INTERNAL BOILER WATER TREATMENT (PRODUCT & CHEMISTRY)

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1 INTERNAL BOILER WATER TREATMENT (PRODUCT & CHEMISTRY)

2 Boiler Water Treatment
Untuk mencegah: Kerak/deposit Korosi Carry over Agar: Menjamin kontinutas tersedianya steam untuk operasi pabrik-meminimalkan downtime Safety Memproteksi biaya capital

3 Boiler Pre-Treatment Process Process Process Blowdown flash tank Flash
Low pressure steam Flash tank Condensate Receiver

4 Kerak/Deposit

5 Mekanisasi Pembentukan Kerak
Presiptitasi dari hardness yang tidak larut/ insoluble Ca(HCO3 ) Panas ---> CaCO3 + H2O + CO2 Mg OH > MgOH+ H2SiO > H+ + HSiO3- MgOH+ + HSiO > MgSiO3 + H2O Melebihi batas kejenuhan/kelarutan melalui evaporasi mengakibatkan terjadinya kristalisasi; contoh: CaSO4, SiO2

6 Boiler Deposit

7 Silica Membentuk deposit pada boiler/waterside
Terbentuk sebagai magnesium silicate atau silicic acid Selective silica carryover Tidak dapat dikontrol secara mekanikal dengan steam separator

8 Selective Silica Carryover
Silica terlarut pada steam Dikontrol dengan pembatasan kandungan silica pada air boiler Dikontrol dengan pembatasan tekanan operasi boiler Dikontrol dengan mempertahankan kontrol pH yang tinggi

9 Bentuk Kerak Besi/Iron
Kerak besi biasanya ditemukan dalam boiler sebagai salah satu atau lebih bentuk berikut: Bentuk kompleks dengan calcium Bentuk kompleks dengan phosphate Hematite Fe2O3 Magnetite Fe3O4

10 Efek Kerak Pada Heat Transfer

11 Efek Kerak pada Temperatur Pipa

12 Contoh Efek Kerak

13 Problem Kerak Boiler tube failure
Disebabkan karena pengurangan heat transfer dan tube overheating Under-deposit corrosion Disebabkan karena konsentrasi tinggi dari bahan bersifat korosif concentration of corrosive agents (dapat berupa NaOH)

14 Apa yang dapat dilakukan untuk mencegah kerak/deposit
Kontrol secara ketat terhadap kualitas air umpan (sesuai dengan batas kontrol) Mengaplikasikan internal treatment

15 Internal Treatment Options
Presipitasi kontaminan Pelarutan (solubilize) kontaminan Pendispersian (disperse) kontaminan Soluble contaminants are blowdown more easily than suspended contaminants Metal oxides are generally suspended material in the boiler water and must be dispersed to be removed by the blowdown

16 Program Internal Treatment Secara Umum/Konvensional
Coagulation programs Organic sludge conditioners Phosphate residual programs Phosphate-Polymer Programs Chelates & Chelate / Polymer programs All-Polymer program Coagulation treatment programs were commonly used in the past ( ). Today, modern, inexpensive pretreatment technology has made their use almost obsolete. Phosphate residual programs are best suited for feedwaters that are consistently below 60 ppm hardness, have low magnesium, and have silica content greater than one-third the magnesium content. Organic sludge conditioners: Tannins are particularly effective in conditioning sludge containing a high percentage of calcium carbonate. Normal application is treating high hardness feedwater for boilers operating below 400 psig (30kg/cm2); tannins are rarely used today. Lignins are stable at temperatures as high as 315 C and are effective in conditioning phosphate sludges as well as iron oxide. Starches are used when high feedwater silica levels result in abnormal quantities of silica-type chemical reaction products (sludges) Starches can also be used when oil contamination is a continuing problem. Polymers can be used alone or in combination with chelates or phosphates. Certain polymers have the capability of dispersing iron and silicates while sequestering calcium and magnesium. Phosphate-Polymer Programsare well suited to boilers with feedwater hardness levels of up to 3 ppm, and where concentrating mechanisms are suspect. They mormally give better results than conventional phosphate organic programs. Chelates&Chelate/Polymer Programs must be fed continuously into dearated feedwater. The presence of any oxygen increases the potential for corrosion by the chelating agent. Therefore, an oxygen must be fed ahead of the feed point of the chelating agent. All-Polymer programs (Transport-Plus) contain nochelates, phosphates, or phosphonate and require no supplemental dispersant to be effective. They offer superior performance over any other currently available programs.

17 Historical Overview of Nalco’s Internal Treatment Programs
Soda ash, Sodium Aluminate, and Phosphates Chelation Synthetic organic polymers Transport-Plus Soda ash, sodium aluminate, and phosphates, used with natural organics such as tannins or lignins, were among the first precipitating programs developed. These programs are used with higher hardness feedwaters, boilers then tend to be dirtier than the newer programs. Precipitating programs were not designed for iron control. Chelation as a means of hardness control through solubilization was the next type of program developed. Two chelates are generally used, nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA). This program offers superior cleanliness over phosphate programs, however it had a major weakness, the potential for corrosion if overfed or fed to a system containing dissolved oxygen. Synthetic organic polymers aided chelation programs, but they could not alter chelate’s corrosive nature. Transport-Plus was developed to offer the cleanliness of chelates without the potential for boiler corrosion, even if overfed.

