JPH055874B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION The present invention is useful in the treatment of crude oil or various fractions of crude oil, and in the treatment of products and fractions recovered from various processes that modify the production of petroleum products made from crude oil. The present invention relates to an antifouling agent for preventing fouling in a device having a heat conduction portion, that is, for reducing fouling that deposits and accumulates on the inner surface of a heat transfer device, and a fouling preventing method using the same. More specifically, the present invention relates to an additive composition and a method for preventing dirt from forming inside a shell-and-tube type crude oil preheating heat exchanger in a crude oil atmospheric distillation process. BACKGROUND OF THE INVENTION The petroleum refining industry uses numerous heat exchangers to heat and cool process streams in various processing steps. For example, in an atmospheric distillation process, crude oil is preheated through a number of heat exchangers before reaching the furnace inlet. In shell and tube heat exchangers, atmospheric distillation residual oil is used on the heating side (shell side). That is, the atmospheric distillation residual oil, which is a heating source, is cooled, and the crude oil passing through the tube is heated. In such processing steps, deposits or dirt that settles and accumulates on the inner surface of the heat exchanger becomes a problem. This fouling material causes serious problems in terms of reduced heat transfer efficiency, increased pressure drop, and loss of oil flow. If such a problem occurs, the operation of the equipment must be stopped and the dirt deposits must be removed periodically, but it is economically disadvantageous to perform this cleaning work frequently. It is. In order to prevent the adhesion of fouling substances, many methods have been proposed in the past for adding chemicals to the feedstock. Examples of such agents include amide condensation products of monocarboxylic acids and alkylene polyamines (Japanese Patent Publication No. 46-23504), ammonia (Japanese Patent Publication No. 54-69106), polyalkylene amines (Japanese Patent Publication No. 54-129490). ), polyoxyalkylene carbamate (Japanese Unexamined Patent Publication No. 59-232170), and the like are known. However, although it is possible to prevent the adhesion of dirt to some extent by adding these compounds to raw materials such as crude oil, it is still not sufficient. [Problems to be Solved by the Invention] Therefore, the present invention provides a high-performance additive composition and a method for preventing fouling of liquid hydrocarbon heat exchangers and various processing equipment in petroleum refining processes. The purpose is to provide More specifically, it is an object of the present invention to provide a high-performance additive composition and a method for preventing dirt from adhering to the inner surface of a crude oil preheating heat exchanger during an atmospheric distillation process. [Means for Solving the Problems] In view of the above-mentioned circumstances, the inventor of the present invention conducted intensive research on the analysis of dirt substances and the dirt adhesion mechanism, and as a result, discovered a dirt-preventing additive that met the above purpose, and developed the present invention. Completed the invention. That is, the present invention is obtained by graft polymerizing the following components (A) and (B), (A) an alkyl or alkenyl succinimide whose hydrocarbon group has a molecular weight of 300 to 5,000, and (B) a polar monomer. Provided is an antifouling agent for a liquid hydrocarbon heat exchanger, characterized in that it contains a polyalkyl methacrylate having a weight average molecular weight of 50,000 to 500,000 in a weight ratio of 1:9 to 9:1, and a antifouling method using the same. It is something to do. The alkyl or alkenyl succinimide as component (A) of the antifouling agent of the present invention is obtained by a condensation reaction between an alkyl or alkenyl substituted succinic acid or its anhydride and a polyalkylene polyamine having 2 to 6 nitrogen atoms. . The molecular weight of the hydrocarbon group moiety of the alkyl- or alkenyl-substituted succinic acid is preferably 300 to 5,000, particularly preferably 600 to 3,000. If the molecular weight is too large or too small, the alkyl or alkenyl succinimide will have poor oil solubility.
It is not preferable because it cannot exhibit sufficient dispersibility in oil. Examples of polyalkylene polyamines having 2 to 6 nitrogen atoms include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, N-octadecylpropylenediamine, N-
Examples include oleylpropylene diamine, N-octadecyldipropylenetriamine, and N-oleyltripropylenetetramine. In addition, the polyalkyl methacrylate of component (B) is produced by graft copolymerizing an alkyl methacrylate monomer obtained by reacting an aliphatic monohydric alcohol having 10 to 18 carbon atoms with methacrylic acid and a polar monomer. . Preferred polar monomers include vinylpyrrolidone, vinylpyridine, diethylaminoethyl methacrylate, and the like, with vinylpyrrolidone being particularly preferred. The proportion of polar monomer in the polyalkyl methacrylate is preferably 1 to 10% by weight, particularly 3% by weight.
~7% by weight is preferred. If the proportion of the polar monomer is too high or too low, sufficient dispersibility in oil cannot be exhibited, which is undesirable. In addition, the weight average molecular weight of this polyalkyl methacrylate is 50,000~
500,000, particularly preferably 150,000 to 300,000. If the average molecular weight is too small, the dispersion performance will be poor due to steric hindrance effect, and if it is too large, the viscosity will be high and the oil solubility will be poor, which is not preferable. The mixing ratio of component (A) and component (B) varies depending on the type of crude oil or petroleum product to be treated, but a weight ratio of 1:9 to 9:1, particularly 3:7 to 7:3, is preferable. To prevent fouling using the antifouling agent of the present invention, for example, the antifouling agent may be dissolved in an organic solvent to a manageable viscosity and continuously injected into a hydrocarbon stream at a rate of 5 to 200 PPM. is preferred. If the additive concentration is too low, the antifouling effect will not be exhibited, and if the additive concentration is too high, the decomposition products of the additive will have an adverse effect and cause economical disadvantages, so addition of 10 to 50 PPM is particularly preferred.
Taking the crude oil atmospheric distillation process as an example, the addition location can be either the crude oil side or the residual oil side, but when adding to the crude oil side, it is preferable to inject it at the outlet of the desalting tank.
When it is added to the residual oil side, it is preferably injected into the suction side of the residual oil outlet pump of the distillation column. [Function] The combination of components (A) and (B) in the present invention prevents fouling due to the combined effect of dispersing fouling substances, preventing agglomeration due to changes in surface conditions, and protecting the inner surface of the heat exchanger. It is believed that this will be achieved. [Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. Example 1 Antifouling performance testing of antifouling agents was conducted using an Alcoa test apparatus. The principle of this test is as follows. Test oil is fed at a constant flow rate into a tube containing a test tube that is electrically heated to a constant inlet temperature, and sufficient heat is supplied to the test tube to maintain a constant outlet temperature. When dirt is deposited on the test tube, thermal conductivity deteriorates, and the temperature of the test tube must be increased in order to maintain a constant outlet temperature of the test oil. The temperature of the initial test tube and the temperature change until the end of the test,
and measure the weight change of the test tube before and after the test. This temperature rise (ΔT) and the amount of precipitate on the test tube indicate the degree of contamination. The test time was 7 hours. The test oil used was a mixture of Middle Eastern heavy crude oil and Middle Eastern heavy atmospheric residual oil at a weight ratio of 1:1. The antifouling agents used in the tests of Examples and Comparative Examples are as follows. Additive A: Alkenylsuccinimide (molecular weight of hydrocarbon group moiety: 1500) Additive B: Polyalkyl methacrylate (contains 6% by weight of vinylpyrrolidone) Additive C: Condensation amide product of monocarboxylic acid and polyalkylene polyamine. Additive D: Commercial product (polyalkyl methacrylate type) Table 1 shows antifouling agents, mixing ratios, amounts added,
The temperature increase (ΔT) of the test tube and the weight increase due to dirt adhesion are shown. The results show that the antifouling agent of the present invention had excellent antifouling performance, with a small increase in temperature of the test tube and a small increase in weight due to adhesion of dirt when added in a low amount.

[Table] Example 2 Antifouling agent shown in Example 1 (A/B in Table 1)
= 5/5) was constantly added at 25 PPM to the atmospheric distillation residue stream of the crude oil atmospheric distillation apparatus for 4 months, and the heat exchanger outlet temperature of the crude oil passing through the heat exchanger was measured. Table 2 shows the results of comparing the same crude oil after 4 months of oil circulation. The addition of the antifouling agent increased the heat exchange efficiency of the heat exchanger, and the crude oil heat exchanger outlet temperature was 1.2°C higher than when no antifouling agent was added. This improved the tendency for the crude oil heat exchanger outlet temperature to decrease by approximately 15%.

〔Effect of the invention〕

According to the present invention, it is possible to significantly reduce the amount of deposits deposited and deposited on the inner surface of a heat exchanger in various processing steps in the petroleum refining industry. In particular, when used in the atmospheric distillation process, the adhesion of dirt to the crude oil preheating heat exchanger is significantly reduced, making it possible to reduce the frequency of removal work of dirt and adhesion, and preventing a drop in temperature at the inlet of the heating furnace. , fuel consumption can be significantly reduced. Heavy oil refined by adding the antifouling agent of the present invention can also reduce fouling of heat exchangers and pipes when used in combustion equipment.

Claims (1)

[Scope of Claims] 1. A compound obtained by graft polymerizing the following components (A) and (B), (A) an alkyl or alkenyl succinimide whose hydrocarbon group has a molecular weight of 300 to 5,000, and (B) a polar monomer. An antifouling agent for a liquid hydrocarbon heat exchanger, characterized in that it contains a polyalkyl methacrylate having a weight average molecular weight of 50,000 to 500,000 in a weight ratio of 1:9 to 9:1. 2 Alkyl or alkenyl succinimide is an alkyl or alkenyl succinimide whose hydrocarbon group has a molecular weight of 300 to 5000 and a nitrogen atom of 2
2. The antifouling agent according to claim 1, wherein the antifouling agent is obtained by a reaction with a polyalkylene polyamine having .about.6 polyalkylene polyamines. 3. Claim 1, wherein the polyalkyl methacrylate is obtained by graft polymerizing 1 to 10% by weight of vinylpyrrolidone as a polar monomer.
Antifouling agent listed. 4 When heating or cooling liquid hydrocarbon through a heat exchanger, the following components (A) and (B), (A) an alkyl or alkenyl succinimide whose hydrocarbon group has a molecular weight of 300 to 5000, ( B) A stain prevention method characterized by adding a stain prevention agent containing a polyalkyl methacrylate having a weight average molecular weight of 50,000 to 500,000 obtained by graft polymerization of a polar monomer in a weight ratio of 1:9 to 9:1. .