JPS58147493A - Antifoulant for thermal decomposition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cracking tube in a furnace used for pyrolysis of a gas stream containing hydrocarbons.
ng tube) and in any heat exchanger used for cooling the effluent stream from the furnace; It relates to a method of reducing the velocity by the use of special antifoulants that are effective in reducing the velocity.

Cr'aCking furnace
forms the heart of many chemical manufacturing processes. In fact, it can be said that the performance of this cracking furnace is responsible for the huge profits of the entire manufacturing process. Therefore, it is extremely desirable to maximize the performance of the cracking furnace.

In manufacturing processes such as ethylene production, feed gases such as ethane and/or FO pan and/or naphtha are fed into a cracking furnace. A diluent fluid, such as steam, is typically combined with the feed material being fed to the cracking furnace. In the furnace, the feed stream combined with the diluent fluid is converted to a gas mixture containing primarily hydrogen, methane, carbon dioxide, propylene, putazoene, and the heavier gases of violet. . At the outlet of the furnace,
This mixture is cooled, removing most of the heavier gases, and compressed.

This compressed mixture is conducted to a valley distillation column where the individual components, such as ethylene, are distilled off and then separated 17. The separated product, of which ethylamine is the major product, then goes to ethylene norant where it is further used in a number of other steps for the production of a wide range of secondary products.

The primary capacity of the cracking furnace is to convert the feed stream to ethylene and/or globylene.

[Semi-pure (se) called coke]
It is formed as a result of the decomposition operation of carbon or decomposition. Coke is also formed in the heat exchanger used to cool the gas mixture flowing from the cracking furnace. The formation of coke is generally a homogeneous thermal reaction in the gas phase (thermal coking).
Catalytic coking) and heterogeneous catalytic reactions between hydrocarbons in the gas phase and metals in the walls of cracking tubes or heat exchangers.
g) ] is generated as a result of the combination.

Coke is generally said to form on the metal surfaces of the cracking tubes that are in contact with the feed stream and on the metal surfaces of the heat exchangers that are in contact with the gaseous effluent from the cracking furnace. However, it should be recognized that coke will also form on the metal surfaces of the connecting conduits and ponds that are still exposed to hydrocarbons at elevated temperatures. Therefore, [Metal
s)] hereinafter refers to all metal surfaces that are exposed to hydrocarbons during the cracking process and that give rise to coke deposition.

The normal mode of operation of a cracking furnace is to periodically shut down the furnace to burn-out the stratified coke. This downtime results in substantial production losses.

Additionally, coke is an excellent thermal insulator. Therefore, as the coke builds up, further furnace temperatures are required to maintain the gas temperature in the cracking zone at the desired level. Such a relatively soft temperature will increase fuel consumption,
At the same time, the length of the tube left is shortened.

Other issues related to carbon formation are
osion), which arises in two ways.

First, it is well known that in catalytic coke formation, all of the catalyst particles are removed or expelled from their surface and into the coke. This phenomenon results in a very sudden loss of the entire area, and eventually becomes a metal illusion. A second mode of erosion is caused by urea particles moving from the tube wall and into the gas stream. The J[% action of these particles is the return bend in the detube (' r
It is particularly severe in etern bends.

However, another and more subtle aspect of coke formation is that the coke enters the furnace tube alloy in the form of a solid bath. This carbon then reacts with the chromium in the base metal to precipitate chromium carbide. 4 charcoal (Carb
This dust phenomenon, known as oxidation, causes the alloy to lose its inherent oxidation resistance and therefore becomes susceptible to chemical infiltration. The tragic nature of the tube also received a lot of criticism.

4 carbon also occurs with respect to iron and nickel in the base metal. Based on the present invention, an antifouling agent selected from a combination of tin, tin and antimony, a combination of I'rumanium and antimony, a combination of tin and germanium, and a combination of tin, antimony and germanium is used to remove the metal. The metal is pretreated with an antifouling agent and brought into contact with the metal by either or both adding the antifouling agent to the hydrocarbon feed stock entering the cracking furnace. The use of this antifouling agent substantially reduces the formation of coke on the metal, and the negative effects associated with coke formation on the metal are substantially reduced.

The present invention describes a cracking furnace used in a process for ethylene production. However, the invention described herein provides that the cracking furnace is used to crack the feed material into certain complementary desired components, and that the cracking furnace is used to crack the feed material into certain complementary desired components, and that the cracking tube of the cracking furnace or other metal surface associated with the cracking process Other methods in which coke is formed are also widely applicable.

