Benchmark with Edge [I]: Operation-Maintenance Manual
SECTION 7
– BOILER SEQUENCING TECHNOLOGY
OMM-0145_A99
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SECTION 7.
BOILER SEQUENCING TECHNOLOGY
7.1 INTRODUCTION
The Boiler Sequencing Technology system (BST) is an integrated 16 boiler control system. It is
built into the Edge [i] Controller. It has its own sophisticated PID control system designed to
simultaneously control the light off and modulation of
up to 16 boilers
while achieving
maximum operational efficiency.
BST is designed to ensure that all Boilers in the system operate at maximum efficiency. This is
accomplished by lighting off boilers only when all ignited boilers reach or exceed a defined
Valve Posi
tion (Fire Rate). Operating all boilers below the defined Fire Rate “Next on VP” (for
Next Turn on Valve Position) insures that they are firing at their most efficient Fire Rate. One
unit the BST network is defined as the “Manager” and all other units on the network are defined
as “Client” units. The Manager monitors the system Header Temperature, and also monitors all
Client unit’s status information, efficiently controlling all units in order to achieve and maintain
the required BST Setpoint Temperature.
When there is a demand, the BST Manager will light off the lead boiler based on the BST
Sequencing selection in the
BST
Cascade Status
screen. As system load increases and the
valve position of the ignited unit(s) reach the Next On VP (% valve position), the Manager will
light off the next available unit. A simplified block diagram of multiple Boilers connected to a
BST is shown in Figure 7-1 below.
Figure 7-1: Simplified BST Block Diagram
NOTE:
After the boiler load is satisfied, the isolation valve remains open for a programmed interval
(default = 2 minutes) before closing. When the
system load
is satisfied, the Edge [i] Controller
will open the
isolation valves for all of the boilers.
The BST controls the valves via a 0-20 mA
signal (see Section 2.11.1:
I/O Board Connections
in the
Benchmark 750-6000 with Edge [i]:
Install-Startup Manual
(OMM-0144, GF-217).
NOTE
: Use either FFWD Header Temp
Sensor or Modbus Header Temp Sensor
