How to Ensure Effective Furnace Lining Efficiency

The central processing unit in many refineries and petrochemical plant furnaces consumes more energy than any other piece of equipment, making it essential that all the correct measures are put in place to realise as much energy efficiency as possible. An efficient furnace is key to reducing overall maintenance costs and ensuring that these facilities run smoothly without undue revenue loss caused by downtime.

The right refractory materials deliver a protective and insulating layer of heat resistance attached to the inside of the shell, hearth, and tap holes of a furnace. Not only does this protect furnace parts from extreme heat caused by smelting, but it also prevents excessive heat loss and can lead to greater overall energy efficiency. However, identifying the need for new furnace lining and installing the right material, is not an easy task. In order to get this right, we have outlined five top tips for maximum furnace lining efficiency:

Use infrared (IR) thermography inspection to evaluate existing lining

Ensuring lining quality is critical to protecting the steel from heat and minimising instances of heat loss. Furnaces which have developed cracks over time are prone to leakage. Some may also have design issues that are not visible from the outside, which can cause heat loss issues over time. This is not uncommon with furnaces that have a painted surface.

In order to identify hot spots where the unit is leaking or reducing performance, infrared thermography scans are essential. This typically involves pointing an infrared camera at several points on the furnace casing to analyse the external temperature and identify any areas where heat loss is occurring. Although these can be conducted from within the furnace, such scans are more effective when performed from the outside, because this enables engineers to keep the furnace in operation. It is advised that specially trained application engineers carry out any infrared imaging, analyse the scans, and provide recommendations on the most appropriate repair options.

Make repairs on-line whenever possible

In the instance that an infrared thermography inspection reveals a need for repair, Morgan always advises that this be done on-line wherever possible. This is the most effective method of maintenance and is reliable, fast and economical, since the unit is still in operation. After all, boilers and process units are constantly generating revenue so any downtime experienced will likely impact a business quite significantly. Of course, this option does depend on the temperature of the furnace, the difficulty of accessing a particular area, and how large the hotspot is.

Morgan’s Superwool^® and Kaowool^® insulating pumpable solutions can be installed by pumping from the outside of a furnace or boiler, filling cracks and voids caused by deteriorated insulation. Effective and simple to apply, these products are ideal for providing thermal insulation efficiencies behind boiler tubes in sidewalls, seals and floors. They can also be used to repair ovens, furnaces, and other process equipment.

For traditional repairs, the furnace must be shut down and cooled until it is safe for maintenance personnel to enter and repair the lining with fibre blankets, pumping solutions, or monolithics.

Consider engineering design carefully

In order to realise maximum operating efficiency for the materials specified for furnace relining, it is important to ensure that the engineering design is suitable. Not only must the materials have enough studs to hold them in place, they also require sufficient joints for expansion or shrinkage. If you install a brick lining without adequate expansion joints, the brick can grow so large that it pushes up the entire lining off the furnace wall. This will lead to further inefficiency, requiring the entire process to be repeated.

Select the right material for furnace re-builds

Some repairs identified by infrared thermology scanning can be too large to address on-line and instead, the unit must be shut down for a furnace reline, or process heater reline. In this scenario, it is important to select the right refractory materials to facilitate a successful furnace rebuild. This will lead to greater efficiency, reliability and lower maintenance costs.

The best place to start when selecting this material is by using a heat flow analysis software programme, in which temperature and use factors are inputted to obtain information on the best materials to be used. Properties including hardness, density, mechanical resistance and insulating factor will vary depending upon the furnace application.

If your furnace is an older model, it will likely have a different type of insulation to that which is commonly specified today, presenting an ideal opportunity to upgrade when relining the furnace. Products such as Morgan’s Superwool^® Plus™ insulating fibre offer up to 20 per cent lower thermal conductivity when compared with other products, making it 17% more energy efficient than traditional Refractory Ceramic Fibres (RCF), and Alkaline Earth Silicate (AES) insulations. This is made possible due to maximised fibre material contained within the solution. Its low bio-persistence also makes it a reliable and effective replacement for RCF insulation.

Ensure a successful installation

The final point to consider when lining a furnace is to ensure that the installation is completed correctly by somebody who has the required level of skills for the task. The number of products available for furnace lining are vast, and all come with their own unique installation requirements. Getting this wrong will cause inefficient lining, as well as wasting large sums of money.

An example of these specific installation requirements can be seen with concrete. If concrete is not mixed with the right volume of water at the correct temperature, the material will not develop properly, it will be difficult to place, and is unlikely to reach expected properties. An ineffective, or inaccurate installation is as bad as not having a good design and not making the right material choice. Get all these points done correctly and you can benefit from an effective and efficient furnace lining for many years to come.

For further information, please visit: http://www.morganthermalceramics.com/furnace-lining