Acid tail gas desulfurization system and method

Abstract

The invention discloses an acidic tail gas desulfurization system and method, and solves the problems of high operation cost, environmental pollution and the like in the prior art, the acidic tail gas desulfurization system comprises a heat exchange device, a primary desulfurization tower, a secondary desulfurization tower and an induced draft fan, a first outlet of the heat exchange device is communicated with an inlet of the first-stage desulfurization tower, a first outlet of the first-stage desulfurization tower is communicated with a first inlet of the second-stage desulfurization tower, and treated tail gas is discharged through an induced draft fan; a second outlet of the primary desulfurization tower is communicated with a neutralizing tank, an outlet of the neutralizing tank is communicated with an inlet of an oxidizer, an outlet of the oxidizer is communicated with an inlet of an evaporator, and an outlet of the evaporator is communicated with a second inlet of the secondary desulfurization tower. The method effectively improves the removal efficiency of SO2 in the tail gas, ensures that the sulfur content in the discharged tail gas is far lower than the environmental protection standard, and reduces the environmental pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of sulfur-containing tail gas treatment, and particularly to an acidic tail gas desulfurization system and method. Background Art

[0002] In the natural gas purification process, MDEA solution (methyldiethanolamine solution, also known as "amine solution") is widely used to remove CO 2 and sulfides from natural gas. The absorbed amine solution is regenerated by low pressure and high temperature. During this process, hydrogen sulfide, SO 2 and other sulfides are released together with CO 2 Since these released tail gases contain sulfides, according to relevant environmental protection standards, the sulfur content in the sulfur-containing waste gas discharged locally needs to be strictly controlled. However, the currently commonly used tail gas treatment processes, such as using substances such as complex iron, iron sulfide, and activated carbon to remove sulfides from tail gases, generally have disadvantages such as high operating costs, high energy consumption, and environmental pollution. Therefore, it is particularly important to develop a treatment process that can not only effectively reduce the sulfur content in tail gases but also realize the low-energy consumption recovery and utilization of sulfides. Summary of the Invention

[0003] The present invention provides an acidic tail gas desulfurization system and method to solve the technical problems of high operating costs and environmental pollution in the prior art.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] An acidic tail gas desulfurization system and method provided by the present application include a heat exchange device, a primary desulfurization tower, a secondary desulfurization tower, and an induced draft fan. A boiler combustion-supporting fan is provided at the inlet of the heat exchange device. The first outlet of the heat exchange device is communicated with the inlet of the primary desulfurization tower. The first outlet of the primary desulfurization tower is communicated with the first inlet of the secondary desulfurization tower. The treated tail gas is discharged through the induced draft fan. The second outlet of the primary desulfurization tower is communicated with a neutralization tank. The outlet of the neutralization tank is communicated with the inlet of an oxidizer. The outlet of the oxidizer is communicated with the inlet of an evaporator. The outlet of the evaporator is communicated with the second inlet of the secondary desulfurization tower.

[0006] Further, the primary desulfurization tower is connected to a primary circulation pump, and the absorption liquid is circulated in the primary desulfurization tower to absorb sulfur dioxide through the primary circulation pump. The secondary desulfurization tower is connected to a secondary circulation pump, and the absorption liquid is circulated in the secondary desulfurization tower to absorb sulfur dioxide through the secondary circulation pump.

[0007] Further, the second outlet of the heat exchange device is communicated with a gas-fired boiler. The outlet of the gas-fired boiler is then communicated with the inlet of the heat exchange device to realize the recycling of flue gas through the gas-fired boiler.

[0008] Further, the secondary desulfurization tower is connected to the primary desulfurization tower through a pipeline, and the excess absorption liquid in the secondary desulfurization tower enters the primary desulfurization tower through the pipeline for utilization.

[0009] An acidic tail gas desulfurization method provided by the present invention specifically includes the following steps:

[0010] (1) When the MDEA decarbonization liquid is regenerated, the sulfur-containing tail gas is released. First, it passes through a gas-fired boiler, and through the high-temperature action of the furnace, all the sulfides in the tail gas are oxidized into SO 2 ;

[0011] (2) By generating suction through an induced draft fan, the tail gas containing SO 2 passes through the primary desulfurization tower and the secondary desulfurization tower. Add NaOH solution to the primary desulfurization tower and the secondary desulfurization tower. Under the action of the primary circulation pump and the secondary circulation pump, SO 2 comes into full contact with the NaOH solution, and SO 2 is absorbed to form Na 2 SO 3 , and the tail gas is safely discharged locally after desulfurization;

[0012] (3) The saturated absorption liquid formed in the primary desulfurization tower is introduced into a neutralization tank, and NaOH solution is added to the neutralization tank for neutralization;

[0013] (4) All the neutralized solution is added to an oxidizer for oxidation to convert it all into Na 2 SO 4 ;

[0014] (5) The solution in the oxidizer is pumped into an evaporator through a pump, and steam is continuously added to the evaporator. While the alkaline solution absorbs sulfides, the concentration of the Na 2 SO 4 solution continuously increases. The alkaline solution passes through the evaporator, continuously increases in concentration, and finally condenses to form crystals, which are dried and dehydrated to produce the final product sodium sulfate particles;

[0015] (6) The condensate generated by the evaporator enters the secondary desulfurization tower to cool the treated tail gas.

