Dry gas liquid natural gas desulfurization system

Abstract

The present application provides a dry gas and liquefied gas desulfurization system, comprising: a pre-washer comprising a power wave washing pipe and a reverse spray washing section connected thereto, the power wave washing pipe being provided with a sulfur-containing dry gas inlet and a semi-lean liquid inlet, the reverse spray washing section being provided with a desulfurization solvent inlet, a rich solvent outlet and a dry gas outlet; a dry gas desulfurization tower provided with a dry gas inlet, a first lean solvent inlet, a semi-lean liquid outlet and a desulfurized dry gas outlet, the dry gas inlet being connected to the dry gas outlet, and the semi-lean liquid outlet being connected to the semi-lean liquid inlet; and a liquefied gas desulfurization tower provided with a sulfur-containing liquefied gas inlet, a second lean solvent inlet, a desulfurized liquefied gas outlet and a desulfurization solvent outlet, the desulfurization solvent outlet being connected to the desulfurization solvent inlet. The present application utilizes the pre-washer and optimizes the process flow, has the functions of solvent internal circulation and pre-washing, realizes the step-by-step utilization of semi-lean liquid and desulfurization solvent, reduces the circulation amount of rich solvent, and further reduces the energy consumption of the solvent regeneration link, thereby improving the economic efficiency of the desulfurization process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of desulfurization, in particular to a dry gas and liquefied gas desulfurization system. BACKGROUND

[0002] In the field of petrochemical production, dry gas and liquefied gas produced by catalytic cracking and hydrocracking units contain hydrogen sulfide, which needs to be desulfurized. The conventional desulfurization process generally adopts a lean solvent once-through method, that is, fresh lean solvent is respectively introduced into a dry gas desulfurization tower and a liquefied gas desulfurization tower to contact with dry gas containing sulfur and liquefied gas containing sulfur in countercurrent to complete desulfurization. After desulfurization, the rich solvent containing sulfur at the bottom is directly discharged from the system and enters a solvent regeneration unit for regeneration.

[0003] The traditional lean solvent once-through desulfurization process has the following disadvantages.

[0004] The desulfurization potential of the solvent is not fully utilized. The hydrogen sulfide content in dry gas and liquefied gas is quite different. For example, the sulfur content in catalytic dry gas is 5 to 10 times that in liquefied gas. The sulfur content (acid gas load) of the rich solvent after liquefied gas desulfurization is not saturated, and it still has the ability to be further desulfurized. However, it is directly sent to the regeneration unit, resulting in waste of solvent.

[0005] The rich solvent circulation amount is large, and the regeneration energy consumption is high. In order to meet the mass transfer requirements, the liquefied gas desulfurization process needs a suitable solvent ratio, and a large amount of lean solvent is needed for single circulation, resulting in an increase in the circulation amount of the rich solvent. The regeneration of the rich solvent consumes a large amount (usually steam), and the increase in the circulation amount directly increases the energy consumption of the solvent regeneration.

[0006] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the present application, and therefore can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0007] The present application provides a dry gas and liquefied gas desulfurization system, which can overcome the problems of insufficient utilization of solvent, large circulation amount of rich solvent, and high regeneration energy consumption in the traditional dry gas and liquefied gas desulfurization process.

[0008] According to one aspect of the present application, there is provided a dry gas liquefied gas desulfurization system, comprising: a pre-washing device comprising a power wave washing pipe and an inverse spray washing section connected in series, the power wave washing pipe being provided with a dry gas inlet containing sulfur and a semi-lean liquid inlet, the inverse spray washing section being provided with a desulfurization solvent inlet, a rich solvent outlet and a dry gas outlet; a dry gas desulfurization tower provided with a dry gas inlet, a first lean solvent inlet, a semi-lean liquid outlet and a desulfurized dry gas outlet, the dry gas inlet being connected with the dry gas outlet, and the semi-lean liquid outlet being connected with the semi-lean liquid inlet; and a liquefied gas desulfurization tower provided with a liquefied gas inlet containing sulfur, a second lean solvent inlet, a desulfurized liquefied gas outlet and a desulfurization solvent outlet, the desulfurization solvent outlet being connected with the desulfurization solvent inlet.

[0009] In some embodiments, the power wave washing pipe is configured to cause the dry gas containing sulfur from the dry gas inlet containing sulfur to undergo co-current mass transfer absorption with the first semi-lean liquid from the semi-lean liquid inlet, so that the first semi-lean liquid absorbs the hydrogen sulfide component in the dry gas containing sulfur to form a rich liquid, which enters the inverse spray washing section.

