Example of Fibre, Bricks and Castable Refractories
The internal walls of furnaces and process heaters are insulated with refractory lining, helping to conserve heat loss and maintain the internal temperature inside the heater. In addition, the external casing of the heater needs to be cool enough for operating staff to access safely.
API 560 Refractory Design Requirements
API 560 Standard has specific requirements to be achieved for the external casing. These requirements are as follows:
- 90 deg C (195 deg F) at the floor
- 82 deg C (180 deg F) on the walls
- 0 m/s (0 mph) wind speed
- 27 deg C (80 deg F) ambient air temperature
Our simulation technology includes for API 560 design requirements as default, however, you have the freedom to adjust the design requirements as you wish.
In modern process heaters, the most common type of refractory materials are as follows:
- Castable Refractory
- Ceramic Fibre Insulation
Therefore, careful monitoring of these analysers can indicate whether there is an issue with combustion. Ideally, this monitoring should be done alongside ‘good old fashioned’ routine observation of the flame where possible, to ensure the shape, colour and vigour of the flame remains suitable.
Castable refractory has traditionally been used in process heaters for over 40 years. The process of installing this refractory involves mixing powder with water, applying this ‘wet-mix’ on to the required surfaces and then an extensive drying out procedure.
Traditionally, this refractory can be applied throughout all areas of the heater. However, in recent years, ceramic fibre has been used on the radiant section walls and castable applied elsewhere.
Fibre lining has been used increasingly with over the last 20 years. Fibre has a much simpler installation process and is significantly lighter than castable refractory, which has significant cost efficiencies for fabrication, assembly and shipment.
Although most commonly used in Radiant sections only, installation of fibre throughout all sections of the heater has become a more frequent occurrence. In some instances, a stainless steel mesh or thin plate is used to further secure the fibre position (particularly where high flue gas velocities are expected).
