19 December, 2013 DIAGNOSIS REPORT ON BED TUBE FAILURE IN 24 TPH FBC BOILER AT APOLLO TYRES, CHENNAI PLANT By Venus energy audit system The 24 TPH FBC boiler was shut following a bed tube failure on 9th December 2013. The bed tubes along with inlet and outlet header were replaced in November 2013. The visit was made immediately on urgent basis to inspect the failed tube and the inside condition of the boiler. On 11th December the boiler was inspected. Further plant operational data were reviewed. Circulation analysis calculations were done. This is the final failure analysis report along with recommendations. Failed tube The bottom tube of a bed coil in 2nd compartment -23rd row had failed due to overheating. The secondary damage happened at middle tube of 24th row. Bottom tube of 24th row was removed for the purpose of access for plugging the failed tubes. There are warped signs on the failed tube. The failed tube can be seen in photo 2 & 3 in annexure 1. There was no water side scale inside the failed tube. However the tube was having oxide scales due to overheating. See photo 7 in annexure 1. This is compared with the previous failed tube in June to October 2013. The photo 8 shows the inside of the oxidised tube taken out in earlier failure incidents. In this also no thick water side scale is seen. What is seen is only oxide scales due to overheating of the tube. There were no scales in the two adjacent tubes which failed due to secondary damage. See photo 9 & 10 in annexure 1.The failed tubes were removed before the arrival. Hence the exact orientation was not known. It was learnt the bottom tube had failed at the top half. However from furnace side, it was seen that the failed tube was just above the coal nozzle. It should be noted that the heat flux is high above coal nozzles. The photographs of failed tubes in the previous occasions, that is, in July to October 2013 can be seen in photos 4, 5 and 6 of annexure 1. All the tubes are with overheated signs. The tubes are swelled, twisted and bowed. The tubes are seen with cracks. Failure mode & cause- Starvation & not scaling The tube had failed due to starvation. The reasons can be excess pressure drop in circulation circuit or due to the loose scales blocking the water flow. This failure is not due to scaling. It had failed by starvation only. Steam blanketing had taken place in the failed tube. Once the steam blankets, the flow is retarded. The metal temperature shoots up due to reduced cooling. The metal gets oxidised. Since this is low pressure boiler, the tube does not fail immediately. The tube which had failed was found to be above coal nozzle. At this point the heat flux will be high.

This is due to high VM imported coal and due to high fines generally present in imported coal. Loose water side hardness scales are being generated due to poor water chemistry management. The boiler bank tubes and drums are seen with scales. Scales peel off and get in to circulating water. These loose scales can retard circulation. Pressure drop in circulation circuit can be high due to below mentioned design defects. Turbo separators are provided in less number. As such turbo separators are not needed for low

pressure boilers. The bed coil outlet header to waterwall links are connected to one side of the waterwall. The

links are not distributed to all four bottom headers of waterwall. The bed tubes to header fitment connections are not good. During the replacement, the stubs

were not fitted as per IBR drawing. This can also cause differential circulation among the bed tubes.

DETAILED REPORTS Loose scale inside the bed coil inlet header The bed coil inlet header was partly filled with loose scales approximately at the location where the tube had burst. However we cannot say that the loose scales were the cause for failure. See photo 11, showing the location of loose scales in the bed coil bottom header. The scales were removed and given for analysis. The scales are seen to be iron oxide scales with small amount of hardness scales. See photo 12. The oxide scales generated from the starved tubes could have accumulated here. The scale analysis would explain this. Wrong tube to header fit up The header to stub fit up was wrong. The tubes were found projecting inside the header in a haphazard way. See photo 13. This can affect the circulation in some tubes. A tube projecting can cause less flow in the downstream tube. Also when the tube is projected in to the header, the local turbulence is created, which would affect the free entry of water in to the tube. The correct arrangement as per IBR figure can be seen in photo 14. Wrong choice of turbo separators The steam drum is fitted with six number tangential inlet turbo separators. Turbo separators inlet opening size is 40 x 190 mm. With an overall circulation ratio 13 (worked out and presented in annexure 3), the velocity is working out to be 16 m/s. The desired velocity is only around 5 m/s. to be very high affecting the circulation ratio. The highest pressure drop in the circulation circuit is found to be at the turbo separators. It is necessary to remove the turbo separators immediately. Low pressure boilers need only baffle separators.

Improper circulation system design The design of circulation system is not proper. We have performed circulation calculations for four options. The bed coil inlet header is provided with two 200 nb downcomers. The bed coil inlet header is located at the left side of the boiler. The riser links of six nos of 150 nb are connected to right side of the waterwall. There are no direct connections to left side wall, front wall and rear wall. The waterwall length is about 6.5 m. The entire waterwall will not be working as relieving circuit. This can affect the circulation. Out of the six links, only extreme links will supply water to the remaining three side waterwalls. The left side wall will receive less circulation in the present arrangement. The circulation calculations were made by us for the various cases and discussed below. Waterwall distortion The waterwall appears to be distorted. See photo 27. This can also happen if there had been a low water level at any time. The condition of the waterwall before the failures, must be known to comment on the distortion. No fin cracks are seen. See water level gauge fit up in photo 16. The visible range of water level gauge is seen to cover only the lower part of the drum. It is possible that the water level is being operated a little less than desired level. The NWL is generally at the centre line of the drum. The operator orally informed that presently the water level is maintained in between 4th and 5th bolts of the level gauge. It is advised to operate in between 5th and 6th bolts. Hardness scales inside the bank tubes / steam drum / mud drum The bank tubes are found with scales. See photo 20 and 23. The scale thickness is around 2 mm maximum. This can increase the boiler exit temperature. In addition there will be problem of bank tube expansion joint in to the drums. Scale will increase the metal temperatures. Hence tube will expand more and lead to failure. On sudden cooling there will be leak / crack in the tube. Whenever the boiler is started and stopped, the scales peel off due to thermal expansion and flow to the bed coil header. This can affect the circulation inside the bed tubes. Scale marks are seen up to top of drum. See photo 17 & 18. Water side of the steam drum is seen with scales up to NWL. There must have been severe scaling issues since the beginning of 2013. See photo 33, 34 and 35. The boiler water hardness is seen to have gone up 30 ppm in boiler water in the recent times. The hardness of boiler water is not being tested on regular basis. Only the chemical supplier – Uniway who supplied chemicals checked this once in 15 days. He had reported that the hardness was high in the recent times. He had also commented that blow down to be increased. This is a wrong comment. Only TSP to be increased to sludge out the Ca, Mg salts. The chloride levels were on the rise, indicating there is contamination from process side. This is to be resolved. Though there is no scale was seen inside the failed tube, reduction of flow due to dislodged scales cannot be ruled out for earlier failures.

Vortex breaker arrangement at mud drum The downcomers are provided with vortex breaker. Vortex breaker is not required as the mud drum is always flooded with water. The vortex breaker causes some pressure loss. The vortex breaker shall be removed. The inlet arrangement shall be modified as per photo 40 in annexure 1. Wrong location of HP dosing arrangement The HP dosing is being done at the deaerator itself. The strainers are being periodically cleaned once it 15 days. This can cause sludge formation of the feed line and in the economiser. The economiser may develop failures. HP chemical is to be dosed only at steam drum. The trisodium phosphate is to be dosed to a level that the pH is maintained at 9 to 9.5 in boiler water. The TSP would form sludge at the mud drum and sometimes at bed coil inlet header. Periodically blow out the sludge from mud drum. It should not be to an extent that the boiler water pH drops below 8.5. The HP dosing pipe shall be internally connected to feed water distributor pipe. See the suggestion in photo 42 in annexure 1. The present chemical dosing and CBD piping arrangement are not proper. See comment in photo 24. Regular analysis of residual phosphate Residual analysis of PO4 is a must. Over dosage also will lead to scaling. PO4 in boiler water shall be 20 -40 ppm subject to boiler water pH is also in the range of 9-10. Low feed water pH & appropriate dosing location The feed water pH is seen to be even 8.5 at times. This has to be around 9. The DM water pH is being boosted only after the transfer pump. This is not OK. The pH at DM plant outlet is < 7. It is advised to shift the pH booster at mixed bed outlet. Source of hardness in return condensate / Make up water The shower water used in plant flash vessel is RO water. This water hardness was found to be 8 ppm as a sample was tested with a test kit. It is advised to check hardness of return condensate & RO water simultaneously on every shift. This should be regularly done so that the cause for water hardness deviation can be identified. 1. The DM plant was inspected to check out the possibility of pumping raw water. The scheme does

not allow raw water pumping. 2. The RO plant was inspected to check out the possibility of pumping raw water to flash tank.

There also the scheme does not allow any bypassing. 3. It was informed by plant engineers that there is no contamination possibility of cooling water to

condensate. They explained that the present system is a closed loop system, in which the temperature is maintained by cooling coils. Only make up is given from RO plant. There is no

steaming taking place in closed loop system. Hence the TDS cannot rise. Yet it is advised to check the chemistry of closed circuit cooling water for contamination from the cooling tower through leaky joints.

