Modern Coal-Chemical Industry to Adjust China’s Traditional Energy Economy
Year:2014 ISSUE:2
COLUMN:ORGANICS
Click:192    DateTime:Feb.24,2014
Modern Coal-Chemical Industry to Adjust China’s Traditional Energy Economy

By Li Fenming

Clean technology to produce natural gas from coal and secondary clean energy structure to be adjusted

Conventional energy resources in China – coal, crude oil, natural gas and hydro-power – accounted for 10-11% of such resources in the world in 2012. In terms of energy consumption structure in China, 88.5% was coal; 3.7% was crude oil; 1.4% was natural gas and hydro-power provided 6.4%. Nuclear energy, biomass energy, solar energy and wind energy were all used, but the proportion of these energies in the overall picture will see little increase in the near future. As for shale gas, it is going take some time to develop the supply on a large scale in China, judging from the current situation of resources, environmental issues and technology. According to forecasts, for the next 20 years, the growth of energy consumption in China will continue at an average annual rate of around 4.5%; the demand for coal will be around 83.0 billion tons; the demand for crude oil will be 12.0 billion tons; the demand for natural gas will be 5 800 billion cubic meters. For many years to come, China will depend mainly on coal for energy.
Urgent modernization and adjustment of the energy sector – with the direct combustion of coal in the lead and the clean-energy economy as a substantial supplement – is crucial to the economic and social development of China today, in view of pressing requirements for economic development and environmental protection. This push necessarily involves (a) importing more oil/gas, (b) using coal gasification, a clean coal technology, to produce more natural gas and (c) renovating and upgrading the existing power plants that burn coal.
According to statistics, using fuels produced by coal gasification would be 10-20% more energy efficient than burning coal, and would produce 99.8% less SO2 emissions and 99.9% less dust. The recycling and reuse of CO2 is also facilitated. Resources can be optimally allocated, and the natural environment can be controlled and protected.
The coal-to-gas technology is quite well developed today and is also regarded in many countries as a clean technology for coal utilization. The world’s first coal-to-gas project, completed in North Dakota of the United States in 1984, won support from the U.S. government and was considered to be a large clean coal utilization demonstration project. For more than 20 years after it went into production, operation has been stable, and several modifications have been made for utilization of byproducts and re-injection of produced CO2 for oil production. The project is also assessed by the state government of North Dakota to be the cleanest energy project.
After studying advanced technologies in developed countries, China has already completed two large commercial coal-to-gas production units. Natural gas produced by these two projects will be delivered to users through pipelines in the near future. The lessons learned in demonstration projects about process, equipment and waste disposal will contribute greatly to building future coal-to-gas plants, supplying clean fuels to the market, and especially, reducing the need to burn coal.

Renovate power generation and adjust the coal-energy economy via clean coal utilization technology

Integrated gasification combined cycle (IGCC) is a new secondary clean energy production system that combines effective gas-steam combined cycle power generation with clean coal gasification. It offers more efficient power generation and excellent environmental protection, so it has bright prospects. The energy conversion efficiency of IGCC usually exceeds 45%. Compared with conventional coal-fired power stations, pollutant emission is only 1/10, reaching the emission level of natural gas power stations –  SO2 emission is only 1/30-1/15, and NOx emission is only 15-20%. The desulfurization ratio can reach 99%. The water consumption is only 1/3-1/2 of the consumption in conventional power stations. Among the commercialized clean coal technologies for power generation, IGCC has the highest efficiency and the biggest environmental benefit, so it will likely become one of the major coal-fired power generation methods in the 21st century.
The United States and Europe took the lead in the development and application of IGCC. Commercial units started operation in these regions in the early 1990s. Over ten countries, including the United States, Germany, Spain, Japan and the Netherlands, are constructing IGCC power stations today. In addition to the Netherlands and the United States, Spain and Japan also have commercial IGCC power stations in operation.
IGCC is now going from the industrial demonstration stage to the commercial application stage, owing maturing IGCC technology, tightening environmental standards and rising energy prices. According to statistics, in 2009, 59 IGCC power stations were already in operation and some had already reached 50% power generation efficiency. Today, the efficiency of new units exceeds 60%. More than 100 IGCC projects have recently been announced or planned for construction outside China.
Companies that can provide complete IGCC technology and equipment include GE, Texaco, E-Gas, Fluor and Bechtel of the United States, Shell of the Netherlands, and Siemens of Germany. Major manufacturers of heavy-duty gas turbines include GE, Siemens, Alstom of France and Mitsubishi of Japan. These companies can provide an IGCC unit with power-generating capacity of 200-300MW.
China started IGCC research in 1978, and the project was included in the major science & technology development plan of China. Through efforts made in past 20 years, and especially the implementation of science and technology development plans from the Eighth Five-year Plan period (1996-2000) to the Eleventh Five-year Plan period (2005-2010), the overall level of IGCC technology in China has been considerably upgraded.
China has introduced gas turbine generating technologies from the United States and Europe in recent years. Through learning about advanced foreign technologies and adding some innovations, medium and large gas turbine generating sets can now be manufactured in Shanghai and Nanjing. The 250MW IGCC power station constructed by Huaneng Tianjin IGCC Power Plant, combining its own technology with some foreign technology, has a design power generation efficiency of 48% and was completed and put on stream in November 2012.

