Energy saving in the company: the main directions:
- Electric energy saving
- Reduction of heat and steam losses.
- Loss reduction in steam lines
Saving energy in the company: energy saving methods
- Selection of the optimal price category and review of the energy supply contractual terms.
- Electric motor optimization
- VFD installation
- Optimization of compressed air systems
Choosing the optimal price category for your power supply
In total, there are 6 categories of energy supply prices, according to which companies can buy electricity from guaranteed suppliers.
All small companies 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 companies 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 between 5% and 30%.
The topic of price categories is quite extensive, in our review on price categories, we tell in detail how to correctly calculate and choose the price category of the power supply.
In addition to the price categories, we also recommend taking a close look at other aspects of the power supply contract:
- Voltage level,
- electricity transmission fee.
In our review, you can learn about these and other methods of reducing energy costs.
Saving energy in the company: 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 must become an integral part of the plant's energy conservation program.
This plan will help implement a long-term energy saving system for all electric motors in the company.
The motor control plan will ensure that failures and malfunctions do not occur, and if they do occur, they are resolved quickly and efficiently.
Steps to create a motor control plan:
- Take an inventory of all engines in the facility.
- Create a list of motors with their main parameters, technical condition, service life.
- Develop general instructions for making 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.
Electric motor rewinding
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 exceeds 60% of the cost of a new one.
Then everything will depend on how the rewind is done.
If the work is done at the highest level, the motor will lose only 1% -2% percent of its efficiency.
If rewinding is done poorly, 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 per year.
The payback period for a new energy efficient motor will not exceed 1. 5 - 2 years.
Energy savings in the company by increasing the load factor
Load factor is the ratio of operating power to apparent power.
This is how efficiently energy is used.
The higher the load factor, the more efficiently the electricity will be used.
The electric motor operates optimally at 75% load or more.
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 in less than 45%, by less powerful models,
- redistribution of load between existing electric motors.
Variable Frequency Drive (VFD)
The installation of variable frequency drives only makes sense for dynamic systems.
In static systems, which are involved, for example, only to lift loads, the installation of a frequency inverter will not help and can often damage.
The VFD balances the load and motor speed, ensuring that electrical power is used optimally.
The VFD can reduce motor power consumption by a minimum of 5% and a maximum of 60%.
VFD's payback period is typically 1-3 years.
Optimization of compressed air systems
Compressed air is used in a wide variety of industries.
In some companies, compressed air is the main consumer of electricity.
Compressed air is used in pneumatic devices and equipment, in 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 is converted into useful work, the remaining 95% goes into the pipeline.
Energy savings in the company: compressed air:
- Do not use compressed air to clean the room.
- Reducing the air temperature at the compressor inlet by 3% reduces energy consumption by 1%.
- For these technical processes, when possible, reduce the compressed air pressure to a minimum. Lowering the pressure by 10% reduces energy consumption by 5%.
- Perform periodic inspections, repairs of compressor equipment and compressed air transmission lines. One, even the smallest compressed air leak can sometimes reduce equipment efficiency.
Energy savings in the company: 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 more 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 operates below its optimal load.
The installed boiler capacity may be much greater than the company's needs, due to a drop in demand for products or unrealized plans to expand production.
In addition, 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 does not operate at full capacity or in short cycle on / off mode.
Both situations lead to significant energy losses.
There are no simple and inexpensive solutions to this problem.
The simplest option isinstall a "small" boiler operating at full capacitywith a medium or low workload in the company.
Although this is not a cheap solution, the payback period for such investment can be less than two years.
And in general, it is always more efficient to have several interchangeable small boilers, especially in companies with changing demand or significant seasonal fluctuations in heat and steam consumption.
Automatic regulation system
If the company has several boilers, then it makes sense to installautomatic system to regulate the boiler load. . .
Automation responds to the need for steam in the company, redistributing the load between the boilers, turning the boilers on or off, thus significantly increasing the efficiency of the entire system.
In companies where boilers are regularly shut down due to a drop in steam demand, heat losses through the stack can be quite high.
It is possible to block the loss of hot air through the chimney. installing a gate valvethat closes the pipe when the boiler is off.
Prevention and maintenance
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 components of the boiler 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: the heat loss from the surface of a properly insulated boiler must be less than 1%.
Soot and scale removal
It is necessary to constantly monitor and eliminate the formation of soot in 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 in the boiler heat exchanger.
The 1 millimeter thick scale increases power consumption by 2%.
Soot and scale can be removed mechanically or with acids.
Soot and scale formation can be determined by increasing the flue gas temperature or by visual inspection when the boiler is not operating.
