An unattended boiler is essentially a fully automated boiler that operates under the constant supervision and control of a complex microprocessor-based safety control system. The BCS controls the entire operation of the boiler, including the energy input management system (gas and oil boilers, commonly referred to as the “burner management system” or BMS), management system water level, alarm system, pressure control, and trigger control. Instruments, all instruments and circuits.
A key feature of this type of boiler is that, in most jurisdictions, boiler specifications and standards stipulate that boilers classified as unsupervised must be continuously monitored and controlled by the BCS throughout use. Unattended boilers can only be used in unattended mode. Even with a qualified operator, it is not possible to operate in assist mode under any circumstances, even for short periods of time. In fact, the BCS used in unattended boilers does not provide manual operation. If the control system fails or is potentially dangerous, the BCS will stop the boiler and block the water supply. This will prevent the boiler from restarting until the repair control system fails or resolves potentially unsafe conditions and all BCS inputs indicate that the boiler is in a safe state.
BCS has a number of ways to record all major events that trigger an alert. In the first unattended boiler, it was a simple printer that recorded these events line by line. However, the most modern systems store information in the memory of the onboard microprocessor for a while. Often, they record a wider range of information to better monitor boiler performance, sometimes integrating with plant-wide information systems for remote data storage. A very long time
Unattended boilers are a relatively new phenomenon. Traditionally, most boiler facilities operate under the constant supervision of qualified operators, although in many jurisdictions, some small boilers can operate in limited auxiliary modes. Until recently, unattended operation of boilers was severely restricted in most jurisdictions. In general, the maximum allowable operating pressure and theoretical efficiency are very limited, and in many places these limits still apply, at least on paper. However, in recent years, boiler specifications and standards in many jurisdictions have been extended to accommodate these types of boilers. In other cases, it has become commonplace for local regulators to grant exemptions on a case-by-case basis.
With the advancement of manufacturing standards and the rapid development of advanced microprocessor-based control and monitoring systems, these systems have become more reliable over the past few years, and most small and medium-sized compact boilers produced by manufacturers are now renamed. BCS and high integrity are integrated into standard equipment. When unattended operation is allowed, they may only require an approved inspection agency to perform inspections and operational certifications to ensure compliance with national and local regulations.
Limited assistance compared to unattended operations
In order to obtain a limited or unassisted rating, the boiler must be subject to strict legal supervision, including recorded operations, maintenance, service and maintenance. Boiler specifications and standards require that all categories of boilers (one off boiler service) be equipped with a minimum and specific inventory of safety equipment that will automatically shut down the boiler in potentially hazardous conditions.
The classification that applies to a particular boiler depends to a large extent on the complexity of the BCS and sometimes on the type of fuel burned. For example, a 10 MW natural gas boiler can be unattended, with the same manufacturer using a similar 10 MW boiler, but solid fuel combustion can be classified as a limited aid.