Processing Research And Engineering Practice On Cyclic Preparation Of Cyanamide

As an important chemical,pharmaceutical and pesticide intermediates,currently cyanamide is produced from lime nitrogen by one step reactive evaporation process with high energy consumption and high risk,while the new low energy and safe lime nitrogen cycle method for the production of cyanamide is in the research phase.This thesis focuses on the processing research and engineering practice on cyclic preparation of cyanamide and has accomplished the following works:(1)On the basis of the research progress of the cyanamide production process and the comparison of advantages and disadvantages of the production process,the superiority of the cyclization process for the production of the cyanamide and the necessity for the company to use the cyclic method to construct the production equipment were proposed.(2)The production process of two raw materials lime nitrogen and carbon dioxide for cyanamide production was briefly described,and the latest production methods of lime nitrogen and CO2 were proposed.At last,the detailed analysis methods and consumption calculationsof two raw materials in the production process of cyanamide were performed.(3)After theoretical calculations and bench scale experiments,the important factors to influence the cyanamide production such as reaction time,reaction temperature and liquid to solid ratio L/S were determined.Then the pilot-plant experimentsvia the orthogonal method were used to determine the optimum reaction time,reaction temperature and L/S value.The parameters for process design,equipment selection and operation control were provided for the construction of pilot production line with production of 5t/a year by cyclic method.(4)After process calculation and equipment selection,the final design and construction of pilot production line with annual production of 5 t/a of cyanamide were completed.After summarizing the production process control indexand operating parameters of the trial production,the emergent production process problems due to the design,equipment selection,and equipment layout and equipment construction were optimized.After that,stable operation of the production process and equipment of the pilot production line were achieved and qualified cyanamide products were produced,which provided accurate design parameters for an annual output of 10,000 tons of cyanamide production.(5)The process design and equipment selection were performed and a complete construction plan was provided for the production line with annual production capacity of 10,000 tons.After completion of the mass scale production line,the trial production was carried out according to the operational parameters summarized in the pilot production line.The problems in the production processwere optimized again,and the operation and control parameters of the industrial production line were summed up,so that the production can be stable operation to produce qualified cyanamide products.And then stable production assessment for 72 hours runningwas performed,which includes the assessment of lime nitrogen consumption of ton raw materials,CO2 consumption,energy consumption of ton product and product quality.After the analysis of the advantages and disadvantages,the production line was put into commercial production running.Through the whole process studies of preparing cyanamide by lime nitrogen cyclefrom laboratory test and pilot to industrial mass scale of 10000t/a,the feasibility and reliability of the production process are demonstrated from theory to practice.Compared with the traditional production process,the new production process is characterized by less production process,simple process,easy process control,safeproduction,low energy consumption and high product quality.Through the whole process of research,it not only demonstrated the operation stability by use of the new production process to construct million-ton production plant,but also could effectively reduce the investment risk.Thus,the new production process is worthing of promoting in the domestic cyanamide industry.