JPH0134083B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is mainly aimed at recovering and reusing the spinning bath acid discharged from the spinning process in factories producing rayon, staple fiber, etc. Regarding the technology for evaporating and concentrating the target sulfuric acid aqueous solution, there is a mechanical compression method that mechanically compresses the generated steam to increase the enthalpy and reuses the latent heat of the steam by using this as heating steam. Concerning an evaporative concentration method.

BACKGROUND TECHNOLOGY Most of the acidic gases such as hydrogen sulfide and carbon disulfide are removed by passing the raw solution to be treated, such as spinning bath acid, through a degassing can, and this is evaporated and concentrated using an evaporator. It is conventionally known that the steam is then sent to a mechanical compressor to be compressed and heated, and then sent back to the heating can of the evaporator for use in heating the evaporator. In addition, the method of cleaning the evaporated vapor through an alkaline scrubber before sending it to the compressor to remove accompanying acidic gases and acidic mist containing inorganic salts is an invention filed by the present applicant in Japanese Patent Laid-Open No.
It is described in No. 61882 and Japanese Patent Publication No. 58-216701,
A device for that purpose is also disclosed.

Based on these basic techniques, the applicant has developed several improved techniques, which have been filed as individual techniques below.

Patent Application No. 1988-129952 “Engine-driven mechanical compression evaporation method” Patent Application No. 129-1983 “Improvement of mechanical compression evaporation method” Patent Application No. 151-168 “Evaporation concentration method” Patent Application No. 1987-158989 No. ``Mechanical Compression Evaporation Concentration Apparatus'' Patent Application No. 158990/1982 ``Mechanical Compression Evaporation Concentration Method'' Problems to be Solved by the Invention However, the advancement of technology as described above is mainly aimed at improving thermal efficiency. However, individual inventions are fragmentary and are generally based on the invention of methods, and devices based on the integrated technology that are the culmination of these inventions have only demonstrated their potential and have not been used industrially. The best embodiment that should have been achieved was something that had not been done.

Means for Solving the Problems Therefore, the present invention aims to provide a comprehensive model device by organically combining several types of inventions with this type of evaporation concentration device. The evaporative concentrator consists of an evaporative concentrator system, a mechanical compressor, and a thermal compressor heat recovery system, and a condesate heat recovery circuit.
The idea is to improve thermal efficiency by installing a superheater for evaporative steam, and to change the implementation of the mechanical compressor drive, thereby consistently adding value to all equipment. It was designed to give the same effect.

EXAMPLES The evaporation concentration apparatus of the present invention will be described below based on examples.

Figure 1 shows the apparatus of the present invention in the form of a flow sheet, in which 1 indicates the stock solution E supplied to the apparatus.
The first preheater is the first preheater, 2 is the second preheater following it, and 3 is a degassing can that is placed after the two-stage preheaters 1 and 2 and removes most of the dissolved gas in the stock solution E. . 4 is an evaporator, which is the main device that heats and evaporates the stock solution E to concentrate it, and a heating can 41 to which steam S ₁ is supplied.
and a separator 42, and a flash can 43.
It also has a. And they form an evaporation concentration system, the lines of the supply line L ₁ are first preheater 1 → line L ₂ → second preheater → line L ₃ → degassing pipe 3 → line
They are connected in this order: L ₄ -> evaporator 4 -> pipe L ₅ -> flash can 43, and recovered acid P as a concentrated liquid is recovered from pipe L ₆ . A pump 46 is provided from the lower liquid chamber 44 to the top 45 of the evaporator 4, and a circulation pipe 47 is connected thereto.
are arranged. Reference numeral 48 denotes a liquid pump installed in the pipe line _L6 after the flash can 43, and the above-mentioned configuration forms the basis of an evaporation concentration apparatus and is well known.

Next, the separator 42 of the evaporator 4 separates the mist, and in the subsequent stage, a heat recovery system is formed to recover the generated raw liquid E from the evaporated vapor, and an alkali scrubber 5 and a mechanical compressor 6 are installed, which sequentially conduit
The vapor that has been pressurized and heated by the mechanical compressor ₆ is returned to _the heating can 41 of the evaporator 4 via the pipe V ₃ and is used as a heat source. This configuration is also known for mechanical compression evaporation concentration plants.

On the other hand, a thermal compressor 7 is installed on the secondary side of the first preheater 1. This thermal compressor 7 is supplied with steam S ₂ as a driving source, and the discharge side of the ejector 8 is connected to the heat supply side of the preheater 1, and is also connected to the flash can 43 by a pipe line 71. ,
The flash vapor of concentrated liquid E is suctioned and pressurized, and heat is recovered in the form of latent heat through self-evaporation.

The above configuration is the basis of the applicant's earlier patent application No. 129953 of 1982 and is well known as an evaporation concentration plant combining an evaporation concentration system, a mechanical compression type, and a self-evaporation type.

