Flue gas emission system of sulfur recovery device

Abstract

The invention discloses a flue gas emission system of a sulfur recovery device. The flue gas emission system comprises a tail gas incinerator, a steam superheater, an incinerator steam generator, a low-pressure steam generator, an alkaline washing tower and a glass fiber reinforced plastic chimney which are sequentially connected through pipelines, the alkaline washing tower is provided with a circulating pump, the circulating pump is arranged on an alkaline liquor circulating pipe, one end of the alkaline liquor circulating pipe is communicated with the bottom of the alkaline washing tower, and the other end of the alkaline liquor circulating pipe extends into the upper part in the alkaline washing tower; the glass fiber reinforced plastic chimney is further communicated with a return pipe, and condensate in the glass fiber reinforced plastic chimney flows back into the alkaline washing tower through the return pipe by means of gravity. The flue gas heating process and heat exchange equipment behind the flue gas alkaline washing tower are omitted, meanwhile, the low-temperature condition that the chimney is made of glass fiber reinforced plastic is created, energy conservation and efficiency improvement are achieved, the construction cost is greatly reduced, the requirements for low-temperature flue gas emission and corrosion resistance are met, the flue gas emission temperature is low, pollutants carried by flue gas are reduced, and white fog elimination is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of oil refining and chemical engineering, in particular to a flue gas emission system of a sulfur recovery device. Background Art

[0002] At present, Chinese companies with large-scale sulfur recovery equipment, such as Shanghai Petrochemical, Luoyang Petrochemical, and Jinlin Petrochemical, all have thermal power departments, which use coal-fired boilers to provide electricity and steam for the factory. The coal-fired flue gas contains low concentrations of sulfur dioxide, generally around 1000ppm. At present, this part of SO2 is converted into low-value-added desulfurized gypsum through calcium desulfurization technology, resulting in serious waste of resources. Therefore, recovering sulfur dioxide in flue gas as a reactant for Claus reaction can achieve flue gas desulfurization and increase sulfur production at the same time; Existing sulfur recovery unit flue gas emission systems and processes (such as Figure 3 As shown in the figure, the flue gas from the flue gas quenching tower and the absorption tower enters the tail gas incinerator. After incineration, the flue gas passes through the medium-pressure steam superheater and the tail gas incinerator evaporator, and the temperature is reduced to about 276°C. The flue gas exchanges heat with the 50°C flue gas discharged from the top of the alkali washing tower in the heat exchange equipment, and then the temperature drops to 150°C and enters the alkali washing tower. The tail gas discharged from the top of the alkali washing tower is heated to 166°C and then enters the steel chimney for discharge. It has the following disadvantages: (1) The chimney is made of steel, and the construction cost of a new sulfur recovery device is relatively high; (2) In order to avoid dew point corrosion of the steel chimney, the temperature of the exhaust gas after leaving the alkali scrubber is 50°C, and then the exhaust gas temperature is raised to about 166°C by the heat exchanger, which is higher than the flue gas dew point, and then discharged through the chimney. The heat used to heat the flue gas is also lost to the atmosphere along with the flue gas, which is not energy-saving; (3) Flue gas heating process: The flue gas discharged into the chimney is heated by the flue gas at the outlet of the waste heat boiler at about 276°C. The investment and maintenance costs of related pipelines and equipment are relatively high; (4) The exhaust gas emission temperature of the chimney is about 166°C, which is relatively high and is easy to carry some water-soluble pollutants. In addition, the difference between the emission temperature and the external temperature is large, which is easy to produce white mist. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the existing defects and provide a flue gas emission system for a sulfur recovery device, which eliminates the flue gas heating process and heat exchange equipment after the flue gas alkali washing tower, and also creates a low-temperature condition for the chimney made of fiberglass, which saves energy and increases efficiency, greatly reduces the construction cost, achieves the low-temperature emission and corrosion resistance requirements of the flue gas, has a low flue gas emission temperature, reduces the pollutants carried by the flue gas, is conducive to the elimination of white mist, and can effectively solve the problems in the background technology.

