4H10 | C2H6O
Maximum flame propagation speed | 2.80 | 0.56 | 0.38 | 0.42 | 0.38 | 0.48
Primary air coefficient at maximum speed | 0.57 | 0.46 | 0.9 | 1.00 | 1.00 | 0.85
Data sourced from “Gas Combustion and Applications” published by China Architecture & Building Press ； Peng Shini et al., Experimental determination of the flame propagation speed of dimethyl ether, Coal Conversion, April 2006, pp. 63-65. 2.3 Analysis of the combustion characteristics of dimethyl ether: As can be seen from the data in the table above, dimethyl ether has a wider explosive concentration range than methane, propane, and butane, as well as a lower auto-ignition temperature; therefore, it is easier to ignite. Furthermore, dimethyl ether itself contains oxygen, resulting in a high combustion air load index; that is, with fans of similar specifications, dimethyl ether can handle a greater combustion load. Dimethyl ether has a faster combustion rate than methane, propane, and butane. Therefore, dimethyl ether is less prone to flameout compared to them. 3 Future development directions of boilers: The continuous rapid economic growth in China, along with the structure and usage of energy sources as well as consumption patterns, are among the main factors contributing to the increasingly severe environmental pollution problems in the country. It is understood that currently, 85% of carbon dioxide, 90% of sulfur dioxide, and 73% of particulate matter across the country are emitted from coal burning; the economic losses caused by carbon dioxide alone in air pollution account for 2.2% of GDP. In the mid-1990s, acid rain and sulfur dioxide pollution in China caused economic losses of over 110 billion yuan in areas such as crops, forests, and human health, which was close to 2% of that year’s gross national product and became a significant factor hindering the economic and social development of the country. Our country’s carbon dioxide emissions rank second in the world, accounting for 13% of the global total. The 1997 Kyoto Protocol did not impose emission reduction or limitation obligations on developing countries; however, in the long term, both developed and developing countries tend to align energy efficiency and environmental standards with trade regulations, as well as to standardize these standards across countries. Looking at the historical development, our country has attached great importance to energy and environmental issues. Gas boilers have been successfully used in power generation and start-up boilers for large-scale power plants; in industrial boilers, gas boilers account for more than 15% of the total number of such boilers. As for domestic boilers, fuel oil boilers are being converted to gas boilers. With the development of more and more new energy fuels, an increasing number of industrial and domestic boilers are being replaced by gas boilers. 4 The necessity of switching from fuel to gas: Influenced by the energy structure, coal-fired boilers account for the vast majority in China. However, these boilers are inefficient, and the emissions they produce cause air pollution, which is not in line with China’s future development goals and plans. At present, our country has become the world’s second-largest oil consumer. The rapid economic development leads to high demand for oil, which results in rising oil prices. The operating costs of fuel boilers are also becoming increasingly unaffordable for users, and some of them are looking for ways to switch from using oil to gas. 5 Advantages of Domestic Oil-to-Gas Conversion Projects: In August 2006, a burner testing facility was established in Shanghai as part of the China Special Equipment Inspection and Research Center. This facility enables high-precision and accurate testing of various aspects related to the performance of combustion equipment. With specialized testing institutions overseeing the performance and exhaust emissions of such equipment, it indicates that China’s combustion equipment industry has reached a considerable level of development. This further promotes the advancement of domestic combustion equipment toward higher efficiency and lower emissions. Looking ahead, over the next 10–20 years, the most notable feature of oil-to-gas conversion projects for combustion equipment in China will be the modification of existing units without the need to purchase new ones. In cases where time is critical, modifications can be carried out directly at the customer’s site. The total cost of such modifications is low, accounting for approximately 30% of the price of a new unit, which is less than 20% of the price of imported European brands. This not only helps customers save on acquisition costs but also shortens the procurement timeline. Generally speaking, the conversion from oil to gas involves mainly the modification of the burner; no significant changes are required to the boiler itself. All that is needed is to replace the transition plate that connects the boiler’s burner outlet. As long as the user installs the gas piping to the boiler room, the entire conversion process is quick and requires low costs. We (domestic suppliers) can make full use of the user’s existing resources; the original model remains unchanged, with only the gas burner and swirler being replaced, as well as additional gas-related components such as a servo control mechanism with cam adjustment. This ensures an accurate ratio between fuel and combustion air, allowing for thorough mixing and combustion of the fuel, **thereby improving the burner’s combustion efficiency. The switching between high and low flame levels is achieved through sliding or proportional regulation, ensuring stable and reliable operation of the burner during ignition and at various flame