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Case study

Energy audit results of Danang Rubber Joint Stock Company

19/09/2019

Da Nang Rubber JSC is one of three largest companies in the tire manufacturing industry in Vietnam. The production line of the company is invested synchronously with many modern machines such as rolling-mixing lines, triplex extruder, tire building machines, tire curing press system automatically in and out. 
Main products of the company include light-load tires, heavy and super heavy-duty tires, special tires, automobile/bicycle/motorcycle tires and other rubber products. 
Energy use situation 
Currently, Da Nang Rubber JSC uses electrical power, steam and water for the production process. The electricity supply system consists of 8 transformers with total capacity 40,000 KVA while the demand for steam is supplied directly from the Tin Thanh boiler.
The electric power use of workshops are as follows: 
Energy efficiency potential 
Energy audit results show that Danang Rubber Joint Stock Company has huge energy efficiency potential. The total value of potential benefits if a maximum set of consistent projects is implemented is 10.745 Billion VND/year. These benefits represent 4.8 % of the total plant energy cost. The total energy saving for this set of projects is 626 toe/yr, which is 5% of the total plant energy use.
Particular energy efficiency solutions 
10 energy solutions are found during energy audit period including chiller system improvement, steam system improvement, absorption chiller application.
Solution No.1: Installing hydro ball auto clean system for cooling water loop
Real situation 
- Chiller system has many mosses leading to deposits caused by sea breezes intrusion;
- Condenser Approach Temperature is high 3.3°C (<2°C);
- 2 condenser pumps run at the peak-time load to improve cooling load of condenser causing energy waste; 
- Cleaning condenser of chiller need to be done regularly.
Expected output 
Installing hydro ball to condenser tubes and monitoring the condenser approach temperature result in 10% saving from chiller energy consumption. 
Energy saving results 
Electric power savings: 448,800 kWh/yearInvestment cost: VND1.2 billion
Cost savings: VND705 million/yearPayback Period: 1.7 years
Solution No. 2: Recovering wasted heat of the condensate for steam saving of AHU 
Real situation 
- 9 AHUs use 3 bar steam for humidity control;
- Flash steam has not been recovered;
- Condenser water waste the heat.
Expected output 
Using condensate water or flash steam to AHU system in state of steam reduces remarkably the amount of steam required for the production process. 
Energy saving results
Steam savings: 4,300 tons/yearInvestment cost: VND4 billion
Cost savings: VND3.15 billion/yearPayback Period: 1.3 years
Solution No. 3: Using Hot Water From Condenser Water To Absorption Chiller
Real situation 
- Condensate water can be recovered from curing machine;
- 10m³/h from Bias and Radial workshop with temperature 100⁰C.
Expected output 
Using hot water from condensate water to absorption chiller results in electrical power savings and energy cost savings.  
Energy saving results
Electric power savings: 424,320 kWh/yearInvestment cost: VND4 billion
Cost savings: VND666 million/ yearPayback Period: 6 years
Danang Rubber Joint Stock Company is one of 10 enterprises entitled to energy audit implementation within the framework of the Project for Promoting Investment Market for Energy Efficiency in Industrial Sector in Vietnam, funded by the Korean Government through Korean International Cooperation Agency (KOICA). The energy audit was conducted from September 10, 2018 to September 21, 2018 by the Energy Conservation Research and Development Center in cooperation with Korean energy experts. 
Ngoc Diep