Waste heat recycling system for xylose hydrolysis reaction

Abstract

The invention discloses a waste heat recycling system for xylose hydrolysis reaction, which comprises a pretreatment waste water waste heat recycling system, a hydrolysis discharge boiler waste heat recycling system and a hydrolysis residue liquid waste heat recycling system, the hydrolysis discharge boiler waste heat recovery system and the hydrolysis residue liquid waste heat recovery system are used for carrying out waste heat recovery on the hydrolyzed slurry. The hydrolysis reaction heat is systematically and intensively recycled, and compared with a traditional recycling mode, the waste heat recycling rate is increased, the electricity consumption of electric heating equipment and the steam consumption are reduced, and the overall production and operation cost of an enterprise is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of xylose production, in particular to a waste heat recovery and utilization system of xylose hydrolysis reaction. Background Art

[0002] In the xylose industry, xylose is obtained by putting biomass raw materials such as corn cobs into a reactor for hydrolysis. The temperature condition of the hydrolysis reaction is 120℃-140℃, and the reaction temperature is controlled by hot steam. After the traditional reaction is completed, the heat is basically discharged on site. Each link in the xylose production is very important. The temperature control of each stage has been achieved through heating, steam heat exchange and other measures in the past, and this method will inevitably consume a lot of steam and electricity. The traditional direct discharge of this part of the heat is very large, which has seriously caused energy waste and pushed up the production cost of the enterprise. How to systematically recycle the heat generated by the hydrolysis reaction process to meet the production of other sections is an urgent problem to be solved. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a systematic, multi-link, high-recovery waste heat recovery and utilization system for xylose hydrolysis reactions.

[0004] The purpose of the present invention is achieved through the following technical scheme: a waste heat recovery and utilization system for xylose hydrolysis reaction, including a pretreatment wastewater waste heat recovery system, a hydrolysis boiler waste heat recovery system, and a hydrolysis slag liquid waste heat recovery system. The pretreatment wastewater waste heat recovery system recovers waste heat from pretreatment wastewater before the hydrolysis process, and the hydrolysis boiler waste heat recovery system and the hydrolysis slag liquid waste heat recovery system recover waste heat from the slurry after the hydrolysis is completed.

[0005] Preferably, the pretreatment wastewater waste heat recovery system includes a pretreatment waste liquid flash tank, a pretreatment waste liquid tank, a first heat exchanger, and a second heat exchanger. The vapor phase pipeline of the pretreatment waste liquid flash tank is connected to the pipeline of the first heat exchanger for heat exchange, the liquid phase pipeline of the pretreatment waste liquid flash tank is connected to the pipeline of the pretreatment waste liquid tank, and the pretreatment waste liquid tank is connected to the second heat exchanger for heat exchange via pipelines.

[0006] Preferably, the hydrolysis boiler waste heat recovery system includes a heat absorption tower, a slag liquid flash tank, and a third heat exchanger. The vapor phase pipeline of the slag liquid flash tank is connected to the heat absorption tower for spray heat exchange, and the washing water of the heat absorption tower is heat exchanged with the third heat exchanger through a pipeline.

[0007] Preferably, the hydrolysis slag liquid waste heat recovery system includes a primary flash tank, a secondary flash tank, a slag slurry tank, a fourth heat exchanger, a fifth heat exchanger, a sixth heat exchanger, a seventh heat exchanger, an eighth heat exchanger, and a ninth heat exchanger. The vapor phase pipeline of the primary flash tank is respectively connected to the fourth heat exchanger and the fifth heat exchanger for heat exchange, the liquid phase pipeline of the primary flash tank is connected to the secondary flash tank, the vapor phase pipeline of the secondary flash tank is respectively connected to the sixth heat exchanger and the seventh heat exchanger for heat exchange, the vapor after heat exchange in the fourth heat exchanger and the fifth heat exchanger is recycled after condensation through the eighth heat exchanger, the vapor of the sixth heat exchanger and the seventh heat exchanger is recycled after condensation through the ninth heat exchanger, and the liquid phase pipeline of the secondary flash tank is connected to the slag slurry tank.

[0008] Preferably, the first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger, the fifth heat exchanger, the sixth heat exchanger, the seventh heat exchanger, the eighth heat exchanger and the ninth heat exchanger are plate heat exchangers.

