Power & Heat Systems, LLC
10005 Whitesel Road Ashland, VA 23005
Tel: 804-798-1318 Fax: 804-752-7631
Call Toll Free: 800-552-6661
10005 Whitesel Road Ashland, VA 23005
Tel: 804-798-1318 Fax: 804-752-7631
Call Toll Free: 800-552-6661
Power & Heat Systems: Case Studies
Biogas Boiler/Burners in Wastewater Treatment
Posted: Sep 24
Energy costs continue to skyrocket across all business categories, taking a larger and larger share of company budgets. Because of this dramatic impact on company profits, every business should take advantage of any opportunity to reduce these costs. This is just as true for non-profit driven entities as will as in as for profit driven companies. City and county wastewater treatment facilities are excellent examples of non-profit entities which consume a lot of energy. These facilities need that energy to provide the heat to keep their anaerobic digester process working at peak efficiency to treat our wastewater.
One of the by-products of that digester process is a biogas, often called methane gas because it is approximately 50% by volume methane. This gas also contains a small amount of hydrogen sulfide (H2S) making it corrosive and lethal in low concentrations. But this biogas is an efficient fuel stock, with the significant cost benefit of being free.
Richmond, Virginia is very fortunate to be the home of one of the worlds leading companies involved with water cleaning and purification. One of their groups designs and builds wastewater treatment plants used around the world. Power & Heat Systems, LLC, headquartered in the Richmond area, has been selected to work with the engineers at this company to provide the hot water boilers used to keep the anaerobic waste digesters working at peak efficiency. A recent project involved the installation of two boilers similar to the one shown in Figure 1. The package boiler shown was selected for this particular project because of its ability to solve many of the challenges associated with the efficient burning of biogas. For this particular project, several factors were considered during the selection process of this package boiler.
The high levels of maintenance repairs required to keep many systems working often have them out of service. The equipment selected for the boiler shown in Figure 1 has all been designed to efficiently burn the biogas and limit the need for the wastewater plant to use expensive natural gas, propane, or light oil to produce the hot water for the anaerobic process.
If the wastewater plant is not using the biogas as a fuel stock, it is required to flare or burn this gas to the atmosphere. The unburned biogas is too toxic for humans to breath. It addition it has a very objectionable odor.
Cold return water entering a boiler can cause high levels of thermal stress, called thermal shock. This thermal shock can be the cause of constant and expensive repairs of the boiler, almost always leading to premature failure and replacement.
The steel boiler in Figure 1 offers a very innovative construction to distribute the stresses associated with water returning to the boiler being too cold. Unlike most steel boilers, the L.E.S. boiler does not contain a large number of short stay bolts. This construction technique, combined with a U-type flex-joint between the furnace and the front tube sheet, serve to minimize thermal stress and shock damage to the boiler. This allows the boiler to safely operate over a wider range of delivery and return temperatures.
The Webster burner and all of its support components were selected specifically for their ability to:
Provide stable and complete combustion of the biogas fuel. The small amount of H2S present in the Biogas is the culprit, which makes the gas toxic to humans. This molecule in the gas is rendered it harmless in the very high temperatures developed in the biogas flame.
The components that come in into direct physical contact with the biogas were all engineered specifically to provide many years of excellent service thereby limiting expensive repairs.
Stainless steel pipe is used to stop the corrosion, which causes leaks in black iron pipe that leads to human exposure to this dangerous gas.
This system, like all systems, will require periodic inspections, maintenance, and adjustment to ensure that everything is working properly. But this customer has taken one additional step to ensure that between checkups the system will automatically control itself to maintain its very high combustion efficiency.
In place of the old style linkage controls (shown in Figure 2) with a single modulation motor driving the air damper, the biogas flow control valve and the back up natural gas fuel flow control valve through interconnected linkage, Power & Heat supplied a Honeywell ControlLinks system which eliminates all the interconnecting linkage and inherent variations in fuel-air mixtures. Each of the flow control devices has their own, very accurate (+0.1o angularity) positioning system for each of two independent fuels to maintain their own specific air control curve. The control maintains the fuel-air setting at all firing rates between tune-ups.
