1. The medium and low temperature coal pyrolysis semicoke passivation method is characterized by sequentially comprising the following steps:

passivating carbon dioxide gas of medium-low temperature coal pyrolysis semicoke, fully contacting pyrolysis semicoke with the particle size of 75-100 microns and the temperature of 650 ℃ with carbon dioxide gas at the temperature of 25 ℃, after the high-temperature semicoke is contacted with low-temperature CO2 for heat exchange, reducing the temperature of the semicoke to about 60 ℃, continuously introducing the carbon dioxide gas into the medium-low temperature coal pyrolysis semicoke at about 60 ℃, adsorbing carbon dioxide by the semicoke at about 60 ℃, and stopping introducing the gas when the adsorption amount of the semicoke to the carbon dioxide reaches 18.6cm3/g 2;

and step two, coating and passivating the surface of the semi-coke of the medium-low temperature coal pyrolysis, pouring the surface coating agent into a semi-coke container, fully stirring, filtering and standing until the surface coating agent of the semi-coke is cured.

2. The method for passivating semi-coke generated by pyrolyzing coal according to claim 1, wherein the purity of carbon dioxide in the first step is higher than 95% and the oxygen content is lower than 1%.

3. The method for passivating semi-coke generated by pyrolyzing coal according to claim 1, wherein the carbon dioxide in the first step is recycled after heat is removed.

4. The method for passivating medium and low temperature coal pyrolysis semicoke as claimed in claim 1, wherein the surface coating agent is composed of water glass, surfactant, defoaming agent and water.

5. The method for passivating medium and low temperature coal pyrolysis semicoke as claimed in claim 4, wherein in the surface coating agent component, the surfactant is an anionic surfactant.

6. The method for passivating medium and low temperature coal pyrolysis semicoke as claimed in claim 4, wherein in the surface coating agent component, the water glass modulus is 3.3, and the Baume degree is 40 degrees.

7. The method for passivating medium and low temperature coal pyrolysis semicoke as claimed in claim 4, wherein the defoaming agent is a silicone oil defoaming agent.

8. The method for passivating medium and low temperature coal pyrolysis semicoke as claimed in claim 4, wherein the surface coating agent comprises the following components in percentage by mass:

25 to 50 percent of water glass

1 to 2 percent of surfactant

47 to 73 percent of water

1% of silicone oil defoaming agent.

9. The method for passivating medium and low temperature coal pyrolysis semicoke as claimed in any one of claims 5 to 8, wherein the surface coating agent comprises the following components in percentage by mass:

40 percent of water glass

1% of surfactant

58 percent of water

1% of silicone oil defoaming agent.

Background

The coke quenching, passivation and storage and transportation of the pyrolytic semicoke are very important links in coal quality-based utilization, and as the coal quality-based utilization technology in China becomes mature day by day, the coke quenching, passivation and storage and transportation technology of the pyrolytic semicoke becomes one of the key points and difficulties in development of the coal quality-based utilization technology. The pyrolysis semicoke has a large amount of active functional groups, a developed pore structure and a large specific surface area, the pyrolysis technology in China mainly takes lump coal pyrolysis and wet coke quenching as the main materials at present, and dry coke quenching cools the hot semicoke by inert gas, recycles the sensible heat of the semicoke, greatly reduces water consumption, ensures the quality of the semicoke, and gradually becomes the first-choice coke quenching mode of the pyrolysis technology. However, the semi-coke after dry quenching has low water content and a developed pore structure, and a large number of active functional groups are easy to contact with oxygen and oxidize to raise the temperature, so that the risk of semi-coke spontaneous combustion is correspondingly increased, the safe storage and transportation of the semi-coke are influenced, and the use radius of the semi-coke is reduced.

One of the prior passivation processes is carried out by spraying an aqueous solution containing an oxidant, but the spraying of the oxidant has higher cost and higher requirements on equipment, sites and environmental protection. The other method is to spray Ca (OH)2 aqueous solution and then perform solidification reaction with carbon dioxide to reduce the surface area of the semicoke, the Ca (OH)2 solubility is very low, and the method has large water consumption and low efficiency.

Disclosure of Invention

The invention aims to solve the problem of oxygen absorption and spontaneous combustion of the low-temperature pyrolysis semicoke, especially the powdered coke in coal, reduce the risk of spontaneous combustion of the semicoke, facilitate the safe storage and transportation of the semicoke and enlarge the use radius of the semicoke.

