Hydraulic And Electrical Study Of The Dubal Compressed Engineering Essay

Hydraulic And Electrical Study Of The Dubal Compressed Engineering Essay

The tight air distribution system on the Dubai Aluminium Ltd ( DUBAL ) site has grown extensively since the initial installing with the air demands increasing significantly. DUBAL, have to an extent, met the addition in demand by integrating organ pipe alterations into the system, put ining extra gas turbines and new compressor units.

In 2002/2003 a old study produced by K Home International Limited ( Reference 1 )

addressed the modeling of the compressed air system for pre Kestrel site air demand which identified a figure of shrieking alterations that should be implemented to provide sufficient air to all of the site users. With the add-on of Potlines 7 and 8, plus extra aluminum oxide conveying systems with the ex post facto tantrum of bing Potlines, the addition in demand for works air station 2003 has been important. As a consequence DUBAL have identified that the current methods for production of tight air is both expensive and debatable due to drops in system force per unit area, peculiarly at the North side of the site.

DUBAL have engaged K Home International Limited to transport out a complete survey of the site compressed air web to find the feasibleness of diminishing the entire sum of air bled from the gas turbines.

2.0 Aim

The survey consists of mechanical and electrical site studies, production of a hydraulic computing machine theoretical account of the current compressed air system, electrical short circuit and burden flow computations climaxing in a concluding study.

The undertaking aims are to find the feasibleness of diminishing the entire sum of air bled from the gas turbines, in order to make this the undertaking required that we:

i‚·Provide an air demand profile for the current system demands.

i‚·iˆ Confirm the supply force per unit areas and flow rates for the system.

i‚·iˆ Confirm the air users and flow rates on the DUBAL site.

i‚·iˆ Model a basal instance of the bing web in order to verify the information obtained on

site by Matthew Lowe ( K Home International Limited ) during September 2010.

i‚·iˆ Identify any trim electrical burden at the site substations SS239 and SS5848 based on

information obtained by Scott Millar ( K Home International Limited ) during September

2010.

i‚·iˆ Identify possible piping alterations to the current air web to cut down system

constrictions.

i‚·iˆ Production of a concluding study foregrounding possible betterments to the compressed air

system and the associated costs.

3.0 SYSTEM OPERATION

The mean hourly demand of tight air had been identified by DUBAL as 80,000 mA?/hr – 85,000 mA?/hr with occasional extremums of about 90,000 mA?/hr at a force per unit area of 6.5 saloon ( g ) . During the site study it was noted that the recent piping alteration at the East of compressor house 1 by-passed the current flow metre, DUBAL have already identified this issue and have initiated a programme to put in an extra flow metre into the new line. However presently the extra air fluxing through this subdivision is quantified and is non included in the SCADA information ( Appendix A ) . The extra air flow through the unmetered subdivision is 7,000 mA?/hr. When reexamining the tight air production tendency information produced from the SCADA system ( Appendix B ) this increases the normal site supply to about 93,000 mA?/hr at a force per unit area of about 6.0 saloon ( g ) .

The production of tight air is presently managed by the Power and DESAL control room ; nevertheless the control room has a limited map as they do non hold an overall position of the compressed air system. Presently the control room monitor the flow rates at the end product of the two compressor houses and at each of the three DAD houses. The force per unit area is merely presently monitored by the control room at two locations, the end product of compressor house 7 and the end product at DAD house 3. The control room has no information available relating to the force per unit area readings at any of the potlines or at any other points within the system.

There are presently 5 beginnings of air providing the DUBAL compressed air system:

1. Compressor House 1 which supplies about 35,000 mA?/hr of air via two Atlas

Copco ZH10000 compressor units, two Ingersoll Rand Centac CV2-C80MX3 compressor units and air bled from the 9B gas turbines.

2. Potline 7 compressor house which supplies about 15,000 mA?/hr of air via nine responsibility and one stand-by Kaeser 5PL7BCOMP2 compressor units.

3. Air from the desiccant driers bled from gas turbines 15 and 16 which supplies

about 12,000 mA?/hr of air.

4. Air from the desiccant driers bled from gas turbines 17 and 18 which supplies

about 15,000 mA?/hr of air.

5. Air from the desiccant driers bled from gas turbines 19 and 20 which supplies

about 25,000 mA?/hr of air.

