Transport ventilation

The use of underground mining methods requires integration of transportation, ventilation, ground control, and mining methods to form a system that provides the highest possible degree of safety, the lowest cost per ton of product, the most suitable quality of final product, the maximum possible recovery of coal, and the minimum disturbance of... 

A carefully planned network of shafts, drifts, and raises are the requisites of a producing underground mine. The word development stands for the preparation of this network. In normal development one can recognize four different kinds of rock excavation and they are shafts, drifts, raises and inclines. The main aim of provision of a shaft is to provide access to or a connection with underground. This access may be utilized for a variety of purposes hoisting rock and ore, personnel and material transport, ventilation, etc. Most modem shafts... 

Starting some years ago, a working group of CENELEC subcommittee SC 31-7 established a (draft) standard pr EN 50381 for TVRs (transportable ventilated rooms with and without an internal source of release). This standard... 

Transport and Transformation. Once emitted into the atmosphere, the fate of a particular poUutant depends upon the stabihty of the atmosphere, which determines the concentration of the species, the stabihty of the poUutant in the atmosphere, which determines the persistence of the substance. Transport depends upon the stabUity of the atmosphere which, in turn, depends upon the ventilation. The stabUity of a poUutant depends on the presence or absence of clouds, fog, or precipitation the poUutant s solubUity in water and reactivity with other atmospheric constituents (which may be a function of temperature) the concentrations of other atmospheric constituents the poUutant s stabUity in the presence of sunlight and the deposition velocity of the poUutant. 

Transportation. Ammonium nitrate is safely transported by rad, road, and water. However, its transportation on U.S. navigable waterways is restricted. Good ventilation must be provided and precautions taken against leakage and contamination. The material must be completely isolated from other cargo and must be kept free of extraneous combustible materials. 

Succinic acid and succinic anhydride are sold in 25-kg net polyethylene (PE) bags having cardboard box protection for the anhydride, in 70-liter (50-kg net) fiber dmms, and in 55-gaHon (275-lb 125-kg net) dmms. The two products must be stored in a fresh, dry, ventilated area. Succinic anhydride must be carefully protected from moisture during transportation and storage to avoid hydrolysis to succinic acid. 

The melting pot is heated either electrically or by gas to 427—524°C. The pot capacity is typically over 100 kg of lead alloy, and periodically the top of the molten metal must be skimmed to remove the dross. The pot fumes must be removed by adequate ventilation (forced suction). When the molten metal has reached the proper temperature and flow characteristics, it is transported by pump to the grid mold. 

Whatever the type of ventilation, air flow must be adequate to prevent partieulate matter settling in the dueting typieal transport veloeities are given in Table 12.13. 

Chemical Reactivity - Reactivity with Water Reacts violently with water as a dry solid or when dissolved in ether. The hydrogen produced by the reaction with water is a major hazard and necessitates adequate ventilation Reactivity with Common Materials Can burn in heated or moist air Stability During Transport Normally stable imstable at high temperatures Neutralizing Agerus for Acids and Caustics Not pertinent Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

FIRAC is a computer code designed to estimate radioactive and chemical source-terms as.sociaied with a fire and predict fire-induced flows and thermal and material transport within facilities, especially transport through a ventilation system. It includes a fire compartment module based on the FIRIN computer code, which calculates fuel mass loss rates and energy generation rates within the fire compartment. A second fire module, FIRAC2, based on the CFAST computer code, is in the code to model fire growth and smoke transport in multicompartment stmetures. 

It is user friendly and possesses a graphical user interface for developing the flow paths, ventilation system, and initial conditions. The FIRIN and CFAST modules can be bypassed and temperature, pressure, gas, release energy, mass functions of time specified. FIRAC i.s applicable to any facility (i.e., buildings, tanks, multiple rooms, etc,) with and without ventilation systems. It is applicable to multi species gas mixing or transport problems, as well as aerosol transport problems, FIRAC includes source term models for fires and limitless flow paths, except the FlRlN fire compartment limit of to no more than three... 

GASFLOW models geometrically complex containments, buildings, and ventilation systems with multiple compartments and internal structures. It calculates gas and aerosol behavior of low-speed buoyancy driven flows, diffusion-dominated flows, and turbulent flows dunng deflagrations. It models condensation in the bulk fluid regions heat transfer to wall and internal stmetures by convection, radiation, and condensation chemical kinetics of combustion of hydrogen or hydrocarbon.s fluid turbulence and the transport, deposition, and entrainment of discrete particles. 

EXP AC analyzes an interconnected network of building rooms and ventilation systems. A lumped-parameter formulation is used that includes the effects of inertial and choking flow in rapid gas transienl.s. The latest version is specifically suited to calculation of the detailed effects of explosions in the far field using a parametric representation of the explosive event. A material transport capability models the effects of convection, depletion, entrainment, and filtration of... 

This chapter describes the aerodynamic principles, models, and equations that govern the flow and the contaminant presence and transport in a designated volume of a work room. The purpose of local ventilation is to control the transport of contaminants at or near the source of emission, thus minimizing the contaminants in the workplace air. 

The necessary containment or transport capability of a local ventilation sy stem depends on the type of contaminant present and its health risks. There could be different demands for gases and particles, for contaminants that have immediate health risks and those that have long-term effects, for contaminants that affect the breathing system and those that affect the skin and eyes, for infectious contaminants, fot contaminants that follow the air streamlines closely and those that fall out on floor and work surfaces, etc. (See Chapter 5 for physiological and toxicological considerations.)... 

To choose a supply inlet as the local ventilation system is not common because it is difficult to design for the specific spreading of contaminants. This is usually easier with an exhaust hood. However, there are moments when large flow rates or specific flow fields are necessary to transport contaminants or for shielding from contaminants. 

Each jet must be designed for a specific function. A jet could easily transport or increase the capturing of contaminants, but could also very easily destroy the intended function of a local ventilation system. 

The ventilation in an abrasive blasting room has three main tunctions. The first is to transport the generated dust to the exhaust during the work in such a w ay that good visibility is achieved. The second is to eliminate, as fast as possible, the dust in the room after the work has ended. 7 he third is to prevent unrestricted dispersal and backwash on the blast operator and the machinery and to keep the dust inside the room, preventing exposure to personnel working outside the room. 

The hunnidity ratio oJ a rotjm at any given time is given by a Jatent heat balance equation including the water vapor flows due to infiltration to ventilation to moisture transport through envelope elements... 

When air flows at a certain rate through the space, energy is transported in relation to the difference between supply and extract air temperature. Such airflow can be induced by natural or mechanical ventilation. See Section 11.5 on the interaction between naturally induced airflows and the thermal behav ior of the room. 

Moisture Is also transported by ventilation airflows. This is dealt with in more detail in Section 11.4,... 

The integration of the ventilation model into the thermal building model can be realized on different levels, from simple stack-flow equations to a full integration of a multizone airflow and contaminant transport model. 

Overview of combined modeling of heat transport and air movement, AIVC Technical Note TN 40. Coventry Air Infiltration and Ventilation Centre, 1993. 

Clean air and many air contaminants are under normal conditions invisible. It is, however, often desired to actually see the movement of air or the emission and transport of contaminants in order to ensure good air quality.. Methods aimed at the visualization of airflow, contaminants emission to the air, and their transportation out in the workplace and to the breathing zone of the worker are therefore important tools for designers of industrial ventilation systems. 

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