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Iran Glass Industry - کربنات سدیم
تاريخ : سه شنبه هفدهم دی 1392 | 0:46 | نویسنده : علیرضا حسینی
واردات کربنات سدیم با قیمت مناسب

hebesaler@gmail.com




تاريخ : چهارشنبه چهارم اردیبهشت 1392 | 0:14 | نویسنده : علیرضا حسینی
خط جدید تولید کربنات سدیم در مراغه بومی‌سازی و وارد چرخه تولید شد

 مدیرعامل مجتمع کارخانجات کاوه سودای مراغه گفت: برای نخستین بار در کشور خط جدید تولید کربنات سدیم در مراغه بومی‌سازی و وارد چرخه تولید شد.

علی حسنی  اظهار کرد: پس از تحریم‌ها و پشتیبانی نکردن سازندگان آلمانی، ایتالیایی و چینی کارخانه کربنات سدیم مراغه فرصتی فراهم کرد تا مهندسین ایرانی خط تولید و قطعات اساسی این کارخانه را بومی‌سازی کنند.

وی افزود: متخصصان کارخانه کربنات سدیم مراغه در این کارخانه علاوه بر طراحی خط جدید به ظرفیت 200 هزار تن در سال 15 قطعه اساسی بخش‌های مختلف این کارخانه را بوی‌سازی کرده‌اند.

حسنی با بیان اینکه بومی‌سازی خط تولید و قطعات این کارخانه علاوه بر قطع وابستگی به بیگانگان از خروج ارز از کشور جلوگیری کرده است، افزود: برای راه‌اندازی خط جدید 20 میلیارد ریال هزینه شده است.

وی هزینه واردات خط کربنات سدیم از آلمان و ایتالیا را 200 میلیارد ریال اعلام کرد.

مدیرعامل مجتمع کارخانجات کاوه سودای مراغه در ادامه گفت: موفقیت‌آمیز بودن خط جدید تولید کربنات سدیم در مراغه موجب شده متخصصان این کارخانه ساخت کارخانه کاملا ایرانی را در استان فارس آغاز کنند.

حسنی افزود: خط تولید کارخانه کربنات سدیم استان فارس در مراغه در حال طراحی و ساخت است.

کارخانه کربنات سدیم مراغه بزرگ‌ترین کارخانه تولید کربنات سدیم کشور است،

با راه‌اندازی این کارخانه در سال 84  ایران اسلامی از واردات این محصول بی‌نیاز و به صادر کننده کربنات سدیم تبدیل شده  است

تاريخ : چهارشنبه پنجم مهر 1391 | 13:14 | نویسنده : علیرضا حسینی

سدیم کربنات در آب محلول است. اما به طور طبیعی در بخش های خشک، به خصوص در رسوب های معدنی شکل گرفته از تبخیر آب دریاچه ها یافت می شود. رسوبات معدنی نمک های قلیایی طبیعی، ترکیبی از سدیم کربنات و سدیم بی کربنات است که از کف دریاچه های خشک شده موجود در مصر از زمان های گذشته استخراج می شده است تا در تهیه مومیایی و نیز ساخت ابتدایی شیشه استفاده شوند. سدیم کربنات به سه صورت ترکیب هیدراته شناخته شده است: سدیم کربنات 2 آبه، سدیم کربنات 7 آبه و سدیم کربنات تک آبه.

Trona یعنی سدیم بی کربنات کربنات 2 آبه، در مناطق مختلفی از ایالات متحده استخراج می شود و تمام سدیم کربنات نیاز داخل را تامین می کند. رسوبات عظیم و طبیعی از آن در سال 1938 در نزدیکی Green River یافت شد و استخراج معادن در آمریکای شمالی بیشتر با توجه به جنبه اقتصادی و نه تولید صنعتی صورت گرفت. این ماده از دریاچه های قلیایی نیز به دست می آید، همچون دریاچه ی Magadi در کنیا که البته با استفاده از فرایند لاروبی از روش های ابتدایی به دست می آید و به طور طبیعی تجدید می شود و بنابراین هیچ گاه این منبع طبیعی پایان نمی پذیرد. Barilla & Kelp بسیاری از انواع گیاهانی که در آب های شور زیست می کنند و در مقابل آب شور مقاومند می توانند انواع ناخالص سدیم کربنات را به ما بدهند و این منابع شکل رایج و کنونی مورد استفاده در اروپا و سایر مناطق تا قرن 19 بود. گیاهان خشکی زی مانند درخت اشنا و نیز علف شوره یا خزه و جلبک های دریایی ابتذا جمع آوری شده و پس از خشک کردن سوزانده می شدند. خاکستر حاصل با آب شسته می شد تا محلول قلیایی تشکیل شود. این محلول پی از جوشانده شدن و خشک شدن محصول نهایی را به ما می دهد که Soda Ash نامیده می شود. این نام قدیمی برگرفته از منبع اولیه ی گیاهی آن است که یک بوته یک ساله به نام Salsola soda (barilla plant) است. غلظت سدیم کربنات موجود در Soda Ash بازه گسترده ای دارد، از 3-2% موجود در “kelp” که خزه و جلبک به دست می آید تا تا 30% موجود در بهترین “barilla” که از گیاهان علف شوره موجود در اسپانیا به دست می آید. منابع گیاهی و جلبک مورد استفاده برای Soda Ash، و نیز برای پتاس های قلیایی مرتبط، به طور افزاینده ای تا پایان قرن 18 ناکافی به نظر می رسیدند. و جستجو برای یافتن راه های تجاری و پایدار برای ساخت و سنتز این ماده از نمک ها و سایر مواد شیمیایی روز به روز گسترش می یافت.

در سال 1791، شیمیدان فرانسوی نیکلاس لبلنک روشی نوین را برای تولید سدیم کربنات از نمک، سولفوریک اسید، و ذغال سنگ به ثبت رساند. نخست نمک دریایی(سدیم کلرید) در سولفوریک اسید جوشانده می شد تا سدیم سولفور و گاز هیدروژن کلرید تولید شود. همچنان که در واکنش زیر مشاهده می کنید. 2nacl+… سپس، مخلوط سدیم سولفور با سنگ آهک خرد شده( کلسیم کربنات) و ذغال حرارت داده می شد تا سدیم کربنات به همراه کربن دی اکسید و کلسیم سولفور حاصل شود.

سدیم کربنات از عصاره گیری خاکستر و آب به دست می آمد، و با تبخیر آب موجود، جمع آوری می شد. هیدروکلریک اسید حاصل از فرایند لبلنک، یکی از منابع اصلی آلودگی هوا است و کلسیم سولفید که به عنوان یک محصول جانبی تلقی می شود یک فرآورده بیهوده می باشد. البته با این توصیفات، روش اصلی تولید سدیم کربنات تا اواخر دهه ی 1880 همین روش فوق الذکر بود.

