阅读说明：本技术 用于钠法脱硫后处理提取亚硫酸钠产品的反应结晶工艺 (Reaction crystallization process for extracting sodium sulfite product by sodium desulfurization post-treatment ) 是由 望西萍 朱俊杰 王曌 戢宏志 张发有 向荣 于 2020-07-21 设计创作，主要内容包括：本发明公开了用于钠法脱硫后处理提取亚硫酸钠产品的反应结晶工艺。包括反应结晶器(1)、结晶换热器(2)、稠厚器(3)、抗氧化剂槽(4)、离心机(5)、流化床干燥器(6)、除尘器(7)；所述结晶换热器(2)连接所述反应结晶器(1)；所述稠厚器(3)连接所述反应结晶器(1)出口；所述稠厚器(3)上清液自流至抗氧化剂槽(4),下层浓浆流至离心机(5)；所述离心机(5)连接流化床干燥器(6),所述流化床干燥器(6)中废气进入除尘器(7)。本发明采用反应结晶原理,相对于蒸发结晶,操作简单,能源消耗低,运行成本低；结晶清液返塔循环利用,干燥尾气返塔处理,整个工艺不产生二次污染。(The invention discloses a reaction crystallization process for extracting a sodium sulfite product by sodium desulfurization post-treatment. Comprises a reaction crystallizer (1), a crystallization heat exchanger (2), a thickener (3), an antioxidant tank (4), a centrifuge (5), a fluidized bed dryer (6) and a dust remover (7); the crystallization heat exchanger (2) is connected with the reaction crystallizer (1); the thickener (3) is connected with the outlet of the reaction crystallizer (1); the supernatant of the thickener (3) automatically flows to the antioxidant tank (4), and the lower thick slurry flows to the centrifuge (5); the centrifugal machine (5) is connected with a fluidized bed dryer (6), and waste gas in the fluidized bed dryer (6) enters a dust remover (7). The invention adopts the reaction crystallization principle, and has simple operation, low energy consumption and low operation cost compared with evaporative crystallization; the crystallized clear liquid is returned to the tower for cyclic utilization, and the dried tail gas is returned to the tower for treatment, so that the whole process does not produce secondary pollution.)

1. The reaction crystallization equipment for extracting the sodium sulfite product through sodium desulfurization post-treatment is characterized by comprising a reaction crystallizer (1), a crystallization heat exchanger (2), a thickener (3), an antioxidant tank (4), a centrifuge (5), a fluidized bed dryer (6) and a dust remover (7);

the reaction crystallizer (1) is used for crystallizing and separating sodium sulfite crystals from the desulfurization mother liquor through reaction;

the crystallization heat exchanger (2) is connected with the reaction crystallizer (1), and the crystallization heat exchanger (2) is used for keeping the temperature of the reaction crystallizer (1) constant;

the thickener (3) is connected with an outlet of the reaction crystallizer (1), and the thickener (3) is used for solid-liquid pre-separation of precipitated sodium sulfite crystals;

the supernatant of the thickener (3) automatically flows to the antioxidant tank (4), and the lower thick slurry flows to the centrifuge (5);

the centrifugal machine (5) is connected with a fluidized bed dryer (6), and waste gas in the fluidized bed dryer (6) enters a dust remover (7).

2. The reactive crystallization plant for sodium sulfite product extraction for sodium desulfurization post-treatment according to claim 1, characterized in that the centrifuge (5) is a scraper discharge centrifuge, a pusher centrifuge, a plate centrifuge.

3. The reactive crystallization equipment for sodium sulfite product extraction by sodium desulfurization post-treatment according to claim 1, characterized in that the dust collector (7) is a bag dust collector, a cyclone dust collector, a water film dust collector.

4. A reactive crystallization process for sodium sulfite product extraction using the apparatus of any one of claims 1 to 3 for sodium desulfurization post-treatment, characterized by the steps of:

s1: conveying the saturated desulfurization mother liquor absorbed in a sodium desulfurization device into a reaction crystallizer (1) by a slurry discharge pump, keeping the temperature of the reaction crystallizer (1) constant by a crystallization heat exchanger (2), adding a sodium hydroxide solution into the reaction crystallizer (1) under a constant temperature condition, and reacting and crystallizing to separate out sodium sulfite crystal slurry;

s2: the separated sodium sulfite crystal slurry automatically flows into the thickener (3), crystals grow up in the thickener (3) and naturally settle, and solid-liquid pre-separation is carried out; the supernatant automatically flows to an antioxidant tank (4), and the lower thick slurry flows to a centrifuge (5);

s3: periodically adding an antioxidant into the antioxidant tank (4), uniformly mixing the antioxidant with the crystallized clear liquid, and conveying the mixture to a desulfurizing tower for slurry recycling;

s4: the concentrated phase flows to a centrifuge (4), centrifugal dehydration is carried out in the centrifuge (4), the dehydrated product enters a fluidized bed dryer (6), and the anhydrous sodium sulfite product is obtained by hot and cold air drying in the fluidized bed dryer (6);

s5: conveying the dried anhydrous sodium sulfite product to a packaging and stacking system for packaging and stacking; and waste gas discharged from the fluidized bed dryer (6) enters a dust remover, sodium sulfite products entrained in the gas are separated, the separated sodium sulfite products are conveyed to a packaging and stacking system, and the waste gas after dust removal returns to a desulfurizing tower for flue gas purification treatment.

