Sewage sampler

Abstract

The invention relates to technology and equipment for taking liquid samples from a sewage system. A sewage sampler comprises a hermetically sealed housing, a radio-frequency transceiver, a microcontroller, a power control unit for a motor, a motor, a peristaltic pump, a filter, a tank, a capacitive tank fill-level sensor, a power supply unit, a check valve, a reed switch sensor, two galvanic isolators, a sample collection hose, and a tank fill-level control hose.

Description

[0001] GOIN 1 / 10

[0002] Sewer sampler

[0003] Field of technology

[0004] The invention relates to the technology and technique for collecting liquid samples from sewerage.

[0005] State of the art

[0006] A device for sampling liquid products from a reservoir is known (RU patent 2431126, published 10.10.2011), containing a reservoir, a tank, a drain valve, vertical pipes, and a pump.

[0007] The disadvantage of the known device is the impossibility of automating the sampling process.

[0008] A device for collecting liquid samples is also known, comprising a container, intermediate measuring containers with tubes installed therein, a drive, a valve switch, and other interconnected elements (RU Patent 2334209, published September 20, 2008). A disadvantage of this known device is its complex design.

[0009] Disclosure of the essence of the invention

[0010] The operating principle of any liquid sampling device (sampler) is to draw liquid into a container through a hose using a pump. A wide range of devices of this type are available, but they are not suitable for use in sewer manholes. Sewer channels and manholes are difficult to access. Furthermore, harmful and toxic substances (such as methane, hydrogen sulfide, etc.) accumulate in manholes and channels as a result of the natural decomposition of organic matter. Furthermore, other toxic and harmful substances (formaldehyde, ammonia, xylene, etc.) are discharged. This sometimes makes human presence impossible (or greatly hampers). Moreover, the greatest interest lies in collecting a sample precisely when a harmful substance stain is passing. Therefore, a sewer sampler should completely replace (or eliminate) human intervention, providing only the ability to remotely command the sample to be collected at the required time.

[0011] Such a sampler must remain in the sewer manhole for an extended period of time, ready to collect a sample. Therefore, a sewer sampler must meet at least the following requirements:

[0012] (i) the sampler must be small enough to fit into the sewer manhole;

[0013] (ii) since the sewer sampler is used in an aggressive chemical environment, it must have a sealed housing;

[0014] (iii) sewage liquid is a chemically aggressive medium. Therefore, the sampler components should not come into contact with it during the sampling process;

[0015] (iv) energy saving. Since the sampler is located in a hard-to-reach place and must operate autonomously for a long time without replacing batteries, it must consume a small amount of energy; (v) the sampler must be controlled remotely via a wireless communication channel with a high degree of noise immunity;

[0016] (vi) the power supply must be autonomous; (vii) the liquid sampling cylinder must be hermetically sealed to prevent evaporation of the volatile components of the aqueous solution.

[0017] The specified requirements are achieved by using a sewer sampler comprising a sealed housing, a radio frequency transceiver, a microcontroller, a motor power supply control unit, a motor, a peristaltic pump, a filter, a tank, a capacitive tank filling sensor, a power supply unit, a check valve, a reed switch sensor, two galvanic isolators, a hose for collecting a sample, a hose-pipe for monitoring the tank filling, wherein the output of the radio frequency transceiver is connected to the information input of the microcontroller, the output of the reed switch sensor is connected to the input for turning on the motor in the reverse direction of the motor power supply control unit, the output of the motor forward stroke control of the motor power supply control unit is connected to the input for starting the forward stroke of the motor and to the input of the capacitive tank filling sensor, the output of which is connected through the first galvanic isolator to the control input of the microcontroller,the control output of the microcontroller is connected via a second galvanic to the motor control input of the motor power control unit, the information output of the microcontroller is connected to the information input of the radio frequency transceiver, the motor output is connected to the control input of the peristaltic pump, the filter is connected via a sample collection hose to the input of the pump, the output of which is connected via a sample collection hose to a container, the output of which is connected via a hose-pipe for monitoring the filling of the container to a check valve.

