CN103194263B - A kind of device and method utilizing high temperature alternating current arc to prepare biomass synthesis gas - Google Patents

Abstract

The invention discloses a device and method for preparing biomass synthesis gas by using high-temperature AC arc, which comprises a high-temperature AC arc area and a gas collection area, and the gas collection area is set on the upper part of the high-temperature AC arc area; the lower part of the high-temperature AC arc area Provided with a steam input area. The biomass raw material is put into the gas collection area, the biomass raw material is in reverse contact with the synthetic gas generated during the reaction, and the free fall reaches the high temperature AC arc area, and the superheated steam passed into the lower part of the high temperature AC arc area is in the high temperature AC arc area Instantaneous reaction to generate synthesis gas; the synthesis gas is discharged at the top of the gas collection area, and the ash is discharged from the slag bin at the bottom of the high-temperature AC arc area. The method has a short reaction time for preparing synthesis gas, only 0.01-2 seconds, and normal pressure; the effective gas component is high, (CO+H ₂ ) is greater than 70%, and the ash residue is less (less than 3%).

Description

A device and method for preparing biomass synthesis gas by using high-temperature AC arc

Technical field:

The invention belongs to the field of biological energy, and relates to a device and method for preparing chemical synthesis gas, especially a device and method for preparing biomass synthesis gas by using high-temperature AC arc. The method uses biomass as raw material and steam reforming , can produce syngas with effective gas (CO+H2) greater than 70%.

Background technique:

With the depletion of fossil energy and the increasingly serious environmental problems brought about by its use, human beings will face serious energy crisis and environmental pollution. Biomass energy is an ideal new energy. It has the characteristics of rich resources, high combustion calorific value and wide application range.

Biomass energy is a clean and renewable energy source that contains almost no sulfur, little nitrogen, and has the advantage of nearly zero CO2 emissions. It is estimated that the total amount of bioenergy on the earth is about 140 billion to 180 billion kilotons per year, which is equivalent to 10 times the current total energy consumption in the world. my country has abundant biomass resources. According to statistics in 2006, the biomass resources available for development can reach at least 540 million tons of standard coal. Among them, the annual amount of crop straw is more than 720 million tons, and forestry residue resources are more than 125 million tons. In the future, the amount of energy crops such as fast-growing forests that can be planted on marginal land will be even greater.

Biomass is composed of C, H, O, N, and S. Compared with fossil fuels, it is not only rich in resources but also has high volatile content, high carbon activity, and low sulfur and nitrogen content (S: 0.1%-1.5%; N : 0.5%-3%), low ash content (0.1%-3%) and other advantages. The traditional biomass gas production methods are mainly low-temperature dry distillation and high-temperature oxidation, which produce syngas with high tar content and low effective components.

Invention content:

In order to overcome the defects of the prior art, the present invention provides a device and method for preparing biomass synthesis gas by using a high-temperature AC electric arc. The reaction time required for the preparation of synthesis gas by using the device is short, only 0.01-2 seconds, and the normal pressure state ; The effective gas component is high (CO+H ₂ ) greater than 70%, and the ash residue is less (less than 3%).

Technical scheme of the present invention is as follows:

A device for preparing biomass synthesis gas by using a high temperature AC arc, comprising a high temperature AC arc area and a gas collection area, the gas collection area is set on the upper part of the high temperature AC arc area; the lower part of the high temperature AC arc area is provided with a steam input area.

The device is an electric arc furnace, including a reaction chamber as a high-temperature AC arc area, and a collection chamber as a gas collection area; the upper part of the reaction chamber is provided with a collection chamber, and the collection chamber is used to collect the gas generated during the reaction process; the The top of the collection bin is equipped with a gas pipeline, which is used to transport the gas in the collection bin; the bottom of the reaction bin is provided with a slag bin for discharging the reacted slag; There is a symmetrical electrode set, which is used to generate an AC arc, forming a high temperature AC arc area.

