Waste gas and waste liquid treatment and heat recovery system for preparing ethylene glycol from natural gas

Abstract

The invention discloses a natural gas-to-ethylene glycol waste gas and waste liquid treatment and heat recovery system which comprises an incineration system, a waste heat recovery system, an economizer, an induced draft fan and a smoke exhaust system which are sequentially connected in series through pipelines, and further comprises a denitration system. Waste gas and waste liquid generated in different working sections are conveyed into the incineration system through respective conveying pipelines to be incinerated to form carbon dioxide, water vapor and nitric oxide, and incinerated high-temperature gasified substances enter the waste heat recovery system and the economizer through suction force of the induced draft fan to be cooled. Meanwhile, nitric oxide in the high-temperature gasified substance is subjected to denitration treatment through the denitration system, and after non-toxic and harmless gasified substances are formed, the gasified substances are discharged outwards through the smoke exhaust system. The waste gas and waste liquid generated in the production process of preparing ethylene glycol from natural gas can be effectively incinerated to reach the emission standard, the generated heat can be recycled, and the waste gas and waste liquid incinerator is simple in used equipment, low in energy consumption, small in investment, green, environmentally friendly and low in production cost.

Description

Technical Field

[0001] The invention relates to the technical field of recovering waste gas and waste liquid from natural gas to produce ethylene glycol to generate steam, and in particular to a waste gas and waste liquid treatment and heat recovery system for natural gas to produce ethylene glycol. Background Art

[0002] Ethylene glycol (EG) includes monoethylene glycol, diethylene glycol and triethylene glycol. The ethylene glycol commonly referred to is monoethylene glycol (MEG). Ethylene glycol, also known as glycol and ethylene glycol, is a colorless, clear and viscous liquid. It is soluble in water, lower alcohols, glycerol, acetone, acetic acid, pyridine and aldehydes, slightly soluble in ether, and almost insoluble in products such as benzene, carbon disulfide, chloroform and carbon tetrachloride. Ethylene glycol is an important basic organic raw material for petrochemical industry. It is mainly used in the production of polyester fibers, antifreeze, unsaturated polyester resins, lubricants, plasticizers, non-ionic surfactants and explosives. In addition, it can also be used in coatings, photographic developers, brake fluids and inks. It is used as a solvent and medium for ammonium borate and used in the production of special solvents such as ethylene glycol ethers. It has a wide range of uses.

[0003] In recent years, with the rapid growth of global polyester product market consumption, the world's ethylene glycol production has developed rapidly. Domestic ethylene glycol production equipment is still the imported ethylene oxide / ethylene glycol joint production equipment, ethylene air direct oxidation method, in recent years, coal-to-ethylene glycol, natural gas-to-ethylene glycol demonstration projects and several pilot projects have also made phased progress in recent years. In addition, there are also several domestic projects that use biomass as raw materials to produce ethylene glycol. However, according to the operation of the currently built equipment, the products are mainly polyols,

[0004] At present, there are two main technical routes for the preparation of ethylene glycol: one is the petroleum route, which is mainly to produce ethylene oxide by gas-phase oxidation of ethylene on a silver catalyst, and then to produce ethylene glycol products by liquid-phase non-catalytic hydration. The advantages are mature technology and wide application; the other method is the natural gas to ethylene glycol technical route, which uses natural gas to make synthesis gas to prepare dimethyl oxalate, and then hydrogenates it to prepare ethylene glycol. With the increasing shortage of world oil resources and the shortage of oil resources, the route of synthesizing ethylene glycol using natural gas as raw material has attracted widespread attention. Considering the economic rationality of raw material selection and the composition of my country's energy structure, the use of natural gas to produce ethylene glycol is most suitable for my country's current situation.

