New Heat Exchanger Coating Resists Adhesion, Corrosion, Microbes, Nanocoating claims triple benefits

GERMANY: A new nanocoating developed for heat exchangers with anti-adhesive, anti-corrosive and anti-microbial properties could find ready acceptance in the air conditioning industry.


The Saarbrücken-based Leibniz Institute for New Materials is demonstrating the possibilities for the new coating at this year’s Hannover Messe which takes place in April.


 The coating is aimed initially at the food industry where heat exchangers are used extensively by companies such as milk and juice processors. In order to ensure there is no risk to consumers, heat exchangers in these areas have to be free from microbes and must be cleaned at regular intervals using aggressive chemicals. These increase the sensitivity for corrosion, especially if mild steel is used as heat exchanger material.
According to Carsten Becker-Willinger, head of Nanomers at the Leibniz Institute for New Materials, the paint developed could also be used in other contexts, including air conditioning and water purification plants.


The developers achieve the anti-adhesive characteristics in the new coating by introducing hydrophobic compounds that are similar to common Teflon. These inhibit the formation of any undesired biofilm and allow residues to be transported out more easily before they clog up the channels of the heat exchangers. The coating also acts as a diffusion barrier, inhibiting corrosion by corrosive substances or aggressive cleaning agents. Colloidal copper is also used in the coating to prevent microbes, bacteria or fungus from adhering to surfaces.


 “In addition, we can keep the paint chemically stable. Otherwise it would not withstand the aggressive chemicals that are required for cleaning,” explained Carsten Becker-Willinger.


The coating could also be adapted for special mechanical loads where, due to mechanical vibrations, the individual heat exchanger plates could be subjected to a certain amount of abrasion at points of contact.


 The paint can be applied using standard methods such as spraying or immersion and subsequent hardening. It can be used on stainless steel, steel, titanium or aluminium.


The Leibniz Institute for New Materials is a leading center for materials research, conducting research into nanocomposite technology, interface materials, and bio interfaces.

Steam Turbines New steam turbine controller promises easy installation

Voith’s range of digital steam turbine controllers has been extended with the new TurCon DTc. This compact model can be set up quickly and easily to perform all standard control functions on mechanical driven machines and generators. The new controller is “pre-engineered” and suitable for steam turbines of all power classes.
 Fast, simple and cost-effective system integration with the best possible reliability, process quality, productivity and safety are the typical customer specifications for modern steam turbine controllers. Decision-makers of OEMs or engineering contractors and modernizers looking to minimize costs prefer to use controllers that dispense with elaborate installation processes and offer a high degree of flexibility. Operators of steam turbines expect a reliable product that uses proven control algorithms to ensure high process quality and productivity.Because the controller is “pre-engineered” the customer only has to set the selected parameters, which keeps installation work to a minimum. There is no need to buy additional special software; data can be displayed at any time via the control panel or via the connected control system.
 The TurCon DTc consists of two rugged assemblies, an intuitive 7″ TFT-LCD touchscreen control panel with integrated CPU and a remote I/O unit. The controller can be integrated into existing Industry 4.0 environments via a standardized Ethernet interface with Modbus TCP or OPC. An optional control panel or PC can be connected via the LAN interface, for example as part of a commissioning process or remote monitoring scenario.
 The option of simultaneously controlling a maximum of 4 HP and 2 LP control valves is another special feature of the TurCon DTc. This means that there is no need to adjust the valves mechanically using a camshaft or via a separate valve coordinator (split range).
Other key elements ensuring reliability and availability include the three frequency inputs with a 2-out-of-3 voting for the speed sensors. The fault-tolerant speed measuring equipment offers high reliability and availability. An integrated simulation mode allows commissioning personnel to check whether the parameter settings are actually correct and improve them if necessary prior to hot commissioning. This minimizes the risk of damage due to incorrect parameters.
 The TurCon DTc archives the last 1,000 status, warning and alarm messages with a time stamp, allowing process flows and malfunctions to be easily identified and traced. As a result, fast, targeted optimizations are possible.
 Voith Digital Solutions bundles Voith’s long standing automation and IT expertise with the know-how in the fields of water power, paper machines and drive engineering.