[0018] In one embodiment of the sampler, galvanic isolation is implemented in the form of an optocoupler.

[0019] In one embodiment of the sampler, the container is designed as a sealed cylinder. In one embodiment of the sampler, the motor power control unit is designed as a bridge circuit.

[0020] In one embodiment of the sampler, the bridge circuit is implemented using field-effect transistors.

[0021] In one embodiment of the sampler, the bridge circuit is implemented using bipolar transistors.

[0022] In one embodiment of the sampler, the bridge circuit is implemented using a relay.

[0023] In one embodiment of the sampler, the galvanic isolation is implemented in the form of a transformer.

[0024] Brief description of the drawings

[0025] Fig. 1 shows the structural diagram of the device.

[0026] Fig. 2 shows the structural diagram of the bridge circuit.

[0027] Fig. 3 shows an example of the implementation of block 3 in the form of a bridge circuit on 4 field-effect transistors and the connection of block 3 to galvanic isolators U1 and U2. Fig. 4 shows an option for placing the device in a sealed case and an option for fastening the case using an external bolt.

[0028] The sampler contains:

[0029] 1. Radio frequency transceiver

[0030] 2. Microcontroller

[0031] 3. Motor power control unit

[0032] 4. Motor 5. Peristaltic pump

[0033] 6. Filter

[0034] 7. Capacity (5L cylinder)

[0035] 8. Capacitive tank filling sensor

[0036] 9. Power supply

[0037] 10. Check valve

[0038] 11. Reed switch,

[0039] 12. sample collection hose

[0040] 13. Hose-branch for monitoring the filling level of the tank. The following symbols are shown in Fig. 1:

[0041] U 1, U2 — galvanic isolation (implemented on optocouplers) 5 1 — hose for sampling

[0042] 52 — hose-branch for monitoring the filling of the tank PH — straight stroke

[0043] R — reverse

[0044] QI, Q2, Q3, Q4 are switches implemented using field-effect transistors. Fig. 4 shows:

[0045] 14 - body

[0046] 15 - bolt

[0047] 16- nut

[0048] 17 - washer

[0049] 18 - sealing rubber.b

[0050] Implementation of the invention

[0051] The proposed sampler has small dimensions, so it can be easily moved and placed in a sewer well.

[0052] The device is controlled via a wireless communication channel with a high degree of interference immunity.

[0053] The sampler collects liquid with a density of approximately 1 g / cm³ to a height of no more than 2 m, with a volume of 5 liters. Lifting this amount of liquid, weighing approximately 5 kg, requires an energy expenditure of no more than E = mgh = 98 J. Taking into account all losses, a battery with an energy capacity of at least 2000 V*C is required for one sample collection. 12V*5 Ah batteries have an energy capacity of 216,000 V*C and, therefore, can be used for long periods. These batteries are lightweight and compact. The entire electrical circuit is coated with a protective insulating varnish.

[0054] The tightness of the housing, along with the varnish coating, prevents charges from draining from the battery terminals during long-term operation.

[0055] A sewer sampler is part of a larger wastewater environmental monitoring system, which includes sensors that analyze hazardous substances in sewer streams. Therefore, the sampler must sample wastewater at a specific time upon an external command. Highly interference-resistant radio communication is used to transmit the sampling command and receive information about the sampling completion. This is necessary because the transmitter (receiver) is located in a sewer manhole, where it is partially shielded by soil.

[0056] The sewage sampler contains two galvanic isolation modules, U1 and U2. This isolation is necessary because the control unit and motor are powered by different voltages. In the event of a breakdown or short circuit in the motor circuit, a higher voltage could damage the control unit and radio module. Furthermore, when wastewater is sampled and flows through hose S1, static electricity can accumulate, creating interference in the motor circuit. Without galvanic isolation, this could lead to incorrect operation of the microcontroller. Control unit (3) sets three motor states: motor stationary, motor running in forward direction, and motor set to reverse rotation.

