Patent Publication Number: US-2019195566-A1

Title: Heat Exchanger Structure

Description:
RELATE APPLICATIONS 
     This application is a national phase entrance of and claims benefit to PCT Application for a heat exchanger, and the application thereof, PCT/CN2013/000307, filed on Mar. 18, 2013, which claims benefit to Chinese Patent Application 201210432100.2, filed on Nov. 2, 2012. The specifications of both applications are incorporated here by this reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of chemical equipment, in particular to a heat exchanger. 
     DESCRIPTION OF THE PRIOR ART 
     In the context of energy saving and emission reduction and deterioration of crude oil, raw media passing through the cooling-heat transfer equipment such as a heat exchanger are generally dirty and viscous. When flowing through the heat exchanger, the dirty and viscous raw media are deposited onto the inner wall of the heat exchanger, what is more important, they influence fluidity and flow field distribution uniformity of the media inside the heat exchanger. If the media on the shell of the heat exchanger are of gas-liquid phases which enter the shell of the heat exchanger from two pipes respectively, large-viscosity media will certainly influence the degree of mixing uniformity of the two-phase media. The non-uniform mixing can not only result in fluid deviation, but also influence the heat exchange efficiency of the heat exchanger. Consequently, the heat exchange effect can not meet the technical requirements, thus bringing hazards to the long-term and stable operation of the equipment. Meanwhile, in order to improve the heat exchange efficiency of the equipment, the arrangement of heat exchange parts such as tubes is made compactly with a small interval which will result in non-uniform mixing of the fluid in the shell of the heat exchanger and thus influence the heat exchange efficiency. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a heat exchanger having stable operation, long cycle, good heat exchange efficiency and wide scope of application. 
     For achieving the above stated object, a heat exchanger comprises a shell with a top and a bottom having a center and a wall; multiple exchange tubes disposed in multiple layers from the center of the shell to the wall of the shell inside the shell, each layer of exchange tubes having at least one exchange tube, each exchange tube having two ends and a spiral form with a plurality of windings; a first board and a second board arranged in parallel inside the shell, each of the first board and the second board having a plurality of holes, two ends of each exchange tube respectively passing through a hole on the first board and a hole on the second board; and 
     a first spiral gas tube winding in a same direction with two ends disposed inside the shell, two ends of the first spiral gas tube passing through respectively a hole in the first board and a hole on the second board, the first spiral gas tube having a first wall, the first wall facing towards the bottom of the shell being provided with a plurality of first gas pores, and the first spiral gas tube has a first inlet and a first outlet that respectively communicates with out-source gas. 
     As an preference, the heat exchanger further comprises a second spiral gas tube, the second spiral gas tube having a second wall facing towards the top of the shell and being provided with a plurality of second gas pores, the second spiral gas tube has a second inlet and a second outlet that respectively communicates with out-source gas, and a valve is provided on the second inlet and the second outlet of the second gas tube. Such a configuration may be selectively opened when pressure drop of the system or temperature difference at the hot end is obviously increased, to strengthen disturbance. 
     Preferably, the spiral second gas tube has multiple second gas pores with a porosity between 2% and 10% and the second gas pores are separated from each other by a predetermined distance. In this case, the configuration has good disturbance effect. 
     In order to ensure the heat exchange effect, adjacent two layers of exchange tubes wind in opposite directions. 
     Preferably, the first gas pores have a porosity between 2% and 10% and are distributed in an equal interval. Similarly, such a configuration has good disturbance effect. 
     According to the requirements of heat exchange, each layer of exchange tubes is composed of multiple exchange tubes winding in a same direction. Certainly, each layer of exchange tubes may be composed of one exchange tube. 
     The heat exchanger further comprises a core with two ends disposed between the first board and the second board, and each end of the core respectively supported by the first board and the second board, all layers of exchange tubes surround in the center of the core with spiral windings, thereby becoming more stable when wound well and facilitating the installation. 