The formation of soot and scale must be carefully controlled if the boiler works with solid fuels (coal, peat, firewood).
Gas boilers are less prone to soot problems.
Boiler blowdown optimization
The boiler blowdown is the discharge of water from the boiler to clean the water inside the boiler of impurities and salts.
The purpose of flushing the boiler is to prevent or reduce scale formation.
Insufficient boiler venting can cause water to enter the steam or build up deposits in the boiler.
Excessive bleeding means loss of heat, water, and chemicals.
The optimum level of blowdown depends on the type of boiler, the operating pressure in the boiler, the preparation and the quality of the water used.
The first thing to pay attention to is the preparation of the water. If the water is well treated (low salt content), the purge rate can be 4%.
If there are foreign substances and salts in the water, the purge rate will be 8% to 10%.
The automatic purge system can also significantly reduce energy consumption.
The payback period for such a system is typically 1-3 years.
Smoke emission reduction
Excessive smoke is often the result of air penetrating 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 that is used to burn fuel, the more heat is thrown into the wind.
A quantity of air slightly higher than the ideal stoichiometric fuel / air ratio is necessary 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 smoke emissions.
An efficient gas burner requires 2% to 3% supplemental oxygen, or 10% to 15% supplemental air, to burn fuel without generating carbon monoxide.
The general rule of thumb is that boiler efficiency increases by 1% for every 15% additional air reduction.
Therefore, it is necessary to constantly check the air / fuel ratio.
This event costs nothing, but 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 is filtered into the boiler through holes and leaks.
The presence of leaks and holes can be easily detected by establishing a monitoring system for the incoming air and the amount of oxygen in the flue gases.
Using the data on the amount of carbon monoxide and oxygen, it is possible to optimize the fuel / air ratio in the boiler.
Installing a system for monitoring and analyzing smoke emissions usually pays for itself in less than a year.
Saving energy in the company: 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 turn into steam, which saves fuel.
The boiler efficiency 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 for itself in less than 2 years.
Heat exchanger to extract heat from the water and steam from the boiler blowdown
The heat exchanger will help recycle approximately 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 purge system does not work in constant mode, then it makes sense to think about transferring it to a constant mode while simultaneously installing a heat exchanger.
The average recovery period of a heat exchanger shall not exceed 1. 5 to 2 years.
Installing a condensation economizer
The hot condensate can be returned to the boiler, saving energy and reducing the need for treated water.
The Condensation Economizer can increase system efficiency by an additional 10%.
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 the condensate to the boiler usually pays off 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 casts heat into the wind.
Energy saving potential in cooling towers:
- In some companies it makes sense to abandon cooling towers entirely. There are many cases where heating is used to heat a room and at the same time a cooling tower is used to dissipate the heat. Installing a heat pump will solve the heating problem and at least partially reduce the need to use the cooling tower.
- Installing cooling tower fan circuit breakers can reduce power consumption by 40%.
- Replacing aluminum or iron fans with new fans (fiberglass and molded plastic) can reduce power consumption by up to 30%.
Loss reduction in steam lines
Disconnection of unclaimed steam lines
Steam requirements 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 from 20% to 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 costly and perhaps not feasible.
However, identifying and shutting down steam lines that are rarely used can be a very effective energy saving measure.
Energy savings in the company - Thermal insulation of pipes
Insulating steam pipes can reduce energy losses by up to 90%.
This is one of the fastest energy savings in a steam distribution system.
The average payback period for insulating pipes through which steam or hot water is transmitted is approximately 1 year.
Condensate pipes for 1. 5-2 years.
Steam trap monitoring
A simple program to monitor the technical condition of steam traps can significantly reduce heat loss.
For example, if maintenance has not been done for 3-5 years, then as a rule about a third of steam traps are out of order, allowing steam to seep into the condensate drain system.
In practice, in companies that have a steam trap monitoring program, no more than 5% of the steam traps are in a faulty condition.
The average payback period for a steam trap replacement or maintenance is less than six months.
A steam trap monitoring program will generally 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
- open when the temperature approaches the saturated steam level (+/- 2 C °),
- emit non-condensable gases after each opening and
- they are in an open state at the beginning of the system's operation, which ensures their rapid heating.
In addition, these steam traps are very reliable and can be used in a wide range of pressures.
Disconnect steam traps
You can reduce energy consumption by turning off steam traps on superheated steam lines when not in use.
Elimination of steam leaks
A small hole steam leak repair program can pay off in less than 3-4 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 the condensate, can be used in a heat exchanger to heat the water or feed air.
Most importantly, it is possible to use this steam and condensate close to the point of release, as it can be very expensive to create a separate piping system to transport it to the point of use.