CN108424797B

CN108424797B - Composite water-coal-slurry additive and preparation process thereof

Info

Publication number: CN108424797B
Application number: CN201810242440.6A
Authority: CN
Inventors: 邱慕涛
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-03-22
Filing date: 2018-03-22
Publication date: 2020-08-28
Anticipated expiration: 2038-03-22
Also published as: CN108424797A

Abstract

The invention belongs to the technical field of production of coal water slurry and coke water slurry, and particularly relates to a composite coal water slurry additive and a preparation process thereof. The invention integrates the characteristics that the naphthalenesulfonic acid formaldehyde condensation compound needs an alkaline regulator for neutralization, and the pulping black liquor modification needs an acidic regulator for regulating the pH of a reaction system, improves the process, saves the use of chemical raw materials, reduces the content of sodium sulfate in the coal water slurry additive, and solves the problems that the viscosity of the coal water slurry is increased and the stability is reduced due to the high content of sodium sulfate.

Description

Composite water-coal-slurry additive and preparation process thereof

Technical Field

The invention belongs to the technical field of production of coal water slurry and coke water slurry, and particularly relates to a composite coal water slurry additive and a preparation process thereof.

Background

The coal water slurry is an oil-substituted coal-based fluid fuel which is low in pollution, high in efficiency and capable of being conveyed by a pipeline, is obtained by physically processing about 65% of coal, 34% of water and 1% of additives, changes the traditional combustion mode of the coal, and shows huge environment-friendly and energy-saving advantages. Because the coal water slurry is a solid-liquid two-phase dispersion system, a small amount of additive is added to prevent precipitation, so that the coal water slurry can achieve the aim of shear thinning on one hand, and coal dust particles are prevented from agglomerating on the other hand.

The most widely used products in the market at present are naphthalene sulfonate condensates with various substituents, and the naphthalene sulfonate condensates have the characteristics of good dispersibility, strong viscosity reducing effect, good slurry fluidity and wide application range, can be used by being compounded with various dispersants, but have poor slurry stability and are easy to generate hard precipitates. The coal water slurry additive sold in the market at present is mainly prepared by mixing a naphthalene sulfonate condensate with sodium lignosulfonate in proportion, and a large amount of sulfuric acid is added in the preparation processes of the lignosulfonate and the naphthalene sulfonate condensate, so that the concentration of sulfate in the additive is higher, and the problems of the coal water slurry such as the increase of the concentration, the reduction of the stability and the like are caused. In general, most of the coal water slurry additives have respective disadvantages, and the development of the additives with high efficiency, low price and wide adaptability is a main research direction in the future.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a process for preparing a composite water-coal-slurry additive by taking pulping black liquor as a raw material and a naphthalenesulfonic acid-formaldehyde condensate intermediate as an acid regulator through a series of chemical modifications and the composite water-coal-slurry additive prepared by the process.

In order to achieve the purpose, the invention adopts the following technical scheme:

the preparation process of the composite water-coal-slurry additive comprises the following steps:

(1) preparation of an acidity regulator: firstly, putting naphthalene and a homologue thereof into a sulfonation reaction kettle, heating to 135-145 ℃, adding concentrated sulfuric acid, and performing sulfonation reaction for 2-3 h at 155-160 ℃; and (2) conveying the reaction materials to a hydrolysis condensation reaction kettle, cooling to 120-125 ℃, introducing water at the temperature of 70-90 ℃, performing hydrolysis reaction for 0.5-1.0 h, slowly adding formaldehyde, performing condensation reaction at the temperature of 100-105 ℃ for 4-5 h, and adding water to dilute until the solid content is 30.0%, thus obtaining the acid regulator.

(2) Preparing a composite coal water slurry additive: placing pulping black liquor into a reaction kettle with good heat preservation performance, adding 150 ℃ saturated steam to raise the temperature of a reaction system to 50-60 ℃, adding the acid regulator prepared in the step (1), regulating the pH value to 10.5-11.5, adding hydrogen peroxide, and carrying out oxidation reaction for 20-30 min; then adding 150 ℃ saturated steam to raise the temperature of the reaction system to 75-85 ℃, adding formaldehyde, and carrying out hydroxymethyl reaction for 30-40 min; then adding a sulfonating agent, adding 150 ℃ saturated steam to raise the temperature of the reaction system to 95-105 ℃, and carrying out sulfonation reaction for 2-3 hours; and (2) cooling to 80-90 ℃, adding the acid regulator prepared in the step (1), regulating the pH to 7-8, reacting for 0.5-1 h, cooling and discharging to obtain a tan liquid product, and performing spray drying to obtain a coffee toner product. The additive of the invention is mainly used for preparing the coal water slurry, so that the coal water slurry has lower viscosity and better fluidity in normal use.

