CN112940821B - Method for improving nitrogen fixation efficiency in coal pyrolysis by using coal ash - Google Patents
Method for improving nitrogen fixation efficiency in coal pyrolysis by using coal ash Download PDFInfo
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- CN112940821B CN112940821B CN202110196773.1A CN202110196773A CN112940821B CN 112940821 B CN112940821 B CN 112940821B CN 202110196773 A CN202110196773 A CN 202110196773A CN 112940821 B CN112940821 B CN 112940821B
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- C—CHEMISTRY; METALLURGY
- 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
- C10L5/00—Solid fuels
- C10L5/02—Solid fuels such as briquettes consisting mainly of carbonaceous materials of mineral or non-mineral origin
- C10L5/04—Raw material of mineral origin to be used; Pretreatment thereof
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B57/00—Other carbonising or coking processes; Features of destructive distillation processes in general
- C10B57/005—After-treatment of coke, e.g. calcination desulfurization
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- C—CHEMISTRY; METALLURGY
- 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
- C10L9/10—Treating solid fuels to improve their combustion by using additives
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Abstract
The invention discloses a method for improving nitrogen fixation efficiency in coal pyrolysis by using coal ash, which comprises the following steps: (1) dissolving water-soluble iron salt and/or water-soluble zinc salt in water to prepare a treatment solution, soaking coal ash burnt by a power plant in the treatment solution for 30-40 min, and drying for later use; (2) mixing a certain amount of raw material coal with the treated coal ash, and pyrolyzing the raw material coal and the treated coal ash under the condition of isolating air to inhibit the separation of nitrogen-containing compound gas in the coal pyrolysis so as to obtain clean pyrolysis gas; (3) and completely soaking the pyrolyzed semicoke or coke in an acid solution for 1-3 h, dissolving out nitrogen in coal into the acid solution, washing to remove coal ash mixed in the coal after soaking, removing most of nitrogen in the coal, and obtaining clean semicoke or coke. The method can reduce the discharge amount of nitrogen oxides in the pyrolysis gas generated in the coal pyrolysis, is simple, has easily controlled process conditions, and has multiple benefits of environmental protection, economy and the like.
Description
Technical Field
The invention relates to the technical field of nitrogen removal in coal pyrolysis, in particular to a method for improving nitrogen fixation efficiency in coal pyrolysis by using coal ash.
Background
Pollutants generated in the coal processing and utilizing process become the largest pollution source causing ecological environment damage, and nitrogen elements enter air in the form of nitrogen oxides and the like in the coal pyrolysis process, so that the pollution control of the earth air is greatly influenced. At present, aiming at the problem of removing nitrogen oxides in flue gas generated by coal pyrolysis, methods such as urea absorption and the like are mainly used, and the methods have the problems of large investment, additional operation equipment and the like.
At present, main pollution of nitrogen oxides in coal pyrolysis flue gas is nitrogen cyanide, and the method is an important method for solving the problems of investment and operation cost and occupied area caused by a flue gas treatment method by reducing hydrogen cyanide or converting more hydrogen cyanide into nitrogen gas in coal utilization. How to simply and efficiently reduce the emission of nitrogen-containing gases such as hydrogen cyanide is a big problem to be solved.
Disclosure of Invention
The invention aims to provide a method for improving nitrogen fixation efficiency in coal pyrolysis by using coal ash, which has the advantages of low investment and low cost.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a method for improving nitrogen fixation efficiency in coal pyrolysis utilizing coal ash, comprising:
(1) dissolving water-soluble iron salt and/or water-soluble zinc salt in water to prepare a treatment solution, soaking coal ash burnt by a power plant in the treatment solution for 30-40 min, and drying for later use;
(2) mixing a certain amount of raw material coal with the treated coal ash, and pyrolyzing the raw material coal and the treated coal ash under the condition of isolating air to inhibit the separation of nitrogen-containing compound gas in the coal pyrolysis so as to obtain clean pyrolysis gas;
(3) and completely soaking the pyrolyzed semicoke or coke in an acid solution for 1-3 h, dissolving nitrogen in the coal into the acid solution, washing to remove coal ash mixed in the solution after soaking, removing most of nitrogen in the coal, and obtaining clean semicoke or coke.
In the above technical scheme, the water-soluble ferric salt in step (1) is one or more of ferric nitrate, ferric sulfate and ferric chloride, and the water-soluble zinc salt is one or more of zinc nitrate, zinc sulfate and zinc chloride.
In the technical scheme, the water-soluble iron salt and/or water-soluble zinc salt in the treatment liquid in the step (1) accounts for 0.1-0.5% of the mass fraction of the coal ash.
In the technical scheme, the coal pyrolysis temperature in the step (2) is 800-1000 ℃.
In the above technical scheme, the mass ratio of the treated coal ash to the raw material coal in step (2) is 1:5 to 10.