No choking of downcomer The downcomer was found to be free from blocks. The downcomers were checked inside the mud drum. See photo 26. The scales present in bank tubes cannot cause restriction for the circulation as there are many tubes available to bring the water from steam drum to water drum. The chronology of tube failures and the load Based on our request the steam consumption load for every month for the year 2012 and 2013 were provided by plant engineers. The boiler was commissioned in May 2011. Till July 2013 no bed tube failures were experienced. It was learnt that the in January 2013 only all the 4 compartments were used as the load went up. The steam consumption data was sent by plant engineer. The same was analysed and our finding is attached in annexure 1. It was seen that in June 2013, the load was the highest. The report does not say about the actual steam generation figure. It is only the whole day consumption and not the peak generation. Yet it can be taken as the measure of the boiler loading. The failures have begun only after steam generation was increased. The failure can be due to starvation only. The circulation calculations were made by us for four cases. The circulation ratio and velocity in various parts are analysed here. A flow diagram is first drawn to indicate the flow paths. The circulation ratio is assumed to start with. The available head due to density difference between water and the water steam mixture in different elements are calculated. The pressure drops in different elements are calculated based on the assumed flow. There are two criterion checked. The pressure drops in parallel circuits have to be the same. The available head and pressure drop should be same for different parallel paths. Iterations are done till the above stated criteria are met with. In this manner four cases were studied by us. They are, Case 1- 24 TPH steam generation with present turbo separators Case 2- 18 TPH steam generation with present turbo separators Case 3- 24 TPH steam generation with baffle separators Case 4- 24 TPH steam generation with additional links from bed outlet header to left side wall. The elemental data were taken from the drawings. The analysis summary of calculations for each case is presented in annexure 3. The comparison made among the four cases is also presented in annexure 3. The findings are, Case 1- bed coil inlet velocity is 0.53 m/s. This is to less as compared to a minimum value of 1

m/s for bed coils of FBC boiler. The local heat flux above coal nozzle in FBC bed coils can be as high as 350 Kw/m2, for imported high VM coal. Due to high heat flux, the steam generation will be more and due to less velocity steam blanketing occurs. It causes intermittent flow. See photo

41. This leads to overheating of the tubes. The bed coil circulation ratio is in the range of 25 – 26. Circulation ratio (CR) is the total flow / steam produced in the particular circuit.

Case 2- bed coil inlet velocity is 0.58 m/s. The circulation ratio in bed coil improves from 25.8 to 37.6. This reduces the risk of phase separation. Due to lower load the tubes had survived since commissioning up to June 2013.

Case 3- bed coil inlet velocity is 0.71 m/s. Since the turbo separators are removed in this case, the common pressure drop due to turbo separator is gone. The circulation velocity is improved. The circulation ratio at bed coil is seen to be 35. It is good improvement over the case 1, where the CR was 25-26.

Case 4- in this case two links are added to carry the steam water mix from bed coil outlet header to left side waterwall. See the arrangement drawing in annexure 4. The detailed layout / production / IBR approval drawing has to be prepared by the boiler maker or the contractor who would do the job. By this modification the CR improves from 35 to 39. The bed coil inlet velocity improves from 0.71 m/s to 0.8 m/s. This modification can be taken up in case the failures are experienced even after the drum internal modifications.

It is recommended to remove the turbo separators immediately. The baffle arrangement recommended during plant visit shall be implemented immediately. The modification suggested during the plant visit is illustrated in sketch in photo 36 of annexure 1. Photos 37 & 38 show the simple drum internal arrangement for 66 kg/cm2 pressure boiler. The tube OD measurement In order to know if there was any other damaged tube or not, it was advised to check the OD of the bed tubes above the coal nozzles. This can be done for every 200 mm from one end to other end at all bottom tubes. The data on OD measurement sent by plant engineer is enclosed in table 3 in annexure 1. It confirms that there is no damage in the other tubes. This leaves a doubt that the particular tube might have failed to partial blockage by foreign material (cotton waste). There is a possibility of loose scales blocking the tube. It can also be due to the improper fit up of the stub in the headers. At any opportunity it is advisable to correct the stub connections. In future the stub connections at headers are not to be disturbed. Only straight tubes are to be replaced inside the refractory walls. The plug detail recommended by Thermax is attached in photo 43 of annexure 1. Removal of scales in the boiler bank tubes and the waterwall The scale can be cleaned by on line chemical. The scale was collected from inside of the boiler bank tubes. This shall be analysed at outside lab. Accordingly the chemical dosage will have to be decided by the chemical supplier. If it is not practical, then off line chemical cleaning is necessary. The loose scales removed from the inlet header shall also be analysed immediately and the results shall be sent to chemical supplier also. For chemical cleaning this data is required.

RECOMMENDATIONS 1. The steam drum internals shall be modified. The turbo separators shall be removed. The inlet

openings in turbo separators shall be blanked. Window openings shall be made in the baffle box at the upper part for steam flow. Canopy shall be provided to direct down the steam flow. The steam shall not enter the steam drier directly. Window openings shall be made at the bottom of the baffle box for water to come out. A sketch was given at the plant explaining this. Same sketch is enclosed in photo 36 of the annexure 1.

2. The sludge inside the header shall be removed. The sludge shall be analysed for chemical contents at outside laboratory such as Vimta lab / SGS lab / Intertek / Shriram testing house.

3. The scale that was removed from bank tubes inside shall be analysed at outside laboratory. Based on this a chemical cleaning is to be decided. There are some on-line chemicals which can be used for chemical cleaning. This shall be discussed with chemical suppliers such as Nalco / Thermax / Ion exchange.

4. The riser arrangement needs modification, if the failures continue, even after the removal of turbo separators. The pressure part arrangement drawing shall be arranged from supplier or from IBR office. As per code the owners are supposed to keep the IBR folder with them after the boiler has put three years of operation. The recommendations are given in annexure 4.

5. The RO water used for flash tank spray shall be regularly analysed for hardness. A few days’ data will tell us about the specification required for softener.

6. Return condensate from process shall be regularly analysed for hardness data. 7. Feed water & boiler water hardness shall be regularly analysed. In order to sludge out the

hardness salts, trisodium phosphate shall be dosed at HP dosing point. The chemical dosing piping shall be modified as per photo 42. It shall be otherwise connected to economiser to steam drum piping. A HP dosing system shall be installed immediately.

8. Any sludge removed from BFP strainer shall be analysed at outside laboratory to know the type of contaminants received from process. This is required to find out the cause of the scaling inside the boiler tubes.

9. At present DM water sent to storage tank is of 6.5 pH. The lines are of MS. It is required to check whether the tank is rubber / epoxy lined or not. It is advised to shift the pH booster to DM plant outlet. It is easy to maintain pH here since the flow is always constant. On line pH meter can be arranged here.

10. Deaerator storage tank needs to be inspected. At present there is no access to the inspection door at the tank. It is advised to install a new door at the accessible place or provide a platform and approach for inspection.

An article on circulation problem is enclosed in annexure 2. The cause for failure remains to be undersized turbo separators in steam drum and the poor distribution arrangement from bed coil outlet header to the waterwall.

K.K.Parthiban

ANNEXURE 1: PHOTOGRAPHS AND COMMENTS

Photo 1: The tubes were removed before our visit. It was informed that the bottom tube failed first. The adjacent mid tube failed due to water jet action from the failed tube. The adjacent bottom tube was removed due to thinning. But there was no failure.

Photo 2: The failed tube can be seen here. There is overheating crack. This can happen both due to starvation and scales. As there are no scales inside, this can be attributed to starvation due to circulation. The failed portion comes above the coal feed point, where the heat flux is more.

First tube to fail by overheating 

2nd tube to fail by impingement 

Photo 3: The total length of the tube is showing the circumferential cracks confirming there is starvation. The tube is seen bulged. This is similar to earlier failures as well.

Photo 4, 5 & 6: All the photographs above show the failed tubes before tube replacement. The failures are similar. All are due to starvation.

Photo 7: The failed tube is seen with overheating signs inside. There is also scale due to starved flow.

Photo 8: The inside appearance of the failed tube before tube replacement. The overheating sign is similar without much of scale. This is case of starvation.

Photo 9 & 10: The inside appearance of the tubes that were damaged due to water impingement can be seen here. The tubes are scale free.

Photo 11: Scales are seen inside the bed coil inlet header.

Photo 12: The scales removed from the bed coil inlet header are seen here. It has both tube oxide scales and the hardness scales.

Photo 13: The bed tubes stubs are inserted haphazardly inside the header. The tubes should have been flush with header inside surface. This can also affect the circulation in some tubes. The stub welding detail given in the IBR drawing was not followed. Starvation in selected tubes can be due this defect. It is necessary to map the failed tubes versus the coal feed point and this defect. But it is practically possible to identify which tube has extra projection.

Photo 14: The above shows the IBR figure in the bed coil assembly drawing. The bed tube is to be in flush with inside surface as per this detail. The contractor who had carried out this work is not an eligible IBR contractor.

Photo 15: The vortex breaker is not required at bed coil downcomers. Mud drum is always flooded with water. This can cause some pressure drop. In order to reduce the pressure drop is advised to install a 300 nb – 200 nb reducer instead for a smooth flow. A wide funnel with 45 deg angle made out of 6 thk plate is also OK. The pipe has to be cut to 50 mm away from the bottom shell surface. A drawing is provided.

Photo 16: The level gauge visibility range is seen to cover the bottom half of the drum. It is advised to maintain the level between the 5th and 6th bolt from bottom. Low water level operation can also be a cause for poor circulation. The operators confirmed that the present water level is between 4th and 5th bolt from bottom.

Photo 17: The steam drum is seen with thick hardness layer at NWL and below.

Photo 18: Thick scale is seen in steam space indicating carryover of water. This can happen due to less number of turbo separators.

Photo 19: Splash marks can be seen above the turbo separators. This is the sign of undersized turbo separators. In low pressure boilers turbo separators are not required.

Photo 20: The bank tubes are seen scaled heavily. The peeled of scales can travel to bed tubes and cause blockages. The scales increase the fuel consumption.

Photo 21 & 22: The turbo separators are seen coated with scales. This type of turbo separators handle less flow and used for high pressure boilers, where circulation ratios are lesser. Otherwise no of turbo separators have to more. It calls for bigger drum.

Photo 23: The scales removed from bank tubes are seen here. This shall be analysed for chemical contents.