All of the compressors at compressor house 1 and 7 are usually runing at maximal end product with the end products from DAD houses 1 and 2 being controlled by manually restricting isolation valves. The system is controlled at DAD house 3 with the usage of a force per unit area control valve.

4.0 MODEL CONSTRUCTION AND DATA INPUT

The air distribution web was modelled utilizing PIPENET package from Sunrise Systems Ltd, version 1.41. Rather than trying to pattern the web in it ‘s entireness it was considered sufficient to simplify the web by merely patterning the 4 ” and above lines.

The theoretical account of the air distribution web was developed by utilizing the line sizes, lengths, adjustments, valve types and locations scaled from pulling INF 02 301 Revision H ( Appendix C ) with the alterations at compressor house 1, compressor house 7, East of Potline 9 identified during the site study and the subsequent alteration associating the North West terminal of Potlines 1 and 9 all incorporated into the theoretical account, see Appendix D for marked up studies. The pipe diameters were by and large available from the drawing and line sizes were merely assumed in a few little countries.

The maximal air flows into the compressed air web used in the theoretical account ( s ) are:

Air Supply Summary

Beginning

Flow Rate ( mA?/hr )

Remarks

Compressor House 1

35,000

Compressor House 7

15,000

DAD House 1

12,000

GT 15 and 16

DAD House 2

15,000

GT 17 and 18

DAD house 3

25,000

GT 19 and 20

The air flows from each of the gas turbines have been split every bit between each brace e.g. the 12,000 mA?/h end product from DAD house 1 has been created by patterning both GT-15 and GT-16 each providing 6,000 mA?/h.

GT-19 and GT-20 are considered to take up any fluctuation from the normal upper limit flows, and the end product from these is assumed to change from the maximal flows as required. The system force per unit area is set to 6.5 saloon ( g ) ( 7.51325 bara ) at GT-20 in order to repair the system force per unit area. The base instance scenario that is discussed in this study is modelled with air flows is taken as 28.656 kg/s, stand foring 100 % of the maximal flows for all Potlines running at maximal rate, all Alumina conveying operating at 50 % of design rate ( except for 5a ) , no Alumina unloading and a 25 % system escape rate. The scenario instances have been specified by DUBAL and are presently deemed to be representative of a normal operating instance, extra scenarios have been used to prove the theoretical account and place countries that can be improved by extra piping alterations.

A tabulated list summarizing the air use on site is included on the undermentioned page.

Air Usage Summary

Area

Item

Flow Rate ( mA?/hr )

Remarks

Potline 1 to 4

Potlines

8651.14

Alumina Unloading

n/a

Own dedicated air supply

Alumina Conveying

n/a

Potline 5 and 6

Potlines

12898.65

Alumina Unloading

0

Alumina Conveying

0

5B and Eagle

Potlines

1027.78

Alumina Unloading

n/a

Alumina Conveying

888

888 Based on 50 % of design value

Potline 7

Potlines

6664.3

Alumina Unloading

0

7a Alumina Conveying

2592

Based on 50 % of design value

7b Alumina Conveying

2472

Potline 8

Potlines

1342.99

Alumina Unloading

0

Alumina Conveying

n/a

Potline 9A

Potlines

5694.3

Potline 9B listed individually

Alumina Unloading

0

Alumina Conveying

1932

Based on 50 % of design value

Potline 9B

Potlines

970.00

Alumina Unloading

n/a

Alumina Conveying

468

Based on 50 % of design value

Carbon Plant

1656

Cast House 1

5562

Cast House 2

3564

Pot Dig Out

504

Crucible Cleaning

504

Rodding Room

3423.8

Pot Repair Building

1198.8

Pot Repair Kestrel

1198.8

Cast House 3

5562

Sub Total =

68,774.56

System Losingss

=25 %

Entire Usage =

85,968.20

The net consequence is a combined air demand of 35,986 mA?/hr to be bled from the gas turbines, see spreadsheet in Appendix E for a sum-up of the air flows and uses calculated for the base instance scenario.

5.0 MODEL RESULTS AND OPTION DISCUSION

5.1 MODEL RESULTS

The base instance theoretical account shows that the bing web with the deliberate air supplies and usage consequences in a minimal force per unit area of 5.910 saloon ( g ) in Potline 7 with similar force per unit areas of bomber 6.0 saloon ( g ) calculated within Potline 9.