در سال 1861، یکی از شیمیدانان صنایع بلژیک، ارنست سولوای، روشی را معرفی کرد که سدیم کلرید با استفاده از آمونیاک به سدیم کربنات تبدیل می شود. این فرایند در یک برج بزرگ میان تهی صورت می گیرد و در انتهای این برج کلسیم کربنات (سنگ آهک) حرارت داده می شود تا کربن دی اکسید به دست آید:

و از قسمت بالای برج، محلول غلیظی از سدیم کلرید و آمونیک وارد آن می شود. به محض این که در میان آن کربن دی اکسید بجوشد، سدیم بی کربنات تهنشین می شود:

سپس سدیم بی کربنات با حرارت دادن در شکل سدیم کربنات ظاهر می شود و آب و کربن دی اکسید سایر فراورده ها را تشکیل می دهند. ضمناً، آمونیاک از فراورده جانبی آمونیوم کلرید مجدداً تولید می شود و این زمانی رخ می دهد که در مجاورت آهک (کلسیم هیدروکسید) باقیمانده از واکنش تولید کربن دی کسید قرار گیرد.

به این دلیل که فرایند سولوای آمونیاک مصرف شده را باز می گرداند و تنها آب شور و آهک طی آن به مصرف می رسد و تنها فراورده ی اضافی آن کلسیم کلرید است، اساساً از نظر اقتصادی نسبت به فرایند لبلنک برتری دارد و به سرعت در تولیدات سدیم کربنات به عنوان روشی اصلی و کارامد مطرح شد. تا سال 1900، 90% سدیم کربنات تحت این فرایند تولید شد و آخرین پایگاه تولید سدیم کربنات که با استفاده از روش قبلی یعنی روش لبلنک فعالیت می کرد، در آغاز دهه ی 1920 بسته شد.

توسط شیمی دان چینی به نام Hou Debang در دهه ی 1930 معرفی شد. این فرایند در مراحل اولیه مشابه فرایند سولوای است. اما به جای واکنش دادن محلول باقیمانده با آهک، کربن دی اکسید و آمونیاک یک محلول تشکیل می دهند و سدیم کلرید هنگامی که دما به حد 40 درجه سانتیگراد رسید به محلول اضافه می شود. سپس محلول تا 10 درجه سانتیگراد سرد می شود. آمونیوم کلرید تهنشین شده و با فیلترگذاری جدا می شود. و در ادامه محلول مجدداً برای تولید سدیم بی کربنات به کار گرفته می شود. این روش مشکل تولید کلسیم کلرید را حل کرده و از محصول جانبی آمونیوم کلریدnh4cl) نیز جهت کود دهی استفاده می شود. این روش، روش روز تولید سدیم کربنات در صنایع کنونی جهان است.


برچسب‌ها: درمورد کربنات سدیم

تاريخ : یکشنبه بیست و ششم شهریور 1391 | 21:5 | نویسنده : علیرضا حسینی
بحث روز -كارخانه كربنات سديم كليد توسعه صنعت شيشه

صنعت شيشه در ايران داراي پتانسيل بالايي است و سيليس و ساير مواد اين صنعت در دل زمين و كوه ها در همه مناطق ايران به وفور يافت ميشود ولي  تنها كربنات سديم است كه به عنوان يك ماده شيميايي بايستي در يك فرايند پتروشيمي توليد گردد.ماده اوليه ان نمك و اهك است كه به مقدار فراوان در اكثر نقاط ايران است .قيمت يك كارخانه كربنات سديم تقريبا برابر با يك خط شيشه فلوت است و كمبود شديد ان در ايران احساس... 


برچسب‌ها: بحث روز, كارخانه كربنات سديم كليد توسعه صنعت شيشه

تاريخ : شنبه دوازدهم آذر 1390 | 10:43 | نویسنده : علیرضا حسینی
 

Soda ash dense

 

Item

Standard

Result

Sodium Carbonate(Na2CO3):

99. 2% MIN

99.3

Chlorides(NaCl):

0. 70% max

0.68

Iron(Fe):

0. 004%max

0.002

Insoluble Esubstance:

0. 04% max

0.03

Loss on Dry:

0. 8% max

0.42



ادامه مطلب
تاريخ : سه شنبه بیست و ششم مهر 1390 | 11:28 | نویسنده : علیرضا حسینی

طرح کربنات سدیم فیروزآباد فارس، بزرگترین طرح کربنات سدیم کشور است

طرح کربنات سدیم فیروزآباد استان فارس بزرگترین طرح کربنات سدیم کشور است که 30 درصد پیشرفت فیزیکی دارد.

این طرح با ظرفیت تولید 300 هزار تن کربنات سدیم در سال با سرمایه گذاری یک هزار و 347 میلیارد ریال (در حدود 135 میلیارد تومان) توسط بخش خصوصی در شهرستان فیروزآباد در حال ساخت است.

 

 هم اکنون مراحل آماده سازی سایت این طرح به پایان رسیده و مراحل ساخت وساز   نیز درحال انجام است، 

 

طرح کربنات سدیم فیروزآباد فارس یکی از طرح های بزرگ صنعتی درحال اجرا ی استان فارس است که در زمینی به  مساحت 280 هکتار (با احتساب احداث لاگون های پساب) در حال اجرا است. 

 

 در استان فارس نیز وجود ذخایر عظیم سنگ آهک ونمک (گنبدهای نمکی) به عنوان مواد اولیه مورد نیاز کربنات سدیم وهمچنین نزدیکی به بنادر جنوبی کشور شرایطی را به وجود آورده است که تمایل به سرمایه گذاری برای احداث وراه اندازی این واحد را افزایش داده است.

  آب مورد نیاز این طرح از طریق سد هایقر تامین می شود.

 

 با بهره برداری از این واحد که بزرگترین واحد تولید کربنات سدیم کشور است بیش از 50 درصد از نیاز کشور به این محصول تامین می شود.

 

 میزان تولید کربنات سدیم در کشور 506 هزار تن در سال می باشد این در حالی است که میزان مصرف این مواد 750 هزار تن در سال است.

 

 با راه اندازی این واحد در استان علاوه بر ایجاد اشتغال برای افراد محلی وبومی وتوسعه اقتصادی، بی نیازی کشور به واردات کربنات سدیم ( میزان واردات 200تا250 هزارتن ) و نیز قابلیت صادرات این محصول به بازارهای جهانی مرتفع می شود.

 


کربنات سدیم با نام تجاری soda ash از جمله مواد معدنی حد واسط می باشد که به دو شکل طبیعی ( در طبیعت) ومصنوعی ( در واحدهای صنعتی) تولید می شود وعمده مصرف این مواد به ویژه در صنایع شیشه و بلور، صنایع بهداشتی و شوینده، صنایع نساجی و دباغی، صنایع غذایی، صنایع کاغذ و صنایع شیمیایی می باشد.



تاريخ : سه شنبه ششم اردیبهشت 1390 | 23:55 | نویسنده : علیرضا حسینی


Solvay process


Solvay process Solvay process

An industrial process, also known as the ammonia-soda process, for the manufacture of sodium carbonate (see sodium). Sodium chloride (common salt), ammonia, carbon dioxide, and water react to give precipitated sodium bicarbonate, which on heating gives sodium carbonate and carbon dioxide for recycling. It was invented by the Belgian chemist Ernest Solvay (1838–1922) and patented by him 1861. By 1913 the process was producing a large part of the world's sodium carbonate.


