Detailed explanation of adipic acid production process (picture)
3.1.2 Process Flow and Pollutant Discharge Nodes
This project uses refined benzene as raw material, and generates cyclohexene through selective hydrogenation. Cyclohexene hydrates to produce cyclohexanol, which is then oxidized by nitric acid to produce adipic acid.
. Hydrogen is produced using pressure swing adsorption technology with methanol synthesis purge gas as the raw material; Nitric acid is produced from liquid ammonia using a dual pressure method. The main process flowchart is shown in Figure 3.1-1, and the list of production process pollution source emission nodes is shown in Table 31-14.
Liquid Ammonia
Nitric Acid
Benzene
Cyclocyclohexene Cyclohexanol
Self
Di
Ethylene
Alcohol
Acid
H2
Methanol Synthesis Release Gas PSA Hydrogen Production Unit
Adipic Acid Finished Product
Figure 3.1-1 Adipic Acid Production Main Process Flow Diagram
3.1.2.1 Hydrogen Production Unit Process Flow and Discharge Nodes This unit adopts the 84PSA process flow, which means that there are 2 adsorption towers in the 8 adsorption towers of the unit. The tower is in the state of feeding adsorption at the beginning and end. The adsorption and regeneration process consists of steps such as adsorption, four consecutive pressure equalization and depressurization, forward discharge, reverse discharge, flushing, four consecutive pressure equalization and pressurization, and product gas pressurization.
The pollutants generated by the hydrogen production unit include safety valve exhaust gas (G1), abnormal production exhaust gas (G2), analytical gas (G3), and the main pollutants CH4, CO, and H2 in the exhaust gas, which are sent to the flare for incineration treatment. 3.1.2.2 Process flow and discharge nodes of nitric acid plant
The project adopts ammonia oxidation method to produce nitric acid, which includes processes such as ammonia air mixture preparation, ammonia oxidation and heat recovery, nitric oxide oxidation and absorption. The production and discharge process flow chart of nitric acid plant is shown in Figure 3.1-2.
Ammonia evaporator for liquid ammonia
Ammonia superheater
Ammonia auxiliary evaporator
Low pressure steam
Process air compressor
Secondary air
Ammonia filter
Ammonia air mixer
Ammonia oxidation furnace
Superheater
Waste heat boiler
Secondary air
High temperature gas to gas heat exchanger
Gas economizer
Low pressure reaction water condenser
Secondary air
Nitrogen oxide separator
NOX
Nitrogen oxide compressor
Tail gas preheater
Adipic acid process
Example G Waste gas W Wastewater S Solid waste
Acid storage tank for finished products
Acid cooler
G4 tail gas exhaust pipe
Tail gas expander
Tail gas reduction device
Tail gas preheater
Bleach tower
High pressure reaction water condenser
Process water
Absorption tower
HNO3
Air
Gas
Secondary air cooler tail gas separator
Figure 3.1-2 Production and discharge process flow chart of nitric acid unit 3.1.2.3 Process flow and discharge nodes of cyclohexanol unit
The project adopts the cyclohexanol method, which includes benzene hydrogenation, extraction distillation, hydration, cyclohexane refining, hydrogenation catalyst regeneration, hydration catalyst regeneration and other processes. The production and discharge process flow chart of cyclohexanol unit is shown in Figure 3.1-3.
Benzene
Pre treatment adsorber
S3
Benzene
H2 first hydrogenation reactor second hydrogenation reactor
Catalyst slurry
Hydrogenation settler
Flash evaporation tank dehydration tower
H2O
Dehydration tower
Benzene recovery tower
Solvent
Benzene separation tower
Low boiling point components
Cyclohexane purification tower
Hydrogenation catalyst regeneration
G7 S1
H2
Water
Cyclohexane Treatment Reactor
Cyclohexane
Cyclohexane Water Washing Tower
Cyclohexene Separation Tower
Solution
S4
Agent
Hydration Catalyst Regeneration
G8 S2
Cyclohexene Recovery Tower
Water
Cyclohexene
First Hydration Reactor Second Hydration Reactor
Cyclohexene Separation Tower
Cyclohexol Cyclohexene
Hexanol
Cyclohexene Washing Tower
Adipic Acid Plant
Cyclohexene
Cyclohexanol Purification Tower
High Boiling Compounds
Legend
G Waste Gas W Wastewater S Solid Waste
Figure 3.1-3 Discharge Node of Cyclohexanol Plant Figure 3.1.2.4 Process Flow and Discharge Node of Adipic Acid Plant
Adipic acid is produced by oxidizing cyclohexanol with nitric acid using copper and vanadium as catalysts, followed by crystallization, concentration, and centrifugation to obtain crude adipic acid. Crude adipic acid is dissolved, decolorized by activated carbon, crystallized, concentrated, centrifuged, and dried to obtain refined adipic acid product. The subsequent system includes nitrogen oxide gas recovery, nitric acid concentration, catalyst and adipic acid recovery. The production and wastewater discharge process flowchart of the adipic acid plant is shown in Figure 3.1-4.
