CN112625771A - Washing dechlorination method of chlorine-containing coal - Google Patents
Washing dechlorination method of chlorine-containing coal Download PDFInfo
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- CN112625771A CN112625771A CN202011385398.7A CN202011385398A CN112625771A CN 112625771 A CN112625771 A CN 112625771A CN 202011385398 A CN202011385398 A CN 202011385398A CN 112625771 A CN112625771 A CN 112625771A
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- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L9/00—Treating solid fuels to improve their combustion
- C10L9/02—Treating solid fuels to improve their combustion by chemical means
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Abstract
The invention belongs to the field of coal combustion, and particularly relates to a washing dechlorination method for chlorine-containing coal, which comprises the following steps: (1) dissolving acid and an elution auxiliary agent in water to obtain an eluent, wherein the molar concentration of the weak acid in the eluent is 0.0005-0.05mol/L, and the elution auxiliary agent accounts for 5-20% of the volume of the eluent; (2) crushing chlorine-containing coal to obtain coal powder, mixing the coal powder with the eluent, wherein the mass ratio of the eluent to the coal powder is 10-100, and obtaining a mixed solution; (3) and stirring the mixed solution for 3-12 hours at the temperature of 20-40 ℃, and separating coal powder to finish water washing. The present invention uses weak acid and water as eluent, and H provided by weak acid+The pH value of the eluent can be reduced, the chlorine-containing compounds in the coal can be effectively removed, the organic solvent is added into the eluent as an auxiliary agent, the affinity between the coal and the solvent can be enhanced, the elution rate is further improved, the combination of the organic solvent and the solvent can obviously remove chlorine elements in the chlorine-containing coal, and the quality of the coal is improved.
Description
Technical Field
The invention belongs to the field of coal combustion, and particularly relates to a washing dechlorination method for chlorine-containing coal.
Background
Chlorine is a common harmful element in coal. After being combusted, the chlorine-containing substances of the coal are present in the flue gas in the form of HCl. When the chlorine content in the coal is too high, equipment is corroded during combustion, and the phenomenon of crusting and blocking is caused. Meanwhile, the release of chlorine during the combustion process causes great pollution to the environment. The power plant generally concentrates most of the chloride ions in the flue gas in the desulfurization tower through a wet desulfurization system. For example, CN 111408255A discloses a coal-fired flue gas dechlorination system and a process method, and the method provides that a flue gas dechlorination system is additionally arranged in a tail flue of a power plant, and HCl in flue gas is removed by using an alkaline dechlorinating agent. However, the process can only remove chlorine-containing gas in the tail flue, and cannot effectively avoid the corrosion of HCl to the high-temperature heat exchange wall, such as the corrosion of HCl to the wall surfaces of a water wall, a superheater and a reheater, and the problem cannot be fundamentally solved. Moreover, in the wet desulfurization system, the desulfurization efficiency is gradually reduced along with the enrichment of chloride ions, and the quality of gypsum as a byproduct is also affected. In addition, in order to reduce the concentration of chloride ions in the slurry in the desulfurization tower, a large amount of chlorine-containing wastewater needs to be discharged, and the cost of wastewater treatment is high.
The water washing is a process widely applied to the dechlorination of the fly ash, and can effectively remove the chlorine salt in the waste incineration fly ash. However, compared with chlorine salt in fly ash, chlorine in coal has more complex appearance and is more difficult to remove by washing. CN108531224A discloses a dechlorinating agent for blast furnace gas, a preparation method of the dechlorinating agent and a dechlorinating method, and particularly discloses a dechlorinating agent which is prepared by kneading calcium carbonate, an adhesive and water together, extruding into strips, maintaining the strips in a natural environment overnight and drying at a higher temperature. The reaction of dechlorinating agent to remove hydrogen chloride is essentially gas-solid acid-base neutralization reaction, the hydrogen chloride is a strong acid gas, and oxides, hydroxides and salts of alkali metals and alkaline earth metals have strong affinity with the hydrogen chloride, so that the active components of the dechlorinating agent mainly comprise alkali metal type and alkaline earth metal type. When dechlorination is carried out, 20-25 original particle dechlorinating agents with the length of about 5mm are filled at the lower end of the dechlorination reactor, which is firstly contacted with an air source, and 3-5 ml of granulation dechlorinating agents with the size of 20-40 meshes are filled on the lower end of the dechlorination reactor. However, the technical method also dechlorinates the flue gas after burning coal, and can not effectively avoid the corrosion of HCl to the high-temperature heat exchange wall.
Therefore, there is still a need in the art to develop a simple and effective method for dechlorinating chlorine-containing coal by intensive water washing with low cost and low pollution.
