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Opportunities Waste Heat Recovery Creates for Industries

Opportunities Waste Heat Recovery Creates for Industries

Process heat is essential to many industrial operations; however, a significant amount of that heat energy is lost due to exhaust gases and steam, the heat released by industrial ovens, cooling processes, and as a byproduct of refrigeration. Instead of releasing it into the environment, this heat energy can be recovered and used to offset energy needs in many industrial processes including:

  • Heating feedwater in boilers for steam applications or for use with closed loop heat transfer systems
  • Combustion air preheating for process heaters, boilers, ovens, and furnaces
  • Creating electricity with an Organic Rankine Cycle (ORC) unit – waste heat is transferred to hot oil or hot water that is then used to drive an ORC turbine that utilizes the heat transfer fluid to drive the turbine and generate electricity

Here, we’ll look at the principles behind waste heat recovery and some examples of how it can be used in industry.

Opportunities for Waste Heat Recovery in Different Industries

Heat waste can be grouped into three broad categories: high temperatures over 400°C (e.g., from combustion), medium temperatures between 100°C and 400°C (e.g., exhaust from combustion), and low temperatures under 100°C.

Depending on the type of heat being captured and the target applications, there are several ways to design waste heat recovery systems. These systems may use a combination of condensers, evaporators, heat exchangers, compressors, turbines, generators, and pre-heaters to reclaim heat for energy savings.

Waste heat recovery technologies are used to offset fossil fuel consumption from existing process heating equipment which also reduces carbon emissions, or for on-site power generationThese systems are used in many industries including, but not limited to, the following:

Municipal Power Generation

Power plants use waste heat recovery technology to improve the efficiency of combustion turbines and power boilers.

Fuel Refining

Heat is recovered from applications such as:

  • Thermal cracking
  • Petroleum distillation
  • Flue gas emissions (with proper handling of sulphuric acid byproducts)

The reclaimed heat can be used in boilers or for pre-heating in cold combustion air processes.

Cement Production

Cement facilities operate kilns at 200°C to 400°C to produce clinker, the material that is finely ground to create cement. Waste heat from kilns can be recaptured to produce additional process heat or energy. Research by the Department of Energy indicates that while this technology is readily available, it has traditionally been underutilized.

Food Industry

Many food processing and production applications generate low- to medium-temperature waste heat that can be recovered. Some examples include heat generated by:

  • Refrigeration and freezing
  • Rendering
  • Hot cleaning and wash water and steam
  • Singeing and scaling in meat and poultry processing
  • Dairy and egg pasteurization
  • Cooking and canning fruits and vegetables
  • Baking and frying

Iron and Steel Industry

Iron and steel production requires enormous amounts of energy, resulting in equally enormous amounts of waste heat. Opportunities for recovery include:

  • Heat from cooling areas and slag
  • Combustion exhaust from blast furnaces
  • Waste gas from electric arc furnaces in steel recycling
  • Heat capture from dry and wet coke quenching

Learn More About Waste Heat Recovery

As technology evolves, the advantages of waste heat recovery continue to increase. Selecting a system tailored to your application translates to greater energy efficiency and facility-wide savings.

Sigma Thermal specializes in providing waste heat recovery systems and process heat solutions for customers in many industries. Our products include thermal oil and thermal fluid heating systems, electric process heaters, indirect process bath heaters, direct-fired process heaters, biomass-fired energy systems, system automation, parts, and retrofits/upgrades.

Please contact us to learn more about waste heat recovery and process heat options, or request a quote today.

Benefits of Thermal Fluid Heaters in the Oil and Gas Industries

Industrial thermal fluid systems are indirect heating systems that increase the temperature of process fluids, such as crude oil and petroleum products in the oil and gas industry. These heating

 systems offer several key advantages over steam systems. This blog will explore industrial thermal fluid heaters briefly, including the benefits they provide for various applications in the oil and gas industry.

What Are Thermal Fluid Heaters?

An industrial thermal fluid heater is a closed-loop heating system that uses a heat medium like thermal oil, water, or water/glycol to increase the temperature of the process fluid. This indirect heating process relies on oil, natural gas, wood, or electricity to heat the thermal medium. Once the medium reaches the desired temperature, a pump circulates it to one or multiple heat exchangers or consumers.

Thermal fluid heaters commonly heat crude oil in the oil and gas industry to reduce oil viscosity for easier pumping and transporting. These heaters also facilitate process heating applications such as dew point heating, regeneration gas heating, and glycol or amine reboilers.

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Benefits of Thermal Fluid Heaters in the Oil and Gas Industries

Advantages of Thermal Fluid Heaters

Industrial thermal fluid heaters deliver a variety of benefits that make them an ideal choice for oil and gas heating applications:

  • Easy Operation and Low Maintenance: Thermal fluid heaters are low maintenance and easy to operate. Thermal oils can lubricate the thermal fluid heater so that the heater does not require monitoring or chemical treatment to prevent corrosion.
  • Reduced Energy Consumption: Thermal fluid heaters offer up to 20% less energy consumption than steam heaters, avoiding heat loss from feedwater preheating, blowdown, and steam traps.
  • Decreased Emissions: These heaters also result in reduced total exhaust emissions due to higher thermal effeciency.
  • Higher Operating Temperatures: Because thermal oil’s boiling point is higher than that of water, thermal fluid heaters can operate at a higher temperature range (-40 to 750 °F or -40 to 400 °C) than steam heaters can. Thermal fluid heaters can also heat process fluids at a range of different operating temperatures using secondary control loops.
  • Better Safety: Since thermal fluid heaters operate at lower pressures than steam boilers, thermal fluid heaters don’t provide a risk of pressure related explosion tofacility personnel.