Photo 24: The bottom tubes with holes are to be used for HP dosing. It is advisable to connect the dosing line to the feed water pipe inside the steam drum for better mixing of the chemical.

Chemical dosing pipe 

CBD pipe 

Photo 25: The feed water distributor pipe is seen with scales. It is advised to connect the HP chemical dosing line – TSP dosage at the location shown here. The chemical dosing pipe can be internally rerouted inside the drum. It does not need IBR approval.

Photo 26: Both the bed coil downcomers are seen free from any blocks or restrictions. Turbo separators are to be removed as suggested earlier.

Connect HP dosing line 

here.  

Photo 27: Mild distortion can be seen in waterwall.

Photo 28: Some of the boiler log sheets show less feed water pH. The pH can be misguiding as TSP is added in the feed water. Due to this morpholine addition will be less. Feed water pH shall be 9.

  Photo 29: The LP steam is seen to be contaminated on some days. On these days, RO water hardness should have been checked. It is necessary to identify the source of contamination. Ideally the spray water should be DM water only. Once the Cogen boiler is in place, this is a must.

Photo 30: The pH of the DM water shall be boosted at DM plant outlet pipe itself to avoid transportation of corrosion products to boiler.

Photo 31 & 32: While going through the drawings, it was seen that the waterwall roof tubes are with downward loop which can trap loose scales. It is advised to take care not to form scales in the boiler by maintaining nil hardness in feed water and boiler water.

Photo 33: Blow down water hardness is high. This can be controlled by maintaining residual PO4. It is advised to procure necessary water testing instruments.

Photo 34: The hardness is too high in boiler water. Source can be from RO plant spray water or from contamination from cooling water circuit.

Photo 35: The hardness is generally found to be under control during 2012. This is to be investigated further, why in recent times the hardness is high. It is advised to test hardness regularly at condensate return, RO water, feed water and boiler water. Single register is advised for all water parameters so that problem can be identified. Sampling to be done in same period of time.

Photo 36: The above sketch shows the modification suggested for immediate implementation to increase circulation ratio. The turbo separators are to be removed and the openings are to be blanked. Openings are to be provided at top of baffle box with canopy to divert the steam downwards. Similar openings are to be at bottom for returning water from risers.

Photo 37: The above is the internal arrangement in a BHEL boiler of 66 kg/cm2 pressure. There is no baffle box at all. It is simply a baffle plate. There are no turbo separators. Chemical dosing line is close to FW distributor. The CBD is close to baffle plate.

Photo 38: The steam drum here is with baffle box but without any turbo separators. This is also a 66 kg/cm2 boiler. The water side color is not good due to poor water chemistry in this plant.

Photo 39: The DM storage tank is seen with inspection door. But there is no access platform. This is to be inspected annually.

Photo 40: The downcomer stub shall be provided with inlet funnel as shown to reduce the pressure drop at the downcomer. The existing vortex breaker shall be removed.

Flow pattern in horizontally oriented tube

Photo 41: The phases tend to separate due to density difference causing a form of stratified flow to be very common. This makes the heavier water phase to accumulate at the bottom of tube. When the tube is inclined at an angle the pattern the slug / plug flow is common. The common flow patterns in horizontal tubes are illustrated above. At low inlet velocity the bed coil can suffer from stratified flow / intermittent flow.

Photo 42: The above modification is suggested for better distribution of TSP in the boiler water and without directly mixing to the CBD line.

Photo 43: The above is the plugging arrangement used in header tubes. The plugged stubs are not to be exposed to flue gas. The plugs should be away from furnace refractory face by 100 mm and above. The above picture is from Thermax O&M manual.

Photo 44: The above is the effect of proper water chemistry. Though the steel is immersed in water, no rusting will be seen if the deaeration is proper; if the boiler water pH, TDS and hardness are within limits; if the condensate & make up are free from contaminants.

TABLE 1: STEAM GENERATION DATA

MonthTotal steam generation/month 2012

per dayTotal steam generation/month 2013

per day% Increase in load

BED COIL FAILURE MONTH

JAN 3583.40 115.59 4554.73 146.93 27.11FEB 7840.85 252.93 9315.57 300.50 18.81

TABLE 2- STEAM GENERATION REPORT

MAR 10541.63 340.05 10101.98 325.87 -4.17APR 10612.70 353.76 11957.03 398.57 12.67MAY 11584.99 373.71 12962.51 418.15 11.89JUN 10542.37 351.41 13149.27 438.31 24.73

JUL 10273.23 9311.15 Bed coil tube failureAUG 10806.17 11829.05 Bed coil tube failureSEP 11956 05 11256 84SEP 11956.05 11256.84OCT 12120.30 9249.89 Bed coil tube failure

NOV 10906.88 10303.65New bed coil replaced , Economiser tube punctured.

DEC 8109.45 5618.02 624.22 9 days Bed coil tube failureTOTAL 118878.02 119609.69

10000.00

12000.00

14000.00

2000.00

4000.00

6000.00

8000.00year 2012

year 2013

0.00

1 2 3 4 5 6

TABLE 2: CHRNOLOGY OF BED TUBE FAILURES

No Month Description FROM TO

1 July In 4th compartment (2,3,4,5) four bed coils tubes got punctured and plugging done.. 15.7.2013 16.7.2013

2 JulyIn 4th compartment 1 tube got punctured and 3 tubes were found in bulged condition. All the four bed coil tubes removed (6,7,9,10) and plugging done.

21.7.2013 22.7.2013

3 July In 2nd compartment tube number 15 got punctured, it was removed and plugging done. 26.7.2013 27.7.2013

4 August In 2nd compartment, tube number 15 & 17 got punctured and both the tubes were plugged. 5.8.2013 7.8.2013

5 AugustIn 2nd compartment 18th tube middle and bottom tube got punctured and three tubes found in bended condition. All the 5 tubes were plugged.

29.8.2013 30.8.2013

6 October In 3 rd compartment tube no 26,28 got punctured, both tubes were removed and plugged. 11.10.2013 12.10.2013

7 October In 2nd compartment tube no 21,22,23(middle),24 (bottom) got punctured. All the 4 tubes were removed and plugged.. 21.10.2013 22.10.2013

8 November Economiser tube punctured at the bend. All bed coils replaced this time. 26.11.2013 26.11.2013

9 DecemberIn 2nd comparment tube no 24 (bottom side) and 23(middle tube) got punctured. For attending the plugging work in 23rd middle tube, bottom tube of the same has been removed and plugged.

11.12.2013 11.12.2013

CHRONOLOGY OF TUBE FAILURES- APOLLO TYRES

TABLE 3: BED TUBE OD MEASUREMENT

Compartment no Tube no Left middle Right compartment no Tube no Left middle Right1 50.5 50.5 50.5 29 50.5 50.5 50.52 50.5 50.5 50.5 30 50.5 50.5 50.53 50.5 50.5 50.5 31 50.5 50.5 50.54 50 5 50 5 50 5 32 50 5 50 5 50 5

TABLE 3- BED COILTUBE (OD) in mm - only BOTTOM TUBES- AS VIEWED FROM FRONT

4 50.5 50.5 50.5 32 50.5 50.5 50.55 50.5 50.5 50.5 33 50.5 50.5 50.56 50.5 50.5 50.5 34 50.5 50.5 50.57 50.5 50.5 50.5 35 50.5 50.5 50.58 50.5 50.5 50.5 36 50.5 50.5 50.59 50.5 50.5 50.5 37 50.5 50.5 50.5

10 50 5 50 5 50 5 38 50 5 50 5 50 5

Compartment -3Compartment -1

10 50.5 50.5 50.5 38 50.5 50.5 50.511 50.5 50.5 50.5 39 50.5 50.5 50.512 50.5 50.5 50.5 40 50.5 50.5 50.513 50.5 50.5 50.5 41 50.5 50.5 50.514 50.5 50.5 50.5 42 50.5 50.5 50.515 50.5 50.5 50.5 43 50.5 50.5 50.516 50 5 50 5 50 5 44 50 5 50 5 50 516 50.5 50.5 50.5 44 50.5 50.5 50.517 50.5 50.5 50.5 45 50.5 50.5 50.518 50.5 50.5 50.5 46 50.5 50.5 50.519 50.5 50.5 50.5 47 50.5 50.5 50.520 50.5 50.5 50.5 48 50.5 50.5 50.521 50.5 50.5 50.5 49 50.5 50.5 50.522 50 5 50 5 50 5 50 50 5 50 5 50 5

Compartment -4Compartment -222 50.5 50.5 50.5 50 50.5 50.5 50.523 51 50.5 50.5 50.524 52 50.5 50.5 50.525 50.5 50.5 50.5 53 50.5 50.5 50.526 50.5 50.5 50.5 54 50.5 50.5 50.527 50.5 50.5 50.5 55 50.5 50.5 50.528 50.5 50.5 50.5 56 50.5 50.5 50.5

Tube replacedTube replaced

8 50 5 50 5 50 5 56 50 5 50 5 50 5

ANNEXURE 2: TECHNICAL ARTICLE ON CIRCULATION

Natural Circulation in Boilers Abstract This article is focused towards the author’s experience in the design and trouble shooting of Boilers related to the principle of natural circulation. Inadequate circulation causes tube failures. Poor circulation in a boiler may be due to design defect or improper boiler operation. In this paper the factors affecting the circulation are summarized. Further case studies are presented. Principle of Natural Circulation

HEAT INPUT

STEAM DRUM

DOWNCOMER

TOFURNACE TUBES

FIG 1. FLOW DUE TO DENSITY DIFFERENCE

Boiling mechanism There are two regimes of boiling mechanisms, namely, the nucleate boiling and the film boiling. Nucleate boiling is formation and release of steam bubbles at the tube surface, with water still wetting the surface immediately. Since the tube surface temperature is closer to saturation temperature the tube is always safe against failure.

