What is the purpose of leaving a row of tubes out of a H.R.T. boiler?

Leaving a row of tubes out of a H.R.T. (High-Rise Tube) boiler primarily serves to improve circulation and reduce carryover. In boiler operations, especially in H.R.T. designs, maintaining optimal water circulation is vital for efficient heat transfer and overall performance. By leaving a row of tubes out, the flow of water can be directed more effectively, helping to minimize the chances of water carryover, which can occur when steam bubbles lift water droplets into the steam output. Carryover can lead to contaminated steam and reduce the efficiency of the system, so this design strategy is essential for maintaining operational integrity and efficiency of the boiler.

This deliberate design choice focuses on enhancing performance rather than on aesthetic value, simplification of the boiler structure, or direct access for maintenance, although leaving a row of tubes out may incidentally assist in maintenance. However, those aspects are not the primary reason for this particular design feature in a H.R.T. boiler.