Tar processing flue gas treatment system

Abstract

The present application provides a tar processing flue gas treatment system, comprising a desulfurization tower and a dust and denitration device, the desulfurization tower comprises a cavity for passing smoke, an outlet flue communicating with the top of the cavity, a lime slurry feeding device connected with the lower part of the cavity, an inlet flue manifold communicating with the lower part of the cavity, an ammonia gas mixing device connected with the inlet flue manifold, the inlet flue manifold is provided with a plurality of flue branch pipes uniformly distributed, the plurality of flue branch pipes are respectively communicated with the smoke exhaust ports of a tar distillation device, an industrial naphthalene distillation device and a modified pitch device, the dust and denitration device comprises a filter bin, a plurality of ceramic filter pipes are arranged in the filter bin, the filter bin inlet is connected with the outlet flue of the desulfurization tower, and the filter bin outlet is connected with a tar distillation original chimney through an induced draft fan. The tar processing flue gas treatment system has small land occupation, can efficiently remove sulfur, nitrogen and dust in the flue gas, and realizes standard flue gas discharge.

Description

Technical Field

[0001] This invention belongs to the field of flue gas purification technology, and in particular relates to a tar processing flue gas treatment system. Background Technology

[0002] Coal tar processing is a production process in the chemical raw materials and chemical products manufacturing industry that involves dehydration, fractionation, and other treatments of coal tar. The main products include light oil, industrial naphthalene, and wash oil, among other chemical raw materials. China's annual coal tar production is 13 million tons. High-temperature coal tar contains tens of thousands of compounds, from which more than 200 kinds of chemical raw materials, such as benzene, naphthalene, and anthracene, can be extracted, many of which are difficult to replace in the petrochemical industry. Processing technologies encompass dehydration and desalination pretreatment, fractionation extraction and hydrogenation refining, and cracking. Products are widely used in synthetic fibers, dyes, and pharmaceuticals. However, tar processing generates a large amount of flue gas. As air pollution becomes increasingly prominent, the national requirements for flue gas emissions from the coking industry have become more stringent, leading to the introduction of the latest "Emission Standard for Pollutants from Coking Chemical Industry" (GB16171.1-2024). Currently, the coal gas tubular furnaces in the tar processing plant include tar distillation units, industrial naphthalene distillation units, and modified asphalt units. All of them use coke oven gas as the combustion medium. At the same time, the VOCs gas washed by the exhaust scrubbing tower of each unit is sent to the tubular furnace for incineration, and the tail gas needs to be treated for desulfurization and denitrification before being discharged. Summary of the Invention

[0003] This invention proposes a tar processing flue gas treatment system that occupies a small area, has a high degree of automation, and efficiently purifies flue gas to achieve compliant emissions.

[0004] This invention provides a tar processing flue gas treatment system, including a desulfurization tower and a dust removal and denitrification device. The desulfurization tower includes a cavity for flue gas circulation, an outlet flue connected to the top of the cavity, a quicklime feeding device connected to the bottom of the cavity, an inlet flue main pipe connected to the bottom of the cavity, an ammonia mixing device connected to the inlet flue main pipe, and multiple evenly distributed flue branch pipes provided on the inlet flue main pipe. The multiple flue branch pipes are respectively connected to the exhaust ports of the tar distillation unit, the industrial naphthalene distillation unit, and the modified asphalt unit. The dust removal and denitrification device includes a filter chamber, which is equipped with several ceramic filter tubes. The inlet of the filter chamber is connected to the outlet flue of the desulfurization tower, and the outlet of the filter chamber is connected to the tar distillation chimney via an induced draft fan.

[0005] Furthermore, it also includes a control device, which includes a controller, an online gas concentration monitor installed inside the tar distillation chimney, an induced draft fan connected to a motor via a first frequency converter, a quicklime feeding device connected to the desulfurization tower feed port via a screw conveyor, a screw conveyor connected to a motor via a second frequency converter, a regulating valve at the ammonia mixing device outlet, an input terminal of the controller electrically connected to the online gas concentration monitor, and an output terminal of the controller connected to the regulating valve, the first frequency converter, and the second frequency converter, respectively.

