JP2009019126A - Regeneration type desulfurization apparatus and desulfurization system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the lowering of heat efficiency involved in the use of a gas for regeneration by applying a dry type desulfurization method to a desulfurization system removing hydrogen sulfide and carbonyl sulfide from the produced gas in a gasification system using a hydrocarbon as a raw material. <P>SOLUTION: Two or more dehydrating towers for absorbing water in a produced gas produced by gasification of a hydrocarbon and two or more desulfurization towers for absorbing a sulfur compound in the downstream of each dehydrating tower are installed so as to change over absorption and regeneration. A zeolite having high selectivity of water absorption is packed in each dehydrating tower, and a zeolite having high selectivity of absorption of hydrogen sulfide and carbonyl sulfide is packed in each desulfurization tower. After water in the produced gas is removed, the produced gas is passed through the desulfurization tower. A gas for regeneration is passed through the dehydrating tower at the time of regeneration to absorb water and the gas for regeneration containing water is used for regeneration of an absorbent packed in the desulfurization tower. The amount of regeneration gas used is reduced thereby. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a regenerative desulfurization apparatus and a desulfurization system that gasify hydrocarbons such as fossil fuels and remove sulfur compounds in the resulting product gas.

  A product gas obtained by gasifying a hydrocarbon such as fossil fuel contains hydrogen sulfide and carbonyl sulfide as sulfur compounds. When generating power using a gas turbine downstream, these are converted to sulfur dioxide in the gas turbine combustor. Sulfur dioxide is harmful and cannot be released to the atmosphere. Therefore, sulfur compounds are removed before being supplied to the gas turbine combustor. In a gas turbine combustor, the product gas is burned with air, so the concentration of sulfur compounds is lower downstream, so removing sulfur dioxide downstream of the gas turbine combustor is more efficient than removing upstream. This is because of a decrease. Further, even when FT gas oil or methanol is synthesized from a gasified product gas using a catalyst, hydrogen sulfide is a component that poisons the catalyst, so it must be desulfurized and supplied to downstream equipment.

  Methods for removing sulfur compounds in the product gas include a wet desulfurization method using an absorbing solution and a dry desulfurization method using an adsorbent.

  Absorption liquids in the wet desulfurization method include a method using an absorption liquid that chemically absorbs a sulfur compound such as amine and methyldiethanolamine, and a method using an absorption liquid that physically absorbs a sulfur compound such as methanol.

  For example, Patent Document 1 discloses a method for removing a sulfur compound using an absorbing solution. This process consists of a carbonyl sulfide converter that converts carbonyl sulfide to hydrogen sulfide, an absorption tower that absorbs hydrogen sulfide, a regeneration tower that regenerates the absorption liquid, a reboiler for heating the absorption liquid, and a heat exchanger. Composed. The carbonyl sulfide converter is necessary because the absorbing solution absorbs only hydrogen sulfide. In the carbonyl sulfide converter, the catalyst is used to react carbonyl sulfide with water vapor to convert it into hydrogen sulfide and carbon dioxide. Since this catalytic reaction is suitable at around 200 ° C., it is necessary to heat the product gas to this temperature. Further, since the absorption tower is operated at room temperature, the product gas after leaving the carbonyl sulfide converter needs to be cooled.

  Since it is necessary to raise and lower the temperature in this way, a heat exchanger is necessary and heat loss occurs. The absorption tower and the regeneration tower need to be installed with a shelf or filled with a filler for improving gas-liquid contact. Also, a knockout drum is installed to prevent scattering of the absorbing liquid, or a flash for separating the gas component that volatilizes from the absorbing liquid as the pressure drops to a line that sends the absorbing liquid from the absorption tower to the regeneration tower. Ancillary facilities such as installing a tank are required.

