Method and device for efficiently utilizing secondary steam of multi-effect evaporator set

Abstract

The invention discloses an efficient secondary steam utilization method and device for a multi-effect evaporator set, and relates to the technical field of multi-effect evaporator sets. The multi-effect evaporator set is formed by combining a two-effect evaporator, a three-effect evaporator, a four-effect evaporator, a five-effect evaporator, a six-effect evaporator, a seven-effect evaporator, an eight-effect evaporator and the like, and the illustration is that the multi-effect evaporator set is composed of six evaporators. The first-effect evaporator, the second-effect evaporator, the third-effect evaporator, the fourth-effect evaporator, the fifth-effect evaporator and the sixth-effect evaporator are sequentially arranged from left to right, a condensate water tank is correspondingly arranged below each evaporator, and the first-effect condensate water tank, the second-effect condensate water tank, the third-effect condensate water tank, the fourth-effect condensate water tank, the fifth-effect condensate water tank and the sixth-effect condensate water tank are sequentially arranged from left to right. According to the secondary steam efficient utilization method and device of the multi-effect evaporator set, the water evaporation amount is increased, the steam consumption of the unit water evaporation amount is reduced, and the energy consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-effect evaporator sets, and specifically to a method and device for efficiently utilizing secondary steam of a multi-effect evaporator set. Background Art

[0002] Multi-effect evaporation refers to using the secondary steam of the previous effect as the heating steam of the next effect. A multi-effect evaporator set refers to multiple evaporators operating together through different formations. A multi-effect evaporator set includes various combinations such as a two-effect evaporator, a three-effect evaporator, a four-effect evaporator, a five-effect evaporator, a six-effect evaporator, a seven-effect evaporator, and an eight-effect evaporator. Each of these evaporators is called an effect. The evaporator into which fresh steam is introduced for heating is called the first effect (or the first stage). The steam produced by each effect evaporator is called secondary steam. The evaporator that uses the secondary steam produced by the first effect as the heating agent is called the second effect, and the evaporator that uses the secondary steam produced by the second effect as the heating agent is called the third effect, and so on. The last effect evaporator may be the second effect, the third effect, the fourth effect, the fifth effect, the sixth effect, the seventh effect, or the eighth effect. The secondary steam produced by the last effect is sent to a water cooler and cooled by circulating water and then discharged from the system. The condensed water produced by the first effect evaporator is returned to the power plant for recycling after passing the conductivity test. The condensed water produced by each effect after the first effect evaporator is sent to the condensed water tank of this effect. According to the change in pressure level, the condensed water in the second effect condensed water tank is sent to the third effect condensed water tank, and the condensed water in the third effect condensed water tank is sent to the fourth effect condensed water tank, and so on. The condensed water of the last effect is pumped out of the evaporator set system.

[0003] The boiling point of a solution is higher than that of the solvent due to the presence of solutes and is affected by pressure and concentration. Under different conditions, the temperature of secondary steam is higher than the saturation steam temperature of the solvent. Superheated steam has low heat transfer efficiency in the heating chamber, reducing the heat utilization efficiency. And the solution concentration process of a multi-effect evaporator includes full countercurrent, full cocurrent, full crossflow, and crossflow processes, etc. The full countercurrent process is where the feed enters from the last effect and the product exits from the first effect, and the secondary steam flow is completely opposite. The full cocurrent process is where the feed enters from the first effect and the product exits from the last effect, and the secondary steam flow is completely the same. The full crossflow process is where the feed enters each effect evaporator in parallel and there are differences in the secondary steam flow. The crossflow process is where the feed enters from different effects and includes countercurrent or cocurrent processes. Due to the different solution feeding methods, the superheat degree of the secondary steam produced by each effect evaporator in multiple evaporator sets is not fixed. Therefore, in the process design and production practice, the utilization work of the superheat degree of the secondary steam produced by each effect evaporator in a multi-effect evaporator set has not been carried out. For this reason, a method and device for efficiently utilizing secondary steam of a multi-effect evaporator set are proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and device for efficiently utilizing secondary steam of a multi-effect evaporator set to solve the problems in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solutions: A method and device for efficiently utilizing secondary steam of a multi-effect evaporator group, including a multi-effect evaporator, a condensate tank, and a water cooler. The multi-effect evaporator group is formed by various combinations of a two-effect evaporator, a three-effect evaporator, a four-effect evaporator, a five-effect evaporator, a six-effect evaporator, a seven-effect evaporator, an eight-effect evaporator, etc. The illustrated example is a multi-effect evaporator group composed of six evaporators, which are, from left to right, a first-effect evaporator, a second-effect evaporator, a third-effect evaporator, a fourth-effect evaporator, a fifth-effect evaporator, and a sixth-effect evaporator. And a condensate tank is correspondingly arranged below each evaporator, which are, from left to right, a first-effect condensate tank, a second-effect condensate tank, a third-effect condensate tank, a fourth-effect condensate tank, a fifth-effect condensate tank, and a sixth-effect condensate tank. A liquid pipeline is connected between the multi-effect evaporators, and a liquid pump is installed on the liquid pipeline. A steam pipeline is connected between the multi-effect evaporators. A condensate pipeline is connected between the multi-effect evaporator and the condensate tank. A condensate pump is installed at the outlet of the last-effect condensate tank. Other qualified clean water pipes can also be externally connected to the condensate pipeline.

