CN112483760A - Efficient driving method of pipelined dissolution unit for alumina production - Google Patents

Abstract

The invention discloses a high-efficiency driving method of a channelization dissolution unit for alumina production, which comprises the following steps: (1) introducing new steam into the dissolution casing for preheating for half an hour, wherein the temperature of the new steam for preheating is 180 ℃ and 200 ℃, and the pressure is 0.3-0.5MPa, and simultaneously sending the circulating mother liquor into the preheating section of the dissolution casing; (2) when the circulating mother liquor begins to enter the heating section of the dissolution casing, the new steam pressure is increased to 1.0-1.5MPa and the temperature is increased to 230-250 ℃ within 20 minutes; (3) after the filling of the heating section of the dissolution casing is finished, closing a drain valve of the new steam condensate water, and increasing the new steam pressure to 2.0-2.5MPa and the temperature to 280-300 ℃ within 20 minutes; (4) after finishing dissolving out the packing of the staying section of the sleeve, increasing the new steam pressure to 5.5-6.0MPa within 20 minutes, increasing the temperature to 310 ℃, then continuing heating the 11 th-level sleeve of the heating section by the new steam, and normally discharging when the outlet temperature of the 11 th-level sleeve of the heating section is higher than 235 ℃; the method can shorten the start time, avoid the waste of new steam and avoid the alkali carried by the exhausted steam of the flash evaporation system.

Description

Efficient driving method of pipelined dissolution unit for alumina production

Technical Field

The invention relates to the field of alumina production, in particular to a high-efficiency driving method of a channelization dissolution unit for alumina production.

Background

In the process of producing aluminum oxide by using a Bayer process, scabbing is generated due to long-time running of a digestion sleeve for a digestion process, the heat exchange effect is influenced, planned cleaning and maintenance are required, when the vehicle is restarted to recover production after the cleaning and maintenance are finished, a large amount of condensed water is generated by cooling the digestion sleeve before the cleaning and maintenance under a high-temperature condition and is stored in an outer sleeve of a heating section, new steam is introduced for preheating in the starting process to generate 'water hammer', and meanwhile, the sleeve is preheated to heat up too fast to expand with heat and contract with cold, so that the sleeve vibrates, and potential safety production hazards are brought; the traditional solution method is to fill the materials first, and then to start to introduce low-pressure new steam to slowly preheat and drain water after the whole sleeve finishes filling, wherein the preheating and draining can be finished only after a large amount of time is consumed, the operation rate of equipment is influenced, the yield is also influenced, a large amount of new steam is wasted, the system is slowly heated after normal start-up and discharging, and a large amount of exhaust steam of the flash evaporator is dissolved out after discharging.

Disclosure of Invention

In view of the above, the present invention provides a high-efficiency start-up method for a pipelined dissolution unit for alumina production, which can shorten the start-up time, increase the equipment operation rate, increase the yield, avoid the waste of a large amount of new steam in the preheating and temperature raising processes, and avoid a large amount of alkali carried in the exhaust steam of a flash evaporation system during start-up.

The purpose of the invention is realized by the following technical scheme:

a high-efficiency driving method of a canalization digestion unit for alumina production sequentially comprises the following steps:

(1) opening a drain valve of the new steam condensate water, introducing new steam into the dissolution casing for preheating for half an hour, wherein the temperature of the new steam for preheating is 180-200 ℃, and the pressure is 0.3-0.5MPa, and simultaneously conveying the circulating mother liquor into the preheating section of the dissolution casing through a diaphragm pump;

(2) when the circulating mother liquor begins to enter the heating section of the dissolution casing, the new steam pressure is increased from 0.3-0.5MPa to 1.0-1.5MPa within 20 minutes, and the temperature is increased from 180-200 ℃ to 230-250 ℃;

(3) after the filling of the heating section of the dissolution casing is finished, firstly closing a new steam condensate water drain valve, and then increasing the new steam pressure from 1.0-1.5MPa to 2.0-2.5MPa and the temperature from 230-250 ℃ to 280-300 ℃ within 20 minutes;

(4) after finishing the filling of the staying section of the dissolving-out casing, increasing the new steam pressure from 2.0-2.5MPa to 5.5-6.0MPa and the temperature from 280 plus 300 ℃ to 310 ℃ within 20 minutes, opening a discharge valve of a unit to exhaust in order to ensure that the outlet pressure of the 12 th-stage casing of the staying section does not exceed 3.0MPa, then continuously heating the 11 th-stage casing of the heating section by the new steam, and normally discharging when the outlet temperature of the 11 th-stage casing of the heating section is higher than 235 ℃.