Boilers are designed with Economiser, Evaporator and superheater depending on the Design parameters. Economisers add sensible heat to water. The economiser water outlet temperature will be closer to saturation temperature. The water is forced through the economiser by the boiler feed pumps. Superheaters add heat to steam. That is the heat is added to steam leaving the Boiler steam drum / Boiler shell. The steam passes through the superheater tubes by virtue of the boiler operating pressure. Evaporators may be multi tubular shell, Waterwall tubes, Boiler bank tubes or Bed coils as in FBC boiler. In evaporators the latent heat is added. The addition of heat is done at boiling temperature. The Flow of water through the evaporator is not by the pump but by the fact called thermo siphon. The density of the water, saturated or sub-cooled is higher as compared the water steam mixture in the heated evaporator tubes. The circulation is absent once the boiler firing is stopped.

Film boiling is the formation of steam film at the tube surface, in which the metal temperature rises sharply. This leads to instantaneous or long term overheating of tubes & failures. Film boiling begins due to high heat flux or low velocity or inclined tubes. Circulation Ratio / Number The flow of water through a circuit should be more than the steam generated in order to protect the tube from overheating. The Boiler tubes, its feeding downcomer pipes, relief tubes / pipes are arranged in such a way that a desired flow is obtained to safeguard the tubes. The ratio of the actual mass flow through the circuit to the steam generated is called circulation ratio.

CIRCUIT THE IN GENERATED STEAM

CIRCUIT THE THROFLOW TOTAL

RATIO NCIRCULATIO

Depending the Boiler Design parameters, configuration of the boiler this number would be anywhere between 5 & 60. In low pressure boilers, this number is on the higher side as the density difference between water & steam is high. What if the circulation ratio is less than that required minimum? Tube deformation / leakage failures / tube to fin weld failures take place. The failure mode varies depending upon the flow, heat input, tube size, boiler configuration, water quality.

Wrinkles seen in tubes Bulging of tubes Wrinkle formation & subsequent circular crack Heavy water side scaling inside tubes. Corrosion of tubes Prolonged overheating & irregular cracks on tubes Sagging of tubes if orientation is horizontal / inclined Tube to fin weld crack

See figure 2 for the illustrations. Factors which affect Circulation

No of downcomers, diameter , thickness, layout No of downcomers are selected depending upon the heat duty of each section of evaporator tubes. Depending on the length of the distributing header, more downcomers would be necessary to avoid flow unbalance. It is desirable to keep the bends, branches to a minimum so that the pressure drop is less. The selection of downcomers is so done to keep the velocity less than 3 m/s.

wrinkles seen in tubes Caustic gouging

Cracks on tubeBulging of tubes

Circumferential cracks in tubes Heavy scaling in tubes

Tube sagging Fin cracking

FIGURE 2. ILLUSTRATION SHOWING TUBE FAILURES

Heated down comers In some boilers the downcomers are subject to heat transfer, for e.g. rear section of boiler bank in Bi drum boilers. The circulation pattern in these boiler evaporator tubes is a function of heat transfer. In case of heated downcomers, burning of tubes may take place if the design is defective. There could be stagnation of water in some tubes depending on the heat pick up. Downcomer location & entry arrangement inside the drum Depending on the Boiler configuration downcomers may be directly connected to steam drum or else to mud drum. One should ensure that the entry of sub-cooled water is smooth into the downcomer. A down comer directly connected to steam drum is vulnerable to steam bubble entry into the downcomer. In such a case the circulation is affected. Instead of using big pipes, more no of smaller diameter pipe would avoid this. Vortex breaker would be necessary to avoid steam entry into the downcomer pipe. In case a set of bank tubes are used for taking water to mud drum, One should ensure that the steam does not enter these tubes during water level fluctuation. Proper baffle plates would be necessary to avoid mix up of steam water mixture from risers section to downcomer section. Downcomers taken from mud drum are very safe. An obstruction in front of downcomer can cause the poor circulation in evaporator tubes. Arrangement of evaporator tubes The circulation in each evaporator tube is dependent on how much it receives heat. If there is non-uniform heating among evaporator tubes, One can expect non-uniform flow. At times even flow reversal can take place. In some situations the water may become stagnated leading to water with high TDS or high pH. Localized corrosion of tubes would occur. Improper operation of boiler Depending upon the boiler capacity there may be number of burners / compartments in a boiler. This is required in order to achieve the boiler turn down in an efficient way. In FBC boilers no of compartments are provided for turn down. Operating only certain compartments all the time would cause stagnation of water in unheated section of bed coils. The concentration dissolved solids, pH could be far different from the bulk water chemistry. This leads to corrosion of boiler tubes. Similarly, operating same burner would heat the evaporator tubes in non-uniform way leading to different water chemistry in unheated section of furnace tubes.

Feed pump operation In low-pressure boilers, (pressures below 21 kg/cm2 g), the feed pump on /off operation is usually linked to level switches in the steam drum. When the pump is in off mode, it is likely that the steam bubbles would enter the downcomer tubes and cause loss of circulation. Arrangement of evaporative sections and the interconnection between sections In certain configuration of boilers it is possible to obtain better circulation by interconnecting a well-heated evaporator sections to poorly heated evaporator section. It would be necessary to separate the poorly heated section if it lies in parallel to well heated section. The downcomers & risers are to be arranged separately so that the reliable circulation can be ensured. This principle is called sectionalizing for reliable circulation. The inlet headers / outlet headers shall be partitioned for this purpose. However, it is desirable to arrange the evaporative surface in such a way that heat flux & heat duties in various circuits are more or less same. If tubes are inclined close to horizontal, the steam separation would take place leading to overheating of tubes. No of risers , pipe Inside diameter, bends, branches No of risers are so selected that the velocity inside the pipes would be 5 – 6 m/s. The no of risers are selected in such a way the flow unbalance is minimum. It is preferable to adopt long radius bends to keep the pressure drop to minimum. The no off bends, branches should be kept as minimum possible as these elements contribute for high-pressure drop. Arrangement of risers in the drum The risers are arranged in such a way that the pressure drop is minimum. The baffles are spaced apart to keep the obstruction to flow is minimum. Instead of terminating the risers below the water level in the drum, it would be better to terminate above water level in the steam drum as it allow free entry. Feed distributor inside the steam drum Feed distributor shall be arranged in such way that the sub-cooled water enters the downcomer section. This will ensure that the good hydrostatic head is available for circulation. Drum Internals arrangement Drum internals such as baffles, cyclone separator also form part of the natural circulation circuit. The baffles are arranged in such a way the steam would rise easily to the steam space without much resistance. High-pressure drop in the drum internals will retard the flow through evaporator tubes.

Slagging of furnace tubes The design of the furnace shall be in such a way that the Slagging of the fuel ash is avoided. Slagging retards the heat transfer to tubes and thus the driving force for circulation will come down. At locations where the tubes are clean, this would lead to overheating of tubes. If unavoidable, soot blowers shall be so arranged that the uniform heat flux to evaporative sections be not hindered. Critical heat flux, Allowable steam quality, recommended fluid velocity In the design of furnace, the heat flux should not be higher that a limit beyond which the tube will burn. Several correlations are available on this. In a circuit the steam produced divided by the mass flow would be the quality of steam produced in the circuit. The allowable steam quality has been found be dependent on the heat flux, mass velocity and the steam pressure. Even after ensuring that the heat flux and steam quality are safe, the entry velocity is important to avoid departure from nucleate boiling. For vertical rising circuit the velocity is in the range of 0.3 m/s to 1.5 m/s. for inclined circuit the velocity shall be in the range of 1.54 m/s to 3 m/s. Analyzing for boiler water circulation In a circuit, the circulation takes place due to difference in density between the cold water in the downcomer circuit and the density of steam water mixture in the evaporator tube. The flow will increase as the heat input is more and the density of water steam mixture decreases in the evaporative circuit. But pressure loss in a circuit rises as the flow increases. Hence there will be appoint of balancing at which time the pressure loss is equal to the head. In order to improve / retard the flow, the circuit may be rearranged duly considering the above discussed factors. Using MSEXCEL, practically any circuit can be analyzed for the circulation. Conclusion The design of the boiler is not necessarily such a mere calculation of Heat transfer surfaces. It is much beyond that. One such subject of importance is undoubtedly the circulation.

CASE 1

BAFFLE

FEED DISTRIBUTOR

BLOW DOWN STUB

STEAM DRUM

CASE 2

FLOW OBSTRUCTION

The bottom rows of the bank tubes of this cross tube boiler were sagging. There were no drum internals. Feed distributor was added to improve the circulation. Further in order to have saturated water into the downcomer baffles were added in the steam drum to promote circulation. The blow down stub was very close to the bottom row of tubes. Continuous blow down was recommended so that loss of circulation could be averted.

In this case, the water wall & bed coils were failing after bulging & overheating. Thick rough edge cracks were observed wherever the failure took place. There were several locations at which the failures had taken place. There was severe scaling in the boiler. Hence the water quality was suspected for a long time. By removing the flue tube immediate to the downcomer, the failure stopped. Similar failures were noted when there was lot of accumulation inside the headers due to improper post cleaning operation after a chemical cleaning of the boiler.

CASE 3

DOWNCOMER

RISER

FEED NOZZLE

This boiler was converted for fluidized bed firing. There were wrinkle formations in bed coil tubes. It was felt that the Downcomer & risers were inadequate and several modifications were done in order to reduce the pressure drop in the circuit. Still the failures continued. Suspecting boiler expansion problem, the refractory work was reconstructed with adequate provision for expansion. Yet the failures continued. The two drums were provided with feed nozzles at dished ends with separate non return valves. It was noticed that the feed water was not going into one of the drums, as the NRV was defective. It is possible that flow reversal was taking place in the downcomer in the drum where the NRV was not functioning. The NRV at each steam drum inlet was removed and a common NRV was provided in the feed line. Also a feed distributor was added in each drum to distribute the water to downcomer area. This way the flow reversal in the downcomer was eliminated and the failures stopped.

