BOILER

Definisi Boiler:

Boiler adalah bejana tertutup dimana air atau cairan lainnya dipanaskan. Cairan

panas atau menguap keluar boiler untuk digunakan dalam berbagai proses atau aplikasi

pemanas.

Jenis-Jenis Boiler:

Superheated steam boilers

A superheated boiler on a steam locomotive.

Most boilers produce steam to be used at saturation temperature; that is, saturated steam.

Superheated steam boilers vaporize the water and then further heat the steam in a

superheater. This provides steam at much higher temperature, but can decrease the

overall thermal efficiency of the steam generating plant because the higher steam

temperature requires a higher flue gas exhaust temperature. There are several ways to

circumvent this problem, typically by providing an economizer that heats the feed water,

a combustion air heater in the hot flue gas exhaust path, or both. There are advantages to

superheated steam that may, and often will, increase overall efficiency of both steam

generation and its utilisation: gains in input temperature to a turbine should outweigh any

cost in additional boiler complication and expense. There may also be practical

limitations in using wet steam, as entrained condensation droplets will damage turbine

blades.

Superheated steam presents unique safety concerns because, if any system component

fails and allows steam to escape, the high pressure and temperature can cause serious,

instantaneous harm to anyone in its path. Since the escaping steam will initially be

completely superheated vapor, detection can be difficult, although the intense heat and

sound from such a leak clearly indicates its presence.

Superheater operation is similar to that of the coils on an air conditioning unit, although

for a different purpose. The steam piping is directed through the flue gas path in the

boiler furnace. The temperature in this area is typically between 1300–1600 degrees

Celsius (2372–2912 °F). Some superheaters are radiant type; that is, they absorb heat by

radiation. Others are convection type, absorbing heat from a fluid. Some are a

combination of the two types. Through either method, the extreme heat in the flue gas

path will also heat the superheater steam piping and the steam within. While the

temperature of the steam in the superheater rises, the pressure of the steam does not and

the pressure remains the same as that of the boiler.[6] Almost all steam superheater system

designs remove droplets entrained in the steam to prevent damage to the turbine blading

and associated piping.

Supercritical steam generator

Steam generation power plant.

Main article: Supercritical steam generator

Supercritical steam generators are frequently used for the production of electric power.

They operate at supercritical pressure. In contrast to a "subcritical boiler", a supercritical

steam generator operates at such a high pressure (over 3,200 psi/22.06 MPa or

3,200 psi/220.6 bar) that the physical turbulence that characterizes boiling ceases to

occur; the fluid is neither liquid nor water but a super-critical fluid. There is no

generation of steam bubbles within the water, because the pressure is above the critical

pressure point at which steam bubbles can form. As the fluid expands through the turbine

stages, its thermodynamic state drops below the critical point as it does work turning the

turbine which turns electrical generator from which power is ultimately extracted. The

fluid at that point may be a mix of steam and liquid droplets as it passes into the

condenser. This results in slightly less fuel use and therefore less greenhouse gas

production. The term "boiler" should not be used for a supercritical pressure steam

generator, as no "boiling" actually occurs in this device.

Hydronic boilers

Hydronic boilers are used in generating heat for residential and industrial purposes. They

are the typical power plant for central heating systems fitted to houses in northern Europe

(where they are commonly combined with domestic water heating), as opposed to the

forced-air furnaces or wood burning stoves more common in North America. The

hydronic boiler operates by way of heating water/fluid to a preset temperature (or

sometimes in the case of single pipe systems, until it boils and turns to steam) and

circulating that fluid throughout the home typically by way of radiators, baseboard

heaters or through the floors. The fluid can be heated by any means...gas, wood, fuel oil,

etc., but in built-up areas where piped gas is available, natural gas is currently the most

economical and therefore the usual choice. The fluid is in an enclosed system and

circulated throughout by means of a pump. The name "boiler" can be a misnomer in that,

except for systems using steam radiators, the water in a properly functioning hydronic

boiler never actually boils. Some new systems are fitted with condensing boilers for

greater efficiency. These boilers are referred to as condensing boilers because they are

designed to extract the heat of vaporization of the flue gas water vapor. As a result of the

lower flue gas temperatures, flue gas water vapor condenses to liquid and with dissolved

carbon dioxide forms carbonic acid. The carbonic acid would damage a typical boiler by

corroding the flue and fireside boiler heating surfaces. Condensing boilers solve this

problem by routing the carbonic acid down a drain and by making the flue exposed to the

corrosive flue gas of stainless steel or PVC. Although condensing boilers are becoming

more popular, they are still less common than other types of hydronic boilers as they are

more expensive.

