Sodium hydrosulfite tail gas pretreatment system

Abstract

The utility model provides a sodium hydrosulfite tail gas pretreatment system, which relates to the technical field of waste gas treatment, and comprises a precooler, a condenser and a gas-liquid separator, the precooler comprises a tail gas inlet, a precooled gas outlet and a separated gas inlet, the condenser comprises a precooled gas inlet and a condensed gas outlet, and the gas-liquid separator is arranged in the precooled gas inlet. The gas-liquid separator comprises a condensed gas inlet and a separated gas outlet, tail gas in the tail gas collecting device is discharged into the tail gas inlet through a pipeline, the pre-cooling gas outlet is connected with the pre-cooling gas inlet through a pipeline, the condensed gas outlet is connected with the condensed gas inlet through a pipeline, and the separated gas outlet is connected with the separated gas inlet through a pipeline. And the separated gas outlet is connected with the separated gas inlet through a pipeline. According to the sodium hydrosulfite tail gas pretreatment system, the sodium hydrosulfite tail gas amount and the content of VOCs gas such as methyl alcohol and ethylene oxide in the tail gas can be reduced, the emission index after tail gas treatment of an RTO system is reduced, and the hidden danger of environmental protection is eliminated.

Description

Technical Field

[0001] The utility model relates to the technical field of waste gas treatment, in particular to a hydrosulfite tail gas pretreatment system. Background Art

[0002] Sodium hydrosulfite, also known as sodium dithionite, is an inorganic compound typically present as a white crystalline powder. When exposed to air, sodium hydrosulfite readily absorbs oxygen, causing oxidation and agglomeration, producing a pungent, sour odor. It also readily absorbs moisture, generating heat and deteriorating. Its aqueous solution is unstable and is a strong reducing agent. It is widely used in the textile industry for reduction dyeing, reduction cleaning, printing, and bleaching, as well as for bleaching silk, wool, nylon, and other fabrics. Because it contains no heavy metals, bleached fabrics have a vibrant color and are resistant to fading. Sodium hydrosulfite is also used to bleach foods such as gelatin, sucrose, and preserved fruits, as well as soaps, animal and plant oils, bamboo products, and porcelain clay. Furthermore, it can be used as a reducing agent or bleaching agent in organic synthesis, such as in the production of dyes and pharmaceuticals. Due to its wide range of uses, it is in high industrial demand.

[0003] The sodium formate method is commonly used in the industry to produce hydrosulfite, which produces a large amount of tail gas. At present, the method of treating tail gas is mainly to add a tail gas collection device after the production is completed. The tail gas generated by each device is first collected and then a washing device is set up. The tail gas is directly discharged into the atmosphere after alkali washing. However, this treatment method does not take into account the problem of odor treatment. Therefore, an RTO furnace was subsequently introduced into the tail gas treatment system. After the tail gas generated by each device is collected and alkali washed, it is sent to the 1# RTO furnace (13000Nm 3 / h)、2#RTO furnace (30000Nm 3 / h) for incineration, and the odor problem on site has been greatly improved.

[0004] However, after the two RTO furnaces were put into operation, as the production of hydrosulfite gradually increased, the exhaust gas volume and the content of VOCs such as methanol and ethylene oxide in the exhaust gas gradually increased. Moreover, the last-stage ammonia condenser in the device could only condense the exhaust gas temperature to -10°C, which was unable to effectively reduce the content of VOCs such as methanol and ethylene oxide in the exhaust gas. After multiple, multi-point, and multi-time analysis of the hydrosulfite exhaust gas, the content of VOCs such as methanol and ethylene oxide in the exhaust gas was found to be as high as 100,000 mg / m 3 , seriously affecting the safe operation of the two RTO furnaces and the emission indicators after treatment. Therefore, the utility model discloses a hydrosulfite tail gas pretreatment system that can effectively reduce the content of VOCs gases such as methanol and ethylene oxide in the tail gas. Utility Model Content

[0005] (1) Technical problems solved

[0006] In view of the shortcomings of the existing technology, the utility model provides a hydrosulfite tail gas pretreatment system, which solves the technical problem that the existing tail gas treatment system cannot reduce the VOCs gas content such as methanol and ethylene oxide in the tail gas to below the index.

