Electric integrated startup

Electric integrated startup test is a complete inspection and test before putting into service of primary and secondary system of electric system. The purpose of thid procedure is that guarantee the startup test are well organized, well planed, orderly and smooth with safety measures and that make preparations in advance to make sure the electric integrated startup work will go smoothly.

Check List for Commissioning Preparation
Mechanical team:

1. Subsystem commissioning of turbine & boiler has been finished and integrated startup can be done
2. Relevant protection for turbine and boiler has been put into service
3. All interlock protection of boiler and turbine has been put into service
4. Turbine bypass system can be put into service reliably
5. Generator tightness test is qualified. Hydrogen injection of generator proper has been finished. Hydrogen cooler and dryer have been put into service
6. Generator stator cooling water is qualified and system operation is normal
7. DCS indication of generator and turbine temperature measuring point is correct.

Electrical team:

1. Installation of primary and secondary equipment related to generator & transformer and 150kV power distribution device has been finished, which complies with the requirements of regulations and specifications and passes the acceptance inspection.
2.  Test of primary and secondary equipments related to generator, transformer, HV auxiliary transformer and excitation transformer has been finished and passed the acceptance inspection.
   Static commissioning of generator, transformer, protection system, excitation system, synchronization system and station service power transfer device has been finished. Setting work has been finished according to the setting list.
3.  Test of primary and secondary equipments related to generator, transformer, HV auxiliary transformer and excitation transformer has been finished and passed the acceptance inspection.
   Static commissioning of generator, transformer, protection system, excitation system, synchronization system and station service power transfer device has been finished. Setting work has been finished according to the setting list.
4.  Commissioning of all electric cabinet secondary circuit has been finished. Interlock protection and static transmission test have been finished, which meets the design requirements.
   Static energization test of CB 5A4 & 5AB4 and generator CT secondary AC circuit have been finished.
5.  Confirm that PT circuit is without short-circuit, CT circuit is without open circuit, wiring is correct and polarity is correct.
6.  150kV power distribution has been put into service normally, and NCS, DCS, remote control and remote measuring system work normally. 
7.  Item, Name, number and identification sign for all electric equipment are clear. Windows and doors of the power distribution room are in good condition. Lighting is sufficient. Trench cover is complete. Safety access is smooth. Communication and fire protection facilities are good and available. Safety warning sign in clear and doors can be locked.
8. Tap of main transformer and HV auxiliary transformer has been put into corresponding position according to the requirements of PLN and DC resistance of the setting position has been measured.
9. Grounding of main transformer and HV auxiliary transformer proper is good.
10.  Drying agent and oil level of oil conservator of main transformer and HIV auxiliary transformer is normal. Porcelain busing is without oil leakage.