[0006] Furthermore, the online gas concentration detector monitors the treated flue gas indicators in real time and transmits them to the controller. The controller automatically controls the opening of the regulating valve, the speed of the first frequency converter and the second frequency converter according to the preset indicators, thereby adjusting the feed rate of mixed ammonia and quicklime and the exhaust speed of the induced draft fan.

[0007] Furthermore, the ammonia mixing device is a Venturi mixer, with a compressed air inlet and a clean flue gas inlet at the contraction end, an ammonia inlet at the throat, and a mixed ammonia outlet at the diffusion end.

[0008] Furthermore, the inner wall of the ceramic filter tube inside the filter chamber is uniformly distributed with denitrification catalyst, and an ash collection hopper and ash discharge device are provided below the filter chamber.

[0009] This invention has the following beneficial effects: The tar processing flue gas treatment system of this invention first desulfurizes the flue gas by setting up a desulfurization tower, and then removes dust and nitrates the flue gas by passing it through ceramic filter tubes in the dust removal and denitrification device. It occupies a small area. By setting up a control device to automatically adjust the feed rate of mixed ammonia and quicklime and the exhaust speed in the induced draft fan, it can meet the safe and stable operation of tar processing load under different working conditions. It efficiently removes sulfur, nitrates, and dust from the flue gas. Under the condition of a baseline oxygen content of 3%, SO2 is reduced from 540 mg / m³ to 9 mg / m³, NOx is reduced from 360 mg / m³ to below 13 mg / m³, and dust content is reduced from 61 mg / m³. 3 Reduce to below 6 mg / m³ to ensure that the air quality above the factory area is up to standard and that flue gas emissions meet or even reach ultra-low emission standards. Detailed Implementation

[0010] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0011] 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.

[0012] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicating the orientation or positional relationship, are only for the convenience of describing the present invention 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, and therefore should not be construed as a limitation of the present invention.

[0013] 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 invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0014] A tar processing flue gas treatment system includes a desulfurization tower, a dust removal and denitrification device, and a control device.

[0015] The desulfurization tower includes a chamber for flue gas circulation, an outlet flue connected to the top of the chamber, an inlet flue main connected to the bottom of the chamber, an ammonia mixing device connected to the inlet flue main, and a slaked lime feeding device connected to the bottom of the chamber. The inlet flue main has multiple evenly distributed flue branch pipes, which are respectively connected to the exhaust ports of the tar distillation unit, the industrial naphthalene distillation unit, and the modified asphalt unit. The ammonia mixing device is a Venturi mixer, with a compressed air inlet and a clean flue gas inlet at the contraction end, an ammonia inlet at the throat, and a mixed ammonia outlet at the diffusion end, with a regulating valve at the mixed ammonia outlet. The slaked lime feeding device includes a silo with a conveying pipe at the bottom. The conveying pipe is connected to the desulfurization tower inlet via a screw conveyor, which is connected to a motor via a second frequency converter.

[0016] The dust removal and denitrification device includes a filter chamber containing several ceramic filter tubes. Denitrification catalyst is evenly distributed on the inner wall of each ceramic filter tube. A dust collection hopper and dust discharge device are located below the filter chamber. The filter chamber inlet is connected to the outlet flue of the desulfurization tower, and the filter chamber outlet is connected to the tar distillation chimney via an induced draft fan. The induced draft fan is connected to a motor via a first frequency converter.

[0017] The control device includes a controller and an online gas concentration monitor installed inside the tar distillation chimney. The controller input is electrically connected to the online gas concentration monitor, and the controller output is connected to a regulating valve, a first frequency converter, and a second frequency converter, respectively.

