cokeman75
Chemical
- Oct 23, 2007
- 2
thread391-77843
Direct primary coolers in by products plant
Averta in his tread posted the wrong question MOISTURE DROP OUT. The coke ovens are in an integrated steel plant. The big problem is the naphthalene all over the plant, and distribution pipes clogged.
They increased pushed ovens from 50 to 60/62 ovens pushed/day COG production increased to 32,500 Nm3/day dry Design inlet Temp to direct cooler is 80°C OK inlet pressure 730 mm Hg,
Very high drop pressure from the ovens main collector in the ovens to primary cooler.
Normaly at ovens +- 0 WC pressure, at the inlet of the primary cooler -100 mm WC and a drop pressure in the direct cooler from 50 mm to 100 mm. This means that the pipe from the ovens to by product plant or is clogged with tar naphthalene and coal ultra fines, or the diameter is too small (designers wise penny) maybe 1,5000 mm NB (60 inches) for this flow,The flow in this pipe is a dual flow,ammonia liquor an tar at the bottom, vapor ,tar and naphthalene fog and COG at the top, the liquor flushes down by gravity to tar decanter, and COG saturated at 80°C goes to direct cooler,in direct coolers the minimum temperature of COG is 30°C to avoid problems with naphthalene. The heat duty to cool 1 Nm3 of dry gas saturated from 80/30°C is 446.31 kcal/Nm3 x 32,500 = 14,505,075 kcal/h TD2K warned this problem,to cool down the gas you need to recirculate approx 17 m3 of ammonia liquor /1000 Nm3 of COG dry = 552.5 m3 of cooled liquor to the sprays
Temperature of liquor must be 5°C to 8°C below gas exit temperature 30°C Tin = 30 - 5 = 25°C
Then you calculate delta-in liquor and , liquor outlet temp. The area needed in SPH for primary coolers goes from 40m2 to 60 m2/1000 Nm3 of gas. Average 50 m2 x 32.5 = 1,625 m2
consumption of industrial water from 24 lts to 32 lts/Nm3 of COG,must be careful to avoid outlet water temperature > 45°C to avoid incrustation in SHE. Peters advices 120°F = 48.8°C
If industrial cooling water inlet temperature is 22°C and T out 45°C Delta T = 22°C y water flow 659.3 m3/hr in SHE
Normally you calculate the condensates only to drain from the upper level in the bottom tank of the cooler,otherwise the column will flood,you never cool the condensate,it flows by gravity trough a seal pot,then to to a sump tank,and pumped hot to tar/liquor decanter (Temp 80°C), and clean liquor goes to a tank and pumped to coke filter to get rid off small amounts of tar and then to ammonia still.
At 65°C condensates almost all the tar, and there is no tar left to absorb the massive condensation o f naphthalene at 50-60°C, for this reason is necessary to add clean tar without ashes, at this level 65°C from 10 to 50 lts/1000 Nm3 of COG dry.
This formula can be used to calculate naphtalene content at the outlet of the cooler at 40°C
gr of naphthalene/Nm3 = 0.125 x 40°C – 2.92 = 7.08 g/Nm3 x 32,500 Nm3/h/1000 = 230.1 kg/h
Kgs/day = 5,522.4 kgs/day distributed all over the steel plant.
Tar content in COG at 40°C = 1,528.8 kg/day
They can clean with an hydro jet the pipe from battery to primary cooler,taking car not to cut big chomps otherwise they will go to down comer and then to tar decanter,breaking the scraper at the bottom.
other treads of averta on by products have the same root.
The volume of ammonia liquor at the bottom for this cooler maybe is H = 0.6 x 4 diameter =2.4 mt,for 32,500 Nm3/hr I suppose a diameter of 4.0 mys Area = 12.56 m2 ,volume = 30.14 m3
residence time = 3.27 minutes. The condensate must be bleeded at 2.4 mt to keep the level of ammonia liquor in the cooler
Supposed preliminary height of cooler 29.2 m, diameter 4.0 m Spraying height 23.3 spray density 43,99 m3/m2. Avesta must do all the math again with the real variables and dimensions.
