A crude gas prewashing device

Abstract

The application relates to the technical field of gas flow bed coal gasification production processes, and provides a crude coal gas pre-washing device which comprises a water washing tower, a crude coal gas pipe is arranged in the middle of the water washing tower, an extension pipe is connected to the crude coal gas pipe in the water washing tower, the extension pipe extends to below the liquid level, a plurality of gas distribution holes are arranged on the extension pipe, and the gas distribution holes are located below the liquid level. The crude coal gas is introduced into black water through the extension pipe for washing, meanwhile, the crude coal gas is divided into a plurality of small gas flows through the gas distribution holes, so that the crude coal gas is fully mixed with the black water, the washing effect of the crude coal gas is ensured, the water washing tower tray load is reduced, the tower tray is prevented from being scaled and the synthetic gas is prevented from being mixed with ash and water, and the service life is prolonged. Meanwhile, the main road gas volume of the extension pipe can be reduced, the pump cavitation caused by the bottom black water pump suction bubbles is reduced, the pump outlet flow low interlock system shutdown and other abnormal accidents are avoided. The scheme has few structures, does not change the existing water washing tower, has low cost and good safety effect.

Description

Technical Field

[0001] This application belongs to the technical field of fluidized bed coal gasification production process, and more specifically, it relates to a crude coal gas pre-washing device. Background Technology

[0002] After exiting the gasifier's quench chamber, the crude coal gas enters the primary mixer, where it mixes with high-pressure ash water from the high-pressure flash distillation tower's hot water chamber (pressurized by a pump). The mixture then enters the cyclone separator, where most of the solids are separated by cyclone separation. The crude coal gas then enters the secondary mixer, where it mixes again with the high-pressure ash water from the high-pressure flash distillation tower's hot water chamber and enters from the middle of the water washing tower. Figure 1 As shown, the crude gas extends from the crude gas pipe to above the liquid surface in the bottom of the washing tower. The crude gas then enters two layers of solid valve trays for high-pressure ash water coarse washing, and further upwards into three layers of bubble cap trays for fine washing with boiler water or high-pressure condensate. This process reduces the solid content in the crude gas to less than 1 mg / L, meeting downstream process requirements. Above the liquid surface in the bottom of the washing tower, the crude gas passes through two types of five trays, contacting the high-pressure ash water and high-pressure process condensate (and / or boiler water) heated by the high-flash evaporation hot water tower. This efficient mass and heat transfer lowers the crude gas temperature while simultaneously washing away solid particles and reducing the concentration of corrosive compounds such as H2S and Cl ions. After passing through a demister at the top of the washing tower to remove mist and fine ash, the crude gas is sent to the purification unit for further treatment.

[0003] During the initial startup phase of the gasification unit, just 20 days after commissioning, the water scrubbing tower experienced severe water carryover. The amount of high-pressure condensate returning downstream exceeded 150% of the design capacity, filling the condensate tank and posing a risk of water carryover to the catalyst in the shift converter, leading to catalyst failure. The water scrubbing tower experienced large fluctuations in liquid level and high tray pressure differentials, with scrubbing water being carried downstream by the gas. Poor control could result in pressure surges from empty tanks, necessitating a 60% reduction in load to maintain operation. During maintenance, access through the manhole revealed severe blockages in all five trays. Sampling and analysis of the blockage material showed that it comprised mostly combustibles, consisting of unreacted carbonaceous substances.

[0004] After the crude coal gas and slag from the gasifier reaction chamber are quenched together in the quench chamber, the slag descends by gravity to the lock hopper and is discharged. The crude coal gas carrying coarse particles exits the quench chamber, is mixed with a small amount of high-pressure ash water for humidification, and then separated by a cyclone separator. After being mixed with a small amount of high-pressure ash water again, it enters the water washing tower. Although it comes into contact with water three times, given the severe water carryover condition caused by the clogging of the water washing tower trays, the effect of relying solely on the washing water on the trays to remove the ash particles entrained in the crude coal gas is limited and cannot meet the operating requirements. It may even exacerbate scaling on the trays. Severe tray clogging leads to serious water carryover, affecting normal operation and safe production. Utility Model Content

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide a crude gas pre-washing device to remove solid particles entrained in crude gas, thereby solving the technical problems of heavy washing load, scaling and clogging of the tower tray, and short operating cycle of the water washing tower.

