Energy saving at the enterprise - the main directions:
- Saving electrical energy
- Reduction of heat and steam losses
- Reduction of losses in steam lines
Energy Saving in the Enterprise - Energy Saving Methods
- Selection of the optimal price category and revision of the contractual terms of power supply
- Optimization of electric motors
- VFD installation
- Optimizing compressed air systems
Choosing the optimal price category for power supply
In total, there are 6 power supply price categories, according to which enterprises can buy electricity from guaranteed suppliers.
All small enterprises with an installed capacity of less than 670 kW, at the time of concluding a contract for an automatic power supply, fall into the first price category.
All enterprises with an installed capacity of more than 670 kW automatically fall into the third price category.
The first and third price categories are not always the most optimal and cheapest power supply categories.
In some cases, switching to a different price category can reduce the cost of electricity by 5% -30%.
The topic of price categories is quite extensive, in our review about price categories, we tell you in detail how to correctly calculate and choose the price category of power supply.
In addition to price categories, we also recommend taking a close look at other aspects of the power supply contract:
- voltage level,
- electricity transmission tariff.
In our review, you can find out about these and other methods to reduce energy costs.
Energy Saving in the Enterprise - Electric Motors
It is necessary to take into account all equipment where electric motors are used:
- machine tools,
- production lines.
Electric motor control plan
The motor control plan should become an integral part of the plant's energy conservation program.
Such a plan will help implement a long-term energy saving system for all electric motors in the enterprise.
The motor control plan will ensure that failures and malfunctions do not occur, and if they do, are resolved quickly and efficiently.
Steps to create a motor control plan:
- Conduct an inventory of all engines in the facility.
- Create a list of engines with their main parameters, technical condition, service life.
- Develop general instructions for carrying out repairs.
- Develop guidelines for preventive maintenance, lubrication and inspection.
- Create a safety stock of frequently used spare parts.
- Create a purchase specification for new engines.
Rewinding electric motors
Generally, rewinding an old electric motor is much cheaper than buying a new one.
The electric motor should be replaced if the cost of rewinding it is more than 60% of the cost of a new one.
Then everything will depend on how the rewind is carried out.
If the work is done at the highest level, then the motor will lose only 1% -2% percent of its efficiency.
If the rewinding is carried out poorly, then the losses in the electric motor will increase by 5% -10%.
Replacing the old electric motor with a new energy efficient one makes sense in cases where the motor runs more than 2000 hours a year.
The payback period for a new energy efficient engine will be no more than 1. 5 - 2 years.
Energy saving in the enterprise by increasing the load factor
Load factor is the ratio of operating power to apparent power.
That is, how efficiently energy is used.
The higher the load factor, the more efficiently the electricity is used.
The electric motor operates optimally at 75% load and above.
Therefore, installing motors above the required power (for safety reasons) will not only be more expensive, but also inefficient in terms of energy consumption.
The load factor can be increased as follows:
- shutdown of unloaded engines,
- replacement of engines, which are loaded by less than 45%, for less powerful models,
- redistribution of the load between the existing electric motors.
Variable frequency drive (VFD)
Installation of variable frequency drives only makes sense for dynamic systems.
In static systems, which are involved, for example, only for lifting loads, the installation of a variable frequency drive will not help, and often can do harm.
Variable Frequency Drive balances the load and speed of the motor, thereby ensuring that electrical power is used optimally.
The VFD can reduce the energy consumption of the motor by a minimum of 5% and a maximum of 60%.
The payback period for VFD is usually 1-3 years.
Optimization of compressed air systems
Compressed air is used in a wide variety of industries.
In some enterprises, compressed air is the main consumer of electricity.
Compressed air is used in pneumatic devices and equipment, on conveyors, automatic lines.
The use of compressed air is popular because it is a convenient and safe source of energy.
But many people forget that compressed air is one of the most inefficient sources of energy - only 5% of the electricity spent on compressed air production turns into useful work, the remaining 95% goes out into the pipe.
Energy saving in the enterprise - compressed air:
- Do not use compressed air to clean the premises.
- Reducing the air temperature at the compressor inlet by 3% reduces power consumption by 1%.
- For those technical processes, where possible, reduce the compressed air pressure to a minimum. Lowering the pressure by 10% reduces power consumption by 5%.
- Carry out regular inspections, repairs of compressor equipment and compressed air transmission lines. One, even the smallest leakage of compressed air, can reduce the efficiency of the equipment at times.
Energy saving at the enterprise - we reduce heat and steam losses
Steam is often used in industry, especially in the textile, food and processing industries.
Improving the efficiency of steam boilers and reusing the generated heat can significantly reduce energy consumption in these plants.