Gas Turbines: How ambient temperature affects gas turbine types

Changes in ambient temperature have an impact on fullload power and heat rate of a gas turbine, but also on part-load performance and optimum power turbine speed. Manufacturers typically provide performance maps that describe these relationships for ISO conditions.
The excerpts are taken from a paper “Gas turbine performance” presented by Rainer Kurz of Solar Turbines and Klaus Brun of Southwest Research Institute at the 2015 Middle East Turbomachinery Symposium.
The performance curves are the result of the interaction between the various rotating components and the control system. This is particularly true for DLN engines. If the ambient temperature changes, the engine is subject to the following effects:
The air density changes. Increased ambient temperature lowers the density of the inlet air, thus reducing the mass flow through the turbine, and therefore reduces the power output (which is proportional to the mass flow) even further. At constant speed, where the volume flow remains approximately constant, the mass flow will increase with decreasing temperature and will decrease with increasing temperature.
The pressure ratio of the compressor at constant speed gets smaller with increasing temperature. This can be determined from a Mollier diagram, showing that the higher the inlet temperature is, the more work (or head)is required to achieve a certain pressure rise. The increased work has to be provided by the gas generator turbine, and is thus lost for the power turbine, as can be seen in the enthalpy-entropy diagram. At the same time NGgcorr (ie the machine Mach number) at constant speed is reduced at higher ambient temperature. As explained previously, the inlet Mach number of the engine compressor will increase for a given speed, if the ambient temperature is reduced. The gas generator Mach number will increase for reduced firing temperature at constant gas generator speed.
The Enthalpy-Entropy Diagram describes the Brayton cycle for a two-shaft gas turbine. Because the head produced by the compressor is proportional to the speed squared, it will not change if the speed remains the same. However, the pressure ratio produced, and thus the discharge pressure, will be lower than before. Looking at the combustion process, with a higher compressor discharge temperature and considering that the firing temperature is limited, we see that less heat input is possible, ie., less fuel will be consumed .The expansion process has less pressure ratio available or a larger part of the available expansion work is being used up in the gas generator turbine, leaving less work available for the power turbine.
On two-shaft engines, a reduction in gas generator speed occurs at high ambient temperatures. This is due to the fact that the equilibrium condition between the power requirement of the compressor (which increases at high ambient temperatures if the pressure ratio must be maintained) and the power production by the gas generator turbine (which is not directly influenced by the ambient temperature as long as compressor discharge pressure and firing temperature remain) will be satisfied at a lower speed. The lower speed often leads to a reduction of turbine efficiency: The inlet volumetric flow into the gas generator turbine is determined by the first stage turbine nozzle, and the Q3/NGG ratio (i.e., the operating point of the gas generator turbine) therefore moves away from the optimum.
Variable compressor guide vanes allow keeping the gas generator speed constant at higher ambient temperatures, thus avoiding efficiency penalties. In a single-shaft, constant speed gas turbine one would see a constant head (because the head stays roughly constant for a constant compressor speed), and thus a reduced pressure ratio. Because the flow capacity of the turbine section determines the pressure-flow-firing temperature relationship, equilibrium will be found at a lower flow, and a lower pressure ratio, thus a reduced power output.
The compressor discharge temperature at constant speed increases with increasing temperature. Thus, the amount of heat that can be added to the gas at a given maximum firing temperature is reduced.
The relevant Reynolds number changes: At full load, single-shaft engines will run a temperature topping at all ambient temperatures, while two-shaft engines will run either at temperature topping (at ambient temperatures higher than the match temperature) or at speed topping (at ambient temperatures lower than the match temperature). At speed topping, the engine will not reach its full firing temperature, while at temperature topping, the engine will not reach its maximum speed. The net effect of higher ambient temperatures is an increase in heat rate and a reduction in power. The impact of ambient temperature is usually less pronounced for the heat rate than for the power output, because changes in the ambient temperature impact less the component efficiencies than the overall cycle output.
By TMI Staff & Contributors
IESG Engineering have a service generating performance models of equipment (gas turbines, generators, boilers, HRSGs, SCRs and other equipment) based on different percentage loads and seasons, minimizing downtime and maximizing performance.