Cost-Effectiveness of Thermal Fluid Heaters

Thermal fluid heaters are a cost-effective solution for the oil and gas industry. Compared to steam systems, thermal fluid systems offer more long-term cost savings in the form of reduced maintenance and lower overall operating expenses. Plus, thermal fluid heaters certified under ASME Section VIII typically don’t require a licensed boiler on site.

Industrial thermal fluid heaters offer up to 20% in fuel savings compared to steam heating systems by eliminating the potential for steam traps, blowdown, and feedwater preheating, all of which may cause heat loss and force the system to work harder to maintain the desired temperature.

Sigma Thermal’s Thermal Fluid Heaters for the Oil and Gas Industries

Industrial thermal fluid heaters use a combination of water and glycol or thermal oil in a closed-loop system to indirectly heat process fluids. In the oil and gas industry, crude oil needs to be heated to reduce its viscosity and make it easier to transport. Thermal fluid heaters offer several advantages over conventional steam systems, such as higher operating temperatures and lower energy consumption.

Sigma Thermal designs, engineers, services, and supplies heating systems like thermal fluid heaters to customers in the oil and gas industry. Our team can help you find the ideal heating solution for your facility or worksite. Contact us or request a quote to speak with a team member about the thermal fluid heating solution for your oil and gas application.

Industrial Process Heating Methods

Process heating systems deliver heat to liquid, gas, and solid materials in various industrial settings. Depending on the application, multiple types of heating methods can be used. We will explore several of these industrial heating methods as well as their benefits and applications to help you determine the ideal solution for your application.

The Different Industrial Process Heating Methods

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Industrial Process Heating Methods

Process heating systems rely on different fuel sources and heating methods to deliver indirect or direct heat to the process material. Here are a few common heating methods.

Combustion or Fuel Based Heaters

Combustion process heaters burn gasses, liquids, or solids to produce and transfer heat to the process material indirectly or directly. Oil, natural gas, coal, charcoal, wood chips, cellulose, and ethanol are common fuel choices. Air or oxygen is introduced to the fuel to achieve combustion. In direct heating, the combustion gas makes direct contact with the process material. In indirect heating, the process material is heated in a vessel away from direct contact with the combustion gas.

Electric Process Heaters

Electric process heaters rely on resistive heating elements through which electric current is passed to generate heat. The heating elements can then be used to directly or indirectly heat processes in tanks, ducts, or circulation vessels.

Heat Recovery and Exchange Systems

Heat recovery and exchange systems rely on a heat exchanger to transfer heat from one process material to another. For example, a manufacturing facility can use a heat exchanger to recover the heat produced by an exothermic chemical reaction and use it to provide heat to another application.

Boilers and Thermal Fluid Heating Systems

Boilers use fuel combustion to produce steam. This process heating method offers simplified transportation, low toxicity, high heat efficiency, and low cost. Boilers are one of the most prevalent process heating solutions in manufacturing facilities. They can be complex and require consideration of various factors to deliver efficiency and performance.

Thermal fluid heating systems utilize a heat transfer medium in the liquid state that is pumped through the heater and out to the heat transfer consumers. These systems commonly use organic or synthetic oils that allow for operation at high temperatures with little or no pressure when compared to boilers.

Hybrid Systems

A hybrid system utilizes multiple energy sources to heat material. For example, a paper manufacturer can use a fuel-based dryer in combination with an electric infrared heater to dry paper.

What Are the Benefits of Industrial Process Heating Systems?

When you partner with an experienced process heating system manufacturer and select the right system, you can enjoy the following benefits:

  • Cost Efficiency: A suitable process heating system delivers optimal heat transfer and generation, improving efficiency, reducing energy consumption, and producing a higher quality product at an overall lower operating cost.
  • Simple Installation: Quality process heating systems provide an all-in-one solution for heating and control. An experienced heating system manufacturer can deliver a custom solution that meets the specified space requirements and can be quickly assembled and installed on-site.
  • Centralized Control: Process heating systems can be managed remotely with advanced instrumentation and controls.

Applications of Industrial Process Heating Systems

Process heating systems are ideal for a variety of flowing liquids, gasses, and air. They are used in the following process heating and industrial applications.

  • Caustic Solution Heating
  • Fuel Gas Heating
  • Hydraulic and Heat Transfer Oils
  • Lube Oil and Fuel Oil Heating
  • Molten Salts
  • Process Air and Gas Heating
  • Process Chemical Reactors
  • Steam Superheating
  • Water Heating
  • Water-Glycol Solution Heating

Process Heating Systems From Sigma Thermal

Industrial and manufacturing facilities have a range of choices for process heating methods. There are several types of heating systems available for solid, liquid, and gas materials, with either direct or indirect heating. Working with a knowledgeable and capable partner is vital to selecting the ideal process heating system for your application that delivers optimal performance and efficiency benefits.