     Compared with the prior art, in the present invention, the first spiral gas tube is disposed inside the shell, which can carry out online disturbance to the fluid in the shell internally, and the first spiral gas tube is arranged inside the whole layers of exchange tubes in large coverage, the process gas is blown out from every gas pore in a three-dimensional and reticular form to carry out all-around disturbance to the fluid in the shell; even in the case that the fluid media are dirty and viscous and there is only a small spacing between tubes and between layers, the mixing of the fluid media tends to be uniform continuously, thus effectively avoiding the deposition of fluid inside the shell, increasing the heat transfer efficiency, and improving the heat exchange effect. Especially when the heat exchange media on the shell are two-phase mixed media, the heat exchanger can play a role of further mixing the heat exchange media uniformly, to avoid fluid deviation and to effectively ensure the long-term and stable operation of the equipment. 
     Meanwhile, in the present invention, the two gas tubes can also be used as purging tubes during downtime of the equipment, which are in good purging effect, effectively reduce the possibility of equipment failure caused by blockage, can clear the impurities which can not be cleared by the conventional common purging configurations in cooperation with impurity settlement space and inspection holes at the bottom of the equipment, are especially suitable for cleaning, purging and maintaining the interior of the non-detachable heat exchanger equipment. 
     The heat exchanger has multiple exchange tubes disposed in multiple layers from the center of the shell to the wall of the shell, which ensures materials of various viscosities to mix fully and uniformly, resulting in good mixing effect and further improving the heat exchanger efficiency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view of a heat exchanger in accordance with an embodiment of the present invention; 
         FIG. 2  is a sectional view of a first (or second) spiral gas tube in accordance with the embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     To enable a further understanding of the innovative and technological content of the invention herein, refer to the detailed description of the invention and the accompanying drawings below: 
     As shown in  FIG. 1  and  FIG. 2 , this embodiment will be described by taking a vertical heat exchanger as an example. The technology of the present invention is applicable to a horizontal heat exchanger. The heat exchange comprises a shell  1 , a core  2 , multiple exchange tubes  3 , a first spiral gas tube  4  and a second spiral gas tube  5 . 
     The shell  1  of an enclosed configuration, being composed of a vertical cylinder  11  and an upper cover (not shown in the figures) and a lower cover  12  respectively mounted on the two ends of the cylinder  11 . Each end of the cylinder of the shell has a first board (not shown in the figures) and a second board  13  arranged in parallel, the shell has an inlet for connecting exchange tubes (not shown in the figures), an outlet  14  for connecting exchange tubes, a gas-phase inlet  15 , a liquid-phase inlet  16 , an opening of the shell (not shown in the figures) and a condensate drain port  17 , and the condensate drain port  17  may be used as an inspection hole during downtime. The shell further has a gas inlet  18  and a gas outlet (not shown in the figures). Each of the first board and the second board has a plurality of holes, two ends of each exchange tube  3  respectively passes through a hole on the first board and a hole on the second board  13 . 
     The core  2  with two ends is disposed between the first board and the second board  13 , and each end of the core  2  is respectively supported by the first board and the second board  13 . 
     The multiple exchange tubes  3 , divided into many groups with each group having one exchange tube  3  or a plurality of exchange tubes  3 , depending upon the actual demand. Multiple exchange tubes  3  disposed in multiple layers from the center of the shell to the wall of the shell inside the shell, and all layers of exchange tubes  3  surround in the center of the core  2  with spiral windings. In this embodiment, adjacent two layers of exchange tubes  3  wind in opposite directions. Two ends of each exchange tube respectively passes through a hole on the first board and a hole on the second board  13  to communicate with the inlet and the outlet  14 . The number of layers of exchange tubes  3  may be provided according to the size of the heat exchanger and the actual demand, for example, there may be two, five or more layers of exchange tubes. 
