METHOD FOR MANUFACTURING A PROCESS APPARATUS AND A PROCESS APPARATUS

Abstract

The invention concerns a method for manufacturing a process apparatus for moving liquid in high temperature liquid immersion under aggressive chemical environment and dynamic stress, wherein the method comprises the step of lining the process apparatus formed of stainless steel with rubber, wherein the method further comprises the step of forming a passivation layer on a surface of the process apparatus in an acid bath prior to lining the process apparatus comprising the passivation layer with rubber. The invention also concerns a process apparatus.

Claims

1-15. (canceled)

16. A method for manufacturing a process apparatus for moving liquid in high temperature liquid immersion under an aggressive chemical environment and dynamic stress, wherein the process apparatus is an impeller, agitator or mixer, and wherein the method comprises the step of lining a process apparatus formed of stainless steel with rubber, wherein the method comprises: roughening a surface of the process apparatus to a roughness of at least 10 m Rz; and forming a passivation layer on the roughened surface of the process apparatus in an acid bath prior to lining the process apparatus comprising the passivation layer with rubber.

17. The method according to claim 16, wherein a surface of the process apparatus is roughened by shot peening prior to forming the passivation layer on the roughened surface of the process apparatus.

18. The method according to claim 16, wherein a surface of the process apparatus is roughened to a roughness of at least 15 m Rz, or at least 20 m Rz, prior to forming the passivation layer on the roughened surface of the process apparatus.

19. The method according to claim 16, wherein a primer and/or an adhesive is applied on the passivation layer prior to lining the process apparatus comprising the passivation layer with rubber.

20. The method according to claim 16, wherein the acid bath is a nitric acid bath or a citric acid bath.

21. The method according to claim 16, wherein the rubber is halobutyl rubber, preferably bromobutyl rubber.

22. The method according to claim 16, wherein the stainless steel is super duplex stainless steel.

23. A process apparatus for moving liquid in high temperature liquid immersion under an aggressive chemical environment and dynamic stress, which is an impeller, agitator or mixer, and wherein the process apparatus is formed of stainless steel, wherein a surface of the process apparatus is roughened to a roughness of at least 10 m Rz, and the process apparatus comprises a passivation layer on the roughened surface of the stainless steel, and a rubber lining on the passivation layer.

24. The process apparatus according to claim 23, wherein the surface of the process apparatus is roughened to a roughness of at least 15 m Rz, or at least 20 m Rz.

25. The process apparatus according to claim 23, wherein it comprises a layer of a primer and/or a layer of an adhesive between the passivation layer and the rubber lining.

26. The process apparatus according to claim 23, wherein the rubber is halobutyl rubber, preferably bromobutyl rubber.

27. The process apparatus according to claim 23, wherein the stainless steel is super duplex stainless steel.

28. The process apparatus according to claim 23 obtainable by the method for manufacturing a process apparatus for moving liquid in high temperature liquid immersion under an aggressive chemical environment and dynamic stress, wherein the process apparatus is an impeller, agitator or mixer, and wherein the method comprises the step of lining a process apparatus formed of stainless steel with rubber, wherein the method comprises: roughening a surface of the process apparatus to a roughness of at least 10 m Rz; and forming a passivation layer on the roughened surface of the process apparatus in an acid bath prior to lining the process apparatus comprising the passivation layer with rubber.

29. The method according to claim 17, wherein a surface of the process apparatus is roughened to a roughness of at least 15 m Rz, or at least 20 m Rz, prior to forming the passivation layer on the roughened surface of the process apparatus.

30. The method according to claim 17, wherein a primer and/or an adhesive is applied on the passivation layer prior to lining the process apparatus comprising the passivation layer with rubber.

31. The method according to claim 18, wherein a primer and/or an adhesive is applied on the passivation layer prior to lining the process apparatus comprising the passivation layer with rubber.

32. The method according to claim 17, wherein the acid bath is a nitric acid bath or a citric acid bath.

33. The method according to claim 18, wherein the acid bath is a nitric acid bath or a citric acid bath.

34. The method according to claim 19, wherein the acid bath is a nitric acid bath or a citric acid bath.

35. The method according to claim 17, wherein the rubber is halobutyl rubber, preferably bromobutyl rubber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:

[0058] FIG. 1 shows an embodiment of the process apparatus; and

[0059] FIG. 2 illustrates a cross-section of the process apparatus shown in FIG. 1.

DETAILED DESCRIPTION

[0060] Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

[0061] For reasons of simplicity, item numbers will be maintained in the following exemplary embodiments in the case of repeating components.