[0006] Preferably, the condensate pipeline extends above the steam pipeline, and a condensate branch pipe is installed between the steam pipeline and the condensate pipeline. The end of the condensate branch pipe extends into the steam pipeline, and a flow valve is installed on the condensate branch pipe. A spray nozzle is fixedly installed at the end of the condensate branch pipe.

[0007] Preferably, the end of the condensate branch pipe is provided with threads, and the spray nozzle is connected to the condensate branch pipe by bolts.

[0008] A method for efficiently utilizing secondary steam of a multi-effect evaporator group specifically includes the following steps: Step 1: Use the liquid pipeline to sequentially transport the liquid to the sixth-effect evaporator, the fifth-effect evaporator, the fourth-effect evaporator, the third-effect evaporator, the second-effect evaporator, and the first-effect evaporator. Step 2: Use fresh steam to heat the liquid in the first-effect evaporator. After heating, the secondary steam in the first-effect evaporator is transported to the second-effect evaporator through the steam pipeline as a heating steam source. After heating, the secondary steam in the second-effect evaporator is transported to the third-effect evaporator through the steam pipeline as a heating steam source. After heating, the secondary steam in the third-effect evaporator is transported to the fourth-effect evaporator through the steam pipeline as a heating steam source. After heating, the secondary steam in the fourth-effect evaporator is transported to the fifth-effect evaporator through the steam pipeline as a heating steam source. After heating, the secondary steam in the fifth-effect evaporator is transported to the sixth-effect evaporator through the steam pipeline as a heating steam source. The steam produced by the sixth-effect evaporator is finally transported to the water cooler through the steam pipeline and discharged from the system after being cooled by circulating water. Step 3: The condensed water produced by the first-effect evaporator is returned to the power plant for recycling after passing the conductivity test. The condensed water produced by the remaining evaporators is sent to the corresponding condensed water tanks. According to the change of pressure level, the condensed water in the second-effect condensed water tank is sent to the third-effect condensed water tank, the condensed water in the third-effect condensed water tank is sent to the fourth-effect condensed water tank, and so on. The condensed water in the sixth-effect condensed water tank is sent out of the evaporator group system by a water pump.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows: In this application, the end-effect condensed water is exchanged heat with the superheated secondary steam of each effect, turning the condensed water into steam, achieving a substantial increase in the value of the condensed water. And by adding condensed water for cooling, the superheated secondary steam of each effect becomes saturated steam, improving the heat transfer efficiency while maintaining the same heating area of the entering evaporator, simultaneously increasing the evaporation amount, reducing the steam consumption per unit evaporation amount, improving the energy utilization rate, and reducing the energy consumption.

[0010] In this application, the atomizing nozzle can be connected by internal or external threads. The unique blade design inside the nozzle makes the spray particles fine and the atomization effect very uniform and fine. The spray shape is a conical solid shape, and the angle can be controlled to achieve uniform distribution of atomized particles in the full pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram of the overall structure of the present invention; Figure 2 is a schematic diagram of the inside of the steam pipeline of the present invention.

