Energy-saving process of coking primary cooling system

Abstract

The invention relates to an energy-saving process of a coking primary cooling system, which comprises a cooling circulating pump, a transverse pipe cooler, a heat exchange station, an air cooling tower, a closed cooling tower and a refrigeration station which are sequentially connected through a circulating pipeline, and a salt-free cooling liquid in the circulating pipeline is pressurized by the cooling circulating pump and then enters from a cooling medium inlet in the lower part of the transverse pipe cooler; the salt-free cooling liquid exchanges heat with hot gas introduced from a hot raw coke oven gas inlet, the heated salt-free cooling liquid is discharged from a cooling medium outlet in the upper part of the transverse pipe cooler and enters a heat exchange station, and the salt-free cooling liquid subjected to heat exchange and cooling in the heat exchange station enters an air cooling tower for cooling, then enters a closed cooling tower for spraying and cooling and then enters a refrigeration station; and finally, the water enters the inlet of the cooling circulating pump again, so that a fully-closed circulating channel is formed. According to the process, the saved energy consumption accounts for more than 90% of that of the conventional process, about 80% of water consumption can be saved, the high-consumption and high-cost conventional process has positive benefits of earning money, emission reduction and environmental protection are realized, the cost is reduced, the efficiency is improved, and the technical difficulties in the conventional process are solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coking, and particularly relates to an energy-saving process for a coking primary cooling system. BACKGROUND

[0002] In a conventional coking primary cooling process, a primary cooler is divided into an upper section and a lower section. Coke oven-derived raw gas at about 84 DEG C is cooled to below 40 DEG C by a horizontal tube cooler (referred to as a horizontal cooler) in the primary cooling process. During the cooling process in the upper section of the primary cooler, an open cooling tower and a large water pump are needed to cool the cooling water, and the open cooling tower brings many disadvantages. For example, during continuous evaporation and cooling of the circulating cooling water, the concentration of salts is continuously increased. Despite continuous blowdown and addition of scale inhibitors, a large amount of scale is still attached to the inner wall of the pipeline of the primary cooling process after a long period of operation. The thermal conductivity of the scale is generally only 1 / 50-1 / 120 of that of steel, which greatly increases the system resistance and significantly reduces the heat exchange effect of the cooler. In the conventional process, the horizontal tube cooler often needs to be stopped for cleaning or replacement of the pipeline during operation, which affects the production yield, increases the operation and maintenance costs, and greatly shortens the service life of the equipment.

[0003] In terms of energy consumption, the conventional primary cooling process is also very large. Not only does the scale cause an increase in the resistance of the pipeline system and the long-term wear of the water pump, which reduces the performance of the water pump, but also the circulating water drops along the pipeline to the open cooling tower during the entire circulation process, resulting in a waste of the potential energy. In terms of water consumption, the open cooling tower uses the heat of vaporization of part of the circulating water to cool itself (circulating water) and 2-5% blowdown water (salt water), and the water consumption is very high. In terms of environmental protection, a large amount of blowdown water is discharged. Although closed cooling towers have been popular in many fields, they have not been applied in the coking primary cooling process. The process combination and details have led to a blank in this field. SUMMARY

[0004] In view of the above, the present application aims to solve the technical problems in the field by providing an energy-saving process for a coking primary cooling system to overcome the shortcomings of the prior art.

