CN211086167U - Dirt thermal resistance testing system for double-pipe heat exchanger - Google Patents

Abstract

The utility model discloses a fouling thermal resistance test system of a sleeve-type heat exchanger, which comprises a sleeve-type heat exchanger (1), and the sleeve-type heat exchanger (1) is inserted with electric circuits arranged along the length direction of the sleeve-type heat exchanger (1). The heating rod (2), the inlet of the casing heat exchanger (1) passes through the test water pipe (5) with the flow meter group (3) and the feed pump (4) and the solution tank ( 6) connected to each other; a plurality of thermocouples (7) for measuring temperature are distributed on the casing heat exchanger (1), and the temperature measured by the thermocouple (7) in real time is collected by the data collector (8), The data collector (8) is connected with the computer (9) through a line. The testing system of the utility model utilizes the prepared aqueous solution containing scaling substances to form scale on the outer wall surface of the inner tube of the casing-type heat exchanger, and can measure the wall after the deposition of the two-phase flow with the scale concentration range of 200-1300 mg/L. Mild water temperature, to achieve the purpose of monitoring the thermal resistance value of dirt.

Description

A test system for fouling thermal resistance of casing-type heat exchangers

technical field

The utility model belongs to the field of industrial scale treatment and monitoring, in particular to a fouling thermal resistance test system of a casing type heat exchanger, which can measure the thickness of the scale by monitoring the surface temperature of the pipe wall.

Background technique

In today's industrial production, heat exchange equipment and boilers are widely used. Due to the lack of technology and management, accidents related to heat exchange equipment and boilers are not uncommon. Once an explosion occurs, it will destroy equipment and buildings, cause personal casualties, and the damage is very staggering. Dirt is a poor conductor of heat, and its thermal conductivity is generally only a tenth of that of carbon steel. Compared with good conductors of heat such as copper, the difference is even greater. This is likely to cause local heat accumulation in the fouling part of the heat exchange equipment or boiler, resulting in uneven temperature of the heat exchange surface of the heat exchange equipment or the boiler body and the interior of the boiler, resulting in material failure, strength reduction, and ultimately an explosion accident. Moreover, the scaling will block the pipeline and cause leakage accidents. If the leakage material is inflammable and explosive, it will also lead to the occurrence of combustion and explosion accidents.

Utility model content

The purpose of the utility model is to solve the problems existing in the prior art, and to provide a casing heat exchanger fouling thermal resistance test system which can measure the fouling thickness by monitoring the surface temperature of the pipe wall.

The purpose of this utility model is to be solved by the following technical solutions:

A fouling thermal resistance test system for a sleeve-type heat exchanger, comprising a sleeve-type heat exchanger, characterized in that: the sleeve-type heat exchanger is inserted with electric heating rods arranged along its length direction, and the sleeve-type heat exchanger is inserted into the sleeve-type heat exchanger. The inlet of the type heat exchanger is connected with a solution tank that provides an aqueous solution containing scaling substances through a test water pipe with a flow meter group and a feed pump; the described casing type heat exchanger is distributed with a plurality of thermoelectric devices for measuring temperature. The temperature measured by the thermocouple in real time is collected by the data collector, and the data collector is connected with the computer through the line.

The outer tube of the casing heat exchanger is a glass tube, the inner tube is a stainless steel tube, and the electric heating rod is located in the stainless steel tube.

The thermocouples are uniformly arranged along the length direction of the sleeve-type heat exchanger, and both the inlet and the outlet of the sleeve-type heat exchanger are provided with thermocouples.

The electric heating rod is connected with a contact voltage regulator, and the power and heating temperature of the electric heating rod are adjusted by adjusting the voltage input to the electric heating rod through the contact voltage regulator.

The feed water pump is located on the front side of the flow meter group, which is a combination of glass rotor flow meters with different ranges and can control the flow.

The solution tank is provided with a stirrer, and the outlet of the solution tank is connected with the feed water pump through a test water pipe with a valve.

The inlet of the solution tank is connected with the pure water generating equipment through the pipeline with the valve, the pure water generating equipment is connected with the raw water tank through the pipeline with the valve, and the raw water tank is connected with the raw water pump through the pipeline with the valve.

A pure water tank is arranged between the solution tank and the pure water generating equipment, the inlet of the pure water tank is connected with the pure water generating equipment through a pipeline with a valve, and the outlet of the pure water tank is connected with a feed pump through a pipeline with a valve .

Compared with the prior art, the utility model has the following advantages:

The test system of the utility model utilizes the prepared aqueous solution containing fouling substances to pass through the casing type heat exchanger to form scale on the outer wall of the inner tube, and the test system can measure the two-phase flow deposition with the scale concentration range of 200-1300mg/L Based on the basic principle of heat transfer, it can measure the total heat transfer coefficient of Reynolds number in the state of 200-16000, and then monitor the total heat transfer coefficient and fouling in the operating state. The thermal resistance can also be measured online to measure the relationship between the thermal resistance of the fouling and the time, and the characteristics of the thermal resistance of the fouling with time can be obtained.

