RU2539160C1 - Solid fuel processing device - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: proposed device consists of top, mid and bottom belts. Top belt comprises loading hatch, gas discharge pipe, igniter and hydraulic lock. Mid belt comprises case with water jacket composed by truncated cone diverging from top belt to bottom belt, cone generatrix being inclined to vertical at negative angle α=-5…-10 degrees. It comprises thermoelectric pickups and electromagnetic two-stroke vibrators secured at case top flange extending elements in circle. Bottom belt comprises case composed by truncated cone converging from mid belt to outlet of truncated cone with generatrix inclined to vertical at β=15…20 degrees. It is equipped with discharge assembly, fire grating and thermoelectric pickups. Besides, it comprises coal air blowing assembly or gas cooling assembly.

EFFECT: high-intensity process, higher efficiency and quality, electric power saving.

1 dwg

Description

The invention is used in the field of metallurgy, energy and the chemical industry for layer-by-layer gasification (pyrolysis) of solid fuel (consisting in the ignition of a coal mass, carbon sorbents or other carbon-containing semi-finished product previously buried in the casing, followed by purging of the mass with an air, vapor-air or vapor-oxygen mixture) upon receipt:

- medium temperature coke;

- energy and process gas not containing condensable products.

A device is known for processing solid fuel and producing pure gas, including an upper inlet coal gateway with side nozzles for gas extraction after purging, exhaust steam and a leveling device for the upper layer of coal, a case with a jacket (for evaporative water cooling under a pressure of 30 atm), a mixer, and also located in the lower part of the housing is a rotating grate, an ignition device and a heated gateway with a purge unit (filling the body of a burning coal array) with an oxygen-vapor mixture from the bottom up significant for heating the vapor-oxygen mixture and removing the output product (coke, ash, slag) [1].

The disadvantage of the solution [1] is the extreme saturation of the resulting gas with resinous substances (up to 0.1 kg / m ³ ). This requires additional cleaning from:

- of the resulting gas product (followed by cooling);

- their deposits and condensate accumulated on the inner walls of the pipeline intended for gas removal (approximately every 3 ... 4 months).

Given these circumstances, the long and continuous operation of the device [1] seems impossible.

The disadvantage of the solution [1] is also the presence of an equalizer of the upper layer of coal (conical shape). This requires additional energy consumption, complicates the design, reduces reliability, increases the metal consumption and cost of the device.

These shortcomings lead to an increase in capital and operational investments, to a decrease in the efficiency of the gasification process and, as a result, to a limitation of the scope of the solution [1].

A device for producing coke and associated gas is known, including an upper inlet coal gateway with a layer leveling device and a coal blowing unit from top to bottom, an air-cooled case, as well as a grate, located in the lower third of the height of the case, an ignition device, side pipes for gas extraction after purges and a gateway for coke removal [2].

The disadvantages of the solution [2] are:

- low efficiency of the air cooling system, which leads to unproductive losses of process heat;

- the presence of the equalizer of the upper cone-shaped layer of coal, which requires additional energy consumption, complicates the design, reduces reliability, increases the metal consumption and the cost of the device;

- a complex system for removing solid product from the apparatus, contributing to the formation of the arch of a burnt coal layer and its freezing at the exit of the lower lock.

The closest known technical solution is a solid fuel processing device consisting of upper, middle and lower belts, the upper belt includes a loading hatch, a gas outlet pipe, an electrothermal ignition device and a water seal, the middle belt includes a cylindrical body with a water jacket and thermoelectric sensors, the lower belt includes a housing made in the form of a truncated cone tapering from the middle belt to the outlet, equipped with a grate, an unloading unit, and a thermoelectric electric sensors, as well as a unit for blowing coal with air or cooling gas from the bottom up [3].

Significant disadvantages of the solution [3] are the uneven distribution in the cross section of the coal mass (filling the cavity of the buildings of the middle and lower zones of the device):

- particles of the upper cone-shaped layer, due to which it is necessary to level it;

- particle packing density, pressure on them (it has been practically established that near the longitudinal axis of the bodies of the middle and lower zones, the laying of coal particles is less dense and, accordingly, the pressure acting on them from the side of neighboring particles is less than in the zone of the annular part of the coal mass, located near the inner surfaces of the walls of the enclosures, i.e. there is a decrease in the values of these parameters in magnitude in the direction from the walls of the enclosures to the longitudinal axis);

- flowability of particles constituting a coal mass;

- coal burn-up rate (near the longitudinal axis of the middle and lower girdle casings, its value is much higher than in the zone of the annular part of the coal mass located near the inner surfaces of the walls of the casings, i.e., it increases in the direction from the walls of the casings to the longitudinal axis) .

