GB2524260A

GB2524260A - Air cooler for hydrogen process application having special header design and repair procedure

Info

Publication number: GB2524260A
Application number: GB1404794.8A
Authority: GB
Inventors: Joachim Conrad
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2014-03-17
Filing date: 2014-03-17
Publication date: 2015-09-23
Also published as: GB201404794D0

Abstract

A tube-tubesheet connection suitable for an air cooler comprises an inlet header (3, Fig. 5), rear header (13, Fig. 5) and outlet header (12, Fig. 5) with tubes connecting to the headers with a tube-tubesheet connection 9 and plugs 2 in the headers opposite the tube-tubesheet connections; the tubes having a threaded groove where the tube connects with the header and a cap 11 having a corresponding threaded groove so that the cap 11 can be tightened onto the tube to seal leaks at the tube-tubesheet connection 9. Leaks at the tube-tubesheet connection can be sealed without cutting or disassembly of the header by screwing the cap onto the tubesheet connection by means of a tightening tool (10, Fig. 8) inserted through the plugged hole opposite the tube end to be sealed.

Description

AIR COOLER FOR HYDROGEN PROCESS APPLICATION HAVING SPECIAL

HEADER DEISGN AND REPAIR PROCEDURE

FIELD OF THE INVENTION

(001) The present invention relates to air coolers that are designed in accordance with the guidelines API 661 / ISO 13706. These air coolers include inlet, outlet and rear headers with a split design and having plugs. Th headers are designed to be leak proof, e.g. allow tightening to avoid leaks of process, gas, air and other substances.

BACKGROUND OF THE INVENTION

(002) The prevention of leakage is an important consideration for the design of headers and tube-tubesheet connections in air coolers. Welding of headers generally satisfies the need for leakage free connections. However, welding does not always achieve leak free tube-tubesheet connections. Testing can be done to determine if leaks are present. For example, He-test, x-ray, PT and other tests can be carried out to find leaks that can then be corrected by welding. However, in critical process applications, such as hot process ::" * gas interacting with cool air, leaks can develop, particularly in the tube-tubesheet connections. If such a leak is detected, it must be repaired safely which generally requires shut down of the air cooler and dismantling of mtjor components, such as the headers to be able to repair the leak of the tube-tubesheet connection.

(003) Prior art related to air coolers and possible solutions to tube-tubesheet connection * : leaks, for example through the use of special plugs are found in prior patents EPO 154833; EP2413083; EP0225544; and EP2423635.

(004) There remains a need the art for improvements to air coolers and the prevention of leaks therein.

SUMMARY OF THE PRESENT INVENTION

(005) The invention provides an air cooler system wherein leaks at the tube-tubesheet connection can be easily repaired without cutting, disassembly, re-welding and leak testing of the headers. This is accomplished according to the invention by providing a new header design having specialized designed plugs that allow access to the tube-tubesheet connection without requiring disassembly of the header.

BRIEF DESCRIPTION OF THE DRAWINGS

(006) Figure 1 is a schematic view of an air cooler as known in the prior art.

(007) Figure 1A is a cross sectional view taken along line A-A of Figure 1.

(008) Figure lB is a cross sectional view taken along line B-B of Figure 1.

(009) Figure 2 is a detailed view of area I of Figure 1.

:. (010) Figure 3 is a detailed view of area II of Figure 2.

0: (011) Figure 3A is a cross sectional view taken along line A of Figure 3.

(012) Figure 3B is an expanded view the welded layers of Figure 3.

(013) Figure 4 is a detailed view of area Ill of Figure 2.

(014) Figure 5 is a schematic view of an air cooler according to the invention.

(015) Figure 6 is a detailed view of area I of FigureS.

(016) Figure 7 is a detailed view of area II of Figure 6.

(017) Figure 8 is a further detailed view of area I of FigureS.

DETAILED DESCRIPTION OF TI-lB INVENTION

(018) The invention will be described in detail with reference to the drawing figures.

Figure I is a schematic view of an air cooler as known in the prior art. The air cooler includes an inlet 4, an inlet header 3, a rear header 13, an outlet header 12 and an outletS.

A vent 6 and drain 7 are associated with the rear header 13. As shown in Figure 1 the headers connect with the tube sheet by tube-tubesheet connections I. In operation hot gas such as syngas at about 160°C enters the air cooler through inlet 4 and passes through the tubesheet, rear header 13 and is then released tirough outlet Sat a temperature of about 60°C. The dark arrows in Figure 1 represent the flow of heat through the air cooler as well as the release of heat into the cold outside air surrounding the tubesheet. Figure IA is a cross sectional view taken along line A-A of Figure I and shows the inlet 4, outlet 5, *. ..

