A novel evaporation concentration system

Abstract

The utility model provides a novel evaporation concentration system for concentrating solution through evaporation mode, comprising: 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 pipeline and a solution outlet, the heating steam channel comprises a heating steam inlet and a condensed water outlet, and is configured to enable the heating steam to physically contact the outer wall of the solution flow pipeline to heat the solution flowing in the solution flow pipeline, the evaporation steam outlet is connected with the solution channel for discharging evaporation steam generated by heating and evaporation of the solution; and a steam pressurizing device, which pressurizes the evaporation steam and provides at least part of the pressurized evaporation steam to the heating steam inlet as heating steam. The utility model can realize concentration of the solution while recovering the waste steam waste heat in the waste steam to the maximum extent, thereby achieving full utilization of energy.

Description

Technical Field

[0001] This utility model relates to a novel evaporation and concentration system for concentrating solutions through evaporation. Background Technology

[0002] Solution concentration is typically achieved using heated evaporation systems, which involve heating the solution to vaporize and remove some of the solvent, thereby increasing the solution's concentration. Common methods include falling film evaporation and rising film evaporation; the following explanation will focus on falling film evaporation as an example.

[0003] Figure 1 This is a schematic diagram of a falling film evaporation system using existing technology. (Example:) 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 heater 11 is typically a surface-type shell-and-tube heat exchanger. In a falling film evaporation system, saturated steam is usually used as the heat source for the evaporation and concentration process, generally referred to as live steam or fresh steam. Live 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, flowing from top to bottom along the inner wall of the pipe and being 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, which flows from bottom to top in the evaporator 12. After passing through the demister 121, the water and steam are separated. The secondary steam 122, with increased dryness, flows into the condenser 13 to exchange heat with the cooling water. The low-temperature cooling water 132 absorbs heat and becomes high-temperature cooling water 131. The secondary steam 122 is cooled into secondary steam condensate 123, which is then recovered and reused by the secondary steam condensate pump 14. Meanwhile, the live steam, which serves as a heat source, is converted into condensate after heat exchange and flows out from the steam condensate outlet 113. The dilute solution 115 is dehydrated and becomes a concentrated solution 116, which is discharged from the material outlet 114.

[0004] The basic working principle of a single-effect falling film evaporation system has been described above. Theoretically, 1 kg of heating steam can evaporate approximately 1 kg of water. However, due to heat loss, the actual amount of heating steam required to evaporate 1 kg of water exceeds 1 kg. To improve thermal energy utilization efficiency, multi-effect evaporation systems have been developed through optimization. When converting from a single-effect to a double-effect system, approximately 50% of the heating steam can be saved; while when converting from a four-effect to a five-effect system, only 10% of the heating steam can be saved. In engineering, 2 to 3 effects are commonly used, with a maximum of 6 effects. The following table shows the heating steam utilization efficiency under various conditions from single-effect to five-effect.

[0005]

[0006] Whether it is a single-effect evaporation system or a multi-effect evaporation system, the secondary steam produced by the last effect, i.e. the exhaust steam, has a very low energy level. Since low-quality energy is difficult to utilize directly, circulating cooling water is usually used for condensation. The residual 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, which is an improvement and optimization of the single-effect evaporation system, increases the ratio of ton water to ton steam, its energy utilization rate of about 10% is still at a very low level. Utility Model Content

[0008] This invention was made in view of the above circumstances, and its purpose is to provide a novel evaporation and concentration system that can concentrate the solution while maximizing the recovery of waste heat from the exhaust steam, thereby achieving full utilization of energy.

[0009] This invention discloses a novel evaporation and concentration system for concentrating a solution through evaporation. It is characterized by comprising: a heater, which includes a solution channel, a heating steam channel, and an evaporation steam outlet; wherein the solution channel includes a solution inlet, a solution flow pipe, and a solution outlet; the heating steam channel includes a heating steam inlet and a condensate outlet, and is configured such 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; the evaporation steam outlet is connected to the solution channel for discharging the evaporation steam generated by the heating and evaporation of the solution; and a steam pressurization device, which pressurizes the evaporation steam and provides at least a portion of the pressurized evaporation steam as the heating steam to the heating steam inlet.