[0004] To achieve the above object, the present invention provides the following technical solution: a flue gas emission system for a sulfur recovery device, comprising a tail gas incinerator, a steam superheater, an incinerator steam generator, a low-pressure steam generator, an alkali washing tower and a glass fiber reinforced plastic chimney connected in sequence through pipelines; the incinerator steam generator is correspondingly connected to a steam drum 1, and the low-pressure steam generator is correspondingly connected to a steam drum 2; The alkali washing tower is provided with a circulation pump, which is installed on an alkali liquid circulation pipe, one end of which is connected to the bottom of the alkali washing tower, and the other end of which extends into the upper part of the alkali washing tower; The glass fiber reinforced plastic chimney is also connected with a reflux pipe, and the condensate in the glass fiber reinforced plastic chimney flows back to the alkali washing tower through the reflux pipe by gravity.

[0005] Preferably, the reflux pipe is also connected to an alkali solution adding pipe, and the alkali solution adding pipe is installed with a valve.

[0006] Preferably, a spiral blade is provided on the upper portion of the smoke exhaust passage in the fiberglass reinforced plastic chimney.

[0007] Preferably, a tower base is provided at the bottom of the FRP chimney, one end of the reflux pipe is located at the bottom of the FRP chimney, the other end of the reflux pipe extends into the lower part of the alkali washing tower, and a valve is installed on the reflux pipe near the FRP chimney.

[0008] A flue gas treatment method for a flue gas emission system of a sulfur recovery device, the flue gas from a quench tower and an absorption tower enters an exhaust gas incinerator for combustion, then exchanges heat through the incinerator steam generator to output medium-pressure steam, the flue gas is cooled to °C and then enters a low-pressure steam generator, exchanges heat to output low-pressure steam, the flue gas is cooled to °C and then enters an alkali washing tower for neutralization and washing, then the flue gas is cooled to °C and then enters a glass fiber reinforced plastic chimney for emission. The flue gas has a low temperature and condensable liquid can flow down the inner wall of the glass fiber reinforced plastic chimney and flow back to the alkali washing tower through a reflux pipe.

[0009] Compared with the prior art, the present invention has the following beneficial effects: (1) Eliminate the traditional flue gas heating process and heat exchange equipment, increase the heat recovery of the low-pressure steam generator, and use the heat from the flue gas to produce more steam, increase benefits, comply with national energy-saving policies, and save investment and maintenance costs for pipelines and heat exchange equipment related to the flue gas heating process; (2) Replacing the chimney material greatly reduces the cost of chimney construction and makes it more corrosion-resistant, achieving low-temperature flue gas emission and corrosion-resistant requirements; (3) Since the flue gas emission temperature is low, the pollutants carried by the flue gas are reduced, and the emission temperature is close to normal temperature, which is conducive to the elimination of white mist; Only after changing the chimney material to meet the low temperature and corrosion resistance conditions can the heating process and heat exchange equipment be cancelled. At the same time, only after lowering the flue gas temperature can the material of the flue gas emission chimney be changed. Otherwise, the fiberglass chimney will overheat. By using a fiberglass chimney, the traditional heat exchange equipment can be cancelled and the heating process can be replaced with a low-pressure steam generator. The two complement each other and cannot be implemented separately. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a schematic diagram of the local structure of the present invention; Figure 3 This is a schematic diagram of the structure of a traditional flue gas exhaust system.

[0011] In the figure: 1 tail gas incinerator, 2 steam superheater, 3 incinerator steam generator, 3.1 steam drum 1, 4 low-pressure steam generator, 4.1 steam drum 2, 5 alkali washing tower, 6 glass fiber reinforced plastic chimney, 6.1 tower base, 6.2 spiral blades, 7 alkali solution adding pipe, 8 alkali solution circulating pipe, 9 circulating pump, 10 reflux pipe. DETAILED DESCRIPTION

[0012] The present invention can be explained in detail through the following embodiments. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention. In the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "front", "back", "left", "right", etc. indicating directions or positional relationships, they only correspond to the drawings of the present application for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific direction.

