Heat Exchange Reforming
In steam methane reforming applications, the reforming furnace is a large piece of equipment and it has flue gas heat losses that have to be minimized through a complex waste heat recovery section. Therefore, there have been several alternative configurations developed that utilize a “heat exchange reformer” concept. These alternative approaches can be used to provide a reduced footprint and/or an alternative approach for debottlenecking existing facilities.
Johnson Matthey Gas Heated Reformer
The gas-heated reformer (GHR) is a compact, refractory-lined vertical vessel containing vertically-supported tubes filled with catalyst. Counter-current heat exchange with a product syngas from an upstream reformer (SMR or ATR) provides the heat for the endothermic reforming reaction.
A pre-heated mixture of natural gas and steam enters the GHR at the top. Passing downwards through the catalyst-filled tubes, the feedstock partially reforms, producing a mixture of syngas (CO, CO2 & H2), unreacted methane and steam.
Since the heat transfer within the GHR is convective rather than radiative, the required footprint of the GHR is much smaller than a conventional steam methane reformer.
Haldor Topsoe Convection Reformer (HTCR)
The HTCR varies from the other heat exchange reformers as it can be used as stand-alone reforming unit. The HTCR combusts fuel directly within its design rather than using an outside stream to provide the heat requirements. The HTCR reactor consists of a vertical, refractory lined vessel, containing the tube bundle with several bayonet tubes. Each bayonet tube is surrounded by a flue gas guiding tube, and the heat flux is adjusted by a proprietary flue gas control device. Below the vertical section is a horizontal combustion chamber containing the burner. A main characteristic of the HTCR is that it absorbs about 80% of the heat release of the burner into the process. This compares to about 50% in a traditional fired tubular reformer with radiant heat transfer. The HTCR is compact and can therefore be provided on a skid-mounted basis.
The KRES is another heat exchange reforming reactor system that is used in unison with an existing SMR or ATR. The KRES is a vertical, refractory-lined, vessel that utilizes a water jacket. The KRES utilizes the product syngas stream exiting a primary reformer as its heat source to perform additional reforming. The feed and steam mixture enter the KRES at the top of the vessel and then it enters the catalyst filled tubes. The primary reformer syngas enters the vessel toward the bottom of the vessel and it flows upward and exits the KRES just below the top of the catalyst tubes. The KRES has been typically utilized for plant revamps where the reforming can be debottlenecked by up to 30%.
Air Products Enhanced Heat Transfer Reformer (EHTR)
The EHTR is essentially a heat exchanger that utilizes an upstream reformer syngas stream to provide the heat to perform additional reforming in catalyst filled tubes within the exchanger.
The EHTR is a vertical refractory-lined piece of equipment. The syngas stream from an existing reformer enters the top of the EHTR and flows downward through the tube bank and exits the EHTR toward the bottom after being combined with the additional syngas produced within the EHTR. The additional feed and steam enter the bottom of the EHTR and travel upward through the tubes and then back toward the bottom of the EHTR where the syngas is collected and then exits the EHTR.