Process Analytical Technology

Objectives and Syllabus

This modules aims to provide a thorough grounding in the principles, technology and practices of analytical measurement. The emphasis is on the specification, installation and operation of the types of on-line analyser and sampling systems commonly used for the monitoring and control of industrial plant and processes.

Aims

The aim is to provide a thorough grounding in the principles, technology and practices of analytical measurement, with an emphasis on the specification, installation and operation of the types of on-line analyser and sampling systems commonly used for the monitoring and control of industrial plant and processes.

Objectives

• To understand the underlying principle of operation and techniques used in on-line chromatography (esp GLC) and spectroscopy (esp NIR). 
• To become familiar with common practice in the application of on-line-analysers and with the technology used for on-line analysis. 
• To understand the principles of sampling and appreciate the principal requirements for the design of sampling systems and analyser housing. 
• To understand the principles and practice of common electrochemical measurements. 
• To develop an awareness of the instrumentation used for ‘demand’ measurements and of the sensors available for measurement of gas species. 
• To introduce chemometrics and process analytical technology (PAT) as a basis for in improving quality and reducing costs. 

Phasing

This is a stand-alone module and has no prerequisites as such.

Note that SPC and multivariate statistics (MLR and PCA) are covered in the Advanced Process Automation module (CME 8368).

Note that software QA, GAMP and validation are covered in the Batch Processing and Automation module (CME 8372).

Note that QA, QC and TQM are covered in the Management of Automation Projects module (CME 8388).

Study Modes

This module is of one week's full-time intensive study consisting of a variety of formal lectures, demonstrations, case studies, etc.  That is followed by an assignment to be carried out in the student’s own time.

Coursework

The time allocation for ‘practical work’ provides for demonstrations of equipment and systems by suppliers, supplemented by case studies of sample applications from real plant by end-users.

Recommended Texts

• Bakeev K A (Editor),  Process Analytical Technology,  pub Blackwell,  2005,
  ISBN: 978-1405121033. 
• Banwell C N and McCash E M,  Fundamentals of Molecular Spectroscopy, 4th Edition, McGraw Hill, 1994. 
• Love J,  Process Automation Handbook,  Pub Springer,  2007,  
  ISBN: 978-1-84628-281-2. 
• Smith E and Dent G,  Modern Raman Spectroscopy: A Practical Approach,  pub John Wiley,  2005,  ISBN:  978-0471497943
• Workman J and Weaver L,  Practical Guide to Interpretive Near-infrared Spectroscopy,  pub CRC Press,  2007,  ISBN-13: 978-1574447842.

Topics Included

Chromatography:  principles of gas and liquid phase chromatography.  Column design: packed and capillary.  Detectors: katharometer and flame ionisation.  Sliding plate valves.  Sampling and conditioning.  Column operation: multiple columns and heartcutting.  Calibration and signal processing.  Normalisation of the component set.

Spectroscopy:  Underlying concepts.  Spectroscopy as an inferential measurement.  Distinction between different types of spectroscopic measurements:  UV, VIS, NIR, FTIR, IR, Laser, Mass, NMR, Raman, etc.  Principal characteristics and principle of operation of typical spectrometers.  Need for calibration against reference mixtures/compounds.

Manual sampling:  Importance of recording sample details: time, location, batch, etc.  Preparation of sample point.  Treatment of sample between drawing and analysis.  Accuracy and repeatability: variability of lab results (for same sample).  Pros and cons of manual vs automated sampling.

Automated sampling: continuous and discontinuous:  Choice of sampling location.  Calibration and sample/grab tanks.  Sample transfer to analyser housing.  Flushing of sample lines.  Sequencing of isolation and transfer valves.  Sample starvation.  Analyser house basics and specification: layout, hazardous area classification, air purging, F&G detection, isolation, etc.

Practice:  Selection of analyser type and specification of requirements according to application.  Calibration methods, types and strategy.  Accuracy and precision.  Validation by comparison with lab results and off-line analysis.  Z scores.  Use of SPC to check for bias, etc.  Operation: checks for validity, value, range, jump, freeze, rate of change, etc.  Fault detection: comparison of analyser spikes with other analogue signals.  Unexpected contaminants.  Reliability issues.  Maintenance and support effort.

Analyser technology:  Typical functionality of proprietary technology for collecting & merging data, standardisation, visualisation and interpretation of the results of analysis.  Tools for model building.  Diagnostics.  Integration with MES and MIS.  Importance of common time base.

Automation:  Use of analysers in control systems.  Interface with DCS, PLC, etc, including OPC.  Impact of transfer and analysis delay (deadtime), minimisation of delay.  Use of inferential models such as neural net predictions.  Updating of inferred and/or predicted results.  Synchronisation issues: discrete signals for read now, reset, alarms, self calibrate, etc.  Serial signals for data transfer.

Pharma applications.  Use of spectrometers for end point determination of reactions, separations, etc.  Measurement of uniformity: homogeneity and consistency.  Dryness measurement: analysis of constituents in vapour or transmission and spectral analysis of ultrasound through solids.  Crystallisation: laser techniques to determine size and shape (longest chord, average chord, x,y,z dimensions etc) of crystals & particle size distribution.

Emissions monitoring.  Incineration and combustion Directives.  Choice of analytical technology for relevant pollutant.  Sampling process/location.  EN 15259 and tech guidance notes (TGN) M1 & M2.  Standardisation of measurements to NTP, dry basis, etc.  Legally required calibration, validation and maintenance procedures.  Long term storage of data.  Operator monitoring assessment (OMA) audit and compliance monitoring.  EN14181, QAL 1, 2 & 3 and MCerts.  Rea lisation of trending: calibration factors, averaging (30 min and daily), exceedance reporting, etc.

Sensors for the measurement of gas species such as CO, CO₂, H₂O, O₂, CH₄, C₂H₂, H₂S, SO₂, NO, N₂O, NH₃, HCl, HF and HCN, especially for flue gas analysis and emiss ions monitoring.

Electrochemical measurements.  Ions and conductivity.  Dissociation: strong/weak solutions.  Nature of pH.  Mixing effects.  Cells, half cells and electrodes.  The glass electrode and the Nernst equation.  Measurement of conductivity and pH.  Ion specific electrodes.  Redox electrodes.  Calibration, drift, linearity, etc.
Demand.  The nature of ORP (oxygen reduction potential), DO, TOC (total organic carbon), BOD (biochemical oxygen demand), COD (chemical oxygen demand) and VOC (volatile organic compounds).  Instrumentation for DO and demand measurements.

Oil and gas applications.  Typical ASTM methods.  Dispute resolution on product quality.  Sample system performance evaluation.  Which analysers are used for what.  Use of GC and NIR on refineries.  Measurement of density, sulphur, etc.  Application to fuel gas, flue gas, HF alkylation, simulated distillation, gasoline and diesel, RVP etc.

Chemometrics:  Introduction to SPC.  Accuracy and precision.  Review of univariate and multivariate summary statistics.  Confidence limits.  Trending and control charts.  Introduction to data mining.  FDA initiative on process analytical technology.  PAT as a driver for improving quality and reducing costs: quality by design (QbD), QA, QC and GAMP.  PAT guidance, standards and regulatory requirements.