KR20040106182A - Apparatus for the production of ammonium thiocyanate from the coke oven by-product acid gas - Google Patents

Abstract

PURPOSE: Provided is an equipment for producing high purity ammonium thiocyanate(NH4SCN) from high concentration ammonium thiocyanate solution without a special purification process and forming sulfur by oxidizing H2S in acidic gas without sulfur-slurry preparation. CONSTITUTION: The equipment for producing NH4SCN comprises the parts of: a condenser(12) for cooling and condensing an acidic gas, and oxidizing H2S in the acidic gas by using vapor, wherein the acidic gas consists of 35% of NH3, 9% of H2S, 2% of HCN, 28% of CO2 and 48% of H2O; an oxidizing tower(13) oxidizing H2S in the acidic gas under supply of air to form sulfur reacting with HCN in the acidic gas; a first evaporator(14) vaporizing water from the solution, provided by condenser and oxidizing tower, to precipitate impurities; a filter(15) to separate precipitates(mainly sulfur) from the NH4SCN solution; a second evaporator(16) vaporizing the NH4SCN solution to form NH4SCN crystals; a centrifuge to separate NH4SCN crystals; a dryer to dry formed NH4SCN crystals.

Description

Apparatus for the production of ammonium thiocyanate from the coke oven by-product acid gas}

The present invention relates to a process for producing ammonium thiocyanate from coke plant by-product acid gas, and more particularly, to prepare a high concentration of ammonium thiocyanate from acid gas, which is a by-product gas of coke plant. Ammonium thiocyanate manufacturing apparatus that enables to manufacture ammonium thiocyanate, and to reduce the production cost of sulfur slurry by oxidizing hydrogen sulfide present in the acid gas itself to produce sulfur. It is about.

Ammonium thiocyanate is used as a raw material for pesticides, medicines and dyes, and ammonium thiocyanate is a coke gas and sulfur slurry during the coke production process in the process of refining the coke gas generated from the coke for use as fuel gas. There was a process for making contact by.

However, as the coke gas purification process changed, acid gas was generated as a by-product in the process of removing impurities to use coke gas as fuel. The gas generated when distilled after absorbing hydrogen sulfide and hydrogen cyanide which are acidic and causing pollution in aqueous solution with alkaline ammonia in this coke gas. .

However, ammonia, hydrogen sulfide, and hydrogen cyanide are present in higher concentrations in the coke gas, and when the ammonium thiocyanate is produced therefrom, the production equipment can be simplified and the impurities content can be reduced. The process for producing ammonium thiocyanate disappeared and was replaced by a process from acidic gas.

A conventional process for producing ammonium thiocyanate from the acidic gas will be described in detail with reference to FIG. 1 as follows.

The aqueous solution which collects water-soluble substances such as hydrogen sulfide, ammonia and hydrogen cyanide from the coke gas is treated in a distillation column (not shown in the drawing), and the acid gas generated in the distillation column is treated in the Klaus process, and the acid gas (AG1) shown in FIG. Is withdrawn before the claus process and unreacted excess gas (AG2) is returned to the original piping for processing in the claus process.

In the conventional process for producing ammonium thiocyanate, powdered sulfur 2 is mixed with water 3 to produce a sulfur slurry 2a for reacting with acid gas AG1, as shown in FIG. The sulfur slurry 2a prepared here is in primary contact with the acidic gas AG1 in the primary reactor 4 and in secondary contact with the secondary reactor 5. The supply amount of the sulfur slurry (2a) should be supplied only as much as the final amount of sulfur is completely consumed in the secondary reactor (5), if the sulfur solids remain in the evaporator (6) will cause clogging phenomenon. At this time, the concentration of the solution discharged from the secondary reactor 5 is about 20%.

On the other hand, the evaporator (6) is evaporated to condense the water and the final discharged concentrated ammonium thiocyanate (7) solution is 50%. The concentrated ammonium thiocyanate (7) undergoes further purification and is commercialized and sold in solution or crystalline form.