The invention has the beneficial effects that:

the efficient driving method of the channelization dissolution unit for producing the aluminum oxide has the following beneficial effects:

(1) preheating and the packing of the digestion sleeve are synchronously carried out, so that the condensed water accumulated in the heating section of the digestion sleeve is discharged before the packing of the heating section of the digestion sleeve is finished;

(2) the method has gentle temperature rise gradient, avoids the vibration caused by expansion with heat and contraction with cold, and effectively eliminates the potential safety hazard of production accidents;

(3) the temperature of the flowing slurry is gradually increased in the filling process, so that the non-flowing slurry is prevented from being heated and preheated after filling is finished, and the problems of uneven cooling and heating and large temperature difference fluctuation of the non-flowing slurry caused by uneven cooling and heating are avoided, so that the method improves the preheating effect, creates favorable conditions for heating and discharging in the heating section, solves the problem that the high-temperature slurry is taken away after the discharging of the dissolution machine set and the temperature of the slurry in the preheating section is increased slowly when the slurry enters the heating section, ensures the stable and continuous heating of the whole system, and avoids the problem that the low-temperature slurry enters the residence section of the dissolution sleeve in the discharging process to cause the flash evaporation system to be difficult to flash evaporation and cause the;

(4) the method shortens the start-up recovery production by at least 2 hours (the traditional start-up recovery production takes at least 4 hours), thereby avoiding the waste of the drainage steam exhaust for at least 2 hours.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail. It should be understood that the preferred embodiments are illustrative of the invention only and are not limiting upon the scope of the invention.

A high-efficiency driving method of a canalization digestion unit for alumina production sequentially comprises the following steps:

(1) opening a drain valve of the new steam condensate water, introducing new steam into the dissolution casing for preheating for half an hour, wherein the temperature of the new steam for preheating is 180-200 ℃, the pressure is 0.3-0.5MPa, simultaneously conveying the circulating mother liquor into a preheating section of the dissolution casing through a diaphragm pump, and the temperature of the circulating mother liquor is more than 130 ℃ after the preheating is finished;

(2) when the circulating mother liquor begins to enter the first pipe of the 11 th-level sleeve of the heating section of the dissolution sleeve, the new steam pressure is increased from 0.3-0.5MPa to 1.0-1.5MPa, and the temperature is increased from 180-200 ℃ to 230-250 ℃ within 20 minutes;

(3) after the filling of the heating section of the dissolution casing is finished, firstly closing a new steam condensate water drain valve, then increasing the new steam pressure from 1.0-1.5MPa to 2.0-2.5MPa within 20 minutes, increasing the temperature from 230-250 ℃ to 280-300 ℃, and then continuously flowing the circulating mother liquor of the heating section to the 12 th-stage casing of the retention section so as to realize the heating of the filling and flowing processes of all dissolution casings;

(4) after finishing the filling of the staying section of the dissolving-out casing, increasing the new steam pressure from 2.0-2.5MPa to 5.5-6.0MPa and the temperature from 280 plus 300 ℃ to 310 ℃ within 20 minutes, opening a discharge valve of a unit to exhaust in order to ensure that the outlet pressure of the 12 th-stage casing of the staying section does not exceed 3.0MPa, then continuously heating the 11 th-stage casing of the heating section by the new steam, and normally discharging when the outlet temperature of the 11 th-stage casing of the heating section is higher than 235 ℃.

According to experiments, when the temperature T and the pressure P of each step are different in the method, the achieved effects are inconsistent, and the method is specifically as follows:

it can be known from the above that the dissolution casing packing and preheating are carried out synchronously, the casing can be preheated in advance to realize drainage, the heating process is fast in temperature rise, and the production recovery start time is shortened by more than 2 hours compared with the start time of the traditional operation mode, so that the waste of the hydrophobic steam for at least 2 hours is avoided, and the start effect of the dissolution casing is improved.

Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.

Claims (1)

1. The high-efficiency driving method of the canalization digestion unit for producing the alumina is characterized by comprising the following steps of: the method sequentially comprises the following steps:

(1) opening a drain valve of the new steam condensate water, introducing new steam into the dissolution casing for preheating for half an hour, wherein the temperature of the new steam for preheating is 180-200 ℃, and the pressure is 0.3-0.5MPa, and simultaneously conveying the circulating mother liquor into the preheating section of the dissolution casing through a diaphragm pump;

(2) when the circulating mother liquor begins to enter the heating section of the dissolution casing, the new steam pressure is increased from 0.3-0.5MPa to 1.0-1.5MPa within 20 minutes, and the temperature is increased from 180-200 ℃ to 230-250 ℃;

(3) after the filling of the heating section of the dissolution casing is finished, firstly closing a new steam condensate water drain valve, and then increasing the new steam pressure from 1.0-1.5MPa to 2.0-2.5MPa and the temperature from 230-250 ℃ to 280-300 ℃ within 20 minutes;

(4) after finishing the filling of the staying section of the dissolving-out casing, increasing the new steam pressure from 2.0-2.5MPa to 5.5-6.0MPa and the temperature from 280 plus 300 ℃ to 310 ℃ within 20 minutes, opening a discharge valve of a unit to exhaust in order to ensure that the outlet pressure of the 12 th-stage casing of the staying section does not exceed 3.0MPa, then continuously heating the 11 th-stage casing of the heating section by the new steam, and normally discharging when the outlet temperature of the 11 th-stage casing of the heating section is higher than 235 ℃.