Project number 6 :Select the materials and manufacturing route for fabricating blades for turbine used in electricity generation

GROUP 4

a1659176 - Tejaswi Lavetia1671815 - Sandeep Bommaka1651544 - Rishinath Venugopala1641638 - Vignesh Ganapathy Subbiah

FUNCTION OF THE PROJECT

Selecting the appropriate materials and manufacturing methods for turbine blades used in energy generation.

Selection of the materials which satisfy the required melting points, Yield Strength ,Young's modulus, density, resistance to fatigue, creep, corrosion, erosion and considering the costs.

Selecting the best method for fabricating the selected materials

FUNCTION OF THE COMPONENT

The topic focuses on a Geothermal Steam Turbine which can generate 30 MW

The primary component of any turbine are the blades. All the kinetic energy from the steam is forced onto the blades at high temperatures ,pressures and velocities.

The blades are always the limiting component of an electricity generation unit. Simply, the entire power production can come to a hold with a failure of a single blade.

The blades experience a number of stresses due to the rotational forces installed by the fluid velocities and can rotate up to 10,000 RPM

Typical Inlet and Outlet Pressures and Temperatures for a low pressure steam turbine with a rated power of 30 MW

TEMPERATURE °C PRESSURE MPa

INLET 130 0.3

OUTLET 30 0.03

The centrifugal force acting on the blade can be found based on Newton’s 2nd law

Stress = Force/ Area where,

Force = M Rω^2 M, mass of the blade

R, Radius of the blade , angular velocity A, cross sectional are of blade We estimate the stress value about 500 MPa and may change upon the type of system

CONSTRAINTSThe constraints for the project have been categorised as follows

Non – Negotiable Negotiable Desirable

Constraint Ranking

Temperature Non-negotiable

Pressure Non-Negotiable

Corrosion Non-Negotiable

Erosion Non-Negotiable

Fatigue Non-Negotiable

Creep Non-Negotiable

Stress Non-Negotiable

Non Negotiable constraints

Constraint Ranking

Shape of the blade Negotiable

Length of the blade Negotiable

Manufacturability Negotiable

Efficiency Negotiable

Maintenance Negotiable

Negotiable Constraints

Desirable Constraints

Constraint Ranking

Cost Desirable

Availability of Material Desirable

Time span Desirable

Design Objectives

Nominal Preservation to the low pressure turbines blades is vital for this component. This ensures minimal downtime for the low pressure turbine blade.

This can be achieved by optimising the design constraints.

Design Objectives The low pressure turbine blades does not fail under any of these

design constraints shown in table below:-

- Non-negotiable constraints

Constraint Objective

Corrosion Highly Resistant

Erosion Highly Resistant

Temperature Melting point beyond 325°C

Pressure Be able to withstand 0.3MPa

Stress Strength of atleast 500MPa

Design Objectives

Cost of the Materials includes:-

Transportation cost.

Manufacturing cost.

Labour and energy used.

Design Objectives

Mass of the Blade:-

By minimising the material mass of low pressure turbine will meet the design objectives by reducing the cost of each blade.

Thus the weight of low pressure turbine blade depends upon the length and its size.

Design Variables and Material Selection

The variables are designed to meet the objectives.

Material Selection:-

Selection of materials can be list out from the charts shown below.:-

Maximum service temperature chart:-

Materials Selection Based on Research

From the charts, we get to know the most desirable materials includes:-

Steels

Alloys

These two materials are likely to meet the objectives:-

Stainless steel:-

- Used due to high fracture ,toughness, desirable cost and low reactivity to corrosion.

- And also has high mechanical properties can withstand large stress, resist creep and fatigue due to continuous use of turbine.

Titanium alloy:-

- Ti-6aAl-4V( Composition includes of 6% of Aluminium,4% of Vanadium and remaining 90% of titanium.

- Usage of material improves the low pressure turbine efficiency.

- Properties includes:- Strength,corrosion resistance,weld and fabricability.

Appearance of blades

Manufacturing methods*Types of manufacturing

-Primary shaping process

-Secondary machining process

Primary shaping process:-

*Closed die forging-billet of steel heated in furnace and then shaped under high pressure in a die

*Investment casting-a wax model is created and heated and the required molten material is poured in to the model to get desired shape.

*Milling-machining of bldae directly form bar stock.

Secondary machining methods:-

*Final milling-usage of 5 axis milling machine to shape the internal shape of the blade.

*Coating technology-usage of high-velocity oxygen-fuel thermal spray coating.

*Shot peening technology- bombards the high-stress areas of the blade and rotor with steel balls at high speed

*Hardening-steam superheated for the inlet of the turbine to withstand corrosion at high degree hardening is used

*Balancing- positioning of blades within rotor plate and checking under dynamic condition.

*Final inspection-Ensuring presence of no Microscopic defects under fluorescent dye.

Energy consumption and Environmental

impactFactors to be taken into consideration for efficient form of energy consumption for manufacturing are as follows

*Blade design

*Materials production – mining and refining of the metal alloys

*Transportation of the base materials to the blade manufacturer

*Blade manufacture, which for Low Pressure Steam Turbine Blades would include forging and machining

*Manufacture, maintenance and replacement of manufacturing equipment and tools.

*Transportation of blades to turbine manufacturer

*Energy consumption during its use, which needs to be offset by the energy generated by the blade

*End of Life disposal and recyclability

Emission of Harmful gases:-

*The consumption of energy produces CO2, NOx, sulphur compounds, dust and waste heat.

*Recycling of waste heat where possible for other business purposes assist in reduction of business costs.

* For example, for electricity generators within Australia, a reduction in carbon emissions will have direct benefits through a reduction in the amount of carbon tax payable by the plant operator on carbon emissions (which is currently set at $23 per tonne).

CostDirect Manufacturing cost

*Material cost:-the raw material cost which incurs during the machining process

Material Cost Category

Gelcoat

Continuous Strand mat

Double-Bias E-Glass Fabric

Unidirectional E-Glass Fabric

Core

Resin

Promotor

Catalyst

Bonding Adhesive

Root Attachment System

*Labor Cost:-The cost of labor involved while performing the following operations

Material

High Pressure Skin

Leading Edge Shear Web

Low Pressure Skin

Trailing Edge Shear Web

Assembly Prep

Bonding

Root Attachment System

Finishing

Inspection

Testing

Shipping

Indirect Manufacturing methods

*Over head cost:-These costs include management oversight, sales and marketing, after-sales customer support, warranty repairs, insurance, and other miscellaneous costs associated with running a manufacturing business.

*Development cost:-The cost associated with the fabrication of tooling and prototypes was estimated by assuming the cost to be dependent upon the blade scale, as is the cost of static, fatigue, and operational field testing

*Facilities cost:-The annual blade production capacity and the plant conceptual design were used to develop tooling, equipment, and facilities cost estimates.