Application case one of an online detection instrument for caprolactam concentration and acid-base concentration

In 2016, at the request of the user, it was required to adjust the concentration of caprolactam in the aqueous solution during the dehydration process in the caprolactam production processlineOnline real-time detection for users andMaster the control of product quality and improve the recovery rate of caprolactam. Through the study of the physicochemical properties and production process of caprolactam, there are high requirements for sensor materials, detection device accuracy, and data processing. We are on Beidou StarOn the basis of MS1204 microwave detection technology, through core technology improvements, it has been applied in the installation site of caprolactam production process. After several years of normal operation, the Beidou MS1204 sensor has expanded its practical field.

Application of Caprolactam Chemical Raw Materials

CaprolactamCPL is an important organic chemical raw material,It's nylon.-6 synthetic fibers、nylon-6 Engineering plasticsNylon -6 thin filmsThe important unit.

Nylon -6 fibers can be processed into civilian silk and industrial silk. Industrial silk is mainly used to make tire curtain fabric, cables, seat belts, parachutes, canvas, insulation materials, transport belts, etc. Civilian silk can be used to make textiles such as carpets, clothing, blankets, non-woven fabrics, bags, ropes, etc.

Nylon -Engineering plastics are widely used in fields such as automobiles, ships, industrial machinery, electronic and electrical components, etc.

Nylon -Thin films are mainly used for processing food preservation films and have a wide range of applications.

【Background technology:Caprolactam process flow

The main industrial processes for preparing caprolactam include phenol method, aminooximation processHydroxylamine phosphate(HPO)The toluene method（SNIA），Hydroxylamine sulfate method(HSO)Aminooximation method, etc. Regardless of the process method, the final product must be neutralized and separated by adding ammonia water. The crude caprolactam separated is then purified and refined to obtain a purity greater than99.98%The finished product of caprolactam.

To achieve high purity, the followingThe Journey of TravelProvide high-quality productsThe refining process of crude caprolactam solution is very important. Countries are constantly developing more economical and less polluting refining processes.

Important indicator of product quality: concentration of caprolactam

To achieve the desired purity of caprolactam,Crude caprolactam needs to be refinedworkmanshipThe current refining methods mainly involvefocus onSolution extraction method、 Ion exchange resin methodcatalytic hydrogenationMethod, vacuum distillation, etc. In order to obtain high-purity products, several methods are generally combined for joint refining in industry, in order to improve the quality and recovery rate of caprolactam.

withHydroxylamine phosphate(HPO) methodproductionCaprolactamfor example，thickCaprolactamofDehydration, concentration and refinementadoptEvaporative distillationThe law,Liquid phase Beckmann rearrangement process of cyclohexanone oxime catalyzed by fuming sulfuric acid. The liquid-phase Beckman rearrangement reaction generates crude caprolactam, which needs to undergo rearrangement neutralization, ammonium sulfate extraction and stripping, benzene extraction, water extraction, ion exchange, hydrogenation, triple effect evaporation, distillation and other processes for separation and purification before being refined to obtain qualified caprolactam products. Caprolactam concentration processEnteringTriple effect evaporation and pre distillationDuring the processConcentrate caprolactam to90% ，Enter againPre distillation system is used to adjust the concentration of caprolactamConcentrate 90% (mass fraction) to 99.9%，The removal rate of impurities has reached99.99%The concentration of crude caprolactam is passed through multiple channelsSeparation and purificationThe concentration of the process gradually increases and eventually reaches greater than99.98%The measurement of concentration values in different processes is an important indicator of process control.

【Technical implementation elements:Measurement of Caprolactam Concentration for Online Detection

To solve the real-time measurement and control of caprolactam concentration, the sensor needs to be directly inserted into the pipeline sampling point. Considering the complexity of the production process of caprolactam, the contact material must be temperature resistant and corrosion-resistant. Therefore, we have chosen polytetrafluoroethylene material, known as the "plastic king", which is resistant to acid, alkali, and various other substancesorganic solventofCharacteristic: Almost insoluble in all solvents. At the same time, it has the characteristic of high temperature resistance and can be used in-Long term use at 180-260 ° C is suitable for the application of caprolactam and its complex production processesAn economical and practical online monitoring instrument.MS1204Sensor applicable temperature range100-120°C;Concentration range:0-100% full range testingThe broad concentration measurement range allows for flexible installation and control in accordance with process requirements. Sensor insertion depth standard60～170 mm， Special requirements can be customized for pipeline and tank installation. Intrinsically safe design explosion-proof type. Can be directly used for displays, recorders, and can enhance PID closed-loop control;

Online concentration meterT-BD5CMD+MS1204pTesting principle

MS1204 microwave attenuation sensing technology, which is applied to the Beidouxing series moisture analyzer, is a highly reliable moisture testing technology developed and gradually improved by Beidouxing for 30 years, through several generations of experts from the Chinese Academy of Sciences, comparing the advantages and disadvantages of the existing technologies of detection principles at home and abroad.

