PRE-BOILER SYSTEM OBJECTIVES To remove dirt ,oil ,grease etc., from - - PowerPoint PPT Presentation

SLIDE 1

CHEMICAL CLEANING OF PRE-BOILER SYSTEM

SLIDE 2

OBJECTIVES To remove dirt ,oil ,grease etc., from Condensate ,Feed water, Drip and Extraction steam lines of HP and LP heaters prior to putting these systems in regular service. This is to ensure flow of clean condensate and feed water to the boiler.

SLIDE 3

STATE OF THE PLANT

• Hydro-test of the entire system to be flushed declared

completed.

• All the regenerative equipments are installed in position and

temporary pipeline connection as per scheme is complete.

• The bore of the temporary pipelines should preferably be the

same as that used in permanent system.

• All permanent support are provided for all the pipelines before

flushing.

• Plugs to be provided in the safety valves of LPHs,water seal

inlets in flash tanks and LPH 1 and in C&I tapping.

• Screens to be provided on booster pump suction line and acid

cleaning pump suction line

SLIDE 4

• Availability of auxiliary steam.
• Reagent preparation plant.
• Sampling points for each circuit.
• Level gauge on tank, pressure gauges and temperature

indicators wherever required.

• All the cutting and welding work on instrument tapping points

are complete upto isolating root valves.

• All the orifices,flow nozzles, control valves and NRV internals

are removed and a checklist is prepared. Spool pieces are provided wherever required.

• Installation of temporary chemical cleaning pumps(2 nos.) and

connected piping along with required instrumentation is complete.

• During post mounting cleaning it is proposed to use chemically

clean water from condensate storage tank.

SLIDE 5

• Readiness of process water supply system,condenser

circulating water system with pump house.

• Availability of compressed air.
• Proximate analysis laboratory facility.
• Power supply to acid cleaning pumps,CEPs,condensate

emergency make up pumps, condensate normal make up pumps, motor operated valves and lighting.

SLIDE 6

EQUIPMENTS AND RESOURCES FOR WATER WASHING

• Condensate storage tanks.
• Condenser of volume 1000m3 as a reservoir for storing the

dematerialized water.

• Turbine condensate pumps (3 nos.).
• Chemical cleaning pumps (q=300t/h,h=80mwg,n=1500rpm)-

2nos.

• Compressor plant and pipeline Dn100 to supply air into the

washing circuit with the parameters not less than q=20m3/min,p=0.6MPa

• Pipelines and valves Dn 20-300,Pn 1.6MPa

SLIDE 7

EQUIPMENT AND RESOURCES FOR CHEMICAL CLEANING AND PASSIVATION

• Deaerator and Feed Water Storage Tank.
• Chemical cleaning pumps (q=300t/h,h=80mwg,n=1500rpm)-

2nos.

• Pipelines and valves Dn 20-300,Pn 1.6MPa
• SG Package neutralizing basin for collecting the spent

solutions.

• Reagent Preparation Plant designed for storage, preparation

and supply of chemical reagents.

• Chemical reagents.
• Washing process controlling instruments (flow elements,

pressure gauges, level gauges, temperature elements)

SLIDE 8

The pre-boiler system consists of

• Condensate system
• Drip system
• Feed water system
• Extraction steam lines to Regenerative Heaters

SLIDE 9

→ Condensate system comprises of 3 nos. of Condensate Extraction Pumps,Low Pressure Heaters, Gland Steam Cooler,Deaerator,connecting pipelines including excess condensate line upto Condensate storage tank.

SLIDE 10

→Feed water system comprises 2 nos. of motor driven boiler feed pumps,2 nos. of Turbine driven boiler feed pumps ,their booster pumps and recirculation lines, high pressure heaters, their connecting pipelines upto econimiser inlet.Reheater and Superheater spray line are also included for the purpose of flushing.

SLIDE 11

→ Drip system comprises of the shell side of all LP and HP heaters and their normal and emergency drip lines.

SLIDE 12

→Extraction steam system consists of bled steam lines from different stages of Turbines (HPT,IPT and LPT) to LP and HP heaters,Deaerator and TDBFPs.