Preferably, the raw materials used in the preparation process of the composite coal water slurry additive comprise the following components in percentage by weight: naphthalene and/or naphthalene family homologues: 6.4% -7.7% concentrated sulfuric acid (98%: 6.6% -7.0%; formaldehyde (37% content): 4.7% -5.6%; 31.0% -37.0% of pulping black liquor; saturated water vapor at 150 ℃: 7.2% -8.0%; hydrogen peroxide (30% content): 0.4% -0.6%; sulfonating agent: 2.2% -2.3%; water: 35.3% -38.5%.

Preferably, the pulping black liquor is prepared from one or more of poplar, eucalyptus, birch and masson pine by a caustic soda method, and the solid content is 40.0-50.0%.

Preferably, the sulfonating agent is one or a mixture of sodium sulfite and sodium pyrosulfite.

Preferably, the acidity regulator prepared in step (1) is a naphthalene sulfonic acid formaldehyde condensate intermediate.

Preferably, the inlet temperature of spray drying equipment adopted by spray drying is 330-350 ℃, the outlet temperature is 105-120 ℃, and the recovery rate of dry powder is more than 95%.

When the product is used, the additive can be directly mixed with powder or prepared into an aqueous solution for use, and the mixing amount of the additive is 0.1-0.5 percent of that of dry coal.

Compared with the prior art, the invention has the following advantages and positive effects:

(1) the invention integrates the characteristics that the naphthalenesulfonic acid formaldehyde condensation compound needs an alkaline regulator for neutralization, and the pulping black liquor modification needs an acidic regulator for regulating the pH of a reaction system, improves the process, saves the use of chemical raw materials, reduces the content of sodium sulfate in the coal water slurry additive, and solves the problems that the viscosity of the coal water slurry is increased and the stability is reduced due to the high content of sodium sulfate.

(2) Because formaldehyde is needed to be used as a raw material for hydroxymethylation and polycondensation in the process of modifying the pulping black liquor, and the naphthalenesulfonic acid formaldehyde condensate contains a large amount of free formaldehyde, the process not only effectively utilizes the free formaldehyde in the naphthalenesulfonic acid formaldehyde condensate, saves resources, but also avoids the free formaldehyde from expanding into the environment and polluting the environment.

(3) The pulping black liquor used in the process is prepared by a soda process, so that the problem that the product performance of the coal water slurry additive is influenced by overhigh sodium sulfate content in the pulping black liquor is avoided.

(4) In the process of modifying the pulping black liquor, saturated steam is adopted for direct heating, so that the heat transfer efficiency is improved, the heat loss is reduced, the preparation time of the product is shortened, and a large amount of heat energy is saved.

Detailed Description

In order to explain technical contents, structural features, and objects and effects of the technical means in detail, the following detailed description is given with reference to specific embodiments.

The preparation process of the invention is as follows:

The mass fraction of the raw materials is as follows: naphthalene and/or naphthalene family homologues: 6.4% -7.7% concentrated sulfuric acid (98%: 6.6% -7.0%; formaldehyde (37% content): 4.7% -5.6%; 31.0% -37.0% of pulping black liquor; saturated water vapor at 150 ℃: 7.2% -8.0%; hydrogen peroxide (30% content): 0.4% -0.6%; sulfonating agent: 2.2% -2.3%; water: 35.3% -38.5%.

The pulping black liquor is prepared from one or more of poplar, eucalyptus, birch and masson pine by a caustic soda method, and the solid content is 50.0-60.0%.

The sulfonating agent is one or mixture of sodium sulfite and sodium pyrosulfite.

The acidity regulator is the intermediate of the naphthalene sulfonic acid formaldehyde condensate prepared in the step (1).

