Abstract
A desulfurization process which uses both a suspension bed and a fixed bed is disclosed herein. In particular, the desulfurization slurry is mixed with a hydrogen sulfide containing gas to obtain a first mixture, and the first mixture passed into a suspension bed reactor from bottom to top, while controlling the first mixture to have a dwell time of 5-60 minutes in the reactor. A second mixture obtained by the reaction is subjected to gas liquid separation to produce a gas phase, and the gas phase is feed into a fixed bed reactor for a second desulfurization which produces purified gas. Advantageously, sulfur content in the hydrogen sulfide containing gas may be reduced from 2.4-140 g/Nm3 to 50 ppm or less by using a suspension bed, and the sulfur content may be even further reduced to less than 10 ppm in conjunction with a fixed bed.
Claims
1. A desulfurization process using a combination of a suspension bed and a fixed bed, comprising the following steps: (1), mixing a desulfurizer with water uniformly to prepare a desulfurization slurry; (2), mixing the desulfurization slurry with a hydrogen sulfide containing gas to obtain a first mixture, and passing the first mixture into a suspension bed reactor from bottom to top, with controlling the first mixture to have a dwell time of 5-60 minutes in the suspension bed reactor to allow the desulfurization slurry to contact and react sufficiently with the hydrogen sulfide containing gas; (3), discharging a second mixture from the top of the suspension bed reactor, and subjecting the second mixture to gas liquid separation, and collecting a gas phase; and (4), feeding the gas phase into a fixed bed reactor for carrying out a second desulfurization to obtain a purified gas.
2. The desulfurization process of claim 1, wherein, in step (1), the desulfurizer has a particle size of no greater than 20 m.
3. The desulfurization process of claim 1, wherein, the desulfurizer is selected from a group consisting of amorphous iron oxide hydroxide, iron oxide, iron hydroxide or any mixture thereof.
4. The desulfurization process of claim 1, wherein, the desulfurization slurry has a desulfurizer concentration of 1-5 wt %.
5. The desulfurization process of claim 1, wherein, the desulfurization slurry has a desulfurizer concentration of 2-3 wt %.
6. The desulfurization process of claim 1, wherein, the hydrogen sulfide containing gas is selected from a group consisting of biogas, coke oven gas, oilfield associated gas, natural gas, petrochemical gas or any mixture thereof.
7. The desulfurization process of claim 1, wherein, the suspension bed reactor has an empty tower gas velocity of 0.03-0.3 m/s.
8. The desulfurization process of claim 1, wherein, there is one suspension bed reactor, or at least two suspension bed reactors connected in series and/or in parallel.
9. The desulfurization process of claim 1, wherein, in step (4), the fixed bed reactor comprises a desulfurizer selected from a group consisting of amorphous iron oxide hydroxide, iron oxide, iron hydroxide, copper oxide, zinc oxide, and any mixture thereof.
10. The desulfurization process of claim 1, wherein, the fixed bed reactor has a gas flow rate of from 1 to 20 m/s.
11. The desulfurization process of claim 2, wherein, the desulfurizer is selected from a group consisting of amorphous iron oxide hydroxide, iron oxide, iron hydroxide or any mixture thereof.
12. The desulfurization process of claim 2, wherein, the desulfurization slurry has a desulfurizer concentration of 1-5 wt %.
13. The desulfurization process of claim 2, wherein, the desulfurization slurry has a desulfurizer concentration of 2-3 wt %.
14. The desulfurization process of claim 2, wherein, the hydrogen sulfide containing gas is selected from a group consisting of biogas, coke oven gas, oilfield associated gas, natural gas, petrochemical gas or any mixture thereof.
15. The desulfurization process of claim 2, wherein, the suspension bed reactor has an empty tower gas velocity of 0.03-0.3 m/s.
16. The desulfurization process of claim 2, wherein, there is one suspension bed reactor, or at least two suspension bed reactors connected in series and/or in parallel.
17. The desulfurization process of claim 2, wherein, in step (4), the fixed bed reactor comprises a desulfurizer selected from a group consisting of amorphous iron oxide hydroxide, iron oxide, iron hydroxide, copper oxide, zinc oxide, and any mixture thereof.