In the antifouling agent with a combination of germanium and antimony, the antifouling agent with a combination of tin and germanium and tin,
Any suitable germanium can be used in the combination antimony and germanium antifouling agent. Preferred uses of the element germanium include inorganic and organic compounds, as well as mixtures of any two or more of these. FHj of [germanium] refers to any of these sources of germanium.

Some of the heartless darmanium compounds that can be used include halides, nitrides, hydrides, oxides, blunts, imides, salts and phosphates.

Among heartless darmanium compounds, those containing no halogen are preferred.

Examples of organogermanium compounds that can be used include the formula 1 R, -Ge -R2 (wherein R1, R2, , R3, and R4 are frozen confectionery, halogen,
(independently selected from the group consisting of hydrocarbyl, and oxyhydrocarbyl). The hydrocarbyl and oxyhydrocarbyl groups may be substituted with halogen, nitrogen, phosphorus or 1-2
It has 0 carbon atoms. Examples of hydrocarbyl groups are alkyl, alkenyl, cycloalkyl, aryl groups and combinations of the above, such as alkylaryl or alkydichloroalkyl groups. Germanium compounds such as tetrabutylgermanium, germanium tetraethoxide, tetraphenylgermanium, germanium tetraphenoxide and zophenylzopromodelmanium can be used. As for Ir, dermanium tetraethoxide is preferred.

Any suitable antimony can be used in combination antifouling agents of tin and antimony, combination antifouling agents of germanium and antimony, or combination antifouling agents of tin, antimony and germanium; 60 elemental antimony, inorganic antimony compounds and organic Antimony compounds as well as any mixtures of two or more thereof are suitable sources of antimony. The term "antimony" generally refers to any one of these sources of antimony.

Examples of some inorganic antimony compounds that can be used include:
Antimony oxides, antimony trisulfide, and blunted antimony such as antimony trioxide, antimony tetroxide and antimony pentoxide, antimony phosphates such as antimony trisulfate, metaantimonic acid, orthoantimonic acid and Antimonic acids like pyroantimonic acid, antimony trifluoride, antimony trichloride, antimony tribromide, antimony halides like antimony Misawa, antimony pentafluoride and antimony pentachloride, antimony chloride and antimony trichloride. Contains antimony halides. Among inorganic antimony compounds, halogen-free compounds are preferred.

Examples of some organic antimony compounds that can be used include:
Antimony carboxylates, such as antimony triformate, antimony trioctoate, antimony triacetate, antimony trioctoate, antimony trioctadecanoate, antimony tribenzoate, and antimony tris (cyclohexene carboxylate), antimony tris (thioacetate) ), antimony thiocarmenates such as antimony tris (dithioacetate) and antimony tris (dithiopentanoate), antimony thiocarbonates such as antimony tris (O-nolopyrdithiocarbonate), antimony tris (ethyl carza antimony carbonates such as triphenyl antimony (- antimony salts of thiophenolic compounds such as thiophenoxide), tenthimontris (benzene sulfonate)
and antimontris (p-toluenesulfonate)
Antimony sulfonates, such as antimony tris (
antimony carbamates such as diethyl carbamate), antimony tris (zozolobyl zothiocarpamate), antimony tris (-phenyldithiocarbamate) and antimony tris (butyl thiocarbamate)
antimony thiocarbamates such as antimony tris (-diphenyl phosphite), antimony phosphites such as antimony tris (dipropyl) phosphate, antimony tris (0,o-zozolovir thiophosphate) antimony phosphites such as antimony tris (dipropyl) phosphate, antimony thiophosphates such as 0,0-zopropyldithiophosphate), and the like. Antimony 2-ethylhexanoate is currently preferred.

Tin in any suitable form can be used as the tin antifouling agent in a combination antifouling agent of tin and antimony; .

Elemental tin, inorganic and organic tin compounds, as well as mixtures of two or more of these, are suitable sources of tin. Tin candy generally refers to any one of these sources of tin.

Examples of inorganic tin compounds that can be used include tin oxides such as stannous oxide and stannic oxide, tin sulfides such as stannous sulfide and stannic sulfide, stannous sulfate and stannic sulfate. stannous acids such as tin sulfate, metastannic acid and thiostannic acid, stannous fluoride, stannous chloride,
Tin halides such as stannous bromide, stannous iodide, stannic fluoride, stannic chloride, stannic bromide, and stannic iodide; tin sulfate such as stannous phosphate; , tin oxyhalides such as stannous oxychloride and stannic oxychloride. Among inorganic tin compounds, those containing no halogen are preferred as the tin source.