The boiler works most efficiently at full power.
Due to the fact that the demand for the amount of steam can change over time, it often happens that the boiler works below its optimal load.
The capacity of the installed boiler can be much higher than the needs of the enterprise, due to a drop in demand for products, or unrealized plans for expanding production.
Also, the boiler capacity may not be required due to improvements in the production process or the introduction of energy saving measures.
In such cases, the boiler works either not at full capacity, or in the mode of short on-off cycles.
Both of these situations entail significant energy losses.
There are no simple and cheap solutions to this problem.
The easiest option isinstall a "small" boiler that will work at full capacityat an average or low workload in the enterprise.
Despite the fact that this is not a cheap solution, the payback period for such an investment can be less than two years.
And, in general, it is always more efficient to have several small interchangeable boilers, especially in enterprises with changing demand or significant seasonal fluctuations in heat and steam consumption.
Automatic regulation system
If the enterprise has several boilers, then it makes sense to installautomatic boiler load regulation system. . .
Automation responds to the need for steam at the enterprise, redistributing the load between the boilers, turns on or off the boilers, thereby significantly increasing the efficiency of the entire system.
In enterprises where boilers are regularly shut down due to a drop in steam demand, heat losses through the chimney can be quite high.
It is possible to block the loss of hot air through the chimneyby installing a gate valvewhich closes the pipe when the boiler is turned off.
Prevention and maintenance
If left unattended, burners and condensate return systems can quickly deteriorate or fail.
This can reduce the efficiency of the boiler by 20% -30%.
A simple maintenance program - ensuring that all boiler components are operating at their maximum level - will significantly increase operating efficiency.
In practice, regular maintenance reduces the energy consumption of the boiler by 10%.
Insulation - heat loss from the surface of a properly insulated boiler should be below 1%.
Removal of soot and scale
It is necessary to constantly monitor and eliminate the formation of soot on the boiler tubes, scale inside the boiler.
A 0. 8 millimeter thick layer of soot reduces heat transfer by 9. 5%, while a 4. 5 millimeter thick layer reduces heat transfer by 69%!
Scale forms when calcium, magnesia, and silicon are deposited on the boiler heat exchanger.
1 millimeter thick scale increases energy consumption by 2%.
Soot and scale can be removed mechanically or with acids.
The formation of soot and scale can be determined by an increase in the temperature of the flue gases or by visual inspection when the boiler is not in operation.
The formation of soot and scale must be monitored especially carefully if the boiler runs on solid fuels (coal, peat, firewood).
Gas boilers are less prone to soot problems.
Boiler blowdown optimization
Boiler blowdown is the discharge of boiler water to clean the water inside the boiler from impurities and salts.
The purpose of the boiler blowdown is to avoid or reduce the formation of scale.
Insufficient boiler blowdown can lead to water entering the steam, or the formation of deposits in the boiler.
Excessive blowdown means loss of heat, water and chemicals.
The optimum blowdown level depends on the type of boiler, the operating pressure in the boiler, the preparation and quality of the water used.
The first thing to pay attention to is water preparation. If the water is well treated (low salt content), the blowdown rate can be 4%.
If there are foreign substances and salts in the water, then the blowdown level will be 8% -10%.
The automatic blowdown system can also significantly reduce energy consumption.
The payback period for such a system is usually 1-3 years.
Reduction of smoke emissions
Excessive smoke is often the result of air penetration into the boiler and chimney through leaks and openings.
This reduces heat transfer and increases the load on the compressor system.
Leaks and holes can be easily eliminated, it is only necessary to periodically carry out a visual inspection of the boiler and chimney.
The more air is used to burn fuel, the more heat is thrown into the wind.
An amount of air slightly above the ideal stoichiometric fuel / air ratio is required for safety reasons, to reduce NOx emissions, and depends on the type of fuel.
Boilers in poor technical condition can use up to 140% additional air, resulting in excessive flue emissions.
An efficient gas burner requires 2% to 3% supplemental oxygen, or 10% to 15% supplemental air, to burn the fuel without generating carbon monoxide.
The general rule of thumb is that boiler efficiency increases by 1% for every 15% reduction in additional air.
Therefore, it is necessary to constantly check the fuel / air ratio.
This event costs nothing, but it has a very good effect.
Smoke emission monitoring
The amount of oxygen in the flue gas is the sum of additional air (added to increase safety and reduce emissions) and air that seeps into the boiler through holes and leaks.
The presence of leaks and holes can be easily detected if a monitoring system for the incoming air and the amount of oxygen in the flue gases is established.
