JPS6245322A - Method of treating exhaust gas of catalyst regenerating tower - Google Patents

Abstract

PURPOSE:To enhance heat recovery efficiency, by using the exhaust gas of a catalyst regenerating tower or the exhaust gas of a boiler as the high temp. desorbing gas of an adsorbent subjected to desulfarization and denitration treatment and controlling the flow amount of the desorbing gas while returning the desorbing gas after a desorbing process to the boiler. CONSTITUTION:The exhaust gas to be treated from a catalyst regenerating tower is supplied to a waste heat line 1a from a line 11 and introduced into an adsorbing tower 2 to adsorb SOX in the gas while the treated gas is exhausted out of a system from a line 13. The adsorbent is subsequently sent to a desorbing tower 3 and a part of the exhaust gas from a catalyst regenerating tower is supplied to the desorbing tower 3 to indirectly heat the adsorbent. At this time, the flow amount of desorbing gas is regulated by a valve 24 so as to set desorbing temp. to 350-400 deg.C. The desorbing gas after the desorbing process is returned to a waste heat boiler 1a but mixed with such a gaseous phase that the temp. difference with the desorbing gas is within 50 deg.C to enhance heat-exchange efficiency. As the desorbing gas, the combustion exhaust gas of the waste heat boiler may be used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating exhaust gas from a catalyst regeneration tower, and more specifically, the present invention relates to a method for treating exhaust gas from a catalyst regeneration tower using a carbon-based adsorbent. This invention relates to a dry desulfurization and denitrification process.

Catalyst regeneration tower exhaust gas usually has a 500 to 600
℃, and contains 50 to 100 mg/Nrn' of fine catalyst powder in addition to harmful gases such as sulfur oxides and nitrogen oxides. Furthermore, in the case of incomplete combustion type catalyst regenerated exhaust gas, it also contains carbon monoxide. Therefore, it is essential to treat such exhaust gas and perform heat recovery, desulfurization, and denitrification, and various methods have been used to date. is proposed.

FIG. 1 is an explanatory diagram of a conventional dry desulfurization apparatus, in which 1 is a waste heat boiler or a carbon monoxide combustion boiler (hereinafter abbreviated as a CO boiler), 2 is an adsorption tower, 3 is a desorption tower, and 4 is a desorption tower. indicates a combustion furnace. In this conventional system, the catalyst regeneration tower exhaust gas is supplied to the boiler 1 through a line 11.
In this case, if the exhaust gas is of the complete combustion type, a waste heat boiler is adopted as the boiler 1 to recover heat, and if the exhaust gas is of the incomplete combustion type, a CO boiler is adopted to recover the heat contained in the exhaust gas. Combustion of carbon oxide and heat recovery of combustion gas are performed.

The exhaust gas after heat recovery is then supplied to the adsorption tower 2 through a line 12, where it is subjected to desulfurization and denitration treatment by contact with a carbon-based adsorbent, and the treated gas is discharged from the system through a line 13.

The carbon-based adsorbent that has adsorbed adsorbent substances such as sulfur oxides is extracted from the adsorption tower 2 and guided to the desorption tower 3 via line 14, where it is indirectly heated by high-temperature desorption gas supplied from line 15. The adsorbed substances are desorbed and regenerated. The regenerated adsorbent is circulated to the adsorption tower 2 via line 16.

In addition, as the desorption gas, in the combustion furnace 4, the line 1
The combustion gas obtained by burning the fuel from No. 9 is used. A part of the desorption gas used for desorption in the desorption tower 3 is circulated through the line 18 to the desorption gas introduction line 15,
The remainder is led via line 17 to the inlet line 12 of the adsorption tower 2 or the discharge line 13 of the desorption tower 2. On the other hand, the desorption gas containing desorbed products such as sulfur oxides is sent through line 20 to the sulfur oxide treatment step.

In the conventional method described above, combustion equipment such as a combustion furnace or burner is required to obtain the high-temperature desorption gas, and a large amount of fuel with low sulfur content, such as lamps, 111, etc., must be used. It was economically disadvantageous.

The present invention has been made to solve the above-mentioned problems of the prior art, and by using catalyst regeneration tower exhaust gas upstream of the adsorption tower or CO boiler combustion gas as the high-temperature desorption gas, combustion equipment and fuel Furthermore, by controlling the amount of desorption gas supplied to the desorption tower and returning the desorption gas after the desorption process to a specific part of the boiler, it is possible to desulfurize and/or remove the exhaust gas from the catalyst regeneration tower. Alternatively, it is characterized by performing denitrification treatment continuously and stably and efficiently recovering heat.

That is, according to the present invention, after the catalyst regeneration tower exhaust gas is heat recovered in a waste heat boiler or heat is recovered after combustion in a carbon monoxide combustion boiler, it is led to an adsorption tower where it is desulfurized and desulfurized by contact with a carbon-based adsorbent. / Or in a method for treating exhaust gas from a catalyst regeneration tower, which performs denitrification treatment and guides the adsorbent adsorbing adsorbent substances such as sulfur oxides to the desorption tower and regenerates the adsorbent by indirect heating with high-temperature desorption gas. A part of the catalyst regeneration tower exhaust gas or a part of the combustion exhaust gas of the carbon monoxide combustion boiler is used as the high-temperature desorption gas, and the desorption gas is supplied to the desorption tower so that the desorption treatment temperature is 350 to 400°C. Furthermore, the desorption gas discharged from the desorption tower is returned to the waste heat boiler or the carbon monoxide combustion boiler, and the gas phase in the boiler whose temperature difference with the desorption gas is within 50°C is controlled. Provided is a method for treating catalyst regeneration tower exhaust gas, characterized in that the catalyst regeneration tower exhaust gas is mixed with:

The invention will now be explained in more detail with reference to the drawings.

