USE OF SIMULATION MODELS FOR OPTIMIZATION OF THE CONTACT APPARATUS WORK IN THE SULFURIC ACID PRODUCTION

Abstract

In the modern world, in connection with the rapid development of computer technology and software widely used A far of processes in chemical industry is continuous and a production lasts twenty-four-hour. The stop of such processes results in considerable economic losses. Realization of active experiment on a production is complicated (through the necessity of stop of productive process and risk of damage of industrial equipment a researcher). Realization of passive experiment often does not give to the researcher of sufficient information about the looked after object (through the very small rejections of entrance signals of object and impossibility of influence a researcher on every entrance signal separately). An attractive alternative in this case is creation of simulation model.The aim of the article is a publication of results of the use of simulation models for optimization of work of pin vehicle in the production of sulphuric acid.Creation of simulation model settles many problems. There is possibility to set any values of entrance signals independent of each other. There is possibility to design emergency situations. In the modern world, transients in chemical industry last during many hours. By means of computer simulation models information about a transient it is possible to get almost instantly (depending on the amount of calculations and power of the computing engineering).Of long duration continuous process the process of pin oxidization can exemplify in the production of sulphuric acid. Oxidization of sulphureous anhydride SO2 in sulfuric SO3 takes place in pin vehicles at the presence of vanadium catalyst. Into a vehicle there are four layers of pin mass. Pin mass is placed on grates. One of basic indexes of quality of work of pin vehicles there is a degree of contact xp, which is calculated on a formula.As evidently from the results of design, the identical values of middle temperatures (levels) are situated along direct. This surface can be used for development of the system of automatic control. Will set the problem to support such temperature condition at which a middle temperature would be in the second area (green area). Thus a management would be near to optimal and there would not be a risk of stop of reaction in case of sudden hit in the area of stop of reaction (white area).On the real object the system of automatic control supports the stationary temperatures of gas on an entrance to every layer of pin mass (catalyst). As a rule gas temperatures on entrances to every layer lie within the limits of 420-450 °C. A maximal temperature on an exit from the layer of catalyst folds close 600 °C. Decline of gas temperature to 400 °C and below given to the stop of reaction (and it is impermissible in a continuous production). Transients in a pin vehicle last a few hours. The new start of process stipulates the considerable losses of time (id est is a loss). Increase of temperature to 650 °C and higher results in the overheat of catalyst to his spoilage. In this case it is necessary to stop a process and replace a catalyst (and these are very considerable material charges). Realization of active experiment is simply impermissible clearly, that. A simulation model enables how pleasingly to influence on a temperature condition into a pin vehicle. There is possibility to investigate temperature conditions near to the emergency (at a temperature on an entrance to one of layers of catalyst close or to the temperature on an exit from one of layers of catalyst close 650 °C).For creation of simulation model it is necessary foremost to formalize an object. For the mathematical design of behavior of object (dynamics and statics) it comfortably to use the system of differential equalizations. Differential equalizations can be got analytically from material balances. It is also possible to get differential equalizations after treatment of results of passive or active experiment. On results the conducted imitation design it is possible to do next conclusions:1. An object is almost not sensible to short-term indignations. Id est there is not a necessity to design the system of automatic control with a high fast-acting. Recommended to steel of time for control system by a concentration and gas temperature approximately equal to 10 minutes.2. Most dangerous for the process of pin oxidization is an increase of concentration of SO2. A nominal concentration is 7,4 %. At the increase of concentration gas must be diluted by air (for normalization of concentration). At development of the system of automatic control it follows to take into account next limitations: maximal static rejection of concentration ± 0,1 %; maximal dynamic (short-term) rejection of concentration ± 1 %.3. Desirable (near to optimal) are tasks of temperature and concentrations within the limits of the second area. Dependence between an optimal temperature and concentration entrance.