Industrial Sector

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Key Areas of Investigation

• ELECTRICAL ENERGY
  An audit of all electrical consumption from each substation was completed to obtain a clearer picture of electricity consumption. It was found that the power factor could be improved.
• BOILERS AND STEAM SYSTEM
  A comprehensive investigation touched on steam flow rate equipment and continuous boiler control.
• COMPRESSED AIR
  This is normally a very expensive form of energy and it was important to investigate its efficiency and application.
• ENERGY MANAGEMENT
  It appeared that the timing of production schedules was made almost arbitrarily. With little or no effect on the final product, these schedules could be amended to reduce utility consumption, and eventually costs.

Having highlighted the potential saving in energy costs, the team proceeded to evaluate these key issues according to succinct evaluation criteria.

Evaluation Criteria

The following table identifies some of the key areas where energy saving could be achieved resulting from this work and selected examples of other SAPPI initiatives. Where possible, these include: a cost estimate (which was a 'high-end cost' where a range was considered), the projected benefit to the company (in money terms), the estimated return on investment (months) as well as category of action required. Results were reviewed by the Mandini engineering staff.
Proposed action for the case studies evaluated in this program were categorised as follows:

• IMPROVED HOUSEKEEPING(1) Covered by maintenance budget or required changes in behaviour and/or schedules
• LOW-COST MODIFICATION (2)
• o RETROFIT (3) Refers to a significant one-off investment which is expensive in relation to the value of existing equipment.
• SUBSTANTIAL CHANGE INVOLVING SIGNIFICANT INVESTMENT (4) Substantial capital outlay on new equipment.

	Costs	Return	Payback	Category
Improved power factor correction	R270 000	R540 000 pa	6 months	(3)
Rigorous program for saving compressed air	R53 000	R106 000 pa	6 months	(1)
Rigorous program for Saving steam	R2 011 000	R4 020 000 pa	6 months	(1)
Efficient lighting upgrades	R888 000	R888 000 pa	1 year	(3)

*All costs indicated above are 'high cost' estimates. In most cases actual costs will be lower.There are of course many more.

Selected Results

After having completed the more detailed analysis, new energy saving opportunities, as well as those listed in the walk through, were identified. The table below highlights some of the main recommendations from this work, and some other key SAPPI Mandini energy and money saving programs.

Other Areas of Activity

• STEAM OPTIMAISATION: SAPPI has an ongoing drive to rationalise the Mandini plants use of steam and formulate a co-ordinated approach to steam monitoring and targeting. This also included a recent extensive steam trap audit.(1)
• 'OPERATION CLINKER' is a program that has been started to try and identify the major energy losses in the Mandini plant and quantify potential energy losses.(1)

	Costs	Return	Payback	Category
Improved power factor correction	R270 000	R540 000 pa	6 months	(3)
Rigorous program for saving compressed air	R53 000	R106 000 pa	6 months	(1)
Rigorous program for Saving steam	R2 011 000	R4 020 000 pa	6 months	(1)
Efficient lighting upgrades	R888 000	R888 000 pa	1 year	(3)

Recommendations

• POWER FACTOR CORRECTION
  Improving the overall power factor for the plant potentially holds these benefits for SAPPI:
    - increase of plant capacity
    - reduction of electrical maximum demand charge
    - fewer power losses in feeders, transformers and distribution equipment
  The table illustrates the potential saving of R540 000 if the power factor is improved to 0,98. A more detailed quote for an upgraded power factor correction system should be obtained in order to determine the payback period for this option.
• COMPRESSORS
  Compressed air leakage was identified as a problem area. A leakage prevention plan could reduce leakage from approximately 25% to 8% and this would result in an estimated saving of R106 000 per annum. An audit of the compressed air system is recommended.
  In addition to the leakage problem, it was noted that the compressed air was used to regulate ambient temperatures during the summer and for general cleaning purposes. Training and education about energy issues could help eliminate such practices.
• BOILER PLANT OPERATION
  The boiler report contained these recommendations:
    - the gas and air tightness of boilers should be checked regularly (air- heater and casing leaks).
    - care should be exercised when operating above maximum continuous rating (MCR) as this could reduce the life span of the boiler
    - the feed water and steam flow meters should be calibrated to determine boiler leaks.
• LIGHTING
  The suggested amendments in lighting as contained in the table will result in an approximate saving of up to 25% (T12 to T8) and up to 70% (CFLs instead of incandescent lights). Group replacement of lights based on 70% of the lamp's rated life will facilitate 25% savings due to the reduced maintenance labour cost.

ENERGY MANAGEMENT TEAM

TO ACHIEVE THE DESIRED RESULTS, THESE KEY ISSUES HAVE TO BE ADDRESSED:

• ENERGY MONITORING AND TARGETING
  (M&T). SAPPI Mandini currently has a well- run utilities department, and the minor adjustments required already form part of the planning for next year. (Generic suggestions, for M & T as well as the topics that follow, are outlined in more detail in the 'How to' booklet of the 3E program.) Monitoring and targeting should arguably receive the most attention as it is a most significant issue due to the size of the installation and the 'organic growth' type of expansion of the plant. It is reccomended that, where possible, 'real-time' monitoring should take place.
• RESPONSIBILITY AND ACCOUNTABILITY
  (The following is a common theme in plants audited.) Due to the desegregated nature of 'utilities', not one particular division assumes responsibility for planning and cost effective utilisation. Significant savings can be achieved by introducing basic constraints to these various consuming sectors. These should be cost driven with final accountability resting with the accounts department and management. Incorporating a summary to an existing regular report could facilitate this. This would also provide a forum for recommendations and innovation.
• CHARGING USERS FOR CONSUMPTION
  This is recommended to improve maintenance and curtail wastage. SAPPI Mandini had, prior to the completion of this energy audit, planned to implement this measure more stringently. Such a step will force users to manage their energy consumption tightly and result in energy efficiency measures being driven from the bottom up. This bottom up approach commonly results in energy savings of 10% - 20%.
• REWARDING INITIATIVES AND PROVIDING INCENTIVES FOR STAFF
  'Energy efficiency' often requires engineers to 'go the extra mile', as it is not yet accepted practice in South Africa. This may be enhanced by rewarding initiatives and creating incentives to motivate staff.

Bottom Line INVESTMENT VS ANTICIPATED PERIOD OF PAYBACK

ALL MEASURES:

• The total investment required for the execution of all the above listed projects is R3.22m.
• The total annual energy earning for the above is R5.55 m. (Following implementation, an amount of approximately R200 000 per annum should be included in budgets of future years to facilitate and motivate the required activities.)
• This represents a saving of more than 5% of the total energy consumption.
• The overall payback is approximately seven months.

MAINTENENCE & LOW COST MEASURES:

• The total investment required for the execution of all the above listed maintenance and low cost projects is R2.06m.
• The total annual energy earning for this is R4.13m.
• The payback for these measures (class 1 & 2) is about six months.

ENVIRONMENTAL CONSIDERATIONS

• NATIONAL ENVIRONMENT
  Reduction in CO2,emissions: 65 200 tons per annum.
• LOCAL ENVIRONMENT
  Reduction in SO2 emissions: 1185 tons per annum.