Turbine insulation with removable insulation blankets helps keeping gas and steam turbines operational with high efficiency. Insulation mattresses for turbine insulation are still the most popular form of providing heat shield around the turbine casing. Efficient performance of turbine is necessary for smooth operation of a power plant. Therefore, in this article we will touch on the subject of how to design and carry out turbine insulation, whether it is a gas turbine or a steam turbine.
- 1 What is a turbine?
- 2 What are the leading suppliers of turbines for power plants?
- 3 Turbine Insulation with removable blanket insulation mattresses
- 4 What are the benefits of blanket insulation for a turbine?
- 5 How to design insulation blankets for turbine insulation?
- 6 How to install insulation blankets on a turbine?
What is a turbine?
Turbine is a device that extracts energy from the flow of fluids like gas or steam and coverts it into electricity.
There are various types of turbines like gas, steam, wind, nuclear and hydro.
For the purpose of this article we will focus only on steam turbines and gas turbines at power plants or petrochemical plants.
You can learn more about a steam turbine in the video below:
What are the leading suppliers of turbines for power plants?
There are a few companies with long traditions in the power sector who manufacture gas and steam turbines.
The one which we insulate most often are turbines from:
- Doosan (also Skoda Power)
- General Electric – please check this webinar from GE about steam turbines
- Mitsubishi Power
Turbine Insulation with removable blanket insulation mattresses
Gas and steam turbines are essential for proper functioning of power plants. Whether it’s a gas fired power plant, coal fired, biomass or waste incinerator power plant, all of these facilities use turbines to produce electricity. With large amount of heat there is a risk of heat loss.
Significantly high temperatures can also cause damage to the personnel operating the power plant. That is why turbine insulation is important. In most cases operators choose flexible blankets known also as insulation mattresses for turbines.
What are the benefits of blanket insulation for a turbine?
As we already mentioned above the main advantage of insulating turbine is preventing heat loss.
Temperature inside the turbine casing can reach over 500°C. At such a high level of temperature heat loss can be significant.
Therefore, a multilayer blanket insulation for turbines is an optimum solution. It reduces heat loss from the system which improves overall turbine efficiency.
What is more, thermal insulation blankets fixed tightly on the turbine provide equal temperature distribution. This reduces the risk of stresses development in the turbine casing.
Additionally turbine insulation protects plant personnel against burns and work in high temperatures.
Last but not least there are several benefits of blanket insulation for turbines due to the nature of the material. Main advantage is that insulation blankets can be removed from turbine and reused again.
Even if the insulation blankets reached their end of design life you can remove these safely without the risk of generating too much dust or releasing mineral fibres into the surroundings.
How to design insulation blankets for turbine insulation?
We take several factors into consideration during the design of turbine insulation blankets. Some of the most obvious are requirements for the insulation blanket thickness, type of material, dimensions, weight.
Let us start with the first item on the list – insulation blanket thickness. What do we need in order to design it properly?
To begin with we need to refer to the tender or contract documents. These should describe which method of calculation or which norm or standard we should use for thickness assessment. Usually project specification contains these details.
In the absence of such information we ask the customer to give us at least the following details:
- Design and operating temperature
- Wind velocity (even for internal applications we usually consider at least some draught, like 1m/s)
- Surface temperature of the insulation blanket
- Heat loss value (for example, some customers require maximum heat loss of 250W/m2 – approximately 80 BTU/sq.ft/h)
- Humidity level
- Ambient temperature
Very often customer already have some insulation design which shows thickness of blanket insulation. Nevertheless, it’s worth to verify it. Sometimes we can suggest more economical solution. In other cases, thickness of blanket insulation is insufficient and we need to redesign.
Digital and on site surveys during the turbine insulation design
When it comes to designing insulation blankets for a new turbine the process is streamlined with the use of 3D models and CAD software. We usually receive detailed models of turbines and these allow us for precise take-offs of quantities.
In case of a retrofit or turbine replacement or renovation works when the client doesn’t have CAD model we carry out site survey. Such a task includes detailed measurements of turbine and associated equipment.
Of course the 3D model does not always show an entire arrangement of piping and equipment around the turbine in its final location. In such cases we discuss it with the customer whether there will be any item that may clash with turbine insulation blankets.
If there is a clash we can design thinner insulation blanket in such spot. Inside of the blanket we fill with a material of higher insulating properties. Such materials are usually more expensive, however, thermal properties of insulation blanket are according to the requirements and without hot spots. You can read more about how Pyrogel insulation performs with gas turbine insulation in this article.
Since turbine heats up to over 500°C we need to allow for thermal expansion of the turbine and expansion within the insulation layers.
We always aim to prepare as many turbine insulation blankets as possible in our factory. This means that the client requires only minor changes or on-site made items.
Fixings and production of turbine insulation blankets
Another important factor which we take into consideration if fixing of insulation blanket on a turbine casing. Most turbines have already welded holding pins. These pins are placed in specified locations. Sometimes there are just lugs available into which you can weld holding pins. In other situations these might be threaded holes where you can screw the holding pin in.
Designers need to calculate the correct quantity of pins to provide sufficient support for the multi-layer insulation blankets.
Once we have all the details we can prepare shop drawings which we hand over to the factory supervisor. Our CNC insulation cutting machine operator downloads the drawings. This way she can instruct the cutting machine to cut the cover material for the insulation blanket in a very precise way. Another benefit of such a method is that there is very little material waste due to the nesting functions of CAD software.
How to install insulation blankets on a turbine?
We prefer to design at least two layers of insulation, for example 2x150mm layers. We aim to make individual blankets under 25kg. If the client asks us we supervise the installation works to make sure all parts go into their correct positon. This process is usually not so difficult since we mark all the parts.
Installation team can also receive a drawing showing position plan with all items.
In a multilayer system operatives always need to make sure the joints are staggered The minimum overlap is usually described in the specification. But sometimes it’s just a rule of thumb that the offset is equal to half of the width of insulation blanket.
You need to install insulation blankets tightly so there are no air gaps in between them. These air pockets can accumulate heat and cause sudden bursts of heat.
If there are any holes or gaps after installation you should fill them in with a loose insulation material or a site measured blanket.
Some areas of the turbine require more frequent maintenance like valves, flanges, inlets, or instruments. We make sure that these areas have smaller blankets that you can remove easily.
There might be also areas that exposed to higher mechanical load, like walkable surface. In such places you might install a thicker layer of walkable plates with suitable substructure.
We supported our customers with retrofitting turbine insulation and supplying new insulation blankets for turbines.
Do you have a current turbine insulation project?
Let us support you with insulation blankets or any other of our removable insulation products.