Epoxy device low-quality steam balance system and technology

Abstract

The invention relates to the technical field of ethylene glycol production, in particular to an epoxy device low-quality steam balance system and process, the epoxy device low-quality steam balance system comprises an epoxy device and an ethylene glycol device, the ethylene glycol device comprises a first-effect evaporation tower, a second-effect evaporation tower, a pre-dehydration tower and a dehydration tower which are connected in sequence, and the system further comprises a first reboiler, a second reboiler and a third reboiler, the tube pass of the second reboiler is connected with the second-effect evaporation tower, and the shell pass of the second reboiler is connected with the tower top of the first-effect evaporation tower; the tube pass of the reboiler III is connected with the pre-dehydration tower, and the shell pass of the reboiler III is connected with the tower top of the second-effect evaporation tower; the tube pass of the reboiler IV is connected with the dehydrating tower; the condensate tank is connected with shell pass outlets of the reboiler II and the reboiler III; the non-condensable gas main pipe is connected with the reboiler I, the reboiler II, the reboiler III and the reboiler IV; the ice machine set is connected with the epoxy device and is connected with the non-condensable gas header pipe and the tower top of the pre-dehydration tower, and the low-quality steam structure is effectively adjusted, so that the effects of reducing cost and improving efficiency are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of ethylene glycol production, and particularly to a low-quality steam balance system and process for an epoxy unit. Background Art

[0002] In the production process of the ethylene glycol plant, the steam energy consumption accounts for the largest proportion. With the increasing tension of global energy resources, reducing energy consumption and improving energy utilization efficiency have become the focus of attention in various industries. As an important chemical raw material, the steam energy consumption problem in the production process of ethylene glycol is particularly prominent. First of all, the production process of ethylene glycol is complex, involving multiple chemical reactions and physical change processes. In these processes, steam, as an important medium and reaction condition, plays a key role. However, due to the influence of factors such as production equipment, technical level and operation management, the steam energy consumption of ethylene glycol is generally high. Secondly, from the perspective of energy consumption, the steam energy consumption in the production process of ethylene glycol mainly comes from links such as heating, evaporation and condensation. These links require a large amount of heat energy to drive, and the heat energy mainly comes from energy sources such as burning fossil fuels. Therefore, reducing the steam energy consumption of ethylene glycol can not only improve the economic benefits of enterprises, but also help to reduce energy consumption and environmental pollution. In addition, the demand in the ethylene glycol market is constantly growing, resulting in the continuous expansion of the production scale. However, with the expansion of the production scale, the steam energy consumption problem has become more and more serious. This has brought huge economic pressure to enterprises and also had an adverse impact on the environment.

[0003] To sum up, the background of ethylene glycol steam energy consumption involves multiple factors such as production process, energy consumption and market demand. In order to reduce energy consumption and improve energy utilization efficiency, enterprises need to take effective measures and methods, such as optimizing the production process, improving equipment technology, strengthening operation management, etc. At the same time, the government and all sectors of society should also pay attention to and support the energy conservation and emission reduction work of the ethylene glycol industry, and jointly promote the sustainable development of the chemical industry. Therefore, there is an urgent need for a balancing method to reduce the steam unit consumption of the ethylene glycol plant and balance the low-quality steam of the unit. Summary of the Invention

[0004] The purpose of the present invention is to provide a low-quality steam balance system and process for an epoxy unit, which has the characteristic of being able to balance the low-quality steam of the ethylene glycol plant.

[0005] The above technical purpose of the present invention is achieved through the following technical solutions: A low-quality steam balance system for an epoxy unit includes an epoxy unit and an ethylene glycol unit. The ethylene glycol unit includes a first-effect evaporation tower, a second-effect evaporation tower, a pre-dehydration tower, and a dehydration tower connected in sequence, and further includes:

[0006] A first reboiler, the tube side of which is connected to the first-effect evaporation tower;

[0007] Reboiler II, whose tube side is connected to the second-effect evaporation tower and whose shell side is connected to the top of the first-effect evaporation tower;

[0008] Reboiler III, whose tube side is connected to the pre-dehydration tower and whose shell side is connected to the top of the second-effect evaporation tower;

[0009] Reboiler IV, whose tube side is connected to the dehydration tower;

[0010] Condensate tank, which is connected to the shell-side outlets of Reboiler II and Reboiler III;

[0011] Non-condensable gas main pipe, which is connected to Reboiler I, Reboiler II, Reboiler III, and Reboiler IV;

[0012] Ice machine unit, which is connected to the epoxy unit and is also connected to the non-condensable gas main pipe and the top of the pre-dehydration tower.

