Thermal Management in Polymer Processing. Professor Mark Price. Mechanical and Aerospace Engineering Queen s University Belfast

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1 Thermal Management in Polymer Processing Professor Mark Price Mechanical and Aerospace Engineering Queen s University Belfast

2 Background UK is one of top 5 plastics processing countries in Europe Turnover 19 billion equivalent to 2.1% of GDP Very energy intensive processes Typical electricity bill is 1-3% turnover ( 380 million p.a in UK) but also big users of gas Mainly SMEs (7400 in UK) who don t have the capability to tackle the problem individually

3 Background Simple no cost/low cost measures could reduce energy costs by by10-20% 90% of polymer processing methods involve an extruder The extruder typically accounts for 50% of total process energy Possible to cut extruder power consumption by 22% by installing insulation

4 Background Extrusion has high energy consumption per kg of product due to: Long set up/change over times during which waste product is produced [energy, material, productivity losses] Poor response times to process disturbances leading to off-spec product Operate with unsuitable screw geometries resulting in inefficient processing Lack of understanding of influence of processing parameters on energy consumption Machines run at conservative rates leading to poor specific energy consumption

5 Background Apart from the extruder there are many other areas where energy may be saved Polymer drying dryer efficiency could be increased from 35% to 56% by recovering heat from exhaust gases Compressed air used in all polymer processing plants 10 times the cost of electricity at point of delivery major opportunities to minimise demand and optimise supply Many opportunities to make use of low grade heat lost at various points in the processing lines

6 Background

7 Background Recommendations for improvements in efficiency usually applied to individual components of system If each component of overall system is optimised then major improvements in efficiency achievable System Component Best efficiency Worst efficiency Electrical wiring Motor Drive Pump Pipes Process demand Assumed constant Assumed constant Overall system efficiency

8 Background The complexity of a typical polymer processing operation requires a global or whole systems approach to optimise energy consumption The whole system approach with energy as the common metric will permit trade-offs between systems with apparently different functions. Extending the whole system approach to the whole life of the plant/factory permits more accurate long term forecasting for life time profits and emissions/energy reduction.

9 Aims & objectives The aim of the proposal is to develop methods and technologies to facilitate the efficient use of thermal energy in existing polymer plant operation and in the design of future plant processing plants Develop an energy management tool for polymer processing to optimise energy efficiency, profitability and quality Develop monitoring and control techniques to optimise energy use and quality in extrusion Validate 1 and 2 under industrial conditions Disseminate results widely to the UK polymer processing industry in the first instance and then internationally.

10 Work Programmes WP1: Energy management tool: development and validation WP2: Application of novel process monitoring techniques and determination of effect of processing/material on specific energy consumption in extrusion. WP3: On-line monitoring and control

11 WP1: Energy management tool: development and validation [1] System definition: the specification for the Energy Management Tool (EMT) will be drawn up in collaboration with industrial partners [2] Gathering input information for EMT: this information will be obtained from a number of sources including industrial partners and from experimental sections of WP2. [3] Database development: A database of information from step [2] and from WP2 will be developed [4] Development of models for system sub-processes

12 WP1: Energy management tool: development and validation [5] Software platform [6] Development of the optimisation technique [7] Integration of all elements into final package [8] Validation

13 WP2: Application of novel process monitoring techniques and determination of effect of processing/material on specific energy consumption in extrusion [1] Experiments carried out on highly instrumented single screw extrusion lines using process monitoring techniques developed at Bradford [2] Specific energy consumption will be monitored [3] Melt temperature profiles and melt temperature homogeneity will be monitored using thermocouple grids and infra-red temperature sensors [4] Optimal energy consumption will be determined for a range of polymers (including, polyethylenes, polycarbonate, pvc and nylon) and set extruder conditions (screw rotation speed, set barrel and die temperatures).

14 WP2: Application of novel process monitoring techniques and determination of effect of processing/material on specific energy consumption in extrusion [5] The effect of scale-up will be studied by comparing the thermal and energy characteristics of a 38mm screw diameter extruder to that of an identical extruder with 63.5mm screw diameter. [6] The data from these experimental trials will feed into a database of recommended processing conditions for different materials in WP1 and also to develop models which could be used to aid process control in WP3.

15 WP3: On-line monitoring and control [1] Focus on the on-line monitoring and control aspects of extrusion to develop inferential methods for tracking energy consumption and melt quality on-line [2] Develop an 'expert system' strategy to aid faster set-up and optimization of process conditions. This will enable settings to be tuned to account for differences in machine design and material properties between different grades of polymer and for the identification and response to difficult to predict melting problems.

16 WP1 Year 1 Year 2 Year 3 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Specification of EMT requirements Data gathering for EMT Database development Development of system models Development of optimisation methods Integration Test/Validation of software Network meetings/dissemination/exploitation activities WP2 Spec. Energy Consumption and melting optimisation Investigation of screw geometry/scale-up Investigation of novel temperature control methodologies Modelling and consolidation of data for On-line control & Energy Management System Testing on industrial scale WP3 1. Development of Inferential techniques to monitor melting stability 2. Development of inferential method for online power monitoring 3. Development of Expert System (a) Processing of feedback signals (b) model development (c) control system design/testing (a) (b) (c)

17 Project staffing QUB Bradford Academic Staff Research Staff Mark Price. Eileen Harkin-Jones. 1PDRA : 36 months 1 PDRA : 24 months Adrian Kelly. Phil Coates. 1 PDRA : 18 months 1PhD student : 36 months

18 Project Partners Partner Business Role Brett Martin Polymer processor Data for EMT development and validation TSM Systems Control systems for polymer Input to development of Industry process control systems and validation trials Tangram Technology All Ireland Polymers & Plastics Network Consulting Engineers for plastics industry-specialise in energy management Polymer industry network in RoI and N.Ireland Advise on energy reduction methods for the industry. Dissemination. Input to EMT design, validation trials, dissemination of results

19 Project Status Start date 31 March 2010