RU2143637C1 - Evaporation-waste recovery installation - Google Patents

Abstract

FIELD: boiler equipment, in which natural gas and liquid fuel are used as fuel. SUBSTANCE: installation comprises evaporating stage 14 in the direction of motion of combustion products with spraying device 17, connected to condensation stage 20 through a pipeline and made in the form of vertical heat-exchange elements 10 secured in the upper 16 and lower 6 tube plates; located at the top is steam superheater 15 connected through a pipeline to vacuum pump 13 creating conditions for water evaporation and boiling within a temperature range from 40 to 50 C, and flash steam cooler 12 installed past it, and it the bottom - steam generating vessel 9 which accommodates nozzles 10 spraying water fed through adjustable shut-off device 11, furnished with water level regulator 8, and condensate removed from condensate collector 4 by exhaust pump 24 operating under the action of condensate level regulator 22. The installation is also furnished with discharge line 2, having blow-off pump 5. EFFECT: use of low-grade heat, enhanced quality of flue gas cleaning of ash and harmful effluents. 1 dwg

Description

 The invention relates to boiler equipment in which natural gas and liquid fuel are used as fuel.

 Known evaporation installation (VN Golubtsov. Water treatment at thermal power plants. Ed. Energia, M.-L., 1966, Fig. 10-1, p. 349), including lines of primary and secondary steam, the condensate of which merges respectively from the heating section of the evaporator and condenser through the steam traps into the distillate collector, from which it is pumped out. A level regulator mounted on the feed line maintains a specific water level in the evaporator. The purge line removes insoluble components.

 Known heat recovery device (Russia, patent N 2006739, F 22 B 1/18, F 28 C 3/06, Bull. N 26, 01/30/94,) (prototype), containing a surface heat exchanger, a contact chamber and a condensation surface in the form of heat-exchange elements with a side wall adjacent to the bottom located under the last water collector. It is equipped with a water-spraying device, a filter nozzle with an irrigator inside, a screw, a circulation pipe with a pump and an ash outlet, moreover, the water-spraying device and the filter nozzle are sequentially placed along the gases in the contact chamber, the side walls of the water collector and heat exchange elements are inclined to the horizontal plane, the screw is placed in the bottom of the sump, and the latter is connected via the above-mentioned pipeline to the sprinkler of the filter nozzle and the water spray device, and the ash outlet pipe is connected to the bottom.

The combustion products entering at a temperature of approximately 150 ... 180 ^o C, are cooled in a convective stage to 110 ^o C. In the evaporation chamber, the exhaust gases pass through a water curtain created by the irrigation device. The fly ash is wetted and washed off into the pan. Purified, moistened and cooled to about 70 ... 80 ^o C the combustion products pass through the nozzles. In it there is an additional filtering of the exhaust gases from the ash component, which is periodically washed off by the washer. On the heat exchange elements of the condensation stage, water vapor is condensed from the vapor-gas mixture. The flue gases cooled to 20 ... 30 ^o C are removed into the chimney. They heat air in the condensation stage, and in convective water.

The heat transfer in the convection stage is determined by the value of the heat transfer coefficient on the gas side, which is significantly less than on the water side, which entails increased mass and size characteristics of the installation. From the water heated in this stage at temperatures above 70 ^o C scale-like salts begin to be deposited on the heat transfer walls. This causes a sharp decrease in the heat transfer coefficient, and over time leads to a decrease in the cross section for the passage of water.

These drawbacks are eliminated by the fact that the evaporation stage in the direction of the combustion products is represented by a spray device connected by a pipeline to the condensation stage, vertical heat exchange elements fixed in the upper and lower tube boards, and at the top there is a superheater connected by pipelines to a vacuum pump, creating conditions for evaporation and boiling water in the temperature range of 40.. .50 ^o C, and the vapor cooler installed behind it, and below the vaporization volume, in which nozzles are placed, spraying raw water supplied through an adjustable shut-off device equipped with a water level sensor, and condensate removed from the condensate collector by a pump that is operated by condensate level controller, as well as a discharge line with a purge pump.

 In FIG. 1 shows the evaporation and recycling plant, where 1, 3, 7, 23 - valves. 2 - discharge line, 4 - condensate collector, 5 - purge pump, 6, 16 - lower and upper tube plates, 8, 22 - water and condensate level controllers, 9 - steam volume, 10 - nozzles, 11 - adjustable locking device, 12 - vapor cooler, 13 - vacuum pump, 14, 20 - evaporation and condensation stages, 15 - superheater, 17 - spray device, 18 - vertical heat exchanger element, 19 - smoke exhauster, 21 - nozzles, 24 - evacuation pump, 25 - pipeline solution - neutralizers.

 Condensation stage 20 (internal device not indicated) for any specific size is calculated according to the methodology given in [L. 1]. It consists of horizontal finned tubes, inside which water flows.

 The evaporation stage 14 has a lower 6 and an upper 16 tube boards in which vertical heat exchange elements 18 are fixed. To increase the value of the heat transfer coefficient inside the tube (not shown), and on the outside, a longitudinal ribbing is made at the levels of the vaporization volume 9 and the superheater 15. Nozzles 10 are placed at the boundary between the superheater 15 and the vaporization volume 9. A constant water level is maintained using a water level controller 8, the effect of which is transmitted to an adjustable locking device 11. The corresponding heating surface areas are determined by thermal calculation. At the lower point of the evaporation stage 14, a discharge line 2 is inserted, on which a purge pump 5 and a valve 7 are installed.

