JPS6410035B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a petroleum distillation apparatus that has a main distillation column and a pre-distillation column, and is further equipped with a naphtha rectification system consisting of a stabilizer and a splitter. More specifically, the present invention relates to a petroleum distillation apparatus that can appropriately adopt various naphtha rectification system configurations depending on the distillation performance of a pre-distillation column. In this specification, petroleum typically means crude oil, but generally refers to petroleum-based compounds from which LPG and naphtha can be obtained by distillation. <Prior art> Various types of equipment have been considered for distilling crude oil at normal pressure to extract various fractions. from crude oil preheated by a heat recovery system.
Part of the mixed fraction of LPG and naphtha (light + heavy) is distilled in a pre-distillation column, and the top fraction of the pre-distillation column is directly transferred to the naphtha rectification system consisting of a stabilizer and a splitter to the main distillation column. There is an atmospheric distillation unit for crude oil that is sent together with the overhead fraction. This apparatus will be explained based on the process diagrams of FIGS. 10 and 11. First, as shown in FIG.
After being preheated in a heat recovery system consisting of one or more heat exchanger groups E1 and E2 using the bottom oil 30c and the like as a heat source, it is supplied to the pre-distillation column 20. Each of these heat exchanger groups has a method in which crude oil is sequentially exchanged heat with one or more heat sources (one-through type), and a method in which crude oil is distributed according to the number of heat sources and merged with each heat source after heat exchange (split type). Alternatively, it is a collection of heat exchangers arranged in a combination manner. The pre-distillation column 20 is equipped with a reflux mechanism such as a side line reflux system, an external reflux system at the top, or a combination of both. When the side line reflux system is adopted, the heat of the side line reflux 20a can be used as a heat source for the heat recovery system, as shown in the figure. The heat required for the rectification of crude oil in the pre-distillation column 20 is normally the heat brought in by the crude oil by preheating the crude oil in the heat recovery system, and a reboiler for the pre-distillation column is not particularly required. Although not shown, stripping steam is introduced into the bottom of the pre-distillation column as needed in order to enhance the rectification effect of the pre-distillation column. The crude oil preheated by the heat recovery system heat exchanger groups E1 and E2 is rectified in the pre-distillation column 20, and the pre-distillation column top fraction 20f, which is a part of the LPG/naphtha mixed fraction, is taken out from the top of the column. On the other hand, the pre-distillation column bottom residual oil 20e is further heated in the heating furnace 70 via the heat recovery system heat exchanger group E3, and then supplied to the main distillation column 30. In the main distillation column 30, various fractions 30c and 30d having different boiling point ranges are sequentially distilled, and from the top of the main distillation column are the remaining LPG/naphtha fractions that were not taken out in the previous distillation column. A column overhead fraction 30f is removed, and a residual oil 30e is obtained from the main distillation column bottom. The top mechanisms of both the pre-distillation column 20 and the main distillation column 30 include condensers 21 and 31, a top receiving tank 22,
It consists of an overhead reflux system equipped with 32, and the condensed water is
The LPG/naphtha mixed fractions 20f and 30f are
As shown in Figure 1, they are mixed and sent to the naphtha rectification system, first separated into LPG and naphtha by a stabilizer 40, and then the naphtha fraction is further passed to a splitter 50.
The naphtha is then sent to the US and separated into light naphtha and heavy naphtha. In FIG. 11, symbols F1 and F2 indicate the top reflux paths of the stabilizer 40 and the splitter 50, respectively, and both include a condenser, a top receiving tank, and a pump. Although not shown, a pre-distillation column, a main distillation column,
The stabilizer and splitter are each provided with a gas vent pipe and a regulating valve for adjusting the operating pressure of the tower at the top of the receiving tank. In the crude oil atmospheric distillation equipment as described above,
The preheating temperature of the crude oil supplied to the pre-distillation column 20 is determined by the amount of LPG and naphtha (light + heavy) fractions obtained from the top of the pre-distillation column and the amount of kerosene fraction mixed into the fractions. The premise is that the temperature is such that rectification can be achieved in the pre-distillation column at a level that does not impair the product specifications of the heavy naphtha obtained from the naphtha rectification system. In addition, the operating pressure in the pre-distillation column 20 varies slightly depending on the type of crude oil, preheating temperature, etc., but is usually 1 to 5.