SLIDE 13

CLEANING METHOD

• Pre- mounting cleaning.
• Extraction steam lines to regenerative heaters
• Post-mounting cleaning.
• Feed water line,Condendate line and heater drip lines.
• Steam blowing.
• MS line,CRH line , HRH line ,steam line to TDBFPs etc.

SLIDE 14

METHODS AND SCOPE OF CLEANING Post Mounting Cleaning

• Main Turbine and BFP Drive Turbine Condenser Cleaning.
• Hydro-pneumatic Washing with Demineralized Water of Unit

Circulating System.

• Chemical Cleaning of Water–Steam path of Heater and

Pipeline with hydrofluoric Acid solution.

• Chemical Passivation of Water-Steam path of Heater and

Pipeline with Hydrogen Peroxide solution added with Ammonia.

SLIDE 15

Pre-Mounting Cleaning

• Chemical Cleaning of Pipelines in a bath of Hydrofluoric Acid

solution.

• Spent solution displacement.
• Chemical Passivation of Pipelines with Hydrogen Peroxide

solution added with ammonia.

• Air Blowing of Passivated pipelines for drying.

SLIDE 16

Main Turbine and BFP Drive Turbine Condenser Cleaning or Condenser Degreasing. STEP- I

• The demineralized water is heated upto 700c in the De-aerator

FST.

• The Chemical solution prepared in reagent preparation plant is

mixed with the hot water in the De-aerator FST.

SLIDE 17

• The hot solution is transferred to Condenser with the help of

temporary chemical cleaning pump through temporary pipelines connecting pump discharge header to the CEP discharge header and the cooling device sprayers of Condenser.

• Circulation is completed by bringing this solution from

condenser to Chemical Cleaning pump suction header through CEP suction header and temporary pipeline connection.

• Circulation is continued for 4 hrs.
• System is isolated after closing one temporary gate valve

provided in the circuit (refer to scheme.)

SLIDE 18

FST DEAERATOR AUX.STEAM CHEMICAL BP BP BP BP ACID CLEANING PUMPS CONDENSERS CEPS

SLIDE 19

STEP –II

• CEPs are charged from water side by opening suction valve

and through proper venting, keeping discharge valve in closed condition and suction strainer in position.

• Flushing started by alternately starting and stopping CEPs and

completing the circulation from CEP discharge to CEP suction line through recirculation line and condenser.

SLIDE 20

• Circulation is continued for 4 hrs.
• After cleaning the spent solution is pumped from condenser to

neutralizing basin.

• Water washing of Condenser started and continued for 4 hrs.

using the two circuits already described..

SLIDE 21

DEAERATOR FST AUX.STEAM CHEMICAL BP BP BP BP ACID CLEANING PUMPS CONDENSERS CEPS

SLIDE 22

Hydro-pneumatic Washing of Unit Circulating System with Demineralized Water and air. → Hydro-pneumatic washing of unit circulating system is carried

• ut step by step with simultaneous water and air supply.

→Demineralized water for washing is stored in the De-aerator FST and Condenser. →Hydropneumatic washing is declared completed if suspended matter content of the washing water reaches no more than 100mg/kg. →Hydro-pneumatic washing of unit circulating system is done using following four circuits.

SLIDE 23

CIRCUIT 1:

Circuit 1A De-aerator FST – TDBFP A booster pump suction line – BP strainers – Temporary header connecting the BP suction lines downstream of the strainers – Acid cleaning pumps – Temporary discharge header – Temporary lines to the discharge gate valves of four feed pumps – Feed lines to HPH – Bypass line of all HPH – HPH bypass lines – Water path of HPH 6,7,8 – Feed water line upto boiler feed control unit – Temporary discharge line to the circulating water line - De-aerator FST.

SLIDE 24

Circuit 1B De-aerator FST – TDBFP B booster pump suction line – BP strainers – Temporary header connecting the BP suction lines downstream of the strainers – Acid cleaning pumps – Temporary discharge header – Temporary lines to the discharge gate valves of four feed pumps – Feed lines to HPH – Bypass line of all HPH – HPH bypass lines – Water path of HPH 6,7,8 – Feed water line upto boiler feed control unit – Temporary discharge line to the circulating water line - De-aerator FST.

