Case Study: Optimization of boiler operation to reduce energy consumption at Nutrition Food Joint Stock Company (NutiFood) – Binh Duong
NutiFood Binh Duong – Nutrition Food Joint Stock Company is a subsidiary of Nutrition Food Joint Stock Company, established in 2003. Over 12 years of operation, NutiFood Nutrition Food Joint Stock Company has built a system of product distribution system throughout 64 provinces/cities. The company’s modern production line is imported from advanced countries, meeting requirements of ISO 9001: 2000, HACCP, GMP … NutiFood brand is considered as one of the leading dairy brands in Vietnam.
NutiFood’s original products have 3 groups: feeding nutritional powder, nutritional milk powder and high energy nutritional food …. In order to distribute its products nationwide, the company has built a professional distribution network across 64 provinces and cities, as a result, its revenue has increased more than 250% annually, accounting for the highest share of full cream milk powder.
In addition to product development activities, the Company is also interested in measures to reduce production costs and protect the environment such as energy saving, especially steam systems, in which boiler operation stability and environment friendly are the first concerns of the Company. Because the steam system is considered as the core utility to create a perfect product in terms of quality and competitive prices in the market, while contributing to environmental protection.
With such goal, NutiFood Nutrition Food Joint Stock Company has cooperated with The Central Energy and Boiler Joint Stock Company to build additional steam system including biomass boiler and new steam pipelines to replace the old system that was built earlier in 2013.
In September 2018, the Central Energy and Boiler Joint Stock Company cooperated with experts of the Project “Promotion of Energy Efficient Industrial Boiler Adoption and Operating Practices in Vietnam” of the Ministry of Industry and Trade (MOIT) and United Nations Industrial Development Organization (UNIDO) to carry out the boiler efficiency assessment as well as implement improvement boiler efficiency measures in order to save energy consumption of the operating boiler.
Steam system of the Company
The steam system of NutiFood Binh Duong Company is identified as a key energy user of the Company. The Company’s steam system includes 01 rice husk fired chain grate boiler with a capacity of 6 tons of steam/hour and 01 wood chip fired fluidized bed boiler with a capacity of 15 tons of steam/hour.
Image: Boiler’s fuel
Evaluation of boiler efficiency done by the UNIDO Project’s Experts
Within the framework of the Technical Expert Training Program on boiler efficiency Evaluation Technique, two national experts were sent to the factory to assess 15 tons/hour boiler’s performance from 13th to 15th of September, 2018 with the assistance of an international expert. Chain grate boilers have not been evaluated because the Company is planning to replace it with modern technology fluidized bed boiler in the first quarter of 2019. The findings from this assessment are as follows:
- Boilers operating at average load of over 50%;
- The average stack temperature above 200oC is too high compared to the biomass furnace because the heat exchanger of the economizer of the Factory is broken;
- The average oxygen content of stack is very low accounting for 3.4%, it is possible that the amount of oxygen supplied to the furnace is shortage, making the combustion process incompletely, causing losses due to high percentage of unburned fuel;
- The factory does not have an automatic blowdown controller, no surface blowdown but has only bottom blowdown. The process of blowdown is done manually. The conductivity of blowdown of the boiler that was measured at the field is 295ppm, which is very low compared to the standard of boiler water blowdown. This shows that the volume of blowdown flow during the day is very large – accounting for 10.17%, which leads to unnecessary energy loss;
- The energy efficiency of the boiler calculated by using the indirect method is 61.8%;
The plant has installed insulation of almost pipeline in the steam distribution system. However, there are still some non-insulated locations with relatively high surface temperatures that is above 100 Celsius degree , which causes energy losses due to heat loss to the ambient.
Image: Measuring activities at the Company
Based on the collected data and the above findings, some energy saving solutions are proposed as follows:
- Replace the old and broken economizer with new one to save fuel for the furnace;
- Install an automatic blowdown based on the TDS installing parameter and conductivity settings as allowed;
- Install the feed water treatment system before supplying to the boiler, to ensure the standard of the boiler water as well as increase the efficiency of the boiler;
- Install an oxygen concentration sensor device to control the level of secondary air into the furnace, the suitable oxygen concentration in stack applied for wood chips fired boilers is about 7-9%;
- Insulating steam supply pipelines and valves on steam distribution system to reduce heat loss and save fuel.
Image: Boiler Monitoring Room
After carefully reviewing the energy saving opportunities that were recommended by the national expert team, the factory has implemented the following solution:
- Replace the old economizer with a new one.
- Invest and install in RO feed water treatment system;
- Increase the secondary air to ensure fuel burns completely and optimize combustion mode.
After two months of monitoring, the energy efficiency of the boiler increased from 61.8% to 65.69%, the amount of biomass fuel consumption decreased by 97.5 tons/month. The estimated annual energy saving is 1,172 tons/year, equivalent to the saving of fuel cost of 1,482 million VND. With the total investment to implement the solutions is 01 billion VND, the payback period is 9.7 months.
|Project “Promotion of Energy Efficient Industrial Boiler Adoption and Operating Practices in Vietnam” of MOIT and UNIDO
91 Dinh Tien Hoang, Hoan Kiem, Hanoi
Project Management Unit.