Examples of organotin compounds that can be used include stannous formate, stannous vinegar, stannous rough acid, and octane.
tin, stannous decanoate, stannous tin, stannous benzoate, and stannous carboxylates such as cyclohexanecarboxylic stannous, thiocarmenes such as stannous thioacetate, stannous dithioacetate. Dihydrocarpylstin, bis(hydrolybilmerzotoalkanoates), 〇-ethylzothiocarzanes, such as dibutyltin, dibutyltinbis(inoctylmercaptoacetate) and dizolobyltinbis(butylmercaptoacetate). tin thiocarboxylic acids such as stannous acids, tin acids such as propyl stannous carbonate, tetrahydrocarpylstannic acids such as tetrabutyltin, tetraoctyltin, tetradodecyltin and tetraphenyltin, zoproviltin Dihydrocarpylstin oxides such as dibutyltin oxide, dioctyltin oxide, diphenyltin oxide P, dihydrocarpylstin oxides such as dibutyltin bis(dodecylmercaptide), bis(hydrocarbylmercaptide), stannous thiophenoxide tin salts of phenolic compounds such as stannous benzenesulfonate, stannous sulfonate such as stannous p-toluenesulfonate, stannous carbamate such as stannous diethylcarbamate, stannous propylthiocarbamate. tin, and stannous phosphates such as stannous diethyldithiocarbamate, stannous diphenyl phosphite, stannous phosphates such as zoprobyl stannous phosphate, stannous 0.0-dipropylthiophosphate, and stannous 0.0-zozolopyl dithiophosphate. tin thiophosphates, such as monotin and stannic 0,0-zozolopyrzothiophosphate, zozotyltin, bis(0,0-
dihydrocarpylstin such as zoprobyl dithiophosphate), bis(0°, 0-dihydrocarbyl thiophosphate), and the like. Currently preferred is stannous 2-ethylhexanoate.

Any of the above tin sources can be used in combination with any of the above antimony and r-rumanium sources to form a tin and r-rumanium combination antifouling agent, a tin and antimony combination antifouling agent, or a tin, antimony, and r-rumanium combination antifouling agent. A staining agent can be formed.

Similarly, any germanium source described above and any antimony source described above can be used in combination to form a germanium and antimony combination antifouling agent.

In combination tin and antimony antifouling agents, any reasonable concentration of antimony can be used. Antimony concentrations within the range of about 10 mole percent to about 75 mole percent are presently preferred, as outside this range the effectiveness of the tin and antimony combination antifouling agent is reduced. Similarly,
Any suitable antimony concentration can be used in the germanium and antimony combination antifouling agent. Approximately 10 mol%
Antimony concentrations within the range of about 75 mole percent are presently preferred, since outside this range the effectiveness of the combination of germanium and antimony is reduced.

Any suitable concentration can be used in the combination antifouling agent of tin and germanium. About 10 mol% to about 75 mol%
Germanium concentrations within the range of are currently preferred,
This is because it is believed that outside this range, the effectiveness of tin and germanium combination antifouling agents may be reduced.

Any suitable antimony concentration can be used in combination with tin, antimony and dermanium.

Concentrations within the range of about 10 mole % to about 65 mole % are currently preferred. Similarly, germanium oxide in the range of about 10 mole % to about 65 mole % is currently preferred.

In general, the combination antifouling agents of the present invention are effective in reducing coke deposition on any temperate steel. Tin antifouling agents are believed to be effective in reducing coke build-up on any tempered steel other than steel having an iron content of about 98 wt % or greater.

A commonly used steel for cranking tubes is Incoloy 8001 Incone. The composition of these steels by weight l1it% is as follows.

Inconel 600 72. 5. 15
8.0 15. b Incoloy 800
32.5. 75. 10 45.6
21. L+HK-4019,0-22
, U O, 35-0, 45 remainder [J, 40 maximum 26. U-n7. Umi50 1 '7'4Cr '7'2Mc)
Residual 0.40 Maximum 0.99-1
．． 46 main 98 304ss 9.0. 08
72 19Mo P
Mn S 1O104 maximum 1.5 square size 1.75 general size 0.40-n, 65 0.035 maximum 0.36-0.6
9 0.13-0.52 The antifouling agent of the present invention is prepared by pretreating the metal with the antifouling agent or by cooling the antifouling agent into a hydrocarbon-containing agrochemical, or preferably both. It may be brought into contact with the metal by any method.

