GB2082309A

GB2082309A - Heat Exchangers

Info

Publication number: GB2082309A
Application number: GB8113825A
Authority: GB
Original assignee: Uhde GmbH
Current assignee: ThyssenKrupp Industrial Solutions AG
Priority date: 1980-05-07
Filing date: 1981-05-06
Publication date: 1982-03-03
Also published as: BE888419A; AU537509B2; DE3017411C2; SE8102804L; NL8102170A; NL188597B; DE3017411A1; NL188597C; BR8102655A; GB2082309B; ZA812994B; AU6988681A

Abstract

The present invention provides a heat exchanger comprising a tube bundle within a housing, 1, each end of the tube bundle being mounted in a tube sheet, wherein the tube bundle is split into two or more discrete tube bundle sections, the outlet ends of each tube being at the same end of the housing. The gas outlet of each tube bundle is connected to a separate chamber 4 and a shut-off valve 6 before joining a common manifold. A cyclone 2 is mounted at the inlet so that the heat exchanger may be used as a cooler for dust-laden gasses. <IMAGE>

Description

SPECIFICATION Heat Exchangers The present invention relates to heat exchangers.

Waste-heat boilers or preheaters of the firetube boiler type are usual in the state of the art and have proved their merits in many plants.

Rapid fouling stage, however, is a problem when these items are operated with dust-laden gases.

Coking characteristics of the dust primarily depend on the moisture content of the dust and of the gas and also on the flow velocity. Operating times of installed gas coolers are frequently too short and the necessary cleaning procedures are unsatisfactory.

There is a need to provide an operative gas cooler for lowering the temperature of for example, dust-laden crude gases and in which the cooling tubes are not subject to severe fouiing even under part-load conditions; moreover, that mechanical cleaning during shut-down periods of the plant should require little expenditure.

The present invention provides a shell-andtube heat exchanger comprising a tube bundle within a housing, each end of the tube bundle being mounted in a tube sheet, wherein the tube bundle is split into two or more discrete tube bundle sections, the outlet ends of each tube being at the same end of the housing.

Preferably, at the outler end of each tube bundle section, there is a separate outlet chamber incorporated into the heat exchanger.

Heat exchangers of the invention find especial application as a gas cooler for dust-laden gases.

In such cases, the tube bundle is preferably arranged in a substantially vertical position. It is further preferred that such a gas cooler be used in conjunction with a cyclone, to cool air from which a substantial proportion of the dust has been removed.

According to a preferred embodiment of the invention, a crude gas cooler is mounted vertically on the discharge nozzle of a cyclone. The discharge end of the cooler is equipped with a number of flanged gas outlet chambers with a downstream shut-off or control valve. In this way, the cooler is partitioned into several parallel passes. The passes can be arranged to ensure the minimum flow velocity necessary to substantially avoid caking of the dust on the tube walls and the formation of deposits even under part-load conditions. In addition, the temperature of the cooling fluid can be adjusted to avoid condensation on the gas side. The result of placing the cooler on the discharge nozzle of a cyclone is that gas-borne dust is retained in the cyclone and that gradual clogging of the cooler inlet chamber is avoided.This arrangement offers further advantages at the time of mechanical cleaning if it is necessary during a routine plant shut-down period. The deposits incrustations drop into the cyclone from where they are discharged.

Depending on the dust load of the gas and on the type of dust, such a cooler may be arranged in a different manner, for example in a vertical position without a cyclone or in a horizontal position with or without a cyclone.

When used as a gas cooler, the heat exchanger of the invention preferably has external insulation on the tube sheet at the tube bundle inlet. Also, each tube preferably has inlet ferrules of heatresistant material.

When used as a gas cooler and when the tube bundle is arranged vertically, it is preferred that there is a cooling fluid inlet in the region of the lower tube sheet. Also, the cooling fluid is preferably subject to natural circulation or preferably subject to forced circulation.