[0013] See also Figure 1-3 The present invention provides a technical solution: a flue gas emission system of a sulfur recovery device, comprising a tail gas incinerator 1, a steam superheater 2, an incinerator steam generator 3, a low-pressure steam generator 4, an alkali washing tower 5 and a glass fiber reinforced plastic chimney 6 connected in sequence through pipelines; the incinerator steam generator 3 is correspondingly connected to a steam drum 1 3.1, and the low-pressure steam generator 4 is correspondingly connected to a steam drum 2 4.1; The alkali washing tower 5 is provided with a circulation pump 9, which is installed on an alkali liquid circulation pipe 8, one end of which is connected to the bottom of the alkali washing tower 5, and the other end of which extends into the upper part of the alkali washing tower 5; the alkali liquid can be rotatably provided to the alkali washing tower 5 through the circulation pump 9 and the alkali liquid circulation pipe 8, and the alkali liquid is neutralized and washed with the flue gas in the alkali washing tower 5; The FRP chimney 6 is also connected to a reflux pipe 10. The condensate in the FRP chimney 6 flows back to the alkali washing tower 5 through the reflux pipe 10 by gravity to recover the condensate. The flue gas coming out of the alkali washing tower 5 will carry small droplets of alkali liquid, which will condense in the discharge stage in the FRP chimney 6, so as to achieve recycling and save resources. Furthermore, the reflux pipe 10 is also connected to an alkali solution adding pipe 7, and the alkali solution adding pipe 7 is installed with a valve, and the alkali solution can be added to the alkali washing tower 5 through the alkali solution adding pipe 7, and the alkali solution adding pipe 7 is switched on and off by the valve; Furthermore, a spiral blade 6.2 is provided on the upper part of the exhaust passage in the glass fiber reinforced plastic chimney 6, and the smoke flows along the spiral blade 6.2, which increases the circulation time and is more conducive to smoke condensation and cooling; Furthermore, a tower base 6.1 is provided at the bottom of the FRP chimney 6, one end of the reflux pipe 10 is located at the bottom of the FRP chimney 6, and the other end of the reflux pipe 10 extends into the lower part of the alkali washing tower 5. A valve is installed near the FRP chimney 6 of the reflux pipe 10, that is, the FRP chimney 6 is higher than the alkali washing tower 5. When the valve on the reflux pipe 10 is opened, the alkali liquid in the FRP chimney 6 automatically flows into the alkali washing tower 5 through the reflux pipe 10.

[0014] A flue gas treatment method for a flue gas emission system of a sulfur recovery device, wherein the flue gas from a quench tower and an absorption tower enters a tail gas incinerator 1 for combustion, and then is heat-exchanged by a steam generator 3 of the incinerator to output medium-pressure steam, and then the flue gas is cooled to 276°C and then enters a low-pressure steam generator 4 for heat-exchange to output low-pressure steam, and then the flue gas is cooled to 150°C and then enters an alkali washing tower 5 for neutralization and washing, and then the flue gas is cooled to 50°C and then enters a glass fiber reinforced plastic chimney 6 for emission, and the condensable liquid due to the low flue gas temperature can flow down along the inner wall of the glass fiber reinforced plastic chimney 6 and reflux to the alkali washing tower 5 through a reflux pipe 10; It can be understood that the exhaust gas passes through the exhaust gas incinerator 1 and then through the incinerator steam generator 3 and the low-pressure steam generator 4 to reach a temperature of 150°C, and then enters the alkali washing tower 5 for neutralization and washing. The flue gas is then cooled to 50°C and then enters the FRP chimney 6 for discharge. Only after the flue gas is cooled to 50°C can it be discharged through the FRP chimney. The traditional heat exchange equipment and heating process are cancelled and replaced with a low-pressure steam generator, which saves energy and increases efficiency, greatly reduces construction costs, and achieves low-temperature flue gas emission and corrosion resistance requirements. The flue gas emission temperature is low, which reduces pollutants carried by the flue gas and is conducive to the elimination of white fog.

