1. Intelligent Boiler Sequencing
Lead-Lag Control

2. Agenda Objectives Explanation and Set-up Procedure
Mk7 communication features
Other Information and Illustrations

3. Overview of System Operation: Features and Benefits
The principal objective of Lead-Lag Control is to ensure that the minimum number of boiler/burner units are in operation at any one time. The benefits from using Lead-Lag Control include:
Increased savings in electrical costs
Reduction in thermal stresses on the boiler
Increased overall plant efficiency
There are 2 variations of Lead-Lag software
One for Heating Boilers
One for Steam Boilers

4. Lead-Lag Control
A maximum of 10 MM modules may be interconnected by a 2 wire screened data cable
Methods to identify the “lead” boiler by
Connecting a mains voltage onto terminal #88
Instructing the modules via the D.T.I. Module by software
Once a lead boiler has been selected it works in the following way
Lead boiler identifies it’s own firing rate
Lead-Lag software calculates the amount of heat being contributed to the system by this boiler

5. Options that must be set for both forms of Lead-Lag
Option #16 must be set to #1 or #3.
Option #33 (MM identification) must be set correctly. Each MM unit must have its own individual number (from #1 to #10). If this is not set then the MM units with the same ID will turn off and on repeatedly.
The fuel flow metering must be entered. This is how the MM units turn on and off, based on the firing rate of the burners.
To enter the fuel flow metering press ENTER when option #57 is set to #1 and this is displayed on the MM screen.
The next time the burner starts the fuel flow metering program will continue. The fuel valve angular position will be displayed and the heat input must be entered. This is done from high fire (position #1) down to low fire (position number #10).

6. Setting the Burner Rating
Options #34 and #77
Both of these options set the rating of the burner. Option #34 sets the value (e.g. 5) and option #77 selects the units (e.g. MBtu/Horse Power/Mega Watt).
Example:
Option #34 = 20
Option #77 = 9
Rating of burner = 20 MBtu’s
Option #77 = 2
Rating of burner = 20 MW

7. Sequence Scan Time and its Importance
Option #35
The sequence scan time has critical effect on the responsiveness of the system, as it dictates how often the Lead can make judgements to turn burners on and off.
It is important to change this option, especially on steam applications when there is a dynamic load.
Sequence scan time too long- sudden demand can cause the header pressure to drop, e.g. a sudden steam demand from an Autoclave
Sequence scan time too short- the system may bring another boiler on when the previous boiler to be turned on had not yet begun to contribute to the requirements, e.g. the sequence scan time is set shorter than the purge time of a burner.

8. Steam Boiler Sequential Control
Option #41
1st state is “on-line/lead” - is when the boiler is operating purely under the control of the MM module’s internal P.I.D. load controller
2nd state is “standby warming” – the header valve is shut. The boiler operates at a reduced set point that is an offset from the required value. In standby warming condition the burner can only run at low fire and only runs for a number of minutes each hour
3rd state is “off-line” – is with the burner shut down and the boiler cold.

9. Lag Boiler Operation in Standby Mode
Phantom set point only operates on the on times, option 54

10. Phantom Setpoint

11. 3-State Sequencing

12. 3-State Sequencing

13. Steam Boiler Sequential Control
Parameter #87- change up threshold: if the total capacity of the lead boiler reaches 95% (or value set in this parameter) then the 1st lag burner will start to fire. If the total capacity for both boilers is 95% then the 2nd lag boiler will start to fire.
Parameter #86- change down threshold: if the total capacity of 3 boilers goes below 85% (or the value set in this parameter) then the 2nd lag boiler will turn off. The lead and 1st lag boiler are able to cope with the load requirements. If the total capacity of the 2 remaining boilers goes below 85% then the 1st lag boiler will turn off since the lead boiler can cope with the load.

14. 2-State Sequencing

15. Low Pressure Steam Applications
If the setpoint is set to 20 psi (2bar) or less then low pressure steam control is implemented

16. 3-State Low Pressure Sequencing

17. 3-State Low Pressure Sequencing

18. 2-State Low Pressure Sequencing

19. Shuffle Sequencing

20. Potential Applications
3 twin burners
3 single furnace
boilers
1 twin burner &
2 single furnace

21. Hot Water Sequencing/Lead Lag Control
The following options must be set correctly for hot water sequencing to function correctly:
Option #53 – 0
Option #41 – 0
Ensures that boilers that are switched “off line” do not contribute return temperature to the water flow header and thus diluting the flow temperature to the building

22. Parameter 57 increased comms
Set this to the highest MM ID you are using. The bus driver will then only request data from the number of units as set in Parameter 57.

23. Further Parameters

24. IBS Diagnostic

25. IBS Diagnostic (Continued)
IBS screen shot showing diagnostic Par 83,84

26. Bus Driver
When using the lead-lag intelligent boiler sequencing (IBS), the bus driver is now determined by the lowest MM ID number, as set in Option 33. Previously this was always the lead boiler. This assists in speeding up the communications between boilers when sequencing and also with the DTI when used for shuffle sequencing.
IBS screen shot showing bus driver (diagnostic) Par 83,84

27. IBS Screen Shots

28. IBS Screen Shots (continued)

29. Trouble Shooting Make sure only 1 lead boiler is selected
Either via the DTI or a live input on terminal #88 (lead boiler select switch)
Fuel Flow Metering is correctly set
This must be calculated and entered for all boilers
It is very important that the correct cable is used for communication between boilers (Beldon 9501)
Use a daisy chain configuration (only connecting the screen at one end of the wire)

30. Trouble Shooting (continued)
Make sure only that there is no input on #94 &95 all units must be in auto (modulating)
Make sure that option 47 (cold start routine) is not optioned
Make sure that the reduced set point is not set, all boilers should use the required set point or phantom set point (standby warming)

31. Trouble Shooting (continued)
Difficulties with maintaining load can often be overcome by making minor alterations to the sequence scan time (option 35). Significant alterations to sequence scan time, will have a significant effect on the systems responsiveness
If using shuffle sequencing ensure parameter #101 is set correctly

32. Thank you for listening.