THE STEAM TURBINE

There are three (3) important things that should be known by an operator to operate the power plant or the Power House.

                   1. SAFETY:

                 a. Security for the people (person). In this case to avoid the things that   can cause an accident.

                  b. Security for equipment (equipment) prevent damage to the equipment with respect to the implementation of the operation as recommended by manufacturer (Manual Book) as well as good maintenance.

2. RELIABILITY / reliability of the unit by way of maintaining continuity of operations.

Avoid the trip unit by mistake and shut down operations due to equipment malfunction. In this case of course, supported by good maintenance.

3. Effeciency:

Carry out operations in order to achieve a high EFF by following operating instructions as recommended by manufacturer.

Before we discuss further steam turbine, it is good we need to know:

2. Power House = use his own power plant →

                                          ↓

                                    - Factory

                                    - Offices

                                    - Housing

                                    - Schools

                                    - Mosques and Churches

                                    - etc

Steam Turbines: is a first mover that converts the steam into potential energy kinetic energy. Further kinetic energy converted into mechanical energy in the form of the turbine shaft rotation

 CLASSIFICATION OF STEAM TURBINE

Steam turbines can be classified into categories berbedatergantung in construction, heat reduction process, the conditions of the beginning and end as well as its use in industrial steam as follows:

1. According Total Pressure Level:

a. Turbine Atua one level with one more level of speed that is usually a small capacity. The turbine is mostly used to drive centrifugal compressors and similar machines.

Example: Turbine DE-LAVAL (Fig. 1)

b. Impulse turbine with a single pressure level and the level of velocity (speed) double (compound). The system is applied to a single rotor turbine with curtis. (Fig.2)

c. Impulse turbine with multiple pressure levels and the rate is applied to the system velocity Rateau turbine. (Figure 3)

d. Impulse turbine with multiple velocity levels of stiffness with this system applied to the dual rotor turbine Curtis (Figure.4)

e. Turbine system using a combination of Curtis-Rateau (Fig.5)

f. Reaction turbine with multiple levels and a level of velocity. The system is applied to the turbine Parson (Figure. 6)

g. Impulse turbine combination - reaction. This system is applied in combination Curtis-Parson (Figure.7)

h. Reaction turbine with a rotor and a double round. The system is applied to the turbine Ljungstrom (Fig. 8)

Figure 1. Turbine Impulse Pressure Level and Velocity Single

 

Figure 2. Turbine Impulse Pressure Levels With Velocity Single and Dual Rate (Compound)

  

Figure 3. Turbine Impulse Pressure Level One Double and Velocity

  

 

Figure 4. Turbine Impulse Pressure Level and A Level Dual Velocity

 

Figure 5. Turbine Combination

 

Figure 6. Reaction Turbine With Pressure Level Double and One Velocity level

Figure 7. The combination of impulse turbines - Reaction

  

Figure 8. Reaction Turbine With Rotor and Round Doubles

2. According to the Steam Flow Direction:

a. Axial turbine, the steam is flowing in a direction parallel to the axis of the turbine.

b. Radial turbine, the steam is flowing in a direction perpendicular to the axis of the turbine.

3. By Number of Cylinders:

a. Turbine Single Cylinder

b. Turbine Double Cylinder

c. Three turbines slinder

d. Turbine Four Cylinder

4. According Methode settings:

a. Turbine with strangulation settings (throttling) the fresh steam entering through one or more (depending on power generated) strangler valve operated simultaneously.

b. Turbine with a steam nozzle arrangement fresh go through two or more regulators opener (Opening regulators) are sequential.

c. Turbine with setting step (by-pass governing) that besides the fresh steam supplied to the first level also directly channeled to one, two or even three mid-level turbine.

5. According to Steam Action Principle:

a. Impulse Turbine, its potential energy converted to kinetic energy in the nozzle or the passage formed by the stationary blades (blade guide) adjacent and in the motion blades (blade movie) kinetic energy is converted into mechanical energy.

b. Reaction turbine steam expansion axial blade passes between both blade guides and blade motion. Each level takes place almost at the same rate.

c. Radial reaction turbine without blades steering silent.

d. Radial reaction turbine with blade guides that are silent.

6. According Process Heat reduction:

a. Condensing turbine (condensing turbine) to the regenerator, in this type of steam turbine at a pressure lower than atmospheric pressure is applied to the condenser, the vapor also dicerat addition of medium levels of filler kettle to heat water, the amount of penceratan usually 2 to 3 to 8 - 9.

