NU ENERGY - Cokemaking technology for future challenges
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Abstract
This paper deals with a technology for formed coke production. Milestones in the development of this technology are summarized. Then, the equipment and the process are described. The environmental impact is briefly addressed. The products obtained along the processes, including char, gas, liquids and coke are characterized, and possible applications are mentioned. As an example, an economical evaluation of a given project is detailed. Finally, a coke cost exercise is carried out.
Related papers
Coke and Chemistry, 2014
The influence of the production conditions on the properties of coke is considered. Coke is pro duced in a pilot plant at the Institute of Technical Chemistry, Ural Branch, Russian Academy of Sciences, in a 200 L reactor equipped with an air supply valve and heating elements. The first stage in coke production is air blowing of the batch with constant temperature rise at 10-12°C/h from 290-310°C; the air flow rate is 45-55 L/kg h. At this stage, the final air blowing temperature and the batch composition are varied. The sec ond stage is coking, with temperature rise at 25°C/h to 550-600°C. The batch consists of industrial air blown pitch (ABP), modified by pitch tar (PT). Oxidation of the ABP, even with a very high final temperature (434°C), does not permit the production of isotropic coke. An analogous result is obtained on adding small portions of PT to the batch (15%). On adding >50% PT, totally isotropic coke may be produced. To obtain coke of isotropic microstructure, the optimal content of PT is 36-41%, and the final air blowing temperature should be high (>390°C). The influence of PT on the structural parameters of the coke is associated with the formation of nonmesogenic structures on air blowing. On coking, these structures suppress the growth of large mesophase. The isotropic coke produced has the following characteristics: limited expansion in the range 1300-2400°C; high structural strength; and optimal density. Graphite based on such coke is consider ably superior to graphite based on industrial pitch coke in terms of its compressive strength, density, and elec trical resistivity.
2007
A series of coking coals covering a wide range of coalification, thermoplastic properties and geographical origin were carbonized at two different scales. All the coals used are available in the international market and they are used by the cokemaking industry in blend preparation. The cokes were produced in two movable wall ovens of 15 and 300 kg capacity available at INCAR-CSIC facilities. The quality of the cokes was assessed by means of reactivity towards carbon dioxide and mechanical strength before and after the reaction with CO2. The results obtained are very promising and a good correlation between the quality parameters of the cokes produced in the two ovens was found. The use of a semi-pilot oven against big-capacity ovens in the optimization of complex coking blends allows to obtain valuable results by using small amount of coal (15 kg vs. 300-400 kg) with the advantages that it is quicker, more flexible and of lower cost.
This paper is an update of a previous publication in Spanish [1]. One of the current trends in the production of metallurgical coke is the comeback of non-recovery ovens. This is driven by less interest in byproducts, smaller investment per annual ton, better environmental performance. The development took place particularly in China, India, USA, Brazil, Australia and Colombia [2]. In the USA, one important factor promoting this technology was that EPA declared it as Maximum Achievable Current technology in 1990. This technology arises from the classic beehive ovens which supplied since the XVIII century the coke for the industrial revolution. Those ovens were manually operated, with small heat recovery, just for heating the oven. Now, non-recovery ovens are modern construction, with highly mechanized operation, and automated to a certain degree. Gases generated by the combustion of the volatile matter are sent through downcomers and further burnt to heat the oven bottom and sides; in many cases, mostly when the plant is built within or closed to a steelmaking facility, the hot gas is used for vapor generation and electric power production. Main differences between conventional and non-recovery/heat recovery processes are shown in figure 1. In conventional process, the coal charged receives the heat indirectly through the furnace walls, by combustion of external gas; inside the oven, positive pressure develops. Gas generated in the coking process is sent to the by-products plant. In non-recovery ovens, coking proceeds from the top through direct heating by the partial combustion of the volatile matter over the coal bed, and from the bottom by heat coming from full combustion of gases escaping from the oven. In these plants, the offgas is treated and sent to the stack, in many cases after recovering sensible heat to produce vapor and electric power. Installed capacity for these furnaces was esteemed in 2005 in 22 M metric tons per year, probably including beehive ovens [2]. In table 1, some of the non-recovery coke plants currently operating are listed. Some plants belong to companies with coal mining as its core business; others are independent coke producers, purchasing coal and selling coke; then there is some joint ventures between coke producers and steelmakers, and finally, captive coke plants belonging to steel companies.