     The first spiral gas tube  4 , used for purging gas to the shell, and normally open during running the equipment in the premise of not affecting temperature difference at the hot end to form disturbance to the fluid in the shell and thus to allow the material flowing through the shell to form a turbulent flow, thus improving the mixing of fluid in the shell and preventing fluid in the shell from depositing in the shell  1 . The first spiral gas tube  4  surround in the center of the core  2  with spiral windings, and there may be many first spiral gas tubes  4 , the number of which is equal to that of layers of exchange tubes, that is, each layer of exchange tubes has one first spiral gas tube  4 , and the first spiral gas tube  4  winding in a same direction with the corresponding layer of exchange tubes. The first spiral gas tube  4  has a first wall, the first wall faces towards the bottom of the shell being provided with a plurality of first gas pores  41 , and only some of the first gas pores  41  are shown in the  FIG. 2 . In this embodiment, the first gas pores  41  have a porosity of 7%, which may be specifically set according to specific circumstances, for example, specifically set a porosity between 2% and 10% according to components of fluid in the shell, composition and size of the heat exchanger. The first spiral gas tube has a first inlet, the first inlet passes through the hole on the second board  13  to communicate with the gas inlet  18  of the shell  1 , while the first spiral gas tube has a first outlet, and the first outlet passes through the hole on the first board to communicate with the gas outlet of the shell  1 . The gas inlet  18  and the gas outlet respectively communicates with out-source gas, with the process gas in this embodiment. 
     The second spiral gas tube  5  used for purging gas to the tube, and selectively open when pressure drop of the system is increased or temperature difference of hot end is obviously raised, to strengthen disturbance in cooperation with the gas flow blown out from the first spiral gas tube  4 . The second spiral gas tube  5  surround in the center of the core  2  with spiral windings, and there may be many second spiral gas tubes  5 , the number of which is equal to that of layers of exchange tubes, that is, each layer of exchange tubes has one second spiral gas tube  5 , and the second spiral gas tube  5  winding in a same direction with the corresponding layer of exchange tubes. The second spiral gas tube  5  has a second wall facing towards the top of the shell and being provided with a plurality of second gas pores  51 , in this embodiment each spiral second gas tube  5  has multiple second gas pores with a porosity of 7%, which may be specifically set according to specific circumstances, for example, specifically set a porosity between 2% and 10% according to components of fluid in the shell and size of the heat exchanger. The second spiral gas tube  5  has a second inlet and a second outlet, the second inlet passes through the hole on the second board  13  to communicate with the gas inlet  18  of the shell  1 , while the second outlet passes through the hole on the first board to communicate with the gas outlet of the shell  1 ; and a valve (not shown in the figures) may be selectively opened for controlling gas linking or cutting off. 
     Working principle of the heat exchanger is as follows. 
     When the heat exchanger runs normally, the first spiral gas tube  4  is normally open, and the process gas is blown out from the first spiral gas tube  4  to carry out three-dimensional and all-around disturbance to the fluid in the shell, thereby make the fluid in the shell fully and uniformly mix, while reducing the possibility of deposition of contaminants on the surface of each exchange tube  3  and on the inner wall of the shell  1 , effectively increasing the heat transfer efficiency and ensuring the long-term and stable operation of the equipment. 
     The valve for controlling the second spiral gas tube  5  is opened when pressure drop of the system is increased or temperature difference at the hot end is obviously raised, to make the process gas blow out from the first gas pores  41  and the second gas pores  51  at the same time, thereby strengthening disturbance to the fluid in the shell, and making pressure drop of the system become stable and temperature difference at the hot end balanced. 
     In a shutdown state, when the shell is to be purged, the process gas or purge gas is directly blown into the shell from the first gas pores  41  and the second gas pores  51  to purge the equipment. However, in the prior art, the purging tubes are usually disposed at the bottom of the exchange tubes  3 . Therefore, the purging effect in an area near the bottom of the purging tubes is good but that in an area far from the bottom of the purging tubes is poor. Especially, the contaminants deposited on the outer walls of the exchange tubes  3  can not be cleared. In the present invention, this problem is completely avoided, as this configuration has a large purging area and good purging effect without any dead angle, effectively reduces the possibility of failure of the exchange tube  3  caused by blockage, and can clear the impurities which can not be cleared by the ordinary purging configurations in cooperation with the inspection hole. 
     In the shutdown state, when the equipment is to be chemically cleaned, the gas inlet  18  of the shell is connected to a cleaning solution pipeline, to make the cleaning solution ejected out from the first gas pores  41  and the second gas pores  51 , thus increasing the flow velocity of the cleaning solution and strengthening the chemical cleaning effect.