CASE 4

The boiler was provided with heated downcomers. There were no baffles inside the drum to separate the steam water mixture from down comer section. When the load in the boiler increased beyond a point the downcomers started bursting. This proved the possibility of steam water mixture entering the downcomers. Boiler drum internals with cyclone separators were added.

CASE 5

RISER

DOWNCOMER

The illustration shows a boiler converted for FBC firing. In this boiler vibration of riser tubes was experienced. Even after a snubber support was provided, the vibration continued. The circulation calculation showed a velocity of 7 m/s in riser tubes. The vibration problem vanished after one of the risers was removed. The velocity in the riser was then estimated to be less than 6 m/s.

CASE 6

CORROSION FAILURE DUE TO CAUSTIC

TOP OF TUBE IDLE COMPARTMENT

The above is a Fluidized bed combustion boiler with three compartments. A pin hole failure

was reported in the 12 o clock position of the bed coil tube. On cutting the tubes, the inside was found have gouging mark for the throughout the inclined portion of the tube. Several adjacent tubes are inspected with D meter. Four adjacent tubes showed less thickness at 12o-clock position. The tubes were cut inspected and these tubes were also found to have the same marks as the leaked tube. On suspicion the symmetrical tubes about the boiler axis ware also checked with D meter. The tubes were found to have similar gouging attack. The boiler water log sheets since commissioning were analyzed and found the water chemistry had deviated in the past three months. The boiler was operated on pH of 11, resulting in free hydroxide. The water inside the idle compartment was stagnant, as the compartment was kept idle. Caustic attack had been the cause of failure. Customer was advised for alternate activation of compartments so that the circulation in all tubes would be good. The above case is clearly a circulation-related failure due to operational defects.

ANNEXURE 3: CIRCULATION ANALYSIS REPORTS & SUMMARY

ELEMENTAL DATADOWNCOMERSElement data BB DC01 DC02Tube/pipe OD mm 51 219.1 219.1thk mm 3.66 6.35 6.35ID mm 43.68 206.4 206.4ID inch 1.719685 8.125984 8.125984flow area m2 0.001499 0.033472 0.033472flow area ft2 0.016136 0.360291 0.360291No of parallel paths no 250 1 1Elevation data1-Up/2-down/3-Hori 2 2 2distance metre 4.5 2 2distance ft 14.76378 6.56168 6.56168Flow resistances datalength metre 4.76 10.2775 4.297entry no 20 1 1 1exit no 40 1 0 0squeeze bend no 75 0 0 0180 bend no 50 0 0 090 short rad bend (R<3d) no 32 0 2 190 std radius ( r = 3d) no 26 0 0 090 long rad bend ( R>3d) no 20 0 0 045 short rad bend ( r<3d) no 15 2 2 245 long rad bend ( R >3d) no 12 0 0 0reducer no 120 0 0 0expander no 100 0 0 0Tee - entrering run no 60 0 1 0Tee- entering branch no 90 0 0 1Tot. equiv. Length m 8.6912 46.1911 39.7978Tot. equiv. Length ft 28.51444 151.5456 130.5702Heat transfer dataHeated or not 1/2 2 2 2

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evaporative circuits Element data BET 01 BET O2 BET 03 FWP RWP LSWP RSWPTube/pipe OD mm 51 51 51 51 51 51 51thk mm 6.35 6.35 6.35 3.66 3.66 3.66 3.66ID mm 38.3 38.3 38.3 43.68 43.68 43.68 43.680ID inch 1.508 1.508 1.508 1.719685 1.720 1.720 1.720flow area m2 0.00115 0.00115 0.00115 0.00150 0.00150 0.00150 0.00150flow area ft2 0.01241 0.01241 0.01241 0.01614 0.01614 0.01614 0.01614No of parallel paths no 56 56 56 27 27 65 65Elevation data 1-Up/2-down/3-Hori 1 1 1 1 1 1 1distance metre 0.931 0.931 0.931 4.5 4.5 4.5 4.5distance ft 3.054 3.054 3.054 14.764 14.764 14.764 14.764Flow resistances datalength metre 3.429 3.296 3.429 9.942 5.44 16.383 16.383entry no 20 1 1 1 1 1 1 1exit no 40 1 1 1 1 1 1 1squeeze bend no 75 0 0 0 0 0 0 0180 bend no 50 0 0 0 0 0 0 090 short rad bend (R<3d) no 32 1 0 1 1 1 0 090 std radius ( r = 3d) no 26 0 0 0 0 0 0 090 long rad bend ( R>3d) no 20 0 0 0 0 0 0 045 short rad bend ( r<3d) no 15 0 2 0 0 2 0 045 long rad bend ( R >3d) no 12 0 0 0 0 0 0 0reducer no 120 0 0 0 0 0 0 0expander no 100 0 0 0 0 0 0 0Tee - entrering run no 60 0 0 0 0 0 0 0Tee- entering branch no 90 0 0 0 0 0 0 0Tot. equiv. Length m 6.9526 6.743 6.9526 13.96056 10.76896 19.0038 19.0038Tot. equiv. Length ft 22.81037 22.1227 22.81037 45.80236 35.33123 62.348427 62.348427Heat transfer dataHeated or not 1/2 1 1 1 1 1 1 1

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links, riser tubes Riser tubes Riser tubes Element data LK01 LK02-05 LK06 LK07 LK08 LK09 LK10 RSWRT01 RSWRT02 RSWRT03 RSWRT04 RSWRT05 RSWRT06 LSWRT01 LSWRT02 LSWRT03 LSWRT04 LSWRT05 LSWRT06 FRRTTube/pipe OD mm 168.3 168.3 168.3 219.1 219.1 168.3 168.3 101.6 101.6 101.6 101.6 101.6 101.6 101.6 101.6 101.6 101.6 101.6 101.6 51thk mm 7.1 7.1 7.1 10.97 10.97 7.1 7.1 5.74 5.74 5.74 5.74 5.74 5.74 5.74 5.74 5.74 5.74 5.74 5.74 4ID mm 154.1 154.1 154.1 197.16 197.16 154.1 154.1 90.12 90.12 90.12 90.12 90.12 90.12 90.12 90.12 90.12 90.12 90.12 90.12 43ID inch 6.06614 6.06614 6.06693 7.76220 7.76220 6.06693 6.06693 3.54803 3.54803 3.54803 3.54803 3.54803 3.54803 3.54803 3.54803 3.54803 3.54803 3.54803 3.54803 1.69291flow area m2 0.01865 0.01865 0.01866 0.03054 0.03054 0.01866 0.01866 0.00638 0.00638 0.00638 0.00638 0.00638 0.00638 0.00638 0.00638 0.00638 0.00638 0.00638 0.00638 0.00145flow area ft2 0.20078 0.20078 0.20084 0.32875 0.32875 0.20084 0.20084 0.06869 0.06869 0.06869 0.06869 0.06869 0.06869 0.06869 0.06869 0.06869 0.06869 0.06869 0.06869 0.01564No of parallel paths no 1.0 4.0 1.0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 27Elevation data 1-Up/2-down/3-Hori 1.0 1.0 1.0 3 3 1 1 3 3 3 3 3 3 3 3 3 3 3 3 3distance metre 0.9 0.9 0.9 0 0 1.069 1.069 0 0 0 0 0 0 0 0 0 0 0 0 0distance ft 3.0 3.0 3.0 0 0 3.507218 3.507218 0 0 0 0 0 0 0 0 0 0 0 0 0Flow resistances datalength metre 1.8 0.9 1.8 3.88 3.88 7.06 7.06 7.84 6.85 5.73 4.64 3.60 2.68 7.84 6.85 5.73 4.64 3.60 2.68 0.3entry no 20 1.0 1.0 1.0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1exit no 40 0.0 0.0 0.0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1squeeze bend no 75 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0180 bend no 50 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 090 short rad bend (R<3d) no 32 0.0 0.0 0.0 0 0 3 3 1 1 1 1 1 1 1 1 1 1 1 1 090 std radius ( r = 3d) no 26 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 090 long rad bend ( R>3d) no 20 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 045 short rad bend ( r<3d) no 15 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 045 long rad bend ( R >3d) no 12 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0reducer no 120 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0expander no 100 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Tee - entrering run no 60 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Tee- entering branch no 90 1.0 1.0 1.0 1 1 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0Tot. equiv. Length m 18.7 17.8 18.7 21.6204 21.6244 49.5886 49.5916 16.12904 15.14104 14.02104 12.93104 11.88704 10.97104 16.12904 15.14104 14.02104 12.93104 11.88704 10.97104 2.88Tot. equiv. Length ft 61.5 58.6 61.5 70.93307 70.9462 162.69226 162.7021 52.9168 49.67533 46.000789 42.42467327 38.9994763 35.99422687 52.9167996 49.67533 46.0007889 42.4246733 38.99947631 35.99423 9.4488192Heat transfer dataHeated or not 1/2 2.0 2.0 2.0 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

kg/h m2 kg/hOverall steam production 24000 DC water sp vol m3/kg 0.00117 Turboseparator vel 16.2 m/s Bed coil generation 12185 FWP 26.1 1326.3

Overall CR 13.16 steam sp vol m3/kg 0.10410 Specific volume 0.0084378 m3/kg Boiler bank generation 7184 RWP 14.29 726.2Pr drop at turbo sep 1592.5 kg/m2 Waterwall generation 4630 SWP 50.72 2577.5