The linkage-less control system allows each fuel, the primary biogas and the back up natural gas or oil fuel, to have it own unique air-to-fuel curve. The system allows for a more efficient combustion setting for each of the fuels and will meticulously maintain that efficiency from tune up to tune up.
The technology applied to this project can be applied to most boilers with savings that offer real paybacks. Boiler owners can reduce their energy cost enough to cover the cost of improvements and provide added profits, help reduce our dependence on fossil fuels, and to be better environmental stewards by producing fewer greenhouse gases.
Previous Case Study -|- Next Case Study
List of all Case Studies
Biogas Boiler/Burners in Wastewater Treatment
Posted: Sep 24
Energy costs continue to skyrocket across all business categories, taking a larger and larger share of company budgets. Because of this dramatic impact on company profits, every business should take advantage of any opportunity to reduce these costs. This is just as true for non-profit driven entities as will as in as for profit driven companies. City and county wastewater treatment facilities are excellent examples of non-profit entities which consume a lot of energy. These facilities need that energy to provide the heat to keep their anaerobic digester process working at peak efficiency to treat our wastewater.
One of the by-products of that digester process is a biogas, often called methane gas because it is approximately 50% by volume methane. This gas also contains a small amount of hydrogen sulfide (H2S) making it corrosive and lethal in low concentrations. But this biogas is an efficient fuel stock, with the significant cost benefit of being free.
 |
Figure 1 Biogas Boiler/ Burner |
The high levels of maintenance repairs required to keep many systems working often have them out of service. The equipment selected for the boiler shown in Figure 1 has all been designed to efficiently burn the biogas and limit the need for the wastewater plant to use expensive natural gas, propane, or light oil to produce the hot water for the anaerobic process.
If the wastewater plant is not using the biogas as a fuel stock, it is required to flare or burn this gas to the atmosphere. The unburned biogas is too toxic for humans to breath. It addition it has a very objectionable odor.
Cold return water entering a boiler can cause high levels of thermal stress, called thermal shock. This thermal shock can be the cause of constant and expensive repairs of the boiler, almost always leading to premature failure and replacement.
The steel boiler in Figure 1 offers a very innovative construction to distribute the stresses associated with water returning to the boiler being too cold. Unlike most steel boilers, the L.E.S. boiler does not contain a large number of short stay bolts. This construction technique, combined with a U-type flex-joint between the furnace and the front tube sheet, serve to minimize thermal stress and shock damage to the boiler. This allows the boiler to safely operate over a wider range of delivery and return temperatures.
The Webster burner and all of its support components were selected specifically for their ability to:
Provide stable and complete combustion of the biogas fuel. The small amount of H2S present in the Biogas is the culprit, which makes the gas toxic to humans. This molecule in the gas is rendered it harmless in the very high temperatures developed in the biogas flame.
The components that come in into direct physical contact with the biogas were all engineered specifically to provide many years of excellent service thereby limiting expensive repairs.
Stainless steel pipe is used to stop the corrosion, which causes leaks in black iron pipe that leads to human exposure to this dangerous gas.
 |
Figure 2 Linkage System |
In place of the old style linkage controls (shown in Figure 2) with a single modulation motor driving the air damper, the biogas flow control valve and the back up natural gas fuel flow control valve through interconnected linkage, Power & Heat supplied a Honeywell ControlLinks system which eliminates all the interconnecting linkage and inherent variations in fuel-air mixtures. Each of the flow control devices has their own, very accurate (+0.1o angularity) positioning system for each of two independent fuels to maintain their own specific air control curve. The control maintains the fuel-air setting at all firing rates between tune-ups.
The linkage-less control system allows each fuel, the primary biogas and the back up natural gas or oil fuel, to have it own unique air-to-fuel curve. The system allows for a more efficient combustion setting for each of the fuels and will meticulously maintain that efficiency from tune up to tune up.
The technology applied to this project can be applied to most boilers with savings that offer real paybacks. Boiler owners can reduce their energy cost enough to cover the cost of improvements and provide added profits, help reduce our dependence on fossil fuels, and to be better environmental stewards by producing fewer greenhouse gases.
Previous Case Study -|- Next Case Study
List of all Case Studies
