In the final installment of our three-part technical series on energy efficiency, we expand our scope beyond grinding and pelleting to encompass the entire facility. Discover how optimizing steam networks, compressed air systems, and VFDs coupled with AI-driven analytics, EMS integration, and ISO 50001 frameworks can unlock 15% to 25% total energy savings across your feed mill.
WAYS TO INCREASE ENERGY EFFICIENCY - STEAM AND WASTE HEAT RECOVERY
One of the most effective methods to enhance energy efficiency in feed mills is the recovery and utilization of process waste heat. Waste heat released from the exhaust air of dryers and coolers, as well as from compressed air compressors, can be utilized for preheating boiler feedwater, producing domestic hot water, or powering process heating applications.
Field applications where hot air discharged from compressed air compressors is used for water heating have achieved particularly successful results, enabling significant energy recovery without additional fuel consumption.
Furthermore, through economizer and flue gas recuperator applications in steam boilers, boiler feedwater can be preheated by utilizing the heat from flue gas. Depending on operating conditions, these applications can deliver approximately a 5–15% increase in total fuel efficiency.
REDUCING HEAT LOSSES IN STEAM PIPING
To maintain the efficiency achieved in steam generation, it is critical to convey the generated energy to the process point with minimal losses. To this end, the boiler room, steam pipelines, valves, flanges, and other equipment should be insulated with high-performance insulation materials of appropriate thickness.
Additionally, installing complete condensate lines and returning the resulting condensate to the boiler feedwater yields savings in both water and energy. Recovering flash steam reduces thermal energy losses, thereby increasing the overall efficiency of the steam system.
OXYGEN PROBE AND BURNER FAN INVERTER APPLICATIONS
Continuous monitoring of flue gas oxygen levels is one of the most vital practices for enhancing combustion efficiency in steam boilers. By operating an oxygen probe placed at the boiler flue outlet in tandem with a frequency converter (VFD) on the burner air fan, combustion air can be automatically optimized.
This prevents combustion with excess air, reduces flue gas losses, and ensures that the boiler operates at peak combustion efficiency. Under suitable operating conditions, this application can deliver natural gas savings of between 8% and 15%.
CONTINUOUS MONITORING OF STEAM AND NATURAL GAS CONSUMPTION
The fundamental principle of energy management is measuring and analyzing consumption. Therefore, data collected from a steam flow meter installed at the steam boiler outlet should be evaluated together with natural gas meter data to continuously monitor boiler efficiency.
By regularly comparing the amount of steam produced with the natural gas consumed, early detection can be achieved for:
- Drops in boiler efficiency,
- Degradation in combustion settings,
- Insulation-related losses,
- Steam leaks, and
- Operational inefficiencies,
allowing necessary improvements to be planned proactively.
SELECTING THE RIGHT STEAM BOILER CAPACITY
Steam boilers reach their highest combustion efficiency when operating at loads close to their nominal capacity. Therefore, sizing the boiler capacity appropriately according to the plant’s average and peak steam demands is of critical importance for energy efficiency.
Boilers oversized relative to operational requirements are forced to run at low loads for extended periods. This results in frequent start-stop cycles, increased stack losses, and higher specific natural gas consumption.
In field trials conducted on a steam boiler with a capacity of 4,000 kg/h, evaluations were carried out at steam production levels of 4,000, 3,000, 2,000, and 1,000 kg/h. Results demonstrate that when the boiler load drops below 75%, and especially below 50%, natural gas consumption per unit of steam produced increases by approximately 10–20%.
For this reason, when determining boiler capacity in new investments, project planners must consider not only maximum production demand but also the average annual steam consumption of the plant. Proper capacity selection reduces fuel costs while ensuring stable, high-efficiency boiler operation.
TECHNICAL EVALUATION
In feed mills, a steam system consists of far more than just the steam boiler itself. The boiler, economizer, steam distribution network, condensate system, combustion controls, and consumption points must be evaluated as a holistic system. Field studies show that proper design and regular monitoring of the steam system can achieve a 10–20% improvement in natural gas consumption and an indirect 3–8% reduction in electricity consumption.