Sigma Thermal offers custom and standard process heating solutions for gasses, solids, and liquids. We offer a selection of combustion, electric, heat recovery and exchange, boiler, and hybrid process heaters, all of which can be customized for your specific needs. Sigma Thermal is ISO 9001:2015 certified and serves a worldwide market.

Contact us or request a quote for your application’s ideal process heating solution.


What Is a Thermal Fluid Heating System?

Heating and precise temperature control are crucial to many industrial processes. These systems also offer consistent performance and work at high temperatures yet low pressures for safer operations. Learn more about thermal fluid heating systems, how they work, their benefits compared to direct-heat and standard steam systems, and other applications.

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What Is a Thermal Fluid Heating System

What Is a Thermal Fluid Heating System?

Thermal fluid systems utilize a heater in combination with thermal oil, water, glycol, or other thermal fluids. The heater within the system warms the fluid of choice before continuously recirculating it through the system, transferring indirect heat to the appropriate process systems, machinery, and materials. Thermal fluid heating systems provide centralized indirect heat so the heater and the heated object never directly touch, just one of their many benefits as compared to direct-fired heating systems.

Thermal fluid systems utilize two loops to control the requirements of each of its heat consumers. The primary loop provides thermal fluid to one or more consumers at a consistent flow rate and temperature, whatever the return temperature. This loop is usually made up of a heater, drain and expansion tanks, and a single or multiple circulation pumps.

As for secondary loops, thermal fluid systems can have single or multiple secondary loops. Secondary loops help meet consumer demands by drawing thermal energy from the fluid at its necessary flow rate and temperature. Generally including a heat exchanger and a thermal fluid control valve, these loops sometimes use a secondary loop pump as well.

What Are the Advantages of Using Thermal Fluid Heating Systems?

Thermal fluid heating systems offer many benefits, including:

  • Reaching high temperatures while maintaining low pressure. Thermal fluid systems are capable of covering a temperature range of 32° F up to 750° F with zero or minimal vapor pressure, unlike standard steam systems that heat from 250° F to 350° F at a design pressure of 150 PSIG.
  • Enhancing efficiency. Unlike steam systems that lose energy through blowdowns and steam straps, thermal fluid systems don’t experience the same auxiliary heating losses. Any heat energy that goes unused flows back to the system through the closed-loop circuit of thermal fluid.
  • Reducing maintenance needs. Like steam boilers, thermal fluid heaters necessitate combustion checks. However, they don’t need regular water treatment, daily blowdown, steam-trap maintenance, retubing hand-hole gasket replacement, or yearly checks for pressure vessels, reducing overall maintenance requirements. That said, always follow the maintenance guidelines your manufacturer outlines to achieve maximum functionality.
  • Central plant heating. For plants using direct-fired heaters, every operational process requires a heater of its own for adequate heating. Thermal fluid systems, however, generate indirect heat that then pumps to multiple heat consumers. This allows operations to separate the heater and the components of its primary loop system from key areas of production. Not only does this mean that thermal heating systems are applicable for outdoor as well as remote indoor installations, but the indirect heating method enhances safety within a facility.

Thermal Fluid Heating Systems Applications

Common industries and applications for thermal heating systems include:

  • Food & Beverage. Fryers for poultry or meat, ovens in bakeries, and snack food production.
  • Rubber, Plastics and Composites. Heat for extrusion and molding processes.
  • Chemicals. Continuous processing applications and batch reactors.
  • Petrochemicals. Catalysis, synthesis, and distillation processes for the petrochemical industry.
  • Oil & Gas. Critical for fuel extraction, transport, refining, and recycling.
  • Construction Materials. Heat presses and dry kilns in facilities for roofing and engineered wood production.
  • Asphalt. Asphalt hot-mix paving and roofing applications for the asphalt industry.
  • Converting. Rolling, pressing, printing, and laminating.
  • Die-casting. Temperature control in die-casting applications.

Thermal Fluid Heating Systems From Sigma Thermal

Industrial facilities need reliable, consistent process heating and temperature control for optimal performance and safe operations with minimal downtime. At Sigma Thermal, we design, manufacture, and service a wide range of standard and engineered heating systems for diverse industries worldwide. Our expert team of engineers and technicians will work closely with you to gain an in-depth understanding of your application and find the ideal solution based on your unique project requirements.

Contact us to learn more about our thermal heating system offerings, or request a quote today.

Effects of Inconsistent or Improper Fuel for Biomass Systems

Biomass is a plant-based product used as fuel to generate heat and electricity. It is an eco-friendly renewable alternative to traditional forms of energy, such as fossil fuels. Biomass includes wood products such as chips, logs, pellets, and other forestry materials such as limbs and brush. 

Biomass-fired combustion systems are useful in many wood product manufacturing and power generation processes. These systems are commonly used for hot gas generation and indirect heating applications. Some applications include:

  • Rotary Dryers – Flue Gas Generation from Combustion
  • OSB, Belt Dryers, ORC, and Misc Secondary Users – Heating Thermal Oil 
  • Steam Turbines – Steam Boiler

Sigma Thermal is a leading provider of modern furnace systems fired by biomass. Our engineering experts provide logistics, troubleshooting, custom maintenance, and related equipment for world-leading industrial contractors. Learn more about the importance of fuel moisture, recommended fuel specifications, and proper inspections for biomass fuel systems.