Hydronic systems are being used more and more in new construction in North America

for several reasons. Among those are:

They are more efficient and more economical than forced-air systems (although

initial installation can be more expensive, because of the cost of the copper and

aluminum).

The baseboard copper pipes and aluminum fins take up less room and use less

metal than the bulky steel ductwork required for forced-air systems.

They provide more even, less fluctuating temperatures than forced-air systems.

The copper baseboard pipes hold and release heat over a longer period of time than air

does, so the furnace does not have to switch off and on as much. (Hydronic systems heat

mostly through conduction and radiation, whereas forced-air heats mostly through forced

convection. Air has much lower thermal conductivity and volumetric heat capacity than

copper, so the conditioned space warms up and cools down more quickly than with

hydronic. See also thermal mass.)

They tend to not dry out the interior air as much as forced air systems, but this is

not always true. When forced air duct systems are air-sealed properly, and have return-air

paths back to the furnace (thus reducing pressure differentials and therefore air movement

between inside and outside the house), this is not an issue.

They do not introduce any dust, allergens, mold, or (in the case of a faulty heat

exchanger) combustion byproducts into the living space.

Forced-air heating does have some advantages, however. See forced-air heating.

Secara garis besar Boiler dikelompokan dalam:

Boilers can be classified into the following configurations:

"Pot boiler" or "Haycock boiler": a primitive "kettle" where a fire heats a

partially-filled water container from below. 18th century Haycock boilers generally

produced and stored large volumes of very low-pressure steam, often hardly above that of

the atmosphere. These could burn wood or most often, coal. Efficiency was very low.

Fire-tube boiler. Here, water partially fills a boiler barrel with a small volume left

above to accommodate the steam (steam space). This is the type of boiler used in nearly

all steam locomotives. The heat source is inside a furnace or firebox that has to be kept

permanently surrounded by the water in order to maintain the temperature of the heating

surface just below boiling point. The furnace can be situated at one end of a fire-tube

which lengthens the path of the hot gases, thus augmenting the heating surface which can

be further increased by making the gases reverse direction through a second parallel tube

or a bundle of multiple tubes (two-pass or return flue boiler); alternatively the gases may

be taken along the sides and then beneath the boiler through flues (3-pass boiler). In the

case of a locomotive-type boiler, a boiler barrel extends from the firebox and the hot

gases pass through a bundle of fire tubes inside the barrel which greatly increase the

heating surface compared to a single tube and further improve heat transfer. Fire-tube

boilers usually have a comparatively low rate of steam production, but high steam storage

capacity. Fire-tube boilers mostly burn solid fuels, but are readily adaptable to those of

the liquid or gas variety.

Water-tube boiler. In this type, the water tubes are arranged inside a furnace in a

number of possible configurations: often the water tubes connect large drums, the lower

ones containing water and the upper ones, steam and water; in other cases, such as a

monotube boiler, water is circulated by a pump through a succession of coils. This type

generally gives high steam production rates, but less storage capacity than the above.

Water tube boilers can be designed to exploit any heat source and are generally preferred

in high pressure applications since the high pressure water/steam is contained within

small diameter pipes which can withstand the pressure with a thinner wall.

Flash boiler. A specialized type of water-tube boiler.

1950s design steam locomotive boiler, from a Victorian Railways J class

Fire-tube boiler with Water-tube firebox. Sometimes the two above types have

been combined in the following manner: the firebox contains an assembly of water tubes,

called thermic siphons. The gases then pass through a conventional firetube boiler.

Water-tube fireboxes were installed in many Hungarian locomotives, but have met with

little success in other countries.

Sectional boiler. In a cast iron sectional boiler, sometimes called a "pork chop

boiler" the water is contained inside cast iron sections. These sections are assembled on

site to create the finished boiler.

Terminologi Boiler:

Ashpan

Sebuah wadah di bawah tungku untuk menangkap abu yang jatuh melalui firebars.

Ashpan dapat terbuat dari bata untuk boiler stasioner, atau lembaran baja untuk

lokomotif. Ashpans sering menjadi lokasi damper dan biasanya berbentuk hopper, untuk

memudahkan pembersihan selama pembuangan.

Blow-down cock

katup yang dipasang rendah di atas boiler, biasanya di sekitar cincin fondasi, yang

digunakan untuk secara berkala melampiaskan air dari boiler.