Cyclohexanol HNO3 water
Oxidation reactor
Crude adipic acid crystallizer
Thickening filter centrifuge
Air
Mother
Liquid
W2
Acid
Water
Nitrous gas condenser
Cold
Condensation
Mother
Liquid acid
Nitric acid concentration tower W3
Liquid
Nitrous gas compressor
Primary evaporator
Activated carbon liquid filter S5
Nitrogen oxide gas absorption tower
G9
HNO3
HNO3
Catalyst recovery resin reactor
S6
Evaporator (falling film)
Water
Storage tank
Crystallization tank
Centrifuge
Self
Second
Yuan
Acid
Acid
Dissolving tank
Storage tank
Oxidation reaction solution tank
Second catalyst adsorber
Mixed dicarboxylic acid
Legend
G waste gas W wastewater S solid waste
Weighing and packaging buffer bin
Drying machine
W2 washing
Fine adipic acid crystallizer
W2
Centrifuge thickening filter
Dust
Figure 3.1-4 adipic acid device discharge node diagram
Appendix information: Unnecessary can be deleted by oneself. Coal mine electromechanical equipment integrity standards
1. General parts
1.1 Fasteners
Bolts, nuts, washers, etc. are complete, tightened, and free of rust. 1.2 The specifications of nuts and bolts in the same part are consistent. The specifications of flat washers and spring washers should match the bolt diameter. Tighten bolts and nuts should have anti loosening devices. 1.3 Tighten the opaque screw hole components with bolts, and leave a thread allowance greater than twice the thickness of the anti loosening washer in the screw hole after tightening. The length of the bolt screwed into the screw hole should not be less than the bolt diameter, but for cast iron, copper, and aluminum parts, it should not be less than 1.5 times the bolt diameter. After tightening the nut, the bolt thread should expose 1-3 pitches of the nut, and excess washers should not be added under the nut to reduce the extension length of the bolt. The upper surface of the bolt or nut fastened inside the protective ring must not exceed the height of the protective ring, and special tools must be used to loosen or tighten it. 2. Explosion proof performance 2.1 The gap, diameter difference, or minimum effective length (width) of the explosion-proof joint surface (Class I) must comply with the provisions of Table 41.
L in the table represents the minimum effective length of the static explosion-proof joint surface; L1- Minimum effective length from the edge of the bolt through-hole to the edge of the explosion-proof joint surface; W-maximum gap or diameter difference between the static explosion-proof joint surface and the explosion-proof joint surface between the control rod and the rod hole; The maximum diameter difference between the explosion-proof joint surface of the shaft and the shaft hole. But the minimum effective length of the explosion-proof joint surface of the quick action door or cover must not be less than 25mm.
Table 41 Structural Parameters of Class I Explosion proof Joint Surface mm
Joint Surface Type
L L1
W
Shell Volume V (t)
V ≤ 0.1
V>0.1
6.0
0.30
Flat and Stop 12.5 8.0
0.40
25.0 9.0
>
0.50
40.0 15.0
60
With rolling 6.0
0.40
Bearings
12.5
0.50
0.50
Cylindrical structure 25.0
>
0.60
40.0
0.80
2.2 The diameter (d) of the control rod and the length (L) of the explosion-proof joint surface should comply with the specifications in Table 42
.
Table 42 Structural Parameters of Control Rod Diameter or Cylinder Diameter and Explosion proof Joint Surface mm
Control Rod Diameter
Explosion proof Joint Surface Length
d≤6
L≥6
6＜d≤25
L≥d
25≤d
L≥25
2.3 The explosion-proof joint surface between the explosion-proof motor shaft and the shaft hole should not produce friction under normal working conditions. When using a cylindrical explosion-proof joint surface, the minimum unilateral clearance between the shaft and the shaft hole must not be less than 0.075mm; when using a rolling bearing structure, the maximum unilateral clearance between the shaft and the shaft hole must not exceed 2.3 of the W value specified in Table 41.