2016
The efficient energy use of Coke Oven Plant is considered in this paper. The main objective is the reduction of energy consumption and reducing CO2 emissions per production unit by use of waste heat for various needs of production site demands. The considered process consumes the external hot utilities 25.4 MW and cold utilities 24.9 MW. The use of waste heat for district heating and hot water supply allow reducing the external cold utilities by 23.5 MW. This heat can be used for heating of 1,869,825.6 m in apartment buildings, municipal facilities, shopping malls and etc. The use of waste heat from flue gases for electricity production allows obtaining additionally about 7.5 MW of power that can be utilized for production needs and exported outside. The provided case studies show the pathway for an efficient retrofit of coke production and most profitable ways for investment.
Procedia Environmental Sciences, 2013
In this paper a multifunctional energy system (MES) is proposed for recovering energy from the extra of coke oven gas (COG), which is usually flared or vented out as a waste stream in coke making plants. The proposed system consists of a pressure swing adsorption (PSA) unit for extracting some of the hydrogen from COG, a gas turbine for producing heat and power from PSA offgas and a heat recovery steam generator (HRSG) for generating the steam o assess the performance of the system practically, simulations are carried out on the basis of the design and operational conditions of Zarand Coke Making Plant in Iran. The results indicate that by utilizing about 4.39 tons of COG per hour, 6.5 MW of net electric power can be approximately produced by the gas ied by the HRSG unit. It is also found that around 350 kilograms per hour of nearly pure hydrogen (99.9% purity) at 200 bar can be produced by the PSA unit. According to the sensitivity analysis results, if the hydrogen content of the coke oven gas decreases by about 10%, the gross power output of the gas turbine also declines by around 5.2% due to the reduction of LHV of the PSA offgas. Moreover, economic evaluation of the system shows that the payback period of the investment, which is estimated at 36.1 M$, is about 5.5 years. The net present value (NPV) and internal rate of return on investment (ROI) are calculated to be 17.6% and 43.3 M$, respectively.
Proceedings of the Conference on Broad Exposure to Science and Technology 2021 (BEST 2021), 2022
Indonesia's green petroleum coke production capacity reaches 360,000 tons/year. Green Petroleum Coke (GPC) is the most widely used raw material in the manufacture of anodes for aluminium and steel smelters, but it is does not have good quality for smelting because it contains high ash, volatile matter and carbon. It is necessary to produce CPC that meets industry standards. Calcined Petroleum Coke (CPC) is produced from calcined coke technology by heating coke to a high temperature of 550-1,150 °C using a rotary kiln or vertical shaft kiln. The calcination process mostly determines the characteristic quality of the petroleum coke produced. This study will compare the advantages of product characteristics resulting from calcination technology between rotary kilns and shaft kilns and analysed calcined coke using Aspen Plus to produce high quality coke products that meet industry demand parameter standards; sulphur content (0.5-1.5%), fixed carbon (99.3%), volatile matter (0.5%) and ash (0.5%) and reduction of wasted CO2 gas emissions. thus can support the mining industry. Mining down streaming also encourages the country's foreign exchange savings and boosts the domestic economy. Thus, Indonesia can produce economical steel and smelters.
