Novel evaporation and concentration system

Abstract

The invention provides a novel evaporation and concentration system, which is used for concentrating a solution in an evaporation mode, and comprises a heater, which comprises a solution channel, a heating steam channel and an evaporation steam outlet, and is characterized in that the solution channel comprises a solution inlet, a solution flowing pipeline and a solution outlet; the heating steam channel comprises a heating steam inlet and a condensed water outlet and is configured to enable heating steam to be in physical contact with the outer wall of the solution flowing pipeline so as to heat the solution flowing in the solution flowing pipeline, and the evaporation steam outlet is connected with the solution channel so as to enable the solution flowing in the solution flowing pipeline to be heated. The evaporation steam generated by heating and evaporating the solution is discharged; and the steam pressurizing device is used for pressurizing the evaporation steam and supplying at least one part of the pressurized evaporation steam to the heating steam inlet as the heating steam. According to the invention, while the concentration of the solution is realized, the waste heat of the dead steam in the dead steam can be recovered to the greatest extent, and the full utilization of energy is realized.

Description

Technical Field

[0001] The invention relates to a novel evaporation concentration system, which is used for concentrating a solution by evaporation. Background Art

[0002] The concentration of the solution is usually carried out using a heating evaporation concentration system, that is, using a heating method to vaporize and remove part of the solvent in the solution to increase the concentration of the solution. Common falling film evaporation and rising film evaporation are generally used. The following is an introduction to the falling film evaporation system as an example.

[0003] Figure 1 Schematic diagram of the falling film evaporation system of the prior art. Figure 1 As shown, a typical falling film evaporation system includes a heater 11, an evaporator 12, a condenser 13 and a secondary steam condensate pump 14. Here, the typical heater 11 is a surface shell and tube heat exchanger. In the falling film evaporation system, saturated steam is usually used as the heat source for the evaporation and concentration production process, generally referred to as raw steam or new steam. The raw steam flows into the heater 11 from the heating steam inlet 112, and the dilute solution (material before concentration) 115 flows into the heater 11 from the material inlet 111, flows from top to bottom along the inner wall of the pipe, and is heated by the steam on the outer wall of the pipe. After the water in the dilute solution 115 is heated, it vaporizes into secondary steam 122, flows from bottom to top in the evaporator 12, and separates water and steam after passing through the demister 121. The secondary steam 122 with improved dryness flows into the condenser 13 to exchange heat with cooling water, and the low-temperature cooling water 132 absorbs heat to become high-temperature cooling water 131. The secondary steam 122 is cooled into secondary steam condensate 123, which is recycled through the secondary steam condensate pump 14. At the same time, the raw steam serving as a heat source is converted into condensed water after heat exchange and flows out from the steam condensed water outlet 113 , and the dilute solution 115 is dehydrated to become a concentrated solution 116 and is discharged from the material outlet 114 .

[0004] The above describes the basic working principle of the single-effect falling film evaporation system. Theoretically, 1 kg of heating steam can evaporate about 1 kg of water. However, due to heat loss, in fact, more than 1 kg of heating steam is required to evaporate 1 kg of water. In order to improve the efficiency of thermal energy utilization, a multi-effect evaporation system has been optimized. When changing from single effect to double effect, heating steam can be saved by about 50%; and when changing from four effects to five effects, heating steam can only be saved by 10%. In engineering, 2 to 3 effects are generally used, and the maximum is 6 effects. The following table shows the efficiency of heating steam in various cases from single effect to five effects.

[0005]

[0006] Whether in a single-effect evaporation system or a multi-effect evaporation system, the secondary steam produced in the last effect, i.e., exhaust steam, has a very low energy level, and low-quality energy is difficult to be directly utilized. Therefore, circulating cooling water is usually used for condensation, and the waste heat in the exhaust steam is not utilized, and this part of the heat is eventually dissipated into the atmosphere.

[0007] Therefore, although the multi-effect evaporation system improved and optimized from the single-effect evaporation system has increased the ratio of tons of water / ton of steam, the energy utilization rate is about 10%, which is still at a very low level. Summary of the invention

[0008] The present invention is completed in view of the above situation, and its purpose is to provide a new evaporation concentration system, which can recover the waste heat of exhaust steam to the maximum extent while achieving concentration of the solution, thereby achieving full utilization of energy.

