A system and method for dry gas desulfurization

Abstract

This invention provides a system and method for dry gas desulfurization, comprising a cooling device, a buffer device, a first desulfurization tower, and a second desulfurization tower connected in sequence. The cooling device is used to cool the raw material dry gas. The buffer device is connected to the cooling device and receives the cooled raw material dry gas for impurity removal. The first desulfurization tower is connected to the buffer device and receives the impurity-removed raw material dry gas for first desulfurization to obtain first desulfurized dry gas. The second desulfurization tower includes an inverted funnel-shaped gas-lifting structure, dividing the second desulfurization tower into a lower desulfurization section and an upper water washing section. The desulfurization section is connected to the first desulfurization tower and receives the first desulfurized dry gas for second desulfurization to obtain second desulfurized dry gas. The desulfurization section and the water washing section are connected through the gas-lifting structure so that the second desulfurized dry gas enters the water washing section. By implementing dry gas desulfurization through the system of this invention, the H2S content in the dry gas is effectively reduced, the thermal efficiency of the heating furnace is improved, the dew point corrosion problem of the heating furnace flue gas is solved, and impurities such as condensed oil, solid particles, and washing liquid in the desulfurized dry gas are also reduced.

Description

Technical Field

[0001] This invention relates to the field of dry gas desulfurization, and particularly to a system and method for dry gas desulfurization. Background Technology

[0002] Refinery heating furnaces typically use desulfurized dry gas as fuel, which is mixed with a fixed amount of air and burned to generate a large amount of heat for heating various media materials. The resulting flue gas is cooled after waste heat recovery and then discharged into the atmosphere. Because the desulfurized dry gas still contains 20-60 mg / Nm³ of sulfur dioxide... 3 The H2S component in flue gas produces SO2 acidic gas upon combustion. If too much waste heat is recovered from the flue gas, the exhaust temperature drops below the dew point, easily forming sulfuric acid and sulfurous acid, which corrode the equipment. Therefore, waste heat recovery from flue gas often needs to be limited to a certain range to ensure that the exhaust gas temperature is above the dew point. However, this operation will result in some heat in the flue gas not being recovered, causing the furnace thermal efficiency to be lower than 94%.

[0003] If refineries can continue to reduce the H2S content in the desulfurized dry gas, even to below 2 ppmv, they can recover more flue gas heat, keep the heating furnace thermal efficiency above 95%, and greatly reduce the company's carbon emissions.

[0004] Desulfurization of refinery fuel gas typically employs an amine process based on organic alcohol amines such as MDEA to remove H2S, aiming to meet H2S content control targets. However, due to the complex composition and high H2S content of raw fuel gas in refineries, the H2S content in the fuel gas after the amine washing process remains between 20-60 mg / Nm³. 3 The range is wide, the fluctuations are large, and the content is high, which leads to problems such as high SO2 emissions and low efficiency of the heaters when the refinery fuel gas is used as fuel for the downstream unit heaters. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a system and method for dry gas desulfurization. Using this system for dry gas desulfurization can effectively improve the desulfurization effect of the raw material dry gas, reducing the H2S content in the dry gas to 2 mg / Nm³. 3 The invention improves the thermal efficiency of the combustion furnace; moreover, by setting up a gas-liquid separation system, it effectively reduces the impurity content in the desulfurized dry gas.

[0006] The objective of this invention is mainly achieved through the following technical solutions.

[0007] In a first aspect, the present invention provides a system for desulfurization of dry gas, the system comprising a cooling device, a buffer device, a first desulfurization tower, and a second desulfurization tower connected in sequence.

[0008] The cooling equipment is used to cool the raw material dry gas.

[0009] The buffer device is connected to the cooling device and is used to receive the cooled raw material dry gas and remove impurities from it.

[0010] The first desulfurization tower is connected to the buffer device and is used to receive the purified raw material dry gas and perform the first desulfurization to obtain the first desulfurized dry gas.

[0011] The second desulfurization tower includes an inverted funnel-shaped gas lifting structure that divides the second desulfurization tower into a lower desulfurization section and an upper water washing section.

[0012] The desulfurization section is connected to the first desulfurization tower to receive the first desulfurized dry gas and perform a second desulfurization to obtain a second desulfurized dry gas; the water washing section is connected to the desulfurization section through a gas lifting structure and is used to wash the second desulfurized dry gas with water.

[0013] Preferably, the air-lifting structure includes a funnel-shaped opening section and a straight pipe section, the straight pipe section extending into the water-washing section.

[0014] Preferably, the funnel opening section is conical, and the ratio of the height of the cone to the diameter of the cone surface is H1:R1 = 1:0.5-3.5, more preferably H1:R1 = 1:0.5-1.5.

[0015] Preferably, the outlet position of the straight pipe section is higher than the liquid level height set by the level gauge of the water washing section, and more preferably 10%-20% higher than the liquid level height set by the level gauge.

[0016] Preferably, the lower sidewall of the desulfurization section is provided with a first desulfurized dry gas inlet section, and the angle α between the outlet direction of the first desulfurized dry gas inlet section and the tangent of the sidewall is 20-80°, preferably 30-60°.

[0018] Preferably, the number of the first desulfurized dry gas inlet sections is 2-5, and more preferably 3-4;

[0019] Preferably, the first desulfurized dry gas inlet section is located on the same horizontal plane.

[0020] Preferably, the volume ratio of the desulfurization section to the water washing section is 1:0.15-0.5, and more preferably 1:0.2-0.35.

[0021] Preferably, the desulfurization section is provided with an alkaline washing liquid circulation structure for circulating the alkaline washing liquid at the bottom of the desulfurization section to the upper part of the desulfurization section; preferably, the bottom of the desulfurization section is provided with an alkaline washing liquid outlet, and the upper side wall of the desulfurization section is provided with an alkaline washing liquid inlet. The alkaline washing liquid circulation structure includes an alkaline washing liquid circulation pipeline and an alkaline washing pump installed thereon. The two ends of the alkaline washing liquid circulation pipeline are respectively connected to the alkaline washing liquid outlet and the alkaline washing liquid inlet.

[0022] Preferably, the upper part of the desulfurization section also has a replenishment inlet for receiving fresh alkali solution.

[0023] Preferably, the washing section has a washing water outlet at the lower part and a washing water inlet on the upper side wall, and the washing water outlet and the washing water inlet are connected by a pipeline and a washing pump installed on the pipeline.

[0024] Preferably, the upper part of the washing section is also provided with a replenishment inlet for receiving demineralized water.

[0025] Preferably, the lower side wall of the first desulfurization tower is provided with a raw material dry gas inlet, which is connected to the raw material dry gas outlet of the buffer device.

[0026] Preferably, the upper side wall of the first desulfurization tower is provided with a lean liquid inlet for receiving lean liquid to perform the first desulfurization on the raw material dry gas entering the first desulfurization tower.

[0027] Preferably, the bottom of the first desulfurization tower is provided with a rich liquid outlet for discharging the rich liquid obtained after the first desulfurization.

[0028] The lower side wall of the first gas-liquid separation tower is provided with a first desulfurized dry gas inlet, which is connected to the first desulfurized dry gas outlet at the top of the first desulfurization tower to receive and perform first purification on the first desulfurized dry gas.

[0029] The first gas-liquid separation tower is provided with a first purified dry gas outlet at the top, and the first purified dry gas outlet is connected to the desulfurization section.

[0030] Preferably, the system further includes a second gas-liquid separation device, wherein the second gas-liquid separation tower is connected to the water washing section to receive and perform a second gas-liquid separation on the second desulfurized dry gas from the water washing section.

[0031] Preferably, the lower side wall of the second gas-liquid separation tower is provided with a second desulfurization dry gas inlet, which is connected to the second desulfurization dry gas outlet at the top of the water washing section.

[0032] In a second aspect, the present invention provides a method for desulfurization of dry gas, the method being implemented using the system described in the first aspect, comprising:

[0033] S1. The raw material dry gas is sent into a cooling device to cool down, and the cooled raw material dry gas is obtained.

[0034] S2. The cooled raw material dry gas is sent to a buffer device for storage and impurity removal to obtain impurity-removed raw material dry gas.

[0035] S3. The purified raw material dry gas is sent into the first desulfurization tower for the first desulfurization to obtain the first desulfurized dry gas.

[0036] S4. The first desulfurized dry gas is sent into the desulfurization section of the second desulfurization tower for second desulfurization to obtain the second desulfurized dry gas.

[0037] S5. The second desulfurized dry gas is fed into the water washing section through the gas lifting structure for water washing and alkali removal, resulting in the second desulfurized dry gas after alkali removal.

[0038] Preferably, in step S4, before the first desulfurized dry gas enters the second desulfurization tower, it first enters the first gas-liquid separation tower for first purification to obtain the purified first desulfurized dry gas.

[0039] The purified first desulfurized dry gas enters the desulfurization section of the second desulfurization tower for second desulfurization.

[0040] Preferably, the method further includes step S6: the second desulfurized dry gas after alkali removal is discharged from the top of the water washing section and sent to the second gas-liquid separation tower for second purification to obtain the purified second desulfurized dry gas.

[0041] Preferably, the flow rate of the raw material dry gas is 1000-9000 m³ / h. 3 / h, preferably 3000-6000m 3 / h.

[0042] Preferably, the temperature of the raw material dry gas after being cooled by the cooling equipment is 30-50°C, and more preferably 35-45°C.

[0043] Preferably, in step S2, the conditions for impurity removal include: a gas phase pressure of 0.5-0.8 MPa, more preferably 0.6-0.7 MPa.

[0044] Preferably, the flow rate of the lean liquor entering the first desulfurization tower is 40-80 m³ / h. 3 / h, preferably 50-70m 3 / h.

[0045] Preferably, in step S3, the conditions for the first desulfurization include: a gas phase pressure of 0.5-0.8 MPa, more preferably 0.6-0.7 MPa; and a temperature of 30-50°C, more preferably 35-45°C.

[0046] Preferably, in step S4, the conditions for the second desulfurization include: a gas phase pressure of 0.5-0.8 MPa, more preferably 0.6-0.7 MPa; and a temperature of 30-50°C, more preferably 35-45°C.

[0047] Preferably, in step S5, the water washing conditions include a gas phase pressure of 0.5-0.8 MPa, more preferably 0.6-0.7 MPa.

[0048] Preferably, in step S4, the conditions for the first purification include: a gas phase pressure of 0.5-0.8 MPa, more preferably 0.6-0.7 MPa; and a temperature of 30-50°C, more preferably 35-45°C.

[0049] Preferably, in step S6, the conditions for the second purification include: a gas phase pressure of 0.5-0.8 MPa, more preferably 0.6-0.7 MPa; and a temperature of 30-50°C, more preferably 35-45°C.

[0050] Preferably, the flow rate of the alkaline washing pump is 30-80 m³ / h. 3 / h, preferably 45-55m 3 / h.

[0051] Preferably, the flow rate of the water washing pump is 2-20 m³ / h. 3 / h, preferably 4-8m 3 / h.

[0052] Preferably, the lean solution is selected from N-methyldiethanolamine and / or diethanolamine.

[0053] Preferably, the alkali in the alkaline solution is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.

[0054] Preferably, the H2S content in the depleted solution is <0.1 mg / L.

[0055] Preferably, the outlet of the straight pipe section is higher than the liquid level in the washing tank.

[0056] The present invention relates to a dry gas desulfurization device and method, which has the following advantages:

[0057] (1) Effectively removes H2S from raw material dry gas; H2S content can be controlled at 2 mg / Nm³. 3 the following;

[0058] (2) Desulfurized dry gas is used in heating furnaces, and the thermal efficiency of the heating furnaces can reach over 95%;

[0059] (3) The purified second desulfurized dry gas obtained not only removes impurities such as condensed oil and solid particles, but also effectively separates the carried solution. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of a dry gas desulfurization system according to the present invention;

[0061] Figure 2 This is a side view of the air-lifting structure 43 of the present invention;

[0062] Figure 3 This is a top view of the first desulfurized dry gas inlet section 411 of the present invention;

[0063] Figure 4 This is a schematic diagram of a dry gas desulfurization system according to Comparative Example 1 of the present invention;

[0064] Figure 5 This is a schematic diagram of a dry gas desulfurization system according to Comparative Example 2 of the present invention. Detailed Implementation

[0065] The preferred embodiments of the invention will now be described in detail with reference to the accompanying drawings, which form part of the invention and, together with the embodiments thereof, serve to illustrate the principles of the invention.

[0066] The inventors of this invention discovered through research that removing impurities such as condensate and solid particles from the raw material dry gas before desulfurization is beneficial to improving the desulfurization effect. Furthermore, adding a secondary desulfurization step on top of the primary desulfurization can further improve the desulfurization effect of the dry gas. Moreover, the inventors have further improved the secondary desulfurization equipment by cleverly dividing the desulfurization equipment into three interconnected areas, enabling one device to complete both desulfurization and water washing functions. In addition, by designing a special structure for the gas lifting structure in the area, the purity of the desulfurized dry gas is greatly improved.

[0067] Based on the above research, in a first aspect, the present invention provides a system for dry gas desulfurization, such as... Figure 1 The system includes a cooling device 1, a buffer device 2, a first desulfurization tower 3, and a second desulfurization tower 4 connected in sequence.

[0068] The cooling device 1 is used to cool the dry gas from the raw material.

[0069] The buffer device 2 is connected to the cooling device 1 and is used to receive the cooled raw material dry gas and remove impurities from it.

[0070] The first desulfurization tower 3 is connected to the buffer device 2 and is used to receive the raw material dry gas after impurity removal and perform the first desulfurization to obtain the first desulfurized dry gas.

[0071] The second desulfurization tower 4 includes an inverted funnel-shaped gas lifting structure (43), which divides the second desulfurization tower (4) into a lower desulfurization section (41) and an upper water washing section (42).

[0072] The desulfurization section 41 is connected to the first desulfurization tower 3 to receive the first desulfurized dry gas and perform the second desulfurization to obtain the second desulfurized dry gas; the water washing section (42) is connected to the desulfurization section 41 through the gas lifting structure 43 and is used to wash the second desulfurized dry gas with water.

[0073] A preferred embodiment of the present invention, such as Figure 2 As shown, the air-lifting structure 43 includes a funnel-mouth section 431 and a straight pipe section 432, with the straight pipe section 432 extending into the water washing section 42;

[0074] In a preferred embodiment of the present invention, the funnel opening section 431 is conical, and the ratio of the height of the cone to the diameter of the cone surface is H1:R1 = 1:0.5-3.5, preferably H1:R1 = 1:0.5-1.5.

[0075] In a preferred embodiment of the present invention, the outlet position of the straight pipe section 432 is higher than the liquid level height set by the level gauge of the water washing section, preferably 10%-20% higher than the liquid level height set by the level gauge.

[0076] A preferred embodiment of the present invention, such as Figure 3 As shown, the lower sidewall of the desulfurization section 41 is provided with a first desulfurization dry gas inlet section 411, and the angle α between the outlet direction of the first desulfurization dry gas inlet section 411 and the tangent of the sidewall is 20-80°, preferably 30-60°.

[0077] In a preferred embodiment of the present invention, the number of the first desulfurized dry gas inlet sections 411 is 2-5, preferably 3-4; and / or, the first desulfurized dry gas inlet sections 411 are located on the same horizontal plane.

[0078] In a preferred embodiment of the present invention, the volume ratio of the desulfurization section 41 to the water washing section 42 is 1:0.15-0.5, preferably 1:0.2-0.35.

[0079] In a preferred embodiment of the present invention, the desulfurization section 41 is provided with an alkaline washing liquid circulation structure for circulating the alkaline washing liquid at the bottom of the desulfurization section 41 to the upper part of the desulfurization section 41; preferably, the bottom of the desulfurization section 41 is provided with an alkaline washing liquid outlet, and the upper side wall of the desulfurization section (41) is provided with an alkaline washing liquid inlet. The alkaline washing liquid circulation structure includes an alkaline washing liquid circulation pipeline and an alkaline washing pump 7 installed thereon. The two ends of the alkaline washing liquid circulation pipeline are respectively connected to the alkaline washing liquid outlet and the alkaline washing liquid inlet.

[0080] In a preferred embodiment of the present invention, the upper part of the desulfurization section 41 also has a replenishment inlet for receiving fresh alkali solution.

[0081] In a preferred embodiment of the present invention, the lower part of the washing section 42 is provided with a washing water outlet and the upper side wall is provided with a washing water inlet. The washing water outlet and the washing water inlet are connected by a pipeline and a washing pump 8 installed on the pipeline.

[0082] In a preferred embodiment of the present invention, the upper part of the washing section 42 is further provided with a replenishment inlet for receiving demineralized water.

[0083] In a preferred embodiment of the present invention, the lower side wall of the first desulfurization tower 3 is provided with a raw material dry gas inlet, which is connected to the raw material dry gas outlet of the buffer device 2; the upper side wall of the first desulfurization tower 3 is provided with a lean liquid inlet, which is used to receive lean liquid to perform the first desulfurization on the raw material dry gas entering the first desulfurization tower 3.

[0084] In a preferred embodiment of the present invention, the bottom of the first desulfurization tower 3 is provided with a rich liquid outlet for discharging the rich liquid obtained after the first desulfurization.

[0085] In a preferred embodiment of the present invention, a first gas-liquid separation tower 5 is further provided between the first desulfurization tower 3 and the second desulfurization tower 4; with this preferred design, the solution carried in the first desulfurization dry gas can be removed before the first desulfurization dry gas enters the second desulfurization tower 4.

[0086] The lower side wall of the first gas-liquid separation tower 5 is provided with a first desulfurized dry gas inlet, which is connected to the first desulfurized dry gas outlet at the top of the first desulfurization tower 3 to receive and perform first purification on the first desulfurized dry gas.

[0087] The first gas-liquid separation tower 5 is provided with a first purified dry gas outlet at the top, and the first purified dry gas outlet is connected to the desulfurization section 41.

[0088] In a preferred embodiment of the present invention, the system is further provided with a second gas-liquid separation device 6, the second gas-liquid separation tower 6 being connected to the water washing section 42 to receive and perform second gas-liquid separation on the second desulfurized dry gas from the water washing section 42; with this preferred design, the liquid carried in the second desulfurized dry gas can be effectively removed, thereby improving the purity of the second desulfurized dry gas.

[0089] In a preferred embodiment of the present invention, a second desulfurization dry gas inlet is provided on the lower side wall of the second gas-liquid separation tower 6, and the second desulfurization dry gas inlet is connected to the second desulfurization dry gas outlet at the top of the water washing section 42.

[0090] In a second aspect, the present invention provides a method for desulfurization of dry gas, the method being implemented using the system described in the first aspect, comprising:

[0091] S1. The raw material dry gas is sent into the cooling equipment (1) to cool down, and the cooled raw material dry gas is obtained.

[0092] S2. The cooled raw material dry gas is sent to the buffer device (2) for storage and impurity removal to obtain the impurity-removed raw material dry gas.

[0093] S3. The purified raw material dry gas is sent into the first desulfurization tower (3) for the first desulfurization to obtain the first desulfurized dry gas;

[0094] S4. The first desulfurized dry gas is sent into the desulfurization section (41) of the second desulfurization tower (4) for second desulfurization to obtain the second desulfurized dry gas.

[0095] S5. The second desulfurized dry gas is sent into the water washing section (42) through the gas lifting structure (43) for water washing and alkali removal to obtain the second desulfurized dry gas after alkali removal.

[0096] In a preferred embodiment of the present invention, in step S4, before the first desulfurized dry gas enters the second desulfurization tower 4, it first enters the first gas-liquid separation tower 5 for first purification to obtain purified first desulfurized dry gas. The purified first desulfurized dry gas then enters the desulfurization section 41 of the second desulfurization tower 4 for second desulfurization.

[0097] In a preferred embodiment of the present invention, the method further includes step S6: the second desulfurized dry gas after alkali removal is discharged from the top of the water washing section 42 and sent to the second gas-liquid separation tower 6 for second purification to obtain the purified second desulfurized dry gas.

[0098] In a preferred embodiment of the present invention, the flow rate of the raw material dry gas is 1000-9000 m³ / h. 3 / h, preferably 3000-6000m 3 / h.

[0099] In a preferred embodiment of the present invention, the temperature of the raw material dry gas after being cooled by the cooling device 1 is 30-50°C, preferably 35-45°C. Using this preferred temperature effectively removes impurities such as oil and particulate matter from the desulfurized dry gas, and the raw material dry gas entering subsequent equipment at this temperature is more conducive to removing H2S.

[0100] In a preferred embodiment of the present invention, the conditions for impurity removal in step S2 include: a gas phase pressure of 0.5-0.8 MPa, preferably 0.6-0.7 MPa.

[0101] In a preferred embodiment of the present invention, the flow rate of the lean liquor entering the first desulfurization tower 3 is 40-80 m³ / h. 3 / h, preferably 50-70m 3 / h.

[0102] In a preferred embodiment of the present invention, in step S3, the conditions for the first desulfurization include: a gas phase pressure of 0.5-0.8 MPa, preferably 0.6-0.7 MPa; and a temperature of 30-50°C, preferably 35-45°C.

[0103] In a preferred embodiment of the present invention, step S4 includes the following conditions for the second desulfurization: gas phase pressure of 0.5-0.8 MPa, preferably 0.6-0.7 MPa; and temperature of 30-50°C, preferably 35-45°C.

[0104] In a preferred embodiment of the present invention, in step S5, the water washing conditions include: a gas phase pressure of 0.5-0.8 MPa, preferably 0.6-0.7 MPa.

[0105] In a preferred embodiment of the present invention, in step S4, the conditions for the first purification include: a gas phase pressure of 0.5-0.8 MPa, preferably 0.6-0.7 MPa; and a temperature of 30-50°C, preferably 35-45°C.

[0106] In a preferred embodiment of the present invention, in step S6, the conditions for the second purification include: a gas phase pressure of 0.5-0.8 MPa, preferably 0.6-0.7 MPa; and a temperature of 30-50°C, preferably 35-45°C.

[0107] In a preferred embodiment of the present invention, the flow rate of the alkaline washing pump 7 is 30-80 m³ / h. 3 / h, preferably 45-55m 3 / h.

[0108] In a preferred embodiment of the present invention, the flow rate of the water washing pump 8 is 2-20 m³ / h. 3 / h, preferably 4-8m 3 / h.

[0109] In this invention, both "gas phase pressure" and "pressure" are gauge pressure.

[0110] In a preferred embodiment of the present invention, the lean solution is selected from N-methyldiethanolamine and / or diethanolamine; more preferably N-methyldiethanolamine.

[0111] In a preferred embodiment of the present invention, the alkali in the alkaline solution is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate; more preferably, it is sodium hydroxide.

[0112] In a preferred embodiment of the present invention, the H2S content in the depleted solution is <0.1 mg / L.

[0113] In a preferred embodiment of the present invention, the outlet position of the straight pipe section 432 is higher than the liquid level in the washing tank 42.

[0114] The following detailed description of preferred embodiments of the present invention illustrates the principles of the invention and is not intended to limit the scope of the invention.

[0115] Example 1

[0116] according to Figure 1 As shown, the alkaline washing pump 7 and the water washing pump 8 are turned on, and the raw material dry gas (flow rate of 16000 Nm3 / h, H2S content of 51200 mg / Nm3) is used. 3 The gas enters the cooling device 1 to cool down to 40°C, and then enters the buffer device 2 to remove solidified oil and solid particles, thus obtaining the purified raw material dry gas.

[0117] The purified raw material dry gas enters the first desulfurization tower 3 from the lower part and comes into countercurrent contact with the N-methyldiethanolamine solution (flow rate of 65t / h, concentration of 30wt%) entering from the upper part of the first desulfurization tower 3 to carry out the first desulfurization (gas phase pressure of 0.65MPa, temperature of 40℃) to obtain the first desulfurized dry gas and rich liquid. The obtained rich liquid is discharged from the bottom of the first desulfurization tower 3.

[0118] The first desulfurized dry gas obtained is discharged from the top of the first desulfurization tower 3 and then enters the first gas-liquid separation tower 5 (gas phase pressure is 0.645MPa, temperature is 40℃) for purification to remove the carried lean liquid and obtain the purified first desulfurized dry gas.

[0119] The purified first desulfurized dry gas enters the desulfurization section 41 (18.8m high, 2.4m in diameter, 0.65MPa gas pressure, and 40℃ temperature) from three inlet sections 411 located in the lower part of the desulfurization section (41) (the three inlet sections are distributed at equal distances on the same horizontal plane, and the outlet direction is at a 45° angle to the tangent of the side wall). It then comes into countercurrent contact with the circulating alkaline washing liquid (circulation rate of 50t / h, 20wt% sodium hydroxide solution) flowing down from the upper part of the desulfurization section 41 to carry out the second desulfurization, and obtains the second desulfurized dry gas.

[0120] The second desulfurized dry gas enters the water washing section 42 (5.5m high, 2.4m in diameter) via the rising structure 43 (specifically, the funnel section 431 is conical with a height of 1.2m and a diameter of 1.1m; the outlet of the straight pipe section 432 is 12% higher than the highest liquid level in the water washing section 42) for water washing; the water-washed second desulfurized dry gas is discharged from the top of the water washing section 42 and enters the second gas-liquid separation tower 6 (gas phase pressure of 0.645MPa, temperature of 40℃) for second purification to obtain purified second desulfurized dry gas;

[0121] Tests showed that the H2S content in the purified second desulfurization dry gas was 0.5 mg / Nm³. 3 It can be used in downstream heating furnaces, where the thermal efficiency can reach 95.6%.

[0122] Example 2

[0123] according to Figure 1 As shown, the alkaline washing pump 7 and the water washing pump 8 are turned on, and the raw material dry gas (flow rate of 16000 Nm3 / h, H2S content of 51200 mg / Nm3) is used. 3 The gas enters the cooling equipment 1 to be cooled to 37°C, and then enters the buffer equipment 2 to remove solidified oil and solid particles, thus obtaining the purified raw material dry gas.

[0124] The purified raw material dry gas enters the first desulfurization tower 3 from the lower part and comes into countercurrent contact with the N-methyldiethanolamine solution (flow rate of 65t / h, concentration of 20wt%) entering from the upper part of the first desulfurization tower 3 to carry out the first desulfurization (pressure of 0.65MPa, temperature of 40℃) to obtain the first desulfurized dry gas and rich liquid. The obtained rich liquid is discharged from the bottom of the first desulfurization tower 3.

[0125] The first desulfurized dry gas obtained is discharged from the top of the first desulfurization tower 3 and then enters the first gas-liquid separation tower 5 (pressure 0.645MPa, temperature 40℃) for purification to remove the carried lean liquid and obtain the purified first desulfurized dry gas.

[0126] The purified first desulfurized dry gas enters the desulfurization section 41 (18.8m high, 2.4m in diameter, 0.65MPa gas pressure, and 40℃ temperature) from three inlet sections 411 located in the lower part of the desulfurization section (41) (the three inlet sections are distributed at equal distances on the same horizontal plane, and the outlet direction is at a 45° angle to the tangent of the side wall). It then comes into countercurrent contact with the circulating alkaline washing liquid (circulation rate of 50t / h, 20wt% sodium hydroxide solution) flowing down from the upper part of the desulfurization section 41 to carry out the second desulfurization, and obtains the second desulfurized dry gas.

[0127] The second desulfurized dry gas enters the water washing section 42 (5.5m high, 2.4m in diameter) via the rising structure 43 (specifically, the funnel section 431 is conical with a height of 1.2m and a diameter of 1.1m; the outlet of the straight pipe section 432 is 12% higher than the highest liquid level in the water washing section 42) for water washing; the water-washed second desulfurized dry gas is discharged from the top of the water washing section 42 and enters the second gas-liquid separation tower 6 (gas phase pressure of 0.645MPa, temperature of 40℃) for second purification to obtain purified second desulfurized dry gas;

[0128] Tests showed that the H2S content in the purified second desulfurization dry gas was 1.3 mg / Nm³. 3It can be used in downstream heating furnaces, where the thermal efficiency can reach 95.2%.

[0129] Example 3

[0130] according to Figure 1 As shown, the alkaline washing pump 7 and the water washing pump 8 are turned on, and the raw material dry gas (flow rate of 16000 Nm3 / h, H2S content of 51200 mg / Nm3) is used. 3 The gas enters the cooling device 1 to cool down to 40°C, and then enters the buffer device 2 to remove solidified oil and solid particles, thus obtaining the purified raw material dry gas.

[0131] The purified raw material dry gas enters the first desulfurization tower 3 from the lower part and comes into countercurrent contact with the N-methyldiethanolamine solution (flow rate of 65t / h, concentration of 30wt%) entering from the upper part of the first desulfurization tower 3 to carry out the first desulfurization (gas phase pressure of 0.65MPa, temperature of 40℃) to obtain the first desulfurized dry gas and rich liquid. The obtained rich liquid is discharged from the bottom of the first desulfurization tower 3.

[0132] The first desulfurized dry gas obtained is discharged from the top of the first desulfurization tower 3 and then enters the first gas-liquid separation tower 5 (gas phase pressure is 0.645MPa, temperature is 40℃) for purification to remove the carried lean liquid and obtain the purified first desulfurized dry gas.

[0133] The purified first desulfurized dry gas enters the desulfurization section 41 (18.8m high, 2.4m in diameter, 0.65MPa gas pressure, and 40℃ temperature) from three inlet sections 411 located in the lower part of the desulfurization section (41) (the three inlet sections are distributed at equal distances on the same horizontal plane, and the outlet direction is at a 45° angle to the tangent of the side wall). It then comes into countercurrent contact with the circulating alkaline washing liquid (circulation rate of 50t / h, 10wt% sodium hydroxide solution) flowing down from the upper part of the desulfurization section 41 to carry out the second desulfurization, and obtains the second desulfurized dry gas.

[0134] The second desulfurized dry gas enters the water washing section 42 (5.5m high, 2.4m in diameter) via the rising structure 43 (specifically, the funnel section 431 is conical with a height of 1.2m and a diameter of 1.1m; the outlet of the straight pipe section 432 is 12% higher than the highest liquid level in the water washing section 42) for water washing; the water-washed second desulfurized dry gas is discharged from the top of the water washing section 42 and enters the second gas-liquid separation tower 6 (gas phase pressure of 0.645MPa, temperature of 40℃) for second purification to obtain purified second desulfurized dry gas;

[0135] Tests showed that the H2S content in the purified second desulfurization dry gas was 1.6 mg / Nm³. 3 It can be used in downstream heating furnaces, where the thermal efficiency can reach 95.1%.

[0136] Comparative Example 1

[0137] The method is carried out according to Example 1, except that a second desulfurization tower 4 and a second gas-liquid separation tower 6 are not provided.

[0138] Tests showed that the H2S content in the purified desulfurized dry gas discharged from the first gas-liquid separator 5 was 59 mg / Nm³. 3 It is used in the heating furnace of downstream equipment, and the heating furnace has a thermal efficiency of 93.95%.

[0139] Comparative Example 2

[0140] The method is carried out according to Example 1, except that, as Figure 3 As shown, the second desulfurization tower 4 is replaced by two separate second desulfurization devices 9 and water washing devices 10. The diameter and volume of the second desulfurization devices are the same as those of the desulfurization section 41, and the diameter and volume of the water washing devices are the same as those of the water washing section 42. The second desulfurization devices 9 and water washing devices 10 are connected by pipelines.

[0141] Tests showed that the H2S content in the purified second desulfurization dry gas was 6 mg / Nm³. 3 It is used in downstream heating furnaces, where the thermal efficiency can reach 94.2%.

[0142] Test case

[0143] Following the method in Example 1, the system was operated continuously for one month. The H2S content in the raw material dry gas, the H2S content in the second desulfurization dry gas, and the thermal efficiency of the heating furnace were measured at 7:30 am on the 5th, 10th, 15th, 20th, 25th, and 30th of the month, respectively. The measurement results are shown in Table 1.

[0144] Table 1

[0145]

[0146] As can be seen from the above embodiments and comparative examples, the device of the present invention can effectively improve the desulfurization effect when used for dry gas desulfurization, and the H2S content in the desulfurized dry gas can be as low as 0.5 mg / Nm³. 3 The H2S content is much lower than that of Comparative Example 1 and Comparative Example 2; the heating furnace efficiency can reach over 95%.

[0147] As shown in Table 1, the device of the present invention operates stably and can control the H2S content in desulfurized dry gas to within 2 mg / Nm³. 3 the following.

[0148] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A system for desulfurization of dry gas, characterized in that, The system includes a cooling device (1), a buffer device (2), a first desulfurization tower (3), and a second desulfurization tower (4) connected in sequence; The cooling device (1) is used to cool the raw material dry gas; The buffer device (2) is connected to the cooling device (1) and is used to receive the cooled raw material dry gas and remove impurities from it. The first desulfurization tower (3) is connected to the buffer device (2) and is used to receive the raw material dry gas after impurity removal and perform the first desulfurization to obtain the first desulfurized dry gas; The second desulfurization tower (4) includes an inverted funnel-shaped gas lifting structure (43), which divides the second desulfurization tower (4) into a lower desulfurization section (41) and an upper water washing section (42). The desulfurization section (41) is connected to the first desulfurization tower (3) to receive the first desulfurized dry gas and perform second desulfurization to obtain the second desulfurized dry gas; the water washing section (42) is connected to the desulfurization section (41) through the gas lifting structure (43) and is used to wash the second desulfurized dry gas with water.

2. The system according to claim 1, characterized in that, The air-lifting structure (43) includes a funnel-mouth section (431) and a straight pipe section (432), the straight pipe section (432) extending into the water washing section (42); Preferably, the funnel-shaped opening section (431) is conical, and the ratio of the height of the cone to the diameter of the cone surface is H1:R1 = 1:0.5-3.5, preferably H1:R1 = 1:0.5-1.5; And / or, the outlet position of the straight pipe section (432) is higher than the liquid level height set by the level gauge of the water washing section (42), preferably 10%-20% higher than the liquid level height set by the level gauge; And / or, the lower sidewall of the desulfurization section (41) is provided with a first desulfurization dry gas inlet section (411), and the angle α between the outlet direction of the first desulfurization dry gas inlet section (411) and the tangent of the sidewall is 20-80°, preferably 30-60°. And / or, the number of the first desulfurized dry gas inlet section (411) is 2-5, preferably 3-4; And / or, the first desulfurized dry gas inlet section (411) is located on the same horizontal plane; And / or, the volume ratio of the desulfurization section 41 and the water washing section 42 is 1:0.15-0.5, preferably 1:0.2-0.

35.

3. The system according to claim 1 or 2, characterized in that, The desulfurization section (41) is provided with an alkaline washing liquid circulation structure for circulating the alkaline washing liquid at the bottom of the desulfurization section (41) to the upper part of the desulfurization section (41); preferably, the bottom of the desulfurization section (41) is provided with an alkaline washing liquid outlet, and the upper side wall of the desulfurization section (41) is provided with an alkaline washing liquid inlet. The alkaline washing liquid circulation structure includes an alkaline washing liquid circulation pipeline and an alkaline washing pump (7) installed thereon. The two ends of the alkaline washing liquid circulation pipeline are respectively connected to the alkaline washing liquid outlet and the alkaline washing liquid inlet. And / or, the upper part of the desulfurization section (41) also has a replenishment inlet for receiving fresh alkali solution; And / or, the lower part of the washing section (42) is provided with a washing water outlet and the upper side wall is provided with a washing water inlet, and the washing water outlet and the washing water inlet are connected by a pipeline and a washing pump (8) installed on the pipeline; And / or, the upper part of the washing section (42) is also provided with a replenishment inlet for receiving demineralized water.

4. The system according to any one of claims 1-3, characterized in that, The lower side wall of the first desulfurization tower (3) is provided with a raw material dry gas inlet, which is connected to the raw material dry gas outlet of the buffer device (2); The upper side wall of the first desulfurization tower (3) is provided with a lean liquid inlet, which is used to receive lean liquid to perform the first desulfurization on the raw material dry gas entering the first desulfurization tower (3); And / or, the bottom of the first desulfurization tower (3) is provided with a rich liquid outlet for discharging the rich liquid obtained from the first desulfurization.

5. The system according to any one of claims 1-4, characterized in that, A first gas-liquid separation tower (5) is also provided between the first desulfurization tower (3) and the second desulfurization tower (4); The lower side wall of the first gas-liquid separation tower (5) is provided with a first desulfurized dry gas inlet, which is connected to the first desulfurized dry gas outlet at the top of the first desulfurization tower (3) to receive and perform first purification on the first desulfurized dry gas. The first gas-liquid separator (5) is provided with a first purified dry gas outlet at the top, and the first purified dry gas outlet is connected to the desulfurization section (41). And / or, the system is further provided with a second gas-liquid separation device (6), the second gas-liquid separation tower (6) being connected to the water washing section (42) to receive and perform second gas-liquid separation on the second desulfurized dry gas from the water washing section (42); And / or, the lower side wall of the second gas-liquid separator (6) is provided with a second desulfurized dry gas inlet, which is connected to the second desulfurized dry gas outlet at the top of the water washing section (42).

6. A method for desulfurization of dry gas, characterized in that, The method is implemented using the system described in any one of claims 1-5, comprising: S1. The raw material dry gas is sent into the cooling equipment (1) to cool down, and the cooled raw material dry gas is obtained. S2. The cooled raw material dry gas is sent to the buffer device (2) for storage and impurity removal to obtain the impurity-removed raw material dry gas. S3. The purified raw material dry gas is sent into the first desulfurization tower (3) for the first desulfurization to obtain the first desulfurized dry gas; S4. The first desulfurized dry gas is sent into the desulfurization section (41) of the second desulfurization tower (4) for second desulfurization to obtain the second desulfurized dry gas. S5. The second desulfurized dry gas is sent into the water washing section (42) through the gas lifting structure (43) for water washing and alkali removal to obtain the second desulfurized dry gas after alkali removal.

7. The method according to claim 6, characterized in that, In step S4, before the first desulfurized dry gas enters the second desulfurization tower (4), it first enters the first gas-liquid separation tower (5) for first purification to obtain the purified first desulfurized dry gas. The purified first desulfurized dry gas enters the desulfurization section (41) of the second desulfurization tower (4) for second desulfurization; And / or, the method further includes step S6: after the second desulfurized dry gas after alkali removal is discharged from the top of the water washing section (42), it is sent to the second gas-liquid separation tower (6) for second purification to obtain the purified second desulfurized dry gas.

8. The method according to claim 6 or 7, characterized in that, The flow rate of the raw material dry gas is 1000-9000 m³ / h. 3 / h, preferably 3000-6000m 3 / h; And / or, the temperature of the raw material dry gas after being cooled by the cooling equipment (1) is 30-50°C, preferably 35-45°C; And / or, in step S2, the conditions for impurity removal include: a gas phase pressure of 0.5-0.8 MPa, preferably 0.6-0.7 MPa; And / or, the flow rate of lean liquor entering the first desulfurization tower (3) is 40-80 m³ / h. 3 / h, preferably 50-70m 3 / h; And / or, in step S3, the conditions for the first desulfurization include: a gas phase pressure of 0.5-0.8 MPa, preferably 0.6-0.7 MPa; and a temperature of 30-50°C, preferably 35-45°C.

9. The method according to any one of claims 6-8, characterized in that, In step S4, the conditions for the second desulfurization include: a gas phase pressure of 0.5-0.8 MPa, preferably 0.6-0.7 MPa; and a temperature of 30-50°C, preferably 35-45°C. And / or, in step S5, the water washing conditions include: a gas phase pressure of 0.5-0.8 MPa, preferably 0.6-0.7 MPa; And / or, in step S4, the conditions for the first purification include: a gas phase pressure of 0.5-0.8 MPa, preferably 0.6-0.7 MPa; and a temperature of 30-50°C, preferably 35-45°C. And / or, in step S6, the conditions for the second purification include: a gas phase pressure of 0.5-0.8 MPa, preferably 0.6-0.7 MPa; and a temperature of 30-50°C, preferably 35-45°C. And / or, the flow rate of the alkaline washing pump (7) is 30-80 m³ / h. 3 / h, preferably 45-55m 3 / h; And / or, the flow rate of the water washing pump (8) is 2-20 m³ / h. 3 / h, preferably 4-8m 3 / h.

10. The method according to any one of claims 6-9, characterized in that, The lean solution is selected from N-methyldiethanolamine and / or diethanolamine; And / or, the alkali in the alkaline solution is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate; And / or, the H2S content in the depleted solution is <0.1 mg / L; And / or, the outlet of the straight pipe section (432) is higher than the liquid level in the washing tank (42).

Images