The inlet temperature of spray drying equipment adopted by spray drying is 330-350 ℃, the outlet temperature is 105-120 ℃, and the recovery rate of dry powder is more than 95%.

Table 1 shows the raw material ratios used in examples 1-3:

the content of each component (unit: kilogram)	Example 1	Example 2	Example 3
				Methylnaphthalene	77	76	64
Concentrated sulfuric acid (98%)	66	70	66
				Formaldehyde (37%)	56	54	47
Black liquor of soda pulping	310	322	370
				Saturated steam at 150 deg.C	77	80	72
Hydrogen peroxide (30%)	6	4	5
				Sodium sulfite	23	22	23
Water (W)	385	372	353

Table 2 shows the raw materials used in examples 1-3 in the ratios (percentages are in units):

content of each component (unit:%)	Example 1	Example 2	Example 3
				Methylnaphthalene	7.7%	7.6%	6.4%
Concentrated sulfuric acid (98%)	6.6%	7.0%	6.6%
				Formaldehyde (37%)	5.6%	5.4%	4.7%
Black liquor of soda pulping	31.0%	32.2%	37.0%
				Saturated steam at 150 deg.C	7.7%	8.0%	7.2%
Hydrogen peroxide (30%)	0.6%	0.4%	0.5%
				Sodium sulfite	2.3%	2.2%	2.3%
Water (W)	38.5%	37.2%	35.3%

Example 1

1. The raw material composition used in this example was as follows (unit: kg):

methylnaphthalene: 77 kg

Concentrated sulfuric acid (98%): 66 kg

Formaldehyde (37%): 56 kg

Black liquor (solid content 50%) prepared by a masson pine caustic soda pulping method: 310 kg

Saturated water vapor at 150 ℃: 77 kg

Hydrogen peroxide (30%): 6 kg

Sodium sulfite: 23 kg

Water: 385 kg

2. The preparation process comprises the following steps and parameters:

(1) preparation of an acidity regulator: putting 77 kg of methylnaphthalene into a sulfonation reaction kettle, heating to 135 ℃, adding 66 kg of 98% concentrated sulfuric acid, and performing sulfonation reaction at 155 ℃ for 3.0 h; conveying the reaction materials to a hydrolysis condensation kettle, cooling to 120 ℃, introducing 15 kg of hot water at the temperature of 90 ℃, performing hydrolysis reaction for 0.5h, slowly adding 44 kg of formaldehyde solution with the solid content of 37% (the adding time is about 2.0 h), after performing condensation reaction for 3.0h at the temperature of 100 ℃, adding 14 kg of water, continuing constant-temperature condensation reaction for 2.0h, adding 310 kg of water, and diluting the concentration of a reaction system to 30.0% to obtain the acid regulator.

(2) Preparing a composite coal water slurry additive: putting 307 kg of pulping black liquor with the solid content of 50% (the initial temperature is 25 ℃) into a reaction kettle with good heat preservation performance, adding 15 kg of 150 ℃ saturated steam to raise the temperature of a reaction system to about 55 ℃, adding 320 kg of acid regulator prepared in the step (1), regulating the pH value to 11.0, then adding 6 kg of hydrogen peroxide, and carrying out oxidation reaction for 25 min; firstly adding 27 kg of 150 ℃ saturated steam to raise the temperature of a reaction system to about 80 ℃, then adding 12 kg of 37% formaldehyde, and carrying out hydroxymethyl reaction for 30 min; preparing 33.3 percent solution by 23 kg of sodium sulfite and 46 kg of water, adding the solution into the reaction system, adding 35 kg of 150 ℃ saturated steam to increase the temperature of the reaction system to 100 ℃, and carrying out sulfonation reaction for 2.5 hours; cooling to 80 ℃, adding 206 kg of the acidic regulator prepared in the step (1) to adjust the pH value to 7.0, reacting for 0.5h, cooling to obtain a reddish brown liquid product, and drying by an LPG-200 spray dryer, wherein the inlet temperature of a spray tower is 350 ℃, and the outlet temperature is 110 ℃, so that the coffee solid powder is obtained.