[0013] Preferably, there are 2 sets of the ethylene glycol units, namely 1# ethylene glycol unit and 2# ethylene glycol unit. The 1# ethylene glycol unit includes 1# second-effect evaporation tower and 1# Reboiler III, and the 2# ethylene glycol unit includes 2# second-effect evaporation tower and 2# Reboiler III. It further includes:

[0014] The first interconnection pipeline, one end of which is connected to the pipeline between the 1# second-effect evaporation tower and the 1# Reboiler III, and a gate valve I is arranged at the shell-side inlet of the 1# Reboiler III; the other end is connected to the pipeline between the 2# second-effect evaporation tower and the 2# Reboiler III, and a gate valve II is arranged at the shell-side inlet of the 2# Reboiler III.

[0015] Preferably, the 1# ethylene glycol unit further includes a 1# pre-dehydration tower, and gate valves III and IV are arranged on the pipeline between the 1# pre-dehydration tower and the 1# second-effect evaporation tower. The 2# ethylene glycol unit further includes a 2# pre-dehydration tower, and gate valves V and VI are arranged on the pipeline between the 2# pre-dehydration tower and the 2# second-effect evaporation tower. The system further includes:

[0016] The second interconnection pipeline, one end of which is connected to the pipeline between gate valves III and IV; the other end is connected to the pipeline between gate valves V and VI.

[0017] Preferably, the epoxy unit includes 1# epoxy unit and 2# epoxy unit, and the ice machine unit includes 1# ice machine unit, 2# ice machine unit, and 3# ice machine unit. The top steam of the 1# pre-dehydration tower and the 2# pre-dehydration tower is connected to the 1# ice machine unit, 2# ice machine unit, and 3# ice machine unit. The 1# ice machine unit and the 2# ice machine unit are respectively connected to the 1# epoxy unit and the 2# epoxy unit, and the 3# ice machine unit is connected to the 3# epoxy unit.

[0018] Preferably, each of the ice machine units includes steam ice machine I, steam ice machine II, and an electric ice machine.

[0019] Preferably, the first reboiler, the second reboiler, the third reboiler, and the fourth reboiler are all high-flux reboilers, and the first-effect evaporation tower, the second-effect evaporation tower, the pre-dehydration tower, and the dehydration tower adopt super-efficient trays.

[0020] Preferably, the bottom temperature of the first-effect evaporation tower is 216 °C, the top pressure is 1.9 Mpa, the material from the epoxy unit is heated and concentrated, the concentration of the ethylene glycol aqueous solution at the bottom of the tower is 18%, and it is transported to the second-effect evaporation tower;

[0021] The bottom temperature of the second-effect evaporation tower is 169 °C, the top pressure is 0.5 Mpa, the material from the first-effect evaporation tower is heated and concentrated, the concentration of the ethylene glycol aqueous solution at the bottom of the tower is 48%, and it is transported to the pre-dehydration tower;

[0022] The bottom temperature of the pre-dehydration tower is 146 °C, the top pressure is 0.1 - 0.13 Mpa, the material from the second-effect evaporation tower is heated and concentrated, the concentration of the ethylene glycol aqueous solution at the bottom of the tower is 78%, and it is transported to the dehydration tower. The low-quality steam generated at the top of the pre-dehydration tower is transported to the ice machine unit;

[0023] The bottom temperature of the dehydration tower is 140 °C, the top pressure is 13 Kpa, the material from the pre-dehydration tower is heated and concentrated, the concentration of the ethylene glycol aqueous solution at the bottom of the tower is 93%, and it is transported to the MEG refining unit.

