THERMAL POWER PLANT

There are many goals and objectives in the Professional Experience programs and the important goals that the students get a chance to apply their academic skills on a practical setting. Also, they can improve their chances to finding a better job after they graduate.

The main objectives of this post is as mentioned below 

1. To work in the real world to improve the academic skills which got from university
2. To learn how to be an active employee of a company.
3. To increase the meaning and purpose of student studies.

My friend had an opportunity to work in a well known company that the Saudi Electric Company (SECO) that was responsible about my friend training. I am producing this post just for sharing the knowledge and skills that i have secured from my friend experience. I have learnt various key information about the power engineering.

Let us come to the point to understand various technical terms of thermal power plant 

Thermal power plant 

In thermal power stations, mechanical power is produced by a heat engine, which transforms thermal energy, often from combustion of a fuel, into rotational energy. Most thermal power stations produce steam, and these are sometimes called steam power stations. 

About 86% of all electric power is generated by use of steam turbines. Not all thermal energy can be transformed to mechanical power, according to the second law of thermodynamics. Therefore, there is always heat lost to the environment. If this loss is employed as useful heat, for industrial processes or district heating, the power plant is referred to as a cogeneration power plant or CHP (combined heat-and-power) plant.

Qurayyah Power Plant 

Qurayyah Power Plant is one of the largest power Generation units. The department operates and maintains 4 X 625 MW steam power generation unites to supply high quality electricity to its customers. The main milestones leading to commercial operation are listed below.

UNIT 4	UNIT 3	UNIT 2	UNIT 1	EVENT
Jun 23, 1990	Jan 02, 1990	May 1987	Oct 1986	Start Erection
Jan 14, 1992	Jan 04, 1991	July 20, 1988	--	Power Receiving
May 20, 1992	Oct 08, 1991	Nov 26,1988	May 02, 1988	First Firing
Jul 26, 1992	Feb 19, 1992	Feb 28, 1989	Oct 08, 1988	First Steam to Turbine
Aug 04, 1992	Mar 02, 1992	Mar 28, 1989	Oct 30, 1988	First On-line
Aug 22, 1992	Apr 11, 1992	Jun 27, 1989	Jan 04, 1989	First Full Load
Nov 17, 1992	Aug 13, 1992	Jun 27, 1989	Mar 28, 1989	Commercial Operation

Qurayyah power plant 

Department divides into three divisions: Technical and Support Division, Operation Division and Maintenance Division.

Technical and Support Division: - Responsibilities

1- Material Unit: To supply unfounded material such as, bearings, gasket ...etc.

2- Planning Unit: To arrange the appointment of maintenance.

3- Engineering unit: To solve the Critical problems.

Operation Division: - Responsibilities

1- Manipulating with the lode of the unit depends of the disparate demand.

2- Observing Process and performance of equipments

3- Isolate or operate any equipment.

All of these work done by a latest microprocessor technologist called DCIS.

Maintenance Division: - Responsibilities

1-    Routine inspection

2-    Corrective maintenance

3-    Preventive maintenance

4-    Breakdown maintenance

5-    Spare & maintenance planning

According of the type of work, Maintenance Division can be dividing into four sections

1-    Mechanical Maintenance.

2-    Workshop Maintenance.

3-    Electrical Maintenance.

4-    Instrument Maintenance.

Steam power plant Cycle 

All steam power plant works on the principle of Rankine cycle  

In Qurayyah Power Plant the same Rankine cycle is applied but with one step more i.e. Reheat step.

Rankin Cycle

Qurayyah power plant cycle

We will consider all major part on it.

                                                 Qurayyah Power Plant Cycle

Main Boiler

There are four Mitsubishi steam generations to drive each of the four turbines at Qurayyah. The boiler is Radiant, Reheat, Controlled Circulation, Tangential Tilting Corner fired type. Steam is generated at 173 bar, 541 C at the super heater and at 41.1 bar, 541 C at the re-heater.

QPP Boiler is controlled circulation, positive draft, radiant reheat, hanger, divided furnace type. It differs than the natural circulation Boiler due to tow characteristic.

                                                                 Main Boiler

                                                          Boiler Drawing

Boiler maximum rated output is 2080 ton/hour at 541°C at the super heater outlet, and 1745 ton/hour steam flow at 541°C steam temperature at the Reheater outlet. The steam pressure is 173 bars at super heater outlet. QPP Boiler can burn oil or gas individually or combination.

