METHOD AND APPARATUS FOR EVALUATING HYDROGEN CHLORIDE EVOLUTION AS A FUNCTION OF TEMPERATURE

Abstract

The present invention is in relation to a method and its apparatus, by means of which HCl generation formed from hydrolysis reactions or thermal decomposition of chloride salts is continuously monitored. Its application is in oil refining or in any other area where chloride salts are heated to temperatures high enough to cause hydrolysis reactions or thermal decomposition. The invention allows for a much more sophisticated and precise record of the thermal events that occur as a function of temperature. It also allows the behavior of chloride salts subjected to these conditions to be evaluated, both in model systems and in industrial saline solutions, with respect to the respective content, composition, or presence of components in the oil phase, such as carboxylic (naphthenic acids) or nitrogenous (ammonia or amines) acids.

Claims

1. Method of construction of the apparatus for evaluation of hydrogen chloride as a function of temperature, characterized by comprising the following steps: a) support the flask (1) with oil (14) on top of the heating mantle (15) and secure it by the larger mouth to a universal mount-clip-clamp (2); b) lay the heating mantle (15) on an elevating platform (3), to adjust the height of the system; c) insert the stirring rod (5) into the PEEK connection (8) provided with retainers (9), which connect to the central mouth of the flask (1); d) use silicone grease to facilitate the passage of the rod (5) through the retainers (9); e) connect the rod (5) to the stirring motor (20); f) carefully place this assembly into the larger mouth of the flask (1) and attach it to the stirring motor (20), always checking the alignment of the system; g) connect the gas-dispersing tube (4) to one side of the flask (1); h) fit a hose (10) to the upper end of this tube through which the inert gas (nitrogen) from the flow controller (21) will pass; i) use two heating tapes (18), one for the upper part of the flask (1) and the other for the gas conducting tube (7), electrically connected; j) wrap one of the heating tapes (18) around the conducting tube, including the separating section in the middle of the tube (7); k) wrap the thermocouple (17) and leave its end as close as possible to the separating funnel, thus the tube assembly (7)+thermocouple (17) will be wrapped in the heating tape; l) attach the conducting tube (7) to the other side of the flask (1) with the help of PEEK connectors (8); m) wrap the second heating tape (18) on the upper part of the three-necked flask (1), particularly around the necks; n) electrically connect the two heating tapes (18) to two of the tapes' temperature-controlling wires (19); o) at the other end of the conducting tube (7), attach a small PTFE hose with a second gas-dispersing tube (11); p) place the immersed sintered glass (4) into a 250-ml beaker (13) with a predetermined amount of deionized water (190 ml), on which the assembly is supported on the titrator's magnetic stirring base (22); q) connect a second thermocouple (17) to the respective inlet of the flask (1), dipping its end into the paraffin oil (14) and away from the stirring propeller (5).

2. Apparatus for evaluating hydrogen chloride as a function of temperature, as obtained in claim 1, comprising the following components: (1) modified three-way round-bottom flask; (2) universal support; (3) lifting platform (jack type); (4) sintered glass tube with gas disperser at the end; (5) glass rod and propeller for stirring; (6) stirring rod guide; (7) gas-conducting tube; (8) connectors; (9) nitrile rubber retainers; (10) silicone hose; (11) small hose with sintered glass gas-dispersing tube; (12) 25-mL beaker; (13) 250-mL beaker for potentiometric titrator; (14) oil with a high initial boiling point (paraffin oil); (15) heating mantle; (16) mantle temperature controller; (17) Type K thermocouples; (18) heating tapes; (19) heating tape temperature controller; (20) agitation motor; (21) flow controller; (22) potentiometric titrator; (23) small adapted separation funnel; (24) sensor (electrode); (25) nitrogen supply. wherein the continuous generation of HCl is monitored, from hydrolysis reactions or thermal decomposition of chloride salts.