The microwave attenuation method is based on the interaction between organic matter and water moleculesThe absorption rate of electromagnetic waves at 100MHz varies greatly（75:1）Designed based on the principle that moisture has a different absorption coefficient for microwaves compared to other media, when a high-frequency electric field is applied to the sample,Due to the presence of moisture, it can affect the phase and amplitude of high-frequency electric fields, and the degree of influence depends on the moisture contentBy testing the phase and amplitude changes of high-frequency electric fields, and through intelligent digital to analog conversion and related data processing, the requirements for fast and accurate detection have been achieved, solving the problem of other moisture detection principles being affected by factors such as electrolyte, organic composition differences, acidity and alkalinity, and sand content in the medium.

Beidou Satellite Instrument relies onMS1204 advanced detection technology was awarded the Beijing Torch Plan project in 1996. It is fast, convenient, easy to install, stable and accurate in data, and has become a high-quality domestic instrument for moisture detection that has been used by nearly a thousand users in various industries and at home and abroad for 30 years. It has been rated as the most competitive moisture analyzer by users, adding another mature testing technology to international moisture detection today.

selfIn 2008, at the request of domestic research institutes, petrochemical plants, and traditional Chinese medicine manufacturers, we began the on-site application development of concentration testing for ethanol, ethylene glycol, n-butanol, butanol, and dimethyl silicone oil. We have accumulated rich experience in the stability, anti-interference, and temperature effects of instrument testing, whether from the instrument itself or from on-site issues.

Beidou satellite moisture meterMS1204 Technical Advantages

1)No additional fees for consumables;

2)There is no harm to personal health from instruments and consumables.

3)The instrument has fast response speed and signal response time<15s, Intelligent transmitter processing interval, * adapted to the fast response requirements of automated processes.

4)Reliable explosion-proof design, with an explosion-proof rating ofEx d ia Ⅱ C T5 intrinsic safety design.

5)Flexible and practical installation structure design, diverse installation connection methods (pipe thread type, flange type, chuck type), sturdy and durable, not easy to scale, adhere, or block, suitable for various process installation requirements.

6)The sensor material design has high compatibility and selectivity, and is suitable for the detection requirements of different materials (polytetrafluoroethylene304 stainless steel, 316 stainless steel).

【T-BD5-EMC1124Electromagnetic concentration meter (acid-base concentration meter)

according toCaprolactamThe raw materials, reaction environment, and by-products of each process in the production process also need to be measured and controlled for acidity, salt concentration, and conductivity. We recommend Beidou StarEMC1124 electromagnetic concentration meter (acid-base concentration meter), capable of testing concentrated sulfuric acid and hydrochloric acid over the full rangePhosphoric acid, nitric acid, hydrofluoric acid, sodium hydroxide, salt mixture, alcohol, emulsified oil, urea, modified starch, coal slurry water (coal washing water), alcohol concentration, ammonia water, ethylene glycol concentration, flame retardant aqueous solution, dimethyl silicone oil, coal tar, slurry concentration, brake fluid, silicon carbide, sodium hydroxide, lime milk and other single component and multi-component mixture concentrations, as well as conductivity testing.

Typical applications: concentration detection of hydrochloric acid mixture, hydrofluoric acid mixture, nitric acid mixture, and sodium hydroxide mixture.

Technical Specifications:

1)Temperature compensation:0 60℃

2)quantity Cheng:0-200ms/m

3)lose Out:4-20Ma/RS232/485

4)Operating temperature: -30~ 70℃

5)Use pressure:0.5MPa

6)Measuring element probeSize: InsertSolution depth125mm， customizable

Main characteristics of the instrument

1)Large screen multi parameter display with Chinese menu guidance for operation.

2)The instrument has multi-point calibration function and adopts the least squares method to ensure measurement accuracy in wide range measurements.

3)The sensitive components are made of special alloy magnetic materials, which improves the sensitivity and stability of the instrument.

4)The single-chip microcomputer inside the instrument automatically compensates for the precise temperature of the solution based on the medium temperature.

5)have4-20mA isolated output signal and RS485 output interface, with upper and lower limit alarm functions for concentration.

6)It has power-off data protection function.

7)The electronic unit adopts a plastic corrosion-resistant chassis with a protection level ofIP65， Waterproof, dustproof, acid resistant, compatible transmitter: DCZ-1 electromagnetic transmitter.

8)Probe installation methods: pipe type, immersion type, and flow type are optional.

9)Using the principle of electromagnetic induction to measure the conductivity of a solution, there is no polarization effect, the measurement is accurate, and the maintenance amount is small.

10)The measurement medium can be selected through the menu, which can accurately measure the concentration of acid, alkali, and salt solutions, as well as measure the conductivity of general solutions.

【 Summary 】

As the production of caprolactam enterprises enters高利ReraAs an important detection method for optimizing the production process, the requirements for instruments and meters will become increasingly high. With such a complex production process control of caprolactam, the application of Beidouxing T-BD5CMD+MS1204p concentration meter and T-BD5-EMC1124 acid-base concentration meter will help with process control and improve process indicators and product quality.

T-BD5CMD+MS1204pConcentration meterApplied in the detection of caprolactam concentration in 2016, it has been running normally for several years.

T-BD5-EMC1124Acid base concentration meterIt has been successfully applied in the petrochemical industry since 2010.

Hope that Beidouxing instruments can achieve more applications in the production process of caprolactam

Please consult the Beijing Beidouxing Industrial Chemistry Research Institute for specific information