In the technical scheme, the acid solution in the step (3) is one or more of hydrochloric acid, sulfuric acid, acetic acid and oxalic acid, and the concentration of the acid solution is 0.1-0.2 mol/L.
In the above technical scheme, the mass ratio of the acid solution to the raw material coal in the step (3) is 1: 10.
the principle of the invention is as follows: the coal ash contains oxides such as iron oxide and aluminum oxide, and after the coal ash is soaked in the treating liquid, more effective components such as iron are added in the coal ash. The coal ash treated by the treatment liquid is mixed in raw material coal, rich substances in the coal ash contain a large amount of cations, and due to the characteristic that a cation outer electron layer is easy to gain and lose electrons and strong oxidizability, and due to the complex synergistic effect of various metals, the treated coal ash can play the roles of fixing nitrogen and inhibiting the generation of nitrogen oxides in the coal pyrolysis process, namely, gases such as HCN and NH precipitated from the coal during pyrolysis 3 The nitrogen-containing gas reacts with the mixed metal addition auxiliary agent to generate nitride, and HCN and NH are inhibited due to the synergistic effect of the mineral substances and the effective components in the coal ash 3 And the generation of harmful gases can fix nitrogen. And (4) eluting the pyrolyzed coal, and removing the mixed coal ash and the generated nitride.
Compared with the prior art, the invention has the following beneficial effects:
1) the efficiency of removing nitrogen in coal is high: the coal ash treated by the treatment fluid is mixed with the pyrolysis coal, so that the emission of nitrogen-containing gas in the pyrolysis gas can be effectively reduced;
2) the influence on the utilization process of the pyrolysis gas after coal pyrolysis is small: the coal ash mixing after the treatment by the treatment liquid can reduce the emission of harmful nitrogen-containing gas in coal pyrolysis, and the pressure of a subsequent device for treating the coal pyrolysis gas is reduced;
3) the technical method has wide applicability: when the treated coal ash is mixed, the coal ash can be used together with the corresponding sulfur-fixing desulfurization type addition auxiliary agent, so that multiple purposes are achieved, the production procedures are reduced, and the universality is high;
4) the required ingredients are readily available: the coal ash used in the invention is the waste coal ash after the combustion in the power plant, which contains a large amount of minerals and natural metal oxides, and provides a new idea for recycling the solid waste coal ash. Meanwhile, in the actual operation, the wet coal preparation method is introduced in the existing process of preparing the semicoke by pyrolysis, only the acid washing process needs to be added into the coal preparation, the coal ash after the nitrogen treatment is fixed can be removed from the coal along with the acid washing solution, and the method can be realized without more additional processes, is simple, mature and effective.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
Adding coal ash treated by a treatment solution into raw material coal, wherein the additive substance contained in the treatment solution is water-soluble iron salt and/or water-soluble zinc salt, and mixing the coal ash treated by the treatment solution and the raw material coal in a ratio of 1: 5-10, putting the mixed coal sample into a high-temperature tube furnace, and pyrolyzing under the condition of isolating air, wherein the coal pyrolysis temperature is 800-1000 ℃.
And (3) acid washing the semicoke pyrolyzed by the aid of an acid solution to remove the mixed coal ash and the fixed nitride, so that nitrogen removal efficiency is improved. The acid comprises any one or a mixture of hydrochloric acid, sulfuric acid, acetic acid and oxalic acid. The concentration of the acid solution is 0.1-0.2 mol/L. The mass ratio of the acid solution to the raw material coal is 1: 10. the acid solution immersion cleaning time is 1-3 h. And washing the acid-washed coal sample with a large amount of water to remove impurity ions introduced into the coal.
The coal coke obtained by the invention can be used as a civil fuel or a coal gasification and liquefaction raw material.
Example 1
Weighing ferric nitrate by using coal ash burnt in a power plant according to the mass fraction of 0.5 percent of the coal ash, and dissolving the ferric nitrate in a proper amount of tap water to prepare the treatment liquid. Soaking coal ash in the treating solution for 40min, and drying. The pyrolysis raw material coal has the total nitrogen content of 0.59 percent and the granularity of less than 0.15 mm. Mixing raw material coal and treated coal ash according to the ratio of 5: 1, and uniformly mixing. 2g of the treated coal sample was loaded on a porcelain boat, which was placed in a high temperature tube furnace and pyrolyzed in the absence of air, at a final pyrolysis temperature of 800 ℃ and held at the final temperature for 30 min. Preparing 0.1mol/L oxalic acid solution, wherein the mass ratio of the oxalic acid solution to raw material coal is 1: and 10, soaking the pyrolyzed coal sample in the water for 2 hours. And (4) carrying out three-wheel water washing on the soaked coal sample, wherein each time of water washing is 10 min. The pyrolysis result shows that the content of nitrogen element in the flue gas is reduced to 2.8 percent from 23.3 percent accounting for the total nitrogen content of the raw material coal, and the nitrogen fixation rate is 87.9 percent.
