SK282384B6 - Process for cooling hot granulated solid materials - Google Patents

Abstract

The process for cooling hot, granular solids is carried out at a pressure higher than atmospheric pressure up to 5 MPa in a fluidized bed. This fluidized bed is located in a first cooling chamber (1a) with a solids inlet (22) and in a second cooling chamber (1b) with a solids outlet (23), between which there is a compartment (7) which has an opening in the lower area ( 15) connecting the two cooling chambers (1a, 1b). In cooling beds, the solids move predominantly in a vertical direction from the solids inlet (22) to the solids outlet (23). A fluidizing gas is introduced into the lower region of both fluidized beds and the heat is indirectly removed by cooling devices (6a, 6b) through which the cooling fluid is passed. Both fluidized beds have a height of 3 to 20 m and the ratio of the height of the fluidized beds to the average width of the fluidized beds is 3: 1 to 10: 1. A pressure of 0.5 to 5 MPa is maintained in both fluidized beds. The cooling fluid is conducted in both devices (6a, 6b) occupying at least half the height of the respective fluidized bed, in cocurrent or countercurrent to the vertical movement of solids, and the temperature differences of the solids between the lower and upper regions of both fluidized beds are maintained at at least 200 °. C.à

Description

Technical field

The invention relates to a method for cooling hot, granulated solids at a pressure higher than atmospheric pressure up to 5 MPa in a first cooling chamber and a second cooling chamber, between which there is a partition having an opening in the lower region connecting the two cooling chambers. the substances to be cooled form fluid beds in the two chambers which are in contact with the cooling devices located in the two chambers, the solids being cooled being guided by the solids inflow up to the fluidized bed of the second cooling chamber and the second cooling chamber; the solids are further directed predominantly downwardly to the aperture in the compartment, immediately thereafter the solids are predominantly downwardly directed to the solids outlet, and fluidizing gas and heat are introduced into the lower region of the two fluidized beds. is indirectly removed by cooling devices by means of which the cooling fluid is guided.

BACKGROUND OF THE INVENTION

A method of this kind and apparatus suitable for carrying out it are known from EP-A-0 478 418.

It is an object of the invention to improve the method described in the introduction so as to substantially reduce operating costs. In particular, intensive cooling of the solids and less fluidization gas consumption are to be achieved.

SUMMARY OF THE INVENTION

The object is achieved by a method of cooling hot, granulated solids at a pressure above atmospheric pressure up to 5 MPa in a first cooling chamber and a second cooling chamber between which there is a partition having an opening in the lower region connecting the two cooling chambers, the solids to be cooled form fluid beds in the two chambers which are in contact with the cooling devices located in the two chambers, the solids which are to be cooled flowing through the solids at the top of the fluid bed of the second and in the second In the cooling chamber, the solids are further led predominantly downwards to the opening in the compartment. The solids are then led in the first cooling chamber predominantly in a vertical upward direction to the solids effluent, while a fluidizing gas is introduced into the lower region of the two fluidized beds and the heat is indirectly dissipated by the cooling means which conduct the cooling fluid according to the invention. is that fluid beds are used which both have a height of 3 to 20 m and the ratio of the height of the fluid beds to the average width of the fluid beds is 3: 1 to 10: 1, and a pressure of 0.5 to 5 MPa is maintained in both fluid beds. is conducted in both coolants occupying at least half the height of the respective fluidized bed in a co-current or countercurrent to the vertical movement of solids and the temperature differences of the solids between the lower and upper regions of the two fluidized beds are maintained at at least 200 ° C. The fluidized state in the fluidized beds is the same as in the stationary fluidized bed.

Chillers operating at atmospheric conditions or pressures less than 0.2 MPa can only be operated at low fluid bed heights due to disturbing coalescence of bubbles. The process according to the invention, which operates at a pressure of 0.2 to 5 MPa, is a fluidized bed height of at least 3 m. Therefore, the stationary fluidized beds are positioned over the smallest possible base area and a low fluidization gas consumption is maintained.