18 ONDEO Nalco’s Internal Treatment Programs
Phosphate Residual Programs Phosphate Polymer Program All Polymer (Transport-Plus) Programs Supplemental Programs (dispersants and antifoam)

19 Program Pengendapan/Koagulasi

20 Perlakuan secara Koagulasi (Coagulation Treatments)
Calcium hardness dipresipitasikan sebagai Calcium Carbonate. Magnesium hardness dipresipitasikan sebagai Magnesium Hidroksida atau Magnesium Silicate The principles and mechanisms of coagulation programs have been well defined and tested over the years. Essentially, a coagulation program preferentially precipitates feedwater calcium hardness as calcium carbonate, while the feedwater magnesium hardness is preferentially precipitated as magnesium hydroxide or magnesium silicate. Feedwater calcium in either the bicarbonate or sulfate form is preferentially precipitated as calcium carbonate. Calcium sulfate scale can be completely inhibited by maintaining enough soda ash (Na2CO3) to completely react with the expected calcium sulfate levels entering the boiler via the feedwater. Maintaining a CO3-2 to SO4-2 ratio of greater than 0.01 in the boiler water will assure that the proper reaction takes place and that no calcium sulfate scale will form. A properly applied coagulation program further ensures this preferential reaction by incorporating a small amount of phosphate. The phosphate can react with calcium sulfate to preferentially precipitate tricalcium phosphate. Feedwater magnesium, either the bicarbonate or chloride form, is preferentially precipitated as magnesium hydroxide or magnesium silicate. Once the preferred precipitation reactions occur, the precipitated sludge must be conditioned so that it is free flowing and non-adherent. The addition of specific organic materials will control the crystal growth of the precipitated CaCO3 and Mg(OH)2. The controlled crystal growth allows the formation of large, flocculated suspended solids that can be easily removed by normal blowdown procedures. In summary, coagulation programs preferentially precipitate the feedwater calcium and magnesium hardness. The precipitated species are conditioned in the boiler water by organic chemicals that permit them to agglomerate and flow freely without adhering to the boiler metal surface. The conditioned sludge (reaction products) is then easily removed by blowdown.

21 Aplikasi Program Koagulasi:
Program Koagulasi dapat diaplikasikan bila; Tekanan operasi boiler < 350 psig Hardness feedwater/air umpan > 60 ppm Alkalinity air boiler < 500 ppm A coagulation program is best suited for low-pressure boilers (no greater than 350 psig; 24.5 kg/cm2) where the feedwater hardness is greater than 60 ppm. Because of the low-pressure, high feedwater hardness limitations, coagulation programs are rarely used today. To treat a feedwater with high sodium bicarbonate alkalinity, where alkalinity reduction is required to avoid exceeding the 500 ppm maximum "P" alkalinity, it is best to reduce the feedwater alkalinity externally using dealkalization or other conventional methods. Rarely, direct addition of sulfuric acid to the feedwater is used to reduce alkalinity. This method is dangerous, and requires exact control with automatic monitoring equipment.

22 Program Koagulasi Kekurangan: Kebaikan:
Dapat diaplikasikan untuk air umpan dengan kandungan hardness yang tinggi. Kekurangan: Cycle operasi boiler rendah TDS air boiler tinggi Jumlah blowdown banyak – pembuangan panas (wastes heat) Pembentukan kerak The main advantage of a coagulation program is its application in boilers that have extremely high feedwater hardness (60 ppm or greater). This program permits a plant to operate a boiler using high feedwater hardness without having to purchase pretreatment (softening) systems. On the other hand, the large amounts of TDS and suspended solids limit the cycles of concentration that may be carried; thus more blowdown is required. Increased blowdown is quite expensive in terms of energy and water lost. In addition, this type of program is more susceptible to scale formation. Coagulation treatment programs were commonly used in the past ( ). Today, modern, inexpensive pretreatment technology has made their use almost obsolete. The best solution to boiler scale is proper softening of the makeup water followed by a good chemical control program. Occasionally, this cannot be done, and for these situations, a coagulation program may be the best choice. By far the most common treatment technologies in use today utilize pre-softening to reduce residual hardness in the makeup to very low levels.

