HEAT INTEGRATION VIA HEAT PUMP ON A BOTTOM DIVIDING WALL COLUMN

Abstract

A dividing wall column system is provided. The dividing wall column system comprises a dividing wall column, a first reboiler, a second reboiler, and a heat pump. The dividing wall column includes a dividing wall positioned in a bottom section of the dividing wall column to divide the bottom section of the dividing wall column into a first side and a second side. The first reboiler is outside of the dividing wall column and in fluid communication with the first side of the bottom section of the dividing wall column. The second reboiler is outside of the dividing wall column and in fluid communication with the second side of the bottom section of the dividing wall column. The heat pump is in fluid communication with the dividing wall column and the second reboiler and configured to compress a first portion of an overhead product from the dividing wall column.

Claims

1. A dividing wall column system comprise, comprising: a dividing wall column comprising a dividing wall positioned in bottom section of the dividing wall column to divide the bottom section of the dividing wall column into a first side and a second side; a first reboiler outside of the dividing wall column and in fluid communication with the first side of the bottom section of the dividing wall column; a second reboiler outside of the dividing wall column and in fluid communication with the second side of the bottom section of the dividing wall column; and a heat pump in fluid communication with the dividing wall column and the second reboiler and configured to compress a first portion of an overhead product from the dividing wall column.

2. The dividing wall column system of claim 1, further comprising a first condenser in fluid communication with the second reboiler.

3. The dividing wall column system of claim 1, wherein the second reboiler is fluidly coupled to the dividing wall column to feed-reflux to the second side of the dividing wall column and the first reboiler is fluidly coupled to the dividing wall column to feed-reflux to the first side of the dividing wall column.

4. The dividing wall column system of claim 1, further comprising a second condenser in fluid communication with the dividing wall column and configured to receive a second portion of the overhead product from the dividing wall column.

5. The dividing wall column system of claim 4, further comprising an accumulator in fluid communication with the first condenser and the second condenser condensers.

6. The dividing wall column system of claim 4, wherein the accumulator is in fluid communication with the dividing wall column to feed-reflux to the dividing wall column.

7. A method of producing an i-C.sub.4-hydrocarbon product, the method comprising: introducing a feed containing hydrocarbons to the dividing wall column of the dividing wall column system in accordance with claim 1: feeding, from the first side of the dividing wall column, a bottom product comprising n-C.sub.4-hydrocarbons to the first reboiler; feeding, from the second side of the dividing wall column, a bottom product comprising n-C.sub.4-hydrocarbons to the second re boiler feeding the first portion of the overhead product from the dividing wall column to the heat pump and compressing the first portion of the overhead product therein to form a compressed overhead product; and feeding the compressed overhead product from the heat pump to the second reboiler to exchange heat between the compressed overhead product and the bottom product comprising n-C.sub.4-hydrocarbons.

8. The method of claim 7, wherein a reflux stream is fed from the second reboiler to the second side of the bottom section of the dividing wall column.

9. The method of claim 7, wherein a reflux stream is fed from the first reboiler to the first side of the bottom section of the dividing wall column.

10. The method of claim 7, further comprising feeding the compressed overhead product from the second reboiler to a first condenser and condensing it therein to form a condensed overhead product.

11. The method of claim 10, wherein the dividing wall column system-4044 further comprises an accumulator, further comprising feeding the condensed overhead product from the first condenser to the accumulator.

12. The method of claim 7, wherein the dividing wall column system further comprises a second condenser, further comprising feeding a second portion of the overhead product from the dividing wall column to the second condenser.

13. The method of claim 12, further comprising feeding the second portion of the overhead product to the accumulator.

14. The method of claim 13, further comprising producing an i-C.sub.4-hydrocarbon feed from the accumulator.

15. The method of claim 14, further comprising leading a reflux stream from the accumulator to the dividing wall column.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The disclosure will be explained in more detail hereinafter with mference to the drawings.

[0035] FIG. 1 illustrates a bottom dividing wall column system with a heat pump in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0036] Various aspects will now be described more fully with reference to the accompanying drawing. The disclosure may, however, be embodied in many different forms and should not be construed as limited to the aspects set forth herein.