A steam pipe is connected below the electrode group, and the steam pipe is used to feed superheated steam into the reaction chamber.

The electrode group is composed of three, six or nine electrodes, and the electrode heads in the electrode group are arranged symmetrically with respect to the circle center.

Based on the method of the above-mentioned device, the following steps are followed: put the biomass raw material into the gas collection area, the biomass raw material is in reverse contact with the synthesis gas generated in the reaction process, the free fall reaches the high-temperature AC arc area, and communicates with the lower part of the high-temperature AC arc area. The incoming superheated steam reacts instantaneously in the high temperature AC arc area to generate synthesis gas; the synthesis gas is discharged at the top of the gas collection area, and the ash is discharged from the slag bin at the bottom of the high temperature AC arc area.

When there are only inorganic carbon electrodes and water vapor in the high-temperature AC arc area, the reaction generates hydrocarbon chains and realizes the growth of carbon chains. The generated synthesis gas contains methane, ethane and propane.

The CO+H ₂ in the synthesis gas is greater than 70%, and the ash residue is less than 3%.

The biomass raw materials are tree stalks, agricultural and forestry straws, urban organic wastes, plastics, tires and agricultural and forestry wastes.

The particle size of the biomass raw material is 100-150 mesh.

The beneficial effects of the present invention are as follows:

This method has a short reaction time for preparing synthesis gas, only 0.01-2 seconds, and normal pressure; the effective gas component is high, (CO+H ₂ ) is greater than 70%, and the ash residue is less (less than 3%); it is different from the existing production Compared with the material utilization transformation approach, the method for preparing synthesis gas from biomass of the present invention is undoubtedly one of the feasible ways suitable for China's national conditions at present. The synthesis gas produced can be widely used in chemical fields such as synthetic oil, reducing the need for fossil energy. Its promotion and application play an important role in promoting the development of biomass energy utilization technology in China, protecting the environment and improving ecology, and improving farmers' living standards.

Description of drawings:

Fig. 1 is the device structure schematic diagram of the present invention;

Among them: 1 is a gas pipeline; 2 is a collection bin; 3 is a reaction bin; 4 is an electrode group; 5 is a slag bin; 6 is a steam pipeline.

Detailed ways:

The present invention is described in further detail below in conjunction with accompanying drawing:

Referring to Fig. 1, a device for preparing biomass synthesis gas by using a high-temperature AC arc includes a high-temperature AC arc area and a gas collection area, the gas collection area is arranged on the upper part of the high-temperature AC arc area; the lower part of the high-temperature AC arc area is provided with Steam input area.

The device is an electric arc furnace, including a reaction chamber as a high-temperature AC arc area, and a collection chamber as a gas collection area; the upper part of the reaction chamber is provided with a collection chamber, and the collection chamber is used to collect the gas generated during the reaction process; the The top of the collection bin is equipped with a gas pipeline, which is used to transport the gas in the collection bin; the bottom of the reaction bin is provided with a slag bin for discharging the reacted slag; There is a symmetrical electrode set, which is used to generate an AC arc, forming a high temperature AC arc area.

A steam pipe is connected below the electrode group, and the steam pipe is used to feed superheated steam into the reaction chamber.

The electrode group is composed of three, six or nine electrodes, and the electrode heads in the electrode group are arranged symmetrically with respect to the circle center. The electrode group uses alternating current to form a high-temperature spherical arc area. The size of the arc area can be adjusted according to the number of arc rods, which facilitates the rapid expansion of equipment output and avoids the formation of only one heating point for DC arc plasma.

Based on the method of the above-mentioned device, the following steps are followed: put the biomass raw material into the gas collection area, the biomass raw material is in reverse contact with the synthesis gas generated in the reaction process, the free fall reaches the high-temperature AC arc area, and communicates with the lower part of the high-temperature AC arc area. The incoming superheated steam reacts instantaneously in the high temperature AC arc area to generate synthesis gas; the synthesis gas is discharged at the top of the gas collection area, and the ash is discharged from the slag bin at the bottom of the high temperature AC arc area.