[0062] FIG. 1 illustrates one embodiment of the process apparatus. In this embodiment, the process apparatus 1, formed of stainless steel, comprises a hub 4 comprising an opening 5 which may be connected to an axis. The process apparatus is rotatable about the axis for moving liquid in which it may be immersed. The process apparatus comprises a plurality of pitched blades 6 which extend outwardly from the hub 4; in general, the number, pitch and shape of blades may vary.

[0063] FIG. 2 is a cross-section II-II of FIG. 1. The blade 6 of the process apparatus 1 comprises a rubber lining 3 and a passivation layer 2 disposed between the blade 6 formed of stainless steel and the rubber lining 3. The passivation layer 2 is formed on the surface of the stainless steel. In this exemplary embodiment, the rubber lining 3 covers the entire surface of the passivation layer 2.

EXAMPLES

Comparative Example

[0064] Steel slabs were cut from super 2507 duplex stainless steel (6024.5 mm). The surface of the slabs was roughened and a primer lining was applied on the roughened surface immediately. The steel slabs were lined with three different primer combinations and with two layers of CEMENT TC 5000 adhesive. Two steel slabs were lined with each primer combination:

Chemosil 211+Chemosil 411 (Henkel) Sample 1

HG1+HG2 Sample 2

PR500+S500-2 Sample 3

[0065] The steel slabs lined with the primer combinations and the adhesive were rubber lined with Chemoline 13 bromobutyl rubber (Rema TipTop) and vulcanized at 140 C. for 4 h.

[0066] One steel slab of each of the samples 1-3 was immersed in sulphuric acid solution at 95 C. for 1000 h in a 10 1 reactor, in which the rubber lined steel slabs were placed in a vertical position. The composition of the sulphuric acid solution was as follows:

TABLE-US-00001 H.sub.2SO.sub.4 75 g/l Fe 45 g/l Cu 15 g/l Cl.sup. 650 mg/l

[0067] The other steel slab of each of the samples 1-3 was not immersed. The adhesion of the rubber lining was tested by measuring the force required to rip the rubber lining off the steel slab. The results are shown in Table 1.

TABLE-US-00002 TABLE 1 Tensile strength test results for samples that were not immersed in sulphuric acid solution and samples that were immersed in sulphuric acid solution. RH refers to adhesion strength in newtons per millimetre (maximum force FH divided by the width of the sample). RH (N/mm.sup.2) Immersion for Sample No immersion 1000 h 1 10.4 2.0 2 10.0 1.2 3 10.1 1.5

[0068] As expected, rubber lining on steel slabs that were not immersed in sulphuric acid solution adhered very well, and a force of at least 10 N/mm.sup.2 was required to pull off the rubber lining. However, immersion for 1000 h in sulphuric acid solution at high temperature led to a significant decrease in adhesion, and a force of approx. 1.6 N/mm.sup.2 on average was required to pull off the rubber lining. Small differences in adhesion were observed between different primers used.

Example 1

[0069] Slabs of super duplex 2507 steel were roughened and passivated by immersing in a nitric acid bath containing 20% (v/v) HNO.sub.3 for 30 min at 25 C., then rinsed and dried with compressed air blow and in a vacuum chamber. A rubber lining was applied on the passivated surface of the steel slabs in a similar manner as in the comparative example. The rubber lined samples were immersed in the sulphuric acid solution for 1000 h either at room temperature (samples 1-2) or at 95 C. (samples 3-6). Tensile strength measurement results are shown in Table 2.

TABLE-US-00003 TABLE 2 Tensile strength test results for passivated samples that were immersed in sulphuric acid solution at room temperature (samples 1 and 2) and samples that were immersed in sulphuric acid solution at 95 C. (samples 3-6). FH refers to the maximum force required to cause separation of the rubber lining. Sample FH (N) RH (N/mm.sup.2) 1 211.53 8.46 2 223.15 8.93 3 217.40 8.70 4 216.68 8.67 5 231.65 9.27 6 196.32 7.85

[0070] The tensile strength test demonstrated that adhesion remained significantly better in samples in which the surface of the roughened steel slab was passivated using nitric acid prior to rubber lining than in the samples of the comparative example. Further, the adhesion was only slightly lower than in samples of the comparative test which were not immersed in sulphuric acid solution. The temperature during the immersion did not appear to have a significant effect on adhesion.

[0071] It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above, instead they may vary within the scope of the claims.