CN107081119B - Reactor for preparing acetylene by cracking coal through thermal plasma array - Google Patents

Abstract

A thermal plasma array pyrolysis reactor for producing acetylene from coal, comprising a coal powder pre-dispersion section, a plasma array reaction section, and a quenching section; multiple rows of plasma electrodes are arranged on the side wall of the plasma array reaction section, and each row of electrodes is It is composed of multiple electrodes, two adjacent rows of electrodes are arranged side by side or staggered, and arc discharge is generated between the electrode pairs to form an array-shaped arc plasma field; the gas carries the pulverized coal through the pulverized coal pre-dispersion section, and the pulverized coal after uniform distribution comes first And through the arrayed arc plasma field formed by the electrodes, the pulverized coal heats up rapidly and reaches thermodynamic equilibrium in a high temperature environment, forming a cracked gas rich in acetylene, and the mixed material through the plasma area enters the subsequent reaction and separation unit to obtain acetylene product. The invention has the characteristics of high coal powder cracking efficiency, high energy utilization efficiency, high acetylene content in the product, long-term stable operation and the like.

Description

A thermal plasma array pyrolysis reactor for acetylene production from coal

technical field

The invention belongs to the technical field of coal chemical industry and acetylene preparation, in particular to a thermal plasma array cracking coal acetylene reactor.

Background technique

Acetylene is an important basic organic chemical raw material. The industrial methods for producing acetylene mainly include calcium carbide method, methane partial oxidation method and plasma cracking method. Among them, the calcium carbide method acetylene process is mature and accounts for an absolute proportion in industrial production, but the pollution and energy consumption are relatively high. Plasma cracking coal to acetylene technology has a short process flow and does not require the high energy-consuming process of producing calcium carbide from limestone, which in turn avoids the generation of calcium carbide slag. A promising route for direct chemical conversion of coal.

Thermal plasma can be conveniently generated by methods such as electric arc, microwave and radio frequency, and the actual operating power can vary from kilowatts in the laboratory to tens of megawatts in the industrial scale. Thermal plasma has unique thermodynamic and transport properties, such as high electro-thermal conversion efficiency, and can conveniently realize a gas environment with an average temperature of 1.5×104K. Coal undergoes three main processes in the hydrogen plasma pyrolysis reactor: devolatilization, volatile gas phase reaction, and quenching of cracked products. Cracking gas of acetylene. After the pyrolysis gas is quenched, separated and purified in milliseconds, gas phase products such as acetylene, hydrogen, carbon monoxide, ethylene and methane are obtained. Part of the product hydrogen is recycled, and the other part is an important by-product of the process. The solid phase products discharged from the reaction process can be directly burned for power supply or mixed with other coal types as raw materials for coal gasification.

In 1963, GB1089092 disclosed a method of producing gaseous and solid products by heating bituminous coal particles at a temperature of 2000-3000 °C. The main products include acetylene and activated carbon. The heating method is mainly obtained by passing coal powder through an arc or plasma jet tail flame. In the 1980s, the rotary arc device of AVCO Company belonged to the former, and the pulverized coal entered the arc area and was directly heated, which had good mixing efficiency. For the cracking of gaseous and liquid hydrocarbons as raw materials, the former is often used. Although the pre-device mixing occurs, to be precise, the reactants enter the arc zone, which is beneficial to the heating and mixing of raw materials and can obtain high acetylene yield, but it is easy to damage the electrodes, and the device structure is relatively complicated.

CN201510777922.8 discloses a plasma cracking coal-to-acetylene reaction device. Coal powder is sprayed into the vertical plasma jet area from the side. However, due to the extremely fast speed of the plasma jet, it is difficult to separate the coal powder and coal powder even if the coal powder is injected at a high speed. The plasma jet mixes thoroughly. In addition, the high-speed injection of pulverized coal limits the size of the nozzle. Larger pulverized coal particles formed during the pulverization process of pulverized coal are likely to cause clogging of the nozzle during the transportation process. Dilute phase transportation is required. Excessive gas introduction will cause the device to Excessive energy consumption.