SLIDE 25

Circuit 1C De-aerator FST – MDBFP booster pump suction line – BP strainers – Temporary header connecting the BP suction lines downstream of the strainers – Acid cleaning pumps – Temporary discharge header – Temporary lines to the discharge gate valves of four feed pumps – Feed lines to HPH – Bypass line of all HPH – HPH bypass lines – Water path of HPH 6,7,8 – Feed water line upto boiler feed control unit – Temporary discharge line to the circulating water line - De-aerator FST.

SLIDE 26

Circuit 1D De-aerator FST – Booster pump suction line – BP strainers – Temporary header connecting the BP suction lines downstream of the strainers – Acid cleaning pumps – Temporary discharge header – Temporary lines to the discharge gate valves of TDBFP A – Feed lines to HPH – Bypass line of all HPH – HPH bypass lines – Water path

• f HPH 6,7,8 – Feed water line upto boiler feed control

unit – Temporary discharge line to the circulating water line - De-aerator FST.

SLIDE 27

Circuit 1E De-aerator FST – Booster pump suction line – BP strainers – Temporary header connecting the BP suction lines downstream of the strainers – Acid cleaning pumps – Temporary discharge header – Temporary lines to the discharge gate valves of TDBFP B – Feed lines to HPH – Bypass line of all HPH – HPH bypass lines – Water path of HPH 6,7,8 – Feed water line upto boiler feed control unit – Temporary discharge line to the circulating water line - De-aerator FST.

SLIDE 28

Circuit 1F De-aerator FST – Booster pump suction line – BP strainers – Temporary header connecting the BP suction lines downstream of the strainers – Acid cleaning pumps – Temporary discharge header – Temporary lines to the discharge gate valves of MDBFP A – Feed lines to HPH – Bypass line of all HPH – HPH bypass lines – Water path of HPH 6,7,8 – Feed water line upto boiler feed control unit – Temporary discharge line to the circulating water line - De-aerator FST.

SLIDE 29

Circuit 1G De-aerator FST – Booster pump suction line – BP strainers – Temporary header connecting the BP suction lines downstream of the strainers – Acid cleaning pumps – Temporary discharge header – Temporary lines to the discharge gate valves of MDBFP B – Feed lines to HPH – Bypass line of all HPH – HPH bypass lines – Water path of HPH 6,7,8 – Feed water line upto boiler feed control unit – Temporary discharge line to the circulating water line - De-aerator FST.

SLIDE 30

Circuit 1H De-aerator FST – Booster pump suction line – BP strainers – Temporary header connecting the BP suction lines downstream of the strainers – Acid cleaning pumps – Temporary discharge header – Temporary lines to the discharge gate valves of four feed pumps – Feed lines to HPH – 50 % bypass line of all HPH– Feed water line upto boiler feed control unit – Temporary discharge line to the circulating water line - De-aerator FST.

SLIDE 31

Circuit 1I De-aerator FST –Booster pump suction line – BP strainers – Temporary header connecting the BP suction lines downstream of the strainers – Acid cleaning pumps – Temporary discharge header – Temporary lines to the discharge gate valves of four feed pumps – Feed lines to HPH – 100 % bypass line of all HPH – Feed water line upto boiler feed control unit – Temporary discharge line to the circulating water line - De-aerator FST.

SLIDE 32

Circuit 1J De-aerator FST –Booster pump suction line – BP strainers – Temporary header connecting the BP suction lines downstream of the strainers – Acid cleaning pumps – Temporary discharge header – Temporary lines to the discharge gate valves of four feed pumps – Feed lines to HPH bypass line for 6A,7A,8A – Feed water line upto boiler feed control unit – Temporary discharge line to the circulating water line – De-aerator FST.

SLIDE 33

Circuit 1K De-aerator FST –Booster pump suction line – BP strainers – Temporary header connecting the BP suction lines downstream of the strainers – Acid cleaning pumps – Temporary discharge header – Temporary lines to the discharge gate valves of four feed pumps – Feed lines to HPH bypass line for 6B,7B,8B – Feed water line upto boiler feed control unit – Temporary discharge line to the circulating water line – De-aerator FST.

SLIDE 34

Circuit 1E De-aerator FST –Booster pump suction line – BP strainers – Temporary header connecting the BP suction lines downstream of the strainers – Acid cleaning pumps – Temporary discharge header – Temporary lines to the discharge gate valves of four feed pumps – Feed lines to HPH – Water path of HPH 6A,7A,8A – Feed water line upto boiler feed control unit – Temporary discharge line to the circulating water line – De-aerator FST.

