Method for processing acid gas and apparatus thereof
09770689 · 2017-09-26
Assignee
- China Petroleum & Chemical Corporation (Beijing, CN)
- FUSHUN RESEARCH INSTITUTE OF PETROLEUM AND PETROCHEMICALS, SINOPEC CORP. (Fushun, Liaoning, CN)
Inventors
- Deqiang Peng (Liaoning, CN)
- Zejun Zuo (Liaoning, CN)
- Huimin Qi (Liaoning, CN)
- Luyao Wang (Liaoning, CN)
- Fanfei Meng (Liaoning, CN)
- Jianbing Chen (Liaoning, CN)
- Xin Chen (Liaoning, CN)
Cpc classification
B01D53/526
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
The present disclosure provides a method for processing an acid gas, comprising: using a processor 1 for receiving and processing the acid gas to obtain a gas phase stream 1 and a liquid phase stream 2, wherein the stream 2 is partially or completely recycled to the processor 1; using a processor 2 for processing the stream 1 from the processor 1 to obtain a gas phase stream 3 and a liquid phase stream 4; using a processor 3 for processing the stream 3 from the processor 2 to obtain a gas phase stream 5 and a liquid phase stream 6; and using a processor 4 for receiving the stream 43 from the processor 2 and using the stream 43 as a processing solution for processing the stream 5 from the processor 3 to obtain a gas phase stream 7 and a liquid phase stream 8, which can be divided into two sub-streams including a stream 81 and a stream 82. The present disclosure further provides an apparatus for processing an acid gas.
Claims
1. A system for processing an acid gas, comprising: a first processor comprising a first gas inlet and a final liquid outlet; a second processor comprising a first liquid inlet; a third processor comprising a second liquid inlet; a fourth processor comprising a final gas outlet; a gas stream that enters the system through the first gas inlet in the first processor, passing through all of the four processors, and exits the system through the final gas outlet in the fourth processor; an alkaline solution that enters the system through the first liquid inlet in the second processor and the second liquid inlet in the third processor simultaneously, passing through all of the four processors, and exits the system through the final liquid outlet in the first processor, and wherein the gas stream entering the system comprises H.sub.2S and CO.sub.2, and the alkaline solution exiting the system comprises Na.sub.2S and NaHS wherein at least one of the first processor, the second processor, the third processor, and the fourth processor is a Venturi reactor comprising: an upper liquid storage tank that stores a first liquid, comprising a gas inlet and a liquid inlet; a Venturi tube comprising a straight reaction tube, a throat pipe section, a discharge section, a contraction section disposed between the straight reaction tube and the throat pipe section, and an expansion section disposed between the throat pipe section and the discharge section; and a lower gas-liquid separation tube comprising a second gas outlet and a second liquid outlet, wherein the straight reaction tube comprises a third liquid inlet upstream from the contraction section and a feed section extending into the upper liquid storage tank so that the upper liquid storage tank discharges the first liquid into the straight reaction tube by causing the aqueous solution to overflow the feed section, and wherein the discharge section extends into the lower gas-liquid separation tube.
2. The system of claim 1, wherein the third liquid inlet in the Venturi reactor is disposed adjacent to a location where the upper liquid storage tank and the straight reaction tube connects.
3. The system of claim 1, wherein the feed section of the Venturi reactor has an upper edge that is sector tooth-shaped, square tooth-shaped, or triangular tooth-shaped.
4. The system of claim 1, wherein the Venturi reactor further comprises a liquid distributor disposed in a center of the straight reaction tube and arranged to inject liquid downwardly.
5. The system of claim 1, wherein the first processor, the second processor, the third processor, and the fourth processor are each independently selected from a group consisting of a bubble column reactor, a packed column reactor, an impinging stream reactor, a rotating bed reactor, and the Venturi reactor, with the proviso that at least one of the first processor, the second processor, the third processor, and the fourth processor is the Venturi reactor.
6. The system of claim 5, wherein the first processor and the second processor are respectively Venturi reactors, and the third processor and the fourth processor are respectively rotating bed reactors.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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(6) In the drawings, the same reference numbers are used for the same devices respectively.
DETAILED DESCRIPTION OF THE EMBODIMENTS
(7) The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, group of elements, components, and/or groups thereof.
(8) Language such as “including”, “comprising”, “having”, “containing”, or “involving”, and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, as well as equivalents, and additional subject matter not recited. Further, whenever a composition, a group of elements, process or method steps, or any other expression is preceded by the transitional phrase “comprising”, “including”, or “containing”, it is understood that it is also contemplated herein the same composition, group of elements, process or method steps or any other expression with transitional phrases “consisting essentially of”, “consisting of”, or “selected from the group of consisting of”, preceding the recitation of the composition, the group of elements, process or method steps or any other expression.
