FI107641B - Method and apparatus for cooling hot solids in a fluidized bed - Google Patents

Description

107641

Method and apparatus for cooling hot solids in a fluidized bed Technical field

The present invention relates to a method for cooling hot granular solids at a pressure of 2 to 50 bar in a fluidized bed located in a cooling chamber having a solid inlet and a solid outlet, wherein the solids generally move vertically from the solid to the fluid outlet at the opposite end of the fluidized bed and the fluidizing gas of the fluidized bed 10 is passed in the lower region, and heat is removed indirectly through the cooling apparatus through which flows a cooling liquid, which extends at least over half the height of the fluidized bed, and a device for this purpose. The cooling device may be in and / or above the fluidized bed.

A method and apparatus of this type, also suitable for working under high pressure, is known from EP 0 407 730. The object of the invention is to improve the method and apparatus so that construction and operating costs are substantially reduced. In this case, intensive cooling of the solid and a reduced need for fluidized gas are particularly sought.

According to the invention, the object is achieved by the method mentioned above with a bath height of 2 to 20 m and a ratio of bath height to average bath width of 2: 1 to 10: 1 so that the coolant flows in a downstream or opposite direction of solid movement. : .0 relative to the solids inlet to the solids outlet, and that the solids ♦: * ·: 25 have a temperature difference of at least 80 ° C between the lower and upper area of the fluidized bed.

· * · ': This places a fluid bed under pressure in a high, narrow • • cooling chamber, which, with good space utilization, results in a low need for fluidized gas. By forced feeding of the solids, a clear temperature profile is obtained from the inlet through the fluidized bed to the outlet, due to the favorable conduction conditions of the fluidized bed. The fluidization state is the same as in the fixed fluid bed.

: Fluid bed coolers operating at atmospheric conditions or pressures of less than 2 bar can only be used at low bath heights ··· due to annoying blowing arrangements. The method of the invention, wherein the working 35 is operated at a pressure of 2 to 50 bar and preferably at least 5 bar, has a bath height of at least 3 m. This provides a fixed float 107641 2 jet on the lowest possible surface and minimizes the need for fluidized gas.

In the method according to the invention, the ratio of bath height to average bath width is 2: 1 to 10: 1 and preferably at least 3: 1. The average width of the Kyl-5 bath is determined by the average of the largest and smallest bath widths measured in a horizontal plane through the fluidized bed, if the cross-section is not circular. If the bath cross-section changes along the bath height, then the average bath width is determined by the average values of the respective bath cross-sections, which are even, e.g., at 50 cm intervals at different fluid bed heights.

The solids moving in the fluidized bed are forced up and down, depending on the solid inlet and the starting point of the solid. In this case, intense mixing of solids in the vertical direction is not expected, resulting in a solids temperature-lap profile at bath height. Therefore, a consistent upstream flow, or also a consistent downstream flow between the coolant and solids, can be controlled by the upstream and downstream coolant in the cooling system piping. This results in high heat transfer from solids to coolant 20, particularly in countercurrent control. Co-current control has advantages when the solid has to be cooled immediately after entering the fluidized bed, or if the upstream • ·: solid has a vaporizable coolant.

The coolant may be a liquid or a gaseous or vaporous liquid. The known, well-known * ♦ **: 25 coolants include: water, oils, or salt melts, in addition, as heat transporters, for example, water vapor or various gases (e.g., nitrogen).

The hot solids are brought to a temperature of about 300-1200 ° C and • normally these values are in the range of 400-1000 ° C. Also, in a fluidized bed constructed in accordance with the invention, it is possible to increase the temperature difference of the solids between the upper and lower parts of the fluidized bed by 150 ° C and even more.

In a high fluidized bed with a small cross-section constructed in accordance with the invention, the need for a fluidized gas is relatively small. 300 to 7,500 Nm 3 of fluidized bed is discharged per m3 of fluidized bed volume and per hour.