[0005] To achieve the above-mentioned purposes, the present application adopts the following technical solutions: The energy-saving process of the coking primary cooling system comprises a cooling circulating pump, a horizontal pipe cooler, a heat exchange station, an air cooling tower, a closed cooling tower and a refrigeration station connected in sequence through a circulating pipeline, the circulating pipeline is filled with salt-free cooling liquid, the horizontal pipe cooler is provided with a hot raw gas inlet at the top and a gas outlet at the bottom, the salt-free cooling liquid in the circulating pipeline is pressurized by the cooling circulating pump and then enters the cooling medium inlet at the lower part of the horizontal pipe cooler to exchange heat with the hot gas introduced from the hot raw gas inlet, the heated salt-free cooling liquid is discharged from the cooling medium outlet at the upper part of the horizontal pipe cooler and enters the heat exchange station, the heat exchange station supplies the heat recovered by heat exchange to the refrigeration station, the salt-free cooling liquid cooled by the heat exchange station enters the air cooling tower for cooling, the closed cooling tower is internally provided with a cooling pipeline and an external cooling spray head, the external cooling spray head is used for spraying the cooling pipeline, the external cooling spray head is supplied with external cooling water, the salt-free cooling liquid discharged from the heat exchange station enters the cooling pipeline for spraying and cooling and then enters the refrigeration station, the salt-free cooling liquid cooled by the refrigeration station reenters the inlet of the cooling circulating pump, so that a full-closed circulating channel is formed.

[0006] In order to better realize the present application, further optimization is made in the above structure, and a desalted water tank and a constant pressure liquid supplementing pump are further included, the desalted water tank is connected to the medium pressure stabilizing tank or the towerless water supply device through the constant pressure liquid supplementing pump, and the medium pressure stabilizing tank or the towerless water supply device is connected to the highest liquid level of the salt-free cooling liquid.

[0007] In order to better realize the present application, further optimization is made in the above structure, and the horizontal pipe cooler is the highest liquid level of the salt-free cooling liquid, and the medium pressure stabilizing tank or the towerless water supply device is arranged at the top of the horizontal pipe cooler and is connected to the highest liquid level inside.

[0008] In order to better realize the present application, further optimization is made in the above structure, and a pressure loss protector is connected above the cooling medium outlet.

[0009] In order to better realize the present application, further optimization is made in the above structure, and the external cooling water is supplied to the external cooling spray head through a cooling water pump.

[0010] In order to better realize the present application, further optimization is made in the above structure, and the external cooling spray head comprises an external cooling upper spray head arranged at the top of the closed cooling tower and an external cooling lower spray head arranged at the bottom of the closed cooling tower.

[0011] In order to better realize the present application, further optimization is made in the above structure, and the heat recovered by heat exchange of the heat exchange station is used to heat lithium bromide solution in the refrigeration station, and refrigerant water vapor is separated out, and then condensed, throttled and evaporated to realize refrigeration by heat absorption.

[0012] In order to better realize the present application, further optimization is made in the above structure, and a heating station is further included, and the heat exchange station supplies the heat recovered by heat exchange to the heating station.

[0013] In order to better realize the present application, further optimization is made in the above structure, the heat exchanger station supplies the heat recovered by heat exchange to the refrigeration station in the hot season, and supplies the heat recovered by heat exchange to the heating station in the cold season.

[0014] In order to better realize the present application, further optimization is made in the above structure, the salt-free cooling liquid is pure water or heat-conducting oil.

[0015] The present application has the following beneficial effects compared with the prior art: 1. Energy saving: the total power of the circulating cooling salt-free water pump and the external cooling water pump is 55kw, and the power consumption is less than 5% of the conventional process; the water consumption is only 20% of the conventional process, and the power consumption is saved by at least 90% through the two measures. 2. Efficiency: the use of 72℃ high-quality heat source of salt-free water creates benefits much higher than the power consumption of the process, making the high-consumption negative benefits of the conventional process into positive benefits.

[0016] 3. No scaling: the cooling medium circulates in a closed pipeline, and the loss and replenishment are very small, so the salt-free medium with high price can be used as the circulating medium, which not only solves the problem of pipeline scaling, but also improves the heat exchange efficiency of the heat exchanger, and greatly reduces the equipment maintenance.

[0017] 4. High efficiency: the scaling problem of the cooling medium is solved, the heat exchange efficiency is improved, the heat carrying rate of the cooling medium is increased by about 5 times, the cooling medium is reduced by about 4 / 5, and the power consumption is also greatly reduced.

[0018] 5. Low water consumption: the cooling medium above 72℃ is suitable for air cooling tower cooling, thereby reducing the external cooling water consumption by about 80%.

