CN204853511U - Sulphur recovery system that low -sulfur discharged based on claus reaction system - Google Patents

Abstract

The utility model discloses a low-sulfur emission sulfur recovery system based on a Claus reaction system, which solves the problems of long tail gas treatment process, high cost and environmental pollution in the Claus reaction system. The technical solution includes a Claus reaction system, the tail gas outlet of the Claus reaction system is connected to the flue gas inlet of the desulfurization tower through an incinerator and a heat exchanger, the top of the desulfurization tower is provided with a flue gas outlet, the lower part is provided with a flue gas inlet, and the bottom part is provided with a flue gas inlet. There is a slurry outlet, and the tower body is composed of an upper washing section, a middle absorption section and a lower concentration section. _The utility model has low equipment investment and operation costs, and is environmentally friendly, and the SO2 content in the treated tail gas can be reduced to below 100mg/ ^Nm3 , which meets the requirements of national norms.

Description

A Sulfur Recovery System Based on Claus Reaction System with Low Sulfur Emission

technical field

The utility model relates to the technical field of chemical industry, in particular to a sulfur recovery system with low sulfur emission.

Background technique

With the rapid development of the economy, the SO ₂ emitted by the smelting and roasting of sulfur-containing fuels in China has increased sharply, and the environmental problems caused by this have become more and more prominent. In this regard, the state has issued many policies and regulations to control SO ₂ emissions. The standard requirements have been further improved, never higher than 960mg/Nm ³ , and the emission concentration of SO ₂ newly stipulated in GB31570 on July 1, 2015 is less than 400mg/Nm ³ (less than 100mg/Nm ³ in special cases), which shows that the Chinese petrochemical industry The determination to implement the green and low-carbon development strategy. However, some chemical plants under construction, especially coal-to-natural gas projects, generally pass through the sulfur recovery device, and the SO ₂ emission concentration in the final tail gas still only meets the old standard, reaching 850mg/Nm ³ and above, which is very unfavorable to environmental protection .

At present, the current sulfur recovery devices of domestic coal-to-natural gas projects mainly adopt the Claus+SCOT process, which includes sulfur recovery process, tail gas treatment process, and solvent regeneration process. Using the two-stage Claus process, the raw material gas and air (oxygen) are mixed and burned below the stoichiometric ratio, and the temperature reaches 1200°C.

2H ₂ S+3O ₂ ＝2SO ₂ +2H ₂ O(1)

2H ₂ S+SO ₂ ＝3S+2H ₂ O(2)

After that, the liquid sulfur is separated by the liquid sulfur separator, and the tail gas is sent to the incinerator for treatment, and the organic sulfur and trace sulfur vapor in it are converted into SO ₂ . Then mix with hydrogen and enter the hydrogenation reactor in the tail gas treatment process, reduce SO ₂ and COS to H ₂ S, absorb the H ₂ S in the diethanolamine solution, and burn the rest into SO ₂ in the tail gas incinerator for recovery After the residual heat, it is discharged from the chimney. In addition, a solvent regeneration process is required to regenerate the poor alcohol amine solution for recycling. The process is long, requires a lot of equipment, costs a lot, requires hydrogenation technology, has high requirements for safety control, and the sulfur recovery effect cannot meet the further improvement of environmental protection requirements. Therefore, there is an urgent need to find a better process method to reduce the tail gas SO ₂ emission of the sulfur recovery unit.

Contents of the invention

The purpose of this utility model is to solve the above-mentioned technical problems and provide a low-sulfur emission sulfur recovery system based on the Claus reaction system with small footprint, low operation cost and equipment investment, environmental friendliness and good tail gas treatment effect.

The utility model is based on the sulfur recovery system of the low-sulfur discharge of the Claus reaction system, which comprises the Claus reaction system. The tail gas outlet of the Claus reaction system is connected with the flue gas inlet of the desulfurization tower through an incinerator, a heat exchanger, and the top of the desulfurization tower There is a flue gas outlet, a flue gas inlet at the lower part, and a slurry outlet at the bottom. The tower body is composed of an upper washing section, a middle absorption section and a lower concentration section.

The upper part of the water washing section of the desulfurization tower is provided with a clean water spray head, and the lower part is provided with a waste ammonia water inlet.

A high-temperature flue gas inlet is also provided on the pipeline connected between the flue gas inlet of the desulfurization tower and the heat exchanger.