3. Method for evaluation of hydrogen chloride evolution as a function of temperature, wherein it comprises the following steps: a) weigh the predetermined mass of paraffin oil (14) in the three-way flask (1); b) weigh pre-determined masses of chloride salts and dissolve them in water; c) add the chloride salts, pure or in aqueous solution, to the flask containing paraffin oil; d) reconnect the disconnected parts in order to add the sample; e) activate flow controller (21); f) activate stirring motor (20); g) activate the heating controller of the gas-conducting tube (19); h) start the heating program on the controller (17) of the mantle (15); i) initiate burette control; and j) start data acquisition in the potentiometric titrator (22).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be described in more detail below, referencing the attached figures which, schematically and in a manner that is not limiting on the inventive scope, show examples of the invention's embodiments. The drawings are as follows:

[0026] FIG. 1 contains a drawing of an apparatus for evaluating hydrogen chloride evolution that is comprised of: heating mantle (15), three-way round-bottom flask (1), temperature sensor (type K thermocouple) (17), stirring motor and transmission (20), condensate decantation funnel (23), burette containing standardized AgNO.sub.3 solution (22) and sensor (electrode) (24) for potentiometric titration;

[0027] FIG. 2 contains an apparatus for evaluating hydrogen chloride evolution that is comprised of: heating mantle (15), three-way round bottom flask (1), type K thermocouple (17), nitrogen supply (25), stirring rod (5) and motor (20), gas-conduction pipe (7) wrapped in heating tape, and a small adapted separation funnel (18), 250 mL beaker (13) for absorption and potentiometric titration of HCl and burette containing standardized AgNO.sub.3 solution (22);

[0028] FIG. 3 shows a flow controller (21), a heating strip temperature controller (19), and a blanket temperature controller (16);

[0029] FIG. 4 shows a computer and temperature data acquisition programs, and potentiometric titration with AgNO.sub.3 (volume of titrant added, and electrochemical potential of the HCl absorption solution);

[0030] FIG. 5 shows a graph of % accumulated chloride and % instantaneous chloride, as a function of the time of the experiment, referring to Example 1;

[0031] FIG. 6 shows a graph of % accumulated chloride and temperature of paraffin oil, as a function of the time of the experiment, referring to Example 2;

[0032] FIG. 7 shows a graph of % accumulated chloride and % instantaneous chloride, as a function of the temperature of the paraffin oil, referring to Example 3.

DETAILED DESCRIPTION OF THE INVENTION

[0033] The present invention deals with a method and its apparatus for continuous monitoring of HCl generation, resulting from hydrolysis reactions or thermal decomposition of chloride salts.

[0034] Hydrolysis or thermal decomposition occurs in a flask containing paraffin oil, to which a known mass of chloride salts, pure and/or dissolved in water has been added. The mixture is stirred throughout the entire test and heated according to a certain temperature ramp.

[0035] As the temperature of the paraffin oil rises, the hydrogen chloride generated in the flask is continuously dragged by the flow of an inert gas (nitrogen or helium, for example). The gas flow containing HCl is bubbled in water, contained in a flask for potentiometric titration. Hydrogen chloride is instantly absorbed, which causes a variation in the electrochemical potential of the medium. The variation is perceived by an appropriate sensor (electrode), which automatically sends the information to a potentiometric titrator. The titrator adds a titrant solution (standardized solution of AgNO3, NaOH or KOH, for example) in order to bring the electrochemical potential back to its original value. This process is repeated continuously throughout the test, until it is finished at the discretion of the operator or until the hydrolysis reactions or thermal decomposition of chloride salts are exhausted.

[0036] Data on the temperature of the paraffin oil, the electrochemical potential of the solution, and the volume of titrant are transmitted to a computer, which is also responsible for controlling the potentiometric titrator and processing the information. The titrant consumption corresponds to a certain mass of HCl that reaches the titration flask, which in turn occurs at a certain time following the start of the test, and at a certain temperature of the paraffin oil. In the end there are curves that plot the HCl generation rate and the total HCl generated as a function of time and temperature.