ANALYSIS tot. flow flow/path in.sp.vol Steaming steam out sp vol mean.sp.vol ele.pr.drop Ele Pr drop ele .head abs head mass inlet velocitykg/h kg/s m3/kg kg/h fraction m3/kg m3/kg kg/cm2 kg/m2 kg/m2/sec m/s

BB 315898.3 0.350998 0.00117 0.00117 0.00117 0.00132 13.20 3846.15 3846.15 234.14 0.270.48 DC01 151592.5 42.10902 0.00117 0.00117 0.00117 0.02639 263.93 1709.40 1709.40 1258.03 1.470.52 DC02 164305.8 45.6405 0.00117 0.00117 0.00117 0.02639 263.93 1709.40 1709.40 1363.54 1.600.331 BET01 104718.6 0.51944 0.00117 4061.67 0.03879 0.00516 0.00269 82.66 0.01190 201.67 346.16 -346.16 450.68 0.530.337 BET02 106311.9 0.52734 0.00117 4061.67 0.03821 0.00510 0.00267 83.92 0.01181 202.03 348.66 -348.66 457.54 0.54

0.332 BET03 104867.8 0.52018 0.00117 4061.67 0.03873 0.00516 0.00269 82.78 0.01193 202.05 346.39 -346.39 451.33 0.530 261165 LK01 82501 58 22 91711 0 00516 12185 00 0 03857 0 00514 0 00515 0 11344 1134 43 175 09 -175 09 1228 58 6 34

CASE 1: 24 TPH WITH SIX TURBO SEPARATORS

Acceleration loss

0.261165 LK01 82501.58 22.91711 0.00516 12185.00 0.03857 0.00514 0.00515 0.11344 1134.43 175.09 175.09 1228.58 6.340.259879 LK06 82095.47 22.8043 0.00516 0.00514 0.00515 0.11227 1122.70 175.09 -175.09 1222.21 6.31

LK02-LK05 151301.2 10.50703 0.00516 0.00514 0.00515 0.02272 227.22 175.09 -175.09 563.28 2.910.623426 LK07 51433.6 14.28712 0.00516 0.00514 0.00515 0.01483 148.34 0.00 0.00 467.78 2.410.650768 LK08 53425.1 14.84031 0.00516 0.00514 0.00515 0.01601 160.08 0.00 0.00 485.89 2.51

0.377 FWP 31067.9 0.31963 0.00515 1326.34 0.08126 0.00953 0.00712 20.31 0.01241 144.46 632.07 -632.07 213.21 1.10 RSWP 151301.2 0.64659 0.00515 1288.74 0.04709 0.00602 0.00557 16.42 0.05413 557.75 807.47 -807.47 431.32 2.22

LSWP 104858.8 0.44811 0.00515 1288.74 0.05086 0.00641 0.00576 11.42 0.02685 279.95 781.86 -781.86 298.92 1.540.349 RWP 28670.4 0.29496 0.00515 726.18 0.06390 0.00775 0.00636 10.25 0.00729 83.11 707.41 -707.41 196.76 1.01

FRRT01 59738.3 0.614591 0.07293 0.07293 0.07293 0.10491 2641.68 0.00 0.00 423.04 30.850.151542 RSWRT01 22928.52 6.369032 0.00641 0.00641 0.00641 0.13705 2963.06 0.00 0.00 998.08 6.390.156408 RSWRT02 23664.77 6.574 0.00641 0.00641 0.00641 0.13705 2963.06 0.00 0.00 1030.13 6.600.162535 RSWRT03 24591.79 6.831 0.00641 0.00641 0.00641 0.13705 2963.06 0.00 0.00 1070.48 6.860.169247 RSWRT04 25607.28 7.113 0.00641 0.00641 0.00641 0.13705 2963.06 0.00 0.00 1114.69 7.140.176523 RSWRT05 26708.12 7.419 0.00641 0.00641 0.00641 0.13705 2963.06 0.00 0.00 1162.61 7.450 183744 RSWRT06 27800 74 7 722 0 00641 0 00641 0 00641 0 13705 2963 06 0 00 0 00 1210 17 7 750.183744 RSWRT06 27800.74 7.722 0.00641 0.00641 0.00641 0.13705 2963.06 0.00 0.00 1210.17 7.750.151542 LSWRT01 15890.5 4.414 0.00602 0.00602 0.00602 0.06184 2210.92 0.00 0.00 691.72 4.160.156408 LSWRT02 16400.8 4.556 0.00602 0.00602 0.00602 0.06184 2210.92 0.00 0.00 713.93 4.300.162535 LSWRT03 17043.2 4.734 0.00602 0.00602 0.00602 0.06184 2210.92 0.00 0.00 741.90 4.460.169247 LSWRT04 17747.0 4.930 0.00602 0.00602 0.00602 0.06184 2210.92 0.00 0.00 772.53 4.650.176523 LSWRT05 18510.0 5.142 0.00602 0.00602 0.00602 0.06184 2210.92 0.00 0.00 805.74 4.850.183744 LSWRT06 19267.2 5.352 0.00602 0.00602 0.00602 0.06184 2210.92 0.00 0.00 838.70 5.05

Circulation ratio Matching Available Head and Pressure DropHEAD DELTA P

BET 01 25.8 BB DC01 BET01 LK02-LK05 RSWP RSWRT01 4226.84 4226.84 1.00BET 02 26.2 BB DC02 BET02 LK01 FWP FRRT01 4399.73 4399.74 1.00BET 03 25.8 BB DC01 BET03 LK06 RWP FRRT01 4326.67 4326.67 1.00 BB DC01 BET01 LK01 LK07 LSWP LSWRT01 4252.46 4252.45 1.00

BB DC01 BET01 LK06 LK08 LSWP LSWRT02 4252.46 4252.45 1.00

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kg/h m2 kg/hOverall steam production 18000 DC water sp vol m3/kg 0.00117 Turboseparator vel 13.2 m/s Bed coil generation 9138.75 FWP 26.1 994.8

Overall CR 19.2 steam sp vol m3/kg 0.10410 Specific volume 0.0062638 m3/kg Boiler bank generation 5388 RWP 14.29 544.6Pr drop at turbo sep 1416.0 kg/m2 Waterwall generation 3472.5 SWP 50.72 1933.1

ANALYSIS tot. flow flow/path in.sp.vol Steaming steam out sp vol mean.sp.vol ele.pr.drop Ele Pr drop ele .head abs head mass inlet velocitykg/h kg/s m3/kg kg/h fraction m3/kg m3/kg kg/cm2 kg/m2 kg/m2/sec m/s

BB 345726.8 0.384141 0.00117 0.00117 0.00117 0.00156 15.60 3846.15 3846.15 256.25 0.300.48 DC01 165906.5 46.08515 0.00117 0.00117 0.00117 0.03119 311.88 1709.40 1709.40 1376.82 1.610.52 DC02 179820.3 49.95008 0.00117 0.00117 0.00117 0.03119 311.88 1709.40 1709.40 1492.29 1.750.331 BET01 114606.6 0.56849 0.00117 3046.25 0.02658 0.00391 0.00227 67.85 0.01203 188.14 410.22 -410.22 493.24 0.580.337 BET02 116350.3 0.57713 0.00117 3046.25 0.02618 0.00386 0.00226 68.88 0.01195 188.36 412.81 -412.81 500.74 0.590.332 BET03 114769.9 0.56930 0.00117 3046.25 0.02654 0.00390 0.00227 67.95 0.01206 188.51 410.46 -410.46 493.94 0.58

0.26291 LK01 90894.96 25.2486 0.00391 9138.75 0.02643 0.00389 0.00390 0.10421 1042.07 231.32 -231.32 1353.57 5.290 260801 LK06 90166 02 25 04612 0 00391 0 00389 0 00390 0 10249 1024 88 231 32 231 32 1342 36 5 24

Acceleration loss

CASE 2: 18 TPH LOAD WITH SIX TURBO SEPARATORS

0.260801 LK06 90166.02 25.04612 0.00391 0.00389 0.00390 0.10249 1024.88 231.32 -231.32 1342.36 5.24 LK02-LK05 164665.8 11.43513 0.00391 0.00389 0.00390 0.02037 203.67 231.32 -231.32 613.03 2.390.599144 LK07 54459.2 15.12755 0.00391 0.00389 0.00390 0.01259 125.86 0.00 0.00 495.30 1.930.643911 LK08 58058.9 16.12748 0.00391 0.00389 0.00390 0.01431 143.07 0.00 0.00 528.04 2.06

0.401 FWP 36435.8 0.37485 0.00390 994.76 0.05374 0.00670 0.00517 17.86 0.01241 141.95 869.78 -869.78 250.05 0.97 RSWP 164665.8 0.70370 0.00390 966.55 0.03230 0.00449 0.00419 13.40 0.04820 495.43 1074.09 -1074.09 469.42 1.83

LSWP 112518.1 0.48085 0.00390 966.55 0.03502 0.00477 0.00432 9.19 0.02322 241.36 1041.22 -1041.22 320.76 1.250.356 RWP 32107.1 0.33032 0.00390 544.64 0.04340 0.00564 0.00471 8.60 0.00677 76.33 954.55 -954.55 220.35 0.86

