On-line soft measurement method of pH value and H2 S03 concentration in acrylonitrile polymerization system

Abstract

The present invention relates to an on-line soft measurement method of pH value and H2SO3 concentration in polyacrylonitrile polymerization system under the sodium-chlorate-sodium bisulfite initiating system. It is characterized by that it utilizes the simulation experiment of NaClO3-NaHSO3 oxidation-reduction initiating system under the condition of operation in the course of acrylonitrile polymerization to make the obtained experiment result undergo the processes of mathematical regression and normalization treatment to obtain an integrated quantitative mathmatical expression formula of 5 operation variable quantities and pH value and H2SO3 concentration in said polymerization system: in which (ci, i=1,2,...4) and D (di, i=1,2,...4) are moded fitting parameter vector, lambda (lambda i, i=1,2,...4) and gamma (gamma i i=1,2,...4) are model fitting parameter matrix x is input vector, i.e. operation variable quantity, after calculation, the real time result of pH value and H2SO3 concentration in the acrylonitrile polymerization system can be obtained.

Description

technical field [0001] The invention relates to on-line soft measurement technology, in particular to a pH value and H value in an acrylonitrile polymerization system under a sodium chlorate-sodium bisulfite initiation system 2 SO 3 On-Line Soft Sensing Methods for Concentration. Background technique [0002] Polyacrylonitrile is the basic raw material for acrylic fiber production. Polyacrylonitrile aqueous two-step wet process has been put into operation in some factories in my country for many years. The key stage in its production process that determines the quality of acrylic fiber products is the polymerization reaction. The process adopts aqueous precipitation polymerization, which terpolymerizes acrylonitrile (AN) with methyl acrylate (MA) and sodium methacrylate (A1). The copolymerization reaction goes through a multi-step reaction process including chain initiation, chain growth, chain termination and chain transfer. In this way, each small acrylonitrile molecu...

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Problems solved by technology

[0007] However, due to various reasons, the current process equipment generally has no detection means for the above two important process parameters, so it is also impossible to have a deep and real-time understanding of the polymerization process, so that in actual production, often occur due to various Slight perturbations in feed amount and ingredient ratio lead to changes in polymerization parameters, making the quality of subsequent spinning unstable, but for no reason

[0008] The pH value of the polymerization system is mainly related to many factors such as system composition, reaction temperature, and water quality of the dispersed phase, and no comprehensive correlation equation related to each operating condition has been found so far.

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