System for recycling pressure swing adsorption desorption gas in ethylene glycol synthesis

Abstract

The utility model discloses a system for recycling pressure swing adsorption desorbed gas in ethylene glycol synthesis, which comprises a pressure swing adsorption desorbed gas buffer tank, a desorbed gas supercharger and a conversion system, an outlet of the pressure swing adsorption desorbed gas buffer tank is connected with the desorbed gas supercharger, the desorbed gas supercharger is connected with the conversion system, and the conversion system comprises a conversion furnace. After pressure swing adsorption desorption gas is pressurized, separation is carried out through a conversion system, fresh hydrogen and purge gas are obtained, and recycling of hydrogen is achieved; according to the utility model, the transformation system is arranged to convert the pressure swing adsorption desorption gas into hydrogen, so that the waste gas is recycled, the emission of pollutants can be reduced, and the air quality can be improved. Meanwhile, waste gas recycling can reduce energy consumption and reduce waste treatment cost, so that the overall production cost is reduced, and economic benefits are improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of ethylene glycol factory, specifically relates to a kind of ethylene glycol synthesis in pressure swing adsorption analysis gas recycling system. BACKGROUND

[0002] In ethylene glycol factory synthesis section, after being treated, the pressure swing adsorption analysis gas in analysis gas buffer tank will be sent into waste gas waste liquid incineration equipment, then into incinerator for incineration, then heat exchange with medium-pressure boiler feed water, refer to Figure 1 .

[0003] In this process, 5 to 6 tons per hour of 3.5Mpa steam is generated, which is transported to steam pipe network. Through the analysis of the gas component, it is found that it is mainly composed of 93% to 97% hydrogen and about 2% nitrogen, working at 30kPa pressure and 1900Nm 3 / h flow.

[0004] Gas plant analysis gas inlet pressure is strictly controlled to be less than 20kpa, and the amount is maintained at 26000Nm 3 / h, after being compressed by gas plant analysis gas, it will be sent to shift system. The design processing capacity of two compressors equipped in the plant can reach 62000Nm 3 / h, and the maximum load in actual operation is 52000Nm 3 / h.

[0005] Waste gas incineration needs continuous fuel supply to maintain combustion temperature, and the cost will increase significantly. At high temperature, waste gas incineration may produce nitrogen oxides, and incomplete combustion may cause some harmful substances to be released into the environment. INVENTION CONTENTS

[0006] In order to overcome the problem of nitrogen oxides produced by waste gas incineration in the prior art, which affects the environment, the purpose of the utility model is to provide a kind of ethylene glycol synthesis in pressure swing adsorption analysis gas recycling system.

[0007] In order to achieve the above-mentioned purpose, the utility model adopts the following technical solutions:

[0008] A kind of ethylene glycol synthesis in pressure swing adsorption analysis gas recycling system, including pressure swing adsorption analysis gas buffer tank, analysis gas booster and shift system, wherein the outlet of pressure swing adsorption analysis gas buffer tank is connected with analysis gas booster, analysis gas booster is connected with shift system, and shift system includes shift furnace.

[0009] Further, the shift system specifically includes gas-liquid separator first shift furnace and second shift furnace; gas-liquid separator is connected with first shift furnace, and first shift furnace is connected with second shift furnace.

[0010] Further, a first raw gas preheater is arranged between the gas-liquid separator and the first shift converter.

[0011] Further, a steam heater is arranged between the first raw gas preheater and the first shift converter.

[0012] Further, a crude gas filter is arranged between the steam heater and the first shift converter.

[0013] Further, the crude gas filter inlet temperature T is set to 225℃ < T < 250℃, the crude gas filter upper temperature < 250℃, and the crude gas filter lower temperature < 250℃.

[0014] Further, the shift system further comprises a cooler, and the second shift converter is connected with the cooler.

[0015] Further, the shift system further comprises an ammonia washing tower, and the cooler is connected with the ammonia washing tower.

[0016] Further, a second raw gas preheater is arranged between the first shift converter and the second shift converter.

[0017] Further, the bed temperature in the first shift converter is set to 230-320℃, and the pressure difference is < 150Kpa; and the bed temperature in the second shift converter is set to 190-250℃, and the pressure difference is < 150Kpa.

