the heat robbers ! 100% fuel energy 80% steam 3% distribution losses 77% process consumption 57% 20%...

The Heat robbers !

100% fuel energy

80

% s

tea

m3% distribution losses

77%

Process consumption 57%

20%

UnburntStackBlowdown

(Condensate & Flash)

How does one measure

Specific Energy Consumption ?

-kg of fuel per kg of Paper

-kg of steam per kg of Paper or kg of Steam/kg of water evaporated

-Kw-h / Tonne of Paper

-Kcal/ kg of water evaporated?

-Total equivalent Energy/ Tonne of Paper ? Gj/Tonne of Paper?

Energy Management Seminar for Vietnam Paper Mills , Ho Chi Minh City , May 2008

How does one Reduce

Specific Energy Consumption ?

-Obviously minimise the Losses ( Boiler losses, Distribution losses)

- Enhance Condensate Return & Recover Flash Steam

- Improve the Process heat Utilisation ( Heat Transfer rate)

EPIC Educational program – Saving Energy Cost by increasing Boiler and Steam system Efficiencies

Specific Steam Consumption on Indian Machines

• Which is more representative ?

Kg of steam / kg of Finished

production

OR

kg of steam /kg of water evaporated ?

• Typical good values

• Newsprint 1.6- 1.7• Wr/Pr (NS) 1.6-1.7• Wr/Pr (SS) 1.9-2.0• Kraft 1.5- 1.9• Paper Board 2.1-2.3• Tissue 2.5-2.6

• Kg of steam/ water = 1.3-1.35

Basic Principles of reducing energy consumption

• Reduce Temperature of any exhausts in Boiler House

• Minimise Amount of water evaporated in drier section

• Minimise Steam condensed outside driers

• Maximise Condensate return and pressure

• Minimise Electrical consumption of drives/pumps

• Monitor and Manage Energy Consumption trends & costs.

The No.1 Rule for energy conservation

• You cannot control what you cannot measure

Factors affecting Specific Steam consumption..1

• Furnish Type

• Stock Freeness

• Dryness off Press

• Stock Temperature

• Felt tensions

• Paper breaks/idling

• No. of Driers /Material

• Design of steam and condensate system

• Condensate evacuation efficiency

• Extent of Flash steam recovery

• Type of Siphon/clearances

• Presence of non condensibles/air

Factors affecting Specific Steam consumption….2

• Type of Hood and Controls

• Hood doors open/closed

• Sizing of Thermocompressors

• Differential Pressures across Driers

• Number of driers connected to Condenser

• Finally the Degree of Automation

Need for Automation in Steam Systems

Upgrade to Efficient Steam /Quality Control systems.•The Need to Produce High Quality Paper

•The Need to run machines faster

•The Need to minimise Cost of Manufacturing

•The need to jump productivity and Energy efficiency

All of these have forced mills to look at improving their systems and Automation is one of the strategies.

Specialist in process efficiency & energy conservation

Steam Generation --

Minimum Cost of Steam generation

•Monitoring real time Efficiency of the Boiler

•Tracking Losses in Boiler

•Both Direct and Indirect Efficiency

•Steam to Fuel Ratio for Different Loads

• Online Excess Air control

•Boiler House Management system with

objective to minimise steam generation cost


Steam Distribution – Minimising Losses

Delivering Steam at the Right Pressure and Temperature to Paper machine is essential

Steam should be Dry Saturated at Drier Inlets

This means that Steam conditioning is essential

Minimising Pressure Drops in lines

Correct Drain Trapping is essential to prevent steam wastage.


Steam Utilisation- Energy Efficiency of Paper Machine

Drying Paper Uniformly at normal steam pressures

Removing Condensate from Driers efficiently

Returning Condensate to Boiler house

Flash Steam Recovery

Steam Response to Final Moisture Value

Heat Transfer in CylindersHeat Transfer in CylindersHeat Transfer in CylindersHeat Transfer in Cylinders

SteamAir gapPaper

Felt

Cylinder

Condensate Air layer

Moisture Paper sheet

Steam in

Condensate out

Condensate in Siphon Drier

Needs for Efficient Steam and Condensate system

• Steam at the Right Pressure , Saturated and Dry• Correct syphon selection and clearance• Adequate Differential Pressure• Venting of Non- condensibles/Air• 100 % Recovery of Flash Steam/ Blow thru• Minimising leakages thru rotary joints• Adequate Thermal insulation• Adequate Steam Trapping on distribution lines

RollCylinder

PV Ventilation

Felt

Hood & Pocket Ventilation-Hood & Pocket Ventilation-Automation for Efficient operation Automation for Efficient operation

Hood & Pocket Ventilation-Hood & Pocket Ventilation-Automation for Efficient operation Automation for Efficient operation


Hood & Pocket Ventilation-Hood & Pocket Ventilation-Controls Controls

Hood & Pocket Ventilation-Hood & Pocket Ventilation-Controls Controls

Hood provides Consistent Drying environment

Hood also provides Energy efficiency

10-12 % saving in Steam is possible using Closed Hoods

Pocket Ventilators can increase production by 5-8%

Controls for :

a) Pocket Ventilation Temperature Control

b) Dew Point Control /Exhaust Humidity

c) Zero Level Control for minimum leakage air.

The Link Between Steam and Quality


Uniform Drying is possible only with a

Stable steam and condensate system.

Poor Moisture profiles can result due to

Poor condensate evacuation or poor

Hood /PV air circulation apart from others

Popereel Moisture controlled by Steam

Valves in Drier Section

Where do we begin ?

• The Small Things– Check for leaking traps and replace immediately– Check Syphon tips and clearances– Check for Rotary Joint seal failures /leakages– Check for excessve DP set points – Check for obvious leakages – Check Excessive Steam pressure – Install Airvents and sightglasses

• The Larger things Leading to Automation– Control Exit moisture from Presses– Installing Thermocompressors– Control Valve and DP automation– Changeover to correct syphons– Install Drier Diagnostic systems– Hood controls

First Start with installing accurate meters for Steam /condensate/electricity

Reduces Production

Loss

Improves Web

Runnability and

Paper Quality

Trouble Shooting & Supervisory

tool for paper

machine

Optimises Paper Drying

Efficiency

Generates set points for

process parameters in dryer section

Mathematical Model &

Simulation Software of Paper Drying

process

DryMax

Parameters Monitored & to be Controlled: Surface Temperature of dryer cylinders Temperature of paper sheet Moisture content of paper sheet Evaporation rate of water from the paper surface

Comparison of Measured parameter value with Set-

Point generated by DryMax

Paper In

Controller

Paper Out

Steam

Condensate

DryMax

Summary


Automation pervades every aspect of Steam in a Paper Plant

To operating Efficient Boilers

To World Class Steam and Condensate systems of Paper machines

To Energy Efficient Hoods and PV systems

To Robust Quality Control systems integrated with Steam systems

Whatever be the Automation……..


The Ultimate Objective is to have the Lowest Specific Steam

Consumption for your plant

Is your Plant close to world class levels of Energy Efficiency ?

the heat robbers ! 100% fuel energy 80% steam 3% distribution losses 77% process consumption 57% 20%...

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