Here, it is superheated in pendant tube banks after passing through the top portions of the furnace envelope. When the furnace flow rate is higher than the boiler’s total steam demand at low loads, the balancing header also acts as a way of removing surplus liquid.
Forced circulation powers the high-pressure, drum less water tube steam boiler known as the Benson boiler. By adding feed water at one end and releasing superheated steam at the other, it sets itself apart.
When the feed pump reaches supercritical pressure—beyond the critical threshold of 225 bar—it becomes possible to convert water directly into steam without boiling it first. Reheat, economizer, and air-heating functions are performed by the flue gases, much as in other types of fossil fuel-fired boilers.
Well, in this reading, I’ll be exploring what Benson Boiler is, its application, diagram, parts, advantages and disadvantages & how it’s work.
Let’s Get Started!
What Is Benson Boiler?
Benson boiler is one of the high-pressure boilers having the unique feature of producing steam at supercritical pressure, which means it operates at a pressure and temperature above the critical point of water, resulting in improved thermodynamic efficiency and power generation capabilities.
An example of a once-through boiler is a Benson boiler, which Marc Benson invented in Germany in 1923. Recirculation features are included for part-load operations below about 60° MCR. The furnace envelope of a Benson boiler is typically formed of spirally wrapped small diameter tubes with a bore of around 25 mm.
High sub-critical or supercritical pressure feed water enters the furnace’s bottom and is evaporated to a high grade in the spiral section. Before the steam/water combination is fed to the open boiler pass, a balancing header is often installed near the top of the furnace to mitigate any fluctuations in steam quality caused by variances in heat absorption in various parallel spiral circuits.
Benson boilers are essential components in modern power plants for efficient steam generation, used in both fossil fuel-fired and nuclear power plants. They are crucial in industrial processes requiring high-pressure and supercritical steam, thermal desalination plants, and cogeneration systems for simultaneous heat and power generation. Benson boilers are essential for efficient power generation in Benson plants.
How Does A Benson Boiler Works?
We discussed what a Benson boiler is and the basic idea behind how it operates in the previous parts. In this section, we go into more detail about the four processes that show how a Benson boiler performs its function.
There are no water droplets or steam in a Benson boiler. It will immediately produce steam out of water. Air will be blown into the air preheater by the blower once it starts operating. Hot air is then released once the air preheater has heated the air. The boiler will utilize this heated air for next processes.
The water pressure is raised to the supercritical pressure by the feed pump. The water then goes into the energy-efficient device. To improve the boiler’s efficiency, combustion gases are used in the economizer to warm the water. The water enters the radiant super heater in this stage.
Radiant heat transfer is used in the radiant super heater to heat the water. In this instance, heat is transported from the combustion chamber to the water, which partly turns into steam and partly stays liquid.
This partially evaporated liquid will then be sent onto the convective super heater. The water is completely transformed into vapor or steam in the last phase, which contains the convective super heater. The superheated steam then travels to the prime mover and turns the turbine. This is the operation of a Benson Boiler.
The Benson boiler is a powerful and efficient system that utilizes forced water circulation to deliver water to the combustion chamber at critical pressure. The air preheater preheats the air before entering the combustion chamber, enhancing the boiler’s efficiency.
The economizer uses combustion gases to preheat water, contributing to the overall boiler’s efficiency. The radiant evaporator transfers heat from the economizer to the water, allowing for complete water evaporation.
The convective evaporator transfers heat from flue gases to the water, resulting in complete water evaporation. The convective super heater serves as the final chamber, allowing steam to flow through, elevating the temperature and extracting superheated steam for industrial processes.
Benson Boilers are a cost-efficient and efficient option for heating water. They offer portability, reduced boiler costs due to the absence of a water-steam separator drum, and can reach their maximum load capacity in just 10 minutes. They can accommodate pressures exceeding 350 bar without changing the evaporator.
However, they have disadvantages such as insufficient water supply due to excessive tube temperatures, and the need for accurate synchronization between steam, feed water, and feed input due to restricted storage capacity.
Dirty water can introduce particles and salts, causing damage and clogs. Handling the boiler under different loads can be complex, and routine inspections are essential to prevent explosions due to the supercritical pressure.