Model selection method of sewage lifting equipment

Abstract

The invention belongs to the technical field of sewage treatment, and relates to a type selection method of sewage lifting equipment, which comprises the following steps of: 1, determining an application scene or a building type of a sewage lifter; 2, determining the sewage discharge amount; 3, determining the type of the water pump; 4, confirming the water pump lift; 5, the volume of a box body of the sewage lifter is confirmed, the volume of the box body of the sewage lifter comprises the effective volume of the box body, and the model selection of the effective volume of the box body of the sewage lifter needs to meet the following formula: # imgabs0 #, V represents the effective volume of the sewage lifter, Q1 represents the input flow, and Q2 represents the output flow; t0 represents water storage time, and k1 represents a de-dimensionalization parameter. According to the model selection method of the sewage lifting equipment, the loss of the equipment can be reduced, the service life of the equipment can be prolonged, stable operation of the system can be ensured, and the maintenance cost can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment and relates to a method for selecting sewage lifting equipment. Background Art

[0002] Currently, market regulations vary regarding selection factors such as sewage lifting equipment capacity and pump parameters. The number of starts for sewage pumps is clearly defined across different companies and application scenarios: Beijing Huanzhi Environmental Protection Equipment Co., Ltd., Shandong Shuanglun Co., Ltd., and Shanghai Panda Machinery (Group) Co., Ltd. stipulate a maximum of 12 starts per hour; Beijing Jingmingqin Engineering Technology Development Co., Ltd. sets a maximum of 15 starts per hour; and Zenit Pumps (China) Co., Ltd. sets a maximum of 45 starts for internal and 40 starts for external water systems. These regulations reflect the differences in design and application between companies.

[0003] Regarding the liquid level control of ordinary sewage lifting devices, the pump start level is set at 200mm from the top of the water tank, the pump stop level is 250mm from the bottom, the super-high / alarm level is 150mm from the top, and the super-low water level is 150mm from the bottom. This setting ensures the stable operation of the sewage pump within the normal operating range and avoids equipment failure or safety hazards caused by abnormal water levels. Beijing Huanzhi Environmental Protection Equipment Co., Ltd. and Shanghai Panda Machinery (Group) Co., Ltd. both describe the working mechanism of the backwash sewage lift in detail: when the sewage reaches the pump start level 200mm from the top of the water tank, the water pump starts, solids are discharged with the water flow, and part of the water flows into the inlet to flush the bottom of the water tank; when the water level drops to the pump stop level (250mm or 100mm from the bottom), the equipment stops operating; if the water level continues to rise to the alarm level (150mm from the top), an alarm signal is issued. This process ensures the effective operation and safety of the system.

[0004] Beijing Jingmingqin Engineering Technology Development Co., Ltd.'s equipment requires specific requirements: the pump start level must be 200mm from the top of the tank, the pump stop level must be 100mm above the pump outlet, and the alarm level must be 100mm from the top. Furthermore, the height difference between the sewage inlet and the incoming sewage pipe must be at least 500mm. These specific parameters are designed to take into account the specific needs of actual application scenarios, ensuring safe and reliable operation of the equipment.

[0005] In summary, different companies have their own standards and characteristics regarding the number of starts, liquid level control, and operating mechanisms of sewage pumps. These differences reflect the different considerations of each company in technical design and application scenarios. However, existing solutions all set parameters based on experience, and there is no design solution that optimizes the volume and start-stop frequency of sewage lifting equipment for different operating conditions to adapt to the different operating conditions and customer needs of the equipment. In the future, with technological advancements and changes in market demand, sewage lifting equipment will develop in a more refined and intelligent direction. Reasonable equipment and operating parameters are important factors in the market competitiveness of sewage lifting equipment.

[0006] The shortcomings of the current sewage lift selection are:

[0007] When selecting a sewage pump on the market, the primary focus is on whether the flow rate and head meet the requirements, but the number of pump starts and volume factors are rarely considered. In fact, the number of pump starts is closely related to the volume of the equipment: if the equipment volume is too small when selecting, the sewage level will quickly reach the starting level, and the pump will immediately start to drain. However, due to the limited volume, shortly after drainage is completed, the new incoming water will quickly reach the specified level, forcing the pump to start again, resulting in frequent starts. This frequent start-stop not only increases wear on the pump and shortens its service life, but can also lead to increased electricity consumption and higher operating costs.