[0018] Compared with the prior art, the present application has the beneficial effects of:

[0019] In the present application, the pressure swing adsorption desorption gas is converted into hydrogen by the shift system, the waste gas is reused, the emission of pollutants is reduced, the air quality is improved, the energy consumption is reduced, the waste treatment cost is reduced, the overall production cost is reduced, the economic benefit is improved, the principle of green economy and circular economy is met, the process of sustainable development is promoted, and the long-term negative impact on the environment is reduced.

[0020] Further, the gas filtered by the crude gas filter reacts with H2O to generate CO2 and H2 under the action of a cobalt-molybdenum catalyst in the first shift converter, and 98% of hydrogen can be recovered.

[0021] Further, the present application is provided with an ammonia washing tower, ammonia is removed by liquid absorption method, and the liquid after ammonia removal can be sent to a downstream low-temperature methanol washing unit. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a processing flow diagram of the pressure swing adsorption desorption gas in the prior art.

[0023] Figure 2 It is a schematic view of the variable pressure adsorption desorption gas recycling system in the ethylene glycol synthesis of the utility model;

[0024] Figure 3 It is a structural schematic view of the conversion system in the utility model;

[0025] In the figure, 1 is a variable pressure adsorption desorption gas buffer tank, 2 is a gas plant desorption gas booster, 3 is a conversion system, 4 is a gas-liquid separator, 5 is a first raw material gas preheater, 6 is a steam heater, 7 is a crude coal gas filter, 8 is a first conversion furnace, 9 is a second raw material gas preheater, 10 is a second conversion furnace, 11 is a cooler, and 12 is an ammonia washing tower. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the utility model, the utility model will be described more fully below with reference to the relevant drawings. The preferred embodiments of the utility model are shown in the drawings. However, the utility model can be realized in various different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the utility model more thorough and comprehensive.

[0027] The advantage of directly utilizing waste gas in the utility model is that energy consumption can be reduced, waste emissions can be reduced, and economic benefits can be created.

[0028] According to the requirements of the gas plant, the technical improvement hydrogen component concentration meets the gas component requirements of the gas plant compressor inlet.

[0029] The improvement of the utility model lies in that a new pipeline and a regulating valve group are added to the waste gas and liquid incineration buffer tank, and the variable pressure adsorption desorption gas of the ethylene glycol synthesis section is sent to the gas plant desorption gas inlet.

[0030] Referring to Figure 2 The variable pressure adsorption desorption gas recycling system in the ethylene glycol synthesis of the utility model comprises a variable pressure adsorption desorption gas buffer tank 1, the outlet of the variable pressure adsorption desorption gas buffer tank 1 is connected with a desorption gas booster 2, and the desorption gas booster 2 is connected with a conversion system 3.

[0031] Referring to Figure 3 The conversion system 3 comprises, in sequence, a gas-liquid separator 4, a first raw material gas preheater 5, a steam heater 6, a crude coal gas filter 7, a first conversion furnace 8, a second raw material gas preheater 9, a second conversion furnace 10, a cooler 11, and an ammonia washing tower 12.

[0032] The variable pressure adsorption desorption gas recycling method in the ethylene glycol synthesis of the utility model comprises the following steps:

[0033] The pressure swing adsorption desorption gas in the pressure swing adsorption desorption gas buffer tank 1 is pressurized by the desorption gas booster 2, separated by the shift system 3, and fresh hydrogen gas and purge gas are obtained, so as to realize the recycling of hydrogen gas.

[0034] Specifically, the desorption gas in the outlet of the pressure swing adsorption desorption gas buffer tank 1 is transported to the raw gas preheater after gas-liquid separation by the gas-liquid separator 4, preheated to 235-250°C, then transported to the steam heater 6, heated to 310°C, then transported to the crude gas filter 7, and a small amount of dust is filtered out, the inlet temperature T of the crude gas filter 7 satisfies 225°C

[0035]

