A thermal integration process system and method for a phenol - acetone unit and a styrene - butadiene rubber unit

Abstract

The present invention belongs to the field of petrochemical industry and relates to a heat integration process system and method for a phenol acetone unit and a styrene butadiene rubber unit. The method includes: the condensate of the medium and low pressure flash tank in the phenol acetone unit is boosted to a subcooled state by a steam condensate pump, then enters a condensate / oxidation feed heat exchanger to exchange heat with the oxidation feed, and then enters an atmospheric flash tank. The low pressure steam of the low pressure flash tank is sent to the styrene butadiene rubber unit to supply heat to the reboiler of the solvent deweighting tower. By utilizing the characteristics of the energy utilization status of the two units respectively, the present invention realizes heat integration between the units, maximizes the utilization of low temperature heat, and achieves the purpose of energy conservation and carbon reduction.

Description

Technical Field

[0001] The present invention belongs to the field of petrochemical industry. Specifically, it relates to a thermal integration process system between a phenol - acetone plant and a styrene - butadiene rubber plant, and a thermal integration process method between a phenol - acetone plant and a styrene - butadiene rubber plant. Background Art

[0002] The phenol - acetone plant uses benzene and propylene as the main raw materials, and adopts the cumene process technology of the American KELLOGG company to produce phenol and acetone. In the reaction process, the main reaction is that cumene is oxidized to cumene hydroperoxide (CHP), and then decomposed into phenol and acetone. At the same time, side reactions produce non - target products such as poly - cumene, butyl - cumene, and methyl - cumene. Then, impurities are separated by distillation methods to produce high - purity phenol and acetone products.

[0003] The phenol - acetone plant includes a raw material treatment system, an alkylation reaction system, a trans - alkylation reaction system, and a separation system. The raw material treatment system pre - treats benzene and propylene through two - stage pre - treatment, removing basic nitrogen and other nitrogen compounds other than basic nitrogen in benzene, as well as removing impurities such as sulfides, arsenic, water, and nitrogen compounds in propylene that are toxic to the catalyst. The alkylation reaction system synthesizes cumene from benzene and propylene. A small part of cumene is further alkylated to produce poly - cumene. The alkylation reaction is an exothermic reaction. The trans - alkylation reaction system reacts poly - cumene with benzene to produce cumene. The trans - alkylation reaction is an isothermal reaction. The trans - alkylation reactor is a single - bed reactor, which is used in parallel with the alkylation reactor. The separation system is mainly a distillation unit, recovering propane and removing impurities in the feed system. At the same time, unreacted benzene is recovered by the benzene tower and returned to the reactor, cumene is produced as a product, and poly - cumene is recovered for trans - alkylation. Summary of the Invention

[0004] The purpose of the present invention is to provide a thermal integration process system between a phenol - acetone plant and a styrene - butadiene rubber plant, and a thermal integration process method between a phenol - acetone plant and a styrene - butadiene rubber plant using this system.

[0005] The inventors found in the research that some thermal energy in the existing phenol - acetone plant cannot be effectively utilized. For example, the distillation process in the separation system consumes a large amount of high - pressure steam and medium - pressure steam, and discharges a large amount of condensate. In the traditional design, the atmospheric pressure waste heat of the phenol - acetone plant, such as the low - temperature waste heat of the condensate, is directly discharged, resulting in the fact that this part of low - temperature thermal energy is not fully utilized. For example Figure 1As shown, the condensate water in the 0.35 MPa flash tank 3 of the current phenol acetone unit flows by gravity into the atmospheric flash tank 5 and then is sent out of the unit. At the same time, the oxidation feed preheater 2 of the phenol acetone unit is preheated with 0.35 MPa steam. After the oxidation feed extracts the phase change heat of the 0.35 MPa steam, the target temperature is 88°C, and the generated steam condensate also enters the atmospheric flash tank 5. The 0.35 MPa steam condensate is about 70 t / hr, and the operating temperature is about 148°C. The temperature of the flashed condensate is relatively high, and the low-temperature waste heat of the condensate is not recovered.

[0006] The solvent stripping column of the styrene butadiene rubber unit requires 0.35 MPa steam. Currently, the unit introduces 1.0 MPa steam from outside the unit, which is converted into 0.35 MPa steam through a desuperheating reducing valve and sent to the user. After releasing heat through phase change, the steam condensate is discharged from the unit.

[0007] The inventors found that by utilizing the characteristics of the current energy utilization status of the two units, heat integration between the units can be achieved, thereby maximizing the utilization of low-temperature heat. Thus, the present invention was completed.