[0005] However, the production process of ethylene glycol from natural gas will produce waste gas and waste liquid. These waste gas and waste liquid come from the conversion section, cryogenic section, DMO distillation section, ethylene glycol synthesis section, ethylene glycol distillation section, etc. At present, the waste gas is treated by incineration through a long-term burning torch. After incineration, carbon dioxide and water vapor are directly discharged to the outside, while the waste liquid is recycled or discharged after sewage treatment. The treatment cost is high. Once the treatment is not sufficient, it is easy to pollute the environment. Moreover, when the amount is large, the treatment is more difficult. Therefore, the waste gas and waste liquid generated in the preparation process of ethylene glycol from natural gas has not been effectively solved. Summary of the invention

[0006] In order to solve one or some technical problems existing in the prior art, the purpose of this application is to provide a natural gas to ethylene glycol waste gas and waste liquid treatment and heat recovery system, which can effectively incinerate the waste gas and waste liquid generated in the production process of natural gas to ethylene glycol to meet the emission standards, and can recycle the generated heat, with simple equipment, low energy consumption, low investment, green environmental protection and low production cost.

[0007] In order to solve the above existing technical problems, this application adopts the following technical solutions:

[0008] A waste gas and waste liquid treatment and heat recovery system for producing ethylene glycol from natural gas comprises an incineration system, a waste heat recovery system, an economizer, an induced draft fan and a smoke exhaust system which are sequentially connected in series through pipelines, and also comprises a denitration system. Waste gas and waste liquid generated in different sections are transported to the incineration system through respective transport pipelines for incineration to form carbon dioxide, water vapor and nitrogen oxides. The high-temperature gasified substances after incineration enter the waste heat recovery system and the economizer through the suction force of the induced draft fan for cooling. At the same time, the nitrogen oxides in the high-temperature gasified substances are denitrated through the denitration system to form non-toxic and harmless gasified substances which are then discharged to the outside through the smoke exhaust system.

[0009] Preferably, the incineration system includes an incinerator whose furnace wall is made of refractory castables, a plurality of pipeline interfaces arranged on the incinerator, a core burner arranged in the incinerator, and a blower arranged on one side of the incinerator. The incinerator forms a sealed insulated furnace chamber through the refractory castables, and the combustion temperature in the incinerator through the core burner is 1100°C to 1200°C. A nozzle is installed inside each of the pipeline interfaces, and the residence time of the waste in the furnace chamber from the nozzle outlet to the incinerator outlet is not less than 2.0s.

[0010] Preferably, the incinerator adopts a vertical cylindrical furnace, the pipeline interface ring is arranged at the upper end of the incinerator, the core burner is arranged at the top of the incinerator, and the internal furnace of the incinerator includes a flame furnace located at the upper part of the vertical cylindrical furnace in contact with the flame, and an oxidation furnace located at the lower part of the vertical cylindrical furnace without flame combustion, and the oxidation furnace adopts an L-shaped structure.

[0011] Preferably, the incinerator is provided with two blowers.

[0012] Preferably, the inner cavity of the incinerator generates negative pressure through the induced draft fan, and the operating negative pressure of the incinerator is between -20 and -200 KPa.

[0013] Preferably, the waste heat recovery system includes a first evaporation section, a second evaporation section, a third evaporation section, a fourth evaporation section and a steam heating device, the first evaporation section and the second evaporation section are provided with heat exchange fins, the third evaporation section and the fourth evaporation section are hollow pipe structures, and the liquid water in the steam heating device is used as an industrial steam power source after heat exchange and vaporization through the first evaporation section, the second evaporation section, the third evaporation section and the fourth evaporation section.

[0014] Preferably, the steam heating device includes a steam drum and a circulation pipeline arranged between the steam drum and each of the evaporation sections. The liquid in the steam drum enters the corresponding evaporation section from each of the circulation pipelines through the siphon principle, is heated and vaporized, and then uniformly flows back into the steam cavity of the steam drum.

[0015] Preferably, one side of the steam drum is also connected to a boiler water pipe, one end of which is connected to boiler water. The boiler water pipe passes through the economizer, and the hot water in the boiler water is heated and vaporized through the boiler water pipe and the economizer to form water vapor, which is then transported to the steam chamber as a power source for standby use.

[0016] Preferably, the denitrification system includes a SNCR denitrification spray gun, which is provided between the first evaporation section and the second evaporation section, and between the third evaporation section and the fourth evaporation section. The high-temperature nitrogen oxides cooled by the waste heat recovery system are denitrified by spraying ammonia water through the SNCR denitrification spray gun.