Air of bucholz relay of main transformer and HV auxiliary transformer proper has been discharged.
Air cooling system and emergency oil discharge system of main transformer and HV auxiliary transformer can be used.
Commissioning of emergency section diesel generator set has been finished, interlock protection test is correct, auto startup function is reliable. Diesel generator set is in hot standby status during integrated startup.
Measure the insulation resistance of generator & transformer primary system, which should meet the requirements.
Measure the insulation resistance of excitation system, which should meet the requirements.
Interlock test of boiler, turbine and generator has been finished, which is correct and reliable.
All DC system and UPS system work reliably.
Generator enclosed bus micro positive pressure system has been put into service and works normally
No people work in the energized equipment area during integrated startup test and no work permit issued.
Main enclosed bus of excitation transformer and generator has been disconnected and isolating measures has been prepared.
6kV temporary excitation power supply connected from CB 6219B cabinet can be used, protection has been set based on the 140A current
Relevant manufacturer’s documents, technical data, protection setting list, test record and drawings from design institute are prepared.
Confirm CB 5A4 and 5AB4 are opened, control power is switched off and warning signs for forbidding closing operation while someone is working of relevant equipment has been hung up
Confirm CB 5A41, 5A42, 5AB41 and 5AB42 are opened, control power is switched off and warning signs for forbidding closing operation while someone is working of relevant equipment has been hung up
Item
Confirm ES 5A41E, 5A42E, 5AB41E and 5AB42E are opened, control power is switched off and warning signs for forbidding closing operation while someone is working of relevant equipment has been hung up
Bus of 150Kv bus I is dead
Confirm ES A1E and A2E of bus I are opened, warning signs for forbidding closing operation while someone is working of relevant equipment has been hung up
Confirm CB 602A and 602B are opened and in test position, control power is switched off and warning signs forbidding closing operation while someone is working of relevant equipment has been hung up.
Confirm #2 generator outgoing line PT in isolating position.
Confirm 602A PT and 602B PT are in isolating position.
6Kv short circuit trolley switch can be used.
Confirm knife switch of excitation rectifier cabinet AC side and DC side in opened position and field extinguishing breaker is in opened position.
Confirm rectification/inversion switch of field regulator cabinet is in inversion position, remote/local control switch in local control position, retreat field flashing power supply switch QF65.
Short circuit wire required in the attached drawing ( generator and transformer system drawing) has been prepared.
Short circuit current of each short circuit point as following:
K1: 13000A
K2: 1000A (Use ES 5A41E to replace it)
K3: 1000A (Use ES 5AB42E to replace it)
K4 & K5: 2000A
Wiring of rotor AC impedance test has been finished
Wiring of closing main stop valve for generator and transformer set protection, turbine over speed for ETS cabinet, synchronization auto load increasing for DEH cabinet and excitation cabinet synchronization signal has been temporarily removed.
Confirm generator neutral point ES G is in closing position.
Put into service of main transformer, HV auxiliary transformer, cooling system and excitation transformer temperature control device before integrated startup test and check  that they work normally.
Current circuit from CB 5A4 CT to bus protection in 150Kv bus I bus protection cabinet has been temporarily adjusted and voltage setting value is 115V.
Check that G & T protection device works normally
Item
Confirm generator water failure has been put into service and stator over voltage protection has been temporarily adjusted and voltage setting value is 115V.
Confirm non-electric protection of main transformer and HV auxiliary transformer has been put into service, outlet of which acts on generator excitation trip. Other protection all retreated.
6Kv primary phase check and protection equipment are available.
Unit integrated startup commissioning procedure has been approved and issued by startup commissioning chief commander and operation team has made the operation permit according to the procedure.

Emisi Dari Power Plants: Yang Harus Anda Ketahui

Power tanaman menghasilkan banyak emisi dalam proses konversi energi dari bahan bakar fosil ke Listrik. Jika hal ini menjadi perhatian bagi kita?
    Eropa masih ingat 1816 "tahun tanpa musim panas". Selama ini sinar matahari terhalang oleh awan dan kimia ominious debu atas Eropa yang menyebabkan hari-hari gelap, kegagalan panen, kelaparan dan kerusuhan. Debu awan disebabkan oleh letusan Gunung Tambora pada April 1815. Ini adalah letusan gunung berapi paling kejam tercatat dalam sejarah, yang mengirimkan jutaan ton lava, batuan dan debu bersama dengan gas sulfit tinggi ke atmosfer. Meskipun ribuan Terjadi kilometer jauhnya di Archipilago Indonesia, Eropa menghadapi konsekuensi musim semi dan musim panas tahun depan, "tahun tanpa musim panas".
    Pertanyaan yang kita hadapi saat ini jika emisi dari pabrik-pabrik industri, pembangkit listrik, kendaraan dan causers polusi lainnya dapat menciptakan efek yang mirip dengan Tambora hari ini.
    Batubara pembangkit listrik termal adalah salah satu kontributor utama untuk polusi udara dan gas rumah kaca. Emisi yang berasal dari tanaman ini bisa dikategorikan ke dalam tiga kategori yang berbeda:
        Gas emisi Karbon Dioksida, Karbon Monoksida, Nitrogen Dioksida Sulphur dan Dioksida yang menyebabkan pemanasan global dan hujan asam.
        
 Emisi partikulat - ini debu halus yang berasal dari tumpukan pembangkit listrik adalah bahaya kesehatan.
        Melacak unsur-unsur seperti Mercury, Kadmium dan Timbal yang juga bahaya kesehatan.

