Steam and power cogeneration system and method for beet sugar production

Abstract

The invention discloses a steam-electricity cogeneration system and method for sugar beet production. The system comprises a desalted water tank, a third heat exchanger, a separation water tank, a water drying tower, a first heat exchanger and a shaft sealing device of a steam turbine. The desalted water tank is connected to the pipe side inlet of the third heat exchanger through a circulation pipeline and a pump body, the pipe side outlet of the third heat exchanger is connected to the desalted water tank through a reflux pipeline, the desalted water tank is connected to the separation water tank through a water supply pipeline and a pump, the water drying tower is connected to the pipe side inlet of the first heat exchanger through a first pipeline, the pipe side outlet of the first heat exchanger is connected to the shell side inlet of the third heat exchanger through a fourth pipeline, the shell side outlet of the third heat exchanger is connected to the water drying tower through a third pipeline, and the condensed water outlet of the shaft sealing device of the steam turbine is connected to the shell side inlet of the first heat exchanger through a water inlet pipe. The invention enables the heat escaped from the shaft sealing device of the steam turbine and the slag cooler to be recycled, heats the desalted water, and makes the desalted water reach the working temperature, which is energy-saving and environmentally friendly.

Description

Technical Field

[0001] The invention relates to the technical field of vegetable processing, and in particular to a steam-electricity cogeneration system and method for beet sugar production. Background Art

[0002] Sugar production is the process of using crops such as sugarcane or beets as raw materials to produce commercial white sugar, soft sugar or raw sugar, and to refine semi-finished raw sugar. In the sugar production process using beets as raw materials, the beets are pre-treated by weeding, stone removal, cleaning, etc., and then cut into shreds and put into the extractor to extract sugar juice. The sugar juice is then cleaned by the double carbonation method after deslagging and weighing to obtain clear and transparent clean sugar juice. Finally, it is evaporated and concentrated, boiled and crystallized, crystal-assisted separation, dried and packaged to obtain commercial white sugar or soft sugar. Modern sugar factories have a large production capacity, processing 5,000 to 10,000 tons of beets per day.

[0003] Sugar production requires 250-300 tons of desalted water for separation and washing of sugar every day, and the boiler needs to be supplemented with 20-50 tons of desalted water every day. The desalted water is generally 15-20℃. The desalted water at 15-20℃ needs to be heated to 75-85℃ by steam for separation and washing of sugar paste in sugar production, and the boiler supplementary water is 15-20℃ soft water directly added to the boiler water. On the other hand, the outlet water temperature of the boiler's slag cooler cooling water and the turbine generator's shaft seal cooling water is relatively high, and needs to be sent to the outdoor air-drying tower for cooling and cooling before recycling. When the weather is good and the temperature is high, the cooling water cannot meet the requirements, and cooling water needs to be supplemented for cooling, which causes a huge waste of energy. Summary of the invention

[0004] The first purpose of the present invention is to overcome the shortcomings of the prior art and provide a more energy-saving steam-electricity cogeneration system for beet sugar production.

[0005] The first objective of the present invention is achieved through the following technical scheme: A system for cogeneration of steam and power in sugar beet production, comprising a desalted water tank, a third heat exchanger, a separation water tank, a water drying tower, a first heat exchanger and a shaft sealing device of a steam turbine, wherein the desalted water tank is connected to the tube side inlet of the third heat exchanger through a circulation pipeline and a pump body, the tube side outlet of the third heat exchanger is connected to the desalted water tank through a reflux pipeline, the desalted water tank is connected to the separation water tank through a water supply pipeline and a pump, the water drying tower is connected to the tube side inlet of the first heat exchanger through a first pipeline, the tube side outlet of the first heat exchanger is connected to the shell side inlet of the third heat exchanger through a fourth pipeline, the shell side outlet of the third heat exchanger is connected to the water drying tower through a third pipeline, and the condensate outlet of the shaft sealing device of the steam turbine is connected to the shell side inlet of the first heat exchanger through a water inlet pipe.

[0006] The water drying tower is connected to the cooling water inlet of the slag cooler through a pipeline, and the hot water outlet of the slag cooler is connected to the fourth pipeline through the second pipeline.

[0007] The water supply pipeline is connected with a second heat exchanger.