In order to achieve the technical effects, the technical scheme of the invention is as follows:

the invention provides a method for passivating medium and low temperature coal pyrolysis semicoke, which sequentially comprises the following steps:

passivating carbon dioxide gas of medium-low temperature coal pyrolysis semicoke, fully contacting pyrolysis semicoke with the particle size of 75-100 microns and the temperature of 650 ℃ with carbon dioxide gas at the temperature of 25 ℃, after the high-temperature semicoke is contacted with low-temperature CO2 for heat exchange, reducing the temperature of the semicoke to about 60 ℃, continuously introducing the carbon dioxide gas into the medium-low temperature coal pyrolysis semicoke at about 60 ℃, adsorbing carbon dioxide by the semicoke at about 60 ℃, and stopping introducing the gas when the adsorption quantity of the semicoke to the carbon dioxide reaches 18.6cm3/g 2;

and step two, coating and passivating the surface of the semi-coke of the medium-low temperature coal pyrolysis, pouring the surface coating agent into a semi-coke container, fully stirring, filtering and standing until the surface coating agent of the semi-coke is cured.

Preferably, the purity of the carbon dioxide in the first step is more than 95%, and the oxygen content is less than 1%.

Preferably, the carbon dioxide in the first step is recycled after heat is removed.

Preferably, the surface coating agent consists of water glass, a surfactant and water.

Preferably, the surfactant in the surface coating agent component is a cationic surfactant.

Preferably, the water glass modulus in the surface coating agent component is 3.3 and the baume degree is 40 degrees.

Preferably, the defoaming agent is a silicone oil type defoaming agent.

Preferably, the surface coating agent consists of the following components in percentage by mass:

25 to 50 percent of water glass

1 to 2 percent of surfactant

47 to 73 percent of water

1% of silicone oil defoaming agent.

Further preferably, the surface coating agent consists of the following components in percentage by mass:

40 percent of water glass

1% of surfactant

58 percent of water

1% of silicone oil defoaming agent.

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

the invention can realize the utilization of carbon dioxide, can realize the double passivation process of gas passivation and surface treatment passivation, improve the water content of the semicoke, seal the semicoke pores, reduce the oxygen absorption capacity of the semicoke, reduce the risk of spontaneous combustion of the semicoke, ensure the safe storage and transportation of the semicoke and enlarge the use radius of the semicoke.

Drawings

FIG. 1: semi-focal electron micrograph without coating treatment

FIG. 2: 25% water glass coated semi-focal Electron microscopy

FIG. 3: electron microscopy of 50% water glass-coated semicoke

FIG. 4: 40% water glass coated semi-focal Electron microscopy

Detailed Description

The present invention is described in further detail below to enable those skilled in the art to practice the invention with reference to the description.

The coke quenching process of the coal semicoke is a process for removing the heat of the semicoke, and under high temperature, the coke quenching process can not adsorb carbon dioxide and can also desorb other adsorbed gases. Therefore, it is desirable to reduce the temperature of the char to a reasonable level, and at lower temperatures, to facilitate adsorption of inert carbon dioxide by the char. On the whole, the number of generated semicoke micropores is increased after coal pyrolysis, the aperture fractal dimension value of semicoke is increased, the number of small pores in activated carbon in the semicoke is increased, in the process of adsorbing CO2 by the semicoke, the micropores provide places for the adsorption process of CO2, and the mesopores and the macropores provide channels for the process. Higher specific surface area, more porosity and smaller pores are critical to achieve faster physical/chemical adsorption. The technical scheme is that under the atmosphere of normal pressure and pure CO2, the semicoke is passivated by inert gas. The size of the micropores of the semicoke is close to the kinetic diameter of CO2 molecules, the outward diffusion of carbon dioxide gas is very slow after the adsorption, the outward diffusion speed of carbon dioxide is an important factor of the design consideration of the passivation process, the carbon dioxide adsorbed by the micropores plays a role in isolating oxygen, when the semicoke adsorbing the carbon dioxide enters a surface coating passivation stage, a water glass solution added with a surfactant soaks the surface of the semicoke and permeates into the macropores, the semicoke is fully wetted by the water glass solution, then the water glass is further cured, and finally the carbon dioxide is firmly sealed in the micropores of the semicoke, so that the active functional groups on the surface of the semicoke are coated, the macropores on the surface of the semicoke are blocked, the specific surface area is reduced, and the spontaneous combustion risk of the semicoke is reduced.

Example 1:

the particle size of the medium-low temperature coal pyrolysis semicoke is 75-100 microns, the temperature is 650 ℃, carbon dioxide gas with the purity of more than 95 percent and the oxygen content of less than 1 percent at room temperature is fully contacted with 650 ℃ high-temperature semicoke, the temperature is reduced to about 60 ℃ after the high-temperature semicoke is contacted with low-temperature carbon dioxide for heat exchange, the carbon dioxide gas is continuously introduced into the medium-low temperature coal pyrolysis semicoke at about 60 ℃, the semicoke adsorbs carbon dioxide at about 60 ℃, and when the adsorption amount of the semicoke on the carbon dioxide reaches 18.6cm3/g2, the gas introduction is stopped.

