Dusts explosion apparatus

The explosion characteristics determined using the vapor and dust explosion apparatus are used in the following way ... 

The subscript in vessel is for the reactor or building. The subscript experimental applies to data determined in the laboratory using either the vapor or dust explosion apparatus. Equation 6-20 allows the experimental results from the dust and vapor explosion apparatus to be applied to determining the explosive behavior of materials in buildings and process vessels. This is discussed in more detail in chapter 9. The constants KG and KSt are not physical properties of the material because they are dependent on (1) the composition of the mixture, (2) the mixing within the vessel, (3) the shape of the reaction vessel, and (4) the energy of the ignition source. It is therefore necessary to run the experiments as close as possible to the actual conditions under consideration. 

The experimental apparatus used to characterize the explosive nature of dusts is shown in Figure 6-17. The device is similar to the vapor explosion apparatus, with the exception of a... 

Test apparatus for acquiring dust explosion data. 

When designing reliefs for gas or dust explosions, special deflagration data for the scenario conditions are required. These data are acquired with the apparatus already described in section 6-13. 

Brown, K. C. and Essenhigh, R. H., Dust Explosions in Factories A New Vertical Tube Test Apparatus. Safety in Mines Research Establishment Research Report, No 165, Ministry of Power, Sheffield, England (April 1959). 

Table 2.5 Dust explosion protected electrical apparatus...

As an example of dust explosion protected apparatus standard IEC 61241-4, 1st edition 2001-3, types of protection pD describes a pressurization technique the interior of this apparatus is subjected to a continuous pressure from a supply of air (not containing any combustible substances) or other inert gases while electrical components within the enclosure are energized. 

The maximum explosion pressure and maximum rate of pressure rise values are determined by using the 20 L sphere apparatus. The dust sample is dispersed within the sphere, ignited by chemical igniters, and the pressure of the resulting explosion is measured. The sample size is varied to determine the optimal dust cloud concentration. The maximum pressure and rate of pressure rise are measured and used to calculate the explosion severity (Kst) value of the dust cloud. These data can be used for the purpose of designing dust explosion protection measures. 

Safety procedures in chemical process facility. Partial contents introduction to corporate safety, laboratory safety and inspections, process area safety features and procedures, DIERs and VSP, dust and vapor explosion apparatus, personal protective equipment, process area inspections, and informal and formal safety reviews. American Institute of Chemical Engineers, 1989. 

PERSONAL PROTECTION Wear impervious protective clothing, including boots, chemical-resistant gloves, lab coat, apron or coveralls wear dust-proof safety goggles enclose operations and use local exhaust ventilation at site of chemical release use dust explosion-proof electrical equipment and lighting for extra personal protection, chemical protection suit including self-contained breathing apparatus is recommended. 

PERSONAL PROTECTION wear full protective clothing and chemical-resistant gloves wear chemical safety goggles wear self-contained breathing apparatus a closed system of local exhaust ventilation is recommended to control emissions at the source and to prevent dispersion into general work area use dust explosion-proof electrical equipment and lighting for extra personal protection, use a P2 filter respirator for harmful particles maintain eyewash baths and safety showers in work area. 

Decomposition products of powder layers deposited on hot surface may flash, inducing a devastating dust explosion. The flash point of the decomposition products is determined in the apparatus shown in Figure 3.81. 2 g of powder sample is heated by an electric heating block at a rate of 4°C/min under an oxygen stream of 1.5 dm /h. At every 1 °C temperature rise, the electrodes arc. The flash point is the lowest temperature at which the decomposition products flare up. 

There are several different devices for determination of dust explosion characteristics. All devices include a vessel which may be op>en or closed, an ignition source which may be an electrical spark or electrically heated wire coil and a supply of air for dispersion of the dust. The simplest apparatus is known as the vertical tube apparatus and is shown schematically in Figure 15.4. The sample dust is placed in the dispersion cup. Delivery of dispersion air to the cup is via a solenoid valve. Ignition may be either by electrical spark across electrodes or by heated coil. The vertical tube apparatus is used for the classification test and for determination of minimum dust concentration for explosion, minimum energy for ignition and in a modified form for minimum oxygen for combustion. 

Figure 15.4 Vertical tube apparatus for determination of dust explosion characteristics.

The minimum dust concentration for explosion is measured in the vertical tube apparatus and is used to give an indication of the quantities of air to be used in extraction systems for combustible dusts. Since dust concentrations can vary widely with time and location in a plant it is not considered wise to use concentration control as the sole method of protection against dust explosion. 

Table 15.2 Dust explosion classes based on 1 test apparatus.

These two quite different operations share the specied hazards that are presented by small, dry particles. These hazards, which relate to surface activity, include static electricity accumulation and the possibility of dust explosions. These can occur in any type of apparatus. No product, therefore, should be dried, ground, or milled without thorough knowledge of its safety-related properties. All of the following must be considered in a hazard evaluation ... 

Open fluid bed units are not capable of mamtainmg environmental protection demands when materials to be dried are moistened by organic solvents. Fluidized bed units are therefore equipped with closed duct systems as well as solvent recovery systems (Scheme 13.2). Due to safety regulations (solvent vapour and dust explosion) the entire apparatus needs to be filled with inert gas prior to process... 

Flammability = 4, ie, very flammable gas, very volatile, and materials that in the form of dusts or mists form explosive mixtures when dispersed in air Health = 2, ie, hazardous to health, but may be entered freely with self-contained breathing apparatus Reactivity = 0, ie, is normally stable when under fire-exposure conditions and is not reactive with water... 

FIG. 23-10 An apparatus for collecting explosion data for dusts. [D. A. Crowl, Understanding Explosions, Center for Chemical Process Safety (CCPS) of the American Institute of Chemical Engineers (AlChE) copyright 2003 AlChE and reproduced with permission. ]... 

Ignitability and explosibility of firedamp) 119-22 (Same for coal dust) 122-23 (Same for mixts of firedamp and coal dust) 11)P.M.Andreev, RusP 51297 (1937) CA 33, 4788 (1939) (Apparatus for stopping explns of coal dust or of firedamp) lla)J.(.Graham, Colliery Guardian 159, 582-85 Sc 626 30... 

---