Turbine Water Induction Protection Systems Cost … · blade damage resulted in full last stage...
2
Services: Trouble Shooting Failure Analysis Turbine and Generator Health Assessment Capital and Maintenance Optimization Outage Cycle Optimization Turbine Generator Design Reviews Torsional Vibration Testing & Analysis Plant Heat Rate Assessments Bid Specifications and Reviews Shop Surveillance Services Ask an Expert Support Expert Witness Testimony Education and Training WWW.TGADVISERS.COM 4550 New Linden Hill Road Suite 152 Wilmington, DE 19808 (302) 691-3330 – Phone (302) 691-3336 – Fax [email protected] – E-mail Background TG Advisers, Turbine and Generator experts who provide engineering services to the power industry. Our mission is to be recognized as a valued leader of independent equipment assessments, expert 3rd party design reviews, and O&M solutions and services. FEBRUARY 2013 Dan Skedzielewski, Senior Consultant, TG Advisers, Inc. James Kugler, PE. Senior Consultant, TG Advisers, Inc. The accidental introduction of water in any part of a steam turbine can cause serious damage requiring extended outages to make costly repairs. A proliferation of such incidents in the electric power generation industry prompted the American Society of Mechanical Engineers (ASME) Standards Committee to develop a uniform set of design criteria to alleviate the problem. With the recent update of ASME Turbine Water Induction Protection (TWIP) standards and the continued focus on fossil plant reliability, TWIP system upgrades have gained increased focus as capital improvement projects in the Industry. TG Advisers has identified many clients that have experienced major water induction turbine outages, resulting in millions of dollars of damage. In the extreme case, full blade replacements and rotor straightening technologies have been employed to return the unit to service. Forced outage durations can extend to 6 months or greater. The following photo was taken after an LP heater level control failure on a 1960s’s vintage General Electric LP rotor design. Extensive LP blade damage resulted in full last stage blade replacements. Turbine Water Induction Protection Systems Cost Effective Insurance Against Major Forced Outages This publication’s purpose is to inform our clients of key industry findings and introduce ways to manage risks. NEWSLETTER
Transcript of Turbine Water Induction Protection Systems Cost … · blade damage resulted in full last stage...
Services:
Trouble Shooting
Failure Analysis
Turbine and Generator Health Assessment
Capital and Maintenance
Optimization
Outage Cycle Optimization
Turbine Generator Design Reviews
Torsional Vibration Testing & Analysis
Plant Heat Rate Assessments
Bid Specifications and Reviews
Shop Surveillance Services
Ask an Expert Support
Expert Witness Testimony
Education and Training
www.tgadvisers.com
4550 New Linden Hill RoadSuite 152
Wilmington, DE 19808(302) 691-3330 – Phone
(302) 691-3336 – [email protected] – E-mail
Background
TG Advisers, Turbine and Generator experts who provide engineering services to the power industry. Our mission is to be recognized as a valued leader of independent equipment assessments, expert 3rd party design reviews, and O&M solutions and services.
FEBRUARY 2013
Dan Skedzielewski, Senior Consultant, TG Advisers, Inc.James Kugler, PE. Senior Consultant, TG Advisers, Inc.
The accidental introduction of water in any part of a steam turbine can cause serious damage requiring extended outages to make costly repairs. A proliferation of such incidents in the electric power generation industry prompted the American Society of Mechanical Engineers (ASME) Standards Committee to develop a uniform set of design criteria to alleviate the problem. With the recent update of ASME Turbine Water Induction Protection (TWIP) standards and the continued focus on fossil plant reliability, TWIP system upgrades have gained increased focus as capital
improvement projects in the Industry. TG Advisers has identified many clients that have experienced major water induction turbine outages, resulting in millions of dollars of damage. In the extreme case, full blade replacements and rotor straightening technologies have been employed to return the unit to service. Forced outage durations can extend to 6 months or greater. The following photo was taken after an LP heater level control failure on a 1960s’s vintage General Electric LP rotor design. Extensive LP blade damage resulted in full last stage blade replacements.
Turbine Water Induction Protection Systems Cost Effective Insurance Against Major Forced Outages
This publication’s
purpose is to inform
our clients of key
industry findings and
introduce ways to
manage risks.
NEWSLETTER
Causses of Water Induction There are many sources of water induction in a steam turbine. The following is a list of the most common sources that are addressed in the ASME TDP-1 standard:
Motive steam systems1.
Steam attemperation systems2.
Turbine extraction/admission 3. systems
Feedwater heaters4.
Turbine drain systems5.
Turbine steam seal systems6.
Start-up systems7.
Condenser steam and water 8. dumps (steam bypass)
Steam generator sources9.
Generating units that were designed and built prior to the development of the design criteria are consequently at risk.
To properly assess the status of steam cycle piping systems with regard to the current design criteria, a Steam Turbine Water Induction Protection Unit Checklist is used. Input for the program can be completed by plant and engineering personnel that are familiar with the plants configuration. The analysis then compares plant equipment to the ASME standards and identifies where additional protection schemes are required.
For example, typical shortfalls that have been identified on vintage steam turbine generator feedwater system include the following:
Upgraded level transmitters • and associated modifications of the digital control system to include inputs and new alarm outputs.
Installation of alternate • feedwater heater drains to the condenser with a power operated block valves. Normally feedwater heater systems are equipped only with the normal cascading drain lines to the next lower pressure heater. Alternate drain lines in many cases are required to meet ASME code requirements.
In more severe water induction incidents, turbine rotors have been permanently bowed. Repairs in these cases could be as extreme as full rotor replacement or a combination of weld repair or heat treatment of the bow location in the rotor.
Installation of extraction • steam line power operated block valves. Most units have power assisted non-return valves installed in the steam extraction lines; however these valves are not leak tight and were originally installed for overspeed protection, not water induction protection.
textt
ext
T
Add power operated isolation valve
T
From Steam Turbine Extraction Steam to FWH
Extraction Steam to FWH
Existing Power Assisted Non-Return Valve
Low Pressure FWH in Condenser Neck
New power-operated bypass block valve replaces manual bypass valve
New power-operated condensate outlet block valves replaces manual block valves
Upgrading turbine water induction systems can be a very cost effective way of ensuring long term reliability not just with older conventional units but also combined cycle plants which have been recognized in the new ASME TDP-1 standard, such as units with axial exhaust LP turbine and condenser configurations.
Installation of feedwater block and bypass power operated valves • where extraction steam line power operated block valves are not practical. Many low pressure feedwater heaters were equipped only with manual block and bypass valves.
