Novel Possibilities for High Temperature Gas Heat Exchanger Design

Novel Possibilities for High Temperature Gas Heat Exchanger Design

Introduction

Several businesses demand heat exchange between gas and gas or liquid and gas, when both gases and liquids are corrosive and, in some cases, at high temperatures. For example, you can find them in fuel cells, gas heating, waste energy recovery, and other applications.

In majority of those applications, the temperature on the hot side is in the 600° to 900° C range, compared to the gas or liquid on the cold side. At those temperatures, the gases become highly corrosive, and we could end up with a serious corrosion problem in our process. Furthermore, several of the applications start with a corrosive liquid, such as deionized water, distilled water, KOH, and others.

Because of the challenges outlined above, the thermal and mechanical design of a robust and effective heat exchanger for gas to liquid is a big task.

Solutions that are currently available

There are numerous types of heat exchangers that can deal with extreme temperatures, corrosiveness, and varying work pressure.

BPHE - Brazed Plate Heat Exchanger

This type of heat exchanger can deal with high temperatures and corrosiveness. Yet, there are numerous downsides of adopting BPHE:

Special materials, as well as brazing materials, are required.

By employing the BPHE, there is a pressure drop. To accomplish the needed modest pressure drop, we must plan to use numerous BPHEs in simultaneously, which increases the volume and thus the expense of the BPHE.

As the temperature rises, so does the allowed operating pressure for BPHE. At 750° C, you cannot work with pressures more than 2 Bars.

Shell and Tube Heat Exchangers

Straight tubes or U shaped tubes are the two possibilities for shell and tube heat exchangers. When working with high temperatures and corrosive materials, the shell & tube heat exchanger can obtain the desired results. They have an edge over the BPHE in terms of working under high stress, but they still have numerous disadvantages:

Because the thermal efficacy is lower, a bigger heat transfer surface is required, increasing the volume of the heat exchanger and hence the cost of one.

The manufacturing process involves several welds, which may cause dependability issues over time.

The production process involves several welds, which may provide a dependability risk over time.

Fin and Tube Heat Exchangers

Currently, we can design and build fin and tube heat exchangers for high temperature and corrosive liquids and gases. Furthermore, we may use them for high working pressure applications, both gas and liquid (up to 550 Bars).

When compared to both BPHE and shell and tube heat exchangers, fin and tube heat exchangers have several advantages:

The fin and tube heat exchanger can withstand extremely high working pressures of up to 550 Bars.

The fin and tube heat exchanger has a very low pressure drop of 0.1 Pascal.

The fin and tube heat exchanger (both fin and tubes) can be made from a variety of stainless steels. For example, 316, 310, Inconel, SMO, Duplex, and others. As a result, we can tailor the material to the desired temperature and corrosiveness of the gas and/or liquid.

When using fin and tube heat exchangers, the heat exchange surface area is bigger, providing a very good thermal solution.

The fin and tube heat exchanger transfers heat under corrosive circumstances and at temperatures up to 1250° C.

The mechanical attachment of the fin to the tube gives greater lifespan and reliability.

The production procedure for the fin and tube heat exchanger is less expensive than that of the other heat exchangers described, allowing for a highly reasonable price.

Designing the heat exchanger based on customer size requirements is simple and inexpensive.

Previously, one of the challenges to adopting the fin and tube heat exchanger for these types of industrial applications was the inability to produce a thermal design. This barrier has been removed as a result of recent improvements, and we can now supply thermal and mechanical designs for the majority of operating conditions (corrosiveness, high temperature, and pressure).

Summary

The issue of designing and manufacturing heat exchangers for applications using corrosive gases or corrosive liquids at high temperatures is becoming more significant as energy prices rise and demand for green energy such as fuel cells, natural gas consumption, waste energy recovery, and others grows.

We can perform heat exchange in practically any temperature and for most forms of corrosive liquids and gases by combining fin and tube technology with various types of stainless steel.

Vrcoolertech specializes in the design and manufacture of bespoke heat exchangers for the following industries: fuel cells, gas applications, waste energy recovery, high temperatures, and corrosive gases and liquids.

Please do not hesitate to contact us if you have any inquiries or encounter any problems.