FIG. 2 is applied when the catalyst regeneration tower exhaust gas to be treated is of a complete combustion type. This figure shows an embodiment of an exhaust gas treatment apparatus for carrying out the method of the present invention, and in the figure, the same members as in FIG. 1 are designated by the same reference numerals. The exhaust gas to be treated from the catalyst regeneration tower is supplied from the inlet 11 to the waste heat boiler 1a, and is then discharged to the outside of the system via the line 12, the adsorption tower 2, and the line 13. The carbon-based adsorbent is circulated between the adsorption tower 2 and the desorption tower 3 through lines 14 and 16, and as described with reference to FIG. These adsorbed substances are desorbed in the desorption tower 3.

In the present invention, desorption in the desorption tower 3 is performed using the treated exhaust gas as a desorption gas. That is, part of the complete combustion type catalyst regeneration tower exhaust gas is supplied to the desorption tower 3 through the line 23. As mentioned above, the temperature of the exhaust gas is 50
The temperature is 0 to 600℃, but this is connected to the gas exhaust line 2 for desorption.
The flow rate is adjusted by the control valve 24 provided at 2 so that the desorption treatment temperature of the desorption tower 3 is in the range of 350 to 400°C. 21 is a thermometer of the regenerated adsorbent. 5: By adjusting the flow rate of the desorption gas supplied to the desorption tower,
Even if the temperature of the exhaust gas to be treated as the desorption gas changes, the temperature of the regenerated adsorbent can be kept constant by responding appropriately, thereby stably operating the adsorption tower.

The desorption tower 3 is operated at 350 to 400°C, and in this case, the temperature of the desorption gas containing desorbed sulfur oxides etc. discharged from the desorption tower 3 through the line 20 is also 350 to 400°C. On the other hand, the exhaust gas is sent to the adsorption tower 2 via the line 12.
), the temperature is below the upper limit temperature for adsorption tower use (usually about 200°C). In the present invention, the desorption gas discharged from the desorption tower 3 is returned to the waste heat boiler 1a, and the heat of this desorption gas is recovered by the waste heat boiler 1a. In this case, the supply position of the desorption gas to the boiler is selected so that it is mixed with the gas phase within the boiler (catalyst regeneration tower exhaust gas) such that the temperature difference is within 50°C. Thereby, the difference in specific gravity of the gases can be minimized, the gases can be mixed efficiently, and therefore the heat exchange efficiency of the waste heat boiler can be maintained at a high value.

FIG. 3 shows one embodiment of an exhaust gas treatment apparatus for carrying out the method of the present invention, which is applied when the catalyst regeneration tower exhaust gas to be treated is of incomplete combustion type. Components that are the same as those in Figure 2 are designated by the same symbols. In the embodiment of FIG. 3, the CO boiler 1b is the waste heat boiler 1a of FIG.
is used instead of. In addition, in the case of Fig. 2, the exhaust gas from the catalyst regeneration tower was directly used as the desorption gas, but in this example, the exhaust gas is first combusted in the CO boiler 11), and the carbon monoxide in the exhaust gas is converted into carbon dioxide. The combustion exhaust gas at this time is supplied to the desorption tower 3 through the line 25 for desorption. The rest is exactly the same as in the case of FIG. In the embodiments shown in Fig. 2 and Fig. 3 above, the temperature of the desorption gas changes depending on the difference in the respective operation modes, but by using the meteor adjustment system 20.21, it is possible to correspond to either mode. Even if the switching is performed, the adsorption process can be performed stably without interruption.

In the above example, the adsorbent was circulated between the adsorption tower and the desorption tower, but in this case, the adsorbent forms a moving bed in each group. However, the present invention is not limited to this embodiment, and it is also possible to adopt a method in which the adsorbent is provided as a plurality of fixed layers, and the gas to be treated and the gas for desorption are switched and introduced into each layer sequentially by valve operation. can.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of a conventional treatment device applied to the treatment of catalyst regeneration tower exhaust gas, and Figures 2 and 3 are applicable to complete combustion type and incomplete combustion type catalyst regeneration tower exhaust gas, respectively. FIG. 2 is an explanatory diagram of an apparatus for carrying out the treatment method of the present invention. In the figure, l...waste heat boiler or carbon monoxide combustion boiler, 1. )... Waste heat boiler, 1b... Carbon monoxide combustion boiler, 2... Adsorption tower, 3... Desorption tower, 4
・Fuel combustion charge, 24...Flow control valve, 21...Thermometer. Patent applicant Chiyoda Corporation Representative Patent attorney Satoshi Ikeura Akiyuki Figure 2 Figure 3

Claims (1)

[Claims] (1) After recovering heat from the catalyst regeneration tower exhaust gas in a waste heat boiler or recovering heat after combustion in a carbon monoxide combustion boiler, it is led to an adsorption tower and subjected to desulfurization and/or denitrification treatment by contacting with a carbon-based adsorbent. In a method for treating a catalyst regeneration tower exhaust gas, the adsorbent that has adsorbed an adsorptive substance is guided to a desorption tower and the adsorbent is regenerated by indirect heating with a high temperature desorption gas, wherein the catalyst regeneration tower exhaust gas is used as the high temperature desorption gas. or part of the combustion exhaust gas of the carbon monoxide combustion boiler, and the desorption treatment temperature of the desorption tower is 350 to 400.
The flow rate of the desorption gas supplied to the desorption tower is controlled so that the desorption gas is returned to the waste heat boiler or the carbon monoxide combustion boiler to be used as the desorption gas. A method for treating exhaust gas from a catalyst regeneration tower, characterized in that the exhaust gas is mixed with a gas phase in a boiler with a temperature difference of 50° C. or less.