CN104671221A - Method and device for preparing sulphuric acid by taking discharged sulfur dioxide as raw material - Google Patents

Abstract

The invention discloses a method and device for preparing sulphuric acid by taking discharged sulfur dioxide as a raw material. According to the method, discharged sulfur-containing smoke goes into a hydrogen peroxide desulfurizer, generated dilute sulphuric acid goes into a multiple-effect concentration device to prepare concentrated sulfuric acid, and the concentrated sulfuric acid with set concentration can be directly obtained. By utilizing the device, a byproduct of concentrated sulfuric acid can be realized by utilizing hydrogen peroxide method desulfuration, the problem that dilute sulphuric acid in smoke desulfuration industries can not be reused and externally sold is solved, the use range of hydrogen peroxide method desulfuration is broadened, and sulphur resource is completely utilized.

Description

A method and device for producing sulfuric acid from sulfur dioxide emissions

technical field

The invention relates to the fields of sulfuric acid manufacturing, iron and steel, metallurgy, non-ferrous smelting, chemical industry and other industries and environmental protection technology, in particular to a method and a device for producing high-concentration sulfuric acid by hydrogen peroxide method tail gas desulfurization.

Background technique

Sulfuric acid is an important industrial raw material. my country is currently the country with the highest sulfuric acid production in the world. According to the data in 2013, the annual production reached 85 million tons. The industrial production method of sulfuric acid is mainly the contact method, that is, the sulfur raw material is oxidized and burned to generate sulfur dioxide, and the sulfur dioxide is contacted with oxygen in the presence of a catalyst to generate sulfur trioxide. The sulfur trioxide is absorbed with 98.3% concentrated sulfuric acid, and then diluted with water or dilute sulfuric acid to obtain commercial acid.

Sulfur raw materials mainly include sulfur, pyrite, smelting flue gas, etc. In foreign countries, sulfur is mostly used, while in my country, pyrite is the main source. However, my country's sulfur resources are insufficient, and nearly half of the sulfur resources required for sulfuric acid production need to be imported from abroad. On the other hand, nearly 20 million tons of sulfur dioxide is discharged into the atmosphere in the form of industrial waste gas every year in my country, forming air pollutants, which wastes resources and harms the environment at the same time. The existing principle of using smelting flue gas or waste sulfur dioxide to produce acid is still the contact method. In the process of contact oxidation, a large amount of sulfur-containing waste gas will still be generated, resulting in circular pollution. In fact, the sulfur-containing waste gas of the existing acid plant There is also a large proportion of off-gas originating from the contacting step.

Sulfur dioxide is the main pollution factor in air pollutants. The discharge of sulfur dioxide will cause acid rain to acidify and corrode water bodies, crops, environment, buildings, etc., causing huge economic losses. The rapid development of my country's iron and steel, metallurgy, non-ferrous smelting, chemical and other industries has brought serious sulfur dioxide pollution, and the environmental load is unbearable. In recent years, the emission standards of various industries have been tightened step by step, which has brought constraints to the development of various industries.

At present, the treatment of sulfur-containing tail gas mainly includes ammonia method, organic amine method, sodium alkali method, activated coke method, zinc oxide method, hydrogen peroxide method, etc. Among them, the hydrogen peroxide method is one of the wet desulfurization methods developed in recent years, which has the advantages of high desulfurization efficiency, short process and relatively low investment. Among them, the patents related to hydrogen peroxide method for removing sulfur dioxide in flue gas and reclaiming sulfuric acid include CN100463847C, a method for preparing sulfuric acid from flue gas, CN100354028C, a method for removing sulfur dioxide from waste gas by reacting with hydrogen peroxide, and CN202070285U, a method for removing sulfuric acid Sulfur dioxide in industrial tail gas, sulfuric acid recovery unit, etc. The above patents all describe the reaction of hydrogen peroxide (hydrogen peroxide) and sulfur dioxide to produce sulfuric acid, the mechanism and device of the method, but in the actual application process, the by-product is 20-40% dilute sulfuric acid, and there is no industrial sulfuric acid production in some In the equipment industry, this part of dilute sulfuric acid cannot be returned to the sulfuric acid system, or it is difficult to directly sell the dilute sulfuric acid with low concentration, which restricts its comprehensive utilization and affects the scope of application of this method.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies and potential problems existing in the application of the above-mentioned existing hydrogen peroxide method desulfurization in some industries, provide a flue gas desulfurization method and device with stable operation and high-concentration sulfuric acid by-product, and broaden the range of hydrogen peroxide method flue gas desulfurization. The scope of application, solve the problem of low application value of by-products in the current desulfurization technology, and make full use of sulfur resources.

