Natural gas-fired systems

Air preheat temperature requirements of 2250—2300 K are anticipated for natural gas-fired systems, and about 2000 K for oil or coal-fired systems (11). Use of 32—40% oxygen enrichment lowers the preheat temperature requirement to a moderate 900—1000 K, which can be attained with conventional metal-type tubular heat exchangers. Depending on the cost of oxygen, this is a viable alternative to the use of separately fired high temperature preheaters. 

In Germany iron oxide/chromium oxide catalysts have been used since the 1960s. Flockenhaus [99] describes an application for SCR downstream in a natural-gas fired system NO.v conversions of about 70% for a NH3 NO ratio of 0.8 were obtained. 

Gas turbine-based power plants, particularly natural gas-fired cogeneration and combined-cycle faciUties, have proven to be highly rehable, efficient, and environmentally attractive. Advances in machine design, more efficient plant integration, and optimistic forecasts for the availabiUty of affordable natural gas worldwide have boosted the appeal of these systems for both base-load and peaking service. 

When optimizing industrial ventilation, the real consequences for the environment due to decisions made are of interest. Therefore, the marginal effect on the whole energy system is what is required. This is of course difficult. Many practitioners use electricity produced from coal processes as marginal, but some use natural-gas-fired power plants. It depends mainly on the area and time frame that is being considered. 

Rabovitser, J.K., Khinkis. M.J., Bannister. R.L. and Miao, F.Q. (1996), Evaluation of thermochemical recuperation and partial oxidation concepts for natural gas-fired advanced turbine systems, ASME paper 96-GT-290. 

The NO t constituent in the exhaust of machines firing natural gas is some 150 to 160 ppm, and for distillate fuels typically 260 ppm. In order to reduce these levels to the targets quoted above, catalytic filters can be used, but the systems currently available are expensive. As an alternative, certain manufacturers are developing low-NO burners but these limit the user to natural gas firing. 

The fuel cell system emits much less carbon into the air than a combustion-based power plant. Less than one percent of the amount is produced from generating the same amount of power. The system is more expensive, costing several times as much per kilowatt-hour (kWh) of electricity produced than energy from a new natural gas fired turbine system. 

Fig. 14.12 Stack concentrations of UHC as function of NO in the exhaust of a lean-burn natural gas fired engine [234], The following conditions can be assumed for the exhaust system inlet composition CH4 = 4410 ppm, C2H6 = 490 ppm, O2 = 8.5%, H2O =13%, CO2 = 6.5%, NO = 10-1813 ppm, NO2 = 3-544 ppm, balance nitrogen temperature = 680°C, reactor residence time = 210 ms, pressure = 1.7 bar.

Many states now require fire suppression systems for public service stations and for some private fleet refueling facilities. Most of these systems are dry chemical using infrared detectors and work as effectively on natural gas fires as gasoline fires. No special requirements are necessary few these systems when used at a CNG refueling facility. All fire suppression systems should be checked after installation for proper coverage using a fraction of the dry chemical that would normally be used (this is called a puff test ). The puff test not only shows the coverage that will be obtained, but tests the components of the fire protection system. 

Mimura et al [1] found an effective amine solvent (KS-2) with a long lifetime and reported that the KS-2 solvent system could reduce the energy penalty by 20% compared with a MEA system. The power plant losses based on generator output power were calculated to be 5.4-5.8% for a natural gas-fired plant and 9.0% for a coal-fired plant at CO recovery of 90%. 

The value of backup power is as much as three to four times the value of primary power on a kilowatt basis. For example, the lifecycle cost of the backup power systems found at the base of a cell tower, which now consists of a bank of lead acid batteries and a diesel or natural gas fired combustion engine, is between 3000 and 4000 per kW. Critical power facilities for data processing centers and the like are also in this cost range. The simple fact is that customers need electricity and will pay a considerable insurance premium to obtain assurance of uninterruptible power. In the case of cellular phone service providers, their federal FCC license may be at risk if they are unable to demonstrate adequate operating capability in the event of grid outages. 

Increased pressure drop. Could require conversion to FD burners, or installation of an ID fan. Precipitation can still occur in the catalyst bed because of capillary action that raises the dew point of the ammonium salts. This is negligible for natural gas and refinery fuel gas fired systems but can be significant for applications with high sulfur in the fuel. 

Schulze, W. J. "A Systems Approach to Adding Natural Gas Firing to Two 600 MW Units." Joint ISA/EPRI Conference, June 8, 1993. 

Goal Line Environmental Technologies, SCONOx, Catalytic Adsorption System for Natural Gas Fired Power Plants to Reduce or Eliminate Nitrogen Oxides and Carbon Monoxide, Technical Brochure. 

A dilution air system designed for fuel-oil firing requires about 5% less dilution air than for natural gas firing therefore, a natural gas system design will perform... 

Natural gas fired power stations with steam cycles achieve efficiencies between 42 and 47 %, fig. 1. But obviously the gas turbine technology offers, in particular for natural gas based systems, a number of advantages, e.g. low capital cost, short construction time, and last not least high potential for efficiency. 

The theoretical advantage an IGCC plant has over a conventional coal plant is in the higher system efficiency of the combined cycle, a concept originally developed for natural gas-fired plants and used in many such plants for meeting intermediate and peak loads. 

Sampattagul S, Kato S, Kiatsiriroat T, Maruyama N, Widiyanto A. LCA-NETS tool for environmental design of natural gas-fired power generation systems in Thailand. In 2003 3rd international symposium on environmentally conscious design and inverse manufacturing — Ecodesign 03 2003. p. 141-6. 

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