CN1005314B

CN1005314B - Dry fluidized bed coal preparation method and its device

Info

Publication number: CN1005314B
Application number: CN87101056.9A
Authority: CN
Inventors: 陈清如
Original assignee: China University of Mining and Technology CUMT
Current assignee: China University of Mining and Technology CUMT
Priority date: 1987-05-28
Filing date: 1987-05-28
Publication date: 1989-10-04
Also published as: CN87101056A

Abstract

The invention discloses a novel dry fluidized bed coal dressing device and a method. The device and the method achieve the aim of coal separation by designing a composite, filling and split air distribution device [ 6 ] and a method for combining a multi-stage small-size air distribution device into a large-size air distribution device, applying a fluidized bed in the coal separation process and reasonably selecting the particle size distribution weight percentage and the fluidization number of a mixture taking magnetite powder and quartz sand as heavy media. The invention solves the problems of large water consumption, difficult treatment of slime water and the like in the existing wet coal dressing, has low investment and quick effect and opens up a new way for coal sorting in water-deficient areas.

Description

Dry fluidized bed coal dressing method and device thereof

The invention relates to a dry fluidized bed separation method and a dry fluidized bed separation device for applying fluidized bed technology to a coal dressing process.

The existing coal sorting method adopts wet sorting, and the method not only can cause pollution of residual coal slime after washing, but also has large water consumption and high investment. More than two thirds of the coal in China can be stored in Shaanxi, inner Mongolia, shanxi and other places where water shortage is serious due to drought. There is therefore an urgent need for new dry separation techniques and apparatus.

Although research on this problem has been conducted abroad so far, it is required that such dry separation technique and equipment have high continuous operation characteristics, good separation effect, and no environmental pollution. Therefore, the separation fluidized bed is required to have uniform and stable performance in continuous operation, high separation precision and high production capacity, and can effectively solve the pollution of dust such as separation media.

The patent US3367501 proposes a gas-solid fluidized bed coal separation experimental device and a separation experimental method. The fluidized bed is provided with a comb-shaped chain scraper which is partially positioned outside the shell, and is provided with air distribution chambers which are divided into each other and have adjustable air quantity. However, this patent only proposes a model experimental device and experimental method for dry sorting, focusing on the sorting principle. The actual production throughput is greatly restricted because such devices only perform active discharge of the float (even for the float), while at the same time utilize chemical displacement principles for passive discharge of the float (even for the float). If the discharge speed is increased to expect an improvement in the throughput, the separation effect is necessarily directly affected by affecting the uniformity and stability of the fluidized bed. In addition, the experimental device has no medium removing equipment synchronous with the discharge, no dust removing measures and the like, and the sorting process is limited in practical application due to a series of reasons.

The invention aims to provide a novel dry fluidized bed coal preparation device and a novel dry fluidized bed coal preparation method, which systematically solve the problems of discontinuous discharge, no removal medium equipment, poor air distribution device and poor operation method existing in the dry fluidized bed coal preparation process from the practical point of industrial production, so as to achieve uniform, stable and continuous fluidized bed dry separation.

The invention aims at realizing the aims of adopting an annular anchor chain-scraper output device positioned in a shell, a two-end discharging device with a removal medium, an air distribution device and a rotary feeding device which are positioned at the lower part of the shell and take glass balls as fillers in the device, adopting forced discharging, adopting closed circulation of most heavy media in a separation chamber and adopting reasonable operation methods such as medium types, granularity composition, fluidization number and the like.

The air flow as fluidization medium passes through the air flow regulating and measuring system, then enters the air distribution device at the lower end of the fluidized bed shell through the air pipe, so that the air flow speed is uniform, then enters the upper fluidized bed, and passes through the heavy medium layer formed by mixing the fluidized magnetite powder and quartz sand to flow out. When the airflow speed reaches the initial fluidization speed, raw coal with different particle sizes and added by a rotary feeding device at the upper part of the fluidized bed shell can float under the support of heavy media and suspend at different heights of the bed layer according to the density, so that the aim of sorting is fulfilled. Coal and heavy media may be fed through an upper swivel feed arrangement. The separated clean coal and gangue are output through an annular anchor chain scraper output system arranged in the fluidized bed after passing through a medium removing device.

In addition, in the air distribution device, the air flow firstly enters the pre-air distribution chamber at the bottom to be decelerated and equalized, and the air flow passes through the pre-air distribution plate above at a low speed and stable. The pre-air distribution chamber is a box body with a cuboid upper part and an inverted prismatic table-shaped combination lower part. The pre-air distribution plate adopts a straight hole plate and is directly fastened on angle steel welded on the pre-air distribution chamber shell. In order to make the air flow velocity uniformity as the fluidizing medium better, an incompressible filling layer composed of glass balls is additionally arranged on the upper part of the pre-air distribution plate, and a group of "++" type dividing plates are additionally arranged in the incompressible filling layer to divide the incompressible filling layer into a plurality of blocks in equal volume. Meanwhile, in order to prevent coal particles and heavy media in the fluidized bed layer from falling into the incompressible filling layer at the bottom and further increase the uniformity of the fluidized media, a fabric layer clamped by two layers of screens is arranged on the upper part of the incompressible layer, the two layers of screens are positioned at the joint of the air distribution device and the fluidized bed shell, and the two layers of screens can be clamped by fastening bolts at two sides.

