阅读说明：本技术 一种深度脱除煤气中杂质的方法 (Method for deeply removing impurities in coal gas ) 是由 刘铁牛 聂胜利 叶青保 江年 陶超 何晴 胡林 何成 于 2021-07-06 设计创作，主要内容包括：本发明公开了一种深度脱除煤气中杂质的方法,属于煤气净化相关技术领域。它包括S1、煤气初步脱除焦油；煤气进入含有初脱填料的初脱塔,将煤气中的焦油进行大部脱除,脱除至煤气中含焦油及含尘量不超过30mg/m～(3)。S2、煤气进入精脱塔,精脱塔中装填活性焦；煤气精脱后可作为原料进行使用,后续主要是进入煤气用户,包含但不限于煤压机、煤气制甲醇单元、焦炉煤气制氢单元等。S3、使用含氨气体对精脱塔进行热再生。利用活性焦和氨之间的特性对于煤气进行净化,净化的效果良好。(The invention discloses a method for deeply removing impurities in coal gas, belonging to the technical field related to coal gas purification. The method comprises the steps of S1, primarily removing tar from coal gas; the coal gas enters a primary removing tower containing primary removing filler to remove most of tar in the coal gas until the tar content and the dust content in the coal gas are not more than 30mg/m 3 . S2, feeding the coal gas into a fine removal tower, and filling active coke in the fine removal tower; the refined coal gas can be used as a raw material, and then mainly enters a coal gas user, including but not limited to a coal press, a unit for preparing methanol from coal gas, a unit for preparing hydrogen from coke oven gas and the like. And S3, carrying out thermal regeneration on the fine stripping tower by using ammonia-containing gas. The coal gas is purified by utilizing the characteristics between the active coke and the ammonia, and the purifying effect is good.)

1. A method for deeply removing impurities in coal gas is characterized by comprising the following steps: the method comprises the following steps:

s1, primarily removing tar from the coal gas;

s2, feeding the coal gas into a fine removal tower, and filling active coke in the fine removal tower;

and S3, carrying out thermal regeneration on the fine stripping tower by using ammonia-containing gas.

2. The method for deeply removing impurities in coal gas as claimed in claim 1, wherein the method comprises the following steps: in the step S1, the coal gas enters a primary removing tower containing primary removing filler, and tar in the coal gas is primarily removed.

3. The method for deeply removing impurities in coal gas as claimed in claim 1, wherein the method comprises the following steps: in the step S2, the average particle size of the active coke is 2mm-12 mm.

4. The method for deeply removing impurities in coal gas as claimed in claim 1, wherein the method comprises the following steps: in the step S3, the refined stripping tower after saturation adsorption is regenerated by adding ammonia water into hot purified gas or superheated steam.

5. The method for deeply removing impurities in coal gas as claimed in claim 4, wherein the method comprises the following steps: in the step S3, the hot purified gas specifically includes: leading out the refined coal gas by a draught fan, heating the led-out clean coal gas, spraying a proper amount of concentrated ammonia water, and regenerating the refined tower.

6. The method for deeply removing impurities in coal gas as claimed in claim 5, wherein the method comprises the following steps: in the step S3, the refined coal gas is led out by an induced draft fan, the led-out clean coal gas amount is carried out according to the proportion of 1/20-1/5 of the coal gas amount processed by the refined stripping tower, the led-out clean coal gas is heated to the temperature of 150 ℃ and 400 ℃, then a proper amount of concentrated ammonia water is injected to ensure that the ammonia content in the regenerated clean coal gas reaches 0.05-2%, and the refined stripping tower is regenerated.

7. The method for deeply removing impurities in coal gas as claimed in claim 1, wherein the method comprises the following steps: before the step S1 is executed, the coal gas is subjected to primary purification to remove part of impurities; after the gas is primarily purified, gas-liquid separation of the gas is carried out.

8. The method for deeply removing impurities in coal gas as claimed in claim 7, wherein the method comprises the following steps: the gas-liquid separation of the coal gas is carried out by adopting a gas-liquid separator.

9. The method for deeply removing impurities in coal gas according to any one of claims 1 to 8, wherein the method comprises the following steps: after the step S3 is performed, the regenerated desorption gas is mixed with the gas without removing impurities.

10. The method for deeply removing impurities in coal gas according to any one of claims 1 to 8, wherein the method comprises the following steps: after the step S3 is performed, the finishing tower is cold-blown using a gas not containing ammonia.

