Energy Optimization

FlowMac and Energy Optimization of a Paper Mill.

Introduction

FlowMac is an established tool for simulation of pulp and paper processes. Models of the processes are made by selection of blocks from libraries designed in the application Extend. (imaginethatinc). Blocks are connected to each other to form a flowsheet. More than 500 blocks are available.

Flows of fiber, filler, chips, bark, water, steam, condensate and up to 60 tracers are simulated and run in a continuos model.

Temperature of solids and water is simulated through the model and based on inputs, outputs and energy exchange.

Product costs for personnel, raw materials and energy is included and summarized in a special block. Investment costs can be summarized in an excel file.

Selected data are animated in the model, reported in block dialogs and in text files opened in Excel. Electricity consumption is summarized in a separate block.

Data can be collected in a text file  for detailed organization , analysis and report of data.

Besides optimization of the energy FlowMac models are used for process design, rebuild, bottlenecking, COD-balances and training.

A late reference for an energy, mainly steam and temperature, and COD balance is the Kvarnsveden project (Stora Enso, Sweden, 2005  www.storaenso.se).

Supply of Power

- Steam Turbines
- Electricity supplier of kw

Costs for Power can be based on different tariffs for level of consumption.

Use of Electricity

- Electrical motor block, connected or unconnected, including mechanical and electrical efficiencies and selection of type.
- Infrared heater
- Steam boiler, water boiler

Supply of Steam

- By a steam block based on the steam data tables. Saturated or superheated steam can be supplied.
- By steam boilers fired by different fuels, bark and or sludge
- By process units as TMP refiners

Supply of Heat

- By Suppliers of chips, bark,water and pulp
- Steam heating equipment
- Water boiler

Exchange of Power and Heat

Heat exchangers are available for
- Water-water
- Steam-water
- Steam-air
- Air-air
- Water-air, Cooling tower
- Steam heating of a flow
- Preheating of chips
- Heating of air by gas or electricity
- Dryers in pulp and paper machines

Heat generated by drives for screens, agitators, pumps, etc is partly transfered to the flow of solids and water.

Stock Preparation

Heat is generated by drives and equipment as Grinders, TMP refiners, refiners and dispergers. Cooling equipment is available to reduce temperature to below 45 C and allow efficient screening of stickies in a dip plant.

Energy consumption of the broke system is estimated.

Paper Machine

Different specified orders can be run in the same simulation run.

The power need of cleaner and fan pump is included.

Heat losses in the wire section is estimated. Can be as large as 15-20 MW in modern machines.

Broke is simulated.

The steam and condensate system is simulated.

Meters

Available are meters for:
- Temperature
- Entalphy
- Exergy
- Steam properties
- Condensate properties
- Pressure

Room Ventilation

Fans and room ventilation is not included. Is done better in other softwares. Fan motors can be included.

Trim calculations, Transports, Storage costs

Is not included. Can be done in MillMac softwares and descrete event simulations.

Conclusions

Many processes and details are included in an optimization of energy consumption of a paper mill. Some are of great importance as:
- transfer of heat generated by drives,
- power consumption of cleaners and fan pumps,
- power consumption of drives for the wire, press, dryers
- the amount of broke
- breaks, trim, culled paper
- paper machine efficiency, number of unplanned and planned stops

FlowMac has the ambitions to cover most of the main areas of power and heat generation, losses and exchange. Everything can be in a model but all details do not need to be analysed in the same time. Objects of interest can be copied from the model and be analysed separatly.

And finally to remember- so much more can be done in use of FlowMac to improve economy of the paper mill.

Late Developement

- Accumulation of electricity and steam consumption
- Summary report for Electricity
- Power consumption of the fan pump
- Power consumption of the cleaner pump

on the list
- Power need for the drive of the wire section

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