Citric acid production system for co-production of flash evaporation waste heat

Abstract

An evaporation system of the citric acid production system is a multi-effect system, a preheating part comprises a first-section preheater and a second-section preheater which are connected in series, and an outlet of the second-section preheater is sequentially communicated with a first-effect evaporator, a first-effect separator, a second-effect evaporator, a second-effect separator, a third-effect evaporator and a third-effect separator of the evaporation part. Materials separated by the triple-effect separator are conveyed out of the system through a discharging pump, and separated secondary steam enters a condenser of the condensation part; the dead steam is communicated with a hot side interface of the first-effect evaporator; the condensate water side of the first-effect evaporator is communicated with a condensate water tank, and an outlet of the condensate water tank is communicated with the second-section preheater through a condensate water extraction pump; condensed water outlets of the second-effect evaporator and the third-effect evaporator are respectively communicated with the first-section preheater through a second-effect condensed water pump and a third-effect condensed water pump; and a second-effect condensed water outlet and a third-effect condensed water outlet are formed in the first-section preheater. According to the utility model, the waste problem of waste heat is solved, and on the other hand, the operation cost of citric acid is saved.

Description

Technical Field

[0001] The utility model relates to citric acid production and fermentation industries, in particular to a flash evaporation waste heat co-production citric acid production system. Background Art

[0002] Citric acid is a typical organic acid, which is obtained through corn fermentation, crude extraction, and refined extraction. It can be widely used in food, medicine, chemical industry and other industries. The energy consumption of citric acid production process is very high, especially in the evaporation and crystallization stages. During the production process, a certain amount of low-temperature secondary steam will be generated in the flash evaporation stage, acidification stage, drying stage, etc. The heat of this secondary steam is currently being discharged or used as hot water, and the heat utilization rate is low. Based on a full understanding of the waste heat and citric acid evaporation characteristics, the utility model utilizes the flash evaporation waste heat to co-produce evaporated citric acid, which greatly saves the consumption of fresh steam and greatly reduces the operating cost. Utility Model Content

[0003] The utility model provides a citric acid production system with flash evaporation waste heat co-production, which utilizes the waste heat of flash evaporation in the citric acid boiling process to concentrate the ion exchange liquid, on the one hand, recovers the waste heat of flash evaporation, and on the other hand, saves the consumption of fresh steam in the evaporation process, thereby reducing the operating cost.

[0004] The technical solution adopted in this utility model is as follows:

[0005] A citric acid production system with flash evaporation waste heat co-production comprises an evaporation system, which is a multi-effect system, and has the following specific structure: the evaporation system comprises a preheating part, an evaporation part and a condensation part; the preheating part comprises a first-stage preheater and a second-stage preheater arranged in series, the outlet of the second-stage preheater is sequentially connected to the first-effect evaporator, the first-effect separator, the second-effect evaporator, the second-effect separator, the third-effect evaporator and the third-effect separator of the evaporation part, the material separated by the third-effect separator is transported out of the system by a discharge pump, and the separated secondary steam enters the condenser of the condensation part; the exhaust steam is connected to the hot side interface of the first-effect evaporator; the condensate side of the first-effect evaporator is connected to a condensate tank, and the outlet of the condensate tank is connected to the second-stage preheater through a condensate extraction pump; the condensate outlets of the second-effect evaporator and the third-effect evaporator are respectively connected to the first-stage preheater through a second-effect condensate pump and a third-effect condensate pump, and the first-stage preheater is provided with second-effect and third-effect condensate outlets.

[0006] The condensed water tank adjusts the discharge of the vacuum tail gas discharge port through the vacuum pump.

[0007] The first-effect evaporator adopts a low-pressure-drop evaporator.

[0008] The condenser adopts a low pressure drop condenser.

[0009] A secondary flash steam outlet is provided on the top of the liquefaction flash tank of the liquefaction flash system, and the secondary flash steam outlet is communicated with the hot side interface of the first-effect evaporator through a steam pipeline.

[0010] A water spray cooling device is provided at the secondary flash steam outlet, and the water spray cooling device is controlled by a regulating valve, and a secondary steam thermometer and a secondary steam pressure gauge are provided on the pipeline of the regulating valve.

