Process Specification for 250,000 tons of methanol

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Process Specification for 250,000 tons of Methanol – Methanol Plant
Table of Contents
Product Description……………………………………………………2
Specifications for Raw Materials, Products, and Catalysts………………8
Consumption of Raw Materials, Catalysts, and Chemicals………………12
Basic Principles of Production and Chemical Reaction Equations……15
Process Flow……………………………………………………17
Relationship between the Methanol Unit and the Entire Plant…………22
Consumption of Raw Materials, Catalysts, and Chemicals………………24
Treatment of Waste Streams…………………………………………27
List of Equipment…………………………………………………30
Energy-Saving Measures and Their Benefits…………………………44
Identification and Handling of Abnormalities During Production……46
Table of Process Parameters……………………………………………54

Process Specification for 250,000 Tons of Methanol ——————————————————————————
Product Description
Physical and Chemical Properties of Methanol
Methanol is the simplest representative of the saturated alcohol series. Its molecular formula is CH3OH, with the structural formula H–C–OH; its molecular weight is 32.04. At normal temperature and pressure, pure methanol is a colorless and transparent liquid that is easy to flow and burn. It is miscible with water in any proportion. It has an odor similar to that of ethanol. Its general properties are as follows:
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Property | Data
Density | 0.8100 g/ml (0°C)
Relative Density | 0.7913 g/ml (d420)
Boiling Point | 64.5–64.7°C
Melting Point | –97.8°C
Flash Point | 16°C (open container), 12°C (closed container)
Autoignition Point | 473°C (in air), 461°C (in oxygen)
Heat Capacity | 2.51 J/g°C (liquid at 20–25°C), 45 J/C°C (at 25°C)
Viscosity | 0.5945×10⁻³ Pa·s (0.5945 CP) (at 20°C)
Vaporization Latent Heat | 35.295 KJ/mol (at 64.7°C)
Corrosivity | Non-corrosive at normal temperatures; corrosive to lead and aluminum.
Explosion Limit | 6.0–36.5% (v/v) (in air)
Allowed Concentration of Methanol in Air (Limit Values)
In operational areas: 5 mg/m³
In residential areas: 0.5 mg/m³

Chemical Properties of Methanol
In air, methanol is oxidized to formaldehyde, which is then further oxidized to formic acid and carbon dioxide:
CH3OH → HCHO → HCOOH → CO2
At 600–700°C, methanol reacts with oxygen to form formaldehyde and water:
CH3OH + ½ O2 → HCHO + H2O
The hydroxyl group in methanol can be replaced by alkali metals:
2CH3OH + 2Na → 2CH3ONa + H2
Methanol reacts with ammonia to produce methylamine, in the presence of a dehydrating catalyst, at 60–200 atmospheres and 370–400°C:
NH3 + CH3OH → CH3NH2 + H2O
At the same conditions, methylamine can also react with methanol to produce dimethylamine:
CH3NH2 + CH3OH → (CH3)2NH + H2O
Under similar conditions, dimethylamine can further react with methanol to produce trimethylamine:
(CH3)2NH + CH3OH → (CH2)3N + H2O
On a catalyst, methanol reacts with benzene to produce toluene:
CH3OH + C6H6 → C6H5CH3 + H2O
Methanol can also be dehydrated to produce dimethyl ether on a catalyst:
2CH3OH → (CH3)2O + H2O
Acids react with methanol to form esters:
CH3OH + H2SO4 → CH3SO3H + H2O
Methanol reacts with hydrohalic acids to produce methyl halides:
CH3OH + HCl → CH3Cl + H2O
It reacts with organic acids to form methyl esters:
RCOOH + CH3OH → RCOOCH3 + H2O
It can also undergo carbonylation with CO to produce acetic acid:
CO + CH3OH → CH3COOH
Methanol can be cracked to produce combustible hydrocarbons:
2CH3OH → C2H4 + 2H2O
It reacts with isobutylene to produce methyl isobutyl ether:
CH3OH + C=CH2 → CH3–O–C–CH3

