William E. Liss

Using Numerical Simulation Tools to Assist the Development of a High Stability Low NOx Industrial Burner

To achieve ultra low NOx emission as well as high efficiency for industrial burners, premixed or partial premixed combustion technology is becoming more attractive than flue gas recirculation approaches, which tend to cause low combustion stability and low energy use efficiency. A well designed premixed combustion system can achieve lower and more uniform combustion zone temperatures thus resulting in reduced thermal NOx generation. A multi-stage premixed industrial scale gas burner with oil backup capability has been developed by the authors, with the assistance from CFD simulation. By using staged combustion, combustion heat release is better distributed into a larger volume to avoid high peak flame temperature zone to occur. By using a primary stage combustion with a fuel rich flame and a hot high emissive metallic chamber wall, the burner combustion stability is ensured. The CFD tool was used to simulate and optimize the whole burner combustion and heat transfer process, with proper fluid dynamics and reaction models for this full size burner development. With the CFD efforts, the final burner design can achieve a very uniform temperature field, with peak flame temperatures below 1650°C, therefore thermal NOx generation is minimized. The numerical results show that this new gas-fired burner can achieve high efficiency with low NOx emission. Using the CFD simulation tool, the burner global parameters, such as its peak flame temperatures, its exhaust flue gas temperatures, and its NOx concentration distributions, have been studied under different burner operation conditions, e.g., different excess air levels, different burner firing rates, and different mixture inlet temperatures. The CFD simulation tool has been proved a good assistance for the burner design, as well as the burner performance optimization.Copyright

An Innovative Technology Development for Building Humidification and Energy Efficiency

Currently, the most widely used residential humidification technologies are forced air furnace mounted bypass wetted media, spray mist, and steam humidifiers. They all use city water as a water source and require furnace heat or electricity to evaporate the water. Mineral deposition, white dust, and microbial growth problems are associated with these humidifiers. For commercial building humidification, de-mineralized water is typically used for humidification equipment like steam heat exchangers, fogging system, electric, and ultrasonic humidifiers. Therefore, in addition to the energy consumption for the water evaporation, energy is also needed to produce the high quality de-mineralized water.An innovative technology called Transport Membrane Humidifier (TMH), has been developed by the authors to humidify home air without external water and energy consumption, while simultaneously recovering waste heat from the home furnace flue gas to enhance the furnace efficiency. The TMH technology is based on our previous extensive study on nanoporous membrane water vapor separation from combustion flue gas, and a design for residential home humidification application was first developed. It has been proved by both laboratory prototype testing for long term performance, and by two occupied single family home demonstrations for two heating seasons. The technology can provide whole house humidification without any external water consumption, and at the same time boost the furnace efficiency. Compared with conventional furnace mounted humidifiers, the TMH does not need additional furnace fuel for the water evaporation, no white dust in the home, no microbial growth since there is no standing water involved. Therefore, it is an innovative technology that can provide energy saving, water saving and healthy building humidification.© 2012 ASME

Water Reclamation From High Moisture Content Waste Heat Streams

A new waste heat and water recovery technology based on a nanoporous ceramic membrane water vapor separation mechanism was developed, to extract the water vapor and its latent heat from low temperature high moisture content waste gas streams. For the water reclamation process, water vapor condenses inside the membrane pores and passes through to the permeate side which is in direct contact with a low-temperature water stream. Contaminants such as CO2 , O2 , NOx, and SO2 are inhibited from passing through the membrane by its high selectivity. The recovered water is of high quality and mineral free, therefore can be used as supplemental makeup water for almost all industrial processes. The membrane based technology has been first developed and demonstrated for industrial boiler flue gas heat and water recovery. Now it is being developed for wider applications, from residential humidification, commercial laundry, biomass production to utility boilers. The increased application areas will greatly enhance waste heat and water recovery potentials worldwide, to save both energy and water, and benefit the global environment. In this paper, the technology development process, and several demonstrations for different applications are discussed in details.© 2011 ASME

Advanced Components for PEMFC Stacks

Currently, fuel cell cost reduction and long life are major priorities for fuel cells to be commercially successful for vehicle, stationary, or portable power applications. In the last five years, Gas Technology Institute (GTI) has formulated and developed a low cost, long lifetime, high conductivity proton exchange membrane (PEM) yielding state-of-the-art fuel cell performance. Additionally, a non-coated, corrosion-resistant metal alloy bipolar separator plate has been patented and tested for both hydrogen-fueled and direct methanol fueled PEMFC applications. Tests in fuel cells plus out-of-cell ASTM corrosion tests have shown very low corrosion rates under fuel cell operating conditions. Metal alloy separator plates have run for over 23,000 hours in cells with corrosion rates an order of magnitude less than the DOE target of 1 μA/cm2 . GTI’s fuel cell polymer membrane research focused on three criteria: (1) use of low cost materials; (2) polymer structures stable under fuel cell operating conditions; and (3) performance equal or better than current Nafion membrane electrode assemblies (MEAs). Fluorine-containing polymers were eliminated due to cost issues, environmental factors, and the negative influence fluorine ion loss has on metallic separator plates. The polymer membrane material was synthesized and cast into films, then fabricated into MEAs. The cost of the membrane (raw materials plus film processing materials) is estimated to be less than

Hydrate Formation in Natural Gas Fuel Applications

10/m2 — or less than 10% of available technology. A variety of out-of-cell testing showed the membrane has sufficient strength, flexibility, and conductivity to serve as an ion conducting membrane for fuel cells. A series of 60 cm2 active area single cells and short stacks were operated over a wide range of fuel cell conditions, showing state-of-the-art MEA performance with long-term polymer stability.Copyright

Coal power plant flue gas waste heat and water recovery

The issue of natural gas moisture content and the potential for hydrate formation has been largely a topic of the gas processing and gas transmission industries. Therefore, research in this area has focused on temperature and pressure conditions likely to exist in underground formations, wells, and pipelines, with less research on high pressures and the severe subzero temperatures encountered by natural gas vehicle (NGV) components. In the operation of natural gas vehicles, NGV equipment is subjected to high on-board storage pressures (up to 3600 psia) and cold ambient temperatures (as low as -40°F). The Joule-Thompson effect can produce even lower temperatures when the on-board storage pressure is reduced to the fuel management system pressure of 15 to 300 psig. At these temperatures and pressures, moisture in the gas can freeze or form hydrates which may obstruct on-board components such as check valves, fuel lines, pressure regulators, and injectors. These “freeze-ups” have been observed by such organizations as General Motors during recent cold weather testing of developmental stage vehicles. The objective of this study is to address concerns about “freeze-ups” of NGVs through a series of laboratory tests. The primary focus of these experiments is to investigate the effect of natural gas moisture content on the operation of the vehicle, in particular, the natural gas regulators. It should be noted that these tests were conducted to observe the potential for freezing or hydrate formation and do not address the issue of hydrate type, the rate of formation, or the effect of gas compositions.