[0024] Preferably, the first reboiler uses steam at 4.0 Mpa from the outside as the heat source, and the generated condensate is directly recovered;

[0025] The second reboiler uses steam at 1.9 Mpa from the top of the first-effect evaporation tower as the heat source. After the generated condensate is transported to the condensate tank, it enters the EG hydration unit;

[0026] The third reboiler uses steam at 0.5 Mpa from the top of the second-effect evaporation tower as the heat source. After the generated condensate is transported to the condensate tank, it enters the EG hydration unit;

[0027] The fourth reboiler uses clean steam at 1.4 Mpa as the heat source, and the generated condensate is directly recovered;

[0028] The non-condensable gases of the first reboiler, the second reboiler, the third reboiler, and the fourth reboiler are discharged to the non-condensable gas main pipe and then transported to the ice machine unit.

[0029] Preferably, when the 1# pre-dehydration tower and the 1# dehydration tower are out of service, the gate valve one and the gate valve four are closed, and the gate valve two and the gate valve six are opened.

[0030] Preferably, when the 2# pre-dehydration tower and the 2# dehydration tower are out of service, the gate valve two and the gate valve six are closed, and the gate valve one and the gate valve four are opened.

[0031] In summary, the present invention has the following beneficial effects: Compared with the existing process, the invention has a small equipment investment, occupies a small space, reduces energy consumption, and optimizes the unit consumption; effectively adjusts the structure of low-quality steam, avoids energy waste, thereby achieving the effect of cost reduction and efficiency improvement, solves the problem of waste of low-quality steam venting in the ethylene glycol plant, and optimizes the use of the ice machine to link the 1# ethylene glycol plant, 2# ethylene glycol plant, 1# epoxy plant, 2# epoxy plant, and 3# epoxy plant, ensuring the achievement of the technical research on steam balance in the ethylene glycol plant during the future continuous growth period, maximizing the benefits, and being able to create tens of millions of yuan of value for the enterprise every year; at the same time, it saves about several million yuan in circulating water, electricity, and steam energy consumption every year. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of the connection relationship of Embodiment 1;

[0033] Figure 2 is a schematic diagram of the ice machine unit in the embodiment;

[0034] Figure 3 is a schematic diagram of the connection relationship of Embodiment 2;

[0035] Figure 4 is Figure 3 an enlarged schematic diagram of part A in;

[0036] Figure 5 is Figure 3 an enlarged schematic diagram of part B in.

[0037] In the figure, 1 is the epoxy unit; 101 is the 1# epoxy unit; 102 is the 2# epoxy unit; 103 is the 3# epoxy unit; 2 is the ethylene glycol unit; 201 is the 1# ethylene glycol unit; 202 is the 2# ethylene glycol unit; 3 is the first-effect evaporation tower; 301 is the 1# first-effect evaporation tower; 302 is the 2# first-effect evaporation tower; 4 is the second-effect evaporation tower; 401 is the 1# second-effect evaporation tower; 402 is the 2# second-effect evaporation tower; 5 is the pre-dehydration tower; 501 is the 1# pre-dehydration tower; 502 is the 2# pre-dehydration tower; 6 is the dehydration tower; 601 is the 1# dehydration tower; 602 is the 2# dehydration tower; 7 is the first reboiler; 701 is the 1# first reboiler; 702 is the 2# first reboiler; 8 is the second reboiler; 801 is the 1# second reboiler; 802 is the 2# second reboiler; 9 is the third reboiler; 901 is the 1# third reboiler; 902 is the 2# third reboiler; 10 is the fourth reboiler; 1001 is the 1# fourth reboiler; 1002 is the 2# fourth reboiler; 11 is the condensate tank; 111 is the 1# condensate tank; 112 is the 2# condensate tank; 12 is the non-condensable gas main pipe; 13 is the ice machine set; 131 is the 1# ice machine set; 132 is the 2# ice machine set; 133 is the 3# ice machine set; 141 is the steam ice machine one; 142 is the steam ice machine two; 15 is the electric ice machine; 16 is the first interconnection pipeline; 161 is the gate valve one; 162 is the gate valve two; 17 is the second interconnection pipeline; 173 is the gate valve three; 174 is the gate valve four; 175 is the gate valve five; 176 is the gate valve six; 18 is the third interconnection pipeline; 19 is the fourth interconnection pipeline; 20 is the ice machine transfer pump. Detailed implementation manners

[0038] The present invention will be further described in detail below with reference to the accompanying drawings.