[0017] Preferably, an SCR system is also provided on the pipeline between the waste heat recovery system and the economizer, the temperature of the high-temperature waste passing through the SCR system is 300-330°, and the SCR system is used to spray catalyst on the high-temperature waste passing through for secondary denitrification.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The equipment used is simple, so it has low energy consumption, low investment, energy saving, high efficiency, and green environmental protection. In the process of incineration of harmful organic matter, it can effectively decompose harmful organic matter completely, greatly reducing the pollution of chemical enterprises, recovering heat to generate steam, while reducing production costs and enhancing product price advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a process flow chart of the present invention;

[0021] In the figure: 1. Oxidation furnace; 2. Blower; 3. Incineration system; 4. Incinerator; 5. Flame furnace; 6. Pipeline interface; 7. Core burner; 8. Denitrification system; 9. Waste heat recovery system; 10. Steam heating device; 11. Steam drum; 12. SNCR denitrification spray gun; 13. SCR system; 14. Smoke exhaust system; 15. induced draft fan; 16. Economizer; 17. Boiler water pipe; 18. Fourth evaporation section; 19. Third evaporation section; 20. Second evaporation section; 21. Circulation pipeline; 22. First evaporation section. DETAILED DESCRIPTION

[0022] Below, the present application is further described in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0023] In the description of the present application, it should be understood that the terms "up", "down", "left", "right", etc., indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0024] The terms "first", "second", etc. in this application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0025] like Figure 1As shown, a waste gas and waste liquid treatment and heat recovery system for producing ethylene glycol from natural gas includes an incineration system 33, a waste heat recovery system 99, an economizer 1616, an induced draft fan 1515 and a smoke exhaust system 1414 which are sequentially connected in series through pipelines, and also includes a denitration system 88. The waste gas and waste liquid generated in different sections are transported to the incineration system 33 through their respective transportation pipelines for incineration to form carbon dioxide, water vapor and nitrogen oxides. The high-temperature gasified substances after incineration enter the waste heat recovery system 99 and the economizer 1616 through the suction force of the induced draft fan 1515 for cooling. At the same time, the nitrogen oxides in the high-temperature gasified substances are denitrated by the denitration system 88 to form non-toxic and harmless gasified substances which are then discharged to the outside through the smoke exhaust system 1414.

[0026] At present, the waste gas and waste liquid in the natural gas production of ethylene glycol come from nitrogen-rich gas from cryogenic separation, PSA-H2 analysis gas from unit 56, tail gas from MN recovery tower, flash steam from low-pressure flash tank I, flash steam from low-pressure flash tank II, natural gas conversion stripping waste gas, flash steam from conversion and decarbonization unit, light fractions from DMC distillation section, heavy fractions from DMO distillation section, MF recovered from MF separation device, mixed alcohol esters (light glycols) from ethylene glycol distillation, heavy glycols from ethylene glycol distillation, and condensate from deep freezer of dealcoholization tower from ethylene glycol distillation. After analyzing the parameters of waste gas and waste liquid and the combustion characteristics of each component, and combining with the provisions of GB18484-2001 "Hazardous Waste Incineration Pollution Control Standard", a set of natural gas to ethylene glycol waste gas and waste liquid treatment system was designed for recycling and utilizing waste gas and waste liquid and heat. When treating the waste gas and waste liquid generated in the production process of natural gas to ethylene glycol, the original waste gas and waste liquid treatment process was changed, and the waste gas and waste liquid were directly transported to the incineration system 3 3 for high-temperature incineration, so that the waste gas and waste liquid are incinerated through the incineration system 3 3 to form high-temperature gasified substances such as carbon dioxide, water vapor and nitrogen oxides. The high-temperature gasified substances after incineration are directly transported backward through the pipeline through the suction force of the induced draft fan 15 15 to enter the waste heat recovery system 9 9 and the economizer 1616 for cooling. While cooling the high-temperature gasified substances through the waste heat recovery system 9 9 and the economizer 1616, it can also play a role in heat recovery and utilization, thereby avoiding the incineration system 3 3. The waste of heat generated by the incineration of waste gas and waste liquid. The economizer 1616 can also play a role in temperature control, so that the temperature entering the induced draft fan 1515 is 130-160°, avoiding damage to the induced draft fan 1515 due to excessive temperature. At the same time, the denitration system 88 can also be used to denitrate the nitrogen oxides in the high-temperature gasified material, so that the gas discharged to the pump through the smoke exhaust system 1414 is non-toxic and harmless gasified material. The entire waste gas and waste liquid treatment system uses simple equipment, low energy consumption, low investment, green environmental protection, and low production cost. It can effectively incinerate the waste gas and waste liquid generated in the production process of natural gas to ethylene glycol to meet the emission standards, effectively solving the high cost of direct incineration through a long-term burning torch in the existing waste gas treatment, high environmental thermal pollution, and high difficulty in waste liquid treatment. It also solves the problem of difficulty in rapid treatment when the waste gas and waste liquid treatment volume is large.