[0008] It also includes: a temperature measurement module, which is arranged on the separation water tank and is used to obtain the water supply temperature; and a control module, which is used to adjust the energy supply of the second heat exchanger.

[0009] The water supply pipeline is also connected to a boiler water supply pipeline.

[0010] The interior of the third heat exchanger is divided into a first cavity, a second cavity and a third cavity from bottom to top in sequence by two groups of tube sheets. The first cavity is connected to the third cavity through a heating tube uprightly arranged in the second cavity. The third cavity is divided into a cold water cavity and a hot water cavity by an isolating member. The third heat exchanger is provided with a tube side inlet communicating with the cold water cavity, the third heat exchanger is provided with a tube side outlet communicating with the hot water cavity, and the third heat exchanger is provided with a shell side inlet and a shell side outlet communicating with the second cavity.

[0011] The isolation member includes two groups of isolation plates, and an isolation cavity is formed between the two groups of isolation plates.

[0012] The third heat exchanger is provided with a drain pipe communicating with the second cavity.

[0013] The second purpose of the present invention is to overcome the shortcomings of the prior art and provide a more energy-saving cogeneration method for beet sugar production.

[0014] The second object of the present invention is achieved by the following technical solution: A steam-electricity cogeneration method for beet sugar production, comprising the following steps:

[0015] S1: Desalted water in the desalted water tank after RO filtration and EDI filtration is sent to the tube side of the third heat exchanger through a circulation pipeline;

[0016] S2: One path of cooling water in the air-drying tower is heated by condensed water of the turbine shaft seal device in the first heat exchanger, and the other path of cooling water in the air-drying tower is heated by the slag cooler. The two paths of hot water enter the shell side of the third heat exchanger to heat the desalted water, and the heated desalted water returns to the desalted water tank, and the cycle repeats in this way;

[0017] S3: After the temperature of the desalted water in the desalted water tank rises to 80-85°C, the pump of the water supply pipeline is started to send the desalted water to the separation water tank and the boiler water supply pipeline for use;

[0018] S4: A second heat exchanger is set in the water supply pipeline. When the temperature measurement module of the separation water tank detects that the temperature of the desalted water is lower than 75°C, high-temperature steam is introduced into the second heat exchanger to perform secondary heating on the desalted water to meet the requirements of the separation and sugar washing process.

[0019] The beneficial effects of the present invention are:

[0020] 1. The steam-electricity cogeneration system for sugar beet production isolates the pollution of desalted water by the cooling water of the steam turbine and the slag cooler, while recycling most of the escaped heat. The sugar paste separation washing water sent to the sugar workshop basically reaches the working temperature, and no or little steam heating is required. The boiler feed water temperature also meets the use requirements, which effectively saves energy and is safe and environmentally friendly.

[0021] 2. In the steam-electricity cogeneration system for beet sugar production, the desalted water fully absorbs the heat sent in by the fourth pipeline and achieves a certain cooling effect on the water in the fourth pipeline. The water flow after preliminary cooling is sent to the water drying tower through the third pipeline for further cooling, which greatly saves the cooling time. The cooling effect further reduces the limitation of the ambient temperature and improves the cooling efficiency;

[0022] 3. The steam-electricity cogeneration system for sugar beet production recycles the waste steam generated by the steam turbine. By installing a heat exchanger and a temperature controller, the desalted water in the desalting tank is heated for use as washing water for product sugar production separation, which not only improves product quality but also reduces energy consumption. At the same time, the desalted water used to supplement the boiler is also heated by more than 60°C, which can save more than 1,000 tons of coal and a large amount of fresh water in one production season.

[0023] 4. The steam-power cogeneration system used for sugar beet production reduces the load on the turbine cooling water drying tower, eliminates the need for constant replenishment of cold water, reduces the use of groundwater, and stabilizes the production of the boiler turbine unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the present invention;

[0025] Figure 2 is a system block diagram of the present invention;

[0026] Figure 3 This is the structural diagram of the third heat exchanger Figure 1 ;

[0027] Figure 4 This is the structural diagram of the third heat exchanger Figure 2 .