[0010] In some embodiments, the dry gas inlet containing sulfur is located at the top of the power wave washing pipe, the semi-lean liquid inlet is located at the lower part of the power wave washing pipe, and the bottom of the power wave washing pipe is connected with the inverse spray washing section.

[0011] In some embodiments, the inverse spray washing section is configured to cause the liquid phase rich solvent in the rich liquid from the power wave washing pipe to be discharged through the rich solvent outlet, and the gas phase dry gas to undergo counter-current mass transfer absorption with the desulfurization solvent from the desulfurization solvent inlet, so that the hydrogen sulfide in the gas phase dry gas is removed by the desulfurization solvent to form pre-washed dry gas, which is discharged from the dry gas outlet.

[0012] In some embodiments, the desulfurization solvent inlet is located at the upper part of the inverse spray washing section, the dry gas outlet is located at the top of the inverse spray washing section, and the desulfurization solvent inlet is located at the bottom of the inverse spray washing section.

[0013] In some embodiments, the dry gas desulfurization tower is configured to cause the pre-washed dry gas from the dry gas inlet to contact the first lean liquid solvent from the first lean solvent inlet, so that the hydrogen sulfide in the pre-washed dry gas is removed to form desulfurized dry gas, which is discharged from the desulfurized dry gas outlet, and to form a second semi-lean liquid, which is discharged from the semi-lean liquid outlet.

[0014] In some embodiments, the dry gas inlet is located at the lower part of the dry gas desulfurization tower, the first lean solvent inlet is located at the upper part of the dry gas desulfurization tower, the semi-lean liquid outlet is located at the bottom of the dry gas desulfurization tower, and the desulfurized dry gas outlet is located at the top of the dry gas desulfurization tower.

[0015] In some embodiments, the liquefied gas desulfurization tower is configured to: contact the sulfur-containing liquefied gas from the sulfur-containing liquefied gas inlet with the second lean liquid solvent from the second lean solvent inlet countercurrently to remove hydrogen sulfide in the sulfur-containing liquefied gas, form desulfurized liquefied gas discharged from the desulfurized liquefied gas outlet, and form desulfurized solvent discharged from the desulfurized solvent outlet.

[0016] In some embodiments, the sulfur-containing liquefied gas inlet is located at the lower part of the liquefied gas desulfurization tower, the second lean solvent inlet is located at the upper part of the liquefied gas desulfurization tower, the desulfurized liquefied gas outlet is located at the top of the liquefied gas desulfurization tower, and the desulfurized solvent outlet is located at the bottom of the liquefied gas desulfurization tower.

[0017] In some embodiments, the dry gas liquefied gas desulfurization system further comprises: a semi-lean liquid circulating pump, the semi-lean liquid outlet is connected to the semi-lean liquid inlet through the semi-lean liquid circulating pump; a pressure control valve arranged in the inlet pipeline of the semi-lean liquid inlet; a first liquid level control valve arranged in the outlet pipeline of the rich solvent outlet; and a second liquid level control valve arranged in the outlet pipeline of the desulfurized solvent outlet.

[0018] In some embodiments, the operating temperature of the pre-washer is 30-50℃, and the operating pressure is 0.5-1.5 MPag; the operating temperature of the dry gas desulfurization tower is 30-50℃, and the operating pressure is 0.5-1.5 MPag; and the operating temperature of the liquefied gas desulfurization tower is 30-50℃, and the operating pressure is 1.5-2.5 MPag.

[0019] The present application has at least the following beneficial effects compared with the prior art:

[0020] The present application adds a pre-washer and optimizes the process flow, has the functions of solvent internal circulation and pre-washing, can overcome the problems of insufficient utilization of solvent, large circulation amount of rich solvent, and high energy consumption of regeneration in the traditional dry gas and liquefied gas desulfurization process, realizes the step-by-step utilization of semi-lean liquid and desulfurized solvent, reduces the circulation amount of rich solvent, and ultimately reduces the energy consumption of the solvent regeneration link, and improves the economy of the desulfurization process.

[0021] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0022] The drawings incorporated into the specification and forming a part thereof illustrate embodiments in accordance with the present application and, together with the description, serve to explain the principles of the application. It is to be expressly understood that the drawings are only exemplary and are, therefore, not to be considered as limiting the application as defined by the appended claims.

[0023] Figure 1 The structure of the dry gas liquefied gas desulfurization system is shown.

[0024] Figure 2 The fluid flow structure of the dry gas liquefied gas desulfurization system in operation is shown. DETAILED DESCRIPTION

[0025] Example implementations will now be described more fully with reference to the accompanying drawings. Example implementations may, however, be implemented in many different forms and should not be construed as limited to the implementations set forth herein. Rather, these implementations are provided as non-limiting examples, so that this disclosure will fully convey the scope of the application to those skilled in the art.