[0019] 6. Easy to clean: the amount of scale generated by the external cooling water is reduced by about 4 / 5, and all the scale is exposed on the outer surface of the heat exchanger of the closed cooling tower, which is easy to clean and does not affect the operation of the equipment.

[0020] 7. Long equipment life: the cross tube bundle of the cross tube cooler does not scale, avoids frequent maintenance and frequent corrosion caused by residual oxidation due to frequent maintenance and emptying in the shell, and can at least double the equipment life.

[0021] 8. Reduced investment: due to the large reduction in the circulating amount of the cooling medium and the elimination of the need to consider the head, the size of the supporting pipeline, water pump and other equipment is greatly reduced, so the water pump can be arranged in the foundation frame of the cross tube cooler, and there is no need to build a large underground pump house and underground water tank, and the investment in the water pump and pump house is less than 1 / 10 of the conventional process.

[0022] 9. More environmentally friendly: electric power and secondary energy such as steam have environmental costs, so energy saving and consumption reduction is equivalent to emission reduction; secondly, the system reduces at least 4 / 5 of the chemical agents for descaling, which is easy to handle and does not affect production during the handling process. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings described below are only some of the embodiments of the present application, and all other embodiments obtained by those of ordinary skill in the art without creative labor based on these drawings also belong to the scope of protection of the present application.

[0024] Figure 1 is a flow chart of the energy saving process of the coking primary cooling system provided by the present application; Figure 2 is a flow chart of the conventional process.

[0025] In the figure: 1-cooling circulating pump, 2-cooling medium inlet, 3-cross pipe cooler, 4-cross pipe bundle, 5-hot raw gas inlet, 6-cooling medium outlet, 7-coal gas outlet, 8-pressure loss protector, 9-salt-free cooling liquid, 10-tower-free water supply device, 11-heat exchange station, 12-heating station, 13-air cooling tower, 14-closed cooling tower, 15-outer cooling upper spray head, 16-cooling water pump, 17-outer cooling water, 18-outer cooling lower spray head, 19-refrigeration station, 20-constant pressure liquid supplement pump, 21-desalination water tank; 51-lower section circulating cooling water pump, 52-middle section circulating cooling water pump, 53-upper section circulating cooling water pump, 54-lower section cooling medium inlet, 55-lower section cooling medium outlet, 56-refrigeration station two, 57-coal gas outlet two, 58-lower section cross pipe bundle, 59-middle section cooling medium inlet, 60-middle section cooling medium outlet, 61-upper section cooling medium inlet, 62-upper section cooling medium outlet, 63-middle section cross pipe bundle, 64-upper section cross pipe bundle, 65-raw gas inlet two, 66-circulating cooling water evaporation mist, 67-open cooling tower, 68-underground water pool, 69-cooling water, 72-cross pipe cooler two, 73-pump house. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present application more clear, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor also belong to the scope of protection of the present application.

[0027] In the description of the present application, it is to be noted that, unless otherwise specified, the meaning of "a plurality of" is two or more; the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present application, it is to be noted that, unless otherwise specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0029] As shown in Figure 1 The flow chart of the coking primary cooling system energy-saving process provided by the present application includes a cooling circulating pump 1, a horizontal pipe cooler 3, a heat exchange station 11, an air cooling tower 13, a closed cooling tower 14 and a refrigeration station 19 connected in sequence through a circulating pipeline, and a non-saline cooling liquid 9 is injected into the circulating pipeline, and the non-saline cooling liquid 9 is pure water or heat-conducting oil. This process uses non-saline water as a cooling medium and operates in a closed cycle, which can effectively utilize the potential energy of the circulating cooling water. The kinetic energy of the circulating cooling water rising height H1 is equal to the potential energy of the descending height H2, so the water pressure on both sides is balanced, and the cooling circulating pump 1 only needs to overcome the system resistance in the closed pipeline to make the non-saline cooling liquid 9 circulate normally. The non-saline cooling liquid 9 basically does not produce water scale in the circulating pipeline, which can greatly reduce the system resistance in the pipeline. The temperature after heat exchange is increased by about 5 times or even more, i.e. the thermal duty of the cooling medium is increased by about 5 times, so the circulating water volume can be reduced by about 80%. When the cooling medium is not more than 100℃, compared with the conventional process, the use of non-saline water can effectively absorb the heat of hot coal gas to increase the temperature to about 72℃ or more, and the heat absorption of the cooling medium is greatly improved, which not only can greatly reduce the circulating water volume, but also can greatly reduce the energy consumption of the cooling circulating pump 1, thereby greatly reducing the cost.

