CN100558912C - A device for mixing saturated steam and superheated steam for use in vacuum refining furnaces - Google Patents

Abstract

The invention relates to a device for mixing saturated steam and superheated steam for use in a vacuum refining furnace, comprising three parts: a steam superheating device, a steam mixing device, and a steam system for an external pipe network. Its characteristic is that saturated steam and superheated steam are mixed for heat exchange, and after reaching the requirement of steam superheat degree for refining and vacuuming, it is used for vacuuming by vacuum pump in steelmaking refining furnace, creating a new technology for supplying superheated steam to vacuum pump. The technology covers a wide range, and it is especially suitable for projects using vacuum refining technology in converter steelmaking plants. It can save a lot of infrastructure investment for the construction unit, reduce the amount of engineering, and the process is simple, safe and reliable, and the operating cost is low.

Description

A device for mixing saturated steam and superheated steam for use in vacuum refining furnaces

technical field

The invention relates to the technical field that the self-produced saturated steam of the reheated heating furnace is mixed with the self-produced saturated steam of the converter vaporization cooling to meet the superheat requirement of the steam and then used for the vacuum pump of the vacuum refining furnace.

Background technique

In the steelmaking vacuum refining furnace device, the vacuum pump for making vacuum is the key equipment of the refining furnace. The vacuum pump relies on steam to pump the vacuum. The steam system of the vacuum pump is strict, and the steam is required to be superheated steam. At the same time, the pressure is required to be stable when the steam consumption of the vacuum pump changes, otherwise the vacuum furnace cannot meet the vacuum degree requirement.

At present, when domestic and foreign converter steelmaking manufacturers build vacuum refining furnaces, the methods for realizing steam superheating mainly include:

1. Separately build a steam supply boiler, which consumes a lot of gas and electricity;

2. After leading the medium-pressure superheated steam pipeline to the vicinity of the vacuum refining furnace, it is stored in a special heat storage station and decompressed to obtain a slight superheat degree, which consumes a large amount of high-quality medium-pressure superheated steam;

3. Use medium-pressure superheated steam after decompression and decompression treatment, and consume a large amount of high-quality medium-pressure and superheated steam;

4. Use an electric heater to heat the saturated steam produced by the converter. After reaching the steam superheat requirement, it can be used for vacuuming the refining furnace (ZL 00136276.3) - this method reduces the consumption of medium-pressure superheated steam, but consumes a lot of electricity, operation and maintenance costs high.

The above several ways of supplying steam to the vacuum pump are generally adopted by steelmaking plants at home and abroad. However, these steam supply methods also have common deficiencies, that is, large investment, large land occupation, high energy consumption and high production costs.

The heating furnace in the hot rolling mill is used to heat the slab, and the bottom water pipe of the heating furnace is cooled by vaporization. The heating furnace burns and heats the steel billet continuously and stably, so the vaporization cooling of the heating furnace can continuously generate saturated steam with stable pressure, temperature and flow rate. Usually, the steam produced is sent to the comprehensive pipe network of the factory area for heating, purging and other low-end Hot users. The flue gas produced by the fuel combustion of the heating furnace is discharged from the flue on both sides of the heating furnace, passes through the air preheater and gas preheater, and then flows into the main flue of the heating furnace, and then enters the chimney row outside the factory building through the flue gate. Walk. During operation, in order to prevent the flue gas from overheating in front of the air heat exchanger, the cooling fan is often turned on to add cold air to protect the air and gas heaters; When the air and hot gas are overheated, it is necessary to open the hot air release valve frequently to release the hot air, resulting in a large amount of waste of heat and electricity, and thermal pollution.

The quality of self-produced steam for converter vaporization cooling in the steelmaking workshop is poor, which does not meet the steam requirements for vacuum pumps; the exhaust gas temperature of the heating furnace in the steel rolling workshop is high, and cooling measures must be taken; the waste heat of the heating furnace flue gas has not been effectively utilized.