[0009] The present invention has the following advantages: waste heat recovery is carried out in three links during the entire circulation process of the xylose hydrolysis reactor, the first link is a pretreatment waste heat recovery system, the second link is a hydrolysis boiler waste heat recovery system, and the third link is a hydrolysis slag liquid waste heat recovery system. The three links are divided into nine heat sources for recovery, and the heat of the hydrolysis reaction is systematically concentrated and recovered for utilization, the waste heat recovery rate is greatly improved, and can be applied to all links in the production, shortening the hydrolysis cycle time, reducing the sewage treatment load, reducing the power consumption and steam consumption of the electric heating equipment, and reducing the overall production and operation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the overall structure of the pre-treated wastewater waste heat recovery and utilization system of the present invention;

[0011] Figure 2 It is a schematic diagram of the overall structure of the hydrolysis boiler waste heat recovery system of the present invention;

[0012] Figure 3 It is a schematic diagram of the overall structure of the hydrolysis slag liquid waste heat recovery system of the present invention.

[0013] In the figure, 11, pretreatment waste liquid flash tank; 12, pretreatment waste liquid tank; 13, heat absorption tower; 14, slag liquid flash tank; 15, primary flash tank; 16, secondary flash tank; 17, slag slurry tank; 18, water storage tank; 21, first heat exchanger; 22, second heat exchanger; 23, third heat exchanger; 24, fourth heat exchanger; 25, fifth heat exchanger; 26, sixth heat exchanger; 27, seventh heat exchanger; 28, eighth heat exchanger; 29, ninth heat exchanger; 31, first vacuum pump; 32, second vacuum pump; 33, third vacuum pump; 34, induced draft fan; 41, waste liquid delivery pump; 42, slag liquid delivery pump; 43, heat absorption circulation pump; 44, heat absorption delivery pump; 45, slag slurry delivery pump; 46, water storage tank delivery pump; 501, first waste liquid; 502 , the second waste liquid; 601, the first heat exchanger water inlet; 602, the second heat exchanger water inlet; 603, the third heat exchanger water inlet; 604, the fourth heat exchanger water inlet; 605, the fifth heat exchanger water inlet; 606, the sixth heat exchanger water inlet; 607, the seventh heat exchanger water inlet; 608, the eighth heat exchanger water inlet; 609, the ninth heat exchanger water inlet; 701, the first heat exchanger water outlet; 702, the second heat exchanger water outlet; 703, the third heat exchanger water outlet; 704, the fourth heat exchanger water outlet; 705, the fifth heat exchanger water outlet; 706, the sixth heat exchanger water outlet; 707, the seventh heat exchanger water outlet; 708, the eighth heat exchanger water outlet; 709, the ninth heat exchanger water outlet; 710, heat absorption washing water; 801, the first slag slurry; 802, the second slag slurry; 803, the third slag slurry. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0015] Example 1: A xylose production enterprise uses corn cobs as raw materials to produce sugar. The capacity of the hydrolysis reactor is 50m 3 The steam pressure is 0.6Mpa, the temperature range is 140-160℃, and the hydrolysis reaction goes through 2 discharges. The first is the discharge of pre-treated waste liquid, and the temperature range is about 120℃, and the second is the discharge of hydrolysis slag liquid, and the temperature range is 130℃.

[0016] There are three waste heat recovery measures before transformation, as follows:

[0017] The waste heat of the pre-treatment waste liquid is recovered through a plate heat exchanger. The waste liquid temperature is 123°C, the inlet water temperature is 27°C, the outlet water temperature is 60°C, and the water flow rate is 13m 3 / H, used for preheating of acid preparation section.

[0018] The waste heat of the boiler is recovered through a plate heat exchanger. The hydrolyzate temperature is 134°C, the inlet water temperature is 35°C, the outlet water temperature is 80°C, and the water flow rate is 20m 3 / H, used for secondary evaporation section.

[0019] The waste heat of slag slurry is recovered through plate heat exchanger. The slag slurry temperature is 98℃, the inlet water temperature is 30℃, the outlet water temperature is 50℃, and the water flow rate is 15m 3 / H, for domestic hot water.

[0020] The remaining sections that require temperature are heated by steam, 30T / day, and by electric heating, 4300 degrees / day.

[0021] After transformation Figure 1 As shown, the pretreatment wastewater waste heat recovery system includes a pretreatment waste liquid flash tank 11, a pretreatment waste liquid tank 12, a first heat exchanger 21, a second heat exchanger 22, a first vacuum pump 31, and a waste liquid delivery pump 41. The first waste liquid 501 discharged from the hydrolysis pot at a temperature of 120°C is discharged into the pretreatment waste liquid flash tank 11 through a pipeline. The pretreatment waste liquid flash tank 11 forms a liquid phase and a vapor phase after low-pressure flash evaporation. The liquid phase exchanges heat with the first heat exchanger inlet water at a temperature of 20°C through the first heat exchanger 21, and the The first heat exchanger outlet water 701 with a temperature of 95°C is recovered after condensation of the waste steam, which is the first heat source heat exchange. The liquid phase with a temperature of 95°C after flash evaporation is collected in the pretreatment waste liquid tank, transported by the pretreatment liquid delivery pump 41, and then passed through the second heat exchanger 22 for heat exchange with the second heat exchanger inlet water 602 with a temperature of 35°C to obtain the second heat exchanger outlet water 702 with a temperature of 87°C. The second waste liquid 502 with a temperature of 30°C meets the discharge index and is discharged, which is the second heat source heat exchange.

[0022] like Figure 2As shown, the hydrolysis boiler waste heat recovery system includes a heat absorption tower 13, a slag liquid flash tank 14, a third heat exchanger 23, a water storage tank 18, an induced draft fan 34, a slag liquid delivery pump 42, a heat absorption circulation pump 43, a heat absorption delivery pump 44, and a water storage tank delivery pump 46. After the reaction is completed, the temperature of the hydrolyzed liquid is 130°C-140°C, and the boiler is discharged under pressure. The first slag slurry 801 with a temperature of 130°C enters the slag liquid flash tank 14 and is flashed and divided into a vapor phase and a liquid phase. After entering the slag liquid flash tank 14, the temperature of the acid mist gas is 130°C. After passing through the heat absorption tower 1 3 Spray washing heat exchange, a part of the water after washing is returned to the heat absorption tower 13 for spraying through the heat absorption circulation pump 43, and the other part of the washing water with a temperature of 98°C is exchanged with the third heat exchanger 23 through the heat absorption pump delivery pump 44 to obtain the heat absorption washing water 710 with a temperature of 90°C, which is used for production of other needs. The third heat exchanger inlet water 603 with a temperature of 20°C in the water storage tank 18 is exchanged with the third heat exchanger 23 through the water storage tank delivery pump 46 to obtain the third heat exchanger outlet water 703 with a temperature of 85°C, which is supplied to the post-production stage. This is the third heat source heat exchange.

[0023] like Figure 3 As shown, the hydrolysis slag liquid waste heat recovery system includes a primary flash tank 15, a secondary flash tank 16, a slag slurry tank 17, a fourth heat exchanger 24, a fifth heat exchanger 25, a sixth heat exchanger 26, a seventh heat exchanger 27, an eighth heat exchanger 28, a ninth heat exchanger 29, a slurry delivery pump 45, a second vacuum pump 32, and a third vacuum pump 33. The feed of the primary flash tank 15 comes from Figure 2The second slag slurry 802 in the first flash tank 15 is started, and the second vacuum pump 32 and the third vacuum pump 33 are started. The pressure indication of the first flash tank 15 and the second flash tank 16 is -0.9Bar, and the system is allowed to run. The second slag slurry 802 is flashed in the first flash tank 15 and is divided into a vapor phase and a liquid phase. After entering the first flash tank 15, the vapor with a temperature of 110°C passes through the fourth heat exchanger 24 and exchanges heat with the fourth heat exchanger inlet water 604 with a temperature of 20°C to obtain the fourth heat exchanger outlet water 704 with a temperature of 70°C, which is the fourth heat source heat exchange. After entering the first flash tank 15, the vapor with a temperature of 110°C passes through the fifth heat exchanger 25 and exchanges heat with the fifth heat exchanger inlet water 605 with a temperature of 30°C to obtain the fifth heat exchanger outlet water 705 with a temperature of 80°C, which is the fifth heat source heat exchange. The slag slurry after flashing in the first flash tank 15 directly enters the second flash tank 16 to obtain vapor and liquid phases. Two routes, the steam with a temperature of 95°C after flashing in the first-stage flash tank 16 passes through the sixth heat exchanger 26 and exchanges heat with the sixth heat exchanger inlet water 606 with a temperature of 20°C to obtain the sixth heat exchanger outlet water 706 with a temperature of 65°C, which is the sixth heat source heat exchange, the steam after heat exchange in the fourth heat exchanger 24 and the fifth heat exchanger 25 passes through the eighth heat exchanger 28 and exchanges heat with the eighth heat exchanger inlet water 608 to obtain the eighth heat exchanger outlet water 708, and the synchronous steam is condensed and recycled, which is the eighth heat source heat exchange, the steam in the sixth heat exchanger 26 and the seventh heat exchanger 27 passes through the ninth heat exchanger 29 and exchanges heat with the ninth heat exchanger inlet water 709 to obtain the ninth heat exchanger outlet water 709, and the synchronous steam is condensed and recycled, which is the ninth heat source heat exchange, the liquid phase of the second-stage flash tank 16 is discharged into the slag slurry tank 17 through the pipeline and forms the third slag slurry 803 with a temperature of 35°C through the slurry delivery pump 45.

[0024] Among them, the first heat exchanger 21, the second heat exchanger 22, the third heat exchanger 23, the fourth heat exchanger 24, the fifth heat exchanger 25, the sixth heat exchanger 26, the seventh heat exchanger 27, the eighth heat exchanger 28, and the ninth heat exchanger 29 are plate heat exchangers, which have higher heat exchange efficiency than shell and tube or tube heat exchangers.

[0025] After the three systems were completed, the effect of waste heat recovery was achieved, saving a total of 14T of steam per day, eliminating electric heating, and saving 4,300 degrees per day.

[0026] Compared with the period before the transformation, it is possible to recover heat multiple times from several links in the hydrolysis reaction, and recover a total of nine heat sources in stages. The nine heat sources can be used in multiple work sections, especially after the temperature of the pre-treatment water and the hydrolysis treatment water is increased in the front stage of hydrolysis. The time of the entire hydrolysis cycle has been reduced from 9 hours to the current 7.5 hours, and the hydrolysis time has been saved by 16%. The temperature of the wastewater has dropped, reducing the load of sewage treatment, and the use of steam has been eliminated in the activation of resin, reducing costs.

[0027] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A waste heat recovery system for xylose hydrolysis reaction, characterized in that: It includes a pre-treatment wastewater waste heat recovery system, a hydrolysis boiler waste heat recovery system, and a hydrolysis slag liquid waste heat recovery system. The pre-treatment wastewater waste heat recovery system recovers waste heat from the pre-treatment wastewater before the hydrolysis process, and the hydrolysis boiler waste heat recovery system and the hydrolysis slag liquid waste heat recovery system recover waste heat from the slurry after the hydrolysis is completed.

2. The waste heat recovery and utilization system of xylose hydrolysis reaction according to claim 1, characterized in that: The pretreatment wastewater waste heat recovery system comprises a pretreatment waste liquid flash tank (11), a pretreatment waste liquid tank (12), a first heat exchanger (21), and a second heat exchanger (22); the vapor phase pipeline of the pretreatment waste liquid flash tank (11) is connected to the pipeline of the first heat exchanger (21) for heat exchange; the liquid phase pipeline of the pretreatment waste liquid flash tank (11) is connected to the pipeline of the pretreatment waste liquid tank (12); and the pretreatment waste liquid tank (12) is connected to the second heat exchanger (22) for heat exchange.

3. The waste heat recovery and utilization system of xylose hydrolysis reaction according to claim 1, characterized in that: The hydrolysis boiler waste heat recovery system comprises a heat absorption tower (13), a slag liquid flash tank (14), and a third heat exchanger (23); the vapor phase pipeline of the slag liquid flash tank (14) is connected to the heat absorption tower (13) for spray heat exchange, and the washing water of the heat absorption tower (13) is heat exchanged with the third heat exchanger (23) through a pipeline.

4. The waste heat recovery and utilization system of xylose hydrolysis reaction according to claim 1, characterized in that: The hydrolysis slag liquid waste heat recovery system comprises a primary flash tank (15), a secondary flash tank (16), a slag slurry tank (17), a fourth heat exchanger (24), a fifth heat exchanger (25), a sixth heat exchanger (26), a seventh heat exchanger (27), an eighth heat exchanger (28), and a ninth heat exchanger (29); the vapor phase pipeline of the primary flash tank (15) is connected to the fourth heat exchanger (24) and the fifth heat exchanger (25) for heat exchange, respectively; the liquid phase pipeline of the primary flash tank (15) is connected to the secondary flash tank (16), the liquid phase pipeline of the primary flash tank (15) is connected to the liquid phase pipeline of ...6) is connected to the liquid phase pipeline of the secondary flash tank (16), the liquid phase pipeline of the primary flash tank (16) is connected to the liquid phase pipeline of the secondary flash tank (16), the liquid phase pipeline of the primary flash tank (16) is connected to the liquid phase pipeline of the secondary flash tank (16), the liquid The secondary flash tank (16) is connected to the sixth heat exchanger (26) and the seventh heat exchanger (27) for heat exchange. The vapor after heat exchange in the fourth heat exchanger (24) and the fifth heat exchanger (25) is recycled after condensation in the eighth heat exchanger (28). The vapor of the sixth heat exchanger (26) and the seventh heat exchanger (27) is recycled after condensation in the ninth heat exchanger (29). The liquid phase pipeline of the secondary flash tank (16) is connected to the slag slurry tank (17).

5. The waste heat recovery and utilization system of xylose hydrolysis reaction according to any one of claims 1 to 4, characterized in that: The first heat exchanger (21), the second heat exchanger (22), the third heat exchanger (23), the fourth heat exchanger (24), the fifth heat exchanger (25), the sixth heat exchanger (26), the seventh heat exchanger (27), the eighth heat exchanger (28), and the ninth heat exchanger (29) are selected to be plate heat exchangers.

Images