18. The desulfurization process of claim 2, wherein, the fixed bed reactor has a gas flow rate of from 1 to 20 m/s.
19. The desulfurization process of claim 1, wherein, the suspension bed reactor has an empty tower gas velocity of 0.05-0.2 m/s.
20. The desulfurization process of claim 2, wherein, the suspension bed reactor has an empty tower gas velocity of 0.05-0.2 m/s.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The above and other features of the present invention or the technical solutions in the prior art will now be described in detail with reference to certain example embodiments thereof illustrated in the accompanying drawings. It should be understood that the embodiments and drawings are given hereinbelow by way of illustration only, and thus are not limitative of the present invention, and apparent modifications can be made by those skilled in the art without paying any creative work, and wherein:
(2) FIG. 1 is a flow chart of Embodiment 3 showing a desulfurization process using a combination of a suspension bed and a fixed bed, and wherein:
(3) The reference numerals are as follows:
(4) 1-coalescer; 2-suspension bed reactor; 3-gas liquid separation tank; 4-flash evaporation tank; 5-oxidation regeneration tank; 6-fixed bed reactor; 7-blower; 8-aerator; 9-aeration pump; 10-venturi mixer; 11-barren solution pump; 12-saturated slurry pump; 13-first sprinkler means; 14-second sprinkler means; 15-third sprinkler means; 16-fourth sprinkler means.
DETAILED DESCRIPTION OF EMBODIMENTS
(5) The technical solution of the present invention will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are exemplary embodiments of the invention, rather than all embodiments. Based on embodiments in the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of the present invention.
(6) In the description of the present invention, unless otherwise expressly stated and defined, the terms connected and connected should be broadly understood, for example, it may be a fixed connection, a detachable connection or an integral connection; it may be either directly connected or indirectly connected through an intermediate medium, or may be an internal communication between the two elements. It will be apparent to those skilled in the art that the specific meaning of the above terms in the present invention may be understood depending on the actual situation. In addition, the technical features described in different embodiments of the present invention described below may be recombined with each other as long as they do not form a conflict with each other.
(7) In the following embodiments, the desulfurization efficiency of the suspension bed=(total mass of hydrogen sulfide in a feed gasmass of hydrogen sulfide in the gas after the desulfurization with the suspension bed)/the total mass of the hydrogen sulfide in the feed gas; regeneration efficiency=mass of sulfur/(mass of the catalyst+mass of sulfur).
(8) Embodiment 1
(9) The desulfurization process using a combination of a suspension bed and a fixed bed provided by the present embodiment comprises the following steps: (1) mixing magnetism ferric oxide having a particle size of 1-20 m with water uniformly to prepare a desulfurization slurry having a concentration of 1 wt % ; (2) mixing a biogas having H.sub.2S content of 71.2 g/Nm.sup.3 with the desulfurization slurry to obtain a first mixture, and passing the first mixture into a first suspension bed reactor having an empty tower gas velocity of 0.3 m/s from bottom to top, and controlling the first mixture to have a dwell time of 5-7 minutes in the first suspension bed, then discharging a second mixture from the top of the first suspension bed reactor, and passing the second mixture into a second suspension bed reactor having an empty tower gas velocity of 0.3 m/s from the bottom thereof, and controlling the second mixture to have a dwell time of 5 minutes in the second suspension bed reactor, such that the biogas contacts and reacts sufficiently with the desulfurization slurry in the two suspension bed reactors connected in series; (3) discharging a gas-solid-liquid three-phase mixture from the top of the second suspension bed reactor, and subjecting the mixture to gas liquid separation to produce a gas phase and a rich solution, wherein the gas phase was determined to have a H.sub.2S content of 45 ppm, and the desulfurization efficiency was 99.6%; (4) feeding the gas phase into a fixed bed reactor filled with iron hydroxide as desulfurizer for carrying out a second desulfurization, with keeping a gas flow rate of 3 m/s in the fixed bed reactor, to obtain a purified gas which was determined to have a H.sub.2S content of 8 ppm.