FRRT01 68542.9 0.705174 0.04889 0.04889 0.04889 0.09259 2341.95 0.00 0.00 485.39 23.730.151542 RSWRT01 24953.82 6.931617 0.00477 0.00477 0.00477 0.12102 2626.17 0.00 0.00 1086.24 5.190.156408 RSWRT02 25755.11 7.154 0.00477 0.00477 0.00477 0.12102 2626.17 0.00 0.00 1121.12 5.350.162535 RSWRT03 26764.01 7.434 0.00477 0.00477 0.00477 0.12102 2626.17 0.00 0.00 1165.04 5.560.169247 RSWRT04 27869.2 7.741 0.00477 0.00477 0.00477 0.12102 2626.17 0.00 0.00 1213.15 5.790.176523 RSWRT05 29067.28 8.074 0.00477 0.00477 0.00477 0.12102 2626.17 0.00 0.00 1265.30 6.040.183744 RSWRT06 30256.41 8.405 0.00477 0.00477 0.00477 0.12102 2626.17 0.00 0.00 1317.07 6.290.151542 LSWRT01 17051.2 4.736 0.00449 0.00449 0.00449 0.05319 1947.92 0.00 0.00 742.24 3.340.151542 LSWRT01 17051.2 4.736 0.00449 0.00449 0.00449 0.05319 1947.92 0.00 0.00 742.24 3.340.156408 LSWRT02 17598.8 4.889 0.00449 0.00449 0.00449 0.05319 1947.92 0.00 0.00 766.08 3.440.162535 LSWRT03 18288.2 5.080 0.00449 0.00449 0.00449 0.05319 1947.92 0.00 0.00 796.09 3.580.169247 LSWRT04 19043.4 5.290 0.00449 0.00449 0.00449 0.05319 1947.92 0.00 0.00 828.96 3.730.176523 LSWRT05 19862.0 5.517 0.00449 0.00449 0.00449 0.05319 1947.92 0.00 0.00 864.60 3.890.183744 LSWRT06 20674.6 5.743 0.00449 0.00449 0.00449 0.05319 1947.92 0.00 0.00 899.97 4.05

Circulation ratio Matching Available Head and Pressure DropHEAD DELTA P

BET 01 37.6 BB DC01 BET01 LK02-LK05 RSWP RSWRT01 3839.93 3840.89 1.00BET 02 38.2 BB DC02 BET02 LK01 FWP FRRT01 4041.65 4041.82 1.00BET 03 37.7 BB DC01 BET03 LK06 RWP FRRT01 3959.23 3959.14 1.00

BB DC01 BET01 LK01 LK07 LSWP LSWRT01 3872.80 3872.83 1.00BB DC01 BET01 LK06 LK08 LSWP LSWRT02 3872.80 3872.86 1.00

Sh 1 of 1

kg/h m2 kg/hOverall steam production 24000 DC water sp vol m3/kg 0.00117 Bed coil generation 12185 FWP 26.1 1326.3Overall CR 17.8 steam sp vol m3/kg 0.10410 baffle sep press drop 25.00 kg/m2 Boiler bank generation 7184 RWP 14.29 726.2

Waterwall generation 4630 SWP 50.72 2577.5ANALYSIS

tot. flow flow/path in.sp.vol Steaming steam out sp vol mean.sp.vol ele.pr.drop Ele Pr drop ele .head abs head mass inlet velocitykg/h kg/s m3/kg kg/h fraction m3/kg m3/kg kg/cm2 kg/m2 kg/m2/sec m/s

BB 427057.2 0.474508 0.00117 0.00117 0.00117 0.00231 23.06 3846.15 3846.15 316.53 0.370.48 DC01 204935.2 56.92644 0.00117 0.00117 0.00117 0.04610 461.03 1709.40 1709.40 1700.71 1.990.52 DC02 222122.1 61.70057 0.00117 0.00117 0.00117 0.04610 461.03 1709.40 1709.40 1843.34 2.160.331 BET01 141567.2 0.70222 0.00117 4061.67 0.02869 0.00412 0.00234 111.75 0.01896 301.35 397.10 -397.10 609.27 0.710.337 BET02 143721.1 0.71290 0.00117 4061.67 0.02826 0.00408 0.00233 113.45 0.01883 301.74 399.69 -399.69 618.54 0.72

0.332 BET03 141768.9 0.70322 0.00117 4061.67 0.02865 0.00412 0.00234 111.91 0.01900 301.93 397.35 -397.35 610.14 0.71

Acceleration loss

CASE 3: 24 TPH WITH BAFFLE SEPARATORS

0.261049 LK01 111482.9 30.96748 0.00412 12185.00 0.02853 0.00411 0.00411 0.16547 1654.72 219.15 -219.15 1660.16 6.850.260209 LK06 111124 30.86777 0.00412 0.00411 0.00411 0.16432 1643.21 219.15 -219.15 1654.38 6.82

LK02-LK05 204450.3 14.19794 0.00412 0.00411 0.00411 0.03314 331.43 219.15 -219.15 761.15 3.140.621578 LK07 69295.4 19.24872 0.00412 0.00411 0.00411 0.02151 215.10 0.00 0.00 630.23 2.600.639996 LK08 71119.0 19.75527 0.00412 0.00411 0.00411 0.02266 226.61 0.00 0.00 646.82 2.67

0.378 FWP 42187.6 0.43403 0.00411 1326.34 0.05997 0.00734 0.00557 27.58 0.01792 206.80 807.32 -807.32 289.53 1.19 RSWP 204450.3 0.87372 0.00411 1288.74 0.03484 0.00476 0.00443 22.18 0.07853 807.49 1016.35 -1016.35 582.83 2.40

LSWP 140414.3 0.60006 0.00411 1288.74 0.03771 0.00505 0.00457 15.30 0.03821 397.39 985.27 -985.27 400.28 1.650.36 RWP 40005.0 0.41157 0.00411 726.18 0.04668 0.00598 0.00499 14.29 0.01112 125.53 902.27 -902.27 274.55 1.13

FRRT01 82192.6 0.845603 0.05350 0.05350 0.05350 0.14570 1482.04 0.00 0.00 582.06 31.140.151542 RSWRT01 30982.85 8.606346 0.00505 0.00505 0.00505 0.19736 1998.61 0.00 0.00 1348.69 6.810.156408 RSWRT02 31977.74 8.883 0.00505 0.00505 0.00505 0.19736 1998.61 0.00 0.00 1392.00 7.030.162535 RSWRT03 33230.39 9.231 0.00505 0.00505 0.00505 0.19736 1998.61 0.00 0.00 1446.53 7.310.169247 RSWRT04 34602.61 9.612 0.00505 0.00505 0.00505 0.19736 1998.61 0.00 0.00 1506.26 7.610.176523 RSWRT05 36090.15 10.025 0.00505 0.00505 0.00505 0.19736 1998.61 0.00 0.00 1571.01 7.940.176523 RSWRT05 36090.15 10.025 0.00505 0.00505 0.00505 0.19736 1998.61 0.00 0.00 1571.01 7.940.183744 RSWRT06 37566.58 10.435 0.00505 0.00505 0.00505 0.19736 1998.61 0.00 0.00 1635.28 8.260.151542 LSWRT01 21278.7 5.911 0.00476 0.00476 0.00476 0.08764 901.38 0.00 0.00 926.27 4.410.156408 LSWRT02 21962.0 6.101 0.00476 0.00476 0.00476 0.08764 901.38 0.00 0.00 956.01 4.550.162535 LSWRT03 22822.3 6.340 0.00476 0.00476 0.00476 0.08764 901.38 0.00 0.00 993.46 4.720.169247 LSWRT04 23764.7 6.601 0.00476 0.00476 0.00476 0.08764 901.38 0.00 0.00 1034.48 4.920.176523 LSWRT05 24786.3 6.885 0.00476 0.00476 0.00476 0.08764 901.38 0.00 0.00 1078.95 5.130.183744 LSWRT06 25800.3 7.167 0.00476 0.00476 0.00476 0.08764 901.38 0.00 0.00 1123.09 5.34

Circulation ratio Matching Available Head and Pressure DropHEAD DELTA P

BET 01 34.9 BB DC01 BET01 LK02-LK05 RSWP RSWRT01 3922.96 3922.97 1.00BET 02 35.4 BB DC02 BET02 LK01 FWP FRRT01 4129.40 4129.41 1.00BET 03 34.9 BB DC01 BET03 LK06 RWP FRRT01 4036.80 4036.80 1.00

BB DC01 BET01 LK01 LK07 LSWP LSWRT01 3954.04 3954.04 1.00BB DC01 BET01 LK06 LK08 LSWP LSWRT02 3954 04 3954 04 1 00BB DC01 BET01 LK06 LK08 LSWP LSWRT02 3954.04 3954.04 1.00