[0010] In the above-described novel evaporation and concentration system, a plurality of heaters are connected in series. The evaporated steam generated by the upstream heater is provided as heating steam to the heating steam inlet of the downstream heater. The evaporated steam generated by the downstream heater is provided to the steam booster, and the steam booster provides at least a portion of the boosted evaporated steam as heating steam to the heating steam inlet of the upstream heater.

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

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

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

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

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

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

[0017] In the aforementioned novel evaporation and concentration system, the drive unit also includes an electric motor connected in series with the driven steam turbine via a clutch.

[0018] In the above-mentioned novel evaporation and concentration system, multiple steam booster devices are connected in series, and their number is less than or equal to the number of heaters. Each of the heaters is provided with a steam booster device corresponding to at least a portion of the heaters. At least a portion of the evaporating steam boosted by the steam booster device corresponding to the heater is provided as heating steam to the heating steam inlet of the corresponding heater.

[0019] The novel evaporation and concentration system described above also includes a demister, which is located between the evaporation steam outlet and the steam booster, and provides the evaporation steam to the steam booster after removing water.

[0020] The specific details of this utility model will be described below in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

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

[0022] Figure 2 This is a schematic diagram of the evaporation and concentration system of this utility model.

[0023] Figure 3 This is a schematic diagram of one embodiment (co-current) of the evaporation and concentration system of this utility model.

[0024] Figure 4 This is a schematic diagram of another embodiment (countercurrent) of the evaporation and concentration system of this utility model.

[0025] Figure 5 This is a schematic diagram of another embodiment of the evaporation and concentration system of this utility model.

[0026] Figure 6 This diagram illustrates the operational performance of a conventional falling film evaporation system as a comparative example.

[0027] Figure 7 This is a diagram illustrating the operation of the evaporation and concentration system of this utility model. Detailed Implementation

[0028] The present invention will now be described in more detail with reference to the accompanying drawings. While some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0029] Figure 2 This is a schematic diagram of the evaporation and concentration system of this utility model. Figure 2 The diagram shows a so-called "multi-effect evaporation system," which is a dehydration system that improves thermal efficiency by connecting multiple evaporation devices 1 to 4 in series. Each evaporation device in the system is called an effect; the evaporation device that receives live steam is called the first effect; the evaporation device that uses the secondary steam generated by the first effect 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 from the previous effect as the heating steam for the next effect, thereby reducing the amount of live steam used and improving thermal efficiency. Although the diagram illustrates a system with four evaporation devices connected in series, as described below, this invention is also applicable to systems with only one evaporation device (single-effect) and systems with multiple evaporation devices connected in series (multi-effect).

[0030] Here, multiple evaporators connected in series are represented in schematic form. Specifically, each evaporator has the same structure, and its structure can be referenced. Figure 1 As shown, the device includes a heater 11 and an evaporator 12, but excludes the condenser 13 and the secondary steam condensate pump 14. The heater 11 and evaporator 12 constitute the evaporation apparatus of this invention. Here, the typical heater 11 is a surface-type shell-and-tube heat exchanger. [The last sentence appears to be incomplete and possibly contains errors. It can be omitted from the translation.] Figure 1The common feature of the prior art falling film evaporation system shown is that live steam first flows in from the heating steam inlet 112 of the heater 11 of the first-effect heating device 1, while dilute solution (material before concentration) 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 pipe. The dilute solution 115 flowing along the inner wall of the pipe is heated by the steam on the outer wall of the pipe, and the water in the dilute solution 115 vaporizes 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, becoming secondary steam 122 with improved dryness. The secondary steam 122 generated by the first-effect heating device 1 flows as heating steam into the second-effect heating device 2 located downstream, and so on. Furthermore, unlike existing technologies, in this 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 pressurized by the steam booster device 7, at least a portion of it flows back as live steam into the heating steam inlet 112 of the heater 11 of the first-effect heating device 1. Here, although it is stated that the system includes an evaporator, the evaporator's function is to separate water from the steam through an internal demister 121, thereby preventing water droplets from impacting the subsequent steam booster device 7. However, from the perspective of solving the technical problem of this invention, this structure is not essential.