Importance of Fuel Moisture

Fuel moisture is the water content present in the fuel, represented as a percentage. Moisture content matters in solid fuels because it influences burning behaviors. If the biomass has too much water moisture, it may not burn all the fuel or as easily and produces no energy or less useful heat energy relative to unit mass.  It can also cause excessive amounts of carbon monoxide which comes from incomplete combustion. If the biomass is too dry, it can reach ash fusion temperatures, foul the heat recovery equipment, or pose an explosion risk.

Because of these challenges, water content of the biomass must fall within a certain range to be most effective. Sigma Thermal’s reciprocating grate furnaces operate ideally with fuel moisture between 35% to 55%. It is important to size the grate floor of the furnace properly according to the maximum percentage of moisture the plant will be burning.

Equipment operators must also understand the roles of primary air zones, secondary air, and flue gas recirculation (FGR). Primary air is the amount of air used in the lower furnace to initiate combustion and controls the quantity and speed of fuel burned. Secondary air enables mixing of combustion gases and fresh air, completes the combustion, and allows the fuel to burn completely, which means combusting all of the carbon in the fuel making the combustion process more efficient.

The amount of secondary air you need depends on the firing rate and the moisture in the fuel. If the fuel is dry, more secondary air is needed to quench the combustion temperature and vice versa. If the fuel contains higher moisture, then less secondary air is needed. FGR is a technique that significantly reduces nitrogen oxide (NOx) emissions by recirculating flue gasses into the combustion chamber. This technique lowers flue gas temperature and oxygen content in the combustion mixture.

Moisture coming into the system must be consistent; operators should be aware of drastic fuel moisture swings, as these extreme changes can cause loss of control of the combustion inside the furnace and make the overall fuel usage go up while actual conversion of carbon-to-carbon dioxide goes down. This would mean the process is less efficient and not all of the fuel gets combusted.

Wet vs Dry Fuel

Wet Fuel Dry Fuel
Lower Heating Value Higher Heating Value
Must Burn More Mass Burn Less Mass
Need more Drying time Need Thicker Bed
Need Less Combustion Air & Secondary Air More Secondary Air or Recirc Air for Cooling
Lower Combustion Temperature and Potential for more CO  Watch for Glassing


Particle Size Consistency

Particle size consistency is another crucial factor in biomass combustion systems. For 100% bark fuel, particles should not exceed 6 inches, and particles in 90% bark content should be no more than 4 inches. The sizes vary further depending on different types of fuel content. Regardless of the type of biomass, fines—very small, fine particles—pose a variety of issues, including:

  • Ash carryover
  • Buildup and glassing
  • Bed becomes difficult to maintain
  • High flame temperatures

The wrong balance of primary and secondary air can also aggravate problems arising from particle size inconsistencies. For example, too much primary air can cause high velocity through the grates, which increases carryover of fines. Not enough primary air can result in unburned fuel being dumped off the grates and other production inefficiencies.

The presence of excess fines usually means moisture content is too low, usually under 40%. To resolve the issue of too many fines, operators should first decrease the flow of primary air and then increase secondary air or recirculate to the quench chamber. Under-fire air dampers in zones 1 and 2—the main drying chambers—should be reduced in 3-5% increments but should not dip lower than 10%. The fire line will slowly move down the grate. If the bed is thin, operators can then increase fuel feed rate.

Recommended Fuel Specifications

Sigma Thermal’s reciprocating grate furnaces are designed to burn biomass with high ash content, low heating value, and high moisture content. The design allows finite combustion control that minimizes emissions and uses fuels with unique fuel particle sizes, chemical compositions, and moisture content. Larger percentages of fines can cause high flame temperatures, large volumes of unburned carbon in flue gas streams, glassing, and difficulties maintaining bed thickness. 

In fuel analysis testing, there are important factors to consider, including: 

  • Heating value
  • Moisture content
  • Fuel particle size distribution
  • Ash content
  • Nitrogen content
  • Sulfur content
  • Carbon and hydrogen content
  • Ash fusion temperature

Different world regions have varying standards for biomass furnaces, so check your local regulations before implementing a system in your facility.

Furnace Inspection

Furnace inspection involves checking the condition of all essential components, such as grate bars, refractory, moving frame roller tracks, emergency stack, fans, and dampers. It also includes cleaning, testing, and lubricating any moving parts.

The following are signs of an improper operation: 

  • Cracked bars: These indicate rapid temperature changes and rapid contraction of the alloy steel, typically from a water
  • Warped bars: Warped bars result from high flame temperatures and oxygen concentrations.
  • Holes in bar nose: This damage is due to wear and high temperatures.
  • Refractory damage: Large amounts of glassed material in the upper furnace are a sign that the operating temperature in the furnace has been too high. In extreme cases, the refractory anchors can overheat and conduct heat back to the furnace casing, where the anchor is welded to the wall.    This will lead to refractory failure.

