JPS61209001A - Mechanical compression type evaporative concentration apparatus - Google Patents

Abstract

PURPOSE:To contrive to improve heat efficiency, by providing a heat recovery circuit of a condensate and an overheater or evaporated steam to an evaporative concn. apparatus constituted of a fundamental evaporative concn. system and a heat recovery system consisting of a mechanical compressor and a heat compressor. CONSTITUTION:The condensates generated in first and second preheaters 1, 2 and an evaporator 4 are respectively withdrawn from the lower parts thereof and drains C1, C2, C3 are gathered to be guided to a flash boiler 9 as a drain C4. Further, the drain C5 from a steam overheater 10 is added to obtain flash vapor V4 which is, in turn, mixed with vapor V2 in the post-stage of an alkali scrubber 5 to be sucked to a mechanical compressor 6 through the steam heater 10. Next, drain waste water W1 is sprayed to overheated steam V3 by the arrangement of a temp. reducing machine in the post-stage of the mechanical compressor 6 to be returned to a saturated state and sent to the evaporator 4 to be utilized as a heat source.

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, in particular, mechanical compression evaporation, which mechanically compresses the generated steam to increase the enthalpy and reuses the latent heat of the steam by using it as heating steam. Regarding the concentration method.

Conventional technology The stock solution to be treated, such as spinning bath acid, is passed through a degassing can to remove most of the acid gases such as hydrogen sulfide and carbon disulfide, which is then evaporated and concentrated in an evaporator. It is conventionally known to send steam to a mechanical compressor to compress and raise its temperature, and to send it back to the heating can of the evaporator for use in heating the evaporator. In addition, the applicant's application requires cleaning the evaporated vapor through an alkaline scrubber before sending it to the compressor to remove accompanying acid gas and acid mist containing inorganic salts.

As an invention, JP-A-58-61882, JP-A-58-2
No. 16701, and a device therefor is also disclosed.

Based on Konera's basic technology, the present applicant has developed several improved technologies, which have been filed as individual technologies below.

% Application No. 59-129952 "Engine driven mechanical compression evaporation method" Patent application 1987-129953 "Improvement of mechanical compression evaporation method" Patent application No. 1511.68 of 1982 "Evaporation AM method" -158989 "Mechanical compression type evaporation concentrator" Patent application No. 158990/1982 "Mechanical compression type evaporation type a method" Problems to be solved by the invention However, the progress of technology as described above has mainly focused on improving thermal efficiency. However, individual inventions are fragmentary and are generally based on the invention of methods, and the devices based on the comprehensive technology that is the culmination of these technologies are still waiting to show their potential and are not used industrially. The best embodiment of what should be done is rarely done.

The present invention aims to provide a comprehensive exemplary device by organically combining several inventions with this type of evaporation concentration device.
In order to improve thermal efficiency, the evaporative concentrator consists of a basic evaporative concentrator system, a mechanical compressor, and a thermal compressor heat recovery system, and is equipped with a condesade heat recovery circuit and an evaporative steam superheater. In addition, the main idea is to vary the implementation of the drive unit for the mechanical compressor, thereby consistently adding value to the entire system.

EXAMPLES Below, the evaporation concentration apparatus of the present invention will be explained based on examples.

FIG. 1 shows a flow sheet of the apparatus of the present invention, in which 1 is the first preheater for the stock solution E supplied to the apparatus, 2 is the second preheater following it, and 3 is the 2nd preheater. Stage preheater 1
, 2, and is a degassing canister that removes most of the dissolved gas in the stock solution E. Reference numeral 4 denotes an evaporator which is a main device for heating and evaporating the stock solution E to concentrate it, and is composed of a heating can 41 to which steam S1 is supplied and a separator 42, and is also provided with a flash can 43. And they form an evaporation concentration system, and the supply line L, the pipeline is the first preheater 1 → pipeline, →
2nd preheater → pipe line Ls → degassing can 3 → pipe line L4 → evaporator 4 → pipe route.

→Flash can 43 is connected in order from pipe L6 to am
Recovered acid P as a liquid is recovered. A pump 46 is provided from the lower liquid chamber 44 to the top 45 of the evaporator 4 to connect the circulation pipe 4.
T is placed.

