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Case study

Energy audit result of Vicem Hai Phong Cement Company Limited

20/08/2019

Vicem Hai Phong Cement Company Limited specializes in clinker and cement production. The company has rotary kilns which are the most modern cement production line in Vietnam. They have separate clinker and additive grinding technologies  helping control grades of cement. 
The company's main products include PCB30 cement, PCB40 cement and other customized cement. 
Energy use situation 
Vicem Hai Phong Cement Company Limited uses different types of energy including electricity, coal, gasoline, oil and LPG. Coal including 3b Coal and 3c coal are primary fuel. 
Energy efficiency potential 
Energy audit results show that Vicem Hai Phong Cement Company Limited has huge energy efficiency potential. Proposed energy efficiency solutions, including waste heat recovery, can lead to energy cost savings of VND 80.15 billion.
Particular energy efficiency solutions 
16 energy solutions are found during energy audit period including pump system improvement, reinforce insulation, adding a new preheater, waste heat recovery generation. 
Solution No. 1: Circulating AQC hot air to primary air to improve the kiln and the calciner performance
Real situation 
Currently, primary air whose temperature is about 30oC from the outside is directly taken into the kiln and calciner. 
Expected output 
When a part of AQC hot air is supplied to primary air for calciner and main burner, it enables to reduce coal consumption. 
Energy efficiency results 
Coal savings: 1,281.54 tons/yearInvestment cost: VND 5.25 billion
Cost savings: VND 2.589 billion/ yearPayback period: 2.03 years
Solution No. 2: Adding the 6th stage of preheater to improve heat exchange efficiency in preheater tower
Real situation
The exhausted gas from the 5-stage preheater is being emitted to EP at the temperature of about 364°C.
Expected output  
The addition of an extra pre-heater step may reduce the amount of heat available for material drying in the raw mills, consequently, the coal consumption decreases. 
Energy efficiency results 
Coal savings: 2,371.2 tons/yearInvestment cost: VND 13.65 billion
Cost savings: VND 3.32 billion/yearPayback period: 4.11 years
Solution No. 3: Waste Heat Recovery Power Generation
Option 1A: Steam Cycle with Cooling Tower
Real situation
Currently, the enterprise has taken advantage of a part of waste heat to provide for the process of crushing coal and cement. However, due to the high temperature of the flue gas (about 330oC - 365oC), there is still huge energy efficiency potential.  
Expected output 
The solutions leads to energy savings of 5,655 toe/year và a reduction of 29,886 tons of CO2/year. 
Energy efficiency results 
Electricity savings: 36,652,200 kWh/yearInvestment cost: VND 291.958 billion
Cost savings: VND57.54 billion/yearPayback period: 4.43 years
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