CS277494B6 - A method of regenerating saturation sludge - Google Patents

Abstract

The invention solves a method of regeneration of saturation sludge, so that the temperature, density and pH of saturation sludge are adjusted in the first water circuit. The solid component from the sludge suspension passes into the second circuit, into which a solution of an agent blocking the transition of non-sugars in the liquid to this circuit is fed. In the second circuit, the sludge is thickened, alkalized and dosed into technological devices for sugar production.

Description

Field of technology:

The invention relates to a process for the regeneration of saturating sludge in sugar factories.

Prior art:

Established methods of saturation sludge regeneration are based on the firing of saturation sludge in rotary kilns. A description of this method is given in Zucker Industrie 21, 1971, page 26, and Sucrerie Franais Nr. 11/1971, 12/1971 and 2/1972. This method of regenerating the saturating sludge consists in diluting the saturating sludge with water, concentrating it in centrifuges and adjusting it to a granular state by adding soda. The granulate proceeds to a rotary kiln heated by fuel oil, where the saturating sludge is burned to calcium oxide, which leaves the kiln in the form of powdered lime, which is granulated again and then used in sugar technology. .

Another published method, patent SU 1442552.8pp, without specifying the practical application, washes the saturating sludge with water, then carbonates it with carbon dioxide, then separates it on hydrocyclones. CaO in the form of lime is dosed into the mixture up to pH 11 to 12, then the mixture is brought into contact with sugar-containing substances until it is sweetened to 5 to 20% sugar and is dosed into a pre-clarifier at a place whose pH is between 8 .0 to 9.5. Lime is introduced into the dilute portion of the hydrocyclones up to a pH of 11 to 11.5 and is heated to 80 to 95 ° C, then the mixture is purified by settling and the precipitate is filtered by vacuum filters; the filter cake is given to customers and the filtrate can be used to alkalize the wash water. .

The disadvantage of these methods in the case of the sludge firing method is the high energy consumption, i.e. fuel oil, and the presence of sodium oxide in the regenerated lime used, which adversely increases the production of molasses from sugar juices. In the case of the method according to SU 1442552.8pp, the procedure is demanding on the consumption of washing water and the proportion of non-sugars in the liquid component of the resulting suspension is maintained. The standard way of using saturation sludge in most sugar factories is to return the saturation sludge without regeneration, for example by recirculating the concentrated saturation sludge or by recirculating the first saturated juice. In this case, non-sugars, sucrose and water are returned along with the calcium carbonate. The disadvantage of this method is the increased consumption of electricity when pumping juices, the deterioration of the resulting color of sugar juices without reducing the consumption of lime.

Summary of the invention:

The essence of the saturation sludge regeneration method according to the invention is a two-circuit regeneration station arrangement, where in the first water circuit a saturation sludge suspension with a density of 1010 kg / m ³ to 1350 kg / m ³ and a temperature above 55 ° C is sorted by a vibrating sieve. to a value of 6.5 to 9.5 by an inorganic acid, gas or other means, after which a solution of the ammonium salt reagent is added to the settling particles of the suspension in the second circuit to prevent the transition of the non-sugar liquid from the first circuit to the second circuit. the resulting sludge suspension is concentrated and subsequently activated by the addition of lime milk, the liquid separated during the concentration being returned to the beginning of the second circuit, (Scheme No. 1). The advantage of the presented solution is the reduction of lime consumption for the purification of sugar juices and thus the reduction of the consumption of limestone, coke, electricity without deteriorating the technological results of cleaning, while it is a sequence of simple operations. The effect of the process is ecological; Limestone mining, coke production, transport of these raw materials are reduced, electricity consumption is reduced, the release of carbon residues into the air is reduced.

