Skip to main content

Boiler Systems: Troubles in Operation and Their Causes

Definition of boiler systems

Boiler system is a system that is used to heat water and to generate required steam or hot water.

The boiler system is generally composed of the following units:

(a) Feedwater treatment unit: demineralizer, etc.

In case that the raw water is supplied from a river, a lake and so on, the raw water treatment units (clarifier, filter,etc.) are required. 

(b) Feedwater line,

(c) Deaerator,

(d) Boiler including preheater, superheater and desuperheater,

(e) Steam and condensate line,

(f) Condensate treatment unit,

(g) Wastewater treatment unit,

(g) Chemical injection unit.

Classification of boilers by their structures

(1) Cylindrical boilers (pressure : below 20 kgf/cm2) :

(a) Vertical boilers,

(b) Flue-tube boilers,

(c) Fire-tube boilers,

(d) Fire and flue-tube boilers.

(2) Water-tube boilers :

(a) Natural circulation boilers (pressure : low to high),

(b) Forced circulation boilers (pressure : low to high),

(c) Once-through boilers (pressure : above 75 kgf/cm2),

(d) Mini-circulation boilers (packaged type) (pressure : below 30 kgf/cm2).

A typical structure of a water-tube boiler

 

A typical water flow of boiler system


Troubles in Boiler System Operation and Their Causes

Kinds of
problems

Troubles in boiler system
operation

Causes of troubles

Scaling

Reduction of boiler efficiency, Expansion or bursting of heating tubes by overheating.

Leakage of hardness, silica, etc., from softeners or demineralizers, Inadequate blowdown control, Inadequate chemical treatment.

Corrosion

Corrosion damages of boiler systems including feedwater, steam and condensate lines, Scaling troubles caused by corrosion products.

Insufficient deaeration of feedwater,
Inadequate oxygen scavenger treatment,
Insufficient pH control of feedwater, boiler water and condensate.

Carryover

Reduction of steam quality,
Reduction of turbine efficiency by scaling,
Reduction of product quality treated by the steam.

Excess concentration of boiler water,
Contamination of boiler water with organic substances,
Fluctuation of boiler operation load,
Defects of steam separator.

Carryover: Transferring of dissolved solids in boiler water into the steam line.
Labels:

Comments

Post a Comment

Popular posts from this blog

Maintenance 4.0 Implementation Handbook (pdf)

WHAT IS MAINTENANCE 4.0? Industry 4.0 is a name given to the current trend of automation and data exchange in industrial technologies. It includes the Industrial Internet of things (IIoT), wireless sensors, cloud computing, artificial intelligence (AI) and machine learning. Industry 4.0 is commonly referred to as the fourth industrial revolution. Maintenance 4.0 is a machine-assisted digital version of all the things we have been doing for the past forty years as humans to ensure our assets deliver value for our organization. Maintenance 4.0 includes a holistic view of sources of data, ways to connect, ways to collect, ways to analyze and recommended actions to take in order to ensure asset function (reliability) and value (asset management) are digitally assisted. For example, traditional Maintenance 1.0 includes sending highly-trained specialists to collect machinery vibration analysis readings on pumps, motors and gearboxes. Maintenance 4.0 includes a wireless vibration sensor conne...
Post a Comment
[Read more...]

Technical questions with answers on gas turbines

By NTS. What is a gas turbine? A gas turbine is an engine that converts the energy from a flow of gas into mechanical energy. How does a gas turbine work? Gas turbines work on the Brayton cycle, which involves compressing air, mixing it with fuel, and igniting the mixture to create a high-temperature, high-pressure gas. This gas expands through a turbine, which generates mechanical energy that can be used to power a variety of machines and equipment. What are the different types of gas turbines? There are three main types of gas turbines: aeroderivative , industrial, and heavy-duty. Aeroderivative gas turbines are used in aviation and small-scale power generation. Industrial gas turbines are used in power generation and other industrial applications. Heavy-duty gas turbines are typically used in large power plants. What are the main components of a gas turbine? The main components of a gas turbine include the compressor, combustion chamb...
Post a Comment
[Read more...]

Top 8 Reasons for Mechanical Seal Failure and How to Prevent Them

Mechanical seals are critical components of pumps, responsible for maintaining a fluid-tight seal between the rotating shaft and the stationary pump housing. However, these seals can fail due to various factors, leading to leakage, reduced pump efficiency, and costly downtime. In this article, we will discuss the top reasons for mechanical seal failure in pumps and how to prevent them. 1-Improper Seal Selection Choosing the wrong mechanical seal can cause it to fail. Consider the following factors that can contribute to seal failure: • Chemical compatibility: All seal components, such as the seal faces and O-rings, must be compatible not only with the process fluid being pumped, but also with non-process fluids used for cleaning, steam, acid, and caustic flushes, etc. • Physical degradation: Using soft seal faces on abrasive liquids will not last. Shear-sensitive liquids, like chocolate, can break down and leave behind solids (such as cocoa powder) and force out liquids (like oil). • S...
Post a Comment
[Read more...]

Why Pump Shafts Often Break at the Keyway Area

By NTS Pump shaft failure can lead to significant downtime and repair costs in industrial plants. One of the most common locations for pump shaft failure is at the keyway area. In this article, we will explore the reasons why pump shafts often break at the keyway and what can be done to prevent such failures. The keyway is a high-stress point (weakest point)  on the shaft, where a key is inserted to transmit torque between the shaft and the pump impeller or coupling. During operation, the keyway experiences cyclic loading that creates a bending moment in the shaft, which is concentrated in the keyway area. Over time, this cyclic loading can cause fatigue failure in the shaft material, leading to a fracture at the keyway. In addition to cyclic loading, other factors can contribute to shaft failure at the keyway. Improper keyway design or installation can lead to stress concentrations or inadequate clearance between the key and keyway . Misalignment or overloading can also cause ex...
Post a Comment
[Read more...]

Pump Shaft Breakage: Case Studies and Solutions

By NTS Pump shaft breakage is a common issue that can cause costly downtime and repairs in various industries. In this article, we will explore several case studies of pump shaft breakage and the solutions implemented to prevent future failures. Case Study 1: Chemical Processing Plant A chemical processing plant experienced repeated pump shaft breakages in their cooling water pumps. Investigation revealed that the pumps were not properly aligned with the motor and had excessive vibration due to the misalignment. This caused the pump shaft to fatigue and break over time. The problem was resolved by realigning the pumps and installing vibration monitoring equipment to detect any future misalignment or excessive vibration. Case Study 2: Wastewater Treatment Plant A wastewater treatment plant had issues with pump shaft breakage in their sludge pumps. The pumps were designed with a straight shaft and lacked a flexible coupling, causing excessive stress and vibration on the pump sha...
Post a Comment
[Read more...]