Example 2

1. The raw material composition used in this example was as follows (unit: kg):

naphthalene and its homologues (mixture of naphthalene and methylnaphthalene, mass ratio is 1: 1): 76 kg of

Concentrated sulfuric acid (98%): 70 kg of

Formaldehyde (37%): 54 kg

The soda pulping process comprises the following steps of (1: 3 by mass ratio, 45% by solid content) black liquor (a mixture of poplar and eucalyptus): 322 kg (weight loss)

Saturated water vapor at 150 ℃: 80 kg of

Hydrogen peroxide (30%): 4 kg

Sodium metabisulfite: 22 kg

Water: 372 kg

2. The preparation process comprises the following steps and parameters:

(1) preparation of an acidity regulator: putting 76 kg of industrial naphthalene and methylnaphthalene into a sulfonation reaction kettle, heating to 140 ℃, adding 70 kg of 98% concentrated sulfuric acid, and sulfonating at 160 ℃ for 2.5 h; conveying the reaction materials to a hydrolysis condensation reaction kettle, cooling to 125 ℃, introducing 18 kg of hot water at 70 ℃, performing hydrolysis reaction for 0.8 h, slowly adding 46 kg of 37% formaldehyde solution (the adding time is about 2.0 h), performing condensation reaction for 3.0h at 105 ℃, adding 19 kg of water, continuing constant-temperature condensation reaction for 1.0h, adding 291 kg of water, and diluting the concentration of the reaction system to 30.0% to obtain the acid regulator.

(2) Preparing a composite coal water slurry additive: putting 322 kg of pulping black liquor with solid content of 45% (initial temperature is 25 ℃) into a reaction kettle with good heat preservation performance, adding 18 kg of 150 ℃ saturated steam to raise the temperature of a reaction system to about 60 ℃, adding 282 kg of acid regulator prepared in the step (1), regulating the pH value to 11.5, adding 4 kg of hydrogen peroxide, and carrying out oxidation reaction for 25 min; adding 28 kg of 150 ℃ saturated steam to raise the temperature of a reaction system to about 85 ℃, adding 8 kg of 37% formaldehyde, and carrying out hydroxymethyl reaction for 30 min; preparing a 33.3% solution from 22 kg of sodium metabisulfite and 44 kg of water, adding the solution into the reaction system, adding 34 kg of 150 ℃ saturated steam to increase the temperature of the reaction system to about 105 ℃, and carrying out sulfonation reaction for 2 hours; and (2) cooling to 80 ℃, adding 238 kg of the acidic regulator prepared in the step (1) to regulate the pH value to 7.5, reacting for 0.5h, cooling to obtain a reddish brown liquid product, and drying by using an LPG-200 type spray dryer, wherein the inlet temperature of a spray tower is 340 ℃, and the outlet temperature is 105 ℃, so that the coffee solid powder is obtained.

Example 3

1. The raw material composition used in this example was as follows (unit: kg):

industrial naphthalene: 64 kg

Concentrated sulfuric acid (98%): 66 kg

Formaldehyde (37%): 47 kg

The soda pulping process comprises the following steps of (1) pulping black liquor (a mixture of eucalyptus, birch and masson pine in a mass ratio of 1:1:3 and a solid content of 40%): 370 kg

Saturated water vapor at 150 ℃: 72 kg

Hydrogen peroxide (30%): 5 kg

Sulfonating agent (mixture of sodium sulfite and sodium pyrosulfite, mass ratio is 3: 8): 23 kg

Water: 353 kg

2. The preparation process comprises the following steps and parameters:

(1) preparation of an acidity regulator: firstly, 64 kg of industrial naphthalene is placed in a sulfonation reaction kettle, heated to 145 ℃, added with 66 kg of concentrated sulfuric acid with the solid content of 98 percent, and sulfonated for 3 hours at 158 ℃; the reaction materials are conveyed to a hydrolysis condensation reaction kettle, the temperature is reduced to 123 ℃, then 15 kg of hot water with the temperature of 85 ℃ is introduced, hydrolysis reaction is carried out for 1.0h, 34 kg of formaldehyde solution with the solid content of 37 percent is slowly added (the adding time is about 2.0 h), after condensation reaction is carried out for 3.0h at 105 ℃, 15 kg of water is added to continue the constant temperature condensation reaction for 1.0h, 277 kg of water is added to dilute the concentration of the reaction system to 30.0 percent, and the acid regulator is obtained.