Reference numeral 48 denotes a liquid sending pump provided with a pipe line L6K downstream of the flash can 43, and the above 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 at the subsequent stage, a heat recovery system from the evaporation paper of the raw solution E generated is formed, and an alkali scrubber 5 and a mechanical compressor 6 are installed. Conduit V, and conduit V! The vapor, which has been pressurized and heated by the mechanical compressor 6, is connected to the pipe v3.
It is returned to the heating can 41 of the evaporator 4 via the evaporator 4 and used as a heating source. This configuration is also known for mechanical compression evaporation concentration plants.

On the other hand, a thermal compressor T is installed on the secondary side of the first preheater 10. This heat compressor 7 uses steam S.

is supplied as a driving source, and the discharge side of the ejector a is connected to the heat supply side of the preheater 1 and also to the flash can 43 through a pipe 71, and the ejector a sucks and pressurizes the flash canister of the concentrated liquid E. Heat is recovered in the form of latent heat through self-evaporation.

The above-mentioned configuration forms 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) Adding vapor from flash evaporation of condensate in the evaporator 4 and preheaters 1 and 2 to the mechanical compressor (Patent Application No. 59-129953) ■) Scrubber 5 and the machine A steam superheater is installed between 60 type compressors (Patent application 1983)
-158989) is a comprehensive device having a configuration that combines the individual improved inventions, and will be sequentially explained below.

U) The condensate of the steam supplied as a heating source to the preheaters 1 and 2 and the evaporator 4 and used for evaporating the stock solution E is supplied from the respective lower parts 101°2 (il, 401 to the pipe C).
1t c, e c, among them, the drain of C, is mainly sent to C4 in bulk to the drain flash can 9, where it is flash evaporated, and this vapor is sent to the pipe line v.
Pipe V from alkaline scrubber 5 via 4! added to.

(2) The above pipe V! After the confluence of V4 and V4, there is a line V! A steam superheater 10 is provided in the steam 8,
is added to heat the paper, the drain C1 of which is used for flash evaporation in the drain flash can 9.

(3) Furthermore, a desuperheater 11 is provided in the middle of the pipe v3 from the mechanical compressor 6 to the heating can 41, and a spray nozzle is provided in the desuperheater 11, for example, a drain 7
The drainage of the canister 9 can be used via a pump. Note that, at the downstream stage of the desuperheater 11, the pipe line V is branched off as a heat source for the second preheater 2.

(4) If a steam turbine auxiliary machine is used coaxially with the drive shaft 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 exhaust gas from the engine. This recovered heat is led to the flash can 43 and can be used as a heat source for the first preheater 1.

If we talk about other configurations in the flow sheet,
The alkaline scrubber 5 is supplied with caustic soda from 51, guided from the lower liquid m52 to the upper part by a pump 53, and sprayed from a spray nozzle 54 in the scrubber to the pipe v1.
Wash the evaporated steam with alkaline. 55 is a water supply pipe, 56 is a caustic soda discharge pipe for 6 seconds, and the alkaline pump 2 bar has a mist 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 condensate pipe line L.
The concentrated liquid is flash-evaporated here and sent to the condenser 32 via the pipe 121, and all the infusion liquid is discharged from the pipe L as the end of the pipe L6. fIkJII liquid P is obtained.

In addition, the drain path W1 in the figure is conducted after the ejector 8, and the drain W is sprayed here.

The residual thermal energy held by at K plus the first
can be sent to the preheater. Furthermore, the preheater 1.2 and the evaporator 4 are provided with bleed pipes R1*nz e R3 which are connected to the vacuum generator.

The basic components of the preheater, evaporator, and alkaline scrubber include the preheater 1 with shell and tube,
2. Although a liquid film falling type evaporator 4 and a cocurrent spray tower alkaline scrubber 5 were used, it is of course possible to select other types of scrubbers.

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 passed through a two-stage preheater 1.
, 2, the degassing can 3, and the L line connecting the evaporator 4, the temperature is raised sequentially, and the evaporated vapor is released and condensed to obtain the recovered acid P. The heating sources for the evaporation concentration system are steam S supplied from the outside at the start of operation, and steam 81 in the previous stage.
In addition to being used as an auxiliary device, the evaporative vapor is mainly sent to the mechanical compressor 6 to be pressurized and heated, and then sent back to the evaporator 4.
3, is purified by the alkaline scrubber 5, circulates through the V line in a non-greasy state, and is sent back to the evaporator 4 and second preheater 2 as a recovered heat source (vs
yV, ).

