SU1163122A1 - Method of controlling flow and temperature of cooling water in ship heat-exchange apparatus - Google Patents

Abstract

A METHOD FOR REGULATING COSTS AND COOLING WATER TEMPERATURE IN A SHIP HEAT EXCHANGER, which consists in changing the flow rate and temperature of the cooling water, which is passed through the flow pipe through the heat exchanger and the flow of the cooling water, which is placed in device, changing the flow rate of cooling water in the drain and recycle pipelines and mixing the recirculated water into the incoming seawater, which is different so that, in order to expand the range of operating conditions, increase the degree of automation and control efficiency when changing the flow rate and temperature of the cooling water, the costs between the pressure pipe and return pipelines at the entrance to the heat exchanger are distributed proportionally, and the costs are proportional to this distribution between the drain and the recirculation piping as the cooling water leaves the heat exchanger and at the same time mix water from the return pipe cathode in incoming; (L outboard water, while the flow of water through the discharge and discharge pipelines change unidirectionally, and the ratio of the velocity of water at the entrance to the heat exchanger and at the exit from it is kept in the range of 0.1-0.85. One from o to

Description

1 The invention relates to heat and power engineering and relates to the power installations of vessels of an unlimited navigation area, including when sailing in ice conditions, and can be used, in particular, to automatically control the condensation pressure in ship refrigeration units. A known method of controlling the flow and temperature of the cooling water in the ship's heat exchanger apparatus is that the change in the flow and temperature of the cooling water which is passed through the pressure pipe through the heat exchanger and in the return pipeline is carried out with a deviation from the set flow rate and temperature water in the heat exchanger, changing the flow rate of the cooling water in the drain and recycle pipelines and mixing the recirculated water into the incoming seawater 1. However, The actual method has limited control limits, since the flow rate of water passing through the heat exchanger is limited, on the one hand, by the flow rate corresponding to the maximum pump head, pump operation with a reduced flow rate when the head decreases (or its constant value, which is determined by pump characteristic - flow rate) leads to a slowdown in the growth of flow rate in the recirculation pipeline, whereas its acceleration is necessary, and on the other hand, flow rate corresponding to the minimum possible head pressure in the working area x Characteristics of the pump, which is determined by the pressure losses in the entire line. Limiting the limits of variation in the flow rate of water passing through a heat exchanger causes the limits on the variation in the flow rate of water through the recirculation pipe, and hence the quantity, to be reduced. incoming seawater, which limits the change in temperature of the water passing through the heat exchanger. In addition, the change in the flow rate in the ducts passing through the heat exchanger is carried out by changing the flow rate in the pipeline 222 overboard when the resistance of the pipeline changes, which determines the operation of the pump with a low efficiency, and therefore degrades the energy indicator, reduces the range of regulation and this reduces the effectiveness of the regulation in conditions of an unlimited navigation area. The purpose of the invention is to expand the range of operating conditions, increasing the degree of automation and efficiency of regulation when. change the flow and temperature of the cooling water. The goal is achieved by the method of controlling the flow and temperature of cooling water in the ship's heat exchanger apparatus, which consists in that the change in flow rate and temperature of the cooling water, which is passed through the pressure pipe through the heat exchanger and through the return pipeline, when the deviation from specified flow rate or temperature of the cooling water in the heat exchanger, changing the flow rate of the cooling water in the drain and recycle pipelines and mixing the recirculation water into supply water, the costs between the pressure and return pipes at the entrance to the heat exchanger are distributed proportionally, and the costs between the discharge and recirculation pipelines when the cooling water leaves the heat exchanger and simultaneously mix the water from the return pipe into the incoming outside water water, while the flow of water through the discharge and drain pipelines change unidirectionally, and the ratio of the velocity of water at the entrance to the heat exchanger and at the exit from it is kept in the range of 0.1-0.85. Proportional distribution of water flow between the discharge and return pipelines at the entrance to the heat exchange. the apparatus and between the outflow and recirculation piping at the outlet from it allows the pump to operate according to the specification characteristic with an optimum efficiency in the entire control range.

since the redistribution of costs does not change the resistance of the pipeline, which expands the operating conditions and efficiency of regulation.

