Energy audit result of An Hoa Paper JSC

Case study

20/08/2019

Hoa An Paper JSC, which was established in 2002, specializes in producing high quality pulp and glazed paper. It is the investor of An Hoa Pulp and Paper Mill consisting of 2 production lines: bleached pulp whose capacity is 130,000 tons/year and glazed paper whose capacity is 140,000 tons/year.

Energy use situation

Currently, the company uses electric power, coal, biomass and black liquor to burn boilers.

The electric power of An Hoa Paper JSC is provided by 110kV transformer station with a capacity of 31.5MVA and voltage level of 110/10.5kV. Black liquor recovered from the wood pelletizing process of the powder workshop is used as fuel for 90-ton boiler. Meanwhile, coal and biomass materials are used to burn 40-ton and 50-ton boilers.

Statistics of energy use at An Hoa Paper JSC for 3 years are as follows:

Energy efficiency potential

Energy audit results show a huge energy efficiency potential of An Hoa Paper JSC. The proposed energy efficiency solutions are feasible both economically and technically because of their low investment costs, high economic efficiency, short payback period and easy implementation.

If these proposed energy efficiency solutions are implemented, the company will significantly reduce energy use costs. Specifically, proposed energy efficiency solutions can help the company save 9,932,443kWh of electric power/year and 8,089.3 tons of coal/year, equivalent to annual energy cost savings of VND33.8 billion.

Particular energy efficiency solutions

16 energy efficient solutions are found during energy audit period including VSD application, air compressor system improvement, shoe press application, vacuum system improvement.

Solution No. 1: Improving excess air ratio of 50 ton steam boiler

Real situation

Emissions measurement results as follows:

Type	O2	CO	CO2
Ratio	7.94%	84 ppm (0.01 %)	11.44 %

This O2 ratio is much higher than the standard ratio 3.5-4.8% (equivalent to the excess air coefficient 1.2-1.3) for the boiler using solid fuel.

Expected output

After the installation of additional excess air coefficient controller to the boiler

Type	O2	Energy
Reduction	3.94%	1.567%

Energy saving results

The amount of fuel saved: 813.3 tons/year

Investment cost: VND650 million

Cost saved for 1 year: VND1.871 billion

Payback period: 0.3 year

Solution No. 2: Installing the roots blower for vacuum to replace the vacuum pump system of paper machine line

Real situation

- The paper machine line uses 08 vacuum pumps integrating the pipe system.
- Suction pressure at the stages is adjusted manually.

Expected output

- Water content in paper is reduced by 4%
- Steam consumption decreases by 16%
- The rate of torn paper reduces
- This technology saves energy, increases productivity and controls moisture uniformly

Energy saving results

Annual power savings: 6,962,845 kWh/year

Investment cost: VND50 billion

Annual cost savings: VND10.674 billion

Payback period: 4.7 years

Solution No. 3: Replacing presses of conventional technology with presses of Shoe Press technology

Real situation

Paper processing stage is processed by a press of conventional technology (Tri-nip) consuming a lot of energy.

Expected output

- Water content in paper is reduced by 4%
- Steam consumption decreases by 16%
- The rate of torn paper reduces
- This technology saves energy, increases productivity and controls moisture uniformly

Energy saving results

Coal savings: 4,801 tons/year

Investment cost: VND60 billion

Annual cost savings: VND11.0423 billion

Payback period: 5.4 years

Hong Ngoc