| With the continuous improvement of market demand and production technology,"four new"in chemical production process,namely new technology,new process,new material and new equipment,are also emerging“The emergence of"four new"improves the production efficiency of enterprises and enhances the competitiveness of enterprises.However,due to the lack of sufficient understanding of"four new",it is rashly applied to production practice.Once the process is out of control,it is easy to cause serious production safety accidents.Therefore,it is urgent to use scientific methods to analyze the safety of"four new"before putting into operation,and put forward corresponding safety countermeasures to prevent accidents,so as to ensure the safe and stable operation of the whole chemical process.Based on the safety system engineering,this paper aims at the safety problem of high temperature drying process of a new compound fertilizer product-calcium dihydrogen phosphate mixture containing sulfur(mass fraction of 12%)(hereinafter referred to as sulfurized dicalcium),and studies the material danger and the safety of drying process by using experimental and numerical simulation methods.The process safety control,accident active defense technology and chain breaking disaster reduction technology of high temperature drying of new materials were studied from the aspects of thermal decomposition behavior of mixture at high temperature(up to 800℃),explosive property of mixture dust,influence of drying process parameters on oxidation combustion of sulfur dust and inerting protection.(1)According to the proportion of the product requirements,the sulfurized heavy calcium sample was prepared in the laboratory,and the actual drying and heating process was simulated through a tube furnace,and the temperature range was 250°C to 800°C with a step of 100°C.The thermal decomposition products at different temperature ranges were analyzed,and the pyrolysis products were analyzed by XRD technology.At the same time,the inhibitory effect of calcium dihydrogen phosphate on sulfur oxidation and combustion was analyzed in combination with TG-DTG.Use a 20L Siwek spherical explosive device to explode the sulfurized heavy calcium dust according to the dust concentration of 100g/m~3,200g/m~3,300g/m~3,500g/m~3,800g/m~3,1500g/m~3,1900g/m~3,2000g/m~3Sexual analysis.At the same time,the amount of dust generated in the dryer is monitored and statistics,and the oxygen content inside the dryer is obtained by material balance calculation.It is found that heavy calcium,namely calcium dihydrogen phosphate,has a flame retardant and explosion-inhibiting effect on sulfur dust,but this effect is related to the initial temperature,and there is a danger of sulfur dust burning inside the dryer.(2)Since sulfur dust oxidation and combustion still occur inside the dryer,the computational fluid dynamics CFD simulation method is used to construct a dryer model,which simulates the temperature field distribution inside the dryer during the drying of wet particles,and can be controlled in actual production.The process parameters include drying air velocity,drying air temperature,and oxygen content of drying air as boundary conditions to numerically simulate the sulfur combustion inside the dryer.It is found that when the air velocity is 10m/s,the airflow temperature is 600℃,and the oxygen content is 1%,the sulfur combustion can be effectively controlled.(3)In order to improve the intrinsic safety of the process,numerical simulation was used to study the inhibitory effect of nitrogen and carbon dioxide on sulfur dust explosion.And design the interlocking of the inert gas generation system and the DCS of the drying process to form an accident active defense and broken chain disaster reduction technology.It is found that under the same mass flow,nitrogen has better suppression effect on sulfur dust explosion than carbon dioxide.The main reason is that the specific heat capacity of nitrogen is greater than that of carbon dioxide,which can absorb more heat in the same time. |
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