Ni Weidou

Energy for sustainable development in China

To ensure energy to meet needs for economic growth and sustainable development more emphasis should be given to energy efficiency, renewable energy and new technologies for both energy end-use and supply. One key technology is gasification of coal to produce liquid and gaseous fuels, and electricity. The overall conclusion is that there are plausible energy-technology strategies, well within reach if early action is taken, that would enable China to continue social and economic development through at least the next 50 years, while ensuring security of energy supply and improving local, regional and global environmental quality. Such desired energy futures will not happen in the present policy environment, and options to enhance the energy systems for sustainable development are discussed.

Polygeneration energy system based on coal gasification

Environmental pollution has become a bottleneck for the sustainable economic development of China. A “business-as-usual” energy system in China is not suitable for meeting sustainability needs. It is well known that China has to use coal as the main primary energy source over the long term. Under such special conditions, to plan and construct an integrated sustainable energy system with optimal benefits in resource and energy utilization and environmental emissions is urgent. By introducing international studies and new developments in sustainable energy systems, this paper puts forward the concept that a polygeneration strategy based on coal gasification is the trend for future development of Chinas domestic energy industry. The framework of a polygeneration system based on oxygen-blown gasification is described and its benefits are analyzed. Finally, the starting procedure, government role, and policies for implementing polygeneration strategies in China are proposed.

Case-study of a coal gasification-based energy supply system for China

“Syngas city” (SC) is a concept for a coal gasification-based energy supply system that deploys gasification-based polygeneration technologies to meet energy needs of coal-rich areas. This paper summarizes an assessment of the projected environmental impacts of implementing a SC strategy for Zaozhuang, Shandong Province, China. A SC scenario and a “business-as-usual” (BAU) scenario are developed for the Zaozhuang area considering the time-frame 2000 to 2020. A comparison of these scenarios is used to assess whether the SC concept for Zaozhuang could reduce air pollution and promote further economic development while meeting projected demand for energy services. On the basis of socio-economic assumptions, sectoral energy-demand projections are developed. Assumptions are made about expected rates of market penetration of dimethyl ether (DME) and methanol, two clean fuels derived via coal gasification. Emissions of air pollutants in the SC scenario are compared with those in the BAU scenario. Policies to promote the SC concept and technologies in China are proposed.

Energy for sustainable development in China: an overview of approach and work carried out by the Working Group on Energy Strategies and Technologies of the China Council for International Cooperation on Environment and Development

The Government of China established the China Council on International Cooperation for Environment and Development (CCICED) in 1992 to advise the leadership of China on the extremely challenging issues of environment and development. The Council meets once a year and adopts recommendations on the basis of reports from working groups. The Council has about 25 Chinese members, mostly with ministerial rank, and 25 international members with corresponding status. This article describes the work of the Working Group on Energy Strategies and Technologies (WGEST). The WGEST, with half Chinese and half international membership, met twice a year and organized studies, workshops, demonstration projects, and conducted capacity-building with research institutions in China. The understanding of the WGEST on the options for China is summarized in this article, and the rest of the articles in this issue cover different topics on which the WGEST has been contributing to the developments in China.

Analysis of hydrogen and oxygen hybrid cycle

Based on the analysis of the typical combined cycles the hydrogen and oxygen hybrid cycle was carried out. From the result of the calculation some conclusions can be drawn that the efficiency of the Hydrogen and Oxygen cycle increases with the increases of the temperature and the maximum pressure of the cycle. The efficiency reached 62% when the temperature is at 1700°C and the pressure is at 30MPa. There is a good ratio in the middle pressure gas turbine and a fine ratio distribution between the middle pressure gas turbine and high pressure gas turbine. When the temperature is 1500°C, the maximum pressure is at 30MPa and the ratio is 8.0 the efficiency can achieve 60.5%, at the same time the fine ratio distribution is at the point of 1.43. The fine ratio distribution decreases with the total ratio of the gas turbine in the sub-critical area while it decreases at first and increases latterly in the supercritical domain there is a transition point at total ratio value of 30. The hydrogen and oxygen hybrid cycle system can obtain a higher efficiency by using optimization method on the recuperation and reheat systems.

