CA1164186A - Controlling temperature of exothermic reactions by superheating steam - Google Patents
Controlling temperature of exothermic reactions by superheating steamInfo
- Publication number
- CA1164186A CA1164186A CA000379979A CA379979A CA1164186A CA 1164186 A CA1164186 A CA 1164186A CA 000379979 A CA000379979 A CA 000379979A CA 379979 A CA379979 A CA 379979A CA 1164186 A CA1164186 A CA 1164186A
- Authority
- CA
- Canada
- Prior art keywords
- steam
- superheating
- reaction chamber
- heat accumulation
- stages
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
- B01J8/1809—Controlling processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
- B01J8/1836—Heating and cooling the reactor
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/69—Sulfur trioxide; Sulfuric acid
- C01B17/74—Preparation
- C01B17/76—Preparation by contact processes
- C01B17/77—Fluidised-bed processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
- B01J2208/00008—Controlling the process
- B01J2208/00017—Controlling the temperature
- B01J2208/00026—Controlling or regulating the heat exchange system
- B01J2208/00035—Controlling or regulating the heat exchange system involving measured parameters
- B01J2208/00044—Temperature measurement
- B01J2208/00061—Temperature measurement of the reactants
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
- B01J2208/00008—Controlling the process
- B01J2208/00017—Controlling the temperature
- B01J2208/00026—Controlling or regulating the heat exchange system
- B01J2208/00035—Controlling or regulating the heat exchange system involving measured parameters
- B01J2208/00079—Fluid level measurement
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
- B01J2208/00008—Controlling the process
- B01J2208/00017—Controlling the temperature
- B01J2208/00026—Controlling or regulating the heat exchange system
- B01J2208/00035—Controlling or regulating the heat exchange system involving measured parameters
- B01J2208/00088—Flow rate measurement
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
- B01J2208/00008—Controlling the process
- B01J2208/00017—Controlling the temperature
- B01J2208/00106—Controlling the temperature by indirect heat exchange
- B01J2208/00115—Controlling the temperature by indirect heat exchange with heat exchange elements inside the bed of solid particles
- B01J2208/00141—Coils
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
- B01J2208/00008—Controlling the process
- B01J2208/00017—Controlling the temperature
- B01J2208/00106—Controlling the temperature by indirect heat exchange
- B01J2208/00168—Controlling the temperature by indirect heat exchange with heat exchange elements outside the bed of solid particles
- B01J2208/00256—Controlling the temperature by indirect heat exchange with heat exchange elements outside the bed of solid particles in a heat exchanger for the heat exchange medium separate from the reactor
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Physical Or Chemical Processes And Apparatus (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Engine Equipment That Uses Special Cycles (AREA)
Abstract
"Controlling Temperature Of Exothermic Reactions By Superheating Steam"
ABSTRACT OF THE DISCLOSURE
A process for controlling the temperature of an exothermic reaction employing superheating of steam to effect cooling, comprising removing steam from a constant pressure heat accumulation zone filled with boiling water and positioned apart from a reaction chamber, the steam being guided by force through into the reaction chamber and into the heat accumulation zone in several cycles, the steam being superheated in the reaction chamber and then being cooled in the heat accumulation zone by indirect evaporation cooling, the steam being maintained at constant pressure in the heat accumulation zone, the number of superheating and recooling cycles being selected such that the ratio of the total of the enthalpy differences of the recooling stages to the enthalpy difference be-tween the saturated steam and feed water supplied is at least 1.1.
Le A 17 896
ABSTRACT OF THE DISCLOSURE
A process for controlling the temperature of an exothermic reaction employing superheating of steam to effect cooling, comprising removing steam from a constant pressure heat accumulation zone filled with boiling water and positioned apart from a reaction chamber, the steam being guided by force through into the reaction chamber and into the heat accumulation zone in several cycles, the steam being superheated in the reaction chamber and then being cooled in the heat accumulation zone by indirect evaporation cooling, the steam being maintained at constant pressure in the heat accumulation zone, the number of superheating and recooling cycles being selected such that the ratio of the total of the enthalpy differences of the recooling stages to the enthalpy difference be-tween the saturated steam and feed water supplied is at least 1.1.
Le A 17 896
Description
I 1 6~ 18~
"Controlling Temperature of Exothermic Reactions By Superheating Steam"
This present invention relates to a process for controlling the temperature of exothermic reactions by superheating stea~, in which the steam is guided by force between a heat accumulator and a reaction chamber in several cycles.
A restriction is imposed on the conventional method of removing the chemical heat of a process using so-called waste-heat boilers, whose evaporators are positioned in the reaction chamber or in the connected product paths, when an exact observance of specific temperaturesis required and where simultaneously there are considerable fluctuations in the amount of heat evolved or when the evaporation temperatures are below the dew point of corrosive media.
The process according to the invention is suitable in general for such processes an~ allows a very precise temperature control. Thus, for example, the heavily exothermic conversion of methanol into hydro-carbons in a fluidized bed may be effectively temperature-controlled using the process according to the invention.
Another example of the joint occurrence of such complicating conditions is the sul~hatizing roasting of sulphidic ores, in which the copper and zinc sulphides which are in mixed concentrates are to be converted into soluble sulphates, but pyrites which is also present is to be converted into insoluble Fe203, for which purpose an exact temperature control is required in the range of from 620 to 670C, depending on the type of concentrate.