[0026] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application. In the drawings:

[0027] The terms "first", "second", and similar terms do not denote any order, quantity, or importance, but are used to identify different components. In addition, in the description of the application, unless otherwise clearly specified and limited, the term "connection" should be interpreted broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or internal connection of two elements.

[0028] It should be noted that the embodiments of the application and the features in different embodiments can be combined with each other without conflict. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0029] Figure 1 The structure of the dry gas liquefied gas desulfurization system is shown, referring to Figure 1 The dry gas liquefied gas desulfurization system provided by the embodiments of the present application comprises:

[0030] The pre-washing device 100 comprises a power wave washing pipe 110 and an inverse spray washing section 120 connected in series, the power wave washing pipe 110 is provided with a sulfur-containing dry gas inlet 111 and a semi-lean liquid inlet 112, the inverse spray washing section 120 is provided with a desulfurization solvent inlet 121, a rich solvent outlet 122 and a dry gas outlet 123;

[0031] The dry gas desulfurization tower 200 is provided with a dry gas inlet 210, a first lean solvent inlet 220, a semi-lean liquid outlet 230 and a desulfurized dry gas outlet 240, the dry gas inlet 210 is connected with the dry gas outlet 123, and the semi-lean liquid outlet 230 is connected with the semi-lean liquid inlet 112;

[0032] The liquefied gas desulfurization tower 300 is provided with a sulfur-containing liquefied gas inlet 310, a second lean solvent inlet 320, a desulfurized liquefied gas outlet 330 and a desulfurized solvent outlet 340, and the desulfurized solvent outlet 340 is connected with the desulfurized solvent inlet 121.

[0033] The dry gas liquefied gas desulfurization system has at least the following advantages:

[0034] The integrated structure design of the pre-washer 100: the pre-washer 100 is simultaneously provided with the power wave washing pipe 110 and the reverse spray washing section 120, which provides a special equipment carrier for the step-by-step utilization of the semi-lean liquid and the desulfurized solvent, and realizes the segmented and solvent-efficient desulfurization of the sulfur-containing dry gas.

[0035] The two-step step-by-step washing process of the sulfur-containing dry gas: first step: the semi-lean liquid from the semi-lean liquid inlet 112 is used to absorb the hydrogen sulfide in the sulfur-containing dry gas from the sulfur-containing dry gas inlet 111, and the liquid phase rich solvent formed can be discharged from the rich solvent outlet 122, fully utilizing the desulfurization capacity of the semi-lean liquid; second step: the gaseous dry gas after power wave washing enters the reverse spray washing section 120, and the desulfurized solvent from the desulfurized solvent inlet 121 is used to further remove the residual hydrogen sulfide in the gaseous dry gas, realizing the step-by-step utilization of the desulfurized solvent in the pre-washing link.

[0036] The internal circulation system of the semi-lean liquid: the semi-lean liquid discharged from the semi-lean liquid outlet 230 of the dry gas desulfurization tower 200 can be sent back to the power wave washing pipe 110 of the pre-washer 100, forming an internal circulation of the semi-lean liquid, so that the semi-lean liquid can play a desulfurization role again before entering the regeneration link, reducing the demand for fresh lean solvent of the dry gas desulfurization tower 200.

[0037] The step-by-step utilization process of the desulfurized solvent: the desulfurized solvent discharged from the desulfurized solvent outlet 340 of the liquefied gas desulfurization tower 300 can be sent to the reverse spray washing section 120 of the pre-washer 100, so that it can participate in desulfurization again in the pre-washing dry gas link, avoiding the waste of desulfurization capacity caused by directly entering the regeneration unit.

[0038] Multi-unit cooperation reduces desulfurization load and energy consumption: the pre-washing of the dry gas by the pre-washer 100, the internal circulation of the semi-lean liquid and the step-by-step utilization of the liquefied gas solvent cooperate with each other, greatly reducing the desulfurization load of the dry gas desulfurization tower 200, and then reducing the amount of fresh lean solvent required by the dry gas desulfurization tower 200, finally realizing the reduction of the circulation amount of the rich solvent, and reducing the energy consumption of the solvent regeneration link.

[0039] Therefore, the present application has the functions of solvent internal circulation and pre-washing by adding a pre-washing device 100 and optimizing the process flow, can overcome the problems of insufficient utilization of solvent, large circulation amount of rich solvent and high energy consumption of regeneration in the traditional dry gas and liquefied gas desulfurization process, realizes the step-by-step utilization of semi-lean liquid and desulfurization solvent, reduces the circulation amount of rich solvent, and finally reduces the energy consumption of the solvent regeneration link and improves the economy of the desulfurization process.

[0040] In some embodiments, the power wave washing pipe 110 is configured to cause the sulfur-containing dry gas S-1 from the sulfur-containing dry gas inlet 111 to undergo co-current mass transfer absorption with the first semi-lean liquid S-12 from the semi-lean liquid inlet 112, so that the first semi-lean liquid S-12 absorbs the hydrogen sulfide component in the sulfur-containing dry gas S-1 to form a rich liquid, and enters the reverse spray washing section 120.

[0041] Among them, the sulfur-containing dry gas inlet 111 can be arranged at the top of the power wave washing pipe 110, the semi-lean liquid inlet 112 can be arranged at the lower part of the power wave washing pipe 110, and the bottom of the power wave washing pipe 110 is connected with the reverse spray washing section 120.

[0042] In some embodiments, the reverse spray washing section 120 is configured to cause the liquid phase rich solvent S-13 in the rich liquid from the power wave washing pipe 110 to be discharged through the rich solvent outlet 122, and the gas phase dry gas to undergo countercurrent mass transfer absorption with the first desulfurization solvent S-9 from the desulfurization solvent inlet 121, so that the hydrogen sulfide in the gas phase dry gas is removed by the first desulfurization solvent S-9, and the pre-washed dry gas S-2 is discharged from the dry gas outlet 123.

[0043] Among them, the desulfurization solvent inlet 121 can be arranged at the upper part of the reverse spray washing section 120, the dry gas outlet 123 can be arranged at the top of the reverse spray washing section 120, and the desulfurization solvent inlet 121 can be arranged at the bottom of the reverse spray washing section 120.

[0044] In some embodiments, the dry gas desulfurization tower 200 is configured to cause the pre-washed dry gas S-2 from the dry gas inlet 210 to contact the first lean liquid solvent S-7 from the first lean solvent inlet 220, so as to remove the hydrogen sulfide in the pre-washed dry gas S-2, form the desulfurized dry gas S-3 discharged from the desulfurized dry gas outlet 240, and form the second semi-lean liquid S-10 discharged from the semi-lean liquid outlet 230.

[0045] Among them, the dry gas inlet 210 can be arranged at the lower part of the dry gas desulfurization tower 200, the first lean solvent inlet 220 can be arranged at the upper part of the dry gas desulfurization tower 200, the semi-lean liquid outlet 230 can be arranged at the bottom of the dry gas desulfurization tower 200, and the desulfurized dry gas outlet 240 can be arranged at the top of the dry gas desulfurization tower 200.

[0046] In some embodiments, the liquefied petroleum gas (LPG) desulfurization tower 300 is configured to: bring sulfur-containing LPG S-4 from sulfur-containing LPG inlet 310 into countercurrent contact with second lean solvent S-6 from second lean solvent inlet 320 to remove hydrogen sulfide from sulfur-containing LPG S-4, forming desulfurized LPG S-5 which is discharged from desulfurized LPG outlet 330, and forming second desulfurization solvent S-8 which is discharged from desulfurization solvent outlet 340.

[0047] The sulfur-containing liquefied petroleum gas inlet 310 can be located at the lower part of the liquefied petroleum gas desulfurization tower 300, the second lean solvent inlet 320 can be located at the upper part of the liquefied petroleum gas desulfurization tower 300, the desulfurized liquefied petroleum gas outlet 330 can be located at the top of the liquefied petroleum gas desulfurization tower 300, and the desulfurization solvent outlet 340 can be located at the bottom of the liquefied petroleum gas desulfurization tower 300.

[0048] In some embodiments, the dry gas liquefied gas desulfurization system further includes: a semi-lean liquid circulation pump 400, with the semi-lean liquid outlet 230 connected to the semi-lean liquid inlet 112 via the semi-lean liquid circulation pump 400. The semi-lean liquid circulation pump 400 is used to pressurize the second semi-lean liquid S-10 discharged from the semi-lean liquid outlet 230 to form a third semi-lean liquid S-11. A pressure control valve K1 is installed in the inlet pipe of the semi-lean liquid inlet 112 and is used to control the pressure of the third semi-lean liquid S-11, for example, through throttling control, to form a first semi-lean liquid S-12 that is fed into the semi-lean liquid inlet 112. A first liquid level control valve K2 is installed in the outlet pipe of the rich solvent outlet 122. The second liquid level control valve K3 is installed in the outlet pipeline of the desulfurization solvent outlet 340 to maintain the stability of the liquid level in the liquefied gas desulfurization tower 300. The second desulfurization solvent S-8 discharged from the desulfurization solvent outlet 340 is converted into the first desulfurization solvent S-9 through the second liquid level control valve K3 and sent into the desulfurization solvent inlet 121.

[0049] In a specific example, refer to Figure 2 The diagram shows the fluid flow during operation of the dry gas liquefied petroleum gas (LPG) desulfurization system. The operating process of the dry gas liquefied petroleum gas (LPG) desulfurization system includes:

[0050] The sulfur-containing dry gas S-1 from upstream enters the power wave washing pipe 110 of the pre-washing device 100, and high-efficiency downstream mass transfer absorption occurs between the sulfur-containing dry gas S-1 and the breaking layer formed by the first semi-lean liquid S-12 sprayed from top to bottom. The first semi-lean liquid S-12 absorbs part of the hydrogen sulfide component in the sulfur-containing dry gas S-1 to form a rich liquid, which enters the reverse spray washing section 120 of the pre-washing device 100. The liquid phase rich solvent S-13 in the rich liquid continuously discharges through the bottom of the reverse spray washing section 120. The gas phase in the rich liquid and the first desulfurization solvent S-9 sprayed from top to bottom perform high-efficiency countercurrent mass transfer absorption, further remove hydrogen sulfide in the gas phase through the first desulfurization solvent S-9, and form pre-washed dry gas S-2 entering the dry gas desulfurization tower 200. The pre-washing device 100 is provided with the power wave washing pipe 110 and the reverse spray washing section 120, and through the internal circulation of the semi-lean liquid and the desulfurization solvent and the optimization design of the process flow, the different sulfur-containing solvent gradient utilization is realized, the desulfurization load of the dry gas desulfurization tower 200 is greatly reduced, the amount of lean solvent required by the dry gas desulfurization tower 200 can be significantly reduced, the circulation amount of the rich solvent is effectively reduced, thereby reducing the energy consumption of the rich liquid regeneration, and energy saving and carbon reduction are realized.

[0051] The pre-washed pre-washed dry gas S-2 from the lower part of the dry gas desulfurization tower 200 enters and contacts the first lean liquid solvent S-7 countercurrently from top to bottom, removes the hydrogen sulfide in the pre-washed dry gas S-2 to the standard, and then forms desulfurized dry gas S-3 which is discharged from the dry gas desulfurization tower 200. The second semi-lean liquid S-10 discharged from the bottom of the dry gas desulfurization tower 200 is pressurized by the semi-lean liquid circulation pump 400 to form the third semi-lean liquid S-11, and then enters the pre-washing device 100 after being controlled by the pressure control valve K1 to further exert the desulfurization potential of the semi-lean liquid.

[0052] The sulfur-containing liquid gas S-4 from upstream enters the liquid gas desulfurization tower 300, and countercurrently contacts the second lean liquid solvent S-6 from top to bottom. After the hydrogen sulfide in the sulfur-containing liquid gas S-4 is removed to the standard, desulfurized liquid gas S-5 is formed and discharged from the liquid gas desulfurization tower 300. The second desulfurization solvent S-8 discharged from the bottom of the liquid gas desulfurization tower 300 forms the first desulfurization solvent S-9 after being controlled by the second liquid level control valve K3, and then enters the pre-washing device 100 to further exert the desulfurization potential of the desulfurization solvent.

[0053] The operating temperature of the pre-washer 100 is 30-50°C, preferably, for example, 40°C, and the operating pressure is 0.5-1.5 MPag, preferably, for example, 1.1 MPag, which can be adjusted according to production requirements. The operating temperature of the dry gas desulfurization tower 200 is 30-50°C, preferably, for example, 40°C, and the operating pressure is 0.5-1.5 MPag, preferably, for example, 1.0 MPag, which can be adjusted according to production requirements. The operating temperature of the liquefied gas desulfurization tower 300 is 30-50°C, preferably, for example, 40°C, and the operating pressure is 1.5-2.5 MPag, preferably, for example, 2.0 MPag, which can be adjusted according to production requirements.

[0054] The dry gas liquefied gas desulfurization system of the present application can achieve the following advantages:

[0055] Integrated structure design of the pre-washer 100: The pre-washer 100 is provided with both the power wave washing pipe 110 and the reverse spray washing section 120, which provides a special equipment carrier for the step-by-step utilization of the semi-lean liquid and the desulfurization solvent, and realizes the segmented and solvent-specific efficient desulfurization of the sulfur-containing dry gas S-1.

[0056] Two-step step-by-step washing process of the sulfur-containing dry gas S-1: Step 1: In the power wave washing pipe 110 of the pre-washer 100, the first semi-lean liquid S-12 is sprayed from bottom to top to form a breaker layer, and the first semi-lean liquid S-12 absorbs part of the hydrogen sulfide to form a rich liquid, which is then discharged from the bottom of the pre-washer 100, thereby fully utilizing the desulfurization capacity of the first semi-lean liquid S-12; Step 2: The gaseous dry gas after power wave washing enters the reverse spray washing section 120 of the pre-washer 100, and the first desulfurization solvent S-9 is sprayed from top to bottom to form a counter-flow mass transfer absorption, thereby further removing the residual hydrogen sulfide in the gaseous dry gas and realizing the step-by-step utilization of the first desulfurization solvent S-9 in the pre-washing link.

[0057] Internal circulation system of the semi-lean liquid: The second semi-lean liquid S-10 discharged from the bottom of the dry gas desulfurization tower 200 is pressurized by the semi-lean liquid circulation pump 400 and controlled by the pressure control valve K1 to form the first semi-lean liquid S-12, which is then sent back to the power wave washing pipe 110 of the pre-washer 100, thereby forming an internal circulation of the semi-lean liquid and allowing the semi-lean liquid to play a desulfurization role again before entering the regeneration link, thereby reducing the demand for fresh lean solvent of the dry gas desulfurization tower 200.

[0058] Step-by-step utilization process of the desulfurization solvent: The second desulfurization solvent S-8 discharged from the liquefied gas desulfurization tower 300 is sent to the reverse spray washing section 120 of the pre-washer 100 after passing through the second liquid level control valve K3, thereby allowing it to participate in desulfurization again in the pre-washing dry gas link and avoiding the waste of desulfurization capacity caused by its direct entry into the regeneration unit.

[0059] Multi-unit synergistic reduction of desulfurization load and energy consumption: the pre-washing device 100, the semi-lean liquid internal circulation, and the liquefied gas solvent cascade utilization synergize to greatly reduce the desulfurization load of the dry gas desulfurization tower 200, thereby reducing the amount of fresh lean solvent required by the dry gas desulfurization tower 200, ultimately achieving the reduction of the circulating amount of rich solvent, and reducing the energy consumption of the solvent regeneration link.

[0060] Matching optimization of key operating parameters: the operating parameters of the pre-washing device 100, the dry gas desulfurization tower 200, and the liquefied gas desulfurization tower 300 are matched with each other, ensuring the optimization of the material transfer efficiency and desulfurization effect between units.

[0061] To facilitate understanding of the present application, the following cases are listed. Those skilled in the art should understand that the following cases are only to help understand the present application and should not be regarded as specific limitations of the present application.

[0062] Case One:

[0063] The design scale of a catalytic cracking device of a certain plant is 300 x 10 4 t / a, and the flow rate and composition of the product dry gas and liquefied petroleum gas (hereinafter referred to as LPG) are as follows. Dry gas: flow rate 20008 kg / h, temperature 44.6℃, pressure 1.1 MPa (gauge pressure), average molecular weight M=22.3, composition containing 1.75% (by weight) H2S and 5.47% (by weight) CO2. LPG: flow rate 53815 kg / h, temperature 40℃, pressure 1.3 MPa (gauge pressure), average molecular weight M=50, density 521 Kg / m 3 , composition containing 0.35% (by weight) H2S. The product quality requirements of the plant after desulfurization are as follows: purified dry gas: H2S≤20 mg / m 3 (gauge pressure), average molecular weight M=50, density 521 Kg / m

[0064] To achieve the above product quality requirements, the actual process design parameters are as follows. The desulfurizer is MDEA (N-methyl diethanolamine); the absorbent concentration is 30% (by weight); the lean liquid quality is H2S≤0.5 g / l, CO2≤2 g / l; the dry gas desulfurization tower requires 32695.1 kg / h of lean liquid, and the acid gas load (the number of moles of H2S and CO2 absorbed in the lean liquid / the number of moles of MDEA in the lean liquid) is 0.3; the LPG desulfurization tower requires 31673 kg / h of lean liquid, and the acid gas load (the number of moles of H2S absorbed in the lean liquid / the number of moles of MDEA in the lean liquid) is 0.093; the rich liquid from the dry gas desulfurization tower and the LPG desulfurization tower is combined and regenerated uniformly, and the design treatment capacity of the absorbent regeneration is 64368.1 kg / h.

[0065] To meet mass transfer requirements, the LPG desulfurization process requires a suitable oil-to-absorbent ratio, thus necessitating a lean liquor volume of 31673 kg / h and an acidic gas load of only 0.093. According to this invention, utilizing the potential of the rich LPG desulfurization liquor to further absorb H2S in downstream desulfurization processes can significantly reduce the total absorbent circulation volume, thereby substantially lowering equipment investment and overall utility consumption.

[0066] If the present invention is used, the semi-lean liquid from the dry gas desulfurization tower and the rich liquid from the bottom of the LPG desulfurization tower can be sent to the pre-washing tower for further absorption of H2S, which can significantly reduce the amount of absorbent circulating.

[0067] See Table 1 below for comparison:

[0068]

[0069] As shown in Table 1 above, after adopting this invention, the total absorbent circulation volume can be reduced by 21854.4 kg / h, which is 33.95% less than the original design, resulting in a significant reduction in utilities. Based on market prices of 1.0 MPa steam (150 yuan / t), electricity (0.5 yuan / kWh), and circulating water (0.2 yuan / t), and assuming an annual operating time of 8000 hours, adopting this invention can save 3.124 million yuan / year in operating costs (excluding the reduced MDEA consumption annually due to the reduced absorbent circulation volume).

[0070] Case 2:

[0071] The design capacity of a certain plant's wax oil hydrocracking unit is 120×10 4 The flow rates and compositions of its products, dry gas and liquefied petroleum gas (LPG), are as follows: Dry gas: flow rate 6791 kg / h, temperature 42℃, pressure 1.35 MPa (gauge pressure), average molecular weight M=17.89, composition containing 9.2% (by weight) H2S. LPG: flow rate 4261 kg / h, temperature 40℃, pressure 1.4 MPa (gauge pressure), average molecular weight M=52, composition containing 3.48% (by weight) H2S. The plant's quality requirements for the desulfurized products are as follows: H2S in the purified dry gas ≤ 20 mg / m³. 3 (Standard) The H2S content in purified LPG is ≤20 ppm.

[0072] In the case, the LPG of the hydrocracking unit is used as the feed of gas fractionation to recover isobutane, and the LPG of the catalytic cracking unit is used as domestic liquefied gas; the dry gas of the hydrocracking unit is used as the feed of hydrogen production, and the dry gas of the catalytic cracking unit is used as fuel gas, at this time, the H2S removal treatment is needed to be carried out respectively, due to the different H2S concentrations of the above-mentioned multiple streams of refinery gas, the H2S load (the ratio of the number of H2S molecules to the number of amine molecules) of the rich absorbent discharged by the H2S removal treatment process is quite different, according to the present application, the potential absorption capacity of the rich absorbent with low H2S load is fully utilized, and the purpose of reducing the circulation amount of absorbent is achieved.

[0073] If the present application is adopted, the semi-lean liquid of the dry gas desulfurization tower and the rich liquid at the bottom of the LPG desulfurization tower are sent to the pre-washing tower to further absorb H2S, which can obviously reduce the circulation amount of absorbent.

[0074] The comparison is shown in Table 2 below:

[0075]

[0076] As shown in Table 2 above, after the present application is adopted, the total circulation amount of absorbent can be reduced by 5507.9 kg / h, which is reduced by 29.9% compared with the original design, and the utility cost is obviously reduced. According to the market price, 1.0 MPa steam is 150 yuan / t, electricity is 0.5 yuan / KW.h, and circulating water is 0.2 yuan / t, and the annual operating hours are calculated as 8000 hours, then after the present application is adopted, the operation cost can be saved by 1041,000 yuan / year (excluding the MDEA amount consumed less per year due to the reduction of the circulation amount of absorbent).

[0077] Finally, it needs to be pointed out that the above content is the further detailed description of the present application combined with the specific preferred embodiments, and the specific implementation of the present application cannot be limited to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, some simple deductions or substitutions can be made without departing from the concept of the present application, and all of them should be regarded as belonging to the protection scope of the present application.

