CN112779072A

CN112779072A - Decoking agent and preparation method thereof

Info

Publication number: CN112779072A
Application number: CN202110052749.0A
Authority: CN
Inventors: 徐四青
Original assignee: Langfang Yitai Chemical Building Materials Co ltd
Current assignee: Langfang Yitai Chemical Building Materials Co ltd
Priority date: 2021-01-15
Filing date: 2021-01-15
Publication date: 2021-05-11
Anticipated expiration: 2041-01-15
Also published as: CN112779072B

Abstract

The invention discloses a decoking agent, which comprises the following raw materials in parts by weight: 80-120 parts of solvent, 0.1-2 parts of high-temperature retention agent, 1-10 parts of nitrate and 8-15 parts of auxiliary agent. Wherein the nitrate is potassium nitrate, cupric nitrate, magnesium nitrate and aluminum nitrate; the auxiliary agent is a compound mixed acid of hydrochloric acid, hydrofluoric acid and nitric acid; the prepared decoking agent has good ash removal decoking efficiency, low corrosivity and good boiler thermal efficiency improvement effect, is suitable for popularization in the field of boiler decoking, and has wide development prospect.

Description

Decoking agent and preparation method thereof

Technical Field

The invention relates to the field of boiler decoking, in particular to a decoking agent and a preparation method thereof.

Background

Due to high heat intensity and high combustion temperature, the coal-fired boiler is easy to form serious coking and dust deposition under the influence of various complex factors such as unreasonable boiler design, improper operation, coal quality change and the like. In the process of coal combustion, due to ash and coking on the heating surface, the heat exchange efficiency of the boiler is reduced, the exhaust gas temperature is increased, and the energy consumption is increased. And the heating surface is easy to generate sulfate corrosion due to coking seriously, and the service life of the boiler is shortened. Both of these problems can seriously affect the safe operation of the boiler.

At present, two methods of manual ash removal and decoking or chemical decoking are generally adopted for the ash removal and the decoking of industrial boilers and large-scale power station boilers. The back of the radiation heating surface and the back of the convection heating surface of the boiler cannot be cleaned by manually cleaning ash and removing coke, so that the use requirement cannot be met, and the normal production operation is influenced. A specific chemical agent (decoking agent) is added in the boiler and reacts with substances in the ash, so that the accumulated ash and coking on the heating surface can be removed, the dual effects of removing and preventing are achieved, and the safe and economic operation of the boiler is ensured.

Chemical decoking agents are commonly used in industry, and at present, the chemical decoking agents mainly comprise a solid type and a liquid type. The addition amount of the solid-state decoking agent is generally more than five thousandth of the coal burning amount, and the cost is higher. The liquid-state decoking agent has the advantages of small addition amount, small solid content of chemical reagent, low cost, no dead angle after being sprayed into a hearth and the like; the decoking agent in the prior art generally has a better decoking effect, but the coke inhibiting effect is not very obvious.

The coal ash component is the most significant cause of slagging, fouling and char formation. Therefore, it is a significant task to develop a decoking agent that can affect the structure of the coal ash to inhibit boiler slagging, fouling and coking.

Disclosure of Invention

In order to solve the problems, the invention provides a decoking agent in a first aspect, which comprises the following raw materials in parts by weight: 80-120 parts of solvent, 0.1-2 parts of high-temperature retention agent, 1-10 parts of nitrate and 8-15 parts of auxiliary agent.

As a preferred scheme, the raw materials comprise the following parts by weight: 85-95 parts of solvent, 0.5-1 part of high-temperature retention agent, 4-8 parts of nitrate and 9-12 parts of auxiliary agent.

As a preferred embodiment, the solvent is deionized water.

In a preferred embodiment, the high-temperature retention agent is at least one of boric acid and borax.

In a preferred embodiment, the high temperature retention agent is boric acid.

In a preferred embodiment, the nitrate is at least one of potassium nitrate, sodium nitrate, magnesium nitrate, aluminum nitrate, and copper nitrate.

In a preferred embodiment, the auxiliary agent is at least one of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, perchloric acid, and hypochlorous acid.

In a preferred embodiment, the auxiliary agent is hydrochloric acid, hydrofluoric acid, and nitric acid.

As a preferable scheme, the volume ratio of the hydrochloric acid to the hydrofluoric acid to the nitric acid is 2-3: 1-2: 5 to 7.

The second aspect of the present invention provides a method for preparing the above decoking agent, comprising the following steps: (1) adding a high-temperature retention agent into a solvent, stirring and mixing completely, then adding nitrate into the solvent, stirring for 20-30 minutes, and dissolving completely to obtain a mixed solution; (2) and (2) slowly introducing the assistant into the mixed liquid obtained in the step (1), and slowly stirring for 10-20 minutes to obtain the decoking agent.