The heat to be removed thereby fluctuates as a result of the changing concentrate composition. Sulphuric acid dew points of up to 300C are produced, conditioned by the water introduced with the roasting air and the Le A 17 896 ~ 1~41~
adhesive moisture of the ore and by the so3-partial pressure required for sulphatization.
Similar corrosi~-e conditions prevail in the wet-catalytic contacting of gases containing S02.
However, even under non-corrosive conditions, such as, for e~ample, in the catalysis of dry gases containing S02 in a fluidized bed, an evaporator is unsuitable as a control heating surface, particularly when, as in processing installations, the concentrations or quantities fluctuate. The process according to the ir.vention is particularly suitable for controlling the temperature of catalytic reactions, in particular the catalytic conversion of S02 into S03, in fluidized beds.
The term "fluidized beds" is understood to designate fluidized beds with or without discharge or circulation control of the fluidized mass.
According to the invention, the requirements are complied with under the conditions mentioned above, according to which steam of a corresponding temperature is provided as a cooling medium. The o~ject of this proposal is to produce this cooling steam without arranging an evaporator in the reaction chamber or product path, which are the only sources oE heat of the processes under consideration, but from its own process heat.
Thus, the present invention provides a process for controlling the temperature of exothermic reactions by superheating steam, which is characterized in that steam as cooling medium is removed from a constant pressure-heat accumulator filled with boiling water and positioned apart from the reaction chamber, is guided by force through into the reaction chamber in several cycles, is there superheated and is then recooled Le A 17 896 ~ ~643 85 respectively in the heat accumulator by ir,direct evaporation cooling, whereby the steam is maintained at constant pressure in the heat accumulator, the number of superheating and recooling cycles being selected such that the ratio of the total of the enthalpy differences of the recooling stages to the enthalpy difference between the saturated steam and feed-water supplied is as least l.l.
The invention will be further described with refer-ence to the accompanying drawings wherein:
Figure 1a is â flow sheet of an apparatus for carrying out one embodiment of the novel process;
Figure 1b is a graphic illustration of the steam conditions prevailing at various points of the apparatus of Figure 1a; and Figure 2 is a flow sheet of an apparatus for carry-ing out another embodiment of the novel process when cool-ing corrosive media.
Referring now more partlcularly to the drawings, one system which has been proposed consists of superheating heating surfaces positioned in the reaction chamber or in the product paths and a constant-pressure heat accumulator which is indirectly charged and positioned outside the reaction chamber or the production paths, as shown in Figure 1 a.
In this figure, the reference numbers represent the following:
l. Entry of the reaction gas
"Controlling Temperature of Exothermic Reactions By Superheating Steam"
This present invention relates to a process for controlling the temperature of exothermic reactions by superheating stea~, in which the steam is guided by force between a heat accumulator and a reaction chamber in several cycles.
A restriction is imposed on the conventional method of removing the chemical heat of a process using so-called waste-heat boilers, whose evaporators are positioned in the reaction chamber or in the connected product paths, when an exact observance of specific temperaturesis required and where simultaneously there are considerable fluctuations in the amount of heat evolved or when the evaporation temperatures are below the dew point of corrosive media.
The process according to the invention is suitable in general for such processes an~ allows a very precise temperature control. Thus, for example, the heavily exothermic conversion of methanol into hydro-carbons in a fluidized bed may be effectively temperature-controlled using the process according to the invention.
Another example of the joint occurrence of such complicating conditions is the sul~hatizing roasting of sulphidic ores, in which the copper and zinc sulphides which are in mixed concentrates are to be converted into soluble sulphates, but pyrites which is also present is to be converted into insoluble Fe203, for which purpose an exact temperature control is required in the range of from 620 to 670C, depending on the type of concentrate.
The heat to be removed thereby fluctuates as a result of the changing concentrate composition. Sulphuric acid dew points of up to 300C are produced, conditioned by the water introduced with the roasting air and the Le A 17 896 ~ 1~41~
adhesive moisture of the ore and by the so3-partial pressure required for sulphatization.
Similar corrosi~-e conditions prevail in the wet-catalytic contacting of gases containing S02.
However, even under non-corrosive conditions, such as, for e~ample, in the catalysis of dry gases containing S02 in a fluidized bed, an evaporator is unsuitable as a control heating surface, particularly when, as in processing installations, the concentrations or quantities fluctuate. The process according to the ir.vention is particularly suitable for controlling the temperature of catalytic reactions, in particular the catalytic conversion of S02 into S03, in fluidized beds.
The term "fluidized beds" is understood to designate fluidized beds with or without discharge or circulation control of the fluidized mass.
According to the invention, the requirements are complied with under the conditions mentioned above, according to which steam of a corresponding temperature is provided as a cooling medium. The o~ject of this proposal is to produce this cooling steam without arranging an evaporator in the reaction chamber or product path, which are the only sources oE heat of the processes under consideration, but from its own process heat.
Thus, the present invention provides a process for controlling the temperature of exothermic reactions by superheating steam, which is characterized in that steam as cooling medium is removed from a constant pressure-heat accumulator filled with boiling water and positioned apart from the reaction chamber, is guided by force through into the reaction chamber in several cycles, is there superheated and is then recooled Le A 17 896 ~ ~643 85 respectively in the heat accumulator by ir,direct evaporation cooling, whereby the steam is maintained at constant pressure in the heat accumulator, the number of superheating and recooling cycles being selected such that the ratio of the total of the enthalpy differences of the recooling stages to the enthalpy difference between the saturated steam and feed-water supplied is as least l.l.
