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[en] [Parts 1 and 2 of this paper appeared in the December 1988 issue.] Within a quench tower the change in gas composition that results from the fitting of arresters is such that the emission is more buoyant. As gas temperature rises, there is a marked fall in the time taken to reach the efflux velocity under the influence of buoyancy - from more than four seconds with open towers to less than one second with arrestment. The time taken to reach final plume rise exceeds 200 s for emission from open towers, but is less than 200 s with arrestment. Under calm conditions the plume rise from the quench tower serving 6 m ovens is approximately 550 m. Wind velocity has a significant effect on the rise, but efflux velocity has only a modest effect so long as it is sufficient to avoid downdraft. From an open tower serving 6 m ovens the plume rise is approximately 165 m, and with arrestment this reaches 190 m. The actual velocity of a buoyant plume fails rapidly with distance downwind from the tower. In the case of the open tower serving 6 m ovens, the efflux velocity of 7.9 m s-1 fails to 3 m s-1 within 30 m of the tower, giving a high rise in the immediate vicinity of the tower. The major effect of enhanced dispersion is found with the finer particles. Maximum ground-level concentration for the finest particles is found 10 Heff downwind. Material is dispersed beyond 3 km from the source. The installation of arresters should reduce ground-level concentrations by about 50%. (author)
[en] This article describes a process which reduces emissions from coke production in coke plants. The focus is on the charging process, which can be partly responsible for the fact that statutory emissions limits, which were originally met, are exceeded as coke plants get older. This article presents a solution in the form of a newly developed system that allows the oven charging system - the charging car - to respond to age-related changes in the geometry of a coke oven and thereby reduce the level of emissions.
[en] In 1984, based on epidemiological data on cohorts of coke oven workers, USEPA estimated a unit risk for lung cancer associated with continuous exposure from birth to 1 microg/m3 of coke oven emissions, of 6.2 x 10-4. This risk assessment was based on information on the cohorts available through 1966. Follow-up of these cohorts has now been extended to 1982 and, moreover, individual job histories, which were not available in 1984, have been constructed. In this study, lung cancer mortality in these cohorts of coke oven workers with extended follow-up was analyzed using standard techniques of survival analysis and a new approach based on the two stage clonal expansion model of carcinogenesis. The latter approach allows the explicit consideration of detailed patterns of exposure of each individual in the cohort. The analyses used the extended follow-up data through 1982 and the detailed job histories now available. Based on these analyses, the best estimate of unit risk is 1.5 x 10-4 with 95% confidence interval = 1.2 x 10-4--1.8 x 10-4
[en] The coke-oven-gas-to-methanol (CGTM) process is one of the most important coal-to-chemical processes. However, it suffers from ineffective hydrogen utilization, limiting both its capacity and energy efficiency. In addition, currently, there is a large amount of low-quality pulverized coke that cannot be used for value-added applications. In this paper, two pulverized coke-assisted CGTM processes (PC-CGTM1&2) are proposed. In these processes, coke-oven gas is either partially oxidized or steam reformed to generate a hydrogen-rich syngas, and simultaneously gas produced by the gasification of pulverized coke is used to adjust the ratio of hydrogen and carbon to about 2, ideal for methanol synthesis. The results show that the optimized mass ratios of PC/COG are 0.27 and 0.51 for the PC-CGTM1&2, respectively. Their exergy efficiencies are increased to 71.3% and 75.9% from 58.6% in the CGTM process. Their methanol productivities are also increased to 0.63 and 0.75 from 0.43 Mt/y. The total product costs of the PC-CGTM1&2 are 21 and 43 US$/t lower than that of the CGTM (282 US$/t). The internal rates of return for these new processes are 19.7% and 25.7%, whereas it is only 13.5% for the CGTM, demonstrating the ability of the new processes to resist inflation and market risk. - Highlights: • Novel pulverized coke gasification-assisted COG-to-methanol processes were proposed. • The co-feeding of pulverized coke and COG resulted in exergy savings by 12–17%. • Two novel processes improved methanol capacity to 0.63 and 0.75 Mt/y from 0.43 Mt/y. • Two novel processes presented great competitiveness with an increase of 6–12% IRR.