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links, riser tubes Riser tubes Riser tubes Element data LK01 LK02-05 LK06 LK07 LK08 RSWRT01 RSWRT02 RSWRT03 RSWRT04 RSWRT05 RSWRT06 LSWRT01 LSWRT02 LSWRT03 LSWRT04 LSWRT05 LSWRT06 FRRTTube/pipe OD mm 168.3 168.3 168.3 219.1 219.1 101.6 101.6 101.6 101.6 101.6 101.6 101.6 101.6 101.6 101.6 101.6 101.6 51thk mm 7.1 7.1 7.1 10.97 10.97 5.74 5.74 5.74 5.74 5.74 5.74 5.74 5.74 5.74 5.74 5.74 5.74 4ID mm 154.1 154.1 154.1 197.16 197.16 90.12 90.12 90.12 90.12 90.12 90.12 90.12 90.12 90.12 90.12 90.12 90.12 43ID inch 6.06614 6.06614 6.06693 7.76220 7.76220 3.54803 3.54803 3.54803 3.54803 3.54803 3.54803 3.54803 3.54803 3.54803 3.54803 3.54803 3.54803 1.69291flow area m2 0.01865 0.01865 0.01866 0.03054 0.03054 0.00638 0.00638 0.00638 0.00638 0.00638 0.00638 0.00638 0.00638 0.00638 0.00638 0.00638 0.00638 0.00145flow area ft2 0.20078 0.20078 0.20084 0.32875 0.32875 0.06869 0.06869 0.06869 0.06869 0.06869 0.06869 0.06869 0.06869 0.06869 0.06869 0.06869 0.06869 0.01564No of parallel paths no 1.0 4.0 1.0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 27Elevation data 1-Up/2-down/3-Hori 1.0 1.0 1.0 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3distance metre 0.9 0.9 0.9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0distance ft 3.0 3.0 3.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Flow resistances datalength metre 1.8 0.9 1.8 3.88 3.88 7.84 6.85 5.73 4.64 3.60 2.68 7.84 6.85 5.73 4.64 3.60 2.68 0.3entry no 20 1.0 1.0 1.0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1exit no 40 0.0 0.0 0.0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1squeeze bend no 75 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0180 bend no 50 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 090 short rad bend (R<3d) no 32 0.0 0.0 0.0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 090 std radius ( r = 3d) no 26 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 090 long rad bend ( R>3d) no 20 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 045 short rad bend ( r<3d) no 15 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 045 long rad bend ( R >3d) no 12 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0reducer no 120 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0expander no 100 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Tee - entrering run no 60 0.0 0.0 0.0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0Tee- entering branch no 90 1.0 1.0 1.0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0Tot. equiv. Length m 18.7 17.8 18.7 21.6204 21.6244 16.12904 15.14104 14.02104 12.93104 11.88704 10.97104 16.12904 15.14104 14.02104 12.93104 11.88704 10.97104 2.88Tot. equiv. Length ft 61.5 58.6 61.5 70.93307 70.9462 52.9168 49.67533 46.00079 42.424673 38.999476 35.99422687 52.9167996 49.67532967 46.0007889 42.42467 38.9994763 35.9942269 9.4488192Heat transfer dataHeated or not 1/2 2.0 2.0 2.0 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3

kg/h m2 kg/hOverall steam production 24000 DC water sp vol m3/kg 0.00117 Bed coil generation 12185 FWP 26.1 1326.3Overall CR 20.1 steam sp vol m3/kg 0.10410 baffle sep press drop 25.00 kg/m2 Boiler bank generation 7184 RWP 14.29 726.2

Waterwall generation 4630 SWP 50.72 2577.5ANALYSIS

tot. flow flow/path in.sp.vol Steaming steam out sp vol mean.sp.vol ele.pr.drop Ele Pr drop ele .head abs head mass inlet velocitykg/h kg/s m3/kg kg/h fraction m3/kg m3/kg kg/cm2 kg/m2 kg/m2/sec m/s

BB 481207.8 0.534675 0.00117 0.00117 0.00117 0.00288 28.76 3846.15 3846.15 356.66 0.420.48 DC01 230920.8 64.14467 0.00117 0.00117 0.00117 0.05750 574.97 1709.40 1709.40 1916.36 2.240.52 DC02 250287.0 69.52416 0.00117 0.00117 0.00117 0.05750 574.97 1709.40 1709.40 2077.07 2.430.331 BET01 159517.8 0.79126 0.00117 4061.67 0.02546 0.00379 0.00223 125.92 0.02289 354.83 417.60 -417.60 686.53 0.800.337 BET02 161944.8 0.80330 0.00117 4061.67 0.02508 0.00375 0.00222 127.83 0.02274 355.24 420.20 -420.20 696.97 0.82

0.332 BET03 159745.1 0.79239 0.00117 4061.67 0.02543 0.00379 0.00223 126.10 0.02294 355.53 417.85 -417.85 687.50 0.80

CASE 4: 24 TPH WITH BAFFLE SEPARATORS & ADDITIONAL LINKS

Acceleration loss

0.178406 LK01 85850.18 23.84727 0.00379 12185.00 0.02532 0.00378 0.00378 0.09022 902.25 238.32 -238.32 1278.44 4.850.178074 LK06 85690.7 23.80297 0.00379 0.00378 0.00378 0.08984 898.42 238.32 -238.32 1275.74 4.84

LK02-LK05 203777.4 14.15121 0.00379 0.00378 0.00378 0.03027 302.74 238.32 -238.32 758.64 2.880.409464 LK07 35152.5 9.764589 0.00379 0.00378 0.00378 0.00509 50.90 0.00 0.00 319.71 1.210.425329 LK08 36446.7 10.1241 0.00379 0.00378 0.00378 0.00547 54.72 0.00 0.00 331.48 1.260.110025 LK09 52944.75 14.70688 0.00379 0.00378 0.00378 0.09074 907.45 283.08 -283.08 788.23 2.990.110025 LK10 52944.75 14.70688 0.00379 0.00378 0.00378 0.09074 907.45 283.08 -283.08 788.23 2.99

0.591 FWP 50697.7 0.52158 0.00378 1326.34 0.05148 0.00647 0.00501 33.14 0.02325 265.63 898.76 -898.76 347.93 1.32 RSWP 203777.4 0.87084 0.00378 1288.74 0.03165 0.00443 0.00410 22.14 0.07219 744.04 1098.36 -1098.36 580.91 2.20

LSWP 177488.8 0.75850 0.00378 1288.74 0.03258 0.00452 0.00414 19.32 0.05537 573.06 1086.26 -1086.26 505.97 1.910.575 RWP 49243.9 0.50662 0.00378 726.18 0.04007 0.00529 0.00450 17.59 0.01520 169.55 1000.73 -1000.73 337.95 1.28

FRRT01 99941.6 1.028206 0.04586 0.04586 0.04586 0.18464 1871.42 0.00 0.00 707.75 32.460.151542 RSWRT01 30880.87 8.578019 0.00452 0.00452 0.00452 0.17558 1780.78 0.00 0.00 1344.25 6.080.156408 RSWRT02 31872.48 8.853 0.00452 0.00452 0.00452 0.17558 1780.78 0.00 0.00 1387.42 6.280.162535 RSWRT03 33121.02 9.200 0.00452 0.00452 0.00452 0.17558 1780.78 0.00 0.00 1441.76 6.520.162535 RSWRT03 33121.02 9.200 0.00452 0.00452 0.00452 0.17558 1780.78 0.00 0.00 1441.76 6.520.169247 RSWRT04 34488.72 9.580 0.00452 0.00452 0.00452 0.17558 1780.78 0.00 0.00 1501.30 6.790.176523 RSWRT05 35971.36 9.992 0.00452 0.00452 0.00452 0.17558 1780.78 0.00 0.00 1565.84 7.080.183744 RSWRT06 37442.93 10.401 0.00452 0.00452 0.00452 0.17558 1780.78 0.00 0.00 1629.90 7.370.151542 LSWRT01 26897.0 7.471 0.00443 0.00443 0.00443 0.13036 1328.60 0.00 0.00 1170.83 5.180.156408 LSWRT02 27760.7 7.711 0.00443 0.00443 0.00443 0.13036 1328.60 0.00 0.00 1208.43 5.350.162535 LSWRT03 28848.2 8.013 0.00443 0.00443 0.00443 0.13036 1328.60 0.00 0.00 1255.77 5.560.169247 LSWRT04 30039.4 8.344 0.00443 0.00443 0.00443 0.13036 1328.60 0.00 0.00 1307.62 5.790.176523 LSWRT05 31330.8 8.703 0.00443 0.00443 0.00443 0.13036 1328.60 0.00 0.00 1363.84 6.040.183744 LSWRT06 32612.6 9.059 0.00443 0.00443 0.00443 0.13036 1328.60 0.00 0.00 1419.63 6.29

Circulation ratio Matching Available Head and Pressure DropHEAD DELTA P

BET 01 39.3 BB DC01 BET01 LK02-LK05 RSWP RSWRT01 3801.27 3786.11 1.00BET 02 39.9 BB DC02 BET02 LK01 FWP FRRT01 3998.27 3998.27 1.00BET 03 39 3 BB DC01 BET03 LK06 RWP FRRT01 3898 65 3898 65 1 00BET 03 39.3 BB DC01 BET03 LK06 RWP FRRT01 3898.65 3898.65 1.00

BB DC01 BET01 LK01 LK07 LSWP LSWRT01 3813.37 3813.37 1.00BB DC01 BET01 LK06 LK08 LSWP LSWRT02 3813.37 3813.37 1.00BB DC01 BET03 LK09 LSWP LSWRT03 3768.37 3768.37 1.00BB DC01 BET03 LK10 LSWP LSWRT04 3768.37 3768.37 1.00

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BET 01 BET 02 BET 03 BET 01 BET 02 BET 03 Front wall Rear wall Left side wall

Right side wall

0.53 0.54 0.53

450.7 457.5 451.3

0.58 0.59 0.58

493.2 500.7 493.9

0.71 0.72 0.71

609.3 618.5 610.1

0.8 0.82 0.8

686.5 697.0 687.5

TABLE 1: COMPARISON OF CIRCULATION EFFECT FOR FOUR CONDITIONS

Generally in FBC boilers, downcomers and risers are so selected to achieve 1 m/s inlet velocity. The removal of turbo separators must be adequate to bring in the improvement in velocity. Starvation / DNB will be avoided.

1.13 1.65 2.4

1.32 1.28 1.91 2.2

1.01 1.54 2.22

0.97 0.86 1.25 1.83

24 TPH with baffle separator and additional links 20 39.3 39.9 39.3

1.1

1.19

18 TPH with present turbo separator 19.2 37.6 38.2 37.7

24 TPH with baffle separator 17.8 34.9 35.4 34.9

Bed coil circulation ratio Bed coil inlet velocity Waterwall inlet velocityOverall Circulation ratio

Case description

24 TPH with present turbo separator 13.2 25.8 26.2 25.8

ANNEXURE 4: RECOMMENDATIONS FOR BETTER DISTRIBUTION FROM BED COIL OUTLET HEADER TO WATERWALL