The invention will be further described with refer-ence to the accompanying drawings wherein:
Figure 1a is â flow sheet of an apparatus for carrying out one embodiment of the novel process;
Figure 1b is a graphic illustration of the steam conditions prevailing at various points of the apparatus of Figure 1a; and Figure 2 is a flow sheet of an apparatus for carry-ing out another embodiment of the novel process when cool-ing corrosive media.
Referring now more partlcularly to the drawings, one system which has been proposed consists of superheating heating surfaces positioned in the reaction chamber or in the product paths and a constant-pressure heat accumulator which is indirectly charged and positioned outside the reaction chamber or the production paths, as shown in Figure 1 a.
In this figure, the reference numbers represent the following:
l. Entry of the reaction gas
2. Fluidized bed reactor
3. Exit of the reaction gas 30 4. Heat accumulator 5. Supply line for cooling steam 6. Temperature sensor .
7. Temperature control valve 8. Superheating stages in the fluidized bed Le A 17 896 ~ 16~3186 9. Récooling stages in the heat accumulator 10. Supply of feed-water to the heat accumulator 11. Level control valve for feed~water 12. Pressure control valve 5 13. Removal of excess steam 14~ Mixer 15. Temperature control valve 16. Bypass line 17. Diversion for cooling steam 10 18. Mixer 19. Connection line between mixers 18 and 14 20. Line to the steam network The manner of operation is as follows:
Saturated steam is removed from the heat accumulator 4 through the line 5, controlled by the temperature sensor 6 and valve 7, and is superheated in several cycles in each one of the at least four, preferably six to twelve, and most preferably eight to ten superheating stages 8, located in the fluidized bed 2, and is then recooled in each respective one of the recooling stages 9 located in the heat accumulator 4.
A balance between the heat removed from the accumulator 4 in the form of saturated steam for cooling the fluidized bed and the heat returned indirectly by means of the recooling stages 9 into the accumulator
7. Temperature control valve 8. Superheating stages in the fluidized bed Le A 17 896 ~ 16~3186 9. Récooling stages in the heat accumulator 10. Supply of feed-water to the heat accumulator 11. Level control valve for feed~water 12. Pressure control valve 5 13. Removal of excess steam 14~ Mixer 15. Temperature control valve 16. Bypass line 17. Diversion for cooling steam 10 18. Mixer 19. Connection line between mixers 18 and 14 20. Line to the steam network The manner of operation is as follows:
Saturated steam is removed from the heat accumulator 4 through the line 5, controlled by the temperature sensor 6 and valve 7, and is superheated in several cycles in each one of the at least four, preferably six to twelve, and most preferably eight to ten superheating stages 8, located in the fluidized bed 2, and is then recooled in each respective one of the recooling stages 9 located in the heat accumulator 4.
A balance between the heat removed from the accumulator 4 in the form of saturated steam for cooling the fluidized bed and the heat returned indirectly by means of the recooling stages 9 into the accumulator
4 occurs when the total of the enthalpy differences of the steam recooled in the recooling stages 9 is the same as the enthalpy difference between the feed-water supplied through the line 10 and the steam removed through the line 5.
This balance is adjusted according to the invention independently of the pre-determined or Le A 17 896 4 ~
selected steam conditions over the number of superheating and recooling cycles.
However, any other ratios greater than l may also be adjusted over the number of superheating and recooling cycles. More steam is always produced in the heat accumulator 4 as a result of this measure according to the invention than is removed therefrom for cooling purposes.
The greater the ratio of the total of the enthalpy differences of the steam recooled in the recooling stages to the enthalpy differences between the steam and feed-water is chosen to ke, the more resiliently the system reacts to fluctuating quantities of heat to be removed:
Excess steam which is not required for cooling is released through the line 13, pressure controlled by the valve 12.
In order to obtain useful steam released`
through the line 20 to the required superheating extent, a part of the quantity of steam used for cooling the 20 fluidized bed is heated in the last of the superheating stages 8 after the last of the recooling stages 9, temperature-controlled by the valve 15, so that the required condition is produced by combining the cooling steam with the excess saturated steam after bringing 25 together the lines 16 and 17 in the mixer 18 and further conveying through the line l9.
The steam conditions passed through in the manner described above are shown in Figure lb.
In thisfigure~ the reference letters 30 represent the following:
tw - temperature of feed-water ts = temperature of saturated steam tu = superheating temperature tk = temperature of the fluidized bed Le A 17 896 ~ 164185 tD = temperature after the last superheating stage tA = temperature of the useful steam released i = enthalpy at the respective temperatures The diagram also clearly shows that by choosing the number of superheating and recooling cycles, any temperature range of the steam used for cooling may be chosen.
A most extensive thermostatization of reaction processes is possible in particular with a small enthalpy difference in the stages with a corresponding increase in the number of the stages.
The reference numbers in Figure 2 represent the following:
15 21 fluidized roaster 22 charge 23 discharge 24 roasting air entry accumulator 20 26 line 27 temperature sensor 28 valve 29 heat exchanger superheating stages 25 31 recooling stages 32 line 33 valve 34 valve line 30 36 line 37 mixer 38 valve 39 line Le A 17 896 -~ 16418~
mixer 41 line 42 exit When cooling corrosive media, with otherwise the same procedure of using steam for cooling, according to Figure 2, the steam is pre-heated to a temperature outside the corrosive range in the indirect heat exchanger 29 before entering the first superheating stage.
