Fractionating tower top gas energy recycling system of diesel oil hydrocracking device

Abstract

The utility model belongs to the technical field of energy utilization of diesel hydrocracking units, and particularly relates to an overhead gas energy recycling system for a fractionating tower of a diesel hydrocracking unit, which comprises a fractionating tower, a tower top gas phase line is led out from the tower top of the fractionating tower, a material discharge line is arranged at the tower bottom, and the outer wall of one side of the fractionating tower is connected through a feed line; a tower top reflux tank is arranged on the other side of the fractionating tower; a hot water heat exchanger is arranged between the top of the fractionating tower and a tower top reflux tank; the bottom of the tower top reflux tank is connected into a fractionating tower top naphtha system through a pipeline; the system utilizes hot water to take heat to solve the problem of heat utilization of tower top gas of the fractionating tower, so that the purposes of reducing cost and improving efficiency are achieved, and the utilization efficiency is 75%; and the naphtha amount can be adjusted according to the production and operation requirements, and the hot water production amount can be flexibly adjusted to 340-2000 t / h.

Description

Technical Field

[0001] The utility model belongs to the technical field of energy utilization of diesel hydrocracking devices, and specifically relates to an energy recovery and utilization system for overhead gas of a fractionation tower of a diesel hydrocracking device. Background Art

[0002] In the existing diesel hydrocracking unit energy utilization technology field, the process flow adopts the method of cooling the top gas of the distillation tower by air cooling and then entering the reflux tank. The problem is that direct air cooling not only consumes electricity, but also fails to recycle energy, thus causing a large amount of capacity loss; therefore, how to effectively utilize the heat of the top of the distillation tower of the diesel hydrocracking unit and reduce the energy consumption of the unit is an important means for refineries to improve economic benefits. Utility Model Content

[0003] In view of the above problems, the purpose of the utility model is to provide a diesel hydrocracking unit fractionation tower top gas energy recovery and utilization system, which uses hot water to obtain heat to solve the problem of heat utilization of the fractionation tower top gas, thereby achieving the purpose of reducing costs and increasing efficiency.

[0004] In order to achieve the above-mentioned purpose, the technical scheme adopted by the utility model is: a diesel hydrocracking unit fractionation tower top gas energy recovery and utilization system, comprising: a fractionation tower, the top gas phase line is drawn out from the top of the fractionation tower, a material discharge line is arranged at the bottom of the tower, the outer wall of one side of the fractionation tower is connected through a feed line, and a top reflux tank is arranged at the other side of the fractionation tower; a hot water heat exchanger is arranged between the top of the fractionation tower and the top reflux tank, and the bottom of the top reflux tank is connected to the naphtha system at the top of the fractionation tower through a pipeline;

[0005] Furthermore, one side of the shell of the hot water heat exchanger is connected via a gas phase line at the top of the distillation tower, and a lead-out line at the other side of the shell is connected to the top of a reflux tank at the top of the tower;

[0006] Furthermore, the pipes of the hot water heat exchanger are connected by an inlet pipe and an outlet pipe respectively; the inlet pipe is led out from the system waste heat recovery station, and the outlet pipe is connected to the system waste heat recovery station; thus forming a cycle;

[0007] Furthermore, a gate valve is provided on the water inlet pipeline from the system waste heat recovery station to the hot water heat exchanger to control the water supply from the system waste heat recovery station to the hot water heat exchanger;

[0008] Furthermore, a pneumatic valve is provided on the water outlet pipeline from the hot water heat exchanger to the waste heat system recovery station, which is used to control the water after heat exchange in the hot water heat exchanger to enter the system waste heat recovery station;

[0009] The water passed through the hot water heat exchanger is sent to the demand unit through the system waste heat recovery station; the utility model sends the water after heat exchange to the seawater desalination device through the system waste heat recovery station for seawater desalination;

[0010] Furthermore, the inlet water temperature provided from the waste heat system recovery station to the hot water heat exchanger is set to 75°C; the water temperature flowing from the hot water heat exchanger to the waste heat system recovery station is 95°C, and the hot water volume is 340-2000t / h;

[0011] Furthermore, the distillation tower top gas flow rate is 200-400 t / h, the temperature is 130-180° C., and the pressure is 0.09-0.15 MPa.

[0012] In the above technical scheme, the top gas is extracted from the top of the fractionation tower, and the top gas enters the hot water heat exchanger through the top gas phase line; by opening the gate valve of the hot water heat exchanger water inlet pipeline, the 75°C low-temperature hot water from the system waste heat recovery station enters, the top gas passes through the hot water heat exchanger and exchanges heat with the 75°C hot water to produce 95°C hot water, and after passing through the top gas hot water heat exchanger, the temperature is 75-85°C and then sent to the top reflux tank; by opening the pneumatic valve on the hot water heat exchanger outlet pipeline, the 95°C high-temperature hot water of the hot water heat exchanger is returned to the system waste heat recovery station;

[0013] After the top gas of the distillation tower is heat-exchanged by the water heater, the pressure of the top gas is 0.06-0.1MPa;

[0014] In the above process, the temperature of the 75°C hot water from the system waste heat recovery station is controlled by a seawater desalination device.