  A method for removing a sulfur compound using an adsorbent is disclosed in Patent Document 2, for example. In this example, metal oxides such as iron, zinc, cobalt, and manganese are used as the adsorbent. These metals become metal sulfides when they adsorb hydrogen sulfide. By supplying a regeneration gas containing oxygen to the metal sulfide, the metal sulfide returns to a single metal and can be used again as an adsorbent. The sulfur content in the regenerated exhaust gas is in the form of sulfur dioxide. In order to repeat the adsorption and regeneration, two adsorption towers are installed, one of which is being adsorbed and the other is regenerated. The tower for filling the adsorbent has a simpler structure than an absorption tower or a regeneration tower used in the absorption method, and can be manufactured at a low cost. However, when the above-described metal is used for the adsorbent, the mechanism of adsorption is due to a chemical change, so that there is a problem that the performance deteriorates due to repeated adsorption and regeneration.

  In Patent Document 3, as a sulfur compound adsorbent mainly composed of hydrogen sulfide, a silica-alumina molded product containing zeolite is immersed in an iron ammonium oxalate solution and then dried and fired. Even with this adsorbent, the mechanism of adsorption is due to a chemical change, so the performance is degraded by repeated adsorption and regeneration.

JP 2000-212581 A (summary) JP-A-1-185393 (Example) JP 63-294944 A (Claims)

  The absorbing liquid process requires a carbonyl sulfide converter that converts carbonyl sulfide to hydrogen sulfide. It is also necessary to heat the product gas to the catalytic reaction temperature in the carbonyl sulfide converter, and to cool the product gas after leaving the carbonyl sulfide converter to room temperature, which is the operating temperature of the absorption tower. Loss occurs and multiple heat exchangers are required.

  On the other hand, in the dry gas purification method, since adsorption and regeneration are repeated using a plurality of towers, a regeneration gas is required, resulting in a decrease in thermal efficiency.

  An object of the present invention is to provide a regenerative desulfurization apparatus and a desulfurization system that can apply a dry desulfurization method and suppress a decrease in thermal efficiency associated with the use of a regeneration gas.

  The present invention relates to a desulfurization apparatus that adsorbs and removes sulfur compounds contained in a product gas of a gasification system using hydrocarbons as a raw material by an adsorbent, and a dehydration tower that adsorbs and removes water contained in the product gas using an adsorbent; Two or more desulfurization towers each for adsorbing and removing sulfur compounds through circulation of the product gas from which moisture has been removed in the dehydration tower are provided, and the product gas is circulated through at least one of the plurality of dehydration towers. The regeneration gas is circulated to at least one other column when the adsorbent is regenerated, and the product gas from which moisture has been removed in the dehydration column is circulated to at least one of the plurality of desulfurization columns. At this time, the adsorbent is regenerated by circulating the regeneration gas that has absorbed moisture in the dehydration tower to at least one other tower.

  The above-described regenerative desulfurization apparatus can be configured to include a heat exchanger that heats the regeneration gas that circulates in the dehydration tower with the product gas that has been circulated to the dehydration tower. Moreover, it can be set as the structure provided with the heat exchanger and the heat exchanger which heats the refinement | purification gas after passing a desulfurization tower with the regeneration waste gas after passing a desulfurization tower.

  The present invention also relates to a regenerative desulfurization system that adsorbs and removes sulfur compounds contained in a product gas obtained by a gasification system using hydrocarbons as a raw material by using an adsorbent. A plurality of dehydration towers to be adsorbed and removed, a plurality of desulfurization towers to adsorb and remove sulfur compounds by circulating a product gas from which moisture has been removed in the dehydration tower, and a product gas before flowing to the dehydration tower A heat exchanger that heats the regeneration gas flowing through the dehydration tower, and a heat exchanger that heats the purified gas purified in the desulfurization tower with the regeneration exhaust gas that has passed through the desulfurization tower. Among the plurality of desulfurization towers, at least one of the desulfurization towers is used to regenerate the adsorbent when the product gas is circulated through at least one tower. Moisture The adsorbent is regenerated by the regeneration gas exiting the dehydration tower in at least one other tower when the generated product gas is circulated, and the regenerated exhaust gas after heating the purified gas is used. A regenerative exhaust gas combustion furnace that burns with gas containing light oil and oxygen, an absorption tower that makes the exit gas of the regenerative exhaust gas combustion furnace come into gas-liquid contact with the limestone slurry, and a dehydrator that recovers gypsum from the limestone slurry. It is a feature.