The heat accumulator may be prepared for operation iJl a simple manner, for example, by blowing in network steam if this is available. If it is not available, the first charging is effected by a circulation evaporator which is not shown in the figure, during the heating-commencement procedure using the same heating gases with which the fluidized bed is brought to working temperature.
The operating manner of the system of temperature control according to the invention will be described in more detail in the following examples of an S03-fluidized catalysis and a sulphatizing roasting process.
Example 1 Using the apparatus of Figure la, 30,000 m3 (based on normal conditions of 0C and 1.013 bars) per hour with approximately 14% by volume of S02 and 10% by volume f 2 enter at a temperature of 380C
through the line 1 into a fluidized bed 2 with a contact mass.
The temperature of the reaction gas issuing through the line 3 is 480C. The catalytic conversiGn into S03 is 93% and the heat to be removed by cooling after drawing off the losses is 1,.12 x 106 kJ/h.
Le A 17 896 1 8 ~
In order to remo~-e this heat, 4511 kg of saturated steam at 35 bars and 241.4C corresponding to an enthalpy of 2803 kJ/kg are removed from the heat accumulator 4 through the line 5, controlled b~ the temperature sensor 6 and the valve 7, and are heated in the first of the superheating stages 8 to 440C, corresponding to an enthalpy of 3316 kJ/kg.
The steam is then recooled to 275C in the first of the recooling stages 9 located in that heat accumulator 4, corresponding to an enthalpy of 2931 kJ/kg~
The enthalpy difference of385 kJ/kg produced in the heat accumulator 4 corresponds, with the quantity of steam of 4511 kg/h, to the heat required for pre-heatlng and evaporation of 716 kg/h of feed-water which, at a temperature of 90C, is supplied to the heat accumulator 4 through the line 10 which is level-controlled by the valve 11.
The same quantity of steam of 4511 kg/h is then forced through each of the superheating stages 8 and each respective recooling stage 9 in six further successive cycles, whereby the steam is heated respectively from 275C, corresponding to an enthalpy f 2931~J/kg, to 440C, corresponding to an enthalpy Of 3316 kJ/kg, and is then recooled to a level of 275C.
A further 716 kg/h of feed-water are pre-heated from 90C to boiling temperature and evaporated by each of these recooling stages 9.
To summari~e, this means that 5013 kg/h of saturated steam at 35 bars and 241C are produced from a ~eed water at 90C in the accumulator 4 usirg 4511 kg/h of superheated steam which is recooled in a total of 7 stages.
Le A 17 896 ~ 16~86 g The ratio of the total quantity of steam produced to the quantity of steam used for cGoling the fluidized bed 2 amounts to 1.11, i.e. there is a control reserve of 11%.
The quantity of steam of~02 kg/h which is not required for cooling the ~luidized bed is introduced intc the mi~er 1~ through the line 13 as saturated steam, pressure controlled by the valve 12.
In order to obtain the steam produced in a quantity OL 5013 kg/h in a condition of 300C
corresponding to an enthalpy of2997 kJ/kg, a part of the quantity of steam used for contac- cooling is heated after the last in this case, the seventh stage of the recooling stages 9, temperature-controlled by the valve 15, in a further, in this case the eighth stage of the superheating stages 8 such that a temperature of 309C, corresponding to an enthalpy of 3020 kJ/kg, is obtained after combining the lines 16 and 17 downstream of the mixer 18.
This steam is combined with the 502 kg/h of saturated steam not required for contact cooling in the mixer 14 through the lir,e 19, so that 5013 kg/h of steam at 30 bars and 300C corresponding to an enthalpy of 2997 kJ/kg issue through the line 20.
Example 2 Using the apparatus of Figure 2, approximately 10.5 t/h of a concentrate of sulphidic Cu- Zn- and Fe ores are charged into a fluidi~ed roaster 21 through the charge entry 22 and the roasted material is removed at 23.
As a result of the roasting process, the Fe-portion should be converted into insoluble Fe203, but the Le A 17 896 ~ 164~8~
- 10 ~
Cu- and Zn-portions should be converted into soluble sulphates. This selective process requires a precise temperature control, in this case at 650C.
The quantity of water introduced together with the moisture of the roasting air of 24,000 m3 (under normal conditions of 1.013 bars and 0C) per hour entering at 24, and with the adhesive moisture of the concentrate entering at 22, amounts to 1 t/h, whereby a sulphuric acid dew point of approximately 250C is produced at the S03-partial pressure required for sulphatization.
The heat of 32.7 x 106 kJ/h which is released in this process is removed as follows: 8000 kg/h of saturated steam at 35 bars and 241C, corresponding to an enthalpy of 2803 kJ/kg, are removed from the accumulator 25 through the line 26, controlled by the temperature sensor 27 and valve 28. As the temperature of this steam is below the sulphuric acid dew point, it is pre-heated to 280~C in the heat exchanger 29 before entering into the first of the superheating stages 30 in order to avoid corrosion, before it is heated to 500C, corresponding to an enthalpy of 3453 kJ/kg.
After producing an enthalpy difference of 141 kJ/kg in the saturated steam flowing in counter-flow in the heat exchanger 29, the steam ~low enters into the first of the recooling stages 31 located in the accumulator 25, where it is cooled to 280C, corresponding to an enthalpy of 2944 kJ/kg with pre-warming and evaporation of 1215 kg/h of the feed water entering at 90C through the line 32, level controlled by the valve 33.