[0027] Further improved, the incineration system 33 includes an incinerator 44 whose furnace wall is a refractory castable, a plurality of pipeline interfaces 66 arranged on the incinerator 44, a core burner 77 arranged in the incinerator 44, and a blower 22 arranged on one side of the incinerator 44, the incinerator 44 forms a sealed insulated furnace chamber through the refractory castable, the combustion temperature in the incinerator 44 through the core burner 77 is 1100℃~1200℃, a nozzle is installed inside each of the pipeline interfaces 66, and the residence time of the waste in the furnace chamber from the nozzle outlet to the incinerator 44 outlet is not less than 2.0s.

[0028] The incinerator 44 is used for high-temperature incineration of waste gas and waste liquid. By adjusting the supply of fuel and combustion air, effective incineration is organized in the furnace and sufficient furnace temperature is established. Therefore, it is necessary to reasonably design the furnace structure, furnace size, and furnace volume to ensure the furnace volume heat load, flue gas flow rate and residence time, thereby ensuring that all components of the waste are completely burned and decomposed in the furnace. To this end, the incinerator 44 forms a sealed insulated furnace chamber through refractory castables, which can reduce heat loss and ensure a uniform furnace temperature field. The insulated furnace chamber is the main place for organic matter incineration and pyrolysis, and meets the requirements of uniform temperature field, flue gas turbulence and sufficient flue gas shutdown time to ensure that toxic and organic components are thoroughly and completely decomposed, so that the outer wall of the incinerator 44 can have better thermal insulation performance. The inner lining is made of refractory castables and lightweight insulating castables, and the parts that people can touch are not higher than 80°C to avoid burns. When treating waste gas and waste liquid, the incinerator 44 normally treats seven waste liquids and six waste gases. The waste gas and waste liquid to be treated are connected to each pipeline interface 66 through their own pipelines, and are injected into the incinerator 44 through the nozzle inside the pipeline interface 66. The injected waste gas and waste liquid are incinerated at high temperature through the core burner 77. Through direct incineration and high-temperature thermal oxidation, the toxic organic components in the waste gas and waste liquid are converted into harmless products. The combustion temperature of organic matter in the waste gas is generally 500°C, while the combustion temperature of waste liquid is about 800°C. In order to have a larger processing capacity, the combustion temperature of the core burner 77 is 1100°C to 1200°C. After the waste gas and waste liquid pass through the high temperature of 1100°C to 1200°C, when the waste gas and waste liquid are processed in large quantities, toxic and harmful substances can be prevented from escaping. The residence time of the waste in the furnace from the nozzle outlet to the outlet of the incinerator 44 is not less than 2.0s, and the temperature during this period is greater than 1100°C, which can give the organic matter enough time to decompose.

[0029] A further improvement is that the incinerator 44 adopts a vertical cylindrical furnace, the pipeline interface 66 is arranged in a ring at the upper end of the incinerator 44, the core burner 77 is arranged at the top of the incinerator 44, and the internal furnace of the incinerator 44 includes a flame furnace 55 located at the upper part of the vertical cylindrical furnace in contact with the flame, and an oxidation furnace 11 located at the lower part of the vertical cylindrical furnace without flame combustion, and the oxidation furnace 11 adopts an L-shaped structure.