[0057] The latter is necessary to drain the remaining wastewater from hose S1 after collecting it. Thus, during a new liquid collection, the wastewater from the previous collection does not get into the cylinder (7). The motor (4) is connected to a peristaltic pump (5). This type of pump does not come into contact with the liquid it pumps, which satisfies point (iii) of the technical requirements. At the end of hose S1 there is a filter (6) preventing solid particles from getting into hose S1. Cylinder (7) is equipped with branch pipe S2 (short hose), on which tank filling sensor (8) is installed. Cylinder (7) is hermetically sealed to prevent the trapped impurities from evaporating too quickly. For this purpose, drain hose S2 is equipped with a check valve (10). There is a reed switch sensor (11), with the help of which the motor reverser is started. The use of the reed switch sensor inside the housing ensures the latter’s hermeticity. The entire system is powered by an autonomous power supply unit (9).

[0058] The sampler works as follows.

[0059] A signal received via the communication line gives a command to collect a sample. This signal is received by the radio module (1) and then processed by the microcontroller (2), which, via galvanic isolation U2, transfers control to the unit (3), which turns on the pump in the forward direction and supplies power to the capacitive sensor (8). Since a peristaltic pump is used, in the pumping mode, liquid directly enters the cylinder (7) through hose S1 without contacting the sampler units. When the container is completely filled, liquid begins to pour out of the container (7) through an additional branch pipe (hose S2). The capacitive sensor (8) located on the branch pipe is triggered, the signal from which is sent via galvanic isolation U1 to the microcontroller (2). The microcontroller (2) via galvanic isolation U2 transmits a command to the power control unit (3), which stops the motor (4), disconnects the power supply to the capacitive sensor (8) and sends a signal to the transmitter (1). The transmitter (1) reports via radio that the tank is full.Since the peristaltic pump constantly compresses hose S1, wastewater remains in the S1 hose after the liquid is pumped into the cylinder, which must be drained back into the sewer. This is accomplished by using the motor's reverse mode. The motor's reverse mode (4) is started and stopped using a reed switch (11). The liquid in the short hose S2 flows out by gravity after the cylinder is removed. After hoses S1 and S2 are emptied, the pump is turned off, and the operator installs a new cylinder (7). The entire system is ready for a new sample collection.

[0060] The power control unit is implemented by a bridge H-circuit with 4 keys (Fig.

[0061] 2).

[0062] Galvanic isolation can be achieved in two ways: using a transformer or an optocoupler. Using a transformer requires a DC-to-AC converter before it, and a rectifier after the transformer. This not only complicates the circuit, but also reduces its reliability and increases power consumption. Using an optocoupler makes the circuit more reliable and consumes less power. Relays, bipolar transistors, and field-effect transistors can be used as switches. When switched on and off, relay contacts burn out, significantly reducing reliability. Bipolar transistors become very hot in open-switch mode, increasing power consumption and reducing circuit reliability. Field-effect transistors are the optimal choice.

[0063] Below is a specific diagram (see Fig. 3) which is optimal for a sewer sampler.

[0064] The power control unit (3) is implemented by a bridge circuit on 4 field-effect transistors. A voltage of 12 V is supplied from the battery to the connector J2. In the standby state, transistors Q1 and Q3 are closed, because the potentials of their gates are pulled up to the potentials of the sources through resistors R2 and R3; and vice versa, transistors Q2 and Q4 are open, because a positive voltage is applied to the gates relative to the potentials of their sources. As a result, zero potential is created at the terminals of connector J3, which supplies voltage to the motor (4), and the motor does not work. Power is not supplied to the capacitive sensor (8). When a signal is received from the microcontroller, which is connected to pin C1, a logical one appears - the voltage on the optocoupler U2. The LED lights up, opening the transistor, and, thus, the optocoupler U2 short-circuits the gates of transistors Q1 and Q2 to ground. Transistor Q2 closes, and transistor Q1 opens. As a result, a voltage of +12V appears at pin 1 of connector J3.The motor (4) is switched on in the forward direction, and the pump (5) begins to pump liquid into the tank (7) through the hose S1. At the same time, the power supply to the capacitive sensor (8) is switched on.

