Processes and systems for generating steam from multiple hot process streams

Abstract

Embodiments of processes and an apparatus for generating steam are provided. The process comprises the steps of indirectly heating water in a first thermosyphon heat exchanger with a first hot stream to form a first stream of heated water comprising steam. The first stream of heated water is fluidly communicated to a first steam drum via natural circulation. Water is indirectly heated in a second thermosyphon heat exchanger with a second hot stream from the process unit to form a second stream of heated water comprising steam. The second stream of heated water is fluidly communicated to the first steam drum via natural circulation. Steam is recovered from the first steam drum.

1 . A process for generating steam comprising the steps of:
 introducing a first hot stream to a first thermosyphon heat exchanger;   indirectly heating water in the first thermosyphon heat exchanger with the first hot stream to form a first stream of heated water comprising steam;   thermosyphoning water between a first steam drum and the first thermosyphon heat exchanger including fluidly communicating the first stream of heated water to the first steam drum via natural circulation;   introducing a second hot stream to a second thermosyphon heat exchanger;   indirectly heating water in the second thermosyphon heat exchanger with the second hot stream to form a second stream of heated water comprising steam;   thermosyphoning water between the first steam drum and the second thermosyphon heat exchanger including fluidly communicating the second stream of heated water to the first steam drum via natural circulation; and   recovering steam from the first steam drum.   
     
     
         2 . The process according to  claim 1 , wherein the step of indirectly heating water in the first thermosyphon heat exchanger includes indirectly heating water with the first hot stream to form the first stream of heated water comprising steam that is at a temperature of about 175 to about 195° C., and the step of indirectly heating water in the second thermosyphon heat exchanger includes indirectly heating water with the second hot stream to form the second stream of heated water comprising steam at a temperature of about 175 to about 195° C. 
     
     
         3 . The process according to  claim 1 , wherein the step of indirectly heating water in the first thermosyphon heat exchanger includes indirectly heating water with the first hot stream to form the first stream of heated water comprising steam that is at a pressure of about 790 to about 1300 kPa gauge. 
     
     
         4 . The process according to  claim 1 , wherein the step of indirectly heating water in the first thermosyphon heat exchanger includes indirectly heating a first stream of liquid water with the first hot stream to form the first stream of heated water comprising steam such that from about 1/10 to about 1/20 by weight of the first stream of liquid water is converted to steam, and wherein the step of indirectly heating water in the second thermosyphon heat exchanger includes indirectly heating a second stream of liquid water with the second hot stream to form the second stream of heated water comprising steam such that from about 1/10 to about 1/20 by weight of the second stream of liquid water is converted to steam. 
     
     
         5 . The process according to  claim 1 , wherein the first thermosyphon heat exchanger comprises a first shell portion and a first tube portion that is configured in the first shell portion for thermal exchange with the first shell portion, and wherein the step of introducing the first hot stream includes introducing the first hot stream to the first tube portion, and the step of indirectly heating water in the first thermosyphon heat exchanger includes fluidly communicating water through the first shell portion and fluidly communicating the first hot stream through the first tube portion to indirectly heat water and form the first stream of heated water. 
     
     
         6 . The process according to  claim 5 , wherein the second thermosyphon heat exchanger comprises a second shell portion and a second tube portion that is configured in the second shell portion for thermal exchange with the second shell portion, and wherein the step of introducing the second hot stream includes introducing the second hot stream to the second tube portion, and the step of indirectly heating water and the second thermosyphon heat exchanger includes fluidly communicating water through the second shell portion and fluidly communicating the second hot stream through the second tube portion to indirectly heat water and form the second stream of heated water. 
     
     
         7 . The process according to  claim 1 , wherein the step of thermosyphoning water between the first steam drum and the first thermosyphon heat exchanger includes fluidly communicating a first liquid water stream from the first steam drum to the first thermosyphon heat exchanger through a first drum water outlet line and fluidly communicating the first stream of heated water from the first thermosyphon heat exchanger to the first steam drum through a first heated water inlet line, and the step of thermosyphoning water between the first steam drum and the second thermosyphon heat exchanger includes fluidly communicating a second liquid water stream from the first steam drum to the second thermosyphon heat exchanger through a second drum water outlet line and fluidly communicating the second stream of heated water from the second thermosyphon heat exchanger to the first steam drum through a second heated water inlet line, and wherein each of the first and second drum water outlet lines and the first and second heated water inlet lines are separately and directly connected to the first steam drum. 
     