[0011] The utility model uses the waste heat and waste gas in the cooking process as a heat source for refined evaporation and crystallization, which solves the problem of waste heat waste on the one hand and greatly saves the operating cost of citric acid on the other hand. The energy-saving effect is remarkable and the promotion and application prospects are broad.

[0012] The utility model is applied to the waste heat evaporation system of citric acid and can also be promoted and applied to industries such as fermentation of sugar alcohol.

[0013] The utility model can increase the concentration of the ionized liquid from about 46% to 73%, and the ionized liquid concentrated to 73% enters the subsequent crystallization system for further crystallization to obtain anhydrous citric acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the production flow chart of citric acid of the utility model;

[0015] Figure 2 This is a block diagram of the evaporation system of the utility model;

[0016] Figure 3 This is a block diagram of the flash evaporation system of the utility model;

[0017] Figure 2 In: E101 first stage preheater; E102 second stage preheater; ES201 first effect evaporator; V201 first effect separator; ES202 second effect evaporator; V202 second effect separator; ES203 third effect evaporator; V203 third effect separator; EC301 condenser; V101 condensate tank; P201 vacuum pump; P202 first effect condensate pump; P203 first effect feed pump; P211 second effect feed pump; P221 discharge pump; P212 second effect condensate pump; P222 third effect condensate pump; 1011 material inlet; 2012 flash secondary steam inlet; 2011 vacuum tail gas discharge port; 1012 second and third effect condensate outlet; 1022 first effect condensate outlet; 2031 concentrate outlet; 3011 cooling water inlet; 3012 Cooling water outlet; 3013 condenser condensate mixed outlet.

[0018] Figure 3Middle: V401 flash tank; P401 liquefied material extraction pump; LV01, cooling water regulating valve; TT01 secondary steam thermometer; PT secondary steam pressure gauge; 4011 flash material inlet; 4012 flash material outlet; 4013 secondary flash steam outlet. DETAILED DESCRIPTION

[0019] The utility model and its effects are described in detail below with reference to the accompanying drawings.

[0020] The citric acid production system includes raw material preparation, cooking, flash evaporation, fermentation, filtration, crude extraction, acid hydrolysis, ion exchange, evaporation, crystallization, drying, packaging and other systems. In the cooking and liquefaction flash evaporation system, flash exhaust steam of about 90-95°C is generated, and fresh steam is required in the evaporation system to concentrate the ion exchange liquid to near saturation. The utility model uses the exhaust steam of the cooking and liquefaction flash evaporation system in the evaporation system as an evaporation heat source to achieve energy-saving optimization.

[0021] The secondary steam temperature of liquefied flash evaporation is not high, about 95°C, the inlet temperature of the evaporation system is 50°C, and the feed concentration is about 46%. In order to match the characteristics of its heat source, combined with the physical properties of the evaporation process, the subsequent evaporation system adopts three effects. The evaporation temperatures of each effect are: 80°C for the first effect, 65°C for the second effect, and 48°C for the third effect. The feed concentration of the evaporation ion liquid is 46%, and the discharge concentration is 71%. The evaporated material enters the subsequent crystallization system for crystallization treatment. The material of the three-effect system flows downstream, and the discharge temperature of the last effect material is about 53°C, so there is no risk of saturated crystallization. The subsequent crystallization temperature is about 45°C, and the evaporation discharge temperature will not affect the subsequent crystallization operation.

