No matter the scope or size of your steam or hot water project, careful consideration must be given to the planning phase to ensure a successful outcome. There are a lot of factors that must be considered when choosing the appropriate system to meet your thermal needs.
From beginners to pros we have found the best tool to have for boiler projects is knowledge. Every boiler company will claim to have the best equipment but with a little advance planning the field can be narrowed substantially
See a term you don’t recognize? Please check out our Boiler Dictionary.
Heating Medium –There are three basic choices for using a boiler to supply heat: Hot Water, Steam or a Thermal Fluid variant. Below you will find a list to help you gather and assess information that will impact your design and ultimately your boiler choice
Steam Boiler Considerations
|15 psi, 150 psi, 250 psi, 300 psi or greater? Steam pressure requirements are process and temperature driven. Typically Firetube and Miura (modular on demand) boilers will be limited to 300 psi. Watertube boilers are used for higher pressures. In some cases steam can be superheated to provide temperature above the temperature of saturated steam at a given pressure.
|Saturated Steam or Superheated Steam
|Steam has many uses and is process specific but typically the steam will either condense in an exchanger or coil or will have direct contract with a product. If direct contact will be made careful consideration must be given to the quality of the steam and the nature of the chemicals used to treat the boiler water.
|Natural Gas, No 2. Oil, Biogas, Biomass, Heavy Oil, Hydrogen, Electric, other. There is an endless list of fuels that can be used to provide heat. However, regulations limit the use of certain fuels. For example in some areas of Texas and California, oil cannot be used due to its higher nitrogen content.
|Boiler capacity or size is usually expressed as Boiler Horsepower for Firetube boilers and Lbs Steam per Hour for larger Watertube boilers. Boilers expressed in Boiler Horsepower are done so under the assumptions of 0 psi and 212F feedwater temperature. Since this is never the case, a distinction must be made between rated steam output and actual steam output given your specific operating conditions
|From the EPA to your local jurisdictions there is a myriad of laws and regulations we can help you navigate. Typical emission that are regulated include CO, NOx, Sox and Particulate Matter(PM). There are lots of control strategies for each of these and many come with a penalty to efficiency or a burden on operations. We can help you select the appropriate emissions control technology.
|The efficiency of a steam boiler is the most abused and misunderstood category when evaluating or promoting boiler performance. See Miura efficiency page
|Depending on your electric service available, you will have several options. Most larger US boilers will require three phase service at 460V to run the FD fan and feedwater pump. Most controls will require 120V.
|Your process or steam requirements will determine the steam load profile. This can range from steady loads 24/7 to batch loads for only hours per day. The nature of this load will have a huge impact on the efficiency and life of your boiler and careful consideration must be given to the type of boiler used to service a given load profile
|If your steam load requires something other than 24/7 operations you will have to take the impact of start/ stop cycle and warm up times into consideration. This is a large efficiency penalty that is not captured in most efficiency measurements and must be taken into consideration when choosing a boiler system.
|If possible, a system should be designed to have condensate returned to the boiler room. Not only is there valuable heat in the condensate but it will not have to be softened saving both fuel and water treatment costs.
|There are two major factors that will impact the life of a boiler, thermal stress during start up and shutdown periods and water quality. All boilers will require softened pH controlled make-up water. A careful analysis should be taken of raw water available for the boiler system. See water treatment page
|In some cases the boiler room is the forgotten room of an operation. In some cases it is fully staffed with licensed operators. A lot of factors including local codes, safety and stream criticality must be considered when considering the operations and maintenance of a boiler.
|If a boiler is to be located outdoors special precautions must be taken to protect the electrical components and other items such as insulation. In some cases a dusty environment or other containments can impact combustion.
|If the steam production is a critical part of the process then mitigation of a boiler technical failure must be considered. This often includes designing the steam plant to be N+ , requiring a back-up boiler. Modularity should be considered.
|Each jurisdiction will have a separate set of codes and often times jurisdictions will overlap. The codes will dictate how the boilers are installed, operated and inspected. The requirements for licensed operators can be based on water volume, BTU input or other factors.
|A deaerator will use steam from the boiler to heat the boiler feedwater in a pressurized tank to over 200F. This mechanical process allows for the removal of oxygen and other dissolved gases that can lead to corrosion of the boiler vessel. It decreases the need for certain water treatment chemicals that would otherwise be necessary. Many incorrectly assume that a deaerator will add efficiency to a system because it delivers higher temperature water to the boiler, however, it is actually a slight (parasitic) loss — remember the steam to heat the water comes from the boiler itself. Traditionally, the rule of thumb is that boilers over 800Hp should have a deaerator. However, this rule has now been challenged through the use of forced flow boilers. See Miura boilers page.
|Once the rate of condensate return has been established, the value in pre-heating make-up water or all the boiler feedwater can be assessed. All else being equal, the colder the feedwater temperature the more opportunity there is to optimize the boiler efficiency. This is normally through use of an economizer or other heat recovery device.
|There are many regulations, codes and safety requirements for a boiler system. Some are required by local jurisdictions, some by insurance companies and some are self imposed standards of the end user. Despite all these requirements there are still boiler accidents each year and some that are fatal. Be sure to work with the manufacturer or our company to understand these risks and how they are mitigated.
|All boiler and manmade machines and one time or another a part will fail. When considering the potential for maintenance issues find out if the parts used on the boiler are proprietary, the average length of time for annual inspections, a typical spare parts list, local service, factory service and the simplicity of the design.
|There are a lot of options for extracting data from a boiler to be monitored onsite or offsite. Ask if the manufacturer has the capability to do this and the impact it has had on boiler uptime.
|Boiler blowdown is necessary to control conductivity levels of the boiler and eliminate Total Dissolved Solids (TDS) that have concentrated in the boiler. Depending on local codes this blowdown may need to be cooled before discharging . There are several energy optimization opportunities here including, blowdown heat recovery, blowdown minimization and flash steam recovery.
|When designing a boiler room some advanced planning can go a long way. Some areas to be considered are the availability of combustion air, fuel volume and pressure requirements, space constraints, foundation (weight) constraints, access for future equipment addition removal, roof and boiler stack design, ambient temperature and a host of personnel safety requirements