Device in a reactor for gasifying spent liquor

Details Device in a reactor for gasifying spent liquor Device in a reactor for gasifying spent liquor

1994-10-26

1996-09-17

Warden, Robert J.

Chemical apparatus and process disinfecting, deodorizing, preser

Chemical reactor

For chemical recovery of chemicals from waste paper making...

422227, 422228, D21C 1100

Patent

active

055566022

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL BACKGROUND

The present invention relates to a device for thermal decomposition of stock, especially a spent liquor obtained from pulp manufacture, where the gas stream formed in this connection contacts a liquid bath, in which smelt particles are separated from the gas. The device comprises a reactor and a housing for the said liquid bath inside which a tipping chute, which is connected to the outlet of the reactor chamber, discharges.


STATE OF THE ART AND PROBLEMS

In the production of pulp, spent liquors are generated which contain both inorganic and organic compounds. It is desirable to recover the inorganic compounds, in order to produce new digestion liquid, and to extract fuel energy from the organic compounds. A special method for achieving this is described in WO-A-SE91/00383. Instead of the conventional recovery boiler, a gasification reactor is used in which thermal decomposition of the spent liquor takes place under conditions of sub-stoichiometric oxygen supply, so that a large amount of combustible gases (CO, H.sub.2, CH.sub.4, H.sub.2 S, etc.) is produced in the reactor. The fuel energy in these gases can then be employed in a flexible manner, for example for steam generation or for gas turbine operation.
However, during the thermal decomposition, a mixture is formed of the said gases and finely-suspended inorganic components. The inorganic components must be separated from the gas stream before the gas can be used as a multi-purpose fuel. According to the above mentioned known method, the main separation takes place in a liquid bath which is arranged in direct connection to the reactor outlet. Using a tipping chute, whose lower end discharges into the liquid bath and whose upper end is arranged at the outlet of the reactor chamber, the gases are conducted down into the liquid bath, in which liquid bath the said main separation occurs.
By means of a follow-up treatment of the liquid in the liquid bath, the inorganic components can be recovered for renewed use. The gas is also subjected to a follow-up treatment before it is utilised as fuel. Included in the latter follow-up treatment are heat exchange of the combustible gases to extract the physical heat (thermal energy) they possess, and also scrubber treatment.
Liquid is added both to avoid problems resulting from depositions of solidified smelt at the outlet of the reactor chamber, and also to protect the inner surface of the tipping chute both from chemical attack and from high temperature. An additional arrangement in association with the outlet of the reactor chamber consists of cooling loops which are arranged on the outer surface of the bottom cone.
It is evident to the person skilled in the art that both these arrangements are relatively comprehensive and expensive, as a result of the separate pumping, piping and controlling systems which are necessary, for which reason it is desirable to avoid these completely. A further problem is that small alkali particles (in the form of fumes) are not separated off in a known kind of quench.


SOLUTION AND ADVANTAGES

An object of the following invention is to present a reactor in which the above mentioned disadvantages are eliminated. The invention also provides the advantage that a greater flow of liquid on the inner wall of the tipping chute can be obtained, which implies that stronger instantaneous cooling, so-called quench cooling, of gas and smelt drops can be obtained, as can improved dissolution of the smelt particles already in transit down through the tipping chute. Secondly it is an object to present a reactor which does not possess special arrangements comprising piping, pumps and control equipment for supplying liquid inside the tipping chute or for cooling the bottom cone of the reactor chamber.
The above mentioned object is achieved using a device for thermal decomposition of stock, especially a spent liquor obtained from pulp manufacture, where the gas stream formed in this connection contacts a liquid bath, which device comprises a reactor with a chamber for the sai

REFERENCES:
patent: 1380067 (1921-05-01), Koch et al.
patent: 2871108 (1959-01-01), Knapp
patent: 3271117 (1966-09-01), Leatham et al.
patent: 4842831 (1989-06-01), Yabumoto et al.

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