5. The reactive crystallization method for sodium sulfite product extraction by sodium desulfurization post-treatment as claimed in claim 1, characterized in that the concentration of sodium hydroxide solution added to the reactive crystallizer (1) is 20-50%.

6. The reactive crystallization process for sodium sulfite product extraction by sodium desulfurization post-treatment according to claim 1, characterized by the step of adding an antioxidant in the antioxidant tank (4) which is hydroquinone, hydroquinone or ethylenediamine tetraacetic acid.

Technical Field

The invention relates to a recovery process of a byproduct in a sodium desulfurization mother liquor, in particular to reaction crystallization equipment and a method for extracting a sodium sulfite product by sodium desulfurization post-treatment.

Background

The wet desulphurization process, which is the most widely used desulphurization process, accounts for about 85% of the total installed capacity of the world desulphurization. Because of the adaptability of the petrochemical industry to sodium hydroxide, sodium desulphurization is a member of wet desulphurization and is widely applied in the petrochemical industry.

Meanwhile, as the environmental protection requirement is gradually increased in recent years, the traditional sodium-method desulfurization process for generating high-salinity wastewater cannot meet the latest zero-emission requirement, and more mechanisms develop zero-emission processes capable of recovering sodium salt.

The anhydrous sodium sulfite is one of sodium salts, and is widely applied to artificial fiber stabilizers, lignin removing agents in the paper industry, reducing agents in the bleaching and dyeing industry, oxygen inhibitors in the leather industry, photographic developer food additives and the like; the method has wide application and good economic benefit, and is a better byproduct of sodium desulphurization.

At present, evaporation crystallization is mostly adopted for industrially producing anhydrous sodium sulfite, and although the process can produce anhydrous sodium sulfite products with better quality, the device is complex, the number of fault points is large, the energy consumption is high, and the operation cost is high. Meanwhile, due to the particularity of the desulfurization mother liquor, the sodium sulfite in the mother liquor is easy to be oxidized by the original flue gas, so that the product quality is reduced.

Disclosure of Invention

The invention aims to overcome the defects of an evaporative crystallization process and the problem that sodium sulfite is easy to oxidize so as to reduce the purity of a product, and provides reaction crystallization equipment and a method for extracting a sodium sulfite product by sodium desulfurization post-treatment.

The technical solution of the invention is as follows: the reaction crystallization equipment for extracting the sodium sulfite product by sodium desulfurization post-treatment comprises a reaction crystallizer, a crystallization heat exchanger, a thickener, an antioxidant tank, a centrifuge, a fluidized bed dryer and a dust remover;

the reaction crystallizer is used for crystallizing and separating sodium sulfite crystals from the desulfurization mother liquor;

the crystallization heat exchanger is connected with the reaction crystallizer, and the crystallization heat exchanger is used for keeping the temperature of the reaction crystallizer constant;

the thickener is connected with the outlet of the reaction crystallizer and is used for solid-liquid pre-separation of precipitated sodium sulfite crystals;

the supernatant of the thickener automatically flows to an antioxidant tank, and the lower thick slurry flows to a centrifuge;

the centrifugal machine is connected with a fluidized bed dryer, and waste gas in the fluidized bed dryer enters a dust remover.

The centrifuge is a scraper discharge centrifuge, a piston pusher centrifuge or a flat centrifuge.

The dust remover is a bag dust remover, a cyclone dust remover or a water film dust remover.

A reaction crystallization method for extracting sodium sulfite products by sodium desulfurization post-treatment comprises the following steps:

s1: conveying the saturated desulfurization mother liquor absorbed in a sodium desulfurization device into a reaction crystallizer by a slurry discharge pump, keeping the temperature of the reaction crystallizer constant by a crystallization heat exchanger, adding a sodium hydroxide solution into the reaction crystallizer under the constant temperature condition, and reacting and crystallizing to separate out sodium sulfite crystal slurry;

s2: the separated sodium sulfite crystal slurry automatically flows into a thickener, crystals grow in the thickener and naturally settle, and solid-liquid pre-separation is carried out; the supernatant automatically flows to an antioxidant tank, and the lower thick slurry flows to a centrifuge;

s3: periodically adding an antioxidant into the antioxidant tank, uniformly mixing the antioxidant with the crystallized clear liquid, and conveying the mixture to a desulfurizing tower for slurry recycling;

s4: the concentrated phase flows to a centrifuge, centrifugal dehydration is carried out in the centrifuge, the dehydrated product enters a fluidized bed dryer, and the anhydrous sodium sulfite product is obtained after hot and cold air drying in the fluidized bed dryer;

s5: conveying the dried anhydrous sodium sulfite product to a packaging and stacking system for packaging and stacking; the waste gas discharged from the fluidized bed dryer enters a dust remover, sodium sulfite products carried in the gas are separated, the separated sodium sulfite products are conveyed to a packaging and stacking system, and the waste gas after dust removal returns to a desulfurizing tower to be subjected to flue gas purification treatment, so that secondary pollution is avoided.