* and inlet header 3. Figure lB is a cross sectional view taken along line B-B of Figure 1 and shows the vent 6 and drain 7. * *.

:.: * (019) Figure 2 is a detailed view of area! of Figure Ishowing a headerS (this can be any of the inlet header, rear header or outlet header) in greater detail. Figure 2 includes details of the plug 2 and tube-tubesheet connection 1 for the headerS. Figure 3 is a detailed view of area II of Figure 2 showing details of the tube-tubesheet connection as known in the prior art. Figure 3A is a cross sectional view taken along line A of Figure 3 and shows the configuration of the tube-tubesheet connection. Figure 3B is an expanded view the welded layers included in the tube-tubesheet ccnnection of Figure 3.

(020) Figure 4 is a detailed view of area III of Figure 2 showing details of the plug 2.

(021) Figures 1, IA, lB, 2,3, 3A, 313 and 4 represent an air cooler as know in the prior art. In this air cooler, the headers are welded and plugged to avoid leakage. In particular, the tube-tubesheet connections between the headers and tubesheet are welded and tested to assure there is no leakage. While the welds of the plugs in the headers are generally long lasting and prevent leaks from the headers, the tube-tubesheet connections are under greater stress and can develop leaks. When such a leak occurs, repair of the leak is difficult. The header must be cut open and disassembled so that the tube-tubesheet connection can be accessed The leak is then repaired by welding and the header must be reassembled and re-plugged. Testing is also required to assure that no leaks persist. This is both time consuming and expensive.

(022) The air cooler of the invention overcomes the problems associated with fixing leaks in the prior art systems. Figure 5 is a schematic view of an air cooler according to * the invention and includes most of the same components as the prior art air cooler. The air cooler of the invention includes an inlet 4, an inlet header 3, a rear header 13, an outlet *. 0* * * header 12 and an outlet 5. A vent 6 and drain 7 are again associated with the rear header 13. The air cooler of the invention operates to cool hot gas such as hot syngas that enters the air cooler through inlet 4 at about 160°C, with the gas passing through the tubesheet, ::: rear header 1 3 and outlet header 12 and out of outlet 5 at a temperature of about 60°C.

The gas is cooled by cold air surrounding the Tubesheet. The dark arrows in Figure 5 represent the flow of heat through the air cooier as well as the release of heat into the cold outside air. This is all like the prior art air cooler. The difference in the air cooler of the invention resides in the header plugs 2 and the wbe-tubesheet connections 9 as will be further explained with reference to Figures 6, 7 and 8.

(023) Figure 6 is a detailed view of area I of Figure 5 showing details of the plug 2 and tube-tubesheet connection 9 for a header 8. According to the invention, the tube-tubesheet connection 9 includes threaded grooves surrounding the tube where the tube is inserted into the header. Figure 7 is a detailed view of area II of Figure 6 showing greater detail of the tube-tubesheet connection according to the invention. n particular, the tube-tubesheet connection 9 includes threaded grooves on its outer surface that can be engaged by a correspondingly threaded cover Ii. The cover II includes gaskets that seal the end of the tube and the threaded surface to the tube to seal any leaks that have occurred. The cover II can be installed without disassembling the header. As shown in Figure 8, the plug opposite the tube to be sealed is opened and the cover 11 is inserted and connected to the tube. A tightening tool 10 can be used to tighten the cover 11 through the open plug. Once frilly tightened, the header can be re-plugged and operation of the air cooler can be restarted.

(024) The invention offers several advantages over the prior art. In particular, it is * . possible to repair a leak of a tube-tubesheet ecnnection in a short period of time, thereby * : ** avoiding long operational shutdown of the prccess plant. Further, the invention makes it possible to repair the leak without having to cut and disassemble the plugged header. By : . using the cover of the invention to repair the leak, the risk of fUrther leaking is minimized.

In addition, when repairing one Leak, it is possible to tighten all of the tube-tubesheet connections in order to minimize the risk of fUrther leaks developing.

(025) It is anticipated that other embodiments and variations of the present invention will become readily apparent to the skilled artisan in the light of the foregoing description. For example, the design of the invention as shown in Figure Sshows the plugged header having an opening bigger than the outside diameter of the tube-tubesheet connection. Other configurations are possible as would be readily apparent to one skilled in the art. *0

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