  Since the present invention is a dry desulfurization apparatus using an adsorbent, a desulfurization system can be constructed with a simple configuration as compared with a method using an absorbent, and the cost can be reduced. In addition, since the water removed from the product gas in the dehydration tower is used as the regeneration gas for the desulfurization tower, the amount of regeneration gas can be reduced. By reducing the amount of regenerated gas, the thermal efficiency of the entire plant is improved.

  In the present invention, a heat exchanger that heats the regeneration gas that circulates in the dehydration tower with the product gas that has passed through the dehydration tower, and a purified gas that has passed through the desulfurization tower with the regenerated exhaust gas that has passed through the desulfurization tower. Providing a heat exchanger is effective for reducing heat loss.

  It is desirable to use zeolite as the adsorbent for the dehydration tower and desulfurization tower. When zeolite is used as an adsorbent, the adsorption mechanism is adsorption by a physical phenomenon. In the case of adsorption by a physical phenomenon, the adsorption capacity is smaller than that of chemical adsorption, but there is little performance degradation due to repeated adsorption and regeneration. Although the frequency of regeneration increases, in the present invention, the amount of regenerated gas can be reduced, so that a decrease in efficiency can be suppressed.

  Since dehydration towers mainly adsorb moisture, zeolite with high moisture adsorption selectivity is used. For example, a hydrophilic zeolite that mainly adsorbs molecules of 3 angstroms or less is packed to adsorb moisture.

  Since the desulfurization tower mainly adsorbs hydrogen sulfide and carbonyl sulfide, a zeolite having high selectivity for adsorbing these gases is selected. For example, a hydrophobic zeolite mainly adsorbing molecules of 4 angstroms or less is packed to adsorb hydrogen sulfide and carbonyl sulfide.

  1 and 2 show the configuration of a regenerative desulfurization apparatus according to this embodiment. The regenerative desulfurization apparatus of this embodiment is composed of two dehydration towers, two desulfurization towers, a heat exchanger, a valve, and the like.

  In the state of FIG. 1, the valves 31b, 32a, 33a, 34b, 35b, 36a, 37a, 38b are in an open state, and the valves 31a, 32b, 33b, 34a, 35a, 36b, 37b, 38a are in a closed state. is there. In this valve open / closed state, the product gas 1 is supplied to the dehydration tower 11 a after the regeneration gas 3 is heated by the heat exchanger 21. In the dehydration tower 11a, moisture in the product gas is removed. The product gas from which moisture has been removed is supplied to the desulfurization tower 12a. In the desulfurization tower 12a, hydrogen sulfide and carbonyl sulfide in the product gas are removed. The purified gas 2 from which the sulfur compound has been removed is heated by the regenerated exhaust gas 4 in the heat exchanger 22. When the sulfur compound adsorption amount in the desulfurization tower 12a is saturated, the valve is opened and closed, and the valve is opened and closed as shown in FIG.

  In the state of FIG. 2, the valves 31a, 32b, 33b, 34a, 35a, 36b, 37b, 38a are in an open state, and the valves 31b, 32a, 33a, 34b, 35b, 36a, 37a, 38b are in a closed state. is there. In this valve open / closed state, the product gas 1 is supplied to the dehydration tower 11 b after the regeneration gas 3 is heated by the heat exchanger 21. The product gas from which moisture has been removed is supplied to the desulfurization tower 12b. In the desulfurization tower 12b, hydrogen sulfide and carbonyl sulfide in the product gas are removed. The purified gas 2 from which the sulfur compound has been removed is heated by the regenerated exhaust gas 4 in the heat exchanger 22. When the sulfur compound adsorption amount in the desulfurization tower 12b is saturated, the valve is opened and closed, and the valve is opened and closed as shown in FIG.

