US3910997A - Process for cleaning slurry coolers - Google Patents
Process for cleaning slurry coolers Download PDFInfo
- Publication number
- US3910997A US3910997A US167028A US16702871A US3910997A US 3910997 A US3910997 A US 3910997A US 167028 A US167028 A US 167028A US 16702871 A US16702871 A US 16702871A US 3910997 A US3910997 A US 3910997A
- Authority
- US
- United States
- Prior art keywords
- heat exchanger
- slurry
- temperature
- deposits
- reaction
- 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 - Lifetime
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28G—CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS
- F28G9/00—Cleaning by flushing or washing, e.g. with chemical solvents
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
- C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
- C07C51/255—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting
- C07C51/265—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting having alkyl side chains which are oxidised to carboxyl groups
Definitions
- reaction temperature of certain exothermic reactions is ordinarily accomplished by cooling the reactants and the reaction product at a rate necessary to maintain the desired temperatures.
- the reaction product is the form of a slurry such as in the manufacture of isophthalic acid by the air oxidation of metaxylene in a catalyst in solvent system such as cobalt in acetic acid, and one cooling means is a conventional shell and tube heat exchanger, the cooling results in a supersaturated solution of reaction product in solvent which is passing through the tubes of the heat exchanger. While it is possible with such a system to minimize the temperature driving force or degree of supersaturation, some amount of plating or deposition of the product on the inside of the heat exchanger tubing is unavoidable.
- An exothermic reaction system such as described above must be controlled as to temperature by continuous cooling.
- the process of this invention is applicable in systems using any conventional type heat exchanger, for example, shell and tube or double pipe coolers.
- cooling fluid may be air, water or any other fluid normally used for cooling.
- water is the cooling fluid and is flowed through the shell at a rate depending upon the water temperature and the amount of cooling necessary to maintain the reactants at the desired temperature.
- the reaction system is a slurry of isophthalic acid solids suspended in a solution of isophthalic acid and m-xylene in acetic acid solvent.
- the reaction system is introduced in the tube inlet and is withdrawn from the tube outlet at a lower temperature. It is preferred to introduce the reactants in the tube section rather than the shell section to avoid shell dead space where solids may collect.
- plating occurs over the passage of time on the side of the tube in contact with the reaction system. The reason for the plating is thought to be due to the change in solubility of the reaction product in the solvent at different temperatures. That is to say as the temperature of the hot reaction system is lowered in the heat exchanger the solution becomes supersaturated Furthermore, the heat of crystallization being removed at the surface causes a tight adherence of the crystal to the metal surface. The resultant plating of precipitated product on the cold tube walls reduces the heat transfer capacity of the heat exchanger and leads to physical plugging of the flow spaces.
- the flow of cooling fluid is stopped and a warm or hot fluid is substituted.
- the hot fluid is preferably steam but may alternatively be any hot fluid such as hot water or hot air or hot oil.
- the flow of process fluid through the exchanger may either be temporarily halted or continued during the periodic deplating process.
- the periodic reversal of the temperature gradient causes localized increase in the solubility of the plated material and flaking from the surface due to a combination of factors such as mechanical stresses due to different coefficients of expansions between the metal surface and plated material, solubility increase at higher temperature at the interface, and mechanical shearing due to normal slurry flow.
- This invention does not operate by melting of the plated material; for example, even though the melting point of isophthalic acid is about 600F. low pressure steam can be used effectively to remove deposits of isophthalic acid in accordance with the process of this invention.
- EXAMPLE I A heat exchanger used to control the temperature of a reaction system wherein metaxylene is oxidized in acetic acid solvent to isophthalic acid using cobalt catalyst in solution and a heat transfer coefficient of about 260 BTU/ft. -hour-F. at the beginning of a production run. Cooling water was run through the shell of the heat exchanger at a rate necessary to control the exothermic reaction at a temperature of about 225 F. The process fluid run through the tubes of the exchanger was a slurry having an average of about 19 weight percent solids. After a run of about days the heat transfer coefficient was down to 50 BTU/ft. -hour-F. due to isophthalic acid plating on the inside of the tubes.
- This example demonstrated successful removal of plating deposits on heat exchanger surfaces in contact with a slurry of oxidation product.