CN201610082986.0 discloses an electric arc heating pulverized coal acetylene reactor. The arc uses a central plasma torch and multiple plasma torches around it to discharge to form a plasma jet area. The pulverized coal is divided into the first pulverized coal nozzle and the second pulverized coal nozzle. , respectively injected from the central plasma torch and the arc channels of multiple plasma torches around. Due to the high-speed plasma jet, it is difficult for the pulverized coal to fully mix with the plasma jet in the arc channel. After entering the reactor cavity from the arc channel, the flow space of the pulverized coal becomes larger and the speed decreases, making it more difficult for the pulverized coal to fully mix with the plasma jet, resulting in The temperature of pulverized coal pyrolysis is low, and the yield of acetylene is low.

CN201410787386.5 discloses a device for producing acetylene by arc pyrolysis of pulverized coal. Multiple sets of electrodes are arranged on the same plane. Each set of electrodes consists of two electrodes facing each other. Inject straight down, and the second pulverized coal nozzle injects from the wall below each group of electrodes. Due to the high-speed plasma jet, it is difficult for the pulverized coal entering the first pulverized coal nozzle to effectively enter the plasma jet formed by each group of electrodes, and most of them slip off the edge of the plasma jet, and it is even more difficult for the pulverized coal entering the second pulverized coal nozzle to be injected into the plasma jet. Most of them slide down the wall, the high temperature generated by the plasma is difficult to effectively use, and the acetylene yield is low.

Contents of the invention

The technical problem to be solved by the present invention is: to overcome the deficiencies of the prior art, to provide a thermal plasma array pyrolysis coal-to-acetylene reactor, which can effectively mix the pulverized coal with the plasma jet, so that the pulverized coal can be heated up rapidly, and In a high-temperature environment, it reaches thermodynamic equilibrium instantly, forming acetylene-rich pyrolysis gas, which has the characteristics of high coal pulverized cracking efficiency, high energy utilization efficiency, high acetylene content in the equilibrium gas, and long-term stable operation.

The technical scheme adopted in the present invention is: a reactor for thermal plasma array pyrolysis of coal to acetylene, including a coal powder pre-dispersion section, a plasma array reaction section, and a quenching section; Rows of plasma electrodes, each row includes M or M+1 plasma electrodes, the positions of the plasma electrodes in two adjacent rows are corresponding or staggered to form a plasma electrode array; the plasma electrodes on the opposite side walls are connected to the plasma The positions of the plasma electrodes in the body electrode array are in one-to-one correspondence, and the polarity is opposite. The corresponding plasma electrodes on the two side walls form electrode pairs, and arc discharge is generated between the electrode pairs to form an array-like arc plasma field; the gas carries coal powder After passing through the coal powder pre-dispersion section, it is uniformly distributed and then undergoes cracking reaction through the plasma array reaction section, and the cracked products after the reaction enter the quenching section for cooling; wherein, N and M are positive integers.

The pulverized coal pre-dispersion section preheats the incoming pulverized coal and gas mixture through the wall surface or other internal heating methods; the pulverized coal flowing through the pulverized coal pre-dispersion section is realized Uniform distribution in space.

The plasma electrodes in the plasma electrode array are all anodes or anodes and cathodes are arranged alternately, and the electrodes of the two plasma electrodes corresponding to each other on the two side wall surfaces are opposite to each other.

The row spacing between the plasma electrodes in each row in the plasma electrode array is 5-30 cm, and the spacing between the plasma electrodes in each row is 5-30 cm.

The distance between the cathode and the anode in the electrode pair on the two side walls of the plasma array reaction section is 5-30cm, the current between the electrode pair is 100-700A, preferably 500-600A, and the input power of each pair of electrodes is 100kW-2MW .

The plasma electrode adopts graphite electrode or metal electrode, and the plasma electrode can move.

Gas is supplied around the rod-shaped plasma electrode, and the supplied gas is hydrogen or a gas composed of hydrocarbons and hydrogen.

Wall gas nozzles or wall slits are arranged between the plasma electrodes in the plasma electrode array on the wall surface of the plasma array reaction section, and protective gas or cracking raw materials are fed in by jetting or any other means. The protective gas is water vapor, CO ₂ Protective gas, hydrogen or gas composed of hydrocarbons.

The quenching section is provided with nozzles or slits through which the quenching medium is sprayed, and the quenching medium is water, hydrocarbon or coal powder.

Said N is 2-10, and M is 2-20.