The proportional distribution of water flow between the drain and recirculation piping allows the pump to operate on the specification characteristic. Due to the large inertia of regulation, when only the temperature of the water passing through the heat exchanger apparatus changes, a proportional distribution of water flow between the pressure and return pipelines is proposed. This will allow changing the flow rate of water through the heat exchanger, retaining the ability of the pump to operate on the specification characteristic with optimum efficiency, which leads to more efficient regulation by reducing its inertia.

The synchronous distribution of water between the pressure and return pipes and between the drain and recycle pipelines so that the flow rates of the pressure pipe and the drain pipe change unidirectionally, and the mixing of water from the return pipe, as well as mixing in from the recirculation pipe, allows the incoming outgoing water to change. the flow rate and the temperature of the water passing through the heat exchanger in the whole range of temperatures of the outboard water while changing the heat load on the heat exchanger This is because it is possible to control the flow of water through the heat exchanger in a wide range while simultaneously varying the flow rate of incoming seawater over wide limits, which extends the operating conditions.

A change in the flow rate of water in a pressure pipe that passes through a heat exchanger is not sufficient in terms of a change in the temperature of the seawater. To eliminate this and the operation of the pump on a non-specification characteristic, a change in the flow rate of water in the discharge pipe was introduced by proportionally distributing it between

pressure and return pipelines synchronously with the distribution of water between the drain and recirculation pipelines, respectively (i.e., an increase in the water flow in the pressure pipe corresponds to an increase in the water flow in the drain pipe. And, conversely, a decrease in the decrease) along with mixing it from the recycle pipe into the incoming seawater.

The ratio of the speeds of the distribution of water at the entrance to the heat exchanger and at the exit from it within the range of 0.1-0.85 ensures stable operation of the heat exchanger and the efficiency of regulation.

0 At a ratio greater than 0.85, the water flow through the heat exchanger is less than the minimum permissible one, at which a large change corresponds to small flow changes

5 temperature in the heat exchanger, which leads to unacceptable changes in the parameters of the controlled medium after the heat exchanger and the inefficiency of the regulation,

As in these conditions, the controlled parameter oscillates with a high frequency (self-oscillation). With a ratio of less than 0.1, the limits of change in water flow

5 through the heat exchange apparatus is less than the maximum allowable, at which the minimum achievable changes in water flow through the heat exchange apparatus correspond to changes

0 tempo {) atures of seawater or heat load on the heat exchanger. When this limit is exceeded, abrupt changes in the temperature of the seawater, discharge (or reception) of

5 heat loads cause the controlled parameter to oscillate with great frequency, i.e. self-oscillation, which causes inefficiency of regulation.

WITH

The degree of automation is increasing, since the latter is provided over the entire range of variation. The temperatures of the seawater and the heat load on the heat exchanger.