  On the other hand, in the valve open / closed state of FIGS. 1 and 2, regeneration gas 3 is circulated through the dehydration tower and desulfurization tower that do not circulate the product gas to perform regeneration. The regeneration gas 3 is heated by the product gas 1 and then supplied to the dehydration tower to absorb moisture. The regeneration gas that has passed through the dehydration tower and has absorbed moisture is then passed through the desulfurization tower to desorb the sulfur compound from the adsorbent filled in the desulfurization tower.

  The operation method of the regenerative desulfurization apparatus of this embodiment will be described with reference to FIG. In order to control the valve, the gas composition analyzer 41 of the product gas 1 at the inlet of the dehydration tower, the gas composition analyzer 42 of the purified gas 2 at the outlet of the desulfurization tower, the gas composition analyzer 43 of the regenerated exhaust gas, and the amount of purified gas are measured. A flow meter 44 and a valve control device 45 are installed. The gas composition analyzer 41 measures the concentration of hydrogen sulfide and carbonyl sulfide.

  From the gas composition measurement result and the purified gas flow rate, the accumulated sulfur compound adsorption amount adsorbed in the desulfurization tower is obtained by the following calculation formula.

[Sulfur compound concentration] = [hydrogen sulfide concentration] + [carbonyl sulfide concentration]
[Cumulative sulfur compound adsorption amount] = [purified gas flow rate] × ([inlet sulfur compound concentration] − [outlet sulfur compound concentration]) × [operation time]
If this cumulative sulfur compound adsorption amount has reached the set value, and the other adsorption tower has been regenerated and the product gas can be circulated, a valve control signal 46 is transmitted and the valves 31a, 31b are transmitted. Switch between ~ 38a and 38b.

  The regeneration of the desulfurization tower is to desorb the adsorbed sulfur compound. Whether or not the desulfurization tower is in a regenerated state is determined by using the hydrogen sulfide concentration and the carbonyl sulfide concentration in the gas composition analyzer 43 of the regenerated exhaust gas, and both the hydrogen sulfide concentration and the carbonyl sulfide concentration are less than the specified values. And when

  Here, if the time from the start of circulation of the regeneration gas to the completion of regeneration exceeds the specified value, there may be some abnormality such as deterioration of the adsorbent or a decrease in the regeneration gas temperature. Because there is, send an alarm.

  Further, if the outlet sulfur compound concentration reaches a specified value before the cumulative sulfur compound adsorption amount reaches the set value, an alarm is issued because the adsorbent may be deteriorated. At this time, if the conditions allow the product gas to flow to the other desulfurization tower, a valve control signal 46 is transmitted to switch the valves 31a, 31b to 38a, 38b.

  In this embodiment, an example of an adsorbent selection method is shown. In this example, the effective diameter of water molecules is 3 angstroms or less, and the effective diameter of hydrogen sulfide and carbonyl sulfide is 3 angstroms or more.

  The dehydration tower is filled with hydrophilic zeolite that mainly adsorbs molecules of 3 angstroms or more to adsorb moisture, so that hydrogen sulfide and carbonyl sulfide are not adsorbed. The desulfurization tower is filled with a hydrophobic zeolite that mainly adsorbs molecules of 4 angstroms or less so that water is not adsorbed and hydrogen sulfide and carbonyl sulfide are adsorbed.

  By selecting the adsorbent in this way, it becomes possible to selectively adsorb moisture and sulfur compounds in the dehydration tower and the desulfurization tower, respectively.

  In this embodiment, an example of a desulfurization system to which the regenerative desulfurization apparatus of the present invention is applied will be described. FIG. 4 shows a configuration diagram of the regenerative desulfurization system.

