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									Station: NTPC- Simhadri   BHEL Ref No.PS-DC-186-500-0012
                                                           Sheet 1 of 10
                          NTPC Ref no SIM/1/TS/1/010
Plant area: BOILER
             PROCEDURE FOR CLEAN AIR FLOW TEST OF COAL PIPES
  SLNO
                               LIST OF CONTENTS

   1.0     PLANT DETAILS

   2.0     OBJECTIVE

   3.0     PROPOSAL

   4.0     SERVICES REQUIRED

   5.0     SAFETY PERECAUTIONS

   6.0     EMERGENCY PROCEDURE

   7.0     STATE OF THE PLANT

   8.0     METHOD

   9.0     COMPLETION CRITERIA


  10.0     APPENDICES

              LOG SHEET
Station: NTPC- Simhadri       BHEL Ref No.PS-DC-186-500-0012
                                                                            Sheet 2 of 10
                              NTPC Ref no SIM/1/TS/1/010
Plant area: BOILER
             PROCEDURE FOR CLEAN AIR FLOW TEST OF COAL PIPES
 SL.NO                                                       STATUS

   1.0       PLANT DETAILS

   1.1       There are 9 (Nine) mills provided for each Unit of 500 MW
             Capacity. These mills are of XRP 1003 type and are provided
             with individual lub-oil system. These mills are designated as
             A,B,C,D,E,F,G,H and J with Unit No. as prefix.

   1.2       There are 4 (four) coal pipes emanating from each mill from mill
             outlet point with individual mill discharge valve (MDV) and coal
             pipe shut-off gate near the coal bumer assembly. These coal
             pipes are subjected to clean air flow test to ensure uniform flow in
             all the coal pipes.

   1.3       The mills are pressurized mills with primary air fans supplying the
             air flow and the head required for overcoming milling system
             resistance.

   1.4       To maintain the required air flow through the mill, a control
             system comprising cold and hot dampers is provided, which
             measures and controls air flow to a specified set point.




Signatures

         NTPC                                                                BHEL
Station: NTPC- Simhadri       BHEL Ref No.PS-DC-186-500-0012
                                                                            Sheet 3 of 10
                              NTPC Ref no SIM/1/TS/1/010
Plant area: BOILER
             PROCEDURE FOR CLEAN AIR FLOW TEST OF COAL PIPES
 SL.NO                                                       STATUS

   1.5       Technical Specification of Mills and its lub-oil system are given
             below.


             XRP 1003 Mills

             a. Type               :     XRP 103
             b. Make & No.         :     BHEL 9
             c. Capacity           :     66.3 TPH
             d. Motor KW           :     525 KW
             e. Motor Speed         :    600 RPM
             f. System             :     Cold PA

             Lub-oil System

             a.   Pump Make/Type          :        Alekton / Screw
             b.   Capacity                :       70 LPM
             c.   Speed                   :       970 RPM
             d.   Relief Valve Setting        :    7.0 KSC
             e.   Motor Rating                  :   3.7 KW


   1.6       Since, Primary Air Fans and mills are available for this test, the
             required plant item completion list, for mechanical, Electrical and
             C & I to be prepared at site prior to test.




Signatures

         NTPC                                                               BHEL
Station: NTPC- Simhadri       BHEL Ref No.PS-DC-186-500-0012
                                                                                Sheet 4 of 10
                              NTPC Ref no SIM/1/TS/1/010
Plant area: BOILER
             PROCEDURE FOR CLEAN AIR FLOW TEST OF COAL PIPES
 SL.NO                                                       STATUS

   2.0       OBJECTIVE

             Clean Air flow test in milling system is carried out to check
             velocity variation between the pulverized coal pipes of a mill is
             within allowable limit and there by to ensure that correct size
             orifices are installed in coal pipes for equalizing the Air flow and
             there is no foreign material pluggage inside the pulverised coal
             pipes.