[0030] The horizontal tube cooler 3 is provided with a hot raw gas inlet 5 at the top and a gas outlet 7 at the bottom. The raw gas produced by the coke oven enters the horizontal tube cooler 3 from the hot raw gas inlet 5 and flows down to the gas outlet 7. The salt-free cooling liquid 9 in the circulating pipeline is pressurized by the cooling circulating pump 1 and then enters the horizontal tube cooler 3 from the cooling medium inlet 2 at the lower part of the horizontal tube cooler 3 and flows up along the pipes of the internal horizontal tube bundle 4. During this period, the salt-free cooling liquid 9 exchanges heat indirectly with the hot gas introduced from the hot raw gas inlet 5, so that the raw gas is reduced to a predetermined temperature and is discharged from the gas outlet 7. The temperature of the salt-free cooling liquid 9 is raised to about 72°C or higher and is discharged from the cooling medium outlet 6 at the upper part of the horizontal tube cooler 3.

[0031] The salt-free cooling liquid 9 discharged from the cooling medium outlet 6 enters the heat exchange station 11. In the hot season, the heat exchange station 11 supplies the heat recovered by heat exchange to the refrigeration station 19, and in the cold season, the heat exchange station 11 supplies the heat recovered by heat exchange to the heating station 12. The refrigeration station 19 heats the lithium bromide solution by the heat recovered by the heat exchange station 11, separates the refrigerant water vapor, and then evaporates and absorbs heat after condensation and throttling to achieve refrigeration.

[0032] The salt-free cooling liquid 9 that has recovered part of the heat through the heat exchange station 11 then enters the air cooling tower 13 for cooling. At this time, the temperature difference between the salt-free cooling liquid 9 and the air is still large, so the heat exchange effect of the air cooling tower 13 is very good. After being cooled by the air cooling tower 13, the temperature of the salt-free cooling liquid 9 is reduced to about 40°C and then enters the closed cooling tower 14.

[0033] The closed cooling tower 14 is internally provided with a cooling pipeline and an external cooling spray head, which includes an external cooling upper spray head 15 arranged at the top of the closed cooling tower 14 and an external cooling lower spray head 18 arranged at the bottom of the closed cooling tower 14. The external cooling spray head is used to spray the cooling pipeline, and the external cooling water 17 is supplied to the external cooling spray head by the cooling water pump 16, which indirectly absorbs a large amount of heat from the salt-free cooling liquid 9. Part of the external cooling water 17 will evaporate and take away heat, and at the same time, the salt-free cooling liquid 9 in the pipeline will be reduced to below 32°C. After being cooled by spraying in the cooling pipeline, the salt-free cooling liquid 9 enters the refrigeration station 19. After being cooled by the refrigeration station 19, the salt-free cooling liquid 9 reenters the inlet of the cooling circulating pump 1, thereby forming a full-closed loop circulation channel.

