Secondary Air Damper Control in Boiler

Keywords: furnace to windbox differential pressure, windbox to furnace

In this proposed work, design and development of managing Supplementary air dampers in a draft system of a vitality plant which is presently focusing on DCS approach has been achieved by using high processing software ARDUINO and results has been proven with suitable simulation in VISUAL BASICS. The purpose of this work is to control the environment dampers in different ways in line with the unit load in that way increasing the boiler efficiency also to reduce the pollution. A set of six interlock conditions were provided for this function. Since DCS does apply only for big system not less than 5000 input and output but this is costly. It includes separate server, processor and computers where as ARDUINO will not require a individual processor chip, no workstation, no operator stop here directly hook up interfacing card with computer itself.

Keywords- Secondary air dampers, Draft system, ARDUINO, Power vegetable (TTPS), Software control.


In power herb boilers, the draft is obtained by means of fans namely Required draft and Induced draft fan. The FD and ID admirers develop enough draft to move the tremendous level of air and gases through the flue gas ducts and stack to atmosphere preserving a balanced draft in the furnace. The supplementary air for combustion mainly enters in to the windbox. The wind flow box assembly is a high structure divided in its level into thirteen compartments which houses 6 no. of Coal nozzles and 5 auxiliary air nozzles otherwise at different elevations from top to bottom. Louvre dampers called as extra air dampers each of which is run by an individual damper drive cylinder located at the side of the wind container. The coal nozzle elevations are designated being a, B, C, D, E, F elevation from bottom level to top, the bottom end air and high class air elevations as AA and FF respectively. The auxiliary air nozzles among coal elevations are chosen as elevations AB, BC, CD, DE, EF. The furnace corners are chosen as nook 1, 2, 3 and 4 in clockwise course. Heat released in the furnace is received by the

Water/heavy steam/air to the utmost extent to acquire boiler efficiency of the order of 86%.


The operation of the auxiliary and fuel air dampers in the windbox assemblies are damaged by the FSSS.

A. Auxiliary air dampers:

During the furnace purge period and first functions up to 30% boiler loading all elevations of auxiliary and end air dampers modulate to keep a predetermined (approx. 40 mmWC) established point differential pressure between windbox to furnace. 30 to 40% of total air flow with an air abundant furnace will be provided through the above period to avoid bad furnace conditions.

When the unit load surpasses 30% MCR, the differential pressure establish point is improved and ramps to a higher setting up (approx. 100 mmWC). Together, the auxillary air dampers associated with coal or engine oil elevations not in service close in timed series starting with the upper elevation of dampers and progressing to the cheapest elevation.

When the machine loading is reduced below 30% loading, the auxillary air dampers available in a timed collection starting with the cheapest elevation of dampers. Simultaneously, the differential collection point changes to its lowest setting.

All the auxillary air dampers keep up with the status quotient after a boiler trip and can open fully when both FD fans are off. The bottom end air damper is normally kept available to a set predetermined position to reduce unburnt coal dust fall out.

B. Fuel (engine oil) air dampers:

Elevation AB, Disc and EF dampers modulate according to the olive oil header pressure when heavy oil is being fired. Otherwise they open up and close with the rest of the aux air dampers. Elevation Stomach dampers are kept at a set beginning when light essential oil is being fired.

C. Energy (coal) air dampers:

Their businesses are impartial of Boiler weight. All coal

air dampers are normally closed. They available fifty seconds after the associated feeder is started, and modulate as a function of feeder speed. Fifty seconds following the coal feeders are taken off service, the associated fuel air dampers close. The petrol (coal) air dampers open completely, when both FD supporters are off or when the boiler journeys on master gasoline trip.

Importance of extra air:

  • Protect Boiler Equipments
  • Control the Pollution
  • Improve the Efficiency of the Boiler


This project is to automatically control the environment inlets that are termed as dampers that happen to be controlled using pneumatic valves. The pneumatic valves are handled by sensors with respect to the windbox to furnace differential pressure. Thus this task controls dampers based on arduino coding

And its aesthetically displayed in visual basics. This forms the basic technique for this project.

A. Hardware Explanation:

The hardware components consist of 4potentiometers of range 10k. They are assumed to be the coal mills/diesel type i. e. inputs for coal. Extra air dampers can be found near all coal and diesel elevations.

The percentage beginning of any damper depends upon the quantity of coal/diesel input. Therefore variant of potentiometers suggest amount of coal/diesel type. The damper beginning will depend on the varying point of the potentiometers.

4 potentiometers are so connected for explanation and they are connected to the A/D convertor pins of AT MEGA 8. 0 controller.

Then the freeduino mother board in which the AT MEGA 8. 0 is set is connected to PC and arduino coding is uploaded in the controller. Then VB shows visual representation of percentage of damper opening and all the factors.

B. Software Information:

The software coding was developed based on several conditions on which the secondary air damper opportunities depend. These form the bottom for creating a program. These conditions are based on some fixed worth and formulas. As already mentioned the percentages of secondary air damper starting depend on the quantity of fuel input to the furnace. The algorithm for visual principles coding are as below.

1) Operation Of Coal Elevation Dampers: (A, B, C, D, E, F)

The coal dampers at elevations A, B, C, D, E and F will be fed with coal with respect to the load of the energy plant. Feeding (30 tonnes each hour) any three of these coal elevations is enough enough to provide the predetermined full fill (210 MW) of the unit. All dampers always have a minimum opening of 30%. In general, significantly less than 20% of the extra air to the fireball will maintain substoichiometric combustion which restricts the flame temp of the fireball and the curtain of secondary air over the walls. The drape of secondary air militates against the forming of slag on the furnace walls. All of this proportioning of air requires tools of modification open to the furnace operator.