It is operated in the range of Kg/cm ² G. By the way, in both the stabilizer 40 and the splitter 50 in the naphtha rectification system, most of the heat required for the distillation operation is obtained through heating by the reboilers 41 and 51, as shown in FIG.
As shown in FIG. 10, the heat source of the reboiler is usually the bottom residue 30e of the main distillation column 30 or a part of the side line reflux 30b. In FIG. 10, the heat source of the reboiler 41 of the stabilizer 40 is the residual oil 30e from the bottom of the main distillation column, and the heat source of the reboiler 51 of the splitter 50 is the side line reflux 30b of the main distillation column. The bottom oil 30e of the distillation column may be arranged as a heat source, or the distillation column 30e from the column side of the main distillation column may be used as a heat source.
c, 30d may be used as a heat source for these reboilers. However, the heating temperature by each reboiler in the stabilizer and splitter in a naphtha rectification system, in other words, the amount of heat required for the reboiler, varies depending on the throughput of LPG/naphtha fraction supplied to the stabilizer and splitter, and is not necessarily constant. Not. The throughput of the stabilizer or splitter depends mainly on the distillation performance of the pre-distillation column and the main distillation column, especially the top yield and fractionation degree of the pre-distillation column. The amount of LPG and naphtha fraction to be processed also changes, and if the amount to be processed is reduced, the amount of heat required for the stabilizer and splitter reboiler will also be reduced. On the other hand, the degree of rectification in the pre-distillation column changes depending on the crude oil type and the preheating temperature of the crude oil supplied to the pre-distillation column, and as a result of this change, the fraction at the top of the pre-distillation column and the top fraction of the main distillation column are Since the yield and composition of the
As shown in the figure, it is not always appropriate to mix the two and send them to the naphtha rectification system in order to reduce the throughput in the stabilizer and splitter. In some cases, it is desirable to supply the stabilizer to the stabilizer or splitter in order to reduce the throughput of the stabilizer or splitter. The conventional naphtha rectification system (Figure 11) described above is
It is configured only when the top fraction of the pre-distillation column and the top fraction of the main distillation column are mixed and then sent to the stabilizer, and depending on the change in the degree of rectification in the pre-distillation column, processing is performed in the stabilizer or splitter. There is a drawback in that it is not possible to minimize the amount of heat required for the reboiler of the stabilizer and splitter by selecting the optimal configuration of the naphtha rectification system that can minimize the amount of naphtha. <Problems to be Solved by the Invention> Therefore, the present invention aims to improve the naphtha rectification system in accordance with changes in the distillation performance of the pre-distillation column and the main distillation column in the conventional crude oil atmospheric distillation apparatus as described above. By selecting the optimal configuration of the naphtha rectification system according to the throughput of LPG/naphtha fraction to be processed and changes in its composition, the throughput of the stabilizer and splitter can be adjusted, and the throughput of the stabilizer and splitter can be adjusted. The purpose of the present invention is to provide a crude oil atmospheric distillation apparatus that can reduce the amount of heat required for the reboiler to the necessary minimum, and that can save energy as a whole by directing the surplus heat of the reboiler heat source to other heat recovery systems. This was done as a. <Means for Solving the Problems> In order to achieve the above object, the present inventors first solved the problem in the case where the degree of rectification in the pre-distillation column fluctuates due to changes in the type of crude oil or operating conditions. For each of these, we investigated the optimal configuration of a naphtha rectification system that can minimize the amount of heat required by the stabilizer and splitter reboilers. If we talk about the degree of rectification of the pre-distillation column here, the degree of rectification of the pre-distillation column is generally determined by the number of trays and internal reflux amount of the distillation column, and the number of trays is determined at the time of construction of the column. Therefore, it can be said that the internal recirculation amount is the operational condition that affects the degree of rectification. This internal reflux amount is
Three elements: (i) the amount of heat brought in by the supplied crude oil (the amount of preheating in the crude oil preheating system), (ii) the ratio of the amount of distillate extracted from the top to the amount of crude oil supplied, and (iii) the amount of heat removed by condensers, side wire reflux, etc. Determined by To explain the degree of rectification in the pre-distillation column using an example, for example, crude oil type A as shown in Figure 2.