The advantage of the present invention compared with prior art is:

(1) The plasma jet array in the present invention can form a uniform high-temperature field in a large space, and the plasma jets that can be fully mixed when the coal powder passes through the plasma jet array from top to bottom ensure that the coal powder can be as high as possible. The thermodynamic equilibrium is reached at a certain temperature, and the concentration of acetylene in the equilibrium cracking gas is high;

(2) In the present invention, there is no need for gas to carry pulverized coal into the plasma jet at a high speed to ensure sufficient mixing of pulverized coal and the plasma jet, reducing the amount of gas carrying pulverized coal into the reactor, and reducing the high-grade energy loss of the plasma jet , high energy utilization rate, good economic benefits;

(3) The plasma electrode in the present invention adopts a push-type electrode, and the electrode can be compensated by horizontal advancement after the discharge time is continuously worn out, which ensures the long-term operation of the plasma reactor;

(4) The reactor wall at the bottom of the plasma electrode in the present invention is provided with a gas nozzle, and the injected cooling gas can protect the reactor wall, avoid damage to the reactor wall, and the reactor can run for a long time.

Description of drawings

Figure 1 is a schematic diagram of a thermal plasma array pyrolysis coal-to-acetylene reactor.

Fig. 2 is a half-sectional schematic diagram of one side of a plasma array reaction section of a thermal plasma array pyrolysis coal-to-acetylene reactor.

Fig. 3 is a half-sectional schematic diagram of the other side of the plasma array reaction section of a thermal plasma array pyrolysis coal-to-acetylene reactor.

Detailed ways

The method provided by the present invention will be further described below through the accompanying drawings, but the present invention is not limited thereto. Many devices are omitted in the figure, such as compressors, valves, pressure control, temperature control, etc.

Figure 1 is a schematic diagram of a thermal plasma array pyrolysis coal-to-acetylene reactor provided by the present invention. Fig. 2 and Fig. 3 are half-section diagrams of the plasma array reaction section of a thermal plasma array pyrolysis coal-to-acetylene reactor provided by the present invention.

A thermal plasma array pyrolysis coal-to-acetylene reactor, comprising a coal powder pre-dispersion section 1, a plasma array reaction section 2, and a quenching section 3; as shown in Figures 2 and 3, the plasma array reaction section 2- N rows of plasma electrodes 4, 4' are arranged on the side wall, each row includes M or M+1 plasma electrodes 4, 4', and the positions of plasma electrodes 4, 4' in two adjacent rows are corresponding or alternately arranged to form Plasma electrode array; the plasma electrodes 4, 4' on the opposite side walls correspond to the positions of the plasma electrodes 4, 4' in the above plasma electrode array, and the polarities are opposite, and the corresponding plasma electrodes on the two side walls 4, 4' form electrode pairs, and arc discharge is generated between the electrode pairs to form an array-like arc plasma field 9; the gas carries coal powder 5 through the coal powder pre-dispersion section 1, and is evenly distributed through the plasma array reaction section 2 for cracking Reaction, the cracked product after the reaction enters the quenching section 3 for cooling; wherein, N and M are positive integers;

Hydrogen or hydrocarbon gas carries the pulverized coal from the reactor inlet into the pulverized coal pre-dispersion section 1. In the pre-dispersion section, the internal member 6 can realize the uniform distribution of the pulverized coal in space and preheat to a certain temperature. Preferably, the internal member 6 of the pulverized coal pre-dispersion section 1 can adopt one or more layers of deflector type distributors.

The evenly distributed and preheated coal powder and gas 5 pass through the arrayed arc plasma jet field 9 formed by multiple sets of electrode pairs from top to bottom. After the coal powder particles are in contact with the plasma jet, they are heated rapidly within a few milliseconds to tens of milliseconds. And release volatile matter to produce small molecule hydrocarbons such as acetylene and ethylene. The plasma jet velocity produced by each pair of plasma electrodes 4, 4' is very fast, and it is difficult for coal powder to directly enter the central area of the plasma jet, so it is difficult to realize the coal powder and plasma jet field generated by a single or several single plasma electrodes. The jet flow is fully mixed, the heating temperature of the pulverized coal particles is low, the equilibrium temperature of the hydrocarbons in the volatile matter is low, and the concentration of acetylene in the equilibrium gas is low. By arranging multiple groups of electrodes in an array, the formed array-like arc plasma jet field 9 can pass through multiple staggered plasma jets to achieve full mixing of coal powder particles and plasma jets, and the coal powder particles are finally heated to 2000~ At 3500K, the acetylene gas in the equilibrium gas reaches a higher concentration.