The importance of sodium chloride

The Solvay process is the most widely used process for the manufacture of sodium carbonate. Because of its many uses, millions of tons of sodium carbonate are produced every year. It is in great demand by the glass industry, and it is important in the manufacture of textiles, soaps and detergents, numerous chemicals, paper, and iron and steel. It is also used as a water softener (household washing soda is a well-known form of sodium carbonate) and in the refining of petroleum.


Why the Solvay process?

Often there are many ways by which a particular chemical can be manufactured. Different raw materials and different reactions may be used to get the same end product. From the many available methods, the chemical industry chooses the most economical one. A good process uses the cheapest and most easily obtainable starting materials, which undergo a series of reactions. It may be that the by-products can be used again in the process or have value in other branches of the chemical industry. Methods which produce large quantities of useless by-products are rejected.

Sodium carbonate can be made in many ways but for reasons of economy most of it is now manufactured by the Solvay process. It has as its stating materials common salt (sodium chloride) and limestone (calcium carbonate), both of which are cheap and readily available. Ammonia is used in the process but it can be used over and over again so only a small quantity of it is needed to replenish that which is lost. The Solvay process consists of a continuous series of reactions from which the end product, sodium carbonate, results.


The chemistry of the Solvay process


تاريخ : چهارشنبه سوم فروردین 1390 | 20:45 | نویسنده : علیرضا حسینی

Solvay process

Sodium carbonate is generally prepared by a process called the ammonia – soda process or solvay process as described below:

 
Principle

When carbon dioxide gas is bubbled through a brine solution saturated with ammonia, it results in the formation of sodium hydrogen carbonate.

NH3 + H2O + CO2 → NH4HCO3

 NaCI + NH4HCO3 → NaHCO3 + NH4CI        

            

Sodium hydrogen carbonate so formed precipitates out because of the common ion effect caused due to the presence of excess of NaCl. The precipitated NaHCO3 is filtered off and then ignited to get Na2CO3.

2NaHCO3 → Na2CO3 + CO2 + H2O

       

 
Plant Process

The various parts for the manufacture of Na2CO3 by solvay process have been illustrated in figure below.

 1594_Plant Process.JPG

Alt text: Plant used for the manufacture of washing soda

 
(i)     Ammonia absorber

A 30% solution of brine is saturated with ammonia (from recovery tower) is introduced into absorber tower. Various impurities like calcium and magnesium salts present in the commercial NaCl precipitate out as corresponding insoluble carbonates. (which comes along with ammonia from the ammonia recovery plant)

2NH3 + H2O + CO2 → (NH4)2 CO3               

 CaCI2 + (NH4)2 CO3 → CaCO3 ↓ + 2NH4CI              

MgCI2 + (NH4)2 CO3 → MgCO3 ↓ + 2NH4CI               

The ammoniated brine is filtered to remove the precipitated calcium and magnesium carbonate.

 
(ii)    carbonation Tower

 It is high tower fitted with perforated plates. Ammoniated brine solution is made to trickle down from the top of the tower while CO2 gas from the lime kiln is admitted from the base of the tower. CO2 rises through the small perforations and its interaction with ammoniated brine results in the formation of insoluble sodium hydrogen carbonate.

NH3 + H2O + CO2 → NH4HCO3               

 NaCI + NH4HCO3 → NaHCO3 ↓ + NH4CI              

 
(iii) Filtration

The solution containing crystals of NaHCO3 is drawn off from the base of the carbonation tower and filtered to get NaHCO3.

 

(iv)   The NaHCO3 obtained from the above step is heated strongly in kiln to covert it into sodium carbonate (Na2CO3)

2NaHCO3 → Na2CO3 + CO2 + H2O               

The carbon dioxide produced here is sent to carbonation tower.

 
(v)    Ammonia recovery tower

The filtrate, after removal of NaHCO3 contains ammonium salts such as NH4HCO3 and NH4Cl.

The filtrate is mixed with Ca(OH)2 and is heated with steam in ammonia recovery tower.

NH4HCO3 → NH3 + H2O + CO2               

2NH4CI + Ca (OH)2 → 2NH3 + 2H2O + CaCI2              

The mixture of ammonia and CO2 gases is obtained which is used for saturation of brine while calcium chloride is obtained as a by – product.

 
(vi)   Lime kiln

Here limestone is heated at about 1300 K to obtained CO2 and calcium oxide

CaCO3 → CaO + CO2               

The CO2 gas goes to the carbonation tower while lime is slaked with water in tank known as slakes to form ca(OH)2.

The overall reaction taking place in solvay process is

2NaCI + CaCO3 → NaCO3 + CaCi2               

Flow sheet diagram of Solvay process

194_Lime kiln.JPG

Alt text: Solvay process to manufacture Sodium carbonate

 

Properties

(i) The aqueous solution absorbs CO2 yielding sparingly soluble sodium bicarbonate.

Na2CO3 + H2O + CO2 2NaHCO­3

(ii) It dissolves in acids with an effervescence of carbondioxide and is causticised by lime to give caustic soda.

Na2CO3 + 2HCl 2NaCl + H2O + CO2

Na2CO3 + Ca(OH)2 2NaOH + CaCO3

(iii)    Fusion with silica, sodium carbonate yields sodium silicate.

Na2CO3 + SiO2 Na2SiO3 + CO­2

(iv)   Hydrolysis – being a salt of a strong base (NaOH) and weak acid (H2CO3), when dissolved in water sodium carbonate. Undergoes hydrolysis to form an alkaline solution

Na2CO3 + 2H2O→ H2CO3 + 2NaOH

 
Uses

(i)     It is used for softening hard water.

(ii)    A mixture of sodium carbonate and potassium carbonate is used as fusion mixture.

(iii)    As an important laboratory reagent both in qualitative and quantitative analysis.

(iv)   It is used in paper, paints and textile industries.

(v)    It is used for washing purposes in laundry.

(vi)   It is used in the manufacture of glass, borax, soap and caustic soda.

 
Potassium carbonate (K2CO3)

It is also known as pearl ash. It is made by passing CO2 into a conc. solution of the chloride, containing hydrated mangesium carbonate in suspension at 20°C when an insoluble potassium hydrogen magnesium carbonate is precipitated.

2KCl + 3(MgCO3. 3H2O) + CO2 2(MgCO3. KHCO3×4H2O) + MgCl2

 

The precipitate is separated by filtration, and then decomposed either by heating with water under pressure at 140°C or by the action of magnesium oxide below 20°C. 

2(MgCO3. KHCO3. 4H2O) 2MgCO3 + K2CO­3 + 9H2O + CO2

2(MgCO3. KHCO3. 4H2O) + MgO 3(MgCO3. 3H2O) + K2CO3

 
Properties

(i)     It is white, deliquescent solid

(ii)    K2CO3 resembles Na2CO3 in properties, but is more alkaline and more soluble than Na2CO3.