Pouring a surface coating agent consisting of the following components in percentage by mass into a semicoke container, fully stirring, filtering and standing:

25 percent of water glass with the modulus of 3.3 and the baume degree of 40 degrees

1 percent of sodium dodecyl benzene sulfonate

74 percent of water

1% of silicone oil defoaming agent.

The experimental results are as follows:

comparing fig. 1 with fig. 2, it can be seen that fig. 1 has many small holes, and the semicoke surface of fig. 2 is flocculent, i.e. amorphous water glass condensate is obtained, and the amorphous water glass is firmly attached to the semicoke surface to realize the semicoke coating.

Adsorption amount of unpassivated semicoke to oxygen: 3.5596cm3/g

The adsorption capacity of the semicoke on oxygen after passivation by the method is as follows: 2.7655cm3/g

The oxygen absorption property of the semicoke is greatly reduced, and spontaneous combustion caused by the oxygen absorption and heat release of the semicoke is avoided.

Example 2:

the particle size of the medium-low temperature coal pyrolysis semicoke is 75-100 microns, the temperature is 650 ℃, carbon dioxide gas with the purity of more than 95 percent and the oxygen content of less than 1 percent at room temperature is fully contacted with 650 ℃ high-temperature semicoke, the temperature is reduced to about 60 ℃ after the high-temperature semicoke is contacted with low-temperature CO2 for heat exchange, the carbon dioxide gas is continuously introduced into the medium-low temperature coal pyrolysis semicoke at about 60 ℃, the semicoke adsorbs carbon dioxide at about 60 ℃, and when the adsorption amount of the semicoke on the carbon dioxide reaches 3/g2 of 18.6cm, the gas introduction is suspended.

Pouring a surface coating agent consisting of the following components in percentage by mass into a semicoke container, fully stirring, filtering and standing:

50 percent of water glass with the modulus of 3.3 and the baume degree of 40 degrees

Ammonium lauryl sulfate 1%

48 percent of water

1% of silicone oil defoaming agent.

The experimental results are as follows:

FIG. 3 shows the semicoke surface is similarly flocculent, i.e. the semicoke surface is an amorphous water glass condensate, and the amorphous water glass is firmly attached to the semicoke surface to coat the semicoke.

Adsorption amount of unpassivated semicoke to oxygen: 3.5596cm3/g

The adsorption capacity of the semicoke on oxygen after passivation by the method is as follows: 2.1381cm3/g

The oxygen absorption property of the semicoke is greatly reduced, and spontaneous combustion caused by the oxygen absorption and heat release of the semicoke is avoided.

Example 3:

the particle size of the medium-low temperature coal pyrolysis semicoke is 75-100 microns, the temperature is 650 ℃, carbon dioxide gas with the purity of more than 95 percent and the oxygen content of less than 1 percent at room temperature is fully contacted with 650 ℃ high-temperature semicoke, the temperature is reduced to about 60 ℃ after the high-temperature semicoke is contacted with low-temperature CO2 for heat exchange, the carbon dioxide gas is continuously introduced into the medium-low temperature coal pyrolysis semicoke at about 60 ℃, the semicoke adsorbs carbon dioxide at about 60 ℃, and when the adsorption amount of the semicoke on the carbon dioxide reaches 3/g2 of 18.6cm, the gas introduction is suspended.

Pouring a surface coating agent consisting of the following components in percentage by mass into a semicoke container, fully stirring, filtering and standing:

40 percent of water glass with the modulus of 3.3 and the Baume degree of 40 degrees

Dodecyl triethanolamine phosphate 1%

58 percent of water

1% of silicone oil defoaming agent.

The experimental results are as follows:

FIG. 4 shows the semi-coke surface is similarly flocculent, i.e. the semi-coke surface is an amorphous water glass condensate, and the amorphous water glass is firmly attached to the semi-coke surface to coat the semi-coke.

Adsorption amount of unpassivated semicoke to oxygen: 3.5596cm3/g

The adsorption capacity of the semicoke on oxygen after passivation by the method is as follows: 2.4451cm3/g

The oxygen absorption property of the semicoke is greatly reduced, and spontaneous combustion caused by the oxygen absorption and heat release of the semicoke is avoided.

While embodiments of the invention have been disclosed above, it is not limited to the applications listed in the description and the embodiments. It can be applied to all kinds of fields suitable for the present invention. Additional modifications will readily occur to those skilled in the art. The invention is therefore not to be limited to the specific details and examples shown and described herein without departing from the general concept defined by the appended claims and their equivalents.