Construct IGCC polygeneration systems and promote the development of modern energy and chemical sectors

Immense resources have been put into the development of polygeneration and the popularization of clean coal technology in recent years, and many breakthroughs have been made. A typical example is the coupling of IGCC with oil refining, iron/steel production and fuel cell manufacturing to conserve raw materials and energy and get other economic benefits. Judiciously combining well-developed and advanced coal gasification and chemical synthesis with IGCC not only speeds up the application of clean coal technology, but also greatly increases the efficiency of coal utilization, reduces greenhouse gas emission and lowers the necessary investment. Using IGCC polygeneration in the modern coal chemical sector can further reduce the traditional low-efficiency combustion of coal. Using IGCC polygeneration in refineries, in particular, can help solve the problem of treating high-sulfur heavy crude oil. The gradual perfection of IGCC+polygeneration+CCUS (carbon capture, utilization and storage) will greatly help to renovate the energy sector and related sectors and to protect the environment.
Judging from the level and economic efficiency of coal chemical technologies today, coal gasification polygeneration is a promising route. Polygeneration is a new coal chemical system that takes coal gasification technology as the core and takes the clean fuels, chemical products, power, heating and refrigeration as the goals to achieve maximum economic and social benefits. Foreign models such as Vision 21 in the United States, Shell’s Syngas Park concept, and Eagle Plan in Japan highlight chemical production and power generation (including fuel cells). China has also proposed quite a few polygeneration models.
A plant with 80MW IGCC power generation and matched 240 kt/a methanol and 200 kt/a acetic acid production, jointly completed by the Chinese Academy of Sciences and Yankuang Group Co., Ltd. in April 2006, was the first project in China that demonstrated commercial polygeneration comprising IGCC power generation and chemical production. Compared with conventional steam turbine power stations of the same scale, the standard coal consumption for supplying power is 25.1% lower; SO2 emission is 83.8% lower; NOx emission is 45.1% lower; CO2 emission is 13.7% lower; and water consumption is 50% lower. The water conservation rate in the plant has reached 50% today. The total energy utilization rate of the polygeneration project is 57.2%.
A 280MW IGCC polygeneration unit constructed to match a refining & ethylene plant in Fujian started trial run at the end of 2009. The IGCC unit can supply 80 000 m3/h hydrogen gas, most of the super high-pressure steam and some of the power needed for the whole refining & ethylene plant. The unit uses technology and equipment introduced from abroad. Solvent deasphalting and pulverized coal gasification technologies are used.
These projects once again prove that it is feasible to develop IGCC polygeneration in China.
A modern energy and chemical industry sector characterized by coal-power-chemical integrated polygeneration will be built to support the sustainable development of China’s economy through using clean coal utilization technologies and related advanced technologies as well as fully employing China’s wealth of coal resources. Moreover, it can help fulfill the Chinese government’s commitment that China’s CO2 emission per unit of GDP will be 40-45% lower in 2020 than it was in 2005.