When there are only inorganic carbon electrodes and water vapor in the high-temperature AC arc area, the reaction generates hydrocarbon chains and realizes the growth of carbon chains. The generated synthesis gas contains methane, ethane and propane.

The CO+H ₂ in the synthesis gas is more than 70%, and the ash is less than 3%.

The biomass raw materials are tree stalks, agricultural and forestry straws, urban organic wastes, plastics, tires and agricultural and forestry wastes.

The particle size of the biomass raw material is 100-150 mesh.

Biomass pyrolysis and gas generation reactions proceed simultaneously.

C _n H _x O _y (biomass) → CO + H ₂ + C _a H _b O _c (ketones, aldehydes, phenols, acids, ethers, etc.).

The biomass material with a particle size of 100-150 mesh is passed through the screw conveyor from the upper part of the electric arc furnace to the high-temperature AC arc zone formed by the three-phase electrodes of the electric arc furnace. Instant cracking and gasification reactions, the reaction principle is as follows:

The water vapor reacts with the carbon electrode to generate carbon monoxide and hydrogen;

C+ _H2O →CO+ _H2 ;

The pyrolysis reaction of water vapor produces oxygen and hydrogen;

H ₂ O→H ₂ +O ₂ (pyrolysis);

Water vapor is electrolyzed to generate hydrogen and oxygen;

H ₂ O→H ₂ +O ₂ (electrolysis);

Hydrogen pyrolysis into hydrogen atoms;

H ₂ →H+H;

Oxygen is pyrolyzed into oxygen atoms;

O ₂ →O+O;

Sublimation of amorphous carbon aggregates into carbon atoms;

C _n =C+C+C....+(n-3)C;

The gas produced by the reaction is collected from the upper part of the electric arc furnace.

A small amount of tar produced by the reaction can flow back into the reaction zone to generate secondary cracking to reduce the tar content; the tar will undergo cracking and gas generation reactions with superheated steam in the reaction zone.

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; o</span>}<span\; class="notranslate">\; \&Right\; Arrow;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; nCO</span>}<span\; class="notranslate">\; ;</span>$

The reaction equation of inorganic carbon and water vapor to generate carbon chain growth is as follows:

C·+H·→·CH·;·CH·+H·→· _CH2 ·;

CH ₂ + H → CH ₃ ;

· _CH3 +H→ _CH4 ;

2·CH ₃ →C ₂ H ₆ ;·C ₂ H ₄ ·+2H·→C ₂ H ₆ ;

2 CH ₂ → C ₂ H ₄ ; C ₂ H ₄ + CH ₃ → C ₃ H ₇ ;

C ₃ H ₇ + H → C ₃ H ₈ ;

· _CH2 ·+ ₂ · _CH3 → _C3H8 ;

2 CH → (CH) ₂ ;

3 CH → (CH) ₃ ;

Example 1

The wood slag with a particle size of 100-150 mesh (moisture content less than 15%) is passed through the high-temperature AC arc zone formed by the three-phase electrodes of the AC arc furnace through the free fall from the upper part of the electric arc furnace through the screw conveyor, and is carried out instantaneously in the high-temperature AC arc zone. For cracking and gasification reactions, the composition of the synthesis gas is as follows (volume percentage):

H ₂ O ₂ N ₂ CH ₄ CO CO ₂ C ₂ H ₆ C ₃ H ₈ 29.406 3.052 11.354 5.363 30.951 13.537 0.326 0.05

Example 2

Wood slag with a particle size of 100-150 mesh (moisture content less than 15%) passes through the screw conveyor from the upper part of the electric arc furnace to free fall, passes through the high-temperature AC arc area formed by the three-phase electrodes of the AC electric arc furnace, and passes through the superheated The steam undergoes cracking and gasification reactions instantaneously in the high-temperature AC arc zone, and the composition of the synthesis gas is as follows (volume percentage):