Specifically, the present invention adopts the following technical solutions to solve the above-mentioned problems:

A device for producing sulfuric acid from sulfur dioxide discharge, comprising a hydrogen peroxide desulfurizer and a dilute sulfuric acid concentration device, wherein the dilute sulfuric acid concentration device includes a preheater, a flash chamber and a flash heater, characterized in that the flash chamber and There are at least one set of flash heaters. The first-effect flash heater at the terminal is heated by the terminal saturated steam, while the second-effect flash heater is heated by the flash steam of the first-effect flash chamber as a heat source, and so on, and finally The flash steam of the final effect flash chamber is used as the heat source of the preheater, the dilute sulfuric acid output pipeline of the hydrogen peroxide desulfurizer is connected to the dilute sulfuric acid preheater, and the first effect flash chamber has a concentrated sulfuric acid outlet, which is connected to the concentrated acid cooler connected to output concentrated sulfuric acid.

Preferably, the device also includes a vacuum condenser, a vacuum heat exchanger, a cooler, a liquid seal tank and a return pump, wherein the discharge ends of each effect flash heater are connected to the vacuum condenser to condense into a liquid, and form a system Vacuum, the uncondensed gas in the vacuum condenser is cooled by the vacuum heat exchanger and then sucked and discharged by the vacuum pump. A liquid seal tank is set to keep the vacuum heat exchanger vacuum-tight to realize the vacuum state of the whole system. The liquid condensed in the vacuum condenser is cooled After the device cools down, it enters the liquid seal tank, collects and recovers through the return pump, and uses it as the balance supplementary water for the hydrogen peroxide method desulfurization device, so that there is no discharge of three wastes.

Preferably, the dilute sulfuric acid output pipeline is also provided with a reducer before entering the dilute sulfuric acid preheater, and the reducer is provided with a reducing agent, and the dilute sulfuric acid is contacted with the reductant before entering the dilute sulfuric acid preheater to reduce the dilute sulfuric acid product. Perform restore processing.

The invention also discloses a method for producing sulfuric acid by using discharged sulfur dioxide as a raw material, which is characterized in that the method comprises the following steps: 1) making sulfur-containing flue gas enter a hydrogen peroxide desulfurization tower for desulfurization to generate dilute sulfuric acid; 2) making The generated dilute sulfuric acid enters the sulfuric acid concentrating device to generate concentrated sulfuric acid, and the sulfuric acid concentrating device includes a dilute sulfuric acid preheater and at least one effect flash to generate sulfuric acid of different concentrations.

The concentration of the concentrated sulfuric acid produced can be adjusted in the range of 50-95%, preferably, the concentration of the produced concentrated sulfuric acid is 60-95%, more preferably 93-95%.

Preferably, a step of contacting the generated dilute sulfuric acid with a reducing agent is also included before the generated dilute sulfuric acid enters the sulfuric acid concentration device for concentration in step 2).

Beneficial effects: the method and device of the present invention can greatly reduce sulfur emissions, fully utilize existing sulfur resources, and realize economic and social benefits.

Description of drawings

Fig. 1 is a schematic diagram of the method and device structure of the hydrogen peroxide method tail gas desulfurization and the production of high-concentration sulfuric acid according to the present invention.