One development of the invention is based on the initial pre-cooling of the hot solids in a pre-activated fluid bed in the second pre-activated second cooling chamber. Also, solids in one of the cooling chambers move from the solid inlet at the end of the second chambers, through a fluidized bed fed predominantly in a vertical direction, to a solids outlet 5 at the opposite end of the second chill. The forward coupled vortex chamber is exposed to approximately the same pressure as the fluidized bed following. Also eteenkytketyssä fluidized bed heat is supplied indirectly from the cooling apparatus, through which cooling fluid flows, wherein the cooling device extends over the fluidized bed upstream side elevation. The fluidized bed height of the forward fluidized bed is in the range of 2 to 10-20 m and the fluidized bed height is preferably at least 3 m. The ratio of fluid height to the average bath width of the feed fluidised bed is 2: 1 to 10: 1. Also in the feed-in fluidized bed, the coolant is directed downstream or counter-current in relation to the movement of solids from the solid inlet to the solid outlet, and the temperature difference between the lower and upper 15 of the feed fluidized bed is at least 80 ° C. In a prefabricated fluidized bed, the pre-cooled solids enter directly from the solids outlet to the stern fluidized bed solids inlet where cooling continues.

It is advantageous if the solids move downwardly between the solid inlet and the solid outlet in the feed-in fluid bed and in the fluidized bed in the rear when cooling continues upward in the fluid bed. to the substance removal point.

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The invention further includes an apparatus for cooling hot, granular solids under pressure in a cooling chamber of 2 to 50 bar having a solids fluid bed, having a solids inlet and a solids outlet, and comprising an indirect bed of solids for the cooling apparatus. and having a fluidized bed feed unit at the bottom. For this purpose: * · *: The cooling chamber is constructed to accommodate a fluidized bed with a bath height of 2 to 20 m and a bath height to average bath width ratio of 2: 1 to 10: 1.

• · ..... 30 The development of this refrigeration system is based on the addition of a second refrigeration chamber with a solid inlet and a solid outlet, adjacent to the cooling chamber: the first cool chamber, whereby the solid outlet is connected to the solid inlet of the first cool chamber.

35 Embodiments of the method and apparatus are explained in the drawing, where: · · 4 107641

Figure 1 schematically shows a longitudinal section of a first cooling apparatus, Figure 2 shows a longitudinal section of a second cooling apparatus, Figure 3 shows a diagram of the need for fluidized gas, Figure 4 shows a longitudinal section of a known fluidized bed cooler.

The apparatus of Fig. 1 has a high, narrow cooling chamber 1 having a solid inlet 2 and a solid outlet 3. The cooling chamber 1 has a fluid bed (10) of granular solids not shown here, which is guided in place by line (4). The fluidized bed extends from the nozzle grate 5 all the way to the outlet 3 and surrounds the coil-bended cooling apparatus line 6 through which the coolant is conducted to remove heat. The fluidizing gas is guided in place along the conduit 8 and initially enters the manifold 9 before it rises through the nozzle grate 5 and forms a vortex 15 in the fluidized bed. Once the fluidizing gases have emerged from the fluidized bed, they initially hate the expanded sedimentation space 10 and exit the refrigeration device via a venting device 11, to which other processing equipment not shown herein, such as dust removal, may be connected.

The cooling chamber 1 is constructed such that the bath 20 of the fluidized bed 20 has a bath height of 2 to 20 m and preferably at least 3 m. The granular solids to be cooled move from the solid inlet 2 to the upstream exit of the fluid chamber, e.g. »» ···: at exit 3. Cooled granular solids move solids • · from inlet 2 through a fluidized gas, e.g. solids. To control the amount of solids in the fluidized bed, there may be a conduit 13 at the inlet 2 for supplying a control gas. The cooling chamber 1 and the cooling chamber 10 • · ..... 30 are enclosed within the pressure vessel 12.

*: * The cooling apparatus of Fig. 2 shows a first cooling chamber 1a and a second cooling chamber 1b. Between the cooling chambers 1a and 1b there is an baffle 7, leaving an opening 15 between the nozzle grate 5 and the lower edge of the baffle 7.