The pipeline between the high-temperature flue gas inlet and the flue gas inlet of the desulfurization tower is lined with a VEGF flake cement anti-corrosion layer.

The process of the utility model is that the acid raw material gas enters the Claus reaction system for reaction, and the tail gas obtained after the reaction is sent to the incinerator for incineration, so that the tail gas is converted into flue gas containing SO ₂ , and the flue gas containing SO ₂ is heat-exchanged After the waste heat is recovered by the flue gas inlet, it is sent to the concentration section at the lower part of the desulfurization tower, where it exchanges heat with dilute thiamine to cool down in the concentration section, and then enters the middle absorption section of the desulfurization tower upwards, where SO ₂ in the flue gas reacts with ammonia water to form thiamine. The reacted liquid goes down into the concentration section and is discharged through the slurry outlet, and the reacted gas goes up into the water washing section at the upper part of the ammonia desulfurization tower, where the liquid entrained in the flue gas is removed and discharged from the top flue gas outlet after cooling down.

The flue gas containing SO ₂ is mixed with high-temperature flue gas after recovering waste heat through a heat exchanger, and then sent to the lower concentration section of the desulfurization tower.

Control the gas temperature after the flue gas containing SO2 is mixed with the high _- temperature flue gas to be 120-140°C.

The inventor analyzed the tail gas treatment process of the existing Claus reaction system, and found that the sulfur _- containing medium in the gas phase of the tail gas will be completely converted into SO2 after being incinerated by an incinerator, forming SO2 _- containing flue gas. This part of the flue gas has Following characteristics: 1: temperature is high, 800 ℃～900 ℃; ₂ , SO content is high (5%～30% mass percentage) in flue gas; Therefore desulfurization is key, for this problem, inventor considers for going out incinerator After the flue gas is recovered by the heat exchanger to cool down, the high-temperature flue gas is introduced into the pipeline for mixing, and then enters the lower concentration section of the desulfurization tower. Concentrated, the flue gas after cooling rises into the middle absorption section, and waste ammonia water is passed into the middle absorption section to react with SO ₂ in the flue gas to form thiamine (the reaction formula is xNH ₃ +H ₂ O+SO ₂ =(NH ₄ )xH ₂ -xSO ₃ ), the reacted liquid goes down into the concentration section, the gas goes up and is further washed by water and cooled down, and then discharged from the flue gas outlet at the top of the desulfurization tower. The slurry drawn from the export can be further processed to obtain thiamine as a by-product.

Control the temperature of the flue gas containing SO ₂ mixed with the high-temperature flue gas to be 120-140°C and the pressure to be 1500Pa. If the temperature is too low, acid condensation will occur to corrode the pipeline. Excessive temperature caused the anti-corrosion layer of VEGF flake cement lining the pipeline to fall off.

The high-temperature flue gas described in the utility model can be the boiler flue gas of the coal chemical plant, and the ammonia water can be the waste ammonia water that can be produced by the plant, which realizes the sustainable development strategy of turning waste into treasure, reduces waste discharge, and saves Processing costs.

Compared with the prior art, the utility model system saves the hydrogenation reaction and solvent regeneration device, reduces the consumption of electric energy, steam and solvent, and the tail gas is incinerated by the incinerator and directly introduced into the The ammonia method desulfurization tower greatly improves the safety of production, reduces the investment cost of equipment and energy consumption, and saves the occupied area. The recovery rate of SO ₂ in the process of the utility model is high, and the content of SO ₂ in the exhaust gas can be reduced to 100ppm Below, compared with the original design, the SO ₂ emission can be reduced by 301.8t/a~322t/a, while meeting the national regulations, limited air pollution is controlled.

Description of drawings

Fig. 1 is a schematic flow chart of the utility model.

In the figure: 1—Claus reaction system; 2—incinerator; 3—heat exchanger; 4—high temperature flue gas inlet, 5—flue gas inlet, 6—flue gas outlet, 7—desulfurization tower, 7.1—water washing section, 7.2-absorption section, 7.3-concentration section, 8-slurry outlet; 9-waste ammonia water inlet, 10-water spray head.

