![]() |
|
![]() |
|
![]() |
|
![]() |
With the rising cost of fuel prices, industries that use steam boilers for heating or power generation are hard pressed to operate at peak efficiencies.
While steam consumption, leakages, and other heat transmission losses can contribute to the overall energy bill, this article focuses on the heart of the steam generator - the boiler.
Controlling the boiler is of utmost importance in any steam generation energy saving program. Below are some ways to improve boiler efficiencies:
Reducing Excess Air
By far the most common reason for energy inefficiencies in a boiler can be attributed to the use of excess air during combustion at the burners. When there is more air than is required for combustion, the extra air becomes heated up and is finally discharged out to the atmosphere. However, there are reasons for putting in some extra air for combustion - to compensate for imperfect burner fuel-air mixing conditions, air density changes, control system "slop", burner maintenance, fuel composition and viscosity variation, and imperfect atomizing steam or air controls for burners.
Adjusting the fuel-air ratio for combustion can be quite tricky. If the fuel is too much as compared to the air, incomplete combustion occurs. This will give rise to carbon soot deposits inside the combustion chamber or even over the boiler tubes.
The consequences of having soot deposits over the heat transfer surfaces and the potential of having explosive flue gases inside the boiler are much worst than losing a slight amount of energy through the exhaust stack. Therefore, many boiler operators choose to adjust their burners to be slightly on excess air.
Installing Economizer
This is only appropriate if there are insufficient heat transfer surfaces in the boiler. The economizer tubes may contain either circulating boiler water or circulating feed water. Because the temperature of the exhaust gases can be quite high, the economizer tubes may be fitted with safety valves to avoid over-pressure damage. Also temperature control of feed water is required to prevent pump airlock. To avoid corrosion, careful design is needed to ensure that the exhaust flue gas temperature does not drop below the dew point.
Reducing Scale and Deposits
For any boiler operation, this is a must. The safety of the boiler is at stake. Any scale or deposits will lead to reduced heat transfer that will eventually lead to overheating, reduction of mechanical strength of the steel and finally to bursting.
This should already be in the normal daily procedure of boiler operation.
Reducing Blow down
Blow down of boiler water is discharging hot water into the drains. However, blow down is necessary to maintain the boiler water concentration of dissolved solids that are necessary for conditioning the boiler water. The dissolved solids are necessary for preventing boiler corrosion and scaling.
As steam is generated from the evaporation of water, the remaining water in the boiler becomes more and more concentrated. This must be drained away during blow down.
The challenge is to control the draining to the minimum.
Recovering Waste Heat from Blow down
Since it is necessary to blow down to control the total dissolved solids in the boiler water, methods can be adopted to recover back some of the heat from the drained hot water.
Blow down tanks, heat exchanger tubes and pumping arrangements can be fabricated to recover some of the heat back into the boiler.
Stopping Dynamic Operation
Whenever a boiler starts or stops, a few minutes are spent running the forced draft fan for purging the combustion chamber of unburnt gases. This is a necessary step for the safe operation of a boiler.
During this time the heat from the boiler water in the shell or tubes will be lost to the purging air.
To avoid this type of losses, it is better to maintain a steady firing condition in the boilers.
Reducing Boiler Pressure
By reducing the boiler pressure, some of the heat losses through leakages or transmission may be reduced slightly. However there can be problems with the boiler with reduced pressure. The boiler circulation may be upset and the steam lines may have insufficient capacity and flow to transport the low pressure steam.
Operating at Peak Efficiency
When operating two or more boilers, improved efficiency can sometimes be obtained by unequal sharing of the load so that the combined load operates at peak efficiency.
Preheating Combustion Air
Any heat loss from the skin of the boiler to the boiler room can be utilized back for combustion. By preheating the intake air the combustion in the furnace becomes more efficient.
Switching from Steam to Air Atomization
For burners with steam atomization, switching to air atomization will naturally result in less steam consumption overall and better boiler efficiencies. This is only applicable for heavy fuel oil burners.