 
Illustration:

Sodium carbonate, which is one of the most important products of the chemical industry, is prepared by the Solvay process based on the interaction of sodium chloride with ammonia and carbon dioxide. The reaction yields

        (A)    NH4HCO3                    (B)    NH4Cl

        (C)    NaHCO3                     (D)    (NH4)2CO3



تاريخ : جمعه بیست و ششم آذر 1389 | 20:39 | نویسنده : علیرضا حسینی


تصاوير زيباسازی ، كد موسيقی ، قالب وبلاگ ، خدمات وبلاگ نويسان ، تصاوير ياهو ، پيچك دات نت www.pichak.net

 



تاريخ : سه شنبه بیست و سوم آذر 1389 | 1:20 | نویسنده : علیرضا حسینی

The Ammonia Soda Process

The reactions involved in the ammonia soda process were discovered by H. G. Dyar and J. Hemming, about 1838, but owing to the mechanical difficulties, its practical success was not thoroughly established until 1873. In 1863, Ernest Solvay, a Belgian, constructed an apparatus which has led to an enormous development of the industry, by which one-half of the world's supply of soda is now made. Its advantages lie in the strength and purity of its products and the absence of troublesome by-products, such as "tank waste." But it does not yield chlorine nor hydrochloric acid, all the former going to waste as calcium chloride.
The ammonia soda process depends upon the fact that sodium bicarbonate is but slightly soluble in a cold ammoniacal solution of common salt. The technical success of the process depends chiefly on the proper regulation of the temperature during the precipitation, and on the capacity of the works to handle large quantities of gases and liquids. As far as possible, manual labor must be avoided, and the products moved and treated in solution or in suspension. The reactions are as follows: -

1) NaCl +NH3 +H20 +CO2= NH4Cl +NaHC03•
2) 2 NHlJl +Ca(OH)2 = CaC12+2 H20 +2 NH3'

The first equation is the chief one; the second represents the recovery of the ammonia, and is essential to the commercial success of the. process.
The salt is used as a very concentrated brine, which has been purified from iron, silica, magnesia, etc.; it is then saturated with ammonia gas, obtained from gas liquors, or by the recovery process according to equation (2). The carbon dioxide is obtained partly from lime kilns and partly from the calcination of the bicarbonate to form the normal carbonate. It must contain at least 10per cent of CO2, and is prepared in special forms of continuous limekilns. The lime resulting is used in the recovery of the ammonia (reaction 2), and for making caustic soda; the limekiln gases are cooled, and the sulphur dioxide removed, by washing in water before they pass into the carbonating towers. (See below.) The brine is contained in a tank, under the perforated bottom of which the ammonia gas is introduced, and rising through the liquor, is rapidly absorbed.
The heat evolved by the absorption is taken up by cold water circulating in coils. When saturated, the ammoniacal brine is pumped into a receiving and settling tank, from which it is delivered to the" carbonating tower" (Fig. 42).* This is from 50 to 65 feet high, built of cast-iron rings or segments (A, A), each about 3.5 feet high and 6 feet in diameter. At the bottom of each segment is a flat plate having a large hole in the centre. Above each plate is a dome-shaped diaphragm (D) perforated with a great number of small holes. In modern works a system of pipes passes through each segment, as shown at (B, B); in these, cold water is kept flowing, thus counteracting the heat generated by the chemical action. The ammoniacal brine is forced under pressure through the pipe (P), entering a little above the middle of the tower, which is nearly filled with brine. By this arrangement, any free ammonia in the brine, which would be swept away by the stream of gases passing up through the tower, is taken up by the carbon dioxide in the upper part of the tower. The carbon dioxide, having been previously well cooled, is forced through the pipe (C), entering under the lowest dome, and rising in small bubbles through the perforations in each dome, comes into intimate contact with the ammoniacal brine. The bicarbonate of sodium thus precipitated gradually works its way down through the tower. A thick, milley liquid, containing the bicarbonate in suspension, and ammonium chloride and comlllon salt in solution, is drawn off through (H) at the bottom.
After a tower has been in use for some days, the holes in the domes become clogged with a deposit of bicarbonate crystals, which prevent the free passage of the gases. Consequently, every ten days or two weeks the liquitl lllUSt be drawn out and the crystals dissolved by filling the towel' with hot water or steam. The tower must be cooled before starting the process anew. As a rule, several towers are employed, so that one may be cleaned and coolec1without interrupting the operation.
The gases escaping from the top of the tower, consisting principally of nitrogen, carbon dioxide, and some ammonia, are passed through scrubbers , one of which contains brine, which afterwards goes to the ammonia saturating tank; in the other is dilute sulphuric acid, to absorb the small amount of ammonia which would otherwise be lost. The carbon dioxide and nitrogen are allowed to escape. The towers are run with the view to the utilization of all the ammonia possible, even though there is considerable loss of salt and carbon dioxide; usually about one-fourth of the salt remains undecomposed.
It is now customary to place a smaller carbonating tower in connection with the large one; in the former the brine is first treated with carbon dioxide and the ammonia converted to neutral carbonate (NH4)2C03; then the brine is pumped into the large carbonating tower, where it meets more carbon dioxide, and the bicarbonate is formed, causing the precipitation of the sodium bicarbonate. 11ore heat is liberated in the formation of the neutral carbonate of ammonia than in its conversion to the bicarbonate, hence the temperature of the precipitation is more easily controlled when two towers are used, and less free ammonia escapes with the waste gases. A temperature of about 35° C. is most favorable to the formation of a granular or crystalline precipitate of bicarbonate, and also to the most complete utilization of the ammonia. At higher temperatures, too much bicarbonate remains dissolved in the liquor; at lower temperatures there is a tendency to the crystallization of ammonium acid carbonate and ammonium chloride, while the bicarbonate separates as a very fine precipitate, which is difficult to filter from the liquor.
The milky liquor from the bottom of the tower, containing the sodium bicarbonate in suspension, is filtered on sand filters connected with a vacuum pump; or better, it is run into centrifugal machines, which afford 1IIore rapid and complete separation of the mother-liquor. '£he bicarbonate is then washed with water, to remove as much of the sodium and ammonium chlorides as possible. The mother-liquors and wash waters go to the ammonia recovery process.
The sodium bicarbonate is then calcined in large covered cast-iron pans or ovens; this converts the acid salt into soda-ash, and drives out any ammonia or moisture still in the mass. The following is the reaction:-