[0012] Reference numerals in the drawings: 1, multi-effect evaporator; 2, liquid pipeline; 3, condensed water pipeline; 301, condensed water branch pipe; 4, steam pipeline; 501, liquid pump; 502, condensed water pump; 6, condensed water tank; 7, water cooler; 8, atomizing nozzle; 9, flow valve; 10, water purification pipe. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0013] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0014] Such as Figure 1 and Figure 2As shown, the present invention provides a technical solution for the efficient utilization of secondary steam in a multi-effect evaporator group, including a multi-effect evaporator 1, a condensate tank 6, and a water cooler 7. The multi-effect evaporator 1 is composed of six evaporators, which are, from left to right, a first-effect evaporator, a second-effect evaporator, a third-effect evaporator, a fourth-effect evaporator, a fifth-effect evaporator, and a sixth-effect evaporator. And a condensate tank 6 is correspondingly arranged below each evaporator, which are, from left to right, a first-effect condensate tank, a second-effect condensate tank, a third-effect condensate tank, a fourth-effect condensate tank, a fifth-effect condensate tank, and a sixth-effect condensate tank. A liquid pipeline 2 is connected between the multi-effect evaporators 1, and a liquid pump 501 is installed on the liquid pipeline 2. A steam pipeline 4 is connected between the multi-effect evaporators 1. A condensate pipeline 3 is connected between the multi-effect evaporator 1 and the condensate tank 6. The condensate pipeline 3 extends above the steam pipeline 4. And a condensate branch pipe 301 is installed between the steam pipeline 4 and the condensate pipeline 3. The end of the condensate branch pipe 301 extends into the steam pipeline 4. A flow valve 9 is installed on the condensate branch pipe 301. An atomizing nozzle 8 is fixedly installed at the end of the condensate branch pipe 301. The end of the condensate branch pipe 301 is provided with a thread, and the atomizing nozzle 8 is connected to the condensate branch pipe 301 by bolts. Other qualified clean water pipes 10 can also be externally connected to the condensate pipeline 3.

[0015] During the normal production process, the condensate in the six-effect condensate tank is transported to the evaporator group system by the condensate pump 502. A condensate pipe 3 is led out from the pump port of the condensate pump 502 or a new condensate pipe 3 is added, and a condensate branch pipe 301 is branched out from this condensate pipe 3. This condensate branch pipe 301 extends into the steam pipe 4, and its pipe diameter is determined through precise calculation based on the number of effects of each evaporator in the multi-effect evaporator group 1 and the different operating modes of the feed liquid. The condensate in the condensate branch pipe 301 is respectively transported into the steam pipe 4 between the multi-effect evaporators 1. In order to adjust the spraying amount of the condensate and ensure its uniform distribution, a flow valve 9 is installed on the condensate branch pipe 301 leading to each effect steam pipe 4. In addition, an atomizing nozzle 8 is also installed on the condensate branch pipe 301 to ensure that the condensate fed into the steam pipe 4 can be quickly atomized. This atomized condensate exchanges heat with the superheated steam, prompting the superheated steam to turn into saturated steam, thereby reducing the amount of superheated steam and improving the heat utilization efficiency of the heating tubes of each effect evaporator. For the feed liquid properties processed by the evaporators of different enterprises, it is necessary to precisely calculate the evaporation amount of each evaporator of the multi-effect evaporator 1. By calculating the temperature of the evaporator feed liquid, the amount of secondary steam, and the pressure level of this effect evaporator, the addition amount of the final effect condensate can be calculated. The water inflow into each steam pipe 4 is adjusted through the flow valve 9 to achieve the optimal operating state. After adjusting the water inflow into each effect steam pipe 4, it is necessary to take samples and analyze the feed liquid entering the evaporator and the feed liquid at the outlet of each effect evaporator. According to the amount of feed liquid entering the evaporator and the concentration of each effect, calculate the evaporation amount and steam-water ratio of the multi-effect evaporator group, and verify whether the adjusted evaporation amount has increased and whether the steam-water ratio has decreased. Compare these data with the theoretical calculated values, and further repeat the same workflow according to the comparison results for continuous optimization. The condensate sprayed by the atomizing nozzle 8 can also be other water with qualified quality, and the other water is transported to the atomizing nozzle 8 through the water purification pipe 10.

[0016] As Figure 2 shown, the design of the atomizing nozzle 8 has multiple options, and users can choose the internal thread or external thread connection method according to actual needs. The unique vane design inside the nozzle can ensure that the spray particles are very fine, thus achieving an excellent atomization effect, making the atomization effect very uniform and fine. In addition, the spray shape of the nozzle is designed as a conical solid shape, which makes the spray have good directivity. Users can also control the spray angle by adjusting the nozzle, so as to achieve the uniform distribution of atomized particles in the full pipe, ensuring the coverage range and effect of the spray.

