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Join Date: Nov 2010
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Boiler/Turbine Follow

10/08/2012 9:47 AM

Hi,

i am working in a 2X300MW power plant.(coal fired)

Can anybody explain to me:

1) If in Boiler follow, Boiler Master is in Auto while Turbine Master is in Manual. How do we control the unit's load? How do we put in MW demand?Who is controlling MW demand?

2)If in Turbine follow, Boiler Master is in manual while Turbine Master is in Auto. How do we control the unit's load? How do we put in MW demand?Who is controlling MW demand?

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#1

Re: Boiler/Turbine Follow

10/08/2012 10:06 AM

<...How do we control the unit's load? How do we put in MW demand?Who is controlling MW demand?...>

The "we" that is the grid determines the load.

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Guru
Engineering Fields - Power Engineering - New Member

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#2

Re: Boiler/Turbine Follow

10/08/2012 1:18 PM

It depends upon what the dispatch authority (if there is one) has as its operational goal. We also have to determine which "load" we are attempting to control, the load on the turbine, the load on the boiler, or the load from the system. All of these combine to determine "who" (actually "what") is controlling the output of the system.

Here's a chart that describes the four possible states of two coupled controllers:

"...There are four usual modes of operation in the world of drum boilers: base mode, boiler-following mode, turbine-following mode, and coordinated control (Table 1). Each of these operating modes is described in the following paragraphs.


Table 1. Options for plant boiler control. Source: Tim Leopold

In general, the boiler master will be either in auto or manual control mode. The turbine is another matter. Turbine controls generally have a number of stand-alone loops - such as megawatt, pressure, valve position, or speed - which are control loops that do not respond to the DCS turbine master. If the turbine controls are not looking at the front end, then as far as the front end is concerned, the turbine is in manual control. For our purposes, "auto" under the turbine master heading in Table 1 means the front end is controlling the turbine governor valves..."

This snippet is from Part 2 of a series of four articles on tuning these controls and gives an excellent introduction in to modern boiler control systems. If you want to know how a power plant is controlled I suggest you start reading the entire series:

http://www.powermag.com/o_and_m/Boiler-Tuning-Basics-Part-I_1741.html

http://www.powermag.com/o_and_m/Boiler-Tuning-Basics-Part-II_1859.html

and download them all.

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