WO2018066008A1

WO2018066008A1 - System for reducing costs of mechanical dewatering of sludge

Info

Publication number: WO2018066008A1
Application number: PCT/IT2016/000231
Authority: WO
Inventors: Luciano LISANTI
Original assignee: Lisanti Luciano
Priority date: 2016-10-06
Filing date: 2016-10-06
Publication date: 2018-04-12

Abstract

The system object of the patent, extremely simple, reliable and functional, at the service of any centrifugal extractor or belt press or screw press or other similar machine, allows to evaluate and display, in real time, on a display the following parameters: • mass flow of dewatered sludge. Concentration in dry material of the dewatered sludge. Costs of dehydration on an hourly basis or according to the flow of the sludge product or according to the flow of the sludge to be dewatered. The system allows to vary the quality of the sludge to be dewatered and the operating parameters (flow of sludge to be dewatered, type and extent of the polyelectrolyte, mode of operation of the machine) to view in real time the effect of changes in the scope and concentration in dry material of the dehydrated sludge and the specific costs of treatment in order to optimize the yields of the process and, consequently, the management costs.

Description

SYSTEM FOR REDUCING COSTS OF MECHANICAL DEWATERING

OF SLUDGE

DESCRIPTION

1. INTRODUCTION

The solids concentration in dry material in dewatered sludge is normally monitored, taking samples of sludge, and by them drying and weighing. The analytical determination of the concentration of the dewatered sludge has the disadvantage that the result is available only after a certain time after sample collection. To control the process of dehydration so as to operate the corrective actions using the laboratory data, it must be assumed that the process operating conditions (quality, concentration and flow rate of sludge, specific dosage of polyelectrolyte, exercise regime extractor) do not change since the sample was taken to the availability of analytical outcome.

Another drawback about the determination in the laboratory is that the process takes a lot of time to plant's technicians and to laboratory's staff. In current installations of dehydration, the scope of the dewatered sludge is also evaluated as the average value in the range of time required for the filling of the body of accumulation to be subjected to weighing before transport to disposal. The system object of this patent, based on a material balance on the flow in the input and output and the material balance of the suspended solids present in the flow, allows the real-time reading of the following data:

• concentration in dry material of dewatered sludge %

• mass flow of dewatered sludge Kg h

• mass flow of solids in the dry sludge KgSS/h For the foregoing reasons, the solution developed by the writer and valid for the technical, engineering and economic aspects, being based on a material balance, allows the real-time measurement of the three parameters listed above with a very simple and reliable plant, and with a modest cost. The possibility to know in real time the values listed above, also allows to know a real-time detailed estimate of the costs of dehydration of the mud, varying the management parameters, namely:

• feed flow rate of the machine

• specific dosage of polyelectrolyte

• modification of the operating parameters of machine

• type of polyelectrolyte

On that latter point, the ability to immediately determine the yields of the process used varing the product (at the same dose) allows the optimal choice of the chemical to buy. The method described below can be applied to a system of centrifugation, and dehydration of belt press and with screw press (generally called "machine")

2. DESCRIPTION OF THE PATENT'S OBJECT

As mentioned above, the proposed methodology allows the achievement of the following two purposes as further described in the following paragraphs:

2.1 Dosage of the chemical (for example, polyelectrolyte) proportional to the mass flow of the dry matter in the entrance to the machine

2.2 Flow measurement and dry matter's concentration of dewatered sludge

2.3 Detailed estimates of dehydration's specific costs

The components of the described system may be installed outside or otherwise inside the centrifuge in order to provide a complete machine that performs all the functions described above. 2.1 CHEMICAL'S CHECKED DETERMINATION

The chemicals's dosage (for example, polyelectrolyte) (or possibly other chemicals) is normally adjusted according to condition of the dry matter present in dewatered sludge. The concentration in dry matter of sludge to be dewatered may vary during operation of section sludge dewatering. With the proposed plant, having available dosing pumps of proportional type, setting the ratio chemical/SS, the dose remains constant during machine's whole operation.