Contents of the invention

The object of the present invention is to provide a device for supplying superheated steam to the vacuum pump of the steelmaking and refining furnace, so as to fully utilize the steam produced by the waste heat boiler of the steelmaking plant for the vacuum pump of the steelmaking and refining vacuum without consuming other energy sources.

The technical solution of the present invention is: a device for mixing saturated steam and superheated steam for use in a vacuum refining furnace, including a flue, a heat accumulator, a regulating valve, a steam-water pipeline, a steam mixing device and a steam superheating device, and the heating furnace is vaporized and cooled automatically The saturated steam produced enters the steam superheater after passing through the saturated steam pipeline and pressure regulating valve, and the superheated steam thus generated is sent to the steam mixing device through the pipeline, and then enters the steam mixer through the temperature regulating valve and steam pressure regulating valve; The saturated steam enters the steam mixer through the main pressure regulating valve and the auxiliary pressure regulating valve. In the mixer, the saturated steam and the superheated steam are mixed and exchanged to meet the set temperature and pressure requirements, and are used by the vacuum pump of the vacuum refining furnace; vaporized in the heating furnace The part of the steam produced by cooling that is greater than the steam used for refining is regulated by the flow regulating valve and sent to the low-pressure heat accumulator. The part of the steam produced by the converter vaporization cooling that is greater than the steam used for refining is sent to the low-pressure heat accumulator after being passed through the saturated steam pressure regulating valve, and stored in the heat accumulator. , stabilized pressure, and then sent to the plant pipe network after passing through the pressure reducing regulating valve, for use by saturated steam facilities.

It is described in the following four parts:

First: steam mixing device

In general, the self-produced steam of converter vaporization cooling is low-pressure saturated steam. When the vacuum pump uses this steam to evacuate, the vacuum pump may have water hammer, which will cause equipment breakdown and shorten the service life of the equipment. At the same time, it is difficult to achieve the desired vacuum. degrees, so superheated steam is required. In the present invention, the low-pressure saturated steam produced by the vaporization and cooling of the heating furnace is heated by the exhaust heat of the heating furnace to become superheated steam, which is mixed with the saturated steam produced by the vaporization and cooling of the converter flue in the steelmaking workshop, and the high-quality superheated steam is used to heat and mix the converter for self-production Saturated steam is used for vacuuming the refining furnace after reaching the steam pressure and superheat for refining and vacuuming.

The flow of the steam mixing device is as follows:

(1) The heating furnace is vaporized and cooled to supply saturated steam—steam superheating device (to form superheated steam)—steam mixing device—sub-cylinder of refining system—superheated steam, and the remaining steam is sent to the plant pipe network through the regulating valve.

(2) Converter vaporization cooling produces steam (saturated steam)—regenerator—steam-water separator—steam mixing device—refining system sub-cylinder—superheated steam, and the remaining steam is sent to the plant pipe network through a regulating valve.

The steam mixing device is composed of static steam mixer, temperature and pressure regulating system. The temperature error of the steam adjusted by the steam mixing device is <±5%, and the pressure error is <±2%, which meets the requirements of steam for vacuuming.

Second: reduce the exhaust gas temperature of the heating furnace, and improve the utilization efficiency of the steam produced by the vaporization and cooling of the heating furnace.

The steam superheater is installed in the flue, through the waste heat of the flue gas, the saturated steam produced by the heating furnace is heated into superheated steam, and the superheating of the steam is realized without consuming other energy sources.

The steam superheating device in the present invention can use the flue gas generated by the heating furnace to exchange heat with the saturated steam without affecting the normal production of the heating furnace, and heat the saturated steam produced by the heating furnace to superheat, which can meet the requirements of the refining vacuum pump, and at the same time, it can be used with the steam After the heat exchange, the temperature of the flue gas decreases and the heat of the flue gas is recovered. Therefore, using the self-produced saturated steam superheating device of the heating furnace to make the saturated steam reach the superheated temperature and then be used by the refining vacuum pump can improve the energy utilization rate of the heating furnace and improve the steelmaking → continuous casting → steel rolling The level of integration has obvious economic and social benefits.