[0016] The beneficial effects achieved by the present invention:

[0017] (1) In the acidic tail gas desulfurization system provided by the present invention, during the desulfurization process, the formed Na 2 SO 3 and Na 2 SO 4The solution can be further processed to be converted into sodium sulfate particles, realizing the resource recovery and utilization of sulfides, reducing waste emissions and creating economic benefits. By introducing a heat exchange device and a gas boiler, the recycling of flue gas is realized, improving the overall thermal efficiency of the system. At the same time, the recycling of the absorption liquid between the first-stage desulfurization tower and the second-stage desulfurization tower also improves the utilization rate of the absorption liquid and reduces waste. By setting up two-stage desulfurization towers, the removal efficiency of SO 2 in the tail gas is effectively improved, ensuring that the sulfur content in the discharged tail gas is far lower than the environmental protection standards and reducing environmental pollution.

[0018] (2) In the acidic tail gas desulfurization method provided by the present invention, all sulfides in the tail gas are oxidized into SO 2 through boiler combustion oxidation, and then through the desulfurization tower, the tail gas is absorbed by the alkali liquid for sulfides and discharged up to standard. The alkali liquid absorbing SO 2 enters the triple-effect evaporation device for drying and crystallization after oxidation to produce sodium sulfate, so that the sulfides in the tail gas are effectively utilized. At the same time, the present invention effectively solves the problem of excessive sulfur content in the discharged tail gas with a simple structure and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the process flow chart of the embodiment of the present invention;

[0020] The drawings are only for illustrative purposes and should not be construed as limitations on this patent. To better illustrate this embodiment, some components in the drawings will be omitted, enlarged or reduced, and do not represent the dimensions of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. Identical or similar reference numerals correspond to identical or similar components. The terms describing the positional relationship in the drawings are only for illustrative purposes and should not be construed as limitations on this patent. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of the technical solutions appears to be contradictory or unable to be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0022] The technical solutions of the present invention will be described in detail below in conjunction with specific drawings.

[0023] As shown Figure 1 As shown, an acidic tail gas desulfurization system and method include a heat exchange device, a primary desulfurization tower, a secondary desulfurization tower, and a induced draft fan. A boiler combustion-supporting fan is arranged at the inlet of the heat exchange device. The first outlet of the heat exchange device is communicated with the inlet of the primary desulfurization tower. The first outlet of the primary desulfurization tower is communicated with the first inlet of the secondary desulfurization tower. The treated tail gas is discharged through the induced draft fan. The second outlet of the primary desulfurization tower is communicated with a neutralization tank. The outlet of the neutralization tank is communicated with the inlet of an oxidizer. The outlet of the oxidizer is communicated with the inlet of an evaporator. The outlet of the evaporator is communicated with the second inlet of the secondary desulfurization tower. The primary desulfurization tower is connected to a primary circulation pump, and the absorption liquid circulates in the primary desulfurization tower through the primary circulation pump to absorb sulfur dioxide. The secondary desulfurization tower is connected to a secondary circulation pump, and the absorption liquid circulates in the secondary desulfurization tower through the secondary circulation pump to absorb sulfur dioxide. The second outlet of the heat exchange device is communicated with a gas-fired boiler, and the outlet of the gas-fired boiler is then communicated with the inlet of the heat exchange device, and the flue gas is recycled through the gas-fired boiler. The secondary desulfurization tower is connected to the primary desulfurization tower through a pipeline, and the excess absorption liquid in the secondary desulfurization tower enters the primary desulfurization tower through the pipeline for utilization.

