Energy saving through efficient Industrial Boiler System

1. Introduction

This report is previous paper continuation of “Saving Techniques: optimization in Boiling water consumption” in which it is willing to debate the role of energy saving in industrial sector such as steam generators. The result of previous paper shows us positive influence of energy saving on boiling water consumption in the public sector while we will not have the same outcome in industrial Boiler system. Why? According to IEO 2010 Reference case, total energy consumption in the world industries will increase an average of 1.3 percent per year from 2007 to 2035. In addition, worldwide industrial energy consumption is equal to 184 quadrillion Btu in 2007 and 262 quadrillion Btu in 2035 whereas total world energy consumption is equal 495 quadrillion Btu in 2007 and 739 quadrillion Btu in 2035. Consequently, industrial energy consumption in the world is approximately 35 to 37 percent of total sum world energy consumption. Besides, only 30 percent of total energy consumption for industrial productions (outputs) is used by the steam energy. Therefore, the influence of energy saving by using of steam on the growth of total energy consumption in the world is negligible.
Why should we increase the efficiency of steam generators?
It is due to competition among industrial companies in the world.
IEO2010 stated, there are five industries that they consume the half of total energy in industrial sector as follows:

-Chemicals 22%
-Iron and steel 15%
-Non-metallic minerals 6%
-Pulp and paper 4%
-Nonferrous metals 3%

Among industries, Pulp and paper manufacturing and Petroleum refining and chemical manufacturing respectively use huge amount of steam as a percentage of total energy consumption as follows:

Industry Total energy consumption by steam
(%)
Pulp and paper manufacturing 84

Petroleum refining 51

Chemical manufacturing 47


As we can see, if pulp and paper manufacturers companies save the energy through efficient industrial Boiler, they can manage the standard cost of their produced goods and finally it will be affected on the lifestyle of their productions. This case is the same for petroleum refining and chemical manufacturers.

How can we increase the efficiency of industrial Boilers?

2.0 Literature Review

As I mentioned beforehand, there are so many common approach about efficiency of Boilers as follows:
Kilicaslan and Ozdermir (2005) stated that Boiler efficiency is ability rate for producing steam from a type of fuel.
Boilers are the equipments which exchange chemical energy to thermal energy(energy in steam) where we have:
Energy in fuel (coal, oil or gas) = Energy in steam + Energy in Heat losses
In fact, for enhancement of Boiler efficiency, we should decrease the losses of Heat in Boilers.It means the conservation of the energy.



What are depressor ways of Heat losses?

It is clear, the biggest energy loss in Boilers are related to exit of the stack gas from the chimney in which the volume and the temperature of the stack gas are determinant factors on heat losses. As Kaya et al (2007) mentioned that incomplete combustion, excess air, water vapor in flue gas, flue gas temperature, fuel type, burners, boiler load, heat loss from boiler surface and the heater surface dirtiness are actual effective factors on Heat losses. And so in a case study conducted by Kaya and Eyidogan (2010), they found that leakage air losses in Rotary Type Air Heater (RTAH) are the most important factor on Boiler efficiency because it is caused an increase on excess air and finally prevents to reach Boiler to full operation.
American Boiler Manufactures Association (ABMA) also refers to the ASME power Test
Code, PTC4 or BTS-2000 to calculate Boiler efficiency that it is included the stack gas, radiation and convection losses. According to ABMA, the principal factors, which are effectively on Boiler efficiency, could be considered as follows:

1) The temperature of Flue gas
2) Heat losses because of the stack
3) The pressure of the steam (High-Medium- low pressure steam)
4) The losses because of Radiation and Convection
5) Excess air
6) The temperature of ambient air
7) Type of fuel

Energy Efficiency Handbook (2007) published by CIBO (Council of Industrial Boiler Owners), introduced several useful strategies for decreasing Heat losses of the stack gas as follows:

1) Reduction of excess air:
When excess air increases, Nitrogen of air rapidly absorb thermal energy and we will have heat loss.




2) The heat transfer surfaces should be clean because these dirty surfaces work just like to an insulation system and absorb the heat so that we will have heat loss.

3) Using of outlet flue gas as combustion air by recovery equipments such as APH (Air Pre-Heater), Economizer in which they work the similar to heat exchangers.

4) Combustible Heat losses:
Because of unburned fuel in ash, heat losses will increase. In fact, the main reason for unburned fuel is not to be enough combustion air. Another reason is the type of fuel.

5) Controlling of air leakage:
It can be done by changing of manufacturing in Rotary Air Pre-Heater (as a new idea) or to replace a new one because of erosion.

6) Radiation Heat:

Thermal exchange between Boiler body and environment is another heat loss that it could be solved by a proper insulation of Boiler.
As we can see, all of above references reflect the influence of the volume and the temperature of Flue gas (stack gas) as a main factor on Heat losses and Boiler efficiency. In fact, if we decrease the temperature of outlet fumes from Boilers, we will have a reduction of excess air accompanied by controlling of air leakage and finally operating of Boiler in full load.
There is the equipment in steam generator systems that it is named Regenerative Air Pre-Heater. It is made by several plates in which flows of inlet and outlet fumes heat the plates and flows of cool air absorb the heat of plates. In the result, the plates of Air Pre-Heater transfer the heat of fumes to cool air. We have two types of this tool:
1) Rotating-Plate Regenerative Air Pre-Heater
2) Stationary-Plate Regenerative Air Pre-Heater



RAPH has a rotor which rotates the plates with slow speed (about 3-5 rpm) while the plates of SAPR are fixed. Each one has the advantages and disadvantages.