[0008] The first aspect of the present invention provides a heat integration process system for a phenol acetone unit and a styrene butadiene rubber unit. The system includes a phenol acetone unit and a styrene butadiene rubber unit.

[0009] The phenol acetone unit includes a raw material treatment unit, an alkylation reaction unit, a transalkylation reaction unit, and a separation unit; the separation unit includes a low-pressure flash tank, a steam condensate pump, and an atmospheric flash tank; a condensate / oxidation feed heat exchanger is provided between the raw material treatment unit and the alkylation reaction unit; the oxidation feed pipeline is sequentially connected to the condensate / oxidation feed heat exchanger and the reactor of the alkylation reaction unit.

[0010] The styrene butadiene rubber unit includes a polymerization kettle, a flash tank, a degassing tower, and a solvent stripping column, and the solvent stripping column is provided with a reboiler at the bottom of the tower.

[0011] A steam discharge pipeline is provided at the top of the low-pressure flash tank, and a condensate discharge pipeline is provided at the bottom. The condensate discharge pipeline is sequentially connected to the steam condensate pump, the condensate / oxidation feed heat exchanger, and the atmospheric flash tank. The steam discharge pipeline is divided into two branches, one is connected to the atmospheric flash tank, and the other is connected to the reboiler of the solvent stripping column of the styrene butadiene rubber unit.

[0012] The second aspect of the present invention provides a heat integration process method for a phenol acetone unit and a styrene butadiene rubber unit. This method is carried out in the aforementioned system, and the method includes:

[0013] The condensate of the low-pressure flash tank in the phenol acetone unit is boosted to a subcooled state by a steam condensate pump, then enters the condensate / oxidation feed heat exchanger to exchange heat with the oxidation feed, and then enters the atmospheric flash tank. The low-pressure steam of the low-pressure flash tank is sent to the styrene butadiene rubber unit to heat the reboiler of the solvent deweighting tower.

[0014] By optimizing the heat exchange network and low-temperature heat integration of the phenol acetone unit, the invention fully utilizes the waste heat of the condensate water in the 0.35 MPa flash tank, integrates and optimizes the heat exchange with the unit materials, reduces or avoids discharging to the atmosphere; provides energy for the styrene butadiene rubber unit that requires low-temperature heat, and saves the heating capacity. By utilizing the characteristics of the current energy consumption status of the two units respectively, the invention realizes the heat integration between the units, maximizes the utilization of low-temperature heat, and achieves the purpose of energy conservation and carbon reduction.

[0015] Other features and advantages of the present invention will be described in detail in the following specific implementation section. Brief Description of the Drawings

[0016] The exemplary embodiments of the present invention will be described in more detail by combining with the drawings.

[0017] Figure 1 The figure shows the 0.35 MPa steam treatment method of the phenol acetone unit in the prior art.

[0018] Figure 2 The figure shows a schematic diagram of the heat integration module of the heat integration process system between the phenol acetone unit and the styrene butadiene rubber unit of the present invention.

[0019] Description of the Reference Numerals in the Drawings

[0020] a, oxidation feed; b, oxidized feed after heat exchange; c, flash tank condensate; d, 0.35 MPa steam; e, 0.35 MPa steam condensate; f, 1.0 MPa steam;

[0021] 1, condensate / oxidation feed heat exchanger; 2, oxidation feed preheater; 3, 0.35 MPa flash tank; 4, steam condensate pump; 5, atmospheric flash tank; 6, solvent deweighting tower; 7, reboiler; 8, desuperheating and pressure reducing valve. Detailed Description of the Invention

[0022] The following will describe in detail the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for explaining and understanding the present invention, and are not used to limit the present invention.

[0023] The present invention provides a heat integration process system between a phenol acetone unit and a styrene butadiene rubber unit. The system includes a phenol acetone unit and a styrene butadiene rubber unit.

[0024] The phenol acetone unit includes a raw material treatment unit, an alkylation reaction unit, a transalkylation reaction unit, and a separation unit; the separation unit includes a low-pressure flash tank, a steam condensate pump, and an atmospheric flash tank; a condensate / oxidation feed heat exchanger is provided between the raw material treatment unit and the alkylation reaction unit; the oxidation feed pipeline is sequentially connected to the condensate / oxidation feed heat exchanger and the reactor of the alkylation reaction unit.

[0025] The styrene-butadiene rubber unit includes a polymerization kettle, a flash tank, a degassing tower, and a solvent deweighting tower, and a kettle reboiler is provided in the solvent deweighting tower.