[0030] The core burner 77 is installed at the top of the incinerator 44, and the flame furnace 55 in contact with the flame in the internal furnace of the incinerator 44, and the L-shaped oxidation furnace 11 located at the bottom of the vertical tube furnace without flame combustion, can make the core burner 77 and the furnace process the gas and waste flow relatively stable, so the flame, flue gas and other combustion conditions in the flame furnace 55 are also basically unchanged, and a safe and reliable combustion environment can be established in the furnace. A normal vertical tube furnace is a cylindrical structure. Under the same diameter and operating conditions, the time the injected waste gas and waste liquid stay in the cavity needs to be controlled according to the height of the inner cavity, resulting in a higher height requirement for the entire incinerator 44, or the need to reduce or adjust other parameters. In order to solve this problem, the inner cavity of the incinerator 44 is designed to be an L-shaped structure, wherein the core burner 77 is installed at the top of the incinerator 44, and the flame is sprayed downward, while the waste gas and waste liquid injected through the nozzle are sprayed into the burning flame in a tangential form, and each nozzle is individually equipped with air, which can make the combustion more complete and make the burned substances enter After the oxidation furnace 11, a residence time difference is formed through the L-shaped structure of the oxidation furnace 11, so that the entire combustion furnace can achieve an increase in the residence time of cavity objects at a lower height, and the overall structural design is simpler. In addition, the core burner 77 can spray from top to bottom through the structure, so that the heated and gasified substances can better float to the core burner 77 for full combustion, reduce heat loss, and ensure a uniform furnace temperature field. The insulated furnace is the main place for the incineration and pyrolysis of organic matter, which meets the uniform temperature field, flue gas turbulence and sufficient flue gas shutdown time to ensure that toxic and organic components are thoroughly and completely decomposed.

[0031] As a further improvement, two blowers 22 are provided on the incinerator 44 .

[0032] The two blowers 22 keep the injected waste gas and waste liquid in the incinerator 44 at a high turbulent speed, promoting flue gas mixing. At the same time, the high-strength refractory lining has an excellent heat preservation effect, forming an insulated furnace, so that the flue gas temperature is basically consistent on the same cross section. The 3T design and excessive oxygen content enable the organic matter to be completely decomposed, and the total CH emission meets the standard; the incinerator 44 is also equipped with measuring point interfaces such as sight glasses, manholes, thermocouples and pressure transmitters. The ratio of the air volume of the blower 22 to the natural gas feed volume is 15:1,

[0033] The inner cavity of the incinerator 44 generates negative pressure through the induced draft fan 15 15, and the operating negative pressure of the incinerator 44 is between -20 and -200 KPa.

[0034] In order to prevent high-temperature flue gas from leaking out, the incinerator 44 is operated at a negative pressure of -50 to -200 Pa, and the negative pressure in the furnace is controlled by the induced draft fan 1515. The above-mentioned staged combustion method allows the fuel, exhaust gas and waste liquid to be fully mixed with the air as soon as they are sprayed into the furnace, which is convenient for controlling the furnace temperature, thereby suppressing the generation of NOx and ensuring that the emission of nitrogen oxides meets the standard.

[0035] Further improved, the waste heat recovery system 9 9 includes a first evaporation section 22 23, a second evaporation section 2021, a third evaporation section 1920 and a fourth evaporation section 18 19 and a steam heating device 10 10, the first evaporation section 22 23 and the second evaporation section 2021 are provided with heat exchange fins, the third evaporation section 1920 and the fourth evaporation section 18 19 are hollow pipe structures, and the liquid water in the steam heating device 10 10 is used as an industrial steam power source after heat exchange and vaporization through the first evaporation section 22 23, the second evaporation section 2021, the third evaporation section 1920 and the fourth evaporation section 18 19.

[0036] In order to recover the heat in the flue gas after incineration, at the same time, the ethylene glycol production process also inevitably needs to use steam as a power device. Therefore, a waste heat recovery system 99 is installed at the outlet of the incinerator 44. The waste heat recovery system 99 consists of four groups of evaporation devices and steam heating devices 1010, wherein the first evaporation section 2223 and the second evaporation section 2021 are provided with heat exchange fins, and the heat of the high-temperature gasified material after incineration can be quickly absorbed by the heat exchange fins, and the steam heating device 1010 is heated and exchanged with the absorbed heat, thereby achieving the purpose of rapid cooling. When the high-temperature gasified material after incineration is cooled twice, the temperature is basically reduced to below 400°. At this time, the third evaporation section 1920 and the fourth evaporation section 18 19 simply adopt a combination of a hollow pipe structure and a steam heating device 10 10, which can effectively absorb and utilize the temperature inside the pipe, so that the heat of the high-temperature gasified material of thousands of degrees can be effectively recovered and utilized, avoiding the waste of heat energy. Through the combination of multiple evaporators and steam heating devices 10 10, the heat in the flue gas can be converted into steam heating energy, so that the heated steam can be used again as an industrial steam power source, which not only avoids the waste of heat energy in the flue gas, but also solves the energy loss problem of existing steam heating.