strengths, without any shocks or vibrations. The gas valve assemblies are selected from internationally renowned brands, and different specifications of valve assemblies can be used according to the various gas pressures provided by the users; as a result, the burner has strong adaptability to fuel pressure. The burner system is equipped with safety protection functions such as low air pressure detection, low gas pressure detection, gas valve leakage detection, and flame detection, providing reliable assurance for the safe operation of the burner. The fuel engines used by users are mostly of the fixed-type two-stage or three-stage design, without cam mechanisms for air distribution; as a result, it is difficult to achieve an accurate ratio between fuel and combustion air. In other words, large air valves are used with low fuel loads, which leads to a high oxygen excess coefficient and reduces the efficiency of the boiler, preventing optimal utilization of resources. On the other hand, the burners used by users are all 7 to 8 years old, or even up to 10 years old; their flame tubes, air distribution devices, impellers, and damper control mechanisms have become severely deformed and scaled. Such factors have a significant impact on the combustion efficiency of these burners, reducing their efficiency by around 5%, or even more. Through theoretical calculations by professional engineering and technical personnel as well as numerous tests, our company is able to carry out modifications that convert fuel engines into gas engines or engines capable of operating on both fuel and gas. We can also provide services for optimizing combustion control and boiler system control. Once the modification is complete, what is presented to the customer is a high-quality, high-performance, brand-new combustion device. Our company has successfully carried out batch modifications for users, and the systems have been operating well; this has helped users save energy and improve their economic efficiency, earning us great favor among them. 6 Technical parameters and economic cost analysis of oil-to-gas conversion: Taking the conversion of a 2 t/h fuel engine into a gas engine in one particular application as an example, the diagram of the fuel-air supply control system is shown in Figure 1, while the data related to gas performance testing and economic analysis are presented in Table 3. Figure 1: Diagram of the fuel-air supply system. Table 3: Test data after converting the fuel engine into a gas engine. Sequence Number, Operating Condition, Gas flow rate in m3/h, Back pressure in mbar, Maximum CO2 percentage, CO concentration in ppm, CO2 test value in %. 1: Low flame level – 48.56, 2.3, 12, 64, 10.26; 2: Medium flame level – 46.52, 2.4, 12, 21, 10.16; 3: High flame level – 46.23, 2.5, 12, 13, 10.10; 4: Maximum flame level – 97.25, 4.8, 12, 0, 10.17; 5: 101.16, 5.5, 12, 0, 10.38; 6: 103.78, 5.7, 12, 0, 10.27. Note: ① These are the test results obtained after converting the oil engine into a gas engine ； ②The experimental fuel is dimethyl ether ； ③Under the low-fire operation conditions of 1 to 3, the excess air coefficient for combustion support a ranges from 1.10 to 1.12; the combustion is thorough, the operation conditions are good, and CO levels are fully within the specified limits ； ④Under the high-fire operating conditions of 4 to 6, the excess air coefficient for combustion support a=1.07–1.11, ensuring complete combustion and favorable operating conditions, with CO levels fully meeting the standards. Comparison of economic benefits between fuel-fired boilers and gas-fired boilers: Example: A 2t/h steam boiler operates for 300 days per year, at full capacity for 12 hours per day. The heat requirement of the steam boiler is 70×104 kcal/h = 292.6×104 kJ/h = 2926 MJ/h. The calorific value of dimethyl ether is 29.8 MJ/kg, that of LPG is 46.37 MJ/kg, and that of diesel is 41.6 MJ/kg. The thermal efficiency of oil-fired boilers is 75%, while that of gas-fired boilers is 90%. The gas consumption for a 1t/h steam boiler in 1 hour is: 2926/(29.8×90%)≈109.09 kg/h ； The amount of LPG required per hour by a 1t/h steam boiler is: 2926/(46.37×75%)≈84.13 kg/h ； The amount of diesel required by a 1t/h steam boiler per hour is: 2926/(41.6×75%)≈93.8kg/h ； The annual consumption of dimethyl ether for a 2t/h boiler is: 2×3600×109.09＝785448kg＝785.45 tons ； The annual diesel consumption for a 2t/h boiler is: 2×3600×93.8＝675360kg＝675.36 tons ； The annual LPG consumption for a 2t/h boiler is: 2×3600×84.13＝605736kg＝605.74 tons. 1 ton of LPG is priced at 4,000 yuan ； 1 ton of dimethyl ether is priced at 3,200 yuan ； 1 ton of diesel is priced at 5,800 yuan: Table 4 Comparison of the economic efficiency of a 2t/h boiler over one year. For a 2t/h boiler: Fuel consumption (tons), Price (yuan per ton), Total cost (10,000 yuan). Cost of LPG per year (before renovation): 605.74; Fuel cost per year (before renovation): 675.36. Cost of gas per year (after renovation): 785.45; Fuel cost per year (after renovation): 3,200. Conclusion: Based on the above analysis, switching boilers from using oil to gas is an inevitable trend in the development of China’s boiler industry. It is in line with the laws governing the development of boilers, and it suits China’s current energy situation and fuel supply conditions. It also aligns with China’s long-term strategic goals of making full and rational use of energy while saving energy. At the same time, the project of switching boilers from oil to gas boasts mature experience and advanced technology in China; it features various safety monitoring and protection functions, can improve the combustion efficiency of boilers, reduce exhaust emissions, and meet higher environmental standards.