There are situations in several areas when the volume is released in the rooms due to a technological process variable amounts of harmful substances. If you enter the room where fresh air technology precession occurs continuously, increase the concentration of harmful substances in the room up to the maximum Ct maximum, then decreases to 0. If the room is ventilated air exchange is zero, then the concentration of discharges is determined as follows :.
Ct =Gt /V [ gr/h : m3/h]
Ct = Ca The allowable limit is the concentration [g / m 3]
Gt: the amount of pollutants that are released in a time [ kg ]
V: volume of the room where the amount of emissions in developing release time [m 3]
Particular but important case of installation failure
Necessary air flow for removal of harmful substances released suddenly in a hall as a result of an accident (crash); this air flow must be determined for a time W in the room volume V so that the concentration of pollutants decreases from a maximum value at a minimum admissible as.
In time W, decrease the amount of substances with harmfulness in volume is equal to the amount extracted hall air mixed with harmful substances discharged.
D=2.303 x V : W lg Ct/Ca D: air flow necessary to evacuate in time of W minutes a quantity of noxious (gas or vapor) due to accidental damage developed at a limited amount of space closed.
V: volume of closed space where there is limited damage to be annihilated by a ventilation emergency surgery for evacuation during hazardous quantity W (gas or vapor) developed at by accident. W: time delay is necessary to introduce the necessary fresh air flow in the hall (in the amount of limited space) where the damage occurred.
Concrete case
Input:
A hall has volume V = 300 m3
During the evacuation of harmfulness W = 5 minutes
The amount of pollutants that emit Gt = 21kg = 21.000 gr
Data Output :
Required to calculate the air flow necessary for the discharge of harmful quantities so that the final concentration of harmful substance to fall from maximum to minimum value admissible as .= 0.01 g/m3
1. Determine the maximum concentration of harmful substances released into the hall
Ct =Gt /V [ gr/h : m3/h]
Ct = 21.000 : 300 = 70g/ m3
Ct = 70g/ m3
2. Calculation of air flow necessary for the discharge of harmful quantities released into the hall during W = 5min
D=2.303 x V : W lg Ct/Ca
D=2.303 x 300 : 5 x lg 7 0/ 0.01 =
D= 691 : 19.25
D = 36 m3/min = 2153 m3/h
Notifications
But why calculate the required air flow volume of air washing harmfulness hall accidentally released due to damage for 7 minutes a machine?
The answer is to protect people.
If a section of the lake drying films characterized by solvent evaporation people working in the hall may be surprised by evaporation which increases rapidly after a failure in a machine; the beginning of the drying process and decreases as the drying process comes to an end, that decreases the amount of steam after stopping damage.
Can be calculated with the installation of emergency ventilation air flow necessary for the discharge amount of noxious casual accidentally while people may leave the premises without their health being affected. (Thus ensuring people’s health and life).
Of course ventilation plant will become operational if ordered by sensing that if the concentration exceeds the permissible limit then the command start emergency ventilation plant.
This sensing from increasing concentration of solvent vapor or carbon dioxide to give the starting command ventilation installations for washing with fresh air to the enclosure from the work site safe flow of people to the harmful substances in a mixture with air is evacuated and of course the machine is repaired damage repaired.
Goodbye !
Niciun comentariu:
Trimiteți un comentariu