23 Calcium dipresitasikan sebagai calcium phosphate
Program Phosphate Calcium dipresitasikan sebagai calcium phosphate Magnesium dipresitasikan sebagai magnesium hydrosida Tricalcium phosphate has an extremely low solubility. Hence, when properly controlled, the addition of phosphate to boiler water removes calcium so completely and efficiently that calcium sulfate, calcium carbonate, and calcium silicate scales can be prevented. In the presence of sufficient alkalinity, the actual phosphate precipitate formed is hydroxyapatite, which is a less sticky, more readily conditioned reaction product than tricalcium phosphate. Although phosphates can also precipitate magnesium as magnesium phosphate, proper boiler chemistry will preferentially precipitate magnesium as a less adherent and more easily conditioned magnesium hydroxide or magnesium silicate. The hydroxide can come from added sodium hydroxide, for waters low in alkalinity, or from the decomposition of naturally occurring carbonate and bicarbonate alkalinity.

24 Phosphate Technology Ortho phosphates
Mono-, di-, tri- sodium phosphates Poly Phosphates Sodium hexa meta phosphate Sodium hepta meta phosphate Sodium tripoly phosphate Tetra sodium pyro-phosphate Phosphate residual programs are acceptable where makeup hardness is less than 60 ppm. Numerous chemicals can furnish the phosphate radical necessary for internal softening treatment; compounds of the orthophosphate ion, PO4-3 (mono-, di-, and trisodiurn phosphates), are the most widely used. Other phosphate ions are meta (PO3-) and pyro (P2O7-4). Some of these salts are called polyphosphates because they form inorganic polymers. Among these are the glassy sodium polyphosphates (hexa- and heptametaphosphate) and crystalline sodium polyphosphates such as sodium tripolyphosphate and tetrasodium pyrophosphate. The meta- and pyrophosphates can be described as molecularly dehydrated phosphates. When added to water, these phosphates 're-hydrate" (at a rate that is temperature-dependent) to the orthophosphate form from which they were derived. Although this discussion of phosphates is rather limited, it is a reminder that the precipitation of tricalcium phosphate (or hydroxyapatite) in the boiler can occur only when the phosphate in use has been converted to trisodium orthophosphate by heat and reaction with boiler alkalinity. This is true for all phosphate treatment for calcium scale control. This slide is not an all inclusive list of phosphate types in use: there are others. However, all are classed as ortho or poly phosphates.

25 Phosphate Technology Titik Injeksi Ortho phosphate
Diinjeksikan lansung ke drum boiler Poly phosphate Diinjeksikan ke line air umpan

26 Phosphate Technology Kelebihan Mudah dimonitor dan dikontrol
Tidak memerlukan air umpan dengan kemurnian tinggi Dapat diaplikasikan pada boiler tekanan tinggi Dikenal luas Memiliki perizinan FDA dan USDA Fluktuasi hardness air umpan dapat ditangani Residual PO4 tidak bersifat korosif PO4 residual yang tinggi - buffer untuk ekskursi Biaya relatif murah 1. Easy to monitor and control - test equipment is cheap, easy to use and readily available. Testing is easy for operators to use with accuracy. 2. Do not require "ultrapure" feedwater: program can tolerate some hardness 3. Can be used at high pressure up to about 1200 psig, but use is normally with pressures below 600 psig 4. Well understood and accepted by industry. These programs have been in use for some years, and considerable experience exists with their use. 5. Many types of phosphate can be FDA/USDA approved 6. Can handle fluctuations in feedwater hardness, but this should not be construed as a license to ignore the requirement for good control of pretreatment softening equipment. 7. Residual PO4 is noncorrosive to boiler metal. 8. Carry large PO4 residuals, so there is more room for feedwater quality excursions should they “accidentally” occur. 9. Less expensive ingredients mean overall lower program cost compared to some other technologies.

27 Phosphate Technology Kekurangan
Menghasilkan presipitasi/endapan pada sistem Kelebihan alkalinity dapat menyebabkan korosi Memerlukan lebih banyak blowdown Jika demikian, lebih banyak panas hilang dan lebih banyak pemakaian bahan kimia Kemungkinan dapat menyebabkan terjadi kerak Umumnya diaplikasikan bersama sludge dispersant 1 . Precipitates of calcium carbonate and magnesium hydroxide can result in scaling and deposition, BTU losses, tube overheating and failure 2. Excess alkalinity can result in caustic corrosion in some units. In units with severe concentrating mechanism, especially when combined with high heat flux, there can be a high localized concentration on caustic soda which can cause caustic gauging 3. May require more blowdown (lower boiler water concentrations); this results in greater BTU, chemical, and water losses 4. Causes suspended solids, therefore supplemental dispersant is necessary

28 Phosphate Technology Detailed Chemistry
(poly) Na5P3O NaOH -> 3Na3PO H2O (ortho) Na2HPO4 + NaOH -> Na3PO4 + H2O 3CaCO Na3PO4 -> Ca3(PO4)2 + 3Na2CO3 3CaSO Na3PO4 -> Ca3(PO4)2 +3Na2SO4 Mg(HCO3) NaOH -> Mg(OH) Na2CO H2O MgCl NaOH -> Mg(OH) NaCl