[0017] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any respect, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Accordingly, all changes that fall within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims concerned.

Claims

1. A multi-effect evaporator set, characterized in that: It includes a multiple-effect evaporator (1), a condensate tank (6) and a water cooler (7). The multiple-effect evaporator (1) can be various combinations such as a two-effect evaporator, a three-effect evaporator, a four-effect evaporator, a five-effect evaporator, a six-effect evaporator, a seven-effect evaporator, an eight-effect evaporator, etc. The illustrated example is a group of multiple-effect evaporator units composed of six evaporators, which are the first-effect evaporator, the second-effect evaporator, the third-effect evaporator, the fourth-effect evaporator, the fifth-effect evaporator and the sixth-effect evaporator in sequence from left to right. And a condensate tank (6) is correspondingly arranged below each evaporator, which are the first-effect condensate tank, the second-effect condensate tank, the third-effect condensate tank, the fourth-effect condensate tank, the fifth-effect condensate tank and the sixth-effect condensate tank in sequence from left to right. A liquid pipeline (2) is connected between the multiple-effect evaporators (1), a steam pipeline (4) is connected between the multiple-effect evaporators (1), a condensate pipeline (3) is connected between the multiple-effect evaporator (1) and the condensate tank (6). A liquid pump (501) and a condensate pump (502) are respectively installed on the liquid pipeline (2) and the condensate pipeline (3). Other qualified clean water pipelines (10) can also be externally connected to the condensate pipeline (3).

2. The multi-effect evaporator group according to claim 1, wherein: The condensate pipeline (3) extends above the steam pipeline (4), and a condensate branch pipe (301) is installed between the steam pipeline (4) and the condensate pipeline (3). And the end of the condensate branch pipe (301) extends into the steam pipeline (4). A flow valve (9) is installed on the condensate branch pipe (301), and an atomizing nozzle (8) is fixedly installed at the end of the condensate branch pipe (301).

3. The multi-effect evaporator set according to claim 2, characterized in that: Threads are provided at the end of the condensate branch pipe (301), and the atomizing nozzle (8) is connected to the condensate branch pipe (301) through bolts.

4. A method for efficiently utilizing the secondary steam of a multi-effect evaporator group, which is applicable to a multi-effect evaporator group as described in any one of claims 1-3, characterized in that The multiple-effect evaporator (1) can be various combinations such as a two-effect evaporator, a three-effect evaporator, a four-effect evaporator, a five-effect evaporator, a six-effect evaporator, a seven-effect evaporator, an eight-effect evaporator, etc. The illustrated example is a group of multiple-effect evaporator units composed of six evaporators. The specific steps are as follows: Step 1: Use the liquid pipeline to sequentially transport the liquid to the sixth-effect evaporator, the fifth-effect evaporator, the fourth-effect evaporator, the third-effect evaporator, the second-effect evaporator and the first-effect evaporator. Step 2: Use fresh steam to heat the liquid in the first-effect evaporator. After heating, the secondary steam in the first-effect evaporator is transported to the second-effect evaporator through the steam pipeline as the heating steam source. After heating, the secondary steam in the second-effect evaporator is transported to the third-effect evaporator through the steam pipeline as the heating steam source. After heating, the secondary steam in the third-effect evaporator is transported to the fourth-effect evaporator through the steam pipeline as the heating steam source. After heating, the secondary steam in the fourth-effect evaporator is transported to the fifth-effect evaporator through the steam pipeline as the heating steam source. After heating, the secondary steam in the fifth-effect evaporator is transported to the sixth-effect evaporator through the steam pipeline as the heating steam source. The steam produced by the sixth-effect evaporator is finally transported to the water cooler through the steam pipeline and is cooled by circulating water and then discharged from the system. Step 3: The condensate water produced by the first-effect evaporator is returned to the power plant for recycling after passing the conductivity test. The condensate water produced by the remaining evaporators is sent to the corresponding condensate water tanks. According to the change of pressure level, the condensate water in the second-effect condensate water tank is sent to the third-effect condensate water tank, the condensate water in the third-effect condensate water tank is sent to the fourth-effect condensate water tank, and so on. The condensate water in the sixth-effect condensate water tank is sent out of the evaporator system by a water pump.

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