However, in such a conventional manufacturing process, a solution having a high concentration cannot be obtained because there is no concentration function of the reactor, and a solution having a relatively high content of impurities is thus obtained because there is no function to filter out impurities in an acid gas. There are inherent disadvantages that can be commercialized only after complex secondary purification.

In addition, in the conventional manufacturing process, there is a problem in that a sulfur slurry manufacturing process is difficult to handle because the sulfur slurry has to be supplied separately to the reactor, and another problem in this process is due to the tar mixed with the acid gas. It is necessary to clean the tar.

Therefore, the present invention has been made to solve the above problems, the present invention is to prepare a high concentration of ammonium thiocyanate solution to prepare a high-purity ammonium thiocyanate without additional purification process, acidic gas The present invention provides an ammonium thiocyanate production apparatus that can reduce manufacturing costs by oxidizing hydrogen sulfide present in the sulfur to generate sulfur, thereby eliminating a separate sulfur slurry manufacturing process.

1 is a conceptual diagram showing a process for producing ammonium thiocyanate from an acid gas according to the prior art

2 is a conceptual diagram showing a process for producing ammonium thiocyanate from an acid gas according to an embodiment of the present invention;

11 acidic gas 12 condenser

13: oxidation tower 14: primary evaporator

15 filter 16: secondary evaporator

17 centrifuge 18 dryer

19a, 19b: air 21: cracking furnace

22a, 22b: steam

In order to achieve the above object, the present invention comprises a condenser for oxidizing hydrogen sulfide in the acid gas by using a vapor containing some air while receiving and cooling and condensing the acid gas; An oxidation tower for supplying quantitative air for oxidizing hydrogen sulfide in the acid gas to oxidize hydrogen sulfide in the acid gas so as to generate sulfur enough to react with hydrogen cyanide contained in the acid gas; A primary evaporator for depositing impurities while evaporating water from the solution provided by the condenser and the oxidation tower; A filter for removing impurities precipitated in the solution in the first evaporator and passing the thiocyanammonium solution; A second evaporator for evaporating water from the impurity-free ammonium thiocyanate solution while passing through the filter to form ammonium thiocyanate crystals; A centrifuge for separating the ammonium thiocyanate crystal produced in the secondary evaporator; An apparatus for producing ammonium thiocyanate using an acid gas composed of a dryer for drying the centrifuged ammonium thiocyanate crystal is provided.

Hereinafter, an embodiment of the present invention will be described in detail.

2 is a conceptual diagram of an ammonium thiocyanate production apparatus using an acid gas according to an embodiment of the present invention. The ammonium thiocyanate production apparatus according to the present invention condensates the acid gas (11) while condensing while receiving the acid gas (11). 12), an oxidation tower 13 for oxidizing hydrogen sulfide using air 19, a primary evaporator 14 for precipitating impurities while evaporating water from a solution, and impurities precipitated in a solution of the primary evaporator. A filter 15 to be removed, a secondary evaporator 16 for producing ammonium thiocyanate crystals from the solution filtered by the filter, a centrifuge 17 for separating the crystals produced in the secondary evaporator, and centrifugation It consists of a dryer 18 for drying the crystals.

On the other hand, the air 19b supplied to the oxidizing tower supplies an amount to oxidize hydrogen sulfide so as to generate sulfur enough to react with hydrogen cyanide contained in the acid gas, where all of the hydrogen sulfide is absorbed to form the oxidizing tower. It is not allowed to escape. Therefore, since the gas leaving the oxidizing tower does not contain hydrogen sulfide at all, the gas decomposed in the decomposition furnace 21 does not contain any pollutant component, so that the gas can be released as it is. In addition, hydrogen sulfide remaining without being oxidized by the air supplied to the oxidation tower is oxidized by supplying air 19a while evaporating some water in the primary evaporator 14 to generate sulfur solids, and sulfur is a filter ( In 15). Air is supplied from the primary evaporator 14, and the steam 22a containing some air generated therein is combined with the acidic gas 11 to be supplied to the condenser 12, thereby simultaneously oxidizing hydrogen sulfide in the condenser 12. It is possible to increase the oxidation efficiency of the hydrogen sulfide in the acid gas 11 and at the same time increase the absorption efficiency. Here, in order to increase the absorption efficiency of the hydrogen sulfide, the air 19b supplied to the oxidation tower 13 and the air supplied together with the steam 22b from the secondary evaporator 6 are combined with the hydrogen cyanide to react with a slight excess. Sufficient air must be supplied to produce sulfur. However, in this case, if too much solid sulfur is present in the condenser 12 and the oxidation tower 13, it is necessary to prevent the supply of too much excess air because it may cause clogging of the pipe.