Third: Steelmaking and steel rolling vaporization cooling waste heat boiler steam supply system

The converter vaporization cooling system is produced synchronously with the steelmaking converter, which is a periodic intermittent working system. Although the vaporization system produces a large amount of steam, if the heat storage capacity of the system is small, there will not be enough steam to be continuously and stably used by the vacuum pump. After the converter vaporization cooling system is established to supply steam to the vacuum pump, the important problem that needs to be solved urgently is to make the converter vaporization cooling system have sufficient heat storage capacity to ensure that the steam output of the converter vaporization cooling is greater than the steam consumption of the vacuum pump. And improving the unit heat storage capacity of the heat accumulator is the primary measure to increase the heat storage capacity of the vaporization cooling system. Under the premise that the volume of the heat accumulator has been fixed and does not exceed the allowable working pressure of the vaporization system, the heat charging pressure of the heat accumulator is increased, and the pressure difference between the heat charging pressure and the heat release pressure is enlarged, so that the unit heat storage capacity of the heat accumulator can be increased. Increase, so that the overall heat storage capacity of the vaporization cooling heat accumulator is improved. The steam production capacity of converter vaporization cooling is greater than the steam used for refining and vacuuming. Therefore, the regenerators in the steelmaking workshop are divided into high and low pressure operations. The high pressure regenerators are used to ensure the refining and vacuuming. The heat accumulator is supplied to the steam pipe network in the factory after being stabilized, stored and pressure regulated by the low-pressure heat accumulator.

The vaporization and cooling of the heating furnace is a continuous working system. After reheating, all the steam produced by the heating furnace is sent to the steelmaking workshop, part of it is used for the steam mixing device, and the rest is sent to the low-pressure heat accumulator. After the pressure is adjusted, it is supplied to the steam pipe network in the factory area, so that the vaporization cooling system of the heating furnace is always operated at a higher pressure level, which is beneficial to the protection of the bottom water pipe of the heating furnace, and at the same time improves the utilization efficiency and reserve pressure of the vaporization cooling steam production of the heating furnace, ensuring steelmaking Implementation of waste heat utilization projects such as saturated steam power generation in factories.

Fourth: Long-distance superheated steam pipeline transportation

(1) Install a steam drain device on the long-distance superheated steam transmission pipeline to solve the problem of water accumulation in the pipeline and improve the efficiency of steam transmission;

(2) Part of the steam supplied by the heating furnace is supplied to the refining and mixing device, and the rest is sent to the low-pressure heat accumulator. The minimum opening of the flow regulating valve is set at 5%, and superheated steam is always circulated to the low-pressure heat accumulator, so that even the vacuum refining furnace When the vacuum is stopped, it can also ensure the continuous flow of steam in the superheated steam pipeline, avoid the static condensation of steam in the pipeline into water, and realize that the superheated steam pipeline for refining is always in a hot standby state, and can meet the refining vacuum production requirements at any time;

(3) Use heat-insulated pipe brackets on superheated steam pipes to reduce pipe heat loss, save energy and reduce consumption.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

Fig. 1 is a system diagram of the present invention;

Fig. 2 is a steam mixing device diagram;

Fig. 3 is a diagram of a heating furnace vaporization cooling steam superheating device;

Fig. 4 is the steam system diagram for steelmaking and steel rolling vaporization cooling;

Fig. 5 is a diagram of a steam trap;

Figure 6 is a diagram of a heat insulating pipe bracket.

Among them: 1-steam mixer, 2-main regulating valve of saturated steam pressure, 3-auxiliary regulating valve of saturated steam pressure, 4-superheated steam temperature regulating valve, 5-superheated steam pressure regulating valve, 6-self-supporting pressure regulating valve, 7-superheated steam start and release regulating valve, 8-superheated steam pipeline, 9-saturated steam cut-off valve, 10-saturated steam pipeline, 11-superheated steam flow meter, 12-superheated steam cut-off valve, 13-superheated steam pipeline after mixing, 14-steam superheater, 15-steam pressure regulating valve, 16-saturated steam pipeline generated by vaporization and cooling of heating furnace, 17-flue gas generated by combustion of heating furnace, 18-flue of heating furnace, 19-gasification and cooling of converter flue Saturated steam production, 20-steam pressure regulating valve of converter vaporization cooling system, 21-saturated steam pressure regulating valve, 22-flow regulating valve, 23-low pressure accumulator for pipeline network, 24-steam drainage device, 25-heat insulation Bracket, 26-high pressure heat accumulator, 27-steelmaking and steel rolling vaporization cooling waste heat boiler supply low-pressure saturated steam pipeline, 28-decompression regulating valve.