[0031] The structure of the steam booster device 7 will be described in detail below. The steam booster device 7 includes: a steam pump (booster) 71 for boosting the secondary steam 42 generated by the final-effect heater 4; an electric motor 73 connected to the steam pump 71 via a coupling 72 to provide driving force to the steam pump 71; and a drive turbine 75 connected to the electric motor 73 via a clutch 74 to provide driving force to the steam pump 71 together with the electric motor 73. Here, this embodiment shows the electric motor 73 as the main drive unit, and the drive turbine 75 connected to the electric motor 73 via the clutch 74 in a disengaged manner, thus serving as an auxiliary drive unit to provide driving force to the steam pump 71 together with the electric motor 73. However, this invention is not limited to this; it is also possible for the drive turbine 75 to be connected to the steam pump 71 via the coupling 72, and the electric motor 73 to be connected to the electric motor 73 via the clutch 74. In this connection method, the turbine 75 serves as the main drive unit, and the motor 73 is connected to the turbine 75 via a clutch 74, thus serving as an auxiliary drive unit to provide driving force to the steam pump 71 together with the turbine 75.

[0032] Furthermore, the electric motor 73 and the driven steam turbine 75, which serve as the drive unit, are commercially available components. Additionally, the steam source for driving the driven steam turbine 75 is... Figure 2The diagram shows compressed steam 702 generated after the secondary steam 701 is compressed by the steam booster 7, but the present invention is not limited to this and may also be from an external steam source.

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

[0034] According to the novel evaporation and concentration system of this invention, only high-parameter live steam needs to flow in from outside the system during system startup as the live steam for the first effect. Once the system is running normally, the exhaust steam 701 from the last effect is pressurized and upgraded into high-parameter steam 702. The pressure and temperature of the upgraded high-parameter steam 702 are the same as the heating steam 11 of the first effect, thus replacing the heating steam 11 of the first effect and starting the next multi-effect evaporation cycle. Therefore, this system no longer needs to draw in live steam from outside the system. This novel evaporation and concentration system of this invention turns all the exhaust steam from the last effect into valuable resources, achieving self-circulation and mass balance of the total amount of media throughout the entire process.

[0035] Figure 3 This is a schematic diagram of one embodiment of the evaporation and concentration system of this utility model. Secondary steam 115 generated by the upstream heater is supplied as heating steam to the heating steam inlet 122 of the downstream heater. Secondary steam 71 generated by the downstream heater is supplied to the steam booster 7, and the steam booster 7 supplies at least a portion of the pressurized secondary steam 72 as heating steam to the heating steam inlet of the upstream heater. Furthermore, 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 This is a schematic diagram of another embodiment of the evaporation and concentration system of this utility model. The specific connection structure is as follows... Figure 3 The connection structure is the same, except that the solution outlet of the downstream heater is connected to the solution inlet of the upstream heater. In other words, 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 the direction of solution flow versus steam flow. During the process of a solution changing from a dilute to a concentrated solution, the viscosity and dehydration difficulty vary at different concentrations. Therefore, in a multi-effect evaporation system, the flow rate of heating steam for dehydration in each evaporator can be adjusted, making it a more flexible and efficient evaporation and concentration system.

[0038] Figure 5 This is a schematic diagram of another embodiment of the evaporation and concentration system of this utility model. The figure shows an embodiment of a double-effect evaporation and concentration system of this utility model. In this embodiment, with... Figure 2 The difference in the evaporation and concentration system of this invention is that a set of steam booster devices is provided for each evaporation unit with each effect. The steam boosted by the steam booster device corresponding to each effect is input into the evaporation unit of that effect as part of the live steam. As mentioned above, this invention does not limit the number of effects of the evaporation unit, and the number of steam booster devices may not correspond to the number of effects of the evaporation unit; that is, the number of steam booster devices can be equal to or less than the number of effects of the evaporation unit. According to this embodiment, the pressurized steam is distributed to different evaporation units, that is, in the "multi-effect evaporation system", the input steam flow rate of each stage of the evaporation unit can be adjusted to achieve effective dehydration at concentrations that are easy to dehydrate (different concentrations have different viscosities).

[0039] Figure 6 This diagram illustrates the operational performance of a conventional falling film evaporation system as a comparative example. Figure 6 The image shows a six-effect evaporation system in the prior art.

[0040] Table 1 shows an example of comparative data before and after evaporation of aluminum hydroxide solution using a conventional falling film evaporation system.