[0009] The novel evaporation concentration system of the present invention is used to concentrate a solution by evaporation, and is characterized in that it comprises: a heater, which comprises a solution channel, a heating steam channel and an evaporation steam outlet, wherein the solution channel comprises a solution inlet, a solution flow pipe and a solution outlet, the heating steam channel comprises a heating steam inlet and a condensed water outlet, and is configured so that the heating steam can physically contact the outer wall of the solution flow pipe to heat the solution flowing in the solution flow pipe, and the evaporation steam outlet is connected to the solution channel for discharging the evaporation steam generated by the heated evaporation of the solution; and a steam boosting device, which boosts the evaporation steam and provides at least a portion of the boosted evaporation steam to the heating steam inlet as the heating steam.

[0010] In the above-mentioned novel evaporation concentration system, it includes a plurality of heaters connected in series, wherein the evaporation steam generated by the heater located upstream is provided as the heating steam to the heating steam inlet of the heater located downstream, the evaporation steam generated by the heater located most downstream is provided to the steam boosting device, and the steam boosting device provides at least a portion of the boosted evaporation steam as the heating steam to the heating steam inlet of the heater located most upstream.

[0011] In the novel evaporation concentration system, the solution outlet of the heater located upstream is connected to the solution inlet of the heater located downstream.

[0012] In the novel evaporation concentration system, the solution outlet of the heater located downstream is connected to the solution inlet of the heater located upstream.

[0013] In the above-mentioned novel evaporation concentration system, the steam boosting device includes a booster and a driving unit, and the driving unit is used to drive the booster to boost the evaporation steam.

[0014] In the above novel evaporation and concentration system, the driving unit is an electric motor.

[0015] In the above-mentioned novel evaporation concentration system, the driving unit further comprises a traction steam turbine connected in series with the electric motor via a clutch, and the traction steam turbine is driven by the steam pressurized by the steam booster device.

[0016] In the above-mentioned novel evaporation concentration system, the driving unit is a traction steam turbine, and the traction steam turbine is driven by external steam.

[0017] In the above novel evaporation and concentration system, the driving unit further comprises an electric motor connected in series with the traction steam turbine via a clutch.

[0018] In the above-mentioned novel evaporation concentration system, a plurality of steam boosting devices are arranged in series, and their number is less than or equal to the number of the heaters. One steam boosting device is respectively arranged corresponding to each of at least a part of the heaters, and at least a part of the evaporation steam boosted by the steam boosting device corresponding to the heater is provided as the heating steam to the heating steam inlet of the corresponding heater.

[0019] The novel evaporation concentration system further includes a demister located between the evaporation steam outlet and the steam booster device, and provides the evaporation steam to the steam booster device after removing water from the evaporation steam.

[0020] The specific contents of the present invention will be described below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of a falling film evaporation system in the prior art.

[0022] Figure 2 It is a schematic diagram of the evaporation concentration system of the present invention.

[0023] Figure 3 It is a schematic diagram of an embodiment (cocurrent) of the evaporation concentration system of the present invention.

[0024] Figure 4 It is a schematic diagram of another embodiment (countercurrent) of the evaporation concentration system of the present invention.

[0025] Figure 5 It is a schematic diagram of another embodiment of the evaporation concentration system of the present invention.

[0026] Figure 6 This is a diagram illustrating the operating effect of a falling film evaporation system of the prior art as a comparative example.

[0027] Figure 7 It is a diagram illustrating the operating effect of the evaporation concentration system of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as being limited to the embodiments described herein, which are instead provided for a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0029] Figure 2 It is a schematic diagram of the evaporation concentration system of the present invention. Figure 2 What is shown is the so-called "multi-effect evaporation system", that is, a dehydration system that improves the efficiency of heat energy utilization by connecting multiple evaporation devices 1 to 4 in series. Each evaporation device in the system is called an effect, the evaporation device that flows with raw steam is called the first effect, the evaporation device that uses the secondary steam generated by the first effect evaporation device as a heat source is called the second effect, and so on. The multi-effect evaporation system is a series evaporation process that uses the secondary steam of the previous effect as the heating steam of the next effect, thereby reducing the use of raw steam and improving the efficiency of heat energy utilization. Here, although the figure illustrates the case where four evaporation devices are connected in series in the system as an example, as described below, the present invention is also applicable to the case where there is only one evaporation device (single effect) and multiple evaporation devices are connected in series (multiple effects) in the system.