 Emisi ini terbentuk karena proses pembakaran saat batu bara dibakar untuk menghasilkan panas. Beberapa dihindari, beberapa dapat dikendalikan atau dikurangi, beberapa tidak dapat dihindari.
Kecuali untuk Karbon Dioksida seluruh emisi lainnya dapat dikontrol baik atau ditangkap dengan teknologi yang tersedia dengan biaya yang wajar.
Beberapa emisi ini tergantung pada kualitas bahan bakar yang digunakan. Misalnya, sulfur dioksida tergantung pada jumlah sulfur dalam batubara. Hal ini juga berlaku dengan lements jejak.Karbon Dioksida-CO2.
Karbon dioksida merupakan bagian tak terhindarkan dari proses pembakaran. Pengurangan kecil yang mungkin dengan penyesuaian proses. Pengurangan besar dalam CO2 hanya dapat dicapai dengan perubahan drastis dalam teknologi Pembangkit listrik. Bauran pembangkit listrik telah bergeser dari batubara ke sumber daya terbarukan lainnya untuk benar-benar menghilangkan CO2. Carbon capture and sistem sequesterian adalah cara yang mahal untuk menghilangkan masalah yang hanya akan membebani orang biasa di negara berkembang. Komitmen dari pemerintah untuk mengubah teknologi pembangkit listrik dan campuran adalah terluar penting. Agar hal ini terjadi teknologi di negara maju harus ditingkatkan.
Mari kita berharap pada COP15 Kopenhagen, UNFCCC dan dunia pemimpin setuju untuk perubahan yang cepat dalam teknologi pembangkit listrik.

Pulverizer Batubara di Boiler

Penghancuran batubara untuk boiler adalah faktor yang sangat penting dalam efisiensi siklus keseluruhan. Ada banyak jenis pulverizers tersedia, tetapi pemilihan yang tepat akan memastikan boiler yang konsisten dan efisiensi siklus. Hal ini membantu dalam pengurangan emisi karbon dioksida per juta unit listrik yang dihasilkan.

 Boiler untuk pembangkit uap di pembangkit listrik dan industri proses menggunakan batu bara sebagai bahan bakar. Persentase boiler beroperasi dengan batu bara sebagai bahan bakar boiler outnumbers menggunakan semua bahan bakar lainnya digabungkan. Batubara ditumbuk sebelum menembak untuk mencapai pembakaran yang stabil dan efisien. Banyak jenis pulverizers digunakan dalam boiler oleh desainer yang berbeda.
    Sejarah Pulverizer
    Sejarah peluluhan tanggal kembali sedini tahun 1824 dan dibayangkan oleh Carnot dalam mesin bertenaga batu bara. Pada tahun 1890 Diesel memanfaatkan batu bara bubuk dalam mesin diesel nya. Bubuk pembakaran batubara pertama kali dikembangkan di industri semen dan kemudian bermigrasi ke listrik dan proses industri. Sebenarnya Thomas Alva Edison dan Niepce saudara Perancis adalah perintis dalam bubuk pembakaran batubara. Teknologi ini mendapatkan momentum setelah Perang Dunia I dalam industri pembangkit listrik. Itu John Anderson, chief engineer pembangkit listrik di Wisconsin Electric Power Company yang memperkenalkan bubuk pembakaran batubara di pembangkit listrik.

    Batubara halus adalah cara yang paling efisien menggunakan batubara dalam pembangkit uap. Batubara tanah sehingga sekitar 70% akan melewati 200 mesh (0,075 mm) dan 99% akan melewati 50 jala (0.300 mm). Sebuah boiler batu bara bubuk dapat dengan mudah diadaptasi untuk bahan bakar lain seperti gas jika diperlukan kemudian tanpa banyak kesulitan. Namun, selama tahap desain adalah mungkin untuk membuat boiler menembak beberapa bahan bakar. Dengan teknologi peluluhan, boiler ukuran besar dapat dirancang, diproduksi, didirikan, dan berjalan jauh lebih efisien.
Jenis pulverizers
Terutama ada tiga jenis semprot yang digunakan dalam industri: pabrik kecepatan lambat seperti bola tabung pabrik, pabrik kecepatan sedang seperti mangkuk, bola dan ras, pabrik roller jatuh dalam kategori ini, dan jenis ketiga adalah kecepatan tinggi pabrik dampak. Kecepatan lambat dan pabrik kecepatan sedang yang dipilih untuk batubara mulai dari sub-bituminous sampai menjadi antrasit. Pabrik pengolahan kecepatan tinggi yang digunakan terutama untuk lignit.
Tujuan dari pulverizer batubara pembakaran boiler

