SU1662933A1 - Method of soda recovery - Google Patents

Abstract

The invention relates to chemical technology, in particular to methods for producing molten salts, and makes it possible to increase the explosion safety of the process. A method for regenerating soda from black liquor, a by-product of pulp production, is that the process is carried out while maintaining the melt temperature of 1000-1100 ° C. 1 il.

Description

The invention relates to chemical technology, in particular, to methods for producing molten salts with a predominantly ionic character of chemical bonding.

The aim of the invention is to increase explosion safety. process.

The method is carried out as follows.

The regeneration of soda is carried out by the so-called burning of black liquor and fuel oil in a soda recovery boiler (RMS). The proposed method is suitable for all designs of IBS. Black liquor suspension - a by-product of cellulose production, composition,%: MaONsvob. 2.5; No. 2CO3 1b; iMa2S 5.5; NaOHopr. 13.5; Na2 $ 04 5.5; organic compounds 55.5 (in terms of dry weight), humidity 45% through the nozzle is fed into the combustion chamber - the furnace. In IBS, two processes occur simultaneously; burning the black liquor organic part and recovering N32S04. The organic part burns in the firebox, and the mineral part falls on under the combustion chamber, forming the cinder butt, in which Na2S is reduced; N32S04 + 2C - 2C02. The cinder cinder is located on the surface of the molten salt — green liquor, which contains mainly Na2S 23% and No. 2CO3 72%.

The melt is continuously removed from the boiler through the taphole. To maintain the temperature of the melt, fuel oil is fed into the combustion chamber through the fuel oil nozzles.

In contrast to the known methods, in which the temperature of the molten salt is 900 ° C, in the proposed method it is constantly maintained above 1000 ° C. Tah even &

WITH

with

-but

This temperature increase does not affect the quality of the product.

When soda is regenerated by a known method, there is a danger of explosion due to water entering the melt from the pipes shielding the internal surface of the IBS. The explosion in case of water ingress into the IBS occurs in two cases: during the technological process and in case of emergency stop of the boiler. The proposed method relates to the case of a technological process for which the explosion is completely excluded. However, it does not resolve the issue during an emergency stop.

Investigations of the explosion process with molten salts, taken from the sr of the SRK, and the molten salt of NaCI showed that explosions occur at a melt temperature below 1000 ° C, there is no explosions above this temperature.

The explosion process was radiated in a special furnace, the crucible with molten salts, taken from the SRK, was installed in a furnace in which a certain temperature was maintained. When the melt reached this temperature, water was injected — initiating, while oscillograms were taken. The experiments were conducted in the temperature range of 970-1150 ° C through 10 ° C. Accuracy of measurements ± 5 ° С. The upper limit of the melt temperature for an area in which an explosion is not observed may be a vaporization temperature of 1540 ° C, however, for the least energy, it is advisable to work with a melt temperature not higher than 1100 ° C. With reliable organization, control and maintenance of the input characteristics of black liquor in the RMS, the melt temperature can be as close as possible to 1000 ° C. If there are uncontrolled changes in the parameters of black liquor, the temperature of the melt should be much higher than 1000 ° C.

The drawing shows oscillograms of changes in the intensity of radiation during an explosion and its absence, where I / I0

relative change in radiation intensity; I is the intensity of melts melted during the interaction of the melt with water; 0 is the radiation intensity of the melt without interaction with water at a given temperature in the furnace; t - time, s. Oscillograms were recorded on an H-115 oscilloscope, and a PD-6 diode served as a radiation receiver.

The oscillograms presented are characteristic for two temperature regions: the first includes temperatures below 1000 ° C (A), the second - above 1000 ° C (B). The first section of the oscillogram characterizes the intensity of radiation of the crucible wall before water injection — initiation (curve a), and three times the change in intensity of radiation of the crucible wall after initiation (curves b and c). At temperatures below 10 ° C, an explosion and destruction of the crucible occur, with a sharp decrease in the intensity of radiation (curve b), and then a sharp rise, above the initial value (curve c). At temperatures above 1000 ° C, crucible destruction is not

radiation intensity does not occur

increases, and its decline in

time (curve b), i.e. explosion excluded.

Thus, the use of the proposed method of regenerating soda from black liquor while maintaining the molten salt temperature of 1000-1100 ° C provides, in comparison with the known method, enhanced explosion safety when carrying out the process without degrading the quality of the product obtained.

Claims (1)

DETAILED DESCRIPTION OF THE INVENTION A method for regenerating soda from black liquor from a by-product of pulp production, including burning black liquor and fuel oil to form a molten salt, characterized in that, in order to improve explosion safety, the process is maintained while maintaining the molten salt temperature 1000-1100 ° C. j; bl BUT a ABOUT about d ST (s) t (s)