(LPG/naphtha fraction is 19.9vol% of crude oil)
A pre-distillation column is assumed to be designed to mildly (coarsely) rectify a portion of the naphtha fraction (11 vol% relative to crude oil) and extract it as a pre-distillation column overhead fraction. In this case, a portion of the LPG fraction will be mixed in the pre-distillation tower bottom residual oil. When the same amount of crude oil type B (LPG/naphtha fraction is 9.3 vol% of crude oil) as shown in Fig. 3 is processed in such a pre-distillation column, the amount of LPG/naphtha fraction is small and the top of the column is The amount of extraction is also reduced (top fraction: 5 vol% of crude oil), and if the condenser capacity is maintained at the same level, the internal reflux will be relatively increased and the degree of rectification will be improved, as shown in Figure 3. This enables rectification in which no LPG fraction is present in the bottom oil of the pre-distillation column. Furthermore, as shown in Figure 4, if the amount withdrawn from the top of the tower is reduced (top fraction:
3 vol% relative to crude oil), the degree of rectification is further improved, and it is also possible to prevent heavy naphtha fraction from being mixed in the overhead fraction. As mentioned above, the present inventors have discovered that when the degree of rectification of the pre-distillation column changes depending on the crude oil type and operating conditions, the composition of the top fraction and bottom oil of the pre-distillation column and the main distillation column changes. In the case of a specific pre-distillation column fractionation degree, the required heat amount of the stabilizer and splitter reboiler can be reduced by configuring a specific naphtha rectification system accordingly. I found out that it works. The rectification degree of the pre-distillation column and the corresponding optimal naphtha rectification system configuration are listed below. In any case, the pre-distillation column bottom residue is further heated through a heat recovery system heat exchanger and a heating furnace as in the conventional case, and then supplied to the main distillation column. (1) Rectification degree of pre-distillation column When an LPG fraction and a part of light naphtha fraction are obtained from the top of the column, and a relatively large amount of LPG fraction is present in the bottom oil. Naphtha rectification system configuration 60 (Figure 5) Main distillation column overhead fraction 30f is directly fed to the splitter 5
A heavy naphtha product is obtained from the bottom of the splitter column. The light naphtha fraction obtained from the top of the splitter column contains an LPG fraction that exceeds the allowable amount of light naphtha products, so it cannot be used as a light naphtha product as it is, so it is combined with the top fraction of the pre-distillation column 20f. LPG is obtained from the top of the stabilizer column and a light naphtha product is obtained from the bottom of the column. This configuration reduces the throughput of both the splitter and stabilizer compared to the conventional configuration (Fig. 11), and as a result, each reboiler 5
1.41 (not shown in FIG. 5) can be reduced. (2) Rectification degree of pre-distillation column The rectification degree is better than the above, and from the top of the column
When an LPG fraction and a part of a light naphtha fraction are obtained, and only a relatively small amount of LPG fraction is present in the column bottom residue. Structure of naphtha rectification system 60 (Figure 6) Main distillation column top fraction 30f is directly fed to splitter 5
A heavy naphtha product is obtained from the bottom of the splitter column, and a light naphtha product is obtained from the top of the column. The light naphtha fraction from the top of the splitter column does not contain enough LPG fraction to exceed the allowable amount of light naphtha products, so it can be used as a light naphtha product as is. On the other hand, the pre-distillation column top fraction 20f is supplied to the stabilizer 40 to obtain LPG from the top of the column, and the light naphtha fraction obtained from the bottom of the column is combined with the light naphtha from the top of the splitter column to produce a light naphtha product. With this configuration, the throughput of both the splitter and stabilizer is reduced compared to the conventional configuration (Fig. 11), and as a result, each reboiler 5