.
Direct primary coolers in by products plant
Averta in his tread posted the wrong question MOISTURE DROP OUT. The coke ovens are in an integrated steel plant. The big problem is the naphthalene all over the plant, and distribution pipes clogged.
They increased pushed ovens from 50 to 60/62 ovens pushed/day COG production increased to 32,500 Nm3/day dry Design inlet Temp to direct cooler is 80°C OK inlet pressure 730 mm Hg,
Very high drop pressure from the ovens main collector in the ovens to primary cooler.
Normaly at ovens +- 0 WC pressure, at the inlet of the primary cooler -100 mm WC and a drop pressure in the direct cooler from 50 mm to 100 mm. This means that the pipe from the ovens to by product plant or is clogged with tar naphthalene and coal ultra fines, or the diameter is too small (designers wise penny) maybe 1,5000 mm NB (60 inches) for this flow,The flow in this pipe is a dual flow,ammonia liquor an tar at the bottom, vapor ,tar and naphthalene fog and COG at the top, the liquor flushes down by gravity to tar decanter, and COG saturated at 80°C goes to direct cooler,in direct coolers the minimum temperature of COG is 30°C to avoid problems with naphthalene. The heat duty to cool 1 Nm3 of dry gas saturated from 80/30°C is 446.31 kcal/Nm3 x 32,500 = 14,505,075 kcal/h TD2K warned this problem,to cool down the gas you need to recirculate approx 17 m3 of ammonia liquor /1000 Nm3 of COG dry = 552.5 m3 of cooled liquor to the sprays
Temperature of liquor must be 5°C to 8°C below gas exit temperature 30°C Tin = 30 - 5 = 25°C
Then you calculate delta-in liquor and , liquor outlet temp. The area needed in SPH for primary coolers goes from 40m2 to 60 m2/1000 Nm3 of gas. Average 50 m2 x 32.5 = 1,625 m2
consumption of industrial water from 24 lts to 32 lts/Nm3 of COG,must be careful to avoid outlet water temperature > 45°C to avoid incrustation in SHE. Peters advices 120°F = 48.8°C
If industrial cooling water inlet temperature is 22°C and T out 45°C Delta T = 22°C y water flow 659.3 m3/hr in SHE
Normally you calculate the condensates only to drain from the upper level in the bottom tank of the cooler,otherwise the column will flood,you never cool the condensate,it flows by gravity trough a seal pot,then to to a sump tank,and pumped hot to tar/liquor decanter (Temp 80°C), and clean liquor goes to a tank and pumped to coke filter to get rid off small amounts of tar and then to ammonia still.
At 65°C condensates almost all the tar, and there is no tar left to absorb the massive condensation o f naphthalene at 50-60°C, for this reason is necessary to add clean tar without ashes, at this level 65°C from 10 to 50 lts/1000 Nm3 of COG dry.
This formula can be used to calculate naphtalene content at the outlet of the cooler at 40°C
gr of naphthalene/Nm3 = 0.125 x 40°C – 2.92 = 7.08 g/Nm3 x 32,500 Nm3/h/1000 = 230.1 kg/h
Kgs/day = 5,522.4 kgs/day distributed all over the steel plant.
Tar content in COG at 40°C = 1,528.8 kg/day
They can clean with an hydro jet the pipe from battery to primary cooler,taking car not to cut big chomps otherwise they will go to down comer and then to tar decanter,breaking the scraper at the bottom.
other treads of averta on by products have the same root.
The volume of ammonia liquor at the bottom for this cooler maybe is H = 0.6 x 4 diameter =2.4 mt,for 32,500 Nm3/hr I suppose a diameter of 4.0 mys Area = 12.56 m2 ,volume = 30.14 m3
residence time = 3.27 minutes. The condensate must be bleeded at 2.4 mt to keep the level of ammonia liquor in the cooler
Supposed preliminary height of cooler 29.2 m, diameter 4.0 m Spraying height 23.3 spray density 43,99 m3/m2. Avesta must do all the math again with the real variables and dimensions.
.