H ₂ O ₂ N ₂ CH ₄ CO CO ₂ C ₂ H ₆ C ₃ H ₈ 36.041 1.256 4.41 4.41 35.029 13.486 0.265 0.034

Example 3

The wood slag with a particle size of 100-150 mesh (moisture content less than 40%) is passed through the high-temperature AC arc zone formed by the three-phase electrodes of the AC arc furnace through the free fall from the upper part of the electric arc furnace through the screw conveyor, and is carried out instantaneously in the high-temperature AC arc zone. For cracking and gasification reactions, the composition of the synthesis gas is as follows (volume percentage):

H ₂ O ₂ N ₂ CH ₄ CO CO ₂ C ₂ H ₆ C ₃ H ₈ 40.312 1.454 5.723 3.012 38.047 14.38 0.247 0.052

This patent not only relies on steam to take away heat through the arc area to form a high temperature area, but directly utilizes the temperature of the arc area; avoiding the long heat transfer time and low heat utilization efficiency caused by heat conduction alone. In the high-temperature arc zone, heat absorption and heat conduction can be neglected and the pyrolysis process can be directly entered; heat consumption is greatly reduced, and water vapor and biomass react in the high-temperature arc zone to ensure heat supply.

Use Q to denote heat _absorption , Q _to denote heat conduction, and Q to denote thermal _cracking .

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, may use the method and technical content disclosed above to make some changes or modify equivalent embodiments with equivalent changes, but if they do not depart from the content of the technical solution of the present invention, Any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims (7)

1. A method utilizing high-temperature AC electric arc to prepare biomass synthesis gas, characterized in that: according to the following steps: The biomass raw material is put into the gas collection area, the biomass raw material is in reverse contact with the synthetic gas generated during the reaction, the free fall reaches the high temperature AC arc area, and the superheated steam passed into the lower part of the high temperature AC arc area is in the high temperature AC arc area Instantaneous reaction to generate synthesis gas; the synthesis gas is discharged at the top of the gas collection area, and the ash is discharged from the slag bin at the bottom of the high-temperature AC arc area; when there are only inorganic carbon electrodes and water vapor in the high-temperature AC arc area, the reaction generates carbon Hydrogen chain, and to achieve carbon chain growth, the generated synthesis gas contains methane, ethane and propane. 2. Based on the method according to claim 1, it is characterized in that: the device used comprises a reaction chamber as a high-temperature AC arc region and a collection chamber as a gas collection region, and the collection chamber as a gas collection region is arranged on a high-temperature AC arc region. The upper part of the reaction chamber in the arc area; the lower part of the reaction chamber as a high-temperature AC arc area is provided with a steam input area; the symmetrical electrode group is arranged in the reaction chamber; a steam pipe is connected below the electrode group, and the steam pipe is used for Pass superheated steam into the reaction chamber. 3. based on the described method of claim 2, it is characterized in that: described device is electric arc furnace, comprises a reaction bin as high-temperature AC arc zone, a collection bin as gas collection area; The top of described reaction bin is provided with A collection bin, the collection bin is used to collect the gas generated during the reaction process; a gas pipeline is installed on the top of the collection bin, and the gas transmission pipeline is used to transport the gas in the collection bin; the bottom of the reaction bin is provided with a slag bin, Used to discharge the slag after reaction. 4. The method according to claim 2, characterized in that: the electrode group is composed of three, six or nine electrodes, and the electrode heads in the electrode group are arranged symmetrically to the center of the circle, and the electrode group is used to generate an alternating current arc to form High-temperature AC arc area, the high-temperature AC arc area is a high-temperature spherical arc area. 5. The method according to claim 3, characterized in that: the CO+H ₂ in the synthesis gas is greater than 70%, and the ash is less than 3%. 6. The method according to claim 3, characterized in that: the biomass raw material is tree stalks and agricultural and forestry straws. 7. The method according to claim 3, characterized in that: the particle size of the biomass raw material is 100-150 mesh.