According to the method of the invention, the ratio of fluid bed height to average fluid bed width is 3: 1 to 10: 1. The average fluid bed width is calculated from the mean of the largest and smallest bed widths measured in the horizontal plane through the fluid bed. the cross-section of the fluidized bed is not circular. When the diameter of the fluidized bed varies at its height, the average width of the fluidized bed is obtained from the mean of the respective diameter values of the different fluidized bed cross-sections made at the same distances, for example 50 cm at different heights of the fluidized bed.

In the fluidized bed, the solids to be cooled, depending on the state of the solids inlet and solids, move upwards or downwards. Intensive mixing of the solids in the vertical direction is not to be expected, so that the solids temperature profile is set above the bed height. Therefore, a consistent countercurrent or even a consistent co-current between the cooling fluid and the solids can be set by means of the cooling fluid flowing in the cooling device duct, up or down in the fluidized bed. In particular, this leads to a large heat transfer from the solids to the cooling fluid when being conducted in countercurrent. The co-stream is advantageous when the solid is to be cooled directly upon entry into the fluidized bed or when the coolant fluid is to be evaporated in an upstream controlled solids stream.

The cooling fluid may be a liquid or even a gaseous fluid or a vapor fluid. Suitable known cooling fluids are, for example, water, oils, or salt melts, furthermore, for example, water vapor or various gases (e.g. nitrogen) for heat dissipation.

Hot solids are fed at a temperature of about 300 to 1200 ° C, and typically these temperatures are in the range of 400 to 600 ° C. It is also possible to produce a temperature difference of solids between the lower and upper regions of the fluidized bed of 150 ° C and higher in the fluidized bed formed according to the invention.

With a high fluidized bed constructed according to the invention with smaller surface diameters, fluidization gas consumption is relatively low. Per m ³ of fluidized bed volume per hour, 300 to 7500 Nm ^{3 of} fluidizing gas is sufficient.

A further embodiment of the invention is that the hot solids are first pre-cooled in the upstream second cooling chamber, in the upstream fluidized bed. Also in the second cooling chamber, the solids move from the solids inlet at one end of the second cooling chamber to a predominantly vertical fluidized bed to the solids outlet at the opposite end of the second cooling chamber. There is approximately the same pressure in the upstream fluid chamber as in the next fluidized bed. Even in the upstream fluidized bed, heat is removed by a cooling device through which the cooling fluid flows, whereby the cooling device extends over at least half the height of the upstream fluidized bed. In the upstream fluidized bed, the bed height is in the range of 2 to 20 m, and preferably the bed height is up to 3 m on average. The ratio of the bed height to the average width of the upstream fluidized bed is 2: 1 to 10: 1 and preferably at least 3: 1. Even in the upstream fluidized bed, the cooling fluid is conducted in co-current or countercurrent to solids movement from solids to solids and the temperature difference between the lower and upper regions of the upstream fluidized bed is at least 80 ° C and preferably more than 200 ° C. Solids,

Pre-cooled in the upstream fluidized bed pass from the solids outlet directly to the solids inflow in the next fluidized bed where further cooling takes place.

It is preferred that the solids move in a downstream fluidized bed between the solids inlet and the solids outlet downwards and in the connected fluidized bed while further cooling up to the solids outlet of the fluidized bed.

The invention further includes an apparatus for cooling hot granular solids under a pressure of 2 to 50 bar in a refrigeration chamber comprising a fluidized bed of solids having a solids inlet and solids outlet, a cooling means for indirect solids cooling and a lower region of the solids. Fluidising gas supply device. In this case, the cooling chamber is designed to accommodate a fluidized bed having a bed height of 2 to 20 m and a ratio of bed height with bed height to an average bed width of 2: 1 to 10: 1.

A further development of this cooling device is that, in addition to the cooling chamber (first cooling chamber), a second cooling chamber is provided with a solids inlet and solids outlet, the solids outlet being connected to the solids inlet of the first cooling chamber.

Overview of the figures in the drawing

The possibilities of creating the method and the device are explained in the drawing. His fig. FIG. 1 is a schematic representation of a longitudinal section through a first cooling device; FIG. 2 shows a longitudinal section of the second cooling device, FIG. 3 is a diagram for fluidizing gas consumption; FIG. 4 - a known fluid bed cooler in the longitudinal direction.

