Sequential Modelling of Thermal Energy: New Potential for Energy Optimisation in Papermaking

Transcription

1 Sequential Modelling of Thermal Energy: New Potential for Energy Optimisation in Papermaking Puya Afshar (1), Martin Brown (1), Paul Austin (2), Hong Wang (1), Timofei Breikin (1), Jan Maciejowski (2) (1) Control Systems Centre, The University of Manchester (2) Engineering Department, The University of Cambridge Correspondences: 1

2 Contents 1. Introduction a) Paper machine process b) Energy consumption figures-motivation 2. Research questions and challenges 3. Exploratory data analysis: DataExplorer tool 4. Sequential modelling of thermal energy a) Unit process models b) Sequentially linked process model c) Consequences of thermal energy reduction 5. Summary and ongoing work 2

3 Part1: Introduction -Paper machine process - Energy consumption figures-motivation 3

4 1.1. Paper machine process Steam Reels headbox Vacuum Pressure 4

5 1.2. Energy consumption-motivation Newsprint mill: Energy Usage ~ 23,000 GWhr/yr 20% saving = 4,600 GWhr/t ~ 240,000 households Most of this energy is in thermal form (steam) used for drying the sheets Current energy saving measures: (effective, expensive) Heat recovery schemes Energy-efficient equipment Look at more cost effective ways by using existing resources (operational data) 5

6 Part2: Research Question and Challenges 6

7 2.1. Potential in de-watering process 7

8 2.2. Research Questions: Can we reduce steam consumption by presenting a dryer sheet to the dryer? Can we achieve this by changing vacuum at forming and press sections? 8

9 2.3. Main Challenges: Key vacuum pressures related to drainage in forming and press must be identified The process units (forming, press,steam consumption) must be modelled. The unit models are linked (sequential unit models) The consequences of steam reduction must be analysed (increase in raw material usage, deteriorating the quality, etc) If there are consequences, we should develop an algorithm to satisfy more than one criteria simultaneously 9

10 Part3 Exploratory data analysis: DataExplorer tool 10

11 3.1.DataExplorer : Exploring data 11

12 3.2. Advantages of DataExplorer Compared to off-the-shelf applications, it provides both sequential dynamic modelling and multi-objective optimisation It uses MATLAB functionality (all toolboxes) It provides means for dealing with large amounts of historical data in an interactive way Model uncertainty can be integrated (on going) Will be made available for academic use 12

13 3.3.DataExplorer: modelling Loading mill data Process and Energy Models Processing data Optimisation modelling Showing the results 13

14 Part4: Sequential Modelling of thermal energy -Unit process models -Sequentially linked Process and Energy models -Consequences of thermal energy reduction 14

15 4.1.Unit process models: Forming & Press Steam To PM Steam To PM FLOW - MULTIFOIL SHOE CHAMBER Trans Section Roll Vacuum PV Relationship: steam usage and draining water (Multi-foil shoe #2- forming) Dependency between steam usage and vacuum pressure in press section. we can manipulate vacuums and drainages to reduce steam usage 15

16 4.2. Sequentially linked models 1) Made by linking unit process models 2) Basis for further optimisation Mass Balance: Steam in = Condensate out Vacuum pressures: - Input to unit models Vacuum Data-based modes Vacuum Steam Headbox Forming Section Press Section Dryer Water Water flowrates: -Outputs of unit models - inputs to energy flow models Data-based models Water Energy Balance: Consumed=Steam in - Condensate out Condensate First principles +Data-based model 16

17 4.3. Analysing the effects of steam reduction With reducing steam use by -2%: Retention aid RA2 increase by +0.51% Sheet fillers increase by +0.44% 13 Need for multiobjective criteria Sheet Ash Steam To PM14 17

18 Part5: Summary and ongoing work 18

19 5.1. Summary of findings to date Forming and Presssections remove the greatest amounts of water while consuming much less energy than dryer By appropriately changing the vacuums pressure in forming and press sections energy usage can be improved The direction for those changes need to be determined by appropriate optimisation algorithms (on-going) The resulting direction may not necessarily incorporate intensifying all vacuum pressures (on-going) Reducing energy this way might result in increasing production costs/decreasing quality 19

20 5.2. Exploration and optimisation 80 Multi-foil shoe2- Vac (barg) 60 Curved Suction box- Vac (barg) 80 Couch Roll 2- Vac (barg) Vacuum Drainage Flow Multi-foil shoe 2-Flow (l/min) Production (tonne/hr) Curved suction box-flow (l/min) Energy- Steam (Tonne/hr) Outer Wire- Flow (l/min) Quality- Moisture (%) Flowrate(l/min) R 2 Multi-foil shoe chamber # Curved suction box Outer wire Couch Roll # Multi-foil shoe chamber # HIVAC Performance

21 Thank you! 21