The deliberate minimal force per unit areas represent similar figures to those presently experienced on site nevertheless the location of the low force per unit area within Potline 7 differs significantly to the location identified by site operations i.e. Potline 9-1 A/B and 9-2 A/B. The location of low system force per unit area is due to the conveying air figures used for Potlines 7 and 7b ; for the basecase scenario this equates to about 7.5 % of the overall air supplied to the system. It must besides be remembered that the base instance theoretical account does non stand for a upper limit tight air use as no aluminum oxide droping or alumina conveying for Potline 5a figures are included in the scenario.

Due to the deficiency of flow metres within the compressed air system on the DUBAL site accurate usage rates can non be determined nevertheless it can be considered that the theoretical account is a moderately accurate and returns consequences that are equal for placing system jobs and betterments. As portion of the current on-going plan to put in extra flow metres within the compressed air system DUBAL should see including flow metering within each of the heavy stage systems to enable more accurate dense stage ingestion figures to be obtained.

The base instance theoretical account consequences were examined and as expected the connectivity around the six GT ‘s at the South terminal of the site is rather good with about 20 % of the air supply for GT ‘s 19 and 20 providing air via a 12 ” line to the 10 ” pealing chief on the West side of compressor house 1. The staying 80 % of the air supplied by GT ‘s 19 and 20 is supplementing the air produced by the four other GT ‘s which supply:

i‚·iˆ Approximately 15 % of the air produced is supplied to Potline 5A via the 6 ” line on the

West side of the Potline.

i‚·iˆ Approximately 25 % of the air produced is supplied to Potlines 5 and 6 via the 8 ” line to the South terminal of the Potline.

i‚·iˆ Approximately 50 % of the air produced is supplied to the North East terminal of the site via

the 12 ” line that was installed as a consequence of the initial study in 2002 ( Reference 1 ) .

i‚·iˆ Approximately 10 % of the air produced is supplied to the 6 ” pealing chief on the Eastern

margin of the site, with the bulk being utilised in Casthouse 2.

The 20 % of air produced at GT19 and 20 addendums the air produced at compressor house 1 and supplies the followers:

i‚·iˆ Approximately 60 % of the air produced supplies the Potlines straight.

i‚·iˆ Approximately 40 % of the air produced supplies the other local users.

5.2 OPTION DISCUSSION

The revised base instance used for alteration B of this study consequences in an air distribution system that does non bespeak any countries of important force per unit area derived functions. The largest derived function in force per unit areas occur between Potlines 1 and 7 and Potlines 5 and 7, calculated at 0.21 saloon ( g ) and 0.19 saloon ( g ) severally. This would propose that the old alterations carried out to the piping web have been successful and have resulted in taking the important constrictions within the system.

As antecedently indicated Potline 7 has been identified as the country on site with the lowest air

force per unit area. One of the chief causes for the low force per unit area is the important measure of air consumed as portion of the dense stage aluminum oxide conveyance.

5.2.1. In a old alteration of this study it was indicated that the base instance state of affairs could doubtless be improved by associating the Potline 9 South heading with the North heading at Potline 1 – 4 ; nevertheless after closer review on site it was noted that one of the alterations proposed had already been identified and implemented associating the West terminal of Potlines 1-4 and 9. The consequence of this alteration as expected has reduced the differential force per unit areas between Potlines 1-4 and 9 significantly, nevertheless the alteration has non reduced the measure of air required from the gas turbines. The 2nd alteration antecedently identified would be to associate the East terminal of Potlines 1- 4 and 9, this alteration would increase the minimal force per unit area experienced in Potline 9 merely marginally by about 0.02 saloon ( g ) .

5.2.2. Furthermore if the subdivision of line providing the North West heading at Potline 1-4 was increased from 6 ” to 8 ” so this would increase the minimal force per unit area experienced by the system further with an addition in force per unit area of about 0.13 saloon ( g ) above the old instance.

5.2.3. Increasing the air capacity in Compressor House 1 is an obvious solution. This would intend that extra connexions between the compressors and the potlines would necessitate to be added.

