Low-temperature methanol washing tail gas purification device and low-temperature methanol washing combination system

Abstract

The utility model relates to a low-temperature methanol washing tail gas purification device and a low-temperature methanol washing combination system. The plurality of sections of fillers are arranged in the water washing tower at intervals along the height direction; the low-temperature methanol washing tail gas pipeline is connected with the lower part of the water washing tower and is positioned below the filler; the regenerated wastewater pipeline and the demineralized water pipeline of the methanol water rectifying tower are arranged at the upper part of the water washing tower and are positioned above the filler. According to the low-temperature methanol washing tail gas treatment device, the emission of methanol in the low-temperature methanol washing tail gas is less than 50mg / m < 3 >, the use amount of demineralized water is reduced, the emission of methanol wastewater is avoided, and the pressure of a sewage treatment unit is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of coal chemical industry and relates to a low-temperature methanol washing tail gas purification device and a low-temperature methanol washing combined system. Background Art

[0002] Low-temperature methanol washing gas purification technology has been widely used in the field of gas purification due to its high degree of purification, high degree of automation and low process energy consumption. It is also the preferred process for gas purification in the coal chemical industry. During the low-temperature methanol washing gas purification process, while methanol absorbs and removes acidic gases such as carbon dioxide and hydrogen sulfide, a portion of methanol will be discharged into the atmosphere with the tail gas, causing environmental pollution and methanol loss.

[0003] Currently, the common low-temperature methanol washing tail gas treatment processes mainly include combustion method (direct combustion method, heat storage combustion method, catalytic combustion method) and absorption method (alkaline washing method, water washing method).

[0004] Table 1 Common low-temperature methanol tail gas washing processes

[0005]

[0006] Coal chemical plants generally use water-coal slurry gasification as the leader. The principle of the low-temperature methanol washing process is similar to the physical separation process, and no hydrocarbon generation reaction will occur. Methanol, methane, ethane, ethylene, acetaldehyde, propane, propylene, butene and other substances that can be analyzed in the tail gas become the main components of the non-methane total hydrocarbons in the tail gas. The content is mainly affected by the type of gasification raw coal and the gasification temperature control, and varies within a large range. Therefore, the non-methane total hydrocarbons in the low-temperature methanol washing tail gas of the synthetic ammonia plant need to be controlled from the source.

[0007] For low-concentration methanol in low-temperature methanol washing tail gas, the water washing method is the most economical and effective. The existing water washing method mostly uses desalted water as washing water, and the methanol-containing wastewater produced after purifying the tail gas also brings certain challenges to the subsequent sewage treatment unit. At the same time, the CO2 in the purified tail gas after water washing is not considered for the production of food-grade or electronic-grade CO2 products, and carbon emission reduction and resource utilization of tail gas components are not achieved, which is not in line with the development trend of the coal chemical industry. Utility Model Content

[0008] The purpose of the utility model is to provide a low-temperature methanol washing tail gas purification device, taking into account the development trend of carbon emission reduction in the coal chemical industry, and combining with the low-temperature methanol washing system to achieve methanol emissions in the low-temperature methanol washing tail gas less than 50mg / m 3 At the same time, it reduces the use of desalted water, avoids the discharge of methanol wastewater, and reduces the pressure on the sewage treatment unit.

[0009] The purpose of the utility model can be achieved through the following technical solutions:

[0010] One of the technical solutions of the utility model provides a low-temperature methanol tail gas purification device, comprising:

[0011] Water scrubber;

[0012] Several sections of packing are arranged in the water washing tower at intervals along the height direction;

[0013] A low-temperature methanol tail gas washing pipeline connected to the lower part of the water washing tower and located below the packing;

[0014] And a methanol-water distillation tower regeneration wastewater pipeline and a desalted water pipeline installed on the upper part of the water washing tower and located above the filler.

[0015] Furthermore, the bottom of the water washing tower is also connected to a sewage middle section return pipeline, which is also returned and connected between the two sections of the fillers. In addition, a sewage middle section loop pipeline is also provided with a sewage discharge port, which is also returned and connected to the methanol water distillation tower.

[0016] Furthermore, the port of the sewage middle section return pipeline extending into the water washing tower is also connected to a liquid distributor.

[0017] Furthermore, a sewage pump is arranged on the sewage middle section return pipeline.

[0018] Furthermore, a gas distributor is installed at the port where the low-temperature methanol-washed tail gas pipeline extends into the water-washing tower.

[0019] Furthermore, a wire mesh demister is provided at the top of the water washing tower.

[0020] Furthermore, a tail gas outlet is provided at the top of the water washing tower, and the tail gas outlet is also connected to a tail gas recycling pipeline.

[0021] Furthermore, a safety valve is provided at the top of the water washing tower, and the outlet of the safety valve is also connected to the flare pipe network.

[0022] Furthermore, the ports where the methanol-water distillation tower regeneration wastewater pipeline and the desalted water pipeline are respectively connected to the water washing tower are also provided with a liquid distributor.

[0023] Furthermore, the desalted water pipeline is located above the methanol water distillation tower regeneration waste water pipeline.