Reducing initial barriers for CCS deployment on pulverized coal-fired power plants in China by optimizing the capture ratio of carbon dioxide

The major barriers for applying carbon dioxide (CO2) capture technology to coal-fired power plants in China and worldwide are the consequent drop in power plant energy efficiency and significantly higher cost of electricity (COE). This paper proposes a new perspective for determining the most cost-efficient CO2 capture ratio using a modeling and simulation approach that balances the per unit parasitic energy consumption for absorbent regeneration with the per unit capital cost of the CO2 capture unit of a coal-fired power plant. Using a typical 550 MW supercritical pulverized coal-fired power plant in China as the reference plant, with monoethanolamine (MEA) absorption unit for CO2 capture, a process model of the power generation unit together with the MEA CO2 capture unit was developed and detailed process simulations were conducted with the model. Then, a sensitivity analysis was then conducted to study the impact on key plant behavior indicators, including per unit energy penalty for absorbent regeneration, net power output and power generation efficiency, total capital cost of the power plant together with the MEA CO2 absorption unit, per unit capital cost of the MEA unit, COE, as well as the per unit CO2 avoidance cost (indicated by cost per tonne (t) CO2 avoided), across a CO2 capture ratio range between 20% and 99%. The results show that when CO2 capture ratio is low, while the unit energy consumption for absorbent regeneration per tCO2 avoided increases steadily with the increase of CO2 capture ratio, the cost per tCO2 avoided decreases as the MEA absorption train is scaled up given the high capital cost of each MEA train. After CO2 capture ratio reaches certain level (60% for this plant), the cost per tCO2 avoided starts to increase with CO2 capture ratio, since the unit energy consumption for absorbent regeneration per tCO2 avoided has increased to so high that it supplants the scaling effect of the MEA train and becomes the dominant factor that determines the increase or decrease trend of the cost per tCO2 avoided. Besides, due to the physical restraint on the upper bound of CO2 capture capability of one single MEA train by the diameter of the absorber, an additional MEA train is needed when the CO2 capture ratio increases to certain points (40% and 85% for this plant), resulting in jumps of several parameters including the total capital cost for the power plant and MEA CO2 capture unit, per unit capital cost for the MEA CO2 capture unit, and last the cost per tCO2 avoided. Based on all these result, finally a cost-optimal CO2 capture ratio of 40% (365 RMB/tCO2-_avoided) was obtained, which is easier for the power plant to bear while realizing a significant reduction in CO2 emission of this plant. Therefore, applying this approach for determining CO2 capture ratios could help minimize the barrier for the initiation of carbon dioxide capture and storage (CCS) in Chinas power industry. Besides, future replacement or improvement for the MEA CO2 capture technology has the potential to further reduce the cost per tCO2 avoided, which needs special attention.

Energy and Exergy Analysis of Hydrogen-Fueled Combined Cycle

The hydrogen-fueled combined cycle has been proposed. Including the balance of the material and energetic flows, the thermal efficiency and the exergy efficiency are introduced to evaluate the overall performance of the cycle. A proper parametric analysis is then performed in order to investigate the influence of the main working parameters on the cycle efficiency. The main factors such as temperature and pressure have strong effects on the attainable performance according to the results; moreover, it comes to the conclusions that the large amount of exergy losses are caused due to the process of combustion, it is necessary to raise the combustion temperature to reduce the losses.

Hybrid Cycles with Hydrogen as Fuel

The gas turbine and steam turbine combined cycle fueled with hydrogen have an overall high efficiency. The virtues of the supercritical steam turbine, the high temperature gas turbine and the low pressure steam turbine are fully expressed in this system. The mean temperature, at which the combined cycle absorb heat is upgraded greatly while the mean temperature, at which the cycle releases heat is decreased to environmental temperature, and finally the system efficiency is raised greatly to a high level. The simple combined cycle and the cycle with heat recover and reheat were analyzed and compared. The calculation results show that the overall efficiency of the once reheat system can reach 63.2% when the max pressure is at 30MPa and the max temperature is at 1500¿. And also, the combined cycle with hydrogen as fuel has no harmful emissions to the environment, it is a prospective energy conversion system in the near future.

Fault diagnostic system on knowledge for steam turbogenerator

In this paper a new neural network model is proposed for fault diagnosis of steam turbogenerator, which is a self-organization network model that forms a continuous topological feature mapping from vibration frequency spectrum to a kind of fault. The self-organization network model is trained without supervision. The knowledge base in the corresponding expert system is built up and maintained automatically. We discuss the setting and running of the network and review the implementation of fault diagnosis when a turbogenerator is started or stopped. The network performs the diagnosis automatically. The topological feature mapping is observed by using graphics. It can quickly gives a direct answer as to whether a fault exists and what type of fault it is, without requiring the interference by a human expert.<<ETX>>

Digital Simulation of Thermal Turbomachinery Systems

A flexible modular type calculation method is developed in this paper, it can be used to a multitude of applications, thus permitting many required turbomachinery systems to be simulated. In this method every standard component is considered as a subsystem, which can be readily linked in diverse ways with other components. This method can also be used for calculating the transients of nonlinear systems under large pertubation. As a case study, a computer programme for simulating the energy recovery system of the fluidized catalytic cracking (FCC) installation is presented.Copyright