1.41 (not shown in FIG. 6) can be reduced. (3) Rectification degree of pre-distillation column LPG fraction, light naphtha fraction, and part of heavy naphtha fraction are obtained from the top of the column, and a relatively large amount of light naphtha fraction is contained in the bottom oil. If there. Configuration 60 of naphtha rectification system (Figure 7) Pre-distillation column top fraction 20f is transferred to stabilizer 40
LPG is obtained from the top of the stabilizer column, and naphtha (light + heavy) fraction is obtained from the bottom of the column. The heavy naphtha fraction 30f obtained from the top of the main distillation column contains a light naphtha fraction that exceeds the allowable amount of heavy naphtha products, so it cannot be converted into a heavy naphtha product as it is. It is supplied together with the fraction to a splitter 50, and a light naphtha product is obtained from the top of the splitter column, and a heavy naphtha product is obtained from the bottom of the column. With this configuration, the throughput of the stabilizer 40 is reduced compared to the conventional configuration (FIG. 11), and as a result, the amount of heat required by the stabilizer reboiler 41 (not shown in FIG. 7) can be reduced. (4) Rectification degree of pre-distillation column The rectification degree is better than the above, and from the top of the column
When an LPG fraction, a light naphtha fraction, and a part of the heavy naphtha fraction are obtained, and only a relatively small amount of the light naphtha fraction is present in the column bottom residue. Configuration 60 of naphtha rectification system (Figure 8) Pre-distillation column top fraction 20f is transferred to stabilizer 40
LPG is obtained from the top of the stabilizer column, and naphtha (light + heavy) fraction is obtained from the bottom of the column. supplying the stabilizer tower bottom fraction to the splitter 50;
A light naphtha product is obtained from the top of the column, and a heavy naphtha product is obtained from the bottom of the column. The heavy naphtha fraction 30f obtained from the top of the main distillation column does not contain enough light naphtha fraction to exceed the allowable amount of heavy naphtha products, so it is directly combined with the splitter column bottom fraction to create a heavy naphtha fraction. It is a quality naphtha product. With this configuration, the throughput of both the splitter and stabilizer is reduced compared to the conventional configuration (Fig. 11), and as a result, each reboiler 5
1.41 (not shown in FIG. 8) can be reduced. (5) Rectification degree of the pre-distillation column The light naphtha fraction and the heavy naphtha fraction can be separated with a high degree of rectification. Therefore, the LPG fraction and the light naphtha fraction are obtained from the top of the column, and the residue at the bottom of the column is When the oil contains substantially no light naphtha fraction. Configuration 60 of the naphtha rectification system (Figure 9) Pre-distillation column top fraction 20f is transferred to the stabilizer 40
LPG is obtained from the top of the stabilizer column and light naphtha product is obtained from the bottom of the column. Since the main distillation column overhead fraction 30f is substantially only a heavy naphtha fraction, it is directly used as a heavy naphtha product. With this configuration, the splitter 50 becomes unnecessary, and the heat amount of the reboiler 51 of the splitter becomes completely unnecessary. Furthermore, the throughput of the stabilizer 40 is also reduced compared to the conventional configuration (FIG. 11), and as a result, the amount of heat required by the stabilizer reboiler 41 (not shown in FIG. 9) can be reduced. Among the above naphtha rectification system configurations, considering the properties of crude oil currently being processed in Japan and the capacity of the existing pre-distillation column installed in response