Blower

blower menyediakan dam buatan di atas api, mendorong pembakaran. Blower terdiri dari

cincin berongga dipasang di dasar cerobong atau di atas blastpipe tersebut. Lubang dibor

di bagian atas cincin blower, dan ketika uap dimasukkan ke dalam ring, jet uap keluar

dari lubang sampai cerobong, merangsang dam buatan tersebut.

Brick arch

Sebuah penyekat horizontal batu bata tahan api dalam tungku, biasanya dari boiler

lokomotif. Brick arch ini memaksa pembakaran gas dari bagian depan tungku mengalir

lebih jauh, mendorong pembakaran yang efisien.

Carryover

kondisi yang merusak di mana tetesan air dilakukan boiler bersama dengan uap kering.

Ini dapat menyebabkan penggosokan dalam turbin atau mengunci hidrolik pada silinder.

Risiko ini disebabkan oleh air umpan kotor.

Check valve

or clack valve, sebuah katup non-return dimana air umpan masuk drum boiler. Mereka

biasanya dipasang di tengah jalan sepanjang drum boiler, atau sebagai top feed, tetapi

jauh dari tungku, sehingga untuk menghindari stressing dari air dingin.

Cladding

Lapisan isolasi dan pembungkus luar sekitar shell boiler, terutama yang dari lokomotif

uap. Dalam praktek awalnya cladding biasanya merupakan strip kayu ditahan oleh pita-

pita kuningan. Kemudian praktek modern adalah dengan menggunakan anyaman asbes

isolasi (atau lainnya, kurang berbahaya, serat) ditutup dengan lembaran baja gulungan.

Bentuk luar kelongsong sering merupakan penyederhanaan dari shell boiler yang

mendasarinya. Juga disebut "pakaian" dalam praktek LMS.

Crinolines

Kerangka lingkaran digunakan untuk mensuport cladding pada boiler.

Crown sheet

Lembar di bagian atas dari firebox bagian dalam pada boiler lokomotif. Crown sheet

merupakan bagian terpanas dari tungku, dan terkadang beresiko menimbulkan ledakan

boiler. Bila tingkat air drop dan lembar mahkota terkena dengan demikian dapat

menyebabkan overheat.

Damper

Sebuah flap yang dapat disesuaikan untuk mengendalikan udara di bawah fire-bed.

Biasanya bagian dari ashpan tersebut.

Dome

lokasi yang dibesarkan di bagian atas drum boiler utama, menyediakan titik tinggi untuk

mengumpulkan uap kering, mengurangi risiko priming.

Downcomer

pipa eksternal yang besar di banyak tube-water boiller, membawa air dingin tanpa

pemanas dari drum uap turun ke drum air sebagai bagian dari jalur sirkulasi.

Drowned tube

Merupakan fire-tube atau water-tube yang sepenuhnya di bawah water-level dari boiler

yang beroperasi. Hal ini mengurangi keausan dan kebutuhan pemeliharaan, pada korosi

dan scaling yang paling aktif di wilayah tingkat air.

Exhaust injector

sebuah injektor air umpan yang irit konsumsi uap nya karna

menggunakan uap limbah, seperti knalpot mesin.

Field-tube

Suatu bentuk single-ended thimble tabung air dengan tabung internal

untuk mendorong sirkulasi.

Firebar

Bar besi replace-able yang membentuk dasar tungku dan mendukung api. Firebar ini

sering aus, sehingga dirancang untuk mudah diganti.

Fire-tube boiler

Sebuah boiler di mana pemanas utama adalah tabung dengan gas panas yang mengalir di

dalam dan air di luar.

Flue

Sebuah tabung api besar yang digunakan sebagai pemanasan permukaan utama dalam

boiler flued, atau digunakan sebagai firetubes yang diperbesar dalam boiler bergaya

lokomotif dimana mengandung unsur-unsur superheater.

Foundation ring

Dasar tungku, di mana kerangka dalam dan luar bergabung.

Fusible plug

Sebuah alat pengaman yang menunjukkan jika tingkat air menjadi sangat rendah. Plug ini

meleleh ketika terlalu panas, melepaskan jet uap ke dalam tungku dan mengingatkan kru

Galloway tubes

Tabung termis yang meruncing menyedot air untuk dimasukkan ke dalam tungku boiler

Lancashire.

Gauge glass

bagian dari alat pengukur tingkat air, yang biasanya terdiri dari tabung gelas vertikal

terhubung atas dan bawah dengan backplate boiler. Ketinggian air harus terlihat di dalam

kaca setiap saat.

Handhole

Manhole kecil yang berguna untuk inspeksi dan pencucian boiler.

