Urea

(NH₂)₂CO · 60.06 g/mol

(NH₂)₂CO

Largest-volume nitrogen fertilizer and resin precursor

Molecular Weight

60.06 g/mol

State

Solid

Catalyst

None

Reactor

High pressure stripper r

Olefinverbund Integration

Inputs

Ammonia, **Carbon Dioxide** (Feedstock)

→

Product

Urea

→

Outputs

Melamine, Fertilizers, Resins

Chemistry & Engineering

Reaction	`2NH₃ + CO₂ ⇌ NH₄CO₂NH₂ ⇌ (NH₂)₂CO + H₂O`
Thermodynamics	First step exothermic, second step endothermic
Catalyst	None
Reactor class	High pressure stripper reactor (150 bar, 180°C)
Note	Corrosion is severe (ammonium carbamate). Biuret formation must be minimized.

Applications

Nitrogen fertilizer (46% N)
Urea-formaldehyde resins
AdBlue/DEF for diesel emissions
Melamine production

Extraterrestrial Production Pattern

NH₃ + CO₂ → ammonium carbamate (fast reaction)
Ammonium carbamate → urea + H₂O (slower, equilibrium limited)
Operating at 140-210°C and 140-250 bar
Stripping and recycling of unreacted materials

Reaction Diagram

2NH3 + CO2 -> (NH2)2CO + H2O

Unit Operations

Process steps following chemical engineering unit operation principles

#	Operation	Description
1	Ammonia/CO₂ Mixing	Mix NH₃ and CO₂ at high pressure (140-250 bar)
2	Carbamate Formation	Exothermic reaction to ammonium carbamate
3	Urea Synthesis	Dehydration to urea at 180-210°C
4	Stripping	Steam strip unconverted carbamate
5	Concentration	Evaporate to 99.7% urea solution
6	Prilling/Granulation	Form solid urea prills or granules

S88 Batch Control Model

ISA-88 BatchML schema — simplified for educational purposes

<?xml version="1.0" encoding="UTF-8"?>
<!-- ISA-88 Batch Control Model for Urea -->
<!-- Educational schema - simplified for demonstration -->
<BatchML xmlns="http://www.wbf.org/xml/B2MML-V0600">
  
  <ProcessCell ID="UREA_SYNTHESIS_CELL">
    <Description>Process cell for Urea production</Description>
    
    <Unit ID="UREA_SYNTHESIS">
      <Description>Main synthesis unit</Description>
      
      <!-- Equipment Modules -->
      <EquipmentModule ID="MIXER">
        <Description>Mixer</Description>
      </EquipmentModule>
      <EquipmentModule ID="CARBAMATE_REACTOR">
        <Description>Carbamate Reactor</Description>
      </EquipmentModule>
      <EquipmentModule ID="UREA_REACTOR">
        <Description>Urea Reactor</Description>
      </EquipmentModule>
      <EquipmentModule ID="STRIPPER">
        <Description>Stripper</Description>
      </EquipmentModule>
      <EquipmentModule ID="EVAPORATOR">
        <Description>Evaporator</Description>
      </EquipmentModule>
      <EquipmentModule ID="PRILLING_TOWER">
        <Description>Prilling Tower</Description>
      </EquipmentModule>
    </Unit>
  </ProcessCell>
  
  <MasterRecipe ID="UREA_SYNTHESIS_RECIPE">
    <Description>Master recipe for Urea</Description>
    <ProductID>UREA</ProductID>
    
    <UnitProcedure ID="UREA_SYNTHESIS_UP">
      <Description>Unit procedure for synthesis</Description>
      
      <Operation ID="OP_01">
        <Description>Operation 1</Description>
        <Phase ID="MIX">
          <Description>Mix phase</Description>
          <PhaseLogic>
            <Step ID="STEP_1"><Action>Initialize</Action></Step>
            <Step ID="STEP_2"><Action>Execute</Action></Step>
            <Step ID="STEP_3"><Action>Complete</Action></Step>
          </PhaseLogic>
        </Phase>
      </Operation>
      
      <Operation ID="OP_02">
        <Description>Operation 2</Description>
        <Phase ID="FORM_CARBAMATE">
          <Description>Form Carbamate phase</Description>
          <PhaseLogic>
            <Step ID="STEP_1"><Action>Initialize</Action></Step>
            <Step ID="STEP_2"><Action>Execute</Action></Step>
            <Step ID="STEP_3"><Action>Complete</Action></Step>
          </PhaseLogic>
        </Phase>
      </Operation>
      
      <Operation ID="OP_03">
        <Description>Operation 3</Description>
        <Phase ID="SYNTHESIZE">
          <Description>Synthesize phase</Description>
          <PhaseLogic>
            <Step ID="STEP_1"><Action>Initialize</Action></Step>
            <Step ID="STEP_2"><Action>Execute</Action></Step>
            <Step ID="STEP_3"><Action>Complete</Action></Step>
          </PhaseLogic>
        </Phase>
      </Operation>
      
      <Operation ID="OP_04">
        <Description>Operation 4</Description>
        <Phase ID="STRIP">
          <Description>Strip phase</Description>
          <PhaseLogic>
            <Step ID="STEP_1"><Action>Initialize</Action></Step>
            <Step ID="STEP_2"><Action>Execute</Action></Step>
            <Step ID="STEP_3"><Action>Complete</Action></Step>
          </PhaseLogic>
        </Phase>
      </Operation>
      
      <Operation ID="OP_05">
        <Description>Operation 5</Description>
        <Phase ID="CONCENTRATE">
          <Description>Concentrate phase</Description>
          <PhaseLogic>
            <Step ID="STEP_1"><Action>Initialize</Action></Step>
            <Step ID="STEP_2"><Action>Execute</Action></Step>
            <Step ID="STEP_3"><Action>Complete</Action></Step>
          </PhaseLogic>
        </Phase>
      </Operation>
      
      <Operation ID="OP_06">
        <Description>Operation 6</Description>
        <Phase ID="SOLIDIFY">
          <Description>Solidify phase</Description>
          <PhaseLogic>
            <Step ID="STEP_1"><Action>Initialize</Action></Step>
            <Step ID="STEP_2"><Action>Execute</Action></Step>
            <Step ID="STEP_3"><Action>Complete</Action></Step>
          </PhaseLogic>
        </Phase>
      </Operation>
    </UnitProcedure>
  </MasterRecipe>
  
</BatchML>

Process CellPhysical grouping of all production equipment

UnitMajor equipment performing the synthesis

Equipment ModulesIndividual devices: reactors, columns, absorbers

PhasesLowest control level: REACT, SEPARATE, PURIFY

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