Disclosure of Invention
In view of the above defects or improvement needs of the prior art, the present invention provides a method for water washing and dechlorinating chlorine-containing coal, which aims to increase the leaching of chlorine elements in the chlorine-containing coal through the combined action of weak acid and organic solvent, thereby effectively removing the chlorine elements in the chlorine-containing coal before entering a furnace and preventing the corrosion of a heating surface of the boiler. The detailed technical scheme of the invention is as follows.
A method for water washing dechlorination of chlorine-containing coal comprises the following steps:
(1) dissolving acid and an elution aid in water to obtain an eluent, wherein the molar concentration of the acid in the eluent is 0.0005-0.05mol/L, and the elution aid accounts for 5-20% of the volume of the eluent;
(2) crushing chlorine-containing coal to obtain coal powder, mixing the coal powder with the eluent, wherein the mass ratio of the eluent to the coal powder is 10-100, and obtaining a mixed solution;
(3) and stirring the mixed solution for 3-12 hours at the temperature of 20-40 ℃, and separating coal powder to finish water washing.
Preferably, the acid is one of acetic acid, oxalic acid, citric acid and carbonic acid, and the carbonic acid is formed by introducing saturated carbon dioxide into water.
Preferably, the pH of the eluent is 3.0-4.5.
Preferably, the acid is acetic acid.
Preferably, the elution assistant is one of ethanol and propanol.
Preferably, the elution aid is ethanol.
Preferably, the chlorine in the chlorine-containing coal is 0.25% by mass or more. The method for measuring the total chlorine content in the coal and the coke adopts the Aika mixture molten sample-ion chromatography for measurement according to GB/T3558-2014 measuring method of chlorine in the coal.
The invention has the following beneficial effects:
(1) according to the invention, weak acid and water are mutually soluble to serve as eluent, H & lt + & gt provided by the weak acid can reduce the pH value of the eluent, so that chlorine-containing compounds in coal can be effectively removed, and organic solvent is added into the eluent to serve as an auxiliary agent, so that the affinity between coal and the solvent can be enhanced, the elution rate is further improved, and the combination of the two can obviously remove chlorine elements in the coal containing chlorine, so that the quality of the coal is improved.
(2) The water washing treatment can be carried out at normal temperature and normal pressure, the conditions are mild, the process is simple, the treatment period is short, the matched process parameters of the mass ratio of the eluent to the coal powder being 10-100, the pH value of the eluent being 3.0-4.5 and the like are set, the chlorine removal rate is up to more than 80%, and a very good dechlorination effect is obtained.
(3) The invention can select a plurality of weak acids, has weaker corrosivity and pollution than strong acids, can recycle the eluent and has low wastewater treatment cost.
(4) The mass percent of chlorine in the coal containing chlorine is more than 0.25%, most of the coal belongs to low-chlorine coal or ultra-low-chlorine coal, the chlorine content is between 0.005% and 0.20%, the average value is 0.10%, when the chlorine content in the coal exceeds 0.25%, equipment is corroded in the combustion process, the skinning and blocking phenomena are generated, the corrosion speed of metal is accelerated due to the increase of the chlorine content, and the coal containing high chlorine can be treated by the method, so that the application range of a water washing dechlorination method is expanded, and the method has wide market prospect.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Examples
Example 1
(1) And dissolving a carbonic acid aqueous solution formed by introducing excessive carbon dioxide as an acid and ethanol as an elution auxiliary agent in water, and mixing to obtain an eluent, wherein the pH value of the eluent is 4.0.
(2) Crushing chlorine-containing coal to obtain coal powder, mixing the coal powder with the eluent, wherein the mass ratio of the coal powder to the eluent is 1:50, and obtaining a mixed solution.
(3) And stirring the mixed solution for 3 hours at 25 ℃, and separating coal powder to finish water washing.
Example 2
This example differs from example 1 in that the acid is acetic acid, the molar concentration in the eluent is 0.0005mol/L, the elution aid ethanol, the volume fraction is 5%, as described below.
(1) The method comprises the steps of dissolving acetic acid as an acid and ethanol as an elution aid in water, mixing to obtain an eluent, wherein the molar concentration of the acetic acid in the eluent is 0.0005mol/L, the volume percentage of the ethanol is 5%, and the pH value of the eluent is 4.2.
(2) Crushing chlorine-containing coal to obtain coal powder, mixing the coal powder with the eluent, wherein the mass ratio of the coal powder to the eluent is 1:50, and obtaining a mixed solution.
(3) And stirring the mixed solution for 3 hours at 25 ℃, and separating coal powder to finish water washing.
Example 3
This example is mainly different from example 2 in that the molar concentration of acetic acid in the eluent is 0.05 mol/L.
(1) The method comprises the steps of dissolving acetic acid as an acid and ethanol as an elution auxiliary agent in water, mixing to obtain an eluent, wherein the molar concentration of the acetic acid in the eluent is 0.05mol/L, the volume percentage of the ethanol is 5%, and the pH value of the eluent is 3.1.