However, this is non an ideal solution as there are important infinite limitations and deficient distribution organ pipe in the country local to Compressor House 1 to function as a cardinal location for the significant increased air supply capacity that would be required to let the riddance of air takeoff from the GT ‘s. Furthermore important organ pipe alterations would be required. If it was deemed executable to turn up extra compressors at Compressor House 1 the organ pipe distribution system could be well improved, perchance by developing a 12 ” pealing chief around the site. This could be carried out by associating the 12 ” pipe that presently runs from the country of Compressor House 1 to the West of GT15 to the 12 ” pipe which runs from a location between GT16 and GT17 across the site. Associating these subdivisions of 12 ” organ pipe up would affect the installing of a significant sum of organ pipe, but would greatly better the flexibleness of the air distribution system and may give economic benefits by doing the location of extra compressor capacity less critical.

There are two options for put ining extra compressor capacity in Compressor House 1 and are discussed in Section 4 of the Electrical study ( Appendix Q ) . Please note limitations on these options.

5.2.3.1. Section 4.1.1 of the Electrical study indicates that there is a possibility to put in an extra 1120kW air compressor such as a H2O cooled Atlas Copco

ZH10000 which could potentially provide an extra upper limit 10,000mA?/hr of

air. No alterations would be required to the patchboard as there is a spare

400A feeder and there is sufficient trim capacity at transformer 239/T3.

5.2.3.2. In add-on to this subdivision 4.1.2 of the study indicates that with minor alterations to the patchboard to include an extra 400A feeder so two extra ZH10000 compressors could be installed.

If both compressors were installed so this would potentially increase the air produced at Compressor House 1 by a entire 20,000 mA?/hr, for a entire budget cost of about ?770,000.

Item

Description

Cost

Remarks

1st Compressor

10,000mA?/hr ZH10000

?266,500

Verbal quotation mark from Atlas Copco

2nd Compressor

10,000mA?/hr ZH10000

?266,500

Verbal quotation mark from Atlas Copco

Compressor Installation

Labour Time 2 x 700 hour

?42,000

Estimate

Shrieking

60m of 10 ” pipe design and installing

?38,000

Organ pipe to tie-in the new

compressors merely ( Estimate )

1st Electrical

Design and installing

?60,000

Refer Appendix Q

2nd Electrical

Design and installing

?70,000

Refer Appendix Q

Weather Canopy

Design and installing

?30,000

5.2.4. A better option would hence be to merely increase the air supply from the East side of the works as presently there is a reasonably good air provide path from the North East side of the site. However there are already a big figure of users in this general country and Potlines 7, 8 and 5B every bit good as Potlines 9A and 9B are comparatively short of air at nowadays. It is hence considered that as it is intended in the long term to cut down the air take off from the GT ‘s so consideration should be given to put ining extra air supply capacity in the country East of Potline 7. There are legion options for put ining extra air capacity at the location of the compressor house at Potline 7 and are discussed in subdivision 5 of the Electrical study located in Appendix Q of this study.

Section 5.1.1 of the Electrical study indicates that there is a possibility nstall an extra 315kW air compressor such as the air cooled Atlas Copco T315 VSD, this could potentially provide an extra upper limit 2,844mA?/hr of air. No major alterations would be required as there is sufficient trim capacity at transformer 5848/T1.

An extra Atlas Copco ZT315 VSD compressor could be installed if the patchboard at the 5848 switchroom was extended as there is sufficient trim capacity at transformer 5484/T2.

If both of the air cooled compressors were installed so this would potentially increase the air produced at the compressor house local to Potline 7 by a entire 5,688 mA?/hr, for a entire budget installing cost of about ?450,000.

Item

Description

Cost

Remarks

1st Compressor

2,844mA?/hr ZT315VSD

?191,500

Verbal quotation mark from Atlas Copco

2nd Compressor

2,844mA?/hr ZT315VSD

?191,500

Verbal quotation mark from Atlas Copco

Compressor Installation

Labour Time 2 x 250 hour

?17,500

Estimate

Shrieking

30m of 6 ” pipe design and installing

?20,000

Estimate

1st Electrical

Design and installing

?10,000

Refer Appendix Q

2nd Electrical

Design andinstallation

?20,000

Refer Appendix Q

With extended alteration to the 400V 5484/1 patchboard there is possible to replace the bing 10s Kaeser 5PL7BCOMP2 compressors with a upper limit of 12 air cooled Atlas Copco ZT315 VSD units. The installing of the 12 compressors could potentially provide the ring chief with 34,128 mA?/hr of free air, about 19,000 mA?/hr more than presently being roduced by the bing Kaeser units. The budget cost for put ining the 12 units is about ?2.6 million. Please note the limitations and operational processs imposed as a consequence of these options.