29 Sludge Conditioning Padatan Calcium Phosphate dan Magnesium Hydroxide yang tidak terlarut terbentuk (Sludge) Particulate Iron Oxide kembali ke kondensat Padatan mengendap pada permukaan panas boiler Transfer panas tidak seimbang, dapat beresiko pipa pecah

30 Tipe Sludge Conditioners
Synthetic polymers Tannins Lignins Starches

31 Pengaplikasian Sludge Conditioners
Produk Starch Organic Jika Mg:SiO2 ratio < 2 Jika minyak mengkontaminasi air boiler Dalam pabrik pengolahan makanan Produk Lignin Organic Untuk mengkondisi Calcium Phosphate & Iron Oxide

32 Titik Injeksi Sludge Conditioners
Tangki Deaerator Jalur air umpan boiler Lansung ke steam drum

33 Solubilizing Program

34 Chelants Melarutkan ion logam
Membentuk senyawa kompleks yang sangat larut Ion-ion bersaing (PO4, SiO2, OH) mengurangi efetivitas

35 Chelant yang Umum EDTA (Ethylene diamine tetracetic acid)
Memiliki 6 sisi logam kompleks termasuk atom nitrogen dan oksigen NTA (Nitrilo triacetic acid) Memiliki 4 sisi logam kompleks

36 Perbandingan Kedua Jenis Chelant
NTA lebih stabil secara thermal 900 psig max. untuk NTA, 600 psig max. untuk EDTA Biaya NTA lebih murah dari pada EDTA EDTA memkompleks Magnesium lebih baik dari pada NTA EDTA memkompleks besi lebih baik dari pada NTA EDTA memiliki perizinan FDA

37 Aplikasi Chelants Harus diinjeksikan secara kontinu pada jalur air umpan memakai injection quill & piping stainless steel Tidak boleh ada oksigen Konsentrasi residual pada air boiler harus dijaga di bawah 10 ppm sebagai CaCO3 untuk meminimalkan korosi Akurasi kontrol pemakaian diperlukan

38 Chelant Control Ranges
Boiler Pressure Chelant Residual psig (Bar) ppm as CaCO3 400 (30) ( ) ( )

39 Kelebihan Chelant Tidak terbentuk endapan
Permukaan perpindahan panas lebih bersih Frekwensi acid cleaning lebih sedikit Terkadang dapat mengurangi jumlah blowdown

40 Kekurangan Chelant Biaya lebih mahal
Memerlukan kontrol yang sangat ketat terhadap mutu air umpan Lebih sulit untuk test kontrol Residual berlebih bersifat korosif Ion-ion yang bersaing dapat bersifat korosif

41 Program Phosphate-Polymer
Mempresipitasikan hardness dan besi Polymer mendispersikan sludge hasil reaksi, untuk menghindari pengendapan pada pipa Boiler lebih bersih daripada program phosphate konvensional

42 Aplikasi Program Phosphate-Polymer
Hardness air umpan lebih rendah dari 3 ppm Softener atau air baku dengan hardness rendah

43 Program Phosphate-Polymer
Kelebihan Perizinan FDA/USDA Dapat diaplikasikan pada air umpan dengan T.hardness tinggi. Boiler lebih bersih Lebih mudah ditest/dikontrol. Tidak mahal. Tidak bersifat korosif Disadvantage Requires much stricter control of feedwater hardness and chemical program

44 Program Phosphate-Polymer
Kekurangan Memerlukan kontrol yang ketat terhadap hardness air umpan dan residual bahan kimia

45 Program All-Organic Polymer
All-polymer program, polymeric blend Tidak mengandung chelant atau phophate, tidak memerlukan tambahan dispersan Berfungsi dengan melarutkan Calcium & Magnesium dan mendispersi besi dan partikulat lainnya Tidak bersifat agresif terhadap metal boiler

46 Program All-Organic Polymer
Diinjeksikan ke tangki deaerator untuk boiler bertekanan < 600 psig dan menggunakan air softener Program/dosis injeksi berdasarkan batas atas kontrol untuk hardness dan besi, bukan nilai rata-rata Kekurangan dosis (<20% dari yang diperlukan) dapat membentuk deposit Calcium Acrylate pada boiler

47 Program All-Organic Polymer
Tidak bersifat korosif untuk internal boiler Memberikan hasil boiler yang lebih bersih - clean boilers – meningkatkan heat transfer Transport 100% of hardness Tidak bersifat volatil – aman untuk turbin Hardness air boiler dapat ditest Test produk sederhana/mudah Program passivasi yang baik

48 Program All-Organic Polymer
Pengaplikasian terbatas untuk tekanan boiler <1000 psig Memerlukan air umpan dengan hardness rendah Beberapa formulasi mengkontribusikan ammonia ke steam

49 Definisi Korosi 2 e- + 1/2 O2 + H2O <---> 2OH-
Korosi adalah proses elektrokimia, dimana metal (teroksidasi) kembali ke bentuk alamiahnya (natural state). Sell Korosi (corrosion cell) : anoda, katoda dan elektrolit harus ada 2 e- + 1/2 O2 + H2O <---> 2OH- 2OH- + Fe <---> Fe(OH) e- Cathodic (reduction) half cell reaction Anodic (oxidation) half cell reaction