Latent heat of exhaust steam condensation during the turbine's all gone.

b. Condensing turbine with one or two penceratan of the medium at pressure levels for industrial purposes and heating.

c. Pressure turbine opponents (Back Pressure Turbine) exhaust steam is used for heating and industrial purposes.

d. Overlap turbine, the turbine is also opposed to the type of turbine pressure difference that is still used for the exhaust steam turbines condensing medium and low pressure.

e. Pressure turbine opponents (Back Pressure Turbine) with penceratan steam from medium levels at a particular pressure, in order to supply steam to consumers at various pressure and temperature conditions.

f. Low pressure turbine (pressure Discard) exhaust steam from steam engines used for power generation purposes.

g. Pressure turbine mixed with two or three levels of pressure with exhaust steam supply to the medium levels.

7. According to Steam Conditions Log In Position:

a. Low pressure turbine (Low Pressure Turbine) pressure (1.2-2.0) atm.

b. Intermediate pressure turbine (Middle Pressure) pressure (2-40) atm.

c. High-pressure turbine, the vapor pressure (40-170) atm.

d. Very high pressure turbine, the steam pressure (170-225) atm.

e. Super critical pressure turbine, the vapor pressure exceeds 225 atm.

8. According pemekaiannya industry:

a. Stationary turbine with a constant rotational momentum is mainly used to drive the alternator.

b. Stationary steam turbine varies with the rapidity which is used to drive the blower, turbo, air dealers (Air Circulator), pumps etc..

c. Turbine is not stationary with varying rapidity, turbines of this type usually used steamers, ships, railroad locomotives (Locomotive turbo)

All types of turbines that have been described above are dependent on the rapidity turn can be connected directly or through a reduction gear with engine-driven machine.

 STEAM TURBINE in use

Many industries use steam for industrial purposes except for process heat, or mechanical energy is also power to run the plane. Because of the special nature of the heat release time, the heat exchanger to heat during the process handover to the medium to be heated. Mechanical power of steam addition can be useful if the process temperature and high vapor pressure, further expands in the turbine pressure allowed an opponent to the required pressure.

Turbine Industry Divided Over Five Group:

1. Pressure turbine opponents (Back Pressure Turbine)

2. Condensing turbine (Condensing Turbine)

3. Extraction turbine / drain (Extraction Turbines)

4. Turbine combination (Mixing Turbines)

5. Turbine waveguide.

ad.1. Pressure Turbine Opponent:

pressure turbine opponents used when an industry that requires multiple steam as a source of potential energy as well as energy sources for processing purposes.

Figure 1. Pressure Turbine Opponents

ad.2. Condensing Turbine:

Condensing turbine is used when all the energy is used to generate steam power, while the former steam condenser is condensed into the opponent under pressure low enough to produce a high power, condensate water can be recirculated into the kettle.

  

 

Figure 2. Condensing Turbine

Ad.3. Turbine extraction:

Extraction turbine is divided into two types:

1. Extraction condensing turbine

2. Pressure extraction turbine opponents

Extraction condensing turbine, operating with dual vapor evaporation, which is in addition to power generation, as well as to supply the necessary steam extraction purposes.

Figure 3. Kettles turbines - Pressure Fight

ad.4. Mixed turbines (Turbine Mixing):

Turbine mixture also known as mixed pressure turbine (Mixed Pressure Turbine).

Low or medium pressure steam is used processed blended into the next level of a condensing turbine or a turbine pressure to boost power turbine opponents.

 

Figure 4. Mixed Turbines

ad.5. Turbine Pandu:

The turbine is also called pressure turbine turbine opponents because it is associated one or more existing turbines, specifically planned for a low initial pressure.

 

Figure 5. Turbine Pandu

 STEAM TURBINE PARTS

Steam turbine consists of several main parts such as:

1. Turbine house (Casing)

2. Rotating part (rotor)

3. Blades

4. Cushion

ad.1. Turbine house (Casing)

A turbine casing houses that make up the room (chamber) around the rotor to allow steam to flow across the blades.

Pedestal that serves as a buffer to put the pads are attached to the rotor casing. Generally one pedestal tied (Anchored) kepondasi dead, while others are placed on rail launcher (Sliding Feet) so that the casing to move freely. Due to the effect of expansion and contraction (Contraction), usually pedestal foundation is tied to the low pressure side of the pedestal or side adjacent to the generator (Generator End), while the other side is left to be able to move freely. When the casing and rotor temperature rises, the entire turbine construction will expand.