\ I. The pressure vessel 16 encloses the cooling chambers and has a solids inlet 35 and a solids outlet 23. The upper edge 7a of the septum 7 is higher than the inlet 22 and the outlet 23. The fluid gases are discharged from the vessel at the outlet 11.

The hot solids introduced from the inlet 22 initially enter the second cooling chamber 1b where the fluidized bed is located, which is referred to herein as the "feed-in fluidized bed". The fluidized gas for the prefabricated fluidized bed is guided in place by a conduit 19, then enters a distribution chamber 20, from where it flows upwardly through a second cooling chamber 1b to an outlet 11. The solids move downwardly through the first fluidized bed 15 and in the vortex chamber in the cooling chamber 1a. The opening 15 has its own fluidized gas supply through a conduit 24 and a distribution chamber 25 located below the nozzle grate 5. By changing the amount of gas introduced along the line 24, the amount of solids passing through the opening 15 can be affected. In this way, a solid stream can be directed to the first cooling chamber 1a like a hydrodynamic valve.

Aperture 15 serves as a solids entry point for the fluidized bed in the first cooling chamber 1a, where the solids move upwardly in the stationary fluidized bed until they leave the cooling device at outlet 23. Fluid gas is introduced through line 26 and passes through the manifold 20. Unlike the representation of Figure 2, mo-. The refrigeration chambers 1a and 1b are disposed in a shield not designed for higher pressures and located in a separate pressure vessel, as shown in Figure 1.

For the first cooling chamber 1a and the second cooling chamber 1b '·' · * 25 and for the fluidized beds therein, what is said for the single fluidized beds for bath height, bath height and; average bath width and the temperature difference between the bottom and the top of the fluidized bed. As will be seen, both the front-link fluidized bed as well as the first cooling chamber 1a may be. In a fluidized bed connected aft, the downstream current or also the counter current * T between the solids and the coolant is controlled, whereby the coolant flows through the cooling apparatus 6a and 6b.

In many applications, fluidized gas velocities are in the range of 0.2 to 0.8 m / s and can be considered to be approximately pressure independent. 3 ”* [. The 35 graphs show the fluidized gas at a speed of 0.5 m / s and a temperature of 500 ° C

and, with solids grain sizes in the fluidized bed 100-400 mm of fluidized gas 6 107641 is enough V (Nm3 per hour and m3 per fluidized bed volume) its observed dependence on pressure p at various bath heights h (h = 1, 2, 5, 10 and 20 m). In this case, for example, point A shows that when p = 10 bars and height h = 1 m, then V = 6,500 has to be worked, but on the other hand, only V is about 5,300 when the same pressure is bath height h = 5 m (point B).

Comparative Example

The following comparison, partially computationally illustrated, compares a conventional known fluidized bed cooler having a flat design according to Figure 4 with the high fluidized bed cooler 10 shown in Figure 1. The fluidized bed cooler of Figure 4 has a housing 30 having a solid inlet 31, a solid outlet 32, a feed system 33 for fluidized gas and is divided by protective partitions into four chambers 35, 36, 37 and 38. Each chamber has a fluidized bed where the solids move over walls 34 31 through fluidized beds up to outlet 32. The Jo-15 fluidized bed bed is indirectly cooled by cooling water supplied with cooling water 39, and the fluidized gas is discharged along line 40.

In the comparative example, each chamber of the apparatus of Figure 4 has a horizontal cross-section of 0.88 m2, as well as a horizontal cross-section of the hover-bed of Figure 1 of 0.88 m2. Other information is given in the following 20 tables:. Figure 4 Figure 1 Height of fluidized bed 0.5 m 2.0 m v: Total volume of fluidized bed 1.76 m3 1.76 m3 T *: 25 Cooling equipment area 36 m2 36 m2

Pressure 10 bar 10 bar • ·: T: Solids production 2500 kg / h 2500 kg / h Cooling water requirement 8 000 kg / h 8 000 kg / h

Fluid gas consumption 48,000 kg / h 12,000 kg / h ···. 30 Temperatures:

T Solids in 700 ° C 700 ° C

Solids out 126 ° C 123 ° C

Cooling water in 30 ° C 30 ° C

Cooling water out 92 ° C 98 ° C

\\\\: 35 Fluidized gas in 150 ° C 150 ° C

Fluidized gas out 146 ° C 123 ° C

7 107641 This information, which is partially calculated, is based on solids consisting of carbon ash with grain sizes in the range of 0.1 to 1 mm. The fluidized gas is air which is passed in all cases at a rate of 0.4-0.7 m / sec through the fluidized bed.