Detailed ways

Below in conjunction with accompanying drawing 1, the utility model is further explained:

As shown in Figure 1, the sulfur recovery system based on the low sulfur emission of the Claus reaction system includes the Claus reaction system 1, the tail gas outlet of the Claus reaction system 1 passes through the flue gas of the incinerator 2, the heat exchanger 3 and the desulfurization tower 7 The inlet 5 is connected, the top of the desulfurization tower 7 is provided with a flue gas outlet 6, the lower part is provided with a flue gas inlet 5, and the bottom is provided with a slurry outlet 8. The tower body is composed of an upper washing section 7.1, a middle absorption section 7.2 and a lower Condensed 7.3 segment composition. The upper section of the water washing section 7.1 of the desulfurization tower 7 is provided with a water spray head 10 for washing the flue gas from the absorption section 7.2, and the lower section is provided with a waste ammonia water inlet 9. A high-temperature flue gas inlet 4 is also provided on the pipeline connected between the flue gas inlet 5 of the desulfurization tower 7 and the heat exchanger 3 . The pipeline between the high-temperature flue gas inlet 4 and the flue gas inlet 5 of the desulfurization tower 7 is lined with a VEGF flake cement anti-corrosion layer.

crafting process:

The acid raw material gas enters the Claus reaction system 1 for reaction, most of the H ₂ S in the acid gas is converted into sulfur, and at the same time, the SO ₂ , COS and trace elemental sulfur vapor in the acid gas, the tail gas exiting the Claus reaction system continues to enter the incinerator 2 Carry out incineration to convert all the sulfur-containing medium into SO ₂ , and the incinerated flue gas containing SO ₂ (referred to as flue gas, 800°C-900°C, SO ₂ content obtained by calculation) enters the heat exchanger 4 for waste heat recovery and cooling to 80°C to 120°C, and then merged with high-temperature flue gas (temperature 120°C-250°C) from a coal chemical plant (control the temperature of the flue gas mixed with the high-temperature flue gas to be 120-140°C, and the gas volume to be 50349Nm ³ /h, SO ₂ content: 0.511% (v) is 13000mg/Nm ³ ), enters the lower concentration section 7.3 from the flue gas inlet 5 of the ammonia desulfurization tower 7, and the dilute thiamine in the concentration section 7.3 flows from the hot flue gas The heat is absorbed in the air for self-concentration, so that the temperature of the flue gas is reduced to 55-60°C; after passing through the concentration section, the flue gas enters the middle absorption section 7.2 of the ammonia desulfurization tower 7 upwards, and the SO ₂ in the flue gas is mixed with the waste ammonia water imported 9 The introduced waste ammonia reacts to generate thiamine, and then the flue gas enters the water washing section 7.1 on the upper part of the ammonia desulfurization tower 7, and is washed by the clean water sprayed from the clean water spray head 10 to remove the liquid entrained in the flue gas and reduce the temperature of the flue gas to 48 ~ 50 ℃, and finally discharged from the flue gas outlet 6 on the top. The thiamine slurry is drawn from the slurry outlet 8 at the bottom of the ammonia desulfurization tower 7, and sent to the subsequent thiamine post-processing unit to obtain thiamine products.

The content of SO ₂ in the flue gas discharged from the flue gas outlet 6 is reduced to below 100mg/Nm ³ , and the year-on-year emission is reduced by 301.8t/a-322t/a, which meets the requirements of national regulations and effectively controls the pollution of SO ₂ to the air. important practical significance.

Claims (4)

1. A sulfur recovery system based on the low sulfur emission of Claus reaction system, comprising Claus reaction system, it is characterized in that, the tail gas outlet of described Claus reaction system is connected with the flue gas inlet of desulfurization tower through incinerator, heat exchanger, The top of the desulfurization tower is provided with a flue gas outlet, the lower part is provided with a flue gas inlet, and the bottom is provided with a slurry outlet. The tower body is composed of an upper water washing section, a middle absorption section and a lower concentration section. 2. The sulfur recovery system based on the low-sulfur emission of the Claus reaction system according to claim 1, wherein the upper part of the water washing section of the desulfurization tower is provided with a clear water spray head, and the lower part is provided with a waste ammonia water inlet. 3. The sulfur recovery system based on the low-sulfur emission of the Claus reaction system according to claim 1, characterized in that: the pipeline connected between the flue gas inlet of the desulfurization tower and the heat exchanger is also provided with a high-temperature flue Gas import. 4. The sulfur recovery system based on Claus reaction system for low-sulfur emission according to claim 3, characterized in that: the pipeline between the high-temperature flue gas inlet and the flue gas inlet of the desulfurization tower is lined with a VEGF flake cement anti-corrosion layer.