Embodiment 2
(10) The desulfurization process using a combination of a suspension bed and a fixed bed provided by the present embodiment comprises the following steps: (1) mixing ferric hydroxide having a particle size of 5-15 m with water uniformly to prepare a desulfurization slurry having a concentration of 2 wt %; (2) mixing coke oven gas having a H.sub.2S content of 2.4 g/Nm.sup.3 with the desulfurization slurry to obtain a first mixture, and passing the first mixture into a suspension bed reactor having an empty tower gas velocity of 0.15 m/s from bottom to top, and controlling the first mixture to have a dwell time of 6-8 minutes in the suspension bed reactor to allow the coke oven gas contacts and reacts sufficiently with the desulfurization slurry; (3) discharging a gas-solid-liquid three-phase mixture from the top of the suspension bed reactor and subjecting the mixture to gas liquid separation to produce a rich solution and a gas phase, wherein the gas phase was determined to have a H.sub.2S content of 50 ppm, and the desulfurization efficiency was 98%; (4) feeding the gas phase into a fixed bed reactor filled with magnetic iron oxide as desulfurizer for carrying out a second desulfurization, with keeping a gas flow rate of 6 m/s in the fixed bed reactor, to obtain a purified gas which was determined to have a H.sub.2S content of 3 ppm.
Embodiment 3
(11) As shown in FIG. 1, the desulfurization process using a combination of a suspension bed and a fixed bed provided by the present embodiment comprises the following steps: (1) mixing amorphous iron oxide hydroxide having a particle size of 5-20 m with water uniformly to prepare a desulfurization slurry having a concentration of 2.5 wt %; (2) feeding a natural gas having a H.sub.2S content of 140 g/Nm.sup.3 into a coalescer tank to remove heavy components above C5, and mixing the natural gas discharged from the coalescer tank with the desulfurization slurry to obtain a first mixture, and passing the first mixture into a suspension bed reactor having an empty tower gas velocity of 0.2 m/s from bottom to top, and controlling the first mixture to have a dwell time of 30-35 minutes in the suspension bed reactor such that the natural gas contacts and reacts sufficiently with the desulfurization slurry; (3) discharging a gas-solid-liquid three-phase mixture from the top of the suspension bed reactor, and subjecting the mixture to gas liquid separation to produce a rich solution and a purified gas, wherein the purified gas was determined to have a H.sub.2S content of 41 ppm; (4) feeding the purified gas into a fixed bed reactor filled with amorphous iron oxide hydroxide as desulfurizer for carrying out a second desulfurization, with keeping a gas flow rate of 1.8 m/s in the fixed bed reactor, to obtain a second purified gas which was determined to have a H.sub.2S content of 3 ppm; (5) feeding the rich solution into a flash evaporation tank having a pressure drop of 0.17 MPa for undergoing flash evaporation to remove light hydrocarbon, and then feeding the rich solution into a regeneration tank for undergoing reaction with air for 55 minutes, wherein the introduction amount of air during the reaction is 11 times of a theoretical consumption amount thereof, to produce a barren solution, wherein the regeneration efficiency is 78%; and the barren solution is then recycled to the Step (2) for being used as the desulfurization slurry; replacing half of the rich solution in the regeneration tank with fresh desulfurization slurry when the rich solution reaches a sulfur capacity of 300%, considered as saturated, and subjecting the replaced rich solution to solid-liquid separation to produce solid sulfur and a liquid phase, wherein the solid sulfur is delivered out and the liquid phase is returned to the oxidation regeneration tank for being used as a recycling supplementary moisture.
