How to Understand Circulation ratio in Boilers

The circulation ratio in a boiler refers to the ratio of the mass of water that circulates through the boiler to the mass of steam generated. This parameter is crucial in understanding the efficiency and effectiveness of a boiler's heat exchange process. The circulation ratio is particularly relevant in water-tube boilers and can be defined as follows:
{Circulation Ratio} = {Mass of water circulated}\{Mass of steam generated}
Importance of Circulation Ratio
1. Thermal Efficiency: A higher circulation ratio often indicates a more effective heat transfer, leading to improved thermal efficiency.
2. Boiler Reliability: Proper circulation helps prevent localized overheating and ensures that the heat is evenly distributed, thereby protecting the boiler tubes from damage.
3. Steam Quality: Adequate circulation ensures better separation of steam and water, leading to improved steam quality.
Typical Values
Natural Circulation Boilers: Typically have a circulation ratio ranging from 4:1 to 8:1.
Forced Circulation Boilers: Can have circulation ratios from 10:1 to 50:1, depending on design and operational conditions.
Factors Affecting Circulation Ratio
1. Boiler Design: The design of the boiler, including the configuration of the tubes and the method of heat transfer, affects the circulation ratio.
2. Operating Pressure: Higher operating pressures can reduce the circulation ratio.
3. Heat Flux: The rate of heat transfer impacts the circulation of water and steam within the boiler.
Calculating the Circulation Ratio
To calculate the circulation ratio, you need to measure or estimate the mass flow rate of water circulating through the boiler and the mass flow rate of steam being generated. For example:
1. Mass of Water Circulated: This can be measured using flow meters or estimated based on the pump capacity and operating conditions.
2. Mass of Steam Generated: This is typically measured using steam flow meters or can be calculated based on the boiler’s heat input and steam properties.
For example, if a boiler circulates 10,000 kg of water per hour and produces 2,000 kg of steam per hour, the circulation ratio would be:
Circulation Ratio} = {10,000 }\{2,000 } = 5
This means that for every kilogram of steam generated, 5 kilograms of water are circulated through the boiler.
#boilers, #steam, #powerplant

[@Ankit_Tarpara]

Thank you sir for guidance on boiler operation/ design parameters like circulation ratio..👍

[@audiotimmy29]

Please can you make video on what this that can contribute to reduced efficiency of Gas turbine. And how can exhaust silencer affect the efficiency of the gas turbine Thank you for this topic

[@powerplantguru007]

Sure

[@audiotimmy29]

Good morning pls I just got employed in a power plant and our GT is frame 6B single cycle turbine. We are preparing for MI Overhauling pls how can u help me with necessary materials with details of step by step on how to go about it with proper measurement

[@richardsamuvel3088]

We run the boiler during low load, that time Feed water flow continue up and down (fluctuations) observed.can you pls explain what is the reason sir

[@powerplantguru007]

Hello Thank you for watching my videos.
There may be several reasons for fluctuations at lower load.
1. Control loops are designed for normal load which is normally 40% and above. So lover loads are difficult to maintain.
2. The heat transfer for convective & radiation are changing at different furnace conditions and accordingly steaming pattern changes and it is one of the reasons.
These are a few important ones, we can discuss more on our discussion forums

[@richardsamuvel3088]

@@powerplantguru007 thank you for your reply sir