The characteristics of recycling gas drilling technology

Recycling gas drilling is a new drilling technology. This paper can be divided into three parts, with the purpose of introducing and analyzing the characteristics of this new technology. First, the major equipment characteristic of this technology was introduced. Secondly, compared with conventional gas drilling, Angel＇s model was used to analyze the wellbore flow characteristics. Due to the closed loop and the effect of back pressure caused by the equipment, the gas flow rate decreases dramatically during drilling. Apart from this, it is also found that the kinetic energy at the casing shoe is always smaller than that at the top of the collar. The proposing of the drilling limit concept points out the basic difference between the two gas drilling technologies. Lastly, according to the results of the theoretical analysis, gas supplement operations for the wellbore must be conducted. Thus, two gas supplement schemes are presented in this paper, to provide some guidance for field operations.

Application of response surface methodology for optimization of purge gas recycling to an industrial reactor for conversion of CO_2 to methanol

Nowadays, by the increasing attention to environment and high rate of fuel production, recycling of purge gas as reactant to a reactor is highly considered. In this study, it is proposed that the purge gases of methanol production unit, which are approximately15.018 t·h^(-1) in the largest methanol production complexes in the world, can be recycled to the reactor and utilized for increasing the production rate. Purge gas streams contain 63% hydrogen,20% carbon monoxide and carbon dioxide as reactants and 17% nitrogen and methane as inert. The recycling effect of beneficial components on methanol production rate has been investigated in this study. Simulation results show that methanol production enhances by recycling just hydrogen, carbon dioxide and carbon monoxide which is an effective configuration among the others. It is named as Desired Recycle Configuration(DRC) in this study. The optimum fraction of returning purge gas is calculated via one dimensional modeling of process and Response Surface Methodology(RSM) is applied to maximize the methanol flow rate and minimize the carbon dioxide flow rate. Simulation results illustrate that methanol flow rate increases by 0.106% in DRC compared to Conventional Recycle Configuration(CRC) which therefore shows the superiority of applying DRC to CRC.

PRODUCTION METHODS AND APPLICATIONS FOR HIGH-QUALITY METAL POWDERS AND SPRAYFORMED PRODUCTS

Metal powders of superlative quality, i.e. high cleanliness, rapidly solidified and spherical shape, have seen an increasing demand in the market. The leading technology for the production of such powders is the inert gas atomization of metal alloy melts. To fulfill these requirements, the metal alloy is usually produced in a vacuum induction melting furnace (VI-GA = vacuum induction melting/gas atomization) and poured by means of a preheated tundish system into a gas nozzle where the metal stream is disintegrated by a high kinetic energy inert gas jet. The produced micro-droplets solidify in a free fall inside the atomization tower. For special applications, super-clean and ceramic-free metal powders can be produced by using the EIGA (electrode induction melting/gas atomization) melting- and atomizing system. As an alternative to the metal powder route, the sprayforming technology allows to produce semi-finished products in one step. In this case, the metal droplets produced by the high-energy inert gas nozzle system are directly solidified on a substrate, allowing to form billets, rolls and tubes.

Operating condition influences on PCDD/Fs emissions from sinter pot tests with hot flue gas recycling

This study was designed to clarify the influence of operating conditions on the formation and emissions of polychlorinated-p-dibenzodioxins and dibenzofurans （PCDD/Fs） from a sintering process with hot flue gas recycling. A pilot scale sinter pot with simulated flue gas recycling was developed, and four key operational parameters, including temperature, oxygen content of the simulated waste flue gas, the coke rate of the sintering mixture, and the quicklime quality, were selected for exploring PCDD/Fs formation. The results showed that the temperature of the recycled flue gas had a major affect on PCDD/Fs formation, and a high temperature could significantly increase their formation during sintering. A clear linear correlation between the temperature of recycling flue gas and PCDD/Fs emission （r = 0.93） was found. PCDD/Fs could be reduced to a certain extent by decreasing the level of oxygen in the recycled flue gas, while sintering quality was unchanged. The coke rate had no significant influence on the formation of PCDD/Fs, but the quality of quicklime used in the sintering mixture could affect not only the amount of PCDD/Fs emissions but also the sintering productivity. Compared with a benchmark sinter pot test, PCDD/Fs emissions markedly decreased with improvements to quicklime quality. However, the reduction in PCDD/Fs emissions realized by using high-quality quicklime was limited by the temperature of the inlet gas. The highest reduction achieved was 51% compared with conventional quicklime when the temperature of the inlet gas was 150°C.