Has the advantages that:

1. according to the invention, the compound auxiliary agent is used for digesting and oxidizing ferrous oxide and silicon dioxide in the coal ash, so that the melting point of a combustion product is directly improved, and the pollution and coking phenomena of a hearth in the melting combustion process are effectively reduced; and the strong oxidizing property of the auxiliary agent is also beneficial to removing a large amount of impurities in the coal ash, and the combustion efficiency of the coal ash is improved, so that the coal ash can be completely combusted.

2. According to the invention, silicate generated in the process of digesting silicon dioxide in coal ash by using the compound auxiliary agent can loosen a coke scale system, the silicate is matched with components in other liquid decoking agents to act on the coal ash, the heat effect is improved, the generation of sulfate is reduced, chemical gas is generated and distributed in each area of a hearth, the coke scale after complete heating combustion is further loosened and porous by matching with the strong oxidizing combustion supporting effect of the auxiliary agent until the coke scale is finally pulverized and falls off, and the effect of the decoking agent is obviously improved.

Detailed Description

The disclosure may be understood more readily by reference to the following detailed description of preferred embodiments of the invention and the examples included therein. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.

The term "prepared from …" as used herein is synonymous with "comprising". The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

The conjunction "consisting of …" excludes any unspecified elements, steps or components. If used in a claim, the phrase is intended to claim as closed, meaning that it does not contain materials other than those described, except for the conventional impurities associated therewith. When the phrase "consisting of …" appears in a clause of the subject matter of the claims rather than immediately after the subject matter, it defines only the elements described in the clause; other elements are not excluded from the claims as a whole.

When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as a range of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2 and 4 to 5", "1 to 3 and 5", and the like. When a range of values is described herein, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range.

The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. "optional" or "any" means that the subsequently described event or events may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

Approximating language, as used herein throughout the specification and claims, is intended to modify a quantity, such that the invention is not limited to the specific quantity, but includes portions that are literally received for modification without substantial change in the basic function to which the invention is related. Accordingly, the use of "about" to modify a numerical value means that the invention is not limited to the precise value. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value. In the present description and claims, range limitations may be combined and/or interchanged, including all sub-ranges contained therein if not otherwise stated.

In addition, the indefinite articles "a" and "an" preceding an element or component of the invention are not intended to limit the number requirement (i.e., the number of occurrences) of the element or component. Thus, "a" or "an" should be read to include one or at least one, and the singular form of an element or component also includes the plural unless the stated number clearly indicates that the singular form is intended.

In some preferred embodiments, the feedstock comprises the following parts by weight: 85-95 parts of solvent, 0.5-1 part of high-temperature retention agent, 4-8 parts of nitrate and 9-12 parts of auxiliary agent.

In some preferred embodiments, the feedstock comprises the following parts by weight: 90 parts of solvent, 0.8 part of high-temperature retention agent, 7.5 parts of nitrate and 10 parts of auxiliary agent.

In some preferred embodiments, the solvent is deionized water.

In some preferred embodiments, the high temperature retention agent is at least one of boric acid and borax.

In some preferred embodiments, the high temperature retention agent is boric acid.

In some preferred embodiments, the weight ratio of boric acid to solvent is from 0.5 to 0.8: 90-95.

In some preferred embodiments, the nitrate salt is at least one of potassium nitrate, sodium nitrate, magnesium nitrate, aluminum nitrate, copper nitrate.

In some preferred embodiments, the nitrate salts are potassium nitrate, copper nitrate, magnesium nitrate, and aluminum nitrate.

In some preferred embodiments, the weight ratio of potassium nitrate, copper nitrate, magnesium nitrate and aluminum nitrate is 4.5-5.5: 0.4-0.6: 0.3-0.5: 0.01 to 0.1.

In some preferred embodiments, the auxiliary agent is at least one of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, perchloric acid, hypochlorous acid.

In some preferred embodiments, the auxiliary agents are hydrochloric acid, hydrofluoric acid, and nitric acid.

In some preferred embodiments, the volume ratio of the hydrochloric acid to the hydrofluoric acid to the nitric acid is 2-3: 1-2: 5 to 7.