In addition, in the zone of contact of the coal massif to the inner surfaces of the cylindrical body of the middle belt and the truncated conical body of the lower belt of the device, the coefficient of sliding friction between coal and metal (from which the walls of these bodies are made) plays a significant role, the values of which significantly exceed the values of the coefficient of friction between adjacent to each other by coal particles located outside and near this zone (which is explained by the increased flowability of the material located outside it). It seems that these features are the reason:

- burning of the coal mass to the inner surfaces of the walls of the housing of the middle and lower zones of the device at their contact point;

- sintering a significant (in radial thickness) of the annular part of the coal mass, located near the inner surfaces of the walls of the buildings of the middle and lower zones of the device;

- the formation of a sufficiently rigid arch hanging sintered solid combustion product at the outlet of the discharge device.

This determines:

- the impossibility of continuous continuous operation of the device [3];

- incomplete combustion of harmful impurities in the produced gas, i.e. its insufficient purity (in particular, with a high content of oxygen-containing sulfur products in it), as well as its increased humidity;

- unplanned temporary, material and energy costs for leveling the upper conical layer of coal formed when it is loaded into the working cavity of the device, for separating the burnt and sintered annular part of the coal mass from the inner surfaces of the middle and lower girdle bodies, as well as for the destruction of the arch formed on exit from the unloading unit of the conical body of the lower belt of the device.

These factors lead to an increase in operating costs, to lower efficiency, efficiency, productivity, quality of the finished product and, ultimately, to reduce the profitability of the device [3].

The invention solves the problem of intensification, increasing the efficiency, productivity, quality of the finished product and reducing the specific energy consumption of the coal gasification process.

The technical result consists in solving these problems by eliminating the possible costs of eliminating the need:

- alignment of the upper conical layer of coal formed when it is loaded into the working cavity of the device;

- burning coal mass to the inner surfaces of the walls of the housing of the middle and lower zones of the device;

- sintering a significant in magnitude of the annular part of the coal mass, located near the inner surfaces of the walls of the buildings of the middle and lower zones of the device;

- formation and freezing of the hard arch of the solid fuel combustion product at the outlet of the discharge unit of the conical body of the lower belt of the device.

These tasks are solved by providing at all points of the cross-section of the coal mass filling the cavity (middle and lower device belts of the device) a uniform distribution throughout its volume:

- particle packing density;

- pressure exerted on the particles;

- particle burnup rate.

To achieve the specified technical result in the device for processing solid fuel, consisting of the upper, middle and lower belts, the upper of which includes a loading hatch, a gas outlet, an electrothermal ignition device and a water seal, the middle belt includes a housing with a water jacket and thermoelectric sensors, the lower the belt includes a housing made in the form of a truncated cone tapering from top to bottom, equipped with an unloading unit, a grate, thermoelectric sensors, and also ohm for blowing coal with air or cooling gas from bottom to top, according to the invention, the middle belt body is made in the form of a truncated cone expanding from top to bottom, the generatrix of which is inclined to the vertical at a negative angle α = -5 ... -10 °, the generatrix of the lower belt is inclined to the vertical under angle β = 15 ... 20 °, and on the protruding elements of the upper flange of the middle belt housing evenly arranged around the circumference, three electromagnetic push-pull vibrators are fixed with an oscillation frequency of the working element of 50 Hz, and the gas is fired th or diesel. The expansion of the casing of the middle belt from top to bottom significantly reduces the role of the sliding friction coefficient between coal and the inner conical surface of the casing wall. It seems that due to this, the percentage of probability of burning coal particles to this surface and sintering them in the adjacent annular part of the coal mass at angles of inclination of its generatrix to the vertical:

- smaller (-5 °), large enough;

- equal (-5 °), is within acceptable limits for large particles of coal particles;

- between (-5 °) and (-10 °), it is within acceptable limits for medium-sized coal particles;

- equal (-10 °), is within acceptable limits for fine particles of coal;

- large (-10 °), minimal, but due to an increase in the diameter of the mating of the bodies of the middle and lower zones, this leads to an unjustified increase in the dimensions and metal consumption of the unloading unit.