When pretreating metals, a preferred pretreatment method is to contact the metal with a bath solution of the antifouling agent. It is preferable to pour a large amount of antifouling agent into the cranking tube. The surface of the cracking tube is left in contact with the antifouling agent for any suitable period of time.

At least one minute is preferred to thoroughly treat the entire surface of the cranking tube. In commercial operations, the contact time will typically be about 10 minutes or more. However, rather than making the contact time relatively longer, it would be substantially more advantageous for the operator to make sure that the cracking tube has been treated.

If the cracking tube 131 is external metal, typically l! If it is necessary to apply with Jl or a brush, or if the armor can be poured with water, an antifouling bath solution can be poured in the winter.

Any suitable solvent can be used to prepare the antifouling bath. Suitable bath agents include water and oxygen-containing organic liquids such as alcohols, ketones and esters and aliphatic, aromatic hydrocarbons and derivatives thereof. Presently preferred solvents are n-hexane, toluene, but in commercial operations kerosene will typically be used.

The antifouling agent solution can be used at any suitable concentration. It is desirable to use a concentration of at least 0.1 molar, and concentrations of 1 molar or higher may be used if the concentration is limited by metallurgical and economic considerations. Presently preferred antifoulant solution concentrations are within the range of about 0.2 to about 0.5 molar.

If the surface of the cranking tube is accessible, antifouling solutions can be applied to the cracking tube surface by spraying or plucking, but application by this method has been found to be less effective in preventing coke formation than by dipping. ing. Cracking tubes can also be treated with finely divided antifouling powder, but this is also not considered particularly effective.

In addition to pretreating the metal with or otherwise contacting the metal with the antifouling agent, any suitable concentration of antifouling agent may be added to the feed stream flowing through the cracking chive. Good too. The antifouling agent in the feed stream has at least 10 ppm by weight of metals contained in the antifouling agent based on the weight of the hydrocarbon portion of the feed stream. The presently preferred concentration of antifoulant metal in the feed stream is from about 20 to about 100 parts by weight based on the weight of the hydrocarbon portion of the feed stream.
i ppm. Higher concentrations of antifouling agent may be added to the feed stream, but this does not substantially increase the effectiveness of the antifouling agent, and economic considerations prohibit the use of higher concentrations. Generally not done.

Antifouling agents can be added to the feed stream in any suitable manner. Preferably, the antifouling agent is added under conditions such that the antifouling agent is highly dispersed. Preferably, the antifouling agent is injected as a solution through the orifice under pressure such that the bath liquid atomizes. The solvents mentioned above may be used to produce this bath liquid. The degree of antifouling agent in solution should be such that the desired concentration of antifouling agent is obtained in the feed stream.

Steam is commonly utilized as a diluent for the hydrocarbon-containing feedstock flowing to the cracking furnace. When using the tin antifouling agent of the present invention, the steam/hydrocarbon molar ratio is
If the molar ratio of hydrocarbons exceeds 2:1, the effectiveness of the antifouling agent will be substantially reduced, so it should not exceed 2=1. Steam/Vapor preferred to promote tin antifoulant effectiveness
The hydrocarbon molar ratio is about 0.25:1 to about 0.75
: Within the range of 1.

This vapor/hydrocarbon molar ratio is approximately It is believed that there will be no impact. The tin antifouling agent is
It is believed that this steam/hydrocarbon molar ratio is important in the case of tin alone due to its volatility at high steam/hydrocarbon molar ratios. Concomitant antifouling agents are not expected to exhibit similar volatility.

The cracking furnace can be operated at any suitable temperature. In the process of steam cracking into light hydrocarbons and ethylene, the temperature of the fluid flowing through the cracking tube increases during passage through the tube and reaches a temperature of about 8
A maximum temperature of 50°C is reached. The wall temperature of the cracking tube will be higher than this and will become substantially hotter with the accumulation of an insulating layer of coke within the tube. Furnace temperatures of about 2000°C can be used. Typical pressures in the cracking process are generally about 10 to about 20 psi at the exit of the cracking tube.
It is g.

