Manufacture Of Urea A REPORT SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIRMENT FOR THE DEGREE OF BACHLOR IN CHEMICAL ENGINEERING By 1.Heba Ramadan Mohammed2. Haneen Mohammed Mahdi 3. Safa Ramadan Mohammed 4. SarahDeia'a Khaleel5. Mowafq KhalafSuliman Supervisor Asst.Prof.Dr.Duraid F.A University Of Tikrit Department Of Chemical Engineering 2015 CONTENTS Abstract CHAPTER 1: Introduction PAGE NO. 1.1Introduction1 1.2 Physical Properties2 1.3Chemical Properties 3 1.4Uses of Urea 4 1.5Environmental Effects 5 1.5.1 Elimination Method5 1.6Urea Production Methods 7 1.6.1Once- Through Urea Process 7 1.6.2Partial recycle process8 1.6.3Stripping process based plants9 1.7Selection of the Process13 1.8Process Description14 Chapter 2: Material Balance19 2.1Around Reactor21 2.2 Around Stripper23 2.3 Around Medium Pressure Decomposer 24 2.4 Around Low Pressure Decomposer 25 2.5Around Vacuum Evaporator27 2.6Around Prilling Tower 28 Chapter 3: Energy Balance32 3.1 Around Reactor 33 3.2 Around Stripper 35 3.3 Around Carbamate Condenser 37 3.4 Around Medium Pressure Decomposer40 3.5Around Low Pressure decomposer 42 3.6 Around Vacuum Evaporator42 3.7Around Prilling Tower43 Chapter 4: Equipment Design46 4.1 Reactor Design 48 4.1.1 Introduction48 4.1.2 Thickness of Shell Design49 4.1.3Head Design50 4.1.4 Piping Design 53 4.1.5 Sieve Plate Design55 4.2 Carbamate Condenser Design 55 4.2.1 Introduction55 4.2.2 DesignProcedure 56 4.3 Low Pressure Decomposer Design60 4.3.1Introduction60 4.3.2 Design Calculation60 4.4Vacuum Evaporator Design 62 4.4.1 Evaporation And Its Mechanism 62 4.4.2 Evaporator Types 63 4.4.3 Evaporator Selection 64 4.4.4 Design Calculation64 4.5 Prilling Tower Design 71 4.5.1 Introduction71 4.5.2 Material Of Construction72 4.5.3 Design Calculation72 Chapter 5:Process Control76 5.1 Introduction 77 5.2 Control Objectives77 5.3 Types Of Control System 78 5.4 Equipment Control79 5.4.1Around Reactor79 5.4.2Around Carbamate Condenser81 5.4.3Around Low Pressure Decomposer 82 5.4.4 Around Vacuum Evaporator84 5.4.5 Around Prilling Tower 87 Chapter 6: Economy Cost 89 6.1 Introduction90 6.2 Types Of Cost Involves In Manufacturing90 6.3 Cost Calculation 90 Chapter 7:Safety Aspect94 7.1 Introduction 95 7.2Principle Of Protection And Prevention96 7.3 Safety Precaution96 7.4 List Of Safety equipment 97 7.5 Fire Hazards 98 Reference 99 Abstract Urea in many ways the most convenient form of fixed nitrogen. It has The highest nitrogen available in a solid fertilizer(46%). It is easy to produce as prills or granules and easily transported in bulk or bags with no explosive hazard. It leaves no salt residue after use in crops. Its specific gravity 1.335, decomposeson boiling and it is fairly soluble in water. The principle raw materials required for this purpose are NH3 andCO2. Two reactions are involved in the manufacture of urea ,first , ammonium carbamateis formed under pressure by reaction between CO2 and NH3. CO2+NH3 NH2COONH4 H= -37.4 kcal The highly endothermic reaction is followed by an endothermicDecomposition of ammonium carbamate. NH2COONH4NH2CONH2+H2O H=+6.3 kcal We selected snamprogetti ammonia stripping process for theManufacture of urea. The selected capacity of the plant 500,000 ton/year Of urea producing 68055.56 kg/hr of( 98%) purity. Urea material andEnergy balance of the plant is done. Urea reactor, vacuum evaporator, Carbamate condenser, low pressure decomposer and prilling tower areDesigned. The volume of reactor is calculated and found to be 119.97 m3 The length and diameter of the reactor are 17.65 m and 2.94 mRespectively. The evaporator used is of climbing-film long-tube type.

Chapter 1 Introduction 1 1.1 Introduction Urea is an organic compound with the chemical formula (CO(NH2)2 , the molecule has two functional group joined by a carbonyl (C=O) functional group. Urea scientific name (Carbonyl di amide); it is composed of 45% (N2), 20% ( C ) 26% (O2) and 9% (H2)it has the highest nitrogenous fertilizer in common use Therefore it being the preferrednitrogen fertilizer worldwide. It is used in solid Fertilizer, liquid fertilizer, formaldehyde resins and adhesives. Roulle first Discovered urea in urine in 1773. His discovery followed by the synthesis of urea from ammonia and cyanic acid by Whler in 1828. This is considered to be the first synthesis of an organic compound from inorganic compound. In 1870 Bassarow produced urea by heating ammonium carbamate in a sealed tube in What was the first synthesis of urea by dehydration. Urea is produced worldwide On a large scale and its production volume exceeds 150*106 ton/year in 2010. At the present urea is produced on an industrial scale exclusively by reactions

based on NH3 and CO2 as the raw material.

2 1.2 Physical Properties Urea is a white odorless solid. Due to extensive hydrogen bonding with water ( up to Six hydrogen bonds may form two from the oxygen atom and one from each hydrogen) Urea is very soluble. Molecular weight60.07Melting point (C)132.7Boiling point(C) 135Density(gm/cm3),solid 1.335Bulk density( gm/cm3)0.74Viscosity ,v20(mpa. Sec)1.9Heat of fusion(J/gm)251Heat of solutioninwater(J/gm)243Specific heat ,S0(KJ/kg. Co) 1.439Specific gravity1.335Vapor pressure(pa)