2 N aHC03 = Nal~03 + CO~+ H~O.

The fumes are passed through coolers and scrubbers to remove ammonia; the concentrated carbon dioxide remaining is pumped into the carbonating towers. The ammonia liquors go to the ammonia stills.
A modification of the Thelen pan (Fig. 40) is sometimes used for this calcining. A gas-tight cover is placed over the pan, and the scrapers pass back and forth over the pan bottom, being moved by a connecting rod and crank. The gases and steam pass off through a pipe set in the cover. In practice, it has been found best to leave the mass in this pan only until all the ammonia and about 75 per cent of the carbon dioxide of the bicarbonate have been expelled; the calcination is completed in a reverberatory furnace.
The product of the calcination is called soda-ash; it is often very pure, containing only a trace of salt and a little bicarbonate, and is free from caustic soda, sulphide, and sulphate. But its density is only 0.8, while that of the Leblanc product is 1.2. This is disadvantageous, owing to the larger packages needed for a given weight and to the mechanical loss incurred in operations where the soda-ash is exposed to a strong draught of air. In order to increase the density, it is sometimes subjected to a second heating in a reverberatory (revolving) furnace.
The second reaction, on p. 8G, is that on which the recovery of the ammonia depends. The liquid in which the bicarbonate of soda was suspended contains undecomposed salt, ammonium chloride, and ammonium carbonate. It is passed through an ammonia still, usually a tall colu1lln or dephlegmator. Steam is admitted at the bottom of the apparatus, and bubbling up through the liquid, decomposes the ammonium carbonate into ammonia, carbon dioxide, part of the towel', or the still proper, where it is decomposed by "milk of lime." The ammonia set free is cooled and used to saturate the brine. The calcium chloride formed remains in solution, and together with the excess of salt, goes to waste. (For the various proposals to utilize the waste calcium chloride for the production of hydrochloric acid and chlorine) The damp bicarbonate is dried in an atmosphere of carbon dioxide, at a temperature of about 90° C.; this prevents decomposition of the sodium bicarbonate, while the ammonium bicarbonate is decomposed, the vapors passing to the scrubbers, where the ammonia is recovered. A considerable quantity of the bicarbonate of soda is sold directly to the manufacturers of ,baking powder and the poorer grades to the soda-water makers.
Caustic soda can be made stronger and purer from ammonia soda· ash than from Leblanc ash, and the process is not essentially different, except that no treatment to remove sulphur is necessary; but it cannot be made so cheaply as from the "red liquors" or the "tank liquors" of the Leblanc process. If pure lime is used for causticizing ammonia soda-ash, the product is better than in the case of the Leblanc ash, as it is free from sulphur, alumina, etc. Loewig's process (p. 81) appears especially suited for causticizing ammonia soda-ash, since it requires an ash free from silica. The Parnell and Simpson process * was expected to solve the problem of the Leblanc" alkali waste"; but while it is interesting, it has not justified the hopes of its promoters. It was proposed to combine to a considerable extent the two leading soda processes. The reactions involved are as follows: -

1) (NH4)2S+ CO2+ H20 = NH4HC03 + NH4HS.
2) NH4HS + CO2 + H~O=NH4HC03 + H2S.
3) NH4HC03 + NaCl =NaHC03 +NH4Cl.
4) CaS + 2 NH4Cl = (NH4)~S+ CaC12t

A solution containing a mixture of ammonium sulphide and salt is treated with carbon dioxide, as in the ammonia process. Sodium bicarbonate is precipitated and hydrogen sulphide set free; this is burned with air, and the sulphur dioxide sent to the lead chambers of the sulphuric acid process. Or the sulphur may also be recovered in a Claus kiln (p. 85). The ammonium sulphide is obtained by chloride liquors of the ammonia process, or those formed in this (Parnell-Simpson) process. Thus the ammonia is recovered and at the same time the troublesome Leblanc waste is disposed of. When the waste is boiled in the ammonium chloride solution, ammonia gas, together with vapors of ammonium sulphide, is liberated. These are led directly into the brine solution in the saturating tank. The ammoniacal brine is then pumped into the carbonating tower, which is very similar to that described earlier Here the first three reactions take place; * the hydrogen sulphide generated goes to the sulphur recovery, while the ammonium chloride solution, carrying the sodium bicarbonate in suspension, is drawn out and filtered.
The conversion of salt into sodium carbonate by any method involves an endothermic reaction in some part of the process. Thus energy must be expended, necessitating the use of fuel. In the ease of the Leblanc process, this expenditure of fuel is large, and is chiefly used in carrying out the reactions in the salt-cake and the black-ash furnaces. But much of the expended energy of this process reappears in the hydrochloric acid, the principal by-product. In the ammonia process the principal reactions are exothermic, but some fuel is consumed by the calcination of the precipitated bicarbonate and in the preparation of the quicklime used in the ammonia recovery and for generating carbon dioxide. Although less fuel is used than in the Leblanc process, the practical economy of the ammonia process is not so great as would at first appear; for all the chlorine is lost, together with a large part of the original salt used. As a method of producing soda-ash it is far superior to the Leblanc, but until a practical process for the cheap production of chlorine is discovered, the latter will continue to be an extensive industry.

http://www.lenntech.com/index.htm



تاريخ : چهارشنبه سوم آذر 1389 | 13:48 | نویسنده : علیرضا حسینی


تاريخ : سه شنبه بیست و ششم مرداد 1389 | 6:9 | نویسنده : علیرضا حسینی


تاريخ : سه شنبه بیست و ششم مرداد 1389 | 6:4 | نویسنده : علیرضا حسینی

Sodium Carbonate (Ammonia-Solvay Process)

Introduction
Sodium Carbonate is an important compound. It is manufactured by Ammonia-Solvay Process.


Raw Meterials


The raw materials for the manufacture of sodium carbonate are
1. Brine
2. Ammonia, which is made by Haber's Process
3. CO2, CaOH, which are obtained from limestone.


Ammonia-Solvay Process


The Ammonia-Solvay Process consist of the following steps.

Step I - Ammonation of Brine
In first step, ammonia gas is mixed with brine. This process is carried in Ammonation Tower. The ammonation tower consist of mushroom shaped buffels at short intervals. Brine is introduced from the top and ammonia is introduced from bottom. They both flow towards each other. Buffels control the flow of brine and ensure that they are mixed to the point of saturation with ammonia.

Step II - Carbonation of Ammonated Brine
In this step, ammonated brine is mixed with carbon dioxide brine is mixed with carbon dioxide in a tower called carbonating tower or Sonvai tower. Ammonated Brine is fed from the top where as carbon dioxide ascends from the bottom. When these two substances meet, the following chemical reactions takes place.
2NH3 + CO2 + H2O ----> (NH4)2CO3
(NH4)2CO3 + CO2 + H2O ----> 2NH4HCO3
2NH4HCO3 + NaCl ----> NaHCO3 + NH4Cl
Sodium bicarbonate is relatively insoluble, which is precipitated out from the solution by cooling the lower part of the tower. Sodium bicarbonate is separated from soluble ammonium chloride by vacuum filteration.

Step III - Production of Soda Ash
Sodium bicarbonate is heated in a long iron tube to obtain anhydrous sodium carbonate or Soda Ash.
This carbon dioxide is recycled to the solvay tower. This hydrated sodium carbonate is also called washing soda.


Recovery of Ammonia


Ammonia gas is recovered from the remaining solution by treating it with Calsium Hydroxide.
2NH4Cl + Ca(OH)2 ----> CaCl2 + 2H2O + NH3


http://www.friendsmania.net/forum/2nd-year-chemistry-notes/25795.htm



تاريخ : سه شنبه بیست و ششم مرداد 1389 | 6:2 | نویسنده : علیرضا حسینی
  • Sodium carbonate, Na2CO3, has a number of uses but its most common use is in the production of glass.

  • Since the 1860's, sodium carbonate has been produced using the Solvay Process.

  • The Solvay Process is a continuous process using limestone (CaCO3) to produce carbon dioxide (CO2) which reacts with ammonia (NH3) dissolved in brine (concentrated NaCl(aq)) to produce sodium carbonate.

  • The steps in the Solvay Process are:

  1. Brine Purification

  2. Sodium Hydrogen Carbonate Formation

  3. Sodium Carbonate Formation

  4. Ammonia Recovery

     

Properties and Uses of Sodium Carbonate

Sodium carbonate, Na2CO3, dissolves in water to form an alkaline solution.