to it, when modifying the existing distillation equipment, etc. , configuration may not necessarily be necessary. However, in any case, the above configurations ~ are individual naphtha rectification system configurations that are adopted depending on the rectification degree of each pre-distillation column, and assuming the rectification degree of any one pre-distillation column, If one optimal naphtha rectification system configuration corresponding to this is determined and the equipment is designed, when processing other types of crude oil with different product compositions, the optimal naphtha rectification system configuration should be selected for each condition. I can't. Therefore, the present invention makes it possible to select and adopt an optimal naphtha rectification system configuration in accordance with changes in the distillation conditions of the pre-distillation column as described above. That is, this invention comprises a naphtha rectification system having a pre-distillation column, a main distillation column, a stabilizer and a splitter, and distills the bottom residue of the pre-distillation column in the main distillation column, and distills the column top oil of the pre-distillation column. In a petroleum distillation apparatus for obtaining LPG, light naphtha, and heavy naphtha by treating the fraction and the top fraction of the main distillation column in a naphtha rectification system, an inlet pipe to the stabilizer is connected to the naphtha rectification system; An inlet pipe to the splitter, a pipe that leads the stabilizer top fraction to the LPG takeoff pipe, a pipe that selectively leads the stabilizer bottom fraction to the light naphtha takeoff pipe or the splitter inlet pipe, and a pipe that leads the stabilizer top fraction to the light naphtha takeoff pipe or the splitter inlet pipe, and Piping that selectively leads the stabilizer inlet pipe or the light naphtha take-out pipe; and piping that leads the splitter bottom fraction to the heavy naphtha take-out pipe;
The present invention is characterized in that a pipe for guiding the pre-distillation column top fraction to the stabilizer introduction pipe and a pipe for leading the main distillation column top fraction to the splitter introduction pipe are provided. According to the above-described invention, the configurations of the naphtha rectification system can be selectively adopted, but the configuration cannot be selectively adopted. In order to be able to selectively adopt the above-mentioned configurations, select the piping that leads the main distillation column overhead fraction to the splitter inlet pipe, and select the piping that leads the main distillation column overhead fraction to the splitter inlet pipe or the heavy naphtha take-off pipe. The piping may be designed to guide the <Examples> Examples of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a drawing conceptually showing a distillation apparatus of the present invention consisting of a naphtha rectification system 60 having a pre-distillation column 20, a main distillation column 30, a stabilizer 40 and a splitter 50, and a heat recovery system heat exchanger group. , the heating furnace, the stabilizer, the reboiler of the splitter, the distillation pipes and side line reflux routes of each distillation column, and their piping, etc., are substantially the same as the conventional apparatus shown in Figs. 10 and 11, so illustrations are omitted. , or the same reference numerals as in FIGS. 10 and 11 are used to omit the explanation. The crude oil preheated by a heat recovery system heat exchanger group (not shown) is introduced into the pre-distillation column 20 and is separated into a pre-distillation column top fraction and a column bottom residue, and the pre-distillation column bottom residue is It is supplied to the main distillation column 30 via a group of heat exchangers and a heating furnace (none of which are shown). The top fraction of the pre-distillation column 20 passes through a condenser 21, a top receiving tank 22, and a pump 23, and is led to a stabilizer 40 by a pipe 1. Similarly, the top fraction of the main distillation column 30 is handled by a condenser 31, a top receiving tank 32, and a pump 3.