Technical Field

The invention belongs to the technical field related to gas purification, and particularly relates to a method for deeply removing impurities in gas.

Background

At present, the blast furnace gas, the coke oven gas, the converter gas, the generator gas and other gases still contain a certain amount of impurities such as hydrogen sulfide, organic sulfur, naphthalene, benzene and the like which are harmful to the subsequent utilization process after being primarily purified, and need to be removed.

The most current methods for removing impurities in the gas include:

firstly, an activated carbon method is adopted, hydrogen sulfide, most organic sulfur and other impurities in coal gas are removed through activated carbon adsorption, and regeneration is carried out through superheated steam or hot inert gas, but activated carbon desulfurization has the problems of low adsorption capacity, easy adsorption saturation, low activated carbon strength, easy blockage and the like under the condition of high regeneration temperature;

secondly, an iron oxide method is adopted, the iron oxide is an old desulfurization method, the normal-temperature iron oxide method can basically remove hydrogen sulfide, when the content of the hydrogen sulfide in the coal gas is high, wet desulfurization and the iron oxide method are combined, and the iron oxide method has an insignificant effect on removing organic sulfur;

thirdly, adopting a Fe (Co) Mo hydrogenation-zinc oxide method, wherein Fe (Co) Mo hydrogenation is a pretreatment measure for organic sulfur in hydrogen-containing raw material gas, particularly, for thiophene-containing gas, the organic sulfur in the raw material can be completely converted into hydrogen sulfide, and the hydrogen sulfide can be removed to be below 0.02ppm by using a zinc oxide desulfurizer, but the reaction conditions of Fe (Co) Mo hydrogenation are harsh, and the operation conditions are as follows: 350-430 ℃, the pressure of 0.7-7.0MPa and the space velocity of 500-2000h-1, wherein the zinc oxide desulfurizer belongs to a transforming agent, namely, hydrogen sulfide is transformed into zinc sulfide, the reaction is easy to saturate, and the required operating temperature is higher and is generally 200-400 ℃;

fourthly, a microcrystal adsorption method is adopted, and the method adopts microcrystal or molecular sieve for adsorption, and is characterized in that the microcrystal and the molecular sieve have pore passages with specific sizes, are suitable for adsorbing impurities with specific sizes such as hydrogen sulfide, naphthalene and the like, but have the problems of pore passage blockage, incomplete regeneration and reduced adsorption and regeneration capacity after long-time operation.

Regarding the removal of impurities in coal gas, the Chinese patent application numbers are: 201810813291.4, publication date is: 2018-11-02, wherein the purification unit is the second iron oxide method mentioned above, the tar recovery unit comprises a gas-liquid separator, a cooling tower, an electrical tar precipitator and a cyclone catcher which are connected in sequence, an ammonia recovery unit is connected behind the cyclone catcher, and the ammonia recovery unit is connected with the gas-liquid separator through a circulating pipeline.

The Chinese patent application numbers are: 201911329580.8, publication date is: 2020-04-17, which relates to the technical field of pyrolysis gas desulfurization and demercuration, in particular to a device and a method for cooperatively controlling and recovering mercuric sulfide in gas; the device structure is as follows: the bottom of the enhanced adsorption oxidation regeneration reactor is provided with a coal gas inlet and a regeneration gas inlet; the upper part of the enhanced adsorption oxidation regeneration reactor is provided with a clean gas outlet and a regeneration gas outlet; the deep separation reactor is connected with a regeneration gas outlet; the sulfur condenser is used for condensing the liquid sulfur in the deep separation reactor; the HgS collector is used for capturing mercury vapor in the deep separation reactor; the deep separation reactor has a heating function; valves are arranged at the inlet of the coal gas inlet, the inlet of the regeneration gas inlet, the outlet of the clean coal gas outlet and the outlet of the regeneration gas outlet. According to the invention, the in-situ generation of sulfur and the fixation of sulfur and mercury are enhanced by adjusting and organizing the H2S adsorption process, so that the removal of sulfur and mercury pollutants in the coal gas is realized, and the resource recovery of the sulfur and mercury is also realized. The desulfurization adsorbent takes a carbon-based porous material or a porous molecular sieve or aluminum oxide as a carrier, and takes a single metal of iron, zinc, manganese, copper or cerium or a composite oxide of the metals as an active component; preferably, the carbon-based porous material is activated carbon or activated coke.