Energy Sources

Over the last 200 years an ever-increasing proportion of our energy has come from non-renewable sources such as oil and coal. While demand for energy rises these resources are running out and scientists are exploring the potential of renewable sources of energy for the future.
Renewable and non-renewable energy resources All life on earth is sustained by energy from the sun. Plants and animals can store energy and some of this energy remains with them when they die. It is the remains of these ancient animals and plants that make up fossil fuels. Fossil fuels are non-renewable because they will run out one day. Burning fossil fuels generates greenhouse gases and relying on them for energy generation is unsustainable. Hence the need to find more renewable, sustainable ways of generating energy. Renewable or infinite energy resources are sources of power that quickly replenish themselves and can be used again and again. Some resources can be thought of as both renewable and non-renewable.
  • Wood can be used for fuel and is renewable if trees are replanted.
  • Biomass, which is material from living things, can be renewable if plants are replanted.
Non-renewable energy resources


Watch below table in a Wide Screen mode for a mobile option.
Type of fuel


               Where it is from

Coal (fossil fuel)
  • Formed from fossilised plants and consisting of carbon with various organic and some inorganic compounds.
  • Mined from seams of coal, found sandwiched between layers of rock in the earth.
  • Burnt to provide heat or electricity.
  • Ready-made fuel.
  • It is relatively cheap to mine and to convert into energy.
  • Coal supplies will last longer than oil or gas.
  • When burned coal gives off atmospheric pollutants, including greenhouse gases.
Oil (fossil fuel)
  • A carbon-based liquid formed from fossilized animals.
  • Lakes of oil are sandwiched between seams of rock in the earth.
  • Pipes are sunk down to the reservoirs to pump the oil out.
  • Widely used in industry and transport.
  • Oil is a ready-made fuel.
  • Relatively cheap to extract and to convert into energy.
  • When burned, it gives off atmospheric pollutants, including greenhouse gases.
  • Only a limited supply.
Natural gas (fossil fuel)
  • Methane and some other gases trapped between seams of rock under the earth's surface.
  • Pipes are sunk into the ground to release the gas.
  • Often used in houses for heating and cooking.
  • Gas is a ready-made fuel.
  • It is a relatively cheap form of energy.
  • It's a slightly cleaner fuel than coal and oil.
  • When burned, it gives off atmospheric pollutants, including greenhouse gases.
  • Only limited supply of gas.
  • Radioactive minerals such as uranium are mined.
  • Electricity is generated from the energy that is released when the atoms of these minerals are split (by nuclear fission) in nuclear reactors.
  • A small amount of radioactive material produces a lot of energy.
  • Raw materials are relatively cheap and can last quite a long time.
  • It doesn't give off atmospheric pollutants.
  • Nuclear reactors are expensive to run.
  • Nuclear waste is highly toxic, and needs to be safely stored for hundreds or thousands of years (storage is extremely expensive).
  • Leakage of nuclear materials can have a devastating impact on people and the environment. The worst nuclear reactor accident was at Chernobyl, Ukraine in 1986.
  • Biomass energy is generated from decaying plant or animal waste.
  • It can also be an organic material which is burned to provide energy, eg heat, or electricity.
  • An example of biomass energy is oilseed rape (yellow flowers you see in the UK in summer), which produces oil.
  • After treatment with chemicals it can be used as a fuel in diesel engines.
  • It is a cheap and readily available source of energy.
  • If the crops are replaced, biomass can be a long-term, sustainable energy source.
  • When burned, it gives off atmospheric pollutants, including greenhouse gases. If crops are not replanted, biomass is a non-renewable resource.
  • Obtained from felling trees, burned to generate heat and light.
  • A cheap and readily available source of energy.
  • If the trees are replaced, wood burning can be a long-term, sustainable energy source.