[0008] On the other hand, selecting equipment with too large a volume may reduce the pump's startup frequency, but it can also create other problems. For example, prolonged storage of incoming water within the tank can lead to fermentation, creating odors and negatively impacting the surrounding environment. Furthermore, pumps that remain idle for extended periods can malfunction due to lack of lubrication, further impacting the equipment's proper operation. Summary of the Invention

[0009] In view of the deficiencies of the prior art, the present invention provides a method for selecting sewage lifting equipment, which can reduce equipment loss, extend its service life, ensure stable operation of the system, and reduce maintenance costs.

[0010] In order to solve the above technical problems, the purpose of the present invention is achieved through the following technical solutions:

[0011] A method for selecting sewage lifting equipment comprises the following steps:

[0012] 1. Clarify the application scenario or building type of the sewage lift;

[0013] 2. Determine the amount of sewage discharged;

[0014] 3. Determine the type of water pump;

[0015] 4. Confirm the pump head;

[0016] 5. Confirm the volume of the sewage lift tank. The volume of the sewage lift tank includes the effective volume of the tank. The selection of the effective volume of the sewage lift tank must meet the following formula:

[0017]

[0018] Wherein, V represents the effective volume of the sewage lift, Q1 represents the input flow, Q2 represents the output flow; t0 represents the water storage time, and k1 represents the dimensionless parameter;

[0019] Specifically, the selection of the effective volume of the sewage lift is limited by the number of times the submersible sewage pump is started. In order to avoid frequent starting of the submersible sewage pump, the number of starts of the sewage pump has a maximum limit of N0; the selection of the effective volume of the sewage lift is limited by the storage time of the sewage in the equipment, because the sewage will emit odor if it stays in the equipment for too long, affecting the customer experience.

[0020] In the above-mentioned method for selecting a sewage lifting equipment, the selection of the output flow rate must satisfy the following formula:

[0021]

[0022] Wherein, D represents the outlet pipe diameter, v0 represents the minimum flow rate of pipeline self-cleaning, and c represents the load rate;

[0023] Specifically, the selection of the output flow is limited by the requirement of the minimum flow for pipeline self-cleaning to ensure that the pipeline is not blocked; the selection of the output flow is limited by the load rate, because the water pump will generate heat during operation, and the submersible sewage pump cannot operate continuously for a long time due to its specific working mechanism, and there is a load rate c.

[0024] In the above-mentioned method for selecting sewage lifting equipment, a parameter M for judging equipment reliability selection is set, and the judgment value of M is calculated by the following equation:

[0025] M=k2(t1+t2)*N*V b ,

[0026] Among them, k2 and b are both positive correlation coefficients, t1 represents the time taken for the incoming water to reach the starting water level of the pump, t2 represents the time taken for the output sewage to reach the stopping water level of the pump, and N represents the number of times the equipment is started and stopped.

[0027] Specifically, the selection of equipment reliability is limited by the sewage retention time, the number of pump starts, and the effective volume. When the other parameters meet the requirements, the equipment reliability selection is only limited by time, that is, the evaluation value of M is determined by the following equation:

[0028] M=V b ;

[0029] The smaller the effective volume, the higher the equipment reliability and the lower the cost.

[0030] Furthermore, in the above-mentioned method for selecting sewage lifting equipment, since the effective volume is the minimum when the output flow Q2 reaches the minimum allowable value, when the equipment reliability is optimal, the effective volume is the minimum and the output flow is the minimum.

[0031] In the above-mentioned method for selecting sewage lifting equipment, in step one, the number of water pumps is selected according to the application scenario or building type of the sewage lifter, including single, double or multiple water pumps.

[0032] In the above-mentioned method for selecting sewage lifting equipment, in step 2, according to the drainage flow formula in the building water supply and drainage design standard GB50015, the calculation formula corresponding to the building type is selected to calculate the sewage discharge volume; the input flow is selected according to the sewage discharge volume, and the output flow is selected according to the input flow, and the output flow must be not less than the input flow.

[0033] In the above-mentioned method for selecting sewage lifting equipment, in step three, the water pump type is selected according to the nature of the sewage, including a cutting pump, a large-channel submersible sewage pump, a semi-open impeller pump, an air-cooled pump or a water-cooled pump.

[0034] In the above-mentioned method for selecting sewage lifting equipment, in step four, the water pump head is selected based on the pipeline resistance and resistance loss during the municipal pipeline transportation process.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The present invention provides a method for selecting sewage lifting equipment, and proposes five steps to improve the sewage lift selection process, including clarifying the application scenario or building type of the sewage lift, clarifying the sewage discharge volume, confirming the water pump type, confirming the water pump head, and confirming the sewage lift box volume. It also supplements and optimizes the lack of selection methods for sewage lift volume and water pump start-up times on the market. The appropriate volume and start-stop times are selected through factors such as sewage lift transportation, pipeline anti-blocking requirements, pump operation heat characteristics, and impact on the outside world. This can reduce costs while reducing the negative impact of temporary sewage on the outside world, and improve the safety and reliability of the water pump.

