What are Different Types of Synthetic Fuels?
Synthetic fuels are those new fuels that are transformed by one or more energetic bodies through chemical changes. [1] At present, there are two main ways to prepare synthetic fuels at home and abroad: First, pure coal or natural gas is represented by Fischer-Tropsch synthesis through carbon addition reaction to generate new fuels; Second, it is obtained by heat treatment of organic matter in urban sludge energy. [2]
Current status of synthetic fuels
Vehicle fuel is a secondary energy source. When discussing energy conservation and GHGs emission reduction, we can not only calculate the energy consumption and emissions of the fuel in the process of use, but also consider the conditions of the upstream stages. [2] Well-to-Wheel (from mine to wheel) is widely used in the latest research results of European and American scientists in this area Comparison chart of Chinese automotive fuel Well-to-Wheel stage
Analysis. It can be seen from the following data:
From the perspective of energy saving and international emission reduction obligations, the Chinese government should not promote large-scale natural gas and coal-based liquid fuels on a large scale until a more efficient synthetic technology route is found. The development of diesel cars and hybrid cars may be more Good choice. According to the regional distribution of resources, research and demonstration of coal-based and natural gas-based vehicle fuels can be carried out in some areas, but the development of supporting carbon storage technologies needs to be strengthened in order to solve the problem of greenhouse gas emissions.
From the perspective of energy consumption and greenhouse gas emissions, coal-based synthetic fuels are much higher than natural gas-based synthetic fuels. After using existing carbon storage technologies, greenhouse gas emissions have been reduced, but still higher than the latter. Natural gas-based synthetic fuels are higher than gasoline and diesel. However, the calculation also shows that the petroleum consumption of coal-based and natural gas-based fuels has dropped significantly. If the traditional petroleum-based fuels are taken into account, the petroleum consumption of coal-based and natural gas-based synthetic fuels is only 1% to 4% of gasoline . Comparison chart of Chinese automobile fuel Well-to-Wheel stage [4]
Table 1 Sources of production data for natural and coal-based synthetic fuels
Vehicle fuel | Gas-based | Coal-based |
Methanol | Actual data of large natural gas chemical plants in Sichuan | Actual data of large coal chemical plants in Henan |
Dimethyl ether | Actual data of two-step 10,000-ton production line in China | Experimental data of two-step coal-to-DME |
Fischer-Tropsch | Sagnol company planning data for construction in Qatar | Henan and Shandong Enterprise Project Planning Data |
Development potential of synthetic fuels
From the perspective of energy saving and international emission reduction obligations, before finding a more efficient synthetic technology route, the Chinese government should not promote large-scale use of natural gas and coal-based liquid fuels for vehicles. The development of diesel cars and hybrid cars may be more Good choice. According to the regional distribution of resources, research and demonstration of coal-based and natural gas-based vehicle fuels can be carried out in some areas, but the development of supporting carbon storage technologies needs to be strengthened in order to solve the problem of greenhouse gas emissions.
Synthetic fuel city sludge heat treatment
Municipal sludge contains a large amount of organic matter, and the calorific value of dewatered sludge is about 8360kJ / kg. If it can be fully utilized, it will be of great significance to develop a "sludge synthetic fuel" that can be used by boilers instead of coal for sewage plants or other industrial and domestic boilers.
From the data below, we can know that the organic matter content in municipal sludge is relatively high. It is of great economic value and environmental significance to compost biogas or add appropriate curing agents for coal combustion. Through Figure 2, we can know the reuse route and process of general urban sludge. [3] Figure 2 Urban sludge pyrolysis and gasification solution
Table 2 Composition of urban sludge
project | Organic matter (%) | Total ash (%) | Non-soluble ash (%) | Pentosan (%) | Oils and fats (ether solubles) (%) | Hemicellulose (%) | Cellulose (%) | Lignin (%) | protein (%) | Remark |
Fresh sludge | 60 ~ 80 | 20 ~ 40 | 17 ~ 35 | 1.0 | 7 ~ 35 | 3.2 | 3.8 | 5.8 | 22 ~ 28 | |
Activated sludge | 65 ~ 75 | 25 ~ 38 | 20 ~ 30 | 2.1 | 5 ~ 12 | ~ | 7.0 * | ~ | 37.5 | * Contains Lignin |
Digested sludge | 45 ~ 60 | 40 ~ 55 | 35 ~ 50 | 1.5 | 3.5 ~ 1.7 | 1.6 | 0,6 | 8.4 | 16 ~ 21 | |
Table 3 Analysis table of calorific value of digested sludge
Mt % | Mad % | Ad / Aad % | Vdff % | Coke slag characteristics 1-8 | FCad % | Qgrvd MJ / kg | Qneg · v · ar MJ / kg | Cdaf % | Hdaf % | Ndaf % | Sdaf % | Odaf % |
5.46 | 2.14 | 51.86 / 50.75 | 56.21 | 2 | 21.25 | 11.87 | 10.75 | 45.10 | 4.98 | 2.94 | 2.78 | 44.20 |
Table 4 Analysis table of synthetic fuel for dam coal and digested sludge
project | Mt % | Mad % | Ad % | Vdaf % | Coke slag characteristics 1-8 | FCad % | Wgrvd MJ / kg | Qneg · v · r MJ / kg |
Dam coal | 9.44 | 1.35 | 28.88 | 33.86 | 6 | 46.14 | 23.22 | 20.14 |
Digested sludge | 5.46 | 2.14 | 51.86 | 56.21 | 2 | 21.25 | 11.87 | 10.75 |
Synthetic fuel | 16,88 | 1.96 | 34.72 | 34.96 | 4 ~ 5 | 41.18 | 21.95 | 17.26 |
project | Aar% | Var% | car% | Har% | Nar% | sar% | Oar% | Remark |
Dam coal * | 26,51 | 21.69 | 51.21 | 2.98 | 0.94 | 4.96 | 3.88 | Dam bituminous coal Class II |
Digested sludge | | | | | | | |
Synthetic fuel | 29.44 | 18.71 | 44.11 | 2.65 | 0.86 | 3.47 | 2.59 |
Table 5 Thermal test comparison table
project | Dam coal | Synthetic fuel |
Boiler output D (kg / h) | 2236.04 | 2619.46 |
Fuel consumption (kgA) | 510.3 | 555.0 * |
Input heat Qr (MJ / kg) | 20.14 | 17.26 |
Positive equilibrium thermal efficiency is still 1 (%) | 58.40 | 73.51 |
Anti-equilibrium thermal efficiency 2 (%) | 62.84 | 73.52 |
Exhaust temperature Qpy () | 155.7 | 160.30 |
Efficiency difference between positive and negative balance (%) | 4.36 | 0.01 |
Excess air factor at smoke exhaust | 2.99 | 2.76 |
Slag combustible content C12 (%) | 30.21 | 10.01 |
* 10% water added when mixing [3]