  • When burned it gives off atmospheric pollutants, including greenhouse gases.
  • If trees are not replanted wood is a non-renewable resource.
How long will fossil fuels last? Estimates from international organizations suggest that if the world’s demand for
energy from fossil fuels continues at the present rate that oil and gas reserves may run out within some of our lifetimes. Coal is expected to last longer. Estimated length of time left for fossil fuels
Fossil fuel
Time left
50 years
Natural gas
70 years
250 years


Next-Generation Wind Technology

Innovation in the design and manufacturing of wind power generation components continues to be critical to achieving our national renewable energy goals. As a result of this challenge, the U.S. Department of Energy’s Wind Program and Advanced Manufacturing Office are partnering with public and private organizations to apply additive manufacturing, commonly known as 3D printing, to the production of wind turbine blade molds.
The Wind Program works with industry partners to increase the performance and reliability of next-generation wind technologies while lowering the cost of wind energy. The program’s research efforts have helped to increase the average capacity factor (a measure of power plant productivity) from 22% for wind turbines installed before 1998 to an average of 33% today, up from 30% in 2000. Wind energy costs have been reduced from over 55 cents (current dollars) per kilowatt-hour (kWh) in 1980 to an average of 2.35 cents in the United States today.
To ensure future industry growth, the technology must continue to evolve, building on earlier successes to further improve reliability, increase capacity factors, and reduce costs. This page describes the goal of the program’s large wind technology research efforts and highlights some of its recent projects.
The newest inventions coming out of the DOE Wind Program can also be found on the Energy Innovation Portal, which houses all technologies available for licensing funded by the DOE’s Office of Energy Efficiency and Renewable Energy.
Research Project Highlights
These are some of the key research project highlights from the program’s next-generation wind technology research. From 2006 to 2014, the Wind Program provided awards totaling more than $160 million for projects focused on testing, manufacturing, and component development.
Prototype Development
Modern wind turbines are increasingly cost-effective and more reliable, and have scaled up in size to multi-megawatt power ratings. Since 1999, the average turbine generating capacity has increased, with turbines installed in 2014 averaging 1.9 MW of capacity. Wind Program research has helped facilitate this transition, through the development of longer, lighter rotor blades, taller towers, more reliable drivetrains, and performance-optimizing control systems. Furthermore, improved turbine performance has led to a more robust domestic wind industry that saw wind turbine technology exports grow from $16 million in 2007 to $488 million in 2014.
During the past two decades, the program has worked with industry to develop a number of prototype technologies, many of which have become commercially viable products. One example is the GE Wind Energy 1.5-megawatt (MW) wind turbine. Since the early 1990s, the program worked with GE and its predecessors to test components such as blades, generators, and control systems on generations of turbine designs that led to GE’s 1.5-MW model. The GE 1.5 constitutes approximately half of the nation’s installed commercial wind energy fleet, and is a major competitor in global markets.
Component Development
The program works with industry partners to improve the performance and reliability of system components. Knight and Carver’s Wind Blade Division in National City, California, worked with researchers at the Department of Energy’s Sandia National Laboratories to develop an innovative wind turbine blade that has led to an increase in energy capture by 12% The most distinctive characteristic of the Sweep Twist Adaptive Rotor (STAR) blade is a gently curved tip, which, unlike the vast majority of blades in use, is specially designed to take maximum advantage of all wind speeds, including slower speeds.
To support the development of more reliable gearboxes, the program has worked with several companies to design and test innovative drivetrain concepts. Through the support of $47 million in DOE funding, the nation’s largest and one of the world’s most advanced wind energy testing facilities was opened at Clemson University to help speed the deployment of next generation energy technology, reduce costs for manufacturers and boost global competitiveness for American companies. The Clemson facility is equipped with two testing bays – for up to 7.5-megawatt and 15-megawatt drivetrains, respectively. The Clemson facility also features a grid simulator that mimics real-world conditions, helping researchers better study the interactions between wind energy technologies and the U.S. power grid.
Utility-Scale Research Turbine
In 2009, the program installed a GE 1.5-MW wind turbine at the National Wind Technology Center (NWTC) located on the National Renewable Energy Laboratory campus in Boulder, Colorado. This turbine was the first large-scale wind turbine fully owned by DOE and serves as a platform for research projects aimed at improving the performance of wind technology and lowering the costs of wind energy. The NWTC is now collaborating with Siemens Energy to conduct aerodynamic field experiments on a 2.3-MW wind turbine. These experiments utilize sonic as well as conventional anemometers and wind vanes on the NWTC’s 135 meter meteorological tower to measure characteristics such as inflow, turbine response, and wind wake. The data gained from these experiments will provide new insights into multi-megawatt turbine aerodynamic response, structural loading, power production, and fatigue life that can be used to increase reliability and performance. The research being done at the NWTC complements DOE’s Atmosphere to Electrons (A2e) initiative that targets significant reductions in the cost of wind energy through an improved understanding of the complex physics governing wind flow into and through wind farms.