During the further forced passage, the same quantity of steam of 8000 kg/h respectively passes in succession through one of the superheating stages 30 and Le A 17 896 ~ 16~18~
one of the recooling stages 31 in six further cycles, whereby the steam is heated respectively from 280C, corresponding to an enthalpy of 244 kJ~kg, to 500C, corresponding to an enthalpy of 3453 kJ/kg, and is then recooled to the level of 280C.
A further 1679 kg/h of feed water are pre-heated from 90C to the boiling temperature of 241C and are evaporated respectively with a steam flow of 8000 kg/h as a result of the enthalpy difference of 509 kJ/kg produced in each of the recooling stages 31.
~.fter passing through the last of the total of eight superheating stages 30 and after being heated to 500C, a part of the quantity of steam, temperature-controlled by the valve 34, is recooled in the last of the total of eight recooling stages such that a temperature of 350C, corresponding to an enthalpy of 3112 kJ/kg, is adjusted downstream of the mixer 37 after combining the lines 35 and 36.
The remaining 1,188.8 kg/h of the total of 12,476 kg/h of the feed water entering into the accumulator 25 through the line 32 at 90C, are pre-heated to the boiling temperature of 241.4C and are evaporated by producing an enthalpy difference of 341 kJ/kg with 8000 kg/h in the last of the total of eight recooling stages 31.
The quantity of saturated steam of 4,476 kg/h which is not required for cooling the fluidized roaster 21 i5 combined, pressure-controlled by the ~alve 38, through the line 39 in the mi~er 40 with the steam flow at 350C
coming from the mixer 37, so that 12,476 kg/h of steam at 30~ C~ corresponding to an enthalpy of 2994 kJ/kg, are removed at 42 through the line 41.
The ratio of the total quantity of steam Le A 17 896 ~ 1~4~8~
produced to the quantity of steam required for cooling the fluidized roaster 31 amounts to 1.56, thus providing an adequate control reservefor sudden load excesses.
When processing the same ~uantity of concentrate according to the hitherto conventional method of temperature control by directly spraying in water of approximately 10.5 t/h, the volume of roastins gas issuing at 42 would increase from 21,000 to approximately 33,000 m3 N/h as a result of which, in addition to the energy loss, an increase in the cross-section of the fluidi~ed roaster 21 by approximately 50% in contrast to the process according to the invention would have to be accepted as another disadvantage.
It will be appreciated that the instant specification and examples are set forth by way of illustration and not limitation, and that various modifications and changes may be made without departing from the spirit and scope of the present invention.
Le A 17 896
This balance is adjusted according to the invention independently of the pre-determined or Le A 17 896 4 ~
selected steam conditions over the number of superheating and recooling cycles.
However, any other ratios greater than l may also be adjusted over the number of superheating and recooling cycles. More steam is always produced in the heat accumulator 4 as a result of this measure according to the invention than is removed therefrom for cooling purposes.
The greater the ratio of the total of the enthalpy differences of the steam recooled in the recooling stages to the enthalpy differences between the steam and feed-water is chosen to ke, the more resiliently the system reacts to fluctuating quantities of heat to be removed:
Excess steam which is not required for cooling is released through the line 13, pressure controlled by the valve 12.
In order to obtain useful steam released`
through the line 20 to the required superheating extent, a part of the quantity of steam used for cooling the 20 fluidized bed is heated in the last of the superheating stages 8 after the last of the recooling stages 9, temperature-controlled by the valve 15, so that the required condition is produced by combining the cooling steam with the excess saturated steam after bringing 25 together the lines 16 and 17 in the mixer 18 and further conveying through the line l9.
The steam conditions passed through in the manner described above are shown in Figure lb.
In thisfigure~ the reference letters 30 represent the following:
tw - temperature of feed-water ts = temperature of saturated steam tu = superheating temperature tk = temperature of the fluidized bed Le A 17 896 ~ 164185 tD = temperature after the last superheating stage tA = temperature of the useful steam released i = enthalpy at the respective temperatures The diagram also clearly shows that by choosing the number of superheating and recooling cycles, any temperature range of the steam used for cooling may be chosen.
A most extensive thermostatization of reaction processes is possible in particular with a small enthalpy difference in the stages with a corresponding increase in the number of the stages.
The reference numbers in Figure 2 represent the following:
15 21 fluidized roaster 22 charge 23 discharge 24 roasting air entry accumulator 20 26 line 27 temperature sensor 28 valve 29 heat exchanger superheating stages 25 31 recooling stages 32 line 33 valve 34 valve line 30 36 line 37 mixer 38 valve 39 line Le A 17 896 -~ 16418~
mixer 41 line 42 exit When cooling corrosive media, with otherwise the same procedure of using steam for cooling, according to Figure 2, the steam is pre-heated to a temperature outside the corrosive range in the indirect heat exchanger 29 before entering the first superheating stage.
The heat accumulator may be prepared for operation iJl a simple manner, for example, by blowing in network steam if this is available. If it is not available, the first charging is effected by a circulation evaporator which is not shown in the figure, during the heating-commencement procedure using the same heating gases with which the fluidized bed is brought to working temperature.
The operating manner of the system of temperature control according to the invention will be described in more detail in the following examples of an S03-fluidized catalysis and a sulphatizing roasting process.