3 and is led to a splitter 50 by a pipe 2 having a valve V2. The stabilizer tower top fraction is taken out as LPG from the pipe 3 via the tower top reflux path F1. The splitter top fraction is taken out as a light naphtha product through the top reflux system route F2 through a pipe 4 having a valve V4, or is merged into a pipe 1 from upstream of the valve V4 through a pipe 5 having a valve V5. Ru. The splitter bottom fraction is taken out from pipe 6 as a heavy naphtha product. The stabilizer bottom fraction is joined to the line 4 downstream of the valve V4 by a line 7 with a valve V7 or to the line 2 downstream of the valve V2 by a line 8 with a valve V8. The main distillation column overhead fraction can also be led from line 2 upstream of valve V2 to line 6 by line 9 with valve V9. Note that the pipe 10 that connects the upstream of the valve V2 of the pipe 2 and the pipe 1 via the valve V10 is for providing the conventional naphtha rectification system configuration shown in FIG. Not necessary. By using the piping system and valve switching as described above,
The configuration of the naphtha rectification system described above can be selected. That is, in the case of the configuration (Fig. 5) Valves to open: V2, V5, V7 Valves to close: V4, V8, V9, V10 In the case of the configuration (Fig. 6) Valves to open: V2, V4 , V7 Valve to close: V5, V8, V9, V10 configuration (Figure 7) Valve to open: V2, V4, V8 Valve to close: V5, V7, V9, V10 configuration (Figure 8) ) Valve to open: V4, V8, V9 Valve to close: V2, V5, V7, V10 In case of configuration (Figure 9) Valve to open: V7, V9, Valve to close: V2 ,V4,V5,V8,V
10. In the case of using the conventional naphtha rectification system configuration as shown in FIG. 11, valves V8, V10, and V4 may be opened, and valves V2, V5, V7, and V9 may be closed. By selecting and adopting the configuration of the naphtha rectification system according to the degree of rectification of the pre-distillation column as described above, it is possible to reduce the throughput in the stabilizer and splitter and the amount of heat required for the reboiler. The reboiler heat source for the stabilizer and splitter is obtained from the side line reflux of the main distillation column or the bottom oil, as in the conventional naphtha rectification system (FIG. 11). 5
2 and temperature control TC-like configuration,
By employing this invention, surplus heat resulting from reduction of the reboiler heat source can be directed to the heat recovery system heat exchanger group. In the above embodiment, configurations ~ of the naphtha rectification system can be selectively adopted, but for the reasons mentioned above, only configurations ~ can be selectively adopted. In this case, the piping 9 and Valve V9 becomes unnecessary. Now, regarding the top of the main distillation column, as shown in FIG. gas and liquid are separated,
Part or all of it is extracted as an overhead product. Generally, the degree of condensation of the top vapor in the condenser 31 is determined by the composition, temperature, pressure, and condenser capacity of the vapor, but if pressure is taken as a parameter, the higher the pressure, the higher the dew point of the top vapor and the condensate. Both boiling point temperatures become higher, and when only part of the top vapor is condensed, the amount of condensed liquid increases. In addition, the refrigerant used in the condenser 31 is generally air or cooling water, which are easily available and inexpensive, used alone or in combination. The effective temperature difference with the refrigerant is reduced. From the above viewpoint, the operating pressure of the main distillation column 30 including the column top receiving tank 32 is usually determined by considering the following two factors. (i) When condensing only a portion of the overhead vapor,
Ensuring the yield and properties of the fraction to be recovered as an overhead product. (ii) Ensuring condenser capacity against fluctuations in the effective temperature difference between the condensed steam side and the condensed steam side caused by seasonal changes in the refrigerant supply temperature for the condenser. However, in the case where the main distillation column 30 is not equipped with the pre-distillation column 20, the vapor in the main distillation column contains moisture, and if this condenses in the column, it causes corrosion in the column. In addition to factors (i) and (ii), taking into consideration prevention of corrosion in the column due to water condensation, the operating pressure of the main distillation column is usually set at a pressure of 0.5 kg/cm ² G or more at the top of the column. However, when installing the pre-distillation column 20 upstream of the main distillation column 30 as in the apparatus of the above embodiment, some of the light components in the crude oil are removed by the pre-distillation column. When the main distillation column is operated under the above-mentioned pressure as in the case where the main distillation column is not installed, there is a tendency for the temperature of the top vapor of the main distillation column to become relatively high. Therefore, in this invention in which a pre-distillation column is installed, even if the operating pressure of the main distillation column is relatively low, it is possible to maintain the temperature level of the vapor at the top of the main distillation column at the same level as when the pre-distillation column is not installed. can. Specifically, it is possible to reduce the main distillation column operating pressure to a minimum of 0.1 Kg/cm ² G at the column top pressure, taking into account the pressure loss of the condenser. At such a pressure, the overhead fraction can be discharged due to the internal pressure of the main distillation column. The main distillation column operating pressure can be adjusted, for example, by pressure regulating means between the top receiving tank 32 of the main distillation column 30 and the valve 35 of the gas venting pipe 34 in FIG.
