The importance of maintaining efficient pressure control in your furnaces

Pressure control in industrial furnaces is a vital factor to avoid the presence of:

• Negative pressure: this results in air infiltrations that can cool the furnace and affect the air/gas ratio and product quality.

• Positive pressure: this can cause damage to the seals and heat loss, which is reflected in higher gas consumption.

Learn about the benefits of having an automated control system for your equipment and our tips to avoid these problems.

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Benefits of having automatic furnace control

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We advise you to install an automated control system in order to obtain the advantages mentioned below.

When we have well regulated pressure inside the furnace it:

• Minimizes the venting of gases via the flue

• Maintains the seal

• Reduces maintenance

• Provides more ease of use

• Eliminates the ingress of cold air

• Delivers higher product quality

• Reduces fuel costs

• Maintains the atmosphere inside the furnace

Dampers to control pressure

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The use of dampers with alumina louvers is one of the best options for controlling furnace pressure since they withstand high temperatures. They are extremely light, so they do not require a high torque actuator motor for the drive.

Ideally, the system should be automatic with the help of pressure control and a damper.

You have to be very careful with them because if they break you will lose control of furnace pressure, which can:

• Cause air leaks

• Cool the furnace

• Affect the air/fuel ratio

They are not recommended for applications in cast aluminum; for these we recommend using:

1.-Ceramic fiber modules: use of a macro-module with counterbalance.

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2.-Air curtains: these prevent hot air from escaping and keep the system pressurized

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Pressure control methods

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1.-Actuators

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Hydraulic, pneumatic or electric drives are used to operate a damper. Hydraulic and pneumatic drives can be used to return to a fully open position in the event of a power outage. Most electrical drives will remain in position if there is a power failure, although there are some actuators capable of returning to position in these circumstances.

Heavy dampers generally require hydraulic drives, often with power amplifiers to withstand large inertial forces. They can sometimes be counterbalanced to reduce the required torque.

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2.-Dampers

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Counterbalanced moving blade dampers allow for the use of a small-scale drive unit. They are frequently used in small furnaces in a row of flues with a universal drive and intermediate shaft.

It can be difficult to keep multiple flue ducts in balance, so a single duct is preferable for automatic dampers.

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3.-Other methods

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A venturi flue controls the furnace pressure by modulating the flow with a jet of cold air, thus avoiding moving parts in the hot gas stream. This method is frequently used to control furnace pressures.

The air damper arrangement has all its moving parts in a cool environment. Its air valve only needs a small control motor.

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We help you automate your furnace for better pressure control

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At Nutec Bickley we can assist you with:

1.-Furnace pressure measurement service

2.-General technical service

3.-We provide Fives North American pressure controls

• Set point controller with integral manual/automatic station

• Relay contact outputs to provide a variety of output control interfaces

• Each relay has a power rating of 125 VA, 120/240 V AC

• They prevent damage to the furnace caused by gases escaping through sight glasses, seals and doors

• Saves fuel by eliminating cold air infiltration

• Direct indication of furnace pressure

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At Nutec Bickley we are specialists in industrial furnaces and their various components. Contact our expert advisors to learn more about all the solutions we have available for you.