Sulfur foam liquid salt extraction and acid making coupling process

Abstract

The invention relates to a sulfur foam liquid salt extraction and acid making coupling process, which comprises the following steps: carrying out solid-liquid separation on sulfur foam liquid to obtain a first solid material and a first liquid material, decoloring the first liquid material, and concentrating to obtain a slurry material and a second liquid material; the first solid material and the slurry material are incinerated, and first synthesis gas is obtained and used for preparing concentrated sulfuric acid; and cooling the second liquid material, and centrifuging to obtain ammonium thiocyanate. The sulfur foam liquid is subjected to solid-liquid separation, so that the waste liquid amount is reduced, the equipment volume in the salt extraction area is reduced, and the cost is reduced. An oxidation process in the salt extraction area is canceled, ammonium thiosulfate is subjected to high-temperature concentration and then is subjected to centrifugal separation to obtain crystals, the crystals and the separated ammonium sulfate are sent to the acid making area to be incinerated, and generated tail gas is sent to a desulfurization and denitrification section of a coking plant to be treated, so that emission without solid waste is realized, and maximum utilization of sulfur element and ammonium thiocyanate in sulfur foam liquid is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sulfur foam liquid treatment, and particularly relates to a coupling process for salt extraction and acid production from sulfur foam liquid. BACKGROUND

[0002] In the ammonia desulfurization process of the coking gas purification procedure, desulfurization waste liquid mainly composed of ammonium thiocyanate, ammonium sulfate and thiosulfate is produced. When the by-product salt accumulates to a certain degree (>= 250 g / L), the desulfurization efficiency is greatly reduced, and even the desulfurization tower is blocked, which seriously affects normal production. The desulfurization waste liquid is complex in composition, highly corrosive and large in discharge amount, and is difficult to be harmlessly treated, which has plagued coking enterprises for a long time. When coking plants practice high-quality development and green development, the treatment of desulfurization waste liquid becomes a technical problem to be solved in the coking industry.

[0003] Currently, there are two treatment methods for sulfur foam liquid (containing desulfurization waste liquid): desulfurization waste liquid salt extraction process and sulfur foam mixed desulfurization waste liquid acid production process.

[0004] The desulfurization waste liquid salt extraction process mainly uses step crystallization method to produce ammonium thiocyanate. The desulfurization waste liquid salt extraction process has a long process flow, in addition, the salt extraction process also has the characteristics of large number of equipment and difficult operation. In order to ensure the purity of ammonium thiocyanate product, low-quality sulfur ammonium produced in the separation process is inevitable, and the treatment of low-quality sulfur ammonium has become a problem to be solved in current industrial production.

[0005] The acid production process currently applied more has wet pretreatment acid production process, semi-dry pretreatment acid production process and dry pretreatment acid production process. The raw material sulfur foam liquid (containing desulfurization waste liquid) contains a large amount of nitrogen element, which will inevitably generate nitrogen oxides after incineration. In addition, the by-product dilute sulfuric acid has the disadvantages of high yield, high consumption of fuel coke oven gas and air. SUMMARY

[0006] The purpose of the present application is to provide a coupling process for desulfurization waste liquid salt extraction and acid production, which can reduce the yield of by-product dilute sulfuric acid, simplify the salt extraction process flow and reduce the initial investment.

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is:

[0008] A coupling process for salt extraction and acid production from sulfur foam liquid, comprising the following steps:

[0009] S1, solid-liquid separation of the sulfur foam liquid to obtain first solid material and first liquid material, decolorization treatment of the first liquid material, concentration to obtain slurry material and second liquid material;

[0010] S2, incineration of the slurry material;

[0011] S3, centrifuging the second liquid material after cooling to obtain ammonium thiocyanate.

[0012] Preferably, in step S1, the first liquid material is subjected to decolorization treatment with activated carbon, and then filtered, and the decolorized activated carbon is sent to the coal preparation section for combustion, and the clear liquid is concentrated.