50 Korosi pada Boiler Tipe korosi Korosi akibat oksigen/oxygen corrosion
Konsentrasi alkalinity/alkalinity concentration Korosi akibat caustic/caustic corrosion Korosi akibat asam/Acid corrosion Korosi akibat chelant/Chelant corrosion Erosi/korosi Corrosion can occur throughout a boiler system. The most common causes of corrosion are the shown on this slide. Different kinds of corrosion are found in different parts of the boiler. Corrosion in boiler systems is not a simple matter to define because the various chemistries involved are often interrelated and complex. Corrosion of boiler metal is generally considered to be one of two types: general corrosion or localized corrosion. General corrosion is a uniform attack of the metal surface resulting in a slow, even wastage of the boiler metal. General corrosion does not normally result in enough metal loss to cause tube or wall thinning and subsequent tube failures. Localized corrosion results in a fairly rapid and severe metal loss in a small, localized area. Such corrosion results in gouge or pitting attack that can cause tube failures in a very short time. The concentrating corrosion mechanism ( such as may be found under iron oxide deposits) is an example of severe, localized corrosion.

51 Korosi Akibat Oksigen Oksigen yang terlarut di air merupakan materi dasar terjadinya reaksi di katoda

52 Korosi Akibat Oksigen ANODE: Natural Metal Electrically Charged Metal Electrons Fe0 Fe e- CATHODE: Electrons Oxygen Water Charged Ion 2e /2 O2 + H2O 2(OH-) Hydroxyl Ions Form Corrosion Products Hydroxide or Oxide OH- O2 Metal Ions Dissolve Oxygen corrosion is an electrochemical process. Iron dissolves at the anodes, releasing electrons that are subsequently consumed by oxygen at the cathode. Pits occur where metal leaves the surface. Above picture misrepresents the pitting process slightly for clarity. - The actual accumulation or tubercle formed from corrosion products usually covers the pit rather than being located adjacent to it. High flow rates will increase the corrosion rate because the reactants are brought in contact faster and corrosion products are also scoured away faster. Active Anodic Area Less Active Cathodic Area Electron flow

53 Korosi akibat Oksigen/Oxygen Corrosion
Dapat terjadi pada sepanjang sistem Mekanisme sama seperti sel korosi akibat oksigen Mekanisme korosi dipengaruhi oleh: Konsentrasi oksigen Temperatur pH Oxygen corrosion can be found throughout the boiler cycle from the deaerator to the final condensate system. The basic chemical mechanism is the same as that found in most waters where oxygen exists in the presence of iron. It produces a very severe localized corrosion. Three variables affect the corrosivity of oxygen: oxygen concentration, temperature, and pH. As the temperature or oxygen concentration increase, the corrosion rate accelerates. pH and oxygen corrosion are inversely related: as the pH increases, the oxygen becomes less corrosive. This is one reason that alkaline conditions are preferable for boiler waters.

54 Korosi Akibat Oksigen

55 Bahan kimia : Oxygen Scavenger
Korosi Akibat Oksigen Bahan kimia : Oxygen Scavenger

56 Oxygen Scavenger yang Umum Dipakai
Sulfite Hydrazine Hydroquinone DEHA (Diethyhydroxylamine) MEKO (Methylethylketoxime) Carbohydrazide Erythorbic acid Chemical scavengers are reducing agents that react directly with dissolved oxygen. The reaction products are removed through boiler blowdown or system venting. Chemical oxygen removal is the last opportunity to prevent oxygen from entering the boiler. Nalco offers four types of oxygen scavengers that are:- Sulfite Hydrazine ELIMIN-OX SUR-GARD

57 ONDEO Nalco’s Oxygen Scavengers
Sulfite/Catalyzed Sulfite Carbohydrazide (Elimin-Ox) Erythorbic acid (SUR-GARD) ONDEO Nalco Patents Nalco offers four types of oxygen scavengers that are:- Sulfite/ Catalyzed sulfite ELIMIN-OX SUR-GARD

58 Sodium Sulfite - Inorganic Oxygen Scavenger
2Na2SO3 + O > 2Na2SO4 8,6 ppm per 1 ppm oxygen terlarut Pada temperatur kamar sodium sulfite mengurangi oxygen sebesar 30 % dalam 10 menit Pada temp.> 120 oC, masih dibutuhkan waktu reaksi lebih dari 30 detik Di atas 150 °C ,oxygen mengkorosi permukaan metal/besi lebih cepat dari pada waktu reaksi sulfite dengan oksigen Sodium sulfite is used to remove dissolved oxygen from the boiler feedwater. Oxygen removal reduces the potential for corrosion in the feedwater and boiler system. When operating properly, spray and tray type deaerators are capable of mechanically reducing the level of dissolved oxygen to less than 7 ppb. However, even at trace levels, dissolved oxygen is extremely corrosive and must be removed. Sodium sulfite reacts with, “scavenges”, the dissolved oxygen, and forms harmless products that are removed through boiler blowdown. Sodium sulfite (Na2SO3) is a reducing agent that chemically scavenges dissolved oxygen by reacting directly with it. Since the presence of dissolved oxygen helps drive the corrosion cell, its removal can shut down the corrosion mechanism. Reducing oxygen corrosion will help control boiler water iron levels and the insulating corrosion products that result. Catalyzed sulfite is preferred to uncatalyzed sulfite because of the very short reaction times available in boiler feedwater systems. Catalyzed Sulfite ( dengan katalis Cobalt Salt ) lebih baik