 The spray device 17 (detail is not shown) consists of a manifold with nozzles. The flow of raw water should be such that it all evaporates on the outer surface of the vertical heat exchange elements 18 and merges minimally into the condensate collector 4.

 The nozzle is filled with Rashig rings with a layer of 100 mm.

 The condensate collector 4 has a condensate level regulator 22, a pipeline through which condensate is pumped by a pump 24 to the nozzles 10. At its lower point, a sludge discharge pipe is provided, which is equipped with a slide 3.

 As the vacuum pump 13 can be used different types of pumps. Its type is determined depending on the specific working conditions.

 The cooler vapor 12 is selected as a result of thermal calculation.

 Based on the aerodynamic calculation, the brand of smoke exhauster 19 is determined.

 Heat exchanging surfaces and enclosing structures are coated on the inside with protective coatings, which increases the life span.

The work of the proposed installation proceeds as follows. The spray device 17 moistens water on the gas side of the surface with a vertical heat exchanger of the elements 18 that make up the evaporation stage 14. When the exhaust gases pass with a temperature above 110 ^° C, it evaporates. Thus, heat transfer is sharply intensified and the heat transfer coefficient from the gas side is increased. At the same time, the percentage of water vapor in the flue gases increases. Once in nozzles 21, they are additionally moistened and at a temperature of 50 ... 60 ^o C enter the condensation stage 20. In it, the exhaust gases are cooled to 20 ... 30 ^o C and removed by a smoke exhauster 19 into the chimney. The water vapor that is part of the exhaust gases condenses on the heat exchange surfaces of the condensation stage 20 and drops in the form of droplets on the nozzles. Part of the condensate flows into the condensate collector 4. When the valve 3 is opened, sludge can be periodically removed. If the condensate level rises, the condensate level controller 22 is activated, which helps to open the valve 23 and turn on the exhaust pump 24. Lowering the condensate level to a certain point by the same regulator brings them to their original position. Condensate is supplied to the nozzles 10. To them, but only through the adjustable shut-off device 11, raw water enters from the condensation stage 20. The required water level in the evaporation stage 14 is maintained by the action of the water level regulator 8 on the adjustable shut-off device 11. The sprayed raw water and condensate evaporate on the heat exchange surface of the vertical heat exchange elements 18 and boil at a temperature of 40 ... 50 ^o C. The resulting steam is overheated in the superheater 15 and is removed by a vacuum pump 13 in the vapor cooler 12, where it condenses.

 Due to the distillate leaving the evaporator cooler 12, an increase in the concentration of dissolved salts occurs in the water space of the vaporization volume 9, which decreases due to periodic purging along the discharge line 2 when the pump 5 is turned on and the valve 7 is opened. The condensate in the condensate collector 4 has a pH approximately equal to 5.5. Its entry into the evaporator 14 thereby eliminates the discharge of acidic effluents into the sewer. Periodic removal of a small amount of sludge from the condensate collector 4 will not lead to excess acid emissions.

 The neutralizing solution supplied through the pipeline 25 is determined depending on the specific salinity of the raw water and the pH of the condensate from the condensate collector 4. It creates a neutral or slightly alkaline environment.

 The purge water from the evaporation stage 14 together with the sludge from the condensate collector 4 (depending on their chemical properties) is brought to normalized requirements before entering the sewer.

The proposed evaporation and recycling plant has the following advantages:
1. The low-grade heat of the exhaust gases is used, which increases the efficiency of the installation by 10-15%.

 2. The introduction of irrigation of the heat exchange surface of the evaporation stage from the side of the combustion products increased the heat transfer coefficient by approximately an order of magnitude (as compared to convective heat transfer), which reduces the overall dimensions by the same amount.

3. The implementation of the boiling process at a temperature of 40 ... 50 ^o C is not accompanied by the deposition of salts on the walls of the heat exchange elements of the evaporation stage.

 4. The installation of a superheater and spray nozzles between it and the vaporization volume helps to flush the steam from the salt-containing droplets of moisture carried away with it.

5. Together with a reduction in the content of CO, SO ₂ , SO ₃ , and NO ₂ in the exhaust gases, the discharge of acid effluents into the environment is eliminated.

Claims (1)

Evaporative-utilization installation, including a smoke exhaust, condensation stage, located above the nozzle and condensate collector, characterized in that the evaporation stage in the direction of the combustion products is represented by a spray device connected by a pipeline to the condensation stage, vertical heat-exchange elements fixed in the upper and lower tube boards with a superheater located at the top, connected by pipelines to a vacuum pump, creating conditions for evaporation and boiling during s in the range of 50 - 40 ^o C, and the established for him coolant vapor, and bottom - vapor generating volume in which are arranged nozzles, atomized raw water supplied through the adjustable locking device provided with a water level sensor, the condensate being removed from the pump condensate collection pump operating under the influence of a condensate level controller and a solution-neutralizer, as well as a discharge line with a purge pump.