On the other hand, the primary evaporator 14 is concentrated to the extent that some ammonium thiocyanate is precipitated, and most of the impurities are ammonium thiocyanate because the solubility in water is very high and the other impurities are lower in solubility than ammonium thiocyanate. When this precipitates and the solution passes through the filter 15 of the next stage, an ammonium thiocyanate solution having a very high purity is obtained.

This solution evaporates water in a secondary evaporator 16 to produce crystals, which are separated in a centrifuge 17 and then dried in a dryer 18 to form a product.

At this time, the waste liquid of the centrifuge 17 is circulated back to the primary evaporator 14 and processed again according to the same principle as described above.

On the other hand, the solid material filtered by the filter 15 is sulfur as the main component and sulfur is shipped as another product.

<Example>

Hydrogen sulfide using condenser 12 and air 19b for cooling and condensing with acidic gas containing NH ₃ 35%, H ₂ S 9%, HCN 2%, CO ₂ 28%, H ₂ O 48% An oxidizing tower (13) for oxidizing water, a primary evaporator (14) for precipitating impurities while evaporating water from the solution, a filter (15) for removing deposits from the primary evaporator, and ammonium thiocyanate crystals from the solution The ammonium thiocyanate was produced in the apparatus which consists of the secondary evaporator 16 which produces | generates, the centrifuge 17 which isolate | separates the crystal | crystallization produced in the secondary evaporator, and the dryer 18 which dries the separated crystal | crystallization. . The acid gas treatment capacity was 1500 L / h and the ammonium thiocyanate (NH ₄ SCN) was 100 kg / h, and the purity of the produced ammonium thiocyanate (NH ₄ SCN) was 95%.

According to the treatment process according to the present invention, because it has its own oxidation treatment equipment to oxidize hydrogen sulfide, it can simultaneously perform two functions of hydrogen sulfide treatment and ammonium thiocyanate production, and when used in place of the existing Klaus process Economic effects can be expected.

In addition, the main constituents of gas generated in the oxidation tower are carbon dioxide and ammonia, which do not cause any pollution when decomposed in the decomposition furnace and discharged into the atmosphere, and thus does not cause environmental problems. It is available.

In addition, according to the present invention, since the conventional Klaus process processes steam of 75 [° C.] or more, it contains a large amount of water vapor, which requires an additional capacity corresponding to the capacity thereof, but in the treatment process according to the present invention, gas is used. Since the temperature can be lowered to room temperature, the water vapor content is low, and the size of the cracking furnace can be made smaller than that of the Klaus process.

Claims (1)

A condenser 12 which takes in the acid gas and oxidizes hydrogen sulfide in the acid gas using steam containing some air while cooling and condensing the acid gas; An oxidation tower 13 for oxidizing hydrogen sulfide in the acid gas by receiving a quantity of air for oxidizing hydrogen sulfide in the acid gas so as to generate sulfur enough to react with hydrogen cyanide contained in the acid gas; A primary evaporator (14) for depositing impurities while evaporating water from the solution provided by the condenser and the oxidation tower; A filter (15) for removing impurities deposited in the solution in the primary evaporator and passing the thiocyanate ammonium solution; A secondary evaporator 16 for evaporating water from the impurity-free ammonium thiocyanate solution while passing through the filter to produce ammonium thiocyanate crystals; A centrifuge (17) for separating the ammonium thiocyanate crystal produced in the secondary evaporator; Ammonium thiocyanate production apparatus using an acid gas, characterized in that consisting of a dryer (18) for drying the centrifuged ammonium thiocyanate crystals.