(9) The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims, if applicable, are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiments described herein were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. Accordingly, while the invention has been described in terms of embodiments, those of skill in the art will recognize that the invention can be practiced with modifications and in the spirit and scope of the appended claims.
(10) The following examples are used to explain the present disclosure in more details, but not to restrict the scope of the present disclosure.
(11) The method of the present disclosure is used for processing an acid gas generated in refineries, with a NaOH solution as an absorption solution, to produce NaHS products, wherein a four-stage gas-liquid two-phase countercurrent absorption reaction process is used.
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(13) The method for processing an acid gas of the present disclosure comprises first feeding the acid gas (comprising H.sub.2S and CO.sub.2) from an acid gas phase inlet line 1 into a first processor 3, wherein the acid gas contacts and reacts with a generation liquid from a second processor 4, to generate a liquid that is divided into two branches, with a first branch 22 being connected to a liquid phase inlet of the first processor 3, and a second branch 12 being connected to a product discharge line. The acid gas after being treated in the first processor 3 enters the second processor 4 and contacts and reacts with a generation liquid from a third processor 6 and a NaOH solution therein, to generate a liquid that is divided into three branches, with a first branch second generation liquid 21, as an absorption fluid, entering the first processor 3 via a liquid phase inlet thereof, a second branch second generation liquid 20 entering the second processor 4, and a third branch second generation liquid 15, as an absorption fluid, entering a fourth processor 8. The acid gas after being treated in the second processor 4 enters the third processor 6, and reacts with the generation liquid from the fourth processor 8 and a NaOH solution therein, to generate a liquid which enters a third intermediate tank 7 and is then divided into two branches, with a first branch 19 entering the second processor 4 as an absorption fluid via a line, and a second branch 18 being recycled into the third processor 6 via the line. The acid gas after being treated in the third processor 6 enters the fourth processor 8, and reacts with the third branch second generation liquid 15 from the second processor 4. The acid gas after being reacted is further demist via a coalescer 2 and then discharged via a purified gas outlet line 11 with the emission standard being satisfied. A generation liquid then enters a fourth intermediate tank 9 and is divided into two branches, with a first branch 17, as an absorption fluid, entering the third processor 6, and a second branch 16 being recycled to the fourth processor 8 via the line.
(14)
(15) The Venturi reactor comprises three parts: an upper liquid storage tank 34 for receiving and storing liquid streams; a middle straight reaction tube 30 comprising a feed section 33, a contraction section 37, a throat pipe section 38, an expansion section 39, and a discharge section 40, the feed section 33 of the straight reaction tube 30 having an upper portion extending into the liquid storage tank 34 to form a sleeve structure; and a lower gas-liquid separation tube 41 which is connected to the straight reaction tube 30 via a lower portion of the discharge section 40 of the straight reaction tube 30. The liquid storage tank 34 is provided with a gas phase inlet 31, which is located above an upper inlet of the feed section 33. And the liquid storage tank 34 is provided with a circulating fluid inlet 32 on a sidewall thereof. The straight reaction tube 30 is provided with an absorption fluid inlet 35 on a tube wall thereof, wherein the absorption fluid inlet 35 is provided above the throat pipe section 38 and connected to a liquid phase distributor 36. The gas-liquid separation tube 41 is provided with a gas phase outlet 42 and a liquid phase outlet 43.
(16) The third processor 6 and the fourth processor 8 are respectively arranged with a gas phase inlet, a gas phase outlet, an absorption fluid inlet, and a liquid phase outlet. An acid gas inlet line 1 is connected to the gas phase inlet of the first processor 3. The gas phase outlet of the first processor 3 is connected to the gas phase inlet of the second processor 4. The gas phase outlet of the second processor 4 is connected to the gas phase inlet of the third processor 6. The gas phase outlet of the third processor 6 is connected to the gas phase inlet of the fourth processor 8. The gas phase outlet of the fourth processor 8 is connected to a purified gas outlet line 11, which is provided with a hydrogen sulfide content detection device 5. Liquid phase inlets of the second processor 4 and the third processor 6 are respectively connected to an alkali solution inlet line 10 via lines 13 and 14. The liquid phase outlet of the fourth processor 8 is divided into two branches via the fourth intermediate tank 9, with a first branch 17 being connected to the absorption fluid inlet of the third processor 6, and a second branch 16 being connected to the absorption fluid inlet of the fourth processor 8. The liquid phase outlet of the third processor 6 is divided into two branches via the third intermediate tank 7, with a first branch 18 being connected to the absorption fluid inlet of the third processor 6, and a second branch 19 being connected to the liquid phase inlet of the second processor 4. The liquid phase outlet of the second processor 4 is divided into four branches, with a first branch 20 being connected to the absorption fluid inlet of the second processor 4, a second branch 21 being connected to the absorption fluid inlet of the first processor 3, a fourth branch 24 being connected to a circulating fluid inlet of the second processor 4, and a third branch 15 being connected to the absorption fluid inlet of the fourth processor 8. The liquid phase outlet of the first processor 3 is divided into three branches, with a first branch 22 being connected to the absorption fluid inlet of the first processor 3, a second branch 12 being connected to a product discharge line, and a third branch 23 being connected to a circulating fluid inlet of the first processor 3.
