For many years, the air pollution emission norms were lenient, and no major emphasis or attention was given to reduce the industrial pollution. The rising pollution levels were damaging the ecological system and human health in and around the plants. This pushed the government to enforce strict guidelines and regulations for emission limits on the industry. As a result, many industries have revamped /upgraded their existing air pollution control equipment for lower emissions.
For some of the industries, for instance cement, the pollution control equipment also acts as a product recovery system. Hence lower the emission norms, it is better for the industry as they will recover the products and increase the revenue.
Although ESP can provide lower emissions as low as < 10 mg/Nm3, but the cost to achieve the same is much higher for ESP as compared to some other solutions like a Bag Filter or a Hybrid Filter. Also, the space required to achieve the same is far more for ESP as compared to other solutions.
The existing plants (which were installed earlier with old emission norms) are also required to be upgraded / changed as per the new stricter emission norms. To do this, there are various constraints while re-designing the equipment. There are various solutions available to do so and match the current norms.
In older days, this following pollution control equipment’s were more commonly used:
– Reverse Air Bag House (RABH)
– Electrostatic Precipitator
These equipment’s have their own drawbacks and limitations.
The existing ESP can be modified in various ways to achieve the desired lower emission levels. However, this has various challenges, which can be overcome in various ways:
- Addition of new field
- Installation of another ESP in parallel to existing ESP
- Replacement of Electrodes and modification in HV
Over a period, the plant production capacities are increased. In such a case, the existing equipment’s are not capable to handle the additional volume flow rates or dust loads. The Bag Houses can be modified to suit the current emission norms or the additional volume flow rate by various ways:
- For handling higher volume flow rates and achieving lower emissions, Existing plenum can be replaced along with increase in bag length and using the new advanced filter bags available. For this, existing casing and hopper should be in good physical condition. If not, then additionalmodules can be installed in continuation with existing ones. Dust discharge arrangement can be reviewed for the capacity and same can be replaced if required.
- In some cases where only lower emissions are required, change in type of filter media can be done.
If the existing ESP cannot be revamped or upgraded to meet the new environment norms, it can be demolished completely and a new pulse-jet bag filter can be installed by using the existing technological structure and civil footings.
The existing ESP can be retrofitted into pulse jet type bag house by retaining casing, hoppers & conveying system, ducting, etc. All the electrodes are removed, and ESP roof is modified to accommodate new plenum and tube sheet.
This is a more economical solution and has advantages of both ESP and Bag Filter in one installation. In this case, first field is kept as it is and other fields are converted into a bag filter, depending on the emission requirement. The structures can be reused.
- Lower clean gas dust emissions compared to the ESP
- Economical bag filter design using low pressure pulse jet cleaning in combination with bag length up to 8m can be used for ESP conversions, to decrease the pressure drop across the filter bags and can help increase the bag life time, which will lead to lower power consumption
- Re-use of existing casing, duct work, steel support, dust transport and auxiliary equipment can help save a lot of cost.
- Flexible and pre-assembled filter head module design reduces downtime to a minimum and enables the plant to execute ESP conversions during regular plant shutdown times
- Since most of the dust load is taken out in the ESP Section, the cleaning requirements are reduced in the Bag Filter section leading to low compressed air consumption & longer bag life
- Low cost solution in comparison to new installation cost.
- This applies best for the cramped layouts where it is difficult to find space for new equipment. The plant / duct layout remains unchanged.
- Sinter Plants
- Thermal Power Plants
- Municipal Waste Incinerators
We have the technical know-how and capability to cater to the needs of retrofit and revamp upgradation requirements from concept to commissioning.