DSI SOP

 STANDARD OPERATING

PRACTICE (DSI)

NTPC DADRI

STAGE I – 4X210 MW

DRY SORBENT INJECTION SYSTEM

DSI EQUIPMENTS

1. Instrument air compressor

2. Viper mill

3. Oil pump viper mill

4. Blower ( injection and unloading )

5. Dehumidifier ( injection and unloading )

6. Heat Exchanger ( injection and unloading )

7. SBC silo

8. Weigh hopper

9. Rotary air lock ( RAL )( Injection and unloading )

10. Rotary vane feeder ( RVF )

11. Jumbo bag hopper

12. Splitter

DSI SYSTEM LINE DIAGRAM

OPERATION MODES

Injection mode: - The RVF speed generated by the control system will be continuously

adjusted to achieve a targeted flow rate entered by the operator

Emission mode: - In “EMISSION” mode, the RVF speed, and the corresponding injection rate, will

be based on the emissions reading determined by the SO2 analyzer

Unloading system: - Feed sorbent into Main SBC SILO through Truck unloading and Jumbo bag

hopper system.

INJECTION START /SEQUENCE AND CHECKS

PRE CHECKS START AND SHUTDOWN

CHECKS STATUS

1 Injection equipments Electrically normal.

2 Instrument airline pressure A dequate in local gauge (7-8 KSC)

and green signal in OWS

3 Oil level in viper mill Normal

4 Cooling water Charged

5 Manual valves APH inlet O pen

6 Manual valve Main SILO O pen

7 Injection system including valves No Fault

FOR INJECTION/EMMISSION MODE WITH AUTOMATIC MILLED OPERATION

SELECT FOLLOWING ON THE SCREEN:

a) Injection Air Blower Screen:

1. Injection Air Blower Select /Injection Air Heat Exchanger /

Injection Air Dehumidifier

Select stream A/B

2. Select Mode for Heat exchanger (AUTO/OFF/ MANUAL)

b) Sorbent Feed Screen:

1. System Mode (Process/Bypass A/Bypass B) Select Process

2. Weigh Hopper Feed Train Select stream (A/B)

3. Weigh Hopper A/B Shutdown

(CLEANOUT/NO CLEANOUT) Select CLEANOUT

4. Sorbent Feed Mode

(INJECTION/MANUAL/EMISSION) INJECTION/EMMISSION

5. Primary Mill Select (A/B)

c) Viper Mill A Screen:

1. Mill A (AUTO/OFF) Select AUTO

2. Mill Shutdown

(CLEANOUT/NO CLEANOUT) Select CLEANOUT

d) Viper Mill B Screen:

1. Mill A (AUTO/OFF) Select AUTO

2. Mill Shutdown

(CLEANOUT/NO CLEANOUT) Select CLEANOUT

e) Duct Injection Screen:

Auto Purge (ENABLE/DISABLE) Select ENABLE

Plug Detection (ENABLE/DISABLE) Select ENABLE

STARTING SEQUENCE:

On pressing System start button on DSI Overview Screen, equipment will start in

following sequence.

a) Viper mill’s oil pump

b) Viper mill

c) Dehumidifier

d) Injection line pneumatic valves open

1. When all above equipments are ON then Injection path OK will appear on blower start

permissive and blower will start.

2. After Mill speed of 25 HZ is reached then One-minute purge cycle will start.

3. Heat exchanger will start in auto and maintains line temperature above 10*c of dew

point.

4. After purge cycle mill speed will increase to milling speed i.e. 50Hz, Mill bearing high

purge air valve will open.

5. System ON indication will appear on Overview screen.

6. RAL (rotary air lock) will start.

7. After 10 sec RVF (rotary vane feeder) will start.

8. Feed rate of RVF in injection mode is set by operator (0-2.26 TPH).

9. Emission mode feed rate of RVF is decided by emission data set point monitored by Sox

analyzer.

10. During injection, if plug detection of any line is sensed (by 3.5% deviation from average

pipe temp), auto purge of plugged line will start.

Parameters to be monitored during system running

i. Mill speed milling ( 50 Hz )

ii. Mill vibration (Below 7 mm/second )

iii. Mill current (50 amp at 50 Hz )

iv. Mill Bearings temperature (below 90 deg. Cent.)

v. Injection Pressure (0. 35 to 0.5 Ksc )

SYSTEM SHUTDOWN PROCEDURES:

For stopping the system Normal Stop button to be pressed, and following

sequences will occur:

1) RAL and RVF will continue to run until the weigh hopper empties out (to avoid packing

of material in weigh hopper).

2) After stopping of RAL and RVF, System will go to final purge for three minutes.

3) Viper mill will ramp down to 25Hz.

4) Injection dehumidifier will cool down.

5) After system purge and cool down of dehumidifier, injection blower and heat exchanger

will stop. After 30 seconds dehumidifier will also stop.

6) Viper mill high flow purge air valve will change over to low flow purge air valve and

will continue to remain open during CIP (clean in place) sequence.

7) CIP (clean in place)

Before CIP sequence start system will ensure:

 Mill discharge valve closed.

 Auxiliary air valve open.

 Diverted valve position to atmosphere.

 Mill speed will be at 25 Hz.

CIP Sequence

1. In CIP, before going to mill wash cycle, purge air valve will open to purge Viper

mill for any material build up in mill body.

2. Viper mill wash cycle will start; spray water valve will open for three minutes.

3. After completion of wash cycle mill water spray valve will close.

4. After wash, drying sequence will start for twenty minutes, during drying sequence

auxiliary air valve at mill inlet will remain open.

5. During drying sequence mill purge air valve will pulse open at end of 1min, 10 min

and 15 min.

6. After completion of CIP, viper mill will get stop command, and diverter valve will

come to process position.

7. Viper mill bearing oil pump will shut down after 10min.

Parameters to be monitored during system Shutdown

 Mill speed @ wash ( 25 Hz )

 Mill speed @ Drying ( 50 Hz )

 Mill vibration (Below 7 mm/second )

 Mill current (50 amp at 50 Hz )

 Mill Bearings temperature (below 90 deg. Cent.)

IMMEDIATE STOP(During Emergency)

The Immediate Stop function initiated through the Operator Interface shuts the associated

system down immediately through the logic without going through a purge cycle. This

option should be used strictly as an emergency operation because omission of the purge

cycle could result in a plugged or partially plugged line. Everything for the system will

shut down except for the Mill Oil Lubrication System. The currently running Mill Oil

Lubrication System(s) will continue to run for 10 minutes after the Immediate Stop

function is selected.