In the figure: 1 hydrogen peroxide tank, 2 hydrogen peroxide pump, 3 stabilizer, 4 hydrogen peroxide desulfurizer, 5 circulation absorption pump, 6 reducer, 7 preheater, 8 three-effect flash chamber, 9 three-effect heater, 10 two Effect flash chamber, 11 two-effect heater, 12 one-effect flash chamber, 13 one-effect heater, 14 three-effect circulation pump, 15 two-effect circulation pump, 16 one-effect circulation pump, 17 concentrated acid cooler, 18 vacuum Condenser, 19 vacuum heat exchanger, 20 cooler, 21 liquid seal tank, 22 return pump, 23 vacuum pump, 24 condensate pump.

Detailed ways

The invention discloses a method and device for producing sulfuric acid by using discharged sulfur dioxide as a raw material. The method comprises that the discharged sulfur-containing flue gas enters a hydrogen peroxide desulfurization device, and the produced dilute sulfuric acid enters a multi-effect concentration device to prepare concentrated sulfuric acid. , can directly obtain concentrated sulfuric acid with a set concentration. The device of the present invention can use hydrogen peroxide desulfurization to realize by-product concentrated sulfuric acid, solve the problem that dilute sulfuric acid cannot be reused or sold outside in some flue gas desulfurization industries, broaden the application range of hydrogen peroxide desulfurization, and make full use of sulfur resources.

The technical scheme of the first part of the present invention obtains the by-product of dilute sulfuric acid by the hydrogen peroxide method, and the second part adopts a multi-effect concentration process on the basis of dilute sulfuric acid to prepare concentrated sulfuric acid.

A method and device for producing high-concentration sulfuric acid from tail gas desulfurization by hydrogen peroxide method. The method and device mainly include two steps and two parts. The first step and the first part are hydrogen peroxide desulfurization steps and devices, and the second step and the second part are concentrated sulfuric acid preparation steps and devices.

The first step and the first part include the hydrogen peroxide tank 1, the hydrogen peroxide pump 2, the hydrogen peroxide desulfurizer 4, and the discharge separation and circulation device. The top of the device has an emptying port, and the lower part is a circulation tank, and the circulation tank is connected to the pipeline of the discharge separation and circulation device through the circulation pump 5.

In a preferred embodiment, a stabilizer 3 is also provided in the circulation tank, and the stabilizer is used to make the newly added hydrogen peroxide contact with the stabilizer when the tail gas desulfurization device is initially started or shut down to exert the function of the stabilizer. Stabilization, to achieve the purpose of stabilizing the newly added hydrogen peroxide from decomposing. In one instance, the stabilizer is a pipe opening in the circulation tank and connected at the other end to a source of stabilizer. When needed, the stabilizer source adds the stabilizer to the circulation tank through the opening of the pipeline, and the added stabilizer is contacted with hydrogen peroxide to achieve the purpose of stabilization. In another case, the stabilizer contains a stabilizer for preventing the decomposition of hydrogen peroxide, and when required, the stabilizer is opened so that the stabilizer is released into the circulation tank. In both cases, the stabilizer is released and the stabilizer is brought into contact with hydrogen peroxide. Stabilizers acting in this way may be liquid or solid, eg stabilizer solutions or granular stabilizers.

As the stabilizer, various agents capable of preventing decomposition of hydrogen peroxide can be used. Generally speaking, hydrogen peroxide is relatively stable under weakly acidic and neutral conditions, but activated under alkaline conditions, it will decompose rapidly in the presence of heavy metal ions. The reagents used in the fields related to the application of hydrogen peroxide to prevent the uncontrolled decomposition of hydrogen peroxide are called hydrogen peroxide stabilizers. There are many types of hydrogen peroxide stabilizers, such as adsorption type, chelating type or mixed type, etc., which can isolate heavy metal ions through adsorption and chelation to avoid the impact on hydrogen peroxide products. Commonly used hydrogen peroxide stabilizers include silicon-containing or silicon-free types. Silicon-containing stabilizers include silicates such as sodium silicate and magnesium silicate stabilizers, which have excellent adsorption capacity and good physical and chemical adsorption properties for metal ions, thereby reducing the catalytic effect of metal ions. Silicone-free stabilizers include types such as fatty acid salts. There are also polymer stabilizers, which form a large structure by forming a polymer network structure, have a strong adsorption effect, and can obtain a good adsorption and isolation effect through surface modification. Some commonly used small molecule chelating agents are also commonly used hydrogen peroxide stabilizers, and they can be combined with polymers to obtain a good hydrogen peroxide stabilization effect. Chelating stabilizers are generally polyvalent organic acids or their salts, such as carboxylates, phosphonates, and the like.