[0039] This specific embodiment is only an interpretation of the present invention and does not limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

[0040] Embodiment 1:

[0041] As Figure 1 shown, a low-quality steam balance system for an epoxy unit provided by the present invention includes an epoxy unit 1 and an ethylene glycol unit 2. The ethylene glycol unit 2 includes a first-effect evaporation tower 3, a second-effect evaporation tower 4, a pre-dehydration tower 5, and a dehydration tower 6 connected in sequence. It also includes a first reboiler 7, a second reboiler 8, a third reboiler 9, a fourth reboiler 10, a condensate tank 11, and an ice machine set 13. The epoxy unit 1 is connected to the ethylene glycol unit 2 and the ice machine set 13.

[0042] A flow meter and a flow control valve are connected to the shell-side inlet pipeline of the first reboiler 7, and its tube side is connected to the bottom of the first-effect evaporation tower 3.

[0043] The top of the first-effect evaporation tower 3 is connected to a pressure gauge. A flow meter and a flow control valve are installed on the top pipeline and are connected to the shell-side inlet of the second reboiler 8, and the bottom pipeline is connected to the second-effect evaporation tower 4.

[0044] The shell-side inlet of the second reboiler 8 is connected to the top pipeline of the first-effect evaporation tower 3, and the outlet is connected to the condensate tank 11. Its tube-side is connected to the bottom of the second-effect evaporation tower 4.

[0045] The top of the second-effect evaporation tower 4 is connected to a pressure gauge. A flow meter and a flow control valve are installed on the top pipeline and are connected to the shell-side inlet of the third reboiler 9, and the bottom pipeline is connected to the pre-dehydration tower 5.

[0046] The shell-side inlet of the third reboiler 9 is connected to the top of the second-effect evaporation tower 4, and the outlet is connected to the condensate tank 11. Its tube-side is connected to the bottom of the pre-dehydration tower 5.

[0047] The top of the pre-dehydration tower 5 is connected to a pressure gauge. A pressure control valve and a gate valve are installed on the top pipeline and are connected to the ice machine unit 13, and the bottom pipeline is connected to the dehydration tower 6.

[0048] A flow meter and a flow control valve are connected to the shell-side inlet pipeline of the fourth reboiler 10, and its tube-side is connected to the bottom of the dehydration tower 6.

[0049] The top of the dehydration tower 6 is connected to a pressure gauge, and the bottom pipeline is connected to the MEG refining unit.

[0050] The first reboiler 7, the second reboiler 8, the third reboiler 9, and the fourth reboiler 10 are all high-flux reboilers, and the first-effect evaporation tower 3, the second-effect evaporation tower 4, the pre-dehydration tower 5, and the dehydration tower 6 adopt super-efficient trays.

[0051] The outlet of the condensate tank 11 is connected to the subsequent EG hydration device.

[0052] The first reboiler 7, the second reboiler 8, the third reboiler 9, and the fourth reboiler 10 are jointly connected to the non-condensable gas main pipe 12 (the relevant pipelines are not drawn). A gate valve is installed on the non-condensable gas main pipe 12 and is connected to the ice machine unit 13.

[0053] As Figure 2 shown, the ice machine unit 13 includes 3 ice machines, namely the first steam ice machine 141, the second steam ice machine 142, and the electric ice machine 15. Gate valves are installed at both ends of each ice machine. Among them, the first steam ice machine 141 and the second steam ice machine 142 are used to introduce low-quality steam. The first steam ice machine 141, the second steam ice machine 142, and the electric ice machine 15 are connected to users through the ice machine transfer pump.

[0054] Working principle:

[0055] The bottom temperature of the first-effect evaporation tower 3 is 216°C, and the top pressure is 1.9 Mpa. It heats and concentrates the materials from the epoxy unit 1. The concentration of the ethylene glycol aqueous solution at the bottom of the tower is 18%, and it is transported to the second-effect evaporation tower 4.

