An economical and environmental-friendly technology for the production of high-quality coke from non-caking or low-caking coal was developed, in the National Project called “Coke Production with Ad-vanced Coal Conversion Technology (SCOPE21) ”. One of the core technological elements of SCOEP21 is rapid coal heating at the temperature less than softening or melting threshold. The targeted parameters are >2, 000°C/minute for heating speed, 380 to 400°C for coal heating temperature, and not more than 50°C for temperature deviation. In this paper we introduce basic results for the development of rapid heating process (RHP). We firstly made a simulation model for the rapid coal heating process by “Computational Fluid Dynamics”. Then, we collected basic data required for simulation analysis and thereby verified the effectiveness of the simulation model in comparison of the test results for the behavior of coal particles in airflow with the simulation results through the cold model test. Finally, we conducted a performance prediction of rapid heating towers both in pilot scale and in commercial scale, by way of the computerized simulation. As a result, it was confirmed that the above-mentioned target parameters were attainable, and that this research well prepared the ground for the practical use of the subject process.
Development of the innovative coke-making process, SCOPE21 (Super Coke Oven for Productivity and Environmental enhancement toward the 21st century) has been conducted by Japan Iron and Steel Federation (JISF). It has been performed from 1994 to 2003. The purposes of SCOPE21 process are as follows. 1) Increasing the blending ratio of poorly-coking coal in coal charge, in order to reduce the cost of coke and expand the use of available coal resources, 2) In SCOPE21, the coking time in coke ovens can be remarkably shortened due to the rapid preheating of coals up to 330-380°C. The shortening of coking time leads to higher productivity of coke, and therefore to the decrease of oven numbers in the case of identical production of coke compared to conventional coke-making process. These two purposes are supposedly achieved by applying a coal rapid preheating technology to the new coke-making process. In this process, coal is rapidly preheated to the temperature range from 330°C to 380°C and then charged into coke oven. Therefore it is important to study the effect of rapid preheating on coal thermoplas-ticity and the strength of resultant coke. It is generally known that the thermoplasticity of coals is enhanced when the coals are rapidly heated through their thermoplastic stages. However, when the coals are rapidly preheated to 330-380°C, the effect of rapid preheating on the subsequent development of coal thermoplasticity has been unclear. Here, changes of thermoplastic behavior by this preheating were studied using a needle penetrater. Conse-quently, it was found that the thermoplasticity of coals was enhanced when the coals are rapidly preheated to 330-380°C, even when the slow heating rate (3°C/min) was applied through the following thermoplastic stages.
An innovative cokemaking process named SCOPE21 has been developed from 1993 to 2003 by member companies of the Japan Iron and Steel Federation as a national project. The concept of this project is higher utilization of non-, slightly coking coals, improvement of productivity and environmental protection. In order to enhance coke productivity, coals are preheated rapidly, fine coals are agglomerated and coke is discharged at medium temperatures. The strength of coke carbonized at medium temperatures will be lower than that of coke carbonized at a temperature over 1000°C so that coke discharged at medium tempera-ture is further heated in an upper part of CDQ pre-chamber to obtain the conventional coke strength. In this study, the quality of cokes discharged at medium temperatures was analyzed and the upgrading effect of them was investigated by three different reheating methods. As a result, it was confirmed that coke discharged at medium temperature could be improved by reheating treatment and upgrading effect was affected by reheating method.
One of the targets in the SCOPE21 (Super Coke Oven for Productivity and Environmental Enhancement toward the 21st Century) process was to improve the productivity. To achieve high productivity, the process was applied the following items; (1) ultra super dense brick, (2) thin wall (70mm), (3) preheated coal charging, (4) medium temperature carbonization. As heat flux for carbonization was needed about 2 times as much as a conventional coke oven, the combustion technologies to achieve high productivity were investigated by using the actual scale combustion test oven. The combustion conditions to achieve low NOx in the exhaust gas and uniform heating were clarified. The carbonization oven of the pilot plant was designed based on these results. The combustion targets for the low NOx and uniform heating were achieved in the test operation.
The evaluation method of caking property is crucial for coke-making technology. Generally, the Gieseler plastometry and dilatation tests are used to measure the caking properties of coals. But these tests have disadvantages when they're applied to non-or slightly caking coals. Most of non-or slightly caking coals can not be distinguished by the Gieseler plastometry test, nevertheless their coke strength indices are not identical. For blended coals consisting of coking coal and non-or slightly caking coals, there are no good relationships can be seen between caking property values of the coal blends measured by the Gieseler plastometry and strength indices of the cokes made from these coal blends. New method for evaluating caking properties by NMR has been discussed. As a result, it was found that caking properties of non-or slightly caking coals could be evaluated by the NMR method. Furthermore, caking properties of coal blends consisting of coking coals and non-or slightly caking coals could be mea-sured by NMR method. As a result, NMR method for measuring caking property of coals has been developed.