Description of drawings

Accompanying drawing 1 is the principle schematic diagram of the fouling thermal resistance test system of the casing type heat exchanger of the present invention;

FIG. 2 is a diagram showing the structure and temperature measurement point distribution of the casing-type heat exchanger for testing of the present invention.

Among them: 1—casing heat exchanger; 2—electric heating rod; 3—flow meter group; 4—feed water pump; 5—test water pipe; 6—solution tank; 7—thermocouple; 8—data collector; 9 - computer; 10 - pressure regulator; 11 - glass tube; 12 - stainless steel tube; 13 - agitator; 14 - pure water tank; 15 - pure water generation equipment; 16 - raw water tank; 17 - raw water pump.

Detailed ways

The utility model will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1: A casing heat exchanger fouling thermal resistance test system, including a casing heat exchanger 1, the casing heat exchanger 1 is inserted with electric heating rods 2 arranged along its length direction. , the inlet of the casing heat exchanger 1 is connected to the solution tank 6 that provides the aqueous solution containing the scaling substances through the test water pipe 5 with the flow meter group 3 and the feed water pump 4, and the feed water pump 4 is located in the front of the flow meter group 3. On the other hand, the flowmeter group 3 is a combination of glass rotor flowmeters with different ranges and can control the flow; a plurality of thermocouples 7 for measuring temperature are distributed on the casing heat exchanger 1, and the temperature measured by the thermocouples 7 in real time is determined by The data collector 8 collects, and the data collector 8 is connected with the computer 9 through a line.

As shown in Figure 1-2: the outer tube of the casing heat exchanger 1 used in this test system is a glass tube 11, the inner tube is a stainless steel tube 12, and the electric heating rod 2 is located in the stainless steel tube 12; A contact voltage regulator 10 is connected, and the voltage of the input electric heating rod 2 is adjusted through the contact voltage regulator 10 to adjust the power and heating temperature of the electric heating rod 2; the thermocouple 7 is along the length of the sleeve heat exchanger 1 The directions are uniformly arranged, and thermocouples 7 are arranged at the inlet and outlet of the casing heat exchanger 1 .

There is a stirrer 13 in the solution tank 6, and the outlet of the solution tank 6 is connected to the feed water pump 4 through a test water pipe 5 with a valve, and the inlet of the solution tank 6 is connected to the pure water generation device 15 through a pipeline with a valve. Connection, the pure water generating device 15 is connected to the raw water tank 16 through a pipeline with a valve, and the raw water tank 16 is connected to the raw water pump 17 through a pipeline with a valve. On this basis, a pure water tank 14 is provided between the solution tank 6 and the pure water generating equipment 15, the inlet of the pure water tank 14 is connected with the pure water generating equipment 15 through a pipeline with a valve, and the outlet of the pure water tank 14 is connected with the pure water generating equipment 15 through a belt The pipeline with the valve is connected to the feed pump 4 .

When the fouling thermal resistance test system of the casing type heat exchanger of the utility model is used, its specific process is as follows:

(1) Use the raw water pump 17 to provide the necessary working pressure for each equipment, and determine the working pressure of the raw water pump 17 according to the design pressure drop of each equipment in the pretreatment (the maximum pressure of each equipment cannot be less than 0.5MPa); Quartz filter and activated carbon filter to remove very fine particles in the raw water, some organic matter and residual chlorine in the water;

(2) Fill the pure water tank 14 and the solution tank 6 with the prepared pure water with an electrical conductivity of less than 3.00 μS/cm, add the required calcium carbonate to the solution tank 6 of the configuration solution, and stir for more than 30 minutes for standby use. Use agitator 13 to keep stirring until the finishing stage;

(3) Turn on the feed water pump 4, drive the pure water into the casing heat exchanger 1 for testing, adjust the flow meter 5 to the required flow, and stabilize for more than 10 minutes;

(4) According to the length of the casing heat exchanger 1, multiple temperature measurement points are evenly selected for measurement, as shown in Figure 2: A total of four temperature measurement points A, B, C, and C are set to measure the temperature of the outer wall of the inner tube. For temperature, if K-type thermocouple 7 is used, use an electric drill to open four small holes in the silica gel plug at the end of the glass tube 11, pass the data wire of thermocouple 7 through the small holes on the silica gel plug, and use a throat for the probe of thermocouple 7. The hoop is fixed on the outer wall of the stainless steel tube 12, and the other end of the data line of the thermocouple 7 is connected to the data acquisition card in the data acquisition device 8 through the terminal block to test the accuracy of the thermocouple 7; There are six temperature measurement points in total; connect the thermocouple 7, set the data collector 8 and open the recording software to start recording data; turn on the electric heating rod 2 and adjust the output voltage to 85V;

(5) When the temperature difference at the temperature measurement point is stable within the range of 5°C (about 1h is required), close the pure water input channel and open the outlet of the solution box 6 containing the calcium carbonate solution at the same time, and inject the solution into the test chamber. In the casing heat exchanger 1, the formal test is started.