59 Kelebihan Sulfite Reaksi cepat Lebih murah Lebih mudah dianalisa
Perizinan FDA/USDA Overfeed of catalyzed sodium sulfite will: 1. Result in excessive energy loss due to the increased blowdown caused by high levels of dissolved solids; 2. Significantly increase the cost of the treatment program. Underfeed of catalyzed sodium sulfite will result in serious corrosion.

60 Kekurangan Sulfite Menambah solid/padatan ke air boiler
Kemungkinan dapat menambah jumlah blowdown Tidak ada efek passivasi pada metal boiler Tidak sesuai untuk boiler dengan tekanan operasi > 600 psi (40 bar) Terurai menjadi H2S & SO2 Overfeed of catalyzed sodium sulfite will: 1. Result in excessive energy loss due to the increased blowdown caused by high levels of dissolved solids; 2. Significantly increase the cost of the treatment program. Underfeed of catalyzed sodium sulfite will result in serious corrosion.

61 Elimin-Ox Oxygen Scavenger Bersifat volatil/tidak menambah solid
Mempasivasi permukaan metal Elimin-Ox is an all-volatile oxygen scavenger developed in response to concerns associated with handling hydrazine. Elimin-Ox is used to both remove dissolved oxygen, as well as enhance metal passivation. Oxygen removal reduces the potential for corrosion in the feedwater and boiler system.

62 Reaksi Elimin-Ox Elimin-Ox * + 2O2 2N2 + 3H2O + CO2** + 2O2 2N2 + 4H2O
+ 2N2H4 + CO2** Elimin-Ox helps complete the deaeration process by chemically removing the trace levels of dissolved oxygen remaining after mechanical deaeration. At low temperatures (<150oC) Elimin-Ox reacts directly with dissolved oxygen. At higher temperatures (>150oC) Elimin-Ox forms hydrazine which reacts directly with oxygen as follows: N2H4 + O2 ---> H2O + N2 2NH3 + N2 + H2 >205 C * As Carbohydrazide ** Maximum 29 ppb/ppm Elimin-Ox Fed

63 Sur-Gard Non-volatile Oxygen Scavenger Menghilangkan Dissolved Oxygen
Mengurangi potensi korosi Bereaksi dengan oksigen secara kimiawi Mempasivasi permukaan metal Food Grade Approval SUR-GARD is a non-volatile oxygen scavenger. SUR-GARD is used to both remove dissolved oxygen, as well as enhance metal passivation. Oxygen removal reduces the potential for corrosion in the feedwater and boiler system. SUR-GARD helps complete the deaeration process by chemically removing the trace levels of dissolved oxygen remaining after mechanical deaeration. SUR-GARD also helps prevent corrosion by passivating the metal surfaces in the feedwater section of the boiler system.

64 Surgard, Eliminox - Organic Oxygen Scavengers
Kelebihan Tidak menambah solid/padatan ke air boiler, sehingga tidak menaikkan jumlah blowdown. Mempasivasi permukaan metal, sehingga dapat melindungi dari korosi. Surgard sudah diizinkan FDA/USDA Kekurangan Reaksi lebih lambat Lebih mahal

65 Hydrazine N2H4 + O2 ---> 2 N2 + 2H2O
toxic material - safe storage and handling issues become paramount N2H4 + O > 2 N H2O 3 N2H4 ---> 4 NH3 + N2 at temp. > 390°F (200°C)

66 C6H4(OH)2 + 1/2O2 ---> C6H4O2 + H2O
Hydroquinone reacts quickly with oxygen at room temperature decomposition -> acetates, CO2, and H2O some toxicity issues C6H4(OH) /2O2 ---> C6H4O2 + H2O

67 Diethylhydroxylamine
volatile neutralizing amine hydroquinone may be added to increase low temp. scavenging rate decomposition > 148°C (300°F) is rapid (seconds) acetic acid, CO2, acetaldehyde, ethylamine, low mwt organics, and NH3 at temperatures above 275°C 4 (CH3CH2)2NOH O2 ---> 8 CH3COO H+ + 2N H2O

68 Condensate System Pre-Treatment Process Process Process
DEAERATOR Process Process The steam/condensate system extends from the boiler all the way back to the deaerator. Blowdown flash tank Low pressure steam Flash tank Condensate Receiver