[0022] like Figure 2A citric acid production system with flash evaporation waste heat co-production includes an evaporation system, which is a multi-effect system. The exhaust steam generated by the cooking system and the liquefaction flash evaporation system is used as the heat source of the evaporation system; the evaporation system includes a preheating part, an evaporation part and a condensation part; the exhaust steam generated by the cooking system and the flash evaporation system is used as the heat source of the evaporation system; the specific structure is: the evaporation system includes a preheating part, an evaporation part and a condensation part; the preheating part includes a first-stage preheater E101 and a second-stage preheater E102 arranged in series, and the outlet of the second-stage preheater E102 is connected in sequence to the first-effect evaporator ES201, the first-effect separator V201, the second-effect evaporator ES202, the second-effect separator V202, the third-effect evaporator ES203, The triple-effect separator V203, the material separated by the triple-effect separator V203 is transported out of the system by the discharge pump P221, and the separated secondary steam enters the condenser EC301 of the condensation part; the exhaust steam is connected to the hot side interface 2012 of the first-effect evaporator ES201; the condensate side of the first-effect evaporator ES201 is connected to the condensate tank V101, and the outlet of the condensate tank V101 is connected to the second-stage preheater E102 through the condensate extraction pump P202; the condensate outlets of the second-effect evaporator ES202 and the triple-effect evaporator ES203 are connected to the first-stage preheater E101 through the second-effect condensate pump P212 and the triple-effect condensate pump P222 respectively, and the first-stage preheater E101 is provided with second and third-effect condensate outlets 1012.

[0023] In addition to the above three-effect system, the evaporation system can also adopt single-effect, double-effect and quadruple-effect. The material can select the process according to the discharge requirements. The second-effect discharge can obtain a higher discharge temperature to ensure the energy consumption of subsequent crystallization. The third-effect discharge can also be used, but the temperature is lower. The third-effect discharge needs to consider the solubility of the material to avoid crystallization.

[0024] The evaporator adopts plate type, tube type or other forms. The evaporator can adopt rising film, falling film or ascending and descending film. The evaporation system adopts cocurrent, countercurrent or mixed flow.

[0025] The condensed water tank V101 adjusts the discharge of the vacuum tail gas discharge port 2011 through the vacuum pump P201. The vacuum pump P201 ensures the tank vacuum degree of -30kpa (G), which is variable frequency to adjust the pressure of the first effect heat source and ensure the smooth transportation of the waste heat steam.

[0026] The first-effect evaporator ES201 adopts a low-pressure drop evaporator to meet the requirements of secondary steam heat transfer and low pressure drop, and the hot side pressure drop needs to be controlled within 2Kpa.

[0027] In order to ensure the evaporation temperature of the triple effect, the condenser EC301 adopts a low pressure drop condenser. To ensure a higher vacuum degree of the system, the condenser pressure does not exceed 2Kpa. At the same time, the circulation inlet temperature is required not to exceed 30℃ and is sufficient.

[0028] like Figure 3 A secondary flash steam outlet 4013 is provided at the top of the flash tank V401 of the liquefaction flash evaporation system. The secondary flash steam outlet 4013 is connected to the hot side interface 2012 of the first-effect evaporator ES201 through a steam pipeline. The exhaust steam of the liquefaction flash evaporation system is used as the heat source of the evaporation system to achieve energy-saving optimization effect.

[0029] The flash temperature is controlled at about 95°C, and the slurry enters the flash tank from the flash material inlet 4011. The flash is controlled by the vacuum pump P201 at the end of the evaporator through the pressure connected to the flash tank.

[0030] In order to match the heat source parameters of the evaporation system, it may deviate from the operating point of the flash tank V401, so a water spray cooling device is set at the secondary flash steam outlet 4013. The flash tank flash pressure is about -17kpa (G), and the flash steam with a temperature of about 95°C is generated. The flash process is far away from the evaporation process, and the exhaust steam transportation distance is long. In order to meet the requirements of negative pressure operation and long-distance transportation, a vacuum system needs to be set at the hot side outlet of the first-effect evaporator to ensure the transportation of secondary steam and the guarantee of flash negative pressure through negative pressure operation. In order to ensure the adjustable flash temperature of the flash tank, a water spray cooling device is set in the flash tank, which is determined by the stability and pressure of the flash tank. The water spray cooling device is controlled by the regulating valve LV01, and the secondary steam thermometer TT01 and the secondary steam pressure gauge PT01 are set on the pipeline of the regulating valve LV01. By checking the temperature and pressure of the flash tank, the opening of the regulating valve LV01 is fed back to ensure the stable operation of the flash system. The main function of the water spray cooling device is to fine-tune the temperature of the flash secondary steam by spraying water under a certain vacuum degree. The slurry after flashing is pumped out by the liquefied material pumping pump P401 and discharged from the system through the flash material discharge port 4012.