Quality Standards for Industrial Methanol
1.2.1 The standards applicable are those of the People’s Republic of China (GB-338-2004) or the American Federal Standard O-M-232K, Grade AA. This standard applies to industrial methanol synthesized from raw materials such as coal, coke, natural gas, and light and heavy oils. It is mainly used in the production of formaldehyde, as well as in synthetic fibers and synthetic resins; it is also an essential raw material in the pharmaceutical and pesticide industries. H structure: H—C—OH. Molecular formula of H: CH3OH. Molecular weight: 32.04 (according to the 1983 international atomic weights). Technical specifications: The density of crude methanol should be between 0.80–0.86 g/ml. Industrial methanol must meet the following requirements. The product produced by this facility is pure methanol, with the following specifications: Temperature: 40°C; Pressure: 0.5 MPaA. Quality: Must comply with **standard (GB-338-2004) or the American Federal O-M-232K Class AA standard. **The standards (GB-338-2004) are shown in the table; the American Federal O-M-232K AA grade standards are also listed in the table. The **standards for the quality of pure methanol (GB-338-2004)** are as follows:
– Premium grade:
– First-grade:
Colority/Hazen units (platinum-cobalt scale): ≤5, ≤5
Density at 20°C, g/cm³: 0.791–0.792, 0.791–0.793
Boiling range (at 101.3 kPa, within 64.0–65.5°C, including 65.6±0.1°C): ≤0.8, ≤1.0
Potassium permanganate test, minutes: ≥50, ≥30
Water solubility test: Passes test (1+3), Passes test (1+9)
Water content, %: ≤0.1, ≤0.15
Acid content (calculated as HCOOH), %: ≤0.0015, ≤0.0030
Alkali content (calculated as NH3), %: ≤0.0002, ≤0.0008
Aldehyde content (calculated as CH2O), %: ≤0.002, ≤0.005
Mass fraction of evaporative residues, %: ≤0.001, ≤0.003
Sulfuric acid washing test/Hazen units (platinum-cobalt scale): 50, 50
Ethanol content, %: To be agreed upon by both parties
American Federal O-M-232K AA grade standards:
Serial number | Parameter name | Value
1 | Methanol (wt%) | 99.85% (minimum)
2 | Water (wt%) | 0.10% (maximum)
3 | Same (wt%) | 0.002% (maximum)
5 | Ethanol (wt%) | 0.001% (maximum)
6 | Acidity (calculated as acetic acid, wt%) | 0.003% (maximum)
7 | Appearance | No suspended solids or precipitates
8 | Color (platinum-cobalt scale) | Not darker than ASTM E346 No. 5
9 | Color that can be carbonized (platinum-cobalt scale) | Not darker than ASTM E346 No. 30
10 | Boiling range | At 760 mmHg, not more than 1°C, including 64.6±0.1°C
11 | Specific gravity (20°C/20°C) | 0.7928 (maximum)
12 | Content of non-volatile substances (mg/100 ml) | 10 (maximum)
13 | Potassium permanganate test | No color change within 30 minutes
14 | Odor | No unusual odor, only normal odor
Uses of methanol: Methanol has a wide range of uses. It is primarily used in the production of polyvinyl alcohol (vinylon), formaldehyde, acetic acid, dimethyl terephthalate (polyester), methacrylic acid, methyl methacrylate (plexiglass), amines (pesticides, chemical agents, surfactants, solvents, methyl halides). It is also used as a refrigerant, fuel, for synthesizing proteins, in paints, gasoline, and methyl isobutyl ether. As a new type of energy-related chemical raw material, methanol can also be used in the production of pentaerythritol, synthetic isoprene rubber, film, and PVC resins. In recent years, there have been new developments in the utilization of methanol. There is still hope for its use in producing olefins, ethanol, ethylene glycol, etc. . Specifications for raw materials, products, and catalysts etc. Raw materials and fuels (1) Feed gas The feed gas for this unit is purified gas, with the following specifications: Temperature: 30°C Pressure: 2.1 MPaA The composition is shown in the table. Composition of feed gas (mol%): H2: 61.36, CO: 20.83, CO2: 3.09, N2: 0.55, CH4: 12.32, Saturated H2O, H2S+COS: 1 mg/Nm3, CnHm: 1.85 (2) Oxygen The oxygen required by this unit comes from an air separation unit, with the following specifications: Temperature: 40°C Pressure: 2.8 MPaA The composition is shown in the table. Composition of oxygen (mol%): O2: 99.6, N2: 0.1, Ar: 0.3 (3) Fuel gas The fuel gas needed by this unit mainly comes from the exhaust gas generated during hydrogen recovery in the methanol plant; any shortfall is covered by the fuel gas storage tanks available throughout the plant. The specifications for the hydrogen recovery exhaust gas are as follows: Temperature: 40°C; Pressure: 0.5 MPaA. The composition is shown in the table below. Composition of hydrogen recovery exhaust gas: mol% H2: 62.48, CO: 6.65, CO2: 4.09, N2: 13.35, CH4: 13.43.

The specifications for the fuel gas in the plant’s fuel gas tanks are as follows: Temperature: 40°C; Pressure: 0.106 MPaA. The composition is shown in the table below. Composition of fuel gas in fuel tanks: mol% H2: 22.17, CO: 0.64, CO2: 74.59, N2: 0.03, CH4: 0.99, O2: 0.01, CnHm: 1.57.

The product of this facility is syngas, with the following specifications: Temperature: 40°C; Pressure: 1.7 MPaA; Flow rate: 143,933 Nm3/h. The composition is shown in the table below. Composition of syngas: mol% H2: 68.13, CO: 23.26, CO2: 7.31, N2: 0.47, CH4: 0.5, H2O: 0.33.

Specifications for catalysts and chemicals:
(1) Steam reforming catalyst: Model: Katalco 28-4Q. Shape: Ring-shaped. External dimensions (mm): φ25×16×8. Packing density: ~1.2 t/m3. Crushing strength: ≥350 N per particle.
(2) Activated carbon: Model: T103. Shape: Rod-shaped. Diameter: Ø3–4 mm. Bulk density: 1.350–1.50 t/m3. Crushing strength: ≥50 N/cm.
(3) Methanol synthesis catalyst: Appearance: Cylinder with a black metallic luster. External dimensions (mm): φ5×(4.5～5) Packing bulk density: ~1.37 kg/l Side pressure strength (N/cm): ≥200 Chemical composition: CuO>52%, ZnO>20%, Al2O3>8%. Consumption of raw materials, catalysts, and chemicals The consumption amounts of raw materials, catalysts, and chemicals are shown in the table. Consumption of raw materials, catalysts, and chemicals | Name | Initial loading amount | Replacement cycle | Hours | Annual consumption | Purified gas (dry) | 11,2013 Nm3 | 8.961x10^8 Nm3 Conversion catalyst | 15.27 m3 | 4 years Activated carbon | 82 m3 | 4 years Specifications for utility materials Circulating cooling water | Pressure (supply/return) | 0.52/0.35 MPa(A) | Temperature (supply/return) | 30/40℃ | Fouling thermal resistance | 0.000344 m2·K/W | Annual corrosion rate | Carbon steel: less than 0.125 mm/year Desalinated water | Pressure | 1.3 MPa(A) | Temperature | 20～30℃ | Conductivity (at 25℃) | ≤0.3 μ.s/cm | SiO2 | ≤0.02 mg/l | Total hardness | 0 | Total Fe