[0015] Furthermore, the bottom of the tower top reflux tank is connected to two distillation tower bottom pumps in opposite directions through a pipeline, and the pump outlet pipelines of the two distillation tower bottom pumps are respectively connected to the distillation tower top naphtha system and the distillation tower; the gas-liquid mixture after heat exchange between the high-temperature gas of the distillation tower and the hot water of the hot water heat exchanger enters the tower top reflux tank, and the hot water produced after the heat exchange enters the waste heat system recovery station. At the same time, the heat exchange also cools the tower top gas, and the tower top gas after cooling meets the downstream process requirements; a part of the liquid coming out of the tower top reflux tank is pumped to the distillation tower top naphtha system through a distillation tower bottom pump, and the other part of the liquid is pumped back to the distillation tower through another distillation tower bottom pump;

[0016] Furthermore, a fractionation tower bottom pump is also provided on the material discharge line at the bottom of the fractionation tower, and the material is pumped to the fractionation tower bottom oil through the fractionation tower bottom pump.

[0017] The beneficial effects of adopting the above technical solution are:

[0018] Hot water is used to obtain heat to solve the problem of heat utilization of the distillation tower top gas, thereby achieving the goal of reducing costs and increasing efficiency, with an efficiency of 75%; the ability to adjust the amount of naphtha according to production and operation needs, and the hot water production can be flexibly adjusted between 340-2000t / h. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural diagram of the utility model.

[0020] In the figure, 1, distillation tower, 2, top gas phase line, 3, material discharge line, 4, feed line, 5, top reflux tank, 6, hot water heat exchanger, 7, water inlet pipeline, 8, water outlet pipeline, 9, system waste heat recovery station, 10, gate valve, 11, pneumatic valve, 12, distillation tower bottom pump. DETAILED DESCRIPTION

[0021] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the utility model. However, the utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the utility model, so the utility model is not limited by the specific embodiments disclosed below.

[0022] like Figure 1 A diesel hydrocracking unit fractionation tower overhead gas energy recovery and utilization system is shown, comprising: a fractionation tower 1, a tower top gas phase line 2 is drawn out from the tower top of the fractionation tower 1, a material discharge line 3 is arranged at the tower bottom, an outer wall of one side of the fractionation tower 1 is connected via a feed line 4, and a tower top reflux tank 5 is arranged at the other side of the fractionation tower 1; a hot water heat exchanger 6 is arranged between the tower top of the fractionation tower 1 and the tower top reflux tank 5, and the bottom of the tower top reflux tank 5 is connected to the naphtha system at the top of the fractionation tower via a pipeline;

[0023] One side of the shell of the hot water heat exchanger 6 is connected to the top gas phase line 2 of the distillation tower 1, and the other side of the shell leads to the top of the tower top reflux tank 5 through the pipeline;

[0024] The pipes of the hot water heat exchanger 6 are connected by an inlet pipe 7 and an outlet pipe 8 respectively; the inlet pipe 7 is led out from the system waste heat recovery station 9, and the outlet pipe 8 is connected to the system waste heat recovery station 9; thus forming a cycle;

[0025] Furthermore, a gate valve 10 is provided on the water inlet pipeline 7 from the system waste heat recovery station 9 to the hot water heat exchanger 6, for controlling the water supply from the system waste heat recovery station 9 to the hot water heat exchanger 6;

[0026] A pneumatic valve 11 is provided on the water outlet pipeline 8 from the hot water heat exchanger 6 to the waste heat system recovery station 9, which is used to control the water after heat exchange in the hot water heat exchanger 6 to enter the system waste heat recovery station 9;

[0027] The water passed through the hot water heat exchanger 6 is sent to the demand unit through the system waste heat recovery station 9; the utility model sends the water after heat exchange through the system waste heat recovery station 9 to the seawater desalination device for seawater desalination;

[0028] The water inlet temperature from the waste heat system recovery station 9 to the hot water heat exchanger 6 is set to 75°C, the water inlet pressure is 0.8MPa, and the flow rate is determined by the size of the designed pipe, generally 1~1.5m / s; the water temperature flowing from the hot water heat exchanger 6 to the waste heat system recovery station 9 is 95°C, and the hot water volume is 340-2000t / h;

[0029] The top gas flow rate of the fractionation tower 1 is 200-400 t / h, the temperature is 130-180° C., and the pressure is 0.09-0.15 MPa.

