Background technology
Along with the new stage of pursuing recycling economy has been come in China's economic development, further saving energy and reduce the cost has become the important topic that high energy consumption industries such as iron and steel, chemical industry, building materials must be faced.
Passed through enterprise's effort for many years, higher waste heat, the waste gas of grade has obtained effective utilization mostly in the factory, thereby the remaining space of taping the latent power mainly is the low-grade energy that grade is low, quantity big, the reuse difficulty is big, and promptly temperature range is at 90-500 ℃ middle-low temperature heat.Typical middle-low temperature heat has the entrained sensible heat of the steam boiler outlet flue gas of about 300 ℃ of temperature and steel billet, slag etc.
Usually, middle-low temperature heat, especially the method for utilizing of low temperature exhaust heat is this waste heat to be converted into 60-90 ℃ hot water, with this thermal source as worker domestic hot-water or heating cooling.For large and medium-sized enterprise, because worker living area and producing region are far apart usually, this utilizes method obviously is inapplicable.In addition, also there are some low temperature exhaust heat to be converted into the research report (Zhao Xiaowei of steam by adopting the second class absorption heat pump technology, Wang Shukun. second class absorption heat pump and the application prospect in smelter thereof. Shandong metallurgy, 2004,26 (6): 37-39.)., the second traditional class absorption heat pump circulatory system exists three shortcomings, and promptly institute's producing steam pressure is low, the thermal efficiency is low (steam of 1 part of calorific value need consume the low temperature exhaust heat of calorific value more than two parts) and the low-temperature heat source that need be used to cool off.
Summary of the invention
The object of the present invention is to provide a kind of middle-low temperature heat to be converted into the system and method for steam, solved three shortcomings that the above-mentioned second class absorption heat pump system exists.
System of the present invention adopts evaporimeter 1, absorber 2, generator 3 and liquid-feeding pump 9 to form the absorption heat pump open-circuit system.Connect with steam passage 7 between evaporimeter 1 and the absorber 2, connect with first, second absorbent solution pipeline 18,19 between absorber 2, generator 3 and the liquid-feeding pump 9; First heat exchanger 4 places evaporimeter 1, the second heat exchanger 5 to place absorber 2, the three heat exchangers 6 to place generator 3.With the thermal source of 250-1300 ℃ of thermal source as generator 3, add the absorbent solution of heater 3 by the 3rd heat exchanger 6 that places generator 3, make it evaporation and produce steam 21; Absorb the steam of flash-pot 1 and produce absorption heat in absorber 2 absorbent solutions,, make it evaporation and produce first steam 20 by placing second heat exchanger, 5 heating condensate waters of absorber 2; With the thermal source of 90-500 ℃ of middle-low temperature heat as evaporimeter 1, the condensed water of first heat exchanger, 4 heating fumigators 1 by placing evaporimeter 1 makes it evaporation and produces steam, by steam passage 7 this steam is introduced absorber 2.
The outside that the present invention causes this circulation with generator second steam 21 is used and makes it to obtain condensation, and the form with condensed water turns back to evaporimeter 1 and absorber 2 afterwards.This is actually the outside that condenser is placed this circulatory system.Therefore, this circulation with respect to the second traditional class heat pump cycle adopted closed (closed circuit) circulation, be the circulation of a kind of heat pump open circuit.As shown in Figure 1, the absorbent solution of absorber 2 is sent into generator 3, utilize the generator 3 and the pressure differential of absorber 2 that the absorbent solution of generator 3 is introduced absorber 2 then, thereby constitute the circulation of absorbent solution by liquid-feeding pump 9.
The present invention also can be provided with steam jet pump 8 in said system, with steam pipework 16 high-pressure side of steam jet pump 8 inlet 14 is connected with the steam (vapor) outlet 12 of absorber 2, with steam pipework 17 low-pressure side of steam jet pump 8 inlet 15 is connected with the steam (vapor) outlet 13 of generator 3, first steam 20 and second steam, 21 interflow of the different parameters that the effect by steam jet pump 8 will be respectively obtains from absorber 2 and generator 3 are the 3rd steam 22 of same parameter, thereby the pressure of generator second steam 21 is got a promotion.