As can be seen from Fig. 1, the present invention is divided into three systems: I-steam mixing device, II-heating furnace vaporization cooling steam superheating device, III-steelmaking and steel rolling vaporization cooling supply steam system.

It can be seen from Fig. 2 that a cut-off valve 9 is set at the place where the saturated steam of the converter vaporization cooling system enters the mixing device through a pipeline 10, and a cut-off valve 12 is set at the place where the superheated steam 8 supplied by the heating furnace vaporization cooling steam superheating device enters the mixing device. Before the steam enters the static mixer 1, the pressure and temperature are adjusted respectively. The main pressure regulating valve 2 and the auxiliary pressure regulating valve 3 are installed on the saturated steam supply pipeline of the converter vaporization cooling system. The regulating signal is taken from the pressure equalizing pipe section after the mixer, which is as close as possible to the refining sub-cylinder, and the auxiliary regulating valve 3 is a small flow regulating valve. , that is, it is used when the amount of steam used for vacuuming is small. When the steam consumption increases, the steam main regulating valve 2 is put into operation to ensure the stability of the steam pressure for vacuuming; the superheated steam supplied by the heating furnace vaporization cooling steam superheating device passes through the pipeline 8 A cut-off valve 12 is set at the place where it enters the mixing device. After passing through the temperature regulating valve 4 and the pressure regulating valve 5, it enters the mixing device to ensure the stability of the constant pressure steam supply for vacuuming and the amount of superheated steam entering the mixer. In the start-up phase, when the temperature of the steam in the pipeline after mixing is lower than the set value, the superheated steam starts to release the regulating valve 7 to open, increase the flow rate of the superheated steam, and increase the temperature of the superheated steam entering the mixer. When the temperature exceeds the starting temperature of the mixing device , the regulating valve 7 is closed. The temperature and pressure of the steam mixing device are taken from the pressure equalizing pipe section behind the mixer, and are supplied to the refining sub-cylinder after being regulated by the self-supporting pressure stabilizing valve 6. The steam mixing device is equipped with overpressure protection.

It can be seen from Fig. 3 that the saturated steam produced by vaporization and cooling of the heating furnace enters the steam superheater 14 installed in the flue 18 of the heating furnace through the pressure regulating valve 15, and the saturated steam produced by the heating furnace is heated into superheated steam by the waste heat of the flue gas 17 , to achieve steam superheating without consuming other energy sources. The regulating signal of the regulating valve 15 is taken from the reheated superheated steam pipeline 8, and the temperature measuring point is close to the refining steam point (or the sub-cylinder temperature signal is communicated to the heating furnace operating room through the steel plant automation system). The steam mixing device is equipped with over-temperature protection.

It can be seen from accompanying drawing 4 that the steam produced by the converter vaporization and cooling in the steelmaking workshop is sent to the heat accumulator 26 through the pipeline 19. In order to ensure the steam supply to the refining vacuum, the heat accumulator 26 operates under a relatively high pressure state; when the steam supply is greater than When refining the amount of steam used for vacuuming, the excess steam is sent to the heat accumulator 23 through the V2 valve, and a pressure regulating valve 21 is set before entering the heat accumulator. The steam pressure is adjusted to the user pressure of the pipe network in the factory area or the saturated steam facility in the steelmaking plant. After being adjusted by the pressure-reducing regulating valve 28, it is supplied to the user through the steam pipeline 27, so the heat accumulator 23 operates at a lower pressure. When the amount of superheated steam supplied by the heating furnace is greater than the amount of steam used for refining and vacuuming, the excess steam is sent to the accumulator 23, and then enters the accumulator after passing through the flow regulating valve 22, and the adjustment signal is taken from the flow meter on the pipeline 8 of the steam mixing device 11. When the flow rate of the superheated steam pipeline 8 is less than the set value, the regulating valve starts to work, the minimum opening of the flow regulating valve 22 is set at 5%, the regulating valve is always in the open state, and there is always superheated steam flowing to the heat accumulator 23 , which can ensure that the superheated steam pipeline 8 is always in a hot standby state.