[0024] Compared with the prior art, the utility model has the following advantages:

[0025] (1) Install exhaust induced draft fans to ensure the pressure requirements of the purified exhaust gas destination, which can be further reused to produce CO2 products.

[0026] (2) The wastewater from the water washing tower is discharged to the methanol water distillation tower for treatment, thereby avoiding the discharge of wastewater to the sewage treatment unit and affecting the treatment capacity and acceptance index of the sewage treatment unit.

[0027] (3) Sharing the existing methanol-water distillation tower of the low-temperature methanol washing system can save investment and space.

[0028] (4) The wastewater regenerated from the methanol-water distillation tower is used as washing water to partially replace desalted water, thereby saving the amount of desalted water.

[0029] (5) Part of the wastewater at the bottom of the water washing tower is returned to the water washing tower for reuse, which can enhance gas-liquid contact and mass transfer and save desalted water consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the low-temperature methanol tail gas purification device of the utility model;

[0031] Description of the markings in the figure:

[0032] 1- exhaust gas induced draft fan; 2- water washing tower; 3- sewage pump; 4- safety valve; 5- exhaust gas recycling pipeline; 6- methanol water distillation tower regeneration wastewater pipeline; 7- demineralized water pipeline; 8- sewage middle section reflux pipeline; 9- flare pipe network; 10- wire mesh demister. DETAILED DESCRIPTION

[0033] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0034] In the following implementation manners or examples, unless otherwise specified, functional components or structures are conventional components or conventional structures used in the art to achieve corresponding functions.

[0035] To achieve methanol emission in low temperature methanol washing tail gas less than 50mg / m 3 At the same time, the use of desalted water is reduced, the discharge of methanol wastewater is avoided, and the pressure of the sewage treatment unit is reduced. The utility model provides a low-temperature methanol washing tail gas purification device, and its structure can be seen in Figure 1 As shown, including:

[0036] Water washing tower 2;

[0037] Several sections of fillers are arranged in the water washing tower 2 at intervals along the height direction;

[0038] A low-temperature methanol tail gas washing pipeline connected to the lower part of the water washing tower 2 and located below the packing;

[0039] A methanol-water distillation tower regeneration wastewater pipeline 6 and a demineralized water pipeline 7 installed on the upper part of the water scrubber 2 and located above the packing;

[0040] And a wire mesh demister 10 arranged on the top of the water washing tower 2.

[0041] In some specific embodiments, the bottom of the water washing tower 2 is also connected to a sewage middle section reflux pipeline 8, and the sewage middle section reflux pipeline 8 is also returned and connected between the two sections of the fillers. In addition, a sewage outlet is also provided on the sewage middle section loop pipeline, and the sewage outlet is also returned and connected to the methanol water distillation tower. In this way, part of the sewage at the bottom of the water washing tower 2 can be sent to the methanol water distillation tower for recycling and treatment, and part of it can be returned to the water washing tower 2 as the middle section reflux.

[0042] Preferably, the filler is arranged into two or more sections, and the sections are arranged at equal intervals.

[0043] In a more specific embodiment, the port of the sewage middle section return pipeline 8 extending into the water washing tower 2 is also connected to a liquid distributor. The liquid distributor can be a device commonly used in the art that can achieve the liquid distribution function, and its specific structure does not belong to the innovative protection point of the utility model, and the same is true for the following gas distributor.

[0044] In a more specific implementation, a sewage pump 3 is also arranged on the sewage middle return pipeline 8 .

[0045] In some specific embodiments, a gas distributor is also installed at the port where the low-temperature methanol-washed tail gas pipeline extends into the water-washing tower 2 .

[0046] In some specific embodiments, a wire mesh demister 10 is further provided at the top of the water washing tower 2 .

[0047] In some specific embodiments, the top of the water washing tower 2 is also provided with an exhaust gas outlet, which is also connected to the exhaust gas recycling pipeline 5. This can facilitate the subsequent recycling of CO2 in the pressurized exhaust gas to produce food grade or electronic grade CO2 products.

[0048] In some specific implementations, a safety valve 4 is further provided at the top of the water scrubber 2 , and an outlet of the safety valve 4 is also connected to a flare pipe network 9 .

[0049] In some specific embodiments, the methanol-water distillation tower regeneration wastewater pipeline 6 and the demineralized water pipeline 7 are respectively connected to the ports in the water washing tower 2 and are also provided with a liquid distributor.

[0050] In some specific embodiments, the desalted water pipeline 7 is located above the methanol-water distillation tower regeneration wastewater pipeline 6 .

[0051] In the above-mentioned embodiments, when comparing the height positions of the various components, based on their positions in the water washing tower 2, for example, if the inlet position of the desalted water pipeline 7 in the water washing tower 2 is higher than the inlet position of the methanol water distillation tower regeneration waste water pipeline 6, then the desalted water pipeline 7 is considered to be higher than the methanol water distillation tower regeneration waste water pipeline 6.

[0052] The above embodiments may be implemented individually or in any combination of two or more.

[0053] The above implementation is described in more detail below in conjunction with specific examples.

