Energy Audit Case Study: Tire Factory Sri Lanka

Company Description

ABC* is one of the leading rubber products factories in Sri Lanka producing tires and retreading small to large tyres using cold and hot processes. The installed annual retreading capacity of the hot process is 400,000 tires and of the cold process 135,000 tyres. Annual productions of the main products are as follows:

- Retreading – Hot 120,000 tires

- Retreading – Cold 46,000 tires

- Vaerling process - 55,000 tires

- Compounding-  9,600 tires

- Tyres manufacturing - 4,000 tires

- Rubber products - 600 tons

Process Description

The company consists of a large number of subsidiary factories using different processes to

manufacture and retread tires and to manufacture rubber products.

- Material preparation: The common process for most of the factories is material preparation.

Raw rubber, mostly in the form of sheets (RSS), is mixed with additives in a Bambury

mixer or calendar.

- Tyre making: Tyre manufacturing for small vehicles consists of several steps:

· Main process – tyre making: Raw rubber compound is warmed, cut and conveyed to an

extruder where it is formed into flat sheets. The tire is built on a mould using the rubber

sheets.

· Sub process 1 - Bead wire ring making

· Sub process 2 - Bias cutting process

· Sub process 3 - Air bag making

- Tyre retreading – Hot process:

· Initial inspection

· Buffering

· Application of new rubber

· Vulcanization

· Final inspection

- Tyre retreading - Cold process: This process is performed below 1000C. The tread used in

this process is cured before retreading and fixed on the carcass.

Continuous improvement

The company has taken several initiatives to ensure energy efficiency improvements will continue. Some important ones are:

· Appointment of a Project and Development Engineer to focus on energy management

· Increased communication to factory staff about energy efficiency options and assessments

The focus areas selected

· Boiler and steam distribution system: five options identified and four implemented

· Compressed air production and distribution system: three options identified and still under investigation

· Rubber Products Division (RPD), where numerous options were generated:

- Main tyre making: 13

- Bead wire process: 11

- Process cutting: 74

- Air bag making: 8

· Electricity supply system

- For six of the implemented options for which results were measured (see table below), the total investment costs were US$ 49,080, annual savings were US$ 84,764 and total payback was 7 months

- For options implemented, the total energy reductions were 521 MW and 173 kilo-liters furnace oil per year resulting in 607 ton CO² emission reductions per year

OPTIONS IMPLEMENTED

FOCUS AREA/ OPTION	FINANCIAL FEASIBILITY	ENVIRONMENT AL BENEFITS	COMMENTS
Compressed air supply system: Replacement of inefficient compressor with two screw type compressors	- Investment costs: US$ 29,500. § Operating costs: lower than in old situation but not quantified § Cost savings: US$ 43,137 /yr § Payback period: 8 months	§ Electricity saving: 500 MW/yr § GHG emission reduction: 102 tCO2/yr	Working environment in the compressor room has improved due to lower noise and ambient temperature levels
Boiler and steam distribution system: Improved steam system efficiency through: § Boiler maintenance § Leak repairs § Pipeline insulation	§ Investment:: US$ 13,400 § Cost savings: US$ 22,315 /yr § Payback period: 7 months	§ Furnace oil savings: 98,400 l/yr § GHG emission reductions: 303 tCO2/yr § Reduction of NOx, particulates	§ Water reduction The implementation of these options will continue as part of a steam management program
Boiler and steam Distribution system: Recover heat from boiler flue gas to preheat combustion air	§ Investment: US$ 300 § Cost savings: US$ 600 /yr § Payback period: 6 months	§ Fuel savings: 1,044 l/yr § GHG emission reduction: 3.2 tCO2 /yr	Option is being implemented. The company boiler room and maintenance staff were involved in the installation
Rubber Products Division (RPD): Insulation of § Steam Pipelines § Tyre moulds of Vulcanization/Curing Process	§ Investment:US$ 1,480 § Cost savings: US$ 1,380 § Payback period: 1 year	§ Furnace oil savings: 6,000 l/yr § GHG emission reduction: 18 tCO2 /yr	The company is continuously repairing insulation and leaks Working conditions improved due to reduced heat loss
Rubber Products Division (RPD): Condensate recovery	§ Investment: US$ 3,200 § Operating costs: US$ 1,200 § Cost savings: US$ 15,456 /yr § Payback period: 4 months	§ Furnace oil saving : 67,200 liters/yr § GHG emission reduction: 207 tCO2/yr	The company implemented this option but all figures are still expected costs and savings
Rubber Products Division (RPD): Compressed air leak survey and leak repair	§ Investment: not quantified but very low § Operating costs: ongoing § Cost savings: US$ 1,876/yr § Payback period: estimated 1 month	§ Electricity savings: 21,432 kWh/yr § GHG emission reduction: 4.4 tCO2/yr
Rubber Products Division (RPD): Electricity saving through waste reduction of nylon thread and rubber compound	§ Investment: not provided § Cost savings: US$ 1,977	§ Electricity savings: 28 MW/yr § GHG emission reduction =5.7 tCO2/yr	Not yet implemented: all figures are expected costs and savings. Preliminary energy audit completed
Electrical Supply system: Installation of load demand indicators	§ Investment: not provided § Cost saving: US$ 6,336	§ Energy savings: 2112 kVA	Not yet implemented: all figures are expected costs and savings. Preliminary energy audit done
Electrical Supply system: Power demand management and installation of electricity sub meters at Bambury Mixer	§ Investment: not provided (for meter) § Cost saving: US$ 7,920 § Payback period: not provided	§ Demand peak reduction: 2,620 kVA § Energy savings: none § GHG emission reductions: none	Not yet implemented: all figures are expected costs and savings. Preliminary energy audit done

- Energy  Efficiency Asia Project

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