Indirect fired heat exchanger

Abstract

An indirect fired heat exchanger is provided, comprising an arcuate airflow pattern.

1 . A heat exchanger for use in an indirect fired heater, said heat exchanger comprising an arcuate process airflow pattern. 
     
     
         2 . The heat exchanger of  claim 1 , wherein the arcuate process airflow pattern is a horseshoe shaped airflow pattern. 
     
     
         3 . The heat exchanger of  claim 1 , wherein the arcuate process airflow pattern is an omega-shaped pattern. 
     
     
         4 . The heat exchanger of  claim 1 , wherein the process airflow pattern is directed by one or more baffles arranged within the heat exchanger. 
     
     
         5 . The heat exchanger of  claim 4 , wherein the process airflow pattern is directed by three connected baffles forming an airflow diversion within the heat exchanger. 
     
     
         6 . The heat exchanger of  claim 1 , further comprising a final pass section situated adjacent to a process airflow inlet such that process airflow from a process airflow inlet travels firstly over the final pass section. 
     
     
         7 . The heat exchanger of  claim 6 , wherein the final pass section comprises multiple final pass heat exchanger tubes arranged in a horizontal in-line stack configuration. 
     
     
         8 . The heat exchanger of  claim 7  wherein the final pass section is a two pass section. 
     
     
         9 . The heat exchanger of  claim 7 , wherein the multiple final pass heat exchanger tubes are finless. 
     
     
         10 . The heat exchanger of  claim 7 , wherein the multiple final pass heat exchanger tubes comprise external fins. 
     
     
         11 . The heat exchanger of  claim 10 , wherein the fins are 0.5″ wide and are spaced at an interval of 6 fins per inch along the length of the final pass heat exchangers tubes. 
     
     
         12 . The heat exchanger of  claim 7 , further comprising a three-pass heat exchanger section between the final pass heat exchanger section and a primary drum, wherein the primary drum is situated adjacent a process airflow outlet such that process airflow travels lastly over the primary drum. 
     
     
         13 . The heat exchanger of  claim 12 , wherein the heat exchanger section comprises multiple first heat exchanger tubes, said first heat exchanger tubes being arranged in one more patterns selected from the group consisting of a semi-offset pattern and a random stagger pattern. 
     
     
         14 . The heat exchanger of  claim 13 , wherein a first portion of the first heat exchanger tubes are arranged in a semi-offset pattern and a second portion of the first heat exchanger tubes are arranged in a random stagger pattern. 
     
     
         15 . The heat exchanger of  claim 13 , wherein the first heat exchanger tubes and final pass heat exchanger tubes are oriented to promote gravity drainage of condensate from the first and final heat exchanger tubes. 
     
     
         16 . The heat exchanger of  claim 12 , wherein the process airflow inlet and the process airflow outlet are substantially equidistant from a base of the heat exchanger. 
     
     
         17 . The heat exchanger of  claim 12 , wherein the distance from a base of the heat exchanger to the process airflow outlet is greater than the distance from the base of the heat exchanger to the process airflow inlet.