•     Untuk memasok batu bara bubuk ke boiler sesuai kebutuhan generasi steam
•     Mengangkut batu bara bubuk dari semprot untuk pembakar dalam boiler
•     Untuk menghilangkan uap air dalam batubara ke tingkat yang dapat diterima untuk menembak boiler
•     Untuk menghapus inorganics kepadatan tinggi dari batubara selama penumbukan
•     Untuk mengklasifikasikan partikel batubara ke tingkat yang dibutuhkan kehalusan, biasanya 70% sampai 200 mesh dan kurang dari 2% pada 50 jala

Parameter yang mempengaruhi produksi batubara pulverizer
Sementara memilih semprot yang, karakteristik batubara memainkan peran penting. Indeks Hardgrove, jumlah air, ukuran batubara input, output kehalusan, dan memakai pabrik berdampak langsung pada output pabrik.
Daftar pasokan batubara memberitahu kita tentang kemudahan yang dapat ditumbuk. Sebuah indeks Hardgrove lebih tinggi menunjukkan batubara lebih mudah untuk menggiling. 50 HGI biasanya diambil untuk menghitung kapasitas dasar pabrik. Ketika batubara dengan HGI lebih tinggi dari 50 diumpankan ke pulverizer, output akan lebih tinggi dari kapasitas dasar, dan di bawah 50 HGI, output akan lebih rendah.

•     Total kelembaban batubara memiliki efek tinggi pada output pabrik. Semakin tinggi kelembaban, semakin rendah output.
•     Tinggi kehalusan batubara halus meningkatkan resirkulasi dalam pabrik dan output mengurangi.
•     Ukuran inlet batubara juga mempengaruhi output pabrik langsung.
•     Mill aliran udara variasi mengakibatkan perubahan suhu keluar pabrik dan kehalusan serta kapasitas.

Ball tube mill
Ball tube mill adalah jenis baik bertekanan atau hisap. Pada jenis bertekanan, udara utama panas digunakan untuk pengeringan batubara dan untuk mengangkut batubara digiling ke tungku. Pada tipe ini, kebocoran di area pabrik yang tinggi.
Dalam tipe hisap, pengisap debu ini digunakan untuk mengangkat batubara giling dari semprot ke tungku melalui siklon. Para pabrik tabung memiliki drum melingkar besar, dengan biaya bola yang memadai, yang diputar di sekitar 70% dari kecepatan di mana muatan bola akan diadakan terhadap permukaan bagian dalam oleh gaya sentrifugal. Dalam pabrik ini bola gerinda dapat diisi ulang di telepon.
Biasanya para desainer ball mill menggunakan tiga jenis bola dengan tiga diameter yang berbeda. Bola ini mengurangi ukuran sebagai pabrik beroperasi dan sehingga ukuran bola tertinggi biasanya digunakan untuk pengisian. Pada hari sebelumnya, sebagian besar pabrik bola memiliki inlet tunggal dan outlet, tapi sekarang desainer menggunakan kedua ujungnya untuk memberi makan batubara dan juga untuk mengambil batu bara bubuk. Sistem kontrol dibuat dengan baik untuk memahami kebutuhan muatan bola dan output dari pabrik. Pabrik bola selalu disukai untuk dioperasikan pada kapasitas penuh karena konsumsi daya dari jenis pabrik sangat tinggi pada beban yang lebih rendah bila dibandingkan dengan jenis lain. Pabrik bola dapat dirancang untuk kapasitas yang sangat tinggi seperti 75 ton per jam output untuk batubara tertentu.
Vertical spindle mill
 Ada banyak varietas yang berbeda dari pabrik vertikal. Desainer menggunakan bola baja besar berkisar antara 2 sampai 6 atau lebih di antara dua cincin grinding untuk penghancuran. Ada juga jenis lain seperti rol kerucut dengan mangkuk dangkal, mangkuk dalam, dll dimana beban diterapkan pada rol dan mangkuk berputar sambil penghancuran. Jenis pabrik dirancang biasanya sampai dengan 60 ton per jam untuk batubara tertentu, namun ada pabrik vertikal dengan 90 ton per output jam. Sebuah pabrik spindel vertikal ini juga dirancang untuk kebutuhan jenis bertekanan dan hisap. Desainer boiler menggunakan jenis pabrik untuk batubara kualitas buruk sebagai jenis pabrik menolak benda asing seperti batu dan bahan lainnya kepadatan tinggi. Daya yang dikonsumsi oleh pabrik per ton tanah batubara hanya dua-pertiga dari pabrik bola. Namun jika daya kipas udara utama juga diperhitungkan, dalam kasus pabrik bertekanan konsumsi daya yang lebih rendah hanya sekitar 15%.
High speed impact mill
 Jenis pabrik menggunakan poros horisontal pusat yang memiliki sejumlah senjata, dan pemukul dari desain yang berbeda melekat pada lengan ini untuk mengalahkan batubara untuk bubuk. Kecepatan tinggi pabrik dampak terutama digunakan dalam penghancuran lignit. Hari ini semua desainer boiler memilih untuk menggunakan bola atau mill spindel vertikal untuk batubara selain lignit.
Sementara memilih jenis pabrik desainer boiler jelas harus memahami karakteristik batubara, keseluruhan sistem yang digunakan, dan kebutuhan pemeliharaan. Itu selalu terlihat bahwa jika keuntungan dari pabrik sendiri dianggap, maka ekonomi boiler keseluruhan dapat membuktikan menjadi berbeda.

