Method and device for coking crude benzol distillation coupled with ammonia distillation waste heat

Abstract

The present application relates to a kind of coking debenzolization and ammonia evaporation waste heat coupling method, 1) the rectifying section of debenzolization tower is divided into two sections by setting baffle, and the oil-containing steam in the top of lower section is partially condensed in oil vapor intermediate condenser tube passage;2) the liquid phase after partially condensed in oil vapor intermediate condenser is self-flowed to the top of lower section of rectifying section of debenzolization tower, and the oil vapor after partially condensed is entered into the bottom of upper section of rectifying section of debenzolization tower;3) the liquid phase in the bottom of upper section of rectifying section of debenzolization tower is flowed into the top of lower section of rectifying section of debenzolization tower;4) the ammonia evaporation waste water in the bottom of ammonia evaporation tower is pumped out by waste water circulating pump and sent to oil vapor intermediate condenser shell side, and heat exchange with the oil-containing steam entering oil vapor intermediate condenser, and the ammonia evaporation waste water after heat exchange is sent to the bottom of ammonia evaporation tower and partially flashed, to provide part of rising stripping steam for ammonia evaporation operation;Another part of rising stripping steam for ammonia evaporation operation is provided by reboiler.The present application reduces the steam consumption of ammonia evaporation and the circulating water quantity of crude benzene distillation.

Description

Technical Field

[0001] This invention relates to the field of coking chemical product recovery technology, and in particular to a method and apparatus for coupling crude benzene distillation and ammonia stripping waste heat. Background Technology

[0002] In the coking process, the crude benzene distillation process and the ammonia stripping process are the two most energy-intensive sub-processes in the gas purification unit.

[0003] Ammonia stripping in coking involves using distillation to desorb NH3 from residual ammonia water and other separated wastewater, thereby reducing the ammonia nitrogen content in the wastewater. This is a necessary pretreatment step for subsequent biological treatment of the wastewater. Currently, commonly used residual ammonia stripping processes in the coking industry generally include conventional atmospheric pressure stripping and heat pump stripping. Conventional atmospheric pressure stripping is a mature and stable technology, but it consumes a large amount of steam, requiring approximately 170-200 kg of low-pressure steam to treat 1 ton of residual ammonia water, resulting in high energy consumption and operating costs.

[0004] Currently, common crude benzene distillation processes in the coking industry are generally divided into atmospheric pressure superheated steam stripping and negative pressure superheated steam stripping. Atmospheric pressure superheated steam stripping is a mature and stable technology, but it consumes a large amount of steam, requiring approximately 1500 kg / h of 400°C high-temperature stripping steam per ton of crude benzene. Negative pressure superheated steam stripping utilizes a vacuum pump to extract the uncondensed non-condensable gases after the crude benzene condenser, creating a negative pressure environment for the benzene removal system. Compared to atmospheric pressure superheated steam stripping, this process requires a small investment in vacuum equipment but significantly reduces superheated steam consumption, requiring approximately 750 kg / h of 400°C high-temperature stripping steam per ton of crude benzene. However, in the two crude benzene distillation processes mentioned above, the stripping steam and crude benzene steam in the benzene stripping tower are directly condensed and cooled by circulating water after exiting the top of the stripping tower. In particular, the rising oil vapor and water vapor in the rectification section of the stripping tower, at 120–170°C, require a large amount of circulating water to cool the crude benzene steam. These high-temperature, high-quality oil-containing steams have low energy utilization rates. Improving the utilization rate of waste heat energy between different coking processes is an important means to reduce the energy consumption of coking units. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for coupling crude benzene distillation and ammonia stripping waste heat, which has low fixed investment, low operating costs and simple process flow.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A method for coupling benzene removal from coking and waste heat from ammonia stripping includes:

[0008] 1) The rectification section of the benzene stripping tower is divided into upper and lower sections by a baffle. The oil vapor at the top of the lower section of the rectification section enters the tube side of the intermediate oil vapor condenser for partial condensation.

[0009] 2) The liquid phase after partial condensation in the oil-vapor intermediate condenser flows by gravity to the top of the lower section of the benzene removal tower, while the partially condensed oil vapor enters the bottom of the upper section of the benzene removal tower.

