RU2013686C1 - Heat accumulator - Google Patents

Abstract

FIELD: heat power engineering. SUBSTANCE: heat accumulator has housing 1 with chamber 2 for liquid heat-transfer agent, vapor chamber 5 bounded with cover 6 and condensate chamber 7. Intake compartment 3 is located in the upper portion of the housing above cover and is brought in communication with vapor chamber 3 by means of bypass branch pipe 12 combined with hydraulic seal whose lower portion is located in chamber 2. In the course of operation, intake compartment 3 is used as expansion tank. EFFECT: enhanced efficiency. 3 cl, 1 dwg

Description

 The invention relates to a power system, in particular to steam and heat supply of agricultural production from a steam boiler.

 Known hot water tank with a tubular heat exchanger connected to the main water heating system, equipped with three water chambers, which serves for heating and hot water supply and cannot be used to produce secondary steam from superheated water [1].

 Also known is a battery of heated water of a variable level, heated by saturated steam and allowing steam supply with secondary steam from the volume of superheated water [2]. However, it excludes the separation of steam condensate from the liquid coolant of the heating circuit and make-up water.

 As a prototype, a heat accumulator was selected, which is heated by steam, for example, from a steam electric boiler with the exception of mixing the resulting condensate with water from the heating circuit and with make-up if it is possible to obtain secondary steam from the liquid coolant chamber from boiling overheated water of the heating circuit [3]. In these circumstances, the electric boiler (steam source) is supplied with its own condensate of heating steam, which is condensed by pumping through the pipes of the heat exchanger immersed in the condensate chamber of the cooled return water from the heat supply line, which guarantees a non-scale operation of the steam boiler.

 However, the presence of an integrated tubular heat exchanger greatly complicates the operation and increases the cost of the heat accumulator. Heat losses through the walls of the battery housing, in particular through the walls of the steam chamber, including its cover, reduce the useful steam productivity of the battery in the process of steam supply. In addition, replenishment according to the prototype scheme to compensate for condensate losses from the boiler circuit with purging and evaporation is carried out by the technical water of the heating line.

 The aim of the invention is to reduce capital costs and increase the operational reliability of the heat accumulator.

 This is achieved by the fact that the receiving compartment of the heat accumulator connected to the return line of the heating network is installed in the upper part of the housing on the lid of the steam chamber, moreover, it is integral with the battery housing and is connected to the steam chamber by a bypass pipe. In addition, the bypass pipe itself is combined with a Y-shaped water lock that connects the steam chamber with a receiving compartment in communication with the atmosphere to avoid exceeding the design pressure in the steam boiler and battery circuit.

According to the proposed design scheme of the heat accumulator, cooled return water with a temperature of 40-65 ^о С is supplied from the heat supply line under the pressure of the mains pump to the receiving compartment of the liquid coolant chamber mounted on the convex inside the lid of the steam chamber, the saturated steam in which has a temperature of 110-115 ^о C at the end of the "charge" to 85-100 ^o C after the "discharge" of the battery. Under these conditions, condensation of saturated steam is inevitable on the inner wall of the lid of the steam chamber, the curvature of which is characterized by convexity outside. The resulting condensate will drain along the wall of the lid and collect in the peripheral condensate chamber, made in the form of a shell, mounted coaxially to the housing in its upper part, equipped with an annular bottom with its central and peripheral sections adjoining the shell and the housing wall, respectively. The heat flux of steam condensation will be transmitted through the wall of the lid of the steam chamber to the water from the return line of the heating network in the receiving compartment, located on the lid of the steam chamber and made integral with the battery case. The upper location of the receiving compartment allows you to combine the bypass pipe with a water seal, and the receiving compartment, in communication with the atmosphere, can be used as an expansion tank.

 The drawing shows a General structural diagram of the proposed heat accumulator.

 The heat accumulator comprises a vertical cylindrical body 1, a liquid heat carrier chamber 2 with a receiving compartment 3 connected to the return line of the heating network 4, a steam chamber 5 limited by a lid 6 convex inwardly, and a condensate chamber 7 made in the form of a shell 8 mounted coaxially to the housing 1 in its upper part, equipped with an annular bottom 9 adjacent to its central 10 and peripheral 11 sections, respectively, to the shell 8 and the wall of the housing 1, and the bypass pipe 12, made in the form of a Y-shaped valve, connecting the steam chamber 5 with a receiving compartment 3 connected to the atmosphere through the valve 13. The heating steam was supplied to the liquid coolant compartment 2 via the steam line 14, and the condensate was removed from the condensate chamber 7 through the condensate line 15. The battery is connected to the heating system by a supply line 16, with drainage system - drain 17 and drain pipe 18.