Before referring specifically to the examples used to further explain the invention, the experimental apparatus will be described with reference to FIG. 1, which shows a 9'H quartz reactor. The quartz reactor portion is located inside the electric furnace 12. Metal coupons (metal c
upon) is supported. A hydrocarbon feed stream (ethylene) is fed to reactor 11 through a combination of conduit arrangements 16 and 17. Air is supplied to reactor 11 through this combination of conduit arrangements.

Nitrogen flowing through line arrangement 21 is fed to a heated saturator 22 and via line arrangement no. 2 to reactor 11. Conduit device 28 is used for pressure averaging.

Steam is generated by saturating the nitrogen carrier gas flowing into the saturator 22. The steam/nitrogen ratio can be varied by adjusting the temperature of the electrically heated saturator.

Reaction effluent is removed from reactor 11 through conduit arrangement 31. Provisions are also made for directing the reaction effluent to a chromatograph for analysis if desired.

When measuring coke deposition on a metal coupon, the amount of carbon monoxide produced during the cracking process is assumed to be proportional to the amount of coke deposited on the metal coupon. The rationale for this method for evaluating carbon intensity is based on the assumption that carbon monoxide is produced from deposited coke by a carbon-vapor reaction. The metal coupons examined at the end of the cracking experiment had essentially no free carbon, supporting the hypothesis that the coke was vaporized by steam heat.

The selectivity for the amount of carbon monoxide in the converted ethylene was calculated based on Equation 1 (A) using nitrogen as an internal standard.
/ MoJl/% N2

(2) Conversion = mol % bow / mol % N4) Feedstock -
(Mole%C!H±1mol%N) The CO level for one sample complete cycle is the weighted average of all analytical values taken during one cycle (vreightedav
% calculated based on formula (3) as
Selectivity is directly proportional to the amount of carbon monoxide in the effluent flowing through the reactor.

Example 1 In this example IncoLOY
s o o tsuk-in 1'xl/4'xl/i,"
〇 Each Incoloy 8 before applying coaching using
00 Kuhn was thoroughly cleaned with acetone. Each stain repellent was applied to the coupon by soaking the coupon in a minimum of 4-stain repellent/solvent solution for 1 minute.

Ta. A new coupon was used for each antifouling agent. After this coating, a heat treatment was performed in air at 700° C. for 1 minute to decompose the antifouling agent into its oxide and remove residual solvent. Blank coupons used for comparison ￥＠lr 411 were prepared by washing the coupons in acetone and heating them in air at 700° C. for 1 minute without any coating. The manufacturing methods for various coatings are as follows.

Q, 5 M 8b: 2.76, i9 Sb (C
8H150,)3 was mixed with sufficiently pure n-hexane to make bath solution IQ, [1m, hereinafter referred to as bath solution A.

Q, 5MGe: 1.261 Ge (OC2Ha)
4 was thoroughly dissolved in absolute ethanol to make 10 IL of a solution, hereinafter referred to as solution B.

0.5 M 8n: 2.02 g of Sn (C8H
1502)2 was dissolved in sufficiently pure n-hexane to form a solution 10.0111, hereinafter referred to as solution C.

0.5 M 5n-8b: 0.81 g of 8n (0
A solution of 41 was prepared by dissolving 8H1502) in sufficiently pure n-hexane. 1.109 of 5b (CsHxsOa)s was dissolved in sufficiently pure n-hexane to make 41 nl of solution.

Both solutions are mixed together and the resulting solution is called solution. 0.5 M Ge-8b: 51 Ge (OC2H5
) 4 was sufficiently dissolved in absolute ethanol to make 40.0 m. 4. Next, 5b (caH1δ0 mushroom) 8 of 1.11 was dissolved in sufficiently pure n-hexane. I made ON. Each solution 4. Ojl/ were mixed together to make a 1:1 Ge-8b bath solution, hereinafter referred to as solution E.

Q, 5 M Ge-8n: ee of 1.269 (QC
,H,) was roughly translated into absolute ethanol and diluted with alcohol to make exactly 10517.

8n(CaHlsOa)s of 2.7I was dissolved in pure n-hexane and diluted with n-hexane to exactly 1[1m]. Both ** are combined and mixed, henceforth referred to as solution F.

Q, 1M 8n-8b: 2. An Oml aliquot of the bath liquid was added to a graduated cylinder and toluene was added to bring it to 1Q, Qsl. The obtained bath liquid will be referred to as bath liquid G hereinafter.

