After the installation of the four grids and the three air plate distribution, you can proceed to the catalyst loading following the procedures here specified, operating from the man-holes.
For the equalization of the layers, use a small rake or similar. Take care of the thermocouples installed inside the converter. 1) Open all the four man-holes
2) Wad the gap between the grid edge and the inner converter wall using the relevant packing supplied by Marsina with the help of a device like a screwdriver or similar. This operation plugs a possible by-pass of the catalyst by the SO2/air gases.
3) You have available supplied by Marsina n .30 of 1” ceramic balls bags, 25 lts. each bag. Sub-supplier “Rauschert”. These balls should be set on each grid before the catalyst to avoid the catalyst pellets fall down through the grids openings and after the catalyst to avoid dispersion of the pellets their self. In both cases the thickness should be about 50 mm. that is about a two balls layer. Being the inner converter diameter 1450 mm., each bed needs 1,45x1,45x3,14/4 =m2 1,65
1,65x0,05 = 0,0825 mcx2 = 0,165 mc = 165 lt.of 1” balls = 6,6 bags ; 3,3 bags on the grid and 3,3 bags on the upper catalyst surface.
4) Proceed for each bed starting from the bottom (fourth bed), setting the lower ceramic balls layer, the catalyst and then the upper ceramic balls layer.
5) During the catalyst handling the operators should wear anti-dust mask. 6) the Monsanto catalyst supplied by Marsina is of two types :
a. type XLP-120 to be installed in the first bed (top bed) lt. 800
b. type XLP-110 to be installed in the second bed lt. 900 c. type XLP-110 to be installed in the third bed lt.1000 d. type XLP-110 to be installed in the fourth bed(bottom)lt.1000
it has been supplied in 200 lts.drums , 4 drums XLP-220 and 15 drums XLP- 110.
So you should distribute it in this way:
- 4,0 drums XLP-120 in the first bed (top)
- 4,5 drums XLP-110 in the second bed - 5,0 drums XLP-110 in the third bed
- 5,0 drums XLP-110 in the fourth bed (bottom)
7) After the operation has been completed, close the man-holes putting the insulation inside the cover as per previous instructions already in your hands.
11.4) R-301 SCRUBBER
Information about possible ways for scrubber management. The R-301 scrubber can be managed in two different ways:
In such a case the scrubber works continuously. A small amount of caustic is continuously fed to scrubber by means of the dosing pump P-302 under control of the pH-meter.
The SO2 absorbed gives Na2SO3 which is oxidized to Na2SO4 (roughly 80% sulphite
and 20 % sulphate).
The sulphite/sulphate solution is continuously transferred to the storage, being the level in R-301 maintained by water make-up.
The management of the scrubber in this case requires more care and control, but gives much more advantages from production and pollution point of view.
2) In excess of caustic soda at pH close to 14
In such a case the scrubber works batch wise. That is initially an amount of caustic necessary to neutralize the SO2 for 24-36, it hours is fed to the scrubber with some
excess.
The pump P-302 is stopped, of course. The scrubber will produce only sulphite.
The concentration of sulphite will start from zero and will gradually increase. The level in R-301 will be maintained by water make-up.
When the concentration will reach the desired value (not more than 10-12 %), the scrubber must be emptied and the caustic solution renewed.
The management of the scrubber in this case does not require much care, but the production of sulphite can give pollution problems.
11.4.1) Procedures for R-301 management.
These procedures start with empty scrubber. Volume of tank-scrubber about 7mc.
Useful volume about 6mc.
Plant capacity 3000 Kg/h
Solution density 1,1
30% caustic soda density 1.33
Case n. 1
- Fill the scrubber with about 5000 lt. of water.
- Put the pH-meter in automatic mode and set the pH value at 9. - Start the pump P-302.
- Start the recycling pump P-301 and fix the recycling rate at about 25 mc/h. - Keep close the transfer line to the storage.
- When the pH will reach value 9 bring the level with water to the floating regulator. - Bring back the set of the pH-meter to 7,5. The pump P-302 will stop immediately.
- Now the scrubber is ready to receive the exhausted gas. The sulphite/sulphate concentration will increase gradually and in about 37 hours will reach 10% concentration.
- When 10% concentration has been reached (check the density), the transfer to the storage can be started.
- From material balance we get:
Na2SO3/Na2SO4 production about 18 Kg/h = 180 Kg/h al 10% = 164 lt/h NaOH required 11,5 Kg/h at 100% = 38,2 Kg/h al 30% = lt/h 28,7
- So we have to transfer to the storage 164 Lt./h to maintain the concentration around 10%.
- Increasing the amount of the transfer decreases the concentration and viceversa.
Case n. 2
- Fill the scrubber with about 4000 lt. of water. - Put the pH-meter in manual mode.
- Add 1413 Kg of NaOH at 30%.
- Start the recycling pump P-301 and fix the recycling rate at about 25 mc/h. - Keep close the transfer line to the storage.
- Now the scrubber is ready to receive the exhausted gas .The sulphite/sulphate concentration will increase gradually and in about 37 hours will reach 10% concentration.
- When 10% concentration has been reached (check the density) ,transfer as much as possible the content of the R- 301 to the storage always maintaining the recycle.
- Add again 1413 Kg of NaOH 30% - Add water up to floating regulation.
- After about 37 hours repeat the operation and so on.
Useful calculation SO2 8,9 Kg/h NaOH 11,5 Kg/h = 38,2 Kg/h al 30% H2O with soda 30% = 26,7 Kg/h Reaction water 2,4 K/h Solids as sulphite 8,9+11,5 –2,4 = 18 Kg/h
For 10% conc. we have to add H2O = 180-18-2,4 = 159,6 Kg/h of which 26,7 come from soda 30%, while the fresh one is 159,6-26,7= 129,9 Kg/h
Total : 8,9+11,5+159,6 = 180 Kg/h /1,1 = 163,6 Lt./h 18/180 = 10%
The water which goes out with the gas at 50 °C is about 350 Kg/h (7000 Kg/h x 50gr/Kg)
At about 6000 lt. R-301 should be almost full, that is after 6000/163,6 = 37 hours compensating the water which evaporate with the exhausted gas.
In 37 hours the inputs should be : 8,9x 37 = 330 Kg SO2
38,2x37 = 1413 Kg NaOH 30% 129,9x 37 = 4806 Kg H2O Total 6549 Kg/ 1,1 = lt.5954
18x37 = 666 Kg 666/6549 = 10 %