[0018] In this example, there are three tar distillation units: H203A pitch tubular furnace, H203B pitch tubular furnace, and H523 heavy oil tubular furnace; two industrial naphthalene distillation units: industrial naphthalene primary distillation tubular furnace and industrial naphthalene rectification tubular furnace; and one modified pitch unit, namely modified pitch tubular furnace. The flue gas from the six units enters the desulfurization tower inlet flue main pipe through the flue branch pipe, mixes with mixed ammonia gas, and then reacts with high-efficiency slaked lime to generate CaSO4 and CaSO3. After desulfurization, the flue gas enters the filtration chamber. Larger dust particles from the desulfurization reaction settle under gravity, while smaller dust particles deposit on the filter media surface to form a dust cake layer. This cake layer then undergoes a secondary desulfurization reaction with the desulfurizing agent on the ceramic filter tube surface. After secondary desulfurization and dust removal, the flue gas passes through the filter media surface and then comes into contact with the catalyst layer inside the filter tube wall. Through the catalytic action of the catalyst, nitrogen oxides and ammonia in the flue gas react to produce nitrogen and water. Finally, the flue gas is extracted by an induced draft fan and sent to the tar distillation chimney for discharge into the atmosphere.

[0019] Throughout the flue gas desulfurization and denitrification process, an online gas concentration detector in the original tar distillation chimney is installed to monitor the treated flue gas indicators in real time and transmit the data to the controller. The controller automatically controls the opening of the regulating valve and the frequencies of the first and second frequency converters based on preset indicators, thereby adjusting the feed rates of mixed ammonia and quicklime, as well as the exhaust speed of the induced draft fan. This ensures safe and stable operation under different tar processing loads. Under a baseline oxygen content of 3%, SO2 is reduced from 540 mg / m³ to 9 mg / m³, NOx from 360 mg / m³ to below 13 mg / m³, and dust content from 61 mg / m³. 3 Reduce to below 6 mg / m³ to achieve standard emissions or even ultra-low emissions for flue gas.

[0020] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications and alterations made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

[0021] Other parts of this invention that are not detailed herein are all prior art and will not be described further here.

[0022] Although the invention has been described in conjunction with preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make various changes, substitutions and modifications to the subject matter set forth herein without departing from the spirit and scope of the invention. Therefore, the scope of protection of the invention shall be determined by the scope defined in the claims.

Claims

1. A tar processing flue gas treatment system, characterized in that, Including desulfurization towers and dust removal and denitrification devices, The desulfurization tower includes a cavity for flue gas circulation, an outlet flue connected to the top of the cavity, a quicklime feeding device connected to the bottom of the cavity, an inlet flue main pipe connected to the bottom of the cavity, an ammonia mixing device connected to the inlet flue main pipe, and multiple evenly distributed flue branch pipes provided on the inlet flue main pipe. The multiple flue branch pipes are respectively connected to the exhaust ports of the tar distillation unit, the industrial naphthalene distillation unit, and the modified asphalt unit. The dust removal and denitrification device includes a filter chamber, which is equipped with several ceramic filter tubes. The inlet of the filter chamber is connected to the outlet flue of the desulfurization tower, and the outlet of the filter chamber is connected to the tar distillation chimney via an induced draft fan.

2. The tar processing flue gas treatment system according to claim 1, characterized in that, It also includes a control device, which includes a controller, an online gas concentration monitor installed inside the tar distillation chimney, an induced draft fan connected to a motor via a first frequency converter, a quicklime feeding device connected to the desulfurization tower feed port via a screw conveyor, a screw conveyor connected to a motor via a second frequency converter, a regulating valve installed at the mixed ammonia outlet of the ammonia mixing device, an input terminal of the controller electrically connected to the online gas concentration monitor, and an output terminal of the controller connected to the regulating valve, the first frequency converter, and the second frequency converter, respectively.

3. The tar processing flue gas treatment system according to claim 2, characterized in that, The online gas concentration detector monitors the parameters of the treated flue gas in real time and transmits them to the controller. The controller automatically controls the opening of the regulating valve, the frequency of the first frequency converter and the second frequency converter according to the preset parameters, thereby adjusting the feed rate of mixed ammonia and quicklime and the exhaust speed of the induced draft fan.

4. The tar processing flue gas treatment system according to claim 1, characterized in that, The ammonia mixing device is a Venturi mixer, with a compressed air inlet and a clean flue gas inlet at the contraction end, an ammonia inlet at the throat, and a mixed ammonia outlet at the diffusion end.

5. The tar processing flue gas treatment system according to claim 1, characterized in that, The inner wall of the ceramic filter tube in the filter chamber is uniformly distributed with denitrification catalyst, and a dust collection hopper and dust discharge device are provided below the filter chamber.