  The raw material 5 is gasified 51 with a gas containing oxygen, heat-recovered 52, dust-removed 53, washed with water 54, and then supplied to the dehydrating tower 11a. The dehydrated gas is sent to the desulfurization tower 12a, becomes the purified gas 2 from which the sulfur content is removed, and is sent to a downstream process.

  The regeneration gas 3 is sent to the dehydration tower 11b, and is sent to the desulfurization tower 12b along with moisture adsorbed by the dehydration tower. The regeneration gas accompanied by moisture becomes the regeneration exhaust gas 4 together with the sulfur compound adsorbed on the desulfurization tower 12 b and is supplied to the regeneration exhaust gas combustion furnace 71. In the regenerated exhaust gas combustion furnace, a combustion field is formed by a gas containing light oil 6 and oxygen 7, and the sulfur compound in the regenerated exhaust gas becomes sulfur dioxide. Light oil combustion exhaust gas and regenerated exhaust gas containing sulfur dioxide are sent to an absorption tower 72 and come into gas-liquid contact with a slurry containing limestone 8. Here, the sulfur content in sulfur dioxide is fixed to gypsum. Carbon dioxide 9 is discharged out of the system. The absorbent containing gypsum is sent to the dehydrator 73, and the gypsum 10 is separated.

It is a figure which shows the structure and valve | bulb open / close state of the regenerative desulfurization apparatus by one Example of this invention. FIG. 2 is a view showing a state in which an open / close state of a valve is switched in the regenerative desulfurization apparatus configured as shown in FIG. 1. It is the figure which showed the valve | bulb control method of the regenerative desulfurization apparatus by this invention. It is a block diagram of the regenerative desulfurization system to which the regenerative desulfurization apparatus of the present invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Product gas, 2 ... Refined gas, 3 ... Regeneration gas, 4 ... Regeneration exhaust gas, 5 ... Raw material, 6 ... Light oil, 7 ... Oxygen, 8 ... Limestone, 9 ... Carbon dioxide, 10 ... Gypsum, 11 ... Dehydration tower , 12 ... Desulfurization tower, 31-38 ... Valve, 41-43 ... Gas composition analyzer, 44 ... Flow meter, 45 ... Valve control device, 46 ... Valve control signal, 51 ... Gasification, 52 ... Heat recovery, 53 ... Dedusting, 54 ... water washing, 71 ... regenerated exhaust gas combustion furnace, 72 ... absorption tower, 73 ... dehydrator.

Claims (10)