[0037] The present invention also reveals the apparatus, as well as its method of assembly, for evaluating hydrogen chloride as a function of temperature.

[0038] The apparatus consists of the following components: [0039] (1) modified three-way round-bottom flask; [0040] (2) universal support; [0041] (3) lifting platform (jack type); [0042] (4) tube with gas disperser at the end, made of sintered glass; [0043] (5) stirring rod and propeller, made entirely of glass; [0044] (6) stirring rod guide; [0045] (7) gas-conducting tube; [0046] (8) connectors; [0047] (9) nitrile rubber retainers; [0048] (10) silicone hose; [0049] (11) small hose with gas-dispersing tube, made of sintered glass; [0050] (12) 25-mL capacity beaker; [0051] (13) 250-mL beaker for potentiometric titrator; [0052] (14) oil with a high initial boiling point (paraffin oil); [0053] (15) Glas-Col heating mantle; [0054] (16) mantle temperature controller; [0055] (17) Type K thermocouples (Cromel-Alumel); [0056] (18) heating tapes; [0057] (19) heating ribbon temperature controller; [0058] (20) stirring motor (IKA RW 20); [0059] (21) flow controller; [0060] (22) potentiometric titrator (Metrohm 809 Titrando); [0061] (23) small adapted separation funnel; [0062] (24) sensor (electrode); [0063] (25) nitrogen supply.

[0064] The method of assembling the apparatus is described below: [0065] a) support the flask (1) with oil (14) on top of the heating mantle (15) and secure it by the larger mouth to a universal support set-mufa-claw (2); [0066] b) lay the heating mantle (15) on an elevating platform (3), to adjust the height of the system; [0067] c) insert the stirring rod (5) into the PEEK connection (8) provided with retainers (9), which connect to the central mouth of the flask (1); [0068] d) use silicone grease to facilitate the passage of the rod (5) through the retainers (9); [0069] e) connect the rod (5) to the stirring motor (20); [0070] f) carefully place this assembly into the larger mouth of the flask (1) and attach it to the stirring motor (20), always checking system alignment; [0071] g) connect the tube with gas disperser (4) to one side of the flask (1); [0072] h) fit a hose (10) to the upper end of this tube through which the inert gas (nitrogen) from the flow controller (21) will pass; [0073] i) use two heating tapes (18), one for the upper part of the flask (1) and the other for the gas-conducting tube (7), electrically connected; [0074] j) wrap one of the heating tapes (18) in the conductive tube, including the separation section in the middle of the tube (7); [0075] k) wrap the thermocouple (17) and leave its end as close as possible to the separating funnel. Thus, the tube set (7)+thermocouple (17) will be wrapped in the heating tape; [0076] l) attach the conductive tube (7) to the other side of the flask (1) with the help of PEEK connectors (8); [0077] m) wrap the second heating tape (18) on the upper part of the three-necked flask (1), in particular around the necks; [0078] n) electrically connect the two heating tapes (18) to two of the tapes' temperature-controlling wires (19); [0079] o) at the other end of the conducting tube (7), attach a small PTFE hose with a second gas-dispersing tube (made of sintered glass) (11); [0080] p) place the immersed sintered glass (4) in a 250-ml beaker (13) with a predetermined amount of deionized water (190 ml), in which the set is supported on the titrator's magnetic stirring base (22); [0081] q) connect a second thermocouple (17) to the respective inlet of the flask (1), dipping its end into the paraffin oil (14) and away from the stirring propeller (5).

[0082] The method for acquiring HCl evolution data comprises the following steps: [0083] a) weigh the pre-determined mass of paraffin oil (14) in the three-way flask (1); [0084] b) weigh pre-determined masses of chloride salts and dissolve them in water; [0085] c) weigh the solution to be added to the flask; [0086] d) reconnect the disconnected in order to add the sample; [0087] e) activate flow controller (21); [0088] f) activate the agitation motor (20); [0089] g) activate the heating controller of the gas-conducting tube (19); [0090] h) start the heating program on the controller (17) of the mantle (15); [0091] i) initiate burette control; [0092] j) start data acquisition in the potentiometric titrator (22).