6.3
2.4 The surface roughness of the explosion-proof joint surface shall not exceed; The surface roughness of the joystick is not less than 3.2.
2.5 Thread Explosion proof Structure: Thread accuracy not less than level 3; The pitch shall not be less than 0.7mm; the minimum number of meshing buckles and the minimum depth of screwing in the thread pattern shall comply with the provisions of Table 43.
Table 43 Minimum number of meshing threads and minimum screwing depth mm
Net volume of shell V (t) Minimum screwing depth
Minimum number of meshing threads
V≤0.1
5.0
0.1＜V≤2.0
9.0
6
2.0≤V
12.5
2.6 The flange thinning thickness of the explosion-proof joint surface should not exceed the maintenance allowance specified in the original design.
2.7 Defects or mechanical scars on the explosion-proof joint surface shall not exceed the following regulations after grinding down the protruding parts on both sides of the scar that are higher than the undamaged surface: a. For sand holes with a diameter not exceeding 1mm and a depth not exceeding 2mm that appear locally on the explosion-proof surface, there shall not be more than 5 holes per 1cm2 on explosion-proof surfaces with a width of 40, 25, and 15mm; On a 10mm wide explosion-proof surface, there shall not be more than 2.
b. The width and depth of the mechanical scars generated should not exceed 0.5mm; their length should ensure that the effective length of the remaining scar free explosion-proof surface is not less than 2/3 of the specified length.
2.8 The explosion-proof joint surface shall not have rust or paint, and shall be coated with anti rust oil or phosphating treatment. If there is rust, and after wiping it off with a veil, there is a greenish brown ferrous oxide like mark left, and there is no feeling when touched by hand, it is still considered qualified.
2.9 The explosion-proof joint surface fixed with bolts should be tightened to flatten the spring washer without loosening, which is qualified.
2.10 Observe that the sealing and transparency of the window holes are good, without damage or cracks.
2.11 The explosion-proof performance of imported equipment shall comply with the provisions of Appendix 5-A, B, C, and D of the Electrical Equipment Volume of the "Quality Standards for Maintenance of Coal Mine Mechanical and Electrical Equipment".
2.12 Any equipment that fails to meet the requirements of 1.2.1 to 1.2.11 shall be deemed to have lost its explosion-proof performance, and shall not be evaluated as intact equipment.
3、 Wiring
3.1 The inlet nozzle should be securely connected and well sealed, and should comply with the following regulations:
a. The sealing ring material must be made of rubber with a Shore hardness of 45-55 degrees and undergo aging treatment according to regulations
.
b. The degree of fastening of the fasteners after wiring is qualified if they do not move when pulled. The clamping of the wire nozzle should have a margin, and a metal gasket should be added between the wire nozzle and the sealing ring. The compression of the cable by the stacked cable nozzle should not exceed 10% of the cable diameter.
c. The difference between the inner diameter of the sealing ring and the outer diameter of the cable should be less than 1mm; the difference between the outer diameter of the sealing ring and the inner diameter of the incoming device should comply with the provisions of Table 4-1-4; The width of the sealing ring should be greater than 0.7 times the outer diameter of the cable, but must be greater than 10mm; the thickness should be greater than 0.3 times the outer diameter of the cable, but must be greater than 4mm (except for 70mm2 rubber sheathed cables). The sealing ring is not damaged and cannot be cut open for use. No other items shall be wrapped between the cable and the sealing ring.
d. When introducing armored cables into low-voltage explosion-proof switches, the sealing ring should be fully wrapped around the cable lead sheath.