(17) The method for processing an acid gas of the present disclosure comprises first feeding the acid gas from an acid gas inlet line 1 into a first processor 3, wherein the acid gas contacts and reacts with a generation liquid from a second processor 4, to generate a liquid that is divided into three branches, with a first branch 22 being connected to a liquid phase inlet of the first processor 3, a second branch being connected to a product discharge line, and a third branch 23 entering a liquid storage tank 34 via a circulating fluid inlet 32 of the Venturi reactor of the first processor. When the elevation of the circulating fluid in the liquid storage tank is above an inlet of a feed section 33, the circulating generation liquid overflows and is distributed over the entire wall of a straight reaction tube 30 of the processor in the form of a wall flow. Thus, a homogeneous liquid film is formed on the inner wall of the straight reaction tube 30 of the processor and acts as a separator, which does not only prevent precipitation of any crystal to be adhered to the inner wall of the straight reaction tube 30 of the processor, but also forms a heat adsorption medium to absorb the heat of reaction, thus effectively preventing excessive evaporation of the generation liquid to form crystals. The acid gas after being treated in the first processor 3 enters a second processor 4 and contacts and reacts with a generation liquid from a third processor 6 and a NaOH solution, to generate a liquid that is divided into four branches, with a first branch generation liquid 21, as an absorption fluid, entering the first processor 3 via a liquid phase inlet thereof, a second branch generation liquid 20 entering the second processor 4, a fourth branch generation liquid 24 entering the second processor 4 via a circulating fluid inlet thereof, and a third branch 15 being connected to an absorption fluid inlet of a fourth processor 8. As is the case in the first processor 3, the circulating fluid overflows in the second processor 4 and is distributed over the entire wall of the straight reaction tube of the second processor 4 in the form of a wall flow. Thus, a homogeneous liquid film is formed on the inner wall of the processor and acts as a separator, which does not only prevent precipitation of any crystal to be adhered to the inner wall of the processor, but also forms a heat adsorption medium to absorb the heat of reaction, thus effectively preventing excessive evaporation of the stream to form crystals. The acid gas after being treated in the second processor 4 enters the third processor 6, and reacts with the generation liquid from the fourth processor 8 and a NaOH solution therein, to generate a liquid which enters a third intermediate tank 7 and then divided into two branches, with a first branch 19 entering the second processor 4 as an absorption fluid via a line, and a second branch 18 being recycled into the third processor 6 via the line. The acid gas after being treated in the third processor 6 enters the fourth processor 8, and reacts with the third branch 15 of the second generation liquid. The acid gas after being reacted is further demist via a coalescer 2 and is discharged via a purified gas outlet line 11 with the emission standard being satisfied. A generation liquid thereof enters a fourth intermediate tank 9 and is divided into two branches, with a first branch 17, as an absorption fluid, entering the third processor 6, and a second branch 16 being recycled to the fourth processor 8 via the line.
(18) The method for processing an acid gas of the present disclosure comprises the following four steps.
(19) (1) Reaction in the First Processor 3
(20) Major reaction in the first processor 3 is as follows. An acid gas that has not been treated is reacted with a second generation liquid (a mixture containing Na.sub.2S, Na.sub.2CO.sub.3, and NaHCO.sub.3). The Na.sub.2CO.sub.3, NaHCO.sub.3, and Na.sub.2S in the second generation liquid are reacted with excessive amounts of H.sub.2S, respectively, to generate a NaHS solution in the first processor, which is divided into two branches, with a first branch being fed into a finished product tank, and a second branch being fed into the first processor 3.