In the separation, the fluidized bed is too large in size, and only a single large-size air distribution device is adopted, so that the fluidization effect is poor. Therefore, the fluidized bed coal dressing device adopts a method of splicing a plurality of air distribution devices, and the air distribution devices of a large-size bed with the required length are formed by longitudinally splicing a plurality of identical small-size air distribution devices.

In addition, the annular anchor chain-scraper output device adopted in the invention consists of a discharging scraper driven by double-chain transmission, a driving wheel, a driven wheel and four guide wheels, wherein the upper scraper and the lower scraper respectively carry out forced reverse discharging on floats and sinkers. Meanwhile, according to the floating and sinking composition characteristics of the separated raw coal, a floating discharge section (namely, a floating medium removing device and an upper anchor chain-scraping plate) and a sinking discharge section (namely, a sinking medium removing device and an upper anchor chain-scraping plate) of the annular anchor chain-scraping plate output device are respectively designed to be at a certain inclination angle. The heavy medium can be used in the bed, and the small part of the heavy medium is removed by the medium removing device and recovered by the magnetic separator. Thereby basically realizing the closed cycle of heavy media in the system in the separation bed and improving the property of the fluidized bed and the stability of the separation effect. The medium removing device is a punching sieve plate.

Compared with the prior art, the invention has the advantages of low cost, less investment, less environmental pollution and the like besides the advantage of no water consumption, and compared with the wet coal preparation plants of the same scale, the invention has the advantages of 2/3 investment cost reduction and 2/3 production cost reduction. The invention opens up a new way for separating coal in water-deficient areas and easy to be muddy when meeting water.

Through the test of density balls with density interstage difference of 0.05g/Cm ³ in a dry fluidized bed sorting device, the possible sorting deviation value Ep=0.025 (Ep-sorting efficiency index) is far better than that of conventional obsolete sorting, and is close to the current wet dense medium sorting effect.

Description of the drawings:

FIG. 1 is a schematic diagram of the structure of a dry fluidized bed coal preparation device;

FIG. 2 is a schematic diagram of the main cross section of the structure of the air distributor in the dry fluidized bed coal preparation device;

FIG. 3 is a cross-sectional top view of the A-A plane of FIG. 2.

Embodiments of the present invention will be described in further detail below with reference to fig. 1-3.

The dry fluidized bed coal preparation device comprises a shell (3), wherein the shell (3) is similar to an inverted trapezoid, a floating object outlet (15) and a sediment outlet (20) are respectively arranged on two sides of the upper end of the shell, a raw coal feeding port and a heavy medium feeding port (2, 1) are respectively arranged at the top of the shell (3), air suction ports (1, 6) are respectively arranged, and a rotary feeding device (8) for uniformly feeding is arranged on the feeding ports. The annular anchor chain-scraper output device (1) is composed of a main driving wheel (17) and a driven wheel (18) which are respectively arranged at two sides of the upper end in the shell (3), four guide wheels (19) which are arranged at the bottom and the upper part of the fluidized bed in parallel, and an annular structure with the bottom formed by the anchor chain-scraper being horizontal and two sides respectively having a certain inclination angle. Punching screen plate removing medium devices (2) and (14) with certain inclination angles are respectively arranged below the upper-layer scraping plate of the annular anchor chain-scraping plate near the floating object outlet (15) and below the upper-layer scraping plate of the annular anchor chain-scraping plate near the sediment outlet (20). An air distribution device (6) is arranged below the shell (3), and the air distribution device is provided with a pre-air distribution chamber (10) with a cuboid upper part and an inverted prismatic table-shaped lower part. The air distribution device is characterized in that the air distribution device is arranged on the upper portion of a pre-air distribution chamber (10) and is provided with a pre-air distribution plate (5) with straight holes, the pre-air distribution plate is fastened on angle steel welded on the wall of the pre-air distribution chamber (10) through bolts, a double-layer screen (4) is arranged above the pre-air distribution plate (5) at a certain distance, a textile layer (13) is clamped between the double-layer screen (4), an incompressible glass ball filling layer (12) with a certain thickness and a diameter of 4-10 mm is filled between the pre-air distribution plate (5) and a lower screen of the double-layer screen (4), a group of "+ +" type division plates (11) divide the incompressible filling layer into a plurality of blocks in an equal volume mode, and an air pipe (9) with one end provided with an adjusting and measuring valve is communicated with the pre-air distribution chamber. The air distribution device arranged at the lower part of the fluidized bed shell (3) can be composed of one or a plurality of air distribution devices (6). The coal or heavy medium is fed into the coal dressing device through the rotary feeding device by the rotation of the impeller. After passing through the airflow regulating and measuring system (7), the airflow serving as the fluidization medium enters the air distribution device (6) at the lower end of the fluidized bed shell (3) through the air pipe (9) to be decelerated and homogenized. Thereafter, the air flow enters the upper fluidized bed shell (3) and contacts heavy medium and raw coal in the fluidized bed, the raw coal enters through a rotary feeding device (8) arranged at the upper end of the fluidized bed shell (3), due to different densities of coal and gangue, after the coal and the gangue are fed into the fluidized bed with certain density, coal with the density smaller than that of the fluidized bed can float, the gangue with the density greater than that of the fluidized bed is sunk at the bottom of the bed, an annular anchor chain-scraper is driven by a main driving wheel (17) at the floating end, the upper scraper moves leftwards as shown by an arrow in fig. 1, the floating matters (namely clean coal) can be discharged from a discharge outlet (15) through a punching sieve plate (2) at the left end of the coal separation device, and the sinking matters (namely the gangue) are discharged from a discharge outlet (20) through a punching sieve plate (14) at the right end of the coal separation device.

