HPMC|Hydroxypropyl methylcellulose production process
1. Pretreatment of hydroxypropyl methylcellulose raw materials
The existing HPMC production process is to complete the pretreatment process of the cellulose raw material by the cellulose raw material-refined cotton through several steps such as opening, pulverizing, cyclone separation, bag dust removal packaging and the like.
1, 1 block diagram:
Refined cotton→Open package→Opening→Crushing→Wind delivery→Cyclone separator→ Bag filter
↓ ↓
Packaging
1, 2 material balance of the process: (based on "dry" refined cotton as a benchmark)
Refined cotton - →
(1000kg kg)
Open bag (≯0.2kg)
Yield
Open (0.1-0.3kg)
99%
Crushing (≯0.3kg
One time packaging (965kg)
Secondary packaging (34kg)
Exhaust gas (0.1-0.5kg)
1,3 process pollution source analysis
The main source of pollution in this process is dust pollution. From the above material balance, the main source of dust is the tiny cellulose particles produced by the crushing process, causing air dust pollution.
The dust in the two steps of unpacking and pulverizing the entire pretreatment process is less and can be controlled, mainly because:
1 The manual opening process is slower and has not been smashed, so human factors can control the generation of dust.
2 crushing small step is a fully enclosed pulverizer operation. In general, normal production will not produce too much dust, except in the case of fault conditions and maintenance.
The opening step is to place the unwrapped sheet-like refined cotton on the opener and tear it into loose pieces of 1-3 cm.
This step is relatively easy to generate dust because the feed is generally open, and the sealing performance of the feeding device of different manufacturers and the feeding device are different, and the degree and amount of dust generated are also greatly different.
Due to the difference in the effect of bag-type dust collectors designed and manufactured by different equipment manufacturers, some manufacturers even install simple dust-removing devices, resulting in a large difference in the dust-removing effect and a large difference in dust generation.
For the process of cotton picking machine, if the isolation of the refined cotton tank of the cotton picker is strengthened, the dust consumption of the whole process will be greatly reduced.
2. Alkalinization, etherification, solvent recovery, washing process
This process is the main reaction stage of HPMC production and the main production link of pollution sources.
2, 1 flow chart is as follows:
Solvent alkali PO MeCl HAC water water
↓ ↓ ↓ ↓ ↓ ↓ ↓
Refined cotton powder→Basification→Etherification→Neutralization→Solvent recovery→One separation→Washing→Second separation→Drying
↑ ↓ ↓ ↓
Refined ←← Mixed solvent Process wastewater Process wastewater
2, 2 process material balance:
Solvent balance: calculated by feeding 7000 kg of solvent
Solvent - →
(7000kg)
Feeding process (5kg)
→ recycling
(6800kg)
Utilization rate 97.1%
Venting (55kg)
Desolvation process (65kg)
Washing (35kg)
Distillation (35kg)
Other unorganized emissions (5kg)
Methyl chloride balance: calculated by feeding 900 kg of methyl chloride
Methyl chloride - →
(900kg)
Filling process (20kg)
→ Total utilization
82.2%
Participate in the main reaction (450-550kg)
Side reaction (200-280kg)
Venting (80-120kg)
Other unorganized emissions (30kg)
Epoxy Propane Balance: Calculated by feeding 300 kg of propylene oxide
Propylene oxide - →
(300kg)
Filling process ( <5kg)
→ Total utilization
93.3%
Participate in the main reaction (160-200kg)
Side reaction (80-120kg)
Venting (<5kg)
Other unorganized emissions (10kg
Process water balance: 20 M3 per ton
Process water—→
(20M3)
Softened water preparation ( <2 M3)
→ Total utilization
90%
Alkalinization (0.6 M3)
Desolvation process (7.5 M3)
Washing process (8.5 M3)
Flushing pipe (0.8 M3)
Dry (0.6 M3)
3. Post-treatment of hydroxypropyl methylcellulose HPMC production
HPMC post-treatment now generally refers to the process of granulation, drying, comminution and mixing. In this process, the impact on the environment has two aspects: one is HPMC dust pollution, and the other is equipment noise pollution. These two kinds of pollution are easier to control from the perspective of control, and generally control from several aspects:
(1) In the process and equipment selection, we must pay attention to: choose mature environmentally friendly post-treatment technology; equipment manufacturers with strong technical strength.
(2) In terms of production control: strictly enforce your operating procedures and eliminate illegal operations.
(3) Strengthen employees' awareness of environmental protection and improve their labor protection capabilities.
(4) Isolation of noise sources, isolation of devices with high noise, and effective noise reduction measures.
Gomez Chemical's post-treatment process in HPMC is now basically mature, so it has gradually gained the attention of enterprises in terms of environmental impact. At the same time, the control of dust also creates new economic benefits for enterprises.
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