                                                        Boiler Hunger

Main components of boiler are Economizer, Steam Drum, and Furnace.

Economizer

To preheat the feed water before it enters the steam drum. Feed water is preheated by using heat recovered from the flue gas leaving the Boiler. This preheating increase overall unit efficiency.

                                                             Economizer

Steam Drum

To supply feed water to the seam generation circuit and steam to the super heated, The Steam Drum contains moisture separation equipment to remove moisture.

Water wall Tubes

To absorb the heat produced by the combustion of fuel in the furnace, and transfer this heat to boil the feed water and produce steam.

                                                            Waterwall Tubes

                        A Cross Section of the Boiler with its Main Components

Main Turbine

There are four Mitsubishi steam turbines at Qurayyah, driven by steam from its own boiler unit. The turbine is Reheat, Regenerate, Condensing. 4-casing Quadruple Flow type, Steam is supplied on the turbine inlet is at 166 bar and 538C. The reheat inlet condition are 38 bar and 538 degree centigrade.There are 8 Regenerative Feed Water (FW) Heaters: FW Heater 1, 2, 3, 4, 6, 7& 8. Dearator is considered as FW Heater No. 5. HP/LP Bypass system is also provided.

Cross Section of a Turbine

Inside Turbine

Main Condenser

Condenser transfers the heat of the vaporization from the turbine exhaust steam to circulating water system. The condenser hot well acts as a collection point for the condensate water. The circulating water removes the waste heat that must be rejected in the main condenser as part of the steam turbine cycle.

LP Heaters

In the first stage of returning the condensate to the boiler, condensate pumps remove the condensate from the condenser hot well and pump it through a series of LP heaters. These are arranged in stages to heat the condensate progressively.

Deaerator

To avoid oxygen corrosion of the internal surfaces of the boilers, especially at higher pressures, it is necessary to deaerate the boiler feed water so that its oxygen content does not exceed 0.005 mg/l.

HP Heaters

Boiler feed pumps take the feed water from the deaerator storage tank and pumps it through a series of HP heaters. The principle of operation of these heaters is similar to that of the LP heaters.

                                                  HP Feed water heater No.6

Intake Area & Water Treatment Plant

Seawater enters the Qurayyah power plant Intake through underwater pipes to each pump (4 pumps for each unit). The incoming water flows through bar screen where large debris is filtered and prevented from entering the system.

Desalination Plant

There are three Desalination Plant Multi Stage Flash type units meeting the water needs of QPP & Each unit has capacity of 4000 tons/day.

Each of the desalination units produce 4000 cubic meters of distilled water/day. The desalination units use multi-stage flash (MSF) evaporation process to transform sea water into distilled water.

 There are seven major flow circuits in each desalination unit:

• Makeup Water

• Brine Re-circulation

• Seawater Re-circulation

• Sea water to Drain

• Distillate Circuit

• Condensate Circuit

Major Components

Also, the major components in each plant are:

Distiller Sea Water Pump

To supply sea water to the Desalination Plant to be used as a cooling medium and as feed water to the evaporator

Decarbonator

To remove non-condensable gases, mainly dissolved carbon dioxide gas from the makeup sea water.

                                                    Decarbonator

Deaerator

To remove air and other non- condense-able gases from the makeup sea water, before entering the evaporator.

                                                           Deaerator

Brine heater

To heat the re-circulated brine exiting the first stage condenser to 110°C 

                                                           Brine Heater

Evaporator

To produce distilled water from sea water by using the multi-stage flash evaporation process.

                                                          Evaporator 

Electricity Generation

Electricity generation based on the basic principle that a potential difference, or voltage, will be established between the ends of an electrical conductor if it is subjected to a moving magnetic field & Spinning a series of large electromagnets inside a fixed, tightly wound coil of wire will therefore produce electricity & this electricity will be in the form of alternating current (AC), which is collected and drawn off at the terminals of the generator. 

                               Electricity Generation in the end of turbine

Electricity Transmission

The Qurayyah transmission system consists of overhead lines, transformers that step up the voltage to the transmission voltage, and switchgear for controlling the lines and transformers.

Fuel System

Natural gas supplied by Saudi Aramco is the primary fuel, with crude oil being used as a backup source. Each generation unit consumes approximately 176,000 m3/hr gas or 24,000 barrels of crude oil at a load of 625 MW.

Fuel Tank 

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