[0026] A steam discharge pipeline is provided at the top of the low-pressure flash tank, and a condensate discharge pipeline is provided at the bottom. The condensate discharge pipeline is sequentially connected to the steam condensate pump, the condensate / oxidation feed heat exchanger, and the atmospheric flash tank. The steam discharge pipeline is divided into two branches, one branch is connected to the atmospheric flash tank, and the other branch is connected to the reboiler of the solvent deweighting tower of the styrene-butadiene rubber unit.

[0027] In the present invention, the low-pressure flash tank can be a 0.3 - 0.4 MPa flash tank, especially the 0.35 MPa flash tank in the phenol acetone unit.

[0028] According to an embodiment of the present invention, at least one branch pipeline of the steam discharge pipeline is provided with a valve for controlling the steam volume entering the styrene-butadiene rubber unit and the atmospheric flash tank.

[0029] According to the present invention, the phenol acetone unit and the styrene-butadiene rubber unit are both conventional units in the art. The functions of each unit and component are well known to those skilled in the art.

[0030] Specifically, for the phenol acetone unit: the raw material treatment unit is used for the purification of benzene and propylene; the alkylation reaction unit is used for the synthesis of cumene from benzene and propylene; the transalkylation reaction unit is used for the reaction of by-product polyisopropylbenzene in the alkylation reaction unit with benzene to generate cumene; the separation unit is used for separating cumene, benzene, propane, and polyisopropylbenzene in the reaction product of the alkylation reaction unit.

[0031] The present invention also provides a thermal coupling process method for the phenol acetone unit and the styrene-butadiene rubber unit. This method is carried out in the above system, and the method includes:

[0032] The condensate of the low-pressure flash tank in the phenol acetone unit is boosted to a subcooled state by the steam condensate pump, then enters the condensate / oxidation feed heat exchanger to exchange heat with the oxidation feed, and then enters the atmospheric flash tank. The low-pressure steam of the low-pressure flash tank is sent to the styrene-butadiene rubber unit to supply heat to the reboiler of the solvent deweighting tower.

[0033] As described above, the low-pressure flash tank refers to a flash tank with a pressure of 0.3 - 0.4 MPa, especially a 0.35 MPa flash tank. Correspondingly, the low-pressure steam of the low-pressure flash tank is steam with a pressure of 0.3 - 0.4 MPa, especially 0.35 MPa steam.

[0034] According to the present invention, a new steam condensate pump is added to the phenol acetone unit. The condensate water from the 0.35 MPa flash tank no longer enters the atmospheric flash tank, but is boosted to 0.5 - 0.6 MPa by the steam condensate pump. At this pressure, the condensate water is in a subcooled state, avoiding water hammer. The present invention adds a high-temperature condensate / oxidation feed heat exchanger to fully optimize and utilize the heat sinks of the unit, and the original oxidation feed preheater can be shut down for standby.

[0035] The present invention connects the phenol acetone unit and the styrene butadiene rubber unit by constructing a 0.35 MPa steam pipeline. To ensure the state of the 0.35 MPa steam during transmission, it is preferably to superheat the low-pressure steam and then send it to the styrene butadiene rubber unit. More specifically, the surplus low-pressure steam of the phenol acetone unit is superheated by 1.8 MPa superheated steam and then sent to the styrene butadiene rubber unit.

[0036] After the optimization of the heat exchange network and the optimization of low-temperature heat integration, the steam consumption of the unit decreases, but the original low-pressure steam balance of the 0.35 MPa steam unit is broken, and there is a surplus of low-pressure steam. Sending it to the styrene butadiene rubber unit for heating the reboiler, the original steam heater (1.0 MPa steam) for the reboiler of the solvent deweighting tower is shut down for standby. After the recovery and utilization of waste heat, the consumption of 1.0 MPa steam in the styrene butadiene rubber unit is actually saved, achieving the purpose of energy conservation and consumption reduction.

[0037] The present invention will be further described below in conjunction with embodiments, but the scope of the present invention is not limited to these embodiments.

[0038] Comparative Example 1

[0039] The actual situations of the existing phenol acetone unit and styrene butadiene rubber unit are as follows:

[0040] A. The condensate water of the 0.35 MPa flash tank in the phenol acetone unit is heated to about 150 °C and then discharged through an air cooler at a rate of 70 t / hr.

[0041] B. The oxidation feed of the phenol acetone unit needs to be preheated, and the preheater uses 0.35 MPa steam for preheating to a target temperature of 88 °C.

[0042] C. The solvent deweighting tower of the styrene butadiene rubber unit needs about 4 t / h of steam at 98 °C and 0.3 MPa. The original unit uses 1.0 MPa steam to supply it by reducing the temperature and pressure, resulting in the problem of low-quality utilization of high-quality energy.