The table shows that with the same fluidized bed volume, the same cooling equipment, the same cooling water requirement and the same fluidized gas velocity, the high fluidized bed bath of Figure 1 will meet one quarter of the fluidized gas need of Figure 4, thus also reducing structural costs. In this case, the dead angles, which experience has shown primarily in the flat-bed fluidized-bed coolers of Figure 4, and whose efficiency is further reduced, are not taken into account in the calculations.

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Claims (1)

A method for cooling hot granular solids at atmospheric pressure up to 50 bar in a first cooling chamber (1a) and a second cooling chamber (1b) between a partition (7) having an opening (15) in its lower region. two cooling chambers which coolable solids form fluidized beds with both cooling chambers, which fluidized beds are in contact with cooling means (6a, 6b) arranged in each of the chambers 10 to be cooled through a second cooling chamber (10) ), the solids in the second cooling chamber being guided downwardly in the vertical direction into the opening (15) of the septum (7), and the solids in the first cooling chamber (1a) are then guided upwards in a generally vertical direction. 15, where fluidized gas is introduced into the lower zone of two fluidized beds and heat is transferred indirectly by means of a cooling medium through which the coolant flows, the bed height of the two fluidized beds being 3 to 20 m and the ratio of the bed height to the width is from 3: 1 to 10: 1, that both the fluidized bed pressure of 5 - 50 bar, the 20 cooling means extend over at least a half case of the fluidized bed height, the cooling fluid in both cooling means flows clockwise * Y direction or in the counter direction of the solid vertical towards the movement, and that the temperature differences of the solids between the lower and upper region of the two fluidized beds are at least 200 ° C. * T *: 25 «I · • ·« * ♦ • • · ♦ ♦ ♦ ♦ ♦ ♦ ♦ 1 1 1 1 10 10 10 10 10 107641 Förfarande för avkylning av Heta, korniga fasta ämnen vid över- at-mosfäriskt tryck änd account trycket av 50 bar i en första sidkammare (1a) och i en 5 andra kylkammare (1b), mellan vilka finns en skiljevägg (7), som i det nedre omradet uppvisar en öppning (15), som förenar tvä kylkamrar, lively fasta ämnen som skall avkylas bildar virvelbäddar i bäda kylkamrarna, lively snare-dar är i contact med kylningsdon (6a, 6b), som är anordnade i ämnen som skall avkylas leds genom det fasta ämnets inlopp (22) 10 Över virvelbädden i den andra kylkammaren (1b), lively fasta ämnen i den andra kylkammaren leds nedvatudsakligen i vertikal riktning account öppningen (15) i skiljeväggen ämnena i den första kylkammaren (1a) led sedan uppat huvudsakligen i vertical l riktning account det fasta ämnets utlopp (23), och varvid svävningsgasen leds account det nedre omradet i tvä snarebäddar och Vär-15 men avleds indirekt med kylningsdonen, genome livestock sowing strömmar, kännetecknat avatt bäddhöjä pä m förhällande account en genomsnittlig bäddbredd är 3: 1 - 10: 1, att trycket head bådbåddarna är 5 - 50 bar, att kylningsdonen sträcker sig minst år höjden av den ifrägavarande årbådnstråms i dörströdnstr. förhällande account det. ·. fasta ämnets vertikala rörelse och att de fasta ämnenas tempurskillnader • · · “V mellan det nedre och det övre omrädet i steaming at 200 ° C. • • 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • · · ··· • · · • ». · · (·· «· · ♦ • · # · • ·