[0037] A further improvement is that the steam heating device 10 10 includes a steam drum 1111 and a circulation pipeline 2122 arranged between the steam drum 1111 and each of the evaporation sections. The liquid in the steam drum 1111 enters the corresponding evaporation section from each of the circulation pipelines 2122 through the siphon principle to be heated and vaporized and then uniformly flows back into the steam cavity of the steam drum 1111.

[0038] The steam heating device 10 10 is composed of a drum 1111 and four circulation pipelines 2122, wherein the liquid in the drum 1111 enters the corresponding evaporation section from each of the circulation pipelines 2122 through the siphon principle for heat energy conversion, thereby reducing the temperature of the exhaust gas, and converting the water vapor into steam through the heat energy in the flue gas and returning it to the steam cavity in the drum 1111 again, so that the liquid water in the bubbles is converted into steam and formed into a certain pressure for backward transportation. The pressure of the drum 1111 is 4.0Mpa.A, and the pressure level of the by-product steam is 1.7Mpa.A or 3.82Mpa.A. The steam heating device 10 is carried out through the waste heat recovery system 9 9 After the steam heat exchange of 10, the high-temperature flue gas produced by combustion can produce saturated steam of 207℃ and 1.7MpaG. The saturated steam of 207℃ is incorporated into the factory steam network. During the start-up phase of the device, the incinerator 44 is used as a power boiler to generate saturated steam of 3.82MPaG by burning natural gas for factory operation.

[0039] A further improvement is that a boiler water pipe 1717 is connected to one side of the steam drum 1111, one end of the boiler water pipe 1717 is connected to boiler water, the boiler water pipe 1717 passes through the economizer 1616, and the hot water in the boiler water is heated and vaporized by the boiler water pipe 1717 and the economizer 1616 to form water vapor, which is then transported to the steam chamber as a power source for standby use.

[0040] A boiler water pipe 1717 is also connected to one side of the steam drum 1111. The boiler water and the bubbles are connected in series through the boiler water pipe 1717, so that the boiler water can be heated again at a lower temperature to gasify the high-temperature hot water or water vapor to form water vapor and mix it into the steam formed by the steam heating device 10 10, which requires lower power for the boiler water, reduces energy loss, and reduces production costs.

[0041] A further improvement is that the denitrification system 88 includes a SNCR denitrification spray gun 1212, the SNCR denitrification spray gun 1212 is provided between the first evaporation section 2223 and the second evaporation section 2021, and the SNCR denitrification spray gun 1212 is provided between the third evaporation section 1920 and the fourth evaporation section 18 19, and the high-temperature nitrogen oxides cooled by the waste heat recovery system 9 9 are denitrified by spraying ammonia water through the SNCR denitrification spray gun 1212.

[0042] The high-temperature nitrogen oxides cooled by the waste heat recovery system 9 9 are denitrified by spraying ammonia water through the SNCR denitrification spray gun 1212, so that the discharged substances no longer contain toxic and harmful nitrogen oxides, thereby meeting the emission standards. The SNCR denitrification spray gun 1212 is respectively installed between the first evaporation section 22 23 and the second evaporation section 2021 and between the third evaporation section 1920 and the fourth evaporation section 18 19. The flow rate of ammonia water sprayed by the SNCR denitrification spray gun 1212 is 300-400KG. The setting of the two evaporation sections can better enable the ammonia water to denitrify the nitrogen oxides in the gas, avoiding the problem of incomplete denitrification.

