Improving Efficiency of Pressurized Boiler by Preheating Air

ENG8001
Engineering Research
Methods
Assignment 1
2019-Semester-2
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TITLE
Improving the efficiency of pressurized boiler by
preheating the air.
Abstract
This is a research proposal which presents techniques of improving the
efficiency of the pressurized boiler by use of preheated air. A boiler by can
be defined as a device employed to generate steam by applying heat
energy to water. Boilers are applied in many industries such as thermal
production plant and industries which use steam energy during production
work. In large scale steam production, there are two common types of
boilers which are used. These include the water tube boiler and fire tube
boiler. The present research highlights use of Fire tube boiler. In most
cases, these boilers operate 24hrs in a day during operation in large scale
industries. It is important to consider the mechanisms or fuel used in
energy production in these industries, however, in most plant, we find that
they use furnace oil. For this case, the amount of oil required in these
industries is a lot and hence any company using this form of energy needs
a good investment in it. Therefore, there is a need to come up with
methods on how to increase the efficiency of the pressurized boiler to
reduce energy used in production. Installation of air preheater is one of
the best solutions that can be used to efficiency of the pressurized boiler.
Introduction
Boiler is defined as an enclosed vessel which offers a way of combusting
and finally transferring heat energy to water and hence making it hot or
rather producing steam. The hot water produced, or steam produced in
this process, is afterward employed in transferring heat to a given
process. It is worth noting that many manufacturing processes would
require steam for heating purposes. Steam is also employed in generation
of electric power. To produce steam, water need to be heated in a closed
container or rather vessel. The closed container is known as a boiler
(BASHEER.P. V5, et al., 2018). Combustion takes place in a furnace. Flue
gas produced, flows via tubes or even outside tubes. There are two types
of boilers classified based on the type of tube used; a smoke tube boiler
and a water tube boiler.
Fire tube boiler can be defined as a kind of boiler which allows the
passage of hot gases that emanates from fire passing via one or more
tubes which run through a container of water that is sealed. Steam is

created by thermal energy conducted through the walls of this tube and
hence heating water inside (BASHEER.P. V5, et al., 2018).
Water tube boiler on the other hand can be defined as a kind of boiler that
water moves inside the tubes which are heated outside by fire. Fuel in the
furnace, is highly heated and hence resulting in the creation of hot gases
which end up heating water inside the tube hence generating steam.
The efficiency of these two boilers can be improved by preheating the air.
By doing so, there will be a resultant reduction in amount of fuel used to
produce thermal energy. This serves the purpose of economizing on the
boiler usage as exhausted gases can be used in pre-heating air that is
blown through the furnace hence warming up feed water (BASHEER.P. V5,
et al., 2018).
Background
To carry out this research, there are previous studies that have been
conducted which will give a proper guideline to be followed in the design
purpose. A journal done by Shaihul Mahin, Shanis Basheer.P.V, A. Bala
Kumaran and Mohammed Assaf.C in April 2018 which discusses on how to
design air preheater that ultimately result in efficiency in energy output in
boilers. This journal gives a guideline of design principles. From this
research, we find out the resulting design gave a positive outcome. By
using preheated air, the overall efficiency of the boiler went up to 75.2%,
this gave a reduction of oil consumption by 59.69kg/hr. In addition to this,
research conducted by S.Sudhakar and C.M Raguraman in 2016 on a
journal on how to improve the efficiency of preheaters in boilers gives
methodology of carrying out maintenance of preheaters. The maintenance
techniques discussed in this journal include replacing the heating plates,
replacing the end baskets, replacing the hot side basket and maintenance
of the seals. This leads to power saving by more than 30% each year.
Methodology
Boilers
Boiler system will be installed or rather an existing boiler system in a
selected firm will be used in this exercise. The initial condition of the boiler
will be assessed and its efficiency ascertained before the test.
Preheaters
Each boiler shall have air preheater installed in them. For small to medium
boilers, tubular preheaters will be installed while for regenerative
preheaters will be installed in high range boilers.