JPS6021768B2 - Cross flow type gas-solid contact device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a cross-flow type gas-solid contacting device in which solid particles and gas are brought into contact by flowing a gas substantially horizontally through a bed of solid particles moving substantially vertically downward.

Cross-flow air contact equipment has been widely used as a treatment device for various exhaust gases, such as S○x and/or N0.
When treating exhaust gas containing .

By the way, the conventional cross-flow type gas-solid contact device has side walls la and lb made of louvers, perforated plates, nets, and other air-permeable holders (louvers in the illustrated example), as shown in a longitudinal sectional front view in FIG. and front and rear walls (not shown) made of an air-impermeable holder to form a tower body with a rectangular cross section, and the side walls la, lb
A hopper 2 is provided below the tower body with a vertical wall continuous to the front and rear walls 2a and 2b, and a bent inclined wall 3 continuous to one of the lower ends of the hopper 2.
A structure in which the roll 4 is disposed in contact with is generally being explored.

Incidentally, number 5 indicates the flow regulation of solid particles. In this device, fresh solid particles or recycled solid particles supplied into the device from the direction of arrow 6 are sequentially moved downward while
After coming into contact with the gas flowing into the device from the direction of arrow 7 and flowing out in the direction of arrow 7' in a cross flow, in other words, the gas is discharged from the device via the roll 4. Since the solid particles passing through the inlet side and the solid particles not passing through the gas outlet side flow down the apparatus at approximately the same moving speed, the following problems cannot be avoided. That is,
When a secondary cross-flow type gas-solid contact device is used to treat S○x-containing exhaust gas using an adsorbent for solid particles,
The adsorbent that has entered the gas-liquid support area (the internal area consisting of the side walls la, lb and the front and rear walls in Figure 1) is saturated with S○x sequentially from the inlet side in the gas flow direction, and this The saturated state gradually progresses toward the gas outlet side, but the adsorbent in this area moves downward as a whole, so in this adsorbent moving bed, as shown in Fig. 1, S decreases as it goes toward the bottom of the moving bed.
The proportion occupied by adsorbent B saturated with ○x increases, and conversely the proportion occupied by unsaturated adsorbent A decreases.

Therefore, if the entire lower part of the moving bed is occupied by an adsorbent saturated with S○x, no S
A problem arises in that ○x cannot be removed by adsorption. Of course, the situation in which the entire lower part of the moving bed is occupied by the adsorbent saturated with S○x can be resolved by increasing the moving speed of the adsorbent, but in this case, the adsorbent that still has adsorption capacity This has the disadvantage that the utilization of the adsorbent is reduced as the result is that the agent is discharged from the device. The undesirable situation described above is not unique to the case where the adsorbent is solid particles or to the desulfurization treatment of exhaust gas. The same problem occurs even when the exhaust gas is denitrified or dust removed.

Particularly in the case of dust treatment, the distribution of soot and dust in the moving bed of furnace filtration agent has a slope corresponding to region B in Figure 1, and the passage resistance of dust-containing gas increases at the bottom of the moving bed. Therefore, not only does the dust-containing gas drift toward the upper part of the moving bed, but this also has the disadvantage of increasing the pressure loss of the entire apparatus. Therefore, the present invention solves the above-mentioned undesirable problems by making the moving speed of solid particles in the moving bed of the cross-flow type gas-solid contact device larger on the gas inlet side than on the gas outlet side. We propose a cross-flow type gas-solid contact device that can avoid this situation.

That is, the present invention provides a cross-flow type gas-solid contact device in which three gases are supplied in a substantially horizontal direction to a bed of solid particles moving almost vertically downward so that they come into contact with each other.
Two solid particle discharge ports are provided on the upstream and downstream sides with respect to the gas flow direction, a first roll is installed below the upstream discharge port, and the same roll as the first roll is installed below the downstream discharge port. The present invention provides the above-mentioned cross-flow type gas-solid contact device characterized in that a second roll having a lower rotation speed in terms of diameter is installed. The gas-solid contact device according to the present invention will be explained below with reference to the drawings. FIG. 2 is a longitudinal sectional front view of the gas-solid contact device which is an embodiment of the present invention, and Solid particles are fed into the device in the direction of arrow 6 and discharged in the direction of arrow 6'.

A tower with a rectangular cross section consisting of two moving beds for solid particles, side walls 21a and 21b made of air-permeable holding bodies such as louvers, perforated plates, nets, etc., and front and rear walls (not shown) made of air-impermeable holding bodies. Formed inside the body. Thus, the gas supplied into the apparatus from the direction of arrow 7 comes into contact with the solid particle bed 20 moving downward in the zero loading tank in a cross flow (also called cross flow), and flows in the direction of arrow 7'. leak. Below the moving bed 20, hoppers 22a and 225b are provided on both the upstream and downstream sides in the gas flow direction.

These two hoppers may be symmetrical to each other with respect to the machine markings. Incidentally, fluid regulators 25a and 25b can be installed in each hopper as necessary. By installing this flow regulator, the flow of solid particles in the hopper becomes even smoother, so it is possible to use a moving bed as in the case where the device of the present invention is used in a desulfurization device that uses an adsorbent such as activated carbon for solid particles. When increasing the moving bed thickness (as seen from the gas) to about 1.5 to 2.5, it is recommended to install a flow regulator, but it is not always essential. Each of the hoppers 22a and 22b is provided with a bent oblique wall 23a and 23b at one of its lower ends, and rolls 24a and 24b having the same diameter and different rotation speeds are disposed in contact with this.

