Blowdown Vessel Control Systems

Blowdown vessel control systems are essential for maintaining the safe, efficient, and sustainable operation of boiler systems. These systems regulate the removal of dissolved and suspended impurities from the boiler water, helping to preserve optimal water quality and protect internal components from damage. A critical element of effective boiler house management is ensuring high-quality feedwater. Poor water quality is one of the primary causes of boiler failure, with up to 90% of breakdowns attributed to pipe corrosion. This corrosion is often caused by impurities left untreated in the system making precise and consistent blowdown control not just beneficial, but essential.

Why is blowdown necessary?

Industrial boilers require clean water to operate efficiently. Filling a boiler with untreated tap water would cause significant damage due to:

  • High oxygen levels, which contribute to internal corrosion.
  • Total Dissolved Solids (TDS), including carbonates that cause scale build-up and reduce heat transfer efficiency.

While boilers are typically fed with pre-treated water via a hotwell, this does not eliminate all impurities. Over time, oxygen ingress and TDS accumulation introduce contaminants into the system. To prevent damage, boilers require regular blowdown cycles to remove these impurities.

typical frequency blowdown is needed:

  • With perfectly conditioned water, blowdown may only be needed every three days.
  • In standard operations, daily blowdown is typically required to maintain efficiency.

 

Role of the blowdown vessel

Blowdown discharge is extremely hot if released directly into pipework, it could cause severe thermal damage. A blowdown vessel plays a critical role in ensuring safe handling by:

  • Collecting and cooling the discharged water using a cold water injection system.
  • Lowering the temperature to a safe level before it is expelled.
  • Managing pressure and flow to prevent damage to downstream piping.

Types of blowdown control

Blowdown control is achieved through two key mechanisms, each targeting different types of contaminants:

TDS control (Top blowdown)
  • Located at the interface between the steam and water space.
  • A probe continuously measures conductivity to monitor water quality.
  • If TDS levels exceed a pre-set threshold, the system modulates a valve to remove contaminated water, skimming it off to the blowdown vessel.
Bottom blowdown
  • Targets sludge accumulation at the base of the boiler.
  • Automatically opens for a set duration (typically 10 seconds per day) to remove settled solids.
  • Prevents build-up that could restrict heat transfer and lead to inefficiencies.

Key benefits of an automated blowdown vessel control system

Implementing a blowdown control system optimises both safety and efficiency, ensuring that:

Maximum boiler efficiency is maintained:

Operational safety is enhanced:

No manual monitoring required:

By integrating automated blowdown control, plants can significantly extend boiler lifespan, reduce downtime, and improve energy efficiency.

Why choose Dunphy?

We’re the leading provider of combustion equipment in the UK and have over 50 years’ worth of experience in the industry. This means there’s no better choice for your boiler house repairs. Get in touch with a member of our expert team to learn more.

Accreditations

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