By placing one above the pedestal rail launcher (Sliding Feet), all turbine parts can move freely as it expands and as illustrated in Fig.1.

 

Figure 1. At the foundation casing construction

 Configuration Casing:

1. Casing intact

The entire casing is an integral part. Generally applied to the construction of small turbines.

2. Separate casing (Split Casing)

Turbine casing is 2 separate parts horizontally and connected into one binder bolts.

The second part of the casing, respectively called the upper casing (Top Half) and the casing bottom (Bottom Half). This construction is more widely used because of demolition and installation is relatively easy.

 Design Casing:

Turbine casing distinguished 3 categories:

a. Single Casing

b. Double Casing

c. Tripple Casing

Almost all of today applying steam turbine casing design double or triple casing for the period startnya faster, smaller problems of differential expansion and maintenance is relatively easy.

ad.a. Single Casing

Generally applied to the design of the old turbines and small capacity. Nevertheless turbines currently still no single casing design that applies mainly to the turbines for propulsion boiler water pump filler (BFPT). When this design is applied to large turbines, the turbine casing will be very thick so it takes quite a long time in the period of "warming" when it start to reach the full expansion.

This is because the walls are very thick casing and only heated by steam from one side of the inner side. These conditions resulted in substantial temperatu difference between the inner surface of the outer casing to the surface.

Thus the time required for temperature equalization becomes longer. Illustration of single casing turbine can be seen in Fig.1. following.

Figure 1. Single Turbine Casing

When the temperature of incoming steam turbine 454 ° C, then when the start-up temperature of the inside of the casing is also approaching 454 ° C. While the outside of the casing temperature is outside air temperature or about 38 ° C.

Thus, at the start there is a difference in temperature between the inner surface of the outer surface at 416 ° C.

The inside tends to expand while the outer portion is relatively not going to expand.

When the temperature difference is large enough, then in extreme conditions can cause cracks in the casing is quite thick.

ad.b. Double Casing

In double casing design consists of 2 turbine casing for each cylinder. Thus, the thickness of each - each case is only half the thickness of a single casing. Thus the distribution of heat and expansion process becomes faster.

Besides, as each segment becomes lighter casing, then maintenance becomes easier or faster.

As an illustration for tirbin double casing can be seen in Figure 2 below.

 

Figure 2. Double Turbine Casing

When the temperature of 460 ° C steam turbine atmospheric temperature being 38 ° C the difference in steam temperature 422 ° C. Double casing design advantage is that the Δt at 422 ° C is divided in 2 incoming steam casing, the casing (inner casing) at 460 ° C and out at about 349 ° C and then flows to the outer casing (outer casing) which means heating side the outside of the inner casing.

Thus Δt inner surface and outer inner casing is:

460 ° C - 349 ° C = 111 ° C

Moderate temperatures and the inner surface of the outer outer casing is:

349 ° C - 38 ° C = 311 ° C

Thus, in each case Δt becomes smaller to reduce possible cracking.

ad.c. Tripple casing

In the design of the casing tripple each cylinder consists of 3 pieces of the inner casing casing, intermediate casing and outer casing.seperti shown in the figure below.

Each casing walls become thinner and the relative temperature difference (Δt) each case will be lower so the time for even heat distribution is relatively even shorter.

Figure 3. Tripple Turbine Casing

ad.2. Rotor

Turbine rotor consists of a shaft with rings formed from a series of heated blades are aligned along the axis.

The rotor is the part of the turbine that converts the energy contained in the steam into mechanical energy in the form of shaft rotation.

In general there are two types of turbine rotor:

- Type rotor disk (Disk)

- Rotor drum

- Rotor disk type

On this type of rotor disks (Disk) is mounted on the shaft to form a disc ranks as shown below

 

Figure 4. type disc rotor (disc)

- Rotor drum

This type of rotor, shaft casted and shaped as desired and direct a series of blades mounted on a shaft. Rotor drum is very versatile and can be worn almost all types of turbines.

As an illustration of this type of rotor can be seen in the picture below

 

Figure 5. rotor drum

ad.3. Blade

is part of a turbine blade wherein the energy conversion occurs on the blade itself consists of a blade root portion, the body blades and blade tip as shown below

 

Figure 6. turbine blades

Blade as shown in Figure 6, then strung together to form a full circle.

The existing series of blades that functioned as the blade path and there are functionalized be fixed blade.