Example 1 Using the apparatus of Figure la, 30,000 m3 (based on normal conditions of 0C and 1.013 bars) per hour with approximately 14% by volume of S02 and 10% by volume f 2 enter at a temperature of 380C
through the line 1 into a fluidized bed 2 with a contact mass.
The temperature of the reaction gas issuing through the line 3 is 480C. The catalytic conversiGn into S03 is 93% and the heat to be removed by cooling after drawing off the losses is 1,.12 x 106 kJ/h.
Le A 17 896 1 8 ~
In order to remo~-e this heat, 4511 kg of saturated steam at 35 bars and 241.4C corresponding to an enthalpy of 2803 kJ/kg are removed from the heat accumulator 4 through the line 5, controlled b~ the temperature sensor 6 and the valve 7, and are heated in the first of the superheating stages 8 to 440C, corresponding to an enthalpy of 3316 kJ/kg.
The steam is then recooled to 275C in the first of the recooling stages 9 located in that heat accumulator 4, corresponding to an enthalpy of 2931 kJ/kg~
The enthalpy difference of385 kJ/kg produced in the heat accumulator 4 corresponds, with the quantity of steam of 4511 kg/h, to the heat required for pre-heatlng and evaporation of 716 kg/h of feed-water which, at a temperature of 90C, is supplied to the heat accumulator 4 through the line 10 which is level-controlled by the valve 11.
The same quantity of steam of 4511 kg/h is then forced through each of the superheating stages 8 and each respective recooling stage 9 in six further successive cycles, whereby the steam is heated respectively from 275C, corresponding to an enthalpy f 2931~J/kg, to 440C, corresponding to an enthalpy Of 3316 kJ/kg, and is then recooled to a level of 275C.
A further 716 kg/h of feed-water are pre-heated from 90C to boiling temperature and evaporated by each of these recooling stages 9.
To summari~e, this means that 5013 kg/h of saturated steam at 35 bars and 241C are produced from a ~eed water at 90C in the accumulator 4 usirg 4511 kg/h of superheated steam which is recooled in a total of 7 stages.
Le A 17 896 ~ 16~86 g The ratio of the total quantity of steam produced to the quantity of steam used for cGoling the fluidized bed 2 amounts to 1.11, i.e. there is a control reserve of 11%.
The quantity of steam of~02 kg/h which is not required for cooling the ~luidized bed is introduced intc the mi~er 1~ through the line 13 as saturated steam, pressure controlled by the valve 12.
In order to obtain the steam produced in a quantity OL 5013 kg/h in a condition of 300C
corresponding to an enthalpy of2997 kJ/kg, a part of the quantity of steam used for contac- cooling is heated after the last in this case, the seventh stage of the recooling stages 9, temperature-controlled by the valve 15, in a further, in this case the eighth stage of the superheating stages 8 such that a temperature of 309C, corresponding to an enthalpy of 3020 kJ/kg, is obtained after combining the lines 16 and 17 downstream of the mixer 18.
This steam is combined with the 502 kg/h of saturated steam not required for contact cooling in the mixer 14 through the lir,e 19, so that 5013 kg/h of steam at 30 bars and 300C corresponding to an enthalpy of 2997 kJ/kg issue through the line 20.
Example 2 Using the apparatus of Figure 2, approximately 10.5 t/h of a concentrate of sulphidic Cu- Zn- and Fe ores are charged into a fluidi~ed roaster 21 through the charge entry 22 and the roasted material is removed at 23.
As a result of the roasting process, the Fe-portion should be converted into insoluble Fe203, but the Le A 17 896 ~ 164~8~
- 10 ~
Cu- and Zn-portions should be converted into soluble sulphates. This selective process requires a precise temperature control, in this case at 650C.
The quantity of water introduced together with the moisture of the roasting air of 24,000 m3 (under normal conditions of 1.013 bars and 0C) per hour entering at 24, and with the adhesive moisture of the concentrate entering at 22, amounts to 1 t/h, whereby a sulphuric acid dew point of approximately 250C is produced at the S03-partial pressure required for sulphatization.
The heat of 32.7 x 106 kJ/h which is released in this process is removed as follows: 8000 kg/h of saturated steam at 35 bars and 241C, corresponding to an enthalpy of 2803 kJ/kg, are removed from the accumulator 25 through the line 26, controlled by the temperature sensor 27 and valve 28. As the temperature of this steam is below the sulphuric acid dew point, it is pre-heated to 280~C in the heat exchanger 29 before entering into the first of the superheating stages 30 in order to avoid corrosion, before it is heated to 500C, corresponding to an enthalpy of 3453 kJ/kg.
After producing an enthalpy difference of 141 kJ/kg in the saturated steam flowing in counter-flow in the heat exchanger 29, the steam ~low enters into the first of the recooling stages 31 located in the accumulator 25, where it is cooled to 280C, corresponding to an enthalpy of 2944 kJ/kg with pre-warming and evaporation of 1215 kg/h of the feed water entering at 90C through the line 32, level controlled by the valve 33.
During the further forced passage, the same quantity of steam of 8000 kg/h respectively passes in succession through one of the superheating stages 30 and Le A 17 896 ~ 16~18~
one of the recooling stages 31 in six further cycles, whereby the steam is heated respectively from 280C, corresponding to an enthalpy of 244 kJ~kg, to 500C, corresponding to an enthalpy of 3453 kJ/kg, and is then recooled to the level of 280C.