In some preferred embodiments, the volume ratio of hydrochloric acid, hydrofluoric acid and nitric acid is 2: 1: 7.

according to the invention, the acid auxiliary agent added in a compounding manner greatly improves the decoking and coke inhibiting effects of the decoking agent, can effectively inhibit coking and contamination phenomena in a hearth, and promotes complete combustion of coke blocks, so that the decoking effect is realized. The applicant speculates that: when the volume ratio of the hydrochloric acid to the hydrofluoric acid to the nitric acid is 2-3: 1-2: 5-7, the hydrochloric acid and the nitric acid are matched to form nitrosyl chloride with stronger oxidability than a single component in the mixed acid, and the nitrosyl chloride and oxygen released by the nitrate penetrating into the coke scale can synergistically act inside and outside to promote the combustion of a deposited carbon layer deposited in the coke scale, so that the coke scale structure is loosened; the strong ionization effect of the hydrochloric acid and the nitric acid can effectively promote and improve the ionization degree of fluorine ions in the hydrofluoric acid, so that the mixed acid auxiliary agent shows stronger stability, the improvement of the ionization degree of the hydrofluoric acid enables the mixed acid auxiliary agent to stably exist in a decoking agent solution and generate beneficial effect, and the generation of volatilization phenomenon is effectively reduced; the coking coal ash mainly contains low-melting-point coal ash consisting of silicon dioxide substances and ferrous oxide, so that the overall melting point of the coal ash is greatly reduced, and molten combustion products are easily generated to cause the phenomena of caking and contamination of a hearth and a heating surface. After the addition of the auxiliary agent, hydrofluoric acid can preferentially digest silicon dioxide substances to generate silicate, and nitrosyl chloride in the auxiliary agent can rapidly oxidize ferrous chloride to become ferric oxide with high melting point, so that the formation of eutectic with lower melting point between the silicon dioxide and the ferric oxide is prevented, the integral melting point of coke scale is improved, the crystallization process of solid particles is improved, and the occurrence of coking and contamination is greatly delayed or inhibited. When the content of hydrochloric acid is too large, the mixed acid has too large oxidizing property, and the wall surface of the hearth is easily oxidized, thereby causing unnecessary loss. When the content of nitric acid is too large compared with hydrochloric acid, the excessive oxidizing property of nitric acid oxidizes a large amount of chloride ions and easily reduces the digestion and oxidizing ability of the whole mixed acid additive.

Meanwhile, silicate generated by digesting silicon dioxide substances with hydrofluoric acid can loosen the coke scale system structure, and is matched with other components in the decoking agent disclosed by the invention to effectively act on the surface of coal ash, so that the heat effect is improved, and the generation of sulfate is reduced; the coal ash coke scale on each heating surface is further made to be porous and loose by spraying the decoking agent distributed on each receiving surface of the boiler through the above functions until the coke scale is pulverized and falls off, and the decoking effect is obviously improved.

Examples

The technical solution of the present invention is described in detail by the following examples, but the scope of the present invention is not limited to all of the examples. The starting materials of the present invention are all commercially available unless otherwise specified.

Example 1

The embodiment provides a decoking agent, which comprises the following raw materials in parts by weight: 90 parts of deionized water, 0.8 part of boric acid, 7.5 parts of nitrate (potassium nitrate, copper nitrate, magnesium nitrate and aluminum nitrate in a weight ratio of 5: 0.5: 0.4: 0.05) and 10 parts of auxiliary agent (hydrochloric acid, hydrofluoric acid and nitric acid in a volume ratio of 2: 1: 7).

The embodiment also provides a preparation method of the decoking agent, which comprises the following steps: (1) adding 0.8 part of boric acid into 90 parts of deionized water, stirring and mixing completely, then adding 7.5 parts of nitrate (potassium nitrate, copper nitrate, magnesium nitrate and aluminum nitrate in a weight ratio of 5: 0.5: 0.4: 0.05) into the deionized water, and stirring for 25 minutes to completely dissolve the nitrate to obtain a mixed solution; (2) and (2) slowly draining the mixed solution obtained in the step (1), adding 10 parts of auxiliary agents (hydrochloric acid, hydrofluoric acid and nitric acid in a volume ratio of 2: 1: 7), and slowly stirring for 15 minutes to obtain the decoking agent.

The decoking agent obtained in this example was designated as C1.

Example 2

The embodiment of the present invention is different from embodiment 1 in that: 0.5 part of boric acid and 95 parts of deionized water.

The decoking agent obtained in this example was designated as C2.

Example 3

The embodiment of the present invention is different from embodiment 1 in that: potassium nitrate, copper nitrate, magnesium nitrate and aluminum nitrate, wherein the weight ratio of the potassium nitrate to the copper nitrate to the magnesium nitrate to the aluminum nitrate is 4.5: 0.6: 0.5: 0.1.

the decoking agent obtained in this example was designated as C3.

Comparative example 1

The embodiment of this comparative example is the same as example 1 except that: 0.2 part of boric acid and 90 parts of deionized water.

The decoking agent obtained in this comparative example was designated as D1.