[0056] The bottom temperature of the second-effect evaporation tower 4 is 169°C, and the top pressure is 0.5 Mpa. It heats and concentrates the materials from the first-effect evaporation tower 3. The concentration of the ethylene glycol aqueous solution at the bottom of the tower is 48%, and it is transported to the pre-dehydration tower 5.

[0057] The bottom temperature of the pre-dehydration tower 5 is 146°C, and the top pressure is 0.1 - 0.13 Mpa. It heats and concentrates the materials from the second-effect evaporation tower 4. The concentration of the ethylene glycol aqueous solution at the bottom of the tower is 78%, and it is transported to the dehydration tower 6. The low-quality steam generated at the top of the pre-dehydration tower 5 is transported to the ice machine unit 13.

[0058] The bottom temperature of the dehydration tower 6 is 140°C, and the top pressure is 13 Kpa. It heats and concentrates the materials from the pre-dehydration tower 5. The concentration of the ethylene glycol aqueous solution at the bottom of the tower is 93%, and it is transported to the MEG refining unit.

[0059] The reboiler one 7 uses the steam with an external pressure of 4.0 Mpa as the heat source, and the generated condensate is directly recycled.

[0060] The reboiler two 8 uses the steam with a pressure of 1.9 Mpa at the top of the first-effect evaporation tower 3 as the heat source. After the generated condensate is transported to the condensate tank 11, it enters the EG hydration unit.

[0061] The reboiler three 9 uses the steam with a pressure of 0.5 Mpa at the top of the second-effect evaporation tower 4 as the heat source. After the generated condensate is transported to the condensate tank 11, it enters the EG hydration unit.

[0062] The reboiler four 10 uses the clean steam with a pressure of 1.4 Mpa as the heat source, and the generated condensate is directly recycled.

[0063] The non-condensable gases of the reboiler one 7, reboiler two 8, reboiler three 9, and reboiler four 10 are discharged to the non-condensable gas main pipe 12 and then transported to the ice machine unit 13.

[0064] Example 2:

[0065] As Figure 3 、 Figure 4 、 Figure 5 shown, this example includes 2 sets of epoxy units and 2 sets of ethylene glycol units. The 2 sets of epoxy units are 1# epoxy unit 101 and 2# epoxy unit 102 respectively; the 2 sets of ethylene glycol units are 1# ethylene glycol unit 201 and 2# ethylene glycol unit 202 respectively.

[0066] The 1# ethylene glycol unit 201 includes a 1# first-effect evaporation tower 301, a 1# second-effect evaporation tower 401, a 1# pre-dehydration tower 501, a 1# dehydration tower 601, a 1# reboiler one 701, a 1# reboiler two 801, a 1# reboiler three 901, a 1# reboiler four 1001, and a 1# condensate tank 111.

[0067] The 2# ethylene glycol unit 202 includes a 2# first-effect evaporation tower 302, a 2# second-effect evaporation tower 402, a 2# pre-dehydration tower 502, a 2# dehydration tower 602, a 2# reboiler one 702, a 2# reboiler two 802, a 2# reboiler three 902, a 2# reboiler four 1002, and a 2# condensate tank 112.

[0068] The connection modes of the towers, reboilers, pipelines, valves, and instruments in each set of ethylene glycol units are as Figure 3 shown, which are the same as those in Embodiment 1. The difference is that a first interconnection pipeline 16 and a second interconnection pipeline 17 are connected between the 1# ethylene glycol unit 201 and the 2# ethylene glycol unit 202.

[0069] One end of the first interconnection pipeline 16 is connected to the pipeline between the 1# second-effect evaporation tower 401 and the 1# reboiler three 901, and a gate valve one 161 is arranged at the shell-side inlet of the 1# reboiler three 901; the other end is connected to the pipeline between the 2# second-effect evaporation tower 402 and the 2# reboiler three 902, and a gate valve two 162 is arranged at the shell-side inlet of the 2# reboiler three 902.

[0070] Gate valves three 173 and four 174 are arranged on the pipeline between the 1# pre-dehydration tower 501 and the 1# second-effect evaporation tower 401, and gate valves five 175 and six 176 are arranged on the pipeline between the 2# pre-dehydration tower 502 and the 2# second-effect evaporation tower 402. One end of the second interconnection pipeline 17 is connected to the pipeline between the gate valves three 173 and four 174; the other end is connected to the pipeline between the gate valves five 175 and six 176.