[0024] An acidic tail gas desulfurization method specifically includes the following steps:

[0025] (1) When the MDEA decarbonization liquid is regenerated, the sulfur-containing tail gas is released. First, it passes through the gas-fired boiler, and through the high-temperature action of the furnace, all the sulfides in the tail gas are oxidized into SO 2 ;

[0026] (2) By generating suction through the induced draft fan, the tail gas containing SO 2 passes through the primary desulfurization tower and the secondary desulfurization tower. Add NaOH solution into the primary desulfurization tower and the secondary desulfurization tower. Under the action of the primary circulation pump and the secondary circulation pump, SO 2 fully contacts with the NaOH solution, and SO 2 is absorbed to form Na 2 SO 3 , and the tail gas is safely discharged on the spot after desulfurization;

[0027] (3) The saturated absorption liquid formed in the primary desulfurization tower is introduced into the neutralization tank, and NaOH solution is added into the neutralization tank for neutralization;

[0028] (4) All the neutralized solution is added into the oxidizer for oxidation to convert it all into Na 2 SO 4 ;

[0029] (5) The formed Na 2 SO 3 solution undergoes a superoxide nanomicrobubble oxidation process to convert it all into Na2 SO 4 , while the lye absorbs sulfide, the concentration of Na 2 SO 4 solution continuously increases. At the same time, the lye passes through the evaporator, continuously increases in concentration, and finally condenses to form crystals, which are dehydrated by drying to produce the final product, sodium sulfate particles; specifically, the solution in the oxidizer is pumped into the evaporator by a pump, and steam is continuously added to it. While the lye absorbs sulfide, the concentration of Na 2 SO 4 solution continuously increases. The lye passes through the evaporator, and the concentration of the material is continuously increased by using triple-effect evaporation steam, and finally condenses to form crystals, which are separated by a centrifuge and dehydrated by drying to produce the final product, sodium sulfate particles;

[0030] (6) The condensate generated by the evaporator enters the secondary desulfurization tower to cool the treated tail gas.

[0031] The serial numbers of the embodiments of the present application above are only for description and do not represent the advantages or disadvantages of the embodiments. The above are only the preferred embodiments of the present application, and do not limit the patent scope of the present application accordingly. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A sour tail gas desulfurization system, characterized in that: It includes a heat exchange device, a primary desulfurization tower, a secondary desulfurization tower, and an induced draft fan. A boiler combustion-supporting fan is arranged at the inlet of the heat exchange device. The first outlet of the heat exchange device is connected to the inlet of the primary desulfurization tower, and the first outlet of the primary desulfurization tower is connected to the first inlet of the secondary desulfurization tower. The treated exhaust gas is discharged through the induced draft fan; the second outlet of the primary desulfurization tower is connected to the neutralization tank, the outlet of the neutralization tank is connected to the inlet of the oxidizer, the outlet of the oxidizer is connected to the inlet of the evaporator, and the outlet of the evaporator is connected to the second inlet of the secondary desulfurization tower.

2. The acidic tail gas desulfurization system according to claim 1, characterized in that: The primary desulfurization tower is connected to a primary circulation pump, through which the absorption liquid circulates in the primary desulfurization tower to absorb sulfur dioxide; the secondary desulfurization tower is connected to a secondary circulation pump, through which the absorption liquid circulates in the secondary desulfurization tower to absorb sulfur dioxide.

3. The acidic tail gas desulfurization system according to claim 1, characterized in that: The second outlet of the heat exchange device is connected to the gas boiler, and the outlet of the gas boiler is connected to the inlet of the heat exchange device, so that the flue gas is recycled through the gas boiler.

4. The acidic tail gas desulfurization system according to claim 1, characterized in that: The secondary desulfurization tower is connected to the primary desulfurization tower through a pipeline, and the excess absorption liquid in the secondary desulfurization tower enters the primary desulfurization tower through the pipeline for utilization.

5. A method for desulfurization of acidic tail gas, characterized in that: The acid tail gas desulfurization system according to any one of claims 1 to 4 specifically comprises the following steps: (1) When the MDEA decarbonization liquid is regenerated, the sulfur-containing tail gas is released and first passes through the gas boiler. Under the high temperature of the furnace, all the sulfides in the tail gas are oxidized into SO2; (2) The exhaust gas containing SO2 is passed through the primary desulfurization tower and the secondary desulfurization tower by generating suction through the induced draft fan. NaOH solution is added to the primary desulfurization tower and the secondary desulfurization tower. Under the action of the primary circulation pump and the secondary circulation pump, SO2 is fully contacted with the NaOH solution and SO2 is absorbed to form Na2SO3. The exhaust gas is desulfurized and then discharged safely on site. (3) Passing the saturated absorption liquid formed in the primary desulfurization tower into the neutralization tank, and adding NaOH solution into the neutralization tank for neutralization; (4) Add all the neutralized solution to an oxidizer for oxidation and convert it into Na2SO4; (5) The solution in the oxidizer is pumped into the evaporator by a pump, and steam is continuously added thereto. While the alkali solution absorbs sulfide, the concentration of the Na2SO4 solution is continuously increased. The alkali solution passes through the evaporator, and the material concentration is continuously increased by using the three-effect evaporation gas, and finally condensed to form crystals, which are separated by a centrifuge and dried and dehydrated to form the final product, sodium sulfate particles; (6) The condensate produced by the evaporator enters the secondary desulfurization tower to cool the treated exhaust gas.

Images