PROCESS TIME ANALYSIS AND LINE OPTIMIZATION
Energy efficiency is influenced not only by equipment performance but also by proper process flow management. Identifying bottlenecks on the production line and minimizing waiting times between processes increases output capacity while reducing specific energy consumption.
Unnoticed short delays during production cause equipment to idle, raising overall energy consumption. Conducting time-motion analyses on the production line helps optimize every process step, ensure line synchronization, and streamline bottleneck points.
VARIABLE FREQUENCY DRIVES (VFD)
Variable Frequency Drives (VFD) are among the most effective tools for preventing unnecessary energy consumption by ensuring motors run strictly at the required speeds.
Deploying VFDs on fans, pumps, elevators, conveyors, and compatible mill motors allows motor speed to adjust according to load demand. This practice can yield electricity savings of 5–15%, particularly in equipment operating under variable loads.
Equipment that does not require continuous full-load operation, such as cooler fans, represents systems where VFD applications deliver the highest return on investment.
PROPER EQUIPMENT SELECTION
Sizing equipment to match actual process needs is a fundamental principle of energy efficiency. Equipment with oversized motor capacities often operates at partial loads, decreasing efficiency and causing unnecessary electricity consumption.
In field studies, detailed measurements and analyses revealed that a cooler fan with a 90 kW motor could deliver identical process performance with a 55 kW motor. Making this replacement resulted in an electricity savings of approximately 40%.
This example underscores the importance of considering real process demands rather than relying solely on safety margins during equipment selection.
REDUCING UNPLANNED DOWNTIME AND BREAKDOWNS
Unplanned breakdowns and short-term stops during production do not merely result in lost capacity; they also adversely affect energy consumption.
When any piece of equipment on the production line stops, other machinery is forced to run idle or consume extra energy due to high starting currents during restarts.
Field observations indicate that shutdown and restart cycles can induce additional energy losses on the order of 10–15% of total consumption.
Consequently, implementing:
- Planned maintenance,
- Predictive maintenance, and
- Condition monitoring systems
is strongly recommended to minimize unplanned downtime.
PROCESS AUTOMATION AND DIGITALIZATION
SCADA and PLC-based automation systems are vital tools for ensuring sustainable energy management.
By continuously monitoring and automatically controlling process parameters in real time such as:
- Motor current,
- Moisture levels,
- Temperature,
- Pressure,
- Steam consumption, and
- Electricity consumption
mills can maintain product standards while preventing energy waste.
AI-assisted predictive maintenance applications forecast equipment failures before they occur, reducing unplanned downtime and maintaining equipment operation at optimum efficiency.
Furthermore:
- Automatically switching idling motors to sleep mode,
- Optimizing purge durations based on process requirements, and
- Ensuring line synchronization
can yield an overall improvement of 15–20% in total electricity consumption.
OPTIMIZATION OF COMPRESSED AIR SYSTEMS
Although compressed air systems are not direct production processes, they represent major electricity-consuming auxiliary utilities in feed mills. Air leaks, excessively high operating pressures, and inefficient compressor operations lead to substantial energy losses.
For instance, in a 50 tph feed mill, a 75 kW air compressor accounts for approximately 5% of total electricity consumption. By eliminating air leaks, optimizing system pressure, and operating the compressor according to actual demand, this share can be reduced to 3–4%, offering energy savings of 10–40% depending on plant conditions.
Therefore, compressed air systems require regular leak inspections, compressor pressure setpoints tailored to process requirements, and the adoption of variable-speed (VFD) compressors wherever feasible.
Operating compressors at pressures higher than necessary directly increase energy consumption. Compressor discharge pressure should be set according to the facility’s actual air requirements, avoiding unnecessarily high pressures.
In test trials comparing compressor operation at 6.5, 7.0, and 7.5 bar pressure levels, results revealed that every 0.5 bar increase in pressure led to an approximate 6.8% rise in electricity consumption.