In another embodiment, the stabilizer is a stabilizer fixed on a carrier or the stabilizer itself is a polymer solid stabilizer, such as water glass and polyacrylamide stabilizer. In this case, the stabilizer is contained in the stabilizer, and the stabilizer is open or always open when needed, so that the hydrogen peroxide can contact the stabilizer when needed, so as to achieve the purpose of stabilizing the hydrogen peroxide without decomposing.

Hydrogen peroxide stabilizers can be purchased from suppliers, such as the ST-1/2 stabilizer purchased from Jiangsu Chengtian Environmental Protection Technology Co., Ltd., or can be prepared by yourself, such as using EDTA as a chelating agent to stabilize hydrogen peroxide.

The hydrogen peroxide method flue gas desulfurizer includes a desulfurization absorber at the upper part and a circulation tank at the lower part. The hydrogen peroxide in the hydrogen peroxide tank 1 is pumped into the desulfurizer through the hydrogen peroxide pump 2 through the pipeline. After contacting with the flue gas, the tail gas is discharged through the top of the desulfurizer, and The reacted liquid falls into the lower circulation tank. The stabilizer 3 is arranged at the bottom of the circulation tank and buried in the absorption liquid. After the hydrogen peroxide solution is added into the circulation tank at the initial start-up, the purpose of stabilizing the hydrogen peroxide from decomposition is achieved. When driving, put the stabilizer in the stabilizer into the circulation tank at the same time as the hydrogen peroxide preparation solution entering the desulfurizer for the first time or before the hydrogen peroxide, so as to stabilize the hydrogen peroxide preparation solution. And the stabilizer will always circulate in the desulfurizer along with the circulation of the liquid, without additional addition, or it can be added after a period of operation to ensure a certain concentration of the stabilizer in the circulation.

The desulfurization absorber can be in the form commonly used in this field, such as empty tower, packed tower, super gravity machine and other equipment forms, and can adopt one-stage or multi-stage desulfurization absorption according to the actual situation.

Preferably, no matter what type of desulfurization equipment is used, a device for removing dust in the flue gas can be installed, and the removal device is preferably made of non-metallic wire mesh, packing or a combination thereof.

The circulating liquid enters the separation device through the circulating absorption pump 5. The separation device is a separation device commonly used in the hydrogen peroxide desulfurization process, and is used to separate the sulfuric acid produced by desulfurization.

The discharge pipeline of the discharge separation and circulation device is divided into two routes, one is the circulation pipeline for sending the separated hydrogen peroxide solution back to the desulfurizer, the separated hydrogen peroxide-containing liquid continues to the desulfurizer, sprayed down from the top, and the Full exposure to smoke. The other way is the pipeline for transporting the separated dilute sulfuric acid, through which 20-40% dilute sulfuric acid is obtained.