Biomass Fuel Systems from Sigma Thermal

Sigma Thermal provides complete biomass fuel system solutions. We understand what it takes to design, engineer, and manufacture efficient, high-performance systems. Our products include indirect process bath heaters, direct-fired process heaters, thermal fluid heating systems, electric process heaters, biomass-fired energy systems, and more. Contact us for more information, or request a quote to start your solution today.  

ASME and Pressure Vessel Design Considerations for Thermal Fluid Systems

Pressure vessels are containers used for holding gases, vapors, or liquids with pressures above or below the ambient pressure. Since the vessels operate under pressure in industrial applications, their fabrication must adhere to a strict code of construction, including the ASME code — also called the ASME Boiler & Pressure Vessel Code or BPVC.

ASME, short for the American Society of Mechanical Engineers, is one of the leading authorities that regulates pressure vessels and boilers. At Sigma Thermal, we uphold exceptional design and quality standards for all of our products, as evidenced by our adherence to ASME requirements.

Types of Pressure Vessels

There are two main types of pressure vessels used in thermal fluid systems:

  • Heat Exchangers: Heat exchangers enable heat transfer between fluids while preventing direct contact between them. Popular applications of these systems include energy, food, bioprocessing, and pharmaceutical industries. Most heat exchangers have a series of metal tubes where one product flows through while the other flows around the tubes allowing heat exchange to occur.
  • Fluid Heaters: Fluid heaters are closed vessels that facilitate the exchange of heat from an electrical or fuel-based source to the heat transfer fluid. These systems are used to heat liquids directly or indirectly.

At Sigma Thermal, we primarily use carbon and stainless steel to manufacture our pressure vessels. However, we can construct pressure vessels using other materials approved in the ASME Sect. II part D.

Design Considerations

Below are design aspects to consider when building a pressure vessel:

1. Pressure

Calculation of vessel specifications occurs around the design pressure, a value obtained from the maximum operating pressure expected during startups, emergency shutdowns, process abnormalities, and other upset conditions. Design pressure should be 5-10% above the maximum operating pressure. If the vessel has the likelihood of experiencing vacuum pressure, the design pressure must be a value that resists a full vacuum (-14.7 PSIG).

2. Temperature

The maximum allowable pressure depends on the temperature because material strength may be lower with increasing temperature, and material toughness may be lower in low temperatures. Pressure vessels should not operate at a temperature above the evaluated maximum allowable stress value. Therefore, the design temperature is always less than the minimum temperature and greater than the maximum operating temperature.

3. Corrosion allowance

Corrosion allowance requirements may vary by manufacturer or engineering specifier. Heat exchanger equipment specifically requires a small corrosion allowance because wall thickness affects the heat transfer rate.

4. Allowable stress

The maximum allowable stress of a pressure vessel is determined by ASME Section II part D. The stress values in ASME Section II part D account for potential deviations from the ideal construction and operation of the pressure vessel.

5. Joint efficiency

Another thing to consider in pressure vessel design is joint efficiency. Joint efficiency refers to the ratio of the strength of the welded plate to that of the unwelded plate. Joint efficiencies are determined by the ASME BPV Code Sec. VIII D.1.

Design Considerations for Pressure Vessels Related to ASME

Importance of ASME for safety and quality

ASME standards provide guidelines that help prevent accidents by making pressure vessels safer. Therefore, ASME certification is an accreditation that a piece of equipment adheres to the ASME code. Having a pressure vessel with an ASME stamp is an assurance that is proven to comply with the quality and safety standards of the Boiler and Pressure Vessel Code.

Requirements of ASME

ASME codes cover everything, including the design, creation, maintenance, and adjustments of pressurized equipment. Pressure vessels, heat exchangers use ASME code VIII-1, while hot water heaters and boilers use ASME code I. The design by rules codes give formula methods that work if the design falls clearly within the range of the code.

Thermal Fluid Heating Systems From Sigma Thermal

At Sigma Thermal, we have years of experience designing and manufacturing ASME code-compliant thermal fluid heating systems. We are proud to offer our customers with high-quality heating solutions they need to maintain seamless and efficient operations in their plants. Contact us today to learn more or request a quote and our representatives will get in touch with you.

Waste Heat Recovery Systems Using Thermal Fluid Systems (Thermal Oil Systems)

Waste heat recovery systems help manage, recover, and repurpose waste heat from various energy consuming systems in commercial, industrial, and municipal facilities. As machines run, processing systems prepare goods or products, they often put off heat as a waste product. That waste heat is typically either a result of the friction of moving parts or from the exhaust of various types of combustion equipment. While the heat of friction can be significant, waste heat from exhaust streams is typically the most practical to recover and utilize. Repurposing waste heat allows facilities to become more efficient, reduce thier fuel costs, and overall emissions to the environment.

How Do They Work?

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Waste Heat Recovery Systems Using Thermal Fluid Systems (Thermal Oil Systems)

One of the most common types of waste heat recovery systems is a closed-loop liquid phase system filled with a thermal fluid of some type: typically thermal oil or a water/glycol solution. Within a waste heat recovery coil located in the exhaust stack or in the exhaust gas ductwork, the circulated thermal fluid absorbs the waste heat from the exhaust stream. The heated fluid is then circulated to the the chosen waste heat consumer(s) within the closed-loop system, where it will offset the heat demand of the combustion system providing that particular system with its heat energy.