[0007] (2) Technical solution

[0008] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0009] The hydrosulfite tail gas pretreatment system includes a precooler, a condenser and a gas-liquid separator. The precooler includes a tail gas inlet, a precooling gas outlet and a separation gas inlet. The condenser includes a precooling gas inlet and a condensation gas outlet. The gas-liquid separator includes a condensation gas inlet and a separation gas outlet. The tail gas in the tail gas collection device is discharged into the tail gas inlet through a pipeline. The precooling gas outlet is connected to the precooling gas inlet through a pipeline. The condensation gas outlet is connected to the condensation gas inlet through a pipeline. The separation gas outlet is connected to the separation gas inlet through a pipeline.

[0010] Preferably, the precooler further includes a precooling separation gas outlet, and the precooling separation gas outlet is connected to the RTO furnace through a pipeline.

[0011] Preferably, the bottoms of the precooler, the condenser and the gas-liquid separator are all provided with condensate discharge outlets, and the condensate discharge outlets are collected to a condensate collection device through a pipeline and then lead to a delivery pump.

[0012] Preferably, the tail gas enters the precooler at a pressure of 0-0.7 kPa and a temperature of 35-40°C, and the tail gas exits the precooler at a pressure of 0-0.7 kPa and a temperature of 25-30°C.

[0013] Preferably, after the tail gas is precooled into pre-cooled gas by the precooler, the pressure of the tail gas entering the condenser is 0-0.7 kPa and the temperature is 25-30°C. The pressure of the tail gas discharged from the condenser is 0-0.7 kPa and the temperature is -10-18°C.

[0014] Preferably, the condensation temperature in the condenser is set to -20°C.

[0015] Preferably, after the tail gas is secondary condensed into condensed gas by the condenser, the pressure entering and exiting the gas-liquid separator is 0-0.7 kPa and the temperature is -10-18°C.

[0016] Preferably, a transmission pump is provided between the gas-liquid separator and the precooler.

[0017] Preferably, the pressure of the separated gas condensed again by the precooler before entering the RTO furnace is 0-0.7kPa, the temperature is 10-20℃, and the flow rate does not exceed 4000Nm 3 / h.

[0018] Preferably, before the tail gas enters the system, the VOCS (methanol) content therein is 2.5%. After condensation by the precooler and the condenser, 0.8% remains. After further treatment by the gas-liquid separator, the VOCS (methanol) removal rate reaches 70%.

[0019] (3) Beneficial effects

[0020] The utility model provides a hydrosulfite tail gas pretreatment system. Compared with the existing technology, it has the following advantages:

[0021] 1. Environmental benefits: The hydrosulfite tail gas pretreatment system of this utility model can reduce the amount of hydrosulfite tail gas and the content of VOCs gases such as methanol and ethylene oxide in the tail gas, reduce the emission indicators of the RTO system after tail gas treatment, eliminate environmental risks, greatly reduce the pressure of production to respond to environmental inspections, and at the same time protect the occupational health of employees.

[0022] 2. Safety benefits: The hydrosulfite tail gas pretreatment system of the present invention reduces the content of VOCs gases such as methanol and ethylene oxide in the hydrosulfite tail gas, thereby essentially reducing the hidden dangers of safe operation of the RTO furnace.

[0023] 3. Economic benefits: The total investment of the hydrosulfite tail gas pretreatment system of this utility model is RMB 491,000, and it can save RMB 771,800 per year after its implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 Schematic diagram of the overall structure of an embodiment of the present invention.

