Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Waste gas purifier
Patent
1991-05-03
1992-12-08
Warden, Robert J.
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Waste gas purifier
422183, 110210, 110212, 110213, 110214, 423241, 4232453, B01D 5000, B01D 5334
Patent
active
051696053
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process and an installation for the destruction by combustion of toxic gaseous effluents bereft of oxygen.
The problem of the elimination of such effluents is raised in particular in integrated circuit factories where gases laden with arsenic hydrides (arsines), and/or phosphorus hydrides (phosphines) and/or silicon hydrides (silanes) . . . are employed to dope the materials.
These gases are toxic and the gaseous stream containing them must absolutely be purified before being rejected into the atmosphere.
A known process of treatment consists in burning said gases; the combustion products not being toxic or being able to be easily eliminated (for example by filtration for arsenous oxide).
Patent No. FR 87 03729 published under No. 2 612 606 describes such a process with its associated device. According to this Patent, the effluent is conducted into a combustion zone via a central conduit surrounded by a pipe supplying the combustible gas, itself surrounded by three annular conduits supplying the combustion-supporting air. Every effort is made to remain as long as possible in laminar flow even beyond the burner in order to repel the inflammation zone in order to avoid the deposit of oxides on the burner. The flowrates and speeds of injection of the gases are regulated to that end. To the same end, the stream of combustible gas constitutes a sheath for protecting the effluent with respect to the combustion-supporting gas.
Applicant is proposing at the present time a process of combustion in which, contrary to the prior art, a considerable turbulence is created.
More precisely, the invention has for its object a process for the combustion of toxic gaseous effluents bereft of oxygen in a flame comprising an inner cone supplied with combustible gas and so-called primary combustion-supporting gas, process carried out under depression and in which said gaseous effluent and a so-called secondary combustion-supporting gas are introduced separately at the level of said inner cone, said secondary combustion-supporting gas being introduced in the form of at least one jet directed towards the axis of said inner cone at a sufficient flowrate and speed to ensure an excess of combustion supporting gas, the maintenance of temperature, and to create a turbulent gaseous mass at the level of said inner cone; the toxic gaseous effluent being introduced in said turbulent gaseous mass.
The invention therefore consists in a process of combustion of toxic gaseous effluents, bereft of oxygen. Such effluents are not explosive per se. They may become so in the presence of oxygen.
They are constituted by a vector gas laden with impurities. Said vector gas may be hydrogen, nitrogen, . . . or a mixture of gases. Air and oxygen are obviously excluded.
Said gaseous effluents to be burned according to the process of the invention may, as indicated above, come from the electronic industry. Such effluents are laden with hydride, particularly phosphines, arsines . . . and/or silanes . . . and/or other chemical compounds containing in particular B, P, As, Te, Se, Cl, F atoms.
Said gaseous effluents may also come from the nuclear industry It may be question of radio-active gases of pyrolysis and/or radio-active gases laden with tritium.
The inner cone of the flame is obtained from a conventional burner disposed at the head of the combustion zone, supplied with combustible gas (natural gas for example) and combustion-supporting gas (air for example). This combustion-supporting gas is called primary in the text of the present application in order to distinguish it from the other streams of combustion-supporting gas. The flowrate of this primary combustion-supporting gas is advantageously adjusted so as to ensure combustion with a small excess of combustion-supporting gas (about 10%).
According to the invention, so-called secondary combustion-supporting gas is sent towards the inner cone in the form of jet(s), at a sufficient flowrate to ensure an excess of combustion-supporting gas, with respect to the quantity necessar
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Societe Generale pour les Techniques Novelles SGN
Thornton Krisanne M.
Warden Robert J.
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