0.1 M 5n-8b-Ge 2 0.6 8
g 5n(CsHx 502)z, 0.9
2 g of 5b(CeH1sO2,) 3 and 0.42
,! i'()e(OC2H5)4 was dissolved in enough toluene to make 10.0 Inl.

2. of this bath liquid. (A Jml aliquot was added to a graduated cylinder and enough toluene was added to make it 10.07 d. The resulting bath liquid is hereafter referred to as bath liquid H.) The temperature of the quartz reactor was increased so that its highest zone The shaft was held at 5° C. The coupon was placed in the reactor while it was at reaction temperature.

A typical experiment consists of three 20-hour coking cycles (
ethylene, nitrogen and steam), a 5 minute nitrogen purge after each cycle, and a 50 minute decoking cycle (nitrogen, steam and air). During the coking cycle, 76 ml/min ethylene, 145 ml/min nitrogen and 73 mA! A gas mixture consisting of /min of steam passed through the reactor in a downward flow. Periodically, snapshots of the reactor effluent were analyzed on a chromatograph. The steam/hydrocarbon molar ratio was 1:1.

Table 1 summarizes the results of cycling experiments (either 2 or 6 cycles) conducted using Incoloy 800 coupons immersed in test solutions [A-H] as described above.

The results for M2.6 and M4, respectively, used separately for tin, antimony, and gelmanyramid show that tin alone substantially reduces the proportion of the carbon layer on Incoloy 800 under conditions simulating an ethane cracking process. was effective. However, in the three-way combination experiment using these elements in Experiments 5.6.7.8 and 9, Ikuga showed a surprising effect. Experiment 5 with tin and antimony and experiment 6 with germanium and antimony show that these combinations are unexpectedly much more effective than expected from their use alone.

Runs 8 and 9 showed an unexpected improvement in terms of the effectiveness of germanium alone over tin alone. However, the tin and germanium combination antifouling agent did not show the impressive improvement shown by the tin and antimony combination antifouling agent and the germanium and antimony combination antifouling agent. He's not very clever among people.

It is unclear why Experiment 7 was less effective than tin alone.

However, Experiments 8 and 9 can be seen as examples of the effectiveness of tin and germanium antifouling agents, and this antifouling agent appears to be more effective than tin alone.

In Experiments 10.11 and 12, a 0.1M solution was used to demonstrate the improvement obtained with the King combination. 0
．． Higher concentrations, such as 5M, tend to mask the improvement. A comparison of experiments 10.11 or 12 shows that the tin, antimony and germanium combination antifouling agent is much more effective than the best combination (8n-sb) antifouling agent.

Example 2 Using the process conditions of Example 1, multiple three cycles were performed with antifoulants containing different ratios of tin and antimony and antifoulants containing different ratios of germanium and antimony. We conducted an experiment.

Fresh Incoloy 800 coupons, previously strained and processed as described in Example 1, were used in each experiment. The antifouling agent solution was prepared as in Example 1, but the ratio of the shaving elements was varied. The results are shown in FIGS. 2 and 6.

Referring to Figure 2, the combination of tin and antimony is
It was particularly effective at antimony concentrations ranging from about 1.0 mole percent to about 75 mole percent. Outside this range, the effectiveness of the tin and antimony combination decreases especially in the second and third cycles.

Next, with reference to FIG.
It is found that it is effective within the range of about 75 mol%. Again, the effectiveness of the combination of germanium and antimony is reduced outside this range. It can also be seen that the effectiveness of the germanium and antimony combination is further reduced with each cycle than was seen with the tin and antimony combination.

It is believed that tin and germanium combination antifoulants are essentially the same as tin and antimony combination antifoulants in terms of effectiveness as a function of concentration; therefore, germanium in combination tin and germanium antifoulants is The concentration is preferably about 10 mol% to about 75 mol%.

Example 6 Transfer line heat exchanger of m+ ethylene cracker
The coupons were cleaned by the method described in Example 1 of 110μ-1 molybdenum steel alloy, an alloy commonly used in Hanger. Separate tarpon were then treated with Baths A, C and D of Example 1.

Each tarpon, including the control coupons, was then cycled under the conditions described in Example 1. The results are summarized in Table U. Due to the experimental difficulties involved in analyzing spilled dirt, we believe that the reported test results will be useful for comparison of the effectiveness of antifouling agents, although the time may vary.