The desulfurization mother liquor is a mixed solution of sodium bisulfite and sodium sulfite, and can have a certain solid content.

And the reaction crystallizer utilizes the solubility difference and the reaction characteristics of the sodium bisulfite, the sodium sulfite and the sodium hydroxide to crystallize and separate out sodium sulfite crystals.

The reaction crystallizer keeps the temperature constant through a crystallization heat exchanger, and the concentration of the alkali liquor in the sodium hydroxide solution added into the reaction crystallizer can be selected to be 20-50% according to the solid content and the concentration of the desulfurization mother liquor.

The solid content of the lower concentrated phase of the thickener is generally 20-50%.

The antioxidant added in the antioxidant tank can be organic matters such as hydroquinone, p-phenylenediamine, ethylene diamine tetraacetic acid and the like.

The centrifuge can select the forms of a scraper discharging centrifuge, a piston pushing centrifuge, a flat plate centrifuge and other centrifuges according to different crystal grain sizes obtained by the thickener and the automation requirement of the whole system.

The beneficial technical effects of the invention are as follows: by adopting the reaction crystallization principle, compared with evaporative crystallization, the method has the advantages of short process flow, simple operation, low energy consumption and low operation cost; the crystallized clear liquid is returned to the tower for cyclic utilization, and the dried tail gas is returned to the tower for treatment, so that the whole process does not produce secondary pollution; adding an antioxidant system, and adding an organic antioxidant into the slurry to inhibit oxidation of sodium sulfite and sodium bisulfite and improve product quality; the added antioxidants are organic matters, and are easy to separate in the subsequent drying process and the like, so that the quality of the product is not influenced.

Drawings

FIG. 1 is a flow diagram of a reactive crystallization process for sodium desulfurization post-treatment extraction of sodium sulfite product;

in the figure: 1-a reaction crystallizer; 2-crystallization heat exchanger; 3-thickener; 4-antioxidant tank; 5, a centrifugal machine; 6-fluidized bed dryer; 7-dust remover.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The reaction crystallization equipment for extracting the sodium sulfite product by sodium desulfurization post-treatment comprises a reaction crystallizer 1, a crystallization heat exchanger 2, a thickener 3, an antioxidant tank 4, a centrifuge 5, a fluidized bed dryer 6 and a dust remover 7;

the reaction crystallizer 1 is used for crystallizing and separating sodium sulfite crystals from the desulfurization mother liquor;

the crystallization heat exchanger 2 is connected with the reactive crystallizer 1, and the crystallization heat exchanger 2 is used for keeping the temperature of the reactive crystallizer 1 constant;

the thickener 3 is connected with an outlet of the reaction crystallizer 1, and the thickener 3 is used for solid-liquid pre-separation of precipitated sodium sulfite crystals;

the supernatant of the thickener 3 automatically flows to the antioxidant tank 4, and the lower thick slurry flows to the centrifuge 5;

the centrifuge 5 is connected with a fluidized bed dryer 6, and the waste gas in the fluidized bed dryer 6 enters a dust remover 7.

The centrifuge 5 is a scraper discharge centrifuge, a piston pusher centrifuge, or a flat centrifuge.

The dust remover 7 is a bag dust remover, a cyclone dust remover and a water film dust remover.

A reaction crystallization method for extracting sodium sulfite products by sodium desulfurization post-treatment comprises the following steps:

s1: conveying the desulfurization mother liquor which is saturated in the desulfurization device into a reaction crystallizer 1 by a slurry discharge pump, wherein the mother liquor is a saturated sodium bisulfite solution, the temperature of the reaction crystallizer 1 is kept stable by a crystallization heat exchanger 2, a sodium hydroxide solution with a certain concentration is added into the reaction crystallizer 1, and a certain amount of sodium sulfite crystals are separated out by reaction crystallization;

s2: the slurry with a certain amount of separated crystals is left in the thickener 3, the crystals grow in the thickener 3 and naturally settle, and the solid-liquid pre-separation is carried out. The supernatant automatically flows to an antioxidant tank 4, and the lower thick slurry flows to a centrifuge 5;

s3: a certain amount of antioxidant p-phenylenediamine and hydroquinone mixture is periodically added into the antioxidant tank 4, and the mixture is uniformly mixed and then is conveyed to a desulfurizing tower for slurry recycling;

s4: the concentrated phase flows to a centrifuge 5, centrifugal dehydration is carried out in the centrifuge 5, the product after most of water is removed enters a fluidized bed dryer 6, and the product is dried by hot and cold air in the fluidized bed dryer 6 to obtain an anhydrous sodium sulfite product;

s5: and conveying the dried anhydrous sodium sulfite product to a packaging and stacking system for packaging and stacking. And waste gas discharged from the fluidized bed dryer 6 enters a dust remover 7, sodium sulfite products entrained in the separated gas are separated, the separated sodium sulfite products are conveyed to a packaging and stacking system, and the waste gas after dust removal returns to a desulfurizing tower for flue gas purification treatment, so that secondary pollution is avoided.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.