69 Condensate Corrosion Destroys capital equipment
repair, maintenance, loss of efficiency Can affect end products if condensate contacts final products Will lead to increased boiler deposits of corrosion products (metal oxides)

70 Primary Causes of Condensate Corrosion
Carbon dioxide Oxygen Ammonia Above are the primary corrodents in condensate. Specific systems may also need to deal with miscellaneous other contaminants: organic acids SO2/H2S from sulfite decomposition or process contamination

71 Condensate Corrosion Carbonic acid corrosion
dissolved carbon dioxide and the resulting carbonic acid, is the most common source of condensate corrosion CO2 + H2O <---> H2CO3 <---> H+ + HCO3- Fe + 2 H HCO > Fe(HCO3)2 + H2

72 Condensate CO2 Corrosion
Sources of CO2 thermal decomposition of carbonate alkalinity in the boiler in-leakage of air into the condensate system 2 NaHCO3 ---> Na2CO3 + CO2 + H2O Na2CO3 + H2O <---> 2 NaOH + CO2

73 Condensate CO2 & O2 Carbonic acid and oxygen
in the presence of oxygen 2 cathodic reactions are possible oxygen may react with other corrosion products 2 Fe + O2 + 4H+ ---> 2 Fe H2O 4 Fe+2 + O2 + 4H+ ---> 4 Fe H2O 4 Fe(HCO3)2 + O2 ---> 2 Fe2O3 + 4H2O + 8 CO2

74 Chemical Condensate Treatment
Neutralizing amines Filming amines ACT Program Chemical treatment programs for steam/condensate systems come in three varieties. No matter which treatment program is used, it has to be able to distribute through the steam/condensate system to the point of condensation.

75 Neutralizing Amines Neutralizes carbonic acid and increases pH
Effective against other acids Neutralizing amines react with all acids. It is not uncommon to see amine usage increase in an account for, seemingly, no good reason. Often, some kind of organic contamination has occurred. This can be something as simple as a cleaner leaking into a condensate system. When these organics break down in the boiler, volatile organic acids are formed which leave with the steam, condense in the condensate system and depress pH. A neutralizing amine will neutralize these acids the same way carbonic acid is neutralized.

76 RNH2 + H2CO3 ---> (RNH3)+ + (HCO3)-
Neutralizing Amines Neutralization of carbonic or other acids Basicity or pKa cyclohexylamine 10.6 diethylaminoethanol morpholine RNH2 + H2CO > (RNH3)+ + (HCO3)- pKa is a function of solution temperature keep pH above 8.8

77 Simple Acid/Base Neutralization
Amine hydrolysis in water: R-NH H2O « R-NH OH- Neut. amine water Neut. amine hydroxide CO2 hydrolysis in water: CO H2O « H2CO3 « H HCO3- carbon dioxide water carbonic acid bicarbonate Net reaction: R-NH H2CO3 « R-NH HCO3- Neut. Amin carbonic acid Neut. amine bicarbonate Neutralizing amines react with CO2 by means of a simple acid/base neutralization reaction. The amine hydrolyzes in water to generate a captive OH- (hydroxide). Likewise, the CO2 hydrolyzes in water to generate carbonic acid. Carbonic acid is very unstable in water and quickly dissociates to H+ (acid molecule) and bicarbonate. The net result of the two reactions is amine bicarbonate. When feeding only neutralizing amines, we typically feed for a slight excess of amine. The OH- generated then serves to raise the pH.

78 Optimum pH Control Increases copper corrosion Increases mild
steel corrosion Neutralizing amines do not directly address corrosion caused by oxygen. However, copper and iron corrosion product solubilities are very low at a pH of approx As a result, corrosion products precipitate and form a semi-protective layer at the surface. This also decreases oxygen diffusion rate to the metal surface, again limiting the corrosion rate. An all-neutralizing amine program is not the best choice in high alkalinity waters because it can easily be cost prohibitive. Most systems will require a blend of several amines to assure proper protection of the entire system. 8.0 8.5 9. 2 Optimum pH

79 a blend of amines is typically required
Neutralizing Amines a blend of amines is typically required Amine A Amine B Neutralizing amines can be characterized by following: The V/L ratio which is the amount of amine in the vapor or steam vs the amount in the liquid or condensate. This characteristic determines how well the amine distributes through the system. The molecular weight and basicity affect the amine’s strength. These characteristics determine how many kgs of amine are required to neutralize or treat a kg of CO2. We usually feed blends of amines to obtain the desirable characteristics required to treat an extensive, complicated condensate system. Prefer Vapour Prefer Water

80 Disadvantages Not effective against oxygen corrosion
Expensive in high alkalinity systems Distribution can cause problems a blend of amines is typically required Difficult to test Neutralizing amines do not directly address corrosion caused by oxygen. However, copper and iron corrosion product solubilities are very low at a pH of approximately As a result, corrosion products precipitate and form a semi-protective layer at the surface. This also decreases the oxygen diffusion rate to the metal surface, again limiting the corrosion rate. An all-neutralizing amine program is not the best choice in high alkalinity waters because it can be cost prohibitive. (1 molecule of amine for every molecule of CO2.) All systems will benefit from a blend of several amines to assure protection of the entire system.

