Design defect led to break down of Chinese make unit at Yamuna Nagar thermal
Vinod Kumar Gupta, 21-Mar-2012

Design defect led to break down of Chinese make unit at Yamuna Nagar thermal

Wednesday March 21, 2012

Chandigarh

The break down leading to forced closure of 300 MW Chinese make unit installed by Reliance at Yamuna Nagar thermal plant is result of design defect.

Haryana Power Generation Corporation Ltd. (HPGCL) is incurring an expenditure of more than 3 crore on the repair of turbine rotor besides suffering a daily generation loss of 72 lakh units worth Rest. 2 crore. This information has been obtained under RTI from HPGCL.

The 5 member committee formed by HPGCL to find the reasons for forced closure of unit has blamed the defective design for forced outage of unit .It may be mentioned that the due to high eccentricity and vibration at turbine bearing no. 1 led to forced closure of unit on September 25 last year. It was found that wet steam / water had entered the turbine.

As per RTI information the committee discussed the matter with BHEL turbine experts, Chinese engineers and local engineers to find out how the water entered the turbine and imbalancing of rotor took place.

As per committee report water induction in turbine was possible through three paths only but that did not happen in the present case. Thus water/ wet steam entered in to HP turbine mainly through some other source. Moreover there was no provision in unit control panel to detect water ingress in the turbine

The committee was of view that most probable path for ingress of water to HP turbine was back flow through low pressure drains connected to HP turbine. The reason for back flow was connection of low pressure drains and high pressure drains on common manifold and pressurization of flash box.

It was found that as per design of 300 MW unit at Yamunanagar high pressure drains are connected to same header to which five low pressure drains of HPT inlet pipes and first stage casing are connected. BHEL turbine experts disagreed with the above design provisions of Chinese company .Even the same company Shanghai Electric Companies provided separate headers at 600 ME Khedar thermal plant.

The work order for rotor straightening including balancing of rotor of unit 2 of Yamuna Nagar Thermal was placed on 24 January on Siemens for 399597 euro i.e. 2.717 crore excluding transportation ,insurance and supervision charges. The service tax @ 10.3 % (around 28 lac) shall be extra. The proposal was approved by Chief Minister Haryana on January 23. The tentative duration of work is 20 weeks. The rotor was transported by HPGCL to the Vadodra works of Siemens on February 8.

As per RTI information Himanshu Gupta Executive Engineer was suspended on October 7 last and no charge sheet has been served till date. He is yet to be reinstated.