The percentage of probability of burning of coal particles to the inner conical surface of the lower belt body (tapering from top to bottom), their sintering (in the adjacent annular part of the coal mass), as well as the formation and freezing of the arch of sintered solid combustion product) at the outlet of the discharge unit of the device) at angles between forming the inner conical surface and the vertical:

- less than 15 °, minimal and within acceptable limits for fine particles of coal;

- equal to 15 °, is within acceptable limits for medium-sized coal particles;

- above 15 ° to 20 °, is within acceptable limits for coarse coal particles;

- large 20 °, it is maximum, since in this case the values of these angles approach the critical values of the dynamic angles of repose characteristic for various grades and fractions of coal and coke (within 25 ° ... 35 ° [4]), which is undesirable for reasons preservation of manufacturability, reliability and overall performance of the device.

The placement of the vibrators on the elements of the upper flange of the middle belt body contributes to the uniform distribution of particles, pressure on them, flowability and rate of burnout in the entire volume of the coal mass loaded into the working cavity of the device. Vibration eliminates the role of the coefficient of sliding friction between coal and the inner conical surfaces of the walls of the casings of the middle and lower zones, as well as between the contacting particles of coal of the annular zone located near the walls of these zones, due to the high and more uniform flowability of the material. This feature is explained by the fact that the vibrators:

- transmit short-term forced disturbing impulses to the bodies of the middle and lower belts rigidly connected to each other, and from their inner walls to coal particles (in contact with the latter and between themselves);

- make the coal particles oscillate with a given frequency and amplitude in the mode when the disturbing forces exceed the friction forces.

This intensifies:

- leveling the upper conical layer of the coal mass, loaded into the working cavity of the device, when the vibrators are initially turned on;

- reducing the percentage of probability of burning coal to the walls of the buildings, sintering it in the annular part of the coal mass adjacent to their inner surfaces, as well as the formation and freezing of the body of solid fuel combustion product at the outlet of the discharge unit of the conical case of the lower belt of the device.

The uniform placement (along the connecting circle) of the three vibrators seems to be the most optimal solution, allowing to connect the technical capabilities of each, respectively, the working angle of the coal mass sector covered by it. According to this distinguishing feature in the proposed device for processing solid fuel, the working angle of coverage should be 120 °. There is a possibility that at coverage angles with:

- large values (ie, with 1 ... 2 vibrators), part of the coal mass will not be covered by the vibration field, which will not allow to achieve the expected technical result;

- lower values (i.e., when the number of vibrators is more than 3 ^x ), the technical capabilities of the vibrators will exceed the values of the working angles covered by them, forming the sectors that make up the coal mass, which will lead to excessive energy consumption.

Uniform placement along the connecting circumference of 3 ^x vibrators can also allow the process to be conducted in modes with:

- sequential inclusion of vibrators, due to which the rotating vibration field also sequentially affects all sectors of the array;

- the simultaneous inclusion of three vibrators, which intensifies the vibrational force impact on the coal mass;

- combined, when the first mode periodically alternates with the second, instantly enhancing at a certain moment the force effect on the particles of the coal mass.

The need for these modes can be quite objectively justified and claimed in case of emergency situations in the production environment.

The common advantages of all known electromagnetic vibrators are:

- lack of rubbing parts;

- ease of regulation of the amplitude of the oscillations of the working body, and therefore, productivity by changing the current strength in the windings of an electromagnet.

The advantage of push-pull electromagnetic vibrators is that the disturbing force of attraction of the electromagnets acts in both directions (up and down) and does not give a load to their elastic system. Under the influence of such forces, the vibrator creates not only a directed pulsating force, but also a variable moment, which seems to be a very effective means of solving complex problems associated with the features described above.

The advantage of the operating mode of the working body of the electromagnetic vibrator with a frequency of 50 Hz is that this value is equal to the frequency of the alternating current supplied to the vibrator from the industrial network. For many technological processes, such values of the vibration frequency are the most effective. In practice, such frequencies are generally preferred.

Gas or diesel ignition can reduce the specific energy consumption in the production of medium-temperature coke, as well as energy and process gas that does not contain condensable products.

In addition, when choosing the design of the vibrators, their traction characteristics and control capabilities of the disturbing force were also taken into account (in particular, as noted above, by controlling the amplitude of the oscillation of the working body).

Of course, all the above advantages of the selected type of vibrators are widely known in the art. Therefore, the authors do not claim any novelty associated with the design features of the selected vibrators.