In the operation process, the method of controlling the particle size of the medium, the height of the fluidized bed and the fluidization number is adopted to realize continuous and stable operation of the fluidized bed by adopting reasonable medium types besides utilizing an annular anchor chain-scraper system to implement closed cycle of heavy medium and adopting a forced reverse discharge method of floats and sinkers according to the float and sinkers of coal. Through experiments, the optimal parameters of the heavy medium granularity proportion are determined to be 40% by weight of Fe ₃O₄, 0.15-0.30 mm of optimal granularity, 60% by weight of SiO ₂, 0.24-0.48 mm of optimal granularity, 200-400 mm of fluidized bed height and 1.6-2.0 of fluidization number N (wherein N represents the ratio of the working flow rate to the minimum critical flow rate, and if the N value exceeds the range, the fluidized bed production is unstable, namely the density in the bed is unstable, so that the separation cannot be performed).

Claims

1. A dry fluidized bed coal preparation device. The device is provided with a shell (3), an air distribution device (6) is arranged below the shell (3), and an annular anchor chain-scraper output device (1) is arranged in the shell (3), and is characterized in that:

a. The air distribution device (6) is provided with a pre-air distribution chamber (10), a pre-air distribution plate (5) which is arranged at the upper part of the pre-air distribution chamber (10) and is provided with a straight hole, a double-layer screen (4) which is arranged above the pre-air distribution plate (5) at a certain distance, an incompressible glass ball filling layer (12) with a certain thickness is clamped between the double-layer screen (4), and an air delivery pipe (9) with one end provided with an adjusting valve is communicated with the pre-air distribution chamber (10).

B. The upper part of the shell (3) is provided with a raw coal and heavy medium feeding port (21)

C. An air suction port (16) is arranged at the upper part of the shell (3);

d. A floating object outlet (15) and a sinking object outlet (20) are respectively arranged on two sides of the upper end of the shell (3), a punching screen plate medium removing device (2) with a certain inclination angle is arranged below an upper layer scraper of the annular anchor chain-scraper output device (1) close to the floating object outlet (15), and a punching screen plate medium removing device (14) with a certain inclination angle is arranged below a lower layer scraper of the annular anchor chain-scraper output device (1) close to the sinking object outlet (20).

2. A dry fluidized bed coal preparation device according to claim 1, characterized in that the air distribution device (6) is provided with a dividing plate (11) for dividing the incompressible filling layer (12) into a plurality of equal volumes.

3. A dry fluidized bed coal preparation device as claimed in claim 1, characterized in that a rotary feeder (8) is arranged on the raw coal and heavy medium feed (21).

4. A dry fluidized bed coal dressing apparatus according to claim 1, wherein said annular anchor chain-scraper output device (1) is an annular structure with a certain inclination angle on both sides, and is characterized in that a main driving wheel (17) and a driven wheel (18) are respectively arranged on both sides of the upper end in the housing (3), four guide wheels (19) are arranged in parallel on the bottom and the upper part of the fluidized bed, and the bottom of the anchor chain-scraper is horizontal.

5. A dry fluidized bed coal preparation method, which is characterized in that raw coal in a shell (3) of a fluidized bed of a human body is fluidized in an air-heavy medium fluidized bed by feeding air flow to be separated into floats and sinkers (namely clean coal and gangue), and the floats and the sinkers are respectively discharged out of the shell (3) by using an annular anchor chain-scraper output device (1), and the method is characterized in that:

a. And (3) sending air flow into the fluidized bed shell (3) through the air distribution device (6) to uniformly and stably fluidize the heavy medium to form a fluidized bed, wherein the fluidization number N in the fluidization operation process is 1.6-2.0, and the height of the fluidized bed layer is 200-400 mm.

B. The raw coal and heavy media are uniformly fed into the fluidized bed through a feeding port (21) by utilizing a gyratory feeding device (8), and forced reverse discharging is realized by adopting an annular anchor chain-scraper output device (1) and medium removing devices (2) and (14), so that most heavy media are reused in the fluidized bed;

c. The weight percentage of Fe ₃O₄ and SiO ₂ is 40% of Fe ₃O₄, 60% of SiO ₂, and the optimal granularity range of the weight medium in the fluidized bed is 0.15-0.3 mm of Fe ₃O₄ and 0.24-0.48 mm of SiO ₂.