Item

Description

Cost

Remarks

12 Compressors

2,844mA?/hr ZT315VSD

?2,300,000

Verbal quotation mark from Atlas Copco

Compressor Installation

Labour Time 12 x 250 hour

?105,000

Estimate

Shrieking

200m of 6 ” pipe installed

?95,000

Estimate

Electrical

Design and installing

?100,000

Refer Appendix Q

Civil/Structural

Existing canopy utilised

If the current 5848/1 patchboard and 5848/T1 and T2 transformers were replaced by equipment with an increased capacity, so larger H2O cooled tight air units could be installed at the bing compressor house 7 location. For illustration six Atlas Copco ZR900 VSD air compressors could be supplied from a new 3.3kV 6.3MVA transformers and patchboards. The installing of six of these units could potentially provide the tight ring chief with 53,064 mA?/hr of free air, about 38,000 mA?/hr more than presently being produced with the bing units. The budget cost for put ining the new transformers, patchboard, organ pipe and six compressors would be about ?2.5 million. An addition of air production and initial nest eggs of around ?360,000 could be made by buying direct thrust compressor units such as the Atlas Copco ZH10000.

Item

Description

Cost

Remarks

6 Compressors

8,844mA?/hr ZR900VSD

?1,950,000

Verbal quotation mark from Atlas Copco

Compressor Installation

Labour Time 6 x 500 hour

?105,000

Estimate

Shrieking

200m of 6 ” pipe installed

?150,000

Estimate

Electrical

Design and installing

?300,000

Refer Appendix Q

Civil/Structural

Existing canopy utilised

The following tabular array summarises the modelled instances, the deliberate minimal force per unit area identified in the system and its location, the net consequence on the measure of air required from the gas turbines and the associated declarative budget costs associated to implement the alterations.

Model Summary

Case

System Pressure

Bleed Air Required from Gas Turbines

Budget Costss

Appendix

Min.

Location

1

Base Case

5.910

saloon ( g )

Potline 7

35,968 mA?/hr

n/a

Appendix E

2

Base Case and all Conveying Operating

5.861

saloon ( g )

Potline 7

38,248 mA?/hr

n/a

Appendix F

3

Base Case and 5a unloading

5.844

saloon ( g )

Potline 7

39,093 mA?/hr

n/a

Appendix G

4

Base Case and 5a+5b

droping

5.769

saloon ( g )

Potline 7

42,218 mA?/hr

n/a

Appendix H

5

Base Case and

5a+5b+7 droping

5.654

saloon ( g )

Potline 7

45,343 mA?/hr

n/a

Appendix I

6

Base Case and

5a+5b+7+8 droping

5.556

saloon ( g )

Potline 7

48,343 mA?/hr

n/a

Appendix J

7

Base Case and

5a+5b+7+8+9

droping

5.434

saloon ( g )

Potline 7

51,468 mA?/hr

n/a

Appendix K

8

Base Case and

5a+5b+7+8+9

droping and 5a

conveying

5.352

saloon ( g )

Potline 7

53,748 mA?/hr

n/a

Appendix L

9

Base Case and

5a+5b+7+8+9

droping and 5a

conveying + Linked

Headings for Potline 4-9

5.367

saloon ( g )

Potline 7

53,748 mA?/hr

?13,000

30m of pipe

including

design and

installing

Appendix M

10

Base Case and 5a+5b+7+8+9 unloading and 5a conveying + Linked

Headings for Potline 4-9.

Supply line increased

to 8 ” .

5.482

saloon ( g )

Potline 7

53,748 mA?/hr

?50,000

110m of pipe

including

design and

installing

Appendix N

11

Base Case and

5a+5b+7+8+9

droping and 5a

conveying + Linked

Headings for Potline 4-9.