Explanation of drawings:

Scheme No. 1 is a technological block diagram of a two-circuit arrangement of sludge regeneration and is an auxiliary scheme to describe the essence of the invention

Scheme No. 2 is a flow chart of the described exemplary embodiment of the invention

Marks in the diagrams have the meaning:

A ..... heating the suspension (liquid, heating surface, shredder)

B ..... sorting of sewing (fixed, vibrating, rotating)

C ..... pH adjustment (liquid, gas)

D ..... settling zone

E ..... solid part of the suspension

F ..... liquid from the second water circuit '

G ..... blocking solution supply

H ..... thickening (sedimentation, centrifugation, filtration)

R ..... alkalization (CaO, Ca (OH) ₂ , MgO, Mg (OH) ₂ )

I-VO .. first water inlet circuit

II-VO. second water circuit outlet

Example of an embodiment of the invention:

The suspension of the sweetened saturating sludge is adjusted to a temperature of 65 ° C and a density of 1.15 t / m ³ . Subsequently, the suspension is pumped by a centrifugal pump into the first water circuit on a vibrating screen with openings of 1x1 mm. Excess is waste from the regeneration station. The subsoil is led to a circulation tube, where the pH of the suspension is adjusted to 7.5. From the space of the circulation tube, the suspension flows into the settling zone. Liquid from the second water circuit is forced into the lower part of this zone. From the upper part of the settling zone, the liquid is discharged to the waste - 20% and to the incoming suspension of the sweetened sludge - 80%. From the lower part of the settling zone, the separated sludge falls off and is treated with a 1% ammonium carbonate solution. him to release heavy metals into the solution. The carbonate solution restricts the passage of the non-sugar liquid into the second water circuit. The mixture obtained is concentrated by decantation, filtration or centrifugation, in which the calcium carbonate crystals are mechanically treated by centrifugal and tangential forces. A thin portion of the concentration of the mixture is passed downstream of the settling zone, but prior to the introduction of the reagent solution. A dense portion of the thickening is mixed with lime milk in a proportion according to the needs of the subsequent technology and after a reaction time of 15

CS 277494- B6 minutes, the resulting regenerated sludge is dosed into technological equipment of sugar production (scheme No. 2).

Industrial applicability:. '

Regenerated saturation sludge can be used in sugar technology - ’

- for the epuration of sugar juices, replacing lime milk and being dosed instead or with it to technological installations in the epuration of the sugar factory; for example in the precursor chambers.

- for the filtration of heavy sugar solutions, where it replaces diatomaceous earth or other alluvial filter material and is dosed in its place or together with it into filtered or alluvial liquids.

- to separate the pre-clarified precipitate by filtration, the use of regenerated sludge in the pre-clarifier facilitating the filtration of the pre-clarified juice. The regenerated sludge is made from sludge after saturation, from sludge after saccharification of molasses or from sludge after filtration of heavy juice and is dosed into diffusion or pre-clarified juice. The precipitate is separated by filtration on textile cloths after any necessary adjustment of pH or density. ’

- for the regeneration of waste from the saccharification of molasses by the method of separation and decomposition of tricalcium saccharide and the subsequent use of this waste in the epuration line of the sugar factory. The molasses saccharification waste is regenerated and activated in the same way as the sludge from saturation, and the waste thus treated is introduced into the refiner. The sludge from saturation is also regenerated and is introduced into the pre-clarifier. The pre-clarified precipitate is separated by filtration.

Claims (1)

PATENT CLAIMS Method for regenerating saturation sludge in a two-circuit arrangement of a regeneration station, characterized in that in the first water circuit a suspension of saturation sludge with a density of 1010 kg / m ³ up to o 1350 kg / m and at a temperature above 55 ° C is sorted by a vibrating sieve, the pH of the sub-sieve fraction is adjusted to 6.5 to 9.5 with an inorganic acid, gas or other means, after which a solution of reagent is added to the settling particles containing ammonium salts to prevent the passage of the non-sugar liquid from the first circuit to the second circuit, and this newly formed sludge suspension is concentrated and subsequently activated by the addition of lime milk, the liquid separated during concentration being returned to the beginning of the second circuit.