Process and composition for removing a scale deposit

• US 8,323,416 B2
• Filed: 07/28/2009
• Issued: 12/04/2012
• Est. Priority Date: 06/30/2008
• Status: Expired due to Fees

• Current Assignee: UOP Llc (Honeywell International Inc.)
• Original Assignee: UOP Llc (Honeywell International Inc.)
• Inventors: Bradley, Steven A., Zamechek, Walter
• Primary Examiner(s): Carrillo, Bibi
• Application Number:
  US12/510,724
• Publication Number:
  US 20090320876A1
• Time in Patent Office: 1,225 Days
• Field of Search: 134/3, 134/22.1, 134/22.11, 134/22.12, 134/22.19, 134/36, 134/40, 134/42, 510/247, 510/367, 510/372, 510/275, 510/434, 510/477, 510/480
• US Class Current: 134/3
• CPC Class Codes: C23G 1/088 solutions containing organic acids

Abstract

One exemplary embodiment can be a process for removing one or more scale deposits formed on a surface. The process can include contacting the surface with a composition for a period of time sufficient to remove the scale deposits that comprise coke or metal sulfides or mixtures thereof. Generally, the composition includes an effective amount of an organic acid and/or a salt thereof, and an effective amount of an oxidizing agent.

Claims

1. A process for removing one or more scale deposits formed on a surface, comprising the steps of:

providing a composition having a first pH of less than about 7.5 to prevent polythionic acid stress corrosion cracking to said surface, said composition comprising;

a) an effective amount of an organic acid and/or a salt thereof; and

b) an effective amount of an oxidizing agent selected from the group consisting of a peroxide, a chlorate, a perchlorate, a nitrate, or a permanganate, wherein the organic acid and/or the salt thereof and the oxidizing agent in the composition are in a weight ratio of about 2.5;

1 to about 1;

10;

providing scale deposits comprising primarily metal sulfides and coke formed on said surface, wherein said scale deposits are formed in a hydrocarbon conversion process;

contacting the surface with said composition for a period of time sufficient to remove one or more scale deposits, wherein during said contacting step, the composition has a second pH, said second pH being greater than the first pH.

2. The process according to claim 1, wherein the composition comprises the organic salt, said organic salt comprising ammonium citrate.

3. The process according to claim 1, wherein the composition comprises the organic acid, said organic acid comprising citric acid.

4. The process according to claim 1, wherein the oxidizing agent comprises hydrogen peroxide.

5. The process according to claim 1, wherein the surface is a hydrocarbon processing apparatus.

6. The process according to claim 1, wherein the metal sulfide scale deposits comprises at least one of iron sulfide, nickel sulfide, iron-nickel sulfide, iron-chromium sulfide or chromium sulfide.

7. The process according to claim 1, wherein the organic acid and/or the salt thereof and the oxidizing agent in the composition are in a weight ratio of about 2.5:

1 to about 1;

5.

8. The process according to claim 1, wherein the organic acid and/or the salt thereof and the oxidizing agent in the composition are in a weight ratio of about 2.5:

1 to about 1;

2.5.

9. The process according to claim 1, wherein the surface is contacted with the composition for at least about 30 minutes.

10. The process according to claim 1, wherein the surface is contacted with the composition at a temperature of about 30°

to about 80°

C.

11. The process according to claim 1, further comprising removing the composition from the surface and recontacting the surface with a fresh batch of the composition.

12. The process according to claim 5, wherein the hydrocarbon processing apparatus comprises a heat exchanger.

13. The process according to claim 12, wherein the heat exchanger comprises a tube and shell wherein the surface comprises an exterior of one or more tubes in the heat exchanger.

14. The process according to claim 13, wherein one or more tubes of the heat exchanger comprises stainless steel.