Stack Height Calculation for DG Sets - CPCB Guidlines

Stack Height Calculation for DG Sets to ensure effective dispersion of exhaust emissions and to comply with the regulations. Stack height is a critical consideration when installing diesel generator sets (DG sets) to ensure effective dispersion of exhaust emissions and to comply with environmental regulations. The stack height of DG sets plays a significant role in minimizing the impact of pollutants on air quality and human health. The following factors influence the determination of stack height for DG sets:

1. Emission Rate: The rate at which pollutants are emitted from the DG sets is a crucial parameter in calculating the stack height. The emission rate is typically provided by the manufacturer and is measured in kilograms per hour or grams per second.
2. Exit Velocity: The speed at which the exhaust gases leave the stack is an important factor that affects the initial rise of the plume. A higher exit velocity can result in a higher plume rise.
3. Stack Diameter: The width of the stack opening or exhaust duct is another factor that influences the dispersion of emissions. A larger stack diameter may lead to better dispersion.
4. Exit Temperature: The temperature of the exhaust gases as they exit the stack can impact the buoyancy of the plume. Hotter gases tend to rise more quickly, affecting the plume rise.
5. Ambient Temperature and Wind Speed: Weather conditions, such as ambient temperature and wind speed, play a significant role in the dispersion and dilution of pollutants. These factors affect the behavior of the plume in the atmosphere.
6. Buoyancy Factor: The ratio of the exit temperature to the ambient temperature, known as the buoyancy factor, influences the plume’s behavior and dispersion.
7. Building Height and Terrain: Nearby buildings and the surrounding terrain can influence the dispersion pattern. Tall buildings or hills may obstruct the plume and require additional stack height.
8. Regulatory Requirements: Local or national environmental regulations and guidelines may specify minimum stack height requirements for DG sets to ensure compliance with air quality standards.

To calculate the stack height for DG sets, dispersion modeling tools and software are often used, which take into account the above factors to estimate the appropriate stack height required for effective dispersion of emissions. It is essential to consult with air quality and environmental experts or regulatory authorities to ensure that the stack height complies with local regulations and minimizes the impact of emissions on nearby areas and public health. Properly calculated stack height and effective dispersion of emissions are essential for maintaining good air quality and mitigating the potential adverse effects of diesel generator operation on the environment.

DG Set Height Calculation formula as per Source: CPCB Emission Regulation Part IV

Calculating Stack Height of DG sets For A Facility:

The minimum height of stack to be provided with each generator set can be worked out using the following formula :

(a) Below 1000 KVA Dg Set Stack Height:

             H = h + 0.2 x √ KVA  

(b) Above 1000 KVA Dg Set Stack Height :

             30 m High or 3 m above the building height, which ever is higher.

Where:

H = Total height of stack in meter

h = Height of the building in meters where the generator set is to be installed

KVA = Total generator capacity of the set in KVA

This is an explicit formula for DG SET stack height calculation, irrespective of the type of industries where the generator set is installed.

Based on the above formula the minimum stack height to be provided with different range of generator sets may be categorized as follows:

For Example, 750KVA DG set Stack Height

For DG Set above 1000KVA, minimum stack height should be 30 m. Dg set exhaust port should be atleast 3m above the building where it is placed. So that total stack height should be 30m or more.

For example if a building is 25m high, then dg set stack exhaust port should be 5m. So total stack height will be 30m.

Another example if building height is 32m, then dg set stack exhaust port should be 3m above the building, so total stack height will be 35m.