21-22 best knowledge on | DG set

21-22 best knowledge on DG set

In this post on Best knowledge on | DG set, we will discuss the details of DG sets, including DG set Selection, Operating Features, and the advantages of DG sets.

Short Description of DG sets

Diesel Engine Components( best knowledge on | DG set )

A DG set consists of the following components. The best matching of these components will be the criteria for the successful functioning of DG sets.

1. Prime mover (Diesel Engine) and associated accessories.
2. Alternator ( AC Generator)
3. Switchgear and control system
4. Powerhouse design and the civil work of the foundation.
5. The connected load on self components like heating, motor drives, and lighting, etc.

Best Book On Diesel Generators

Diesel Generator Handbook meets the need for an authoritative reference work covering the range of mechanical and electrical topics embodied in the practical design and application of diesel generating plant. It will be particularly welcomed in many parts of the developing world where the diesel generator is basic to the electricity supply system

This is the best Book on Diesel generators. The book is intended to serve as an engineering guide to all those who may be concerned with the selection, specifications, testing, commissioning, operation and maintenance of Diesel generator plant. It should therefore be valuable to ;- the plant or service engineers to non-specialist engineers and users; and to young technicians and engineers who are embarking on a career in the Diesel Generators.

DG set important selection factors.

Following important factors are mandatory for the selection of the DG set. The book is intended to serve as an engineering guide to all those who may be concerned with the selection, specifications, testing, commissioning, operation and maintenance of Diesel generator plant. It should therefore be valuable to ;- the plant or service engineers to non-specialist engineers and users; and to young technicians and engineers who are embarking on a career in the supply industry.

1. Speed
2. Loading
3. Environment conditions
4. Ambient conditions ( Temperature, altitude, and Humidity)
5. Fuel quality
6. Cooling system
7. Starting equipment
8. Control system
9. Type of drives

The formula for estimating the DG set rating-Best knowledge on | DG set-DG set selection factors-Unbalanced loads

DG set rating in KW = Maximum Demand/ % loading.

Maximum demand In KW= Connected Load/ Diversity factor

Rating in KVA= DG set rating in KW/ Power factor.

Diversity Factor= Installed load/Running Load

Types of Cooling in DG sets

1. Air Cooling
2. Water cooling

Water cooled DG set is better than Air cooled.  In the summer season, air cooling will not control the engine cooling water temperatures of the prime mover to rise beyond the permissible limits.

Reason for not paralleling the small DG set with the Grid supply

The reason for not paralleling the small DG with the grid supply is, Grid being the infinite bus, a small DG will be at risk of safety protection like reverse power relay, voltage, and frequency relay.

Unbalanced loads and its effect on DG set operation-Best knowledge on | DG set-DG set selection factors-Unbalanced loads

It will be better to have the best possible balanced loads. Unbalanced loads will cause the following irregularities.

1. Losses will increase
2. Excess heating of the system
3. Decrease in the efficiency
4. Unbalanced output voltage

The maximum permissible load between the phases should not exceed 10 % of the capacity of the DG set.

Effects of running DG set at a low power factor

Losses will increase due to the higher excitation current demand at a low power factor. Oversize AC generators running at lower power factors will result in poor operating efficiency and higher cost.

Energy balance in DG set.

Input

Thermal Energy; 100%

Output

Electrical Output; 35%

Alternator losses; 4%

Flue gases losses; 33%

Coolant losses; 24%

Radiation losses; 4%

Factor affecting waste heat recovery from flue gases

1. Loading of DG set
2. Exhaust gas temperature after the Turbocharger
3. Operating hours
4. Back pressure on DG set

Impact of Back pressure in the exhaust gas system

Additional pressure drop in the waste heat recovery unit causes back pressure in flue gas pathways. The back pressure should be between 250 to 300 mm of Wc.

 Waste heat recovery methods from DG set flue gases

1. Waste heat recovery Boiler ( WHRB)
2. Hot water use in the vapor absorption system

Application of Waste heat recovery system of DG set

1. Steam generation by WHRB
2. Pre-heating of combustion air for heaters and furnaces.
3. Air heating in dryers 
4. Process hot water generation
5. Process thermal oil heating
6. Use in vapor absorption refrigeration system
7. Pre-heating of Stock furnaces

Special Instruments to carry out the energy audit of the DG set.

1. Fyrite kit for the measurement of CO2 % in flue gases
2. Optic Pyrometer with sensor
3. Anemometer with vane for measuring the radiator air velocity
4. Engine Speed measuring digital tachometer
5. Load manager/ Power Analyser to measure the electrical parameters ( Voltage, current, KW, KVA, and Power factor)

Energy conservation methods for DG set

1. Waste heat recovery from flue gases
2. Load factor improvement
3. Installation of a paralleling system for the improved loading and economical operation of DG sets
4. Filtration improvement

DG set performance analyzing parameters.

1. Average Engine loading
2. Average Alternator loading
3. Alternator loading percentage
4. Engine loading percentage
5. Specific power generation KWH/ litre.

Vital steps during the selection of DG set with non-linear loads

Application check for the following loads.

• Rectifier/ Thyristor loads
• Welding loads
• Furnace Loads

Take the consultation from the OEM of DG set for the proper recommendations on achievement of desired utilization of DG set without any problem.

Identify the loads sensitive to voltage, frequency regulation, and voltage waveform, and feed such loads by a dedicated power supply which usually assumes the form of a DG motor-driven generator set. This alternative will ensure the restriction of the design of the AC generator. This process will also restrict the overall cost of the DG set.

Consider the following points while selecting the engine for the Dg set.

1. Engine Power
2. Engine Speed.

Engine Power;- Maximum load is the decisive factor for the power requirement. Engine power rating should be 10 to 20% more than the power requirement demanded by the end-user. By choosing the extra rating will prevent the engine from getting overload.

Engine Speed’- Engine speed is the other important factor for the selection of an Engine. The engine will be more efficient at optimum speed. Operate The DG set at the rated speed to avoid unwanted deposits in the combustion chamber and exhaust manifold.

Diesel Power plant advantages(Best knowledge on | DG set)

1. Low installation cost
2. Small delivery periods
3. Higher efficiency (43 to 45 %)
4. Plant performance is efficient even at part loads.
5. Less space area requirement
6. Auxiliary power consumption is low.
7. The diesel engine can run even on poor-grade fuels with high sulfur contents.
8. Cooling water requirement is optional and can run with air coolers in the area with less water.
9. Start-up time is short
10. DG set is easy to use.
11. DG set is the most dependable source of power generation.

Captive Power plant Comparison

Energy-saving measures for DG sets (Best knowledge on | DG set)

1. Load conditions should be steady on the DGset.
2. Improve the air filtration
3. Follow the guidelines of oil companies for the fuel oil storage, handling, and preparation 
4. Consider the use of additives.
5. Maintain the fuel injection equipment as per schedule.
6. Comply with the maintenance checklist
7. Use the waste heat recovery system.
8. Consider the parallel operation for improved loading and fuel economy.
9. Always carry out the DG set field trails regularly to monitor the DG set performance.

I hope the post has been useful to the readers.

Good Luck!!!