(2) Crushing chlorine-containing coal to obtain coal powder, mixing the coal powder with the eluent, wherein the mass ratio of the coal powder to the eluent is 1:50, and obtaining a mixed solution.
(3) And stirring the mixed solution at 25 ℃ for 6 hours, and separating coal powder to finish water washing.
Example 4
This example is mainly different from example 2 in that the molar concentration of acetic acid in the eluent is 0.05 mol/L.
(1) The method comprises the steps of dissolving acetic acid as an acid and ethanol as an elution auxiliary agent in water, mixing to obtain an eluent, wherein the molar concentration of the acetic acid in the eluent is 0.05mol/L, the volume percentage of the ethanol is 5%, and the pH value of the eluent is 3.1.
(2) Crushing chlorine-containing coal to obtain coal powder, mixing the coal powder with the eluent, wherein the mass ratio of the coal powder to the eluent is 1:10, and obtaining a mixed solution.
(3) And stirring the mixed solution at 25 ℃ for 6 hours, and separating coal powder to finish water washing.
Example 5
This example is mainly different from example 2 in that the molar concentration of acetic acid in the eluent is 0.05 mol/L.
(1) The method comprises the steps of dissolving acetic acid as an acid and ethanol as an elution auxiliary agent in water, mixing to obtain an eluent, wherein the molar concentration of the acetic acid in the eluent is 0.05mol/L, the volume percentage of the ethanol is 5%, and the pH value of the eluent is 3.1.
(2) Crushing chlorine-containing coal to obtain coal powder, mixing the coal powder with the eluent, wherein the mass ratio of the coal powder to the eluent is 1:100, and obtaining a mixed solution.
(3) And stirring the mixed solution at 25 ℃ for 6 hours, and separating coal powder to finish water washing.
Example 6
This example differs from example 3 mainly in that the ethanol volume fraction is 10%, as described below.
(1) The method comprises the steps of dissolving acetic acid as an acid and ethanol as an elution auxiliary agent in water, mixing to obtain an eluent, wherein the molar concentration of the acetic acid in the eluent is 0.05mol/L, the volume percentage of the ethanol is 10%, and the pH value of the eluent is 3.3.
(2) Crushing chlorine-containing coal to obtain coal powder, mixing the coal powder with the eluent, wherein the mass ratio of the coal powder to the eluent is 1:50, and obtaining a mixed solution.
(3) And stirring the mixed solution for 3 hours at 25 ℃, and separating coal powder to finish water washing.
Example 7
This example is different from example 3 mainly in the washing time.
(1) The method comprises the steps of dissolving acetic acid as an acid and ethanol as an elution auxiliary agent in water, mixing to obtain an eluent, wherein the molar concentration of the acetic acid in the eluent is 0.05mol/L, the volume percentage of the ethanol is 5%, and the pH value of the eluent is 3.1.
(2) Crushing chlorine-containing coal to obtain coal powder, mixing the coal powder with the eluent, wherein the mass ratio of the coal powder to the eluent is 1:50, and obtaining a mixed solution.
(3) And stirring the mixed solution at 25 ℃ for 6 hours, and separating coal powder to finish water washing.
Example 8
The main difference between this example and example 2 is that the acid is oxalic acid, the molar concentration of oxalic acid in the eluent is 0.0005mol/L, and the volume fraction of ethanol is 10%, as described below.
(1) Dissolving oxalic acid as acid and ethanol as an elution aid in water, and mixing to obtain an eluent, wherein the molar concentration of the oxalic acid in the eluent is 0.0005mol/L, the volume percentage of the ethanol is 10%, and the pH value of the eluent is 3.0.
(2) Crushing chlorine-containing coal to obtain coal powder, mixing the coal powder with the eluent, wherein the mass ratio of the coal powder to the eluent is 1:50, and obtaining a mixed solution.
(3) And stirring the mixed solution for 3 hours at 25 ℃, and separating coal powder to finish water washing.
Comparative examples
Comparative example 1
Mixing the chlorine-containing coal powder with deionized water according to the proportion of 1:50, stirring the mixed solution at 40 ℃ for 12 hours, separating solid from liquid by using a filtering device, and drying the obtained solid to obtain the dechlorinated coal.
Comparative example 2
(1) The method comprises the steps of dissolving acetic acid as an acid and ethanol as an elution aid in water, mixing to obtain an eluent, wherein the molar concentration of the acetic acid in the eluent is 0.0005mol/L, the volume percentage of the ethanol is 5%, and the pH value of the eluent is 3.1.
(2) Crushing chlorine-containing coal to obtain coal powder, mixing the coal powder with the eluent, wherein the mass ratio of the coal powder to the eluent is 1:5, and obtaining a mixed solution.