[0071] In this embodiment, three ice machine sets 13 are provided, including a 1# ice machine set 131, a 2# ice machine set 132, and a 3# ice machine set 133. The top steam of the 1# pre-dehydration tower 501 and the 2# pre-dehydration tower 502 is connected to the 1# ice machine set 131, the 2# ice machine set 132, and the 3# ice machine set 133. The 1# ice machine set 131 and the 2# ice machine set 132 are respectively connected to the 1# epoxy unit 101 and the 2# epoxy unit 102. The 3# ice machine set 133 is additionally connected to a 3# epoxy unit 103 to make full use of the low-quality steam in the unit. A third interconnection pipeline 18 is connected between the outlet pipelines of the 1# ice machine set 131 and the 2# ice machine set 132, and a fourth interconnection pipeline 19 is connected to the pipeline between the 2# ice machine set 132 and the 3# ice machine set 133. Gate valves are installed on both the third interconnection pipeline 18 and the fourth interconnection pipeline 19.

[0072] Working principle:

[0073] The working principle of this embodiment is basically the same as that of Embodiment 1. The difference is that when the producer adjusts the production plan according to the market demand and hopes to reduce the output, the 1# pre-dehydration tower 501 and the 1# dehydration tower 601 can be deactivated, or the 2# pre-dehydration tower 502 and the 2# dehydration tower 602 can be deactivated, so as to achieve the purpose of reducing energy consumption and saving energy.

[0074] When it is necessary to deactivate the 1# pre-dehydration tower 501 and the 1# dehydration tower 601, close the first gate valve 161 and the fourth gate valve 174, and open the second gate valve 162 and the sixth gate valve 176. The low-quality steam generated at the top of the 1# second-effect evaporation tower 401 is sent to the 2# reboiler three 902. The non-condensable gases generated by all reboilers enter the non-condensable gas main pipe 12 and are mixed and then sent to the 1# ice machine set 131, the 2# ice machine set 132, and the 3# ice machine set 133, serving as the heat source for the ice machine set 13 to provide heat removal for the 1# epoxy unit 101, the 2# epoxy unit 102, and the 3# epoxy unit 103. The bottom material of the 1# second-effect evaporation tower 401 is sent to the 2# pre-dehydration tower 502.

[0075] When it is necessary to deactivate the 2# pre-dehydration tower 502 and the 2# dehydration tower 602, close the second gate valve 162 and the sixth gate valve 176, and open the first gate valve 161 and the fourth gate valve 174. The low-quality steam generated at the top of the 2# second-effect evaporation tower 402 is sent to the 1# reboiler three 901. The generated non-condensable gases enter the non-condensable gas main pipe 12 and are mixed and then sent to the 1# ice machine set 131, the 2# ice machine set 132, and the 3# ice machine set 133, serving as the heat source for the ice machine set 13 to provide heat removal for the 1# epoxy unit 101, the 2# epoxy unit 102, and the 3# epoxy unit 103. The bottom material of the 2# second-effect evaporation tower 402 is sent to the 1# pre-dehydration tower 501.

[0076] As Figure 2 shown, when any one of the ice machine sets 13 is put into use, just open the gate valves at both ends of the corresponding ice machine. The material is pressurized by the ice machine transfer pump 20 and then sent to the ice machine for cooling. After cooling, it is sent to each user, and after heat exchange with the user, it returns to the ice machine transfer pump; when any one of the ice machines is deactivated, just close the gate valves at both ends of the corresponding ice machine.

[0077]

[0078] Through experiments, the load relationship between the ethylene glycol section of the 1# ethylene glycol unit 201 and the 2# ethylene glycol unit 202 and the load of the ice machine set 13 is obtained as shown in the above table.

[0079] When the ethylene glycol sections of the 1# ethylene glycol unit 201 and the 2# ethylene glycol unit 202 are at a load of 50% - 80%, the low-quality steam generated by the 1# pre-dehydration tower 501 and the 2# pre-dehydration tower 502 can meet the start-up of the steam ice machine 141 in the 1# ice machine set 131, the 2# ice machine set 132, and the 3# ice machine set 133. Therefore, open the gate valves at both ends of the steam ice machine 141 in each ice machine set 13, close the gate valves at both ends of the steam ice machine 142, and open the gate valves at both ends of the electric ice machine 15.