Host Load Unit

Host Load

Host Load Unit pembangkitan berbeban pemakaian sendiri

Penyebab Host Load :

1. Under/Over frequensi

• Under frequensi terjadi bila ada unit atau pembangkit lain yang lepas dari system. Biasanya set point 45,5 Hz.
• Over frequensi terjadi sebaliknya, karena adanya lepas beban secara berlebihan dalam waktu yang sama. Set point Over frequensi 51,5 Hz. bila proteksi over frequensi tidak bekerja, maka proteksi turbine yang bekerja yaitu turbine overspeed pada putaran 3300 rpm.

2. Negative Sequence

3. Out of Step

4. Voltage Balance

5. Backup Impedance

Black Out System

Black Out

Black Out adalah kondisi dimana suplai tegangan dari system tidak ada dan kondisi unit pembangkit sendiri trip. Pada saat terjadi black out tegangan murni ditanggung oleh bateray dan EDG. Baterry DC untuk mensuplai power EOP (Emergency Oil Pump) sedangkan EDG (Emergency Diesel Generator) mensuplai untuk penerangan dan keperluan Essential lainnya.

Tindakan bila terjadi Black Out :

Amankan peralatan utama (essential ) Turbin.

1. Pastikan Emergency Oil Pump Running
2. Bila EDG sudah running, pastikan JOP (Jacking Oil Pump) Auto Start pada putaran turbin <300 rpm
3. Running Turning Gear pada nol rpm turbin (Zero speed muncul)
4. Bila dalam keadaan Black Out yang cukup lama, maka suplai udara instrument akan turun, maka untuk merunning Turning Gear harus Manual Mode, start dari DCS namun tuas engage dilokal harus diposisikan tegak lurus ke atas oleh Operator Lokal.

Steamblowing

Purpose of steam blowing

Cleaning and removing the sands, welding slag, high temperature oxide and corrosions inside the main steam pipes and over-heater pipes of the boiler, which have been produced during manufacture, transportation,storage and installation. Prevent pipe explosion of the over-heater, damage of the turbine blades,and other serious accidents. Provide qualified steam for initiating the turbine and ensuring the safety initiation and operation.

Acceptance criteria

The cleaning is successfully completed when the target plate examination fulfills the
following criteria:
No impacts > 0.8 mm in an area of 2500 mm²
Max. 2 impacts >0.4 mm in an area of 2500 mm²
Max.10 impacts >0.2 mm in an area of 2500 mm²
Impacts < 0.2 mm² are well dispersed and nowhere present on concentration.

Diameter indicates maximum corner to corner measurement

STEAM BLOWING

PRINCIPLE

         The activity consist of blow-up the line with steam, discharging to the atmosphere through temporary spools and, if possible, temporary silencers to reduce the noise into acceptable range. Steam blowing utilizes the heat effects and kinetic energy of steam flow.  Heating, blowing and cooling down of the pipe concerned are repeated during steam blowing, this cycle of pipe expansion and contraction together with the flow of steam removes adhering rust, weld slag, spatter and mill scale.

          The results of steam blowing are more effective than the use of kinetic energy only as in air blowing. To obtain good result of cleanness, the steam kinetic energy on internal of steam lines must be higher than that we have during normal operation.

                                                  K =     (m2xV) SB

                                                            (m2xV) MCL

where:

k = cleaning factor

m= steam flow (kg/s)

V= steam specific volume (m3/kg)

SB = Steam Blowing condition

MCL = Max Continuous Load

          For good results during the blow up the factor K must be > 1,25

         The execution of steam blowing proceeds in the sequential order of steam supply common header, unit header, sub-header and individual branch lines.