[0034] In the embodiment, the desalted water tank 21 and the constant pressure liquid supplement pump 20 are further included, the desalted water tank 21 is connected to the medium pressure tank or the towerless water supply device 10 through the constant pressure liquid supplement pump 20, and the medium pressure tank or the towerless water supply device 10 is connected to the highest liquid level of the desalted cooling liquid 9. The horizontal tube cooler 3 is the highest liquid level of the desalted cooling liquid 9, and the medium pressure tank or the towerless water supply device 10 is arranged at the top of the horizontal tube cooler 3 and connected to the highest liquid level of the internal horizontal tube bundle 4. The medium pressure tank and the towerless water supply device have the function of automatic exhaust, and the gas in the circulating channel is automatically exhausted. The medium pressure tank is a high tank without power supply, and is not affected by power failure. If the medium pressure tank cannot be arranged at the top of the horizontal tube cooler 3, the towerless water supply device with automatic control can be used instead. The desalted water tank 21 and the constant pressure liquid supplement pump 20 can supplement the circulating cooling water, stabilize the pressure of the desalted cooling liquid 9, and ensure that the circulating cooling water in the closed loop pipe always circulates to prevent air from entering to cause the circulating cooling water to be cut off at a high position, increase the load of the cooling circulating pump 1, cause the pump to be damaged, and cause the factory to stop production and maintenance. The pressure protector 8 is connected above the cooling medium outlet 6 to prevent the pressure imbalance inside and outside the pipe, and to protect the safety of the pipe and the equipment. The pressure protector 8 first ensures that when an accident such as power failure (i.e. no premonition power failure) occurs and the water cannot be supplemented or the circulating water leaks, the pressure protector 8 can automatically open the air inlet channel to prevent the horizontal tube bundle 4 from being sucked flat due to the rapid drop of the water level and losing pressure, which causes the horizontal tube bundle 4 to be sucked flat. Once the equipment is damaged, it needs to be replaced, which may cause the whole factory to stop production for about one week, resulting in great loss and a large amount of raw coal gas being discharged and burned to pollute the environment. The pressure protector 8 can also be used to automatically exhaust the gas generated in the horizontal tube cooler 3 and the circulating pipeline during normal operation, prevent the circulating water of the horizontal tube bundle 4 at the top of the horizontal tube cooler 3 from being cut off, and cause the water pump pressure to increase dramatically, the power consumption to increase, and the motor to be burned out.

[0035] The process adopts a complete closed loop circulation, fully and effectively utilizes the potential energy of the circulating cooling water, and converts the gravitational potential energy generated by the descending height H2 of the circulating cooling water into kinetic energy of the circulating cooling water rising, thereby saving the energy consumption of the cooling circulating pump 1 overcoming the head. In the conventional process, the circulating pump power is very large because the head is particularly high. In addition, compared with the conventional process, the desalted cooling liquid 9 of the process can be heated to above 72℃, and the efficiency is increased by about 5 times, thereby reducing the circulating cooling water volume to about 1 / 5 of that of the conventional process. In summary, the cooling circulating pump 1 of the process can reduce the energy consumption by more than 90% compared with the conventional process. Hot coal gas can be analogized to similar industrial fields, such as oxygen plants and LNG plants, various hot gases with gas compression and heating, or other processes requiring cooling of hot gases.

[0036] The high-temperature salt-free cooling liquid 9 at 72°C can be used as a high-quality heat source, such as winter heating, heat source for a refrigeration station in a hot season, water vapor for an ammonium sulfate section, etc., so that the waste heat is recycled, and the environment is protected and the cost is saved. The salt-free cooling liquid 9 recovered by the heat is still high in temperature compared with air, so the air cooling tower 13 is used to exchange heat with a large amount of air, so that the temperature is reduced to about 40°C, and then the temperature is reduced to below 32°C in the closed cooling tower 14. The outer cooling water 17 in the closed cooling tower 14 only needs 1 / 5 of the amount of the conventional process, and the energy consumption of the outer cooling water pump 16 is greatly reduced, only 3m-5m head is needed to meet the requirements, and the evaporation amount of the outer cooling water 17 is also reduced by 4 / 5 compared with the conventional process.

[0037] Therefore, the coking primary cooling system of the process saves more than 90% of the energy consumption of the conventional process, and also saves about 80% of the water consumption. The conventional process with high consumption and high cost is made into a positive benefit of making money, which reduces environmental protection and reduces cost and increases efficiency.