(3) And stirring the mixed solution for 3 hours at 25 ℃, and separating coal powder to finish water washing.
Comparative example 3
(1) Dissolving oxalic acid as acid and ethanol as an elution auxiliary agent in water, and mixing to obtain an eluent, wherein the molar concentration of acetic acid in the eluent is 0.0001mol/L, the volume percentage of ethanol is 5%, and the pH of the eluent is 4.9.
(2) Crushing chlorine-containing coal to obtain coal powder, mixing the coal powder with the eluent, wherein the mass ratio of the coal powder to the eluent is 1:50, and obtaining a mixed solution.
(3) And stirring the mixed solution for 3 hours at 25 ℃, and separating coal powder to finish water washing.
Test examples
And (4) testing the removal rate of the chlorine element. The determination method comprises the following steps: the method comprises the steps of digesting dechlorinated coal at 180 ℃ by using nitric acid and hydrogen peroxide as digesting agents, measuring the content of chloride ions in obtained leaching filtrate and residual coal digesting solution by using ICP-OES (inductively coupled plasma atomic emission spectrometry), and calculating to obtain the removal rate of chlorine elements in the chlorine-containing coal.
Examples 1 to 6 and comparative examples 1 to 3 were tested, and the test results are shown in Table 1.
Table 1 table of example parameters and test results
As can be seen from the analysis of the data in Table 1, the removal rate of the present invention is far superior to that of the water washing method as can be seen from examples 1 to 8 and comparative example 1. As is clear from examples 3, 4 and 5 and comparative example 2, the liquid-solid mass ratio is preferably 10 or more. As is clear from examples 2 to 3 and comparative example 3, the molar concentration of the acid in the eluent is preferably 0.0005 to 0.05mol/L, and the pH is preferably 4.5 or less.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (7)
1. The method for water washing dechlorination of the chlorine-containing coal is characterized by comprising the following steps of:
(1) dissolving acid and an elution aid in water to obtain an eluent, wherein the molar concentration of the acid in the eluent is 0.0005-0.05mol/L, and the elution aid accounts for 5-20% of the volume of the eluent;
(2) crushing chlorine-containing coal to obtain coal powder, mixing the coal powder with the eluent, wherein the mass ratio of the eluent to the coal powder is 10-100, and obtaining a mixed solution;
(3) and stirring the mixed solution for 3-12 hours at the temperature of 20-40 ℃, and separating coal powder to finish water washing.
2. The water washing dechlorination method according to claim 1, wherein the acid is one of acetic acid, oxalic acid, citric acid and carbonic acid, and the carbonic acid is formed by introducing saturated carbon dioxide into water.
3. The aqueous dechlorination process of claim 2 wherein the eluent has a pH of from 3.0 to 4.5.
4. The aqueous dechlorination process of claim 3 wherein the acid is acetic acid.
5. The water-washing dechlorination method according to claim 2, wherein the elution assistant is one of ethanol and propanol.
6. The aqueous dechlorination process of claim 5 wherein the elution aid is ethanol.
7. The water washing dechlorination method according to claim 1, wherein the percentage by mass of chlorine in the chlorine-containing coal is 0.25% or more.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2106934A (en) * | 1981-09-19 | 1983-04-20 | Coal Ind | Method of dechlorinating coal |
| CN105238488A (en) * | 2015-09-30 | 2016-01-13 | 华中科技大学 | Coal dealkalization method |
| CN106281565A (en) * | 2016-09-06 | 2017-01-04 | 哈尔滨工业大学 | A kind of method of high sodium Coal pretreatment |
| US20170152455A1 (en) * | 2012-06-03 | 2017-06-01 | Emmanouil Koukios | Method of production of fuels from biomass, from low quality coals and from wastes, residues and sludges from sew age treatment plants |
-
2020
- 2020-12-01 CN CN202011385398.7A patent/CN112625771A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2106934A (en) * | 1981-09-19 | 1983-04-20 | Coal Ind | Method of dechlorinating coal |
| US20170152455A1 (en) * | 2012-06-03 | 2017-06-01 | Emmanouil Koukios | Method of production of fuels from biomass, from low quality coals and from wastes, residues and sludges from sew age treatment plants |
| CN105238488A (en) * | 2015-09-30 | 2016-01-13 | 华中科技大学 | Coal dealkalization method |
| CN106281565A (en) * | 2016-09-06 | 2017-01-04 | 哈尔滨工业大学 | A kind of method of high sodium Coal pretreatment |
Non-Patent Citations (2)
| Title |
|---|
| ZHAO XIONG等: ""A novel CO2-water leaching method for AAEM removal from coal:Suppression of PM formation and release during Zhundong coal combustion"", 《FUEL》 * |
| 田琳等: ""酸洗预处理对飞灰中氯和重金属脱除的影响规律"", 《环境卫生工程》 * |
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