On the other hand, the steam T1 obtained by flash evaporation of the evaporator is also led to the self-steam heat compressor 7, where it forms a self-heating system.
Heat is recovered in the form of passion, and a series of devices evaporates and condenses the raw solution E.

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, to explain according to the above configuration items, (1) 1st.
The steam S supplied to the second preheaters 1 and 2 and a part of the vapor V add a residual amount M to the heat amount for preheating, and evaporate R4
, there is a remainder of steam S1 and vapor V.

Therefore, these condensates are drawn out from the bottom of each drain C1 using gravity head or pressure difference.
e C1r C3 is led from C4 to the drain flash can 9. Furthermore, by adding drain C from the steam superheater 10, flash vapor v4 is obtained, and vapor V! is obtained after the alkaline scrubber 5. It is possible to heat the vapor that is mixed with the vapor, passes through the heat pipe of the mechanical compressor 6, and is introduced into the vapor pipe V, which is arranged in a coil shape or the like, and at the same time, it is possible to precipitate and separate the mist in the vapor. As mentioned in U) above, the heat from 8 m2 of conde/sade per steam is also recovered for use as flash vapor.

(3) Next, the temperature reducing machine 11 in the latter stage of the mechanical compressor 6
By installing the superheated steam Vs K, the water of the drain water W1 is sprayed to return it to a saturated state and sent to the evaporator 4 as a heat source.

(4) Motor M is mainly used as a drive device for mechanical compressor 6.
In some cases, a turbine auxiliary equipment is installed coaxially and low-pressure steam is supplied to it. This not only reduces the load on the motor M, but also directs this exhaust gas to the raw liquid E.
It can be used as supplementary steam for the steam booster of the vacuum crystallizer for mirabilite contained in the raw solution of the spinning bath acid, or for heating the spinning bath acid bath heater. Low-pressure steam (1-2 V-gauge) is sufficient for the application, improving the efficiency of steam enthalpy utilization and saving on a separate steam system.

(5) The driving machine for the mechanical compressor 6 is an electric motor M as in this embodiment, and a turbine auxiliary machine may be added.
Alternatively, it is possible to select or combine a steam turbine alone, a turbine with an auxiliary motor, or a diesel engine. 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 concentrator of the present invention constructed as described above, the thermal efficiency is improved by providing additional circuits at each important point of the basic construction and supplying a small amount of make-up steam. This is a series of well-known devices completed in an integrated type, and can provide an epoch-making device for integrated evaporation plants.

[Brief explanation of drawings]

The drawing shows the evaporation c! of the present invention! This is a flow sheet showing the configuration of the line device. 1.2... 1st. Second preheater 3... degassing can 4
... Evaporator 5 ... Alkali scrubber 6 ...
Mechanical compressor T...Thermal compressor 9...Drain flash can 10...Steam superheater 11...Desuperheater 1
2...Self-evaporator E...Natural solution P...Recovered acid, -'-L,...Evaporation concentration system pipe ■1-V,...Heat recovery system pipe

Claims (5)

[Claims] (1) An evaporator that has a preheater and a degassing can in the front stage, an alkaline scrubber that cleans the vapor of the target processing liquid generated in the evaporator, and a mechanical compressor that compresses and raises the temperature of the cleaning vapor. In an evaporative concentrator that has a heat compressor and sends compressed steam from the compressor back to the preheater and the heating can of the evaporator to serve as a heat source, the drain side of the preheater and the heating can is is connected to a drain flash can, and the flash can is connected to the suction side of a mechanical compressor to form a condensate heat recovery circuit, and a steam superheater is provided between the subsequent stage and the mechanical compressor. Mechanical compression type evaporation concentration equipment. (2) The driving machine of the mechanical compressor is an electric motor, a steam turbine, or a diesel engine. Claim 1
The evaporative concentrator described in Section. (3) The drive machine of the mechanical compressor is provided coaxially as 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, as set forth in claim 1. evaporative 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.