[0031] The working process of the utility model is as follows: after the material enters the evaporation system from the material inlet 1011, it is preheated by the first-stage preheater E101 and the second-stage preheater E102, and then the temperature is raised to 75°C before entering the first-effect evaporator ES201, where it is heated and evaporated and then enters the first-effect separator V201 for gas-liquid separation. The concentrated material after separation is transported to the second-effect evaporator ES202 by the first-effect feed pump P203, and then enters the second-effect separator V202 for gas-liquid separation. The concentrated liquid after separation enters the third-effect evaporator ES203 by the second-effect feed pump P211, and then enters the third-effect separator V203 for separation. The concentration of the separated and concentrated material reaches 71%, and is output from the system by the discharge pump P221 to enter the subsequent crystallization system.

[0032] In order to reduce the overall energy consumption, a preheater is set up when the material enters the evaporation system. The preheater adopts two stages. The heat source of the first stage is the condensed water of the second-effect evaporator and the third-effect evaporator; the heat source of the second stage is the condensed water of the first-effect evaporator. The water pumped out by the second-effect condensed water pump P212 and the third-effect condensed water pump P222 is combined and enters the first-stage preheater E101. After preheating, the condensed water temperature is reduced to 55°C and then discharged from the system. The first-effect condensed water is sent to the second-stage preheater E102 through the first-effect condensed water pump P202. After heat exchange, the condensed water temperature is reduced to 65°C and then discharged from the system. The material temperature is raised to 75°C through two-stage heat exchange.

Claims

1. A citric acid production system with flash waste heat co-production, comprising an evaporation system, characterized in that: The evaporation system is a multi-effect system, and its specific structure is as follows: the evaporation system includes a preheating part, an evaporation part and a condensation part; the preheating part includes a first-stage preheater (E101) and a second-stage preheater (E102) arranged in series, and the outlet of the second-stage preheater (E102) is connected to the first-effect evaporator (ES201), the first-effect separator (V201), the second-effect evaporator (ES202), the second-effect separator (V202), the third-effect evaporator (ES203), and the third-effect separator (V203) of the evaporation part in sequence, and the material separated by the third-effect separator (V203) is transported out of the system by the discharge pump (P221), and the secondary steam after separation enters the condensation part The exhaust steam is connected to the hot side interface (2012) of the first-effect evaporator (ES201); the condensate side of the first-effect evaporator (ES201) is connected to the condensate tank (V101), and the outlet of the condensate tank (V101) is connected to the second-stage preheater (E102) through a condensate extraction pump (P202); the condensate outlets of the second-effect evaporator (ES202) and the third-effect evaporator (ES203) are connected to the first-stage preheater (E101) through a second-effect condensate pump (P212) and a third-effect condensate pump (P222), respectively, and the first-stage preheater (E101) is provided with second-effect and third-effect condensate outlets (1012).

2. A flash evaporation waste heat co-generation citric acid production system as claimed in claim 1, characterized in that: The condensed water tank (V101) adjusts the discharge of the vacuum tail gas discharge port (2011) through the vacuum pump (P201).

3. A flash evaporation waste heat co-generation citric acid production system as claimed in claim 1, characterized in that: The first-effect evaporator (ES201) adopts a low-pressure-drop evaporator.

4. A flash evaporation waste heat co-generation citric acid production system as claimed in claim 1, characterized in that: The condenser (EC301) adopts a low pressure drop condenser.

5. The flash evaporation waste heat co-generation citric acid production system according to claim 1, characterized in that: A secondary flash steam outlet (4013) is provided at the top of the liquefaction flash tank (V401) of the liquefaction flash system. The secondary flash steam outlet (4013) is connected to the hot side interface (2012) of the first-effect evaporator (ES201) through a steam pipeline.

6. A flash evaporation waste heat co-generation citric acid production system as claimed in claim 5, characterized in that: A water spray cooling device is provided at the secondary flash steam outlet (4013), and the water spray cooling device is controlled by a regulating valve (LV01). A secondary steam thermometer (TT01) and a secondary steam pressure gauge (PT01) are provided on the pipeline of the regulating valve (LV01).

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