PRECAUTION

         The following precaution is observed while steam blowing:

1)         Before conducting any steam blowing activity, the following matters are notified on in order to prevent boiler operational upsets during steam blowing caused by BFW consumption and steam demand variations.

- Steam blowing schedule

- Approximate steam consumption and duration

- Actual opening and closing of the steam valve for each steam blow

During steam blowing, it maintains close communications between the user and producer.

2)         Steam traps shall be bypassed, or removed where possible, at first while the upstream connecting lines are steam blown.  As soon as the upstream lines are confirmed clean, the steam traps shall be put into service and the function shall be inspected.

3)         Check pipes are free for the expansion and have sufficient anchorage up to the blow-off point.

4)         Sacrificial valve, such as knife valve or butterfly valve to allow quick opening,  is installed at the start end of the lines, and restriction orifice is installed downstream of such valve if required, in order to alleviate the erosion on the valve.

5)         Steam and debris shall be blown to a safe location.

Temporary lead pipes, vents etc. shall be installed at blow-off points as required to direct steam and debris to safe areas.

6)         The blow off area shall be cordoned off in compliance with site safety regulations.

7)         Exposed piping shall be checked for non-contact with combustible materials such as scaffold boards etc. to prevent the possible outbreak of fire.

8)         Before conducting steam blowing, the pipe is slowly warmed up in order to prevent the occurrence of steam hammer.

9)         In order to ensure effective steam blowing, heating, blowing and cooling shall be cycled by time or temperature monitors.

10)      When the steam line is in the cool-down step or hot condensate remains, the blow-off end must be kept open to prevent a vacuum formation inside the pipe.

11)      Once steam blowing has been successfully completed, the line instrument and line equipment/accessories which are removed prior to steam blowing shall be reinstated and placed in service or otherwise protected to prevent the re-occurrence of rust.

DETAILS FOR IMPLEMENTATION

Planning

(1)      Steam blowing shall be carried out in the sequence from upstream to downstream as follows;

Common Header → Unit Header → Sub header → Branch Lines.

After the steam blow of upstream is completed, the downstream can be started steam blowing.

(2)      Steam blowing route shall be determined and shown on a marked up P&ID.

                  The following items shall be indicated:

                  (a)        Steam blow-off points and its timing for all blows.

                  (b) Major valve positions.

                  (c) Temporary valves, spools, lead pipes, etc.

Preparation

1)   Remove the following and upon completion reinstall:

                  (a)         Safety valves

                  (b)         Check valves

                  (c)  Rupture disks

                  (d) Orifice plates of flow meter elements

                  (e)         In-line mixers/strainers

                  (f)  Spargers

                  (g)         Spray nozzles

                  (h) Control valves except ball/gate type

                  (i)  Self-actuated control valves except ball/gate type

                  (j)  Emergency shut off valves except ball/gate type

               (k)    All other items which could be damaged by the ingress of dirt or restrict the blow path

               (l) Steam traps, where possible

                  Note:  The above equipment/instrument/other accessories, where steam blowing has been finished, can be reinstalled and used for steam blowing of their downstream pipes as required.

2)   All steam traps on lines being blown shall be bypassed at first.

3)   All steam header branch lines are closed when blowing the main header.

4)   All pipe supports related are checked and confirmed its condition.

5)   Target plates is installed and checked its position (if required).

6)   Prior to the commencement of steam blowing, the route shall be checked by Company and Contractor personnel and confirmed at site.

Execution

         Lines for steam blowing are classified into the following groups, dependant on the requirements of the steam user:

         (1)    Lines equipped with a target plate.

         (2)    Lines where repeated blowing to be applied.

         (3)    Lines where once-through steam blow to be applied.

         Hereinafter, outlined procedures are given for the above classifications.

Lines Equipped with a Target Plate

         This method shall be applied to steam turbine inlet line.

         (1)    Warming up

                  Warming up operation shall be carried out by gradually opening the supply valve (initially using the bypass valves) and draining all condensate from the line until dry steam is issuing from the blow point.

         (2)    Blowing

                  Steam blowing shall be done for a period long enough to ensure that dislodged mill scale etc. has sufficient time to exit the pipe.

         (3)    Cooling down

                  Cooling down operation shall be carried out by natural or forced means dependent upon schedule requirements.