DETAILED DESCRIPTION OF THE INVENTION

The device of FIG. 1 has a high, slender cooling chamber 1 having a solid inlet 2 and a solid outlet 3. A fluidized bed (not shown) of granular solids which is fed via line 4 is in operation in the cooling chamber 1. The fluidized bed extends from the grate 5 with the nozzles to the outlet 3 and surrounds the piping of the cooling device 6 through which the cooling fluid for heat dissipation . The fluidizing gas is supplied via line 8 and first enters the distribution chamber 9 before it rises through the grate 5 with the nozzles upwards and fluidizes the fluidized bed. Upon exiting the fluidized bed, the fluidizing gases first flow to the extended quenching space 10 and leave the cooling device 6 through an outlet 11, to which other working devices, for example dedusting, may be connected.

The cooling chamber 1 is designed such that the fluidized bed contained therein has a bed height of 2 to 20 m, and preferably at least 3 m. The solid, granular substances to be cooled move from the solid inlet 2 under the action of a fluidizing gas, for example air, in the cooling chamber 1 upwards and leave the fluid bed through the outlet 3. By this predetermined solids movement, the cooling fluid can be cooled. flowing in the cooling device 6, lead in co-current or countercurrent to the solids. To control the amount of solids entering the fluidized bed, a line 13 may be provided in the inlet 2 for supplying the control gas. The cooling chamber 1 and the calming chamber 10 are closed by a pressure-resistant tank 12.

The cooling device of FIG. 2 shows a first cooling chamber 1a and a second cooling chamber 1b. A partition 7 is provided between the first cooling chamber 1a and the second cooling chamber 1b, leaving a hole 15 between the nozzle grate 5 and the bottom edge of the partition 7. The pressure-resistant body 16 closes the cooling chambers. This has an inflow 22 for the solid and an outlet 23 for the solid. The upper edge 7a of the compartment 7 lies higher than the inlet 22 and the outlet 23. Fluidizing gases leave the body 16 through the outlet 11.

The hot solids which are fed through the inlet 22 first enter the second cooling chamber 1b, in which the fluidized bed is located, referred to herein as the "upstream fluidized bed". The fluidizing gas for the upstream fluidized bed is supplied via line 19, enters the manifold chamber 20 and then flows upwardly through the second cooling chamber 1b up to the outlet 11. The solids move upstream of the upstream fluid bed 1b and enter through the opening 15 into the fluidized bed. the beds of the first cooling chamber 1a. The area of the opening 15 has its own fluidizing gas supply through a line 24 and a distribution chamber 25 which is located below the grate 5 with the nozzles. By varying the amount of gas supplied through line 24, the amount of solids entering the orifice 15 can be influenced. In this way, the solids flow to the first cooling chamber 1a can be controlled in the form of a fluid flow valve.

The aperture 15 serves as a solids inflow for the fluidized bed in the first cooling chamber 1a in which the solids move upwardly in the stationary fluidized bed until they leave the cooling device through the outlet 23. The fluidizing gas is supplied via line 26 and enters the manifold chamber 27 and the grate 5 with fluidized bed nozzles. Referring to FIG. 2, the first cooling chamber 1a and the second cooling chamber 1b can also be arranged in a body which is not dimensioned for a higher pressure which is located in a separate pressure body, as shown in FIG. First

For the first cooling chamber 1a and the second cooling chamber 1b, as well as the fluidized beds therein, what has been said previously for the individual beds, with respect to the bed height, the bed height to average bed width ratio, and the temperature difference between the lower and upper regions of the fluidized bed. As can be seen, a co-current or a counter-current can be set in the first cooling chamber 1a between the solids and the cooling fluid, both in the upstream fluid bed and in the subsequent fluidized bed, the cooling fluid flowing through the device 6a and 6b.

In many applications, fluidizing gas velocities are in the range of 0.2 to 0.8 m / s and can be considered approximately independent of pressure.

In the diagram of FIG. 3 is shown for a fluidizing gas velocity of 0.5 m / s and a temperature of 500 ° C, as well as a particle size of the solids in a fluidized bed of 100 to 400 µm with fluidized gas consumption V (in Nm ³ per hour and m ^{3 of} fluidized bed). the observed pressure dependence p for different bed heights h) h = 1, 2, 5, 10 and 20 m). For example, point A shows that a pressure of p -10 bar and a height of h = 1 m and V = 6500 must be operated, whereas at the same pressure and bed height h = 5 m (point B) only V = about 1300 is consumed.