In addition to the above-mentioned basic configuration, the present invention has the following features: (1) The condensate flash vapor in the evaporator 4 and the preheaters 1 and 2 is added to the mechanical compressor (Japanese Patent Application No. 59-129953) (2) The scrubber 5 and This system is a comprehensive system that combines the individual improvement inventions of providing a steam superheater between the mechanical compressors 6 (Japanese Patent Application No. 59-158989), and will be explained in sequence below.

(1) The steam condensate that is supplied as a heating source to the preheaters 1 and 2 and the evaporator 4 and used for evaporating the stock solution E is stored in the lower parts 101 and 20 of each.
Pipes C ₁ , C ₂ , and C ₃ are provided from 1,401, and among them, the drain from C ₃ is mainly sent to C ₄ in bulk to the drain flash can 9, where it is evaporated as a flash, and this vapor is vaporized. It is added to line V ₂ from the alkaline scrubber 5 via line V ₄ .

(2) A steam superheater 10 is installed in the line V ₂ after the confluence of the above-mentioned pipes V ₂ and V ₄ , and steam S ₃ is added to heat the paper, and its drain C ₅
is used for flash evaporation in the drain flash can 9.

(3) Furthermore, a desuperheater 11 is provided in the middle of the pipe V ₃ from the mechanical compressor 6 to the heating can 41.
A spray nozzle is provided inside, so that, for example, the waste water _W1 from the drain flush can 9 can be used via a pump. Note that in the latter stage of the desuperheater 11, the pipe line V ₃ is branched off (V ₅ ) as a heating source for the second preheater 2.

(4) If a steam turbine auxiliary machine is used coaxially with the drive oil of the drive motor M of the mechanical compressor 6, the load on the motor M can be reduced by using separate low-pressure steam.

(5) A diesel engine can be selected as the drive motor M. In that case, a jacket is provided on the engine, and water is supplied to the jacket to cool the heat of the engine exhaust gas with water. This recovered heat is led to the flash can 43 and can be used as a heat source for the first preheater 1.

Regarding other configurations in the flow sheet, caustic soda is supplied from 51 to the alkaline scrubber 5, is guided from the lower reservoir 52 to the upper part by the pump 53, is ejected from the spray nozzle 54 in the scrubber, and is sent to the pipe V. The evaporated steam from ₁ is washed with alkaline. 55 is a water supply pipe, 56 is a caustic soda discharge pipe, and the alkaline scrubber has a mineral separator and is equipped with alkali adjustment instrumentation.

The gas degassed in the degassing can 3 is led to a condenser 32 through a conduit 31, condensed by external water supply, and discharged.

Next, 12 is a self-evaporator, which is a conduit for concentrated liquid.
The condensed liquid is provided downstream of the pump 48 in the middle of L ₆ , where the concentrated liquid is flash evaporated and sent to the condenser 32 via the pipe 121, and the condensed liquid is sent to the condenser 32 through the pipe 121.
The concentrated liquid P is discharged from the pipe L ₇ as the end of L ₆ .
is obtained.

Further, the drain path W ₁ in the figure is led to the latter stage of the ejector 8, and the remaining thermal energy sprayed here and held by the drain W ₁ can also be sent to the first preheater in addition to S ₂ . Furthermore, the preheaters 1, 2 and the evaporator 4 are provided with bleed pipes R ₁ , R ₂ , R ₃ connected to the vacuum generator.

In addition, as the preheater, evaporator, and alkali scrubber as the basic components, the preheater 1 and 2 by shell and tube, the evaporator 4 of the liquid film falling type, and the alkali scrubber 5 of the cocurrent type spray tower were used. However, it is of course possible to choose various other formats.

Operation The operation of the evaporation concentration apparatus of the present invention will be explained, and the operation of the present invention configured as described above will be described.

The raw solution E to be supplied and processed to this apparatus for recovering the spinning bath acid discharged from the spinning process is supplied to the L line connecting the two-stage preheaters 1 and 2, the degassing can 3, and the evaporator 4. The temperature of the acid is raised in sequence, vapor vapor is released, and the acid is concentrated to obtain recovered acid P.
The heating source for the evaporative concentration thread is mainly the steam S ₁ supplied from the outside at the start of operation and the steam S ₂ in the previous stage that is used for assistance, and the pressure and temperature are increased by the mechanical compressor 6 and sent back to the evaporator 4. Evaporation vapor V ₃
It is cleaned by the alkaline scrubber 5, circulates through the V line in a non-corrosive state, and is sent back to the evaporator 4 and second preheater 2 as a recovered heat source (V ₃ , V ₅ ). On the other hand, the vapor 71 obtained by flash evaporation in the concentrator is also led to the self-steam heat compressor 7, where it forms a self-heating system, where the heat is recovered in the form of latent heat, and the raw solution E is concentrated by a series of devices. will be held.