(6) When the temperature of the temperature measurement point no longer changes significantly, enter the final stage; stop recording and save the data, turn off the power of the electric heating rod 2, switch the pure water into the casing heat exchanger 1, flush the casing After the electric heating rod 2 is cooled to room temperature, turn off the feed water pump 4, disassemble the casing heat exchanger 1 and wash it with pure water, and replace it with a new stainless steel Tube 12, after assembly, wait for the next set of tests.

The local fouling thermal resistance can be easily determined using the data measured with the indirectly electrically heated casing heat exchanger 1, because the surface heat flow of the concentric heating core can be easily calculated from the input power and the diameter and length of the heating section, and because the fouling experiment The experimental fluid velocity, average temperature, and heat flow through the annular channel were maintained constant. At this time, if the influence of the thickness and roughness of the fouling deposit layer on the flow and heat transfer is assumed to be negligible, the heat transfer coefficient is basically kept constant, and the interface temperature T _s of the fluid deposit layer is also kept constant. Then in this case, the fouling thermal resistance is calculated by:

Among them, R _f is the thermal resistance of fouling deposition, the unit is m ² ·K/W; Tw is the temperature of the outer wall of the inner tube, _{Twc is the temperature of the outer wall of the inner tube in a clean state, Twf is} the temperature of the outer wall of the inner tube in a polluted state, The unit is K; T _s is the interface temperature of the fluid deposition layer, the unit is K; Q is the heat transfer rate of the heat exchanger, the unit is W; A is the heat transfer area, the unit is m ² .

Based on the obtained fouling thermal resistance curve, an accurate fouling prediction model can be obtained that fits the test system:

Among them, Re is the flow Reynolds number, C _b is the average concentration of fouling substances, the unit is kg/m ³ ; θ is the time, the unit is h or s.

The above embodiments are only to illustrate the technical idea of the present utility model, and cannot limit the protection scope of the present utility model. Any changes made on the basis of the technical solution according to the technical idea of the present utility model shall fall into the scope of the present utility model. It is within the scope of protection of the new model; the technology not involved in the present invention can be realized by the existing technology.

Claims (8)

1. A double pipe heat exchanger fouling resistance test system comprises a double pipe heat exchanger (1), and is characterized in that: an electric heating rod (2) arranged along the length direction of the double-pipe heat exchanger (1) is inserted in the double-pipe heat exchanger (1), and the inlet of the double-pipe heat exchanger (1) is connected with a solution tank (6) for providing aqueous solution containing scale substances through a test water pipe (5) with a flowmeter group (3) and a feed water pump (4); a plurality of thermocouples (7) for measuring temperature are distributed on the sleeve-type heat exchanger (1), the temperature measured by the thermocouples (7) in real time is collected by a data collector (8), and the data collector (8) is connected with a computer (9) through a circuit.

2. The dirtiness resistance test system of double pipe heat exchanger according to claim 1, wherein: the outer pipe of the double-pipe heat exchanger (1) is a glass pipe (11), the inner pipe of the double-pipe heat exchanger is a stainless steel pipe (12), and the electric heating rod (2) is positioned in the stainless steel pipe (12).

3. The fouling resistance test system of double pipe heat exchanger according to claim 1 or 2, characterized in that: the thermocouples (7) are uniformly arranged along the length direction of the double-pipe heat exchanger (1), and the thermocouples (7) are arranged at the inlet and the outlet of the double-pipe heat exchanger (1).

4. The dirtiness resistance test system of double pipe heat exchanger according to claim 1, wherein: the electric heating rod (2) is connected with a contact voltage regulator (10), and the power and the heating temperature of the electric heating rod (2) are adjusted by adjusting the voltage input into the electric heating rod (2) through the contact voltage regulator (10).

5. The dirtiness resistance test system of double pipe heat exchanger according to claim 1, wherein: the water feeding pump (4) is positioned on the front side of the flow meter group (3), and the flow meter group (3) is a combination of glass rotameters with different measuring ranges and can control the flow.

6. The dirtiness resistance test system of the double pipe heat exchanger according to claim 1 or 5, wherein: the stirrer (13) is arranged in the solution tank (6), and the outlet of the solution tank (6) is connected with the water feeding pump (4) through a testing water pipe (5) with a valve.

7. The dirtiness resistance test system of double pipe heat exchanger according to claim 6, wherein: the inlet of the solution tank (6) is connected with a purified water generating device (15) through a pipeline with a valve, the purified water generating device (15) is connected with a raw water tank (16) through a pipeline with a valve, and the raw water tank (16) is connected with a raw water pump (17) through a pipeline with a valve.

8. The dirtiness resistance test system of double pipe heat exchanger according to claim 7, wherein: a purified water tank (14) is arranged between the solution tank (6) and the purified water generating equipment (15), the inlet of the purified water tank (14) is connected with the purified water generating equipment (15) through a pipeline with a valve, and the outlet of the purified water tank (14) is connected with the water feeding pump (4) through a pipeline with a valve.

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