Gas Turbine Bleed Heating System

Gas turbine operating range may be restricted for cold compressor inlet temperatures in order to protect the gas turbine compressor from exceeding its operating limit and/or inlet ice buildup. Gas turbines that operate with the inlet guide vanes at restricted angles at low ambient temperatures are prone to inlet ice formation and reduced compressor operating limit. With such designs, inlet heating becomes necessary to guarantee full gas turbine operating range.

The Compressor Bleed Inlet Heating system recirculates a fraction of the hot compressor discharge airflow into the inlet to prevent condensate ice formation and to prevent exceeding the compressor operating limit.


Description of the System

1-System component
a. One thermocouple (CT_BD-1) mounted in the bleed heat piping upstream of the distribution manifold to indicate bleed flow.

b. Drain valve motor operator (90 TH-4) opens drain valve VA 30-1 which is used to blow down any collected condensate in the bleed heating piping system. This is monitored by 33 TH-4 limit switch.

c. Upstream isolation valve (VM 15-1) used to provide shutoff capability against compressor discharge air pressure for disabling the bleed heat piping system.

d. Control valve assembly (VA 20-1) regulates compressor discharge airflow by measuring upstream and downstream pressure with 96 BH-1,-2, and calculating air flow. The following components are mouted on the control valve.



2-Operation
The percentage of compressor bleed to be recirculate to the compressor inlet is determined in the SPEEDTRONIC sofware. This percentage is transformed into a required valve position command which is converted to a 4-20 mA signal that is used to drive the valve positioner 65 EP-3A 4-20 mA valve position feedback signal provided by the position transmitter 96 TH-1 is used in the control sofware for fault detection. If the difference between the command position and the feedback position signals is greater than a set limit for a certain period of time, a bleed heat control valve fault alarm will be annunciated. If this condition persists for an extented period of time, the SPEEDTRONIC will disable the compressor bleed inlet heating system and take action to restrict the gas turbine operating region within a set of safe limits.

Similar fault detection is applied to the thermocouple signals imputed to the SPEEDTRONIC. The compressor bleed inlet heating sofware must detect a rise in the ambient temperature thermocouple signal (CT_BD-1). If this temperature rise is not detected an alarm will sound and the system will be disabled.

 
Bleed Heating System

1 comment:

  1. Aladdin Plumbing & Mechanical will provide a free heating installation quote to ensure our services suit both your home specifications and your budget. Heating System

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