Embodiment 4
(12) As shown in FIG. 1, the desulfurization process using a combination of a suspension bed and a fixed bed provided by the present embodiment comprises the following steps: (1) mixing amorphous iron oxide hydroxide having a particle size of 1-20 m with water uniformly to prepare a desulfurization slurry having a concentration of 3 wt %; (2) feeding an oilfield associated gas having a H.sub.2S content of 108 g/Nm.sup.3 into a coalescer tank to remove heavy components above C5, and mixing the oilfield associated gas discharged from the coalescer tank with the desulfurization slurry to obtain a first mixture, and passing the first mixture into a suspension bed reactor having an empty tower gas velocity of 0.05 m/s from bottom to top, and controlling the first mixture to have a dwell time of 20 minutes in the suspension bed reactor such that the oilfield associated gas contacts and reacts sufficiently with the desulfurization slurry; (3) discharging a gas-solid-liquid three-phase mixture from the top of the suspension bed reactor, and subjecting the mixture to gas liquid separation to produce a rich solution and a purified gas, wherein the purified gas was determined to have a H.sub.2S content of 43 ppm; (4) feeding the purified gas into a fixed bed reactor filled with amorphous iron oxide hydroxide as desulfurizer for carrying out a second desulfurization, with keeping a gas flow rate of 4 m/s in the fixed bed reactor, to obtain a second purified gas which was determined to have a H.sub.2S content of 5 ppm; (5) feeding the rich solution into a flash evaporation tank having a pressure drop of 0.23 MPa for undergoing flash evaporation to remove light hydrocarbon, and then feeding the rich solution into a regeneration tank for undergoing reaction with air for 50 minutes, wherein the introduction amount of air during the reaction is 15 times of a theoretical consumption amount thereof, to realize regeneration to produce a barren solution, wherein the regeneration efficiency is 66%; and the barren solution obtained by regeneration is then recycled to the Step (2) for being used as the desulfurization slurry; replacing all of the rich solution in the regeneration tank with fresh desulfurization slurry when the rich solution reaches a sulfur capacity of 300%, considered as saturated, and subjecting the replaced rich solution to solid-liquid separation to produce solid sulfur and a liquid phase, wherein the solid sulfur is delivered out and the liquid phase is returned to the oxidation regeneration tank for being used as a recycling supplementary moisture.
Embodiment 5
(13) As shown in FIG. 1, the desulfurization process using a combination of a suspension bed and a fixed bed provided by the present embodiment comprises the following steps: (1) mixing amorphous iron oxide hydroxide having a particle size of 10-15 m with water uniformly to prepare a desulfurization slurry with a concentration of 5 wt %; (2) feeding a petrochemical gas having a H.sub.2S content of 35 g/Nm.sup.3 into a coalescer tank to remove heavy components above C5, and mixing the petrochemical gas discharged from the coalescer tank with the desulfurization slurry to obtain a first mixture, and passing the first mixture into a suspension bed reactor having an empty tower gas velocity of 0.3 m/s from bottom to top, and controlling the first mixture to have a dwell time of 40 minutes in the suspension bed reactor such that the petrochemical gas contacts and reacts sufficiently with the desulfurization slurry; (3) discharging a gas-solid-liquid three-phase mixture from the top of the suspension bed reactor, and subjecting the mixture to gas liquid separation to produce a rich solution and a purified gas, wherein the purified gas was determined to have a H.sub.2S content of 46 ppm; (4) feeding the purified gas into a fixed bed reactor filled with zinc oxide as desulfurizer for carrying out a second desulfurization, with keeping a gas flow rate of 5 m/s in the fixed bed reactor, to obtain a second purified gas which was, determined to have a H.sub.2S content of 4 ppm; (5) feeding the rich solution into a flash evaporation tank having a pressure drop of 0.3 MPa for undergoing flash evaporation to remove light hydrocarbon, and then feeding the rich solution into a regeneration tank for undergoing reaction with air for 60 minutes, wherein the introduction amount of air during the reaction is 13 times of a theoretical consumption amount thereof, to produce a barren solution, wherein the regeneration efficiency is 81%; and the barren solution is then recycled to the Step (2) for being used as the desulfurization slurry; replacing all of the rich solution in the regeneration tank with fresh desulfurization slurry when the rich solution reaches a sulfur capacity of 300%, considered as saturated, and subjecting the replaced rich solution to solid-liquid separation to produce solid sulfur and a liquid phase, wherein the solid sulfur is delivered out and the liquid phase is returned to the oxidation regeneration tank for being used as a recycling supplementary moisture.
