Fire design

WH boilers are usually packaged WT types of dual-fire design because a supplementary fuel is also required. The thermal energy is recovered and used to produce medium pressure (600-900 psig) process steam. 

The burners are located between tube rows. A larger number of burners reduces the heat release per burner and allows a smaller flame diameter and a reduced lane spacing. A ratio of one burner for every 2 to 2.5 tubes provides a uniform heat release. Most burners are a dual-fired design, firing both PSA offgas and supplemental makeup gas. Low NOx burners are used to meet environmental requirements. Makeup gas can be used to induce flue gas into the flame, reducing the flame temperature and NOx level. In a well functioning unit NOx levels as low as 0.03 lb/MMBtu are possible. 

These units are designed for operation at pressures up to 11.4 MPa (1650 psia) and 783 K (OSO F). Figure 24-35 shows a gas- or liquid-fuel-fired unit. While most shop-assembled boilers are gas- or oil-fired, designs are available to bum pulverized coal. A field-erected coal-fired industrial boiler is shown in Fig. 24-36. 

Limits on flue-gas velocities for gas- or oil-fired industrial boilers are usually determined by the need to limit draft loss. For coal firing, design gas velocities are established to minimize fouling and pluKing of tube banks in high-temperature zones and erosion in low-temperature zones. 

Recently, two significant developments have raised the profile of fire toxicity. The first is the development of the steady-state tube furnace (SSTF) (ISO TS 19700 2006), which has been shown to replicate the toxic product yields corresponding to the individual stages of fires. The second is the acceptance of performance-based fire design as an alternative to prescriptive fire regulations, so that architects can specify the components within a building based on a safe escape time, within which toxic and irritant gas concentrations must not approach a lethal level (ISO 13571 2007). 

Description Natural gas or another hydrocarbon feedstock is compressed (if required), desulfurized, mixed with steam and then converted into synthesis gas. The reforming section comprises a prereformer (optional, but gives particular benefits when the feedstock is higher hydrocarbons or naphtha), a fired tubular reformer and a secondary reformer, where process air is added. The amount of air is adjusted to obtain an H2/N2 ratio of 3.0 as required by the ammonia synthesis reaction. The tubular steam reformer is Topsoe s proprietary side-wall-fired design. After the reforming section, the synthesis gas undergoes high- and low-temperature shift conversion, carbon dioxide removal and methanation. 

Two additional types of fires, designated D and E, should be handled only by trained personnel. Type D fires include those involving powdered metal materials (e.g., magnesium). A special powder is used to fight this hazard, A type E fire is one that cannot be put out or is liable to result in a detonation (such as an arsenal fire). A type E fire is usually allowed to burn out while nearby materials are being appropriately protected. 

Xia Lingcao, Zhu Jiang, Liu Wenli 2010, Ideas and Practices of Buildings Fire Design for the Large Terminal Airport, Building Science, 26(ll) 95-99. 

Full scale experiments on FRP structural members subjected to realistic fire exposure are also necessary. Not only does this supply valuable results and provide confidence for the fire performance of FRP structural members to be used in civil engineering, it also validates the above modeling concepts on the structural level. Similarly, as performed in the fire design of structures made by traditional materials such as steel and reinforced concrete, active and passive fire protection techniques may be necessary for prolonging resistance time of composite materials in fire. Such techniques are reviewed and compared, particularly with regard to their applications for composite materials. 

BS EN 1995-1-2 2004 Eurocode 5. Design of timber structures. General. Structural fire design. 

Berwick, D.M. (2003) Escape Fire. Designs for the Future of Healthcare, Jossey Bass, San Francisco CA. 

P(l) The fundamental requirements of fire design shall be as specified ... 

P(l) The following factors shall be taken account of in the fire design of components made of FRP composites ... 

Active methods of fire design are principally involved with fire safety and are applicable to all materials, not only FRP composites. 

P(4) Systems and methods adopted in fire design for fire penetration shall provide adeqnate fire barriers around pipes, services and other perforations throngh the FRP composite components. 

P(8) in developing methods and systems for fire design of FRP composites, the designer shall consider the effects on other design properties of the materials and of the structure. Such design properties shall include ... 

The factors that need to be considered in fire design include ... 

Berwick, D. M. Escape Fire Designs fir the Euture of Health Care. San Francisco Jossey-Bass, 2003. 

Many factors affect the ability of a building and the assemblies of materials in it to continue to carry loads during a fire. Designers use analytical design, data from design tables and guides, code requirements, and test results to reach decisions. 

Figure 33.6 Simplified SOFC/GT hybrid system schematic (direct-fired design).

---