boiler burner(steam jet)

7/27/2019 Boiler Burner(Steam Jet)

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STEAM ATOMISING BURNER, TYPE KBSD SD5580#01.4

Steam atomising burner, type KBSD

1 General

The burner is a steam atomising burner for modulating operation. The burner is

capable of burning both diesel oil and heavy fuel oil. An illustration of the KBSD

burner is shown in Figure 1.

The burner system consists of the burner unit, combustion air fan, and supply

systems for oil, steam, and combustion air. The burner unit is mounted on top of the

boiler and connected to the combustion air fan via an air duct.

The design of the KBSD burner ensures that the flame is kept highly stable at all

loads. Due to the advanced wind-box and oil flow control system, the KBSD burner

can provide inert gas at low loads and has an increased turn down ratio.

Illustration of the KBSD burner

Figure 1 burner2d.cdr

Language UK Page 1/4

W i n d b o x

B u r n e r l a n c e

A t o m i s e r

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S e c o n d a r y s w i r l e r

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A t o m i s i n g s t e a m i n l e t- c o m m o n s t e a m l i n e

A t o m i s i n g a i r i n l e t

F u e l o i l r e t u r n

F u e l o i l i n l e t

A i ri n l e t

S m a l l s iz e K B S D b u r n e r sa r e e q u i p p e d w i t h t w o s w i r l e r s

L a r g e s i z e K B S D b u r n e r s a r ee q u i p p e d w i t h o n e f la m e s t a b i l i s e r


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1.1 Burner design

1.1.1 Wind-box design

When the combustion process in an oil burner is controlled, it is essential to have a

stable and uniform distribution of the combustion air in the burner register and the

air duct. A badly shaped air duct can cause instability of the flame, and therefore the

burner has been designed with a dynamical wind-box, as shown in Figure 2. This

wind-box, shaped as a spiral, in combination with the radially fixed guide vanes

ensure a uniform air distribution in the burner register. This is an efficient way to

achieve a stable combustion.

Illustration of the dynamical wind-box

Figure 2 windbox3.cdr

1.1.2 Burner register

The burner register is the duct between the wind-box and the furnace. The burner

lance with atomiser, swirlers/flame stabiliser, and ignition burner are placed in the

burner register. Small size burners are fitted with divided swirlers one primary air

swirler and one secondary air swirler, whereas large size burners are fitted with only

one flame stabiliser.

For maintenance and inspection purposes the burner lance can be dismounted

separately from the top of the wind-box. This makes replacement of the atomiser

very easy.

The swirlers/flame stabiliser are designed to create an internal re-circulation of hot

gases, which provides the continuous ignition, and hereby to stabilise the flame

resulting in less pulsation.

1.1.3 Ignition burner

The ignition burner is a separate diesel oil burner with its own oil supply system.

When the burner is started, and the ignition sequence step is reached, the ignition

burner is moved into position by means of the air servo cylinder.

The diesel oil flame is ignited by an electric spark between two electrodes which areconnected to a high voltage ignition transformer.

After the ignition period has expired, the ignition burner is purged with air and

retracted again.


A i r i n l e t

G u i d e v a n e s

B u r n e r la n c e

S w i r le r s o r f l a m e s t a b i li s e r


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1.1.4 Atomiser

The burner lance contains the Y-jet atomiser, in which steam and fuel are mixed and

ejected. This oil mist is then mixed with combustion air, and the combustion is

completed. The requested oil capacity of the burner unit determines the number and

bore of discharge ports in the atomiser.

The oil flow regulation is based on flow measurements, and therefore the oil

pressure is of little importance to the atomisation quality. As a consequence of this,

the atomisation quality does not vary over the burner turn down range even with the

oil pressure operating between 2 and 25 bar.

1.1.5 Flame failure equipment

Flame failure during light up and normal operation is detected by photo electric cells

mounted on the burner unit and coupled to an amplifier mounted inside the localcontrol panel. By loss of flame, this flame failure equipment will automatically shut

down the burner.

1.2 Supply systems

1.2.1 Oil and atomising systems

The atomising medium and oil are supplied from valves through flexible hoses to

the burner lance.

The automatic shut-off valves, re-circulation valve, solenoid valves, and the rest of

the necessary burner mountings are all fixed on the wind-box. All shut-off valves are

standard ball valves, and the automatic valves are with electric/pneumatic actuators.The arrangement of the components on the burner is made as simple as possible and

is therefore very user friendly regarding operation and maintenance.

The oil flow control valve is fitted together with a pneumatic converter/positioner.

To obtain a very accurate regulation of the oil flow, which is very important to have

a large turn-down ratio, the valve is also fitted with an adjustable Cv-adjuster. This

Cv-adjuster makes it possible to adjust the pressure loss coefficient of the valve

whereby the oil flow regulation can be optimised to each single installation. The oil

flow is measured by a screw-type flow meter.

The fuel oil pressure control loop includes a motorised control valve to ensure the

correct pressure at the fuel oil inlet of the burner, and thereby providing a larger

turn-down ratio of the control valve. A single loop PID-controller and a standard 4-

20 mA pressure transmitter ensure optimum and accurate functionality.

The fuel oil temperature before the burner inlet is kept precisely at the desired value

by means of a motorised flow control valve, a single loop PID-controller, and a

Pt100 temperature transmitter.

The atomising steam is supplied through a motorised control valve. The steam

pressure is kept constant at high burner load, but at low burner loads, the steam

pressure is reduced. A single loop PID-controller with external set point and a

standard 4-20 mA pressure transmitter ensure optimum and accurate functionality.

The external set point is related to the fuel oil flow and changes together with this,

making regulation more optimal.

Both steam and compressed air can be used for atomisation of the fuel oil. Normally

steam is used for the atomisation, which is supplied from the steam line. Whenconnecting to the common steam line in plants with two boilers, boiler No. 2 can be

started by using steam from boiler No. 1 and visa versa.



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Atomisation of the fuel oil by compressed air should only be used during start-up or

due to failure of the steam supply.

1.2.2 Combustion air system

The combustion air system supplies air to the burner according to the demands of

the control system. The draft loss of the burner air register is measured by a

differential pressure transmitter, which converts the signal to a flow signal used by

the control system for automatic air/oil ratio control.

The combustion air is supplied by a directly driven centrifugal fan. The fan is

mounted on a common bed frame with motor, inlet vanes, and servo-drive unit. The

fan impeller inside the spiral housing is mounted directly on the motor shaft. The air

flow to the burner is regulated by inlet vanes mounted on the fan suction side.

The inlet vanes are of a multi-blade design and regulated by a servo-driven unit

comprising an air cylinder and an I/P positioner. A silencer can be mounted on the

fan suction side.


boiler burner(steam jet)

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