     
         8 . The process according to  claim 1 , wherein the step of indirectly heating water in the first thermosyphon heat exchanger includes indirectly heating water with the first hot stream to form a first cooled hot stream, and the step of indirectly heating water in the second thermosyphon heat exchanger includes indirectly heating water with the second hot stream to form a second cooled hot stream, and wherein the process further comprises the steps of:
 introducing the first cooled hot stream to a third thermosyphon heat exchanger;   indirectly heating water in the third thermosyphon heat exchanger with the first cooled hot stream to form a third stream of heated water comprising steam;   thermosyphoning water between a second steam drum and the third thermosyphon heat exchanger including fluidly communicating the third stream of heated water to the second steam drum via natural circulation;   introducing the second cooled hot stream to a fourth thermosyphon heat exchanger;   indirectly heating water in the fourth thermosyphon heat exchanger with the second cooled hot stream to form a fourth stream of heated water comprising steam;   thermosyphoning water between the second steam drum and the fourth thermosyphon heat exchanger including fluidly communicating the fourth stream of heated water to the second steam drum via natural circulation; and   recovering steam from the second steam drum.   
     
     
         9 . The process according to  claim 8 , wherein the step of indirectly heating water in the third thermosyphon heat exchanger includes indirectly heating water with the first cooled hot stream to form the third stream of heated water comprising steam at a temperature of about 140 to about 160° C., and the step of indirectly heating water in the fourth thermosyphon heat exchanger includes indirectly heating water with the second cooled hot stream to form the fourth stream of heated water comprising steam at a temperature of about 140 to about 160° C. 
     
     
         10 . The process according to  claim 8 , wherein the third thermosyphon heat exchanger comprises a third shell portion and a third tube portion that is configured in the third shell portion for thermal exchange with the third shell portion, and wherein the step of introducing the first cooled hot stream includes introducing the first cooled hot stream to the third tube portion, and the step of indirectly heating water in the third thermosyphon heat exchanger includes fluidly communicating water through the third shell portion and fluidly communicating the first cooled hot stream through the third tube portion to indirectly heat water and form the third stream of heated water. 
     
     
         11 . The process according to  claim 10 , wherein the fourth thermosyphon heat exchanger comprises a fourth shell portion and a fourth tube portion that is configured in the fourth shell portion for thermal exchange with the fourth shell portion, and wherein the step of introducing the second cooled hot stream includes introducing the second cooled hot stream to the fourth tube portion, and the step of indirectly heating water in the fourth thermosyphon heat exchanger includes fluidly communicating water through the fourth shell portion and fluidly communicating the second cooled hot stream through the fourth tube portion to indirectly heat water and form the fourth stream of heated water. 
     
     
         12 . The process according to  claim 8 , wherein the step of thermosyphoning water between the second steam drum and the third thermosyphon heat exchanger includes fluidly communicating a third liquid water stream from the second steam drum to the third thermosyphon heat exchanger through a third drum water outlet line and fluidly communicating the third stream of heated water from the third thermosyphon heat exchanger to the second steam drum through a third heated water inlet line, and the step of thermosyphoning water between the second steam drum and the fourth thermosyphon heat exchanger includes fluidly communicating a fourth liquid water stream from the second steam drum to the fourth thermosyphon heat exchanger through a fourth drum water outlet line and fluidly communicating the fourth stream of heated water from the fourth thermosyphon heat exchanger to the second steam drum through a fourth heated water inlet line, and wherein each of the third and fourth drum water outlet lines and the third and fourth heated water inlet lines are separately and directly connected to the second steam drum. 
     
     
         13 . An apparatus for generating steam, the apparatus comprising:
 a first steam drum configured for providing water and receiving steam for recovery thereof;   a first thermosyphon heat exchanger;   a first thermosyphoning water loop circuit that is in fluid communication with the first steam drum and the first thermosyphon heat exchanger, wherein the first thermosyphoning heat exchanger is configured for fluid communication with a first hot process line to receive a first hot stream from a process unit, and wherein the first thermosyphon heat exchanger is configured to indirectly heat water with the first hot stream to form a first stream of heated water comprising steam, and the first thermosyphoning water loop circuit is cooperatively configured with the first thermosyphon heat exchanger for thermosyphoning water between the first steam drum and the first thermosyphon heat exchanger including fluidly communicating the first stream of heated water to the first stream drum via natural circulation;   a second thermosyphon heat exchanger;   a second thermosyphoning water loop circuit that is in fluid communication with the first steam drum and the second thermosyphon heat exchanger, wherein the second thermosyphoning heat exchanger is configured for fluid communication with a second hot process line to receive a second hot stream from the process unit, and wherein the second thermosyphon heat exchanger is configured to indirectly heat water with the second hot stream to form a second stream of heated water comprising steam, and the second thermosyphoning water loop circuit is cooperatively configured with the second thermosyphon heat exchanger for thermosyphoning water between the first steam drum and the second thermosyphon heat exchanger including fluidly communicating the second stream of heated water to the first stream drum via natural circulation.   
     
     
         14 . The apparatus according to  claim 13 , wherein the first and second thermosyphon heat exchangers are disposed underneath the first steam drum to facilitate thermosyphoning of water between the first steam drum and the first and second thermosyphon heat exchangers. 
     