[0028] In the figure: 1. desalted water tank; 2. circulation pipeline; 3. pump body; 4. third heat exchanger; 5. third pipeline; 6. return pipeline; 7. flow meter; 8. water drying tower; 9. second pipeline; 10. slag cooler; 11. first pipeline; 12. first heat exchanger; 13. water inlet pipe; 14. fourth pipeline; 15. water supply pipeline; 16. drain pipe; 17. boiler water supply pipeline; 18. second heat exchanger; 19. separation water tank; 20. separator water tank; 21. liquid level sensor; 22. temperature sensor; 23. steam turbine; 24. tube sheet; 25. first cavity; 26. second cavity; 27. cold water cavity; 28. hot water cavity; 29. ​​isolation plate; 30. heating tube. DETAILED DESCRIPTION

[0029] The present invention is described in detail below with reference to the accompanying drawings.

[0030] Reference Figure 1 , Figure 3 and Figure 4 A system for cogeneration of steam and power in sugar beet production comprises a desalted water tank 1, a third heat exchanger 4, a separation water tank 19, a water drying tower 8, a first heat exchanger 12 and a shaft sealing device of a steam turbine 23, wherein the desalted water tank 1 is connected to a tube side inlet of the third heat exchanger 4 through a circulation pipeline 2 and a pump body 3, a tube side outlet of the third heat exchanger 4 is connected to the desalted water tank 1 through a reflux pipeline 6, the desalted water tank 1 is connected to the separation water tank 19 through a water supply pipeline 15 and a pump, the water drying tower 8 is connected to a tube side inlet of the first heat exchanger 12 through a first pipeline 11, a tube side outlet of the first heat exchanger 12 is connected to a shell side inlet of the third heat exchanger 4 through a fourth pipeline 14, a shell side outlet of the third heat exchanger 4 is connected to the water drying tower 8 through a third pipeline 5, and a condensate outlet of the shaft sealing device of the steam turbine 23 is connected to a shell side inlet of the first heat exchanger through a water inlet pipe 13.

[0031] The water supply pipeline 15 is connected to a second heat exchanger 18 for further heating the water when the water temperature in the water supply pipeline 15 does not reach the separation water temperature requirement. The water supply pipeline 15 is also connected to a boiler water supply pipeline 17 .

[0032] The demineralized water filtered by the reverse osmosis membrane and the ultrafiltration membrane is stored in the demineralized water tank 1. A circulation pipeline 2 is installed in the 300m³ demineralized water tank 1. The circulation pipeline 2 sends the low-temperature water in the demineralized water tank 1 to the second heat exchanger 4. At the same time, the air-drying tower 8 sends the cold water to the first heat exchanger 12 through the first pipeline 11, which is used to exchange the heat of the condensed water output by the shaft sealing device of the steam turbine 23. The cold water is heated to hot water in the first heat exchanger 12. The hot water is sent to the third heat exchanger 4 through the fourth pipeline 14 to heat the demineralized water. The heated demineralized water flows back to the demineralized water tank 1 through the reflux pipeline 6, and then is sent to the boiler water supply pipeline 17 or the separation water tank 19 through the water supply pipeline 15. After the hot water in the fourth pipeline 14 is cooled by heat exchange, it is sent back to the air-drying tower 8 through the third pipeline 5 for further cooling.

[0033] The water drying tower 8 is connected to the cooling water inlet of the slag cooler 10 through a pipeline, and the hot water outlet of the slag cooler 10 is connected to the fourth pipeline 14 through the second pipeline 9. The second water flow is sent to the slag cooler 10 through the second pipeline 9 to cool the working slag cooler 10 and discharge hot water. Finally, the heated water in the first pipeline 11 and the second pipeline 9 is sent to the third heat exchanger 4 through the fourth pipeline 14.

[0034] The present invention isolates the pollution of the desalted water by the shaft seal device of the steam turbine 23 and the slag cooler 10, so that most of the heat of boiler slag discharge and the heat escaped from the shaft seal of the steam turbine 23 can be recovered and utilized, and the sugar paste separation washing water sent to the sugar workshop basically reaches the working temperature, and no or little steam heating is required, and the boiler water supply temperature is also relatively high, which effectively saves energy and is safe and environmentally friendly.

[0035] The shell side outlet of the first heat exchanger 12 is connected to the condensate return port of the steam boiler through a pipeline, and the steam generated by the steam boiler is continuously supplied to the shaft sealing device of the steam turbine 23.