In order further to improve the pressure of absorber first steam 20 and generator second steam 21, second system of the present invention as shown in Figure 2, cooling partial crystallization device 10 and solid-liquid separator 11 are set between absorber 2 and generator 3, make the concentration reduction of the absorbent solution of introducing generator by the effect of cooling partial crystallization device 10 and solid-liquid separator 11.More particularly,, make solute supersaturation partial crystallization, after Separation of Solid and Liquid, parting liquid is sent into generator by absorber outlet absorbent solution is cooled off.According to the characteristic of absorbent solution VLE, the pressure of the low more saturated vapor of concentration of absorbent solution is just high more under the certain condition of temperature.Because the part solute in the absorbent solution is at cooling partial crystallization device 10 partial crystallizations, the solute crystallization obtains separating at solid-liquid separator 10, thereby the concentration of absorbent solution has obtained reduction in the generator 3, and the pressure of generator second steam 21 also just increases.Simultaneously, will send into absorber 2, and make the solute crystallization in absorber 2, obtain dissolving in solute crystallization and generator exports absorbent solution that solid-liquid separator obtains.Characteristic according to the absorbent solution VLE, at the absorption steam pressure is that the high more absorption temperature of concentration of absorbent solution under the certain condition of evaporator pressure is just high more, because the concentration of absorbent solution is improved in the dissolving absorber 2 of solute crystallization, absorber 2 operating temperatures just increase, and the absorption heat of emitting with absorption process is that the pressure of absorber first steam 20 of thermal source also just increases.Second system of the present invention is characterised in that, by cooling partial crystallization device 10 and solid-liquid separator 11 are set, have reached the purpose that can set and optimize absorber 2 and generator 3 absorbent solution working concentrations respectively between absorber 2 and generator 3.That is to say, second system of the present invention can realize a kind of for the very useful process conditions of absorption heat pump circulation, be when absorber is worked under high absorbent solution concentration conditions, generator is worked under than the low absorbent solution concentration conditions of absorber absorbent solution concentration, and this to be the circulation of traditional absorption heat pump be difficult to accomplish.
The present invention is also without particular limitation to the kind of employing absorbent solution, can adopt LiBr solution, also can adopt LiBr, NaBr, KBr, MgBr
2Deng mixed solution.
The present invention can utilize the thermal source of low ebb electricity as generator 3.
Method of the present invention is to adopt evaporimeter, absorber and generator to form the absorption heat pump open-circuit system to transform; With the thermal source of 250-1300 ℃ of thermal source as generator 3, add the absorbent solution of heater 3 by the 3rd heat exchanger 6 that places generator 3, make it evaporation and produce second steam 21; Absorb the steam of flash-pot 1 and produce absorption heat in absorber 2 absorbent solutions,, make it evaporation and produce first steam 20 by placing second heat exchanger, 5 heating condensate waters of absorber 2; With the thermal source of 90-500 ℃ of middle-low temperature heat as evaporimeter 1, the condensed water of first heat exchanger, 4 heating fumigators 1 by placing evaporimeter 1 makes it evaporation and produces steam, by steam passage 7 this steam is introduced absorber 2.
The present invention also can be provided with steam jet pump 8 in system shown in Figure 1, with steam pipework 16 high-pressure side of steam jet pump 8 inlet 14 is connected with the steam (vapor) outlet 12 of absorber 2, with steam pipework 17 low-pressure side of steam jet pump 8 inlet 15 is connected with the steam (vapor) outlet 13 of generator 3, it is the 3rd steam 22 that first steam 20 and generator second steam 21 are collaborated in the effect by steam jet pump 8.
The present invention can also transform with system shown in Figure 2, cooling partial crystallization device 10 and solid-liquid separator 11 promptly are set between absorber 2 and generator 3, make the concentration reduction of the absorbent solution of introducing generator by the effect of cooling partial crystallization device 10 and solid-liquid separator 11.
According to principle of the present invention, the generator thermal source of each part heat also can be converted into steam with the middle-low temperature heat of a heat simultaneously except self can produce the steam of a heat.And then, the two parts of steam that produce can be the steam of same parameter in the effect interflow by steam jet pump, this steam can be directly used in steam turbine generating, also can be used as the heating thermal source of existing steam turbine condensed water, by reducing or saving the purpose that the turbine rate of air sucked in required reaches increases generated energy.And then institute of the present invention producing steam also can be incorporated the steam pipe system of factory into by the effect of second steam jet pump.In addition, institute of the present invention producing steam also can be used as the required water vapour of vapor reforming hydrogen production process of natural gas, coke-stove gas etc.
Another feature of the present invention is, by adjusting the capacity of absorption liquid, absorber and generator both can move synchronously continuously, can distinguish independent periodic running again, and these characteristics are very useful for the utilization of the middle-low temperature heat of steelmaking process intermittent discharge.