Injector

Pompa air umpan yang tidak bergerak menggunakan tekanan uap dan efek Bernoulli

untuk mendorong air masuk sebagai umpan dalam boiller.

Klinger gauge glass

Berbentuk seperti gauge glass dimana water level dapat terlihat melalui jendela kaca

dengan frame metal yang kuat. Klinger gauge glass ini digunakan untuk boiler yang

memakai operator dan boiler tekanan tinggi.

Manhole

pintu oval akses ke shell boiler, digunakan untuk pemeliharaan dan pembersihan.

Manholes disegel dengan pintu removeable dari dalam. Karena mereka oval, pintu ini

dapat berbalik dan diangkat keluar melalui lubang tersebut. Pintu ini dijepit di tempat dari

luar dengan satu atau dua klem jembatan. Karna potongan pada manhole ini melemahkan

shell boiler, daerah sekitarnya diperkuat dengan patch.

Mud

Merupakan lumpur partikel skala boiler, endapan dan kotoran umum yang menumpuk di

bagian bawah boiler. Lumpur mengurangi sirkulasi air dan penumpukan lokal dapat

mengakibatkan overheating lokal dan mungkin ledakan.

Mud drum

Drum air, terutama yang dipasang rendah pada boiler yang berfungsi terutama untuk

mencegah lumpur dari peredaran.

Mudhole

Manhole kecil berguna untuk pembersihan boiler dari lumpur.

Rocking grate

Bentuk lanjutan dari firebar, di mana bagian dari grate yang dapat untuk memecah

klinker dalam api, atau untuk memadamkan api setelah satu hari kerja.

Safety valve

Katup otomatis yang digunakan untuk mengeluarkan kelebihan tekanan pada boiller.

Scale

Mineral terlarut dari air yang mengeras dan mengendap dalam ruang uap sekitar level air.

Bila scale ini jatuh ke bagian bawah boiler dan bercampur dengan kontaminan lain, hal

ini disebut lumpur.

Scum valve

Sebuah katup blow-down yang dipasang pada tingkat air dari boiler, digunakan untuk

mengalirkan minyak atau busa dalam boiler yang mengapung pada tingkat air.

Smokebox

Ruang tertutup pada fire-tube boiller dimana gas keluar dari tabung digabungkan dan

dilewatkan ke lorong.

Steam drum

Katup silinder dipasang pada tempat yang tinggi pada water-tube boiller dimana dry-

steam dapat berpusah diatas water-level sehingga dapat ditarik tanpa resiko priming.

Steam drum ini mirip dengan fungsi dome pada fire-tube boiller.

Steam & water drum

Drum uap yang mengandung campuran turbulent antara uap dan air dengan sebagian

substansialnya air.

Steam drier

bentuk superheater ringan yang menambah panas tambahan untuk uap basah atau jenuh,

sehingga memastikan bahwa semua air dalam uap air telah menguap, untuk menghindari

masalah dengan tetesan air dalam silinder atau turbin. Tidak seperti superheater, steam

drier tidak berusaha untuk menaikkan suhu uap secara signifikan melampaui titik didih.

Suction valve

katup non-return otomatis, yang akan terbuka bila tekanan boiler kurang dari tekanan

atmosfir. Hal ini untuk menghindari risiko vakum kolaps, ketika boiler panas teralu

mendingin

Throatplate

piring membentuk bagian depan bawah dari tungku luar boiler lokomotif, di bawah laras.

Top-feed

dalam boiler lokomotif, sebuah air umpan check valve ditempatkan pada bagian atas

drum boiler. Hal ini mendorong kecepatan pengadukan dari air umpan dingin dengan uap

panas, mengurangi risiko sengatan panas untuk bagian panas dari boiler.

Tubeplate

piring di laras fire-tube boiller, mengandung lubang kecil untuk menerima fire-tube.

Sebuah boiler lokomotif memiliki dua tubeplates: satu di bagian depan tungku dalam

(tubeplate tungku) dan satu di bagian depan boiler, berdekatan dengan smokebox

(smokebox tubeplate).

Water-wall

tungku atau dinding lain dalam lingkup boiler yang terdiri dari banyak set water-tube.

Tabung-tabung tersebut bisa gundul atau ditutupi oleh semen mineral.

Water-tube boiler

Boiler dimana pemanas utama adalah permukaan yang terdiri dari tabung kecil, diisi

dengan air. Tabung berdiameter 3 inci keatas disebut "large-tube" boiler. Belakangan

desain water-tube yang digunakan lebih kecil "small-tube" 2 inci atau kurang.