SLIDE 35

Circuit 1L De-aerator FST –Booster pump suction line – BP strainers – Temporary header connecting the BP suction lines downstream of the strainers – Acid cleaning pumps – Temporary discharge header – Temporary lines to the discharge gate valves of four feed pumps – Feed lines to HPH – Water path of HPH 6B,7B,8B – Feed water line upto boiler feed control unit – Temporary discharge line to the circulating water line – De-aerator FST.

SLIDE 36

CIRCUIT 2: Circuit 2A Condenser – CEP suction lines – Acid cleaning pumps – CEP discharge header – Condensate line bypassing LPHs – line down stream of LPHs – Temporary discharge line to the circulating water system – De- aerator FST Circuit 2B Condenser – CEP suction lines – Acid cleaning pumps – CEP discharge header – Water side of LPHs – Line down stream of LPHs – Temporary discharge line to the circulating water system – De-aerator FST

SLIDE 37

CIRCUIT 3:

Circuit 3A Condenser – CEP suction lines – Acid cleaning pumps – CEP discharge header – Condensate line bypassing LPHs – Temporary header for water supply to the HPH steam space – Steam side of HPH 6A – HPH discharge line – Temporary discharge line to the circulating water system – De-aerator FST

SLIDE 38

Circuit 3B Condenser – CEP suction lines – Acid cleaning pumps – CEP discharge header – Condensate line bypassing LPHs – Temporary header for water supply to the HPH steam space – Steam side of HPH 6B – HPH discharge line – Temporary discharge line to the circulating water system – De-aerator FST

SLIDE 39

Circuit 3C Condenser – CEP suction lines – Acid cleaning pumps – CEP discharge header – Condensate line bypassing LPHs – Temporary header for water supply to the HPH steam space – Steam side of HPH 7A – HPH discharge line – Temporary discharge line to the circulating water system – De-aerator FST

SLIDE 40

Circuit 3D Condenser – CEP suction lines – Acid cleaning pumps – CEP discharge header – Condensate line bypassing LPHs – Temporary header for water supply to the HPH steam space – Steam side of HPH 7B – HPH discharge line – Temporary discharge line to the circulating water system – De-aerator FST

SLIDE 41

Circuit 3E Condenser – CEP suction lines – Acid cleaning pumps – CEP discharge header – Condensate line bypassing LPHs – Temporary header for water supply to the HPH steam space – Steam side of HPH 8A – HPH discharge line – Temporary discharge line to the circulating water system – De-aerator FST

SLIDE 42

Circuit 3F Condenser – CEP suction lines – Acid cleaning pumps – CEP discharge header – Condensate line bypassing LPHs – Temporary header for water supply to the HPH steam space – Steam side of HPH 8B – HPH discharge line – Temporary discharge line to the circulating water system – De-aerator FST

SLIDE 43

CIRCUIT 4:

Circuit 4A Condenser – CEP suction lines – Acid cleaning pumps – CEP discharge header – Condensate line bypassing LPHs – Temporary header for water supply to the LPH steam space – Steam side of LPH 1A – LPH discharge line – Temporary discharge line to the circulating water system – De-aerator FST

SLIDE 44

Circuit 4B Condenser – CEP suction lines – Acid cleaning pumps – CEP discharge header – Condensate line bypassing LPHs – Temporary header for water supply to the LPH steam space – Steam side of LPH 1B – LPH discharge line – Temporary discharge line to the circulating water system – De-aerator FST

SLIDE 45

Circuit 4C Condenser – CEP suction lines – Acid cleaning pumps – CEP discharge header – Condensate line bypassing LPHs – Temporary header for water supply to the LPH steam space – Steam side of LPH 2 – LPH discharge line – Temporary discharge line to the circulating water system – De-aerator FST

SLIDE 46

Circuit 4D Condenser – CEP suction lines – Acid cleaning pumps – CEP discharge header – Condensate line bypassing LPHs – Temporary header for water supply to the LPH steam space – Steam side of LPH 3 – LPH discharge line – Temporary discharge line to the circulating water system – De-aerator FST

