An apparatus for removing hydrogen sulfide and water vapor from a natural gas stream

Abstract

The application relates to the technical field of natural gas production and supply, in particular to a device for removing hydrogen sulfide and water vapor in natural gas flow, which comprises an outer shell and an inner rotor installed in the outer shell, and is sequentially divided into a first section provided with a driving turbine, a second section for throttling and a third section provided with a centrifugal impeller along the axial direction of the inner rotor; a radial gas inlet opening into the driving turbine is arranged on the outer shell; the second section is at least divided into a primary speed-up section with a radius of r4 close to the first section and a secondary speed-up section with a radius of r5 close to the third section, and r5>r4. The device removes water vapor and H2S in natural gas by using a mechanical mode, guarantees desulfurization efficiency and reduces desulfurization cost.

Description

Technical Field

[0001] This invention relates to the field of natural gas production and supply technology, and more specifically, to an apparatus for removing hydrogen sulfide and water vapor from a natural gas stream. Background Technology

[0002] During natural gas transportation, water vapor and H2S in the natural gas not only degrade its quality but also corrode the pipelines. Current technologies typically use pressure reduction and cooling to condense water vapor and remove it from the natural gas. Existing H2S removal technologies mainly focus on chemical methods, such as zinc oxide and activated carbon methods, to adsorb H2S in transported natural gas, thereby reducing its content. However, because natural gas pipelines usually have high flow rates, these chemical methods have short sulfur absorption times, and the substances that react with H2S are consumables. As the adsorbed H2S content increases, the subsequent adsorption effect decreases, requiring regular replacement of the adsorbent and increasing treatment costs. Summary of the Invention

[0003] The purpose of this invention is to provide a device for removing hydrogen sulfide and water vapor from a natural gas stream. This device uses mechanical means to remove water vapor and H2S from the natural gas, ensuring desulfurization efficiency and reducing desulfurization costs.

[0004] The embodiments of the present invention are achieved through the following technical solutions:

[0005] A device for removing hydrogen sulfide and water vapor from a natural gas stream includes: an outer casing and an inner rotor installed inside the outer casing. The inner rotor is divided into three sections along its axial direction: a first section with a drive turbine installed, a second section for throttling, and a third section with a centrifugal impeller installed. A radial air inlet leading to the drive turbine is provided on the outer casing. The second section is divided into a primary acceleration section with a radius of r4 near the first section and a secondary acceleration section with a radius of r5 near the third section, where r5 > r4.

[0006] Furthermore, let the rotor inlet radius of the driving turbine be r1, and the shaft radius of the inner rotor be r3, where 0.26 ≤ r3 / r1 ≤ 0.35; let the outlet radius of the driving turbine be r2, and satisfy... Let the minimum inlet radius of the centrifugal impeller be r6, and satisfy...

[0007] Furthermore, the maximum relative Mach number within the centrifugal impeller channel is 1.2 ≤ ma max ≤1.68.

[0008] Furthermore, the drive turbine is a radial-flow centripetal turbine.

[0009] Furthermore, a liquid outlet is provided on the outer shell.

[0010] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0011] This invention incorporates a depressurization section, where water vapor in natural gas condenses into a liquid state under low temperature and low pressure. A secondary acceleration section further reduces the temperature of the natural gas, causing the liquid water vapor to condense into crystals, while gaseous H2S condenses into a liquid under the cooling conditions. Finally, a driving turbine powers a centrifugal impeller to eject the solid water vapor and condensed H2S towards the outlet for discharge. This invention mechanically removes gaseous water vapor and H2S from natural gas. The device can operate continuously in a cycle, ensuring efficient removal of water vapor and H2S while reducing costs. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 A schematic diagram of the meridional flow surface provided by the present invention;

[0014] Figure 2 A schematic diagram of the circumferential average relative Mach number distribution of the meridional flow surface provided by the present invention;

[0015] Figure 3 A schematic diagram of the circumferential average static temperature distribution of the meridional flow surface provided by the present invention;

[0016] Figure 4 A partially enlarged view of the circumferential average static temperature distribution of the meridional flow surface of a centrifugal impeller provided by the present invention;

[0017] Figure 5 This invention provides a table showing the changes in the system performance parameters of the device under varying operating conditions.

[0018] Icons: 1-Outer shell, 11-Radial air inlet, 12-Liquid outlet, 13-Air outlet, 21-First stage, 22-Second stage, 221-First acceleration stage, 222-Second acceleration stage, 23-Third stage. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] Example 1

[0022] Reference Figure 1 As shown, the present invention provides a device for removing hydrogen sulfide and water vapor from a natural gas stream, comprising: an outer casing 1 and an inner rotor installed inside the outer casing 1, which is sequentially divided along the axial direction of the inner rotor into: a first section 21 with a drive turbine installed, a second section 22 for throttling, and a third section 23 with a centrifugal impeller installed. A radial air inlet 11 leading to the drive turbine is provided on the outer casing 1. The second section 22 is divided into a primary acceleration section 221 with a radius of r4 near the first section 21 and a secondary acceleration section 222 with a radius of r5 near the third section 23, where r5 > r4. Furthermore, a liquid outlet 12 is also provided on the outer casing 1.

[0023] In practical use, the radial air inlet 11 of this device is connected to the pipeline that transports natural gas. The high-pressure natural gas flows to the drive turbine, which is a radial centripetal turbine. The natural gas blows the impeller of the drive turbine, causing the inner rotor to rotate. Part of the pressure energy of the natural gas is converted into the output power of the drive turbine, while the natural gas is cooled and depressurized.

[0024] Low-temperature, low-pressure natural gas enters the second stage 22, which is used for throttling. The radius r4 of the first acceleration stage 221 is relatively small. The cross section that serves as the throat for natural gas flow is small, and the flow velocity increases to supersonic speed. Under the low-temperature, low-pressure environment, the water vapor in the natural gas condenses into liquid.

[0025] The natural gas continues to flow from the second end to the secondary acceleration section 222, where the radius r5 of the secondary acceleration section 222 is relatively large. In the supersonic fluid, the flow area increases and the flow velocity continues to increase. Here, the temperature of the natural gas continues to decrease, and the liquid water vapor continues to condense into solid crystals. Under the conditions of constant pressure and decreasing temperature, the H2S in the natural gas condenses from the gaseous state to the liquid state.

[0026] Natural gas, carrying condensed water vapor and condensed H2S, travels to the centrifugal impeller, where it throws the solid water vapor and liquid H2S towards the outlet 12 for discharge. Furthermore, the natural gas has a certain travel distance in the second stage 22; during the natural gas transport process, the axial velocity increases while the circumferential velocity decreases, thus maintaining a low airflow angle when the natural gas enters the downstream centrifugal impeller, ultimately ensuring the centrifugal impeller's rotational efficiency.

[0027] Immediately afterwards, the natural gas continues to be transported along the pipeline. The liquefied H2S and water vapor solidified into ice crystals in the natural gas are thrown out to the liquid outlet 12 by the centrifugal force of the centrifugal impeller. The natural gas continues to be transported through the gas outlet 13. This invention removes water vapor and hydrogen sulfide from natural gas by means of mechanical means, and can operate continuously, reducing processing costs.

[0028] Example 2

[0029] Reference Figure 1 As shown, let the rotor inlet radius of the driving turbine be r1, and the shaft radius of the inner rotor be r3, where 0.26 ≤ r3 / r1 ≤ 0.35; let the outlet radius of the driving turbine be r2, and satisfy... Let the minimum inlet radius of the centrifugal impeller be r6, and satisfy... The maximum relative Mach number in the centrifugal impeller flow channel is 1.2 ≤ Ma max ≤1.68, assuming the outlet blade height h of the driving turbine is... turbo The height h of the inlet blades of the centrifugal impeller turbo .

[0030] The design concept of this invention consists of three main steps:

[0031] (1) First, using the formula Estimate the geometric parameters of the driving turbine, where N is the turbine rotational speed (in revolutions per second). The specific process is as follows: k is taken as 1.4, R as 288.15, T1 is the known inlet total temperature, π is the turbine expansion ratio (range 1.5 ≤ π ≤ 4.2), and r is the average turbine blade exit radius. 22 =r3+0.5h turbo Let r3 be the known shaft radius. The initial value of the turbine blade inlet radius r1 is calculated using the formula 0.26 ≤ r3 / r1 ≤ 0.35, and the circumferential component of the inlet average absolute velocity c is also calculated. 1u The calculation method is as follows The circumferential component of the average absolute velocity at the exit is c 2u =2πNr 22 *A(0≤A≤0.4). Based on the above, ensure c 1u ≤2πNr 11 ≤1.6c 1uAnd by varying h within a reasonable range turbo Reasonable N and h can be calculated iteratively using numerical methods. turbo .

[0032] (2) Secondly, the height of the inlet section of the second segment is equal to h. turbo The inlet radius of the pipeline is equal to the outlet radius of the drive turbine, r2 = r3 + h turbo .pass Calculate r4. Then calculate r5 using 1.01 ≤ r5 / r4 ≤ 1.025. The minimum inlet radius r6 of the centrifugal impeller is obtained.

[0033] (3) Finally, for the calculation of the driving impeller, its blade inlet height h imp =r6-r3. Then, using the formula... Determine the key geometric parameters of the centrifugal impeller. Where k is taken as 1.4, R as 288.15, and π... imp The pressure ratio of the centrifugal impeller, with a value range of 1 ≤ π. imp ≤1.08. Set T3 as the static temperature at the centrifugal impeller inlet, T3 = 0.7~0.8T1. The centrifugal impeller speed N is the same as the turbine speed N calculated previously. Subsequently, the average inlet radius r of the centrifugal impeller blades... 33 =r3+0.5h imp The circumferential component of the average absolute velocity at the centrifugal impeller inlet 3u =2πNr 33 *B(0.45≤B≤0.76). Finally, the formula for calculating the circumferential component of the average absolute velocity at the outlet of the combined centrifugal impeller is c. 4u The centrifugal impeller outlet radius r7 is obtained by calculating =2πNr7*C (1≤C≤1·2).

[0034] Example 3

[0035] Reference Figures 2-5 As shown, taking a system with a total inlet pressure of 600,000 Pa, a total inlet temperature of 300 K, and a static outlet pressure of 150,000 Pa as an example, from... Figure 2-4 As can be seen, when using this device, the natural gas undergoes a three-stage cooling process from the drive turbine inlet to the centrifugal impeller outlet. After passing through the drive turbine and the second stage 22 used for throttling, the gas temperature drops to an average of 227K, at which point the water vapor has been deeply cooled to an ice crystal state, and H2S is liquefied. It can be observed that the present invention generally meets the design objectives: the average static temperature at the centrifugal impeller outlet is lower than the boiling point of H2S at the outlet (at an outlet static pressure of 0.15 MPa, the boiling point of H2S is approximately 221K), thus achieving the purpose of H2S liquefaction. Furthermore, the overall efficiency of the present invention remains above 70%, ensuring the efficiency of removing water vapor and hydrogen sulfide.

[0036] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An apparatus for removing hydrogen sulfide and water vapor from a natural gas stream, comprising: The outer casing (1) and the inner rotor installed inside the outer casing (1) are sequentially divided along the axial direction of the inner rotor into: a first section (21) with a drive turbine installed, a second section (22) for throttling, and a third section (23) with a centrifugal impeller installed. The feature is that a radial air inlet (11) leading to the drive turbine is provided on the outer shell (1), the drive turbine is a radial flow centripetal turbine, and both the drive turbine and the centrifugal impeller are disposed on the inner rotor; The second segment (22) is at least divided into a primary acceleration segment (221) with a radius of r4, close to the first segment (21), and a secondary acceleration segment (222) with a radius of r5, close to the third segment (23), where r5 > r4. The radial air inlet (11), the first segment (21), the primary acceleration segment (221), the secondary acceleration segment (222), and the third segment (23) are sequentially connected so that the natural gas entering through the radial air inlet (11) first drives the drive turbine, and then flows sequentially through the primary acceleration segment (221), the secondary acceleration segment (222), and the centrifugal impeller, and the drive turbine drives the centrifugal impeller to rotate through the inner rotor. Let the rotor inlet radius of the drive turbine be r1, and the shaft radius of the inner rotor be r3, wherein the following conditions are met: Let the outlet radius of the drive turbine be r2, and satisfy the following conditions: Let the minimum inlet radius of the centrifugal impeller be r6, and satisfy the following conditions: .

2. The apparatus for removing hydrogen sulfide and water vapor from a natural gas stream according to claim 1, characterized in that, The maximum relative Mach number in the centrifugal impeller channel .

3. The apparatus for removing hydrogen sulfide and water vapor from a natural gas stream according to claim 1, characterized in that, A liquid outlet (12) is also provided on the outer shell (1).

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