Effect of the present invention
The first, heat recovery efficiency height, the generator thermal source of each part calorific value and the middle-low temperature heat of a calorific value can produce the steam of 2 parts of calorific values;
The second, flow process is simple, and equipment manufacturing cost is low.This is owing to need not sub-cooled thermal source and system thereof, and device all moves under the pressure conditions of higher, need not to be provided with the noncondensable gas treatment system;
Three, absorber and generator both can move synchronously continuously, also can distinguish independent periodic running, very were suitable for the characteristics of steel manufacture process.
Four, can organicly incorporate the existing energy of enterprise and use system such as steam turbine generating set or steam pipe system etc., thereby reach the purpose of maximum energy-saving consumption reduction and economic benefit.
The specific embodiment
Embodiment 1
As shown in Figure 1, be the thermal source of generator 3 with about 500 ℃ flue gas, add the absorbent solution of heater 3 by the heat exchanger 6 that places generator 3, make it evaporation and produce about 200 ℃, the steam 21 of 0.2MPa, the concentration of absorbent solution raises in the synchronizer 3; The absorbent solution of generator 3 is introduced into absorber 2.Absorb the steam of flash-pot 1 and produce absorption heat in absorber 2 absorbent solutions,, make it evaporation and produce about 150 ℃ by heat exchanger 5 heating condensate waters that place absorber 2, the steam 20 of 0.5MPa, the concentration of absorbent solution reduces in the absorber 2 simultaneously.With about 250 ℃ low-temperature flue gas is the thermal source of evaporimeter 1, and the condensed water of first heat exchanger, 4 heating fumigators 1 by placing evaporimeter 1 makes it to evaporate and produce the about 90 ℃ steam of temperature, and by steam passage 7 this steam is introduced absorber 2.First steam 20 and second steam 21 that absorber 2 and generator 3 are produced are introduced steam jet pumps 8, obtain about 160 ℃, the 3rd steam 22 of 0.3MPa in the outlet of steam jet pump 8.The 3rd steam 22 can be incorporated steam pipe system into by another steam jet pump, also can introduce steam turbine system and do directly or indirectly generating.The absorbent solution that present embodiment adopted is lithium-bromide solution, and the lithium bromide mass percent of absorber 2 absorbent solutions is about 65%; The lithium bromide mass percent of generator 3 absorbent solutions is about 67%;
Embodiment 2
First system of the present invention has the simple advantage of flow process, but has the lower deficiency of institute's producing steam pressure.This is because absorber absorbent solution working concentration and generator absorbent solution working concentration are subjected to the result of mutual restriction.In order further to improve institute's producing steam pressure, second system of the present invention as shown in Figure 2, its flow process characteristics are to be provided with cooling partial crystallization device 10 and solid-liquid separator 11 between absorber 2 and generator 3.Present embodiment is the same with the foregoing description one, is the thermal source of evaporimeter 1 with about 250 ℃ low-temperature flue gas, and is the thermal source of generator 3 with about 500 ℃ flue gas.Produce about 90 ℃ steam at evaporimeter 1, this steam enters absorber 2 by steam passage 7; Absorb the steam of flash-pot 1 and produce absorption heat in absorber 2 absorbent solutions, by placing second heat exchanger, 5 heating condensate waters of absorber 2, make it evaporation and produce about 170 ℃, first steam 20 of 0.8MPa, the concentration of absorbent solution reduces in the absorber 2 simultaneously.The absorbent solution of drawing from absorber 2 is admitted to cooling partial crystallization device 10, cools off partial crystallization with about 8 ℃ cooling water as refrigerant, and after solid-liquid separator 11 carried out Separation of Solid and Liquid, the parting liquid that obtains was sent into generator 3 by liquid-feeding pump 11.Absorbent solution evaporation in the generator 3 produces about 200 ℃, second steam 21 of 0.3MPa, and the absorbent solution concentration in the synchronizer 3 raises; The solute crystallization that absorbent solution of being drawn by generator 3 and solid-liquid separator 11 obtain is admitted to absorber 2.And then, first steam 20 and second steam 21 are introduced steam jet pump 8, obtain about 180 ℃, the 3rd steam 22 of 0.5MPa in steam jet pump 8 outlets.The absorbent solution that present embodiment adopted is lithium-bromide solution, and the lithium bromide mass percent of absorber 2 absorbent solutions is about 70%; The lithium bromide mass percent of generator 3 absorbent solutions is about 60%.