   3.0       PROPOSAL

   3.1       Clean Air flow tests shall be conducted in all the mills individually
             with Cold Air.

   3.2       The test will be conducted by running primary air fan and mill and
             flow measurement will be taken at specified locations and
             ensured that completion criteria (Section 9.0) is achieved.


   4.0       SERVICES REQUIRED

   4.1       Availability of man power with required tools for attending to any
             leakage in the system.

   4.2       Availability of operating personnal to coordinate the activities

   4.3       Availability of lighting arrangements and communication in the
             operating floor.




Signatures

         NTPC                                                                   BHEL
Station: NTPC- Simhadri        BHEL Ref No.PS-DC-186-500-0012
                                                                                Sheet 5 of 10
                               NTPC Ref no SIM/1/TS/1/010
Plant area: BOILER
             PROCEDURE FOR CLEAN AIR FLOW TEST OF COAL PIPES
 SL.NO                                                       STATUS

   4.4       Availability of portable fire fighting equipment near test area.

   4.5       Availability of auxiliary cooling water for mills & fans.

   4.6       Availability of instrument air supply

   4.7       Availability of LT supply

   4.8       Availability of HT supply


   5.0       SAFETY PRECAUTIONS

   5.1       Debris is and around milling system shall b e removed.

   5.2       Approach / Staircase / Platform wherever required are made
             available especially near the pitot tube traversing location.

   5.3       First aid kit available near test.

   5.4       The test team should be aware of the procedure adopted.

   5.5       Other agencies working near the test area are informed / cleared
             as per requirement.


   6.0       EMERGENCY PROCEDURE

             The test team should be aware of the steps to be taken to trip the
             running equipment in case any emergency / abnormal
             observations are notified to them.


Signatures

         NTPC                                                                   BHEL
Station: NTPC- Simhadri        BHEL Ref No.PS-DC-186-500-0012
                                                                              Sheet 6 of 10
                               NTPC Ref no SIM/1/TS/1/010
Plant area: BOILER
             PROCEDURE FOR CLEAN AIR FLOW TEST OF COAL PIPES
 SL.NO                                                       STATUS

   6.2       The test team should be aware of actions to be taken in case of
             injury to any personnel.

   6.3       The test team should be aware of operating instructions of
             portable fire extinguishers.


   7.0       STATE OF THE PLANT

   7.1       The trial run of the mill which is selected for the test, is completed
             and is ready for operation from remote.

   7.2       One set of ID, FD & PA fan is commissional and ready for
             operation from remote.

   7.3       The corresponding raw coal feeder is erected and is boxed up
             property to avoid any air escape from mill through these feeders.

   7.4       Mill dischage damper is commissioned and kept opened fully.

   7.5       Mill and Coal pipes seal air dampers are commissioned and kept
             fully closed.

   7.6       The Coal Pipes isolation gate near the burner end (in all 4
             corners) are kept opened fully.

   7.7       Two suitable size tapping points at 90 degrees apart in the same
             plane provided in the vertical straight portion of the all the 4 P.C.
             pipies of the mill.



Signatures

         NTPC                                                                  BHEL
Station: NTPC- Simhadri        BHEL Ref No.PS-DC-186-500-0012
                                                                             Sheet 7 of 10
                               NTPC Ref no SIM/1/TS/1/010
Plant area: BOILER
             PROCEDURE FOR CLEAN AIR FLOW TEST OF COAL PIPES
 SL.NO                                                       STATUS

   7.8       Proper access platform provided for taking pilot tube differential
             pressure measurement.

   7.9       Pilot tube differential pressure gauge, Thermometer (0-100 Deg.
             C), polethene tubes of sufficient length, are made available.

  7.10       10 markings are made on the pilot tube at a distances as given
             below. At 0.0436 R, 0.135 R, 0.238 R, 0.358 R, 0.507 R, 1.492 R,
             1.642R, 1.762R,1.816 Rand 1.956 R, (R-Inside radius of the Coal
             Pipe)

  7.11       All gates and dampers in Primary Air and Milling circuits are
             commissioned and ready for operation.