[0026] Among them, 1. Precooler; 11. Exhaust gas inlet; 12. Precooling gas outlet; 13. Separation gas inlet; 14. Precooling separation gas outlet; 2. Condenser; 21. Precooling gas inlet; 22. Condensate gas outlet; 3. Gas-liquid separator; 31. Condensate gas inlet; 32. Separation gas outlet; 33. Condensate outlet; 4. Pipeline; 5. Transmission pump. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0028] The embodiment of the present application solves the technical problem that the existing exhaust gas treatment system cannot reduce the content of VOCs gases such as methanol and ethylene oxide in the exhaust gas to below the target by providing a hydrosulfite exhaust gas pretreatment system.

[0029] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0030] Example:

[0031] like Figure 1 As shown, the hydrosulfite tail gas pretreatment system includes a precooler 1, a condenser 2, a gas-liquid separator 3, a pipeline 4 and a transmission pump 5.

[0032] The precooler 1 includes an exhaust gas inlet 11 , a precooling gas outlet 12 , a separation gas inlet 13 and a precooling separation gas outlet 14 .

[0033] The condenser 2 includes a pre-cooling air inlet 21 and a condensed air outlet 22 .

[0034] The gas-liquid separator 3 includes a condensed gas inlet 31 , a separated gas outlet 32 ​​, and a condensed liquid outlet 33 .

[0035] The tail gas inlet 11 is connected to the tail gas collection device through the pipeline 4. The tail gas in the tail gas collection device enters the precooler 1 through the tail gas inlet 11. The pressure of the tail gas entering the precooler 1 is 0-0.7kPa and the temperature is 35-40°C. After being precooled into pre-cooled air by the precooler 1, the temperature drops to 25-30°C.

[0036] The pre-cooled air is discharged from the pre-cooler 1 through the pre-cooled air outlet 12, and the pressure when discharged is 0-0.7 kPa and the temperature is 25-30°C.

[0037] The pre-cooling air is transported to the pre-cooling air inlet 21 of the condenser 2 through the pipeline 4, and enters the condenser 2 for secondary condensation into condensed air. The condensation temperature in the condenser 2 is set to -20°C, and the pressure of the condensed air discharged from the condenser 2 is 0-0.7kPa and the temperature is -10-18°C.

[0038] Before the tail gas enters the system, the VOCS (methanol) content is 2.5%. After condensation in the precooler 1 and the condenser 2, 0.8% remains.

[0039] The condensed gas enters the gas-liquid separator 3 through the condensed gas inlet 31 on the gas-liquid separator 3 for gas-liquid separation. The VOCS (methanol) removal rate after separation reaches 70%. The pressure of the condensed gas entering and exiting the gas-liquid separator 3 is 0-0.7 kPa and the temperature is -10-18°C.

[0040] After the separated gas is discharged from the separated gas outlet 32, it is transported back to the precooler 1 through the transmission pump 5, enters the precooler 1 through the separated gas inlet 13 on the precooler 1, and is precooled again in the precooler 1 and discharged into the RTO furnace through the precooled separated gas outlet 14. The pressure of the separated gas condensed again in the precooler 1 before entering the RTO furnace is 0-0.7kPa, the temperature is 10-20℃, and the flow rate does not exceed 4000Nm 3 / h.

[0041] The implementation principle of the present invention is as follows: the tail gas is first passed into the precooler 1 for primary condensation, the temperature of which drops to 25-30°C, then passes through the condenser 2 for secondary condensation, the temperature of which drops to -10-18°C, and then passes through the gas-liquid separator 3 for gas-liquid separation, which can effectively pre-remove the VOCs gas content such as methanol and ethylene oxide in the tail gas.

[0042] In summary, compared with the existing technology, the present invention has the following beneficial effects:

[0043] 1. Environmental benefits: The hydrosulfite tail gas pretreatment system of this utility model can reduce the amount of hydrosulfite tail gas and the content of VOCs gases such as methanol and ethylene oxide in the tail gas, reduce the emission indicators of the RTO system after tail gas treatment, eliminate environmental risks, greatly reduce the pressure of production to respond to environmental inspections, and at the same time protect the occupational health of employees.