However, in combination with other distinguishing features, the use (in the field of gasification of solid fuel) of the type of vibrational pathogens indicated in this application is unlikely. This is confirmed by the results of a patent search.

The drawing shows a frontal projection of a solid fuel processing device with a number of symbols.

Arrows: single - solid fuel loading; double - slag unloading; triple - air supply; four - the supply of cooling gas; ○ → - removal of gas obtained as a result of gasification of solid fuel.

Latin letters: A - upper belt; B - middle belt; C is the lower belt; OO - vertical (common for upper A, middle B and lower C device belts).

Angles: α - between the generatrix of the inner conical surface of the middle belt case B and the vertical OO, β - between the generatrix of the inner conical surface of the lower belt body C and the vertical OO.

The solid fuel processing device consists of upper A, middle B and lower C belts.

The upper zone A includes a loading hatch 1, an outlet pipe 2 for gas exhaust, a water trap 3 and an electrothermal device 4 for igniting coal. The middle belt B includes a housing 5 with a water jacket 6 and thermoelectric sensors 7.

The lower belt C includes a housing 8 made in the form of a truncated cone (tapering from top to bottom) with a grate 9, an unloading unit 10, thermoelectric sensors 7, and also a unit 11 for purging coal with air or cooling gas from the bottom up.

In contrast to the known device [3] in the proposed solution:

- the body 5 of the middle B belt is made in the form of a truncated cone expanding from top to bottom, the generatrix of which is inclined to the vertical OO at a negative angle α = - (5 ... 10) °;

- the generatrix of the truncated conical body 8 of the lower belt C is inclined to the vertical OO at an angle β = (15 ... 20) °;

- on the protruding elements of the upper flange of the middle belt housing evenly spaced around the circumference, three electromagnetic push-pull vibrators are fixed with an oscillation frequency of the working body of 50 Hz.

A solid fuel processing device operates as follows. Pre-processed solid fuel (e.g. coal, carbon sorbents, or another carbon-containing starting material) is fed through the loading door 1 of the upper belt A of the device (single arrow, see drawing), filling the working cavity of the device to a predetermined level.

The loading hatch 1 is hermetically closed. Drain the water from the valve 3.

Then, in contrast to the known devices [1, 2 and 3], vibrators 12 are turned on, transmitting vibration to the walls of the housings 5 and 8 of the middle B and lower C belts, and through them a layer of the loaded fuel array that contacts them.

The solid fuel particles forming this layer transmit the received impulse to adjacent layers of particles in contact with them. Thus, the received impulse moves to the vertical OO in the form of a circular wave.

In this case, the wave radius decreases from a value equal to the radii of the circles (lying in cross sections of the inner surfaces of the buildings 5 and 8 of the middle B and lower C belts) to zero (at the point of passage of the vertical OO).

When this happens:

- distribution of particles (constituting an array of solid fuel loaded into the working cavity of the device) at all points of the cross-sections of the array over its entire height from chaotic (to start the vibrators) to uniform (after a certain time interval after they are turned on);

- leveling the upper layer of the solid fuel array.

At the same time, electrothermal sensors 7 are turned on.

At the end of the above-described technological operations preceding the main process, an electrothermal ignition device 4 is turned on, operating until the temperature in the zone of the upper layer of the array part (occupying the working cavity of belt A) reaches the temperature of self-ignition of the material of its constituent particles.

This leads to ignition of the upper layer. After a technologically justified time interval has elapsed, air is supplied through the assembly 11 from bottom to top with a predetermined temperature and humidity (adjustable during conditioning).

Air flow is also regulated with a gradual increase from small to nominal level.

Subsequently, using signals from thermoelectric sensors 7, the air flow rate is maintained at a nominal level, determined by:

- properties of solid fuels;

- the cross-sectional area of the loaded fuel array (which, for the middle belt B, in contrast to the known devices [1, 2 and 3], is a variable value);

- the purpose for which the process of processing solid fuel.

During the operation of the device, the combustion front moves from top to bottom from the upper belt A to the grate 9 located in the lower part of the belt C. Moreover (in contrast to the known devices [1, 2 and 3]), the percentage of probability in the proposed solution is almost close to zero :

- burning of coal to the walls of buildings 5 and 8;

- sintering of coal in the annular part of the solid fuel array adjacent to the inner surfaces of the walls 5 and 8;

- the formation of a hard arch (combustion products of fuel) at the outlet of the discharge unit 10 of the conical body 8 of the lower belt C of the device.