Table 44 Gap between Outer Diameter of Sealing Ring and Inner Diameter of Inlet Device mm
Outer Diameter of Sealing Ring D
Gap between Outer Diameter of Sealing Ring and Inner Diameter of Inlet Device
D≤20
≤1.0
20＜D≤60
≤1.5
60＜D
≤2.0
e. The length of the cable sheath (lead sheath) inserted into the inlet nozzle is generally 5-15mm. If the cable is thick and cannot be inserted, the inserted part can be filed fine (but the joint between the sheath and the sealing ring cannot be filed fine).
f. The wiring nozzle of the low-voltage explosion-proof switch space should be sealed with a sealing ring and a steel gasket with a thickness of not less than 2mm, and tightly sealed. Tightening degree: The spiral nozzle is qualified when tightened by hand; The stacked nozzle is considered qualified if it cannot be shaken by hand. The steel gasket should be placed outside the sealing ring, and the difference between its diameter and the inner diameter of the incoming device should comply with the provisions of Table 44. The wiring nozzle of the high-voltage explosion-proof switch space should be sealed and compressed with steel pads that match the thickness and diameter of the nozzle flange. The gap between the explosion-proof joint surfaces should comply with the provisions of Table 41.
g. After introducing armored cables into the high-voltage explosion-proof switch junction box, insulation should be poured into the cable at three or more branches.
h. Any equipment that does not meet one of the above regulations shall be deemed as a lost device and shall not be evaluated as intact. 3.2 The wiring device is complete, intact, and securely fastened, with good conductivity, and meets the following requirements:
a. The insulation seat is intact and free of cracks; b. The threads of the wiring bolts and nuts are undamaged, with no discharge marks, and the wiring components are complete, including claws, spring washers, back caps, etc; c. The wiring should be neat, without burrs, and the claws should not press against insulation rubber or other insulation materials, nor should they press or touch the shielding layer; d. The electrical clearance and creepage distance of the wires inside the junction box shall comply with the provisions of GB3836.3-83 "Explosion proof Electrical Equipment for Explosive Environments - Increased Safety Electrical Equipment" e "; e. Explosion proof switch power supply and load introduction device shall not be used upside down. 3.3 The wiring of fixed electrical equipment should meet the following requirements: a. The terminal ends of the incoming (outgoing) lines of the equipment should be wired with wire noses or transition joints; b. The wire connection should be firm and reliable, and the joint temperature should not exceed the wire temperature. 3.4 In addition to complying with the provisions of Article 449 of the Coal Mine Safety Regulations, the connection of cables should also meet the following requirements:
The connection of cable cores is strictly prohibited from binding and should be made by crimping or welding.
. The resistance of the connected joint should not be greater than 1.1 times the resistance of the same length core wire, and its tensile strength should not be less than 80% of the original core wire. The connection of core wires of different materials should use transition joints, and the resistance value of the transition joint should not be greater than 1.3 times the resistance value of core wires of the same length;
The high and low voltage armored cable terminals should be filled with insulation materials, and epoxy resin dry sealing can be used indoors. The intermediate junction box should be filled with insulation glue. 4. Safe power supply
4.1 Short circuit, leakage, grounding and other protective devices for high and low voltage electrical equipment must comply with the provisions of the "Coal Mine Safety Regulations", "Detailed Rules for Safety, Inspection and Measurement of Mine Protection Grounding Devices", "Detailed Rules for Installation, Operation, Maintenance and Overhaul of Coal Mine Underground Leak Detection Relays" and "Detailed Rules for Setting of Mine Low voltage Grid Short circuit Protection Devices".
4.2 The short-circuit protection calculation setting is qualified, and the action is sensitive and reliable. 4.3 The use of leakage protection devices is qualified. 4.4 Grounding device 4.4.1 Grounding bolts shall comply with the following standards:
The external grounding bolts of the metal casing and armored cable junction box of electrical equipment shall be complete and marked with the symbol "" (except for mining machinery and equipment that are moving during operation).
The junction box of electrical equipment should be equipped with internal grounding bolts and marked with the symbol "" (excluding electrical equipment on electric locomotives and electrical equipment with a voltage below 36V).
The diameter of the external grounding bolt with a capacity of less than or equal to 5KW shall not be less than M8; the capacity between 5KW and 10KW shall not be less than M10;
For capacities greater than 10KW, not less than M12; Small equipment such as communication, signal, button, lighting, etc. should not be smaller than M6. The grounding bolt should be treated with electroplating and rust prevention. 4.4.2 The grounding wire shall comply with the following regulations: a. The cross-sectional area of the grounding busbar for the main grounding electrode shall not be less than:
Galvanized iron wire 100 mm 2 Flat steel 25 4 mm 2 Copper wire 50 mm 2 b. The cross-sectional area of the grounding wire for the connection box between the electrical equipment shell and the grounding busbar or local grounding electrode, and the armor and lead skin at both ends of the cable junction box shall not be less than:
Copper wire 25 mm 2 Flat steel 50 mm 2 (thickness not less than 4mm) Galvanized iron wire 25 mm 2 4.4.3 The grounding resistance shall not exceed the following values: a 100KVA or above (low-voltage neutral point direct grounding system) 4; The power supply lines of transformers with a capacity of over 100KVA are repeatedly grounded for 10 times; 10 transformers below 100KVA; Repeated grounding of transformer power supply lines below 100KVA for 30 days; Joint grounding of high and low voltage electrical equipment 4; Current and voltage transformer secondary coil 10; The protection network or protection line of high-voltage transmission lines; Underground equipment 2;
Handheld mobile electrical equipment 1 underground.