Medium oxygen enriched blast furnace with top gas recycling strategy

Top gas recycling oxygen blast furnace（TGR-OBF）process is a promising ironmaking process.The biggest challenge of the TGR-OBF in operation is the dramatic decrease of top gas volume（per ton hot metal）,which once led to hanging-up and shutdowns in practice of the Toulachermet.In order to avoid this weakness,the strategy of medium oxygen blast furnace was presented.The maneuverable zone of the TGR-OBF was determined by the top gas volume,which should not be far from the data of the traditional blast furnace.The deviation of ±12.5% was used,and then the maneuverable blast oxygen content is from 0.30 to 0.47 according to the calculation.The flame temperature and the top gas volume have no much difference compared to those of the traditional blast furnace.The minimum carbon consumption of 357 kg per ton hot metal in the maneuverable zone occurs at the oxygen content of 0.30（fuel saving of 14%）.In the unsteady evolution,the N2 accumulation could approach nearly zero after the recycling reached 6 times.Thus far,some TGR-OBF industrial trials have been carried out in different countries,but the method of medium oxygen enriched TGR-OBF has not been implemented,because the accumulation of N2 was worried about.The presented strategy of medium oxygen enriched TGR-OBF is applicable and the strategy with good operational performance is strongly suggested as a forerunner of the full oxygen blast furnace.

Comprehensive Mathematical Model and Optimum Process Parameters of Nitrogen Free Blast Furnace

According to different energy utilization in different regions, blast furnace is divided into raceway zone, bottom heat exchange zone （BHZ）, thermal reserve zone （TRZ）, and top heat exchange zone （THZ）, and a mathe- matical model of nitrogen free blast furnace （NF-BF） is established. The optimum process parameters of two kinds of nitrogen free blast furnaces are calculated by the new mathematical model. The results show that for the nitrogen free blast furnace with a single row of tuyeres, the optimum process parameters are coke ratio of 220 kg/t, coal ratio of 193 kg/t, and volume of recycling top gas of 577 m3/t; for two rows of tuyeres, the process parameters are coke ratio of 202 kg/t, coal ratio of 211 kg/t, volume of recycling top gas in upper area of 296 m3/t, and volume of recy- cling top gas in lower area of 295 ma/t. Energy balances are reached in different regions. Theoretical combustion temperature （TCT） in raceway zone is largely affected by different processes, and a lower TCT should be adopted for the single row of tuyeres, but for two rows of tuyeres, a higher TCT should be maintained. Compared with tradi- tional blast furnace, in NF-BF, the emission of CO2 would be reduced by 45.91% and 49.02G for a single row of tuyeres and two rows of tuyeres, respectively, and combined with CO2 sequestration technology, zero emission of CO2 could be realized.

NICE's Indirect Coal-to-Liquid Process for Producing Clean Transportation Fuels Using Fischer-Tropsch Synthesis

China is currently the world's top coal consumer and the largest oil importer to sustain its rising economy and meet the mounting demand for transportation fuels.However,the increasing emissions due to the huge fossil fuels consumption,coupled with oil market instability,could derail China's economic growth and jeopardize its national energy security.To face such a hurdle,China has been aggressively supporting low-carbon businesses opportunuties over the past decade,has recently announced several plans to cap coal utilization,and is currently the biggest investor in clean energy technologies.Coal-toLiquid(CTL) is one of the most promising clean coal technologies,offering an ideal solution that can meet China's energy demands and environmental expectations.It is widely known that the Shenhua Group has pioneered and is currently leading the commercialization of the Direct Coal Liquefaction(DCL) process in China.This paper highlights a part of the joint research effort undertaken by the National Institute of Clean-and-LowCarbon Energy(NICE) and University of Pittsburgh in order to develop and commercialize the Indirect Coal Liquefaction(ICL) process.In this mission,NICE has built and operated an ICL plant including a large-scale(5.8-m ID and 30-m height) Slurry-Bubble-Column Reactor(SBCR)for Fischer-Tropsch synthesis using iron catalyst.The research,conducted at the University of Pittsburgh over the past few years,allowed building a user-friendly Simulator,based on a comprehensive SBCR model integrated with Aspen Plus and is validated using data from the NICE actual ICL plant.In this paper,the Simulator predictions of the performance of the NICE SBCR,operating with ironand cobalt catalysts under four different tail gas recycle strategies:(1) direct recycle;(2) using a Pressure Swing Adsorption(PSA) unit;(3) using a reformer;and(4) using a Chemical looping Combustion(CLC) process,are presented.It should be mentioned also that our joint research effort has laid the foundation for the design of a commercial-scale SBCR for producing one-million tons per annum of environmentally friendly and ultraclean(no sulfur,no nitrogen and virtually no aromatics) transportation fuels,which could greatly contribute to ensuring China's national energy security while curbing its lingering emission problems.