The dampers modulate matching to coal type in three different ways as:

When coal is given into a particular(own) elevation, the related air damper starts modulating predicated on the fuel suggestions to let the secondary air necessary for the combustion of given source.

Rather when coal is given into an (auxillary) elevation adjacent to a particular damper, the damper modulates to maintain the windbox to furnace differential pressure, therefore controlling the continuous negative pressure necessary to create swirling fireballs of combustion in tangentially fired boilers.

When the condition of tripping the complete unit develops, all the six coal elevation dampers are opened up to100 % (maximum).

When there is no fuel input in virtually any of the above mentioned elevations then your dampers will maintain minimum starting position. (0%)

2) Operation of engine oil elevation dampers

(Abdominal, BC, Compact disc, DE, EF):

Oil is employed as fuel type during startup and during scarcity of coal. Each couple of coal nozzle elevations is served by one elevation of essential oil burners (4 nos. /elevation) situated in the auxiliary air nozzle. Thus 12 oil weapons, non retractable type, are accommodated in the three elevations Abs, Disc and EF. Heavy petrol engine oil can be fired at the engine oil guns of all these three elevations, whereas light gasoline oil (Broadband diesel olive oil) can even be fired at Belly elevation. Each petrol gun is associated with a retractable high energy arc (HEA) igniter, organized beside the oil weapon in the auxiliary air compartment and they directly light up the oil weapons.

The dampers modulate according to oil suggestions in three various ways as:

When engine oil is given into a specific(own) elevation, the equivalent air damper begins modulating based on the fuel type to allow secondary air required for the combustion of given suggestions.

When steam input is greater than 30% with adjacent elevation exposed then windbox to furnace differential pressure is retained.

Rather when petrol is given into an (auxillary) elevation adjacent to a specific damper, the damper modulates to keep up the windbox to furnace differential pressure, therefore controlling the frequent negative pressure essential to create swirling fireballs of combustion in tangentially fired boilers.

When the health of tripping the whole unit occurs, all the petrol elevation dampers are opened up to 100 % (maximum).

When there is no fuel input in virtually any of the above elevations then the dampers will maintain minimum beginning position. (0%)

3) Procedure of AA, FF elevation dampers:

The AA elevation of air damper is definitely fully (100%) opened and the FF elevation is often closed to improve combustion.

Thus the coding for the task is developed based on the conditions of the coal and oil inputs.


The starting of dampers will depend on the strain and coal insight. The above stand I illustrate the ratio of coal insight in each mill for given ratio of weight. Here 30 Tonnes/Hr of coal is the 100% source and 10 Kg/cm2 of essential oil is the 100% insight of oil.

When unit insert is 50%, then coal mills A, B are completely procedure and C mill operates 10% with AB elevation having engine oil.

For lots of 60%, coal mills A, B, C will operate till 30% and mill D has 10% suggestions. AB essential oil elevation is given with full ratio of engine oil.

If the strain is 70%, then you don't have for petrol but coal mills A, B, C, and D are fed with maximum insight.

For 90%, you don't have for oil but the coal mills

A, B, C, D is fed with maximum source and E with 20% of gasoline input.

For 100% insert, all the coal elevations are fed with maximum insight.


Visual Basic is a third-generation event-driven programming language and integrated development environment (IDE) from Microsoft for its COM coding model first released in 1991. Visual Basic was derived from BASIC and permits the rapid request development (RAD) of visual user interface (GUI) applications, usage of databases using Data Access Objects, Far off Data Things, or ActiveX Data Objects, and creation of ActiveX handles and things. VBA is effectively the same words as Visible Basic but VBA-code is linked with Microsoft Office and can only just run within that environment. A programmer can put together a credit card applicatoin using the components provided with Aesthetic Basic itself.

The four petrol inputs are received via the potentiometer to the AT MEGA 8 microcontroller. The variation of potentiometers point out amount of coal/diesel type. The damper starting depends on the adjustable point of the potentiometers.

The controller board is linked to Computer and arduino coding is uploaded in the controller. Then VB is used for graphical representation of damper beginning.

The simulation results displaying air dampers status variation according to the various input establish points is as follows:

The amount of coal type given is shown in the aforementioned fig 5. This show the percentage of source given, timer, coal mill that is effective, amount of fill, steam input placed point and heavy steam input in percentage.

This form shows all the elevation of dampers and denotes the damper that is available and the percentage of damper beginning is also shown. In addition to that reactive vitality produced for matching fill is also computed.


Based on the graphical programming language and the info stream operating setting, the software rather than apparatus, the utilization of virtual instrument technology has exposed our new field of control. Compared to the traditional control they have obvious advantages. Coding is easy by the graphical programming language. A kind of visual basics personalizes button design and structure, with the electronic knobs and switches to struck the friendly individual, intuitive control program makes vivid, so that the operators are involved in the operation much easier to control the procedure and results instantly. The main advantage of controlling extra air dampers by using arduino is reduced cost as compared to DCS technique, because the interfacing of inputs and outputs are straight given to the Computer (which works as work station i. e. block panel and operator station i. e. leading -panel). This newspaper was manufactured in a Coal Established Thermal power vegetable at tuticorin, TTPS as the prevailing is operating on DCS system.


DCS - Distributed Control System

FSSS - Furnace Guard Supervision System

FD enthusiast - Required Draft Fan

ID supporter - Induced Draft Fan

ADC - Analog to Digital converter

PC - Personal Computer

VB - Aesthetic Basic 6. 0

Draft - difference of pressure causing stream of air

Elevation -position of dampers

Windbox -secondary air storage area between FD supporter and furnace.

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