Switching to Lower Cost Fuel
When comparing natural gas and fuel oil, if the cost is the same or more per BTU delivered, switch over to fuel oil.
The reason for this is that in the combustion process, hydrogen combines with oxygen to form water. The latent heat of vaporization is lost when water vapor leaves the boiler stack.
Fuels like natural gas with higher hydrogen to carbon ratio will lose this heat more than those with lower hydrogen-carbon ratio like fuel oil.
However one must also recognize that there will be increased maintenance, operating costs and greater need for more excess air in order to achieve complete combustion for fuel oil. In addition, soot deposits and incomplete combustion might also affect the overall costs.
Some of the ways mentioned above may not be feasible at all for your plant. Each of them may result in only a few percentage points of boiler efficiency improvement. However, if carried out carefully and with the proper tools and instruments, they do add up to huge savings.
Many years of working experience in Marine, Facilities, Construction has given the author material for writing e-books and articles related to engineering, and management. Subscribe to facworld ezine
More information at Marine Engineer and M & E Engineer
Keying off a very interesting concept confined within Static Quantum... Read More
We need very much to study meteorites more, but we... Read More
Aerodynamics of a flying sphere. It has been said that... Read More
If we are to tackle the challenges of future populations... Read More
Complex control systems all make use of signals that can... Read More
The aerodynamics of the human body are very interesting indeed.... Read More
Balancing our quest for Space and its costs with the... Read More
Unmanned Aerial Vehicles should be shot down from the air... Read More
Human innate bonding to ELF ? Extremely Low Frequencies of... Read More
The changes in the earth magnetic field away from the... Read More
In any important task you need to stay alert and... Read More
The reason for the apparently absurd question in the title... Read More
Visual limits of the human brain and the visual processing... Read More
Tree hugging is a thing of the past. It is... Read More
If we bring the locusts to a feasting area of... Read More
Egyptian scholars know there is little other than fiction that... Read More
Is Mars Hollow? We are pretty sure it is not,... Read More
More and more future fighting vehicles introduced at the Military... Read More
Perhaps we should design tunneling robots, which can dig out... Read More
One future problem, which has not sufficiently been addressed, is... Read More
Cleaning Plexiglas windows is not easy, you have to be... Read More
Can a hybrid Surface to Air Missile, UAV loiter for... Read More
Research Method:Quantitative determination by contrasting HBV-DNA of cases before and... Read More
We need to design tiny robotic bees, which can mimic... Read More
Binoculars and telescopes and other astronomy equipment and accessories are... Read More
Egyptian scholars know there is little other than fiction that... Read More
I propose a lighter than air tubular unmanned mini blimp... Read More
As scientists and theorists study patterns, design, chaos, complexity they... Read More
It is possible to disrupt the sound waves coming from... Read More
It maybe possible to apply a rogue wave theory and... Read More
Remote Control Bacteria. Why not, we have remote control everything.... Read More
Thought of the day. I talked to an old guy... Read More
I propose a beach ball hopping robotic planetary explorer, which... Read More
Tesla was always looking for a way to harvest electromagnetic... Read More
In our present period we are continually reminded that we... Read More
It is difficult to have a discussion with someone about... Read More
The crop circle enigma is not always a hoax. I... Read More
Animation of personified reality is intriguing, memorable and interesting as... Read More
Love, pure Love, is the feeling one has when they... Read More
Science is inherently a series of experiments within closed systems.... Read More
A Thorn in the Side for American Business and Consumers... Read More
In the United States, Congress approved, last month, increases in... Read More
We see in the organized world of the Japanese with... Read More
Nature has millions of intervowen interrelationships among the numerous flora... Read More
Destruction! Blow Up! Eliminate! These are not pleasant words!Unfortunately, when... Read More
The much publicized stem cell research debate focusing on moral... Read More
The reason for the apparently absurd question in the title... Read More
Let's describe this idea as a Self Generating a Tsunami-Perpetual... Read More
Presently mini-blimps are being deployed in government leadership buildings as... Read More
Many believe it is possible to build an anti-gravity machines... Read More
Science Articles Science Articles |