  In a desulfurization apparatus that adsorbs and removes sulfur compounds contained in a product gas of a gasification system using hydrocarbon as a raw material by an adsorbent, a dehydration tower that adsorbs and removes moisture contained in the product gas by an adsorbent, and When two or more desulfurization towers that adsorb and remove sulfur compounds by circulating the product gas from which moisture has been removed are provided, and when the product gas is circulated through at least one of the plurality of dehydration towers, When the regeneration gas is circulated through at least one of the towers, the adsorbent is regenerated, and at least one of the plurality of desulfurization towers is circulated with the product gas from which water has been removed in the dehydration tower. The regenerative desulfurization apparatus is characterized in that the adsorbent is regenerated by circulating a regeneration gas having absorbed moisture in the dehydration tower to at least one other tower.   In a desulfurization apparatus that adsorbs and removes sulfur compounds contained in a product gas of a gasification system using hydrocarbon as a raw material by an adsorbent, a plurality of dehydration towers that adsorb and remove moisture contained in the product gas by the adsorbent, and the dehydration A plurality of desulfurization towers that adsorb and remove sulfur compounds by circulating the product gas from which moisture has been removed in the tower, and heat exchange that heats the regeneration gas that flows to the dehydration tower with the product gas that flows to the dehydration tower An adsorbent that circulates the regeneration gas heated by the heat exchanger to at least one other column when the product gas is circulated to at least one of the plurality of dehydration columns When at least one of the plurality of desulfurization towers is circulating the product gas from which water has been removed in the dehydration tower, the other dehydration tower absorbs moisture in the dehydration tower. Recycled video Regenerative desulfurization apparatus characterized by distribution to that to perform the regeneration of the adsorbent.   In a desulfurization apparatus that adsorbs and removes sulfur compounds contained in a product gas of a gasification system using hydrocarbon as a raw material by an adsorbent, a plurality of dehydration towers that adsorb and remove moisture contained in the product gas by the adsorbent, and the dehydration A plurality of desulfurization towers that adsorb and remove sulfur compounds by circulating the product gas from which moisture has been removed in the tower, and heat exchange that heats the regeneration gas that flows to the dehydration tower with the product gas that flows to the dehydration tower And a heat exchanger that heats the purified gas that has passed through the desulfurization tower with the regenerated exhaust gas that has passed through the desulfurization tower, and the product gas is circulated through at least one of the plurality of dehydration towers. The regeneration gas is circulated through at least one other column to regenerate the adsorbent, and at least one of the plurality of desulfurization columns is circulated through the product gas from which water has been removed in the dehydration column. sometimes The regenerative desulfurization is characterized in that the adsorbent is regenerated by circulating a regeneration gas that has absorbed moisture in the dehydration tower in at least one of the towers so that the purified gas is heated by the regeneration exhaust gas. apparatus.   The regenerative desulfurization apparatus according to any one of claims 1 to 3, wherein the dehydration tower is filled with zeolite.   The regenerative desulfurization apparatus according to any one of claims 1 to 3, wherein the desulfurization tower is filled with zeolite.   The regenerative desulfurization apparatus according to any one of claims 1 to 3, wherein the dehydration tower is filled with hydrophilic zeolite, and the desulfurization tower is filled with hydrophobic zeolite.   In the regenerative desulfurization apparatus according to any one of claims 1 to 3, switching between the flow of product gas and the flow of regeneration gas to the plurality of dehydration towers and the plurality of desulfurization towers is performed by a valve operation. The regenerative desulfurization apparatus characterized in that the valve operation is performed by the gas composition of the purified gas purified by passing the gas generated by gasification through the desulfurization tower.   The regenerative desulfurization apparatus according to claim 7, further comprising: an analyzer that measures a gas composition of the purified gas; and a valve controller that performs the valve operation using the gas composition of the purified gas. Regenerative desulfurization system.   The regenerative desulfurization apparatus according to claim 8, wherein when the sulfur compound concentration in the refined gas becomes a specified value or more, the adsorption and regeneration of the dehydration tower and the desulfurization tower are switched. Regenerative desulfurization equipment.   In a regenerative desulfurization system that adsorbs and removes sulfur compounds contained in a product gas obtained by a gasification system using hydrocarbons as a raw material with an adsorbent, a plurality of dehydrations that adsorb and remove moisture contained in the product gas with an adsorbent A tower, a plurality of desulfurization towers for adsorbing and removing sulfur compounds by removing a product gas from which moisture has been removed in the dehydration tower, and a regeneration gas that is circulated to the dehydration tower with the product gas flowing to the dehydration tower And a heat exchanger that heats the purified gas purified in the desulfurization tower with the regenerated exhaust gas that has passed through the desulfurization tower, and the product gas is provided in at least one of the plurality of dehydration towers When the adsorbent is regenerated by the regeneration gas in at least one other column when the gas is circulated, at least one of the plurality of desulfurization columns is subjected to moisture removal in the dehydration column. The adsorbent is regenerated by the regeneration gas that has passed through the dehydration tower in at least one other tower when in circulation, and the regeneration exhaust gas after heating the purified gas is used as a gas containing light oil and oxygen. A regenerative desulfurization furnace comprising: a regenerative exhaust gas combustion furnace combusted by a gas; an absorption tower for bringing the outlet gas of the regenerative exhaust gas combustion furnace into gas-liquid contact with a limestone slurry; and a dehydrator for recovering gypsum from the limestone slurry. system.

Images