81 Filming Amines Long chain amines that absorb onto the metal surface
Function at the lower pH range of 6.5 to 9.0 O2 CO2 O2 O2 CO2 O2 CONDENSATE O2 O2 CO2 O2 CO2 O2 O2 Filming amines build a protective barrier layer between the metal surface and the aggressive condensate Neutralizing amines are typically fed in conjunction with neutralizing amines, since the pH must be between 6.5 to 9.0 for film formation to occur. The ideal pH (optimum corrosion protection) occurs in the pH range 7.5 to 8.0. CO2 O2 O2 CO2 CO2 CO2 O2 CO2 Metallic wall Protective filming amine layer

82 A filmed metal surface promotes dropwise condensation

83 Filming Amines Protect against acids, O2, and ammonia
Dosage dependent on surface area and not contaminant concentration Cost effective in high CO2 systems Because filming amines do function by formation of a barrier layer, they are effective against most condensate contaminants; i.e acids, oxygen, and ammonia. They also effectively protect against air-in-leakage. They are cost effective for high alkalinity and low % condensate return.

84 Filming Amines Limitations/Considerations
Film formation takes time pH control still necessary Overfeed may cause sticky deposits and “gunk” ball formation Should be fed after turbines and condensate polishers Will clean up old deposits But if they were so wonderful, everyone would be using filming amines. And they’re not. Filming amines do have several significant drawbacks as shown above. Note following in addition to above: pH > 9 causes the film to strip pH<6.5 causes the amine not to film Filmers have very low V/L ratios and can have problems distributing throughout the system.

85 Advanced Condensate Treatment (ACT)
ACT is an innovative condensate corrosion program that uses new technology to prevent operational problems.

86 Innovative Approach Brand New Approach! Instead of neutralizing carbonic acid or using a filming amine, Nalco researchers discovered safe emulsifiers which provide a barrier to corrosion in the condensate system.

87 So Safe, it is in the stuff you eat ...
Nalco’ ACT program is made from food grade materials used in many food products. The ACT program has received U.S. FDA clearance under 21 CFR Part 173 for Secondary Direct Food Additives Permitted in Food for Human Consumption; Boiler Water Additives.

88 Provides Safe Corrosion Barrier to Metal Surfaces
no filmer

89 It serves the regulatory needs It serves the safety needs
ACT Program It serves the regulatory needs It serves the safety needs It serves the technical needs It serves the economic needs Under ordinary circumstances, only facility managers and engineering staffs concern themselves with the implications of improper boiler water treatment. With respect to regulatory issues and condensate treatment, wider awareness is important. An amine-related problem certainly affects more than the engineering staff. It also affects all people working around the plants. The symptoms of exposure to amines are nausea, vomiting, dizziness and the like. Amines can be introduced inhalation, ingestion, absorption through the skin and skin and eye contact. Obviously, the higher the level of exposure, the more serious the potential risk. In worst cases, exposure to amines can cause liver and kidney damage and a variety of respiratory problems. Less often, concern is raised not because someone has been exposed to a high concentration of amines, but because of the application of the steam treated with amines. The areas of concern are: 1. Food Processing Plants regulated by the Food & Drug Administration (FDA) 2. Meat, Poultry and egg processing plants regulated by the USDA 3. Hospitals where the steam is used for the preparation of food, sterilization of surgical instruments or direct humidification of room air 4. Offices and other types of buildings where steam is used for heat or humidification. Reportable quantities - In some states in the USA and some countries, there have been restriction limited the amount of hazardous chemicals in the system or even limit amount of spilled chemical. ACT fills in the technical gaps which conventional amines treatment cannot succeed. Our customers want to buy products that work, deliver REAL value and provide a quantifiable ROI!

90 Benefits Effective against carbonic acid
Effective against oxygen corrosion Effective against erosion corrosion Easy to test for Dosage dependent on surface area and not contaminant concentration Cost effective in high CO2 systems Operate at lower pH and not alter pH We know there is technical gap that the existing amine products cannot fill in. Here are some properties that ACT can add more value. When feed is interrupted, typical neutralizing amine cannot adequately protect the system due to a rapid drop of pH. The typical filming amine protection is also decrease while the film move off. In some applications or industries, it does not allow the contamination of nitrogen with some system for example refining. Unlike typical filming amine, ACT does not bond to itself that can cause gunk ball. ACT, unlike typical filming amine, has no cleaning property that remove the corrosion products before filming on to the surface.

91 Disadvantages Must be fed to the steam header Not volatile
Same as other filmers, ACT needs to be fed directly to steam header. It is not volatile, therefore, flash steam areas require satellite feed