مجله فرآیند نو
پیاپی 41 (بهار 1392)

The importance of syngas production in the synthesis of synfuels and chemicals is likely to increase in the future, and this appears to be the most promising route to synfuels. This is illustrated by the increase of the projects related to the use of synthetic fuels. This article investigates the different methods of producing synthesis gas. First, old methods including, steam reforming, partial oxidation and autothermal reforming are investigated and than new methods as dry reforming of methane, ethane, ethanol, propane and dimethyl ether and mixed processes are surveyed and compared, and finally, the applications of synthesis gas are presented.

At the present time by growing public awareness and concern regarding the threat to people and the environment from industrial activities, the management has been forced to increase safety level. Hazard and Operability (HAZOP) study is the most widely used methodology in the world as a tool for hazards identification. The rector-furnace is one of the most important parts of sulfur recovery unit (SRU). About 54% of the total sulfur yield is formed as elemental sulfur vapor in the reactor furnace. This paper presents hazard evaluation for reactor-furnace by using HAZOP procedure. All of the deviations have been considered by HAZOP team and the recommendations are suggested to reduce the likelihood of consequences that mostly are related to the environmental risk. The principle problems of sulfur recovery unit are related to temperature decrease or increase of reactor-furnace which can lead to severe damages to the following parts and environment.

Using a thermal multi-effect desalination (MED) system for sea water desalination in areas facing with a shortage of appropriate drinking, agricultural or industrial water is a way to get fresh water, which acts on the basis of the evaporation- distillation methods. The incoming seawater temperature together with the other factors is among the main parameters affecting the efficiency of these systems. In this study, to increase the efficiency of the MED system we have presented a new proposal, which includes two condensers and a heat exchanger, and is used to increase the temperature of the input feed. In addition to reduce steam consumption through vapor condensation exited from the flash tank in an attached condenser, the rate of the fresh water production also increases by the proposed design. Mathematical modeling on the basis of mass and energy balance equations, which is implemented in MATLAB software, is used to investigate the influence of various parameters on the efficiency of the process. The modeling results show that the performance ratio (PR) of a multi-effect process with a low and a high number of steps will be increased by using the proposed procedure more than one and 3.5 units, respectively. According to the results, the temperature of the steam entering the first effect has been chosen to be 60oc. Furthermore, With regard to the concentration factor and thermocompressor efficiency, the optimal effect count of stages will be 3. The number of effects will be decreased to 2 ones, if the new system works with the same performance ratio of old system.

The main purpose of splitter tower process of pentane unit is to separate pentane gas from light gasoline as a valuable and value-added product. Having knowledge of the product quality is necessary to help proper process control, more production and sale and ultimately more profit margins. For this purpose the process must be identified. In this study the Splitter Tower is identified. In this paper, in addition to studying different identification methods and studying how the pentane unit works, the new model based identification and estimation methods are implemented. These methods include implementation of intelligent control technology based on soft computing techniques such as neural networks. Using these model based methods, a comparison between two different methods is carried out and the best one is chosen. To build a system model the identification using nonlinear intelligent methods such as MLP and RBF neural networks have been examined. Finally, the best one with the least mean square method is introduced.

Sulfur is one of the most important by-products of oil and gas processing industries which is used for various applications such as sulfuric acid production and agricultural issues. Therefore, boosting the sulfur recovery efficiency of industrial scale units (particularly Claus based Units), has attracted much attention during recent years. ProMax®, is a well known simulator for researching the gas industry processes particularly sulfur recovery units (SRUs). Although, numerous researches have been published by means of simulating SRUs with ProMax, however, the effect of benzene, toluene, and xylene (BTX) compounds have not been taken into account on the catalyst deactivation and overall sulfur recovery of SRUs. In this article, while simulating Khangiran natural gas refinery SRUs, shortcomings of the ProMax simulator in the presence of BTX compounds are investigated and proper modifications are considered to improve the simulation results.

The most important view points of petroleum refining industries in the near future are: supplying the cleaner fuels growing market, gradual substitution of increasingly rare refinery feeds of light-low sulfur crude oils, by heavy-high sulfur petroleum, and paying attention to the descending demand for heavy fuel oil. One solution of the above problems is the use of heavy residue upgrading processes. Economic and strategic reasons confirm the exploitation of refineries heavy residue and vast heavy petroleum and very heavy petroleum resources. In this manner, the selection of proper processes is a major challenge for petroleum refiners. This article introduces the most suitable ones as: Delayed Coking, Integrated Combined Cycle & Gasification, Residue Catalytic Cracking\ and Slurry Hydrocracking (Hydro-Conversion) for the Islamic Republic of Iran refineries.