- the concepts of this invention are applicable to any system having a heat exchanger subject to plating type clogging and is thought to include any reaction system wherein product continuously crystallizes from a solution causing a slurry.
- the invention is especially applicable to systems wherein an exothermic reaction must be controlled by continuous cooling, and a high melting point reaction product is caused to precipitate.
- classes of reactions are oxidation or organic compounds to acids.
- Exemplary organic acids are isophthalic acid, terephthalic acid, orthophthalic acid, salicylic acid, and other acids having a high melting point and produced by processes involving slurry in reactors.
- An improved process of controlling the temperature of a circulating slurry of reaction system in the exothermic oxidation reaction of metaxylene to isophthalic acid in the presence of acetic acid as solvent and a soluble catalyst comprising: cooling the reaction product in a heat exchanger so as to maintain a reaction temperature of from about 200F. to 275F. by circulating cooling water in said heat exchanger; and
Abstract
Description
Claims (4)
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US167028A US3910997A (en) | 1971-07-28 | 1971-07-28 | Process for cleaning slurry coolers |
CA145,800A CA948624A (en) | 1971-07-28 | 1972-06-27 | Process for cleaning slurry coolers |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US167028A US3910997A (en) | 1971-07-28 | 1971-07-28 | Process for cleaning slurry coolers |
Publications (1)
Publication Number | Publication Date |
---|---|
US3910997A true US3910997A (en) | 1975-10-07 |
Family
ID=22605655
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US167028A Expired - Lifetime US3910997A (en) | 1971-07-28 | 1971-07-28 | Process for cleaning slurry coolers |
Country Status (2)
Country | Link |
---|---|
US (1) | US3910997A (en) |
CA (1) | CA948624A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4515641A (en) * | 1982-06-28 | 1985-05-07 | Akzona Incorporated | Cleaning control through measurement of electrical conductivity |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3004397A (en) * | 1958-04-17 | 1961-10-17 | Union Carbide Corp | Method and apparatus for dehydration |
US3305320A (en) * | 1963-07-22 | 1967-02-21 | Phillips Petroleum Co | Purification of aluminum nitrate by alternate melting and crystallization |
-
1971
- 1971-07-28 US US167028A patent/US3910997A/en not_active Expired - Lifetime
-
1972
- 1972-06-27 CA CA145,800A patent/CA948624A/en not_active Expired
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3004397A (en) * | 1958-04-17 | 1961-10-17 | Union Carbide Corp | Method and apparatus for dehydration |
US3305320A (en) * | 1963-07-22 | 1967-02-21 | Phillips Petroleum Co | Purification of aluminum nitrate by alternate melting and crystallization |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4515641A (en) * | 1982-06-28 | 1985-05-07 | Akzona Incorporated | Cleaning control through measurement of electrical conductivity |
US4586523A (en) * | 1982-06-28 | 1986-05-06 | Akzona Incorporated | Cleaning control through measurement of electrical conductivity |
Also Published As
Publication number | Publication date |
---|---|
CA948624A (en) | 1974-06-04 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: ATLANTIC RICHFIELD COMPANY Free format text: MERGER AND CHANGE OF NAME;ASSIGNORS:ATLANTIC RICHFIELD COMPANY (MERGED INTO);ATLANTIC RICHFIELD DELAWARE CORPORATION (CHANGED TO);REEL/FRAME:004911/0380 Effective date: 19850314 Owner name: ARCO CHEMICAL COMPANY, 1500 MARKET STREET, PHILADE Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:ATLANTIC RICHFIELD COMPANY;REEL/FRAME:004911/0448 Effective date: 19870831 Owner name: ARCO CHEMICAL COMPANY,PENNSYLVANIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ATLANTIC RICHFIELD COMPANY;REEL/FRAME:004911/0448 Effective date: 19870831 |
|
AS | Assignment |
Owner name: ARCO CHEMICAL TECHNOLOGY, INC., A CORP. OF DE, DEL Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:ARCO CHEMICAL COMPANY;REEL/FRAME:005010/0113 Effective date: 19880831 |
|
AS | Assignment |
Owner name: ARCO CHEMICAL TECHNOLOGY, L.P. A PARTNERSHIP OF Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:ARCO CHEMICAL TECHNOLOGY, INC.;REEL/FRAME:005970/0340 Effective date: 19911220 |