The scheme mainly comprises the following steps: (1) introducing pyrolysis coal gas containing H2S and Hg0 into an enhanced adsorption-oxidation regeneration reactor with a desulfurization adsorbent through a coal gas inlet, and introducing O2 and/or SO2 at the same time, SO as to realize in-situ reduction of H2S on the desulfurization adsorbent at a set temperature, and forming elemental sulfur; meanwhile, Hg0 in the coal gas reacts with sulfur on the surface of the adsorbent to generate HgS which is fixed on a desulfurization adsorbent, and the adsorbed coal gas is discharged from a clean coal gas discharge port; (2) stopping introducing pyrolysis coal gas, introducing regeneration gas through a regeneration gas inlet, heating and purging the adsorbent through the regeneration gas to separate sulfur and HgS solidified on the adsorbent, and introducing the sulfur and the HgS into the deep separation reactor along with the regeneration gas from a regeneration gas outlet. (3) After entering a deep separation reactor, sulfur becomes liquid sulfur at a set temperature, and HgS is decomposed into liquid sulfur and mercury vapor; then the liquid sulfur enters a sulfur condenser for condensation and then is collected; the mercury vapor enters the HgS collector to react with the sprayed cold sulfur powder to form HgS, so that the deep separation and resource recovery of sulfur and HgS are realized.

Although the activated coke used in the adsorbing material is adopted in the patent, the method of reaction after adsorption causes more process raw materials, the flow is long and complicated, and the problems of incomplete regeneration and easy blockage exist.

The Chinese patent application numbers are: 201911378067.8, publication date is: 2020-03-06 'a method for removing sulfides in blast furnace gas', which comprises a cyclone dust collector, a bag-type dust collector and a gas pipeline between the cyclone dust collector and the bag-type dust collector, wherein the gas pipeline is connected with a branch pipe, the branch pipe is provided with a nozzle, the nozzle is connected with a high-pressure nitrogen device, the nozzle sprays a small amount of active coke powder into the gas pipeline through the high-pressure nitrogen for adsorbing sulfides in the blast furnace gas, the adsorbed sulfides enter the bag-type dust collector along with the blast furnace gas, the gas flow velocity in the bag-type dust collector is up to 0.2-0.3m/min, and the active coke has contact time with the blast furnace gas and is used for adsorbing the sulfides in the blast furnace gas by the active coke; the active coke powder produced by screening is resolved and used as an adsorbent, so that the purchase cost is low; mature process equipment such as the existing dry-method bag-type dust removal, dust removal treatment and the like is utilized, so that the investment is reduced, and the risk is reduced; the nitrogen is sprayed in, so that the influence on the components of the blast furnace gas is small. The sulfide is H2S, COS and CS2 in the blast furnace gas, and SO2 is generated along with the combustion of the blast furnace gas. The desulfurizer adopts active coke, and the grain distance of the active coke is 0.5-2 mm. The saturated desulfurizer absorbing sulfide is collected by the bag-type dust collector along with dust, and is discharged by a dust conveying and discharging system of the bag-type dust collector.

The invention adopts the adsorption method to remove the sulfide in the blast furnace gas by using the active coke powder, the active coke powder after saturated adsorption is not regenerated and is directly used as solid waste for treatment, the quantity of the consumed active coke is large, and the power and investment cost is also large.

Disclosure of Invention

1. Problems to be solved

Aiming at the problem that impurities in coal gas are not easy to remove in the prior art, the invention provides a method for deeply removing impurities in coal gas, which can not only effectively remove impurities such as sulfide, organic sulfur, naphthalene, benzene and the like in coal gas, but also effectively regenerate active coke of an adsorbent.

2. Technical scheme

In order to solve the problems, the technical scheme adopted by the invention is as follows:

the invention discloses a method for deeply removing impurities in coal gas, which comprises the following steps:

s1, primarily removing tar from the coal gas; the coal gas enters a primary removing tower containing primary removing filler to remove most of tar in the coal gas until the tar content and the dust content in the coal gas are not more than 30mg/m³。

S2, feeding the coal gas into a fine removal tower, and filling active coke in the fine removal tower; the refined coal gas can be used as a raw material, and then mainly enters a coal gas user, including but not limited to a coal press, a unit for preparing methanol from coal gas, a unit for preparing hydrogen from coke oven gas and the like.

And S3, carrying out thermal regeneration on the fine stripping tower by using ammonia-containing gas.

Activated Coke (AC) is a carbonaceous porous material prepared by pyrolysis-activation of raw coal as a raw material. The specific surface area of the activated coke is small compared to activated carbon. But its intensity is high, and the price is low and pore structure is unique, therefore is applicable to absorption and catalysis effect, and fresh column active coke diameter is 6 ~ 9mm, and length is 5 ~ 12 mm. The key point of the technical application lies in the reasonability of the selection of the cylindrical carbon adsorption material, and the cylindrical carbon adsorption material with the specification of 6-9mm in the active coke needs to be selected as much as possible to adsorb inorganic and organic molecules such as hydrogen sulfide, benzene, naphthalene and the like in the coal gas. Although the molecular sieve or the microcrystalline adsorbent can adsorb, the size of the pore channel is uniform, and only molecules with specific sizes can be adsorbed; although the pore size range of the activated carbon is wide, the activated carbon has low strength, and structural collapse is easy to occur after heating and desorption, so that the resistance is increased and the adsorption capacity is reduced. For the resolution, NH is used₃In the form of coal gas, ammonia gas is used as a reducing agent to be combined with certain active groups in the active coke, and in the next round of adsorption, because the ammonia gas is alkaline, acidic inorganic substances such as hydrogen sulfide and the like in the coal gas can be effectively adsorbed, and organic molecules such as benzene, naphthalene and the like in the coal gas are further adsorbed by adsorbing phenols in the coal gas, and a certain removing effect on organic sulfur is achieved.

The surface groups of the active coke are mostly acidic groups, such as C ═ O, -OH and the like, and form hydrogen bonding or intermolecular adsorption with alkaline ammonia molecules, meanwhile, part of water molecules in the coal gas are adsorbed on the surface of the active coke to form a tiny water molecule film, and the ammonia reacts with the water molecules to generate ammonium hydroxide to form ammonium radical ions in an ionic state, so that the active coke has strong reactivity.

When ammonia exists in the presence of water and ammonia molecules, ammonium ions, hydroxide ions and water molecules exist at the same time, the adsorption and reaction of acidic inorganic substances in the coal gas are strong, hydrogen sulfide, organic sulfur and aromatic hydrocarbon phenols in the coal gas can be well adsorbed and removed, and benzene rings of the phenols have adsorption on benzene and naphthalene in the coal gas. Meanwhile, naphthalene is more active and more polar than benzene, and mainly has electrophilic substitution on naphthalene ring, which is the same as benzene ring, but has stronger activity than benzene ring. Therefore, naphthalene is more easily and completely adsorbed in the environment mainly with polar adsorption, while benzene is adsorbed mainly due to the structural similarity with phenol and naphthalene and the principle of similar phase solubility, so that the adsorption and removal efficiency is lower than that of naphthalene.

In the further description of the present invention, in step S1, the coal gas enters a primary stripping tower containing a primary stripping filler, the primary stripping tower can be filled with multiple layers of cokes with particle size fractions of 8-15mm and 15-30mm to primarily remove the tar in the coal gas, and the cokes in the primary stripping tower can be periodically replaced.

In a further aspect of the present invention, in step S2, the average particle size of the active coke is 2mm to 12 mm. After the fine removal in the fine removal tower, the coal gas contains hydrogen sulfide no more than 10mg/m³Containing benzene no more than 2000mg/m³Containing naphthalene not more than 100mg/m³(ii) a The removal rate of organic sulfur and hydrogen sulfide is not less than 90%.

In the further explanation of the present invention, in step S3, the adsorption-saturated fine stripping tower is regenerated by adding ammonia water to hot purified gas or superheated steam. The adsorption saturation fine desorption tower can adopt gas containing ammonia for desorption, in the gas selection process, thermal purification gas is used, after desorption is completed, the gas can be put into a purification system for cyclic utilization, the superheated steam method is mainly carried out after the regeneration effect of the thermal purification gas is not great for a long time, the active coke filler can be deeply regenerated, and the regeneration temperature is 300-.

The number of the fine stripping towers is generally set to three-opening one-standby regeneration or other forms through calculation so as to ensure that the fine stripping towers with saturated adsorption can have time to regenerate and recover the adsorption capacity under the condition of normal operation.

In a further description of the present invention, in step S3, the hot purified gas specifically includes: leading out the refined coal gas by a draught fan, heating the led-out clean coal gas, spraying a proper amount of concentrated ammonia water, and regenerating the refined tower.

In the further description of the present invention, in the step S3, the refined coal gas is led out by an induced draft fan, the led-out clean coal gas amount is performed according to the proportion of 1/20-1/5 of the coal gas amount processed by the refined stripping tower, the led-out clean coal gas is heated to reach the temperature of 150-.

In the further description of the present invention, before executing step S1, the coal gas needs to be primarily purified to remove part of impurities; after the gas is primarily purified, gas-liquid separation of the gas is carried out. The coal gas is primarily purified, and the sulfur-containing hydrogen sulfide of the coke oven is not higher than 250mg/m after desulfurization, deamination and debenzolization³Contains benzene no more than 4500mg/m³Containing naphthalene not more than 500mg/m³The tar content is not more than 50mg/m³。

In the further explanation of the present invention, gas-liquid separation of gas is performed by using a gas-liquid separator. The gas after primary purification passes through a gas-liquid separator to remove obvious liquid drops in the gas, and the tar content after the gas-liquid separator is not more than 40mg/m³。

In a further description of the present invention, after the step S3 is performed, the regenerated desorption gas is pre-cooled (temperature reduction effect) in a pre-cooling tower and then mixed with the gas without removing impurities. The regenerated gas contains hydrogen sulfide, ammonia, benzene, naphthalene, organic sulfur, etc. and is then mixed with un-impurity-removed coal gas for further impurity removal.

In a further embodiment of the present invention, after the step S3 is performed, the finishing tower is cold-blown with a gas not containing ammonia. After the thermal regeneration is finished, ammonia is not added into the purified gas for regeneration any more, and the adsorption tower is subjected to cold blowing by using the purified gas without ammonia, so that excessive ammonia is prevented from being separated out into the purified gas when the adsorption tower enters the next adsorption period.

3. Advantageous effects

Compared with the prior art, the invention has the beneficial effects that:

(1) according to the method for deeply removing the impurities in the coal gas, the defects of absorption and analysis efficiency reduction caused by micropore blockage in absorption methods such as microcrystal or molecular sieve and the like are avoided by utilizing the characteristics that the activated coke is not easy to block and is easy to activate;

(2) according to the method for deeply removing impurities in the coal gas, when the resistance is increased and the adsorption performance is reduced, superheated steam can be selected for activation to recover the performance of the activated coke;

(3) according to the method for deeply removing the impurities in the coal gas, the strength of the activated coke is far better than that of the activated carbon, so that the defect that the activated carbon loses structural strength and is easy to block and pulverize during regeneration is avoided;

(4) according to the method for deeply removing the impurities in the coal gas, a small coal gas wet desulphurization device can be newly built to treat the analyzed hydrogen sulfide and organic sulfur under the condition that preliminary purification desulphurization is not adopted in the previous procedures such as blast furnace gas, converter gas and the like;

(5) the method for deeply removing impurities in the coal gas adopts an analytic method, has no strict requirement on the temperature of clean coal gas for regeneration, and can achieve satisfactory effect under the condition of slightly low temperature;

(6) according to the method for deeply removing the impurities in the coal gas, the analyzed and generated ammonia, hydrogen sulfide, benzene, naphthalene and other impurities can be returned to the previous desulfurization, deamination and debenzolization unit for adsorption and removal, and no waste gas is generated.

Drawings

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and examples, but it should be understood that these drawings are designed for illustrative purposes only and thus do not limit the scope of the present invention. Furthermore, unless otherwise indicated, the drawings are intended to be illustrative of the structural configurations described herein and are not necessarily drawn to scale.

FIG. 1 is a basic flow chart of a method for deeply removing impurities from coal gas according to the present invention;

Detailed Description

The following detailed description of exemplary embodiments of the invention refers to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration exemplary embodiments in which the invention may be practiced. Although these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that various changes to the invention may be made without departing from the spirit and scope of the present invention. The following more detailed description of the embodiments of the invention is not intended to limit the scope of the invention, as claimed, but is presented for purposes of illustration only and not limitation to describe the features and characteristics of the invention, to set forth the best mode of carrying out the invention, and to sufficiently enable one skilled in the art to practice the invention. Accordingly, the scope of the invention is to be limited only by the following claims.

The detailed description and exemplary embodiments of the invention will be better understood when read in conjunction with the appended drawings, where the elements and features of the invention are identified by reference numerals.

Example 1

As shown in fig. 1, the method for deeply removing impurities from coal gas of this embodiment includes the following steps:

s1, primarily removing tar from the coal gas; the coal gas enters a primary stripping tower containing primary stripping filler, wherein the primary stripping tower can be filled with multilayer coke with the particle size fraction of 8-15mm and 15-30mm to primarily remove tar in the coal gas, the coke in the primary stripping tower can be replaced periodically until the tar and dust content in the coal gas are not more than 30mg/m³。

S2, feeding the coal gas into a fine removal tower, and filling active coke in the fine removal tower; the refined coal gas can be used as a raw material, and then mainly enters a coal gas user, including but not limited to a coal press, a unit for preparing methanol from coal gas, a unit for preparing hydrogen from coke oven gas and the like. The average particle size of the active coke is 2mm-12 mm. After the fine removal in the fine removal tower, the coal gas contains hydrogen sulfide no more than 10mg/m³Containing benzene no more than 2000mg/m³Containing naphthalene not more than 100mg/m³(ii) a The removal rate of organic sulfur and hydrogen sulfide is not less than 90%. The particle size is selected in a narrow interval to reduce the resistance of the whole equipment, and if the particle size interval is too large, different particle sizes are mutually filled, so that the air flow resistance is increased. At the same time smaller particle sizeThe surface area for gas adsorption can be increased.

And S3, carrying out thermal regeneration on the fine stripping tower by using ammonia-containing gas, and regenerating the fine stripping tower after adsorption saturation by adding ammonia water into hot purified gas. The number of the fine stripping towers is generally set to three-opening one-standby regeneration or other forms through calculation so as to ensure that the fine stripping towers with saturated adsorption can have time to regenerate and recover the adsorption capacity under the condition of normal operation. The thermal purification coal gas specifically comprises the following steps: leading out the refined coal gas by using an induced draft fan, wherein the extracted clean coal gas amount is carried out according to the proportion of 1/20-1/5 of the coal gas amount processed by the refined knockout tower, and the specific proportion can be as follows: 1/20, 1/10 or 1/5, etc., the extracted clean gas is heated to the temperature of 150-: 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, etc., for the fine stripping column.

Activated Coke (AC) is a carbonaceous porous material prepared by pyrolysis-activation of raw coal as a raw material. The specific surface area of the activated coke is small compared to activated carbon. But its intensity is high, and the price is low and pore structure is unique, therefore is applicable to absorption and catalysis effect, and fresh column active coke diameter is 6 ~ 9mm, and length is 5 ~ 12 mm. The key point of the technical application lies in the reasonability of the selection of the cylindrical carbon adsorption material, and the cylindrical carbon adsorption material with the specification of 6-9mm in the active coke needs to be selected as much as possible to adsorb inorganic and organic molecules such as hydrogen sulfide, benzene, naphthalene and the like in the coal gas. Although the molecular sieve or the microcrystalline adsorbent can adsorb, the size of the pore channel is uniform, and only molecules with specific sizes can be adsorbed; although the pore size range of the activated carbon is wide, the activated carbon has low strength, and structural collapse is easy to occur after heating and desorption, so that the resistance is increased and the adsorption capacity is reduced. For the resolution, NH is used₃In the form of coal gas, ammonia gas is used as a reducing agent to be combined with certain active groups in the active coke, and in the next round of adsorption, because the ammonia gas is alkaline, acidic inorganic substances such as hydrogen sulfide and the like in the coal gas can be effectively adsorbed, phenols in the coal gas are adsorbed, and the coal gas is further adsorbedOrganic molecules such as benzene and naphthalene in the organic fertilizer have a certain removing effect on organic sulfur.

The surface groups of the active coke are mostly acidic groups, such as C ═ O, -OH and the like, and form hydrogen bonding or intermolecular adsorption with alkaline ammonia molecules, meanwhile, part of water molecules in the coal gas are adsorbed on the surface of the active coke to form a tiny water molecule film, and the ammonia reacts with the water molecules to generate ammonium hydroxide to form ammonium radical ions in an ionic state, so that the active coke has strong reactivity.

When ammonia exists in the presence of water and ammonia molecules, ammonium ions, hydroxide ions and water molecules exist at the same time, the adsorption and reaction of acidic inorganic substances in the coal gas are strong, hydrogen sulfide, organic sulfur and aromatic hydrocarbon phenols in the coal gas can be well adsorbed and removed, and benzene rings of the phenols have adsorption on benzene and naphthalene in the coal gas. Meanwhile, naphthalene is more active and more polar than benzene, and mainly has electrophilic substitution on naphthalene ring, which is the same as benzene ring, but has stronger activity than benzene ring. Therefore, naphthalene is more easily and completely adsorbed in the environment mainly with polar adsorption, while benzene is adsorbed mainly due to the structural similarity with phenol and naphthalene and the principle of similar phase solubility, so that the adsorption and removal efficiency is lower than that of naphthalene.

Example 2

The method for deeply removing impurities from gas in this embodiment is different from embodiment 1 in that after the fine stripping tower is subjected to multiple times of thermal purification gas desorption, the effect of regenerating the thermal purification gas is not great, and steam is used to deeply regenerate the active coke filler in the fine stripping tower, the regeneration temperature is 300-.

Example 3

The method for deeply removing impurities in coal gas comprises the following steps:

s1, primarily purifying the coal gas to remove part of impurities. The coal gas is primarily purified, and the sulfur-containing hydrogen sulfide of the coke oven is not higher than 250mg/m after desulfurization, deamination and debenzolization³Contains benzene no more than 4500mg/m³Containing naphthalene not more than 500mg/m³Containing no more than tar50mg/m³。

And S2, after the gas is primarily purified, carrying out gas-liquid separation on the gas, wherein the gas-liquid separation on the gas is carried out by adopting a gas-liquid separator. The gas after primary purification passes through a gas-liquid separator to remove obvious liquid drops in the gas, and the tar content after the gas-liquid separator is not more than 40mg/m³。

S3, primarily removing tar from the coal gas; the coal gas enters a primary removing tower containing primary removing filler to remove most of tar in the coal gas until the tar content and the dust content in the coal gas are not more than 30mg/m³。

S4, feeding the coal gas into a fine removal tower, and filling active coke in the fine removal tower; the refined coal gas can be used as a raw material, and then mainly enters a coal gas user, including but not limited to a coal press, a unit for preparing methanol from coal gas, a unit for preparing hydrogen from coke oven gas and the like. The average particle size of the active coke is 2mm-12 mm. After the fine removal in the fine removal tower, the coal gas contains hydrogen sulfide no more than 10mg/m³Containing benzene no more than 2000mg/m³Containing naphthalene not more than 100mg/m³(ii) a The removal rate of organic sulfur and hydrogen sulfide is not less than 90%. The particle size is selected in a narrow interval so as to reduce the resistance of the whole equipment, for example, if the particle size interval is too large, different particle sizes are mutually filled, so that the airflow resistance is increased, and meanwhile, the smaller particle size can increase the surface area for gas adsorption.

And S5, carrying out thermal regeneration on the refined tower by using ammonia, and regenerating the refined tower after saturated adsorption by adding ammonia water into hot purified gas. The number of the fine stripping towers is generally set to three-opening one-standby regeneration or other forms through calculation so as to ensure that the fine stripping towers with saturated adsorption can have time to regenerate and recover the adsorption capacity under the condition of normal operation. The thermal purification coal gas specifically comprises the following steps: leading out the refined coal gas by using an induced draft fan, wherein the extracted clean coal gas amount is carried out according to the proportion of 1/20-1/5 of the coal gas amount processed by the refined knockout tower, and the specific proportion can be as follows: 1/20, 1/10 or 1/5, etc., the extracted clean gas is heated to the temperature of 150-: 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, etc., for the fine stripping column.

And S6, precooling the regenerated desorption gas by a precooling tower, and mixing the desorption gas with the coal gas without impurity removal. The regenerated gas contains hydrogen sulfide, ammonia, benzene, naphthalene, organic sulfur, etc. and is then mixed with un-impurity-removed coal gas for further impurity removal.

And S7, cold blowing the refined stripping tower by using ammonia-free coal gas, and after the thermal regeneration is finished, not adding ammonia into the regeneration clean gas any more, and cold blowing the adsorption tower by using ammonia-free clean gas to ensure that excessive ammonia is not separated out into the clean gas when the adsorption tower enters the next adsorption period.

Example 4

The method for deeply removing impurities from gas in this embodiment is different from embodiment 3 in that after the fine stripping tower is subjected to multiple times of thermal purification gas desorption, the effect of regenerating the thermal purification gas is not great, and steam is used to deeply regenerate the active coke filler in the fine stripping tower, the regeneration temperature is 300-.