Thus, resolving air leaks, setting appropriate pressure levels, and using VFD-controlled compressors offer significant energy savings potential in compressed air systems.
TECHNICAL EVALUATION
Energy efficiency becomes sustainable not by upgrading a single piece of equipment, but through the joint optimization of process management, equipment selection, automation, maintenance practices, and auxiliary facilities. Field applications show that this holistic approach can deliver an overall energy consumption improvement of 15–30% in feed mills.
ENERGY MANAGEMENT SYSTEMS (EMS) AND DIGITAL ENERGY MONITORING
The core principle of energy efficiency is accurate consumption measurement and the effective use of collected data in decision-making processes. The traditional management axiom, “You cannot manage what you do not measure,” must be expanded today into a more comprehensive perspective:
“If you do not transform measured data into actionable insights and apply them in decision-making, effective energy management is impossible.”
In this context, smart energy analyzers should be installed on grinders, mixers, pellet presses, compressors, and other high-consumption equipment, with all measurements integrated into SCADA and Energy Management System (EMS) infrastructures.
Real-time monitoring allows parameters like:
- Energy consumption per ton (kWh/t),
- Motor load ratios,
- Steam consumption,
- Natural gas consumption,
- Output capacity, and
- The impact of formulation changes on energy usage
to be tracked instantaneously and analyzed using decision-support systems.
For example, changes in energy consumption resulting from increased fat levels or high-binding raw materials in feed formulations can be monitored directly, allowing for the determination of optimal formulation structures.
To ensure sustainable energy management, facilities should establish an ISO 50001 Energy Management System or a similar management framework, define Key Performance Indicators (KPIs), report on them regularly, and drive operations through a continuous improvement approach.
ECONOMIC AND ENVIRONMENTAL BENEFITS OF ENERGY EFFICIENCY
Energy efficiency investments are not merely technical initiatives that cut operating costs; they are strategic investments that enhance environmental performance and international competitiveness.
Reducing energy consumption:
- Lowers unit production costs, boosting market competitiveness.
- Decreases carbon footprints, advancing sustainability goals.
- Increases operational resilience against energy price fluctuations.
- Simplifies compliance with environmental certifications and sustainability criteria demanded in international markets.
- Strengthens corporate reputation and brand value.
COST-EFFECTIVENESS AND INVESTMENT PRIORITIES
The payback period for energy efficiency initiatives varies depending on the investment scale and project scope.
When establishing implementation priorities, decision-makers should evaluate investment costs alongside energy savings potential, impacts on production capacity, and maintenance requirements.
CONCLUSION AND FUTURE OUTLOOK
Energy efficiency in the feed sector has evolved beyond a simple cost-reduction activity into a foundational pillar of sustainable manufacturing, low-carbon economics, and global competitiveness.
Field applications and the trial results presented in this article demonstrate that total energy savings of 15–25% can be achieved in feed mills through process optimization, effective steam management, proper equipment selection, automation, and data-driven energy management. With targeted applications, this rate can reach even higher levels in specific processes.
Looking ahead, the widespread adoption of AI-supported decision systems, digital twins, predictive maintenance technologies, and real-time energy management systems will enable even more precise control over energy performance in feed mills.
Green transformation, carbon footprint management, and energy efficiency must now be viewed not only as environmental responsibilities, but as strategic imperatives for market access, corporate sustainability, and long-term profitability.
Facilities that embed continuous energy improvement into their corporate culture will gain lower production costs, higher operational efficiency, and a stronger competitive edge.
Pusulay Engineering & Consultancy provides consulting services focused on engineering, operational management, and productivity to feed industry businesses by analyzing operational processes backed by 21 years of sector expertise.
We continue to support and add value to feed sector enterprises through specialized solutions including shrinkage management, energy efficiency, operating cost optimization, capacity expansions, breakdown and downtime improvements, site audits, feed mill investments, feasibility studies, regional market analyses, and operational SWOT analyses.
Other articles in this series: