Venturi-cyclone grading washing system and method for treating high-dust-content synthesis gas

Abstract

The invention discloses a Venturi-cyclone grading washing system and method for high-dust-content synthesis gas treatment, and relates to the technical field of industrial gas purification. The system comprises a first-stage treatment unit and a second-stage treatment unit which are connected in series, and venturi scrubbers and a plurality of straight-flow cyclone separators which are connected in parallel are adopted respectively; the first-stage unit is used for capturing particles with the particle size larger than or equal to 3 microns, and the pressure drop is 45-55 kPa; the second-stage unit is used for intensively trapping fine particles of 0.8-3 microns, and the pressure drop is 70-80 kPa. A spiral ring reverse blocking device is arranged on the inner wall of the cyclone separator and used for restraining liquid drop entrainment and airflow interference. A WC-Co hard alloy layer is overlaid on the surface of the venturi throat pipe, and a system body is made of an S31603 stainless steel material and is subjected to high-precision machining and detection treatment. According to the method, washing and separation are carried out in stages according to the particle size, efficient removal of fine particles is achieved, system operation is stable, energy consumption is low, and the method is suitable for purification requirements of high-dust complex gas sources of coal chemical industry, coking and the like. Tests show that the dust removal efficiency of the system is greater than or equal to 99.5%, the continuous operation period is greater than or equal to 180 days, and the energy consumption is less than or equal to 100 kW.h / 1000 m < 3 >.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of industrial waste gas purification and dust control, and particularly relates to a Venturi-cyclone staged washing system and method for high-dust-containing synthesis gas treatment, which is suitable for the purification of synthesis gas containing high-concentration particulate matter and sticky components (such as coal powder and tar) in the processes of coal chemical industry, coking gas, and hydrogen production, and is particularly suitable for efficient dust removal and gas-liquid separation treatment under complex conditions such as high pressure, high humidity, high corrosion, and easy blocking. BACKGROUND

[0002] In high-temperature and high-humidity industrial scenes such as coal chemical industry, coking, and hydrogen production, synthesis gas often contains a large amount of dust and tar and other sticky components, which must be efficiently removed and purified before entering the subsequent reaction or separation unit. The currently widely used dust-containing gas purification technologies mainly include spray towers, cyclone separators, packed towers, and electrostatic precipitators, but all have different degrees of technical limitations under high load and complex gas source conditions.

[0003] Firstly, the existing wet spray system (as shown in CN108745236A) usually adopts single-stage nozzles or gravity washing mode, and the capture efficiency for fine particles with a particle size less than 1 μm is generally less than 40%. For process requirements that the outlet dust content needs to be less than 30 mg / Nm 3 , it is obviously impossible to meet the precision requirements.

[0004] Secondly, although the conventional cyclone separator (such as CN210206615U) has a simple structure and stable operation, its separation efficiency for particles with a particle size of 0.8 μm and below is only about 30%, which is difficult to meet the high cleanliness condition, especially when tar components exist, the cyclone structure is prone to efficiency decay and liquid droplet entrainment problems.

[0005] Thirdly, in order to improve the efficiency, some systems try to use high pressure drop design (such as single-stage Venturi scrubber with pressure drop ≥120 kPa), but the system energy consumption rises sharply, generally exceeding 120 kW·h / 1000m 3 , which is not conducive to the energy saving and emission reduction target of industrial application. At the same time, most of these systems use packed tower structure (such as the regular packed tower described in CN209406415U) in the tower, which is prone to particle adhesion and packing blockage when facing high-sticky gas, resulting in an actual operation period generally less than 90 days, frequent cleaning and shutdown maintenance are required.

[0006] In summary, the existing technologies are difficult to achieve an effective balance between fine particle capture efficiency, anti-blocking performance, and system energy consumption, and there is an urgent need for a high-performance dust-containing synthesis gas purification device and method with optimized structure, significantly improved efficiency, stable operation, and controllable energy consumption to meet the development needs of current clean utilization of coal-based energy. SUMMARY

[0007] To solve the problems of low fine particle removal efficiency, easy plugging of equipment and high energy consumption in existing dust-containing synthetic gas treatment technologies, the present application provides a Venturi-cyclone staged washing system with reasonable structure, high efficiency, reliable operation and strong adaptability and an application method thereof. The system realizes high-efficiency separation and removal of particles with different particle sizes by optimizing the gas-liquid contact structure, designing the staged pressure drop and configuring the anti-blocking components, and the operation cycle and industrial applicability of the device are significantly improved by strengthening the material selection and process processing. The technical solutions of the present application are described in detail below in combination with multiple embodiments.

[0008] In one possible embodiment, a Venturi-cyclone staged washing system for high-dust-containing synthetic gas treatment is provided, which comprises a first-stage treatment unit and a second-stage treatment unit arranged in series: the first-stage treatment unit is composed of a first-stage Venturi scrubber and at least 2 parallel straight-flow cyclone separators, the design pressure drop of the first-stage Venturi scrubber is 45-55 kPa; the second-stage treatment unit is composed of a second-stage Venturi scrubber and at least 4 parallel straight-flow cyclone separators, the design pressure drop of the second-stage Venturi scrubber is 70-80 kPa; the inner wall of the straight-flow cyclone separator is provided with a spiral ring resistance device, and the axial inclination angle of the spiral ring resistance device is 45°-60°.

[0009] Further, the spiral ring resistance devices are uniformly distributed along the circumference of the inner wall of the cyclone separator, and the center lines of adjacent spiral rings are spaced apart by 30°±2°.

[0010] Preferably, the radial height of the spiral ring resistance device is 12-18 mm, preferably 15 mm.

[0011] Further, the throat surface of the first-stage Venturi scrubber and the second-stage Venturi scrubber is stacked with a WC-Co hard alloy layer with a thickness of 0.8-1.2 mm.

[0012] In one possible embodiment, the collection efficiency of the first-stage treatment unit for particles with a particle size of ≥3 μm is ≥93%, and the collection efficiency of the second-stage treatment unit for particles with a particle size of 0.8-3 μm is ≥84.5%.

[0013] Further, the total dust removal efficiency of the system is ≥99.5%, the continuous operation cycle is ≥180 days, and the system energy consumption is ≤100 kW·h / 1000 m 3 .

[0014] Alternatively, the main body of the system adopts S31603 stainless steel material and is subjected to underwater plasma cutting, mechanical beveling processing (accuracy ±0.5 mm) and 100% post-welding penetration detection (PT) and magnetic powder detection (MT) processing.

[0015] Preferably, the throat diameter of the primary Venturi scrubber is 350-400 mm, and the throat diameter of the secondary Venturi scrubber is 250-300 mm.

[0016] In one possible implementation, a Venturi-cyclone staged scrubbing method for high-dust-containing synthetic gas treatment is provided, using any of the above systems, comprising the following steps:

[0017] (1) Coarse particle staged removal: passing synthetic gas containing 50-200 g / Nm 3 of dust into a primary Venturi scrubber, mixing with scrubbing liquid under a pressure drop of 45-55 kPa, capturing coarse particles with a particle size of 3 μm or more, and then entering parallel straight-flow cyclone separators for gas-liquid separation;

[0018] (2) Fine particle enhanced removal: passing the gas treated in the primary stage into a secondary Venturi scrubber, enhancing the capture of fine particles with a particle size of 0.8-3 μm under a pressure drop of 70-80 kPa, and then entering parallel straight-flow cyclone separators for separation, to obtain purified gas containing 20 mg / Nm 3 of dust or less.

[0019] Optionally, the liquid-gas ratio of the scrubbing liquid to the synthetic gas in step (1) is 3-5 L / m 3 , and the liquid-gas ratio in step (2) is 5-8 L / m 3 .

[0020] Based on the above technical solutions, the Venturi-cyclone staged scrubbing system for high-dust-containing synthetic gas treatment provided by the present application solves the problems of low fine particle capture efficiency, easy equipment clogging, and high system energy consumption in the prior art by combining two Venturi scrubbers with different pressure drops and multiple parallel straight-flow cyclone separators, and by arranging a spiral ring resistance and reverse device on the inner wall of the cyclone separator, thereby significantly improving the dust removal efficiency, operation stability, and energy saving performance.

[0021] Specifically, the staged treatment of coarse particles and fine particles is realized through the series connection of the primary and secondary Venturi scrubbers. The primary scrubber preferentially removes coarse particles with a particle size of more than 3 μm under a relatively low pressure drop, thereby reducing the load of the downstream; and the secondary scrubber focuses on capturing fine particles with a particle size of 0.8-3 μm under a higher pressure drop, thereby effectively breaking through the bottleneck of insufficient treatment capacity for fine particles in traditional systems and improving the overall dust removal efficiency of the system to more than 99.5%.

[0022] The spiral ring resistance and reverse device arranged in the cyclone separator enhances the stability of the liquid-containing gas flow in the separator through reasonable inclination and circumferential arrangement, effectively suppresses the liquid droplet climbing and secondary entrainment phenomenon, and prolongs the fault-free operation period of the equipment to more than 180 days, thereby significantly reducing the maintenance frequency.

[0023] In addition, the Venturi scrubber throat surface is stacked with a WC-Co hard alloy layer, which greatly improves the erosion resistance and ensures the structural stability and long-term operation under the condition of high dust content and high-speed airflow impact. Combined with the S31603 stainless steel main structure and high-standard welding and detection process, the system service life of more than 15 years is realized.

[0024] The present application also optimizes the operation parameters such as liquid-gas ratio and system energy consumption, ensures that the overall energy consumption is controlled at 100kW·h / 1000m 3 The following meets the requirements of energy saving and carbon reduction, adapts to the current engineering needs of high dust and high humidity conditions such as coal chemical industry, hydrogen energy preparation, and coking tail gas treatment, and has good industrial application prospect and promotion value. DETAILED DESCRIPTION

[0025] In order to better understand the structural composition, functional characteristics and practical application effects of the present application, the Venturi-cyclone grading washing system and its application method proposed by the present application are described in detail below in combination with specific working conditions and system configurations. The structural parameters, operating conditions and performance data involved in the embodiments are all derived from actual engineering verification or functional testing, and are used to fully demonstrate the implementability and technical advantages of the present application.

[0026] The Venturi-cyclone grading washing system and method proposed by the present application are described in detail below in combination with embodiments, but the present application is not limited to the following embodiments, and equivalent modifications or functional replacements made by those skilled in the art without departing from the principles of the present application should be considered as falling within the scope of the present application.

[0027] Example 1:

[0028] I. System structure and grading design

[0029] In one specific embodiment of the present application, the system includes a primary treatment unit and a secondary treatment unit, and the two units are arranged in series along the airflow direction to achieve efficient removal of particles of different particle sizes.

[0030] 1. Primary treatment unit

[0031] The primary treatment unit is composed of one Venturi scrubber and at least two parallelly arranged straight-flow cyclone separators, and the main target is to efficiently remove coarse particles with a particle size of 3μm or more:

[0032] Venturi scrubber parameters: throat diameter 380 mm, design gas inlet velocity 85 m / s, corresponding pressure drop control at 50±5 kPa; internal surface build-up 1.0 mm thick WC-Co hard alloy layer, with good anti-erosion ability, thickness loss less than 0.01 mm after 1200 hours of wear test.

[0033] Cyclone separator structure: inner diameter 1200 mm, each processing gas volume 15000 Nm 3 / h. The inner wall is uniformly provided with a spiral ring resistance device along the circumference, the inclination angle of the spiral ring is 50°, the radial height is 15 mm, and the interval is 30°±2°.

[0034] Operation effect: the actual measurement of the particle size ≥3 μm particle capture efficiency is 94.2%, the gas-liquid separation is stable, and there is no obvious secondary entrainment.

[0035] 2. Secondary treatment unit

[0036] For further removal of fine particles with particle size of 0.8-3 μm, it is the key component of system precision control:

[0037] Venturi scrubber parameters: throat diameter 280 mm, inlet gas velocity increased to 120 m / s, actual running pressure drop 75±5 kPa. The internal surface is also build-up with 0.8-1.2 mm WC-Co alloy layer to ensure the wear resistance under high pressure scouring.

[0038] Cyclone separator configuration: 4 units in parallel, inner diameter 800 mm, single unit processing gas volume about 8000 Nm 3 / h, internal spiral ring device with inclination angle of 55°. Compared with the first cyclone separator, its structure is more compact, and the cyclone intensity and liquid film stability are optimized.

[0039] Operation effect: the actual measurement of fine particle capture efficiency of 0.8-3 μm is 85.7%, and the outlet dust content ≤20 mg / Nm 3 , meeting the requirements of many clean gas processes.

[0040] II. System materials and manufacturing process

[0041] Main material: S31603 stainless steel plate is used for manufacturing, which has good acid resistance, wear resistance and welding adaptability, especially suitable for high temperature gas environment containing tar and corrosive substances.

[0042] Manufacturing process flow:

[0043] Underwater plasma cutting (stable seam, neat edge);

[0044] Mechanical beveling, precision control within ±0.5 mm;

[0045] 100% of the welds are subjected to PT (penetrant testing) and MT (magnetic particle testing) after welding to ensure no cracks and no slag inclusion defects, ensuring system airtightness and long-term stability.

[0046] Life assessment: Through accelerated corrosion and abrasion experiments, the service life of the system is not less than 15 years.

[0047] III. Method steps and operating parameters

[0048] The matching washing method includes the following steps:

[0049] 1. Step one: coarse particle classification removal

[0050] The dust content of the high-temperature synthesis gas is 50-200 g / Nm 3 The high-temperature synthesis gas first enters the first-stage Venturi scrubber, and high-speed turbulent mixing occurs with the sprayed droplets of the washing liquid, forming a large number of gas-liquid interfaces under the action of a pressure drop of 45-55 kPa. Coarse particles are captured by the droplets to form liquid films, which enter the cyclone separator with the gas. The spiral ring structure guides the liquid film downward, effectively separating the droplets from the gas, and controlling the secondary entrainment rate to be less than 0.5%.

[0051] 2. Step two: fine particle intensive removal

[0052] The gas after the first-stage treatment enters the second-stage Venturi scrubber, and the pressure drop is controlled at 70-80 kPa, achieving full contact with fine particles through high-pressure atomization. Fine particles combine with droplets to form high-density droplet clusters, which then enter four cyclone separators for separation, achieving efficient removal of fine particles and significantly improving gas purification.

[0053] 3. Liquid-gas ratio optimization

[0054] To ensure the balance between capture efficiency and energy consumption, the liquid-gas ratio of the first-stage washing liquid and gas is controlled at 3-5 L / m 3 , and the second-stage is 5-8 L / m 3 . It is found that under the condition of a liquid-gas ratio of 4.8 L / m 3 (first stage) + 7.5 L / m 3 (second stage), both efficiency and pressure loss can be maintained, and the liquid load is not too high.

[0055] IV. System comprehensive performance and applicability

[0056] The measured data from the Yankuang Lunan Coal-to-Hydrogen Project show that the system has the following performance indicators:

[0057]

[0058]

[0059] In summary, the washing system and process method proposed by the present application realize innovation breakthroughs in structural design, efficiency control, anti-blocking measures, and manufacturing process, and are particularly suitable for complex working conditions such as coal gasification, methanol hydrogen production, and coke oven gas purification, and have strong engineering promotion prospects.

[0060] Example 2:

[0061] This example aims to verify the operating performance of the Venturi-cyclone classification washing system under the regulation of different key structural parameters, especially the influence of the spiral ring resistance reversing device parameters and the liquid-gas ratio on the dust removal efficiency and energy consumption.

[0062] Under this implementation condition, the processing object is still coal chemical industry high-dust synthetic gas, with dust content of 185 g / Nm 3 , temperature 220℃, and operating pressure 4.2MPa. The device structure and parameter configuration are as follows:

[0063] The throat diameter of the primary Venturi scrubber is 370mm, and the operating pressure drop is maintained at 50kPa;

[0064] The throat diameter of the secondary Venturi scrubber is 270mm, and the pressure drop is maintained at 75kPa;

[0065] In the cyclone separator, the radial height of the spiral ring resistance reversing device is optimized to 14.8mm, and the circumferential spacing is 30.5°;

[0066] The primary liquid-gas ratio is set to 3.5L / m 3 , and the secondary liquid-gas ratio is 5.2L / m 3 ;

[0067] The remaining structural parameters are consistent with those of Example 1.

[0068] The running test results show that:

[0069] Index item Optimized configuration measured value Example 1 comparison value 0.8 μm particle removal efficiency 86.3％ 85.7％ System total dust removal efficiency 99.58％ 99.54％ System energy consumption 96.2 kW-h / 1000 m 3 ]] 98.0 kW-h / 1000 m 3 ]] Droplet entrainment (cyclone outlet) 0.42％ 0.48％

[0070] This example shows that optimizing the geometric parameters of the spiral ring and the liquid-gas ratio configuration can further improve the capture efficiency of fine particles while maintaining stable system energy consumption, effectively improving the stability of the liquid film and the entrainment rate. At the same time, this scheme demonstrates the good parameter adjustment adaptability and performance stability of the system under different operating conditions, and has strong engineering adjustability and promotion potential.

[0071] Example 3:

[0072] This example is used to verify the running stability and dust removal boundary performance of the system under extreme high load and abnormal working conditions, to ensure the adaptability and reliability of the technical solution of the present application.

[0073] The test gas source is synthetic gas discharged from a coking device, with the following working condition characteristics:

[0074] Dust content peak is 253 g / Nm 3 ;

[0075] Tar content 4.8%, much higher than conventional coal gas (1.5%);

[0076] Flow rate fluctuation frequently, inlet fluctuation range ± 15%;

[0077] The running cycle is set to 180 days without interruption (simulated limit continuous operation).

[0078] System key configuration:

[0079] The pressure drop of the primary Venturi scrubber is raised to 55 kPa;

[0080] The pressure drop of the secondary Venturi scrubber is adjusted to 80 kPa;

[0081] The liquid-gas ratio of the primary / secondary is adjusted to 4.8 L / m 3 and 7.5 L / m 3 ;

[0082] All cyclone separators are provided with a spiral ring resistance structure with an inclination angle of 60°;

[0083] The detection system continuously monitors the pressure drop, dust content, flow rate and running stability.