2.1 FLOW RATE/CONCENTRATION OF DEHYDRATED SLUDGE

The functional parameters which influence the yields of the process are the following:

• Quality of sludge to be dewatered

• Flow rate of the sludge to be dewatered

• Concentration in dry solids to be dewatered

• Type of chemical product (for example polyelectrolyte) dosed

• Dosing of chemicals (for example polyelectrolyte)

• Operating conditions of the machine

It is assumed that it does not exist a commercially instrumentation able to determine in real time the flow rate and concentration in dry matter of dehydrated sludge in order to optimize the above parameters.

The possibility of monitoring in real time the concentration of dehydrated sludge can improve machines's performance varying the flow rate of the sludge and the dosage of chemicals with the instrumentation to measuring the following parameters:

• flow rate of the sludge for supplying the machine

• concentration of sludge to be dehydrated

• rate of the chemical product (for example polyelectrolyte)

• water flow centrifugation • concentration of suspended solids in the residual process water

All of the above functional parameters will be adjusted so as to optimize the process in terms of operating costs and residual water's quality.

Instruments's output will be sent to the control panel of the machine to report the possible need for changing the operating parameters

2.2 SPECIFIC COSTS OF DEHYDRATION

The main items that determine the cost of dewatering of sludge, net of personnel's cost and those relating to the interventions of ordinary and extraordinary maintenance of the machine (significantly reduced with the optimization process of the proposed methodology) are the following:

a) chemicals's cost (for example polyelectrolyte): the increased specific doses of chemical product (for example, polyelectrolyte) does not always lead to improved yield of the process, balancing the higher cost of the product.

b) electricity's cost consumed by the machine: energy costs are a major item of expenditure

c) the cost of transportation and disposal of dewatered sludge: the cost of transportation and disposal of dewatered sludge is definitely the voice that mainly affects the costs of managing the sludge line of a plant

Dehydration's costs will refer to the number of daily hours of operation for the treatment of the anticipated volume of sludge to be dewatered or to the flow of dry matter of the sludge.

3. CONCLUSIONS

It is believed that the proposals may lead to the optimization of the management of the dehydration section of sludge in terms of:

• Selection of the best chemical product (for example polyelectrolyte) to be used in the sludge's conditioning • Chemicals's constant dosage (for example polyelectrolyte) based on the solids to be conditioned

• Reduction of operating costs related to the consumption of chemical, energy costs and those relating to the transport and disposal of dewatered sludge

• Lower costs of ordinary and extraordinary maintenance machine resulting in the best operating conditions tested in real time

Claims

SYSTEM FOR REDUCING COSTS OF MECHANICAL DEWATERING OF SLUDGE CLAIMS

1. System in service of a machine for the dehydration of sludge(decanter, belt press or screw press) characterized by the following components:

a) measurer of the flow rate of the sludge in the feeding of the extractor b) measurer of the flow rate of the chemical

c) measurer of the flow rate of the washing water

d) measurer of the concentration of suspended solids in the residual water of the process

e) measurer of the flow rate of the residual water of the process

f) measurer of the dry matter's concentration of the thickened sludge to be dehydrated

g) computer complete with LCD terminal for the management, control and display of the output of above mentioned instruments

2. System according to claim 1. characterized in that the instrument mentioned in a) is installed on the pipe which connects the feed pump of the machine and the dehydrator machine

3. System according to claim 1. characterized in that the instrument mentioned in b) is installed on the pipe connecting the outlet side of the dosing pump of the chemical and the dehydrator machine

4. System according to claim 1. characterized in that the instrument mentioned in c) is installed on the pipe which connects the water plant and the washing plant of the belt press or the screw press that require industrial water for operation (not required for centrifugal extractors)

5. System according to claim 1. characterized in that the instrument mentioned in d) is installed in the water container of result of dehydration

6. System according to claim 1. characterized in that the instrument mentioned in e) is installed on the discharge piping of the water container of result of dehydration

7. System as claimed in claim 1. characterized in that the meter mentioned in f) is installed on the pipe which connects the feed pump of the machine and the dehydrator machine

8. System according to claim 1. mentioned in g), characterized in that the computer in question acquires:

• the default values set by the operator (unit costs of electricity, chemical, transportation and disposal of dewatered sludge)

• the output of the instruments mentioned in a) -b) -c) -d) -e) -f)

processes these values and gives as a output on the display the dehydration costs (electricity, chemicals, transportation and disposal of dewatered sludge).