(2) Preparing a composite coal water slurry additive: putting 370 kg of pulping black liquor with the solid content of 40% (the initial temperature is 25 ℃) into a reaction kettle with good heat preservation performance, adding 15 kg of 150 ℃ saturated steam to increase the temperature of a reaction system to about 50 ℃, adding 300 kg of the acid regulator prepared in the step (1), regulating the pH value to 10.5, adding 5 kg of hydrogen peroxide, and carrying out oxidation reaction for 30 min; adding 23 kg of 150 ℃ saturated steam to raise the temperature of a reaction system to about 75 ℃, adding 13 kg of 37% formaldehyde, and carrying out hydroxymethyl reaction for 30 min; preparing 33.3 percent solution by 23 kg of sodium sulfite and 46 kg of water, adding the solution into the reaction system, adding 34 kg of 150 ℃ saturated steam to raise the temperature of the reaction system to 95 ℃, and carrying out sulfonation reaction for 3 hours; cooling to 80 ℃, adding 171 kg of the acid regulator prepared in the step (1) to adjust the pH value to 8.0, reacting for 1.0h, cooling to obtain a reddish brown liquid product, and drying by an LPG-200 type spray dryer, wherein the inlet temperature of a spray tower is 330 ℃, and the outlet temperature is 100 ℃, so that the coffee solid powder is obtained.

(1) In the above embodiments 1,2, and 3, the characteristics that the naphthalenesulfonic acid formaldehyde condensate needs an alkaline regulator for neutralization, and the pulping black liquor modification needs an acidic regulator for regulating the pH of the reaction system are integrated, and the process improvement is performed, so that the use of chemical raw materials is saved, the sodium sulfate content in the coal water slurry additive is reduced, and the problems of the coal water slurry additive such as increased viscosity, reduced stability and the like are caused due to the high sodium sulfate content.

(2) In the above examples 1,2, and 3, since formaldehyde is required as a raw material for the hydroxymethylation and polycondensation reactions in the process of modifying the pulping black liquor, and the naphthalenesulfonic acid-formaldehyde condensate contains a large amount of free formaldehyde, the process not only effectively utilizes the free formaldehyde in the naphthalenesulfonic acid-formaldehyde condensate, saves resources, but also avoids the free formaldehyde from expanding into the environment and polluting the environment.

(3) In the above embodiments 1,2 and 3, the pulping black liquor is prepared by a soda process, so as to avoid the influence of the excessive sodium sulfate content in the pulping black liquor on the product performance of the coal water slurry additive.

(4) In the above examples 1,2 and 3, saturated steam is used for direct heating in the process of modifying pulping black liquor, which not only improves heat transfer efficiency but also reduces heat loss, shortens preparation time of products and saves a large amount of heat energy.

Performance testing

Taking Shenhua coal as a research object, crushing and weighing quantitative coal, fine slurry, corresponding water and a coal water slurry additive, mixing and stirring the mixture in a rod mill to form slurry, quickly stirring the slurry (the rotating speed is 1200 r/min) for 10min and slowly stirring the slurry (the rotating speed is 500 r/min) for 5min by using a stirrer, and then measuring performance indexes such as concentration, apparent viscosity, fluidity, stability and the like.

(1) Concentration of the coal water slurry: the water content was measured by using a MA100 rapid moisture meter.

(2) Apparent viscosity and slurry rheology of coal water slurry: the apparent viscosity, determined by RV-1 rheometer (Z41 rotor), is taken as the shear rate of 100s^-1The average value of the viscosity and the test temperature are constant temperature 20 ℃.

(3) And (3) testing the fluidity: the method is divided into A, B, C and 3 grades according to the flowing character by adopting an eye measuring method, and the division standard of each grade is as follows: a is continuous flow, B is discontinuous flow, C is no flow, and + represents a more subtle difference, e.g., A + is more fluid than A, and C is the least fluid.

(4) And (3) stability testing: the stability of the coal water slurry is characterized by a static water separation method and a rod drop experiment, 100mL of the coal water slurry is poured into a100 mL measuring cylinder by a funnel, the percentage of water separated out in a test tube accounting for the total height of the coal water slurry is measured after 3d, then a round-head glass rod with the diameter of 4mm is gently inserted into the test tube, and if the water can directly reach the bottom, no precipitate is shown; if the bottom can be reached by slightly stirring, soft precipitation is realized; if the force is applied, the insertion is not performed, and the hard precipitate is formed. And the time when the coal water slurry is hard precipitated is determined by long-term observation.