[0006] To achieve the above objectives, the technical solution adopted in this application is: to provide a crude gas pre-washing device, comprising: a water washing tower, wherein a crude gas pipe is provided in the middle of the water washing tower, an extension pipe is connected to the crude gas pipe inside the water washing tower, the extension pipe extends below the liquid surface, and multiple gas distribution holes are provided on the extension pipe, the gas distribution holes being located below the liquid surface.

[0007] In one embodiment, the end of the extension tube away from the coarse gas pipe is provided with a ring of bubble-breaking teeth.

[0008] In one embodiment, a support member is provided between the extension pipe and the water washing tower, with one end of the support member fixed to the extension pipe and the other end fixed to the inner wall of the water washing tower.

[0009] In one embodiment, at least three supports are provided at equal arc intervals, and the included angle between the support and the axis of the extension tube is 40°-90°.

[0010] In one embodiment, the angle between the support member and the axis of the extension tube is 60°.

[0011] In one embodiment, the support member is provided in at least two layers along the axis of the extension tube.

[0012] In one embodiment, the distribution holes are arranged in 55-65 circles along the axis of the extension tube, with 45-52 gas distribution holes at equal arc intervals in each circle, and the diameter of the gas distribution holes is 20-25 mm.

[0013] In one embodiment, the gas distribution hole is provided at one end of the extension pipe away from the coarse gas pipe, extending to 2 / 5 of its length.

[0014] In one embodiment, the coarse gas pipe is welded to the extension pipe.

[0015] The beneficial effects of the crude gas pre-washing device provided in this application are as follows: Compared with the prior art, the crude gas pre-washing device of this application introduces crude gas into black water for washing through an extension pipe, and simultaneously uses gas distribution holes to divide the crude gas into multiple small airflows, ensuring that the crude gas is fully mixed with the black water, guaranteeing the washing effect of the crude gas, reducing the load on the water washing tower trays, avoiding scaling on the trays and ash and water carryover in the syngas, and extending the service life. It also reduces the gas volume in the main pipeline of the extension pipe, reducing the risk of pump cavitation caused by air bubbles being sucked into the bottom black water pump, and preventing abnormal accidents such as pump outlet flow rate low interlock system shutdown. This solution adds little structure, does not require changes to the existing water washing tower, and is low in cost and has good safety performance. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a simplified schematic diagram of a water washing tower used in the prior art for washing crude coal gas.

[0018] Figure 2 A simplified structural diagram of the crude gas pre-washing device provided in the embodiments of this application.

[0019] The following are the labeling elements in the figure:

[0020] 1. Water washing tower; 2. Coarse gas pipe; 3. Extension pipe; 4. Gas distribution hole; 5. Bubble-breaking teeth; 6. Support component; 7. Bubble-breaking filter plate. Detailed Implementation

[0021] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0022] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0023] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0025] like Figure 2 As shown, a crude gas pre-washing device provided in this application embodiment will now be described. This crude gas pre-washing device includes: a water washing tower 1, which is the original structure. A crude gas pipe 2 is located in the middle of the water washing tower 1. The improvement in this embodiment is that an extension pipe 3 is connected to the crude gas pipe 2 inside the water washing tower 1. The extension pipe 3 extends below the liquid surface and has multiple gas distribution holes 4 located below the liquid surface. Crude gas is passed into the black water through the extension pipe 3 for washing. Simultaneously, the gas distribution holes 4 divide the crude gas into multiple small airflows, ensuring thorough mixing of the crude gas with the black water, guaranteeing the washing effect on the crude gas, reducing the load on the trays of the water washing tower 1, preventing scaling on the trays and ash and water contamination in the syngas, and extending the service life. It also reduces the main gas flow in the extension pipe, reducing the risk of air bubbles being sucked into the bottom black water pump (connected to the pump inlet) causing pump cavitation, low pump outlet flow, and other abnormal accidents such as system shutdown. This solution requires minimal structural additions, does not alter the existing water washing tower 1, and is cost-effective and safe.

[0026] In this embodiment, the end of the extension pipe 3 away from the coarse gas pipe 2 is provided with a ring of bubble-breaking teeth 5. The bubble-breaking teeth 5 are used to break up large bubbles and prevent large bubbles from carrying solid particles upward.

