1. natural gas
Natural gas is a colorless and odorless combustible gas produced in oil and gas fields. The main component of CH4 is methane (CH4), accounting for 80-99%, followed by ethane, propane, total butane, total pentane, carbon dioxide, carbon monoxide, hydrogen sulfide, total sulfur and water. Under the standard condition, the boiling point is - 161.52 ℃, the density of natural gas is generally 640-750g / m3, and the relative density relative to air is 0.55-0.62
2. Working principle of natural gas as fuel
CH4+2O2—–2H2O+CO2+38MJ/m3
3. Main uses of natural gas
Natural gas is an important industrial raw material and fuel. Its main uses are as follows.
1) Main fuel for power plant, thermal energy, heating, air conditioning and other industrial enterprises;
2) Fuel for catering and civil use;
3) The main raw materials of chemical industry can synthesize or refine various industrial raw materials and semi-finished products;
4) As a clean fuel for motor vehicles that meet the requirements of environmental protection and an ideal substitute for gasoline and diesel, this is a new technology developed rapidly at home and abroad in recent years, which can be used in automobiles, ships, trains and even airplanes.
4. LNG basic parameters
The main components of LNG are methane (over 90%), ethane, nitrogen (0.5-1%) and a small amount of C3-C5 alkanes. LNG is another form of energy transformed from natural gas.
1) The main component of LNG is methane, chemical name is CH4, and a small amount of ethane C2H6, propane C3H8, nitrogen N2 and other components.
2) The critical temperature is - 82.3 ℃.
3) The boiling point is - 161.25 ℃, and the ignition point is 650 ℃.
4) The liquid density is 0.420-0.46t/m3, and the gas density is 0.68-0.75kg/m3.
5) The calorific value of gas is 38mj / m3, and that of liquid is 50mj / kg.
6) Explosion range: upper limit is 15%, lower limit is 5%.
7) Octane number ASTM: 130.
8) Colorless, tasteless, non-toxic and non corrosive.
9) The volume is about 1 / 625 of the same volume of natural gas.
5. Six advantages of LNG
1) The volume of LNG is 625 times smaller than that of natural gas of the same mass, so it is convenient to transport LNG to places without natural gas by car and ship.
2) LNG has high storage efficiency and small land occupation. In the province of investment, 10m3 LNG storage capacity can provide 10000 households with one day's domestic gas.
3) Compared with gasoline, LNG has higher octane number, better antiknock performance and longer engine life. Low fuel cost. Good environmental protection performance. It can reduce HC by 72%, NOx by 39%, CO by 90%, Sox and Pb by zero.
4) The latent heat of LNG vaporization is high, and the cooling capacity in the liquefaction process can be recycled.
5) As the density of LNG after vaporization is very low, only about half of the air, a little leakage will fly away immediately, which will not cause explosion.
6) LNG is a good clean fuel because of its pure composition, complete combustion and the generation of carbon dioxide and water after combustion, which is conducive to environmental protection and urban pollution reduction.
6. Main use of LNG
1) As a clean fuel vaporized for urban residents, it is safe, convenient, fast and has little pollution.
2) It is used as alternative vehicle fuel. When LNG is used as the fuel of automobile engine, the engine only needs to be changed properly. The operation is not only safe and reliable, but also has low noise and pollution. Especially in today's increasingly strict emission regulations, the exhaust of automobile using LNG as the fuel is obviously improved. According to reports: compared with compressed natural gas (CNG), the fuel cost of LNG vehicle is 20% lower and the weight is 2 / 3 lighter for medium-sized and medium-sized heavy-duty vehicles under the same travel distance and operation time. At the same time, the cost of fuel supply system is at least 2 / 3 lower. It can be proved that liquefying natural gas and storing it in liquid state is the most economical and effective way to promote its application in transportation fuel.
3) As a cold source, it can be used in the production of fast cooling food, the low-temperature grinding of plastics and rubber, as well as desalination of seawater and cable cooling.
4) As industrial gas fuel, it is used in glass shell factory, process glass factory and other industries.
7. LNG transportation mode
LNG is mainly transported by ship, train and truck. Within the economic transportation radius of 500-800 km, it is an ideal way to transport LNG by truck. The tank body of tank car adopts double wall vacuum powder insulation, equipped with operation valve safety system and infusion hose, etc. The manufacturing technology of domestic cryogenic liquid tank car is relatively mature, and the tank car is safe to use. LNG products are stored in cryogenic liquid tanks with double wall vacuum powder insulation. The daily evaporation rate of LNG can be controlled within 0.46%, and the storage period is 4-7 days.
8. LNG is the clean fuel of automobile
Among all clean fuels, natural gas is regarded as the most suitable alternative fuel for automobiles by many countries and experts in the world because of its mature application technology, safety, reliability and economic feasibility. Compared with gasoline, the emission of HC, NOx, Co, Sox and Pb are reduced by 72%, 39%, 90% and zero respectively. 40% noise reduction. Therefore, promoting the use of natural gas fuel will play a positive role in reducing air pollution and improving the environment.