In this study, the production of ethylene and hydrogen is studied via the thermal cracking of ethylene in an ethylene plant based in Libya. During the process of thermal cracking, a mix of naphtha and steam is input into tubes that are directed to the naphtha main line. The utilization of steam is generally used because of the partial removal of coke which has undesirable effects on the process. The coke accumulation on the coils, or tubes, result in a decrease in pressure and also reduction in the yields produced. In this work, the naphtha thermal cracking process is both designed and solved numerically. A thorough comparison of the design results and the data extracted from the experiment reveal that the design may predict the overall process precisely. Also, the direct effects of CO2 are studied with regard to the accumulation of coke. Based on the results of two separate scenarios, the process of thermal cracking with the CO2 is beneficial to the overall process due to the higher yield of ethylene and propylene, and less accumulation of coke, and, in turn, less thickness on the coils inside the furnace. The results from the simulation show that the run time, or run length, of the furnace with the addition of CO2 becomes almost two times as the run time with adding steam. Based on these results, this study has proven to be worthy to explore, and the addition of CO2 has been observed to have noticeably positive results on the thermal cracking process. Keywords: naphtha, ethylene, hydrogen, coke accumulation
International journal of …, 2006
The steam-gasification of petroleum coke using concentrated solar radiation as the source of high-temperature process heat is proposed as a viable transition path towards solar hydrogen production. The advantages are threefold: (1) the calorific value of the feedstock is upgraded; (2) the gaseous products are not contaminated by the byproducts of combustion; and (3) the discharge of pollutants to the environment is avoided. The thermodynamics and kinetics of the pertinent reactions are analyzed for two types of petroleum coke: Flexicoke and Petrozuata Delayed coke. The net process is endothermic by about 50% of the feedstock's LHV, and proceeds at above 1300 K to produce, in equilibrium, an equimolar mixture of H 2 and CO. A Second-Law analysis on the processing of this syngas to H 2 (by water-gas shift followed by H 2 /CO 2 separation) for power generation in a fuel cell indicates the possibility of doubling the specific electrical output and, consequently, halving the specific CO 2 emissions, vis-à-vis conventional coke-fired power plants. Kinetic rate laws are formulated based on elementary reaction mechanisms describing reversible adsorption/desorption processes and irreversible surface chemistry. The kinetic parameters and their Arrhenius-type temperature dependence are experimentally determined using a quartz tubular reactor containing a fluidized bed of petroleum coke in steam and directly exposed to concentrated thermal radiation. Syngas containing approximately an equimolar mixture of H 2 and CO and with a relative CO 2 content of less than 5% was produced at above 1350 and 1550 K for Flexicoke and Petrozuata Delayed coke, respectively.
Chicago Review, 1974
Various traditional and industrial coke making techniques were discussed based on their limitations and production capacities, and the criteria such as the quality and size of coke production, amount of coke crumb, amount of investment, amount of operational costs, labor force and mechanization. In this work, the rankings of various traditional and industrial coke making techniques were carried out using a multi-criteria decision making with technique for order preference by similarity to ideal solution (TOPSIS), in which, at first, industrial heat recovery coke oven, by product coke oven and non-recovery coke oven and then traditional beehive coke making was performed in Shahrood Simin Coke Company. The designed oven decreased both the environmental pollution and the amount of coke crumb, and increased the coke production and coke recovery qualities.
Applied Thermal Engineering, 2018
In order to predict the behaviour of the heat-recovery (HR) /non-recovery (NR) coke oven during the coke-making process, time-dependent numerical simulations have been carried out. A one-dimensional (1D), self-made (non-commercial) mathematical model has been used to predict temperatures, pressure and gas composition within upper-oven, downcomers and sole-flue of the oven analyzed. Moreover, mass flow rates of primary and secondary air, entrained from the surroundings, have been calculated. The results of the simulations indicate that the carbonization process performed in HR/NR ovens is slightly affected by surrounding conditions. A 15.8 % (from 253 K to 293 K) increase in surroundings temperature has resulted in a 0.6% of temperature change within the upper-oven and the soleflue. The same variation in ambient temperature affects slightly (0.3%) the primary and secondary air mass flow rate entrained from the environment. The increase in surroundings temperature reduces the natural draft by about 6 Pa, but pressure losses in the air ducts become higher. The usage of the so-called "sliding gates" installed in the primary and secondary air inlets is of great importance for coke-making. Changing the closure level of the primary air inlets by 25% causes the gas temperature to be altered by 4.3%. Another important factor is suction generated by a fan/stack. This parameter (suction increased by 40 Pa) changes the temperature inside the oven by about 9.7% for the upper-oven and 3.7% for the sole-flue. Both parameters have key significance for the carbonization process. The gathered data provides an improved understanding of the HR/NR coke oven operation and allows optimizing HR/NR coke oven design and the carbonization process itself.

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