Urea

Molecular Structure

Molecular Details

Molecular Formula	(NH₂)₂CO
Molecular Weight	60.06 g/mol
State	Solid at standard conditions

Olefinverbund Integration

Chemistry & Engineering

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

Extraterrestrial Production Pattern

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

Applications

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

Reaction Diagram

Overall Reaction: 2NH3 + CO2 -> (NH2)2CO + H2O

Unit Operations

Process steps following chemical engineering unit operation principles:

Step	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

This module follows the ISA-88 (S88) batch control standard. Below is a simplified BatchML schema 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>

**Key S88 Concepts:**
- **Process Cell**: The physical grouping containing all equipment for this process
- **Unit**: The major equipment that performs the synthesis
- **Equipment Modules**: Individual pieces of equipment (reactors, columns, etc.)
- **Unit Procedure**: The sequence of operations to produce the product
- **Phases**: The lowest level of procedural control (e.g., REACT, SEPARATE, PURIFY)

Key S88 Concepts:
• Process Cell: Physical grouping containing all equipment
• Unit: Major equipment performing synthesis
• Equipment Modules: Individual pieces (reactors, columns, etc.)
• Phases: Lowest level of procedural control (REACT, SEPARATE, etc.)

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This Synthesis Module is part of the 100chemicals Olefinverbund — an integrated chemical production network designed for extraterrestrial civilization on Moon and Mars.