(21) (2) Reaction in the Second Processor 4
(22) Major reaction in the second processor 4 is as follows. The exhaust gas of the first reaction (gas phase of the second reaction) having a reduced concentration of H.sub.2S yet still dissatisfying the emission standard is reacted with a generation liquid of the third processor 6 and a NaOH solution (liquid phase treatment agent of the second-stage reaction). Thereby, the gas phase is purified and a Na.sub.2S solution of a certain concentration is formed. The Na.sub.2S solution is partially conveyed to the first processor 3 for further reaction as an absorption fluid, partially recycled to the second processor 4, and partially entering the fourth processor 8 as an absorption fluid.
(23) (3) Reaction in the Third Processor 6
(24) Major reaction in the third processor 6 is as follows. The exhaust gas of the second reaction (gas phase of the third reaction) having a significantly reduced concentration of H.sub.2S yet still dissatisfying the emission standard is reacted with a generation liquid from the fourth reaction and a NaOH solution (treatment agent of the third reaction). The mixture solution of NaOH and Na.sub.2S is reacted with a slightly excessive amount of H.sub.2S to generate Na.sub.2S and NaHS. The generation liquid obtained in the third processor is divided into two branches, with a first branch entering the second processor 4 as an absorption fluid and a second branch entering the third processor 6 for circulation, so as to achieve deep adsorption and heat circulation of the absorption fluid.
(25) (4) Reaction in the Fourth Processor 8
(26) Major reaction in the fourth processor 8 is as follows. The exhaust gas of the third reaction (gas phase of the fourth reaction) having an extremely low concentration of H.sub.2S that has substantially reached the emission standard is reacted with a generation liquid of the second reaction that is rich in Na.sub.2CO.sub.3 (treatment agent of the fourth reaction). Na.sub.2CO.sub.3 is reacted with a small amount of H.sub.2S to generate a small amount of Na.sub.2S, so as to realize absorption of H.sub.2S to replace CO.sub.2. Thus, the amount of CO.sub.2 in the acid gas is reduced, so as to reduce amounts of Na.sub.2CO.sub.3 and NaHCO.sub.3 generated in the liquid phase products. Hence, crystals can be prevented from being precipitated and a long-term operation of the apparatus can be ensured. The generation liquid obtained in the fourth processor is divided into two branches, with a first branch entering the third processor as an absorption fluid, and a second branch entering the fourth processor via the intermediate tank for circulation, so as to achieve deep adsorption and heat circulation of the absorption fluid and ensure satisfaction of the emission standard of the purified gas.
(27) The effects of the present disclosure will be explained in detail in connection with specific examples.
Example 1
(28) An acid gas was reacted with a NaOH solution using the method and apparatus as shown in
(29) In this example, the first processor 3 and the second processor 4 were Venturi reactors, while the third processor 6 and fourth processor 8 were rotating bed reactors.
(30) In this example, the volume flow ratio of the second branch generation liquid 22 that came from the first processor 3 and was recycled to the first processor 3 to the total amount of the generation liquid generated in the first processor was 5:6. The volume flow ratio of the second branch generation liquid 20 that came from the second processor 4 and was recycled to the second processor to the total amount of the generation liquid generated in the second processor was 2:6. The volume flow ratio of the second generation liquid that enters the fourth processor 8 to the total amount of the generation liquid generated in the second processor 4 was 1.5:6. The volume flow ratio of the second branch generation liquid 18 that came from the third processor 6 and was recycled to the third processor 6 to the total amount of the generation liquid generated in the third processor was 5:6. The volume flow ratio of the second branch generation liquid 16 that came from the fourth processor 8 and was recycled to the fourth processor 8 to the total amount of the generation liquid generated in the fourth processor was 5:6.
(31) In this example, the volume flow ratio of the alkali added into the second processor 4 to the alkali added into the third processor 6 was 2:1.
(32) The reaction temperature in the first processor 3 and that in the second processor 4 were respectively 80° C. The reaction temperature in the third processor 6 and that in the fourth processor 8 were respectively 75° C. The rotating speed of the rotating bed in the third processor 6 and that of the rotating bed in the fourth processor 8 were respectively 1,500 rpm. The residence time of the reaction stream in the third processor 6 and that of the reaction stream in the fourth processor 8 were respectively 10 s. The reaction results are as shown in Table 1.
Example 2
(33) The method and apparatus as indicated in
(34) In this example, the volume flow ratio of the generation liquid that came from the first processor 3 and was recycled to the first processor 3 via the absorption fluid inlet thereof to the total amount of the generation liquid generated in the first processor 3 was 5:8. And the volume flow ratio of the generation liquid that came from the first processor 3 and was recycled to the first processor 3 via the circulating fluid inlet 32 thereof to the total amount of the generation liquid generated in the first processor 3 was 5:24.
