Automatic control of the excess air ratio in steam boilers

Optimizing the excess air ratio in steam boilers makes it possible to significantly reduce chimney losses and coal consumption. Thanks to automatic control, DB Energy achieved annual savings of 13.09 MWh of energy and improved boiler house efficiency in a food processing plant.

Challenge

In the food industry, steam boilers are a key source of energy, and their efficiency directly affects production costs. An analysis of the operation of grate boilers showed that the largest energy loss was chimney loss, caused by excess air in the flue gases and high outlet flue gas temperature.

An excessively high excess air ratio (λ) reduced boiler efficiency and increased coal consumption, while manual control did not allow optimal parameters to be maintained throughout the entire boiler operating cycle.

Our approach

The DB Energy team carried out:

measurements of the excess air ratio λ and outlet flue gas temperature,
tests of excess air control by adjusting the performance of primary air and exhaust fans,
analysis of boiler control parameters such as: furnace chamber pressure, amount of secondary air, outlet medium temperature, and boiler output regulation,
development of a concept for automatic boiler house control based on precise measurements and control algorithms.

Automation enabled maintaining the optimal λ ratio throughout the entire boiler operating cycle, eliminating the risk of operator errors and allowing quick response to process parameter changes.

Solution

The modernization included:

installation of an automatic control system for the operation of primary air and exhaust fans,
integration of temperature, pressure, and air flow measurements into the control system,
optimization of boiler house control algorithms in real time.

The investment costs amounted to PLN 1.2 million, with relatively high savings achieved as a result of the modernization.

Results

The measures taken by DB Energy resulted in:

reduction of annual energy consumption: 13.09 MWh,
financial savings: PLN 702,100 annually,
improved boiler efficiency through maintaining the optimal excess air ratio,
reduced chimney losses and better utilization of fuel energy,
elimination of operator error risk and faster response to boiler parameter changes.

Conclusions

Automatic control of the excess air ratio allows an easy and fast way to increase the efficiency of steam boilers, reduce fuel consumption, and lower energy costs.

The example from the food industry shows that precise control and automation of boiler house processes deliver measurable benefits in a short time.

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