The present invention further provides a crude gas cooler with gas-carrying tubes which are arranged in a longitudinal direction which a liquidfilled vessel, wherein the tube-bundle is split into two or more tube-bundle sections, the gas outlet end of each section being connected to a separate gas outlet chamber and each gas outlet chamber being connected through a control and/or shut-off valve to a header.

One form of heat exchanger of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a section through the heat exchanger partly in diagrammatic form; and Figure 2 is a cross section through the heat exchanger partly in diagrammatic form.

Referring to both Figures a crude gas cooler 1 serves as a steam generator and is placed in a vertical position upon a cyclone 2. The two items are joined by a flanged connection. The tube bundle of the crude gas cooler is split into two or more parallel tube bundle sections 3. The discharge end of each section terminates in a separate gas outlet chamber 4. Each chamber 4 is connected to a gas header 5, each of which is equipped with a control and shut-off valve 6. Gas outlet chamber and valve are joined by a flanged connection 7 which allows mechanical cleaning.

Cooling water is admitted through each of several nozzles 8 near the lower tube sheet. The water/steam mixture is withdrawn at one or more outlets 9 in the region of the upper tube sheet.

The design of such a gas cooler allows one or more sections of the tube bundle to be disconnected during operation for mechanical cleaning. Solids detached from the tubes drop into the cyclone and are discharged. By disconnecting individual tube bundle sections during operation, the flow velocity across the other sections can be substantially raised temporarily. This mode of operation will cause detachment of solids and, consequently, cleaning of the tubes.

Claims

1. A shell-and-tube heat exchanger comprising a tube bundle within a housing, each end of the tube bundle being mounted in a tube sheet, wherein the tube bundle is split into two or more

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Heat Exchangers The present invention relates to heat exchangers. Waste-heat boilers or preheaters of the firetube boiler type are usual in the state of the art and have proved their merits in many plants. Rapid fouling stage, however, is a problem when these items are operated with dust-laden gases. Coking characteristics of the dust primarily depend on the moisture content of the dust and of the gas and also on the flow velocity. Operating times of installed gas coolers are frequently too short and the necessary cleaning procedures are unsatisfactory. There is a need to provide an operative gas cooler for lowering the temperature of for example, dust-laden crude gases and in which the cooling tubes are not subject to severe fouiing even under part-load conditions; moreover, that mechanical cleaning during shut-down periods of the plant should require little expenditure. The present invention provides a shell-andtube heat exchanger comprising a tube bundle within a housing, each end of the tube bundle being mounted in a tube sheet, wherein the tube bundle is split into two or more discrete tube bundle sections, the outlet ends of each tube being at the same end of the housing. Preferably, at the outler end of each tube bundle section, there is a separate outlet chamber incorporated into the heat exchanger. Heat exchangers of the invention find especial application as a gas cooler for dust-laden gases. In such cases, the tube bundle is preferably arranged in a substantially vertical position. It is further preferred that such a gas cooler be used in conjunction with a cyclone, to cool air from which a substantial proportion of the dust has been removed. According to a preferred embodiment of the invention, a crude gas cooler is mounted vertically on the discharge nozzle of a cyclone. The discharge end of the cooler is equipped with a number of flanged gas outlet chambers with a downstream shut-off or control valve. In this way, the cooler is partitioned into several parallel passes. The passes can be arranged to ensure the minimum flow velocity necessary to substantially avoid caking of the dust on the tube walls and the formation of deposits even under part-load conditions. In addition, the temperature of the cooling fluid can be adjusted to avoid condensation on the gas side. The result of placing the cooler on the discharge nozzle of a cyclone is that gas-borne dust is retained in the cyclone and that gradual clogging of the cooler inlet chamber is avoided.This arrangement offers further advantages at the time of mechanical cleaning if it is necessary during a routine plant shut-down period. The deposits incrustations drop into the cyclone from where they are discharged. Depending on the dust load of the gas and on the type of dust, such a cooler may be arranged in a different manner, for example in a vertical position without a cyclone or in a horizontal position with or without a cyclone. When used as a gas cooler, the heat exchanger of the invention preferably has external insulation on the tube sheet at the tube bundle inlet. Also, each tube preferably has inlet ferrules of heatresistant material. When used as a gas cooler and when the tube bundle is arranged vertically, it is preferred that there is a cooling fluid inlet in the region of the lower tube sheet. Also, the cooling fluid is preferably subject to natural circulation or preferably subject to forced circulation. The present invention further provides a crude gas cooler with gas-carrying tubes which are arranged in a longitudinal direction which a liquidfilled vessel, wherein the tube-bundle is split into two or more tube-bundle sections, the gas outlet end of each section being connected to a separate gas outlet chamber and each gas outlet chamber being connected through a control and/or shut-off valve to a header. One form of heat exchanger of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a section through the heat exchanger partly in diagrammatic form; and Figure 2 is a cross section through the heat exchanger partly in diagrammatic form. Referring to both Figures a crude gas cooler 1 serves as a steam generator and is placed in a vertical position upon a cyclone 2. The two items are joined by a flanged connection. The tube bundle of the crude gas cooler is split into two or more parallel tube bundle sections 3. The discharge end of each section terminates in a separate gas outlet chamber 4. Each chamber 4 is connected to a gas header 5, each of which is equipped with a control and shut-off valve 6. Gas outlet chamber and valve are joined by a flanged connection 7 which allows mechanical cleaning. Cooling water is admitted through each of several nozzles 8 near the lower tube sheet. The water/steam mixture is withdrawn at one or more outlets 9 in the region of the upper tube sheet. The design of such a gas cooler allows one or more sections of the tube bundle to be disconnected during operation for mechanical cleaning. Solids detached from the tubes drop into the cyclone and are discharged. By disconnecting individual tube bundle sections during operation, the flow velocity across the other sections can be substantially raised temporarily. This mode of operation will cause detachment of solids and, consequently, cleaning of the tubes. Claims