Embodiment 6
(14) As shown in FIG. 1, the desulfurization process using a combination of a suspension bed and a fixed bed provided by the present embodiment comprises the following steps: (1) mixing amorphous iron oxide hydroxide having a particle size of 10-15 m with water uniformly to prepare a desulfurization slurry having a concentration of 1.5 wt %; (2) feeding a petrochemical gas having a H.sub.25 content of 123 g/Nm.sup.3 into a coalescer tank to remove heavy components above C5, and mixing the petrochemical gas discharged from the coalescer tank with the desulfurization slurry to obtain a first mixture, and passing the first mixture into a suspension bed reactor having an empty tower gas velocity of 0.1 m/s from bottom to top, and controlling the first mixture to have a dwell time of 10-15 minutes in the suspension bed reactor such that the petrochemical gas contacts and reacts sufficiently with the desulfurization slurry; (3) discharging a gas-solid-liquid three-phase mixture from the top of the suspension bed reactor, and subjecting the mixture to gas liquid separation to produce a rich solution and a purified gas, wherein the purified gas was determined to have a H.sub.2S content of 48 ppm; (4) feeding the purified gas into a fixed bed reactor filled with copper oxide as desulfurizer for carrying out a second desulfurization, with keeping a gas flow rate of 10 m/s in the fixed bed reactor, to obtain a second purified gas which was determined to have a H.sub.2S content of 8 ppm; (5) feeding the rich solution into a flash evaporation tank having a pressure drop of 0.1 MPa for undergoing flash evaporation to remove light hydrocarbon, and then feeding the rich solution into a regeneration tank for undergoing reaction with air for 35 minutes, wherein the introduction amount of air during the reaction process is 8 times of a theoretical consumption amount thereof, to produce a barren solution, wherein the regeneration efficiency is 65%; and the barren solution is then recycled to the Step (2) for being used as the desulfurization slurry; replacing all of the rich solution in the regeneration tank with fresh desulfurization slurry when the rich solution reaches a sulfur capacity of 300%, considered as saturated, and subjecting the replaced rich solution to solid-liquid separation to produce solid sulfur and a liquid phase, wherein the solid sulfur is delivered out and the liquid phase is returned to the oxidation regeneration tank for being used as a recycling supplementary moisture.
Embodiment 7
(15) As shown in FIG. 1, the desulfurization process using a combination of a suspension bed and a fixed bed provided by the present embodiment comprises the following steps: (1) mixing amorphous iron oxide hydroxide having a particle size of 1-10 m with water uniformly to prepare a desulfurization slurry having a concentration of 2.5 wt %; (2) feeding a petrochemical gas having a H.sub.2S content of 89 g/Nm.sup.3 into a coalescer tank to remove heavy components above C5, and mixing the petrochemical gas discharged from the coalescer tank with the desulfurization slurry to obtain a first mixture, and passing the first mixture into a suspension bed reactor having an empty tower gas velocity of 0.03 m/s from bottom to top, and controlling the first mixture to have a dwell time of 50-60 minutes in the suspension bed reactor such that the petrochemical gas contacts and reacts sufficiently with the desulfurization slurry; (3) discharging a gas-solid-liquid three-phase mixture from the top of the suspension bed reactor, and subjecting the mixture to gas liquid separation to produce a rich solution and a purified gas, wherein the purified gas was determined to have a H.sub.2S content of 45 ppm; (4) feeding the purified gas into a fixed bed reactor filled with amorphous iron oxide hydroxide as desulfurizer for carrying out a second desulfurization, with keeping a gas flow rate of 20 m/s in the fixed bed reactor, to obtain a second purified gas which was determined to have a H.sub.2S content of 7.5 ppm; (5) feeding the rich solution into a flash evaporation tank having a pressure drop of 0.4 MPa for undergoing flash evaporation to remove light hydrocarbon, and then feeding the rich solution into a regeneration tank for undergoing reaction with air for 30-40 minutes, wherein the introduction amount of air during the reaction is 5 times of a theoretical consumption amount thereof, to produce a barren solution, wherein the regeneration efficiency is 80%; and the barren solution is then recycled to the Step (2) for being used as the desulfurization slurry; replacing all of the rich solution in the regeneration tank with fresh desulfurization slurry when the rich solution reaches a sulfur capacity of 300%, considered as saturated, and subjecting the replaced rich solution to solid-liquid separation to produce solid sulfur and a liquid phase, wherein the solid sulfur is delivered out and the liquid phase is returned to the oxidation regeneration tank for being used as a recycling supplementary moisture.