(35) The volume flow ratio of the generation liquid 21 that came from the second processor 4 and was recycled to the second processor 4 via the absorption fluid inlet thereof to the total amount of the generation liquid generated in the second processor 4 was 5:8. The volume flow ratio of the generation liquid 24 that came from the second processor 4 and was recycled to the second processor 4 via the circulating fluid inlet thereof to the total amount of the generation liquid generated in the second processor 4 was 5:24. And the volume flow ratio of the second generation liquid 15 that came from the second processor 4 and entered the fourth processor 8 to the total amount of the generation liquid generated in the second processor 4 was 1:12.
(36) The volume flow ratio of the second branch generation liquid 18 that came from the third processor 6 and was recycled to the third processor 6 to the total amount of the generation liquid generated in the third processor 6 was 5:6. And the volume flow ratio of the second branch generation liquid 16 that was recycled to the fourth processor 8 to the total amount of the generation liquid generated in the fourth processor 8 was 5:6.
(37) In this example, the volume flow ratio of the alkali added into the second processor 4 to the alkali added into the third processor 6 was 2:1.
(38) The reaction temperature in the first processor 3 and that in the second processor 4 were respectively 80° C. The reaction temperature in the third processor 6 and that in the fourth processor 8 were respectively 75° C. The rotating speed of the rotating bed in the third processor 6 and that of the rotating bed in the fourth processor 8 were respectively 1,500 rpm. The residence time of the reaction stream in the third processor 6 and that of the reaction stream in the fourth processor 8 were respectively 10 s. The reaction results are as shown in Table 1.
Comparative Example 1
(39) The steps of Example 1 were repeated under the same conditions except that the NaOH solution was altogether added in the fourth processor 8 instead of being added in different stages. The results are shown in Table 1.
Comparative Example 2
(40) The steps of Example 2 were repeated under the same conditions except that the NaOH solution was altogether added in the fourth processor 8 instead of being added in different stages. The results are shown in Table 1.
Comparative Example 3
(41) The steps of Example 1 were repeated under the same conditions except that the second generation liquid was cancelled as an absorption fluid of the fourth reaction. The results are shown in Table 1.
Comparative Example 4
(42) The steps of Example 1 were repeated under the same conditions except that the NaOH solution was altogether added in the fourth processor 8 instead of being added in different stages and that the second generation liquid was cancelled as an absorption fluid of the fourth reaction. The results are shown in Table 1.
(43) TABLE-US-00001 TABLE 1 Reaction results of the examples and comparative examples Comparative Comparative Comparative Comparative Example 1 Example 2 Example 1 Example 2 Example 3 Example 4 Concentration of the 40% 41% 39% 40% 39% 37% product of NaHS Content of Na.sub.2S <3% <4% <4% <4% <4% <4% Content of H.sub.2S in the 25 30 28 28 30 32 purified gas (mg/Nm.sup.3) Operating cycle of the The The Blockage Blockage Blockage Blockage apparatus operation operation occurred occurred occurred occurred stayed stayed after after after after still still operation of operation of operation of operation of stable stable 300 h and 400 h and 280 h and 50 h and after after manual manual manual manual 600 h. 600 h. processing processing processing processing was required. was required. was required. was required.
(44) The results in Table 1 indicate that although the methods and apparatuses of the comparative examples can obtain purified gas containing more or less the same content of H.sub.2S as the method and apparatus of the present disclosure can obtain, i.e., both can achieve good processing effects of H.sub.2S, the method and apparatus of the present disclosure have much longer operating cycles.
(45) In order to further explain effects of the present disclosure,
(46) As will be appreciated by one skilled in the art, the foregoing functions and/or process may be embodied as a system, method or computer program product. For example, the functions and/or process may be implemented as computer-executable program instructions recorded in a computer-readable storage device that, when retrieved and executed by a computer processor, controls the computing system to perform the functions and/or process of embodiments described herein. In one embodiment, the computer system can include one or more central processing units, computer memories (e.g., read-only memory, random access memory), and data storage devices (e.g., a hard disk drive). The computer-executable instructions can be encoded using any suitable computer programming language (e.g., C++, JAVA, etc.). Accordingly, aspects of the present invention may take the form of an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects.
(47) It should be noted that the above examples are only used to explain, rather than to limit the present disclosure in any manner. Although the present disclosure has been discussed with reference to preferable examples, it should be understood that the terms and expressions adopted are for describing and explaining instead of limiting the present disclosure. The present disclosure can be modified within the scope of the claims, and can be amended without departing from the scope or spirits of the present disclosure. Although the present disclosure is described with specific methods, materials, and examples, the scope of the present disclosure herein disclosed should not be limited by the particularly disclosed examples as described above, but can be extended to other methods and uses having the same functions.