HRSG steam pipe leaks downstream of the attemperators.

When we are talking about any kind of vehicle or a combined cycle plant, the crucial point to successful operation of any power equipment is an effective maintenance plan. This aids maintenance managers strategize ahead, minimize unforeseen failures, and accommodate limitations forced by financial and outage resources. Cost, outage time and contractor manpower are some of the factors to be considered.
Each plant may select a different maintenance plan. Some may want to max up the synchronization of Heat Recovery Steam Turbine (HRSG) maintenance with the overhaul of the gas turbine (GT) or steam turbine (ST) to exploit outage time. Others may struggle to level their costs by fluctuating as much HRSG maintenance to the years before or after the GT and ST outage window to avoid large peaks in annual maintenance costs.
This is important when you take into consideration the fact that hundreds of F-class or larger HRSGs were commissioned in the 2000-to-2005 time period. Therefore many are about half-way through their original specified design life.
Figure 1: Replacement of attemperator piping must be planned well in advance

Figure 1: Replacement of attemperator piping must be planned well in advance

Component redesigns
Factor in the severe increase in plants conducting HRSG cycling, and many of these HRSGs can presume to need major component redesigns and replacements in the next ten years. Consequently combined cycle power plants will need more attention and coordination over the next few years than they did in the earlier ten to identify and plan for the possibility of HRSG capital projects.
There are many large HRSG projects that managers of combined cycle plants should evaluate thoroughly and include in any predictions being done as part of GT and ST maintenance planning. Attemperator piping failure and replacement is a vital area to take into account (Figure 1).
Problems in this part of the HRSG are frequently caused by a desuperheater overspray and short distance from a feedwater inlet to downstream elbow where liquid water is not able to completely vaporize before it comes into contact with a pipe and extinguishes it.
Desuperheater overspray is an operational problem and can happen when steam is sprayed to saturation or within 50°F of saturation temperature. But even well designed and correctly operated desuperheater arrangements can experience a pipe failure.
All it takes is one leaky feedwater valve or faulty desuperheater probe. Some gas turbine upgrades from OEMs that allow lower loads and changes to the turbine exhaust conditions can aggravate this problem. Issues with attemperator piping are no small matter as redesigned piping systems can take 40 or more weeks to design and supply. Their assessment involves visual inspection of superheaters and reheaters for bowing, check of performance data to look for indicators of overspray, and quality non-destructive evaluation (NDE) of piping locations at risk to stress and cracking.
Another common area of combined cycle maintenance is duct burner replacement. This occurs due to burner failure from cracking initiated at the nozzles or from overheated, warped and burnt away components. Detection requires visual inspection, both off-line and on-line, and review of maintenance history of comparable designs (Pictures 3 & 4 in the slideshow).
Poor burner flame patterns or burner element failures may force a derate of a steam turbine generator from its maximum full-load, full-duct firing power output. A burner derate on one HRSG can affect not only that HRSG, it can also derate adjacent HRSGs if they are part of a 2×1, 3×1 or 4×1 steam turbine configuration within a combined cycle plant.
Figure 2: A badly bowed duct burner inside HRSG

Figure 2: A badly bowed duct burner inside HRSG

With full-duct firing at full load, it becomes important to have relatively balanced steam flows across each HRSG to elude tube overheat issues. The challenging side of a thorough duct burner inspection, however, is inspecting elements at higher elevations.
It would consequently be wise for maintenance managers to plan on building a scaffold, mobilizing a Sky Climber or even a drone examination as a part of a regular maintenance. This is especially significant if a history of duct burner complications already exists.