[0080] When the ethylene glycol sections of the 1# ethylene glycol unit 201 and the 2# ethylene glycol unit 202 are at a load of 85% - 100%, the low-quality steam generated by the 1# pre-dehydration tower 501 and the 2# pre-dehydration tower 502 can meet the start-up of the steam ice machine 141 and the steam ice machine 142 in the 1# ice machine set 131, the 2# ice machine set 132, and the 3# ice machine set 133. Therefore, open the gate valves at both ends of the steam ice machine 141 in each ice machine set 13, open the gate valves at both ends of the steam ice machine 142, and close the gate valves at both ends of the electric ice machine 15.

[0081] It can be seen that with the change of the load of the ethylene glycol section, more low-quality steam can be utilized, reducing the direct emission of low-quality steam into the air, achieving the balance of low-quality steam; at the same time, we can reduce the load of the electric ice machine 15 and save electric energy consumption, achieving both steam energy consumption and electric energy consumption.

Claims

1. An epoxy unit low-quality steam balance system, comprising an epoxy unit (1) and an ethylene glycol unit (2), characterized in that, The ethylene glycol unit (2) includes a first-effect evaporation tower (3), a second-effect evaporation tower (4), a pre-dehydration tower (5), and a dehydration tower (6) connected in sequence, and further includes: A first reboiler (7) whose tube side is connected to the first-effect evaporation tower (3); A second reboiler (8) whose tube side is connected to the second-effect evaporation tower (4) and whose shell side is connected to the top of the first-effect evaporation tower (3); A third reboiler (9) whose tube side is connected to the pre-dehydration tower (5) and whose shell side is connected to the top of the second-effect evaporation tower (4); A fourth reboiler (10) whose tube side is connected to the dehydration tower (6); A condensate tank (11) connected to the shell side outlets of the second reboiler (8) and the third reboiler (9); A non-condensable gas main pipe (12) connected to the first reboiler (7), the second reboiler (8), the third reboiler (9), and the fourth reboiler (10); An ice machine unit (13) connected to the epoxy unit (1) and connected to the non-condensable gas main pipe (12) and the top of the pre-dehydration tower (5).

2. The low-quality steam balance system of an epoxy device according to claim 1, wherein There are 2 sets of the ethylene glycol unit (2), namely the 1# ethylene glycol unit (201) and the 2# ethylene glycol unit (202). The 1# ethylene glycol unit (201) includes a 1# second-effect evaporation tower (401), a 1# dehydration tower (601), and a 1# third reboiler (901). The 2# ethylene glycol unit (202) includes a 2# second-effect evaporation tower (402), a 2# dehydration tower (602), and a 2# third reboiler (902), and further includes: A first interconnection pipeline (16) whose one end is connected to the pipeline between the 1# second-effect evaporation tower (401) and the 1# third reboiler (901), and a first gate valve (161) is provided at the shell side inlet of the 1# third reboiler (901); the other end is connected to the pipeline between the 2# second-effect evaporation tower (402) and the 2# third reboiler (902), and a second gate valve (162) is provided at the shell side inlet of the 2# third reboiler (902).

3. The low-quality steam balance system for an epoxy device according to claim 2, characterized in that, The 1# ethylene glycol unit (201) further includes a 1# pre-dehydration tower (501), and a third gate valve (173) and a fourth gate valve (174) are provided on the pipeline between the 1# pre-dehydration tower (501) and the 1# second-effect evaporation tower (401). The 2# ethylene glycol unit (202) further includes a 2# pre-dehydration tower (502), and a fifth gate valve (175) and a sixth gate valve (176) are provided on the pipeline between the 2# pre-dehydration tower (502) and the 2# second-effect evaporation tower (402). The system further includes: A second interconnection pipeline (17) whose one end is connected to the pipeline between the third gate valve (173) and the fourth gate valve (174); the other end is connected to the pipeline between the fifth gate valve (175) and the sixth gate valve (176).