[0044] 2. Safety benefits: The hydrosulfite tail gas pretreatment system of the present invention reduces the content of VOCs gases such as methanol and ethylene oxide in the hydrosulfite tail gas, thereby essentially reducing the hidden dangers of safe operation of the RTO furnace.

[0045] 3. Economic benefits: The total investment of the hydrosulfite tail gas pretreatment system of this utility model is RMB 491,000, and it can save RMB 771,800 per year after its implementation.

[0046] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0047] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A hydrosulfite tail gas pretreatment system, characterized in that: The invention comprises a precooler (1), a condenser (2) and a gas-liquid separator (3); the precooler (1) comprises an exhaust gas inlet (11), a precooling gas outlet (12) and a separation gas inlet (13); the condenser (2) comprises a precooling gas inlet (21) and a condensing gas outlet (22); the gas-liquid separator (3) comprises a condensing gas inlet (31) and a separation gas outlet (32); the exhaust gas in the exhaust gas collecting device is discharged into the exhaust gas inlet (11) through a pipe (4); the precooling gas outlet (12) is connected to the precooling gas inlet (21) through a pipe (4); the condensing gas outlet (22) is connected to the condensing gas inlet (31) through a pipe (4); and the separation gas outlet (32) is connected to the separation gas inlet (13) through a pipe (4).

2. The hydrosulfite tail gas pretreatment system according to claim 1, characterized in that: The precooler (1) further comprises a precooling separation gas outlet (14), and the precooling separation gas outlet (14) is connected to the RTO furnace via a pipeline (4).

3. The hydrosulfite tail gas pretreatment system according to claim 1, characterized in that: The bottoms of the precooler (1), the condenser (2), and the gas-liquid separator (3) are all provided with condensate outlets (33), and the condensate outlets (33) are collected to a condensate collecting device through a pipeline (4) and then flow into a delivery pump.

4. The hydrosulfite tail gas pretreatment system according to claim 1, characterized in that: The tail gas enters the precooler (1) at a pressure of 0-0.7 kPa and a temperature of 35-40°C, and the tail gas exits the precooler (1) at a pressure of 0-0.7 kPa and a temperature of 25-30°C.

5. The hydrosulfite tail gas pretreatment system according to claim 1, characterized in that: After the tail gas is pre-cooled by the pre-cooler (1) to become pre-cooled gas, the pressure of the tail gas entering the condenser (2) is 0-0.7 kPa and the temperature is 25-30°C. The tail gas is discharged from the condenser (2) with a pressure of 0-0.7 kPa and a temperature of -10-18°C.

6. The hydrosulfite tail gas pretreatment system according to claim 5, characterized in that: The condensation temperature in the condenser (2) is set to -20°C.

7. The hydrosulfite tail gas pretreatment system according to claim 1, characterized in that: After the tail gas is secondary condensed into condensed gas by the condenser (2), the pressure of the tail gas entering and exiting the gas-liquid separator (3) is 0-0.7 kPa and the temperature is -10-18°C.

8. The hydrosulfite tail gas pretreatment system according to claim 1, characterized in that: A transmission pump (5) is provided between the gas-liquid separator (3) and the precooler (1).

9. The hydrosulfite tail gas pretreatment system according to claim 1, characterized in that: The pressure of the separated gas condensed again by the precooler (1) before entering the RTO furnace is 0-0.7kPa, the temperature is 10-20℃, and the flow rate does not exceed 4000Nm 3 / h.

10. The hydrosulfite tail gas pretreatment system according to claim 1, characterized in that: Before the tail gas enters the system, the VOCS (methanol) content therein is 2.5%. After condensation by the precooler (1) and the condenser (2), 0.8% remains. After further treatment by the gas-liquid separator (3), the VOCS (methanol) removal rate reaches 70%.

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