Comparative example 2

The embodiment of this comparative example is the same as example 1 except that: potassium nitrate, copper nitrate, magnesium nitrate and aluminum nitrate, wherein the weight ratio is 10: 0.5: 0.4: 0.05.

the decoking agent obtained in this comparative example was designated as D2.

Comparative example 3

The embodiment of this comparative example is the same as example 1 except that: potassium nitrate, copper nitrate, magnesium nitrate and aluminum nitrate, wherein the weight ratio is 5: 0.5: 0: 0.

the decoking agent obtained in this comparative example was designated as D3.

Comparative example 4

The embodiment of this comparative example is the same as example 1 except that: hydrochloric acid, hydrofluoric acid and nitric acid, wherein the volume ratio is 2: 5: 7.

the decoking agent obtained in this comparative example was designated as D4.

Comparative example 5

The embodiment of this comparative example is the same as example 1 except that: hydrochloric acid, hydrofluoric acid and nitric acid, wherein the volume ratio is 7: 1: 7.

the decoking agent obtained in this comparative example was designated as D5.

Evaluation of Performance

1. Ash removal and coke removal rate: the decoking agents obtained in all the examples and comparative examples were added to the boiler in equal amounts to test the removal efficiency. Firstly, measuring the weight W1 of a boiler, wherein the boiler is normally used and is roasted for 1 hour at 1200 ℃, measuring the weight W2, 5 percent of the decoking agent obtained in the embodiment and the comparative example is sprayed on the boiler, and is placed for 2 hours at room temperature, and then is rinsed by sponge under the flow of hot water and is dried, and the weight W3 is measured; ash removal and coke removal rate { (W2-W3)/(W2-W1) } x 100%; each example comparative example 5 samples were tested and the values averaged and reported in table 1.

2. Corrosion conditions: and finally observing the corrosion condition of the decoking boiler by adopting the same test mode as the ash removal decoking rate, and recording the observed result into a table 1.

3. Thermal efficiency; the thermal efficiency of the boiler which is normally operated is tested according to the GB/T10180 standard, and the thermal efficiency of the boiler which is normally operated is 75 percent after the decoking agent obtained in the examples and the comparative examples is added into the boiler; each example comparative example 5 samples were tested and the values averaged and reported in table 1.

TABLE 1

The embodiments 1 to 3, the comparative examples 1 to 5 and the table 1 show that the decoking agent prepared by the preparation method of the decoking agent provided by the invention has good ash removal decoking efficiency, low corrosivity and good boiler thermal efficiency improvement effect, is suitable for being popularized in the boiler decoking field, and has wide development prospect. Wherein example 1 achieves the best performance index with the best volume ratio of mixed acid adjuvant and weight ratio of nitrate.

Finally, it should be understood that the above-described embodiments are merely preferred embodiments of the present invention, and not intended to limit the present invention, and any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The decoking agent is characterized in that: the raw materials comprise the following components in parts by weight: 80-120 parts of solvent, 0.1-2 parts of high-temperature retention agent, 1-10 parts of nitrate and 8-15 parts of auxiliary agent.

2. The decoking agent of claim 1, wherein: the raw materials comprise the following components in parts by weight: 85-95 parts of solvent, 0.5-1 part of high-temperature retention agent, 4-8 parts of nitrate and 9-12 parts of auxiliary agent.

3. The decoking agent of claim 1, wherein: the solvent is deionized water.

4. The decoking agent of claim 1, wherein: the high-temperature retention agent is at least one of boric acid and borax.

5. The decoking agent of claim 1, wherein: the high-temperature retention agent is boric acid.

6. The decoking agent of claim 1, wherein: the nitrate is at least one of potassium nitrate, sodium nitrate, magnesium nitrate, aluminum nitrate and copper nitrate.

7. The decoking agent of claim 1, wherein: the auxiliary agent is at least one of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, perchloric acid and hypochlorous acid.

8. The decoking agent of claim 7, wherein: the auxiliary agent is hydrochloric acid, hydrofluoric acid and nitric acid.

9. The decoking agent of claim 8, wherein: the volume ratio of the hydrochloric acid to the hydrofluoric acid to the nitric acid is 2-3: 1-2: 5 to 7.

10. A method for preparing the decoking agent according to any one of claims 1 to 9, characterized in that: the method comprises the following steps: (1) adding a high-temperature retention agent into a solvent, stirring and mixing completely, then adding nitrate into the solvent, stirring for 20-30 minutes, and dissolving completely to obtain a mixed solution; (2) and (2) slowly introducing the assistant into the mixed liquid obtained in the step (1), and slowly stirring for 10-20 minutes to obtain the decoking agent.