Used as a base, sodium carbonate is cheaper and safer than sodium hydroxide.

Uses of Sodium Carbonate
Use Process Notes
Glass Making A mixture of Na2CO3, CaCO3 and SiO2 (silicon dioxide sand) is used for window or bottle glass.

Water Softening Agent CO32- from dissolved Na2CO3 can precipitate Mg2+ and Ca2+ ions from hard water as the insoluble carbonates, preventing them from forming a precipitate with soap resulting in scum.
For this reason, sodium carbonate is also known as washing soda.

Paper Making Na2CO3 is used to produce the NaHSO3 necessary for the sulfite method of separating lignin from cellulose.

Baking Soda Production Baking soda (or sodium hydrogen carbonate or sodium bicarbonate), NaHCO3, is used in food preparation and in fire extinguishers.

Sodium Hydroxide Production for Soaps and Detergents Na2CO3 is reacted with a Ca(OH)2, slaked lime, suspension.

Wool Processing Na2CO3 removes grease from wool and neutralises acidic solutions.

Power Generation Na2CO3 is used to remove SO2(g) from flue gases in power stations.

Solvay Process

The Solvay Process for the production of sodium carbonate is summarised in the flowchart below:

brine
NaCl(aq)
-----> ammoniated brine <----- ammonia
NH3
      |
|
    /\
|
 
limestone
CaCO3
    |
|
|
|
NaCl
H2O
NH3
  |
|
|
|
NH3
|
|
\/
    |
|
|
\/
    |
|
|
|
 
lime kiln CO2
----->
carbonating tower   |
|
|
 
 
H2O
|
CaO
    |
\/
    |
|
 
|
\/
|
\/
    filter
|
NH4Cl
--------->
ammonia recovery
lime slaker Ca(OH)2
------------|--------------->
  |
|
\/
  |
\/
  product
NaHCO3
  by-product
CaCl2
  |
300oC
|
\/
   
  product
Na2CO3
   

  1. Brine Purification


    Brine is concentrated by evaporation to atleast 30%
    Impurities such as calcium, magnesium and iron are removed by precipitation, eg,
    Ca2+(aq) + CO32-(aq) -----> CaCO3(s)
    Mg2+(aq) + 2OH-(aq) -----> Mg(OH)2(s)
    Fe3+(aq) + 3OH-(aq) -----> Fe(OH)3(s)

    Brine solution is then filtered and passed through an ammonia tower to dissolve ammonia.
    This process is exothermic, releases energy, so the ammonia tower is cooled.

  2. Sodium Hydrogen Carbonate Formation


    Carbon dioixide is produced by the thermal decomposition of limestone, CaCO3(s), in the lime kiln:
    CaCO3(s) -----> CO2(g) + CaO(s)

    Carbon dioxide is bubbled through the ammoniated brine solution in the carbonating tower.
    The carbon dioxide dissolves to form a weak acid:
    CO2(g) + H2O(l) HCO3-(aq) + H+(aq)

    The ammonia in the brine reacts with H+ to form ammonium ions:
    NH3(aq) + H+(aq) NH4+(aq)

    The HCO3- then reacts with the Na+ to form a suspension of sodium hydrogen carbonate:
    HCO3-(aq) + Na+(aq) NaHCO3(s)

    NaHCO3 precipitates because of the large excess of Na+ present in the brine which forces the equilibrium position to shift to the right by Le Chatelier's Principle (NaHCO3 is quite soluble in water).
    The overall molecular equation for the formation of sodium hydrogen carbonate in the carbonating tower is:
    NH3(aq) + CO2(g) + NaCl(aq) + H2O(l) -----> NaHCO3(s) + NH4Cl(aq)

    The net ionic equation for the formation of sodium hydrogen carbonate in the carbonating tower is:
    NH3(aq) + CO2(g) + Na+(aq) + H2O(l) -----> NaHCO3(s) + NH4+(aq)
    where Cl- is a spectator ion

  3. Sodium Carbonate Formation


    Suspended sodium hydrogen carbonate is removed from the carbonating tower and heated at 300oC to produce sodium carbonate:
    2NaHCO3(s) -----> Na2CO3(s) + CO2(g) + H2O(g)

    The carbon dioxide produced is recycled back into the carbonating tower.

  4. Ammonia Recovery


    CaO is formed as a by-product of the thermal decomposition of limestone in the lime kiln.
    This CaO enters a lime slaker to react with water to form calcium hydroxide:
    CaO(s) + H2O(l) -----> Ca(OH)2(aq)

    The calcium hydroxide produced here is reacted with the ammonium chloride separated out of the carbonating tower by filtration:
    Ca(OH)2(aq) + 2NH4Cl(aq) -----> CaCl2(aq) + 2H2O(l) + 2NH3(g)

    The ammonia is recycled back into the process to form ammoniated brine.
    Calcium chloride is formed as a by-product of the Solvay Process.

Environmental Issues

  1. Solid Wastes

    Calcium chloride, CaCl2, is a by-product of the Solvay Process.
    There are a limited number of uses for CaCl2:
        - drying agent in industry
        - de-icing roads
        - an additive in soil treatment
        - an additive in concrete
    The rest must be disposed of either by pumping out to sea, or by evaporating to dryness and disposing of the solid.
    CaCl2 can not be pumped into rivers or lakes because it will raise the concentration of chloride ion to unacceptable levels.

    Other solid wastes include unburnt calcium carbonate, sand and clay from the kiln. It is possible that these could be used to make bricks, landfill or road base.

  2. Air Pollution

    Some ammonia is lost to the atmosphere during the Solvay Process. Ammonia is a toxic atmospheric pollutant.
    Ammonia losses are minimised to reduce plant operation costs.

  3. Thermal Pollution

    Some of the processes involved in the Solvay Process are exothermic, they release heat.
    Near the ocean, water used during the cooling processes can be released into the sea without causing disruption to aquatic organisms.
    Inland plants need to either release heated water slowly into rivers or lakes or cool the water first before releasing in order to prevent disruption to aquatic organisms



تاريخ : یکشنبه شانزدهم خرداد 1389 | 12:5 | نویسنده : علیرضا حسینی

The Solvay process produces sodium carbonate from salt (sodium chloride) and limestone (calcium carbonate).

In neutral or basic solutions, sodium bicarbonate is less water-soluble than sodium chloride. When carbon dioxide passes through a concentrated solution of sodium chloride and ammonia, sodium bicarbonate precipitates according to the following chemical reaction:

NaCl + CO2 + NH3 + H2ONaHCO3 + NH4Cl

The ammonia is necessary to buffer the solution at basic pH. Without it, a hydrochloric acid byproduct would render the solution acidic, and in acidic solutions, the reaction cannot proceed. In industrial practice, the reaction is carried out by passing concentrated brine through two towers. In the first, ammonia bubbles up through the brine and is absorbed by it. It the second, carbon dioxide bubbles up through the brine and precipitates sodium bicarbonate. Carbon dioxide for this step is produced by heating calcium carbonate:

CaCO3CO2 + CaO

The solid sodium bicarbonate is then filtered out and converted to sodium carbonate by heating it, recovering some carbon dioxide in the process:

2 NaHCO3Na2CO3 + H2O + CO2

Meanwhile, ammonia is recovered from the ammonium chloride byproduct by treating the ammonium chloride solution with the calcium oxide (a strong base) left over from carbon dioxide generation:

2 NH4Cl + CaO → 2 NH3 + CaCl2 + H2O

The recovered carbon dioxide and ammonia are recycled back to the initial brine solution. When properly designed and operated, a Solvay plant can reclaim almost all its ammonia, and consumes only small amounts of additional ammonia to make up for losses. The only major inputs to the Solvay process are salt and limestone, and its only major byproduct is calcium chloride.