 The heat accumulator operates as follows.

After 19 phase process of steam supply chamber 5 through the steam line 19 steam supply process temperature of saturated steam and water heat transfer fluid in the chamber 2 decreases to 100-102 ^{° C,} which corresponds to the state of "discharging" the heat accumulator to steam supply phase. At this time, the water in the receiving compartment 3 from the return line of the heating network 4 is warmed up to a maximum temperature and the heat flux through the cover 6 of the steam chamber 5 is minimal. However, as the removal of heat to the heating system via line 16 to the receiving compartment via line 4 to return cooled liquid coolant temperature 40-65 ^{° C} when the temperature of feed water 100 to 75-80 ° ^C. At this stage, the heat accumulator for heating the discharge the system the temperature head between the steam chamber 5 and the receiving compartment 3 causes a heat flux with condensation of the secondary steam on the wall of the cover 6 of the steam chamber 5. Due to the convex outside the shape of the cover 6, the resulting condensate will drain into the condensate chamber 7 made on the periphery of the liquid coolant chamber 2 in the upper part of it in the form of a shell 8, mounted coaxially to the vertical housing 1, provided with an annular bottom 9 with a tight fit with its central 10 and peripheral 11 sections, respectively, to the shell 8 and the wall of the housing 1 with the exception of mixing the contents in chambers of liquid heat carrier 2 and condensate 7.

Condensate collected in the chamber 7 through the condensate line 15 can feed the steam source, and the heating steam through the steam line 14 will go under the water level in the liquid coolant chamber 2. The heating steam bubbles will condense during bubbling, heating the water and “charging” the battery to the maximum water temperature 110-112 ^о С in the liquid heat carrier chamber 2 and the maximum saturated vapor pressure in the steam chamber 5 is about 0.15 MPa (taking into account the pressure of the hydrostatic column of water in the battery). When the pressure of the heating steam in the chamber 5 is higher than the maximum calculated column of water from the connecting channel 12, made in the form of a Y-shaped hydraulic lock, will be released into the receiving compartment 3 and the excess pressure in the steam chamber 5 along with the steam flow through the hydraulic lock 12 will be released into the receiving compartment 3, and from it - through the atmospheric valve 13 through the atmosphere. By lowering the pressure in the steam chamber at 5 "detente" akkumutora water column in the water seal 12 of the outer knee will be forced into the inner pipe it, maintaining integrity of the system prior to dilution values of about 0.05 MPa, which corresponds to the temperature of saturated steam in the steam chamber 80 ^of C, "discharge" the battery below this temperature is impractical. To do this, it is necessary to again ensure the supply of heating steam through the steam line 14, raise the temperature of water and steam to the maximum design values, after which the cycle repeats.

The technical and economic parameters of the proposed heat accumulator and prototype are such that for a steam electrode boiler of 500 kW working in the charging mode for 8 hours at night during the period of failure of the electric load, 2 battery tanks of 25 m ^{3 of} useful capacity with dimensions of about 5 m in height and 2.8 are needed m in diameter. For a given diameter of the cover 5 of the steam chamber 6, the effective condensate collection surface will be F _k = 5 m ² .

, где W_эк - мощность электрического парового котла, кВт;
η_эк - КПД электрического котла по производству пара;
D - диаметр корпуса аккумулятора, соответствующий расчетному диаметру крышки паровой камеры и площади конденсации пара, м²;
α_к - коэффициент теплоотдачи конвекций в большом объеме приемного отсека с внешней стороны крышки паровой камеры, в первом приближении соответствующий коэффициенту теплопередачи через эту теплообменную стенку, кВт (м²˙K);