4.5 The equipment locking device is complete and reliable.
4.6 Underground power supply should comply with the provisions of Article 470 of the Coal Mine Safety Regulations, which means "three no's, four have's, two have's, three all's, and three insist's".
5、 Regulations on non oil leakage and non electric leakage
5.1 There should be no oil stains on the non oil leakage fixed joint surface, valves, oil gauge pipes, etc. The sports department allows for oil stains, but after drying, there should be no oil visible within 3 minutes and no dripping within half an hour. Non enclosed transportation: Lubricating grease for moving parts must not be thrown onto other components and foundations.
5.2 The insulation resistance of the non leakage network shall not be less than the following requirements, and the leakage relay shall be put into operation normally.
1140V 60K ；
660V
30K ；
380V
15K ；
127V
10K 。
6、 Electrical performance testing
6.1 The insulation performance of electrical equipment must be tested according to the period and items specified in the "Coal Mine Electrical Test Regulations (Trial)"
, and meet the standards, with records available for inspection.
.
6.2 Insulation oil, oil quality analysis should be conducted before using new oil; Perform simplified analysis on the running oil once a year; The oil of the multi oil circuit breaker should undergo a voltage withstand test every six months. Other tests should be conducted in accordance with the "Coal Mine Electrical Test Regulations (Trial)". There are records available for reference.
6.3 Relay protection device calculation and setting inspection shall be conducted once a year; The relay protection device of the mine power supply should be inspected every six months and comply with the setting plan, with records available for reference.
6.4 The indicating rotary instrument should be inspected once a year, and its accurate registration should not be lower than level 2.5; Power measuring instruments should be calibrated every six months, and their accuracy level should not be lower than 1.0. There are records available for reference. 7. 7.1 The selection of high and low voltage switches for equipment use should comply with the requirements of Article 421 of the Coal Mine Safety Regulations, and should match the capacity of the controlled equipment. If any of the following situations occur, it shall not be evaluated as intact equipment.
Users of high-capacity and overvoltage levels; B is not within the scope of use; The relay protection fails, and the selected melt is unqualified; The explosion-proof magnetic starter uses a small horn mouth to lead out the power line. 7.2 Underground explosion-proof electrical equipment must have a certificate of conformity issued by a designated explosion-proof electrical equipment inspector before going underground, otherwise it cannot be evaluated as intact. 8. Safety protection 8.1 The computer room (chamber) and electrical equipment, as well as all exposed live parts and rotating parts that may endanger personal safety, must be equipped with protective covers, guardrails, and hung with danger warning signs. 8.2 The computer room (chamber) should have fire-resistant equipment that meets the regulations. 8.3 The computer room (chamber) shall not store gasoline, kerosene, insulating oil, and other flammable materials. Used cotton yarn (rags) should be stored in a tightly sealed specialized container and placed in a designated location. 9. Coating 9.1: The surface of the equipment should be coated with anti rust paint. The inner walls of switch boxes, junction boxes, etc. should be coated with arc resistant paint, and the color should be consistent with the factory color.
9.2 The protective fence, oil label, oil injection hole, and oil plug of the equipment should be painted with red paint on the surface. 9.3 The parts of the equipment surface where the paint has peeled off should be repainted in a timely manner. 10. Equipment environment 10.1: The surface of the equipment is free of dust and oil stains. 10.2 The computer room (chamber) should be clean, free of debris, silt, accumulated water, dripping water, and oil stains. Tools, spare parts, materials, etc. should be stored in a fixed location and neatly arranged. 10.3 The computer room (chamber) has good ventilation, appropriate brightness of lighting facilities, and meets safety requirements
