The Current State of Process Fired Heaters: Top 4 Concerns

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Incomplete combustion and the use of excess air can lead to higher levels of toxic emissions. Also, variation in fuel quality, the designed inefficiency or low emission burners, aging heaters and boilers, and the desire to increase production through the unit would seem to push the limits of proper control and safety. What happens if limits are crossed?

Fired heaters account for 37% of the U.S. manufacturing energy end use. Combustion sources such as furnaces and fired heaters therefore play a critical role in the process industry. Unfortunately, combustion requires large amounts of fuel (gas, fuel oil). As a result, combustion efficiency directly influences the performance and operational costs of production facilities.

However, energy efficiency is not the only concern. In this blog I will highlight and explain the four main concerns related to fired heaters: 1. Inefficient Operations 2. Asset Sustainability 3. Operator Skillset 4. Safety & Compliance

 
 

ASSET SUSTAINABILITY

  • Low ranking CAPEX projects for improvements for years have resulted in antiquated diagnostics and controls, leaving the majority of the burden to operator response
  • False low incident rate has been created by lack of reporting near misses, such as contained over pressuring of equipment
  • Traditional PHA/LOPA does not fully provide coverage of the myriad of potential hazards associated with fired equipment
  • Premature tube failures from operating with higher excess Oxygen than design leads to convection section temperatures outside of the design limits

INEFFICIENT OPERATIONS

  • Different parts of facilities are faced with different goals, and operations are not always aligned appropriately
  • Control schemes for firing rates have changed very little over 40 years
  • Air-Fuel ratio-control is only used on a few systems, and fewer still compensate for changing fuel composition
  • Feedback measurements are minimal and often not leveraged or trusted
  • Emissions are higher than design
  • Thermal efficiency is lower than design
  • Traditional ESD (Emergency Shutdown System), commonly referred to as burner management system, is not proactive and is not designed to prevent tripping the asset
  • Typically only one control loop governs normal firing rate, where the process outlet temperature controls the fuel pressure to the burners, with no override or cross-limiting functions to maintain operation in a safe envelope

OPERATOR SKILLSET

  • Operator lacks a clear understanding of fi red heaters design which has operational consequences
  • Engineering principles of heat transfer are not part of the education
  • Fired system design for air fl ow is another aspect where operators are not fully educated
  • Aging workforce: skilled operators are close to retirement

SAFETY & COMPLIANCE

  • To address safety concerns, industry standards are upgrading their recommended practices for instrumentation, control & protective systems for fired heaters & steam generators
  • Plants not meeting the best industry practice guidelines will be at risk in the event of an incident on a fired heater.
  • Many natural draft fired heaters do not meet this guideline with existing instrumentation and control systems.
  • Most natural draft fired heaters have only automated control of the fuel supply and not the air, excess air is often applied to the combustion process, thereby reducing thermal efficiency.

Fired Heater Optimization

Recognize any of these challenges? Download our free eBook about Combustion & Fired Heater Optimization below. This eBook explains how to improve safety & efficiency by controlling combustion using TDLS technology. Simultaneously control air and fuel supply by measuring average gas concentrations across the high temperature radiant section of your fired heater.