[0036] The bed temperature in the first shift converter 8 is controlled at 230-320°C, and the pressure difference is controlled to be less than 150 Kpa; the reaction heat is removed in the form of byproduct 3.5 MPaG saturated steam, the temperature of the shift gas at the outlet of the first shift converter 8 is controlled at 260-290°C, the CO dry basis content is reduced to 6.0 vol% or less, and the shift gas leaving the first shift converter 8 is transported into the second shift converter 10 after being controlled at 230-250°C by the second raw gas preheater 9, and deep shift reaction is carried out with the cobalt-molybdenum catalyst, the bed temperature of the second shift converter 10 is controlled at 190-250°C, the pressure difference is controlled to be less than 150 Kpa, the shift reaction heat is removed in the form of byproduct 0.5 MPaG saturated steam, the temperature of the shift gas at the outlet of the second shift converter 10 is controlled at 190-205°C, and the CO dry basis content is reduced to 1.3 vol% or less; finally, it is sequentially cooled to 40°C by the low-pressure steam generator (byproduct 0.5 MPaG saturated steam), the condensate preheater, the desalted water preheater, and the cooler 11, and finally sent to the downstream low-temperature methanol washing unit (799346 Nm 3 / h (dry basis), <45°C, 3.35-3.8 MPaG, H2: 57.44%, CO2: 40.54%, CO (dry basis): <1.3%, H2S: 0.12%, NH3≤2 ppm) after ammonia removal by cold sealing water (>13 m3 / h) in the ammonia washing tower 12.

[0037] The low-temperature condensate discharged from the tower kettle of the ammonia washing tower 12 is preheated to about 90 DEG C by a low-temperature condensate preheater, and then enters the stripping tower to be stripped by 0.5 MPaG low-pressure saturated steam to remove ammonia. The kettle liquid of the low-temperature condensate preheater is pressurized to above 1.7 MPaG by a stripping tower kettle pump and sent to an external gasification device. The gas at the top outlet of the ammonia washing tower 12 is cooled by the low-temperature condensate preheater and a stripping waste gas cooler 11, and then enters a gas-liquid separator 4 to separate, the stripping acid gas is sent to a power station boiler for treatment, and the condensate is pressurized to 0.7 MPaG by a low-temperature condensate pump and returned to the stripping tower for continuous ammonia removal.

[0038] The recycling system can improve the CO conversion rate.

[0039] The technical scheme of the utility model belongs to the first implementation case in the ethylene glycol industry, and the utility model changes the label of the resolved gas waste gas in the industry by recycling the pressure swing adsorption resolved gas, which is beneficial to the process optimization and energy saving of the industry.

[0040] Example 1

[0041] The pressure swing adsorption resolved gas recycling system is used for recycling in the ethylene glycol synthesis.

[0042] The ethylene glycol device is provided with two sets of incineration systems and one set of flue gas treatment system. The annual operation time is 8000h, the operation flexibility is 60-110%, the annual operation days are >330 days, and the operation time per day is 24h.

[0043] The processing capacity of a single incinerator of the incineration system is as follows: ethylene glycol purge gas hydrogen recovery system resolved gas (hydrogen recovery section) 1900Nm 3 / h, this part is the resolved gas recycled by the utility model; MN recovery tower tail gas (MN recovery section) 7706Nm 3 / h; ethylene glycol synthesis section low-pressure flash tank flash gas (ethylene glycol synthesis section) normal 150Nm 3 / h, maximum 330Nm 3 / h; VOCs emission gas 2100Nm 3 / h; DMC light fraction (DMC recovery section) 2576kg / h; DMO heavy component (DMO rectification section) 1414kg / h; DMC heavy component (DMC recovery section) 240kg / h; recovered MF (DMO rectification section) 1739kg / h; ethylene glycol flare condensate 200kg / h; and light and heavy sludge oil added.

[0044] After the technical improvement is implemented, the benefits of the project mainly come from the benefits of hydrogen recovery, and the project cost mainly comes from the cost generated by the reduction of S2S (i.e. 3.5 MPa steam) of the waste heat boiler by-product steam. Therefore, the project cost details are as follows:

[0045] 1, 94% hydrogen, gas volume is 1900Nm 3 / h to the gas plant, the gas plant can recover 98% of hydrogen, then

[0046] Hydrogen revenue = 1900x8000x0.80x0.94x0.98 = 1120 million yuan / year;

[0047] 2, the expected reduction in S2S output after the implementation of technical transformation 5t / h, then

[0048] S2S steam reduction costs = 5x8000x93.56 = 374 million yuan / year;

[0049] 3, the annual revenue of the project

[0050] The comprehensive income = hydrogen revenue - S2S steam reduction costs = 746 million yuan / year;

[0051] If the technical transformation is completed, it can be long-term increase of 1000Nm 3 / h to the air exhaust fuel gas, waste gas incineration section can produce 3.5Mpa steam 2 tons / h.