The challenge for the system designer is to match a heat energy consumer with a waste energy source. In order for the system to work the waste heat source must be hotter than the heat consumer with enough margin to drive the heat transfer from one system to the other. One of the biggest benefits of a closed loop liquid phase heat recovery system is it’s ability to connect multiple sources with multiple consumers that may not be physically close to one another. If, for example, if three exhaust stacks in one part of the plant collectively produce 450F exhaust, and a boiler feedwater system 200 yards away could utilize that waste heat to pre-heat the feedwater to 200F, the energy can be collected from the three sources, combined, and then circulated over to a feedwater heat exchange to heat the boiler feedwater. The cold thermal fluid simply recirculates from the heat exchanger outlet back to the waste heat sources, and the process repeats continuously.

Benefits of Using Waste Heat Recovery Systems

Manufacturing centers, processing facilities, and large buildings all benefit from the introduction of closed-loop waste heat recovery systems. Some of the core benefits include:

Cost Savings

Because the systems recover heat energy the facility has already generated, the facility can use that energy more intentionally instead of having to pay for heat that is rejected to the environment. Recovering energy can reduce operational costs by offsetting energy demand, and therefore fuel consumed, in gas or oil fired combustion equipment. Natural gas and/or diesel fuel costs can fluctuate and can be a significant portion of a plants total energy operating costs.

Waste heat boilers are often utlized as altneratives to closed loop liquid systems, but they can actually be less efficient to operate. Steam traps, blow down, and energy lost to condensate return cause inneffeciencies in the system that don’t exist in a closed loop liquid phase system. For those reasons, a closed loop liquid phase waste heat recovery system may allow you to utilize more of your waste heat and maximize your fuel cost offset.

In addition to fuel cost savings, there are frequently opportunities for government funding, tax credits, and other incentives at the federal, state, and local levels. These can be specific to waste heat recovery projects, or generalized incentives for sustainability and effeciency improvement initiatives. In many cases there are several incentives available at multiple levels that can all be utilized in tandem with one another: federal, state, and local. These incentive can significnat decrease the cost of installing a system, decreasing your investment payback period and maximizing your long term cost savings.

Waste Heat Recovery Systems From Sigma Thermal

At Sigma Thermal, we have the experience and expertise to design or select the right closed-loop waste heat recovery system for your facility’s needs. Our company is ISO 9001:2015-certified, and our signature process includes every step from initial system design to installation and complete project management. Contact us today to learn more or request a quote to start your project.

Pre-Engineered Thermal Fluid Systems vs. Custom Thermal Fluid Systems – How to Decide What You Need

Pre-Engineered Thermal Fluid Systems vs. Custom Thermal Fluid Systems – How to Decide What You Need 

Depending on the needs of a particular application, either a pre-engineered thermal fluid system or a custom-engineered thermal fluid system may be ideal. In this blog post, we’ll cover the differences between these two types of systems to help you determine which is best for your application. Both feature unique benefits, which is why it’s important to understand their differences when deciding which to use for your project.

Pre Engineered vs. Custom Thermal Fluid Heating System

Pros and Cons to Each Heating System

When selecting a thermal fluid system is critical, it’s important to:

  • Define the application’s unique performance requirements
  • Thoroughly assess the installation requirements and any specific facility needs
  • Compare different thermal system suppliers and learn about their products and how they approach projects for their customers
  • Determine how to properly install and operate the system in your facility

    light blue circle with an icon of a lightbulb with gears inside

Keep in mind that any mistake made in these areas may negatively impact your project. Whether you fail to assess the different heater designs or don’t take the time to compare suppliers, these and other mistakes are difficult to correct once you start installing your system. Fortunately, Sigma Thermal is here to provide plenty of guidance to ensure you make the right decisions regarding your thermal fluid system. 

One key decision you’ll need to make during system selection is whether to use a pre-engineered system, a custom-engineered system, or a combination of the two. To help you make this critical decision, the following are some of the pros and cons of each type of system.

Pre-Engineered Thermal Fluid Systems

The main advantages of pre-engineered thermal fluid systems include:

  • Reduced capital cost due to standard bill of materials
  • Faster delivery times because no engineering is required
  • Fully defined dimensions, drawings, and performance prior to purchase
  • Simplified projects and reduced site or plant engineering expenses due to the lack of drawings that require review, revisions, or approval

Custom Engineered Thermal Fluid Systems 

thermal fluid system

On the other hand, custom thermal fluid systems are often a better choice for more complex installations or processes. You may want to implement one of these systems if you plan to provide guidance on or specify certain factors such as:

Process Considerations

For custom engineered thermal fluid systems, you should provide information regarding the following process considerations:

  • System flow rates
  • Fuels, including biogas, waste gas, liquid fuels, off-spec fuels, variable fuel compositions, or dirty fuels
  • Strict requirements for emissions
  • Heat transfer fluids such as silicone-based fluids, molten salt, or ultra high-temp synthetic oils

Review and Approval of Drawings

In some cases, you may want to directly influence:

  • Connection location and orientation
  • Mechanical specifics such as configuration, materials, and paint
  • Certain system components if your company has required specific instruments, valves, pumps, or other buy-out equipment.
  • Factory interconnection and skid mounting for various components, such as mounting an expansion tank, pump skid, heater, and drain tank on one skid frame
  • Custom secondary loop skids for auxiliaries such as indirect steam generators, temperature control units, control valves, and process coolers

A Hybrid Approach – Mixing and Matching Pre-Engineered and Custom Components

At Sigma Thermal, we offer a modular approach to pre-engineered thermal fluid systems, which facilitates the combination of both pre-engineered and custom-engineered systems. Using this hybrid approach, you can use pre-engineered components for areas that don’t require customization. At the same time, you can customize the specific areas over which you want more control. If, for example, you can use a pre-engineered heater and pump skid design, but you have a large system volume and need a large custom expansion and/or drain tank, you could take a hybrid approach to the system design.

Using a hybrid approach to system selection, you can save more time and cost while simplifying your systems. Additionally, you’ll be able to easily adapt systems for specific project requirements. 

Process Heating Systems from Sigma Thermal

The experienced professionals at Sigma Thermal specialize in pre-engineered and custom-engineered thermal fluid heating systems. Our equipment allows for optimal installation, operation, and fulfillment. If you require pre-engineered thermal fluid systems, we offer both our HC2 gas-fired heaters and SHOTS electric heaters. We can also work with you to design a completely custom solution if you want to specify certain components and design elements.

For additional information about our thermal fluid systems, contact us today with any questions or concerns. We can also help you find the ideal solution when you request a quote from us.

Biomass Energy Systems

With decades of global experience in the energy industry, Sigma Thermal knows how to provide robust industrial solutions designed and engineered to meet even the most demanding client specifications. Our biomass fired energy systems provide minimal emissions and finite combustion control, all while accepting a wide range of waste fuels with varying sizes, chemical compositions, and moisture content. 

Sigma Thermal’s reciprocating grate furnace allows for the efficient, complete combustion of waste materials with high ash, high moisture content and low heating value. Keep reading for more information about how these systems work as well as the different energy delivery systems that we offer.

biomass systemHow Does a Biomass System Work?

Biomass energy systems all generally consist of three components—fuel handling, ash handling, a furnace, and a control system. Biomass equipment employs these four systems to convert raw organic material into fuel in a series of steps:

  1. Fuel preparation. Before biomass equipment can effectively handle raw material, it must process and prepare the biomass used for fuel production. Solid, liquid, and gas biomass all require different processing techniques to ensure consistency and efficiency, such as drying, screening, grinding, and separating. 
  2. Fuel intake and handling. The fuel handling system includes the initial feed and an intermediate storage bin. Fuel moves from the feed to the storage bin, where specialized equipment measures it out and subsequently distributes it into the furnace and onto the reciprocating grate. 
  3. Material combustion. Biomass energy systems heat and combust the prepared materials with process heating equipment, achieving drying and gasification by creating hot gases that will move along through the next steps of the process.
  4. Gas capture. Newly created hot gases move through two chambers, the upper combustion chamber and the secondary combustion chamber, which capture and store the gases for future use. Burning biomass for energy generates carbon dioxide as a byproduct, so proper gas capture and removal is crucial to keeping carbon emissions low. 
  5. Ash handling. Lastly, the ash handling system captures the grate ash byproduct, which is dropped from ash hoppers to the ash conveyor. This conveyor is submerged underwater for improved ash management and transports the ash outside of the system where it can be collected and disposed of.

Energy Delivery Systems & Equipment for Enhanced Performance

biomass energy system

Bio energy systems provide several benefits over traditional energy generation solutions, including enhanced performance, efficiency, and more. Biomass fired energy systems are a source of renewable energy, which makes them eligible for a host of benefits like Renewables Energy Certificates (RECs) for each MWh of power created or even process heat RECs. . Not only is biomass renewable, but it also boasts carbon savings that have both environmental and financial benefits, especially in the industrial sector. 

Biomass energy delivery systems are also incredibly efficient regarding total cost and material usage.  Advanced gasification technology like the processes described above can have up to 80-90% thermal efficiency, which drastically reduces input costs and expands profit margins. Operational fuel cost savings and reduced fuel price volatility are other key benefits of biomass energy  since organic waste energy sources are much more available and abundant than nonrenewable sources of fuel. Finally, biomass fired energy is considered an efficient combined heat and power (CHP) system as it simultaneously generates both heat and electricity.

At Sigma Thermal, we offer several different types of energy delivery systems: 

  • Biomass Fired Hot Gas Generators. These systems cleanly generate hot gas for direct heating requirements.
  • Biomass Fired Thermal Fluid Heaters. Built for indirect heating, these systems use thermal oil or fluid. 
  • Biomass Fired Steam Boilers. Steam boilers generate steam directly from wood-fired furnaces. 
  • Thermal Oil to Steam Generation. These systems use a thermal oil heat exchanger to generate low-pressure steam.

Let Our Process Heating Experts Assist You

Partner with our team of industry veterans to unlock the benefits of bio energy systems. From highly engineered process heating equipment to standard packaged heaters, Sigma Thermal’s dedicated experts know how to find the perfect biomass energy systems for your individual needs. We believe that successful energy delivery systems require not only advanced industry knowledge and applied field experience but also exceptional customer service every step of the way. These three keys to success bind our team together and provide a powerful framework for consistently crafting exceptional biomass equipment and processes. 