The separated dilute sulfuric acid preferably enters the reducer for treatment before being discharged. The reducer device is set on the dilute sulfuric acid pipeline. The reducer device contains a reducing agent for decomposing residual hydrogen peroxide in the by-product dilute sulfuric acid. The purpose of hydrogen peroxide. If hydrogen peroxide is contained in the sulfuric acid entering the subsequent process, on the one hand, the final product obtained will contain hydrogen peroxide impurities, which will reduce product quality; It is therefore necessary to minimize or even eliminate the concentration of hydrogen peroxide in the feed before dilute sulfuric acid enters the subsequent concentration process. The reducer used to accommodate the reducing agent is a container made of non-metallic material, filled with reducing agent substances that can decompose residual hydrogen peroxide in dilute sulfuric acid, equipped with liquid inlet, liquid outlet and gas discharge port; dilute sulfuric acid containing residual hydrogen peroxide from liquid The inlet enters and sprays on the reducing agent filled inside, the residual hydrogen peroxide is decomposed into water and oxygen, and is emptied from the gas discharge port, and the liquid is discharged from the liquid outlet. The decomposition of hydrogen peroxide is the opposite effect of the aforementioned stabilizing effect, so as long as the agent that can accelerate the decomposition of hydrogen peroxide can be used as the reducing agent used here, it is preferably a fixed catalyst, such as a metal oxide bed, such as containing two The solid bed that the material of manganese oxide catalyst is made, described reductant can also be purchased from businessman, and purchased reductant can be the reductant that reaches the effect of the present invention with various principles, for example purchased from Jiangsu Chengtian Environmental Protection Technology Ltd. ST-1 Reductant.

The second step and the second part, concentrated sulfuric acid preparation method and device, including dilute sulfuric acid preheater 7, flash evaporator 8, 10, 12, flash heater 9, 11, 13, flash circulation pump 14, 15, 16 , Concentrated acid cooler 17, vacuum condenser 18, condensation pump 24, vacuum heat exchanger 19, cooler 20, liquid seal tank 21, return pump 22, vacuum pump 23 and corresponding pipelines. The dilute sulfuric acid obtained in the first step enters the flash chamber after being preheated by the dilute sulfuric acid preheater, and part of the water is flashed out, and the heat is continuously replenished under the action of the flash circulation pump and the flash heater to keep the water in the flash state continuously. According to the needs, one-effect, two-effect, three-effect or multi-effect flash connection can be used to obtain concentrated sulfuric acid products with different concentrations. The concentrated sulfuric acid products are cooled by concentrated acid coolers and stored for sale. The first-effect heat source of the flash heater is saturated steam, the flash steam of the first-effect flash chamber is used as the heat source of the second-effect flash heater, and so on, and the flash steam of the final effect flash chamber is used as the dilute sulfuric acid preheater. The heat source, so multi-effect evaporation, saves heat energy consumption. The discharge end of each effect flash heater is connected to the vacuum condenser, and under the absorption and cooling of the circulating liquid of the condensing pump, it condenses into a liquid and forms a system vacuum; the uncondensed gas of the vacuum condenser is cooled by the vacuum heat exchanger After being sucked and discharged by the vacuum pump, the condensate is discharged into the liquid seal tank, and the discharge nozzle is even immersed below the liquid level of the liquid seal tank; the vacuum pump can be in the form of a water ring vacuum pump, a jet vacuum pump, etc. According to the vacuum pressure level, a liquid seal tank is set to keep the vacuum heat exchanger vacuum-tight, and the liquid seal is cleverly realized by means of the condensate of the condenser and the heat exchanger to realize the vacuum state of the whole system. All the liquid is then returned to the pump for the desulfurizer to be used as supplementary water to realize the infinite circulation of waste without being discharged outside. The liquid produced by the flash evaporation of the method and the device and the condensed liquid of the vacuum heat exchanger are all acid-containing liquids, which are collected and recycled for use as balanced supplementary water for the hydrogen peroxide method desulfurization device, without discharge of three wastes.

The by-product sulfuric acid of the present invention can be adjusted in the range of 50-95% according to requirements, for the convenience of reuse or market sale, preferably 60-95%, more preferably 93-95%.

Among the present invention, multi-effect concentration produces the flow process of vitriol oil as follows:

