Reconstruction of turbine PT-135/165-130/15 (replacement of Low Pressure Rotor and sealings)

CND (low pressure section) in turbine PT-135/165-130/15 consists of three stages with height of rotating blades of last stage 830 mm. During operation in cogeneration modes the considerable losses of capacities for friction and ventilation occur. To cool the stages of low pressure section and to keep the temperature of exhaust not over 80^оС the steam flow rate through the above-mentioned stage should be not less than 30 t/h.

Availability of such a big ventilation flow rate reduces the cost - efficiency of turbine operation in district heating modes, as the heat of this steam is transferred to circulation water and is lost irreclaimably.

In 2005 during middle repair of steam turbine PT-135/165-130/15 st.#6 at Kazan cogeneration plant #3 according to project of JSC "Teploenergoservis-EK" the low pressure rotor was reconstructed by transfer from three-stage one with height of last stage 830 mm to two-stage one with height of last stage 660 mm.

Rotor low pressure section with three and two stages on condensation mode with pressure of steam in condenser 0.11 kgs/cm² are equally saving, during further increase of pressure in condenser, the blades of height 660 mm provide the operation of low pressure section with higher efficiency.

Economical effect from the action "Reconstruction of turbine PT-135-130 (with replacement of Low Pressure Rotor and sealings)" is reached from reduction of ventilation flow rate of steam in condenser from 30 to 15 t/h during district heating modes. Thus the losses of capacities for friction and ventilation reduce in stages of low pressure section by 1 МW and the heat output from district heating extractions increases by 8 Gcal/h.

Besides during the mid repair reconstruction was done of the wingtip sealings of Low Pressure Rotor with transfer to the cell ones, this allowed to reach the normative value of air sticking of 18 kg/h in the turbine vacuum system. According to preliminary estimates the reconstruction would allow to reach saving of fuel in the amount of 1,400 tons of reference fuel per year.

In 2006 the same reconstruction was done at turbine PT-135/165-130/15 st.#2 PTK-2 of Nizhnekamsk CHPP.