[0038] The system flow of the process is as follows: the salt-free cooling liquid 9 is pressurized by the cooling circulating pump 1, enters the lower cooling medium inlet 2 of the horizontal tube cooler 3 from the horizontal tube cooler 3, and rises along the tube side of the horizontal tube bundle 4, and exchanges heat with the hot raw coal gas entering the shell side of the horizontal tube cooler 3 from the top hot raw coal gas inlet 5 of the horizontal tube cooler 3 and discharged from the lower gas outlet 7. The cooling salt-free water is circulated in the closed circuit, which can achieve the three purposes of no scaling in the tube side, greatly reducing the cooling water circulation amount, and obtaining high-quality heat source to recycle waste heat. The salt-free cooling liquid 9 receives heat from the hot gas to obtain high-quality heat source, and the high-quality heat source is transported to the device needing heat source nearby through the cooling medium outlet 6 at the upper part of the horizontal tube cooler 3 and the connecting pipeline, and the heat is utilized, so that the waste heat is recycled. The cooling water temperature is still high after passing through the heat exchange station 11, and is suitable for being reduced to about 40°C by the air cooling tower 13; the heat on the finned tube is indirectly and effectively dissipated by a large amount of cooling air in the air cooling tower 13, so that the salt-free cooling liquid 9 is reduced to the lowest possible temperature and enters the closed cooling tower 14; the salt-free cooling liquid 9 exchanges heat with the outer cooling water 17 in the closed cooling tower 14, a part of the outer cooling water 17 evaporates to convert the sensible heat into water vapor containing latent heat and is discharged into the atmosphere, so that the temperature of the salt-free cooling liquid 9 is reduced to the rated temperature range, and then enters the next cycle through the cooling circulating pump 1, so as to form a closed circuit.

[0039] For example, Figure 2The flow chart of the conventional process is shown. As can be seen from the figure, the horizontal tube cooler 72 in the conventional process is divided into upper, middle and lower sections. The lower section cooling water is cooled to 16°C by the refrigeration station 56, and then pumped into the lower section horizontal tube bundle 58 by the lower section circulating cooling water pump 51, enters from the lower section cooling medium inlet 54, goes up to the lower section cooling medium outlet 55, and is discharged again to the refrigeration station 56 for refrigeration.

[0040] The cooling water 69 in the upper and middle sections is pressurized by the middle section circulating cooling water pump 52 and the upper section circulating cooling water pump 53, and then lifted to the top of the middle section horizontal tube bundle 63 and the upper section horizontal tube bundle 64 in the horizontal tube cooler 72, respectively. The pump pumps the cooling water 69 to the highest height H3. However, the potential energy of the cooling water 69 cannot be utilized because the cooling water 69 will be directly sprayed and cooled in the open cooling tower 67 after being discharged from the horizontal tube cooler 72. Therefore, a very powerful pump is needed to meet the head requirement. The large power of the circulating water pump results in a very large volume, so a very large pump house 73 needs to be built, which not only occupies a large area but also greatly increases the investment cost. The energy consumption of the circulating water pump is very high, not only because the head requirement needs to be met, but also because the system resistance is very large due to frequent fouling in the pipe. The conventional process only relies on water evaporation to remove heat, so a large amount of water resources is consumed.

[0041] Taking a 1.8 million tons / year coking plant primary cooling system as an example, the known conditions are as follows: The amount of raw gas generated by the coke oven per hour is 100000 Nm 3 The upper section gas temperature of the horizontal cooler is cooled from 84°C to 36°C, and the total heat released is: 100000 x (655.04-43.74) = 61330000 (kcal); In the formula, 655.04 and 43.74 are the total heat enthalpy of each at 84°C and 36°C, respectively, when the gas per standard meter is saturated by water vapor, with the unit of kcal; In the conventional process, the water temperature is designed to be increased from 32°C to 40°C to slow down the fouling in the cooling water pipe. In early designs, the water temperature is designed to be increased from 32°C to about 43°C or 45°C, but the fouling rate is significantly accelerated; In this process, the cooling medium is salt-free water, which can completely prevent fouling in the pipe, so the water temperature can be designed to be increased from 32°C to 72°C; The latent heat and sensible heat taken away by the closed cooling tower or open cooling tower per kg of water evaporated is 540 kcal.