The dilute sulfuric acid produced by hydrogen peroxide desulfurization is preheated to a certain temperature by using the flash gas of the three-effect flash evaporator as the heat source in the preheater, and then enters the three-effect flash chamber to flash water; in the flash circulation pump and flash heating Under the action of the device, the heat is continuously replenished, and the water in the flash state is continuously discharged. According to the needs, one-stage, two-stage, three-stage or multi-stage flash connection can be adopted to obtain concentrated sulfuric acid products with different concentrations. The concentrated sulfuric acid products are passed through concentrated acid Store in coolers for takeaway. The terminal heat source of the flash heater adopts fresh saturated steam, and the flash steam in the terminal flash chamber is used as the heat source of the previous flash heater, and so on. Multi-effect evaporation saves heat energy consumption; The terminal is connected to the vacuum condenser, and under the absorption and cooling of the circulating liquid of the condensing pump, it condenses into a liquid and forms a system vacuum, so as to maintain the vacuum flash state of the flash chambers at all levels; the uncondensed gas of the vacuum condenser is replaced by a vacuum After the heat exchanger is cooled, it is sucked and discharged by the vacuum pump. According to the vacuum pressure level, a liquid seal tank is set to keep the vacuum heat exchanger vacuum-tight, so as to realize the vacuum state of the whole system. The liquid produced by the flash evaporation of the system device is used as the balance supplementary water of the hydrogen peroxide method desulfurization device, and there is no discharge of three wastes.

The embodiment of the present invention has been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiment, within the scope of knowledge possessed by those of ordinary skill in the art, it can also be done without departing from the gist of the present invention. Various changes.

Claims (6)

1. one kind to discharge the device of sulfurous gas for waste sulfuric acid, comprise hydrogen peroxide devulcanizer and thin sulfuric acid thickener, wherein thin sulfuric acid thickener comprises preheater, flashing chamber and flash heater, it is characterized in that, flashing chamber and flash heater have at least a set of, one effect flash heater of terminal is by the heat supply of terminal saturation steam, and two effect flash heaters imitate the flash steam of flashing chamber as heat supply by one, by that analogy, the flash steam of last end effect flashing chamber is as the thermal source of preheater, the dilute sulphuric acid export pipeline of hydrogen peroxide devulcanizer is connected with dilute sulfuric acid preheater, and an effect flashing chamber has vitriol oil outlet, this outlet is connected to export the vitriol oil with concentrated acid water cooler.

2. as claimed in claim 1 to discharge the device of sulfurous gas for waste sulfuric acid, it is characterized in that, described device also comprises vacuum cooler-condenser, vacuum interchanger, water cooler, liquid seal trough and return pump, the drain side access vacuum cooler-condenser of wherein respectively imitating flash heater is condensed into liquid, and form system vacuum, the not solidifying gas of vacuum cooler-condenser, discharge is attracted through vacuum pump after the cooling of vacuum interchanger, liquid seal trough is set and keeps the vacuum seal of vacuum interchanger, realize whole system vacuum state, the liquid that in vacuum cooler-condenser, condensation produces enters liquid seal trough after supercooler cooling, recovery is collected by returning pump, the supplementary water of balance as peroxide passivation desulfurizer, thus three-waste free discharge.

3. as claimed in claim 1 to discharge the device of sulfurous gas for waste sulfuric acid, it is characterized in that, dilute sulphuric acid export pipeline was also provided with reducer before entering dilute sulfuric acid preheater, be provided with reductive agent in reducer, dilute sulphuric acid first contacted to carry out reduction treatment to this dilute sulphuric acid product with reductive agent before entering dilute sulfuric acid preheater.

4. to discharge the method for sulfurous gas for waste sulfuric acid, it is characterized in that, said method comprising the steps of: 1) make sulfur-containing smoke gas enter hydrogen peroxide thionizer and carry out desulfurization, generate dilute sulphuric acid; 2) make the dilute sulphuric acid of generation enter sulphuric acid concentration device, generate the vitriol oil, described sulphuric acid concentration device comprises dilute sulfuric acid preheater and the sulfuric acid of at least one effect flash distillation work in order to produce different concns.

5. as claimed in claim 4 to discharge the method for sulfurous gas for waste sulfuric acid, it is characterized in that, produce the vitriol oil concentration be 60-95%.

6. as claimed in claim 4 discharge the method for sulfurous gas for waste sulfuric acid, to it is characterized in that, in step 2) dilute sulphuric acid of generation is entered before sulphuric acid concentration device carries out concentrating also comprise the step that the dilute sulphuric acid of generation is contacted with reductive agent.