In addition to the above-mentioned basic operation, the present invention aims to further improve thermal efficiency, and constructs additional circuits in various places focusing on thermal potential. That is, if explained according to the above configuration items, (1) the steam supplied to the first and second preheaters 1 and 2;
S ₂ and a portion of the vapor V ₅ have a residual amount of heat for preheating, and the evaporator 4 has a residual portion of the steam S ₁ and the vapor V ₃ . These condensates are therefore drawn from the bottom of each and drained using gravity heads or pressure differences.
C ₁ , C ₂ , and C ₃ are led from C ₄ to the drain flash can 9 . Furthermore, the drain C ₅ from the steam superheater 10
is added to obtain flash vapor V ₄ , which is mixed with vapor V ₂ after the alkaline scrubber 5 and sucked into the mechanical compressor 6 .

(2) The above-mentioned steam S ₃ passes through a finned heat transfer tube in the steam superheater 10, heats the vapor that is piped in a coil shape, etc., and is introduced through the vapor pipe V ₂ , and precipitates and separates the mist in the vapor. can do. As mentioned in (1) above, steam
The heat from the condensate in _S3 is also recovered for flash vapor use.

(3) Next, the temperature reducer 11 after the mechanical compressor 6
By installing the superheated steam V ₃ , water from the drain water W ₁ is sprayed onto the superheated steam V 3 to return it to a saturated state, which is then sent to the evaporator 4 and used as a heat source.

(4) Motor M is mainly used as a drive device for mechanical compressor 6.
In some cases, a turbine auxiliary machine is installed coaxially and low-pressure steam is supplied to it. This not only reduces the load on the motor M, but also allows the exhaust gas to be used before introducing the stock solution E, making it possible to supply steam for the steam booster of the vacuum crystallizer for mirabilite, etc. contained in the stock solution of the spinning bath acid. Alternatively, it can be used for heating a spinning bath acid bath heater, and low pressure steam (1 to 2 Kg/cm ² gauge) is sufficient for both of these applications.
Improve the efficiency of using the enthalpy of steam,
Separate steam system can be saved.

(5) The driving machine for the mechanical compressor 6 may be an electric motor M as in this embodiment, a turbine with an auxiliary machine added, a steam turbine alone, a turbine with an auxiliary motor added, a diesel engine, etc. Machines can be selected or combined. Therefore, when a diesel engine is used, the heat of the exhaust gas can also be extracted with cooling water, and such thermal energy is suitable for use in preheating the first stage in the first preheater 1.

Effects of the Invention In the evaporation concentration device of the present invention configured as described above, additional circuits are provided for each key point of the basic configuration, and
Since it improves thermal efficiency by supplying a small amount of make-up steam, it is a series of well-known devices completed into a comprehensive type, and provides an epoch-making device for a comprehensive evaporation concentration plant. can.

[Brief explanation of drawings]

The drawing is a flow sheet showing the configuration of the evaporation concentration apparatus of the present invention. 1, 2...first and second preheaters, 3...degassing can, 4...evaporator, 5...alkaline scrubber,
6... Mechanical compressor, 7... Heat compressor, 9... Drain flash can, 10... Steam superheater, 11...
Attemperator, 12...Self-evaporator, E...Standard solution, P...
...Recovered acid, L ₁ to L ₇ ... Evaporation concentration system pipe, V ₁ to _{V 5}
...Heat recovery system pipe line, _C1 to _C5 ...Condensate circuit, _S1 , _S2 , _S3 ...Steam pipe line.

Claims (1)

[Scope of Claims] 1. An evaporator with a preheater and a degassing can at the front stage, an alkaline scrubber that cleans the vapor of the target treatment liquid generated in the evaporator, and a machine that compresses and raises the temperature of the cleaning vapor. In an evaporative concentrator that has a compressor, the compressed steam from the compressor is sent back to the preheater and the heating can of the evaporator to serve as a heat source, and also has a heat compressor to recover heat. The drain side of the can is connected to a drain flash can, and the flash can is connected to the suction side of the mechanical compressor to form a condensate heat recovery circuit, and a steam superheater is installed between the subsequent stage and the mechanical compressor. A mechanical compression type evaporation concentration device characterized by: 2. The evaporative concentrator according to claim 1, wherein the mechanical compressor is driven by an electric motor, a steam turbine, or a diesel engine. 3. The evaporator according to claim 1, wherein the drive machine of the mechanical compressor is a combination of an electric motor and a steam turbine auxiliary machine, or a combination of a steam turbine and an electric motor auxiliary machine, which are coaxially provided. Concentrator. 4. The evaporative concentrator according to claim 1, wherein the driving machine of the mechanical compressor is a diesel engine, and is equipped with means for cooling its exhaust gas. 5. The evaporation concentration device according to claim 1, wherein a desuperheater is provided between the mechanical compressor and the heating can of the evaporator.