EXAMPLES

[0093] The following tests were carried out for this study, which are examples of embodiments of the present invention.

Example 1: 4-nitro-anilinium Chloride

[0094] 117.2 mg of 4-nitro-anilinium chloride were added to 1,095 kg of chloride-free vacuum-hydrogenated gasoil (paraffin oil) contained in a three-way flask, which was heated according to the following temperature curve:

[0095] i. 35° C., for 2 minutes;

[0096] ii. 35° C. to 120° C., in 72 minutes;

[0097] iii. 120° C., for 180 minutes (isothermal).

[0098] Along the entire heating curve, N.sub.2 was bubbled into the paraffin oil at a flow rate of 180 mL/min. The gas flow was conducted to a flask containing 190 mL of water, whose electrochemical potential was adjusted to 20 mV. At each displacement of the initial electrochemical potential, resulting from the introduction of HCl into the flask, an AgNO.sub.3 solution with a concentration of 0.1 mol/L was added by an automatic titrator until the return to the initially adjusted electrochemical potential.

[0099] Finally, the titrant consumption curve, and consequently the evolution of HCl over the temperature program, are obtained. As can be seen in FIG. 5, the percentage of chloride evolution in relation to the mass of 4-nitro-anilinium chloride added to the paraffin oil, was 83%.

Example 2: Mixture of Alkali Metal Chlorides

[0100] 76.6 mg of sodium chloride (NaCl), 37.1 mg of calcium chloride dihydrate (CaCl.sub.2.2H.sub.2O) and 24.6 mg of magnesium chloride hexahydrate (MgCl.sub.2.6H.sub.2O) were diluted in 5 mL of deionized water. This solution was transferred to a round-bottom flask containing 900 g of synthetic lubricating oil (paraffin oil).

[0101] The following temperature program was used: [0102] i. 35° C., for 2 minutes; [0103] ii. 35° C. to 100° C., in 30 minutes; [0104] iii. 100° C. to 150° C., in 60 minutes; [0105] iv. 150° C. to 330° C., in 150 minutes; [0106] v. 330° C. for 240 minutes (isothermal).

[0107] Along the entire heating curve, N.sub.2 was bubbled into the paraffin oil at a flow rate of 180 mL/min. Because an aqueous solution was added to the paraffin oil in this example, and not a pure substance, the line that leads the flow of N.sub.2 containing HCl to the flask where the titration occurs was kept at 150° C. to prevent water condensation. The electrochemical potential of the water where HCl is absorbed and titrated with AgNO.sub.3 with a concentration of 0.01 mol/L was adjusted to 29.8 mV. With each displacement of the initial electrochemical potential resulting from introduction of HCl into the flask, titrant is added by an automatic titrator until the return to the initial electrochemical potential.

[0108] Finally, the titrant consumption curve is obtained, and consequently the evolution of HCl over the temperature program. As shown in FIG. 6, the chloride evolution percentage in relation to the total mass of chloride added to the paraffin oil was 3.6%.

Example 3: Industrial Saline Solution

[0109] 5 ml of industrial saline solution was added to the same paraffin oil in Example 2, containing 120 mg/L sodium, 26 mg/L calcium, 5.5 mg/L magnesium, 610 mg/L chloride and 129 mg/L nitrogen. The same temperature program as that used with the paraffin oil and the transfer line to the titration flask was used. HCl evolution intensified from 110° C. and at the end reached 11%, as seen in FIG. 7.

[0110] Note that although the present invention has been described in relation to the attached drawings, it may undergo modifications and adaptations by technicians versed in the subject, depending on the specific situation, but as long as it is within the inventive scope defined herein.