[0030] Here, a plurality of evaporation devices connected in series are shown in the form of a schematic diagram. Specifically, each evaporation device has the same structure, and its structure can be referred to as Figure 1 As shown, it includes a heater 11 and an evaporator 12, but does not include a condenser 13 and a secondary steam condensate pump 14, wherein the heater 11 and the evaporator 12 constitute the evaporation device of the present invention. Here, the typical heater 11 is a surface shell and tube heat exchanger. Figure 1The similarity of the falling film evaporation system of the prior art shown is that the raw steam first flows in from the heating steam inlet 112 of the heater 11 of the first-effect heating device 1, and at the same time, the dilute solution (pre-concentration material) 115 flows into the heater 11 from the material inlet 111 of the heater 11 of the first-effect heating device 1, and flows from top to bottom along the inner wall of the pipeline. The dilute solution 115 flowing along the inner wall of the pipeline is heated by the steam on the outer wall of the pipeline, and the water in the dilute solution 115 is vaporized into secondary steam (evaporation steam) 122, which flows from bottom to top in the evaporator 12. After the secondary steam 122 passes through the demister 121 in the evaporator 12, the water and steam are separated to become the secondary steam 122 with improved dryness. Among them, the secondary steam 122 generated by the first-effect heating device 1 flows into the second-effect heating device 2 located downstream thereof as heating steam, and so on. In addition, the difference from the prior art is that, in the present invention, the secondary steam 42 generated by the final effect heating device 4 flows into the steam booster device 7 described later, and after being boosted by the steam booster device 7, at least a portion of it flows back into the heating steam inlet 112 of the heater 11 of the first effect heating device 1 as raw steam. Here, although it is described that the system includes an evaporator, the role of the evaporator here is to separate the water in the steam through the demister 121 arranged inside, so as to prevent the water droplets from impacting the subsequent steam booster device 7, but from the perspective of solving the technical problem of the present invention, this structure is not necessary.

[0031] The structure of the steam booster 7 will be described in detail below. The steam booster 7 includes: a steam pump (booster) 71, which is used to boost the secondary steam 42 generated by the final effect heater 4; an electric motor 73, which is connected to the steam pump 71 through a coupling 72 to provide driving force for the steam pump 71; and a driving steam turbine 75, which is connected to the electric motor 73 through a clutch 74 to provide driving force for the steam pump 71 together with the electric motor 73. Here, in this embodiment, the electric motor 73 is shown as the main driving unit, and the driving steam turbine 75 is connected to the electric motor 73 through the clutch 74 so as to provide driving force for the steam pump 71 together with the electric motor 73 as an auxiliary driving unit. However, the present invention is not limited to this, and it can also be a mode in which the driving steam turbine 75 is connected to the steam pump 71 through the coupling 72, and the electric motor 73 is connected to the electric motor 73 through the clutch 74. In this connection mode, the traction steam turbine 75 serves as the main driving unit, and the electric motor 73 is connected to the electric motor 73 through the clutch 74 in a switchable manner, thereby serving as an auxiliary driving unit and providing driving force to the steam pump 71 together with the traction steam turbine 75.

[0032] In addition, the electric motor 73 and the traction steam turbine 75 as the driving unit are both related devices sold on the market. In addition, as a steam source for driving the steam turbine 75 to operate, Figure 2The compressed steam 702 is shown as being generated by the steam booster 7 compressing the secondary steam 701, but the present invention is not limited thereto and may also be a steam source from an external source.

[0033] In addition, the steam pump is a booster used to pressurize steam, and various types of compressors may be used, such as a piston compressor, a rotary compressor, a screw compressor, a centrifugal compressor, an axial flow compressor, a mixed flow compressor, and a jet compressor.

[0034] According to the novel evaporation and concentration system of the present invention, it is only necessary to flow high-parameter raw steam from outside the system as the first-effect raw steam when the system is started. When the system starts to operate normally, all the exhaust steam 701 of the last effect is pressurized and upgraded to become the upgraded high-parameter steam 702. The upgraded high-parameter steam 702 has the same pressure and temperature as the first-effect heating steam 11, thereby replacing the first-effect heating steam 11 and starting the next multi-effect evaporation cycle. At this point, the system no longer needs to flow raw steam from outside the system. The novel evaporation and concentration system of the present invention turns all the exhaust steam of the last effect into treasure, and realizes the self-circulation and quality balance of the total amount of medium in the whole process.