[0054] Embodiment 1:

[0055] like Figure 1 As shown, this embodiment provides a novel low-temperature methanol-washed tail gas purification device, including a tail gas induced draft fan 1, a water washing tower 2, a sewage pump 3, a safety valve 4, and a tail gas recycling pipeline 5. The inlet end of the tail gas induced draft fan 1 is connected to the low-temperature methanol-washed tail gas, and the outlet end is connected to the lower part of the water washing tower 2, the upper part of the water washing tower 2 is connected to the desalted water pipeline 7, the upper part of the water washing tower 2 is connected to the methanol-water distillation tower regeneration wastewater pipeline 6, the top of the water washing tower 2 is connected to the inlet of the safety valve 4, the outlet of the safety valve 4 is connected to the flare pipe network 9, the top of the water washing tower 2 is connected to the chimney, the top of the water washing tower 2 is connected to the tail gas recycling pipeline 5, the bottom of the water washing tower 2 is connected to the inlet of the sewage pump 3, the outlet of the sewage pump 3 is connected to the middle part of the water washing tower 2, and the outlet of the sewage pump 3 is connected to the methanol-water distillation tower.

[0056] The low-temperature methanol washing tail gas is pressurized to ~0.08MPaG by the tail gas induced draft fan 1 and enters the water washing tower 2. The desalted water (generally from the system pipeline, with a pressure of 0.5-0.6MPaG) and the methanol water distillation tower regeneration wastewater (from the methanol water distillation tower of the low-temperature methanol washing system) enter the water washing tower 2 from the upper part of the water washing tower 2. The water washing tower 2 is filled with multiple sections of fillers, the water phase is from top to bottom, and the gas phase is from bottom to top. The gas and liquid phases in the tower are in countercurrent contact. The top purifies the tail gas to the chimney / subsequent reuse. After the bottom sewage is pressurized by the sewage pump 3, a part of it is returned to the water washing tower 2 for reuse, and the rest is sent to the methanol water distillation tower for treatment.

[0057] Embodiment 2:

[0058] Based on the exhaust gas purification device of Example 1, this embodiment provides a low-temperature methanol washing combined system, which includes a low-temperature methanol washing system and a low-temperature methanol washing exhaust gas purification device, the low-temperature methanol washing exhaust gas pipeline is connected to the exhaust gas exhaust pipeline in the low-temperature methanol washing system, and the methanol-water distillation tower regeneration wastewater pipeline is connected to the methanol-water distillation tower in the low-temperature methanol washing system.

[0059] The above description of the embodiments is to facilitate the understanding and use of the utility model by those skilled in the art. It is obvious that those familiar with the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the utility model is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the utility model without departing from the scope of the utility model should be within the scope of protection of the utility model.

Claims

1. A low-temperature methanol washing tail gas purification device, characterized in that: include: Water scrubber; Several sections of packing are arranged in the water washing tower at intervals along the height direction; A low-temperature methanol tail gas washing pipeline connected to the lower part of the water washing tower and located below the packing; and a methanol-water distillation tower regeneration wastewater pipeline and a demineralized water pipeline installed on the upper part of the water scrubber and located above the packing; A wire mesh demister is also provided on the top of the water washing tower; A safety valve is also provided at the top of the water washing tower, and the outlet of the safety valve is also connected to the flare pipe network.

2. A low-temperature methanol washing tail gas purification device according to claim 1, characterized in that: The bottom of the water washing tower is also connected to a sewage middle section return pipeline, and the sewage middle section return pipeline is also returned and connected between the two sections of the fillers.

3. A low-temperature methanol washing tail gas purification device according to claim 2, characterized in that: The port of the sewage middle section return pipeline extending into the water washing tower is also connected to a liquid distributor; A sewage pump is also arranged on the sewage middle section return pipeline.

4. A low-temperature methanol tail gas purification device according to claim 1, characterized in that: A gas distributor is also installed at the port where the low-temperature methanol-washed tail gas pipeline extends into the water-washing tower.

5. A low-temperature methanol washing tail gas purification device according to claim 1, characterized in that: The top of the water washing tower is also provided with an exhaust gas outlet, which is also connected to an exhaust gas recycling pipeline.

6. A low-temperature methanol tail gas purification device according to claim 1, characterized in that: The methanol-water distillation tower regeneration wastewater pipeline and the desalted water pipeline are respectively connected to the ports in the water washing tower and are also provided with a liquid distributor.

7. A low-temperature methanol tail gas purification device according to claim 1, characterized in that: The desalted water pipeline is located above the methanol water distillation tower regeneration waste water pipeline.

8. A low-temperature methanol washing combined system, comprising a low-temperature methanol washing system and a low-temperature methanol washing tail gas purification device as claimed in any one of claims 1 to 7, characterized in that: The low-temperature methanol tail gas purification device's low-temperature methanol tail gas washing pipeline is connected to the tail gas vent pipeline in the low-temperature methanol washing system, and the regeneration wastewater pipeline of the low-temperature methanol tail gas purification device is connected to the methanol-water distillation tower of the low-temperature methanol washing system.

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