[0037] 2. When selecting a sewage pump, the present invention comprehensively considers multiple factors, including flow rate, head, volume, and the number of times the pump is started. The effective volume of the sewage pump is determined in a quantitative manner. Furthermore, the optimal effective volume can be determined to achieve the best equipment reliability. The rational selection provided by the present invention can not only reduce equipment losses and extend its service life, but also ensure stable operation of the system and reduce maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a flow chart of the present invention; DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to specific embodiments of the present invention. Figure 1 :

[0040] In this embodiment, the selection of sewage lifting equipment refers to user needs, including sewage flow, sewage characteristics, equipment installation space, sewage discharge height requirements, equipment price, service life and subsequent maintenance, etc. In order to select the best model suitable for the user, it is necessary to match the multiple parameters mentioned above. This embodiment will gradually deepen according to the various factors proposed above, and optimize the two parameters of equipment volume and start and stop times according to relevant requirements to select the most suitable sewage lifting equipment model.

[0041] Compare with Figure 1 , the specific implementation steps of the selection plan are as follows:

[0042] 1. Identify the application scenario or building type of the sewage lift and select the number of water pumps. The specific selection implementation method is: by clarifying the application scenario or building type of the sewage lift, such as a single-family flat, a multi-story villa, a small commercial building, a school, a hotel, or an industrial enterprise living room, a public bathroom, a gymnasium and other buildings, it can be roughly determined whether the number of water pumps used is single or two or more. Under normal circumstances, in an environment with low personnel flow and infrequent water demand, a single water pump is preferred. On the contrary, when the flow of personnel is dense and the water demand is large, two or more water pumps are needed to discharge the sewage in time. The alternating use of two pumps can prevent a single water pump from running for too long and the motor from overheating and causing damage. On the other hand, when the amount of sewage water is large, the two water pumps can be started at the same time to discharge the sewage in time. When selecting the flow rate of the water pump, it needs to be larger than the drainage flow rate or just right. If it is too small, when the water flow is too large, the sewage will not be discharged in time, resulting in sewage overflow and polluting the environment.

[0043] 2. Determine the sewage discharge volume and select the pump type based on its input and output flow rates. The specific selection method is:

[0044] According to the drainage flow formula in the building water supply and drainage design standard GB50015, select the calculation formula corresponding to the building type for estimation:

[0045] 1. The design flow rate of domestic drainage pipes in buildings such as residences, dormitories (with toilets in the rooms), hotels, guesthouses, hotels, hotel-style apartments, hospitals, sanatoriums, kindergartens, retirement homes, office buildings, shopping malls, libraries, bookstores, passenger transport centers, airport terminals, convention and exhibition centers, primary and secondary school literature buildings, canteens or business restaurants shall be calculated according to the following formula:

[0046]

[0047] Where q p ——Calculate the design drainage flow rate of the pipe section (L / s);

[0048] Np - the total equivalent drainage volume of sanitary appliances in the calculated pipe section; a coefficient determined according to the purpose of the building, determined according to Table 1;

[0049] q max ——Calculate the drainage flow rate (L / s) of the largest sanitary appliance on the pipe section.

[0050] Table 1 Coefficient values according to building use

[0051]

[0052] Note: When the calculated flow rate value is greater than the cumulative value of the drainage flow of sanitary appliances on the pipe section, it should be calculated according to the cumulative value of the drainage flow of sanitary appliances.

[0053] The design flow rate per second of domestic drainage pipes in buildings such as dormitories (with public washrooms), living rooms of industrial enterprises, public bathrooms, laundries, kitchens of staff canteens or business restaurants, laboratories, theaters, and stadiums (stadiums) shall be calculated according to the following formula:

[0054] Q p =∑q p0 n0b p

[0055] Where q p0 --Drainage flow rate of a sanitary appliance of the same type (L / s);

[0056] n o --Number of sanitary appliances of the same type;

[0057] b p --The percentage of simultaneous drainage of sanitary appliances and the percentage of simultaneous drainage assisted by flushing water should be calculated as 12%.

[0058] Note: When the calculated value is less than the drainage flow of one toilet, it should be calculated based on the drainage flow of one toilet.

[0059] The actual drainage flow rate is calculated using the above two formulas. Furthermore, it is necessary to consider the drainage volume of the equipment under the most unfavorable conditions, that is, when all water-using appliances are operating at full load. At this time, the drainage is the largest and most unfavorable.