The walls of the upper or lower space of each row of plasma electrodes in the inner space of the plasma array reaction section 2 are provided with wall gas nozzles or slits 7, which can be sprayed into water vapor or _CO Protective gas 8 or cracking raw materials, the cracking raw materials can be Coal powder, to avoid the reactor wall being damaged by the high temperature field formed by the plasma jet. The pair of plasma electrodes 4 and 4' composed of graphite electrodes or metal electrodes can be moved or replaced. When the pair of plasma electrodes 4 and 4' is continuously consumed at high temperature, the pair of electrodes can gradually move into the reactor to ensure that the reactor can be used for a long time. time stable operation. Around the plasma electrodes 4 and 4 ′, gas is supplied, and the supplied gas is hydrogen or hydrocarbon gas, and the supplied gas is used for distributing the heat generated by the arc in the plasma array reaction section 2 . Substances passing through the plasma array reaction section 2 are fully mixed with the quenching medium 11 sprayed into the reactor space through the nozzles or slits 10 on the wall in the quenching section 3, and the high-temperature cracking products are rapidly cooled to the temperature required by the subsequent section.

Parts not described in detail in the present invention belong to the well-known technology of those skilled in the art.

Claims (4)

1. A reactor for preparing acetylene by cracking coal through a thermal plasma array is characterized in that: comprises a coal dust pre-dispersing section (1), a plasma array reaction section (2) and a quenching section (3); n rows of plasma electrodes are arranged on the wall surface of one side of the plasma array reaction section (2), each row comprises M or M +1 plasma electrodes, and the plasma electrodes in two adjacent rows are arranged correspondingly or in a staggered mode to form a plasma electrode array; the plasma electrodes on the opposite side wall surfaces correspond to the plasma electrodes in the plasma electrode array in position one by one, the polarities are opposite, the corresponding plasma electrodes on the two side wall surfaces form electrode pairs, arc discharge is generated between the electrode pairs, and an array-shaped arc plasma field (9) is formed; the gas carrying coal dust (5) passes through the coal dust pre-dispersing section (1), is uniformly distributed and then is subjected to cracking reaction through the plasma array reaction section (2), and the reacted cracking product enters the quenching section (3) for cooling; wherein N, M is a positive integer;

the pulverized coal pre-dispersing section (1) preheats an entering pulverized coal and gas mixture (5) in a wall surface or other internal heating modes; the coal dust flowing through the coal dust pre-dispersing section (1) is uniformly distributed in space through an inner member (6) arranged in the coal dust pre-dispersing section (1);

all the plasma electrodes in the plasma electrode array are anodes or anodes and cathodes are staggered, and the electrodes of the two plasma electrodes corresponding to each other in position on the two side wall surfaces are opposite;

the plasma electrode is a graphite electrode or a metal electrode and can move;

gas is fed around the plasma electrode, and the fed gas is hydrogen or gas consisting of hydrocarbon;

a wall surface gas nozzle or a wall surface slit (7) is arranged between plasma electrodes in the plasma electrode array on the wall surface of the plasma array reaction section (2), protective gas (8) or cracking raw materials are fed in by gas injection or any other mode, and the protective gas (8) is water vapor and CO₂Shielding gas, hydrogen gas or gas composed of hydrocarbon;

n is 2-10, and M is 2-20.

2. The reactor for preparing acetylene by cracking coal through the thermal plasma array according to claim 1, wherein the reactor comprises: the row spacing between each row of plasma electrodes in the plasma electrode array is 5-30 cm, and the spacing between each row of plasma electrodes is 5-30 cm.

3. The reactor for cracking coal to acetylene by using the thermal plasma array as claimed in claim 1 or 2, wherein: the distance between a cathode and an anode in electrode pairs on the two side wall surfaces of the plasma array reaction section (2) is 5-30 cm, the current between the electrode pairs is 100-700A, and the input power of each pair of electrodes is 100 kW-2 MW.

4. The reactor for cracking coal to acetylene by using the thermal plasma array as claimed in claim 1 or 2, wherein: the quenching section (3) is provided with a nozzle or a slit (10), a quenching medium (11) is sprayed through the nozzle or the slit (10), and the quenching medium (11) adopts water, hydrocarbon or coal powder.