Extra 20,000mA?/hr

at CH1

5.564

saloon ( g )

Potline 7

33,748 mA?/hr

?770,000

see 5.2.3.2

Appendix O

12

Base Case and

5a+5b+7+8+9

droping and 5a

conveying + Linked

Headings for Potline 4-9.

53,000mA?/hr at CH7

6.325

saloon ( g )

Casthouse 1

15,748 mA?/ hour

?2.2-2.5 m

see 5.2.4.4

Appendix P

Notes:

1. The base instance theoretical account has been produced for a maximal operating instance for potlines, 50 % of the design valves for aluminum oxide conveyance ( excepting 5a ) , no aluminum oxide droping and a system leakage factor of 25 % .

2. Location of low force per unit area within Potline 7 is due to the ingestion rate of air used for heavy stage conveyance.

3. It is assumed that for instance 11 and 12 there would be sufficient chilling H2O available.

4. It is assumed that no extra driers would be required as there would be sufficient trim capacity within the bing air drying equipment.

5. All computations are based on free air measures.

6. All costs given are an declarative order of magnitude ; farther technology would be required to polish the estimations.

6.0 CONCLUSIONS AND RECOMMENDATIONS

6.1 Measuring the proposed options and from the findings of the burden flow survey farther enlargement is possible at both Substations 239 and 5848. The options given have increasing cost deductions that need consideration to measure their practicality. Both SS239 and SS5848 Switchboards have range for enlargement but besides have restrictions and limitations with burden casting patterns that may non be deemed appropriate for the DUBAL operational processs.

6.2 There are a figure of short to medium term solutions that could be implemented to cut down the figure of issues that are presently being experienced by operations due to low force per unit areas in the system, peculiarly at the North terminal of the site, these include:

6.2.1 The possibility of reassigning force per unit area sender signals using links to other country control systems should be explored. These would be used to supply an air ingestion overview page on the SCADA system displayed in the Power & A ; DESAL control room. This graphical page can be designed to expose tight air force per unit areas throughout the site which would supply early indicant of any decrease in system force per unit area and warn the operator or turn to the job automatically.

6.2.2 Ensure that standalone compressors are utilized for house maintaining responsibilities to cut down the measure of air drawn from the web.

6.2.3 Continue with the current programme of plants to put in standalone compressors for alumina unloading activities to cut down the measure of air drawn from the web.

6.2.4 Review the options to use any of the bing electrical provenders that are presently

available, one such possibility reviewed on site would be to add little compressor units local to substations 5160 and substation 5360 at Potline 9. The size of the compressor suitable would necessitate to be determined nevertheless indicants are that a little 315KW air cooled compressor could be installed by modifying the bing switchgear.

6.2.5 Continue with the current programme of plants to put in extra flow metres within the compressed air system. Focus should be given to the installing for metering the dense stage conveying systems, in peculiar within Potline 7. The values obtained from the install metres could so be built into the theoretical account enabling more accurate computations and designation of system low force per unit areas.

6.2.6 Initiate a programme of plants to increase the size of the organ pipe antecedently installed associating the West headings of Potline 1-4 and Potline 9 and put in extra organ pipe to associate the East headings ; nevertheless implementing both of these alterations would merely increase the minimal system force per unit area by about 0.13 saloon ( g ) and hence may non be deemed economically feasible.

6.2.7 The possibility of put ining extra organ pipe to the aluminum oxide droping station at Potline 8 has been considered but deemed to be inappropriate as presently there is no indicant of limitations within the piping system. Therefore in order to cut down the operational issues presently experienced by the site users during alumina droping at Potline 8, the feasibleness of put ining a little local standalone compressor should be considered.

6.3 The long term recommendation to cut down the air bled from bing gas turbines would be to originate a plan of plants to put in extra transformers and switchgear in the compressor house local to Potline 7, with the long term purpose of put ining a significant measure of extra compressed air. In order that this can be carried out no major organ pipe alterations would be required to the ring chief for the extra air produced other than a 12 ” nexus line from the compressor house into the bing 12 ” chief. This is deemed a better option than increasing the air production capacity at Compressor House 1 as an addition of the graduated table required would necessitate considerable organ pipe alterations in add-on to the addition in electrical substructure. It must be noted that the indicated budget costs, assumes that there is sufficient trim capacity within the bing air drying equipment and besides within the bing chilling H2O system to run into the extra demands described within this study.