Example 2
Weighing zinc nitrate by using coal ash burnt in a power plant according to the mass fraction of 0.4 percent of the coal ash, and dissolving the zinc nitrate in a proper amount of clean industrial water to prepare the treatment solution. And (3) soaking the coal ash in the treatment solution for 30min, and drying to obtain the pyrolyzed raw material coal with the total nitrogen content of 0.51% and the particle size of less than 0.15 mm. Mixing the raw material coal and the treated coal ash according to the proportion of 10: 1, and adding a metal additive which is beneficial to sulfur fixation. A porcelain boat was used to carry 3g of the treated coal sample, and the porcelain boat was placed in a high temperature tube furnace and pyrolyzed in the absence of air, with a final pyrolysis temperature of 900 ℃ and held at the final temperature for 30 min. Preparing 0.1mol/L hydrochloric acid solution, wherein the mass ratio of the hydrochloric acid solution to the raw material coal is 1: and 10, soaking the pyrolyzed coal sample in the water for 3 hours. And (4) carrying out three-wheel water washing on the soaked coal sample, wherein each time of water washing is 10 min. The pyrolysis result shows that the content of nitrogen element in the flue gas is reduced to 2.1 percent from 22.3 percent of the total nitrogen content of the raw material coal, the nitrogen fixation rate is 90.6 percent, and simultaneously the content of sulfur element in the flue gas is also reduced.
Example 3
Weighing ferric sulfate by using coal ash burnt in an electric power plant according to the mass fraction of 0.5 percent of the coal ash, and dissolving the ferric sulfate in a proper amount of deionized water to prepare the treatment solution. Soaking coal ash in the treating solution for 30min, and drying. The total nitrogen content of the pyrolyzed raw material coal is 0.45 percent, and the granularity is less than 0.15 mm. Mixing raw material coal and treated coal ash according to the weight ratio of 10: 1, and uniformly mixing. 2g of the treated coal sample was loaded on a porcelain boat, which was placed in a high temperature tube furnace and pyrolyzed in the absence of air, at a final pyrolysis temperature of 1000 ℃ and held at the final temperature for 30 min. Preparing 0.2mol/L acetic acid solution, wherein the mass ratio of the acetic acid solution to the raw material coal is 1: and 10, soaking the pyrolyzed coal sample in the water for 1 h. The pyrolysis result shows that the content of nitrogen element in the flue gas is reduced to 2.2% from 22.1% of the total nitrogen content of the raw material coal, and the nitrogen fixation rate is 81.1%.
Claims (5)
1. A method for improving nitrogen fixation efficiency in coal pyrolysis by using coal ash is characterized by comprising the following steps:
(1) dissolving water-soluble iron salt and/or water-soluble zinc salt in water to prepare a treatment solution, soaking coal ash burnt by a power plant in the treatment solution for 30-40 min, and drying for later use; the water-soluble ferric salt is one or more of ferric nitrate, ferric sulfate and ferric chloride, and the water-soluble zinc salt is one or more of zinc nitrate, zinc sulfate and zinc chloride; the water-soluble iron salt and/or water-soluble zinc salt in the treatment liquid accounts for 0.1-0.5% of the mass fraction of the coal ash;
(2) mixing a certain amount of raw material coal with the treated coal ash, and pyrolyzing the raw material coal and the treated coal ash under the condition of isolating air to inhibit the separation of nitrogen-containing compound gas in the coal pyrolysis so as to obtain clean pyrolysis gas;
(3) and completely soaking the pyrolyzed semicoke or coke in an acid solution for 1-3 h, dissolving out nitrogen in coal into the acid solution, washing to remove coal ash mixed in the coal after soaking, removing most of nitrogen in the coal, and obtaining clean semicoke or coke.
2. The method for improving nitrogen fixation efficiency in coal pyrolysis by using coal ash as claimed in claim 1, wherein the coal pyrolysis temperature in step (2) is 800-1000 ℃.
3. The method for improving nitrogen fixation efficiency in coal pyrolysis by using coal ash according to claim 1, wherein the mass ratio of the coal ash treated in the step (2) to the raw material coal is 1: 5-10.
4. The method for improving nitrogen fixation efficiency in coal pyrolysis by using coal ash as claimed in claim 1, wherein the acid solution in step (3) is one or more of hydrochloric acid, sulfuric acid, acetic acid and oxalic acid, and the concentration of the acid solution is 0.1-0.2 mol/L.
5. The method for improving nitrogen fixation efficiency in coal pyrolysis by using coal ash as claimed in claim 1, wherein the mass ratio of the acid solution to the raw material coal in step (3) is 1: 10.
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