This is facilitated by the fact that, in contrast to the known devices [1, 2, and 3], in the proposed solution, the dynamic coefficient of sliding friction (between coal particles and the inner conical surfaces of the walls of the bodies 5 and 8, respectively, of the middle B and lower C zones) is leveled (t .e. significantly reduced) due to the fact that:

- the body 5 of the middle belt B is made in the form of a truncated cone expanding from top to bottom, the generatrix of which is inclined to the vertical OO at a negative angle α = (- 5 ... -10) °;

- the generatrix of the truncated body 8 (tapering from top to bottom) of the lower belt C is inclined to the vertical OO at an angle β = (15 ... 20) °, smaller than the dynamic angle of repose of the fuel (for different grades of coal equal to 25 ... 35 °);

- on the protruding elements of the upper flange of the housing 5 of the middle belt B evenly arranged along the connecting circumference, three electromagnetic push-pull vibrators are fixed with an oscillation frequency of the working body of 50 Hz.

At the moment of approaching the burning front to the grate 9 from the thermoelectric sensors 7, a signal is received, after which the air supply is stopped. The temperature of the solid residue is (600 ... 800) ° C.

To reduce it to 70 ° C (technologically regulated value), the process is switched to cooling mode by switching on the forced circulation of cooling gas along the "device-heat exchanger" circuit with the beneficial use (selection) of thermal energy. As a cooling gas, its own associated gas or chilled products of its combustion are mainly used. To exclude the entrainment from the fuel dust array, the cooling gas flow should not exceed the air flow in the nominal mode. The cooled slag is discharged through the discharge unit 10. The resulting gas is sent for treatment and further processing. Compared with the known solutions [1, 2 and 3], the use of the inventive solid fuel processing device will allow:

- to intensify the process of gasification of solid fuel by eliminating the possibility of sintering significant in size of the annular part of the coal mass, located near the inner surfaces of the walls of the buildings 5 and 8 of the middle B and lower C zones of the device;

- increase efficiency by eliminating the possibility of burning the coal mass to the inner surfaces of the walls of the buildings 5 and 8 of the middle B and lower C zones of the device;

- increase productivity by reducing time spent on leveling the upper layer of the fuel array (after it is loaded into the working cavity of the device), as well as on the hanging of the hard arch of the solid fuel combustion product (at the outlet of the discharge unit 10 of the conical body 8 of the lower belt C of the device);

- improve the quality of the finished gas product by observing the basic requirements for increasing its purity, as well as reducing the percentage of unregulated impurities contained in it, products of incomplete combustion (these requirements are ensured by the uniform distribution of fuel particles, pressure on them, as well as its burning rates all points of the cross sections of the array, over its entire height);

- reduce specific energy consumption by increasing productivity.

Information sources

1. G.-D. Schilling, B. Bonn, W. Kraus, "Gasification of Coal." Translation from German. M .: "Nedra", 1986, p. 43 ... 51, (total p. 176).

2. United Stftes Patent, Patent Number 4883499, Int. CL ⁴ C10B 49/06, C10I 3/14, C01B 31/10., Date of Patent Nov.28, 1989.

3. RU, No. 2299901, IPC C10B 47/04, C10B 53/08, C10I 3/20, Pub. 05/27/2007.

4. EAPO, No. 007800, B1, int. C1. C10B 11/00 (2006.01), C10B 53/08 (2006.01). Date of publication 02.27.2007.

Claims (1)

The solid fuel processing device, consisting of the upper, middle and lower belts, the upper belt includes a loading hatch, a gas outlet, an ignition device and a water seal, the middle belt includes a body with a water jacket and thermoelectric sensors, the lower belt includes a body made in the form of a tapering from the middle zone to the exit of the truncated cone, equipped with an unloading unit, a grate, thermoelectric sensors, as well as a unit for blowing coal with air or cooling gas from bottom to top, characterized in that the middle belt case is made in the form of a truncated cone expanding from the upper zone to the lower one, the generatrix of which is inclined to the vertical at a negative angle α = -5 ... -10 °, the lower belt case is inclined to the vertical at an angle β = 15 ... 20 °, and on the protruding elements of the upper flange of the middle belt housing evenly spaced around the circumference, three electromagnetic push-pull vibrators are fixed with a working frequency of 50 Hz.

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