[0043] Example

[0044] The present invention adopts a thermal integration process system for a phenol - acetone plant and a styrene - butadiene rubber plant. The system includes a phenol - acetone plant and a styrene - butadiene rubber plant.

[0045] The phenol - acetone plant includes a raw material treatment unit, an alkylation reaction unit, a trans - alkylation reaction unit, and a separation unit.

[0046] The thermal integration module is as Figure 2 shown. The separation unit includes a 0.35 MPa flash tank 3, a steam condensate pump 4, and an atmospheric flash tank 5. A condensate / oxidation feed heat exchanger 1 is arranged between the raw material treatment unit and the alkylation reaction unit. The oxidation feed pipeline is sequentially connected to the condensate / oxidation feed heat exchanger 1 and the reactor of the alkylation reaction unit.

[0047] The styrene - butadiene rubber plant includes a polymerization kettle, a flash tank, a degassing tower, and a solvent stripping tower 6. The solvent stripping tower 6 is provided with a reboiler 7 at the bottom of the tower.

[0048] The condensate discharge pipeline of the 0.35 MPa flash tank 3 is sequentially connected to the steam condensate pump 4, the condensate / oxidation feed heat exchanger 1, and the atmospheric flash tank 5. The steam discharge pipeline of the 0.35 MPa flash tank 3 is divided into two branches. One branch is connected to the atmospheric flash tank 5, and the other branch is connected to the reboiler 7 of the solvent stripping tower 6 of the styrene - butadiene rubber plant. A valve is arranged on the branch pipeline connected to the atmospheric flash tank 5.

[0049] The method for thermal integration using this device includes: The flash tank condensate c of the 0.35 MPa flash tank 3 in the phenol - acetone plant is boosted to 0.6 MPa by the steam condensate pump 4, and then enters the condensate / oxidation feed heat exchanger 1 to exchange heat with the oxidation feed a. The oxidized feed b after heat exchange enters the reactor, and the flash tank condensate after heat exchange enters the atmospheric flash tank 5. The 0.35 MPa steam d of the 0.35 MPa flash tank 3 is sent to the styrene - butadiene rubber plant to supply heat to the reboiler 8 of the solvent stripping tower 7 (superheated by 1.8 MPa superheated steam and then sent to the styrene - butadiene rubber plant), and the surplus can enter the atmospheric flash tank 5.

[0050] The present invention optimizes the heat exchange network between the phenol - acetone plant and the styrene - butadiene rubber plant as follows:

[0051] 1. A compressor is arranged after the condensate of the 0.35 MPa flash tank in the phenol - acetone plant to boost the pressure to 0.5 - 0.6 MPa.

[0052] 2. A high - temperature condensate / oxidation feed heat exchanger is newly added before the oxidation feed pre - heater to pre - heat the oxidation feed using the high - temperature condensate after pressure boost.

[0053] 3. By constructing a 0.35 MPa steam pipeline to connect the phenol - acetone plant and the styrene - butadiene rubber plant. The surplus 0.35 MPa steam from the phenol - acetone plant is superheated by 1.8 MPa superheated steam and then sent to the styrene - butadiene rubber plant.

[0054] The energy - saving effects are as follows:

[0055] (1) After optimizing the first and second points in the optimization plan, the heat - exchange effect between the steam condensate of the phenol - acetone plant and the oxidation feed is shown in Table 1. When the oxidation feed is heated to 88 °C, the temperature of the steam condensate is still 110 °C, which can save 2.95 MW of the original heat for heating the oxidation feed. Under normal circumstances, heat - exchange can completely replace the steam heater, and about 4 t / hr of 0.35 MPaG steam can be saved.

[0056] Table 1 Heat - exchange effect between the steam condensate of the phenol - acetone plant and the oxidation feed

[0057] Material Name Flow Rate t / h Temperature before Cooling ℃ Temperature after Cooling ℃ Heat MW 0.35MPa Steam Condensate 70 147 110 2.95 Oxidation Feed 100 34 88 -2.95

[0058] (2) After optimizing the third point in the optimization plan, since the 0.3 MPa steam for the styrene - butadiene rubber plant is generated by reducing the pressure of the 1.0 MPa steam pipeline outside the plant, after the waste - heat recovery and utilization, the external supply of 1.0 MPa steam to the styrene - butadiene rubber plant is actually eliminated, and the consumption can be reduced by about 4.4 t / hr.

[0059] (3) After the modification according to the solution of the present invention, the steam network balance of the phenol - acetone plant is shown in Table 2.