New era of Natural Gas Production

About five years ago, when natural gas prices continued to linger at historic lows, I was one of many who predicted a quick return to the volatility once synonymous with the natural gas market.
Today’s unflappable, low-priced environment is in stark contrast to the Wild West exploration and production market of the past.
It was not unusual for natural gas prices to spike from $2 per million Btu (MMBtu) to $14 per MMBtu in a matter of months. Drilling rigs would be deployed en masse, supplies would slowly replenish and prices would drop. The boom-bust cycle would be repeated for several decades. Like the sunrise and sunset, it was a customary and familiar occurrence.
But this fundamental assumption about the natural gas market is no longer true. Turns out the generous estimates of recoverable gas supplies in the U.S., which were questioned by many skeptics, are more precise than we thought.
In the U.S., we no longer have to wage an extensive search for new supplies or deploy a fleet of drilling rigs to exploit them. Over the years, natural gas producers have tapped into immense natural gas resources that have long been trapped in a thin, nonporous rock known as shale. Bringing in more supply is as simple as turning on a spigot.
Thanks to new production methods, including hydraulic fracturing and horizontal drilling, natural gas production in the U.S. has fundamentally changed. Specifically, producers can ramp up gas production much more quickly in response to rising demand, which means we may have entered an era of long-term stability in the price of natural gas in the U.S.
According to a new study released last month by Resources for the Future (RFF), a think tank devoted to the research and analysis of natural resources, natural gas produced from unconventional resources such as shale are 2.7 times more responsive to changes in demand than conventional production. The reason is this: Unconventional wells produce significantly more gas at a consistent and faster flow rate. RFF researchers said production from these wells behaved more like a “manufacturing process.”
Today, natural gas produced from shale formations account for 50 percent of U.S. natural gas production, according to the Energy Information Administration (EIA). What’s more, natural gas production from shale is projected to rise over the next 24 years, accounting for nearly 70 percent of U.S. gas production by 2040.
This means the return on investments in gas-fired power generation will be greater versus the building booms of the past, when gas-fired plants built on the promise of low-cost fuel were shut down amid sharp spikes in the price of gas.
Power generation will account for 34 percent of the growth in natural gas consumption between 2015 and 2040, according EIA. During the 25-year period, natural gas consumption in the U.S will rise 1 percent a year, from 28 trillion cubic feet (Tcf) in 2015 to 34 Tcf in 2040.
Nearly 19,000 MW of power generation fueled with natural gas is expected to be built and commissioned in the U.S. between 2016 and 2018. Not surprisingly, much of that capacity (52 percent) is being built near shale formations.
According to data released earlier this month by the EIA, natural gas was by far the leading source of generation in the U.S. during the first half of 2016. Natural gas accounted for 33.5 percent of electricity produced through June while coal accounted for 28.1 percent.
What’s more, power produced with natural gas reached an all-time high in July. In EIA’s short-term energy outlook, the agency found that gas-fired power plants generated 4,950 gigawatt-hours of power each day in July, up 9 percent from the previous record high set in July 2015.
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Engineering Mechanics


Engineering mechanics is the study of forces that act on bodies and the resultant motion that those bodies experience. Engineering mechanics subject involves the application of the principles of mechanics to solve real-time engineering problems.
Engineering Mechanics types

Types of Engineering Mechanics:

Engineering mechanics can be broadly classified into two types. They are:

  1. Statics and
  2. Dynamics

1. Statics:

Statics is the branch of mechanics that deals with the study of objects at rest. Objects at rest may or may not be under the influence of forces.

2. Dynamics:

Dynamics is the branch of mechanics that deals with the study of objects in motion and the forces causing such motion.

Dynamics Types:

Dynamics can be further classified into two types. They are:

  1. Kinematics
  2. Kinetics

2.1 Kinematics:
Kinematics is the study of motion of bodies without consideration of the cause of the motion. Kinematics deals with the space-time relationship of the motion of a body. Some examples of kinematic concepts are displacement, velocity and acceleration.

2.2 Kinetics:
Kinetics is the branch of mechanics which deals with the study of motion of bodies by considering the cause of motion.


Open Cycle Gas Turbine Plant

A simple open cycle gas turbine consists of a compressor, combustion chamber and a turbine as shown in the below figure. The compressor takes in ambient fresh air and raises its pressure. Heat is added to the air in the combustion chamber by burning the fuel and raises its temperature.