[0043] As a further improvement, an SCR system 1313 is further provided on the pipeline between the waste heat recovery system 99 and the economizer 1616, and the temperature of the high-temperature waste passing through the SCR system 1313 is 300-330°, and the SCR system 1313 is used to spray catalyst on the high-temperature waste passing through for secondary denitration.

[0044] In order to completely remove NOx from the flue gas, a denitration system 88 is added to the tail of the incinerator 44, and an SCR denitration system is set between the waste heat recovery system 99 and the economizer 1616. In the normal treatment process, the denitration system 88 can achieve complete denitration. However, when the amount of waste gas and waste liquid to be treated suddenly increases, the entire system needs to be operated at full load for a short period of time. Due to the large total amount of high-temperature gasified substances after incineration, it is inevitable that the denitration system 88 has a certain amount of nitrogen oxides that are not completely denitrated. Simply adding an SNCR denitration spray gun 1212 is generally difficult to achieve a good effect. Therefore, in the waste heat recovery system 9 An SCR system 1313 is also added to the pipeline between 9 and the economizer 1616, wherein the temperature of the high-temperature waste at the installation end of the SCR system 1313 is 300-330°. When the SCR system 1313 is used to spray the catalyst on the passing high-temperature waste for secondary denitrification, the denitrification effect is better and can make up for the problem that some nitrogen oxides escaping from the SNCR denitrification system are difficult to completely denitrify.

[0045] The specific embodiments after adopting the above technical solution are as follows:

[0046] Embodiment 1:

[0047] Example 1 Operating parameters:

[0048] A system for treating waste gas and waste liquid from natural gas to ethylene glycol and recovering heat, the specific method is as follows: the temperature in the incinerator 44 is controlled at 500-700°C, the pressure is controlled at a slight negative pressure of -200KPa.A, the NOX generated by decomposing harmful organic matter in the waste gas is 2.5mg / m3, and the steam generated is:

[0049]

[0050] Taking the production capacity of 1.2 million tons / year of ethylene glycol produced from natural gas as an example, this method can effectively remove harmful organic matter.

[0051] Embodiment 2:

[0052] Example 2 Operating parameters:

[0053] A system for treating and recovering waste gas and waste liquid from natural gas to ethylene glycol, the specific method is as follows: the temperature in the incinerator 4 is controlled at 700-1000°C, the pressure is controlled at a slight negative pressure of -200KPa.A, and the harmful organic matter in the waste gas is decomposed to generate NO X 3.0 mg / m 3 , and the steam generated is:

[0054]

[0055] Embodiment 3:

[0056] A system for treating waste gas and waste liquid from natural gas to ethylene glycol and recovering heat. The specific method is as follows: the temperature in the incinerator 4 is controlled at 1100-1200°C, and the pressure is controlled at a slight negative pressure of -200KPa.A, and the NO generated by the decomposition of harmful organic matter in the waste gas is X 3.5 mg / m 3 , and the steam produced is:

[0057]

[0058] As shown by the results of the above specific embodiments 1 to 3, the amount of steam generated by embodiment 3 is greater than that of the other embodiments, and the treatment effect is better.

[0059] The above-mentioned implementation modes are only preferred implementation modes of the present application and cannot be used to limit the scope of protection of the present application. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present application shall fall within the scope of protection required by the present application.

Claims

1. A system for treating waste gas and waste liquid from natural gas to ethylene glycol and recovering heat, characterized in that: The invention comprises an incineration system (3), a waste heat recovery system (9), an economizer (16), an induced draft fan (15) and a smoke exhaust system (14) which are sequentially connected in series through pipelines, and also comprises a denitration system (8). Waste gas and waste liquid generated in different working sections are transported to the incineration system (3) through respective transport pipelines for incineration to form carbon dioxide, water vapor and nitrogen oxides. The high-temperature gasified material after incineration enters the waste heat recovery system (9) and the economizer (16) for cooling through the suction force of the induced draft fan (15). At the same time, the nitrogen oxides in the high-temperature gasified material are denitrated through the denitration system (8) to form non-toxic and harmless gasified material which is then discharged to the outside through the smoke exhaust system (14).