         (4)    Repetition

                  Above procedures, (1) ~ (3), shall be repeated three times without target.

         (5)    Target plate installation

                  A target plate shall be installed at the blow-off end immediately after the last steam blowing step.

         (6)    Final blow or Test blow

                  Final blowing shall be done with target plate for 10 minutes after warming up.

         (7)    Target plate inspection

                  Target plate shall be removed and inspected after the final blow.

Steam blowing shall be repeated until the results as per the target blows are acceptable and a certificate of acceptance is signed by the Company.

Lines where Repeated Blowing to be Applied

         The same procedure as described in above (1) through (4) is applicable. Implementation of steam blowing for these lines will be in the order of 10-minute blows to be repeated three times.  However, blowing duration and repetition may be considerably changed according to actual performance.  This method shall be applied to lines in the following service:

         -   Heat Exchanger

         -   Steam Ejector

         -   Atomizer

         -   Desuperheater

         -   Control Valve

         -   Column/Drum/Tank

         -   Sparger

         -   Heater for Tempered Water

         -   Jacket/Coil

         -   Exhaust Steam Lines of steam turbines

         -   Snuffing Steam

         -   Exhaust Steam Line

Lines where Once Through Steam Blowing to be Applied

         Steam blowing is carried out only once.  This method shall be applied to:

         -   Steam Pipe (Header Manifold) for Steam Trace

         -   Hose Station

ACCEPTANCE CRITERIA

Acceptance criteria for steam blowing also differ depend on the steam user classification in previous paragraph.

Lines Equipped with a Target Plate

         A copper or aluminum plate shall be brought into contact with blown-out steam at right angles and the number and degree of flaws formed on the plate due to the impact of foreign materials shall be observed.

         Acceptance criteria for these lines shall be specified by the following or by equipment vendor specification: -

         (1)    The number of flaws observed shall not exceed five per square centimeter.

         (2)    The size of a flaw shall not exceed 0.5 mm.

         Light pot-marks may be acceptable provided that there shall be NO RAISED METAL on any penetration. Steam blowing is deemed complete when the above criteria have been satisfied.

Lines where Repeated Blowing will be applied

         Steam blowing is deemed complete when no dirt or debris is witnessed at the blow-off point.

Lines where Once Through Steam Blowing will be applied

         Steam blowing is deemed complete when a single steam blowing cycle has been carried out.

POST WORK

(1) Pipes concerned are re-installed as per P&ID immediately after steam blowing has been completed or otherwise protected from corrosion and dirt ingress.

(2) All completed blows are documented and recorded on P&ID's.  Target plates are to be retained for evidence.

(3) A reinstatement work through request is conducted.

 

NOISE

During steam blowing noise is one of major HSE concern. The noise produced by a steam blow out point can to be in the region of 130-150 dB PWL. The main concerns coming from noise are as follows:

·      Possibility of hearing damage due to noise received by workers closed to a steam discharging point

·      Noise received at the nearby facilities

The following actions can be taken to avoid the hazards due to noise:

·     Noise source can be barricaded or cordoned off. Minimum distance is given by the noise calculation. In these areas access shall be restricted, regardless of whether the hearing protection is worn.

·     All the people working in the area subject to steam blowing shall use  hear protection equipment such as ear plugs and mufflers (during the steam blowing)

·     Activity can be performed during night time or when there is no personnel working on site (i.e. Sunday)

·      Noise produced can be limited by the use of silencers.

A prediction of the expected sound generated during steam blowing is made here below using the following formulas:

PWL=10 log (1/2 MC²η) +120

While the sound pressure level at a distance r from the source is calculated using this formula:

SPL = PWL – 10 log (4*π*r²)

Where:

SPL :         Sound pressure level

PWL          :         Sound Power Level

r     :         distance from the noise source

M    :         mass flow rate (kg/sec)

C    :         speed of sound of the chocked gas=kRT/Mw

k     :         ratio of specific heats (1.26 for steam)

R    :         Universal gas constant 8.3 *10³

T    :         Temperature (^oK)

Mw  :         Molecular weight

η    :         Acoustic efficiency (assumed 4*10^-3)

The calculations to be made based on noise limit 115 dB (A) (See API EA 7301), and the results give the radius of area where access shall be avoided during the steam blowing. Based on this calculations, we can decided whether to use silencer or not.