[0042] If the two processes are implemented, the effects are completely different.

[0043] First embodiment of the conventional process: In the conventional process, the water temperature is increased from 32°C to 40°C, with a temperature difference of 8°C, so the circulating cooling water quantity is: 61330000÷8=7666250 (kg / h)≈7666 t / h (water specific heat capacity is 1 kcal / kg·℃).

[0044] Considering the pump wear and tube fouling resistance, the general flow is selected as 3000 m 3 / h, the head is 57 m, the motor power is 600 kw of double suction pump, 3 for 1 spare, that is, 3 simultaneous operation, the total power of synchronous motor is: 600 kw×3=1800 kw.

[0045] The evaporation of open cooling tower water is (another increase in medium sensible heat is very small, which can be ignored): 61330000÷540=113574 (kg / h)≈114 t / h. The second embodiment of the conventional process: If the water temperature of the conventional process is raised from 32℃ to 43℃ (the fouling rate of the tube is obviously higher than the first embodiment, so the equipment is frequently maintained, and the equipment life is shortened), the temperature difference is 11℃, and the circulating cooling water quantity is still very considerable: 61330000÷11=5575455 (kg / h)≈5575 t / h; The flow is still selected as 3000 m 3 / h, the head is 57 m, the motor power is 600 kw of double suction pump, 2 for 1 spare, that is, 2 simultaneous operation, the total installed power of synchronous operation is: 600 kw×2=1200 kw.

[0046] The evaporation of open cooling tower water is the same as the first embodiment.

[0047] Embodiment of the process: The cooling medium of the process is selected as salt-free water, so its temperature can be raised from 32℃ to 72℃, the temperature difference is 40℃, and the cooling water quantity is: 61330000÷40=1533250 (kg / h)≈1533 t / h; Since the process only considers overcoming system resistance, and does not have to consider head and fouling resistance, the circulating salt-free cooling liquid pump flow is selected as 1600 m 3 / h, the head is 7 m (only used to overcome system resistance), and the motor power is 39 kw of low head mixed flow pump, 1 for 1 spare; The temperature of the cooling medium after the heat exchange station is still very high, and it is appropriate to use an air cooling tower to reduce the water temperature to 40℃; then use a closed cooling tower to reduce the salt-free water from 40℃ to 32℃, the temperature drop is 8℃. The closed cooling tower mainly reduces the temperature of the salt-free water to below 32℃ by evaporating part of the external cooling water to absorb heat, and the evaporation quantity is: 1533250 x 8 ÷ 540 = 22715 (kg / h) ≈ 22.7 t / h; According to its evaporation amount, the outer cooling water pump flow is selected as 900 m 3 / h, and the low-head mixed flow pump with a head of 5 m can be used, and the pump matching motor power is only 16 kw, 1 for use and 1 for standby.

[0048] The total motor power of the two pumps in synchronous operation is: 39 kw + 16 kw = 55 kw.

[0049] Even if the above matching motor runs at full load all year round, the electricity cost is 0.8 yuan / kwh, and the annual electricity cost is only: 0.8 x 55 x 8760 = 385440 (yuan).

[0050] And the 72℃ high-quality heat source salt-free water can replace the downstream process ammonium sulfate section coal gas preheater heating steam, which can save more than ten thousand tons of steam per year, and the price of steam is generally at least 160 yuan per ton, so the annual cost reduction is about two million yuan, and only this one saved cost is about 10 times the electricity cost, that is, after deducting the electricity cost, it can still save more than one hundred thousand yuan per year, which is equivalent to the coal gas primary cooling system changing the high energy consumption and negative benefit of the conventional process into positive benefit. If the high-quality heat source is used in places that need heat source to create more benefits.

