Instrument Type Choosing And Control System Designing For The Shifting Section Of A Synthetic Ammonia Plant

Synthetic ammonia industry was born in the early 21st century,which its scale has been to the direction of large and medium-sized development.At present,large-scale ammonia production accounted for more than 80%of the world's total ammonia.Synthetic ammonia is one of the most important inorganic chemical products,and the associated economy occupies a very important position in GDP of China.Synthetic ammonia industry has been renowned as the basis of modern chemical industry.Except the broad use of synthetic ammonia industry in agriculture,its products play a significant role in industry,national defense,improvement of people's live quality and some other aspects.According to the status quo and current situation of the production of synthetic ammonia industries in China,the ammonia plants which were built at the beginning of the founding of the PRC has adopted the Central Control Room and set up them independently.In recent years,with the development of the automation technology,the domestic and foreign distributed control system manufacturers have developed different types of DCS that operate with stability and smoothness.In this way,most of the new ammonia plant can achieve centralized control of the system.?1?In this paper,a reference to a chemical plant in Henan is evaluated,which is a productivity of 600,000 Tons per year synthetic ammonia project with some auxiliary projects.It adopted the crude raw gas as the material.In the analysis of the basic process of ammonia production process on the basis of the various sections of the instrument in the comparison,classification,selection,adopt the Zhejiang University DCS for ammonia project configuration.Complete the design of the whole automatic control project.?2?This article mainly focuses on the Shifting section along with the introduction to the process and critical instruments selection.There are two types of thermometers that are used in this section.They are thermal resistance and thermocouple temperature measurement instruments.During the start-up,the infrared gun is used to the CS₂ temperature measurement.The remote transmitters uses pressure transmitter.And for the viscous,corrosive and toxic media,diaphragm sealed pressure transmitter is used.According to the different media and different conditions,some ordinary pressure gauges,stainless steel pressure gauges and seismic pressure gauge are selected.Flow meters are considered as some kind of instruments that selection is even more difficult than manufacture.In this project,a criteria is admired that same types of flow meters are largely selected.However,there are almost 10 different types of conventional flow meter transmitter.For the conventional types of flow meters,differential pressure flow meters transmitter are used,such as vortex flow meters are used for medium pressure and low temperature stream flow.As the factor that there are restrictions in terms of temperature for the use of vortex flow meters,the Delta Pakistan flow meters are used in high temperature and high pressure steam flow.For the most of circumstances,gas Delta bar flow meters are given priorities to be selected.Metal tube rotor flow meters are used to measuring small diameter fluid flow.Conductive fluid such as desalination water can be measured by electromagnetism flow meters.There are a large quantity of towers and other containers.Their liquid levels are measured by magnetostrictive level gauge and magnetic flap level gauge respectively.In the boiler section of the coal warehouse level measurement,radar level instruments are selected.In terms of valve selection,in order to reduce the investment and probability of failure during the operation,simple single-seat through valves are selected.For the requirements of valves with large diameter,resistance to high temperature,resistance high pressure and high shut-off differentiation pressure,domestic valves are fail to meet all those requirements,therefore well-known foreign products are adopted.Zirconia analyzer and infrared analyzer are used for online analytical instruments.?3?ZheJiang University JX-300XP is adopted for control system,which is ranked in medium to high position in similar products in the domestic and foreign markets.As there are a large number of configuration contents and similarities amongst them are identified,the system configuration demonstration is only conducted to pressure indicative adjustment of heat exchanger of Shifting section.?4?At present,the project has been put into operation,and achieved good results,the basic design requirements.