- среднелогарифмический (во времени в течение суток) температурный напор между паровой камерой и приемным отсеком, К.The condensation of steam and its collection in the condensate chamber within 24 hours should compensate for the loss of condensate in the steam boiler circuit, equal to its capacity for 8 hours of night work when mixing the heating steam in the liquid heat carrier chamber with water from the heating circuit. The balance of steam production and steam condensation corresponds to the following balance of the heat of vaporization and the heat of condensation, which can be expressed by the formula
8W _ek η _ek = 24 · 2

where W _ek - power of the electric steam boiler, kW;
η _ek - the efficiency of the electric boiler for steam production;
D is the diameter of the battery housing, corresponding to the estimated diameter of the lid of the steam chamber and the area of vapor condensation, m ² ;
α _k is the heat transfer coefficient of convection in a large volume of the receiving compartment from the outside of the steam chamber lid, to a first approximation, corresponding to the heat transfer coefficient through this heat-exchange wall, kW (m ² ˙ K);

- average logarithmic (in time during the day) temperature head between the steam chamber and the receiving compartment, K.

Среднелогарифмический температурный напор составит

=

=

= 30^°C где Т_пк, Т_об - температура в паровой камере и температура обратной воды системы; Т^{макс, мин} - индексы максимального и минимального значений температур, ^оС.From the last expression we obtain the formula for estimating the required estimated value of the diameter of the battery case
D =

The average log temperature head will be

=

=

= 30 ^° C where T _pc , T _about - the temperature in the steam chamber and the temperature of the return water of the system; T ^{max, min} - the indices of the maximum and minimum temperatures, ^about C.

= 2,8 м♂♂♂
Величина расчетного среднелогарифмического напора может быть еще увеличена путем установки в приемном отсеке аккумулятора змеевика 20 системы горячего водоснабжения и подпитки. Таким образом, поставленная цель в рассматриваемом численном примере легко может быть достигнута, т. е. отказ от рекуперативного теплообменника, встроенного согласно конструктивной схеме прототипа в камеру конденсата, не уменьшит количество конденсата в контуре парового электрокотла, позводит отказаться от подпитки котлового контура водяным теплоносителем теплосети, что приведет к сокращению тепловых потерь в окружающую среду, упростит эксплуатацию, профилактические осмотры и ремонты, удешевит конструкцию теплового аккумулятора.The heat transfer coefficient of convection in a large volume is pressed upward by a convex surface according to empirical data is 150-200 W / (m ² ˙K). However, in this case, this value can be no less than 2 times increased due to the injection of return water with jets onto the heat exchange surface under the pressure of the heating system network pump. Thus, taking into account the high values of the heat transfer coefficient on the condensation side (of the order of 5000-10000 W / (m ² ˙K), we can assume that K = α≥ 400 Kt / (m ² ˙K). Then the calculated value of the diameter of the battery case and steam cover cameras will be according to the above formula
D

= 2.8 m♂♂♂
The value of the calculated average logarithmic pressure can be further increased by installing a coil 20 of the hot water supply and recharge system in the receiving compartment of the battery. Thus, the goal in the considered numerical example can be easily achieved, i.e., the rejection of a recuperative heat exchanger integrated in the condensate chamber according to the design scheme of the prototype will not reduce the amount of condensate in the steam electric boiler circuit, and will make it unnecessary to refuel the boiler circuit with a water heating medium , which will lead to a reduction in heat losses to the environment, simplify operation, routine inspections and repairs, and reduce the cost of the design of the heat accumulator.

 When calculating in a working draft, the mass and design of the original version of the case will practically not change and become more complicated. But at the same time, a structurally complex and metal-intensive tubular heat exchanger is eliminated, the design of heating steam supply pipelines is simplified, and the expansion tank is eliminated. This provides a reduction in capital costs and improved performance of the heat accumulator.

Claims (3)

 1. HEAT BATTERY, comprising a cylindrical body with a chamber for the liquid coolant located therein, a receiving compartment communicated with the return line of the heating network and a steam chamber limited by a convex lid, and a water seal, characterized in that, in order to increase its operational reliability and reduce capital cost, the receiving compartment is located in the upper part of the housing above the convex cover and is in communication with the steam chamber through an additionally installed bypass pipe.  2. The battery under item 1, characterized in that the bypass pipe is combined with a water seal and placed its lower part in the chamber of the liquid coolant.  3. The battery according to paragraphs. 1 and 2, characterized in that the receiving compartment is communicated through an additionally installed air valve with the atmosphere.