[0035] Figure 3 Schematic diagram of an embodiment of the evaporation concentration system of the present invention. The secondary steam 115 generated by the upstream heater is provided as heating steam to the heating steam inlet 122 of the downstream heater, the secondary steam 71 generated by the most downstream heater is provided to the steam booster 7, and the steam booster 7 provides at least a portion of the boosted secondary steam 72 as heating steam to the heating steam inlet of the most upstream heater. In addition, the solution outlet of the upstream heater is connected to the solution inlet of the downstream heater, that is, in this embodiment, the flow direction of the solution is the same as the flow direction of the secondary steam.

[0036] Figure 4 Schematic diagram of another embodiment of the evaporation concentration system of the present invention. Figure 3 The connection structure is the same as that of the heater, except that the solution outlet of the downstream heater is connected to the solution inlet of the upstream heater, that is, in this embodiment, the flow direction of the solution is opposite to the flow direction of the secondary steam.

[0037] here, Figure 3 and Figure 4 The only difference is that the flow direction of the solution is different from that of the steam. In the process of changing from a dilute solution to a concentrated solution, the viscosity of the solution is different at different concentrations, and the difficulty of dehydration is different. Therefore, the flow rate of heating steam for dehydration of each effect evaporator in the multi-effect evaporation system can be adjusted, which is a more flexible and efficient evaporation concentration system.

[0038] Figure 5 Schematic diagram of another embodiment of the evaporation concentration system of the present invention. This figure shows an embodiment of the evaporation concentration system of the present invention with double effect. In this embodiment, Figure 2 The difference of the evaporation concentration system of the present invention shown is that a group of steam boosting devices are provided corresponding to each effect of the evaporation device, and the steam boosted by the steam boosting device corresponding to each effect of the evaporation device is input into the evaporation device of the effect as a part of the raw steam. As mentioned above, the present invention has no limitation on the number of effects of the evaporation device, and the number of steam boosting devices may not correspond to the number of effects of the evaporation device, that is, the number of steam boosting devices may be equal to or less than the number of effects of the evaporation device. According to this embodiment, the steam is boosted and divided to provide different evaporation devices, that is, the input steam flow rate of each evaporation device in the "multi-effect evaporation system" can be adjusted so as to effectively dehydrate at a concentration that is easy to dehydrate (different concentrations have different viscosities).

[0039] Figure 6 This is a diagram illustrating the operating effect of a falling film evaporation system of the prior art as a comparative example. Figure 6 What is shown in FIG. 1 is a six-effect evaporation system in the prior art.

[0040] Table 1 shows an example of comparative data of aluminum hydroxide solution before and after evaporation by a falling film evaporation system of the prior art.

[0041]

Table 1

[0042]

[0043] Based on the above example, the evaporation concentration dehydration quality is 900×1.26-680×1.36=209t / h. At this time, assuming that the evaporation station uses steam, the pressure is 0.4MPa, the temperature is 144℃, and the flow rate is 45t / h. At this time, the steam enthalpy value is 2739kj / kg. 45t / h steam ÷ 209t / h dehydration = 0.215 tons of steam / ton of water. Compared with the single-effect falling film evaporation system, the six-effect evaporation system has achieved lower energy consumption, but the secondary steam generated by the last effect has not been utilized, and there is still room for optimization.

[0044] like Figure 6 As shown in Table 2, the exhaust steam temperature of the six-effect evaporator is about 60℃, and the exhaust steam enthalpy is 2600kj / kg. As shown in Table 2, the secondary steam of the last effect is cooled, and the cooling system parameters are: circulating pump inlet pressure 0.33MPa, cooling water pressure after the pump 0.6MPa, flow rate 2200m3 / h, low temperature cooling water temperature 35℃, and high temperature cooling water temperature 47℃.

[0045]

Table 2

[0046]

[0047] The secondary steam mass flow rate of the six-effect evaporator is about 42t / h.