[0010] 3) The liquid phase at the bottom of the upper section of the benzene stripping tower flows into the top of the lower section of the benzene stripping tower;

[0011] 4) The ammonia stripping wastewater at the bottom of the ammonia stripping tower is pumped out by the wastewater circulation pump and sent to the shell side of the oil-gas intermediate condenser to exchange heat with the oil-containing steam entering the oil-gas intermediate condenser. After heat exchange, the ammonia stripping wastewater is sent to the bottom of the ammonia stripping tower for partial flash evaporation to provide some of the rising stripping steam for the ammonia stripping operation. The other part of the rising stripping steam for the ammonia stripping operation is provided by the reboiler through a heat source.

[0012] The temperature of the oil vapor at the top of the lower section of the benzene removal tower rectification section in step 1) is 140℃~175℃.

[0013] In step 2), the temperature of the oil vapor after partial condensation in the intermediate condenser is 120℃~130℃.

[0014] The temperature of the ammonia-steamed wastewater after heat exchange in step 4) is 115℃~120℃.

[0015] A coking unit coupling benzene removal and ammonia stripping waste heat includes a benzene removal tower, an oil-gas intercooler condenser, a wastewater circulation pump, an ammonia stripping tower, and a reboiler. A closed baffle divides the rectification section of the benzene removal tower into an upper rectification section and a lower rectification section. The bottom of the upper rectification section has an upper vapor phase inlet and an upper liquid phase outlet. The top of the lower rectification section has a lower vapor phase outlet, a lower liquid phase inlet 1, and a lower liquid phase inlet 2. The lower vapor phase outlet is connected to the tube-side vapor phase inlet of the oil-gas intercooler condenser. The vapor phase outlet of the tube side of the intermediate oil-gas condenser is connected to the upper vapor phase inlet; the liquid phase outlet of the tube side of the intermediate oil-gas condenser is connected to the lower liquid phase inlet 1, and the upper liquid phase outlet is connected to the lower liquid phase inlet 2; the liquid collection area at the bottom of the ammonia stripping tower is connected to the wastewater circulation pump, and the wastewater circulation pump is connected to the shell-side inlet of the intermediate oil-gas condenser; the shell-side outlet of the intermediate oil-gas condenser is connected to the vapor phase space at the bottom of the ammonia stripping tower; the liquid collection area at the bottom of the ammonia stripping tower is connected to the reboiler inlet, and the reboiler outlet is connected to the vapor phase space at the bottom of the ammonia stripping tower.

[0016] Compared with existing technologies, the beneficial effects of this invention are:

[0017] 1) Compared with the existing ammonia stripping process and crude benzene distillation process, the present invention can reduce the steam consumption of the ammonia stripping process and the circulating water consumption of the crude benzene distillation process, which greatly reduces the operating cost of the ammonia stripping process and crude benzene distillation process in coking.

[0018] 2) This invention requires fewer additional equipment compared to the existing ammonia stripping and crude benzene distillation processes, and the material requirements for the equipment are reduced. The lower fixed investment and operating costs make it suitable for upgrading existing coking plants.

[0019] 3) The coking crude benzene distillation and ammonia stripping waste heat coupling method of the present invention is applicable to both atmospheric pressure superheated steam stripping crude benzene distillation process and negative pressure superheated steam stripping crude benzene distillation process. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention.

[0021] In the diagram: 1. Benzene removal tower; 2. Intermediate oil-gas condenser; 3. Wastewater circulation pump; 4. Ammonia stripping tower; 5. Reboiler; 6. Lower vapor phase outlet A; 7. Lower liquid phase inlet 1 B; 8. Upper vapor phase inlet C; 9. Upper liquid phase outlet D; 10. Lower liquid phase inlet 2 E. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0023] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] like Figure 1 A device for coupling benzene removal and ammonia stripping waste heat in coking processes includes a benzene removal tower 1, an oil-vapor intermediate condenser 2, a wastewater circulation pump 3, an ammonia stripping tower 4, and a reboiler 5. A closed baffle 6 divides the rectification section of the benzene removal tower 1 into an upper rectification section and a lower rectification section. The bottom of the upper rectification section has an upper vapor inlet C and an upper liquid outlet D. The top of the lower rectification section has a lower vapor outlet A, a lower liquid inlet B, and a lower liquid inlet E. The lower vapor outlet A is connected to the tube-side vapor inlet of the oil-vapor intermediate condenser 2, and the tube-side vapor outlet of the oil-vapor intermediate condenser 2 is connected to the upper vapor inlet C. The tube-side liquid outlet of the oil-vapor intermediate condenser 2 is connected to the lower liquid inlet B, and the upper liquid outlet D is connected to the lower liquid inlet E.