[0037] FIG. 1 illustrates a bottom dividing wall column system 100 according to an embodiment of the present disclosure. The system 100 includes a dividing wall column 102 that receives a feed 104 that includes hydrocarbons. The dividing wall column 102 includes a bottom dividing wall 106 that divides the bottom section of the dividing wall column 102 into two sides 108, 109. The bottom dividing wall 106 extends vertically from the bottom of the dividing wall column 102 upwardly over about 50% of the height of the dividing wall column 102. Furthermore, the dividing wall column system 100 includes a first reboiler 110 and a second reboiler 112 that are fluidly, coupled to sides 108, 109 of the bottom sections of the dividing wall column 102 respectively. The second reboiler 112 is embodied as a shell and tube reboiler. The first reboiler 110 strips the feed on the first side 108 of the dividing wall 106 of C.sub.4-hydrocarbons and produces a C.sub.5+-product stream on that first side 108 of the dividing wall 106, which is withdrawn from the dividing column system 100 via the C.sub.5+-hydrocarbon product line 113. The second reboiler 112 strips i-C.sub.4-hydrocarbons and produces a n-C.sub.4-hydrocarbon product stream. In addition, the bottom dividing wall column system 100 comprises a compressor 118 (or heat pump, respectively), a first condenser 120, a second condenser 114, a third condenser 122 and an (overhead) accumulator 116.

[0038] The dividing wall column 102 outputs an overhead product (or light product, respectively) at the top of the dividing wall column. A first portion of the overhead product is fed via line 124 to the compressor 118, where it is compressed. The compressed overhead product is then fed into the tube side of the second reboiler 112, whereas the bottom product withdrawn from the bottom section of the dividing wall column 102 is fed into the shell of the second reboiler 112 so that a heat exchange between the warmer compressed overhead product and the colder bottom product is effected, which leads to an at least partial vaporization of the n-C.sub.4-hydrocarbon bottom product obtained in the second side 109 of the bottom section of the dividing wall column 102. While a portion of the n-C.sub.4-hydrocarbon bottom product is refluxed from the shell of the second reboiler 112 via the reflux line 126 back into the bottom section of the dividing wall column 102, the other portion of the n-C.sub.4-hydrocarbon bottom product is withdrawn from the dividing column system 100 via the n-C.sub.4-hydrocarbon product line 128. Alternatively, a part of or all of the n-C.sub.4-hydrocarbon product stream may be withdrawn from the column sump 129 instead of from the reboiler 112. The compressed overhead product is fed from the tube side of the second reboiler 112 to the first condenser 120, from there to the third condenser 122, and from there into the accumulator 116.

[0039] The second portion of the overhead product is fed via line 130 directly, i.e. under bypassing the compressor 118, to the second condenser 114 and from there to the accumulator 116, where it is combined with the first portion of the overhead product which has been led through the compressor 118 and through the second reboiler 112. From the accumulator 116, a portion of the i-C.sub.4-hydrocarbon overhead product is recycled via reflux line 132 into the top section of the dividing wall column 102, whereas the other portion of the i-C.sub.4-hydrocarbon overhead product is withdrawn from the dividing column system 100 via the i-C.sub.4-hydrocarbon product line 134.

[0040] The dividing wall column 102 is typically operated at a pressure of less than 1 MPag. The light product (i.e. overhead vapor) from dividing wall column 102 is close to typical cooling water supply temperature ranges. As such, by condensing the light product in reboiler 112, cooling water requirements and heating medium requirements are reduced.

[0041] The benefits of bottom dividing wall column system 100 include: [0042] Reduction in overhead condensing duty, thereby requiring less cooling water supply. [0043] Reduction in hot medium requirement (typically hot oillsteam) for the n-C.sub.4-reboiler. [0044] Savings in operating costs. [0045] Smaller footprint of the hot oil system due to a lower requirement of hot oil, [0046] Lower heater emissions due to lower hot oil requirement.