Comparative example

In the comparison, partially calculated, described below, the known fluid bed cooler of the flat construction, as shown in FIG. 4, with a high fluid bed cooler of FIG. 1. The fluid bed cooler of FIG. 4 has

A body 30 with a solids inflow 31, a solids outlet 32, a fluidized-gas supply system 33 and is divided into three hollow partition walls 34 into four chambers 35, 36, 37 and 38. In all chambers 35, 36,37,38 there is a fluidized bed, wherein the solids move through the walls 34 from the inlet 31 through the fluid bed passage to the outlet 32. All fluidized beds are indirectly cooled by a cooling device 39 supplied with cooling water, the fluidizing gas being discharged via line 40 .

In a comparative example, the horizontal cross-sectional area of each chamber of the apparatus of FIG. 4 0.88 m ² , fluid bed according to FIG. 1 also has a horizontal cross-sectional area of 0.88 m ² . Further data can be found in the following table.

Fig. 4 Fig. 1 fluidized bed height 0.5 m 2,0 m total volume 1.76 m ³ 1.76 m ³ fluid bed surface of the cooling device 36 m ² 36 m ² pressure 10 bar 10 bar solid charge 2500 kg / h 2500 kg / h cooling water consumption 8000 kg / h 8000 kg / h fluidization gas consumption 48,000 kg / h 12,000 kg / h Teplotv: solids to 700 ° C 700 ° C solids from 126 [deg.] C Mp 123 ° C cooling water to Deň: 29 ° C Deň: 29 ° C cooling water from 92 ° C 98 ° C fluidizing gas to 150 [deg.] C 150 [deg.] C Fluid gas from 146 ° C Mp 123 ° C

and a fluidizing gas is introduced into the lower region of the two fluidized beds and heat is indirectly removed by cooling means (6a, 6b) through which the cooling fluid is guided, characterized in that fluidized beds are used, both of which are used. they have a height of 3 to 20 m and the ratio of the height of the fluidized beds to the average width of the fluidized beds is 3: 1 to 10; 1 and in both fluidized beds a pressure of 0.5 to 5 MPa is maintained, the cooling fluid being conducted in both cooling devices (6a, 6b) occupying at least half the height of the respective fluidized bed, upstream or countercurrent to vertical movement of solids and temperature differences The solids between the lower and upper regions of the two fluidized beds are maintained at at least 200 ° C.

drawings

Data, which is partially calculated, is based on solids consisting of ash and coal and having a grain size in the range of 0.1 to 1 mm. The fluidizing gas is air, which is in all cases guided through the fluidized bed at a velocity of 0.4 to 0.7 m / sec.

The table shows that with the same fluidized bed volume, the same cooling device, the same cooling water consumption and the same fluidizing gas velocity at the high fluidized bed, as shown in FIG. 1, a quarter of the fluidization gas consumption is sufficient than that of FIG. 4, while also reducing the construction cost. In the calculations, it is not necessary to take into account the dead corners, which, in experience, advantageously appear in the flat bed fluid coolers of FIG. 4 and further impair the efficiency.

Claims (1)

PATENT CLAIMS A method of cooling hot, granulated, solids at a pressure higher than atmospheric pressure up to 5 MPa in a first cooling chamber (1a) and a second cooling chamber (1b) between which there is a partition (7) having an opening in the lower region ( 15) connecting the two cooling chambers (1a, 1b), wherein the solids to be cooled form fluid beds in the two cooling chambers (1a, 1b) which contact the cooling devices (6a, 6b) located in the two cooling chambers (1a, 1b) 1a, 1b), wherein the solids to be cooled are led through the solids inflow (22) upwards to the fluidized bed of the second cooling chamber (1b) and in the second cooling chamber (1b), the solids are further led predominantly downwards to opening (15) in the compartment (7), immediately thereafter the solids are led in the first cooling chamber (1a) predominantly in the vertical direction up to the