In here, I would not like to illustrate the technology of Regenerative Air Pre-Heater more but it is better we zoom the influence of this technology on energy saving in Boilers.

3.0 Research Methodology

All of technical information as secondary data has been obtained by searching in Internet (Google website) and case study has been downloaded from UTM library zone.

4.0 Data Analysis and Discussion

I have brought a case study about the ways of enhancing efficiency through steam generators at high pressure operating here that I will explain the reason of it in conclusion.
Kaya and Eyidogan (2010) conducted a experimental study on boiler which was operating at 420 Bars and 440 ° C temperature whit a natural fuel gas in which the nominal capacity of Boiler was 33.33 kg/s.




They measured the volume, velocity, pressure and temperature of flue gas in outlet and chimney accompanied by mass balances and exergy analysis. According to their measurements, Boiler efficiency was obtained around 88.28% and exergetic efficiency was equal to 36.7%. They found the huge losses of efficiency which was due to air leakage in Rotating-Plate Regenerative Air Pre-Heater so that it increased not only the temperature of flue gas in stock (chimney) but also decrease the capacity of Boiler in full operating by increasing of excess air and incomplete combustion.
According to their data, total energy saving potential was calculated as follows:
Type of energy saving Energy saving potential
(%)

Avoiding excess
leakage air losses 31.14

Reduction
of excess air 17.81

Operating
the boiler
at full load 36.56


Reduction of
flue gas
temperature 14.49



Total 100

Total Energy Saving Potential

Why have we leakage air losses? Because the erosion will occur on the plates in the period of time in connection with the fumes flows. If we decrease leakage air, we will increase the operating of Boiler in full load so. How can we scale down leakage air? By using of new technology, modernization and change in manufacturing of Rotating-Plate Regenerative Air Pre-Heater.
Regarding to total energy saving potential, they calculated the finance of new manufacturing included in investment costs and payback period as follows:



Finance of new manufacturing (RAPH)

-Manufacturing Cost of new model RTA-Heater $600,000
-Annual net profit of Energy saving:
- By avoiding excess leakage air losses $221,625
- By operating the boiler at full load $260,215
-Total profit $481, 840
-Payback period ($600,000/481,840) 1.245 years 15 months
In this case study, the influence of leakage air plus full operating of Boiler has been considered as total sum of energy saving. In my opinion, if we decrease the volume and temperature of flue gas, we will cover every three another items such as saving energy by reducing of leakage air and excess air that finally the result will be the operating of Boiler in the full load condition. In fact, we need new ideas for next generation of Regenerative Air Pre-Heater which could be adopted from the parameters as follows:
- Increase of sum total area of each plate
-Number of plates
-rpm of motor drive
-Material of plates
As we can see, the function of energy saving in Boilers is depended on four variables and we should solve this problem by consideration of maximum energy saving and optimum cost of manufacturing.

5.0 Conclusion

This paper shows us how the business such as marketing in the field of competition can manage a technology as the core to stay in stocks and continue the lifestyle of production. And so, it represents us how an idea can be as a base of R &D and innovation and complete the cycle of process development for the production. Therefore, the new ideas are very important for industry.
Why do I use from this case study?



We will have the big challenge with extraction of crude oil throughout the world in the near future. In the matter of fact, one of the best ways will be the injection of high pressure steam to extract crude oil from wells in which we will have to decrease the cost of high pressure steam by saving of energy. This will be the important strategy for firms in the field of oil & gas.
In the result, apparently the influence energy saving by using of steam on the growth of total energy consumption in the world is negligible but if we measure the performance by a Balance Scorecard method as a research study, we will perceive that the conclusion is vice verse. In fact, there is the high influence of energy saving on total energy consumption in the world by using of steam in industry.

6.0 References

- American Boiler Manufacturers Association. (2008, May). Determining & Testing Boiler Efficiency for Commercial/Institutional Packaged Boilers. Retrieved September 4, 2010, from http://www.abma.com/Commercial_Boiler_Efficiency.Determine.Test.FINAL_POSTED_TO_WEBSITE.pdf/.
- Gietz, M., Schule, V., & Faller, B. (2009). Method for Optimised Operation of an Air PreHeater and Air Preheater. United States Patent Application Publication,US 2009/0095440 A1.
- Kaya, D., & Eyidogan, M. (2010). Energy Conservation Opportunities in an Industrial Boiler System. Journal of Energy Engineering, 136, 18-25.
- U.S. Department of Energy. (2003). How To Calculate The True Cost of Steam.
DOE/GO-102003-1736. Washington, DC: U.S. Industrial Technologies Program.

- US. Department of Energy. (2006). Best Practices: Steam. DOE/GO-102006-2275. Washington, DC: Energy Efficiency and Renewable Energy.

-US. Department of Energy. (2004). Improving Steam System Performance. DOE/GO-102004-1868. Washington, DC: Energy Efficiency and Renewable Energy.

-US. Department of Energy. (2002). Steam System Opportunity Assessment for the Pulp and Paper. DOE/GO-102002-1639. Washington, DC: Energy Efficiency and Renewable Energy.

-U.S. Energy Information Administration. (2010). International Energy Outlook 2010. DOE/EIA-0484(2010). Washington, DC: Office of Integrated Analysis and Forecasting.

- ZEITZ, R. A. (2007). ENERGY EFFICIENCY HANDBOOK. COUNCIL OF INDUSTRIAL BOILER OWNERS (CIBO). Retrieved September 4, 2010, from http://www.cibo.org/pubs/steamhandbook.pdf/.