Study On Production Process Of Acrylic Fiber "Five-effect Evaporation" Device

Multi-effect evaporation system is the common approach for concentration and separation of solid dilute solvent,which is widely used in the field of chemical,medicine,light industry and environmental protection.In this thesis,we proposed the common testing method of the five-effect evaporation system.The testing route line contains the following steps: single engine test,vacuum test,cold water operation,hot water operation,parameter adjustment,fault elimination,batching,feeding operation,concentration control correction,process improvement.Moreover,the technical adjustment and parameter optimization are carried out for the vacuum test,cold water operation,hot water operation with loading and feeding operation of five-effect evaporation system to meet the technological requirements of the system operation.The vacuum value of the multi-effect evaporation system is the key factor to obtain the qualified concentrate solution.The measurement method of the vacuum value is discussed in detail.By the method to measure the vacuum degree and eliminate leakage points,the vacuum value of the whole system can be guaranteed to reach the standard.Operations of cold water,hot water with loading and running test of multi-effect evaporation system must be mastered by a skilled operators,and these stages are very important to set controller parameters and test the stability of equipment operation.Meanwhile,problems in various stages of operation should be solved reasonably.We present the operation steps of the devices and problem-solving program for dealing with the troubles in the process of operation according to the actual production condition of company.High-quality sodium thiocyanate crystal was required to use in the device,which lead to increase cost due to its high price.It is necessary to reduce the waste of raw materials and energy in the operation of the device.Therefore,we proposed the dosing process of sodium thiocyanate solution systematically for completing the operation in an efficient and convenient way,including the calibration of storage tank,dosing operation,adjustment and test of material liquid concentration to reduce the waste of raw materials,labor,time and energy.In this project,whether the main control parameters(discharge concentration and quantity,ratio of steam and water,salt content in the condensed water,etc.)meet the process design value and production requirements were mainly examined through manual operation with materials andautomatic multiple operation process.And we focused on the discussion whether concentration control relationship provided by the original design can meet the process requirements under automatic control.As a result,it is proved that the original designed logic relationship of concentration control cannot be satisfied with the device.Therefore,the new logical relationship of concentration control was updated and verified through the collection and analysis of the actual operation data of the five-effect device.Under the multiple controls,the final controlled value of the discharge concentration achieved the technical requirements of the device.