[0027] In this embodiment, the coarse gas pipe 2 and the extension pipe 3 are made of the same stainless steel and are welded together. To ensure the secure installation of the extension pipe 3, a support member 6 is provided between the extension pipe 3 and the water washing tower 1. One end of the support member 6 is fixed to the extension pipe 3, and the other end is fixed to the inner wall of the water washing tower 1. Specifically, at least three support members 6 are arranged at equal arc intervals, such as 3, 4, 5, or 6. The included angle between the support member 6 and the axis of the extension pipe 3 is 40°-90°, preferably 60°, which provides good support. In this embodiment, L-shaped steel plates are welded to both the extension pipe 3 and the water washing tower 1, and both ends of the support member 6 are fixedly connected to the L-shaped steel plates by bolts. Preferably, the support member 6 is arranged in at least two layers along the axis of the extension pipe 3 to ensure good support for the extension pipe 3.

[0028] In this embodiment, the extension pipe 3 extends to a depth of 50% of the normal black water level in the water washing tower 1, meaning the extension pipe 3 is 5m long, ensuring a certain distance from the pump inlet. The specific length of the extension pipe 3 is selected according to different models of water washing towers. In one specific embodiment, the gas distribution holes 4 are arranged in 55-65 turns along the axis of the extension pipe 3, with 45-52 gas distribution holes 4 at equal arc intervals in each turn, a hole spacing of 25-30mm, and a hole diameter of 20-25mm. A gas distribution hole 4 is provided at the end of the extension pipe 3 furthest from the crude gas pipe 2, up to 2 / 5 of its length. That is, the gas distribution hole 4 is provided within 2 meters of the end of the extension pipe 3. This ensures that part of the crude gas entering the water washing tower 1 can fully transfer mass and heat with the black water through the gas distribution hole 4, effectively removing solid particles entrained in the gas. At the same time, the crude gas will not all pass through the extension pipe 3 directly to the end of the extension pipe 3, avoiding the crude gas from entering the black water pump inlet which is not far away, causing cavitation of the black water pump.

[0029] In this embodiment, the crude gas pre-washing device developed water carryover after more than 20 days of operation. However, after 159 days of operation without maintenance, the water carryover phenomenon in the crude gas did not recur. The water washing tower 1 operated normally, including normal tray pressure and black water pump operation. The operating load increased from the initial 60% to an average of over 90%, with a maximum operating load of 102%. After 159 days of operation, inspection revealed no obvious scale buildup on the surface and inside of the solid valves and bubble cap trays of water washing tower 1, no deformation of the solid valve tray supports, and a clean demister. This device achieves a pre-washing effect, significantly reducing the tray load of water washing tower 1 and preventing abnormal operating conditions such as high tray pressure differential and water / ash carryover in the crude gas caused by tray scaling and blockage.

[0030] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A crude gas pre-washing device, comprising: A water washing tower (1) is provided with a coarse gas pipe (2) in the middle of the water washing tower (1). The feature is that an extension pipe (3) is connected to the coarse gas pipe (2) inside the water washing tower (1). The extension pipe (3) extends to below the liquid surface. The extension pipe (3) is provided with multiple gas distribution holes (4). The gas distribution holes (4) are located below the liquid surface.

2. The crude gas pre-washing device as described in claim 1, characterized in that: The extension pipe (3) has a ring of bubble-breaking teeth (5) at the end away from the coarse gas pipe (2).

3. The crude gas pre-washing device as described in claim 2, characterized in that: A support member (6) is provided between the extension pipe (3) and the water washing tower (1). One end of the support member (6) is fixed on the extension pipe (3), and the other end is fixed on the inner wall of the water washing tower (1).

4. The crude gas pre-washing device as described in claim 3, characterized in that: At least three support members (6) are arranged at equal arc intervals, and the included angle between the axis of the support member (6) and the axis of the extension tube (3) is 40°-90°.

5. The crude gas pre-washing device as described in claim 4, characterized in that: The included angle between the axis of the support member (6) and the axis of the extension tube (3) is 60°.

6. The crude gas pre-washing device as described in claim 5, characterized in that: The support member (6) is arranged in at least two layers along the axis of the extension tube (3).

7. The crude gas pre-washing device as described in claim 6, characterized in that: The distribution holes are arranged in 55-65 circles along the axis of the extension tube (3), and each circle has 45-52 gas distribution holes (4) at equal arc intervals. The diameter of the gas distribution holes (4) is 20-25 mm.

8. The crude gas pre-washing device as described in claim 7, characterized in that: The gas distribution hole (4) is provided at one end of the extension pipe (3) away from the coarse gas pipe (2) up to 2 / 5 of its length.

9. The crude gas pre-washing device according to any one of claims 1-8, characterized in that: The coarse gas pipe (2) is welded to the extension pipe (3).

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