Simple open cycle gas turbine plant

Simple open cycle gas turbine plant

The heated gases coming out of the combustion chamber are then passed to the turbine where it expands doing mechanical work. Some part of the power developed by the turbine is utilized in driving the compressor and other accessories and remaining is used for power generation. Fresh air enters into the compressor and gases coming out of the turbine are exhausted into the atmosphere, the working medium need to be replaced continuously. This type of cycle is known as open cycle gas turbine plant and is mainly used in majority of gas turbine power plants as it has many inherent advantages.


  1. Warm-up time: Once the turbine is brought up to the rated speed by the starting motor and the fuel is ignited, the gas turbine will be accelerated from cold start to full load without warm-up time.
  2. Low weight and size: The weight in kg per kW developed is less.
  3. Fuels: Almost any hydrocarbon fuel from high-octane gasoline to heavy diesel oils can be used in the combustion chamber.
  4. Open cycle plants occupies less space compared to close cycle plants.
  5. The stipulation of a quick start and take-up of load frequently are the points in favor of open cycle plant when the plant is used as peak load plant.
  6. Component or auxiliary refinements can usually be varied in open cycle gas turbine plant to improve the thermal efficiency and can give the most economical overall cost for the plant load factors and other operating conditions envisaged.
  7. Open cycle gas turbine power plant, except those having an intercooler, does not need cooling water. Therefore, the plant is independent of cooling medium and becomes self-contained.


  1. The part load efficiency of the open cycle gas turbine plant decreases rapidly as the considerable percentage of power developed by the turbine is used for driving the compressor.
  2. The system is sensitive to the component efficiency; particularly that of compressor. The open cycle gas turbine plant is sensitive to changes in the atmospheric air temperature, pressure and humidity.
  3. The open cycle plant has high air rate compared to the closed cycle plants, therefore, it results in increased loss of heat in the exhaust gases and large diameter duct work is needed.
  4. It is essential that the dust should be prevented from entering into the compressor to decrease erosion and depositions on the blades and passages of the compressor and turbine. So damages their profile. The deposition of the carbon and ash content on the turbine blades is not at all desirable as it reduces the overall efficiency of the open cycle gas turbine plant.

Benson Boiler

With use of Benson boiler the main difficulties experienced in the La Mont boiler, the formation and attachment of bubbles on the inner surfaces of the heating tubes of boiler are resolved. The attached bubbles reduce the heat flow and steam generation as it offers higher thermal resistance compared to water film.

Benson Boiler

Benson Boiler

  1. In the year 1922 Benson argued that if the boiler pressure was raised to critical pressure of 225 atmospheres, the steam and water would have the same density and therefore the danger of bubble formation can be high.
  2. Natural circulation boilers require expansion joints but these are not required for Benson as the pipes are welded. The erection of Benson boiler is easier and quicker as all the parts are welded at site and workshop job of tube expansion is altogether avoided.
  3. Benson boiler parts transportation is easy as no drums are required and majority of the parts are carried to the site without pre-assembly.
  4. The Benson boiler can be erected in a comparatively smaller floor area. The space problem does not control the size of Benson boiler used.
  5. The furnace walls of the boiler can be more efficiently protected by using small diameter and close pitched tubes.
  6. In Benson boiler superheater is an integral part of forced circulation system, therefore no special starting arrangement for superheater is needed.
  7. Due to welded joints Benson boiler can be started very quickly.
  8. Benson boiler can be operated most economically by varying the temperature and pressure at partial loads and overloads. The desired temperature can also be maintained constant at any pressure.
  9. Sudden fall of demand creates circulation problems in this boiler due to bubble formation in the natural circulation boiler which never occurs in Benson boiler. This feature of in-sensitiveness to load fluctuations makes this boiler more suitable for grid power station as it has better adaptive capacity to meet sudden load fluctuations.
  10. The blowdown losses in this boiler are hardly 4% of natural circulation boilers of same capacity.
  11. Explosion hazards are not at all severe as it consists of only small diameter tubes and has very little storage capacity compared to drum type of boiler.

During starting of this boiler, the water is made pass through the economizer, evaporator, superheater and back to the feed line through starting valve.

During starting of this boiler, first circulating pumps are made to start and then the burners are made to start to avoid the overheating of evaporator and superheater tubes.