2. A natural gas to ethylene glycol waste gas and waste liquid treatment and heat recovery system according to claim 1, characterized in that: The incineration system (3) comprises an incinerator (4) whose furnace wall is made of refractory castable material, a plurality of pipeline interfaces (6) arranged on the incinerator (4), a core burner (7) arranged in the incinerator (4), and a blower (2) arranged on one side of the incinerator (4). The incinerator (4) forms a sealed and insulated furnace chamber through the refractory castable material. The combustion temperature in the incinerator (4) through the core burner (7) is 1100° C. to 1200° C. A nozzle is installed inside each of the pipeline interfaces (6). The residence time of the waste in the furnace chamber from the nozzle outlet to the incinerator (4) outlet is not less than 2.0 seconds.

3. A natural gas to ethylene glycol waste gas and waste liquid treatment and heat recovery system according to claim 2, characterized in that: The incinerator (4) is a vertical cylindrical furnace, the pipeline interface (6) is arranged in a ring at the upper end of the incinerator (4), the core burner (7) is arranged at the top of the incinerator (4), and the internal furnace of the incinerator (4) includes a flame furnace (5) located at the upper part of the vertical cylindrical furnace and in contact with the flame, and an oxidation furnace (1) located at the lower part of the vertical cylindrical furnace and burning without flames, and the oxidation furnace (1) adopts an L-shaped structure.

4. A natural gas to ethylene glycol waste gas and waste liquid treatment and heat recovery system according to claim 3, characterized in that: The incinerator (4) is provided with two blowers (2).

5. A natural gas to ethylene glycol waste gas and waste liquid treatment and heat recovery system according to claim 1, characterized in that: The inner cavity of the incinerator (4) generates negative pressure through the induced draft fan (15), and the operating negative pressure of the incinerator (4) is between -20 and -200 KPa.

6. A system for treating waste gas and waste liquid and recovering heat from natural gas to ethylene glycol according to any one of claims 1 to 5, characterized in that: The waste heat recovery system (9) comprises a first evaporation section (22), a second evaporation section (20), a third evaporation section (19), a fourth evaporation section (18) and a steam heating device (10); the first evaporation section (22) and the second evaporation section (20) are provided with heat exchange fins; the third evaporation section (19) and the fourth evaporation section (18) are hollow pipe structures; liquid water in the steam heating device (10) is vaporized by heat exchange through the first evaporation section (22), the second evaporation section (20), the third evaporation section (19) and the fourth evaporation section (18) and is used as an industrial steam power source.

7. A natural gas to ethylene glycol waste gas and waste liquid treatment and heat recovery system according to claim 6, characterized in that: The steam heating device (10) comprises a steam drum (11), and a circulation pipeline (21) provided between the steam drum (11) and each of the evaporation sections. Liquid in the steam drum (11) enters the corresponding evaporation section from each of the circulation pipelines (21) through the siphon principle, is heated and vaporized, and then uniformly flows back into the steam cavity of the steam drum (11).

8. A natural gas to ethylene glycol waste gas and waste liquid treatment and heat recovery system according to claim 7, characterized in that: A boiler water pipe (17) is also connected to one side of the steam drum (11), one end of which is connected to boiler water. The boiler water pipe (17) passes through the economizer (16). The hot water in the boiler water is heated and vaporized through the boiler water pipe (17) and the economizer (16) to form water vapor, which is then transported to the steam chamber as a power source for standby use.

9. A natural gas to ethylene glycol waste gas and waste liquid treatment and heat recovery system according to claim 6, characterized in that: The denitration system (8) comprises an SNCR denitration spray gun (12), wherein the SNCR denitration spray gun (12) is arranged between the first evaporation section (22) and the second evaporation section (20), and the SNCR denitration spray gun (12) is arranged between the third evaporation section (19) and the fourth evaporation section (18), and the high-temperature nitrogen oxides cooled by the waste heat recovery system (9) are denitrated by spraying ammonia water through the SNCR denitration spray gun (12).

10. A natural gas to ethylene glycol waste gas and waste liquid treatment and heat recovery system according to claim 9, characterized in that: An SCR system (13) is also provided on the pipeline between the waste heat recovery system (9) and the economizer (16). The temperature of the high-temperature waste passing through the SCR system (13) is 300-330°. The SCR system (13) is used to spray a catalyst on the high-temperature waste passing through for secondary denitration.

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