[0013] Preferably, in step S1, the decolorized first liquid material is sent to a concentration kettle, heated to 85°C while maintaining a vacuum state, concentrated, cooled to 60°C after concentration, and then centrifuged to obtain a slurry material and a second liquid material.

[0014] Preferably, in step S2, the first solid material and the slurry material are incinerated together to obtain a first synthesis gas for preparing concentrated sulfuric acid.

[0015] Preferably, in step S2, the first synthesis gas for preparing concentrated sulfuric acid includes the following steps: washing and cooling the first synthesis gas to obtain dilute sulfuric acid and a second synthesis gas; then drying the second synthesis gas, supplementing air, converting SO2 in the second synthesis gas into SO3, using concentrated sulfuric acid to absorb SO3 in the gas, and preparing concentrated sulfuric acid.

[0016] Preferably, the drying of the second synthesis gas includes: using concentrated sulfuric acid to wash and absorb the moisture in the second synthesis gas, and the moisture in the dried second synthesis gas will reach 0.1g / Nm 3 .

[0017] The present application has the following advantages:

[0018] 1) The present application separates the sulfur foam liquid by solid-liquid separation, reduces the amount of waste liquid, reduces the volume of devices and equipment in the salt extraction area, and reduces the cost.

[0019] 2) The oxidation process in the salt extraction area is cancelled, ammonium thiosulfate is separated by high-temperature concentration and centrifugation, and the separated ammonium sulfate is sent to the incineration process in the acid production area, the tail gas is sent to the desulfurization and denitrification section of the coking plant for treatment, realizing no solid waste discharge, simplifying the process flow, and reducing the operation difficulty.

[0020] 3) In the incineration process in the acid production area, the content of the by-product salt in the sulfur foam is reduced, the salt crystallization is reduced, the possibility of pipeline blockage is reduced, the maintenance frequency is reduced, the corrosion effect on the equipment is reduced, and the equipment maintenance frequency is reduced.

[0021] 4) In the incineration process in the acid production area, the content of the by-product salt in the sulfur foam is reduced, the viscosity of the solution is reduced, the mass transfer efficiency is increased, the use frequency of the compressed air blowing pipeline is reduced, and the power consumption is reduced.

[0022] 5) In the acid-making area incineration process, compressed air and coke oven gas enter the incinerator, and the elemental sulfur and other by-products in the sulfur foam liquid are burned at high temperature, the content of by-products is reduced, the consumption of coke oven gas is reduced, the amount of saturated water vapor is reduced, and the production of by-product dilute sulfuric acid is reduced.

[0023] In summary, the coupling process of salt extraction and acid production of the disclosed sulfur foam liquid (containing desulfurization waste liquid) realizes the maximum utilization of sulfur elements and ammonium thiocyanate in the desulfurization waste liquid, and reduces the generation of hazardous waste. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a process flow diagram of the present application. DETAILED DESCRIPTION

[0025] The present application will be further described below in combination with the drawings and specific examples.

[0026] The coupling process of salt extraction and acid production of the present application comprises the following steps:

[0027] S1, solid-liquid separation of the sulfur foam liquid to obtain first solid material and first liquid material, decolorization treatment of the first liquid material, concentration to obtain slurry material and second liquid material;

[0028] Specifically, the sulfur foam liquid is sent to the pretreatment process for solid-liquid separation, and the solid sulfur paste (containing trace salt) containing water ≤10% is separated out and sent to the acid-making area incineration process, and the remaining liquid is sent to the salt extraction area decolorization process. The decolorization process uses activated carbon to decolorize the first liquid material to remove impurities in the solution, and then filters. The decolorized activated carbon is sent to the coking plant for combustion, and the clear liquid is sent to the concentration separation process. The clear liquid is heated to about 85℃ by low-pressure steam while maintaining a vacuum state, and concentrated in the concentration kettle. After concentration, the temperature is reduced to 60℃, and then centrifuged once to obtain slurry material, which is sent to the acid-making area incineration process for combustion. The slurry material is ammonium sulfate and thiosulfate. The clear liquid obtained by the first centrifugation is thiocyanate mother liquor.