[0026] The bottom collection area of ​​the ammonia stripping tower 4 is connected to the wastewater circulation pump 3, and the wastewater circulation pump 3 is connected to the shell-side inlet of the oil-gas intermediate condenser 2; the shell-side outlet of the oil-gas intermediate condenser 2 is connected to the bottom vapor phase space of the ammonia stripping tower 4; the bottom collection area of ​​the ammonia stripping tower 4 is connected to the inlet of the reboiler 5, and the outlet of the reboiler 5 is connected to the bottom vapor phase space of the ammonia stripping tower 4.

[0027] Using the coking benzene removal and ammonia stripping waste heat coupling method described above, the 140℃~175℃ oil-containing vapor at the top of the lower section of the rectification section of benzene removal tower 1 flows out from the lower section vapor phase outlet A and enters the tube side of the oil-vapor intermediate condenser 2 for partial condensation; the liquid phase after partial condensation in the oil-vapor intermediate condenser 2 flows by gravity to benzene removal tower 1, and returns to the top of the lower section of the rectification section of benzene removal tower 1 from the lower section liquid phase inlet B; the condensed 120℃~130℃ oil vapor enters the bottom of the upper section of the rectification section of benzene removal tower 1 from the upper section vapor phase inlet C; the rectification section of benzene removal tower 1... The liquid phase at the bottom of the upper section flows out through the upper liquid phase outlet D and flows into the top of the lower section of the benzene stripping tower 1 through the lower liquid phase inlet E; the ammonia stripping wastewater at the bottom of the ammonia stripping tower 4 is pumped out by the wastewater circulation pump 3 and sent to the shell side of the oil-gas intermediate condenser 2 to exchange heat with the oil-containing steam entering the oil-gas intermediate condenser 2. The ammonia stripping wastewater at 115℃~120℃ after heat exchange is sent to the bottom of the ammonia stripping tower 4 for partial flash evaporation to provide part of the rising stripping steam for the ammonia stripping operation; the other part of the rising stripping steam for the ammonia stripping operation is provided by the reboiler through a heat source.

[0028] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention. Furthermore, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. In addition, various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the spirit of the present invention, and should also be considered as the content disclosed by the present invention.

[0029] To make the objectives, technical solutions, and technical effects of this invention clearer, the technical solutions in the embodiments of this invention are now described clearly and completely. However, the embodiments described below are only some embodiments of this invention, not all embodiments. All other embodiments obtained by those skilled in the art in conjunction with the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0030] Example

[0031] With a coking capacity of 3 million tons / year of coke and a wash oil circulation rate of 300m³ for benzene removal, 3 / h, the remaining ammonia water treatment capacity is 100m³. 3 For example, / h.

[0032] A device for coupling benzene removal and ammonia stripping waste heat in coking processes includes a benzene removal tower 1, an oil-vapor intermediate condenser 2, a wastewater circulation pump 3, an ammonia stripping tower 4, and a reboiler 5. A closed baffle 6 divides the rectification section of the benzene removal tower 1 into an upper rectification section and a lower rectification section. The bottom of the upper rectification section has an upper vapor phase inlet C and an upper liquid phase outlet D. The top of the lower rectification section has a lower vapor phase outlet A, a lower liquid phase inlet B, and a lower liquid phase inlet E. The lower vapor phase outlet A is connected to the tube-side vapor phase inlet of the oil-vapor intermediate condenser 2, and the tube-side vapor phase outlet of the oil-vapor intermediate condenser 2 is connected to the upper vapor phase inlet C. The tube-side liquid phase outlet of the oil-vapor intermediate condenser 2 is connected to the lower liquid phase inlet B, and the upper liquid phase outlet D is connected to the lower liquid phase inlet E.

[0033] The bottom collection area of ​​the ammonia stripping tower 4 is connected to the wastewater circulation pump 3, and the wastewater circulation pump 3 is connected to the shell-side inlet of the oil-gas intermediate condenser 2; the shell-side outlet of the oil-gas intermediate condenser 2 is connected to the bottom vapor phase space of the ammonia stripping tower 4; the bottom collection area of ​​the ammonia stripping tower 4 is connected to the inlet of the reboiler 5, and the outlet of the reboiler 5 is connected to the bottom vapor phase space of the ammonia stripping tower 4.

[0034] Using the coking benzene removal and ammonia stripping waste heat coupling method described above, the 140℃~175℃ oil-containing vapor at the top of the lower section of the rectification section of benzene removal tower 1 flows out from the lower section vapor phase outlet A and enters the tube side of the oil-vapor intermediate condenser 2 for partial condensation; the liquid phase after partial condensation in the oil-vapor intermediate condenser 2 flows by gravity to benzene removal tower 1, and returns to the top of the lower section of the rectification section of benzene removal tower 1 from the lower section liquid phase inlet B; the condensed 120℃~130℃ oil vapor enters the bottom of the upper section of the rectification section of benzene removal tower 1 from the upper section vapor phase inlet C; the rectification section of benzene removal tower 1... The liquid phase at the bottom of the upper section flows out through the upper liquid phase outlet D and flows into the top of the lower section of the benzene stripping tower 1 through the lower liquid phase inlet E; the ammonia stripping wastewater at the bottom of the ammonia stripping tower 4 is pumped out by the wastewater circulation pump 3 and sent to the shell side of the oil-gas intermediate condenser 2 to exchange heat with the oil-containing steam entering the oil-gas intermediate condenser 2. The ammonia stripping wastewater at 115℃~120℃ after heat exchange is sent to the bottom of the ammonia stripping tower 4 for partial flash evaporation to provide part of the rising stripping steam for the ammonia stripping operation; the other part of the rising stripping steam for the ammonia stripping operation is provided by the reboiler through a heat source.

[0035] Using the above-mentioned apparatus and method, the steam consumption for ammonia stripping is 105 kg / ton of residual ammonia water, which saves 22.2% of low-pressure steam compared to the existing coking ammonia stripping process with a low-pressure steam consumption of 135 kg / ton of residual ammonia water. The circulating water consumption for crude benzene distillation is 85 t / ton of crude benzene, which saves 16.6% of circulating water compared to the negative pressure superheated steam stripping crude benzene distillation process with a circulating water consumption of 102 t / ton of crude benzene.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for coupling the waste heat of coking debenzolization and ammonia distillation, characterized in that, The application relates to a benzene removal tower and an oil-vapor intermediate condenser. 1) A partition is arranged in the rectifying section of the benzene removal tower to divide the rectifying section into an upper section and a lower section, 140-175 DEG C oil-containing steam at the top of the lower section of the rectifying section enters a tube passage of the oil-vapor intermediate condenser for partial condensation; 2) The liquid phase after the partial condensation in the oil-vapor intermediate condenser flows to the top of the lower section of the rectifying section of the benzene removal tower, and 120-130 DEG C oil vapor enters the bottom of the upper section of the rectifying section of the benzene removal tower; 3) The liquid phase at the bottom of the upper section of the rectifying section of the benzene removal tower flows into the top of the lower section of the rectifying section of the benzene removal tower; 4) Ammonia removal waste water at the bottom of the ammonia removal tower is pumped out by a waste water circulating pump and sent to the shell passage of the oil-vapor intermediate condenser to exchange heat with the oil-containing steam entering the oil-vapor intermediate condenser, the 115-120 DEG C ammonia removal waste water after the heat exchange is sent to the bottom of the ammonia removal tower for partial flashing to provide part of the rising stripping steam for the ammonia removal operation; another part of the rising stripping steam for the ammonia removal operation is provided by the reboiler through heat source heating.

2. A device for the method of coking debenzolization coupled with ammonia distillation waste heat according to claim 1, characterized in that, The application relates to a benzene removal tower and an oil-vapor intermediate condenser. The application relates to a benzene removal tower and an oil-vapor intermediate condenser. The oil-vapor intermediate condenser tube passage liquid phase outlet is connected with the lower section liquid phase inlet one, the upper section liquid phase outlet is connected with the lower section liquid phase inlet two, the ammonia removal tower bottom liquid collecting area is connected with the waste water circulating pump, the waste water circulating pump is connected with the oil-vapor intermediate condenser shell passage inlet, the oil-vapor intermediate condenser shell passage outlet is connected with the ammonia removal tower bottom vapor space, the ammonia removal tower bottom liquid collecting area is connected with the reboiler inlet, and the reboiler outlet is connected with the ammonia removal tower bottom vapor space.

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