A steam drainage device 24 is arranged on the long-distance superheated steam pipeline 8 to solve the problem of water accumulation in the pipeline and improve steam delivery efficiency. The heat-insulating pipe bracket 25 is used on the pipeline 8 to reduce the heat loss of the steam pipeline, save energy and reduce consumption.

The present invention is applicable to the construction of vacuum pump steam source device when new and old converter steelmaking plants adopt vacuum refining technology. When the steelmaking plant has no steel rolling heating furnace, a small amount of medium-pressure steam can be extracted and mixed with converter vaporization cooling steam for refining and vacuuming use. The coverage is relatively wide, especially suitable for old factories to add vacuum refining furnaces to solve steam problems.

Claims (4)

1, a kind of saturation steam and superheated vapour are mixed for the device that vacuum refining furnace uses, comprise flue, thermophore, variable valve, steam-water pipeline, it is characterized in that: also comprise vapor mixing device and steam superheating device, steam superheating device comprises vapor superheater (14) and vapor pressure variable valve (15), and the vapor mixing device comprises static steam mixer (1) and pressure regulator valve; The self-produced saturation steam of process furnace vaporization cooling enters vapor superheater (14) behind saturation steam pipeline (16), pressure regulator valve (15), vapor superheater (14) is arranged in the flue (18), waste heat by flue gas (17), the self-produced saturation steam of process furnace is heated to be superheated vapour, under the condition that does not consume other energy, realize steam superheating, consequent superheated vapour is sent into the vapor mixing device through pipeline (8), enters steam mixer (1) through temperature control valve (TCV) (4), vapor pressure variable valve (5); The self-produced saturation steam of converter vaporization cooling enters steam mixer (1) behind pressure main inlet control valve (2), pressure auxiliary adjustment valve (3), saturated steam and superheated vapour carry out the temperature and pressure requirement that mixed heat transfer reaches setting in mixing tank (1), use for the vacuum refining furnace vacuum pump; Process furnace vaporization cooling is steamed by sending into low pressure thermophore (23) with the vapour part greater than refining after flow control valve (22) is regulated in the superheated vapour of vapor superheater (14) back generation, converter vaporization cooling is steamed and is sent into low pressure thermophore (23) greater than refining with the vapour part behind saturated vapor pressure force regulating valve (21), through thermophore (23) storage, voltage stabilizing, by sending into plant area's pipe network behind the decompression valve (28), use for the saturation steam facility.

2, saturation steam as claimed in claim 1 and superheated vapour are mixed for the device that vacuum refining furnace uses, it is characterized in that: the minimum aperture of described flow control valve (22) is set at 5%, all the time there is superheated vapour to be circulated to low pressure thermophore (23), guarantees that superheat steam pipeline (8) is in heat and is equipped with state.

3, saturation steam as claimed in claim 1 or 2 and superheated vapour are mixed for the device that vacuum refining furnace uses, and it is characterized in that: length is provided with steam steam trap connection (24) and heat insulation bracket (25) apart from superheat steam pipeline (8).

4, saturation steam as claimed in claim 1 and superheated vapour are mixed for the device that vacuum refining furnace uses, it is characterized in that: thermophore is pressed high and low pressure classification setting, the self-produced saturation steam of steelshop converter flue vaporization cooling (19) is delivered to high pressure thermophore (26) for refining vapour through pipeline, and part more than needed supplies plant area's pipe network vapour through low pressure thermophore (23).

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