[0060] Table 2 0.35 MPa steam network balance of the phenol - acetone plant

[0061]

[0062] As can be seen from the above table, in the original process, the steam supplemented by the phenol - acetone plant is 0.3 t / hr. In the optimized process, the 0.35 MPaG steam sent to the styrene - butadiene rubber plant is drawn from the low - pressure steam pipeline of the phenol - acetone plant. Through theoretical calculation, the phenol - acetone plant can output about 4.4 t / hr of 0.35 MPaG steam.

[0063] Comparative Example 2

[0064] Adopt the low - temperature thermal power generation technology to recover low - temperature heat, and then use the electric energy to heat the feed of the phenol - acetone plant and the de - heavy - component tower of the styrene - butadiene rubber plant. Due to the low power - generation efficiency, the energy - saving rate is about 8%, and the amount of circulating water needs to be increased.

[0065] The combined heat utilization between the devices of the present invention does not require additional load. The air - cooled unit, feed heater of the phenol - acetone plant, and steam heater of the solvent de - heavy - component tower of the styrene - butadiene rubber plant can all be shut down, and the energy - saving rate is 100%.

[0066] The embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is also not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

[0067] The endpoints and any values in the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

Claims

1. A thermal integration process system for a phenol - acetone unit and a styrene - butadiene rubber unit, characterized in that, The system includes a phenol - acetone plant and a styrene - butadiene rubber plant. The phenol - acetone plant includes a raw material treatment unit, an alkylation reaction unit, a trans - alkylation reaction unit, and a separation unit; the separation unit includes a low - pressure flash tank, a steam condensate pump, and an atmospheric flash tank; a condensate / oxidation feed heat exchanger is arranged between the raw material treatment unit and the alkylation reaction unit; the oxidation feed pipeline is sequentially connected to the condensate / oxidation feed heat exchanger and the reactor of the alkylation reaction unit. The styrene - butadiene rubber plant includes a polymerization kettle, a flash tank, a degassing tower, and a solvent de - heavying tower, and the solvent de - heavying tower is provided with a reboiler at the bottom of the tower. The top of the low - pressure flash tank is provided with a steam discharge pipeline, and the bottom is provided with a condensate discharge pipeline. The condensate discharge pipeline is sequentially connected to the steam condensate pump, the condensate / oxidation feed heat exchanger, and the atmospheric flash tank. The steam discharge pipeline is divided into two branches, one is connected to the atmospheric flash tank, and the other is connected to the reboiler of the solvent de - heavying tower of the styrene - butadiene rubber plant.

2. The thermal integration process system of a phenol - acetone unit and a styrene - butadiene rubber unit according to claim 1, wherein The low - pressure flash tank is a 0.3 - 0.4 MPa flash tank.

3. The thermal integration process system of the phenol acetone unit and the styrene butadiene rubber unit according to claim 1, wherein The raw material treatment unit is used for the purification of benzene and propylene. The alkylation reaction unit is used for synthesizing cumene from benzene and propylene. The trans - alkylation reaction unit is used for reacting the by - product poly - cumene in the alkylation reaction unit with benzene to generate cumene. The separation unit is used for separating cumene, benzene, propane, and poly - cumene in the reaction product of the alkylation reaction unit.

4. A thermal integration process method for a phenol acetone unit and a styrene butadiene rubber unit, characterized in that, This method is carried out in the system described in any one of claims 1 - 3, and the method includes: The condensate of the low - pressure flash tank in the phenol - acetone plant is boosted to a sub - cooled state by a steam condensate pump, then enters the condensate / oxidation feed heat exchanger to exchange heat with the oxidation feed, and then enters the atmospheric flash tank. The low - pressure steam of the low - pressure flash tank is sent to the styrene - butadiene rubber plant to heat the reboiler of the solvent de - heavying tower.

5. The method according to claim 4, characterized in that, The low - pressure steam of the low - pressure flash tank is 0.3 - 0.4 MPa steam.

6. The method according to claim 5, characterized in that The low - pressure steam of the low - pressure flash tank is 0.35 MPa steam.

7. The method according to claim 4, characterized in that The condensate is boosted to 0.5 - 0.6 MPa by the steam condensate pump.

8. The method according to claim 5 or 6, characterized in that The low - pressure steam is sent to the styrene - butadiene rubber plant after being superheated.

9. The method according to claim 8, wherein The low - pressure steam is superheated by 1.8 MPa superheated steam and then sent to the styrene - butadiene rubber plant.

10. The method according to claim 4, wherein The original steam heater for the reboiler of the solvent de - heavying tower is shut down for standby.

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