A further 1679 kg/h of feed water are pre-heated from 90C to the boiling temperature of 241C and are evaporated respectively with a steam flow of 8000 kg/h as a result of the enthalpy difference of 509 kJ/kg produced in each of the recooling stages 31.
~.fter passing through the last of the total of eight superheating stages 30 and after being heated to 500C, a part of the quantity of steam, temperature-controlled by the valve 34, is recooled in the last of the total of eight recooling stages such that a temperature of 350C, corresponding to an enthalpy of 3112 kJ/kg, is adjusted downstream of the mixer 37 after combining the lines 35 and 36.
The remaining 1,188.8 kg/h of the total of 12,476 kg/h of the feed water entering into the accumulator 25 through the line 32 at 90C, are pre-heated to the boiling temperature of 241.4C and are evaporated by producing an enthalpy difference of 341 kJ/kg with 8000 kg/h in the last of the total of eight recooling stages 31.
The quantity of saturated steam of 4,476 kg/h which is not required for cooling the fluidized roaster 21 i5 combined, pressure-controlled by the ~alve 38, through the line 39 in the mi~er 40 with the steam flow at 350C
coming from the mixer 37, so that 12,476 kg/h of steam at 30~ C~ corresponding to an enthalpy of 2994 kJ/kg, are removed at 42 through the line 41.
The ratio of the total quantity of steam Le A 17 896 ~ 1~4~8~
produced to the quantity of steam required for cooling the fluidized roaster 31 amounts to 1.56, thus providing an adequate control reservefor sudden load excesses.
When processing the same ~uantity of concentrate according to the hitherto conventional method of temperature control by directly spraying in water of approximately 10.5 t/h, the volume of roastins gas issuing at 42 would increase from 21,000 to approximately 33,000 m3 N/h as a result of which, in addition to the energy loss, an increase in the cross-section of the fluidi~ed roaster 21 by approximately 50% in contrast to the process according to the invention would have to be accepted as another disadvantage.
It will be appreciated that the instant specification and examples are set forth by way of illustration and not limitation, and that various modifications and changes may be made without departing from the spirit and scope of the present invention.
Le A 17 896
Claims (5)
1. A process for controlling the temperature of an exothermic reaction employing superheating of steam to effect cooling, comprising removing steam from a constant pressure heat accumulation zone filled with boiling water and positioned apart from a reaction chamber, the steam being guided by force through into the reaction chamber and into the heat accumulation zone in several cycles, the steam being superheated in the reaction chamber and then being cooled in the heat accumulation zone by indirect evaporation cooling, the steam being maintained at constant pressure in the heat accumulation zone, the number of super-heating and recooling cycles being selected such that the ratio of the total of the enthalpy differences of the re-cooling stages to the enthalpy difference between the satura-ted steam and feed water supplied is at least 1.1.
2. A process according to claim 1, wherein the satura-ted steam removed from the heat accumulator is pre-heated before entering the first superheating stage by indirect heat exchange with the highly superheated steam issuing from one of the superheating stages.
3. A process according to claim 1, wherein the reaction chamber is a fluidized bed reactor.
Le A 17 896 -US
Le A 17 896 -US
4. A process according to claim 1, wherein the exothermic reaction is an S02- catalysis.
5. A process according to claim 1, wherein the exother-mic reaction is a sulphatizing roasting process.
Le A 17 896 -US
Le A 17 896 -US
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3022800.3 | 1980-06-19 | ||
| DE19803022800 DE3022800A1 (en) | 1980-06-19 | 1980-06-19 | METHOD FOR TEMPERATURE CONTROL OF EXOTHERMAL REACTIONS BY OVERHEATING WATER VAPOR |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1164186A true CA1164186A (en) | 1984-03-27 |
Family
ID=6104875
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000379979A Expired CA1164186A (en) | 1980-06-19 | 1981-06-17 | Controlling temperature of exothermic reactions by superheating steam |
Country Status (12)
| Country | Link |
|---|---|
| EP (1) | EP0042519B1 (en) |
| JP (1) | JPS602906B2 (en) |
| AU (1) | AU538206B2 (en) |
| BR (1) | BR8103826A (en) |
| CA (1) | CA1164186A (en) |
| DE (2) | DE3022800A1 (en) |
| DK (1) | DK267981A (en) |
| ES (1) | ES8203634A1 (en) |
| FI (1) | FI66763C (en) |
| NO (1) | NO151071C (en) |
| PT (1) | PT73158B (en) |
| ZA (1) | ZA814117B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3412482A1 (en) * | 1984-04-03 | 1985-10-10 | Linde Ag, 6200 Wiesbaden | Process and reactor for the catalytic dehydration of methanol and/or dimethyl ether |
| JP3720386B2 (en) * | 1993-12-27 | 2005-11-24 | 住友製薬株式会社 | Drug release controlled formulation |