[0036] The interior of the third heat exchanger 4 is divided into a first cavity 25, a second cavity 26 and a third cavity from bottom to top in sequence by two groups of tube sheets 24. The first cavity 25 is connected to the third cavity through a heating tube 30 uprightly arranged in the second cavity 26. The third cavity is separated into a cold water cavity 27 and a hot water cavity 28 by an isolating member. The third heat exchanger 4 is provided with a tube side inlet connected to the cold water cavity 27, and the third heat exchanger 4 is provided with a tube side outlet connected to the hot water cavity 28. The circulation pipeline 2 and the reflux pipeline 6 are respectively connected to the cold water cavity 27 and the hot water cavity 28. The third heat exchanger 4 is provided with a shell side inlet and a shell side outlet connected to the second cavity 26. The fourth pipeline 14 and the third pipeline 5 are both connected to the second cavity 26. The isolating member includes a plurality of groups of isolation plates 29, and an isolation cavity is formed between the plurality of isolation plates 29. The isolation cavity is filled with an inert gas. A drain pipe 16 is provided on the bottom side wall of the second cavity 26.

[0037] During operation, the hot water in the fourth pipeline 14 enters the second cavity 26 through the shell side inlet, and flows back to the air-drying tower 8 through the shell side outlet and the third pipeline 5. At the same time, the low-temperature desalted water directly enters the cold water cavity 27 through the circulation pipeline 2, and then enters the first cavity 25 through the left half of the heating pipe 30. After that, the water flows through the right half of the heating pipe 30 into the hot water cavity 28, and then is sent back to the desalted water tank 1 through the reflux pipeline 6 to ensure full use of heat and prevent the water in the fourth pipeline 14 from polluting the desalted water. The desalted water fully absorbs the heat of the hot water sent in by the fourth pipeline 14 in the third heat exchanger 4, and cools the water in the fourth pipeline 14. The cooled water is sent to the air-drying tower 8 through the third pipeline 5 for further cooling, which greatly saves the cooling time, and the cooling effect is further free from the limitation of the ambient temperature, thereby improving the cooling efficiency.

[0038] The separation water tank 19 is connected to the separator water tank 20 through a water distribution pipe, and also includes: a temperature measurement module, which is arranged on the separation water tank 19, and is used to obtain the water supply temperature; a control module, which is used to adjust the energy supply of the second heat exchanger 18. The control module of the PLC system and the temperature measurement module with a sensor are arranged on the separation water tank 19, which are used to monitor and manage the water temperature in the separation water tank 19. The temperature of the hot water sent from the desalted water tank 1 is usually 15-20°C, which can be directly used for boiler production water replenishment through the boiler water supply pipeline 17, and the separation water tank 19 is preferably 75-85°C. In order to improve the production quality of sugar paste separation and washing in sugar production, a second heat exchanger 18 is arranged in the process of supplying water to the separation water tank 19, and the desalted water is secondary heated by high-temperature steam to ensure its greatly optimal production temperature. At the same time, the control system in the central control room can realize the monitoring operation of the site, ensuring the normal water temperature while reducing the workload.

[0039] Flow meters 7 are provided on the water supply pipeline 15, the return pipeline 6 and the first pipeline 11, so as to obtain the field data in real time and carry out the subsequent unified distribution through the central control room, which greatly reduces the difficulty of work. The desalted water tank 1 is provided with a liquid level sensor 21 and a temperature sensor 22, which can ensure the controllable water temperature in the desalted water tank 1 and the normal circulation.

[0040] join Figure 2 , a method for cogeneration of steam and electricity for beet sugar production, the steps are as follows:

[0041] S1: Deionized water in the deionized water tank 1 after RO filtration and EDI filtration is sent to the tube side of the third heat exchanger 4 through the circulation pipeline 2;

[0042] S2: One path of cooling water in the air-drying tower 8 is heated by condensed water of the shaft seal device of the steam turbine 23 in the first heat exchanger 12, and the other path of cooling water in the air-drying tower 8 is heated by the slag cooler 10. The two paths of hot water enter the shell side of the third heat exchanger 4 to heat the desalted water, and the heated desalted water returns to the desalted water tank 1, and the cycle repeats in this way;

[0043] S3: After the temperature of the desalted water in the desalted water tank 1 rises to 80-85°C, the pump body 3 of the water supply pipeline 15 is started to deliver the desalted water to the separation water tank 19 and the boiler water supply pipeline 17 for use;

[0044] S4: A second heat exchanger 18 is provided in the water supply pipeline 15. When the temperature measuring module of the separation water tank 19 detects that the temperature of the desalted water is lower than 75°C, high-temperature steam is introduced into the second heat exchanger 18 to perform secondary heating on the desalted water to meet the requirements of the separation and sugar washing process.

[0045] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for cogeneration of steam and electricity for beet sugar production, characterized in that: The steam-electricity cogeneration method for beet sugar production adopts a system for steam-electricity cogeneration for beet sugar production, and the system for steam-electricity cogeneration for beet sugar production includes a desalted water tank, a third heat exchanger, a separation water tank, a water drying tower, a first heat exchanger and a shaft sealing device of a steam turbine, the desalted water tank is connected to the pipe side inlet of the third heat exchanger through a circulation pipeline and a pump body, the pipe side outlet of the third heat exchanger is connected to the desalted water tank through a reflux pipeline, the desalted water tank is connected to the separation water tank through a water supply pipeline and a pump, the water drying tower is connected to the pipe side inlet of the first heat exchanger through a first pipeline, and the first heat exchanger is connected to the pipe side outlet of the third heat exchanger through a reflux pipeline. The tube-side outlet of the heat exchanger is connected to the shell-side inlet of the third heat exchanger through a fourth pipeline, the shell-side outlet of the third heat exchanger is connected to the air-drying tower through a third pipeline, and the condensate outlet of the shaft seal device of the steam turbine is connected to the shell-side inlet of the first heat exchanger through a water inlet pipe; the air-drying tower is connected to the cooling water inlet of the slag cooler through a pipeline, and the hot water outlet of the slag cooler is connected to the fourth pipeline through a second pipeline; the water supply pipeline is connected to the second heat exchanger; and further includes: a temperature measuring module, which is arranged on the separation water tank, and is used to obtain the water supply temperature; a control module, which is used to adjust the energy supply of the second heat exchanger; The steam-electricity cogeneration method for beet sugar production comprises the following steps: S1: Desalted water in the desalted water tank after RO filtration and EDI filtration is sent to the tube side of the third heat exchanger through a circulation pipeline; S2: One path of cooling water in the air-drying tower is heated by condensed water of the turbine shaft seal device in the first heat exchanger, and the other path of cooling water in the air-drying tower is heated by the slag cooler. The two paths of hot water enter the shell side of the third heat exchanger to heat the desalted water, and the heated desalted water returns to the desalted water tank, and the cycle repeats in this way; S3: After the temperature of the desalted water in the desalted water tank rises to 80-85°C, the pump of the water supply pipeline is started to send the desalted water to the separation water tank and the boiler water supply pipeline for use; S4: A second heat exchanger is set in the water supply pipeline. When the temperature measurement module of the separation water tank detects that the temperature of the desalted water is lower than 75°C, high-temperature steam is introduced into the second heat exchanger to perform secondary heating on the desalted water to meet the requirements of the separation and sugar washing process.

2. The steam-electricity cogeneration method for beet sugar production according to claim 1, characterized in that: The water supply pipeline is also connected to a boiler water supply pipeline.

3. The steam-electricity cogeneration method for beet sugar production according to claim 2, characterized in that: The interior of the third heat exchanger is divided into a first cavity, a second cavity and a third cavity from bottom to top in sequence by two groups of tube sheets. The first cavity is connected to the third cavity through a heating tube uprightly arranged in the second cavity. The third cavity is divided into a cold water cavity and a hot water cavity by an isolating member. The third heat exchanger is provided with a tube side inlet communicating with the cold water cavity, the third heat exchanger is provided with a tube side outlet communicating with the hot water cavity, and the third heat exchanger is provided with a shell side inlet and a shell side outlet communicating with the second cavity.

4. The steam-electricity cogeneration method for beet sugar production according to claim 3, characterized in that: The isolation member comprises two groups of isolation plates, and an isolation cavity is formed between the two groups of isolation plates.

5. The steam-electricity cogeneration method for beet sugar production according to claim 4, characterized in that: The third heat exchanger is provided with a drain pipe communicating with the second cavity.

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