[0060] The above two points can be used to preliminarily estimate the sewage flow rate, that is, the input flow rate of the sewage lifting equipment, and the water pump output flow rate must be greater than or equal to this value.

[0061] 3. Confirm the type of water pump. According to the first two steps, the total drainage flow rate and the number of supporting water pumps required and the corresponding flow rate can be preliminarily determined. Then, the type of water pump can be selected based on the usage of the equipment. The type of water pump needs to consider whether the sewage contains materials that need to be cut. For example, large pieces of material require a water pump with a cutting impeller. If the water contains a lot of small particles, a water pump with a large channel or a semi-open impeller can be used to avoid the risk of blockage. In addition, the equipment installation space needs to be considered to decide whether the water pump is air-cooled or water-cooled. If the water pump space is narrow and needs to run for a long time, wet installation using water cooling can quickly cool the motor in the sewage. If the equipment cannot be placed in a sewage environment, the water pump needs to be separated from the sewage and installed dryly in an air-circulating place. An air-cooled water pump or a self-circulating cooling water pump can be used. The self-circulating cooling water pump produces less noise than the air-cooled water pump and has less impact on the surrounding area.

[0062] 4. Confirm the pump head. As an intermediate role in sewage collection and discharge, sewage lifting equipment needs to lift sewage to the municipal pipe network, so it needs to have a certain head to overcome the pipe resistance. In the process of transporting sewage to the municipal pipe network, in addition to lifting the sewage to the height required by the municipal pipe network, the valves and pipe fittings (such as tees, elbows, large and small reducers, etc.) passed by the equipment during transportation will produce a certain resistance loss. At the same time, the neck pipe also needs to overcome resistance loss when it is transmitted to the municipal pipe network. Different pipe fittings have different resistance coefficients. When calculating, it is necessary to make a prediction based on the actual installation requirements to determine the pump head parameters.

[0063] 5. Confirm the volume of the sewage lift tank. The tank specifications often include the effective volume of the tank. Under normal circumstances, the maximum number of pump starts per hour and the effective volume determine the maximum drainage volume. The pump start level of most equipment is 1 / 3 of the tank or 200mm from the top of the tank. The effective volume of the tank multiplied by the maximum number of starts per hour of the water pump (double pumps need to be multiplied by 2) is the maximum amount of water that the equipment can handle. Compare this number with the most unfavorable drainage volume: if it is greater, the most unfavorable drainage volume is appropriate; if it is less, the tank volume needs to be reselected. Different water pumps have different number of starts per hour. The national standard stipulates that the number of starts per hour for water pumps is 20 times. When the equipment uses two water pumps, it can be 40 times. This is because the frequent starting of the water pump causes the motor to generate a lot of heat. If it is not cooled in time, the motor will be damaged, and in severe cases, the water pump will be damaged.

[0064] Sewage pumps typically have alarm levels. When the water level reaches the alarm level, the controller sends a signal, alerting the user to promptly check the equipment's operation. Therefore, the selected volume of the equipment must be larger than the effective volume. Furthermore, the water outlet diameter must meet self-cleaning requirements. This is because an overly large outlet diameter can result in a low flow rate, which can cause sedimentation in the pipe and reduce the effective volume. Therefore, the outlet diameter must be calibrated to meet the minimum flow rate requirements for the current pipe diameter.

[0065] Some parameters can be determined according to the above steps, but there are still a few values that lack reference basis, especially the equipment volume and the number of times the water pump is started and stopped. Therefore, this application proposes to optimize the volume and inlet and outlet dimensions of the sewage lifting equipment based on the operating parameters under the equipment usage scenario, so as to reduce the equipment processing cost and the number of times the water pump is started and stopped.

[0066] The following parameters are set: input flow rate is Q1, effective volume of sewage lifting equipment is V, equipment output flow rate is Q2, outlet pipe diameter is D, minimum required flow rate for pipeline self-cleaning is v0, equipment start and stop times is N, rated start and stop times is N0, time for incoming water to reach the pump start level is t1, time for outgoing sewage to reach the pump stop level is t2, water storage time is t0, and load rate is c. Parameter optimization is performed according to the requirements, and the process is as follows:

[0067] 1. Considering the operating mechanism of sewage lifting equipment and the possibility of long-term uninterrupted sewage input, the output flow and input flow must meet the following conditions:

[0068] Q2 ≥ Q1;

[0069] 2. In order to ensure that the pipeline is not blocked, the flow rate requirements of the sewage transported in the pipeline must be met:

[0070]

[0071] 3. It is known that water pumps generate heat during operation. Due to their specific working mechanism, submersible sewage pumps cannot operate continuously for a long time. There is a load rate c, which must meet the following conditions:

[0072]

[0073] Among them, it is known Bring in:

[0074]

[0075] 4. If the sewage stays in the equipment for too long, it will emit odor and affect the customer experience. Therefore, the water storage time of the equipment cannot be too long. The following conditions must be met:

[0076] t1+t2≤t0,

[0077] Simplified, we get:

[0078]

[0079] 5. Considering the working mechanism of the submersible sewage pump, the number of starts cannot exceed the limit value N0, and the following equation must be satisfied:

[0080]

[0081] Where k1 is a dimensionless parameter, and the simplified relationship can be obtained:

[0082]

[0083] From the above 4 and 5 points, we can get:

[0084]

[0085] 6. Refer to the equipment and pump operating conditions, and set the evaluation standard parameter M to determine the equipment reliability. It is known that the shorter the sewage retention time, the better the customer experience, the fewer the number of starts, the higher the equipment reliability, and the smaller the effective volume, the lower the cost. Therefore, its evaluation value can be preliminarily calculated by the following equation:

[0086] M=k2(t1+t2)*N*V b ,

[0087] Among them, k2 and b are both positive correlation coefficients. When the sewage retention time and the number of startups meet the requirements, M and V b Related, simplifying it, we can get:

[0088] M=V b ,

[0089] Therefore, it can be preliminarily determined that, under the premise that other parameters meet the requirements, the smaller the effective volume, the higher the equipment reliability and the lower the cost.

[0090] According to the relationship It can be seen that when the output flow Q2 reaches the minimum allowable value, the effective volume V is the minimum value. It is known that Q2 must meet the following conditions:

[0091]

[0092] Through the above steps, the selected sewage lifting equipment model is the most suitable for the current application scenario. Not only does the water pump operate safely and smoothly, the box volume is appropriate, saving equipment costs and operating power consumption, but the impact on the surrounding environment can also be reduced to a reasonable range.

[0093] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for selecting sewage lifting equipment, characterized in that: The following steps are involved:

1. Clarify the application scenario or building type of the sewage lift; 2. Determine the amount of sewage discharged; 3. Determine the type of water pump; 4. Confirm the pump head; 5. Confirm the volume of the sewage lift tank. The volume of the sewage lift tank includes the effective volume of the tank. The selection of the effective volume of the sewage lift tank must meet the following formula: Wherein, V represents the effective volume of the sewage lift, Q1 represents the input flow, Q2 represents the output flow; t0 represents the water storage time, and k1 represents the dimensionless parameter.

2. The method for selecting sewage lifting equipment according to claim 1, characterized in that: The output flow selection must satisfy the following formula: Wherein, D represents the outlet pipe diameter, v0 represents the minimum flow rate for pipeline self-cleaning, and c represents the load rate.

3. The method for selecting sewage lifting equipment according to claim 2, characterized in that: The evaluation parameter M for equipment reliability selection is set, and the evaluation value of M is calculated by the following equation: M=k2(t1+t2)*N*V b , Among them, k2 and b are both positive correlation coefficients, t1 represents the time taken for the incoming water to reach the pump start water level, t2 represents the time taken for the output sewage to reach the pump stop water level, and N represents the number of times the equipment is started and stopped.

4. A method for selecting sewage lifting equipment according to claim 3, characterized in that: When the reliability of the equipment is optimally selected, the effective volume is minimized and the output flow rate is minimized.

5. The method for selecting sewage lifting equipment according to claim 1, characterized in that: In step one, the number of water pumps is selected based on the application scenario or building type of the sewage lift, including single, double or multiple pumps.

6. The method for selecting sewage lifting equipment according to claim 1, characterized in that: In step 2, according to the drainage flow formula in the building water supply and drainage design standard GB50015, select the calculation formula corresponding to the building type to calculate the sewage discharge volume; select the input flow according to the sewage discharge volume, and select the output flow according to the input flow, and the output flow must be no less than the input flow.

7. The method for selecting sewage lifting equipment according to claim 1, characterized in that: In step three, the water pump type is selected according to the nature of the sewage, including cutting pump, large channel submersible sewage pump, semi-open impeller pump, air-cooled pump or water-cooled pump.

8. The method for selecting sewage lifting equipment according to claim 1, characterized in that: In step 4, the water pump head is selected based on the pipeline resistance and resistance loss during the municipal pipeline transportation process.

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