[0041] Table 1

[0042]

[0043] Based on the above example, the evaporation, concentration, and dehydration mass is 900 × 1.26 - 680 × 1.36 = 209 t / h. At this point, assuming the evaporation station uses steam at a pressure of 0.4 MPa, a temperature of 144℃, and a flow rate of 45 t / h, the steam enthalpy is 2739 kJ / kg. 45 t / h steam ÷ 209 t / h dehydration = 0.215 tons of steam / ton of water. Compared to a single-effect falling film evaporation system, although the six-effect evaporation system has achieved lower energy consumption, the secondary steam generated in the last effect is not yet utilized, indicating room for optimization.

[0044] like Figure 6 As shown, the temperature of the secondary exhaust steam discharged from the sixth-effect evaporator is around 60℃, at which point the enthalpy of the exhaust steam is 2600 kJ / kg. Referring to Table 2, the secondary steam in the last effect is cooled. The cooling system parameters are: circulating pump inlet pressure 0.33 MPa, post-pump cooling water pressure 0.6 MPa, flow rate 2200 m³ / 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 approximately 42 t / h.

[0048] In the current system, the generated steam from the first effect is utilized from a pressure of 0.4 MPa, a temperature of 144 °C, and an enthalpy of 2739 kJ / kg to a pressure of 0.02 MPa, a temperature of 60 °C, and an enthalpy of 2600 kJ / kg. The utilized enthalpy difference is 139 kJ / kg, resulting in a waste heat of 2600 kJ / kg.

[0049] Table 3

[0050]

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

[0052] Figure 7 This is a diagram illustrating the operation of the evaporation and concentration system of this utility model.

[0053] Table 4

[0054]

[0055] like Figure 7 As shown, producing 61 t / h of steam at 0.4 MPa and 200°C consumes 12600 kW of electricity. It is estimated that producing 45 t / h of steam at 0.4 MPa and 200°C consumes 9500 kW. When evaporating 209 t / h of water (that is, when the single-effect evaporator inputs 45 t / h of steam at 0.4 MPa and 200°C), the evaporation concentration system consumes 9.5 MW of energy, which is 70% less than the 34.24 MW consumed by existing evaporation concentration systems.

[0056] In summary, this utility model provides a novel evaporation and concentration system, the significant feature of which is that it can greatly reduce the energy consumption of the evaporation and concentration system.

[0057] The above description is merely a preferred embodiment of this utility model and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure involved in this utility model is not limited to the technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this utility model.

Claims

1. A novel evaporation and concentration system for concentrating a solution by evaporation, characterized in that, include: A heater includes a solution channel, a heating steam channel, and an evaporating steam outlet. The solution channel includes a solution inlet, a solution flow pipe, and a solution outlet. The heating steam channel includes a heating steam inlet and a condensate outlet and is configured such 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. The evaporating steam outlet is connected to the solution channel for discharging the evaporating steam generated by the heating and evaporation of the solution. as well as A steam booster device that boosts the pressure of the evaporated steam and provides at least a portion of the boosted evaporated steam as heating steam to the heating steam inlet.

2. The novel evaporation and concentration system as described in claim 1, characterized in that, The heaters include multiple heaters connected in series. The evaporated steam generated by the upstream heater is provided as heating steam to the heating steam inlet of the downstream heater, the evaporated steam generated by the downstream heater is provided to the steam booster, and the steam booster provides at least a portion of the boosted evaporated steam as heating steam to the heating steam inlet of the upstream heater.

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

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

5. The novel evaporation and concentration system as described in claim 1, characterized in that, The steam booster device includes a booster compressor and a drive unit, wherein the drive unit is used to drive the booster compressor to boost the evaporating steam.

6. The novel evaporation and concentration system as described in claim 5, characterized in that, The drive unit is an electric motor.

7. The novel evaporation and concentration system as described in claim 6, characterized in that, The drive unit also includes a drive turbine connected in series with the electric motor via a clutch. The traction turbine is driven by steam pressurized by the steam booster device.

8. The novel evaporation and concentration system as described in claim 5, characterized in that, The drive unit is a steam turbine. The traction turbine is driven by external steam.

9. The novel evaporation and concentration system as described in claim 8, characterized in that, The drive unit also includes an electric motor connected in series with the driven steam turbine via a clutch.

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

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

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