  7.12       All leakage points in the milling circuit are arrested.

  7.13       Reliable communication system among the test team members is
             made available.

  7.14       The classifier assembly is serviced thoroughly and all the vanes
             are set uniformly at desired position to facilitate air flow required
             for conducting the test.


   8.0       METHOD

   8.1       Start ID, FD & PA fans and establish furnace draft and air flow
             through the selected mill.

   8.2       Mill also started and kept running.



Signatures

         NTPC                                                                 BHEL
Station: NTPC- Simhadri        BHEL Ref No.PS-DC-186-500-0012
                                                                               Sheet 8 of 10
                               NTPC Ref no SIM/1/TS/1/010
Plant area: BOILER
             PROCEDURE FOR CLEAN AIR FLOW TEST OF COAL PIPES
 SL.NO                                                       STATUS

   8.3       Air flow through the mill is in creased by opening hot air damper
             and loading PA fan accondingly.

   8.4       PA header pressure shall be maintained at 750-800 mmwc.

   8.5       Select a Coal Pipe of average length, and insert the pilot tube to
             the center of the pipe and adjust the air flow to produce the
             calculated pilot tube differential pressure (approx imetely 110%
             flow)

   8.6       Velocity profile in each Coal Pipe shall be obtained by traversing
             the pilot tube at two directions, 900 apart at the center of equal
             areas.

   8.7       Record mill air temperature, mill air flow indication mill differential
             pressure, PA header pressure at control room. If control room
             indications not available, suitable measuring arrangements to be
             made at local.

   8.8       Convert the pilot tube differential pressure reading (velocity head)
             into air velocity inside the Coal Pipe by using the formula

             V = 0.2365227           h. (t)

             Where V - air velocity in m/Sec

                     h – Pilot tube dift. Pr. in mmwc

                     t – Air temp in 0 K

   8.9       Calculate the average velocity. Find the maximum and minimum
             velocity and the deviation shall be within plus or minus 5% of the
             average velocity.


Signatures

         NTPC                                                                   BHEL
Station: NTPC- Simhadri      BHEL Ref No.PS-DC-186-500-0012
                                                                          Sheet 9 of 10
                             NTPC Ref no SIM/1/TS/1/010
Plant area: BOILER
             PROCEDURE FOR CLEAN AIR FLOW TEST OF COAL PIPES
 SL.NO                                                       STATUS


             % Max. deviation = Max.Velocity - Ave.Velocity
                                                              x 100

                                      Ave. Velocity

             % Minimum deviation = Ave.Velocity – Min.Velocity
                                                                  x 100
                                          Average Velocity


   9.0       COMPLETION CRITERIA

   9.1       The clean air flow test for Coal Pipes completed after achieving
             the following criteria.

                a)     Velocity variation of maximum and minimum velocity is
                       within plus or minus 5% of average velocity.




Signatures

         NTPC                                                             BHEL
                                                                                 Sheet 10 of 10

          10.0                                 LOG SHEET

                                                                                              DATE:

          PROJECT         :
          UNIT            :
          ACTIVITY        :


                     Corner 1                     Corner 2           Corner 3             Corner 4
 S.No            A                 B             A        B         A        B        A           B
           Vh        V        Vh           V   Vh V Vh V          Vh V Vh V      Vh       V Vh      V
  1
  2
  3
  4
  5
  6
  7
  8
  9
  10
  11
Ave.Vel
  Air
 Flow


  1.      Air Temperature              :
  2.      Coal Pipe ID                 :
  3.      PA HDR Pressure              :
  4.      Furnace Pressure             :
  5.      Max. Velocity                :       (Tolerance +5%)
  6.      Average Velocity             :
  7.      Min. Velocity                :       (Tolerance – 5%)



   Signatures

           NTPC                                                                       BHEL
PROCEDURE FOR CLEAN AIR FLOW TEST
          OF COAL PIPES

								
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