1. A shell-and-tube heat exchanger comprising a tube bundle within a housing, each end of the tube bundle being mounted in a tube sheet, wherein the tube bundle is split into two or more discrete tube bundle sections, the outlet ends of each tube being at the same end of the housing.

2. A heat exchanger as claimed in claim 1, wherein the outlet end of each tube bundle section is connected to a separate outlet chamber.

3. A heat exchanger as claimed in claim 1 or claim 2, wherein the fluid to pass through the tube bundle is a gas.

4. A heat exchanger as claimed in claim 3, wherein the tube bundle is arranged in a substantially vertical position.

5. A heat exchanger as claimed in claim 3 or claim 4, which is used in conjunction with a cyclone.

6. A heat exchanger as claimed in any one of claims 3 to 5, which is arranged centrally above the cyclone.

7. A heat exchanger as claimed in any one of claims 3 to 6, which is used as a gas cooler.

8. A heat exchanger as claimed in claim 7, wherein the tube sheet at the tube bundle inlet is provided with external insulation.

9. A heat exchanger as claimed in claim 7 or claim 8, wherein each tube is provided with inlet ferrules of heat-resistant material.

10. A heat exchanger as claimed in any one of claims 7 to 9, when the tube bundle is arranged vertically and has a cooling fluid inlet in the region of the lower tube sheet.

11. A heat exchanger as claimed in any one of claims 7 to 10, wherein the cooling fluid is subject to natural or forced circulation.

12. A heat exchanger as claimed in claim 1, which is substantially as described herein with reference to, and as illustrated by, the accompanying drawings.

1 3. A crude gas cooler with gas-carrying tubes which are arranged in a longitudinal direction within a liquid-filled vessei, wherein the tubebundle is split into two or more tube-bundle sections, the gas outlet end of each section being connected to a separate gas outlet chamber and.

each gas outlet chamber being connected through a control and/or shut-off valve to a header.

14. A method of heat transfer between two fluids which comprises passing one fluid in parallel flow through the tubes of two or more discrete tube bundle sections of a shell-and-tube heat exchanger and passing the other fluid over the tubes within the housing of the exchanger.

1 5. A method of heat transfer as claimed in claim 14, which is carried out in a heat exchanger as claimed in any one of claims 1 to 13.