This can be done using a PC. By operating the main distillation column at a relatively low operating pressure as described above, the non-volatility increases and the distillation effect increases, so the amount of heating required for distillation can be reduced, and therefore the main distillation It becomes possible to reduce the load on the heating furnace of the tower. <Effects of the Invention> As explained above, according to the present invention, an optimal naphtha rectification can be achieved in which the amount of treatment in the stabilizer and splitter of the naphtha rectification system can be minimized according to the degree of rectification in the pre-distillation column. The system configuration can be selected, thereby minimizing the required heat source for the stabilizer and splitter reboilers. As a result, it becomes possible to allocate the surplus heat of the reboiler heat source to, for example, crude oil preheating, thereby making it possible to further reduce the heating furnace load on the main distillation column. The effects of this invention will be specifically explained below with reference to experimental examples. Experimental example: In a crude oil atmospheric distillation apparatus with a capacity of 100,000 BPSD (barrel/day), which is equipped with a pre-distillation column, a main distillation column, and a naphtha rectification system, Middle Eastern crude oil is processed at 100,000 BPSD, and the naphtha rectification system is as shown in Figure 1. Regarding the case where the apparatus of this invention is used to adopt the optimal naphtha rectification system configuration depending on the degree of rectification of the pre-distillation column, and the case where the conventional naphtha rectification system (Fig. 11) is used. Comparing the throughput of the stabilizer and splitter and the reboiler heat amount, we calculated the reduction in reboiler heat amount and the associated main distillation column heating furnace fuel reduction benefit, and the increase in heat exchanger construction cost due to the increase in the required heat transfer area due to the increase in the amount of heat recovered in the crude oil preheating system. I asked for The results are shown in the table below. From this table, it can be seen that even if the heat exchanger construction cost increases by up to 44 million yen by adopting this invention and the profit from main distillation column heating furnace fuel reduction is the minimum of 101 million yen/year, the savings will be made against the increased equipment cost. It is recognized that the energy effect is sufficiently exerted.

【table】

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an embodiment of the distillation apparatus of the present invention; Figs. 2, 3, and 4 are explanatory diagrams showing examples of the degree of rectification of the pre-distillation column; Figs. 5 and 6. , 7th
Figures 8 and 9 are explanatory diagrams individually showing the degree of rectification in the pre-distillation column and the configuration of the optimal naphtha rectification system corresponding thereto; Figures 10 and 11 are explanatory diagrams showing conventional distillation equipment. It is a diagram. 1 to 10... Piping, 20... Pre-distillation column, 30... Main distillation column, 40... Stabilizer, 50... Splitter,
60... Naphtha rectification system.

Claims (1)

[Scope of Claims] 1. A naphtha rectification system having a pre-distillation column, a main distillation column, and a stabilizer and a splitter, in which the bottom residue of the pre-distillation column is distilled in the main distillation column, and the column of the pre-distillation column is In a petroleum distillation apparatus in which the top fraction and the top fraction of the main distillation column are processed in a naphtha rectification system to obtain LPG, light naphtha, and heavy naphtha, an inlet pipe to the stabilizer is connected to the naphtha rectification system. , the inlet pipe to the splitter, and the stabilizer tower overhead distillate to LPG.
A pipe leading to the take-out pipe, a pipe selectively leading the stabilizer bottom fraction to the light naphtha take-off pipe or the splitter introduction pipe, and a pipe selectively leading the splitter top fraction to the stabilizer lead-in pipe or the light naphtha take-out pipe. a pipe that leads the splitter bottom fraction to the heavy naphtha take-off pipe, a pipe that leads the pre-distillation column top fraction to the stabilizer introduction pipe, and a pipe that leads the main distillation column top fraction to the splitter introduction pipe. A petroleum distillation apparatus characterized by being provided with piping leading to a pipe. 2. A patent characterized in that the piping that leads the top fraction of the main distillation column to the splitter introduction pipe is a pipe that selectively leads the top fraction to the splitter introduction pipe or the heavy naphtha take-off pipe. Claim 1
Distillation equipment for petroleum as described in Section 1.