Using the data on the amount of carbon monoxide and oxygen, it is possible to optimize the fuel / air ratio in the boiler.
The installation of a monitoring and analysis system for flue emissions usually pays for itself in less than a year.
Energy Saving in the Enterprise - Installing an Economizer
The heat from the flue gases can be used to heat the water entering the boiler.
The heated water enters the boiler and requires less heat to be converted into steam, thereby saving fuel.
The efficiency of the boiler increases by 1% for every 22 ° C decrease in the flue gas temperature.
The economizer can reduce fuel consumption by 5% - 10% and will pay off in less than 2 years.
Heat exchanger for extracting heat from water and steam from boiler blowdown
The heat exchanger will help to recycle about 80% of the water and steam heat from the boiler blowdown.
This heat can be used to heat buildings or to heat the water that feeds the boiler.
Any boiler with a constant blowdown rate of 5% or more is an excellent candidate for a heat exchanger.
If the blowdown system does not operate in a constant mode, then it makes sense to think about transferring it to a constant mode with the simultaneous installation of a heat exchanger.
The average payback period for a heat exchanger will not exceed 1. 5 - 2 years.
Installing a condensing economizer
Hot condensate can be returned to the boiler, thereby conserving energy and reducing the need for treated water.
The condensing economizer can increase the efficiency of the system by an additional 10%.
The installation of such an economizer should be carried out under the close supervision of specialists who will take into account all the nuances of such a system, its effect on the boiler and the chemical composition of the water.
Using a system that returns condensate back to the boiler usually pays for itself in 1-1. 5 years.
A system that directs condensate to a hot water supply pays for itself in less than a year.
Cooling towers (cooling towers)
A cooling tower is a heat exchanger in which water is cooled by a stream of air.
And in terms of energy efficiency, a cooling tower is a device that dumps heat into the wind.
Energy saving potential in cooling towers:
- In some enterprises, it makes sense to abandon cooling towers altogether. Cases are not alone when heating is used to heat a room and at the same time a cooling tower is used to dissipate heat. Installing a heat pump will solve the heating issue and at least partially reduce the need to use the cooling tower.
- Installing circuit breakers for cooling tower fans can reduce energy consumption by 40%.
- Replacing aluminum or iron fans with new fans (fiberglass and plastic molded) can reduce energy consumption by up to 30%.
Reduction of losses in steam lines
Disconnecting Unclaimed Steam Lines
Steam needs and consumption are constantly changing.
This can lead to the fact that the entire steam distribution system is not used at full capacity, but only 20% -50%, which inevitably leads to heat losses.
It is clear that optimizing or reconfiguring the entire steam distribution system to meet new needs will be very expensive and, perhaps, not feasible.
However, identifying and shutting down steam lines that are hardly used can be a very effective energy saving measure.
Energy saving at the enterprise - Thermal insulation of pipes
Insulating steam pipes can reduce energy losses by up to 90%.
This is one of the fastest return on energy savings in a steam distribution system.
The average payback period for insulation of pipelines through which steam or hot water is transmitted is about 1 year.
Condensate pipes for 1. 5-2 years.
Monitoring of steam traps
A simple monitoring program for the technical condition of steam traps can significantly reduce heat loss.
For example, if maintenance has not been carried out for 3 to 5 years, then, as a rule, about a third of steam traps are out of order, allowing steam to seep into the condensate drain system.
From practice, in enterprises that have a monitoring program for steam traps, no more than 5% of steam traps are in a faulty condition.
The average payback period for replacement or maintenance of one steam trap is less than six months.
Trap monitoring programs typically reduce steam losses by 10%.
Thermostatic steam traps
The use of modern thermostatic steam traps can reduce energy consumption and at the same time increase the reliability of the entire system.
The main advantage of thermostatic steam traps is that they
- open when the temperature approaches the level of saturated steam (+/- 2 C °),
- emit non-condensable gases after each opening and
- are in the open state at the beginning of the system operation, which ensures its rapid heating.
Also, these steam traps are very reliable and can be used over a wide range of pressures.
Disconnecting steam traps
You can reduce energy consumption by turning off steam traps on the superheated steam lines when not in use.
Elimination of steam leaks
A small hole steam leak repair program can pay off in less than 3 to 4 months.
We must not forget that small leaks can go unnoticed for years, constantly damaging the system.
Reuse of condensate and steam
When a steam trap discharges condensate from a steam system, the pressure drop creates steam from that condensate.
This steam, together with condensate, can be used in a heat exchanger to heat feed water or air.
Most importantly, it is possible to use this steam and condensate close to the point of release, as it can be very costly to create a separate piping system to transport it to the point of use.