Claims

1. A dry gas liquefied petroleum gas desulfurization system, characterized in that, include: The pre-washer includes a connected dynamic wave washing pipe and a reverse spray washing section. The dynamic wave washing pipe is provided with a sulfur-containing dry gas inlet and a semi-lean liquid inlet. The reverse spray washing section is provided with a desulfurization solvent inlet, a rich solvent outlet and a dry gas outlet. The dynamic wave scrubbing tube is configured to allow sulfur-containing dry gas from the sulfur-containing dry gas inlet to undergo co-current mass transfer absorption with a first semi-lean liquid from the semi-lean liquid inlet, so that the first semi-lean liquid absorbs hydrogen sulfide components from the sulfur-containing dry gas to form a rich liquid, which then enters the counter-current spray scrubbing section. The counter-current spray scrubbing section is configured to allow the liquid-phase rich solvent in the rich liquid from the dynamic wave scrubbing tube to be discharged through the rich solvent outlet, and for the gas-phase dry gas to undergo counter-current mass transfer absorption with the desulfurization solvent from the desulfurization solvent inlet, so that hydrogen sulfide in the gas-phase dry gas is removed by the desulfurization solvent, forming pre-washed dry gas that is discharged from the dry gas outlet. The dry gas desulfurization tower is provided with a dry gas inlet, a first lean solvent inlet, a semi-lean liquid outlet, and a desulfurized dry gas outlet. The dry gas inlet is connected to the dry gas outlet, and the semi-lean liquid outlet is connected to the semi-lean liquid inlet. The liquefied petroleum gas (LPG) desulfurization tower is equipped with a sulfur-containing LPG inlet, a second lean solvent inlet, a desulfurized LPG outlet, and a desulfurization solvent outlet, wherein the desulfurization solvent outlet is connected to the desulfurization solvent inlet.

2. The dry gas liquefied gas desulfurization system as described in claim 1, characterized in that, The sulfur-containing dry gas inlet is located at the top of the dynamic wave scrubbing pipe, the semi-lean liquid inlet is located at the bottom of the dynamic wave scrubbing pipe, and the bottom of the dynamic wave scrubbing pipe is connected to the reverse spray scrubbing section.

3. The dry gas liquefied gas desulfurization system as described in claim 1, characterized in that, The desulfurization solvent inlet is located at the upper part of the reverse spray scrubbing section, the dry gas outlet is located at the top of the reverse spray scrubbing section, and the desulfurization solvent outlet is located at the bottom of the reverse spray scrubbing section.

4. The dry gas liquefied gas desulfurization system as described in claim 1, characterized in that, The dry gas desulfurization tower is configured as follows: The pre-washed dry gas from the dry gas inlet is brought into contact with the first lean solvent from the first lean solvent inlet to remove hydrogen sulfide from the pre-washed dry gas, forming desulfurized dry gas that is discharged from the desulfurized dry gas outlet, and forming a second semi-lean liquid that is discharged from the semi-lean liquid outlet.

5. The dry gas liquefied gas desulfurization system as described in claim 4, characterized in that, The dry gas inlet is located at the lower part of the dry gas desulfurization tower, the first lean solvent inlet is located at the upper part of the dry gas desulfurization tower, the semi-lean liquid outlet is located at the bottom of the dry gas desulfurization tower, and the desulfurized dry gas outlet is located at the top of the dry gas desulfurization tower.

6. The dry gas liquefied gas desulfurization system as described in claim 1, characterized in that, The liquefied gas desulfurization tower is configured as follows: The sulfur-containing liquefied gas from the sulfur-containing liquefied gas inlet is brought into countercurrent contact with the second lean solvent from the second lean solvent inlet to remove hydrogen sulfide from the sulfur-containing liquefied gas, forming desulfurized liquefied gas that is discharged from the desulfurized liquefied gas outlet, and forming desulfurized solvent that is discharged from the desulfurized solvent outlet.

7. The dry gas liquefied gas desulfurization system as described in claim 6, characterized in that, The sulfur-containing liquefied gas inlet is located at the lower part of the liquefied gas desulfurization tower, the second lean solvent inlet is located at the upper part of the liquefied gas desulfurization tower, the desulfurized liquefied gas outlet is located at the top of the liquefied gas desulfurization tower, and the desulfurization solvent outlet is located at the bottom of the liquefied gas desulfurization tower.

8. The dry gas liquefied gas desulfurization system as described in claim 1, characterized in that, Also includes: A semi-lean solution circulation pump, wherein the semi-lean solution outlet is connected to the semi-lean solution inlet via the semi-lean solution circulation pump; A pressure control valve is installed in the inlet pipe of the semi-lean liquid inlet; The first liquid level control valve is installed in the outlet pipeline of the rich solvent outlet; The second liquid level control valve is installed in the outlet pipeline of the desulfurization solvent outlet.

9. The dry gas liquefied petroleum gas desulfurization system according to any one of claims 1 to 8, characterized in that, The pre-washer operates at a temperature of 30°C to 50°C and an operating pressure of 0.5 MPa g to 1.5 MPa g. The operating temperature of the dry gas desulfurization tower is 30℃ to 50℃, and the operating pressure is 0.5MPag to 1.5MPag. The operating temperature of the liquefied gas desulfurization tower is 30°C to 50°C, and the operating pressure is 1.5 MPa to 2.5 MPa.

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