[en] A novel high precision detection method for the determination of the distillation end point of the coking process (usually in the 950 deg C range) has been developed. The system is based on the use of a metallic capsule that melts at a fixed temperature and releases a radioactive gas tracer (133Xe) in the stream of the distillation gas. A series of tests on a pilot oven confirmed the feasibility of the method on industrial scale. Application of the radioactive tracer method to the staging and monitoring in the coking process appears to be possible. (author). 6 refs., 5 figs., 3 tabs
[en] This project deals with the demonstration of a coking process using proprietary technology of Calderon, with the following objectives geared to facilitate commercialization: (1) making coke of such quality as to be suitable for use in hard-driving, large blast furnaces; (2) providing proof that such process is continuous and environmentally closed to prevent emissions; (3) demonstrating that high-coking-pressure (non-traditional) coal blends which cannot be safely charged into conventional by-product coke ovens can be used in the Calderon process; and (4) demonstrating that coke can be produced economically, at a level competitive with coke imports. The activities of the past quarter were focused on the following: Conducting bench-scale tests to produce coke and acceptable tar from the process to satisfy Koppers, a prospective stakeholder; Consolidation of the project team players to execute the full size commercial cokemaking reactor demonstration; and Progress made in advancing the design of the full size commercial cokemaking reactor
[en] This project deals with the demonstration of a coking process using proprietary technology of Calderon, with the following objectives geared to facilitate commercialization: (1) making coke of such quality as to be suitable for use in hard-driving, large blast furnaces; (2) providing proof that such process is continuous and environmentally closed to prevent emissions; (3) demonstrating that high-coking-pressure (non-traditional) coal blends which cannot be safely charged into conventional by-product coke ovens can be used in the Calderon process; and (4) demonstrating that coke can be produced economically, at a level competitive with coke imports. The activities of the past quarter were focused on the following: Consolidation of the team of stakeholders; Move the site for the commercial demonstration to LTV Steel, Cleveland, Ohio; Permitting for new site; Site specific engineering; Cost update of the project as it relates to the Cleveland location; FETC update; DCAA audit; and Updated endorsement of Calderon process by Ohio EPA and U.S. EPA, Region 5
[en] The coking capacities of the world today come up to 360 million t/a or 200 mill. t/a in the western world alone. Assuming that the specific coke rate of blast furnace will be further reduced and that conde steel production stagnates these capacities are necessary in order to supply the steel industry with the required amounts of coke. A comprehensive analysis of coking plant capacities, especially in the countries of the western world shows that plants are often outdated. Old and badly-maintained plants mean reduced production and closing down of coking plants. This seriously geopardises safety of supplies to the steel industry. Decisions to build new coking plants are there for urgently required. (orig.)
[de]Die derzeit nutzbaren Kokereikapazitaeten liegen bei rund 360 Mio. t/a in der Welt bzw. rund 200 Mio. t/a in der westlichen Welt. Geht man davon aus, dass der spezifische Kokssatz im Hochofen weiter reduziert wird und die Rohstahlerzeugung stagniert, so sind diese Kapazitaeten notwendig, um auch zukuenftig die Stahlindustrie mit dem benoetigten Koks versorgen zu koennen. Eine umfangreiche Analyse der Kokereikapazitaeten, vor allem in den Laendern der westlichen Welt, macht deutlich, dass die dort verfuegbaren Kapazitaeten stark ueberaltert sind. Ueberalterung und auch schlechte Wartung der Anlagen werden zu weiteren Produktionseinschraenkungen und Kokereistillegungen fuehren. Damit ist die Versorgung der Stahlindustrie mit Koks in ernsthafter Gefahr. Es muessen deshalb zuegig Entscheidungen zum Bau neuer Kokereianlagen getroffen werden. (orig.)
[en] Highlights: • CO2 recycle assistance with COG to SNG is proposed. • SNG production is increased by 14% through CO2 recycle. • CO2 recycle scheme helps to convert 20% CO2 and capture 80% CO2. • CO2 recycle simplified carbon supplementary with resulting of 6–7% energy saving. - Abstract: Based on the industrial technology from coke oven gas to synthetic natural gas, a process of CO2 recycle assistance with coke oven gas to synthetic natural gas is proposed, simulated, and optimized. The effects of key parameters on the performance of new system are investigated and the optimum parameters are determined. The coke oven gas reacts with the recycled CO2 separated from the CO2-rich exhaust gas to produce syngas for synthetic natural gas production. This CO2 recycle can significantly improve the hydrogen utilization efficiency in coke oven gas, which does not only increases the synthetic natural gas production and thus enhancing energy efficiency, but also reduces the CO2 emission simultaneously. The results show that the energy and exergy efficiency (79.0% and 81.1%) of the new process is increased by 6.3 and 6.6 percent points, synthetic natural gas production cost and direct CO2 emission reduced by 0.05 US$/m3 and 99.9%, whereas the synthetic natural gas output increased by 20%, in comparison with the conventional coke oven gas to synthetic natural gas process. The proposed system provides a promising way for future improvements of coke oven gas to synthetic natural gas process, and can also be a guide for CO2 utilization or CO2 emission reduction in coking industry.
[en] Highlights: • A dynamic model for the hot blast stove system has been developed. • The developed model was validated with experimental measurements. • The effect of OxyFuel technique on the performance of hot blast stoves was studied. • Increasing the cycle time of a stove system can increase the blast temperature. - Abstract: A large amount of energy is required in the production of steel where the preheating of blast in the hot blast stoves for iron-making is one of the most energy-intensive processes. To improve the energy efficiency of the steelmaking it is necessary to investigate how to improve the hot blast stove operation. In this work a mathematic model for evaluating the performance of the hot blast stove was developed using a finite difference approximation for the heat transfer inside the stove during operation. The developed model was calibrated and validated by using the process data from hot blast stove V26 at SSABs plant in Oxelösund, Sweden. The investigation shows a good agreement between the measured and modelled data. As a case study, the developed model was used to simulate the effect of a new concept of OxyFuel technique to hot blast stoves. The investigation shows that, by using this OxyFuel technique, it is possible to maintain the blast temperature while removing the usage of coke oven gas (COG). The saved COG can be used to replace some fossil fuel, such as oil and LPG. Furthermore, the effect of the cycle time on the single stove was studied. As expected, both the hot blast and flue gas temperatures are increased when increasing the cycle time. This shows that it is a good strategy for the hot blast stove to increase the blast temperature if the stove is currently not operated with the maximum allowed flue-gas temperature.