     
         15 . The apparatus according to  claim 13 , wherein the first thermosyphoning water loop circuit comprises a first drum outlet line and a first heated water inlet line, the first drum outlet line and the first heated water inlet line configured to fluidly communicate water from the first steam drum to the first thermosyphon heat exchanger and to fluidly communicate the first stream of heated water from the first thermosyphon heat exchanger to the first steam drum, respectively, and the second thermosyphoning water loop circuit comprises a second drum outlet line and a second heated water inlet line, the second drum outlet line and the second heated water inlet line configured to fluidly communicate water from the first steam drum to the second thermosyphon heat exchanger and to fluidly communicate the second stream of heated water from the second thermosyphon heat exchanger to the first steam drum, respectively, and wherein each of the first and second drum water outlet lines and the first and second heated water inlet lines are separately and directly connected to the first steam drum. 
     
     
         16 . The apparatus according to  claim 13 , wherein the first thermosyphon heat exchanger comprises a first shell portion that is in fluid communication with the first thermosyphoning water loop circuit, and a first tube portion that is in fluid communication with the first hot process line and is configured in the first shell portion for thermal exchange with the first shell portion, and wherein the second thermosyphon heat exchanger comprises a second shell portion that is in fluid communication with the second thermosyphoning water loop circuit, and a second tube portion that is in fluid communication with the second hot process line and is configured in the second shell portion for thermal exchange with the second shell portion. 
     
     
         17 . The apparatus according to  claim 13 , further comprising:
 a second steam drum configured for providing water and receiving steam for recovery thereof;   a third thermosyphon heat exchanger;   a third thermosyphoning water loop circuit that is in fluid communication with the second steam drum and the third thermosyphon heat exchanger;   a first cooled hot stream line in fluid communication with the first and third thermosyphon heat exchangers to advance a first cooled hot stream from the first thermosyphon heat exchanger to the third thermosyphon heat exchanger, wherein the third thermosyphon heat exchanger is configured to indirectly heat water with the first cooled hot stream to form a third stream of heated water comprising steam, and the third thermosyphoning water loop circuit is cooperatively configured with the third thermosyphon heat exchanger for thermosyphoning water between the second steam drum and the third thermosyphon heat exchanger including fluidly communicating the third stream of heated water to the second stream drum via natural circulation;   a fourth thermosyphon heat exchanger;   a fourth thermosyphoning water loop circuit that is in fluid communication with the second steam drum and the fourth thermosyphon heat exchanger;   a second cooled hot stream line in fluid communication with the second and fourth thermosyphon heat exchangers to advance a second cooled hot stream from the second thermosyphon heat exchanger to the fourth thermosyphon heat exchanger, wherein the fourth thermosyphon heat exchanger is configured to indirectly heat water with the second cooled hot stream to form a fourth stream of heated water comprising steam, and the fourth thermosyphoning water loop circuit is cooperatively configured with the fourth thermosyphon heat exchanger for thermosyphoning water between the second steam drum and the fourth thermosyphon heat exchanger including fluidly communicating the fourth stream of heated water to the second stream drum via natural circulation.   
     
     
         18 . The apparatus according to  claim 17 , wherein the third and fourth thermosyphon heat exchangers are disposed underneath the second steam drum to facilitate thermosyphoning of water between the second steam drum and the third and fourth thermosyphon heat exchangers. 
     
     
         19 . The apparatus according to  claim 17 , wherein the third thermosyphoning water loop circuit comprises a third drum outlet line and a third heated water inlet line, the third drum outlet line and the third heated water inlet line configured to fluidly communicate water from the second steam drum to the third thermosyphon heat exchanger and to fluidly communicate the third stream of heated water from the third thermosyphon heat exchanger to the second steam drum, respectively, and the fourth thermosyphoning water loop circuit comprises a fourth drum outlet line and a fourth heated water inlet line, the fourth drum outlet line and the fourth heated water inlet line configured to fluidly communicate water from the second steam drum to the fourth thermosyphon heat exchanger and to fluidly communicate the fourth stream of heated water from the fourth thermosyphon heat exchanger to the second steam drum, respectively, and wherein each of the third and fourth drum water outlet lines and the third and fourth heated water inlet lines are separately and directly connected to the second steam drum. 
     
     
         20 . The apparatus according to  claim 17 , wherein the third thermosyphon heat exchanger comprises a third shell portion that is in fluid communication with the third thermosyphoning water loop circuit, and a third tube portion that is in fluid communication with the first cooled hot stream line and is configured in the third shell portion for thermal exchange with the third shell portion, and wherein the fourth thermosyphon heat exchanger comprises a fourth shell portion that is in fluid communication with the fourth thermosyphoning water loop circuit, and a fourth tube portion that is in fluid communication with the second cooled hot stream line and is configured in the fourth shell portion for thermal exchange with the fourth shell portion.