five

The drawing shows a diagram of an apparatus for carrying out the proposed method. The device contains a condensation pressure sensor 1 in a condenser 2 of a refrigeration unit, electrically connected to a converter 3, for example a pressure switch, which is connected to a control unit 4 connected to two actuators 5 of three-way mixing valves 6 located at the inlet and outlet of condenser 2. Pump 7 communicated with pressure pipeline 8 and return pipe 9, as well as with the discharge pipe 10 and recycling 11 pipelines. Return pipe 9 and circulation circuit 11 are connected to the seawater suction pipe 12. The method is implemented as follows. When the temperature of the cooling water supplied by the pump 7 changes AND / OR the heat load on the condenser 2 changes, the condensation pressure is changed in it, which is controlled by sensor 1. The pulse from sensor 1 converted in converter 3 switches on via control unit 4 drives 5 for moving three-way Mixing valves 6 with the help of which proportional redistribution of cooling water flow between the pressure pipe 8 takes place, through which the changed amount of water enters the condenser.2 , and return pipe 9, as well as between the drain 10 and the recycling pipe 11. The change in flow rate in the pressure 8 and the discharge 10 pipelines occurs unidirectionally. The water in the condenser 2 is heated through the recirculation pipe 1 to the suction pipe 12 of the pump 7 in a changed amount, which leads to a change in the temperature of the water passing through the condenser 2. The decrease in water flow in the pressure pipe 8 corresponds to an increase in its temperature ho compared with the outside temperature water. At low temperatures of seawater and minimal heat load on condenser 2, the heated water through the recirculation pipe 11 comes in a small amount, since the three-way mixing valve 6 at the inlet to condenser 2 reduces water consumption through it to a minimum, redistributing it to the return Tpy6onpOBoi 9 to the maximum. However, returning water mixed with recycled water to suction pipe 12 reduces the flow of seawater. The change in the amount of water entering the condenser 2 occurs until the temperature of the water in front of the condenser 2 reaches the nominal value at a given flow rate through the condenser 2 and the condensation pressure reaches the specified value. After that, sensor 1 removes the pulse from converter 3, which by means of control unit 4 turns off actuators 5, and valves 6 are stopped. The required ratio of water distribution speeds by valves 6 at the inlet to condenser 2 to its distribution at the outlet from it is determined by calculation and is carried out, for example, by different speeds of actuators 5 of valve 6. In terms of speeds of distribution of water flow at the entrance to condenser 2 and at the outlet of 0.85, the three-way mixing valve 6 at the inlet to the condenser 2 distributes cooling water more slowly than the output from Hefo by about 1.2 times, which provides large limits for the variation of water flow through the condensation Torus 2 and more gradual regulation, since the rate of change in the flow of seawater is small (the amount of incoming seawater is equal to the amount of drained water overboard). However, the change in the temperature of the outboard water to the minimum (O -) or i discharge of the heat load (for example, up to 50% of the nominal) determines the flow rate through the condenser 2 is greater than the minimum allowable, at which a small change in the flow rate corresponds to a large change in the temperature in the condenser. 2, which leads to unstable operation of the capacitor 2 and the inefficiency of the regulation. With the ratio of the rates of distribution of the water flow at the inlet to the condenser 2 and at the outlet of it equal to 0.1, the three-way mixing valve 6 at the entrance to the condenser 2 expands the cooling water 10 times slower than at the outlet from it, which ensures rapid change in seawater intake and change in condensation pressure. Wherein . the limits of variation in the flow rate of the water passing through the condenser 2 are reduced. However, the temperatur changes. Seawater or heat load on the condenser 2 does not result in this ratio of speeds to a full rise in the flow of seawater and a sharp increase in the condensation pressure, and the variation of the flow rate within the required limits is provided by the design of the valve 6 until a certain amount of cooling water through the condenser is reached given heat load and a certain water temperature. This minimizes the inertia of regulation while ensuring its effectiveness. Intermediate values of the ratio of the rates of distribution of water flow at the inlet to condenser 2 and at its outlet are determined by the required operating conditions for the smoothness and inertia of controlling the parameters of condenser 2 (condensation pressure). The discharge pipe 10 can drain water into an ice box (not shown ), which reduces the intake of seawater and improves the ice NIN condition, since warm water does not overflow. Thus, according to the proposed method, the flow rate and temperature of the cooling water through the heat exchanger is changed by redistributing the flow of cooling water at the inlet to the heat exchanger and at the outlet from it, so that the parameters of the ship heat exchangers can be adjusted under the conditions of temperature change. water and / or heat load on the heat exchanger in a wide range when the pump operates on the specification characteristics. This achieves the possibility of operating the power plant in an unlimited area of navigation of ships up to ice conditions, increasing its efficiency and degree of automation.

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Claims (1)

METHOD FOR REGULATING COOLING WATER CONSUMPTION AND TEMPERATURE IN A SHIP HEAT EXCHANGE UNIT, which consists in changing the flow rate and temperature of cooling water,. which is passed through the pressure pipe through the heat exchanger and through the return pipe, is carried out when • the flow rate or temperature of the cooling water in the heat exchanger deviates, changing the flow of cooling water in the discharge and recirculation pipelines and mixing recirculated water into the incoming seawater, characterized in that that, in order to expand the range of operating conditions, increase the degree of automation and regulation efficiency when changing the flow rate and temperature of the cooling boiling water, the cost between the pressure and return conduits at the inlet of the heat exchanger is distributed proportionally, and this distribution is proportional synchronously partitioned between charges and discharges of the recirculation conduits exit from the cooling water heat exchanger and simultaneously admixed with water from the WHO-5 VRÁTNA incoming _pipeline; sea water, while the water flow rate through the pressure and discharge pipelines is changed unidirectionally, and the ratio of the water velocities at the inlet to the heat exchanger and at the outlet from it is kept within 0.1-0.85. SU ... 1163122 1163