Embodiment 8
(16) The process provided by the above embodiments 1-7 of the present invention is carried out using the following integrated system, as shown in FIG. 1. The integrated system comprises: a suspension bed reactor 2, provided with a feed inlet at bottom thereof and a discharge outlet at top thereof, and having a first sprinkler means 13 provided therein and disposed adjacent to the discharge outlet of the suspension bed reactor 2, and the suspension bed reactor 2 being filled with a mixture of a desulfurization slurry and a hydrogen sulfide containing gas, wherein the mixture has a dwell time of 5-60 min in the suspension bed reactor; and wherein alternatively, the desulfurization apparatus of the present embodiment is not limited to comprise one suspension bed reactor, and it may comprise two or more suspension bed reactors connected in series or in parallel; a gas liquid separation tank 3, in connection with the discharge outlet of the suspension bed reactor 2, and provided with a rich solution outlet at bottom thereof and an exhaust port at top thereof; wherein the gas liquid separation tank 3 has a second sprinkler means 14 for spraying the desulfurization slurry, and the second sprinkler means 14 is provided inside the gas liquid separation tank 3 and disposed adjacent to the exhaust port of the gas liquid separation tank 3; and wherein the gas liquid separation tank 3 is provided with a low pressure condensate water return line and a low pressure steam return line on the outer side wall thereof; wherein alternatively, the desulfurization apparatus in this embodiment may comprise a plurality of gas liquid separation tanks according to the gas volume, the circulation amount of the slurry and the capacity of the equipment, etc., in order to prevent liquid from entering the fixed bed dry desulfurization unit and affecting the performance of the desulfurizer; a fixed-bed reactor 6, connected to the exhaust port of the gas liquid separation tank 3, and provided with a purified gas outlet at the top thereof; wherein preferably, the present embodiment comprises two fixed bed reactors connected in series, to ensure smooth operation in case one of them encounters fluctuation and failure, or alternatively, comprises at least two fixed bed reactors connected in parallel; a flash evaporation tank 4, in connection with the rich solution outlet of the gas liquid separation tank 3, and provided with a saturated liquid outlet at bottom thereof; wherein the flash evaporation tank 4 has a third sprinkler means 15 provided therein and disposed adjacent to a light hydrocarbon discharge outlet at the top of the flash evaporation tank 4; an oxidation regeneration tank 5, in connection with the saturated liquid outlet of the flash evaporation tank 4, and provided with a barren solution outlet arranged at bottom thereof and in connection with the feed inlet of the suspension bed reactor 2; wherein the oxidation regeneration tank 5 has a fourth sprinkler means 16 provided at an upper portion thereof; and wherein the oxidation regeneration tank 5 is provided with an aerator 8 therein and a blower 7 and a aeration pump 9 in exterior thereof, wherein the blower and the aeration pump are respectively connected with the aerator 8, and the aeration pump 9 is connected with a liquid outlet in a lower portion of the oxidation regeneration tank 5; a venturi mixer 10, having an outlet connected to a slurry inlet in an upper portion of the oxidative regeneration tank 5, and further having a desulfurizer inlet and a water inlet; and a solid liquid separator (not shown in the drawings), in connection with a saturated liquid outlet arranged in a lower portion of the oxidation regeneration tank 5, and provided with an water outlet which is respectively connected with an water inlet of each of the first sprinkler, the third sprinkler, the fourth sprinkler and the venturi mixer 10. As an alternative embodiment, the present embodiment further comprises a coalescer 1 having an exhaust port communicating with the feed inlet of the suspension bed reactor 2. When the integrated system according to the present invention is shut down, water is sprayed into the suspension bed reactor 2 by the first sprinkler means 13 in order to achieve the purpose of cleaning. In addition, the desulfurization slurry is sprayed into the gas liquid separation tank by the second sprinkler means 14, water is sprayed into the flash evaporation tank 4 by the third sprinkler means 15, and water is sprayed into the oxidation regeneration tank 5 by the fourth sprinkler means 16, all of which serve the purpose of preventing sulfur from accumulating in the liquid surface, so all of them play a role of scouring.
(17) It is obvious that the above embodiments are given by way of illustration only, and thus are not limitative of the present invention. Those skilled in the art should understand, any equivalent alternatives derived on the basis of the present invention should be embraced within the protection scope of the present invention.