[0030] In the above technical scheme, the top gas is extracted from the top of the fractionation tower 1, and the top gas enters the hot water heat exchanger 6 through the top gas phase line 2; by opening the gate valve 10 of the water inlet pipeline 7 of the hot water heat exchanger 6, the 75°C low-temperature hot water from the system waste heat recovery station 9 enters, and the top gas passes through the hot water heat exchanger 6 and exchanges heat with the 75°C hot water to produce 95°C hot water, and after passing through the top gas hot water heat exchanger 6, the temperature is 75-85°C and then sent to the top reflux tank 5; by opening the pneumatic valve 12 on the water outlet pipeline 8 of the hot water heat exchanger 6, the 95°C high-temperature hot water of the hot water heat exchanger 6 is returned to the system waste heat recovery station 9;

[0031] After the top gas of the fractionation tower 1 is heat exchanged by the water heater 6, the pressure of the top gas is 0.06-0.1MPa;

[0032] The bottom of the tower top reflux tank 5 is connected to two distillation tower bottom pumps 12 in opposite directions through a pipeline, and the pump outlet pipelines of the two distillation tower bottom pumps 12 are respectively connected to the distillation tower top naphtha system and the distillation tower 1; the gas-liquid mixture after the high-temperature gas of the distillation tower 1 and the hot water heat exchanger 6 heat exchange enters the tower top reflux tank 5, and the hot water produced after the heat exchange enters the waste heat system recovery station 9. At the same time, the heat exchange also cools the tower top gas, and the tower top gas after cooling meets the downstream process requirements; a part of the liquid coming out of the tower top reflux tank 5 is pumped to the distillation tower top naphtha system through a distillation tower bottom pump 12, and the other part of the liquid is pumped back to the distillation tower 1 through another distillation tower bottom pump 12;

[0033] A fractionation tower bottom pump 12 is also provided on the material discharge line 3 at the bottom of the fractionation tower 1, and the material is pumped to the fractionation tower bottom oil through the fractionation tower bottom pump 12.

[0034] This scheme makes full use of the heat of the overhead gas of the distillation tower and the feature of adjusting the amount of naphtha according to production and operation needs. The amount of hot water produced can be flexibly adjusted between 340-2000t / h.

[0035] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0036] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0037] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0039] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

Claims

1. A diesel hydrocracking unit fractionation tower overhead gas energy recovery and utilization system, characterized in that: include: A distillation tower, wherein a top gas phase line is led out from the top of the distillation tower, a material discharge line is arranged at the bottom of the tower, an outer wall on one side of the distillation tower is connected through a feed line, and a top reflux tank is arranged on the other side of the distillation tower; a hot water heat exchanger is arranged between the top of the distillation tower and the top reflux tank, and the bottom of the top reflux tank is connected to the naphtha system at the top of the distillation tower through a pipeline.

2. The diesel hydrocracking unit fractionation tower overhead gas energy recovery and utilization system according to claim 1, characterized in that: One side of the shell of the hot water heat exchanger is connected through the tower top gas phase line of the distillation tower, and the other side of the shell leads to the top of the tower top reflux tank through a pipeline.

3. The diesel hydrocracking unit fractionation tower overhead gas energy recovery and utilization system according to claim 1, characterized in that: The pipes of the hot water heat exchanger are connected by an inlet pipe and an outlet pipe respectively; the inlet pipe is led out from the system waste heat recovery station, and the outlet pipe is connected to the system waste heat recovery station; thus forming a cycle.

4. A diesel hydrocracking unit fractionation tower overhead gas energy recovery and utilization system according to claim 3, characterized in that: A gate valve is installed on the water inlet pipeline from the system waste heat recovery station to the hot water heat exchanger.

5. A diesel hydrocracking unit fractionation tower overhead gas energy recovery and utilization system according to claim 3, characterized in that: A pneumatic valve is provided on the water outlet pipeline from the hot water heat exchanger to the waste heat system recovery station.

6. A diesel hydrocracking unit fractionation tower overhead gas energy recovery and utilization system according to claim 3, characterized in that: The water after heat exchange in the hot water heat exchanger is sent to the seawater desalination device through the system waste heat recovery station.

7. A diesel hydrocracking unit fractionation tower overhead gas energy recovery and utilization system according to claim 3, characterized in that: The inlet water temperature provided from the waste heat system recovery station to the hot water heat exchanger is set to 75°C; the water temperature flowing from the hot water heat exchanger to the waste heat system recovery station is 95°C, and the hot water volume is 340-2000t / h.

8. A diesel hydrocracking unit fractionation tower overhead gas energy recovery and utilization system according to claim 6, characterized in that: After the top gas of the distillation tower is heat-exchanged by the water heater, the pressure of the top gas is 0.06-0.1 MPa.

9. A diesel hydrocracking unit fractionation tower overhead gas energy recovery and utilization system according to claim 2, characterized in that: The bottom of the tower top reflux tank is connected to two distillation tower bottom pumps in opposite directions through a pipeline, and the pump outlet pipelines of the two distillation tower bottom pumps are respectively connected to the distillation tower top naphtha system and the distillation tower.

10. The diesel hydrocracking unit fractionation tower overhead gas energy recovery and utilization system according to claim 1, characterized in that: A fractionation tower bottom pump is also provided on the material discharge line at the bottom of the fractionation tower, and the material is pumped to the fractionation tower bottom oil through the fractionation tower bottom pump.

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