Saving Operating Costs by Recycling Hydrogen
An estimated $64 billion worth of hydrogen is used worldwide in the production of metals, electronics, thin-film solar panels, edible oil processing and a variety of other applications.
Much of this hydrogen is used to create a hydrogen-rich atmosphere in operations to treat materials and products, such as bright annealing of stainless steel and float glass production. Once this hydrogen is used in the industrial process, it is usually then vented or flared.
Skyre has developed technology that allows manufacturers to save money by recovering hydrogen used as an atmosphere. The H2RENEW™ system (Fig. 1) uses an electrochemical process that is derived from fuel-cell technology. Fuel cells have traditionally been used by NASA and (more recently) Toyota, Hyundai, Honda and Mercedes as a way to convert the chemical energy contained in hydrogen into electrical energy.
The system uses a derivative of fuel cells to separate hydrogen from a gas stream containing other constituents. A version of this system has been under development with NASA funding for large-scale separation of hydrogen and helium gas mixtures used in space rocket-engine test operations.
H2RENEW (the system) enables heat treaters and metals manufacturers to efficiently recycle hydrogen, thereby reducing operating costs, site emissions and the carbon footprint associated with traditional hydrogen production and delivery (Fig. 2). The system can typically recover up to 75-85% of the hydrogen from industrial waste streams in a cost-effective and reliable manner. Since the cost savings of industrial gas recycling depends on the value of the recovered gas in relation to the energy consumption of the system, it is designed to minimize electrical power requirements, resulting in maximum operating savings for the hydrogen user.
Saving Typically Vented or Flared Hydrogen
Given the increasing cost and tight supply of delivered hydrogen and the competitive economic climate, the economics of hydrogen recycling can be very compelling.
Hydrogen cost is a substantial portion of operating expenses in heat-treating processes, and it is often cited as the second highest non-labor operating cost next to energy for processes that use high-concentration (75-100%) hydrogen atmospheres. Depending on how the hydrogen is produced and distributed (e.g., liquid or gaseous) and the level of purity required, the cost of delivered hydrogen is around $1.15 or greater per 100 cubic feet (CCF).
Hydrogen consumption rates vary from one industrial user to the next and are process-dependent, ranging from hundreds of CCF per day up to 100,000 CCF per day. Skyre’s H2RENEW has a rated output of 423 CCF per day of recycled hydrogen gas, which is typical for certain heat-treating processes such as stainless steel bright-annealing furnaces.
Assuming optimal system operating conditions of 24/7 operations and an 80% hydrogen-recovery rate from the furnace, hydrogen recycling savings can provide a system payback in less than two years, depending on factors such as the cost of delivered hydrogen and electricity to the site. Multiple systems can be deployed to address larger hydrogen quantities.
Electrochemical Hydrogen Recovery, Recycle
The electrochemical hydrogen recycling system developed by Skyre is significantly different than the more-conventional approach that utilizes mechanical compressors, a process known as pressure-swing adsorption (PSA). PSA requires expensive compression of the entire gas stream, including non-hydrogen gases such as nitrogen, in order to process and purify the hydrogen.
In the electrochemical hydrogen recovery system, a hydrogen waste stream is fed to a “stack” of electrochemical cells. An electrical potential is applied to the cell stack, causing the splitting of hydrogen in the waste-gas stream into its constituent parts – hydrogen atoms (the smallest element on the periodic chart).
The hydrogen atoms cross through a special membrane, leaving larger gas molecules and other impurities behind. The hydrogen atoms then re-combine on the hydrogen product side of the membrane into pure hydrogen, which is returned to the industrial process (Fig. 3). H2RENEW recycles pure hydrogen back to the furnace or other process. The waste gas that is filtered out is then vented.
This electrochemical approach and proprietary control design allow the hydrogen recycling system to extract hydrogen from industrial-process waste streams without impacting the furnace’s atmosphere or internal pressure. As a result, H2RENEW can be used with many types of furnaces that operate at atmospheric or near-atmospheric pressures.
The system is integrated into the existing furnace exhaust and hydrogen supply systems, thereby eliminating the potential of upsetting the heat-treating process. The system is designed for remote operation, monitoring and reporting of certain specific maintenance activities, minimizing required interaction by the end user in the operation of the device.
Skyre technology also inherently compresses the hydrogen without the need of a mechanical compressor. Pressures as high as hundreds of psi can be generated with little increase in the power required. Skyre is developing a version of the system that can compress to thousands of psi.
The system can handle a number of gaseous impurities commonly found in heat-treating furnace gas exhaust. Gases such as carbon dioxide, ammonia, nitrogen, sulfides, carbon monoxide and water vapor are typical in waste streams of annealing and brazing operations. Most of these gases are generated from residual protective surface coatings (oils) or reactions with secondary gases such as nitrogen.
The impurities are handled by a number of proprietary methods within the system. The final gas cleanup and drying stages are dependent on the customer’s process requirements. H2RENEW is capable of delivering hydrogen at a purity of up to 99.99% or higher and in many cases with dew points well below -76°C (-105°F), often exceeding the delivered hydrogen supply quality.
The typical operating characteristics of the system are presented in Table 1.
Reduce Capital and Maintenance Costs
H2RENEW systems will be commercially available for purchase or under a leasing model in 2019. Under the leasing option, a monthly payment allows customers to pay for recycled hydrogen and includes system maintenance costs. The customer pays for utilities (mainly electricity to operate the system) and site preparation for installation. Due to low power consumption, electricity costs are around $0.25/ CCF of hydrogen processed, or less than a quarter of the cost of delivered hydrogen gas from an industrial gas company. Under the lease model, savings begin immediately after the installation of the H2RENEW system.
For more information: Contact Trent Molter, Ph.D., President & CEO, (firstname.lastname@example.org) or Nancy Selman, VP of Business Development (email@example.com); Skyre, Inc., 111 Roberts Street, Suite J, East Hartford, CT 06108; tel: 860-652-9690; e-mail: firstname.lastname@example.org, web: www.skyre-inc.com.