Process Technologies

ATEC’s PARAFORMALDEHYDE TECHNOLOGIES

 

ATEC is in possession of technologies to produce all types of Paraformaldehyde products in varying concentration ranges and polymerization degree spans. It can offer PLANTS for:

 

(89-91)% FLAKED PARAFORMALDEHYDE PRODUCTION

 

Multi stage evaporation and chilled conveying process.

 

(91-96)% GRANULAR / PRILLED PARAFORMALDEHYDE PRODUCTION

 

Multi stage evaporation and rotary vacuum drying.

 

(91-96)% PRILLED PARAFORMALDEHYDE PRODUCTION

 

Multi stage evaporation and spray cum fluidized bed drying.


            


PARAFORMALDEHYDE PLANTS


PLANTS for production of flakes are relatively inexpensive, whereas the processes for production of prills / granules are fairly elaborate and such PLANTS involve a much larger investment.

 

Paraformaldehyde is a polymer of Formaldehyde in solid form, containing a percentage of water, readily soluble in order to obtain an aqueous solution or to be used as a reactant by dissolving it in the reaction medium.

 

Paraformaldehyde, which is represented by typical formula HO (CH2O)n H  is also termed as mixture of Polyoxymethylene Glycols.  It is controlled polymerized product of Formaldehyde in solid form.  The presence of Formaldehyde unit per molecule is more than 6.



PARAFORMALDEHYDE PRODUCTS RANGE


Typical characteristics of various Paraformaldehyde grades known to be manufactured are given below:


FREE FLOWING WHITE GRANULES WITH TYPICAL FORMALDEHYDE ODOUR (Granules)

WHITE POWDER

89%

91%

93%

96%

97%

FORMALDEHYDE CONTANT (%)

89 ± 1

91 ± 1

93 ± 1

95.5 ± 1

96.5 ± 1

METHANOL CONTENT (%Max.)

1

0.5

0.5

0.5

0.5

pH (10% AQUEOUS SUSPENSION

3-5

3.5-6.5

3.5-6.5

5-7

5-7

ACIDITY (AS FORMIC ACID (%) Max.)

0.03

0.03

0.03

0.03

0.03

REACTIVITY (RESORCINOL TEST ) (Minutes)

2-3

2-4

2-4

2-4

3-5

FLASH POINT (OPEN CUP) (oC)

93

93

93

93

93

FLASH POINT (CLOSED CUP) (oC)

71

71

71

71

71

IRON CONTENT (PPM Max.)

2

2

2

2

2

ASH CONTENT (PPM Max.)

100

100

100

100

100

MELTING POINT (oC)

120-170

120-170

120-170

120-170

120-170

BULK DENSITY (kg / m3)

750-750

750-850

750-850

750-850

500-800

GRAIN SIZE (MIN. 80%) (mm)

 

 

0.2-1.0

0.2-1.0

0.2-1.0

0.2-1.0

Min. 90%  < 0.100 DIN 60




PRODUCTION TECHNIQUE

Production of Paraformaldehyde usually starts from 37% or 55% by weight aqueous solutions of Formaldehyde. It is concentrated at temperatures below 100°C often done by vacuum distillation and mainly water distills of at first. The concentration of Formaldehyde present chiefly as hydrate is increased. The solutions can be concentrated in this way up to Formaldehyde content of above 80% at which point the greater part of the Formaldehyde is already present in the form of oligo – oxymethylene glycols. On cooling, gels with colloidal properties are obtained which are at first waxy but later on becomes brittle which consist of Paraformaldehyde.

ATEC`s FLAKED PARAFORMALDEHYDE TECHNOLOGY

Paraformaldehyde in flake form is produced by this process.  The raw material for the said Paraformaldehyde production is freshly manufactured high concentration (52-55%) Formaldehyde solution. A basic flow diagram is given below :




Salient Features


Salient features of ATEC`s modified process for manufacture of flaked Paraformaldehyde are enumerated below:

 

1)            Simple in Operation

2)            Free flowing, dustless white flakes. Dust is a big problem for the workers handling Para

3)            100% utilization of Formaldehyde with almost ‘0%’ loss in the process.

