Nagaoka Packing "Super H Pack"

 

 

NAGAOKA PACKING  “Super H pack”

Tadayoshi Nagaoka

Laboratory of structured packing for distillation

Abstract

In the distillation and absorption processes of chemical plant, the structured packing was introduced instead of historical random packing and increased separation efficiency.

The structured packing, however, could not increase treating volume. When treating volume increases, speed of upward vapor also increases. In this circumstance, downward liquid, specially free liquid droplet at the bottom of distributor and structured packing  can not go down due to high speed of upward vapor, and is accumulated in the column, resulting in start of flooding. These phenomena came from layout of all internals, because of separated layout, distributor, and structured packing.(Fig.2)

NAGAOKA PACKING “Super H pack”  has connected a distributor, structured packing and collector by changing layout in the column. Super H pack realized increased speed operation of vapor and reached two-times larger treatment volume with high efficient separation.(Fig.1)

Structure  and  feature

NAGAOKA PACKING ”Super H pack” has five main features of unique structure as follows.(Fig.1)

1. Epoch-making connected structure with distributor, structured packing and collector pushes away the flooding point because of avoiding free liquid-droplet at the bottom of distributor and structured packing  and expand operating range up to a higher F-Factor which enables high speed operation.
2. Super H pack is constructed with multiple vertical capillary wires which run with equal interval and in parallel in the full length.

Multiple linear liquid flow along the vertical capillary wires and upward organized vapor flow produce efficient vapor-liquid counter-contact.

Downward liquid flow which is led by the capillary wires can go down against high speed of upward vapor.  Therefore high efficient separation and high speed operation  which means larger treatment volume are achieved  simultaneously.

1. Trough distributor is overflow type and has many equally spaced liquid ports and all capillary wires of structured packing hang from each of all liquid ports. Number of liquid drip points of distributor over 50,000/m2 can be available.

Combination of many equally spaced liquid ports and hanging capillary wires

produces uniform liquid distribution over the entire column.

1. Many equal liquid distribution starts at top of structured packing.      

Elimination of the mal-distribution results from the constitution of vertical and parallel wires  in the full length.

Therefore minimum specific surface area of Super H pack produces high efficient separation.

1. Constitution of vertical and parallel wires  and minimum specific surface area achieve minimum pressure drop in operation.

Test result of distillation and valuation          

Vacuum batch distillation.

(Photo 1)

Head pressure 100mmHg.

Fluid;  Chlorobenzene  and  

Ethyl benzene. 

Separation efficiency ;NTS/m  

(Fig.3)

Pressure drop; mbar/NTS 

(Fig.4)

Photo1

Indication	Remarks	Specific Surface Area  m2/m3
HP-140	Super H pack	140m2/m3
HP-190	Super H pack	190m2/m3
HP-240	Super H pack	240m2/m3
MP-250	Conventional Sheet Metal	250m2/m3
BX-500	Conventional Wire Gauze	500m2/m3

u  Comparison of vapor velocity,  F-Factor(Load) m/s√kg/m3   (Fig.3 and 4)

Super H pack; --------------------------Max. F-Factor=5

Conventional structured packing

Sheet Metal and Wire Gauze; Max. F-Factor=3

After F-Factor=3, 

Conventional structured packing----Pressure drop going up sharply  

 Flooding start. Impossible operation

Super H pack--------------------------------Pressure drop going up slowly

Stabilizing operation until F-Factor=5.

u  Comparison of separation efficiency  NTS/m  (Fig.3)

After F-Factor=3

Conventional structured packing------Separation efficiency going down sharply

                                   Impossible operation

Super H pack--------------------------------Separation efficiency going down slowly

                                   Stabilizing operation until F-Factor=5

u  Stabilizing operation of  Super H pack in wide range is a main feature which separation efficiency(Fig.3) and pressure drop(Fig.4) graphs show .

u  Separation efficiency of  Super H pack in minimum specific surface area is superior to conventional structured packing with large specific surface area which show  in Fig.3.

Conclusion

Super H pack is epoch-making structured packing which realized two-times larger treatment volume with high efficient separation simultaneously in condition of minimal specific surface area and minimal pressure drop.

Above features are proved in the distillation tests

In the revamping case, separation efficiency  will be  raised  and  treating volume will be increased two-times.

In the new plant case, column size will be reduced  and  cost-down will be realized in initial stage.

 Column height------------Shortening   by higher  NTS/m

Column diameter---------Shortening  by higher  F-Factor/NTS

Running cost down will be added by higher separation efficiency, larger treating volume and lower pressure drop.

Large economic impact of initial stage and running cost down will be expected in the actual chemical plant.

Super H pack which is of a simple structure with multiple vertical and parallel wires will be applicable to processing of fluid which will condense in the column or processing of dirty materials.

Application field of Super H pack are not only distillation but  also absorption, stripping, cooling and  aeration etc.

Especially, application of Super H pack for  absorption and stripping of CO2 which will  contribute to the earth will be highly expected.

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