In this case, the upstream roll 24a has a higher rotational speed than the downstream roll. Therefore, within the moving bed 20, solid particles located on the upstream side in the gas flow direction move downward at a greater speed than solid particles located on the downstream side. This situation can be explained using an experimental example as follows. It is as follows. EXPERIMENTAL EXAMPLE A solid particle flow test was conducted without gas flow using an apparatus having the same configuration as in FIG. 2 except that the fluid regulators 25a and 25b were not provided.

For the solid particles, 4 female J spherical porcelain poles were used, the particle bed height (h) was 2 kites, the layer thickness (t) was 1, and the skin width was 0.5.
The hover angle (a) was set to 600. When the rotational speed of the rolls 24a and 24b placed below the hopper was set to the same value and the flow of solid particles was observed, the flow pattern of the particles appearing on the front wall of the device was as shown in Figure 3a. Ta.

Next, the rotational speed of the rolls 24a and 24b was changed, and the rotational speed of the former was set to 1.30% of the latter, and the flow pattern was observed in the same way as in the previous case, and the results shown in Figure 3b were obtained. It was done.

As is clear from this experimental result, if the apparatus of the present invention is used, the particles in the moving bed on the upstream side in the gas flow direction can be caused to flow down at a faster speed than the solid particles on the downstream side. If the moving bed volume, solid particle type and supply/discharge volume, and gas flow rate are the same compared to the conventional apparatus as shown in FIG. 1, the problems experienced with the conventional apparatus can be alleviated.

Also, the system detects changes in the composition or pressure between the gas flowing into the device and the gas flowing out, and accordingly changes the pressure between the rolls 24a and 24a.
When the apparatus of the present invention is equipped with a control means that can adjust the rotation speed ratio with 4b, the flow pattern of solid particles in the moving bed can be maintained at an optimal pattern depending on the composition of the exhaust gas to be treated. . Therefore, if the device of the present invention is used in a desulfurization device, not only can the adsorbent be used effectively, but the pressure loss is also small, and S○x with relatively high soot and dust concentration can be used.
Even when treating contained exhaust gas, there is no need to particularly expand the cross-sectional area of the gas inlet of the moving bed.

In addition, if used in a denitrification device, even if the concentration of pollutants is high,
Even when treating x-containing exhaust gas, the catalyst can be used effectively, and there is no drifting of the gas due to the accumulation of soot and dust, so there is an advantage that an economical superficial velocity can be used. Furthermore, when the device of the present invention is used as a dust collector, there is no uneven flow of gas or increase in pressure loss due to accumulation of dust, so dust-containing gas can be collected using an economical device with a relatively small furnace area. can be processed. EXAMPLE Using a cross-flow type gas-solid contact device having the same configuration as the device shown in Fig. 2 except that the fluid regulators 25a and 25b were not installed, S○xloo gongketsu and butterfly dust were produced at 400 mo/N. Coal boiler exhaust gas containing a temperature of 15 psi was treated.

Granular activated carbon with a particle size of 5 mm was used as the solid particles, the height of the moving bed was 4 mm, the layer thickness was 1.2 mm, and the layer width was 1 mm. Further, the rotation speed of the upstream roll 24a was set to 1.5 times that of the downstream roll 24b, and the average residence time of the granular activated carbon in the moving bed was adjusted to 26.5 hours. In this case, when the above-mentioned coal boiler exhaust gas was supplied to the device at a rate of 300 sails per hour, a desulfurization rate of 90% and a dust removal rate of 80% were obtained. The pressure loss in the moving bed was 15 Aq, and the average adsorption amount of activated carbon discharged from the device was 8.5%. For comparison, when coal boiler exhaust gas was treated in exactly the same manner as above except that the rotational speed of the rolls 24a and 24b was the same, a desulfurization rate of 87% and a dust removal rate of 85% were obtained. The pressure loss was 280 Aq.

In addition, when a similar experiment was conducted by adjusting the moving speed of activated carbon to obtain a desulfurization rate of 90% while maintaining the ratio of the rotational speed of rolls 24a and 24b at 1, it was found that the average amount of activated carbon in the moving bed was Residence time is 2 oil hours, dust removal rate is 78
%.

The pressure loss in the moving bed was 16 Aq, and the average adsorption amount of activated carbon discharged from the device was 7.4%.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional front view of a conventional cross-flow type gas-solid contact device.
FIG. 2 is a longitudinal sectional front view of a cross-flow type gas-solid contacting device according to an embodiment of the present invention, and FIGS. 3a and 3b are explanatory views of the flow pattern of solid particles in a moving bed. la, lb, 21a, 21b... air permeable side wall,
2, 22a, 22b...hopper, 3, 23a, evening 23
b...Bent wall, 4, 24a, 24b.・・・
．． ...Roll, 5, 25a, 25b... Rectifier, 20.
...Moving floor. Box diagram Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. In a cross-flow type gas-solid contact device in which gas is supplied in a substantially horizontal direction to a solid particle bed moving substantially vertically downward so that they come into contact with each other, at the bottom of the solid particle bed, Two solid particle discharge ports are provided on the upstream and downstream sides with respect to the gas flow direction, a first roll is installed below the upstream discharge port, and a first roll having the same diameter as the first roll is installed below the downstream discharge port. The above-mentioned cross-flow type gas-solid contact device is characterized in that a second roll having a low rotational speed is installed. 2 Detecting a change in gas composition or a change in pressure between the gas inlet and the gas outlet, and adjusting the first and second rolls accordingly.
2. The cross-flow type gas-solid contact device according to claim 1, further comprising a control means that can adjust the rotation speed ratio with respect to the roll.