[0029] S2, incineration of the slurry material;

[0030] Specifically, the sulfur paste and the concentrated ammonium sulfate and thiosulfate are placed in the incineration furnace of the incineration process, the elemental sulfur and other by-products in the raw material liquid are burned at high temperature, and part of the reaction heat released during combustion is recovered.

[0031] S21, incineration of the first solid material and the slurry material to obtain first synthesis gas for preparing concentrated sulfuric acid;

[0032] More specifically, the high-temperature synthesis gas (containing acid mist, water) formed after incineration is sent to a purification process, and the first synthesis gas, i.e., the high-temperature synthesis gas, is washed with water and dilute sulfuric acid to reduce the temperature of the first synthesis gas to a suitable temperature, remove the acid mist in the first synthesis gas, and the gas out of the purification process is the second synthesis gas, and the liquid is dilute sulfuric acid; the second synthesis gas is further sent to a drying process, and concentrated sulfuric acid is used to wash and absorb the moisture in the second synthesis gas, and after drying, the moisture in the second synthesis gas will reach 0.1 g / Nm 3 After the dried gas is supplemented with air, it is sent to a conversion process;

[0033] In the conversion process, SO2 in the second synthesis gas reacts with oxygen to generate SO3, and a four-stage conversion process is used, and the conversion gas after the third stage of the conversion furnace is sent to a first absorption stage, and the conversion gas after the fourth stage of the conversion furnace is sent to a second absorption stage, and 98% concentrated sulfuric acid is used in the first absorption stage and the second absorption stage to absorb SO3 in the gas, and the tail gas formed after the conversion gas passes through the absorption process enters a tail gas absorption process, and is discharged after being purified by a washing tower and an electric dust remover.

[0034] S3, centrifuging the second liquid material after cooling to obtain ammonium thiocyanate.

[0035] Specifically, the thiocyanate mother liquor is cooled and crystallized to precipitate solid crystals, and ammonium thiocyanate is obtained by secondary centrifugal separation, and the liquid desulfurization clear liquid can be returned to the desulfurization system; the tail gas of each equipment in the salt extraction area is collected to a tail gas treatment system, and after treatment, it reaches the discharge standard and is sent to outdoor venting.

Claims

1. A process for coupling salt extraction and acid production from sulfur foam, characterized in that, The method comprises the following steps: S1, solid-liquid separation of sulfur foam liquid to obtain first solid material and first liquid material, decolorization treatment of the first liquid material, concentration to obtain slurry material and second liquid material; S2, incineration of the slurry material; S3, centrifugation of the second liquid material after cooling to obtain ammonium thiocyanate.

2. The process of claim 1, wherein the sulfur foam liquid brine and acid production coupling process is characterized by, In step S1, the first liquid material is subjected to decolorization treatment by using activated carbon, and then filtration, the decolorized activated carbon is sent to the coal preparation section for combustion, and the clear liquid is concentrated.

3. The process according to claim 1 or 2, characterized in that, In step S1, the decolorized first liquid material is sent into a concentration kettle, heated to 85°C, and concentrated while maintaining a vacuum state, and then cooled to 60°C and separated by centrifugation to obtain slurry material and second liquid material.

4. The process of claim 1, wherein the process is characterized by, In step S2, the first solid material and the slurry material are incinerated together to obtain first synthesis gas for preparing concentrated sulfuric acid.

5. The process of claim 4, wherein the sulfur foam liquid brine and acid coupling process is characterized by, In step S2, the first synthesis gas for preparing concentrated sulfuric acid comprises the following steps: washing and cooling the first synthesis gas to obtain dilute sulfuric acid and second synthesis gas; then drying the second synthesis gas, supplementing air, converting SO2 in the second synthesis gas into SO3, using concentrated sulfuric acid to absorb SO3 in the gas, and preparing concentrated sulfuric acid.

6. The process of claim 4, wherein the process is characterized by, The second synthesis gas drying includes: using concentrated sulfuric acid to wash the moisture absorbed by the second synthesis gas, and the moisture in the dried second synthesis gas will reach 0.1 g / Nm 3 .

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