4. The low-quality steam balance system for an epoxy device according to claim 3, characterized in that, The epoxy unit (1) includes the 1# epoxy unit (101) and the 2# epoxy unit (102). The ice machine set (13) includes the 1# ice machine set (131), the 2# ice machine set (132), and the 3# ice machine set (133). The top steam of the 1# pre-dehydration tower (501) and the 2# pre-dehydration tower (502) is connected to the 1# ice machine set (131), the 2# ice machine set (132), and the 3# ice machine set (133). The 1# ice machine set (131) and the 2# ice machine set (132) are respectively connected to the 1# epoxy unit (101) and the 2# epoxy unit (102). The 3# ice machine set (133) is connected to the 3# epoxy unit (103)(1).

5. An epoxy plant low-quality steam balance system according to claim 4, characterized in that, Each of the ice machine sets (13) includes a steam ice machine one (141), a steam ice machine two (142), and an electric ice machine (15).

6. A low-quality steam balance system for an epoxy device according to any one of claims 1, characterized in that The reboiler one (7), the reboiler two (8), the reboiler three (9), and the reboiler four (10) are all high-flux reboilers. The first-effect evaporation tower (3), the second-effect evaporation tower (4), the pre-dehydration tower (5), and the dehydration tower (6) adopt super-high-efficiency trays.

7. According to the low-quality steam balance system of an epoxy unit described in claim 1, wherein The bottom temperature of the first-effect evaporation tower (3) is 216°C, and the top pressure is 1.9 Mpa. It heats and concentrates the material from the epoxy unit (1). The concentration of the ethylene glycol aqueous solution at the bottom is 18%, and it is transported to the second-effect evaporation tower (4). The bottom temperature of the second-effect evaporation tower (4) is 169°C, and the top pressure is 0.5 Mpa. It heats and concentrates the material from the first-effect evaporation tower (3). The concentration of the ethylene glycol aqueous solution at the bottom is 48%, and it is transported to the pre-dehydration tower (5). The bottom temperature of the pre-dehydration tower (5) is 146°C, and the top pressure is 0.1 - 0.13 Mpa. It heats and concentrates the material from the second-effect evaporation tower (4). The concentration of the ethylene glycol aqueous solution at the bottom is 78%, and it is transported to the dehydration tower (6). The low-quality steam generated at the top of the pre-dehydration tower (5) is transported to the ice machine set (13). The bottom temperature of the dehydration tower (6) is 140°C, and the top pressure is 13 Kpa. It heats and concentrates the material from the pre-dehydration tower (5). The concentration of the ethylene glycol aqueous solution at the bottom is 93%, and it is transported to the MEG refining unit.

8. According to the low-quality steam balance system of an epoxy unit described in claim 7, wherein The reboiler one (7) uses the external steam at 4.0 Mpa as the heat source, and the generated condensate is directly recycled. The reboiler two (8) uses the steam at 1.9 Mpa at the top of the first-effect evaporation tower (3) as the heat source. After the generated condensate is transported to the condensate tank (11), it enters the EG hydration unit. The reboiler three (9) uses the steam at 0.5 Mpa at the top of the second-effect evaporation tower (4) as the heat source. After the generated condensate is transported to the condensate tank (11), it enters the EG hydration unit. The reboiler four (10) uses the clean steam at 1.4 Mpa as the heat source, and the generated condensate is directly recycled. The non-condensable gases discharged from the first reboiler (7), the second reboiler (8), the third reboiler (9), and the fourth reboiler (10) are transported to the ice machine set (13) after being discharged to the non-condensable gas main pipe (12).

9. A low-quality steam balance system for an epoxy unit (1) according to claim 2, characterized in that When the 1# pre-dehydration tower (501) and the 1# dehydration tower (601) are out of service, the first gate valve (161) and the fourth gate valve (174) are closed, and the second gate valve (162) and the sixth gate valve (176) are opened.

10. A low-quality steam balance system for an epoxy unit (1) according to claim 2, characterized in that When the 2# pre-dehydration tower (502) and the 2# dehydration tower (602) are out of service, the second gate valve (162) and the sixth gate valve (176) are closed, and the first gate valve (161) and the fourth gate valve (174) are opened.

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