[0052] S2S steam revenue: 2x8000x93.56 = 149.6 million yuan / year;

[0053] Long-term increase of 1000Nm 3 / h to the air exhaust fuel gas comprehensive income is 895.6 million yuan.

[0054] 4, the standard of taking fees

[0055] 1, hydrogen: 0.80 yuan / NM 3 ;

[0056] 2, steam 3.5MPa(G): 93.56 yuan / ton.

[0057] 3, 1kg standard coal = 2.493kgCO2;

[0058] 4, 1 tons of steam consumption of 110kg fuel coal.

[0059] The above only on the best embodiment of the utility model is explained, but can not be understood as the limitation of claims. The utility model is not limited to the above embodiments, the specific structure allows changes. Any changes made within the scope of the utility model independent claims are within the scope of the utility model.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

Claims

1. A system for recovering and reusing a purge gas from a pressure swing adsorption in the synthesis of ethylene glycol, characterized in that, The system comprises a pressure swing adsorption desorption gas buffer tank (1), a desorption gas booster (2) and a shift system (3), wherein the outlet of the pressure swing adsorption desorption gas buffer tank (1) is connected with the desorption gas booster (2), the desorption gas booster (2) is connected with the shift system (3), and the shift system comprises a shift converter.

2. The system for recovering and reusing the pressure swing adsorption desorption gas in the ethylene glycol synthesis according to claim 1, characterized in that, The shift system specifically comprises a gas-liquid separator (4), a first shift converter (8) and a second shift converter (10), wherein the gas-liquid separator (4) is connected with the first shift converter (8), and the first shift converter (8) is connected with the second shift converter (10).

3. The system for recovering and reusing the pressure swing adsorption desorption gas in the ethylene glycol synthesis according to claim 2, characterized in that, A first raw material gas preheater (5) is arranged between the gas-liquid separator (4) and the first shift converter (8).

4. The system for recovering and reusing the pressure swing adsorption desorption gas in the ethylene glycol synthesis according to claim 3, characterized in that, A steam heater (6) is arranged between the first raw material gas preheater and the first shift converter (8).

5. The system for recovering and reusing the pressure swing adsorption desorption gas in the ethylene glycol synthesis according to claim 4, characterized in that, A crude gas filter (7) is arranged between the steam heater (6) and the first shift converter (8).

6. The system for recovering and reusing the pressure swing adsorption desorption gas in the ethylene glycol synthesis according to claim 5, characterized in that, The inlet temperature T of the crude gas filter (7) is set to 225℃<T<250℃, the upper temperature of the crude gas filter (7) is <250℃, and the lower temperature of the crude gas filter (7) is <250℃.

7. The system for recovering and reusing the pressure swing adsorption desorption gas in the ethylene glycol synthesis according to claim 2, characterized in that, The shift system further comprises a cooler (11), and the second shift converter (10) is connected with the cooler (11).

8. The system for recovering and reusing the pressure swing adsorption desorption gas in the ethylene glycol synthesis according to claim 7, characterized in that, The shift system further comprises an ammonia washing tower (12), and the cooler (11) is connected with the ammonia washing tower (12).

9. The system for recovering and reusing the desorbed gas in the pressure swing adsorption of ethylene glycol synthesis according to claim 2, characterized in that, A second raw material gas preheater (9) is arranged between the first shift converter (8) and the second shift converter (10).

10. The system for recovering and reusing the desorbed gas in the pressure swing adsorption of ethylene glycol synthesis according to claim 2, characterized in that, The bed temperature in the first shift converter (8) is set to 230~320℃, and the pressure difference is <150Kpa; and the bed temperature in the second shift converter (10) is set to 190~250℃, and the pressure difference is <150Kpa.

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