[0065] When the tank (7) is filled, liquid begins to flow through the S2 connection. The capacitive sensor (8) is triggered, and zero potential appears at the Out output of the J5 connector. Current begins to flow through the LED of the optocoupler U1. The diode's light signal opens the optocoupler transistor, and the potential of the C2 terminal of the L connector is pulled to ground. This signals the microcontroller to remove a logical high from the C1 terminal, which opens the transistor of the optocoupler U2. As a result, the Q1 transistor closes, and the Q2 transistor opens. The motor control unit (3) returns to its initial state—standby mode.

[0066] To activate reverse, the reed switch (11) closes pins 1 and 2 of connector J4. Resistor R4 shorts the gates of transistors Q3 and Q4 to ground, causing Q4 to close and Q3 to open. As a result, a positive voltage of +12V is applied to pin 2 of connector J3, causing the motor to rotate in the opposite direction (reverse).

[0067] The housing is sealed by connecting the housing parts using a tongue-and-groove design with a soft rubber seal (see Fig. 4). To prevent holes in the housing, the bolt ties are located outside and installed around the housing perimeter. The hoses are mounted on brass tubes and sealed with ties. The brass tube itself is installed into the housing with rubber seals using nuts. The use of a sealed housing, peristaltic pump, and reed switch prevents contact of the sampler components with aggressive environments, thereby increasing the reliability and service life of the unit. The use of a high-tech semiconductor base, along with the above-described circuit, results in low power consumption, allowing the device to be used for long periods of time in autonomous mode without replacing batteries.

[0068] A nozzle with a capacitive sensor allows for monitoring the cylinder's fill level and shutting off the motor when the tank is full. Using the reverse mode allows for the sampler's system to drain any remaining sample, ensuring a cleaner sample. This undoubtedly impacts the accuracy of subsequent chemical analysis of wastewater. Sewage channels accumulate large quantities of methane, hydrogen sulfide, and other harmful and toxic substances, making it sometimes impossible (or extremely difficult) for an operator to be present. The proposed development allows for autonomous sampling without the need for an on-site operator. The command to collect a sample is sent from the control center via radio at any time.

Claims

Invention formula 1. A sewage sampler comprising a sealed housing, a radio frequency transceiver, a microcontroller, a motor power supply control unit, a motor, a peristaltic pump, a filter, a container, a capacitive tank filling sensor, a power supply unit, a check valve, a reed switch sensor, two galvanic isolators, a hose for collecting a sample, a hose-pipe for monitoring the tank filling, wherein the output of the radio frequency transceiver is connected to the information input of the microcontroller, the output of the reed switch sensor is connected to the input for turning on the motor in the reverse direction of the motor power supply control unit, the output for controlling the forward running of the motor of the motor power supply control unit is connected to the input for starting the forward running of the motor and to the input of the capacitive tank filling sensor, the output of which is connected through the first galvanic to the control input of the microcontroller, the control output of the microcontroller is connected through the second galvanic to the motor control input of the motor power supply control unit,the microcontroller's information output is connected to the information input of the radio frequency transceiver, the motor's output is connected to the control input of the peristaltic pump, the filter is connected via a sample collection hose to the pump's input, the output of which is connected via a sample collection hose to a container, the output of which is connected via a hose-pipe for monitoring the filling of the container to a check valve.

2. A sampler according to item 1, characterized in that the galvanic isolation is implemented in the form of an optocoupler.

3. The sampler according to item 1, characterized in that the container is made in the form of a sealed cylinder.

4. The sampler according to item 1, characterized in that the motor power supply control unit is made in the form of a bridge circuit.

5. A sampler according to item 4, characterized in that the bridge circuit is implemented using field-effect transistors.

6. A sampler according to item 4, characterized in that the bridge circuit is implemented using bipolar transistors.

7. A sampler according to item 4, characterized in that the bridge circuit is implemented using a relay.

8. A sampler according to item 1, characterized in that the galvanic isolation is made in the form of a transformer.

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