[0084] The test results are as follows:

[0085]

[0086] This example shows that even under the extreme conditions of high dust content, high tar content and pressure drop fluctuation, the system can still maintain a stable running state and effectively capture fine particles without problems such as plugging, liquid droplet entrainment rising or running interruption, fully demonstrating the adaptability and structural robustness of the system under extreme conditions.

[0087] In summary, the present application provides a compact, stable, high-efficiency and adaptable Venturi-cyclone grading scrubbing system and its application method, which can effectively solve the problems of low fine particle capture efficiency, frequent equipment plugging and high system energy consumption in the prior art, and is particularly suitable for continuous purification treatment of high-dust, tar-containing and complex gas sources in coal chemical industry, coking, hydrogen production and other fields. The system has good scalability and industrial promotion value, and can provide reliable protection for high-end clean gas supply systems.

[0088] It should be understood that the above embodiments are only used to illustrate the technical principles and specific application solutions of the present application, and are not intended to limit the scope of protection of the present application. Equivalent changes or improvements made by those of ordinary skill in the art without departing from the basic concept of the present application shall fall within the scope of protection of the present application. The scope of protection of the present application is defined by the appended claims.

Claims

1. A venturi-cyclone staged scrubbing system for high dust laden syngas treatment, characterized by, The system comprises a primary treatment unit and a secondary treatment unit arranged in series. The primary treatment unit comprises a primary Venturi scrubber and at least two parallel straight-flow cyclone separators, and the design pressure drop of the primary Venturi scrubber is 45-55 kPa. The secondary treatment unit comprises a secondary Venturi scrubber and at least four parallel straight-flow cyclone separators, and the design pressure drop of the secondary Venturi scrubber is 70-80 kPa. The inner wall of the straight-flow cyclone separator is provided with a helical ring resistance device, and the axial inclination angle of the helical ring resistance device is 45-60°.

2. The system of claim 1, wherein, The helical ring resistance devices are uniformly distributed along the inner wall of the cyclone separator in the circumferential direction, and the center lines of adjacent helical rings are spaced apart by 30°±2°.

3. The system of claim 1 or 2, wherein, The radial height of the helical ring resistance device is 12-18 mm, preferably 15 mm.

4. The system of claim 1, wherein, The throat surface of the primary Venturi scrubber and the secondary Venturi scrubber is stacked with a WC-Co hard alloy layer with a thickness of 0.8-1.2 mm.

5. The system of claim 1, wherein, The collection efficiency of the primary treatment unit for particles with a particle size of ≥3 μm is ≥93%, and the collection efficiency of the secondary treatment unit for particles with a particle size of 0.8-3 μm is ≥84.5%.

6. The system of claim 1, wherein, The total dust removal efficiency of the system is greater than or equal to 99.5%, the continuous operation period is greater than or equal to 180 days, and the system energy consumption is less than or equal to 100 kW·h / 1000m 3 .

7. The system of claim 1, wherein, The main body of the system is made of S31603 stainless steel and is subjected to underwater plasma cutting, mechanical beveling (precision ±0.5 mm), and 100% post-welding penetration detection (PT) and magnetic powder detection (MT).

8. The system of claim 1, wherein, The throat diameter of the primary Venturi scrubber is 350-400 mm, and the throat diameter of the secondary Venturi scrubber is 250-300 mm.

9. A venturi-cyclone staged scrubbing process for the treatment of high dust laden synthesis gas, characterized in that, The system of any one of claims 1-8 comprises the following steps: (1) Coarse particle removal: The synthetic gas with dust content of 50-200 g / Nm 3 was introduced into a first stage Venturi scrubber, mixed with the scrubbing liquid under a pressure drop of 45-55 kPa, and the coarse particles with a particle size of ≥3 μm were captured, and then the gas stream entered the parallel straight-flow cyclone separators for gas-liquid separation; (2) Fine particle strengthened removal: the gas after the first stage treatment enters the second stage venturi scrubber to strengthen the capture of 0.8-3 μm fine particles under the condition of 70-80 kPa pressure drop, and then enters the parallel straight-flow cyclone separator for separation, to obtain the purified gas with dust content ≤20 mg / Nm 3 ​ 10. The method of claim 9, wherein, The liquid-gas ratio of the washing liquid to the synthesis gas in step (1) is 3-5 L / m 3 The liquid-gas ratio in step (2) is 5-8 L / m 3 .

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