For more information about our biomass energy systems, contact us or request a quote today. 

5 Industrial Applications for Direct Fired Heaters (API 560 & Non API)

Rendering Radiant Convective Heater

Direct fired heaters use one of three possible methods for heat transfer:

  • Radiant-convective heat
  • Radiant heat
  • Convection heat

Radiant–convective style direct fired heaters are a popular style of heater and are used more often than not. These heaters utilize a bare tube radiant zone in combination with a bare / finned convection section. The most typical configurations are vertical cylindrical, A-frame, and cabin style. Sigma Thermal offers all types of direct fired radiant–convective heater designs including API 560 compliant systems.

Convection style direct fired heaters provide the benefits of a direct-fired heater, but eliminates some of the drawbacks associated with radiant heat transfer. In specific temperature-sensitive applications, radiant heat transfer can be undesirable, as radiant heat transfer tends to be more harsh and unevenly distributed around the coil surface.  To minimize the impact effect of the radiant heat transfer to the process coil, Sigma Thermal’s convection style direct fired heaters are designed to utilize a separate combustion chamber and flue gas recirculation. With this design, the combustion chamber temperatures are reduced to 1,400°F. 

API 560 Heaters vs Non API Heaters

Convection or radiant-convective direct-fired heaters can be designed using API RP 560 guidelines and practices created for fired heaters used for general refinery service. These guidelines are established by the American Petroleum Institute (API). Typically if the application involves the direct heating of crude oil, API560/ISO 13705 standard design guidelines will apply.  For almost all other applications (i.e. regeneration gas, thermal oil heating, water, glycol, and temperature gases), more optimal designs are available that lower the capital and installed cost, footprint, fabrication, installation time, and freight cost. A practical strategy to use to obtain an API-style design, without incurring unnecessary costs for irrelevant design elements (that are not useful for some applications), is to use API 560 as a guideline with key exceptions. 

5 Applications for Direct Fired Heaters

Regeneration Gas Heating

Regeneration gas heaters remove unwanted moisture from high-temperature process streams, such as natural gas. The wet gas runs through a desiccant-style or molecular sieve bed drying system that captures moisture from the fluid stream, leaving a purer form of the gas that is ready for additional processing and storage. The regeneration gas heater then dries the desiccant so it can be reused. Regeneration gas heating systems are also common in air separation facilities, where water and carbon dioxide are removed from the surrounding air, allowing air to be cooled into a liquid.

Process Air Heating

Process air heating, in combustion turbine systems, improves combustion ability and the reliability of the  system. Process air heating also  temperature control for process air, either at specific locations or facility-wide. Common examples of this type of heater include water-glycol systems and thermal oil systems. Robust, reliable, and long-lasting, process air heating systems see frequent use for precision temperature control in commercial food processing ovens and feeding heated air into industrial process consumers.

Viscosity Reduction

Heating heavy liquids reduces their viscosity, reducing the level of power required to pump and transport them in process systems and pipelines. This process has become common to facilitate easier transportation of crude oil and its various derivatives. Overheating crude oil will damage it and reduce its quality, making precision control essential during viscosity reduction processes. 

Skid-mounted indirect heating systems are often used near oil wells in remote locations, offering precision temperature control by heating oil through a heating medium. Some operations also use direct oil heating, which can be managed properly using low watt-density electric heating elements and convection-only style direct-fired heaters.

Inline Liquid or Gas Heating

In opposition to tank heaters or full process system heaters, inline heaters provide heat for fluids at a specific point in a process, making the fluid ready for its intended purpose. By only heating the gas or liquid that’s immediately needed, users significantly reduce energy consumption and associated expenses. Inline heaters may be either direct-fired or electric, depending on their intended application.

 Thermal Oil Heating

Thermal oil heating systems provide indirect heating using thermal oil as a heat transfer medium. Thermal oil provides an ideal medium for high-temperature operation, facilitating temperatures up to 600°F with organic oils, or up to 800°F with synthetic oils. Thermal oil heating has broad applications, including reboilers, tank heating, press heating, and numerous other industrial use cases. Thermal oil heating systems work well for processes that require high-temperature operation and precision control.

Sigma Thermal Solutions

The above guide demonstrates the impressive versatility of direct fired heating systems. Whether you need to design a unit to suit one of the applications we’ve discussed here or an entirely new purpose, Sigma Thermal Solutions can produce direct fired heaters customized to your demands. Our business serves customers from an array of industries, including aerospace, agriculture, automotive manufacturing, chemical processing, food processing, gas production, mining, oil processing, power generation, paper manufacturing, wastewater processing, and more.

Our signature Sigma Thermal convection-style, API 560, and non-API radiant-convective heaters range from 1MM to 80 MM BTU per hour. To learn more about ordering direct fired heaters, contact an expert from Sigma Thermal Solutions today. 

Sigma Thermal Solutions was founded on the belief there are three keys to success: exceptional engineering knowledge, practical field experience, and honest customer service. We look forward to helping you fulfill all your company’s heating needs!

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