History

Soda ash is important to the glass, soap, paper, and textile industries. Historically, it was extracted from the ashes of marine plants such as barilla or kelp or mined from dry lakebeds in Egypt. By the late 1700's however, these sources were insufficient to meet Europe's demand for the chemical, particuarly in Great Britain. In 1791, the French physician Nicolas Leblanc developed a method to manufacture soda ash using salt, limestone, sulfuric acid, and coal. Although the Leblanc process achieved widespread industrial use, the expense of its inputs and its polluting byproducts (including hydrochloric acid gas) made it apparent that it was far from an ideal solution.

In 1811, the French physicist Augustin Jean Fresnel discovered that sodium bicarbonate precipitates when carbon dioxide is bubbled through ammonia-containing brine—the chemical reaction central to the Solvay process. Over the next fifty years, several groups attempted to reduce this reaction to industrial practice, but none succeeded.

In 1861, the Belgian industrial chemist Ernest Solvay turned his attention to the problem. His solution, an 80-foot-tall gas absorption tower in which carbon dioxide bubbled up through a descending flow of brine, together with efficient recovery and recycling of the ammonia, proved effective, and by 1864, Solvay and his brother Alfred had acquired financial backing and constructed a plant in the Belgian town of Charleroi. The new process proved more economical and less polluting than the Leblanc method, and its use spread. In 1874, the Solvays expanded their facilites with a new, larger plant at Nancy. The same year, the British firm Brunner Mond began operation of the first Solvay-based plant in Great Britain, and in 1884, the Solvays opened a joint venture with the American engineer William Cogswell to produce soda ash in the United States. Ludwig Mond of Brunner Mond was instrumental in making the Solvay process a commercial success through several refinements between 1873 and 1880 that removed byproducts that could slow or halt the mass production of sodium carbonate through use of the process. By the 1890s, Solvay process plants produced the majority of the world's soda ash.

In 1938, large natural deposits of the mineral trona were discovered near the Green River in Wyoming. Sodium carbonate can be mined from this source less expensively than it can be produced by the Solvay process, and since 1986, there have been no Solvay-based plants operating in North America. Throughout the rest of the world, however, the Solvay process remains the major source of soda ash.



تاريخ : شنبه یکم خرداد 1389 | 14:16 | نویسنده : علیرضا حسینی

كربنات سديم ، سودااش                                        Na2Co3

انگليسي(Soda  Ash)  Sodium  Carbonate                              :

فرانسوي: Carbonate  de  Sodium (Soude)  " Soude"                

آلماني:Natriumkarbonat ,  Wasserfrei,  Kalzinierte  Soda     

پودر يا دانه هاي گرانولي سفيد.

رطوبت پذير. مقدار آب بايد بطور پيوسته چك گردد( در oc  250 خشك مي گردد.)

 

الزامات كيفي:

     عموما" بصورت، سودااش گرانولي  متراكم استفاده مي شود كه بايد شامل حداقل            Na2Co3 99 %  (حداقل Na2O 58%) باشد. دانسيته حجمي تقريبا" 1 مي باشد. اين كيفيت نسبت به كيفيتهاي ديگر نبايد گرد و غباري داشته باشد. " سودا اش سبك " گاه گاهي مورد استفاده قرار مي گيرد. بطور معمول اين ماده ارزان تر است ولي يك سري مشكلات   گرد و غباري هنگام حمل و نقل و ذوب  بوجود مي آورد. (سوزش بيني، خوردگي سوپر استراكچر و غيره).

 

پيشنهادات كيفي: اندازه دانه

1.5mm >         حداكثر 1%   

1.0mm      >    حداكثر  10%

0.2-0.6 mm >   حداقل 50%

0.1mm >          حداكثر   5%

 

تركيب:

مجموع مقدار Na2O < 58% Na2O(99% ‌Na2Co3)

كلريد سديم حداكثر 0.5%

سولفات سديم حداكثر 0.1%

آهن بصورت Fe2O3 حداكثر 0.005%

 غير محلول در آب حداكثر 0.1%

 آب حداكثر 1%

اين ماده نبايد شامل تركيبات فلزي رنگي باشد.

 

كاربرد:

 ماده اوليه مهم براي ايجاد Na2O در شيشه.

 

ملاحظه:

  كربنات سديم بلوري شده Na2Co3.10H2O در ساخت شيشه نبايد استفاده شود.

 

فاكتورهاي تبديل:

             1 Na2Co3    --------      0.585 Na2O

(پرت ذوب ) 0.415 H2O

            1 Na2O     -------        1.71 Na2Co3



تاريخ : شنبه یکم خرداد 1389 | 12:52 | نویسنده : علیرضا حسینی

 

 



تاريخ : شنبه یکم خرداد 1389 | 12:47 | نویسنده : علیرضا حسینی

 



تاريخ : شنبه یکم خرداد 1389 | 12:42 | نویسنده : علیرضا حسینی

شرکت کربنات سدیم



تاريخ : سه شنبه بیستم بهمن 1388 | 20:44 | نویسنده : علیرضا حسینی

 designed adopting the Solvoy Process. It is composed of seven main sections and threeauxiliary units. Main process sections such as brine section, lime section, distillation & absorption section, carbonation section, calcination section, dense ash section and compression section.  

Main duty of brine section is supply with purified brine for next process section. That is Raw salt is dissolved into saturated crude brine and then through lime & soda ash method get purified brine.

Main duty of lime section is supply with kiln gas for carbonation section and lime milk for distillation section and brine section. In this section, limestone is decomposed by heating into kiln gas and lime, and the lime is slaked into lime milk.

Distillation & absorption includes two systems: ammonia distillation and ammonia absorption. Main duty of Distillation is distilling off Ammonia of mother liquor from carbonation section for recycling utilization in the Ammonia absorption. Main duty of absorption is absorbing distilled ammonia from Distillation to prepare qualified ammoniated brine for carbonation section.

For carbonation system, its main duty is that ammoniated brine from absorption is carbonated by CO2 from calciner gas of calcination section and kiln gas of lime section into magma with sodium bicarbonate crystal. Magma is filtrated off the sodium bicarbonate cake and cold mother liquid by vacuum drum filter. The sodium bicarbonate cake is sent to calcination section for obtaining soda and cold mother liquid is sent to distillation section for ammonia recovery. 

Duty of calcination section is that bicarbonate is decomposed by heating into light soda ash; then light soda ash is sent to dense soda ash section.

In dense ash section, the light soda ash is hydrated by water into monohydrate sodium carbonate. The dense soda ash production is produced after passing through fluidized-bed dryer/cooler/classifier and screen, and then conveyed to product package section.