4)            100% pollution free

5)            Highest safety measures

6)            Easy solubility and simple to dissolve

7)            Low power consumption


           


FLAKED PARAFORMALDEHYDE PLANTS


GRANULAR / PRILLED PARAFORMALDEHYDE PRODUCTION TECHNOLOGY BY ROTARY VACUUM DRYING


A unique process based on Vacuum Concentrated and Drying of Product to produce various (91% to 96%) concentration grades of Paraformaldehyde would be applied. In the ATEC process Paraformaldehyde is manufactured from aqueous (37%) Formaldehyde solutions by the process involving distillation and concentration at a point at which solidification or precipitation of polymer takes place. The process of concentration is carried out by vacuum evaporation. The main sections of the PLANT are:

 

Concentration of aqueous Formaldehyde (AF-37 / AF-55)

Polymerization and drying

Concentration of distillates for recycling.

Conveying, pulverization and storage / packaging of the Product.

 

This Process is offered by ATEC in association with Libra Techcon.




Indicative Process flow diagram for the Granular / Prilled Paraformaldehyde processes is shown below:



GRANULAR  / PRILLED PARAFORMALDEHYDE PROCESSES BASED ON ROTARY VACUUM DRYING


The Process has been over the years upgraded based on actual operational experience obtained in PLANTS of different optimal production level from 5 M.P.D through 15 M.T.P.D. upto 30 M.T.P.D. and beyond. The upgradation carried out was in terms of optimization of equipment / machinery sizing and more compact lay out at individual floor level of the PLANTS.


          


PARAFORMALDEHYDE PLANTS


PRILLED PARAFORMALDEHYDE PRODUCTION PROCESS BASED ON SPRAY CUM FLUIDIZED BED DRYING


The process essentially consists of the following steps:

 

·               Concentration of Aqueous Formaldehyde

·               Vacuum Spray Drying

·               Fluidized Bed Drying

·               Product Handling

 

Concentration of Aqueous Formaldehyde (AF-37) to AF (75 – 85) is carried out in a falling film evaporation and thin film evaporation (side stream) system.

 

(75 – 85) % concentrated Aqueous Formaldehyde is fed to a conical bottom NIRO vacuum Spray Dryer.

 

Spray dried powder is further concentrated in a Fluidized Bed Dryer before being sent to the product handling system. A liquid catalyst is used.

 

Three different grades (89%, 92% and 96%) of Paraformaldehyde are produced by under for end use application in resins, agro chemicals (Herbicides / Pesticides), Disinfectant / Medical intermediates sectors.

 

Basic block diagrams of the Process are shown below:



PROCESS BLOCK DIAGRAM


ALTERNATIVE PRILLED FORMALDEHYDE PROCESS

 

An alternative process for production of prilled Paraformaldehyde products using the “Prilling Tower Concept” is also available. A schematic block diagram of this Process is shown below:




SCHEMATICS OF PRILLED PARAFORMALDEHYDE PRODUCTION


                


COMBINED SPRAY AND FLUIDIZED BED DRYING FOR PARAFORM


PRODUCT’S SPECIFICATIONS

 

The granular Paraformaldehyde manufacturing processes offered by ATEC will produce Paraformaldehyde of the following specifications:

 

Aldehyde content (as HCHO % by mass)

:

(91-96 ± 1) for individual grades

Ash Content, ppm (max.)     

:

100

Free Moisture content Percent by mass, (max.)

:

1

Acidity (as HCOOH) Percent by mass (max.)

:

0.03

Iron (ppm by mass max)

:

2

p-H

:

4 – 7

Methanol (% by mass max.) 

:

1

Melting Point

:

120º - 170º C