SLIDE 47

Circuit 4E Condenser – CEP suction lines – Acid cleaning pumps – CEP discharge header – Condensate line bypassing LPHs – Temporary header for water supply to the LPH steam space – Steam side of LPH 4 – LPH discharge line – Temporary discharge line to the circulating water system – De-aerator FST

SLIDE 48 M M M M M M M M M M M M M M M M M M LPH-1A LPH-1B LPH-2 LPH-3 LPH-4 M M M DRIP /P-A DRIP /P-B M M M M

BP

M

BP

M M M M M M M M M M M MAIN CONDENSER - 1 MAIN CONDENSER - 2 M M M M M M

GSC CPU

M CEP-3 CEP-2 CEP-1 M HPH-6A HPH-7A HPH-8A M M M M M M M M M HPH-6B HPH-7B HPH-8B M M M M M M M M M M M M M M M M M TO ECO I/L

SLIDE 49

BP

M

BP

M M M M M M M M M M M MAIN CONDENSER - 1 MAIN CONDENSER - 2 M M M M M M

GSC CPU

M CEP-3 CEP-2 CEP-1 M HPH-6A HPH-7A HPH-8A M M M M M M M M M HPH-6B HPH-7B HPH-8B M M M M M M M M M M M

TO ECO I/L

SLIDE 50 M M M M M M M M M M M M M M M LPH-1A LPH-1B LPH-2 LPH-3 LPH-4 M M

BP

M

BP

M M M M M M M M M MAIN CONDENSER - 1 MAIN CONDENSER - 2 M M M M M M

CPU

M CEP-3 CEP-2 CEP-1 M M M M M M M M M M M

GSC

M M M

SLIDE 51 M M M M

BP

M

BP

M M M M M M M M M M M MAIN CONDENSER - 1 MAIN CONDENSER - 2 M M M M M M

GSC CPU

M CEP-3 CEP-2 CEP-1 M HPH-6A HPH-7A HPH-8A M M M M M M HPH-6B HPH-7B HPH-8B M M M M M M M M M M M M M M M TO ECO I/L

SLIDE 52 M M M M M M LPH-1A LPH-1B LPH-2 LPH-3 LPH-4 M M M DRIP /P-A DRIP /P-B M M

BP

M

BP

M M M M M M M M M M M MAIN CONDENSER - 1 MAIN CONDENSER - 2 M M M M M M

GSC CPU

M CEP-3 CEP-2 CEP-1 M M M M M M M M M

SLIDE 53

ACID CLEANING: →Acid cleaning is made using the same four circuits on which water washing is made. To make closed circuit the de-aerator is included into the scheme, in which cleaning solution can be heated if required. →Reagents in liquid form, each by separate pipeline, are supplied from reagent preparation plant into suction pipeline

• f acid cleaning pump.

→Minimum Hydrofluoric acid solution temperature is 200C and

• ptimum temperature is 400 C

→Acid cleaning phase duration is 4-8 hours at temperature up to 400C →Hydrofluoric acid cleaning solution concentration is selected depending on ferric oxide quantity in the circuit to be washed.

SLIDE 54

CLEANING SOLUTION DISPLACEMENT: →Primary displacement of spent cleaning solution is carried out by compressed air from the compressor-house ; this allows saving of water for washing. →The final removal of solution is carried out with standard speed ; in drainable section – not less than 1m/s and in non- drainable section not less than 2m/s. Solution is removed from the circuits by hydraulic pneumatic method with water supply from condensers by acid cleaning pumps. →Acid cleaning is declared finished if discharge water conductivity reaches 20µs/cm.

SLIDE 55

PASSIVATION: →Passivation of acid cleaned surface is carried out with Hydrogen Peroxide solution added with ammonia. →Before passivation the acid cleaned surface is neutralized with the circulation of ammonia solution. →Passivation is carried out with demineralized water under the following conditions:

• Hydrogen Peroxide concentration is 0.02%.
• Ammonia Concentration is upto 0.8%.
• Solution temperature is 400C.
• Duration 4-6 hours.
• Solution flow velocity is 0.3 to 0.5 m/s

SLIDE 56

→Metal surface treatment with oxidant solution permits to form thin protective ferric oxide film.