No. 13.8
45.64 19.1
70.86 23.5
83.58 24.2
B6.5Sn 24 31-2
82.630 25.6
82.13<5 23.6
82.453 45.5
97.1sb 5 42.0
B6.5Sn+Sb 2
14.0 2.54 13.8
1.66 13.8
1.8B 13.9
1.812 14.5
4.116 14.6 2.
820 15.4 b, 42
3 15.6 7.8 Hayabusa The experiment continued for 21.2 hours, but due to trouble with the measuring equipment, no other analytical values could be obtained. In the second cycle, the experiment was stopped after 1.2 hours because too much carbon was deposited on the coupon and hindered the flow altogether.

Treating the 11 chromium-↓ molybdenum steel alloy with separate baths of tin or antimony was considered ineffective in reducing the adhesion side q of carbon under the conditions of these experiments; however, tin and antimony When both antimony and antimony were present, the woodblock fraction under the same conditions was substantially reduced.

Example 4 Type 304 stainless steel coupons were cleaned by the method of Example 1. One coupon was then treated with Zokuso C of Example 1. The treated and control coupons were cycled under the conditions set forth in Example 1 at: The results are summarized in Table m.

No table 23,3 74,2
85.4Sn 4.1
6.0 Table 8.1 shows that the iron content is approximately 72 tons%.
Tin has proven to be an effective antifouling agent for Tyzoro 04 stainless steel. In contrast, in Example 6, for a Rom-Molybdenum alloy from 1 with an iron content of about 98i11t%,
2 has proven to be an ineffective antifouling agent.

Therefore, although tin is an effective antifouling agent for steels with relatively high iron contents, it appears that the use of tin should be avoided on steels with iron contents of about 981 i.d.% or higher.

Example 5 A tin antifouling agent of the present invention was tested in a commercial ethylene cracking furnace. The feedstock to this cracking furnace was ethane except for a relatively short period of time when propane was used. The cranking tube is in communication with a downstream transfer line heat exchanger and a solution containing stannous octoate is pumped into the thalassoking tube until it fills the tube. I entered.

This treatment bath was prepared by diluting stannous octoate (T-9, manufactured by M&T Kagaku Kagaku Co., Ltd.) with kerosene of various awards. The compound, undiluted as reported by the manufacturer, was removed from the tartaring tube in a 0% stannous octoate bath solution, typically containing 28 wt% tin. In addition to tube treatment, this stannous octoate bath was also applied to the transfer line heat exchanger by spraying.

The cracking furnace was shut down when the inlet pressure of the packing tube exceeded a predetermined limit. In the decomposition furnace that passed the test, the tube LJ was used for 10~
It was operated for 61 days and underwent oxidation combustion treatment to remove coke and soot. Driving was 40.49 in three trials involving antifouling agents as described above.
and maintained for 47 days, which was a substantial improvement over the maximum of 61 days seen without antifoulant treatment.

In one experiment, in addition to treating the cracking furnace tubes and transfer line exchanger as described above, a stannous octoate solution was injected into the ethane before it entered the cracking furnace. The concentration of tin in the ethane is v 23
It was ppm. The antifoulant bath liquid was forced into the ethane through an orifice at elevated pressure with a stream of ethane moving at a linear velocity of about 1000 feet/second. This antifoulant injection continued for 10 of the first 11 days of operation and was then stopped.

In this experiment, the racking tube was used for 60 days until excess inlet pressure led to its shutdown. All operations in the commercial cracking furnace were carried out at a steam/ethane filtration ratio of 0.55:1 and cracking. The temperature at the tube outlet was about 846°C.

Example 6 Using the method of Example 1 and Bath C of Example 1, three separate 48s were prepared, each with a steam/hydrocarbon molar ratio of 1.
:1.2:1 and 2.5:1.

The results are shown in FIG.

Referring to Figure 4, the steam/hydrocarbon molar ratio is 1.0.
It can be seen that the tin antifouling agent has good results. However, as the steam/hydrocarbon molar ratio became simpler, the effective layer decreased.

[Brief explanation of the drawing]

FIG. 1 shows a diagram of the test iron group used in testing the antifouling agent of the present invention. FIG. 2 is a graph showing the combined effect of tin and antimony. FIG. 6 is a graph showing the combined effect of germanium and antimony. FIG. 4 is a graph showing the effect of steam on tin antifouling agents. Four agents: Akira Asamura (Continued from page 1) Priority claim @September 30, 1982 @United States (US)■
424889 0 Inventor Jacques Paul Guillory 1316 Ridgewood Drive, Nis., Puddlespil, Oklahoma, United States of America

Claims (1)

Claims: (1) A method for reducing the formation of coke on a metal plate in contact with a hydrocarbon-containing gas stream in a pyrolysis process, in which said metal is combined with a combination of tin and antimony;
Φ, characterized in that the method comprises contacting with an antifouling agent selected from a combination of r-rumanium and antimony, a combination of tin and dermanium, and a condensation of tin, antimony and r-rumanium. (21) The contact with the antifouling agent may be caused by the metal or f
2. A method according to claim 1, characterized in that it comprises contacting with the antifouling agent when not in contact with the gas stream of JII. (3) The metal is mixed with the bath liquid at least about 1
3. The method of claim 2, wherein the soil is contacted for a minute and the yield of said antifouling agent in said bath liquid is at least about 1 mole. (4) The second bath agent used to form the antifouling agent bath liquid is water, an oxygen-bearing organic compound, or an aliphatic or aromatic hydrocarbon. Or the method described in Section 3. (5) said contacting with said antifouling agent comprises cooling a suitable amount of said antifouling agent to said gaseous stream before said metal contacts said gaseous stream; The method according to any one of Items 1 to 4 above. (6) that the weight of the antifouling agent in the gas stream is at least 10 ppm of antifouling agent metal based on the weight of hydrocarbons in the gas stream; 6. The method according to item 5 above. said fifth aspect characterized in that said antifouling agent is added to said gas stream by injecting said antifouling agent bath liquid under pressure such that said bath liquid is atomized. or the method according to item 6. (8) The combination of tin and antimony and r
The degree of antimony in said combination of rumanium and antimony is within the range of about 10 to about 75 mole percent, and the degree of dermainium in said combination of tin and derma is within the range of about 10 to about 75 mole percent. The method according to any one of items 1 to 7 above, characterized in that the thickness is . (9) A method of reducing the formation of coke on a metal in contact with a gas stream containing hydrocarbons and water vapor in a pyrolysis process, wherein said metal is contacted with a tin antifouling agent, said metal being contacted with a tin antifouling agent, said A first method characterized in that the iron content of the metal is reduced to about 98 mm% or less, and the molar ratio of water vapor to hydrocarbon in said gas stream is less than about 2:1. . Concave The molar ratio of steam to hydrocarbons is approximately 0.25:1.
10. The method according to item 9, wherein the 1% mark is within the range of approximately 0.75:1. said contacting with said tin antifouling agent of Qlll Ail comprises contacting said tin antifouling agent with a bath liquid when said metal is not in contact with said gas stream; The method according to paragraph 10. 11, wherein the metal of paragraph 11 is in contact with said bath solution for at least about 1 minute, and the backing layer of said antifouling agent in said solution is at least about 0.1 molar. The method described in. No. 31 The bath agent used to form the bath liquid of the tin antifouling agent is water, an oxygen-bearing organic liquid, or an aliphatic or aromatic hydrocarbon. Or the method described in item 12.鵵 Said contact with said tin antifouling agent comprises adding a suitable amount of said tin antifouling agent to said gaseous stream before said metal contacts said gaseous stream. 17. The method according to any one of items 9 to 16 above. (151) Clause 14, wherein the weight of the antifouling agent in the gas stream is at least 10 ppm of tin based on the coulombicity of the hydrocarbon in the gas stream. (16) Under pressure such that the solution is atomized,
16. A method according to claim 14 or 15, characterized in that the tin antifouling agent is removed from the gas stream by injecting a bath of the tin antifouling agent. Q71 The method according to item 11 or 12 of M'+J, characterized in that the tin liquid of the tin antifouling agent in URL is octane "autumn tin" in kerosene. 0- Tin, antimony An antifouling agent composition characterized in that the antifouling agent composition comprises from about 10 to about 65 mole % of the antimony in the antifouling agent composition described above. The composition according to item 18 of AiJ, wherein the backing layer of dermanium in the antifouling agent composition is in the range of about 10 to about 65 mol %. (4) The antifouling agent as described above. d, wherein the composition is present as a bath solution, and the backing layer of the antifouling agent composition in the bath solution is at least about 0.1 molar.
Compositions as described. Said No. 20, characterized in that it is a bath agent, water, an oxygen-containing sentient liquid, or an aliphatic or aromatic hydrocarbon used to form a solution of the antifouling composition described in EnmlJ. Morning preparation described in section 0