Case study: Trang An 2 Confectionery Joint Stock Company – Nghe An

Case study: Replacing the inefficiency coal-fired boiler with the high efficiency biomass boiler at Trang An 2 Confectionery Joint Stock Company – Nghe An

Trang An 2 Joint Stock Company is located at 233 Sao Nam, Nghi Phu, Cua Lo Town, Nghe An, and it is one  of four companies of Trang An Confectionery Production Group. Through 8 years of striving and growing, Trang An 2 Joint Stock Company has constantly grown and accumulated a lot of experience in production and business development. With a team of experienced leaders, good business strategies, a team of highly trained engineers and skilled workers, Trang An 2 Joint Stock Company has steadily progressed and constantly developed to maintain its reputation and product’s quality deserving the trust of consumers.

Trang An 2 Joint Stock Company is one of the first enterprises in the field of confectionery production to be certified with ISO 22000: 2005 “Hazard analysis and critical level control points” for food safety and hygiene management system in Vietnam. This represents the commitment of business management to ensure food safety for consumers’ health.

Trang An confectionery products have become ones of the famous products in Vietnam, trusted and loved by consumers nationwide.

Image of company’s products

In addition to product’s development activities, the Company is also very interested in solutions to reduce production costs and to protect the environment such as saving energy, especially boiler systems, one of key energy use equipment of the Company.

In the past time, the Company has cooperated with national experts of the Project “Promotion of Energy Efficient Industrial Boiler Adoption and Operating Practices in Vietnam” of the Ministry of Industry and Trade and the United Nations Industrial Development Organization (UNIDO) to carry out the evaluation of boiler efficiency as well as to provide consultancy in implementing solutions on boiler efficiency improvement for energy savings.

Evaluation of boiler efficiency by UNIDO Project’s Expert

Within the framework of the expert training program on boiler efficiency evaluation technique of the UNIDO Project, two national experts were sent to the Plant to conduct the evaluation of the boiler system in May 27, 2018. Some comments drawn from this evaluation are as follows:

Trang An 2 company is using coal-fired boilers system including: 01 coal dust fired chain grate boiler with the capacity of 7 tons/hour, loading pressure of 10 kG/cm2 and 01 coal-fired boiler with capacity of 3.5 tons steam/hour, loading pressure of 10 kG/cm2 that were manufactured by the Vietnam Boiler Joint Stock Company.

The company’s coal-fired chain grate boilers system, after a period of operating, has occurred some problems/ disadvantages, affecting the production costs and the surrounding environment. Disadvantages of the chain grate boiler system of Trang An 2 Joint Stock Company are as follows:

  • Chain grate boilers currently are operating at very low efficiency (58% calculated by direct method) that have resulted in a lot of fuel consumption and high operating costs;
  • Often being broken, especially the chain grate section and the chain of waste slag that was caused by working in harsh environments, so it must be stopped unexpectedly to repair and that affecting production capacity;
  • Complex and time-consuming to implement the reparations and replacements;
  • Simple stack treatment system and dust/emission discharged into the environment that does not meet the Vietnam National Standard on Environment.

The operation of boilers at the Company also has inadequate optimization points which leads to very low boiler efficiency. That are:

  • The concentration of oxygen in stack is too high (average 16.6%), showing that the excess air is too high, leading to a large amount of heat loss through stack;

The average stack temperature after the economizer is about 124oC which is unreasonable for the coal-fired boilers. The factory should control the output stack temperature after the economizer to be greater than 150oC for ensuring the stack is free from acid dew, avoiding the corrosion of the chimney.

Image of the old chain grate boiler of the Company

Based on these assessments, the consultant team suggested that the Company should implement the following solutions:

  • Optimizing the combustion process of the boiler to reduce the concentration of oxygen in stack from 16.6% to a minimum of 7%. This solution can reduce the heat loss through stack, providing an expected savings of 92.75 tons of coal per year, equivalent to a fuel cost savings of 176 million VND. With an investment of 220 million VND, the payback period of the solution is 15 months.
  • Or replace the existing coal fired boiler with a higher efficiency biomass-fired fluidized bed boiler. The investment cost of the new boiler installation is estimated at 4,200 million VND, resulting in an expected fuel cost savings of 1,880 million VND, thus the payback period for implementing the solution is over 26 months.

After reviewing the boiler efficiency assessment report conducted by the consulting team, Trang An 2 Company has decided to replace the coal burning boiler with the biomass fired fluidized bed boiler.

General diagram of the new boiler

The outstanding advantages of biomass-fired fluidized bed boiler technology in comparison with the old coal-fired boiler are as follows:

  • Fully automatic or semi-automatic operation; The boiler efficiency is higher than 85%;
  • Fuel sources available, cheap and environmentally friendly such as: logs, sawdust…;
  • Operational costs have been reduced by 25% to 40% in comparison with the operational costs for chain grate boilers;
  • The treatment of stack and dust concentration thoroughly through Cyclone dry dust filter system and wet dust stamping tower; Emissions always meet Vietnam National Environment Standards – QCVN19: 2009/BTNMT;
  • Durable operation boiler, the boiler house area is clean, airy, high aesthetic;
  • Easy to maintain, repair quickly.

According to the evaluation done by national experts after the new boiler has been put into operation, the replacement of the old coal-fired boiler with the biomass-fired boiler will help Trang An 2 Joint Stock Company to save 1,649 million VND of fuel cost annually. With the investment cost of new boiler installation of 4,460 million VND, the project’s payback period is over 32 months.

Moreover, the installation of new biomass boilers means that the complete switching of the fuel use from fossil fuels (coal dust) to the use of biomass fuel. New technology helps the Company to reduce not only production costs, but also contribute to reduce 100% of greenhouse gas emissions (equivalent to 8,699 tons CO2/year) because biomass fuel with short carbon life cycle which is not included as CO2 emission cycle causing greenhouse effect.

Project Management Unit.