| KR100824976B1 (en) * | 2006-06-01 | 2008-04-28 | 주식회사 효성 | Preparation process of 1,5-dimethyltetralin |
| FI120905B (en) | 2008-08-12 | 2010-04-30 | Stora Enso Oyj | Einespakkaus |
| FR3010916A1 (en) | 2013-09-26 | 2015-03-27 | Gdf Suez | METHANATION REACTOR FOR REACTING DIHYDROGEN WITH AT LEAST ONE CARBON-BASED COMPOUND AND PRODUCING METHANE |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2735743A (en) * | 1956-02-21 | Temperature- xe | ||
| GB740567A (en) * | 1952-04-22 | 1955-11-16 | Celleco Ab | Method and installation for regulating the heat transfer conditions in fluidised solids processes |
| DE1116644B (en) * | 1952-07-05 | 1961-11-09 | Combustion Eng | Plant for carrying out exothermic reactions over a catalyst fluidized bed and process for operating the plant |
| FR1312785A (en) * | 1962-01-26 | 1962-12-21 | Celleco Ab | Improved process for preparing sulfur trioxide from elemental sulfur |
| IT1007028B (en) * | 1974-01-23 | 1976-10-30 | Montedison Spa | TEMPERATURE REGULATION SYSTEM OF FLUID-BED CATALYTIC REACTORS OPERATING AT HIGH TEMPERATURE |
| DE2651567A1 (en) * | 1976-11-12 | 1978-05-24 | Didier Eng | PROCESS AND DEVICE FOR SETTING AND KEEPING THE TEMPERATURE DURING METHANIZATION |
-
1980
- 1980-06-19 DE DE19803022800 patent/DE3022800A1/en not_active Withdrawn
-
1981
- 1981-06-03 NO NO811889A patent/NO151071C/en unknown
- 1981-06-05 EP EP81104340A patent/EP0042519B1/en not_active Expired
- 1981-06-05 DE DE8181104340T patent/DE3160312D1/en not_active Expired
- 1981-06-09 PT PT73158A patent/PT73158B/en unknown
- 1981-06-17 FI FI811902A patent/FI66763C/en not_active IP Right Cessation
- 1981-06-17 BR BR8103826A patent/BR8103826A/en unknown
- 1981-06-17 ES ES503153A patent/ES8203634A1/en not_active Expired
- 1981-06-17 CA CA000379979A patent/CA1164186A/en not_active Expired
- 1981-06-18 ZA ZA814117A patent/ZA814117B/en unknown
- 1981-06-18 DK DK267981A patent/DK267981A/en not_active Application Discontinuation
- 1981-06-18 AU AU71951/81A patent/AU538206B2/en not_active Ceased
- 1981-06-18 JP JP56093112A patent/JPS602906B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| ES503153A0 (en) | 1982-04-16 |
| ZA814117B (en) | 1982-07-28 |
| JPS5730543A (en) | 1982-02-18 |
| NO151071C (en) | 1985-02-06 |
| PT73158B (en) | 1982-07-01 |
| NO811889L (en) | 1981-12-21 |
| JPS602906B2 (en) | 1985-01-24 |
| FI811902L (en) | 1981-12-20 |
| NO151071B (en) | 1984-10-29 |
| BR8103826A (en) | 1982-03-09 |
| DE3022800A1 (en) | 1982-01-07 |
| DE3160312D1 (en) | 1983-07-07 |
| AU7195181A (en) | 1981-12-24 |
| PT73158A (en) | 1981-07-01 |
| AU538206B2 (en) | 1984-08-02 |
| ES8203634A1 (en) | 1982-04-16 |
| EP0042519B1 (en) | 1983-05-18 |
| FI66763C (en) | 1984-12-10 |
| EP0042519A1 (en) | 1981-12-30 |
| FI66763B (en) | 1984-08-31 |
| DK267981A (en) | 1981-12-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102958829B (en) | Energy recovery in manufacture of sulfuric acid | |
| EP0181313B2 (en) | Heat recovery from concentrated sulfuric acid | |
| EP3233723B1 (en) | Process and plant for improved energy-efficient production of sulfuric acid | |
| CA2019462C (en) | Absorption of wet conversion gas | |
| US4368183A (en) | Process of producing concentrated sulfuric acid | |
| US3656900A (en) | Process for the catalytic conversion of sulfur dioxide to sulfur trioxide with production of sulfuric acid | |
| US3374061A (en) | Process for obtaining sulfuric acid | |
| CA1164186A (en) | Controlling temperature of exothermic reactions by superheating steam | |
| NZ237552A (en) | Contact process for the preparation of sulphuric acid in which reaction heat is recovered for use in pre-heating oxygen gas prior to combustion of sulphur | |
| US3490868A (en) | Method of recovery of sulphuric acid | |
| GB1598959A (en) | Process and device for the catalytic oxidation of gaseous sulphur compounds to sulphur trioxide | |
| US3525586A (en) | Production of sulfur trioxide and sulfuric acid | |
| US5538707A (en) | Acid concentration control in SO3 absorption | |
| US3780166A (en) | Process of catalytically reacting so2 to form so3 and of producing sulfuric acid | |
| US4445461A (en) | Waste heat recovery method and apparatus | |
| US3047365A (en) | Temperature control in the fluidized roasting process of sulfidic ores with the by-product recovery of steam | |
| US2934407A (en) | Method for the arrangement of thermodynamic relations | |
| US4088686A (en) | Urea synthesis with improved heat recovery and conversion | |
| US2629651A (en) | Manufacture of sulfuric acid | |
| US4334907A (en) | Phosphoric acid ammoniation process to produce liquid fertilizers | |
| US4495161A (en) | Energy recovery method and system for combined sulphuric acid and phosphoric acid manufacturing plant | |
| US2079760A (en) | Manufacture of sulphuric acid by the contact process | |
| US3988428A (en) | Sulfur-producing process and system for producing sulfur dioxide | |
| US2871107A (en) | Moisture control in gas generators | |
| US3709675A (en) | Process for producing liquid np fertilizers |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |