As safety monitoring is the primary function of a burner management system, there are many ways that a burner trip can occur. While this is the desired response to an unsafe condition, if a burner management system with a series interlock circuit is being used, it can often be difficult to troubleshoot why the lockout is occurring. This […]
Burner Management Series II: BMS Limits Circuits
Safely sequencing a burner through each state of the burner cycle is the primary function of a burner management system (BMS) or flame safeguard. To do this the BMS utilizes various limits circuits to monitor the status of the burner through each step of the burner sequence. Each of these are “series limits circuits”, meaning that power is […]
Burner Management Series I: Safely Sequencing a Burner
When it comes to burner management systems, safely sequencing a burner through each state of the firing process is the top priority. This can be broken down into 4 basic functions: 1) Pre-ignition checks verifying that the burner and boiler are in a safe condition to start, 2) Continuous monitoring of all safety limits while the burner is […]
Crucial Components: System Reliability at a Maryland University
Recently, our Service Crew was called to address a critical issue at a Maryland University involving an improper drum pressure reading. The investigation led to the discovery of a damaged transducer, which was unprotected due to the absence of a siphon pigtail. This small yet crucial component plays a significant role in maintaining the reliability and safety of […]
System Reliability at a Maryland University
Our Service Crew was recently called to diagnose an issue with an improper drum pressure reading at a Maryland University. What we found highlighted the importance of a small but crucial component in pressure control systems: the siphon pigtail. The Problem Upon inspection, we discovered that the transducer, responsible for providing accurate pressure readings, had been damaged. The […]
Fuel/Air Cross-Limiting
What is the Application? Steam supply and heating loads in a boiler plant vary throughout the course of the boiler firing cycle. In response to this, the boiler firing rate output % is continuously adjusting to maintain steam or temperature setpoint. This means that the boiler controller’s outputs (typically a fuel valve positioner, air damper positioner, and variable […]
Drum Level Control Essentials
What is the Application? As boilers convert water into steam to supply the plant’s load demand, more water must be supplied to the boiler to maintain the drum level at setpoint. In a modulating PID system, Boiler feedwater flow is controlled by the drum level controller by modulating a feedwater control valve which can be opened to give […]
PID Loops in Boiler Control Systems Part 4: Practical Tuning Techniques
Now that the PID components and type structures have been examined, Let’s get into the process of fine-tuning a PID loop. It is important to remember that in a real-world setting there are many variables that must be accounted for such as the plant process load variations, transmitter calibration and range scaling, control valve stroke, fuel supply pressures, […]
PID Loops in Boiler Control Systems Part 3: Boiler Control Applications and Common PID Loops
As stated in Part 1, PID loops are a central component of a modern boiler control system. In this section, we will examine some of the more common applications of PID loops in boiler control systems. We will look at four types of PID loops: Reverse Acting, Direct Acting, Cascading, and Override. Reverse Acting PIDs The most common […]
PID Loops in Boiler Control Systems Part 2: Expanded Definitions of Proportional and Integral Terms
Now that the basic PID terms have been examined, we can now look deeper into the PID calculations and some less common variations that can be used. Defining KP In the basic definition of the Proportional Term in Part 1, the Proportional Term was calculated by finding the Error (either SP-PV or PV-SP) and multiplying it by a […]