Download NFL summer internship report PDF

TitleNFL summer internship report
TagsBoiler Valve Power Supply Power Inverter Pressure Measurement
File Size1.2 MB
Total Pages54
Table of Contents

Basic Principle of Bourdon tube pressure gauge:
	The hardware Control Station
	Human Interface Station (HIS)
	Engineering Station
	Communication Network
Control Module
The control module is a multiple loop analog, sequential, batch and advanced controller, that provides powerful solutions to process control problems. It also handles data acquisition and information processing requirements providing true peer-to-peer communications.
The comprehensive set of function codes supported by these modules handles even the most complex control strategies. The system uses a variety of analog and digital I/O modules to communicate with and control the process. The control module can communicate with a maximum of 64 modules in any combination.
The module has three operating modes: execute, configure and error.
In the execute mode, the module executes control algorithms while constantly checking itself for errors. When an error is found, the front panel LEDs displays an error code corresponding to the type of error found.
In the configure mode, it is possible to edit existing or add new control algorithms. In this mode, the module does not execute control algorithms.
If the module finds an error while in execute mode, it automatically goes into error mode.
	Human Interface Station ( HIS )
The HIS is mainly used for operation and monitoring of the plant – it displays process variables, control parameters and alarms necessary for users to quickly grasp the operating status of the plant. It also incorporates open interfaces so that supervisory computers can access trend data, messages and process data & events.
Physically it consists of mostly general purpose PC with CRT, LCD based screens and normal keyboards with an option for dust and drip proof flat keys, which enable one touch operation.
Advantages of the DCS displays.
	High speed data update.
	Multi-monitor function permitting to display more information.
	Multi-window display mode.
	System message window display.
	Tuning trend displays.
	Dynamic graphics displays.
	Alarm handling functions.
	Print screen functions.
	Long term data archiving functions.
	Voice messaging functions.
	Security functions.
Engineering Station
	No matter how good a system is, it cannot succeed if the system configuration is extremely time consuming and difficult. So mostly the engineering functions are designed for efficient engineering- they are designed for ease of use and software reusability. It contains all the control logic templates, function codes, macros, shapes, and borders that are used to create controller configurations (control logic documents).
	Engineering tool consists of
	Memory blocks (locations and capacity ).
	Specific functions.
	Connecting tools.
	Constant value blocks.
	Build the logic / control strategy using the various function blocks.
	Compile the logic.
	Check for any errors.
	Remove the errors one by one.
	If no errors then a configuration file is generated.
	Download this file to the controller and putting the controller to configure mode.
	Change the mode of the controller to execute mode.
	New configuration is downloaded in the controller.
Communication Modules
	The communication cards connects Communication network -to-HMI interface. It enables controllers to:
	• Communicate field input values and states for process monitoring and control.
	• Receive control instructions from plant personnel through human system interfaces to adjust process field outputs.
	• Provide feedback to plant personnel of actual output changes through human system interfaces.
	• Communicate controller function block configuration information and parameters. These parameters determine the operation of functions such as process control, data acquisition, alarming, trending, and logging.
	• Report status.
	• Download firmware.
	Data is transferred in messages that contain system data, control, and configuration information and also in exception reports.
Communication network -to-control Unit Interface
	• Communication network provides a plant-wide communication network.
	• It provides time-synchronization across the control system plant wide.
	• Each node can operate independently of other Communication network nodes.
	• Control Unit interface modules provide localized startup and shutdown on power failure without operator intervention.
	• Fast response time. The 10-MHz communication rate gives timely information exchange.
	• The modules process information for maximum transmission efficiency.
	• The Control Unit interface modules handle four message types: broadcast, time-synchronization, multicast, and NIS poll.
	• All messages contain cyclic redundancy check codes and checksums to insure data integrity.
	PLC Advantages
Document Text Contents
Page 1







Page 2



Distributed Control System

Prepared in Partial Fulfillment of Industrial Training – I


National Fertilizers Ltd. BATHINDA

Submitted to: -


June-July 2012


The industrial training in an industry / project site is an essential part of curriculum for

completion of B.Tech degree. I am grateful to authorities at National Fertilizers Limited, Bathinda

for permitting me to undergo six weeks Industrial training in their esteemed organization. During

this training I have learnt a lot, for which I pay my heartiest gratitude to the HRD Sr. Manager

Page 27

(Figure 1. Wheatstone Bridge of the thermal conductivity detector.)

When all four resistances are the same, VOUT is zero and the bridge is considered balanced.

When zeroing, the reference gas is passed over all the filaments, the resistances will be the same

(because filaments are matched) andthe bridge is balanced. When the sample gas is passed over

half of the bridge, then VOUT’s value correlates to the content of the sample gas in the

reference.The detector is a four element Katharometer having two elements situated in the

reference gas and two elements in

the sample gas shown in Figure 2 below.

(Figure 2. Cut-away view of the thermal conductivity sensor.)

The four elements are electronically connected in a bridge circuit and a constant current is passed

through thebridge to heat the elements. If each element is surrounded by the same gas, then the

temperature, and hence theresistance, of each element will be similar and the bridge circuit will

be balanced.

Page 28


Measure the gas sample content of a sample/reference mixture by comparing
the thermal conductivity of the mixture with that of a reference.

For example, hydrogen has a thermal conductivity which is approximately
seven times greater than that of nitrogen, so small changes are readily
detected. All other common gases have thermal conductivities similar to
nitrogen so the method of measurement is fairly selective.

Other gases that may be measured using this technique are:

 Carbon Dioxide

 Oxygen

 Argon

 Methane

 Sulphur Dioxide

 Ammonia

In NFL we are using this type of analyzer for hydrogen

Gases to be detected are often corrosive and reactive. With most sensor

types, the sensor itself is direct exposed to the gas, often causing the

sensor to drift

or die prematurely.The main advantage of IR instruments is that the

Page 53

All input power to the mounting unit is fused and filtered through a power
entry panel. The power supplies providing the regulated voltages are fused
and filtered.

Regulated power supply voltages (+5 VDC, +15 VDC, –15 VDC, and +24
VDC), PFI, and STATUS signals are distributed to the system through the
system power bus bar located inside the cabinet. Power is transferred to the
mounting unit from the bus bar through cables.


After performing the training I have concluded that in a process industry, a
chemical plant like N.F.L. a large number of processes are to be controlled.
Each process includes large number of variables which are to be maintained
simultaneously. Therefore, large numbers of control mechanisms are
involved. Hence electronics, mechanical, instrumentation, electrical and
chemical knowledge go hand in hand.

From the study in
Captive Power Plant, one can conclude that plant’s non-stop working is a
prime factor as rest of the plants are completely dependent upon CPP. For
efficient working of the plant, the control system must be excellent and

Page 54

Process Portal fulfills all the needs. PP which supports DCS (Distributed
Control System), provides the best results with complete automation. The
system provides a very user friendly environment which is easy to
understand and operate. The PP system can also tackle emergency situations
very effectively thus reducing the large number of hazards present in the

The PP also
has the ability to generate reports and show the current and previous trends
just on a click. As all the instruments are redundant hence chances of failure
are reduced to minimum.

Though this system has number of merits, the negative aspect of the plant is
that in some cases DCS cannot be used as the process happens very fast. For
example, in dedicated controllers like ETS 301 and ETS 302, which are used
to control speed and load of turbines are standalone and only display is given
to DCS because of there high speed. Also with the upgrading technology, the
replacement of malfunctioning circuits becomes tough as they become
obsolete in the market.


 NFL manuals

 Engineer lecture’s

 Internet sites -

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