[0051] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any skilled person in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A process for energy saving in a coking primary cooling system, characterized in that: The application relates to a closed cooling system, which comprises a cooling circulating pump (1), a horizontal pipe cooler (3), a heat exchange station (11), an air cooling tower (13), a closed cooling tower (14) and a refrigeration station (19) connected in sequence through a circulating pipeline, wherein a salt-free cooling liquid (9) is injected into the circulating pipeline, the top of the horizontal pipe cooler (3) is provided with a hot raw gas inlet (5), the bottom of the horizontal pipe cooler (3) is provided with a gas outlet (7), the salt-free cooling liquid (9) in the circulating pipeline is pressurized by the cooling circulating pump (1), then enters the cooling medium inlet (2) at the lower part of the horizontal pipe cooler (3), exchanges heat with hot gas introduced from the hot raw gas inlet (5), the heated salt-free cooling liquid (9) is discharged from the cooling medium outlet (6) at the upper part of the horizontal pipe cooler (3) and enters the heat exchange station (11), the heat exchange station (11) supplies the heat recovered by heat exchange to the refrigeration station (19), the salt-free cooling liquid (9) after heat exchange and cooling in the heat exchange station (11) enters the air cooling tower (13) for cooling, the closed cooling tower (14) is internally provided with a cooling pipeline and an external cooling spray head, the external cooling spray head is used for spraying the cooling pipeline, the external cooling spray head is supplied with external cooling water (17), the salt-free cooling liquid (9) discharged from the heat exchange station (11) enters the cooling pipeline for spraying and cooling, then enters the refrigeration station (19), and the salt-free cooling liquid (9) after cooling in the refrigeration station (19) re-enters the inlet of the cooling circulating pump (1), thereby forming a full closed circulating channel.

2. The energy conservation process for coking primary cooling system as claimed in claim 1 wherein: The application further comprises a desalted water tank (21) and a constant pressure liquid supplementing pump (20), the desalted water tank (21) is connected to a medium pressure stabilizing tank or a towerless water supply device (10) through the constant pressure liquid supplementing pump (20), and the salt-free cooling liquid (9) is connected to the medium pressure stabilizing tank or the towerless water supply device (10) above the highest liquid level.

3. The coking quenching system energy saving process of claim 2, wherein: The horizontal pipe cooler (3) is the highest liquid level of the salt-free cooling liquid (9), and the medium pressure stabilizing tank or the towerless water supply device (10) is arranged at the top of the horizontal pipe cooler (3) and is connected to the highest liquid level in the interior.

4. The coking quenching system energy saving process of claim 3, wherein: A pressure loss protector (8) is connected above the cooling medium outlet (6).

5. The coking quenching system energy saving process of claim 1, wherein: The external cooling water (17) is supplied to the external cooling spray head through a cooling water pump (16).

6. The coking quenching system energy saving process of claim 5, wherein: The external cooling spray head comprises an external cooling upper spray head (15) arranged at the top of the closed cooling tower (14) and an external cooling lower spray head (18) arranged at the bottom of the closed cooling tower (14).

7. The coking quenching system energy saving process of claim 1, wherein: The refrigeration station (19) heats lithium bromide solution by the heat recovered by heat exchange of the heat exchange station (11), separates refrigerant water vapor, and realizes refrigeration through condensation, throttling and evaporation.

8. The coking quenching system energy saving process of claim 7, wherein: The application further comprises a heating station (12), and the heat exchange station (11) supplies the heat recovered by heat exchange to the heating station (12).

9. The coking quenching system energy saving process of claim 8, wherein: The heat exchange station (11) supplies the heat recovered by heat exchange to the refrigeration station (19) in the hot season, and supplies the heat recovered by heat exchange to the heating station (12) in the cold season.

10. The coking quenching system energy saving process of claim 1, wherein: The salt-free cooling liquid (9) is pure water or heat-conducting oil.

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