Switching your boiler over to natural gas could save a lot of money in the long run, but it is not the right choice for everyone. Here are the nine big questions and things you need to know when considering converting your boiler to run on gas:
1. What will it take to get natural gas to my boiler? One of the first things you need to do is find out if there is a pipeline nearby and the distance that you will have to run piping outside of your plant. An economic analysis needs to be done when it comes to reaching a gas line, especially one that requires crossing a stream or other obstacle.
2. If I can’t get natural gas to my boiler, what are my options? Contact your local gas supplier to see if it could be worth it for them to run a line nearby your plant. This is more of a long-term process. Running a pipeline could take months or years. It may be an option to get delivery of compressed or liquefied gas to operate your boiler until a permanent gas supply can be established.
3. Do I need to change my control system? An engineering study will be performed to simulate how your boiler will behave will gas. Depending on the type of boiler, your control system may need modification. Some old boilers require retrofitting and additional instrumentation. The control system will likely need to be modernized or upgraded as a result of fuel change and will likely involve DCS and BMS, depending on the type of boiler. NFBA 85 code must be met.
4. How will it affect the way my boiler used to operate? The engineering study will also help determine the differences in operation. Your boiler may require a slightly different startup time with a different fuel. Oil has a rich, luminous flame, but gas will have a slightly transparent one. Without oil there will also be less exhaust gas and heat transfer is affected.
5. Do I have enough space available to do a boiler conversion? Gas conversions require a big piece of equipment that valves and skids need to run on that can take up a big chunk of space. This is also determined in the engineering study after the physical plant is surveyed for an appropriate place to house the new equipment.
6. Should my boiler be able to run on both fuels? That depends on your contract with your gas supplier. There may be a time when gas is more expensive than oil, so you might want to leave the option of going back to oil if needed. This is something that must be decided early in the project and is more expensive to set up. There may be a time where gas is curtailed which would require an alternate source of fuel. The proper option can be determined in the contract phase with your gas supplier.
7. Can I continue to fire my solid fuels together with gas? You may want to be able to fire gas and solid fuels (coal, wood, etc.) This can be determined on a case by case basis and decided early on so that the boiler can be modeled correctly. Modifications may be necessary on control systems and your boiler.
8. How will it affect my emissions? Generally, emissions are improved while firing gas. Firing gas will affect emissions more on start up than when your boiler gets up to a full load. Also, Carbon monoxide can be hard to control during startup. The EPA requires stricter emission requirements that may determine the type of fuel that you’re firing.
9. What modifications will be required to achieve my original operating conditions? Modifications to the operating controls as well as the physical boiler may be necessary. The engineering study will determine if your boiler will be able to handle the conversion and achieve original operating conditions or at least come close. Based on the original design conditions a boiler derate may be necessary. If the boiler was originally designed to fire oil or coal, a derate will most likely be required. The engineering study will determine this information for you.
If you have any further questions about a boiler conversion, contact us here: http://www.metso.com/corporation/mci_84101100.nsf/home?readform