Energy Savings and Improved Uniformity with Airtorch®

Energy: When one includes the social cost of CO2 production the cost of 1KWh of electric or combustion energy starts converging. For example, if the social cost of making CO2 is $50/ton then the price of 1 KWh of electric or similar energy from the combustion of natural gas is not too different. If the efficiency of Airtorch devices is even 25% better than combustion heat exchangers then the operational cost of the electric Airtorch is lower than the combustion heat exchanger devices.

There are other cost benefits. The pressure drops for electric Airtorch devices is lower than heat-exchanger devices. For a 2000 SCFM flow, when you save ~5 psi in pressure drop, it is equivalent to about 30 KW in power savings. This is almost a savings of $25,000 per year assuming a price of 10US¢ per KWhr.

MHI Airtorch® models are designed with thermal energy loss reduction, and pressure energy loss reduction features. MHI Airtorch® models offer a high-temperature input even to 500°C, particularly useful for Duct-Heaters that are used in ovens or for replacing natural gas heating. Did you know that converting from a 16MW combustion heater to Electric Airtorch can save over 30% in energy alone and several millions of dollars in climate costs?

For the best energy savings compare the following:

The efficiency of thermal transfer. What is the ratio of the real efficiency to theoretical? Depending on the model, the MHI Airtorch® systems offer greater than 95% efficiency.
Pressure drop. Is it the lowest for the Airtorch®? Some large MHI models allow a pressure drop at 1000C of as low as 0.1 psi.
Control systems. Does your control have a good turn-down ratio and intelligent cascade electronics? MHI uses the best SCRs and electronics that are industry standards.
Materials and Design. What is the best temperature rating of the Airtorch®. A higher temperature rated Airtorch® will perform better even at a lower temperature. Depending on the model MHI Airtorch® systems offer 1200°C temperatures.
Improvement of over 30% in energy efficiency with the compared to …..(click here for case studies)

Temperature	Lower Power (1-12 kW)	High Power (36-400 kW)
600-1000°C	LTA, VTA, MTA925	MVTA-900-(THN/DNA) Models, SH
900-1000°C	(Custom), DNA	MVTA-1000-(THN/DNA) Models, SH
1000-1200°C	DNA, DPF, SH	(Custom)
High Pressure Enclosures	Up to 1200°C	(Custom)

Resources

Airtorch® System Introduction

Please use the 5 step process for selection. First, choose the maximum rated exit temperature of the Airtorch®. If below 900°C , please choose TA models e.g. VTA and MTA models. If above 925°C please choose the MVTA or DPF models or please contact MHI.

Sometimes to use the lowest power users work through several cycles in a recuperator mode. The SH models can accept inlet gas temperatures up to 800°C. Please contact MHI for details.

The Airtorch® convective system uses a special class of elements to heat the ambient air and direct that heated air towards a surface or into a chamber. Depending on the model, the Airtorch® system can achieve temperatures ranging from room temperature to 1100-1200°C (~2200°F) with infinitely variable volume flow rates and no harmful emissions, providing a beneficial new method of heating with modern controls.

MHI Airtorch® applications are in drying electrical varnish, weld pre-heating, die heating, plastic softening prior to forming, drying motor parts, removing moisture, expansion fitting, combustion, simulation preheating and heating molds, curing, prosthetics, heat shrinking, compression molding, flock setting, curing catalysts drying slurries, freeze-drying, improving ink print finish, finishing mirror drying, latex, heating adhesives, and general heating of chambers as shown below. Add to chambers for powder, and liquid finishing. Add to continuous furnaces for wood conditioning, metal finishing, and forming. Very small but finite temperature drop is experienced when directing Airtorch® flow with insulated piping because of the high velocity.

For impingement type of applications the DPF’s offer very superior value.
A good rule of thumb for augmenting uniformity in an existing furnace with an Airtorch® add-on is to choose a Airtorch® power with at least 30% of the original furnace power. This may not be enough if a temperature increase is also sought.
When planning to extend the Airtorch® exit piping, please note that well-insulated pipes will drop the temperature only very little as the exit velocity is m/s. Please contact MHI when required. A helpful but very rough rule of thumb may be about 50°C-100^°C/m drop for good internal pipe insulation. Good pipe insulation is specific to the insulation and whether the pipe is internally or externally insulated. The MHI industry standard is about a 1-2″ thick insulation.

The use of Airtorch® products may be classified into 3 major categories schematically drawn below

Introduction to Airtorch® | AirtorchIn Line® Applications | Calculating Power vs Flow Rate | Easy Design Criterion

Direct Impingement	Gas Preheating	Retrofit for Enhancement
Direct Impingement. High temperature direct heating, surface ignition, surface processing, chemical processing or direct die heating. .	Gas Preheating. Process Gas Heating. Preheat inert gases for a variety of applications including in-line with pressure. Call MHI for more information. Sealed models like the MTA and MVTA are available.	Retrofit/Upgrading. Use the Airtorch® with existing furnace technology infra-red, gas, radiant to improve uniformity and furnace efficiency.

With its variable volume flow rate and power adjustability, the Airtorch™ can be set up to perform at any condition of flow temperature under the curve. Such features offer the user maximum flexibility when applying the Airtorch™ technology to your specific heating application. Easy to use selection and design page.

Continuous Ovens.

Example of Use to Augment an Existing Furnace Installations for Improved Power and Uniformity.

An example of a 4kW Airtorch® augmentation application is schematically shown below. In this application, many complex-shaped rods are to be heated uniformly. The heat-treater reported that the rods were not uniformly heated in his existing radiant heat furnace. MHI proposed an add-on to his existing furnace with a system of air torches which then greatly impacted the uniformity and reduced the total energy consumed. More Green Installation and more Profits to the user. Improve oven performances and eliminate bad emissions.

Let MHI calculate for you.

A uniform surface heating retrofit example and continuous oven example is illustrated below.

As a rule of thumb an Airtorch power of 0.3 the furnace power is employed when designing for better uniformity.

MHI Airtorch® Supplemental Heating Proposal

Scope: Supplement existing electrodes by applying Airtorch convective heating to increase performance and life

Solution: By supplementing the existing electrodes with the Airtorch® and blankets, the watt density is increased on the mold thus reducing the workload of the existing electrodes which should improve performance and life. Other results include an increase of uniformity across the mold surface. Call MHI for more information.

1 Heating: Create a convective cavity around the assembly using two 4kW Airtorch® units. Fixture Airtorch units behind mold and electrodes at angles to create air movement. This should improve the overall heating of the mold.

2 Insulation: The assembly is surrounded by refractory blankets (all 5 sides) to retain as much heat inside as possible. Blankets can be supplied by MHI at customer’s request.

Simple Just add a duct Heater