[0048] In the current system, the steam from the first effect is used from the pressure of 0.4MPa, the temperature of 144℃, the enthalpy of 2739kj / kg to the pressure of 0.02MPa, the temperature of 60℃, the enthalpy of 2600kj / kg. The enthalpy difference is 139kj / kg, and the waste heat is 2600kj / kg.

[0049]

Table 3

[0050]

[0051] As shown in Table 3, when evaporating 209 t / h of water, the evaporation concentration system consumes 34.24 MW of energy.

[0052] Figure 7 It is a diagram illustrating the operating effect of the evaporation concentration system of the present invention.

[0053]

Table 4

[0054]

[0055] like Figure 7 As shown, when 61t / h of steam at 0.4MPa and 200℃ is produced, 12600kw of electricity is consumed. It is estimated that when 45t / h of steam at 0.4MPa and 200℃ is produced, 9500kw of electricity is consumed. When 209t / h of water is evaporated (that is, when 45t / h of steam at 0.4MPa and 200℃ is input into the first-effect evaporation device), the evaporation concentration system consumes 9.5MW of energy, which is 70% less than the 34.24MW of energy consumed by the evaporation concentration system in the prior art.

[0056] In summary, the present invention provides a novel evaporation concentration system, the remarkable feature of which is that the energy consumption of the evaporation concentration system can be greatly reduced.

[0057] The above description is only a preferred embodiment of the present invention and an explanation of the technical principles used. Those skilled in the art should understand that the disclosure scope involved in the present invention is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present invention (but not limited to) by each other.

Claims

1. A novel evaporation concentration system, used to concentrate a solution by evaporation, characterized in that: include: A heater, comprising a solution channel, a heating steam channel and an evaporation steam outlet, wherein the solution channel comprises a solution inlet, a solution flow pipe and a solution outlet, the heating steam channel comprises a heating steam inlet and a condensed water outlet, and is configured so that the heating steam can physically contact the outer wall of the solution flow pipe to heat the solution flowing in the solution flow pipe, and the evaporation steam outlet is connected to the solution channel for discharging evaporation steam generated by heating and evaporation of the solution; as well as A steam boosting device boosts the pressure of the evaporation steam and provides at least a portion of the boosted evaporation steam as the heating steam to the heating steam inlet.

2. The novel evaporation concentration system according to claim 1, characterized in that: comprising a plurality of said heaters connected in series, wherein the evaporative steam generated by the heater located upstream is provided as the heating steam to the heating steam inlet of the heater located downstream, the evaporative steam generated by the heater located most downstream is provided to the steam boosting device, and the steam boosting device provides at least a portion of the boosted evaporative steam as the heating steam to the heating steam inlet of the heater located most upstream.

3. The novel evaporation concentration system according to claim 2, characterized in that: The solution outlet of the heater located upstream is connected to the solution inlet of the heater located downstream.

4. The novel evaporation concentration system according to claim 2, characterized in that: The solution outlet of the heater located downstream is connected to the solution inlet of the heater located upstream.

5. The novel evaporation concentration system according to claim 1, characterized in that: The steam boosting device comprises a booster and a driving unit, wherein the driving unit is used to drive the booster to boost the evaporation steam.

6. The novel evaporation concentration system according to claim 5, characterized in that: The driving unit is an electric motor.

7. The novel evaporation concentration system according to claim 6, characterized in that: The drive unit also includes a traction steam turbine connected in series with the motor through a clutch, The traction steam turbine is driven by the steam pressurized by the steam booster.

8. The novel evaporation concentration system according to claim 5, characterized in that: The driving unit is a steam turbine. The traction steam turbine is driven by external steam.

9. The novel evaporation concentration system according to claim 8, characterized in that: The drive unit also includes an electric motor connected in series with the traction steam turbine via a clutch.

10. The novel evaporation concentration system according to claim 2, characterized in that: The steam booster devices are arranged in series in multiple numbers, and their number is less than or equal to the number of the heaters. One steam booster device is arranged corresponding to each of at least a part of the heaters, and at least a part of the evaporated steam boosted by the steam booster device corresponding to the heater is provided as the heating steam to the heating steam inlet of the corresponding heater.

11. The novel evaporation concentration system according to any one of claims 1 to 10, characterized in that: It also includes a demister, which is located between the evaporation steam outlet and the steam booster device, and provides the evaporation steam to the steam booster device after removing water from the evaporation steam.

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