In compression section, calciner gas coming from calcination section and kiln gas coming from lime section, are compressed to proper pressure, cooled by calciner gas cooler and kiln gas cooler, and delivered to carbonation section respectively.


2           Feed characteristics

2.1         Raw Salt.

Composition              Content (wt.%)

NaCl                        ³95

Ca2+                        £0.8

Mg2+                        £0.5

SO42-                        £1.7

Insoluble                     £1

Water                                                    £5.0

Grain size                    £5mm

2.2         Lime Stone.

Composition              Content (wt.%)

CaCO3                                                  ³93

MgCO3                                                  £3.5

SiO2                                                      £3

Al2O3+Fe2O3                                        £1.5

Grain size                    50~120mm  

2.3         Liquid Ammonia.

Composition              Content (wt.%)

NH3                                                      >99.0

Oil                                                         <5ppm

Color                    Colorless liquid

2.4         Na2S

Composition              Content (wt.%)

Na2S                        ³60.0

Nature                       Solid

2.5         Coke

Composition              Content (wt.%)

Fixed Carbon                > 80

Volatile                     <8

Granularity                  30~50 mm

2.6         BaCl2

Composition              Content (wt.%)

BaCl2                       ³98.5

Nature                      Solid

2.7         Fresh water

Items

Specification

Water temperature at the time of testing

15 ~ 25ºC

Color

----

Taste and odor

----

Electrical conductivity

4697.5 umhos/cm

PH

7.01

Turbidity                  

0.5 NTU

Suspended solid

----

Total dissolved solid at 180 ºC

3917 mg/L

Alkalinity to phenolphthalein

0.0 mg/L CaCO3

Total Alkalinity

114 mg/L CaCO3

Total hardness

2125 mg/L CaCO3

Calcium                 

635.5 mg/L Ca

Magnesium                

133.15 mg/L Mg

Sodium                   

499 mg/L Na

Potassium                

10.5 mg/L K

Chloride                 

705.5 mg/L Cl

Sulphate                   

1857.75 mg/L SO4

Silica                    

16.5 mg/L SiO2

Ammonia                  

0.29 mg/L NH3

Nitrate                   

9.2 mg/L NO3

Nitrite                    

0.068 mg/L NO2

 

3           Products Specification

Composition                Content (wt.%)

Total alkali (as Na2CO3)          ³99.2

Chloride (as NaCl)                    £0.6~0.7

Iron (as Fe)                 £0.004

Water insoluble                          £0.04

Loss on ignition                         £0.8

Sulfate (SO42-)                            £0.03

Density of Light Ash           ~0.5 kg/dm3

Density of Dense Ash          ~1.0 kg/dm3

Grain Size                   Max. 2 % larger than 1180 µm

Max. 8 % smaller than 180 µm

4           Material balance

Refers to process flow diagram.

5           Battery limits condition

5.1         Fresh water

Pressure                           0.55MPa (G)  

Temperature                       15~25°C

Flow rate (Nor.~Max.)              289.7 ~334.5 m3/h

5.2         De-mineralized water

Electrical Conductivity

<= 20µs/cm

SiO2                    

<= 100 µg/l

Na+

<= 5ppm

CL-

<= 8ppm

Pressure                   

≥0.5MPa (G)

Temperature                

Up to 25°C

Flow rate (Nor.~Max.)              

40.3 ~44.3m3/h

5.3         Cooling water supply

Pressure

0.45   0.45MPa (G)

Temperature           

27    27 °C

Flow rate (Nor.~Max.)

5178  4671~4990 m3/h

5.4         Cooling water return

Pressure

0.15 MPa (G)

 

Temperature

~37°C

 

Flow rate (Nor.~Max.)

 4671~4990 m3/h

 

5.5         Steam

a)         Medium pressure steam

Pressure                                                           2.8MPa (A)

Temperature                                                  270~285 °C 

Flow rate (Nor.~Max.)                                  55.45 ~59.73t/h

b)         Low pressure steam

Pressure                                                           0.4MPa (A)

Temperature                                                  143±5°C 

Flow rate (Nor.~Max.)                            52.52 ~59.19t/h

5.6         Instrument Air

Pressure                                                           0.7 ~0.8MPa (G)

Temperature                                                  Ambient

Dew Point (at 0.6 MPa)                               -20°C  

Flow rate (Nor.~Max.)              700~770Nm3/h

5.7         Condensate

Pressure                                                           0.4MPa (A)

Temperature                                                  Saturated

Flow rate (Nor.~Max.)                            44.01 ~47.4t/h

5.8         Electricity (estimated)

6.0kVInstallation Power              6800 kW

0.38/0.22 kV Installation Power        4944 kW

5.9         Emergency power

The buyer shall design emergency power supply, and connect the incoming line to the emergency incoming switchboard in 0.4kV L.V. distribution switchboard.

The emergency power shall be considered in following fields:

Process equipment such as: Brine clarifier, Steam calciner, and Lime milk tank, Prelimer.

The total emergency power of above equipment is about 265kw, the voltage is 380v.

6           Design features

Brine section used lime & soda ash method for purification of crude brine. This method simplifies the process, lessens the equipment, makes Ca2+ and Mg2+ precipitated simultaneously and clarified in one time, hence it realizes simple operation, less investment and high efficiencies of removal of Ca2+ and Mg2+ 98% to 99 % and 99% to 99.6 % respectively. Lime & soda ash method is applied to purify brine at the Contract Plant.

In the lime section, lime is slaked with returning fresh water coming from distillation section into lime milk in lime slaker, which can make use of the heat of returning fresh water.

For the distillation & absorption, according to design condition of this project, we selected corrugated pipe heat exchanger as Ammonia Condensate Cooler. Corrugated pipe heat exchanger has furring-resistant automatically and capacity of cleaning.  It has smaller pressure drop than plate heat exchanger. It is easy to adjust, easy to operation and easy to maintain it has longer operation period than plate heat exchanger.  So we select three sets of horizontal corrugated pipe heat exchanger and three sets of vertical corrugated pipe heat exchanger Pipe material: Titanium.

In the carbonation section, based on operation experience, carbonating tower adopted bubble tower, it has advantage of high percent conversion, each carbonating tower requires cleaning after 60~80 hours making. Thus, a group of 4 carbonators is the optimum choice. Each carbonating tower is cleaned once per 24 hours. For the filtration of bicarbonate, Vacuum drum filter contains stainless steel is used, which is advantage to guarantee the product quality.

In calcination section, Crude bicarbonate enters into calciner equipped with finned heating tubes inside. Crude bicarbonate is decomposed into light soda ash by means of indirect heating with superheated steam.

In dense ash section, the light soda ash is hydrated by water into monohydrate sodium carbonate. The dense soda ash production is produced after passing through fluidized-bed dryer/cooler/classifier and screen; that equipment selected VA TECH, good in quality and high in efficiency.

For the compression, it is adopted the screw type compressor, it has the advantages of centrifugal type compressor. Additionally, it also has the following advantages:

a)        Lower requirements to the quality of kiln gas

b)        Less maintenance

c)        One-stage compressing, simplified process, lessen auxiliary facilities

d)       Stable running, less failure, long period of successive operation. Therefore, the screw type compressor is suitable for the production of soda ash plant.