Examples 1,2 and 3 all used solid form feeding, the feeding amount is 0.5% of the dry coal mass, and the slurry forming performance is shown in table 3.

Table 3 shows the comparison of the pulp forming properties of the products

As can be seen from the data in Table 3, when the additive of the invention in the examples 1-3 is used, the concentration and the viscosity of the Shenhua coal after slurrying both meet the requirements of GB/T18855-.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrases "comprising … …" or "comprising … …" does not exclude the presence of additional elements in a process, method, article, or terminal that comprises the element. Further, herein, "greater than," "less than," "more than," and the like are understood to exclude the present numbers; the terms "above", "below", "within" and the like are to be understood as including the number.

Although the embodiments have been described, once the basic inventive concept is obtained, other variations and modifications of these embodiments can be made by those skilled in the art, so that the above embodiments are only examples of the present invention, and not intended to limit the scope of the present invention, and all changes that can be made by using the equivalent structure or equivalent flow of the present specification, or directly or indirectly applied to other related technical fields are included in the scope of the present invention.

Claims

1. The preparation process of the compound coal water slurry additive is characterized by comprising the following steps of: the method comprises the following process steps:

(1) preparation of an acidity regulator: firstly, putting naphthalene and/or naphthalene homolog in a sulfonation reaction kettle, heating to 135-145 ℃, adding concentrated sulfuric acid, and sulfonating at 155-160 ℃ for 2-3 h; conveying the reaction materials to a hydrolysis condensation reaction kettle, cooling to 120-125 ℃, then introducing water at 70-90 ℃, carrying out hydrolysis reaction for 0.5-1.0 h, slowly adding formaldehyde, carrying out condensation reaction at 100-105 ℃ for 4-5 h, adding water to dilute until the solid content is 30.0%, and obtaining an acid regulator, wherein the obtained acid regulator is a naphthalenesulfonic acid formaldehyde condensation product intermediate;

(2) preparing a composite coal water slurry additive: one or more pulping black liquor which is prepared from poplar, eucalyptus, birch and masson pine by a caustic soda method and has a solid content of 40.0-50.0% is prepared by placing the pulping black liquor into a reaction kettle, adding 150 ℃ saturated steam to raise the temperature of a reaction system to 50-60 ℃, adding the acid regulator prepared in the step (1), regulating the pH value to 10.5-11.5, adding hydrogen peroxide, and carrying out oxidation reaction for 20-30 min; then adding 150 ℃ saturated steam to raise the temperature of the reaction system to 75-85 ℃, adding formaldehyde, and carrying out hydroxymethyl reaction for 30-40 min; then adding a sulfonating agent, adding 150 ℃ saturated steam to raise the temperature of the reaction system to 95-105 ℃, and carrying out sulfonation reaction for 2-3 hours; cooling to 80-90 ℃, adding the acidic regulator prepared in the step (1), regulating the pH value to 7-8, reacting for 0.5-1 h, cooling and discharging to obtain a brown liquid product, and performing spray drying to obtain a coffee toner product;

the raw materials used in the process steps (1) and (2) comprise the following components in percentage by mass:

naphthalene and/or naphthalene family homologues: 6.4 to 7.7 percent

98% concentrated sulfuric acid: 6.6% -7.0%;

37% formaldehyde solution: 4.7% -5.6%;

31.0% -37.0% of pulping black liquor;

saturated water vapor at 150 ℃: 7.2% -8.0%;

30% of hydrogen peroxide: 0.4% -0.6%;

sulfonating agent: 2.2% -2.3%;

water: 35.3% -38.5%.

2. The preparation process of the compound coal water slurry additive according to claim 1, which is characterized in that: the sulfonating agent is one or a mixture of sodium sulfite and sodium pyrosulfite.

3. The preparation process of the compound coal water slurry additive according to claim 1, which is characterized in that: the inlet temperature of spray drying equipment adopted by spray drying is 330-350 ℃, the outlet temperature is 100-110 ℃, and the recovery rate of dry powder is more than 95%.