Boiler Feed Water
Control Systems

Critical for Boiler Safety & Efficiency

Boiler feed water control systems maintain the correct water level in the boiler drum at all times and under all load conditions. Proper feed water control is essential for:

• ✓ Preventing low water conditions that can cause overheating and tube failure
• ✓ Preventing high water conditions that can cause carryover and turbine damage
• ✓ Maintaining stable steam pressure and temperature
• ✓ Optimizing boiler efficiency and reducing fuel consumption
• ✓ Protecting boiler internals from thermal stress
• ✓ Meeting class society requirements for boiler safety

Control Strategies

• ✓ Single-Element Control – Drum level only (small boilers, steady load)
• ✓ Two-Element Control – Drum level + steam flow (feed-forward)
• ✓ Three-Element Control – Drum level + steam flow + feed water flow (most common for marine boilers)
• ✓ Cascade Control – Master/slave control loops
• ✓ Feed Pump Speed Control – VFD or turbine-driven pumps
• ✓ Feed Water Valve Control – Modulating control valves

How Three-Element Control Works

Three-element control is the most advanced and accurate method for boiler drum level control, especially under varying load conditions.

• ✓ Element 1: Drum Level – Primary controlled variable
• ✓ Element 2: Steam Flow – Feed-forward signal for load changes
• ✓ Element 3: Feed Water Flow – Feedback signal for mass balance

The controller compares these three signals and adjusts the feed water control valve or feed pump speed to maintain precise drum level regardless of steam demand fluctuations.

Benefits of Three-Element Control

• ✓ Eliminates “Shrink & Swell” Effect – Compensates for apparent level changes during load changes
• ✓ Precise Level Control – ±1% accuracy even during rapid load changes
• ✓ Reduces Thermal Stress – Prevents sudden temperature changes in drum
• ✓ Improves Steam Quality – Prevents carryover and water droplets in steam
• ✓ Energy Efficiency – Optimized feed water usage
• ✓ Extended Boiler Life – Reduces thermal cycling fatigue

Feed Pump Types

• ✓ Centrifugal Pumps – Most common for marine boilers
• ✓ Turbine-Driven Pumps – Steam turbine driven for efficiency
• ✓ Motor-Driven Pumps – Electric motor driven
• ✓ Reciprocating Pumps – For high-pressure applications
• ✓ Booster Pumps – For deaerator to main pump suction
• ✓ Manufacturers – KSB, Sulzer, Flowserve, Grundfos

Pump Control Methods

• ✓ On/Off Control – Start/stop based on drum level
• ✓ Throttling Control – Feed water valve modulation
• ✓ Variable Speed Control (VFD) – Most efficient method
• ✓ Hydraulic Coupling Control – Variable speed fluid couplings
• ✓ Turbine Speed Control – Governor control for turbine pumps
• ✓ Pump Sequencing – Lead/lag control for multiple pumps

• ✓ Yokogawa – DCS, controllers, transmitters (EJX, EJA series)
• ✓ Siemens – PLC, S7, PCS7, transmitters (SITRANS series)
• ✓ ABB – Controllers, drives, instrumentation (2600T series)
• ✓ Honeywell – Controllers, recorders, transmitters (ST series)
• ✓ Rosemount – Pressure, level, flow transmitters (3051, 2051 series)
• ✓ Endress+Hauser – Level, flow, pressure instrumentation
• ✓ Fisher – Control valves, regulators, positioners (DVC series)
• ✓ Masoneilan – Control valves, level controllers (SVI series)
• ✓ Samson – Control valves, positioners, controllers (3730 series)
• ✓ Flowserve – Valves, pumps, seals (Logix positioners)
• ✓ KSB – Feed pumps, valves
• ✓ Sulzer – Feed pumps, turbomachinery
• ✓ Rotork – Electric actuators (IQ series)
• ✓ Auma – Electric actuators (SAR, SA series)
• ✓ Spirax Sarco – Condensate control, steam traps
• ✓ Armstrong – Steam traps, condensate control
• ✓ TLV – Steam traps, condensate recovery
• ✓ Cochrane – Deaerators, feed water systems
• ✓ Stork – Deaerators, feed water systems
• ✓ Alfa Laval – Deaerators, heat exchangers

• ✓ VLCC / ULCC Tankers – Crude oil carriers (300K DWT+)
• ✓ Suezmax Tankers – Crude oil carriers
• ✓ Aframax Tankers – Product and crude carriers
• ✓ Chemical Tankers – Product and chemical carriers
• ✓ LNG Carriers – Membrane & Moss type (Q-Flex, Q-Max)
• ✓ LPG Carriers – Fully refrigerated & semi-ref
• ✓ FPSO / FSO – Floating production units
• ✓ Drillships – Deepwater drilling
• ✓ Semi-submersibles – Drilling rigs
• ✓ Jack-up Rigs – Self-elevating units
• ✓ Container Vessels – Feeder to ULCS (10,000 TEU+)
• ✓ Bulk Carriers – Handy to Capesize (Newcastlemax)
• ✓ Cruise Ships – Passenger vessels (Oasis class, etc.)
• ✓ Ro-Ro / Ferries – Roll-on roll-off
• ✓ Naval Vessels – Frigates, destroyers, carriers
• ✓ Offshore Platforms – Fixed & floating
• ✓ PSV / AHTS – Offshore supply vessels (UT design, VS design)
• ✓ Dredgers – Hopper & cutter suction
• ✓ Heavy Lift Vessels – Semi-submersible heavy lift
• ✓ Cable Layers – Specialized vessels

• ✓ UAE – Dubai, Abu Dhabi, Fujairah, Sharjah
• ✓ India – Mumbai, Kochi, Chennai, Kolkata, Goa
• ✓ Singapore – Jurong, Tuas, Keppel, Sembawang
• ✓ Netherlands – Rotterdam, Amsterdam, IJmuiden
• ✓ Norway – Bergen, Stavanger, Oslo, Kristiansand
• ✓ Greece – Piraeus, Athens, Thessaloniki
• ✓ UK – Aberdeen, London, Southampton, Falmouth
• ✓ USA – Houston, New Orleans, Norfolk, Los Angeles
• ✓ Brazil – Rio de Janeiro, Santos, Macaé
• ✓ China – Shanghai, Hong Kong, Shenzhen, Dalian
• ✓ South Korea – Busan, Ulsan, Geoje
• ✓ Japan – Tokyo, Yokohama, Kobe, Nagasaki
• ✓ Middle East – Bahrain, Qatar, Kuwait, Oman
• ✓ Africa – Nigeria, South Africa, Egypt, Angola
• ✓ Australia – Perth, Sydney, Melbourne, Brisbane
• ✓ Any major port worldwide – 24/7 emergency response