Series of blades mounted around a street circuit rotor blades are fixed mounted around the inner casing. The series blade serves to kinetic road steam into mechanical energy in the form of turbine shaft rotation. Being fixed blade, in addition there is a function to convert heat energy into kinetic energy, but there is also a function to reverse the flow direction of steam. Examples of the blade series can be seen in the picture below

 

Figure 7. blade path

In figure 7 shows that the blade root section is drilled into the grooves around the rotor, while the ends of the blades are united by a plate bajapenghubung called Shroud.

Shroud serves to strengthen and reduce the vibration of a series of blades. Fixed blades are generally arranged in a semicircle on a segment called the diaphragm as terliahat in the picture below 

 

            

Figure 8. Fixed blade

One segment of the diaphragm and then mounted on the casing around the bottom being a partner dippasang diaphragm segments at different parts of the upper casing.

When these two chassis together, between the diaphragm to form a full circle.

In general there are two types of blades:

- Blade impulse

- Blade reaction

Figure 9. impulse blade

On impulse blade, the entire heat energy changes into kinetic energy carried in fixed blade (nozzle).

When the blade across the road, the pressure did not change and theoretically, the vapor pressure before the blade the same way with the vapor pressure after the blade.

Because the turbine impulse pressure is often called flat. Denagn Thus, the turbine shaft with blades impulses arise virtually no axial force on the shaft.

Picture 10. blade reaction

 Being on the blade reaction, some of the energy is converted into kinetic energy heat fixed and partly disudu disudu road.

Result: each blade through the ranks, the ranks of both fixed blade and the blade line, vapor pressure will decrease. Consequences on the turbine blades reactions, axial forces arise quite big on the rotor shaft.

ad.4. Cushion

as part of a rotating, the rotor has a tendency to move in both radial and axial direction, because it's riveted rotor should be good to avoid a shift of radial and axial overload. Diapkai component for this purpose is called bearing (Bearing).

Steam turbines are generally equipped by:

- Bearing journals (journal bearing)

- Axial bearing (thrust bearing)

to support the rotor and rotor to shift mebatasi. Picture below is an example of a typical bearing above.

Picture 11. Cushion

On journal bearings, the inner surface of which may be in direct contact with the surface of the metal shaft coated by white (white metal / Babbit) are soft. Besides, there is also a channel - the channel where the lubricating oil to flow into the channel Diman Bantala and lubricating oil can flow out left bearing.

While the axial bearing (thrust bearing) consists of a disc umumya (thrust collar) which is part of the shaft and the two shoes (thrust pad) attached to the casing. Axial bearing function:

- To control the axial position of the rotor relative to the casing.

- Prevents the interface between the rotating part with a stationary part.

Axial retaining Style

1. Dummy Piston / Piston Balancing

Directors at the turbine pressure drop occurs in each row of blades - blade motion, will mengakibatka onset enormous force on the rotor where the direction of the force is in line with the flow of steam.

So to reduce the load on the bearing axial (thrust) axial force is balanced with a counterweight or a dummy piston piston mounted on the turbine rotor.

 

Image. Piston construction balancer

 

  

On the turbine casing which has a cylinder with double or tripple dummy casing is connected to the piston-cylinder steam out, but on a machine - a machine that old low-pressure side of the dummy piston cylinder low pressure associated with.

To reduce steam leakage at the edge of the dummy piston seals fitted labyrint types.

On the high and low dummy mounted piston seals (seal labyrint). Difference in surface area between the low pressure side and high pressure side dummy piston gives rise to the pressure difference between the two sides of the dummy piston.

Differences so as to produce sufficient thrust to offset the effect of axial gay steam flow through the turbine blades.

If still no resultant force is usually small enough, then this style will be muted by Bantala axial (thrust bearing) mounted on the front turbine

Dummy piston is only required on turbine blade with single wing type of reaction.

On the type of impulse turbine no vapor pressure reduction in blade - blade motion.

To ensure this, it made a hole - the hole offsetting pressure on the rotor rim.

The turbine - turbine flow like the IP cylinder and low pressure cylinder (LP) arising force - axial force opposing directions.

Thus the force - axial forces will cancel each other out with each other.

2. Bearing Axial (Thrust bearing)

Axial bearing construction which is widely used in steam turbines:

- For the turbine shaft flexible coupling connected with each spindle has its own axial bearing.

- For turbines with solid coupling mounted only one axial bearing is usually placed between the cylinder the cylinder HP LP

 

  

Image. Location Thrust Bearing

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