A continuous monitoring technique for measuring all gases generated from coal during coking reaction was developed. This system has two gas detectors, which are a Fourier transform-infrared spectrometer for hydrocarbon, carbon monoxide and carbon dioxide and a semiconductor sensor (SnO2) for hydrogen. Using this system, the gas generation behavior on the condition of two levels, a laboratory scale (about 50 mg sample) and a coke test oven scale (about 120kg), were investigated. As a result, the tendency of both gas generation behaviors was in agreement and the gas generation behavior by difference of a coal combination was found. It was shown that the gas generated from plural coals was based on the additive property of gas from each combination coal.
Acid rain has harmed the soil, the lake and the swamp, and failed the forest reserves. It has spread to all over the world. Nowadays, three large acid rain regions have been formed separately in Northern Europe, North America and Asia. Based on the analysis of the newest data about acid rain in China, we describe the distribution, features and current situation, the cause of formation and the forecast of acid rain in near future, with an emphasis on countermeasures planned in China.
The grey theory carries out the system analysis and prediction on the basis of the accumulated data of original series. The accumulated generating operation (AGO) is one of the most important characteristics of grey theory. Its main purpose is to reduce the randomness of original data. Therefore, the grey theory is more suitable for analysis and prediction of the system whose regularity of the original series is poor and/or whose original information are lacking. The improved grey model by the equal-dimensional replenishment and residual modification with Markov-chain sign estimation further improve the accuracy of grey model. In this paper, we first simply introduce the mechanism of grey model and grey analysis and predictionmodel on China's energy system, then discuss the accuracy and variable sensitivity of this model. The results show that grey energy model has a higher simulating and forecasting accuracies. Along with GDP growth, the final energy consumption in China shows three stages: rapid growth stage, slow growth stage and slow declining stage. The sustaining period per stage is closely related with GDP growth rate. The longer the used original series is, the larger the future energy consumption is. The results of sensitivity analyses show that grey energy model is stable for GDP and the length of original series.
In 2000, the world natural gas consumption was about 2, 397 bcm (billion cubic meter), 32% of which is consumed in North America. In this paper, genetic algorithms procedure was applied to compute annual time series of economically optimum supply rates combination consisting individual natural gases in North America so that net present value of total production costs plus transportation costs could be minimized. At first, several computations for USA were carried out to settle the appropriate parameters of genetic algo-rithms, because long historical data on USA are available as well as infrastructure of gas pipelines is fully furnished. Next, computations based on the supply and demand scenario for North America were carried out and it was concluded that unconventional natural gases would play an important role to satisfy stable natural gas demand in the next 30 years in North America.
Combustion flue gases have particulate and gaseous mercury. Particulate mercury is captured in an electrostatic precipitator (EP) as fly ash but gaseous mercury passes through an EP and flows into a wet-flue gas desulfurization (wet-FGD) unit in combustion plants. Besides, gaseous mercury takes elemental and oxidized forms (Hg0 and He2+) in combustion flue gases, these chemical forms have great influence on the behavior of gaseous mercury in a wet-FGD unit. The behavior of Hg0 and Hg2+ in water and calcium compound slurries simulating limestone-gypsum process, which is one of wet-FGD systems, has been studied. It was clarified that almost of Hg0 passed through the solutions, on the other hand Hg2+ was captured in it and some captured He was converted into Hg0, which was released from the solutions. The conversion ratio of Hg2+ into Hg0 was influenced by gas and solution conditions.
This study was made to obtain basic knowledge of conversion biobriquettes composed of low rank coals contiaining large amount of ash and sulphur and biomass like agricultural and forest waste into clean gaseous fuels. Three Chinese bituminous coals and three kinds of biomass were heat-treated at 1173K in nitrogen after into biobriqettes. Each biobrigette char obtained was subsequently gasified with steam at 1073-1273K and 0.12-0.68MPa partial pressures of H2O to measure the reactivity. For comparision, steam gasification of the corresponding coal char was conducted under the same conditions. It was found that coal chars had low reactivities, while gasification rate of biobriquette chars with and without Ca (OH) 2 acting as desulphurization agent were greatly enhanced to the same level of that for a subbituminous coal. The enhancement of the rate for biobriquette chars without calcium can be explained by such a situation that the portion of biomass would be preferentially gasified, thereby the contact area between unreacted coal char and steam could be increased, in addition of the catalytic effect of biomass ash. For the composition of gases evoluved, it depended on the ratio of coal/biomass in weight, gasification temperature, and the partial pressure of steam, indicated the control of the ratio of H2/CO by selecting these operating factors.