[0015] The following is an explanation with specific data: (1) Replacing the chimney material greatly reduces the cost of chimney construction. Taking the chimney of a 100,000 ton / year sulfur recovery unit as an example, the construction cost of a steel chimney is about RMB 10.04 million, while the construction cost of a fiberglass chimney is about RMB 4.50 million, which can save RMB 5.54 million in construction costs at one time; (2) This flue gas emission system recovers a large amount of heat emitted by flue gas to the atmosphere, thereby improving the economic benefits of the device during operation. Taking a sulfur recovery device with an annual output of 100,000 tons as an example, the heat of 45.4t / h flue gas temperature rise of 116℃ is discharged through the chimney and completely lost. By adding a low-pressure steam generator, about 5.16*106kJ / h of heat can be recovered (the efficiency is calculated at 70%), and 18.4t / h of 0.35MPa saturated steam can be produced, with an annual efficiency increase of 29.01 million yuan (calculated at the tax-free price of 180 yuan / ton for 0.35MPa steam); (3) After the flue gas heating process and equipment are innovatively eliminated, construction costs are saved. Taking the sulfur recovery unit with an annual output of 100,000 tons as an example, the investment cost saved by eliminating the pipelines and equipment related to the flue gas heating process is about 950,000 yuan, including the flue gas heat exchanger and related carbon steel pipelines. At the same time, construction costs and subsequent maintenance costs are also saved; (4) Since the flue gas emission temperature is reduced from about 166°C to about 50°C, the low flue gas temperature condensed liquid can flow down the inner wall of the chimney to the alkali washing tower, thereby reducing the pollutants carried by the exhaust gas. In addition, the emission temperature is close to normal temperature, which is conducive to the elimination of white mist, environmental protection and visual experience.

[0016] The parts of the present invention that are not described in detail are prior art. It is obvious to those skilled in the art that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention; therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and it is intended that all changes that fall within the meaning and scope of equivalent elements are included in the content of the present invention.

Claims

1. A flue gas emission system for a sulfur recovery device, comprising a tail gas incinerator (1), a steam superheater (2), an incinerator steam generator (3), a low-pressure steam generator (4), an alkali washing tower (5) and a glass fiber reinforced plastic chimney (6) connected in sequence through pipelines; characterized in that: The incinerator steam generator (3) is correspondingly connected to a steam drum 1 (3.1), and the low-pressure steam generator (4) is correspondingly connected to a steam drum 2 (4.1); The alkali washing tower (5) is provided with a circulation pump (9), which is installed on an alkali liquid circulation pipe (8), one end of the alkali liquid circulation pipe (8) is connected to the bottom of the alkali washing tower (5), and the other end of the alkali liquid circulation pipe (8) extends into the upper part of the alkali washing tower (5); The glass fiber reinforced plastic chimney (6) is also connected to a reflux pipe (10), and the condensate in the glass fiber reinforced plastic chimney (6) flows back into the alkali washing tower (5) through the reflux pipe (10) by gravity.

2. A flue gas exhaust system for a sulfur recovery unit according to claim 1, characterized in that: The reflux pipe (10) is also connected to an alkali solution adding pipe (7), and the alkali solution adding pipe (7) is equipped with a valve.

3. The flue gas exhaust system of a sulfur recovery unit according to claim 1, characterized in that: A spiral blade (6.2) is provided at the upper portion of the smoke exhaust passage in the fiberglass reinforced plastic chimney (6).

4. A flue gas exhaust system for a sulfur recovery unit according to claim 1, characterized in that: A tower base (6.1) is provided at the bottom of the glass fiber reinforced plastic chimney (6), one end of the return pipe (10) is located at the bottom of the glass fiber reinforced plastic chimney (6), and the other end of the return pipe (10) extends into the lower part of the alkali washing tower (5). A valve is installed near the glass fiber reinforced plastic chimney (6).

5. A flue gas treatment method for a flue gas exhaust system of a sulfur recovery device according to any one of claims 1 to 4, characterized in that: The flue gas from the quench tower and the absorption tower enters the tail gas incinerator (1) for combustion, and then passes through the incinerator steam generator (3) for heat exchange to output medium-pressure steam. The flue gas is cooled to 276°C and then enters the low-pressure steam generator (4) for heat exchange to output low-pressure steam. The flue gas is cooled to 150°C and then enters the alkali washing tower (5) for neutralization and washing. The flue gas is then cooled to 50°C and then enters the glass fiber reinforced plastic chimney (6) for discharge. The low temperature of the flue gas allows the condensed liquid to flow down the inner wall of the glass fiber reinforced plastic chimney (6) and flow back to the alkali washing tower (5) through the reflux pipe (10).

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